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13.1
THE DESIGNING
OF ORDINARY
IRON HIGHWAY BRIDGES,
BY
J. A. L. WADDELL, C. E., B.A.Sc, Ma.E.,
'^"'■'^r^i'lT' ^'"^""'-'=''' "^'ANSAS CITV, MO.; ALSO ENGINEER IN CHARGE OF THE WESTERN 0FP1CK
OF THE IHOiNlX BRIDGE COMPANY AND THE PHCENIX IRON COMPANY; FORMERLY PROFESSOH
OF CIV.I. ENGINEERING IN THE IMPERIAL UNIVERSITY OF JAPAN MEMlfER OF ^hI
AMERICAN SOCIETY OF CIVIL ENGINEERS, AMERICAN SOCIETY OF MECHANIcIl
ENGINEERS, LA SOClfiTlt DES INofeNIEURS CIVILS, PARIS, RENSSELAER
SOCIETY OF ENGINEERS, ENGINEERS* CLUB OF PHILADEI PHIA
WESTERN SOCIETY Or KNGINEEHS. AND FNGINEERs' CLUB '
OF KANSAS l(. ASSOCIATE MEMlUiR OFIHE
INSTITUTION F CIVIL ENGINEERS, LONDON,
AND HONORARY MEMBEk OF THE
KOGAKU KYOKAI (JAPANESE
ENGINEERING SOCIETY).
FJFTH EDITION.
SECOND THOUSAND.
NEW YORK :
JOHN WILEY & SONS,
53 East Tenth Street.
1894.
Copyright, 1884,
By J. A. L. WADDELL.
1
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PREFACE.
This work is principally a compilation of the results of inve:tigations
made by the author during the last three years, and presented in a
number of papers to the various American engineering societies. Sev-
eral port.o.. of the book, including many of the tables, are new. as
th.s ,s the first systematic treatmeni. by the author, of bridges for cities
and manufacturing districts; the previous papers havmg dealt especially
w.th those for country roads. In ..aking this compilation, the author
has been governed by no blind adherence to what he has alrea'dy writ-
ten but as made changes wherever they have appeared to be advisable
One o the ch.ef objects of this work is to reduce the labor of iron
h.g way bndge designing to a minimum, for which purpose every thing
that cou d be so arranged has been tabulated. Not only are the exact
sues of h.p verticals joists, floor beams, beam hangers, lateral rods and
truts, portal rods and struts, vibration rods, intermediate struts, lattice
bars, stay plates, etc.. given for all practical cases, but also the most
economic d„.ensions of panels and trusses, and dead loads, so exact
ha by the,r use all necessity for a second trial is avoided. These
2^ .t IS hoped, will prove useful to those in the actual practice of
ndge des,gnu.g. enabling them to greatly reduce the time required
to make diagrams of stresses and sections and estimates of cost The
other^tables. although they do not give final result, should also be of
The value of the book may appear to some readers to be limited, in
that ,t treats of only the Pratt and Whipple systems; but it must be
IV
PREFACE.
reineml)ered that at least ninety per cent of all American iron highway-
bridges are built on these systems. This fact alone ought to prove
conclusively that they are the best type of bridge. Moreover, the
author has demonstrated, in a paper entitled " Economy in Struts
and Ties," published last year in the " Canadian Magazine of Science,"
and copied in the " American Engineer," by a method entirely practical,
that for economy the web compression members of trusses should be
vertical, or nearly so ; thus showing, that, of all the ordinary types of
truss, the Pratt or Whipple is the best.
Through bridges and pony trusses, both having inclined end posts,
have alone been treated at length ; for highway deck bridges are un-
common, and inclined end posts not only are more economical than
vertical ones, but are also superior to them because they produce tensile
stresses in the end panels of the bottom chords, thus ailding to the
rigidity of the structure.
The work is written for engineers, students, and, to a certain extent,
county commissioners. It is not intended, though, to be used by itself
as a text-book on bridges, dealing, as it does, with only one general
style of triiss, but to supplement the books generally used by classes
in engineering schools.
It is essentially a treatise upon bridge designing, and not one upon
stresses : nevertheless, it has been found necessary to discuss the latter
subject in order to make the work comjjlete. The author would refer
those who wish to study concerning stresses to Burr's " Stresses in
Bridge and Roof Trusses," Bovey's "Applied Mechanics," and I)u
Bois' " Strains in Framed Structures."
For county commissioners. Chapters IV., XIV., and XVII., Tables
I.-V., XV.-XXV., XXX.-XXXIII., and XXXVIII., and parts of Chap-
ter II., will be found very useful ; containing, as they do, directions and
data for making estimates of cost, and means of proving whether either
designs or finished structures have or have not in many particulars
sufficient strength.
Those portions of the "General Specifications" in Chapter II.,
relating to quality and tests of materials, workmanship, painting, etc.,
have been taken from standard specifications too numerous to permit
PREFACE.
of their autliority being here quoted : nevertheless, the author must
atkiu)wlf(Igf that he has received considerable assistance from a pa])or
by Mr. 1'. F. Brcndlinger published in No. 4, vol. iii., of the "Proceed-
ings of the Engineers' Club of Philadelphia," treating of some railroad-
bridge specifications prepared by Theodore Cooper, C.E. He wishes
to acknowledge also, with many thanks, the valuable aid rendered him
by his assistants, Messrs. Y. Nakajima and T. Fukuda, in preparing
drawings, and checking tables.
J. A. L. W.
ToKio, Japan, February, 1884.
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PREFACE TO SECOND EDITION.
Although the first edition of this work was issued only three or
four months ago, it has had the opportunity for receiving a thorough
overhauling by a class of half a dozen students, who were requested
to take special pains to point out errors. A few were found; but
they are of small importance, being principally typographical or
numerical. It is thought that all have been discovered and corrected,
but it is possible that others may exist : so, if any reader find any, he
will confer a favor upon the author by informing him of the same.
The correctness of the weights of iron in Tables I., II., and III.,
has received additional confirmation from the same class of students,
each student having made a complete design for a bridge. The great-
est variation found was less than one-half of one per cent. As the
bridges varied in class, span, and width of roadway, one being on a
skew, and two having sidewalks, it is fair to conclude that the tables
may be relied upon as correct for all cases.
A slight change has been made in Chapter V., near the end, in respect
to a statement concerning stresses in the posts of deck bridges ; but, for
reasons there stated, the formula has not been altered.
In a review of this treatise, by " The American En^neer;' there was
mentioned the fact that double beam hangers are not a satisfactory
detail, because of the unequal distribution of the floor-beam load there-
on. In the addenda is described a detail which will remove the objec-
tion. There are given also in this part of the work, and on Plate VIII.,
several other details that will be found to be improvements upon those
previously described. ,,
vm
i'Ri:rACE TO sEco.xn edition.
About July I, tlicre will be issued by the University of Toklo, In the
form of the usual "Memoir," a treatise of the author upon "A System
of Iron Railroad Bridges for Japan," which will be found to contain a
nun )er of important matters respecting the designing of railroad-
bridges, that have not hitherto received proper attention. The book is
not for sale ; but there will be alwut two hundred copies distributed in
America among engineers, colleges, public libraries, etc.
The author wishes to express his thanks to the profession for the
favorable reception given to his fust edition.
J. A. L. W.
ToKio, Japan, May 6, 1885.
PREFACE TO THIRD EDITION.
It is with considerable regret that the author allows this edition to
go to press without making a single change or addition, more especially
because his practice in bridge designing has lately been modified.
Time will not permit of his rewriting the work for a year or two at
least, so it will have to remain as it is for the present. The changes
which he would like to introduce in the text are not in principles, init
in methods and details of design ; American practice having changed
somewhat since thj book was first written. These points s^'ll all be
covered by some general specifications, which the author expects to
issue in a few months. They will probably be for sale, and advertised
in " Engineering Neros."
The priiuii)al changes in his methods are the following : —
I St, For long spans it is better to use the Pratt truss, with halved
panels, instead of the Whipple truss. In spans exceeding two hundred
feet, it is economical to make portions of the top chords inclined.
For short spans it is, in general, well to use rolled beams up to
twenty feet, plate girders from twenty to forty feet, triangular riveted
girders from forty to sixty-five feet, pin-connected pony trusses from
sixty-five to ninety feet, and pin-connected throug'^ or deck truss
bridges from ninety feet upward.
2d, Tlie batter braces (or, as they are now being generally termed,
the inclined end posts) are hinged at hip and pedestal.
3d, Floor beams are riveted to posts as near the lower chords as
possible, and the lateral rods are attached to the lower part of the
beams. The wooden shims over beams are retained for the purpose
of spiking the joists thereto.
ix
PREFACE TO THIRD EDITIO.W
4th, Filling-plates under floor beam stiffeners are no longer necessary,
as it is now very easy to Ijend the ends of the angles to fit around the'
flanges of the beams. It is permissible to stagger intermediate
stiffeners. End stiffeners should be figured for the total shear, using
an intensity of three tons for bridges of Class A, and three and three-
quarter tons for bridges of Classes B and C.
5 th, Upper lateral and portal struts are made of four angle -irons,
with a single system of lacing-bars. These struts are rigidly connected
to top chords or inclined end posts by riveting.
6th, End lower lateral struts can, in general, l^e made of single
angle-iron of large size. It is preferable to use one of these struts at
each end of every span. They can be riveted to the pedestals by
means of a connecting-plate at each end.
7th, Lacing is used everywhere instead of latticing.
8th, Rivets are figured for shear and bearing, not for bending.
9th, In many cases flattened heads may be used to advantage,
instead of countersinking the rivets, the thickness of the heads
being three-eighths of an inch.
lotli, Lateral rods are attached at each end to top chord by means
of three short pieces of angle-iron, through one of which the rod
passes. Tlie adjustment is made by a nut at each end, which bears
against the last mentioned angle-iron.
nth, In top-chord splicing, reliance is placed upon the abutting
ends of the chord sections. The splice is made about fifteen or
eighteen mches from the panel point on the side towards the nearer
pier, and there are only two vertical rows of rivets in the splice i)late
on each side of the joint The shop practice of first-class bridge
companies has improved so much during the past five years, that it
is now legitimate to rely upon abutting ends for this detail. Never-
theless, the author would prefer to hinge the top chord at each panel
point, for in this case there can be no doubt as to how the stresses
travel. The same cannot be said for any other style of connection.
1 2th, When a bridge is sufficiently heavy, it is well to build the toj)
chords and inclined end posts of plates and angles, using small, lioht
PREFACE TO THIRD EDITION.
XI
angles above, and large, heavy angles below, so as to bring the centre
of gravity of the section to the middle of the vertical plate.
13th, For hip verticals it is preferable to use a strut of two channels
similar to the posts, but not so efficiently laced, as the member acts
only in tension. Channels provide greater rigidity than do eye-bars.
14th, In proportioning compression members, Thacher's formula is
used instead of that of the late C. Shaler Smith. It is the following : —
/ =
9,000 — 30 - for O D
9,000 - 35- for D O
9,000 — 40- for O O
r
where / is the intensity of working stress in pounds, / the un.supported
length of strut in inches, and r the radius of gyration of section in
inches. The above formula is for bridges of Class A. To use it for
Classes B and C, multiply/ by \ ; and to use it for lateral struts, multiply
/ by |. In the latter case, however, considerations of rigidity generally
necessitate the use of greater sectional area than the stress would call
for.
15th, In order to be in accordance with modern practice, floor
beams should be proportioned by neglecting the resistance of the web
to bentling, and using an intensity of five tons for finding the ttct area
of the bottom flange in bridges of Class \, and six tons for bridges of
Classes B and C, then making tlie upper flange of the same section
as the lower, taking care, however, to have the ratio of unsupported
lengtii of beam to width of flange not greater than thirty.
In the author's opinion this method is not so rational as the one
which he used formerly, but it is more easily applied and gives about
the same results.
Strictly speaking, the web of a built beam does aid the flanges to
resist bending; but, in truth, the designing of built beams and girders
pertains less to science than to rule uf tiiumb.
Xll
PREFACE TO THIRD EDITION,
1 6th, Bent eyes on rods are no longer allowed,
i7tli, In every thing relating to quality of material, workmanship,
inspection, and tests, the Manufacturers' Standard Specifications are
to be followed.
The author trusts that the preceding lemarks, together with his
new specifications, will keep his book from becoming antiquated until
he can find time for re-writing the whole treatise.
J. A. L. W.
Kansas City, Mo., July i6, 1887.
PREFACE TO FOURTH EDITION.
Again with great regret does the author permit this work to reach
another edition without receiving a thorough revision, amounting, in
fact, to a complete re-writing of the book. The past year has been
such a busy one, that it was impossible for him to spare the necessary
time.
The new specifications promised in the last preface have been issued,
and are now on sale by Mr. A. C. Stites, Walworth Building, Kansas
City, Mo., the price being twenty-five cents per copy.
The author would advise that these be used in connection with this
book, and that, where they conflict, the new specifications be followed.
It will be seen that the latter contain considerably more than mere
si)ecifications, being a systematic attack upon the present methods of
tlesigning, letting, and building highway bridges. The pamphlet is
being well advertised and distributed aniong county commissioners ; and
the author is sparing neither time, trouble, nor expense to accomplish
the reform which he deems so necessary.
The re-writing of this treatise has already been begi;n ; but there is
no telling when it will be completed, for the author's spare time is
very limited. He hopes, however, that it will be be finished before a
fifth edition becomes necessary.
J. A. L. W.
Kansas City, Mo., April u, 1888.
CONTENTS.
Chapter.
, , Page.
I. Introduction
•••••••• I
II. General Specifications ....
III. List of Members
28
IV. Live AND Dead Loads. — Wind Pressure .... ,2
V. Stresses in Trusses .
38
VI. Stresses in Lateral Systems and Vertical Sway Bracing . 48
VIL Remarks concerning Main Members
Vin. Proportioning of Main Members of Trusses, Lateral' Sys^
TEMs, AND Sway Praclng . ^
00
IX. Proportioning of Floor System ^
X. Theory of Pin Proportioning g
XL Practical Method of Pin Proportioning g.
XIL Riveting
90
Xin. Proportioning of Other Details
XIV. Bills OF Materials AND Estimates OF Cost . ... 114
XV. Economy
120
XVI. Complete Design for a Bridge ,,5
XVIL Bridge Lettings
157
XVIII. Working-Drawings
172
XIX. Order Bills and Shipping Bills jg,
XX. Erection and Maintenance j_g
APPENDIX I. A Neglected Consideration in Highway-Bridge
Designing .
215
APPENDIX II. Demonstration of Formula for Floor Beams . 219
APPENDIX III. Method of Finding the Length of the Long
Diagonals in a Double-Intersection Bridge . . ,21
ADDENDA ...
GLOSSARY OF TERMS . * "5
INDEX 233
. . . 247
INDEX OF TABLES.
i.-iii.
IV., V.
VI.-VIII.
IX.
X., XI.
XII.
XIII., XIV.
XV.-XVIII.
XIX.-XXI.
XXII.-XXIV.
XXV.
XXVI., XXVII.
XXVIII.
XXIX.
XXX.
XXXI.
XXXII., XXXIII.
XXXIV., XXXV.
XXXVI., XXXVII.
XXXVIII.
XXXIX.
XL.
XLI.
XLII.
Dead Loads.
Economic Depths and Tanel-Lengths.
Sizes of Hip Verticals.
Working Tensile Stresses and Initial Tensions.
Intensities OF Working-Stresses for Channel Struts,
Working Bending-Moments and Shearing-Resist-
ances for Tins.
Working Loads for Wooden Beams.
Amounts of Lumher per Panel, Sizes of Joists, etc.
Sizes and Weights of Floor-Beams.
Sizes of Beam-IIangers.
Sizes of Portal, Lateral, and Intermediate .Struts,
and of Upper Lateral, Lower Lateral, and Vibra-
tion Rods.
Thicknesses for Pin-Bearings.
Dimensions of Union Iron Mills' Channel-Bars.
Lengths of Lattice-Bars, Weights per Foot of Same,
ETC.
Sizes of Lattice-Bars.
Sizes of Lacing-Bars.
Sizes of Stay Plates.
Permissible Pressures on Rollers.
Working Bending-Moments and Bearing-Pressures
FOR Rivets.
Laisor in Erection.
Working Loads for Falsework Pillars.
Working-Loads for J-Beam Struts.
Stresses in Single-Intersection Trusses.
Stresses in Double-Intersection Trusses.
XV
INDEX OF PLATES.
I. Isometric Drawing of a Bridge with Names of Main Members.
II. General Descriptive Plate of Details.
III. Details for a Pony Truss-Bridge.
IV. Details for a Single-Intersection Through City Bridge with
Two Sidewalks.
V. Diagram of Stresses and Sections.
VI. Working-Drawings for a Bridge.
VII. Working-Drawings for Falsework.
VIII, Details Illustrating the AnnENDA.
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THE DESIGNING
or
ORDINARY IRON HIGHWAY-BRIDGES.
CHAPTER I.
INTRODUCTION.
That many bridge designers will have fault to find with the
contents of this book goes without saying, but it will be found
that the principal objections will come from those who design
the lightest and poorest structures. The weights of iron in the
bridges here treated are probably from twenty to fifty per cent
greater than those in the bridges ordinarily built ; but it is to
be remembered that most American iron highway-bridges are
not what they ought to be, and that the author has endeavored
to design structures first-class in every respect.
The principal differences between these bridges and those
ordinarily built are the stiffening of the end panels wherever
necessary ; the use of C. Shaler Smith's formula, involving, as it
generally does, an increase of sectional area ; the peculiar lower
lateral system, which avoids using the floor beams as lateral
struts ; the large lateral rods employed ; the allowance for initial
tension in all adjustable rods; the variation of the intensity
of working-stress for main diagonals ; the assumption that all
stresses at joints in top chords and at upper ends of posts are
carried by the connecting plates and their rivets, no reliance
bemg placed upon the abutting ends of channels ; the limiting
sizes of the sections of iron employed ; and the unusual strength
O/WJAAKy JKOA' JiiuliWAV-nKIDuES.
of the upper lateral and portal struts, especially when no verti-
cal sway bracinj; is usctl.
On the other hand, those who wish to proportion bridges by
the latest theories may object to the employment of C! Shaler
Smith's formula (which fails to take into account the radius
of gyration of the section) and to the non-employment of the
results of Wohler's and Weyrauch's recent investigations con-
cerning intensities of working-stresses. To the first objection,
the author would reply, that designers of ordinary highway-
bridges cannot afford the time to spend at least fifteen minutes
in obtaining the theoretically best intensity of working-stress for
each strut, but must have for this pur|)ose tables which will ^ive
the intensities without calculation : besides, the best theoretical
intensity is merely approximate. To the second objection, he
would reply, that the results of the investigations rcfeired to
have not yet been generally adopted, and that the variation of
intensity of working-stress for the main diagonals used in tiiis
treatise is, in his opinion, for ordinary highway-bridge design-
ing, a sufficient concession to the general correctness of the
theory of those writers.
The units used throughout this work are as follows : the
American ton (two thousand pounds) for the units of weight
and stress, the foot for the unit of length, and the square inch
for the unit of area.
It is presupposed that the reader, if he intend to design, or
even study the designing of, iron bridges, has procured a copy
of Carnegie's " Pocket-Companion," the most useful little book
of its kind for bridge builders that has ever been printed : so
the tables therein are here referred to, instead of being repro-
duced.
The sections of iron employed arc those rolled at the Union
Iron Mills, for the reason that not only is there more iron rolled
in these mills than anywhere else in America, but the proper-
ties of the sections arc tabulate'' n a mnch more convenient
form than are those of any othe* n;il'<. The author intended
to prepare a table of channels ,i ! by the New-Jersey Steel
and Iron Company of Trenton, N.J., similar to Table XXVIII. ;
but the information in that company's pocket-book is not
II IK) vcrti-
CSS of the
OA'D/A'Afiy /A'ox nn;n\\'Av-niuiH;Es. 3
complete enou-h to enable him to tabulate the thicknesses of
the webs.
Anyone intending to desijrn bridges according to the method
herein proposed should thoroughly acquaint himself with the
numbers and uses of the different tables, so as to turn to the
one required without delay. He should also become posted on
the contents of Chapters VII.-XIII., so as not to have to refer
to that part of the book, turning to Chapter II. to refresh his
memory concerning intensities of working-stresses, limitations.
etc., while designing each main member and detail. After a
little practice, one will become acquainted with the method,
when it will be necessary to refer to the tables only.
If a designer be in doubt about how to proportion any main
member or detail, he can at once find out the method by look-
ing in the Inde.x, under the head "Proportioning," where he
will see the numbers of the pages on which the proportioning
of this member or detail is treated.
Any intelligent man who is not an engineer can make an
approximate estimate of what a first-class iron highway-bridge
ought to cost, by finding the required weight of iron from one of
Tables I., II., or III., modifying it, if neces.sary, in the manner
explained in Chapter IV. ; and the required amount of lumber
from one of Tables XV., XVI., XVII., or XVIII.. ascertaining
the prices of iron per pound, and lumber per thousand feet°
delivered at the nearest railway-station or seaport, and filling
out the form for an estimate of cost given on p. 1 16. By refer-
ring to the Index, under the heading "Cost," he can ascertain
where approximate data for all bridge-building expenses can be
found.
No special treatment is here given for skew bridges ; for none
is needed, the methods for designing them being precisely the
same as those for other bridges. On account of the obliquity,
the working drawings for the lateral bracing and sway bracino-
are a little more complicated. Whenever it is convenient to do
so, the panel lengths should be arranged so that the shoe of
one truss comes opposite to the first panel point of the other
truss, in order that the floor beams may be at ri-ht angles
to the planes of the trusses, both for economical reasons, and to
ORDIXARY IRON HIGHV'AY-BRIDGES.
avoid using single beam hangers. This arrangement can often
be made by shortening the panel length a little, and, if it be
allowable, slightly changing the angle of the skew. Even if it
be impracticable to make this arrangement, it is usually better,
in skew bridges, to advance the ends of the floor-beams at one
side of the bridge, by one or even two panel lengths, if, by so
doing, the floor beams be shortened.
ORDINARY IRON HIGHWAY-BRIDGES.
CHAIT'ER II.
GENERAL SPECIFICATIONS.
This chapter, at first thought, may appear out of place ; for it
is really a n'siivic of the whole subject of iron highway-bridge
designing. It is placed here in order to be of easy reference.
Students, and those unacquainted with bridge designing, are
advised to omit these specifications, and to return to them after
having read through Chapter XIII.
Classification. — Highway-bridges maybe divided into three
classes ; viz., Class A, which includes those for cities and their
suburbs that are subjected to the continued dL\)X)\\c:xt\on of heavy
loads ; Ciu.is B, which includes those for cities and their suburbs,
or manufacturing districts, that are subjected to the occasional
application of heavy loads ; and Class C, which includes those
for country roads, where the traffic is lighter.
Live Load. — The live loads for bridges of the different
classes are to be taken from the followins table: —
SPAN IN FEET.
Moving Load per Square Foot of Floor.
Classes A and B.
Class C.
to 50
50 to I 50
I 50 to 200
200 to 300
300 to 400
100 pounds
90 pounds
80 pounds
70 pounds
60 pounds
80 pounds
80 pounds
70 pounds
60 pounds
50 pounds
The live loads for joists, floor beams, beam hangers, and hip
verticals, are to be one hundred (100) pounds per square foot of
floor for bridges of Classes A and \\, and eighty (80) pounds per
6
OKD/A\l/n- /J^O.y JIIullWA V-B RIDGES.
square foot for bridges of Class C, irrespective of the length of
bridge.
DiacfLoad—Tho dead load is to include the weight of all
the iron and wood in the structure, excepting that of those por-
tions resting directly on the abutments, whose weights do not
affect the stresses in the trusses ; also, if necessary, an allow-
ance for snow, mud. paving, or any other unusual fixed load
that may ever be placed on the bridge.
Pine-lumber is assumed to weigh two and a half (2.1) pounds
per foot, board measure ; and oak-lumber, fotir and a third (4^)
pounds per foot, board measure.
: Should, in any biidge of or below one hundred (100) feet
span, the calculated dead load differ more than eight (8) per
cent from that assumed, or in any bridge from one hundred
(100) to two hundred (200) feet span, more than six (6) per
cent, or in any bridge exceeding two hundred (200) feet span,
more than four (4) per cent, the calculations of stresses, etc.,
are to be made over with a new assumed dead load.
IViiui Prcssiin:— The wind pressure per square foot i.s to
be assumed as forty (40) pounds for spans of one hundred (100)
feet and under, thirty-five (35) pounds for spans over one hun-
dred (100) and not greater than one hundred and fifty (150)
feet, and thirty (30) pounds for all greater spans.
For bridges in unusually exposed situations, these pressures
are to be increased by ten (10) pounds per square foot.
The total area opposed to the wind is to be determined by
adding together the area of the vertical projection of the floor
and joists, and twice the area of the vertical projection of the
windward truss, hand rail, hub plank, guard rail, and ends of
floor-beams.
Laigt/t of Span. — The length of span is to be understood
as the distance between centres of end pins for trusses, and
between centres of bearing-plates for all beams and girders.
Umitiiii; Lengths of Span for Different Clear Roadzvavs. —
The greatest lengths of span for the different clear roadways
are to be one hundred and forty (140) feet for twelve (12) foot
roadways, one hundred and ninety (190) feet for fourteen (14)
foot roadways, two hundred and sixty (260) feet for sixteen
ORDINARY IROX HIGHlVAY-liRlDGES. 7
(16) foot roadways, and three hundred and fifty (350) feet for
eighteen (18) foot roadways. By clear roadway is meant the
tlistance between the innermost portions of the opposite trusses,
measured in a direction perpendicular to their planes.
Limit of Char Hcadivay. — The least allowable clear head-
way is to be fourteen (14) feet, unless some local consideration
cause it to be increased. \\y clear headway is meant the ver-
tical distance between the upper face of the flooring and the
lowest part of the portal or overhead bracing.
Styles of Bridges for Different Spans. — Spans of and belo>v
twenty (20) feet are to consist of rolled beams ; spans from
twenty (20) to forty (40) feet, of riveted plate girders or trussed
beams ; spans from forty (40) to si.xty-five (65) feet, of stiffened
pony trusses or stiffened deck bridges, unless the weight of
bridge be great enough to admit of the use of eye bars for the
bottom chords ; and spans above sixty-tive (65) feet, of pin-
connected through or deck truss bridges.
Limiting Depth of Pony Trusses. —T\^ii greatest allowable
depth, measured from centre to centre of chords, for pony
trusses without exterior side bracing, is to be six (6) feet ; and
that for pony trusses with exterior side bracing, nine (9) feet.
Vw bridges with sidewalks, in which it is inconvenient to use
exterior side braces, the depth may be increased to eight (8)
feet, provided that the width of the top chord plate be double
the dejith of the top chord channels, and that the channels
comjiosing the posts and hip verticals be splayed outwartlly so
as to be separated in the clear at their feet by at least twenty-
four (24) inches.
Limiting Slope for Batter Braces of Pony Trusses.— i:\\<t least
allowable slope for batter braces of pony trusses is to be two
and a quarter {2]) horizontal to one (1) vertical.
Side Fumes. — The least allowable batter for side braces in
pony-truss bridges is to be five (5) inches to the foot, and all
sitle braces are to be made to resist both tension and compres-
sion. In no case is a side I'race to have less strength than that
of a 2^" X 2»" 5-lb. angle-iron.
Limiting Length of Span for Double Interseetion Btidges. ~
The least allowable length of span for double intersection
bridges is to be taken from the fdlldwin-" table: —
ORDINARY IROX HIGniVAY-BRinGKS.
CLEAR ROADWAY.
I.i.MiTJNc; Lkni;tiis.
Class A.
Class B.
Class C.
14'
16'
18'
20'
22'
24'
i6s'
•55'
150'
145'
140'
140'
175'
165'
160'
155'
ISO'
•45'
180'
170'
165'
160'
■55'
150'
Limiting Sizes of Sections. — No rods less than three-quar-
ters (|) of an inch in diameter are to be used in a bridge. No
channels less than five (5) inches in depth are to be used for
upper chords, batter braces, or posts, or less than four (4) inches
in depth for other members. No flat bars less than one-half {I)
inch thick, or one and a half (i^) inches wide, are to be used
for diagonals or chord bars ; nor any iron less than one-quarter
(|) of an inch thick anywhere in a bridge, excepting for filling
plates.
Expansion. — All spans are to be provided with some means
of expanding and contracting longitudinally, with a variation in
temperature of one hundred and fifty (150) degrees Fahrenheit.
Spans of over seventy-five (75) feet are to have at one end nests
of turned wrought-iron friction rollers, running between planed
surfaces.
Anchorage. — At least one end of every bridge must be
anchored to the foundations. If the overturning moment of
the greatest assumed wind pressure be more than half the
resisting moment of the weight of the bridge, the latter must
be anchored at the roller end also, but in such a manner as not
to interfere with the expansion.
Sliding. — At the roller end of a bridge, if the frictional
resistance to the sliding of the shoe in the direction of the axes
of the rollers be not more than double the tendency to slide
produced by the wind pressure, a resistance equal to the differ-
ence between this tendency and the frictional resistance with a
factor of safety of four (4) must be provided.
ORDINARY IRON HIGHWAY-BRIDGES. g
CiHitii/iioiis Sfaiis. — Except in the case of swing bridges or
cantilevers, consecutive spans are not to be made continuous
■over the points of support.
Camber. — The cambers for bridges of the different spans are
to be taken from the following table : —
Si'AN IN Feet.
Camber in Inches.
Si'AN IN Feet.
Camber in Inches.
40-60
I.O
180-220
3-S
60-80
'S
220-250
4.0
,So-ioo
2.0
250-280
4-5
100-140
2.5
280-300
5.0
1 40- 1 So
3-0
Vertical Sway Bracing. — \n all deck bridges, and in all
through bridges where the depth from centre to centre of
chords is twenty-four (24) feet or over, vertical sway bracing
is to be used.
Portal and Lateral Struts. — Portal and lateral struts are to
be proportioned to resist the compression produced by the
wind pressure and the initial tensions in all the rods meeting at
the end of the strut. If the strut be also subjected to bending,
then to the area necessary to resist compression must be added
sufficient area to resist the bending ; the intensity of working
bending-stress being taken equal to six (6) tons.
Effect of Wind on Posts and Batter Braces. — But the effect
of the wind on the posts and batter braces is not to be considered
to occur when the bridge is fully loaded : so, unless the stresses
produced thereby exceed the product of the live load stresses
by the ratio of seven and a half (7.5) to the intensity of working
tensile stress for the bottom chord, the effect of the wind on
these members may be neglected.
Effect of Wind Pressure on Bottom Chord Tension. — For the
same reason, the sectional area of the bottom chord need not
be increased to resist the tension caused by the wind, unless
the latter exceed the product of the live load stress by the ratio
of seven and a half (7.5) to the intensity of working tensile
stress for chord bars.
10
ORDIXARY IRON HIGHU'A Y-li RIDGES.
Initial Tension. — To allow for the stresses caused in adjusta-
ble members by the screwing up of the turn buckles or sleeve
nuts, the stress in each such member is to be increased by the
amount given in the following table :■
iMA.MiniCU (IK Kl>I>.
Inhial Tension.
DlAMETKR (IK R(ll).
Initiai, 'Iensiiin,
1"
0.50 ton
■1"
2.25 tons
r
0.75 ton
If
2.50 tons
I"
1. 00 ton
•r
2.75 tons
li"
1.25 ton
2"
3.00 Ions
li"
1.50 ton
^-^'
3.25 tons
If"
1.75 ton
2f'
3.50 tons
li"
2.00 tons
2a"
375 t<"i^
Square or flat bars are to receive the allowance for round rods
of equal sectional area.
Conncctioti for Lateral Systems. — Whenever it be possible,
the lateral rods of both upper and lower systems are to be
connected directly to the chord pins. But, if the rods exceed
one and three-quarter (i|) inches in diameter, bent eyes are not
to be employed.
Lower lateral rods are not to be attached to the floor beams.
To make them clear the joists, wooden lateral struts resting
on the floor beams, and having wrought-iron jaws at their ends
attached to the chord pins, are to be employed for the joists to
rest upon.
These wooden struts are to be bolted about every two feet
through the upper flange of the floor beam by five-eighth {\)
inch bolts, care being taken to stagger the bolt holes, and to
avoid placing a bolt at the middle of the beam.
Should the sizes of the lateral rods be such as to prevent the
use of bent eyes, pins dropped vertically through the jaws are
to be employed.
Stresses in End Lower Lateral Stmts. — In figuring the stress
in a lower lateral strut at the roller end of a l^ridge, the
stress caused by the wind pressure is to be added to the trans-
verse component of the initial tension in the end lateral rod.
ORDINARY IRON HIGHIVAV-URIDGES.
I I
lAI.
'i'ENSlON.
25
tons
50
Ions
75
tons
00
tons
-5
tons
50
tons
75
tons
round rods
ai.d Irom the sum is to be subtracted the product of the press-
lire on the windward shoe, when the bridge is empty and sub-
jected to the greatest wind pressure, l)y the co-efficient of iron
upon iron, which is about 0.25 for this case.
Stiffened End Panels. ~\l, in the end panel of a bridge, the
longitudinal component of the greatest allowable working^stress
(including initial tension) in the lower lateral rod exceed the
tension in the lower chord of that panel, caused by the dead
load alone, when the bridge is subjected to the greatest wind
p--jssure, the bottom chord of that panel must be made to resist
both tension and the excess of compression. Where two chan-
nels are employed for the lower chord section, the effective area
of tie webs alone must be counted on to resist tension. Where
the sriffening is obtained by trussing the inner chord bars, the
intensities of working tensile stress to be employed for the net
section of those bars arc four (4) tons for bridges of Class A,
and five (5) tons for those of Classes B and C.
Top-Chord and Battcr-Bracc Sections. — The top chords and
batter braces shall consist of two channels, with a plate above,
and latticing or lacing below. The top plate must be of the
same section, and the chord channels of the same depth, from
end to end of span ; the increase in chord section towards the
middle being ojjtained by thickening the webs of the chan-
nels.
Post 5<v7/,vAv. — Posts arc to consist of two channels, with
latticing or lacing on each side. The upper ends may be either
rigidly attached to the chords, or may be hinged on the pins ;
preference being given to the latter method.
Portal and Upper Lateral Stmt Seetions. — Portal struts anrl
upper lateral struts are to be formed of two channels, latticed o--
laced, and rigidly attached at their ends to the batter braces or
chords.
IVorkin^^r Tensile 5/;r...r.x - Except for the case of trussed
bars, mentioned under the divisions " Stiffened I-:nd Panels " and
"Stiffened Hip Verticals," the intensities of working-strosses for
iron in tension in the various members are to be as given in the
f'.>llowing table : —
ORDLXARV IRON HliiH WAY-BRIDGES.
MEMBERS.
Lower chord bars and end main diagonals .
Middle panel diagonals, counters, and hip
verticals
Flanges of rolled beams
Flanges of built beams (net section) . . .
Lateral and vibration rods
Beam-hangers
Intensitiks i)F W'okkinc.-Strkss.
Class A. Classes B and C.
5.00 tons
4.00 tons
5.00 tons
4.00 tons
7.50 tons
3.00 tons
6,25 tons
5.00 tons
6.00 tons
5.00 tons
7.50 tons
4.00 Lons
The intensities of working-stress for main diagonals inter-
mediate between the counters or middle panel diagonals and
the end diagonals lie between four (4) and five (5) tons for
bridges of Class A, and between five (5) and six and a quarter
(6|) tons for those of Classes B and C; the amounts being
directly interpolated according to the position of the panel.
Working Compressive Stresses. — For struts composed of two
channels with plates, or lacing, or latticing, the following for-
mulas are to be used in finding the intensities of working
compressive stresses.
For chords, batter braces, and posts in bridges of Class A,
/
I +
H^
P =
4 +
20
and for all other cases,
/
1 +
/ =
4 +
C
30
H =
p being the intensity of working-stress, and
length of strut
least diameter of stmt'
f 19.25 for two fixed ends
(1 end and one hinged end
.yo •
/= I 19.25 for one fixed end and
I 18.90 for t\\(i liin:j:cil rnds,
OND/X.IKV nWN HlGHWAY-liRlDGES.
13
'iiukinc-Stress.
Classes B and C.
6.25 tons
5.00 tons
6.00 tons
5.00 tons
7.50 tons
4.00 ions
and
[5820 for two fixed ends.
C -■- \ 3000 for one fixed end and one hinged end
[ 1900 for two hingctl ends.
Where I-beams are employed for intermediate struts or end
lower lateral struts, the working-stresses arc to be taken from
Table XL. For the flanges of rolled beams, the intensities of
working compressive stress are to be taken equal to five (5) tons
for bridges of Class A, and six (6) tons for bridges of Classes H
and C. For the flanges of built beams, the corresponding inten-
sities are to be four (4) and five (5) tons respectively on the
gross section.
Working Bcnding-Strcsscs. — The intensities of working bcnd-
ing-stress on pins arc to be seven and a half (7.]) tons for bridges
of Class A, and nine and three-eighths (9|) tons for those of
Classes B and C. For pins belonging wholly to the lateral
systems of bridges of either class, the intensity of working
bending-stress may be taken equal to eleven and a quarter
(I i|) tons. The intensities of working bending-stress for rivets
are to be seven and a half (7.]) tons for bridges of Class A, and
nine and three-eighths (9'^) tons for those of Classes V> and C.
The latter intensity is also to be used for the lateral systems of
bridges of Class A.
Where steel pins are employed, the intensity of working
bending-stress must not be taken greater than twelve (12) tons
for bridges of Class A, or fifteen (15) tons for those of Classes
B and C, unless special experiments on the steel used show an
ultimate bending resistance greater than si.xty (60) tons per
sc|u:He inch ; in which case a factor of five (5) may be used for
bridges of Class A, and a factor of four (4) for those of Classes
B and C. As before stated, the intensity of working bending-
stress for channels in portal and lateral struts is to be six (6)
tons.
Working Bcaring-Strcsscs. — The intensities of working bear-
ing-stress for pins and rivets, measured upon the projection of
the semi-intrados upon a diametral plane, are to be six (6) tons
for bridges of Class A, and seven and a half (7.^) tons for those
'4
ORD/XARV /ROX Hh'.IIWA V-liRllh'.ES.
of Classes V> and C. I'or pins and rivets belonging; wholly to
the lateral system of a bridge of any class, the intensity is to
be taken equal to seven an'l a half (7^) tons.
Sirjcs of rp/'cr Lntrnil Rods. — In bridges of less than two
hundred {200) feet span, the stresses in the upper lateral system
in through bridges, or the lower lateral system in deck bridges,
usually call for sections of rods which are practically too small :
therefore the inferior limits of the diameters of these rods in
such cases are to be taken from Table XXV.
Stiffened Hip W-rticah. — Hip verticals in three or four panel
pony trusses are to be stiffened so as to resist compression. If
the section employeil consists of two channels, the net section
of the webs alone is to be relied on to resist tension. If it con-
sists of two flat bars trussed, the intensities of working tensile
stress on the net section are to be reduced to three (3) tons for
bridges of Class A, and to four (4) tons for those of Classes H
and C.
Trussing. — Trussing is to be used only in the posts of pony
trusses, where there is a great excess of strength, in the hip
verticals of pony trusses, and in stiffening lower chord bars.
Upset Ends. — Middle panel diagonals, counters, lateral rods,
vibration rods, and all other adjustable rods, excepting beam
hangers that have an excess of section, are to have their ends
enlarged for the screw threads, so that the diameter at the bot-
tom of the thread shall be one-si.xteenth (,";.) of an inch greater
than that of the body of the rod, .square or Hat bars being
figured as if of equivalent round section.
Threads. — All threads, except those on the ends of pins,
must be of the United-States standard.
Miiiininin Dimensions of Chord and Batter-Brace Plates. —
The minimum dimensions for the top plate in top chords and
batter braces are to be taken from the following table. For five
(5) and six (6) inch channels, the thickness docs not increase
with the width. For seven (7) inch channels, the thickness
should be increased to five-sixteenths (/',.) of an inch, should
the width exceed fifteen (15) inches. For the other channels,
should the width of plate exceed that given in the table by
from forty (40) to seventy (70) per cent, the thickness must be
s than two
cral system
ick bri(l};es,
,' too small :
jsc rods ill
;inf; tensile
bars bein<^
ONJJ/XANV /h-OX umilWA Y-liRinCES.
IS
Increased by one-sixteenth (j\,) of an inch, while, if it exceed
by more than seventy (70) per cent, the thickness must be
iiuToased by one-eighth (J) of an inch.
Iii-rni i)K
MiNIMlM
MlNIMI'M
l)i:nii (IP
MiM.MI'M
MiNlMIM
ClIANNBL.
s"
Thickness.
Width.
Channel.
Thickness,
WlDlll,
f
7"
9"
A"
\\\"
6"
f
8"
10"
A"
I2V'
7"
f
9"
12"
i"
IS"
,S"
i"
10"
15"
i"
■ 9"
AAn' /'/-^Ax —Sizes of stay plates are to be taken f
rom
Tables XXXII. and XXXIII. Stay plates on latticed or laced
compression members are to be i)laced as near the pin holes as
possible. Latticing or lacing must never be used without stay
plates at the ends.
I.atticiiii:; (vui Laciiio; Inirs. — The sizes for lattice bars and
lacing bars are to be taken from Tables XXX. and XXXI.
The distance from the back of an end rivet hole to the end
of the bar must not be less than one-half the width of the bar.
The ends of the bars are to be semicircular, except when there
are two rivets at each end, in which case they should be cut
l)arallel to the channels.
Inclination of Latticiiii^ and Lacing Bars. — Lattice bars shall
ces will permit.
make with each other, as nearly as circumstan
angles of ninety (90) degrees ; and lacing ba
rs, an<iles
of
SIX
(60) degrees.
ty
Diameters of Rivets for Different Channels. — For attaching
|)lates and Ltttice or lacl.-.g bars to the flanges of channels, the
least diameters of the rivets to be used are to be taken from
the following table ; and the greatest diameters must not exceed
those there given by more than one-eighth (J) of an inch.
Drptli of tliiinnel . . 4" 5"
Di.imuter of rivets . , 4" J"
6"
k"
7"
9 "
V6
8"
1"
9"
10" 12"
11" 3"
16 1 %
15"
13"
16
Splice Plates.— The length of a splice plate is to be deter-
16
oRP/x.ih']' /A'o.v nhiiiW'A v-nh'/in;/:.s\
mined by the niinihcr of rivets necessary to transfer the stress
from one main meniber to the other. The sum of the workinj;
bearing resistances of all the rivets on either side of the joint
must not be less than the stress in the main member upon that
side. The rivets must also be fi^an-ed for beiulin};. When
practicable, a splice plate must be placed on each side of every
member where a joint occurs.
The transmission of compressive stresses shall be considered
as entirely throu^di the medium of the rivets and connectin^^
plates, and these must be proportioned accor(lin<;ly ; so that the
area of the two sj^lice plates connecting two channel bars must
be at least ecpial to that of the Iar},^er channel bar.
Ki-i/z/o/rn/^i,'- J'^latis. — Simple re-enforcing plates, or plates
riveted to webs at pin holes in order to compensate for strength
lost there, or to provide additional bearing for the pins, must
have as many rivets to attach tliem to the webs as will give
bearing and bending resistances for the same, equivalent to at
least the greatest stresses that can come upon the re-enforcing
plates.
Cover Plates. — Cover plates for top chords or batter braces
are to have the same section as the chord or batter-brace |)late,
the joints in which they cover, and enough rivets on each side
of the joint to take up the greatest stress that could ever come
U|)on the said chord or batter-brace plate.
Extension Plates. — Ivxtension plates on the end of a strut,
for the purpose of hinging the latter, are to have at least twice
the sectional area of the strut from the pin-hole to the nearest
edge of the stay jilate ; and the thickness must be great enough
to give sufficient bearing upon the pin. The length of the
extension plates is to be such as to allow of the use of a suffi-
cient number of rivets to provide proper bearing and bending
resistances for the same.
Shoe Plates, Roller Plates, ami Bed Plates. — No shoe jilate
is to have a less thickness than three-cpiarters {\) of an inch,
and no roller plate or bed plate a less thickness than seven-
eighths (^) of an incli. When nine (9) or ten (10) inch chan-
nels are used for tlie batter braces, the thickness of the shoe
plates is to be seven-eighths {\) of an inch. When twelve (12)
r)A7>/.\. //T fNOX mcinVAV-nNlDC.KS.
17
considered
iiuli rlKinm-ls are used for tlie l)atter braces, the thickness of
the slioe plates, roller plates, and bed plates, is to be one (i)
iiuh ; and, when fifteen (15) inch channels arc used, it is to be
(Hie :'nd an eighth {\\) inches.
Ik'd plates must be of such dimensions that the fjreatcst
pressure on the masonry shall not exceed two hun.Ired (200)
pounds per scpiare inch.
Every bearinj; upon masonry must lie provided with cither a
bed plate or a roller plate, well fastened to the masonry by bolts
not less than one (1) inch in diameter; but, if the shoe plate
i)e sufficiently large, it may act as a bed plate at the fixed i^mX
(if tile span.
Inam-llaiii^ir Plates. — Ream-hanger plates arc never to be
made less than three-(piarters {%) of an inch thick, and their
ru-eas are to be such that the hanger nuts will always have a full
bearing thereon. The necessary thickness for a beam-han-er
plate is to he determined by considering it as a beam uniformly
loaded by the whole weight that comes on th,. luingers ; the
length of said beam being the distance between the centres of
the holes through whieh pass the ends of one hanger, and its
width I)eing the extreme dimension of the plate, mc^isured par
allel to the floor beam. The intensity of working-stress for
ben.hng in the plate is to be taken equal to that used in pro-
portioning the lloor beam.
Rivctii,}^r, _ In ri,,ctcd work, all joints arc to be squarely and
truly dressed, and the rivet holes must be accurately spaced
No rivets with crooked heads, or heads not formed accurately
on the shank, or rivets which are loo.se either in the rivet holes
or under the shoulders, will be allowed in a bridge.
Kivet holes in top-chord plates and batter-brace plates shall
be spaced as nearly as practicable two and a half (2I) inches
eenlre to centre near the panel points, and four (4) inches centre
to centre elsewhere.
No rivet-hole centre shall be less than one and a half (lU
< lameters from the edge of a plate: whenever practicable, this
distance is to be increased to two (2) diameters.
The diameter of a hole shall never exceed that of the rivet by
more than one-sixteenth {-^) of an inch.
i8
OA'/)/A:iA'r /A'O.V IIlCUWAV-nRlDGES.
When two or more thicknesses of plate are riveted together
in compression memljers, the outer row of rivets shall not be
more than three (3) diameters from the side edge of the plate.
Rivet holes must never be spaced less than two and a haif
(2},) diameters from centre to centre: it is preferable that this
distance be increased to three (3) diameters when so doing will
not cause inconvenience in designing.
All the rivet holes of the respective parts of any structure
must be made to exactly coincide, either b> drilling the holes
full size through the connecting portions, after being put
together, or by sub-punching the pieces separately, and after-
wards reaming the combined rivet holes to proper size. In all
cases the burrs must be removed by slightly countersinking the
edges of the holes.
All rivets in splice or tension joints are to be systemati-
cally arranged, so that each half of a tension member or splice
plate will have the same uncut area on each side of its centre
line.
No rivet, excepting those in shoe plates, is to have a less
diameter than the thickness of the thickest plate through which
it passes, nor in any case less than half (\) an inch.
Built J/rw/v/x — The several pieces forming one built mem-
ber must fit closely together, and when riveted shall be free
from twists, bends, or open joints.
Use of Balis.— Ihc use of bolts instead of rivets is to be
avoided whenever practicable.
Lateral Dracin^r for Plate Girders. —When a span consisting
of plate girders is over fifteen (15) feet in length, the adjacent
girders are to be braced to each other by diagonal angle irons
attached to or near the lower flanges. There are to be, also,
light bracing-frames at each end between adjacent girders, so
placed as not to interfere with the expansion. When the si^an
is over twenty-five (25) feet in length, the upper flanges of
adjacent girders are also to be connected by diagonal angle-iron
braces.
In every case the joists are to be dapped at least an inch
onto the girders, and every third joist resting on any girder is
to be bolted through the upper flange.
ORD/AARV IROX HlGHlVAY-nRlDGES.
19
Fonna/a jor Built Floor Bavus mid Plate Girders * — The
tension flanges of built floor beams and plate girders are to be
proportioned by the formula
A =
8DT 6
+ A",
where A is the area of the flange, A' that of the web, A" that
lost from the flange by a rivet hole, JFthe uniformly distributed
load in tons, /. the length of the beam in feet betv jen centres
of supjjorts, 7) the depth in feet between centres of gravity (,(
flanges, and T the intensity of working tensile stress in tons.
The same formula will apply to the compression flanges by
making A" equal to zero.
Stiffnnrs. — Built floor beams and plate girders must be stiff-
ened by four (4) angle irons at each support, and by two (2)
angle-irons at several intermediate points ; the distance apart
of the stiffeners being made no greater than twice the depth of
the beam when the ratio of thickness of web to depth of same
is not less than one-eightieth {^^), and no greater than one and
a half (I J) times the depth when this ratio is one over one
hundred and twenty (y-|^). Distances for intermediate ratios
arc to be interpolated.
Tee-irons are not to be used as stiffeners.
Stiffening angles, which must always be in pairs (one angle
on each side of the web), must extend from the upper leg^'of
the upper flange angle to the lower leg of the lower fla^nge
angle, being made flush with the other legs of the flanges by
filling plates.
U'r/> Splices in Floor Beams and Plate Girders. — Wchs of
floor beams and plate girders must be well spliced at all joints
by a splice plate on each side of the web ; and joints must be
located where the shear is not great.
Limitiug Depths of Floor Beams and Plate Girders. — The
depth of the web of a floor beam or plate girder must never
exceed one hundred and twenty (120) times its thickness.
• For proof of this formula, see Appendix II.
20
ORDLXARV IROX HIGHWAY-BRIDGES.
Rivets in Flanges of Floor Bcmiis and Plate Girders. — In
spacing the rivets in the flanges of floor beams and plate gird-
ers, the flanges are to be divided into portions of about two (2)
feet in length, the stresses in the flanges are to be found at
each point of division, and there must be enough rivets between
any consecutive points of division to take up the dilfercnce
between the stresses at the points, providing that the rivets be
not spaced more closely than two and a half (2i) diameters,
nor more than six (6) inches apat.
/y,,x _In welded heads, the length of metal behind the pni-
hole must be at least equal to the depth of the bar or diameter
of pin, whichever be the greater, unless the head be corre-
spondingly thickened ; while in hammered heads the amount is
to be the same as that above or below the pin hole.
The least amount of metal in the heads across the pin holes
is to be as given in the following table : —
DIAMETER OF I'lN
Metal in Head across Pin.
WIDTH OF BAR
Welded.
Hamnicred.
o.So
1.50
1.50
1.04
1.50
1.50
1. 12
1.50
I-S3
1.20
1.50
,.56
1.28
1.50
1.60
1.36
1-55
1.72
143
1 .60
1.76
1.50
1.67
1.85
1.64
i.r,7
1-95
177
1.70
2.05
1.90
..76
'Til
In loop eyes the distance of the inner point of the loop from
the centre of the pin must not be less than three (3) times the
diameter of the pin. The loop must fit closely to the pin
throughout its semi-circumference.
Pin holes in eye bars shall be bored to an exact size and dis-
tance, and to a true perpendicular to the line of stress. No
error in the length of bar exceeding one sixty-fourth (,.'4) of an
ORDINARY IRON II IGIIW AY-BRIDGES.
21
irdcrs. — In
I plate <;-ird-
bout two (2)
be found at
/ets between
e (lilference
he rivets be
) diameters,
lind tlie pin-
or diameter
id be eorre-
le amount is
he pin holes
mc
h will be allowed, nor
ROSS Pin.
Hammered.
1.50
1.50
'•S3
1.56
1.60
1.72
1.76
1.8s
1.9s
2.05
2.21
the loop from
(3) times the
<f to the pin
size and dis-
f stress. No
irth (ji'^) of an
#
J variation of more than one thirty-
secon.d {^.,) of an inch between the centre of the eye and the
centre line of the bar.
J'iiis. — Pins are to be proportioned to resist the greatest
bending produced in them by the bars or struts which they
connect.
Steel pins are also to be proportioned for shearing.
No pin is to have a diameter less than eight-tenths {-^^) of
the depth of the deepest bar coupled thereon ; nor shall it vary
from that of the eyes of the bars coupled theretc by more than
one-fiftieth (r,^,) of an inch.
The least allowable diameters for chord pins are two (2)
inches for bridges of Class A, and one and a half {\l) inches
for those of Classes B and C. The least allowable diameter for
pins belonging wholly to the lateral systems of bridges of any
class is one and a quarter {\\) inches.
J'iii Baviiigs.— AW pin holes through webs shall be re-en-
forced by additional material, so that the permissible pressure
upon the bearings shall not be exceeded. Where a pin bears
against a re-enforced channel bar, the web of the latter is not to
be assumed to take any bearing-stress, unless the re-enforcing
plates be riveted to it before the pin-hole be bored.
Chord I\ickii/o^. — The lower chords are to be packed as
closely as possible, and in such a manner as to produce the
least bending-moments upon the pins. The various members
attached to any pin must be packed as closely as possible, and
all interior vacant spaces must be filled with wrought-iron
fillers.
Rxpaitsion Rollers. — Expansion rollers for bridges of Class A
are to be proportioned by the formula
/ = 0.25^^7,
and those for bridges of Classes B and C by the formula
/ = o.3i25V'^,
where p is the working-load in tons per lineal inch of roller, and
d is the diameter of the roller in inches.
22
OKD/XAKV /h'OX IIICinVA V-IIK/IHUCS.
The least allowable diameters for rollers are one and three-
quarters (\\) inches for bridges of Class A, and one and a half
(I 1) inches for bridges of Classes H and C. The spaces between
roflers must ne^■er exceed three-quarters (|) of their diameter.
Ttini niickhs iiiid Slave Nuts. — All turn buckles and sleeve
nuts must be made so strong, that they will be able to resist
without rupture the ultimate pull of the bars which they con-
nect, and without distortion, the greatest twisting-force to which
they could ever be subjected. U-nuts are not to be used in any
part of a bridge.
Sizes of Xiits. — The dimensions of all scpiare and hexagonal
nuts for the various diameters of rods are to be taken from
Carnegie's "Pocket-Companion" (pp. 130, 13 1), excepting those
nuts on the ends of pins which are subject to but a slight ten-
dency to sheir the thread : in this case, these dimensions may
be diminished, in direct [iroportion to this tendency, until the
thickness reaches the limit of one-half (i) of an inch.
Washers ami Xiits. — Washers and nuts must have a uniform
bearing. Cast-iron washers must be used under the heads and
nuts of all timber bolts, when the bearing is on the wood.
Beam Ilai/oers. — Whenever possible, four (4) beam hangers
per beam are to be used. The screw ends are to be provided
with check nuts.
y^,j,y. _ Great care must be taken, ii designing jaws for the
ends of any strut, that they be so strong in every respect, that,
when the strut is subjected to its ultimate load, it will fail near
the middle rather than at the ends.
Bnnkets. — Brackets, or knees, must be used to connect each
overhead strut to the posts or batter braces. They should be of
straight tee, angle, or channel iron : if made curved, no depend-
ence is to be placed upon them, either for strength or stiffness.
When there is no vertical sway bracing, each intermediate
bracket must be proportioned to resist the compression induced
in it by the wind pressure concentrated at the windward and lee-
ward points of that panel of the top chords to which the bracket
belongs; and each portal bracket, to resist the compression
induced in it by one-half of the total wind pressure concentrated
at the panel i)oints of the top chords.
^
'i
■*
OKD/XAK ) ■ /A'O.y I IK /// W.W '-H RIDGES.
23
ul IiL'xaL^onal
taken from
opting those
a sliij;ht ten-
ensions may
:y, until the
h.
ve a uniform
le heads and
I wood,
leam hangers
be provided
jaws for the
respect, that,
will fail near
connect each
J should be of
d, no depend-
I or stiffness.
intermediate
bsion induced
ward and lee-
h the bracket
compression
concentrated
Cut tins; off the I'laiigcs of Cliatincls. — The llanges at the ends
of channel bars must not be cut away, if it be practicable to
a\()i(l doing so : if not, there must be sufficient re-enforcing
used to make the strut as strong as it would have been with
the flanges uncut.
Sizes of /■'/ooriiig and Joists. — Pine flooring is to be at least
tiirec (,^) inches thick, and oak flooring at least two and a half
(j.i) inches thick. It is to be laid with close joints, anil well
spiked to each alternate joist with two (2) seven (7) inch cut
spikes. Consecutive boards should not be spiked to the same
joists.
Joists are to be proportioned by the formula,
JF =
ch
where W is the safe uniformly distributed load in tons, b the
hreadtli of the joist in inches, d the depth of same in inches,
/the length in feet, and c — 16 for jjine and 1 1.5 for oak.
Where the greatest load is a concentrated one, it is to be
considered as supported equally between the joists directly
under the wheels and those contiguous to the same ; i.e., the
wheels on one side of a wagon are supposed to be placed
directly over a joist, which joist is assumed to take half their
load, the remaining half being equally divided between the two
adjacent joists. All concentrated loads must be reduced to
equivalent uniformly distributed loads in respect to deflection
by multiplying them by one and si.\-tenths (1.6) before applying
the formula.
Wooden Hand Rails, etc. — Wooden hand railing is to be
made of pine, the posts being 4" X 6" X 4', with two runs of
2" X 6" timbers — one on its flat, and the other below on edge to
support the first for a hand rail — and one run of 2" X 12" hub
plank. The latter and the lower run of 2" X 6" timber are to
be let into the posts to their full depth, and spiked to the same
with five (5) inch cut spikes ; and the posts are to be halved
on the outer joists, to which each one is to be bolted by two
(2) three-quarter (|) inch bolts.
Guard rails are to be of C" X 6" pine, bolted to each hantl-
24 ORDINARY JRU.X lUCllW AY-BRIDGES.
rail post, and to the floor once in, at most, cvc-ry five (5) feet,
by three-quarter (|) inch bolts.
When there are no wooden hand-rail posts, the guard rails
must be bolted through joists placed symmetrically below them,
care being taken that there be no bolt within two (2) feet of the
middle point of any joist.
The joints in the guard rails are to be lap joints, six inches
long, and are to have a bolt passing through the middle of each
lap.
About every eighth or tenth plank, there is to be a crack left
between flooring boards to let the water run through : this
crack should be less than a quarter (|) of an inch in width.
Should it be considered desirable to elevate the guard rails
in order to let the air and water pass beneath, it is to be accom-
plished by inserting hard-wood shims — one (1) fool long by two
(2) inches deep, and six (6) inches wide — beneath the guard rails
at each bolt hole ; the bolt passing through the middle of the
shim, and each shim being fastened to the floor by four (4) five
(5) inch cut spikes.
Ii'ou Hand Railing. — Bridges with sidewalks v.-ill not require
the wooden hand railing inside the trusses, but are to be pro-
vided with a neat, substantial iron hand rail on the exterior of
each sidewalk. It is to be rigidly attached to the floor beams
and exterior sidewalk joists.
Details not prcvionsly Mentioned. — Finally, as regards the
proportioning of any structure, if cases should occur which are
not covered by the preceding specifications, the following rule
is in all such cases to be adhered to : " Details must always
be proportioned so as to resist every direct and indirect stress
that may ever come upon them under any probable circum-
stances, without subjecting any portion of their material to a
stress greater than tlie legitimate corresponding working-stress."
Cast-iron. — No cast-iron is to be used except for washers
for timber bolts, and for ornamental work and name plates.
Name Plates. — The names of the designer and the manu-
facturer of the bridge must be attached thereto in a prominent
position and in a durable manner.
Field Riveting. — I-'ield riveting must be done with the button
OND/X.INV /KOX IIIGHU'AY-IiRinGES.
!5
•egards the
r which arc
or washers
1 the button
sett. The heads of the rivets must be hemispherical, and no
rou<;ii edges must be left.
Paiutiiii^. — i\\\ finished work, before leaving the shop, shall
he thoroughly cleaned from all loose scale and rust, and covered
with one good coat of pure boiled linseed-oil well worked into
all joints and open spaces. In riveted work all surfaces coming
into contact shall be painted before being riveted tofether.
Ik'd plates, and all parts of the work which will not be acces-
sible for painting after erection, shall have two coats of paint.
i'ins, i)orcd jjin holes, and turned friction rollers, shall be
coated with white lead and tallow before being shipped from
the shop.
After the structure is erected, the iron-work shall be cleansed
from mud, grease, or any other objectionable material that may
be found thereon, then thoroughly and evenly painted with two
coats of jiaint mixed with pure linseed-oil, of a color pleasing to
the eye ; the tension members being generally of a lighter shade
than the compression members.
Wherever it be possible to so design it, the iron-work must
be made accessible to the paint-brush.
Tititbcr.— KW timber is to be of the best quality, free from
wind-shakes, large knots, decayed wood, sap, or any defect that
would impair its strength or durability.
Quality of Workmanship. — All workmanship is to be first-
class ; abutting joints are to be truly planed and dressed, so
as to insure a perfect bearing ; the pin holes in chords, batter
braces, and posts, are to be bored as truly as is specified for the
eye bars ; and there are no rough edges or corners to be left on
the iron-work.
15ars which are to be placed side by side, or in similar posi-
tions in the structure, shall be bored at the same temperature,
and of such equal length, that, upon being piled on one another,
the pins shall pass through the holes at both ends without
driving. Whenever necessary for the protection of the thread,
provision shall be made for the use of pilot nuts in erection.
Quality ami Tests of Materials. — All wrought-iron must be
tough, fibrous, and uniform in character. It shall have a limit
of elasticity of not less than twenty-six thousand (26,000)
pounds per square inch.
26
OA'V/X.lA'i' /A'O.V HlCllUAY-llRIDGES.
Il:
Finished bars must be thoroughly welded during the rolling,
and free from injurious seams, blisters, buckles, cinder spots, and
imperfect edges.
lu)r all tension members the muck bars shall be rolled into
flats, and again cut, piled, and rolled into finished sizes.
They shall stand the following tests. Full-sized pieces of flat,
round, or square iron, not over four and a half (4,}) scjuare inches
in sectional area, are to have an ultimate strength of fifty thou-
sand (50,000) pounds per scjuarc inch, and are to stretch twehc
and a half (12.]) per cent of their whole length.
Bars of a larger sectional area than four and a half (4^) square
inches arc to be allowed a reduction of one thousand (i,ooo)
pounds per square inch for each additional square inch of sec-
tion, down to a minimum of forty-six thousand (46,000) pounds
per square inch.
Specimens of a uniform section of at least one (i) square
inch, taken from bars of four and a half (4]) square inches sec-
tion, and under, are to have an ultimate tensile strength of
fifty-two thousand (52,000) pounds per square inch, and are to
stretch eighteen (18) per cent in eight (<S) inches.
Similar specimens from bars of a larger section than four and
a half (4.^) square inches are to be allowed a reduction of five
hundred (500) pounds per square inch for each additional square
inch of section, down to a minimum of fifty thousand (50,000)
pounds per square inch.
Similar sections from angle and other shaped iron are to have
an ultimate strength of fifty thousand (50,000) pounds per
square inch, and are to stretch fifteen (15) per cent in eight (8)
inches.
All iron for webs of plate girders is to have an ultimate
strength of not less than forty-six thousand (46,000) pounds
per square inch of area of test-piece, and is to have a minimum
elongation of ten (10) per cent in eight (8) inches.
Rivets are to be of the best quality of double refined iron.
The cast-iron must be of the best quality of soft gray iron.
Test of Structure. — On the completion of the entire struc-
ture, any bridge, after being in constant use for one day, may
be tested by a load equal to that for which it was designed
O/v'DLV.l/CV /A\hV n/GI/WA V-nN/DGES.
27
remaining upon it for at least one hour, then removed, and
placed upon it again. The first removal of the loatl may show
a little permanent set ; but, when the second load is ap|)lied,
the total deflection must not be any greater than it was for the
first loading, and upon its removal the bridge must return to
the exact position which it occupied after the removal of the
first loading.
28
ORD/XA N 1 ' //.'( ^\' ///( /// U'.n -/}N/1)(.;ES.
CHAPTER III.
T.IST OK MF:M1!KRS.
In the followinj; list of momliors will be found the names of
all the parts, both of wood and iron, in the bridj^es with wliich
this treatise deals. Its use will be explained in Chapter XIV.
It is inserted here so that those unacquainted with bridf;e
designing; may inform themselves as to the names of all the
parts of a bridge before proccedin<; farther. This they can do
by consultinj;- the Cilossary, and referring; to the i)lates there
indicated. The author would advise students, before proceeding
to Chapter IV., to study closely Plates I. -IV., so as to obtain a
general idea of how bridges are constructed.
LIST OF MEMBERS IN A WROUGHT-IRON HIGHWAY-BRIDGE.
M.MN PORTIONS.
Channel Bars. — Top chords, batter braces, bottom chords,
posts, upper lateral struts, end lower lateral struts, upper portal
struts, lower portal struts, hip verticals in pony trusses.
Plates. — Top chords, batter braces.
I-Beams. — Floor beams, intermediate struts, end lower lateral
struts, bottom chords.
Bars and Rods. — Main diagonals, counters, hip verticals,
upper lateral rods, lower lateral rods, vibration rods at portals,
vibration rods on posts, chord bars.
Angle Iron. — Side bracing, end lower lateral struts.
Iron hand railing.
Floor beams.
DET.\ILS.
Stay Plates. — Top chords, batter braces, ends of posts, mid-
s.
( >A-J)/X. IRV /A'O.V 1 Hi.: nil -A J -liKt IHlllS.
-9
he names of
s with which
hapter XIV.
with brid<;c
»s of all the
they can do
plates there
■e proceeding;
s to obtain a
\Y-BRIDGE.
ttom chords,
upper portal
isses.
lower lateral
u|) verticals,
Is at portals,
uts.
)f posts, mid-
dle of i)i)sts, bottom-chord channels, upper lateral struts, end
lowrr latt'ral struts, up])er portal struts, lowrr portal struts.
Ri-iiifoiriiii^ and Coiuuctiiii^ or SI'Hcl- /Wit^s. — Hip inside, Iiip
outside, top-clinrd intermediate jiaml points inside, top-chord
iiilerniediate panel points outside, holtoni-tliord struts at shoe,
l)ottom-ch()rd struts at first panel points, shoe inside, shoe out-
side, lower enils of posts insiile, lower ends of jiosts outside, mid-
dle of posts inside, middle of i)osts outside, lateral struts U) to|)
ihoids, up|)er portal struts to batter braces, lower portal struts
to hatlL'r braces, portal struts to brackets and name plates,
iiitennediate struts to posts, side bracinuj to floor beams, end
lower lateral struts to pedestals.
(\nrr P/atis. — Hip joints, joints at intermediate panel points
of to|) chords.
I'i/liiii^ Plates. — Hips, intermediate panel points of top chord,
over end floor beams, between pedestals and lateral struts.
ICxtension plates at upper enils of posts, shoe plates, roller
plates, bed plates, beanvhanger jilates, name plates.
/,(?(-///i,'- or Latticing. — Top-chord channels, batter-brace chan-
nels, bottom-chord channels, post channels, upper lateral strut
channels, end lower lateral strut channels, upper portal struts,
lower portal struts, hip verticals in pony trusses.
y'/v/.ovV/i,'-. — Hip verticals in pony trusses, lower-chord bars.
/V//.S-. — Top chords, bottom cliords, middle of posts, lower
lateral rod connection to jaws, vibration-rotl connection to upper
portal and lateral struts, vibration-rod connection to lower portal
struts, between floor beams and beam-hanger plates.
Bolts. — Brackets to portal struts and lateral struts, brackets
to batter braces and posts, name plates to jwrtal struts, vibra-
tion rods to lateral struts, vibration rods to intermediate struts,
bed plates to piers (anchor bolts), shoes to bed plates, expansion
pedestal connection to bed plates, portal struts to batter braces,
iiand-rail posts to joi.sts, lower lateral struts to floor beams,
lower lateral struts to jaws, felly planks to floor and hand-rail
posts.
Brackets or Knee Braces. — Portal struts to batter braces,
upper lateral struts to posts, intermediate struts to posts.
Ornamental work at portals, beam hangers, expansion rollers,
30
ORDINARY IROX IllGllWlV-BRlDGES.
roller frames, fillers for pins, turn buckles, sleeve nuts, ronnect-
in^'-iiiord heads for bt)tl()ni chord channels, jaws for lateral and
portal struts.
Ati}^lc //vw. — natter braces to shoe plates, sides of roller
plates, ends of roller plates.
Picas of Chanmb. — Hearins for bent eyes of upper lateral
rods, bearinj; for bent eyes of lower lateral rods, batter-brace
connectioh o shoe plates.
Kivif Heads. — Tlate to chord and batter-brace channels, lat-
ticin-; or lacing to channels, latticing; to latticing, the various
stay plates to channels, the various connecting and re-enforcing
plates to channels, connecting plates to shoe plates, connecthig
plates to intermediate struts, connecting plates to side bracing
and floor beams, connecting plates at pedestals to pedestals and
lateral struts, cover plates to chords, extension plates to posts,
trussing to hip verticals and posts, trussing to chord bars, orna-
mental work to portals, brackets to posts and batter braces,
brackets to portal, lateral, and intermediate struts, components
of jaws to each other, angle irons to shoe plates, angle irons to
roller plates, the various pieces of channels to the parts which
they connect.
5y,//vx — Flooring to joists, hand rails to posts, hub planks
to posts, felly planks to flooring, joists to lower lateral struts,
jaws to lower lateral struts.
Waslicrs. — Hand-rail post bolts, bolts connecting lateral struts
to floor beams, felly-plank bolts.
^\^/^/.s-. — On pins, on bolts, on beam hangers, lock nuts on
beam hangers, pilot nuts.
Details for a Built Floor Beam. — Web, upper-flange angles,
lower-flange angles, top plate, bottom plate, stiffening angles,
filling plates, re-enforcing plates at beam-hanger holes, rivet
heads.
Details for a Trussed Beam. — Rolled I-beam for upper chord,
lower-chord bars, end diagonals, counters, I-beam posts, con-
necting plates for posts to beam, re-enforcing plates at feet of
posts, pin plates for end diagonal connection to beam, stiffeners
at supports, pins and nuts on same, fillers, turn buckles or
sleeve nuts, rivet heads.
lateral struts
lock nuts on
0/\/)/.y.lA-r /I'lKV Jl/UJ/lfA V-IiKUHiLS.
31
f.iniil'tr. — Joists, flooring, hand-rail pieces, hand-rail posts,
lull) planks, felly planks or guard rails, lower lateral struts.
es of roller
DI/PAILS roR A SPAN COMI'OSED OK PI.ATK (ilROKKS.
Webs, upper-flange angles, lower-flange angles, top plates,
bdttoin plates, stiffening angles, filling plates, angles for lateral
braces, connecting plates for lateral braces, shoe plates, bed
plates, anchor bolts and nuts, rivet heads.
32
OKDL\AJ<]- JNO.X HluUWA V-HRlDuES.
CHAPTER IV.
LIVE AND DEAD l,( )ADS.— WIXD PUKSSURE.
As stated in Cliaptor 1 1., lii^Ii\vay-liri(ls;os are divided into
throe elasses, A, B, and C, whieh arc res])ectively for loeations
where the loads are heavy and of frequent oecurrenee, loea-
tions where the loads are occasionally heavy, and locations
where the loads are li_nht.
After deeidinj;' ui^on the lenfjth of sjian, width of roadway,
and class of hridi;e for any location, the live load per s(|uare
foot of floor is to be taken from the table on p. 5. The reason
why lont; sj)ans maybe proportioned for lii;-hter loads than short
ones is the very small probability of a loni;- span e\er beini;'
covered bv the maximum loatl, while there is a chance of sucii
ai. event takinj;' place in case of a short span.
It can easily be seen, then, that, in all bridt^es of any hiirth
of span, each jianel should be proportioned to sustain the maxi-
mum load ; for it is possible to load one panel heavily without
loadin^f any of the others.
This panel excess will affect only the sizes of the joists, floor
beams, beam hangers, and hip verticals. Sometimes the jxinel
excess is sup})osed to exist when the bridt;e is partially or
wholly covered by the movinj;' load, thus aflectin,<4' all the main
membei-s of the trusses ; but this is too nnich letinement for
highwav-bridt;e desii;-ninL;'.
The dead load per lineal foot is to be taken from one of
Tables 1., II., and III., if there be no special loadin<j: such as
that tlue to snow, if the style of hantl railini;-, i;uard rail, etc.,
for the bridj^e to be designed, corresiiimd with that adopted in
this work, if the wiilth of roadway correspond with one of those
in the table, and if the length of the siian be exactly divisible
(>A'/)/x.iA'y /A'o.v J //amy A y-/uu/)g/':s.
Zl
divided into
' for locations
iirrcnce, loca-
and locations
1 of roadway,
d per sc|uare
The reason
ids than short
n e\er Ikmiil;'
lance of sucli
of any hiii'ih
;ain the maxi-
.'avily without
le joists, floor
nes the panel
■; partially or
;■ all the main
^'tinenient for
from one of
idinii; such as
lard rail, etc.,
It adopted in
1 one of those
actly divisible
by Icn. If either or both of the last two conditions be not
fulfdled, the dead load is to be directly interpolated ; then if
there be any difference in the lumber, or any special loadin<,^.
the effect of the chan.i^e or changes is to be calculated by the
method to be explained presently.
The weiurhts of iron and lumb
LT given in Tables I., II., and
III., are the results of calculations for the bills of materials of
sixty bridges, so chosen in respect to length of span, and width
e weights vary
e most eco-
(if roadway, as to indicate the laws by which th
with these dimension.s. All the bridges are of th
nomic (le
\\\
th t
ie (hm
fiv
e colunms un
pth and panel length, corresponding in these respects
ensions given in Table IV. The figures in the
weights
ems, and floor
Jot, not includinj
der each roadway gi\e respectively the
of iron per lineal foot in the tru.sses, lateral syst
system ; the weight of lumber per lineal fo
was
te; and the dead load per lineal foot, corrected for the small
amount resting on the i)iers.
To find the dead load for any span where there is to
increased weight of floorinf:, or
be
an
an additional load, find th
value for the weight of lumber (proportioning the ioist
methoi
n\
WCl
■hs t
en in Chapter IX., remembering that
e new
by the
pine lumber
wo pounds and a half per foot, board measure, and oak
lumber four pounds and a thirtl), then that of the fl
by the formula
oor system
where F' is the weight per foot of the floor system required, F
that of tiie floor system given in the table, ami r (greater than
unity) the ratio of total loads on floor beams in the two cases
considered.
Next assume T\ the new value for the weight T m the truss
column, and find the ratio ;-' (greater than unity) of total loads
per foot on trusses in the two cases ; then
If the value of T' thus found agrees with that assumed, all right ;
'1 not, It will be necessary to try again until it does agree.
34
ORDINARY IRON HIGHWAY-BRIDGES.
Next add together the differences between T' and T, between
F' and F, and between the weights of lumber per lineal foot.
To the sum of these differences add the weight of snow or
other special loading per lineal foot of bridge, and the dead
load taken from the table. The final sum will be the dead load
required.
To find the dead load for a bridge with sidewalks, look in
the table of the class to whicli the bridge belongs, and find the
weights for a bridge of the same span and roadway without
sidewalks, then estimate the increments of these weight." as
follows : —
First, the weight of lumber per lineal foot on the sidewalks
is to be calculated ; and from it is to be subtracted twenty-four
pounds, which is the weight per foot of the wooden hand rails,
hub planks, and hand-rail posts (lumber not required when there
are sidewalks). The difference will be the increment for the
"lumber" column.
The increment for the " lateral system " column will be zero :
that for the " floor system " column can be found approximately
by the formula
/ =
2bF
where / is the increment required, F the weight per foot of
floor system taken from the table, b the sum of the widths
of the sidewalks, and /; the clear width of main roadway.
The increment of the "truss" column is found by assuming
the dead load required, and calling it W'l,.
Let
IVa = tlie dead load given in the table,
p^ _ the live load per lineal foot on the main roadway,
Pi, = that on the sidewalks ;
then
Let
Pa + //;,
T„ = the truss weii^lit from the table,
7), — the new iriiss weit;ht ;
ORDINARY IRON HIGH WAY-BRIDGES.
35
then
1 roadway,
s.
Ty
^(-
^{ Pa\-P l,-^Wt)\
and the increment will be T/, — T„-
Next add /F„, the three increments found, and the weight
per lineal foot of the iron hand rails : the sum will be the dead
load required. If it agrees with the assumed load IVt, all right ;
if not, another trial for the new truss weight is to be made.
There is one case in which this method would give too trreat
a result : it is that of a pony truss with side braces, of which
the only representative in the tables is the sixty-foot span. To
apply the method to this case, it will be sufificiently exact to
use the weight of floor system of the fifty-foot span, because the
floor beams of the sixty-foot span project beyond the trusses.
This change being made, the method can be otherwise followed
exactly.
The full double horizontal lines in Tables I., II., and III.,
divide the single from the double intersection trusses.
All the bridges in Table III. lying to the left of the double
vertical line which separates the twenty-two-foot and twenty-
fnur-foot roadways, have stiffened end panels. The correspond-
ing lines of division in Tables I. and II. separate the twenty-foot
and twent}-two-foot roadways.
The weights of iron in Tables I., II., and III., do not include
tlw 'u'cig/it of the spikes.
It is seldom necessary to make an allowance for snow load in
bridges of Class C, but it may be advisable to do so in bridges
of Classes A and B; for, after a heavy snow-storm, the travel
nn country roads would be light, which would not necessarily
the case in a city or its suburbs. The proper allowance
snow load should be from ten (lo) to thirty (30) pounds
er square foot of floor ; according to climate, locality, proba-
bility of greatest live load occurring simultaneously with the
.siKJW load, etc.
As stated in Chapter II., the wind pressure assumed is forty
(40) pounds per square foot for spans of one hundred (100) feet
and under, thirty-five (35) pounds for spans between one hun-
dred (100) and one hundred and fifty (150) feet, including the
36
ORDINARY IRON HIGHWAY-BRIDGES.
latter, and thirty (30) pounds for all greater spans. It is true
that actual wind pressures do occasionally exceed these amounts ;
but in view of the fact that the chance of any one bridge ever
being subjected to such pressure throughout its whole length
is extremely small, and that it could receive once in a while
a far greater pressure without suffering material injury if tlic
bridge' be properly designed, it seems legitimate to adopt the
pressures assumed.
Moreover, when a highway-bridge is blown down, the actual
loss is seldom much greater than the cost of a new bridge.
Travellers can cross the stream at the nearest bridge above or
below, until the structure be replaced. And the fall of the bridge
need involve no loss of life : for, in the f^rst place, no human
being would be likely to be upon it in such a storm ; and, in
the second, if there were, he could not escape being dashed to
pieces or blown off, even if the bridge were sufificiently rigid
to withstand the pressure.
With railroad-bridges, of course, it is a very different matter.
The delay caused by the loss of such a bridge may be much
more expensive than the replacing of the structure. Besides,
railroad-bridges are subjected to the greatest wind pressure
when covered by a train ; so that the fall usually involves the
loss of human life.
If the lateral systems of highway-bridges were ^o be made as
strong as those of railroad-bridges, unstiffened eye-bars could
be very seldom employed for the bottom chords ; because the
compression there due to the wind pressure would be far in
excess of the tension due to dead load (%ndc Appendix I.).
Even with the pressures assumed, it is necessary to rely upon
the stiffness of the joists to prevent buckling the bottom chords
of at least two-thirds of the iron and combination highway-
bridges in the United States.
It is not necessary to add any area to the section of the bot-
tom chords to resist the tension due to wind pressure, unless
this tension exceeds that due to the live load multiplied by
the ratio of the intensity f)f working tensile stress in lateral
systems to that of working tensile stress in chords. Should it
so exceed, the chords should he proportioned to resist the wind
ORDLXARV IRON HIGHWAY-BRIDGES.
37
stress plus the dead-load stress multiplied by the aforesaid
ratio, using an intensity of seven and a half (/.]) tons, or, in
case of stiffened eye-bars, six and a half (6^) tons. This ex-
cess should be looked for in narrow bridges in unusually
exposed situations, in the design for which the wind pressure
has been increased ten (lo) pounds per square foot.
I-\)r this same reason, of there being no probability of a live
l(md remaining upon a highway-bridge during a heavy storm,
the effect of the wind upon posts and batter braces may be
neglected, unless the stresses produced thereby exceed those
due to the live load multiplied by the ratio before mentioned ;
in which case the wind stresses should be multiplied by the
reciprocal of this ratio, and to the product should be added
the dead-load stresses, in order to find the greatest stresses for
which to ])roportion these members. As before, this excess is
to be looked for when the assumed wind pressure has been
increased by ten (lo) pounds per square foot: it will probably
be only the lighter posts that will be so affected.
l^ut the bending effect of the wind pressure upon portal and
latL'ral struts, when no vertical sway bracing except brackets is
used, should always be provided for.
The author believes, that, instead of designing highway-
bridges in ordinarily exposed situations to resist the greatest
recorded wind pressure in the district, it is better to run a
little risk of losing a structure than to make all the britlges
so much more expensive. Nevertheless, he wishes it to be
distinctly understood, that, in advocating the adoption of com-
paratively low wind pressures, he does not countenance the
buikling of such miserable apologies for lateral systems as one
rinds in the majority of highway-bridges.
38
ORDINARY IROX HIC-lIW'AV-liRIDGKS.
CHAPTER V.
STRKSSKS IN TRUSSES.
The length of span having hecn decided by considerations of
both necessity and economy {vide Chapter XV.), and the width
of roadway by the requirements of travel, there remain to be
determined, before making out the diagram of stresses, only
the style of intersection, panel length, and depth of trusses.
These matters are fully treated in Cluipter XV. Meanwhile,
the style of intersection may be settled by remembering that the
single is more expensive than the double, and that the inferior
limits of the latter for the different classes of bridges and differ-
ent clear roadways are given in the table on p. 8. The most
economic panel lengths and depths of truss for locations wliere
long timber is expensive, and, in fact, for nearly all locations,
are to be taken from Table IV. For locations where long tim-
ber is very cheap, there can be made a little saving in the
iron-work by using Table V. instead of Table IV.
As is customary in figuring stresses, uniformly distributed
loads are to be considered as concentrated at the panel points;
and the half-panel load at each end of the truss is not supposed
to produce any stress in any member of the truss.
The first step in making a diagram of stresses is to fill out
one of the following tables of data : —
Single Intersection.
11 —
d =
diag. =
sec Q =
iLMM.E ISTEUSECTION.
Doi'Fii.E Intersecticin,
;n Number of Panels.
odd Number of I'.uicls.
n —
n =
/ =
/ =
d=.
d =
short diag. =
short diag. =
long diag. =
long diag. =
OKJ)/XAKV /NOX lllClllVAY-nRIDGES.
39
Doi'dLlv iNTKHMiCTlON.
DoimtR
iNTF.RSKCTinN
SlMiLE iNTEK-iKCTlON.
Even Niinitjcr of i'aiicls.
Odd Number of I'anek
tan B =
sec a =
sec a = ;
w =■
tan u =
tan a =
IV, =
sec ft =
sec ft =
IV" =
70 =
TV =
IV' =
^F,=
PV,=
I
JF" =
IV" =
n
IV' =
IV =
- w sec =
w
I
1
~ 7V =
n
n\ sec =
U/;sec6 =
I
- 70 sec « =
n '
'/r"tane =
^ /F" tan 6 =
?Fj sec « =
I U\ sec « =
I
- IV sec « =
11
- 7S.I sec i8 =
Uv,
sec« =
IV, sec j8 =
\ n\ sec /3 =
- 7v sec fl =
]V" tan <« =
^ff'tan« =
n '
sec /3 =
-■ W" tan « =
is to fill out
where ;/ is the number of panels in the span, / the length of
each panel, d the depth from centre to centre of chords, b the
inclination of the diagonal ties in the single-interspction truss
to the vertical, a' the live panel load in tons on one truss (i.e.,
one-half the ]:)roduct of the live load per foot by the panel
length, or one-half the product of the clear roadway by the
l);incl length by the live load per square foot in pounds, all
divided by two thousand), W, the panel dead load on one truss,
W" — III + //'j, IV" the portion of H\ concentrated at the upper
panel point, « the inclination of the short diagonal ties in double-
intersection trusses to the vertical, and ft the inclination of the
long diagonal ties in same to the vertical. The value of If" is
usually between one-foiuth and one-third of /f'j: by taking it
always eqtial to one-third of Jl\ a small error on the side of
safety will be made in designing short spans.
Having filled out the table of data, the next step is to draw a
40
ORDINARY IRON H/GHWAY-nR/DGES.
skeleton diagram large enough to contain all the stresses and
sections. It is not necessary that the diagram be drawn to
scale ; but the ratio of panel length to depth of truss on the
diagram, for the sake of appearance, should not vary too greatly
from the ratio of the actual values of these dimensions. A
panel length of an inch and a half, and a depth of two inches
and a half, are about as small dimensions as will be found con-
venient.
At each lower panel point write lightly in pencil, so th^t it
can be afterwards erased, the number of the panel point, begin-
ning with zero at the right-hand end of the span.
It is well known, and will be accepted here without proof,
that the greatest stresses in the chords and batter braces occur
when the bridge is entirely covered by the moving load ; that
the greatest stress in any diagonal exists when the live load
extends to its foot from that end of the bridge towards which
the diagonal points in a dimiiu'a ni (Xnccixon ; that the greatest
stress in any post occurs when the main diagonal (or, if there
be none, when the heaviest counter) attached to its up[)er end
receives its greatest stress ; and that the two diagonals of a
panel cannot at the same time be subjected to the same kind
of stress, excepting, of course, the initial tension.
It is apparent that when the greatest stresses in all the
diagonals sloping upward in one direction, and in all the posts
and chord panels on one side of the central plane, are found, the
greatest stresses in the diagonals shjping in the opposite direc-
tion, and in the |)osts and chord panels on the other side of the
central plane, can be immediately written. This fact is so well
known, that, in making a diagram of stresses, it is usual to write
the stresses on only one-half of the members of the truss.
First let us take a single-intersection through-bridge.
The greatest stress in any diagonal sloping upward from right
to left can be found by the formula
-(// + I ) sue & + { //
2 /I \ 2
')'K
sec 9,
where ;/ is the number of the j^anel point at the foot of the
diagonal. This formula is ai)plicable to counters as well as to
ORDINARY IRON HIGHWAY-URIDCEs.
41
main {liayonals. If the stress should come out negative, it
shows tiuit no counter is needed in the panel considered. It is
also applicable to the batter brace by putting (// — i) for ;/.
The stress in any post can be found by the formula
u liere ;/ (not less than "^ is the number at the foot of the post.
The stress in any panel of the top chord is given by the
formula
c z=. "'(^ ~ ^0
W" tan 6,
wliere ;/ (not greater than -^ is the number at the end of the
panel nearest to the centre of the bridge.
The stress in any panel of the bottom chord, except the one
at the end of the span, is given by the formula
r=l^jH^Zl^_L),r'tan^.
;/' having the same value as in the last formula. For the end
panel, the stress is the same as for the second panel.
As the values of '^, ^ sec ^, and //; sec ^, are given in the
table of data, the substitution in these formulas is a very simple
matter. ' '
The stress in the hip vertical is tc + .1 (weight of floor beam
plus a panel weight of lumber), neglecting the weight of the
Dcam hangers, end lower chord bars, etc., which is not worth
considermg. It is not necessary to calculate this stress ; for
the section required, or the size of the square bars, if that
shape be employed, can be taken immediately from one of
Tables VI., VII., or VIII.
Some engineers may object to using formulas for figuring
stresses : if so, the following method will give the same results
lor single-intersection bridges.
42
OA'/)/.\:iA'i- fh'(h\ //A/////'./ J'-/.'A'//>(;a\v.
I'ass ;i vcMtical plane through the middle point of the bottom
ehoni • all ihe dead loads to the ri-ht of this plane may be
c.nsidered to k<> to the li-ht-haml pier, and all to the left of
the plane to the leftdianii pier. Shonld there be a post at the
middle of the brid-e. the wei-ht at the foot is to be e.msidere.l
as halved, one-half goin- to each pier. Then the stress m any
main diagonal of the left-hand half of the bridge is to be f.mnd
by eommencin- at the ri-hthand end, and a.ldin- the nimd.ers
at the panel points until the foot of the diagonal eonsidered is
reached, multiplying the sum by Sc sec ^, and to the product
adding the number of panel dead loads between the central
plane and the panel point at the foot of the diagonal considered
(including the one at this point) multiplied by \\\ sec b.
Vox instance, in a ten-panel bridge, the stress in the end
main diagonal, the number at its foot being eight, will be
lO
(I + 2 + 3 + etc. .
The stress in a counter on the right-hand half of the bridge
will be found bv adding the numbers at the panel points
until the foot of 'the counter considered is reached, multiply
ing the sum by - «- sec /^ and from the product subtracting the
dead-load stress of the main diagonal which crosses the coun
icr Thus, in the ten-panel bridge, the stress in the second
counter from the centre in the right-hand half of the span, or
the one at the foot of the third panel point, is
The greatest stress in any post is found by adding W to the
vertical component of the greatest stress in the main diagonal
attached to its upper end ; thus, in the same bridge, the stress
in the first post from the left-hand end, or the one at the eighth
panel point, is
(x + . + 3-fctc.... + 7)"+(Jf + O^J^+^^'-
()A'/)/A:iA'y /NOX niCIIW.lY-lil^lDCES.
43
For the case of a middle post, the stress in one of the coim-
tiTs at the upper ^wA must be substituled for that of tlic .uaiii
(lia-onal ; thus, in the same bridge, the stress in tiie middle
post is
(I + 2 + 3 + 4),^ -\W, + W'.
btractiiii; tlie
The stresses ni the chords are to be found by the follow-in-
nu'thod : —
I'ass a plane throu{,^h the foot of the post at or nearest to the
mi. Idle of the truss, and take the centre of moments at this
loot. I-rom the moment of the re-action at the nearest end of
the l.ridj^a" subtract the sum of the moments of the pane 1 loads
(//'") lyinj; between the centre of u mci.ts and this end, and
divide the dilTerence by the depth of the truss. The result will
be the stress in the panel of the top chord nearest the centre
of the brid^^e : it will be some multiple of //'" tan e.
The stress in tiie panel of the bottom chord immeuiately
below will be equal to the one found, less the horizontal com-
|)oncnt of tile luaiit diagonal of the panel, when the brid<;e is
covered by the moving load. This horizontal component" will
be zero for a truss with an odd number of panels, anti .i //'" tan
lor a truss with an even number of panels.
The stress in the ne.xt panel of the bottom chord towards the
nearest end of the bridj^e Is found by subtracting from the one
already determined tlie horizontal component of the stress in
the main diagonal at the panel point between the two panels
considered ; the bridge, as before, being fully loaded. This com-
ponent is a multiple of W" tan 6. In this way can be found all
the stresses in the panels of the bottom chord, the correctness
of the work being checked by seeing if the stress in the end
panel be equal to the re-action multiplied by tan (i. If so,
the remaining upiier-chord stresses mav be at once written by
mspection; for the stress in the ;/th panel of the top chord,
counting from the nearest jjier or abutment, and supplying
the missmg panel at the end, is numerically equal to that in the
{it-\- i)th panel of the bottom chord.
It seems almost unnecessary to state, that the stresses in the
44
oNn/XAKV //COX ///<;// ivA y-/i/c//Hi/-:s.
top chords, hatter hraccs, and posts, arc compressive, and those
in liottom chords, main diagonals, counters, and hip verticals
tensile.
Next let us consider the double-intersection truss.
The formulas for this case are so complicated that it is better
not to employ them. The simplest method is to draw a skele-
ton diagram, and number the panel points, as in the single-inter-
section truss. The double-intersection truss really consists of
two trusses, as may be seen in the accompanying diagram.
D II i:t 11! 11 Id 1) a j ;■ » :< i :i j i u
Ah NlxM /I A -
fig. 3
IBM n 10 n i i i a
Such a division is necessary in order to calculate the chord
stresses when the truss contains an odd number of panels.
This is accomplished by finding, by the method of moments
already explained, the chord stresses in each of the trusses
shown in Figs. 2 and 3, and then combining them. Thus the
stress in panel 9-10 of the lower chord in Fig.i is equal to
that in panel 9-1 1 of Fig. 2, plus that of panel 8-10 of Fig. 3.
The live-load stress in any diagonal sloping upward from
right to left is found by noting whether the number at its foot
be" odd or even, then taking the sum of the odd or even
numbers, from one or two up to the number at the foot of the
to IV
diagonal, and multiplying the sum by - sec a, or - sec [i, as
the case may be.
The stress due to the dead load is found by taking the sum
of the same numbers, and from it subtracting the sum of the
odd or even numbers from one or two up to n — (//' + 2), where
;/ is the number of panels in the span, and // is the number at
the foot of the diagonal considered.
Whether the odd or even
OA'/>/.\:iA'y /A'6».v ///(,// n: I y-/,'/://h;/:s.
45
iiiimhns should he taki-n can he ascertained hy followinf? out
towards the left the system to which the dia^a)nal helon;;s : if
the system contain the short (lia;j;onal at tli.it end, then th.-
even nimihers arc to he taken, otherwise the odd ones.
The difference thus found, multiplied hy " ' '*'''-'" or ^^'''■' /^,
'/ //
as the case may he, will f,Mve the dead-load stress in the dia;;onal.
Thus, in the diagram, the dead-load stress in the main diago-
nal at the panel point lo is
[(2 + 4 4- etc. + io)-(i +3)]--
/F, sec /3
As in the case of the sinp;le intersection, the stress in a main
(liaj;-onal is equal to the simi of the live and dead load stresses ;
that in a counter, to the difference hetvveen its live-load stress
and the dead load stress of the main diaj,fonal crossin^^ it at the
middle of its len-^th ; that in a post, hy the sum of //" and the
vertical component of the Kix-atest stress in the main dia-onal
(or, if there he none, that in the principal counter) attached to
its upper end. As the hatter hraces helong to hoth systems of
triangulation, their stresses are the sum of the stresses found
hy each system, or hy the formula
C=[r + 2 + 3 -f- etc + (n - ,)]l^:±i51i££i.\
If the numher of panels he even, the calculation for the dead-
load stresses may he much simpliiietl hy coinitin-; the numher
nf panel jjoints on the system considered lyin^ hetween the
central plane and the panel point at the foot of the diagonal,
inchuling the latter, rememherin-,- th.at the load at the middle
panel is halved, and multiplying the result hv Jl\ hcc a, or
/r, sec/i.
The finding of the chord stresses is .also simplified when
there is an even numher of ixmels ; for they can then he calcu-
lated hy the method explained for the single-intersection truss.
In every douhle-intersection truss, there is neces.sarily a little
amhiguity ; for it is possihle that the whole of the load con-
■} 1*
46
ORDLXARV IROX IIIGIIWAY-BRIDGES.
centrated at the first panel point docs not travel by the sys-
tem of odd numbers ; but this ambiguity is a matter of small
moment.
The only difference between the stresses in a deck bridge
and those in a corresponding through bridge will be in the
posts, the stresses for which are to be found by letting the live
load extend from the farthest end of the bridge to the top of
the post ; so that the post will no longer take its greatest stress
with the main diagonal attached to its top, but with the one
attached to its foot.
The formula for post stresses in single-intersection deck
bridges is, therefore.
C =
t>'{jl' - I)+ 2
'i{^\ + [,,'-.'i±iyv,+w'.*
To find the stress in a post of a double-intersection deck
bridge, add ic, U", and the vertical component of the greatest
stress in the principal diagonal attached to its upper end.*
In designing bridges where there is an assumed snow load, tlie
counter stresses, and the post stresses produced by the counters,
should be figured without the snow load ; because, the greater
the dead load, the less the counter stresses,
In Carnegie's "Pocket-Companion," pp. 141-143. ^'ViH be found
tabulated the numerical co-efificients for the stresses in single-
intersection trusses having from three to twelve panels, and in
double-intersection trusses having from eleven to twenty panels.
The panel dead loads are supposed to be concentrated^on the
" * This method of finding post stresses is not exact, but gives an error on the side of
safety, varying from "- at the centre to zero at the ends of tlie span : it assumes the total
panel load «■ to pass down the i^ost before being divided into the portions which i>ass to
nglit and left, when in fact the portion going to the farther end passes down the main diago-
nals as compression. Tlie formula was uriginally obtained under tlie false assumption ; but
it has been retained for the following reasons : —
ist, There is a certain amourt of shock accomjianying the application of the panel live
load on the post ;
2d, The load w comin^^ from the floor beam is applied to one side of the axis of the
post, and consequently tends to produce a slight bending thereon ;
3d, The distribution of the excess of stress is favorable, being greatest for the light jxjsts
near the middle of the span, and smallest for the heavy ones near the ends.
ORDIXA R Y IRON HIGH WA J -BRIDGES.
section deck
47
bottom chords in through bridges, which will cause an error on
the side of danger in the post stresses : this fact is pointed out
on p. 141. A slight difference will be found between the co-
efficients there given for the diagonal and chord stresses of
double-intersection trusses having an odd number of panels,
.uul those obtained by following the method indicated in this
chapter. The latter will give stresses slightly in excess of
those in the "Pocket-Companion;" but the difference is so
small, that it is scarcely worth mentioning. Had the engineer
who ijrepared the tables been a believer in the use of long
panels, he would have commenced his douWe-intersection trusses
with seven panels instead of eleven.
Tables XLI. and XLII. give the stresses for all bridges
treated in this work.
rsection dec)
ion of tlie panel live
Ic of the axis of tlie
48
ORDLXAKY JRO.X HlGlilVA V-BRWGES.
CHAPTER VI.
STRESSES IN LATERAL SVSTEALS AND SWAY BRACING.
The wind loads concentrated at the panel points are deter-
mined by imagininjj; a horizontal plane passing through the
middle of the truss, and supposing that the pressure on all
the exposed surface of the bridge above this plane is concen-
trated at the upper- panel points, and all below this plane at the
lower-panel points. This may be a correct assumption, or
may not ; but it is as likely to be correct as any other.
Where vertical sway bracing is used, the di\'ision of wind
pressure becomes still more ambiguous ; but, as before, the
same assumption is as likely to be correct as any other.
In calculating the area opposed to the wind, the area of the
vertical projectit)n of one truss, hand railing, including hub
plank, guard rail, and the rectangles described about the
windward ends of the floor beams, is to be doubled, and to this
is to be added the area of the vertical projection of the floor
and joists.
As the windward hand rail would probably fail under high
pressure, the total area thus found is somewhat in excess ; but
such a failure should not be depended upon when the wind is
considered to strike the bridge suddenly. For spans of and
under two hundred, or sometimes even two hundred and thirty
feet, the sizes of the upper lateral rods are not to be determined
by the effect of the wind pressure, as this method would make
them smaller than experience would indicate to be necessary
for rigidity. The sizes to be used can be found in Table XXV.
The wind stresses on the lateral systems are to be calculated
for a moving load, instead of one upon the whole bridge ; because
this method causes the rods towards the centre of the span to
IRACING.
s are deter-
;hrough the
^sure on all
; is concen-
plane at the
u nipt ion, or
cr.
ion of wind
before, the
her.
area of the
:luding hub
about the
and to this
of the floor
under high
e.xcess ; but
the wind is
pans of and
d and thirty
' determined
would make
le necessary
rable XXV.
le calculated
Ige ; because
the span to
o/wj.v.iA'i- /AU)x uicnwAv-nRincEs.
49
he somewhat increased in diameter : besides, it is possible for
a portion only of a structure to be subjected to wind pressure-
the rest being protected by a hill, a building, or some other
neighboring object.
Without making any appreciable error, the wind pressure, for
the purpose of simplifying calculation, may be considered as
equally distributed between the two sides of the bridge, althou-h
the windward side does receive the larger share. "
The stress in any diagonal can be found by the formula
^ _ !i'(?i' + i) 7o sec e
and that in any strut, except at the end of the lower lateral
system, by the formula
C =
n\n ~ \) + n
271
•70,
wiiere r.' is the sum of the pressures at a wind
lanel point, // the number of panels in th
ing in the two lackiu"; at th
ivard and leeward
e wind bracing, count-
e ends of the upper lateral brae
m-r
in through bridges, ;/ ("not less th
lan
D
th
e number at the lee-
ward
end of the diagonal, or at eitl
panel pom
ler end of the strut, the
ts being marked as directed in the last chapter, and
't the angle that the diagonals make with th
1 he stresses in the diagon
tension, or, what is the same
e struts.
al
s are to be
th
increased for initial
)e taken from Tabic IX.
mg, the W(jrking-stresses are t
T
atl(
le ellect of the initial tei
led to the stresses in those member
sions on the struts is also
to bi
The method of calculating the st
resses in the vertical sw
bracing is as follows. It is essentially that of Profe<
;i\'en in his treat
In 1-ig. I, let J' be the
se on " Stresses in Brids
ay
ssor Burr, as
;eand Roof Trusses."
at the upper ])anel point on on
pressure supposed to be concentrated
wliic'h CO
e side of the brid-
mes upon a panel length of lop chord,
area o| the diaironals
:e'. It is that
one-haif the
tiun of the post above the plane A/>
meetmg at the panel point and th
por-
so
OA'D/.V.I A" 1 • /A'OA I i lull II :n -JIKJDGES.
Let P' be the pressure concentrated at one end of the inter-
mediate strut /A'. It is that which comes upon the portion of
the post between the planes AB and CD, the latter passing
halfway between the intermediate strut
and the bottom chords. If the interme-
diate strut be at the middle of the post,
and if the main diagonals and counters be
coupled on a pin at this point, it would
be necessary to divide the pressure upon
■ w**H the diagonals between the upper, middle,
and lower points of the posts ; the middle
taking one-half, and the others one-quarter each.
Let
d = the depth of the truss,
/= the vertical distance between the upper lateral and interme-
diate struts,
d = the perpendicular distance between centres of trusses,
and
6 = the ancle made bv the vibration rods with the vertical.
The pressures concentrated at the lowest points of the posts
do not affect the vertical sway bracing, so are not considered.
The total pressure, 2{P + /") = //, is assumed to be ec|ually
resisted by the feet of the posts. It is possible that this
assumption is incorrect, for one foot may resist more than the
other ; but, when it is remembered that perhaps the whole of
the force 2P passes through the upper lateral system to the
pedestals at the feet of the batter braces, it will be conceded
that the assinnption is not upon the side of danger.
If the whole of 2{P -f P') were to be resisted by the feet of
the posts, th(! functions of the upper lateral system would be
rather limited, the whole of the wind pressure upon the sliuc-
ture being carried by the lower lateral system, which is highly
improbable.
But, whether the wnnd pressure upon the upper part of the
trusses be carried by the ujiikt or by the lower lateral bracing, it
is better, as far as the vertical sway bracing is concerned, to pro-
portion the latter under the suj^position that the pressures at the
upper panel points are carried thereby to the feet of the posts.
ORDIXARY IKOX UIGHWAV-IiRlDGES.
5'
ral and interme-
Taking the centre of moments at E, the moment of the
pressure is
2Pd+ 2P\d-f), :
which can be resisted only by the moment of a released weight
/'upon the foot at /^; thus,
2Pd^2P\d-f)=.Vb,
and
y_ 2d{P^P')-2P'f
b
This release of weight V must pass up the vibration rod KG,
causing a tension therein equal to
,. „ 2d{P+ P') - 2P'f
Fsec 6 = ^ ^' Z. sec 6,
To find the stress on the strut /A', pass a plane through the
sway bracing, cutting GI/, GK, and /A' {/// not being strained);
take the centre of moments at G, and consider the forces act-
ing on the left side of the truss ; then the moment of the stress
In JK will balance the moments of P' and i//, thus,
(Ml =
\Hd-P'f d,^
^~^-^=jr{P^P')-P',
to which must be added the horizontal component of the initial
tension in///. {JK) represents the stress mJK.
The stress in the upper lateral strut GH is that due to the
wind pressure, considering it as a portion of the upper lateral
system plus the sum of the horizontal components of the initial
tensions in the three rods meeting at one of its ends.
If G/I be considered as a portion of the vertical sway bracing,
its stress may be found by passing a jilane, as in the last case!
and taking the centre of moments at K, considering the external
fcrces acting on the left-hand half of the truss ; then the mo-
ment of the stress in Gil will balance the moments of the
horizontal re-action at E and the pressure at G, the moment
of the increased weight at E balancing the moment of the
increased re-action ; thus,
or equal to the stress in /A".
[
52 ORDINARY IRON HIGIIWAV-HRI IK;ES.
At first thought, it might appear tliat the two stresses found
for GH should be added together to obtain the total stress ; but
such is not the case, for the wind pressures cannot pass by both
the vertical sway bracing and the upper lateral bracnig : so the
greater stress must be taken. In all practical cases, the greater
stress will be found by considering GH as belongmg to the
upper lateral system.
The bending moment on the post is
and, if m be the distance between centres of gravity of post
chamiels, the stress on one channel produced by the bending
^- III
The released weight V, on the windward post, passes down the
leeward post, producing a stress equal to y on each channel,
makinf^ the total wind stress on one channel
According to the method given in Chapter IV., if twice this
stress or 2C+ F, exceed the live-load stress on the post, mul
tiplied by seven and a half {jV), and divided by the intensity ot
working tensile stress for lower chords, the post must be pro-
portioned for dead-load and wind stresses, instead of dead-load
and live-load stresses.
All these formulas, except that for the stress in GH, may be
made applicable to the portal bracing by putting for d the length
of the batter brace, for / the perpendicular distance between
centre lines of upper and lower portal struts, for /" the press-
ure on one-half of the batter brace, and for P one-fourth of the
sum of all the pressures concentrated at windward and leeward
panel points of the top chord.
If Pi be the pressure at the leeward hip, then the stress on
the upper portal strut will be Ldvcn bv the formula
C='^(r+P')-^" + ^'-P''
OKDIXARV INOA lllCllWAY-nRlDCES.
53
he stress on
The stresses on all vibration rods must he increased for initial
tension, or the rods must be proportioned by using Table IX. ;
and the stress on each portal strut is to be increased by the
sum of the components of the initial tensions in all the rods
meeting at one of its ends, taken in the direction of its length.
When there is no vertical sway bracing, stiffness is obtained
by the use of knee braces, or brackets {AB, CD, Fig. 2), making
angles of forty-five degrees with the vertical. Let the notation
be as shown in the figure; F being, as before, the release of
weight at /-: P is the sum of the pressures at H and G.
Taking the centre of moments at E gives
b'
Vb = Pd and V =
Again : taking the centre of moments at A gives the value of
the bending-momcnt J/ on the strut at that
point ; thus,
M= V{b -S)- hPd= ^'Ub - 2S).
G k-S--
TV
I-
I
I
I
I
I
—b
Fig.2
•»-.iP
jr««.ip
Let // equal the distance between the cen
tres of gravity of the two channels of which j
the upper lateral strut is comi)osed, then the
bcnding-stress will be
^ M P/
'^--k^.bl^'-^^^'
The intensity of the working bending-stress being six tons,
the number of square inches to be added to the area of each
channel, in order to resist bending, will be
A C Pi ,,
A= -= ,,{b- 2S).
6 1 2b/i ^ '
The stress in AB is found by taking the centre of moments
at G, and making the moment of its stress R equal to the
moment of the horizontal re-action at E ; thus,
and
RS\l\ = \Pd,
^ = -^\h = 0-707 ^. •
54
OA'JJLV.lA'y /A'O.V lHullWAV-BRUhiES.
As before, to make these formulas applicalile to a portal,
make d equal to the length of the batter brace, and P equal to
one-half the sum of the pressures concentrated at all the upper
panel points of the bridge.
To find the effect of the wind on posts and batter braces,
use the formula previously found, substituting in it .S' for /.
Finally, the stress in an end lower lateral strut, at the free
end of the span, may be obtained by the formula
C„ =
2«
•IV
+ /cos 6 + '-^ . w' - \ (^- - vy
where ;/ is the number of panels in the bridge, tc the sum
of the windward and leeward panel wind loads for the lower
system, re-' the same for the upper system, / the initial tension
in the end lower lateral rod, $ the angle between this rod and
the strut, fCthc total weight of the unloaded bridge, and /'the
release of weight at a windward shoe.
Owing to the fact that the joists of the end panel rest on the
masonry, this formula will give a result slightly on the side of
safety.
One or two applications of this formula will convince the
most sceptical, that the general idea that any section is strong
enough for a strut between pedestals is a fallacy. Too great a
reliance has hitherto been placed upon the friction of the shoe,
the released weight there not having been considered ; and the
pressure which comes from the upper panel points seems to
have been neglected.
ORDhXARV IROiX HIGHIVAV-URIDGES.
55
CHAPTER VII.
REMARKS CONCERNING MAIN MEMBERS.
Top chords should nearly always be built of two channels,
will) a plate on top, and latticing or lacing below. It is never
good practice to use a single I-beam for top chord or batter
brace, because of the great variation in stiffness in its two
])rincipal rectangular jilanes and the difficulty in making neat
details for the connections. When the s|)an iDecomcs so short
that it appears to be economical to use such a section, it is short
enough to employ plate girders which are far superior, both as
regartls strength and stiffness, to a bridge with I-beam chords.
The same objection applies to an I-beam post, a favorite
design of inferior bridge companies. If one were to take the
trouble, in passing over a few bridges where they are used, to
cast his eye along the posts, he would generally see that they
are bent to one side or the other, or to both ; the latter being
the case when there are employed what are termed out West
"(}iasticutus rods," or horizontal rods five-eighths or three-
quarters of an inch in diameter, passing from the middle of one
post to the middle of the ne.\t in the same truss. Such rods
are a noticeable feature in arch bridges, a class of structure that
ought to be universally condemned. The principal objections
to these bridges are their lack of rigidity, and their inability to
resist wind pressure, because of the absence of efficient lateral
bracing. But another grave fault is, that, being as a rule built
by companies of the low(}st order, they are weak in section and
detail, and the workmanship is poor. They are, without doubt,
the cheapest kind of iron bridge that can be manufactured :
hence their general adoption throughout the West, where short-
sighted economy in building is the order of the day.
5<5
OKDIA'ARV ll<iK\ IllullU AV-liRlih.F.S.
The I-hcani is mort- (iftcn found in u,ij)er laU'nil struts, wf^oiL'
its use is fjuitc asobjcctioiiahlc, ICvcn if strong enough, whirh
it .sekloni is, il i- by no means tlie hes* section for that place,
owing to the ditVuuUy in connecting to the t i]) cho Wli re
it rests on the cliord plate, and is riveted thereto, the lateral
rods being attached to the chord pins, there is a great leverage
affcrded to the wind stresses to distort tl\e chord ; and, where
connected to the [liii by a jaw, the detail I; as to be either very
clumsy or very weak. Anothei objection to I-beams tor lat( ral
struts is the little room which there is in the flanges lur innuh-
ing rivet holes. Hut the chief one is the small resistance tliat
they oft\ I to the iieiiding effect of the wind pressure when there
is no vertical sway bracing. \Vh..t lias been said of I-beams in
lateral struts can be said with nui.eli more effect concerning
I-beams in i)ort:d braces, for great stiffness and strength are
there necessary in order to carry the wind pressure upon the
upper half of the bridge to the foundations.
The proper function oi an I-beam is to resist deflection in the
plane of its web: ct)nset|uently it should be used as a floor
beam, in which place its depth should seldom be less than ten
inches, never less than nine inches. When one is debating about
using such small floor beams, he should ligure them for a eon-
centratetl wheel load, as well as for a uniformly distributed load.
About the only places where a small I-beam can be legiti-
mately employed are between the i edestals, as a lateral strut
at the fi.xed end of a span, or at the free end if the bridge be
narrow and the span very short, and in vertical sway bracing as
an intermediate strut.
For upper lateral struts, iron gas-pipe was formerly often em-
ployed, and is so yet to a certain extent. Regarded as a section,
nothing could be better fir more economical ; but the connec-
tions made with il are very weak. Then, again, there is the
objection that it is a closed column, and consequently inacces-
sible to painting. Notwithstanding the fact that two of the
leading bridge companies of the I'nited States employ almost
exclusively closed columns, such columns are not. by engineers
in general, conceded to be so good as open ones, which are
always accessible to the paiiU-brush.
Sonic other common forms of upper lateral struts are the fol-
lowing: two tee-irons trussed, the upper restin- on tiie ehorcis
an<l riveted thereto, the low.r ahuttin- a-ainst the same and
att.KiK-d by bent phites ; two Uiannels trussed and attachc'd to
thr .hords m tlie same manner; a eomi)ination of a channel
and a plate, with trussing between ; and two tee-irons laced or
latticed, with a jaw plate at each end wider than their flan-es
screwed up to the chords by nuts on the ends of the chord ptns'
('win- to their lack of both strength and rigidity, all these are
|M.wr contrivances, two channels laced or latticed bcin"- the best
lorm of strut that can be designed for the upper lateral system
As stated in the "General Specifications," in no highway
bridge should the channels in chords, posts, or batter braces be
less than live inches in depth, nor in any other part of the
sti urture less than four inches. One does hear occasionally of
such a thing as a three-inch channel top chord with tuo-inch
I Mils, for a sixty ur seventy foot span. JJut, fortunately for the
public .safety, such structures are few and far between The
author once heard the senior representative of one of the most
llnunsh.ng highway-bridge companies in America contend that
iwo thice-mch channels trussed make a very good centre post
lor short through-spans, -strong enough, because the area
called for by the stress is less than three square inches He
must either have forgotten, or been ignorant of, the f ict that
stillness IS as important a factor in a bridge as simple strength
in reality, strength is dependent upon stiffness; for where
vibrat on can occur, the stresses are increased, not only in the
members where stiffness is wanting, but in adjoining members
of the structure.
Light sections for compression members arc more economical
than heavy ones, and it is generally preferable to use them
nut, It the situation be one where the members will be exposed
to excessive moisture, the webs should be thickened
1 he top plate for chords and batter braces should generallv
I'c from one-quarter to three-eighths of an inch thiJk. Any
thing below the inferior limit would be liable to distortion when
roughly handled, and to ru.st through too readily; and any thino-
above the superior limit would usually be inconsistent with the
best distribution of area in the section.
58
(>A'/>/.v.iA-y /A'o.y ///(/////'./ J -/m'/m;a\v.
It used to 1)0 customary, and tho practice is still followed
to some extent, to make the top plate of varying thickness, or to
vary the number of plates, increasin;,^ from the ends of the truss
to the centre, makini; the ehanncls of the same dimensions
throughout. lUit this method is not advisal)le ; for the proper
plAce for the larger part of the material in a chord like the one
under discussion is in the channels, and not in the plate. Simi-
larly, in any channel, the proper i)lace for the larger part of the
material is in the flanges, and not in the web; the reason being,
in both cases, that the moments of inertia of the section in
respect to vertical and hoiizontal neutral a.xes are increased Iv,
removing a portion of the area away from these a.xes, and the
strength of a strut increases with the moments of inertiii of its
section.
Star iron should never be employed in an iron bridge, and
there is never any necessity for using tee-iron. Two of the
latter sections, latticed by a triple or quadruple intersection ot
thin, narrow bars, are sometimes ado])ted for a portal brace ;
but it is evident how weak such a strut must be, and it is in
the very place where a strong one is most needed.
Four angles with the legs turned in, and set at the corners of
a .square, laced on the four faces thus formed, make an economi-
cal strut, as far as the section is concerned ; but it is probable
that the e.xtra weight of detail and the increased cost of shoii-
work will make it more expensive than another strut of larger
section. Two channels latticed or laced arc the best form of
portal strut. Large, heavy cast-iron [jortals made in one or
two pieces look very well, and might be made strong enough,
but are not so neat and graceful as some other kinds of bracing,
besides adding unnecessary dead load to the structure. Cast-
iron is not to be depended upon, and should not be used in any
part of an iron bridge to resist stress.
Channels in posts usually have their webs parallel to the direc-
tion of the plane of the truss, with their flanges turned outward :
sometimes they are turned inward ; and, where the floor beams
are riveted to the posts, the webs are, or should be, placed at
right angles to the plane of the truss, the flanges turning out-
ward.
0A'/)/.\:tA' y /A'OA' maun '.-/ j ■-uridgi-is.
<;cv
Theoretically it is more economical, as far as the area <.f the
>,eiti()n is concerned, to tuin the flanges in, for the moment
of inertia is greater; but, on the other hand, the diiriculty en-
countered in riveting in a confined space more than equalizes
tile advantage just mentioned.
Another advantage which can be claimed for channels turned
in, \\/.., avoiding cutting them off before reaching the upper
rhord pin, is partially counterbalanced by the increased size of
pill, due to the larger leverage thus given to the stresses in the
diagonals. Notwithstanding the difficulty in riveting, it is often
hiuiid necessary, in swing bridges, to turn in the flanges of the
post channels in order to form a good connection with the chan-
iiel bottom chords : otherwise, the channels of the bottom chords
may be turned in, and the post channels be allowed to bestride
tlicm.
The objection to cutting away the flanges of channels at the
feet of posts has been shown by some experiments made by
the Chicago and Alton Railroad Company, as given in a paper
i\a(l before the Western Society of luigiiieers by Air. \\. J.
Ward, who shows that this cutting-away reduces the strength
of the strut about ten per cent.
Main diagonals, as will be demonstrated in Chapter X., should
have the proi)()rlion of width to depth of about one to four;
and the chord bars, the proportion of from one to four to one
to seven, according to the number of them in the panel.
It is preferable, for ajipearances, to make the counters of
square or round instead of flat bars, because of the unsightly
change that there would be in the diameter of the flat bars at
the upset ends. It is immaterial, except for the effect upon the
pins, whether the hip verticals be flat, scpiare, or round ; but
the preference is usually given to square iron.
I5uilt floor beams in ordinary bridges should be formed of
solid plates and angles, and not made trussed ; because, even if
the latter method permit of a saving of material, it is more
conducive to vibration. Where the panels are long and the
roadway is very wide, it would be permissible to use trussed
!)L'ams, provided that they be made \ery rigid in their details,
and not too slight in their .sections.
i;; !
CO
C'A'/V
.y.i/n' iNox ]iic,iiw.\y-Bi^ii)C,Es.
CHAPTER VIII.
rUOrORTIONING OF MAIN MKMBKRS OK TRUSSES. LATERAI
SYSTEMS, AND SWAY ISKACIXo.
HwixG found all the stresses in the main members of the
truss and in those of the lateral systems and sway bracmg, and
havino- written them alon-side the respective members m the
dia-n-mns, the next step is to calculate the sections requn-cd.
The dia-rams for the lateral systems and sway bracmg may be
rouohly\u-awn in pencil ; for they need not be preserved, as the
size's of the members are to be written on the truss dia-ram.
For the tension members of the trusses, the sections required
can be found by dividing the stresses on the diagram by the
proper intensities of working-stress, as given on p. 12; remem-
bering- that the intensities for main diagonals are to be inter-
polated. When f.u.ncl. the reciuired areas for the sections
should be written on the diagram, after the stresses, preuxing
them with the letters S. R. (section required), as shown on
riue V Then, by using Carnegie's " Pocket-Companu)..
pp. 94-105, or some eciuivalent tables, ^an be found the sizes
necessary to give at hast the section required, taking care that
the sections be in good proi«)rtion.
The stresses in the counters are to be increased for initial
.crsion by the amounts given on p. 10; or, what is the same
tliin.^ the size required can be found from Table IX. by look-
ing- '";iown the column headed " Working-Stress = 4 tons per
.c,uaie inch," if the bridge belong to Class A, or down the one
headed " Working-Stress = 5 tons per square inch, if it belon.i;
to Class W or Class C", until a stress is reached which is ec|ual
to or greater than one-half or the whole of the .stress on the
diuo-ram, according to whctlier doul)le or single counters
:)C
Oh'D/.y.iRv /A'o.y }ii<.;iiivAY-nRii)(.]Es.
6 1
ES, LATER A I
cniplincd ; tlicn, by following;- the horizonla! line which con-
tains tliis stress, cither to right or left, will be found the ^ize
of the counters or counter required.
As previously mentioned, the sections required for, and the
sizes of, the hip verticals, can be found without calculation from
OIK- of Tallies VI., VII., or VHI. Should the joists and floor-
ing,' be of oak instead of pine, the section required for, and the
<ize of, hi]) verticals, can still be found from the table by sup-
posing an increase of one foot in the panel length.
The sizes of the lateral and vibration rods can be found from
Table IX. by looking in the column headed "Working-Stress
= 7-5 toii^ P^'f square inch," in the same manner as e.xplainetl
for counters. If the panel length correspond with the one given
in Table IV., or if it do not differ greatly therefrom, there need
be no calculations made for stresses in the lateral .systems and
sway bracing ; for the dimensions of all the struts and rods for
these .systems are given in Table XXV. In that table the
(iimcnsions in the column marked " Pan. i " arc the sections
rcsi)ectively of the upper portal struts, the portal vibration rods
df any), the lower portal struts (if any), and the end lower lat-
eral rods. Those in the other columns are the sections
resiK'ctively of the upper lateral struts, the upper lateral rods,
the post vibration rods (if any), the intermediate struts (if anv),
and the lower lateral rods. The portal struts are thus assumed
to belong to the first panel ; the first upper lateral strut, with
its sway bracing, to the second panel, etc. ; so that, when the
bridge has an odd number of ijanels, there is no lateral strut
or vertical sway l)racing given for the middle panel. The fort\-
toot, fifty-foot, and si.\ty-foot span.^, being pony trusses, have
only lower lateral rods. Sloans above one hundred and fift)'
feet in length have \ertical sway bracing.
If the counter stresses be large, it is preferable to use double
counters : sometimes both single and double counters are cm-
plt.yed in the same truss. Where there is an odd number of
]xuiels, the centre tliagonals should be made double and adju.sta-
hle. The number of main diagonals per panel is generally two ;
init, if the sections become so great as to necessitate excessively
large chord pins, it is better to employ f.iur ; placing two inside,
02
OKD/X.UiV INOX HIGHWAY-BRIDGES.
and two outside, of the top chord and posts. The widths of the
main diagonals should, for the sake of appearance, increase
from the centre of the bridge to the ends. For the same rea-
son, it is well to have all the chord bars of the same, or nearly
the same, depth ; the correct area of section being obtained for
each panel by varying the thickness and the number per panel.
In large bridges it is permissible to reduce the depth of the
choid bars towards the ends of the span in order to economize
on the pins. It is also permissible, when there are several
chord bars in the same panel, to employ depths varying by a
quarter of an inch, provided that the bars of smaller depth be
placed on the inside.
As stated in the " General Specifications," where chord bars
are trussed to resist the buckling effect of the wind pressure,
the intensities of working-stress for the trussed bars on the net
section should be reduced to four tons for bridges of Class A,
and to five tons for those of Classes B and C.
"Chord packing" is a term applied to the arrangement of the
chord bars, diagonals, posts, and beam hangers upon the bottom
chord pins. It is a matter of great importance, but is very
often neglected. The three princijial considerations to be kept
in mind while arranging the packing are, that the bending-
moments on the pins are to be made as small as possible, that
the packing is to be made as close as circums;ances will permit,
and that there be sufficient clearance to avoid all chance of
finding the space between the post channels too narrow when
the bridge is being erected.
The width of the packing is dependent, not only upon the
number and thickness of the bars, but also upon the width of
the top chord plate. The latter is often, in its turn, dependent
u]X)n the chord packing.
Th<' usual arrangement is to pack the main diagonals, coun-
ters, and beam hangers inside of the posts, and the chord bars
outside ; bringing the latter, however, within the batter braces
at the shoes, unless the end panel contain four bars per truss,
when two should go outside, and two inside. It is not abso-
lutely necessary that the chord bars \m\\ in the exact line of
the trusses ; an inch or two of deflection in twenty feet being
ORDINARY IROX lilGHW AY-BRIDGES.
0?>
scarcely noticeable, and making no appreciable difference in the
length of the bar : nevertheless, it is better to make the bars as
nearly as possible parallel to the planes of the trusses. The
main diagonals should be placed next to the post, then the
beam hangers, and inside of all, the counters with a filler
iK'tvveen them long enough to permit of the screwing-up of the
turn buckles, or sleeve nuts.
The arrangement of the chord bars will be treated in Chan-
ter X. ^ *
The sections of the top chords and batter braces are to con-
sist of two channels, with a plate on top, and latticing or lacing
below. The same depth of channel, and the same width and
thickness of plate, are to be employed from one end of the chord
t.) the other; the difference in area being obtained by thicken-
in- the webs of the channels. On this account, there is often
an excess of section in the end panels of the top chord, and, in
long bridges, even in the next panels.
It is customary and better, but not necessary, to make the
depth of the channels in the batter braces the same as that of
the channels in the chord. Tlie top plate for the batter brace
should be of the same size as that for the chord.
The width of the toji plate is dependent upon the depth of
the channels ; as the transverse distance between the centre lines
of the rivets which attach the channels to the plate should be
never less, and not (unless there be good reason) much greater,
than the depth of the channels. The least dimensions for such
|)lates for different channels are given on p. 15, The chord
channels are sometimes spread apart in pony trusses, so as
to mcrease the lateral stiffness; and in any bridge it may be
necessary to spread them a little to admit of a certain manner
of packing below : but, the more narrow the chord plate, the
more economy of material will there usually be.
To proportion the top cliord or batter brace for a given stress,
.issume the deplh of the channels, and divide the length of the'
piiiel or batter brace by it, both dimensions being expressed in
the same unit. Referring to Table X. or XI., according to the
class of bridge to be designed, look down the column marked
"Kutioof L to A" until the ratio ju.st found is reached: the
64
ONJ)L\AKy JA'iKV J/lu/IUW ) -/.'A7/n;/'-.V,
n
umber to the ri<rht, in the first of the three columns, is the
s are
intensity of working-stress to be used. The three column
for the three cases, — both ends fixed, one end fixed and one
end hinged, and both ends hinged, marked LiE, L^iO, and (••
respectively. The tables were calculated by the formula of
C. Shaler Smith, CM. ; to whom the author is indebted for
its use, and for other valuable information in connection with
bridge work. Then, to find the area of the top chord or batter
brace, divide the stress given on the diagram by the intensity
of working-stress taken from the table ; from the quotient
subtract the area of the top plate, and divide the remainder
by two : the final quotient will be the area of each channel.
This calculation should be made with both the stress in the
panel nearest the middle of the span and that in the end
one, or, in long spans, that in the one next to the end. If,
then, with the depth of channel assumed, it be found that
there is, in the taljle of channel sections employed, a light
channel that will not be much too heavy for the end. and a
table for the middle of the chord, all right :
ther trial must be made, with a channel of a dif-
leavier one sui
if not.
ano
fcrent depth. The greater the depth of channel, the less
the ratio of length of strut to diameter, and consequently
the greater the intensity
sectional area required : :
)f workinu-stress, and th(
less
generally speakin;
use the lightest and deepest channel;-: possible,
saving in section be small, when it will be
the
it is well to
unless the
more econonucal
for other reasons, to use the next smaller depth. These rea-
sons will be given in Chapter XV. The dimensions of the
channels
an
d pi
ate should be written on the cHagram of
stresses as shown on Plate V.
The sizes of the post channels are to be found in a similar
manner to the one just described, with these two exceptions, —
that the column for two hinged ends i to he used, and that
there is no plate. .Some engineers prefer fixing the uj)])er ends
of the i)osts bv attaching them, through the medium of pkites.
to the chord, thus saving a little in the section ; but, as will be
seen farther on, there is no true economy in so doing.
In high double-intersection bridges, where the diagonals are
OKD/A.INV /A'OX IIIC.n\VAV-I^R,nGKS. 65.
halved and connected by pins passin-^ through the middle of-
he post channels, as shown in Fi.-. ,5. Plato [I., the post may
be proportioned for half-length witl, both ends hinged; but in
this case the counters must extend to the ends of the span
although there be no stress in some of them, for the purpose of
preventing the posts from moving laterally at the middle "
The upper lateral struts and portal struts are to be propor-
t.oned by using Table XI. for both ends fixed, and adiing, f
necessary, to the section thus found, enough area to resist the
bending as determined in Chapter VI
The ultimate strength of the intermediate struts, which are
Ibcams can generally be found from experiments made by the
manuaicturers ; a factor of safety of four being sufficient In
default of such experiments, the approximate workino-.stresses
^:^^^^^^^ foi-Lbeams used as pillars may be ta^:; f::m
iablc XL., which has been compiled from an old edition of
Carnegie s "Pocket-Companion." When the I-beam .strut
suppo,sed o bend ,n a vertical plane, its length should be taken
c<,u to the istance between the points of attachment of th
-a ets but when ,t ,s assumed to bend in a horizontal plane,
.ts cngth mu.st be taken equal to the distance between opposite
posts of the trusses. i^pposut
J^rackets should extend inward and downward, from about
l<n,r feet m narro^v bridge s, to about six feet in wid; ones it
s|.,ybrac,ng given in labie XXV was proportioned for brack-
a of hese dimension,s. Brackets beneath intermediate struts
n^onb^rvetostiH^^^
Ti- intermediate lou. r lateral struts being of wood, it will
n.H be necessary to calculate their section.s, which p actical
;;;;-c..uo.
' SI, t of two channels laced or latticed, and ■ ttached to the
'"' ;'7' P.ns by J,,.. The si.e for the channels is to e
- lut utl.er end is really fixed or hinged, but I^cause the
■^tungth of a strut .0 attached is intermediate between that of
66
ORl)/XARy JA'-'-y JiIOJIUA)-!lJ</D'^ES.
one witii fixed ends and that of one with hinged ends. It is
not positively necessary to use a lateral strut at the fixed end
of a span ; but it is much better to do so, especially in long
spans, not only to distribute the horizontal re-actions, but also
to keep the chords in line, for there is necessarily a little play
in the anchor bolt holes.
It is not unusual to make the struts between pedestals of the
same dimensions at l)oth ends of the span, although the one at
the fixed end need not be so strong as the one at the free end.
Appendix I., the substance of which appeared as an editorial
in the " American Engineer" of July 20, 1883, shows the neces-
sity for stiffening, at least the end panels of many bottom
chords. This can be accomplished in several ways; one by
inserting a strut between the inner chord bars ; another by
using channel bars, laced or latticed, instead of eye bars, in
which case the net section of the zvcbs alone should be relied
on to resist tension ; and another by trussing the inner chord
bars. The second of these methods is the most satisfactory,
but at the same time the most expensive. When stiffening
the end panel, it is well, though not perhaps essential, to
stiffen also the second panel, where the stress is the same as
in the one at the end. Such a practice is certainly conducive
to the prevention of vibration of light bridges under rapidly
moving loads.
Hip'^vcrticals in three or four panel pony trusses are to be
made to resist the compression which might be produced m
them by rA-er-screwing the turn buckles of the counters. The
section to be employed is cither that of two channels laced or
latticed, or two flat bars trussed : in the latter case, as iire-
viously stated in the "General Specifications," the intensities
of working tensile stress on the net section are to be three tons
for bridges of Class A, and four tons for bridges of Classes 15
and C. If two channels be used, the net area of the webs alone
is to be relied on to resist tension.
ORDINARY IRON UHJUlVAY-BRIDuES.
6;
CHAPTER IX.
PROPORTIONING OF FLOOR SYSTEM.
The wooden portions of the floor system are the joists, floor-
ing, hand railing, hub planks, and guard rails, or felly planks.
Of these, only the joists require calculation for strength Pine
flooring is generally three inches thick, and oak flooring two
and a half inches. The hand railing, when of wood, should
consist of 4" X 6" X 4' posts, not more than ten feet apart
2" X 6" rails, and 2" X 12" hub plank, all of pine, and built as
shown m Plate II., Fig. 13, and as specified on p. 23.
The guard rails should be of 6" X 6" pine, connected as speci-
fied in the same place.
To proportion the joists, first assume their number per panel
and their dimensions, in order to determine the total weio-ht of
lumber per panel ; to this add the total maximum panc5 live
load, or the product of the panel length by the clear roadway
by the live load per square foot, given on p. 5, the sum being
expres.sed in tons; then, referring to Table XIII. or Table
XIV., find, with the given panel length and the assumed depth
ol joists, the safe load for a joist one inch wide, and dh-ide this
number into the total load just found : the quotient will be the
total width of joists per panel, when laid side by side. Divide
this total width by the assumed width of one joist : the quotient
\vill be the number of joists per panel. If it agree approxi-
mately with the number assumed, and if the distance between
centres of joists, when in place, will be between eighteen and
tucnty-four inches, all right ; if not, another trial must be mr.de,
with a different depth of joist, and a new assumed panel wei-^ht
;'l lumlKM-. It may be well, in any case, to try two depths" of
joists, m order to see which is the more economical. The
68
oj^n/.y.iKV fKOx inc.invAv-nRinr.Es.
minimum size of pine joists slioulil be 3" X 10": the maximum
size tliat it is advisable to figure on is 4" X 14". because deeper
joists cannot always be readily purchased. It is to be remem-
bered that pine lumber can be found in the market in only
certain sizes, usually even inches in depth, and ahvays even feet
in len-th ; i.e., timbers 3" X 8", 3" X 10", or 3" X 12" are readily
procured, while timbers 3" X 9" ^"- 3" X n" are not; also, if
one require joists eiKhteen feet six inches long, it will be neces-
sary for him to buy lengths of twenty feet, and cut off a foot
and a half. Timbers over eighteen feet in length cost more
per thousand than those of that and shorter lengths.
Tables XV., XVI., XVII., and XVIII. give not only the sizes
of joists, and number per panel, but also the total number of
feet, board measure, of pine and oak per panel, including, when-
ever there is any, waste material.
The total load for a floor beam consists of the live load, the
weight of lumber which it supports, and the weight of the beam
itsctf. The latter must of course be assumed : this can always
be done with sufficient exactness to determine the floor-beam
load. The latter is assumed to be uniformly distributed be-
tween centres of bearings.
In calculating the dimensions of a floor beam to sustain a
given load, the section of the web is to be assumed ; and the
beam is to be proportioned accortling to the formula given on
p. 19, and to the principles there enunciated. It may be neces-
sary to make two or three designs, in order to determine the
most economic depth ; but it will be often found that a variation
of several inches in the depth will not affect the weight per
foot.
The lower lateral strut, which is to be well bolted to the floor
beam, will add consi.lerably to the strength and stiffness of the
latter. The joists .should be dapped on to the strut at then-
bearings, so as to offer a resistance to the lateral deflection of
both strut and beam.
The lower flange plate, if there be one, need not extend over
more than the middle half of the length of the beam. The
rivets attaching the plate to the lower flange angles should be
staggered, and .should be spaced ah«»«!t four inches apart ; ami
(>h'/)/X.l/n- /A'OX niGIIU-AY-liRii)GES.
69
the areas lost from the plate and angles by these rivet holes
should be deducted when figuring the net section.
In heavy beams, several plates arc often used to vary the
section gradually from the centre of the beam to the ends ; but
if one share Weyrauch's views upon rivet stresses, as expressed
in his "Structures of Iron and Steel," he will avoid any such
practice.
Many bridge companies reduce the depth of built beams at
the ends, in order to save a little weight of iron. This method
may be advantageous to the company which pays for finished
britlges by the pound ; but it is seldom so to the manufacturer,
for the triangular pieces cut from the web are often wasted : be-
sides, the e.xtru work in cutting the web, bending the angles, and
making square rests for the beam-hanger nuts on the inclined
flanges, more than counterbalances any saving of material.
For a bridge with sidewalks, reducing the depth of the floor
beams at the ends adds to the appearance of the structure, and
need not interfere with the bearing of the hanger nuts.
Tables XIX., XX., and XXI. give the sizes of floor beams
for all cases ordinarily met with.
To illustrate the method of proportioning an ordinary floor
beam, let us take the case of a beam for a twenty-foot panel,
fourteen feet clear roadway, and fifteen feet between centres of
trusses, the bridge belonging to Class A.
The live load on the beam will be
14 X 20 X i§^^ = 14 tons.
The weight of , he lumber, from Table XV., is
2085 X 2.5
2000
= 2.606 tons.
Let us assume the weight per foot of the beam to be fifty-five
pounds, the total weight of same will then be
2000
= 0.44 ton.
The total load on the beam is, therefore,
14.000 + -.606 + 0.440 = I 7.046 tons.
■JO
O/WIXA/^ V /A'OX II H IIIW.W --nRllh .KS.
The most economic depth for the beam can be found by trial, or
by consulting Table XIX., which gives J" X 27" for the section
of the web. ■ 1 u
Let us assume these dimensions, and take the eflcctive deith
D equal to 26"; then substituting in the formula given on p. ig,
omitting A\ and remembering that 7' = 4 tons for bridges of
this class, gives
the half of which is 1.28 d", corresponding to a wei-ht per foot
of 4.27 pounds, because a bar of wrought-iron one inch square
and three feet long weighs just ten pounds. Referring to Car-
negie's " Pocket-Companion," p. 68, we find that a 2.^' X 3" 44*
angle will be required. Let us see if a 2"X3" 5* '-mj^'*-^ ^^;'ll
dol^or the bottom flange. Assuming that the rivets are |",
and the holes \};\ in diameter, the area lost by a rivet hole will
be 2 X *■'-" X 11" = 0.430", which, added to 2.56, gives 2.99 c",
corresponding' to two angles, each weighing five pounds per
foot The assumed angles will therefore be exactly what are
required. For stiffeners, let us use 2"X2" 3-1* -ingl^'S- I'our
of them at each end of the beam will be needed to take up the
compression produced by the stress in the beam hangers, leaving
a space between the inner angles equal to about fourteen feet.
The ratio of thickness of web 10 depth of same is -^^^ — \q^
Referring to p. 19, we find, by interpolating, that the distance
between "stiffeners should be 1.65 times the depth, or about
44.1". The number of spaces between stiffeners in the four-
teen feet will be -^^^i^ = 4, requiring six stiffeners, three on
each side of the web. The filling plates will have to be
_5_" X 2" X 22.1".
^^The method' of finding the number and distribution of the
rivets in the flanges will be treated in Chapter XIII.: for
the present, it will be sufiiciently accurate to assume that the
average spacing is two inches and a half.
tVv7V.\./A'J- JA\).\ ///(/// If. I i-ZlAV/JuJ'S.
71
uctivc ck'i th
ven on p. 19,
r bridges of
icrs, three on
1 have to he
Wo arc now ready to pass to the hill of iron for the hcani,
the list of details for which is ^iveii on p. 30.
nil. I, or ii<()\.«
Wcl)
I
i"
27"
16'
3O0#
r|)per flan • . .
2
2i"X3"
4.4#L
16'
141 "
Lower Han^c . . .
2
2"X3"
S*L
16'
iro"
Still' ning angles. .
14
2"X2"
3.i*L
26i"
f/. "
Filling plates . . .
' 1
6 "
ID
2"
22i"
5S-'
Rivet heads . . .
220
pairs
(h)
o.i6#
35"
Tofal weight of beam .
847*
Dividin-,- 847 by 16 gives 53 pounds as the weight per foot of
the tlixir beam.
Referring to Table XIX.. wc find that the beam there given
agrees with the one just designed in e\ery respect, except that
the weight is a pound and a half per foot greater. This is
owing to the fact that the weights in the tables of floor beams
were made large enough lo cover a slight variat
ion in the
d
esignnig.
There is no need for proportioning rolled beams, be
cause m
Carnegie's " I'ocket-Companion," pp. 33-44, are given the work-
ms.
I'll
,^-loads for all the I
)eams rolled at the Union Iron Mills.
ese loads are directly applicable to bridges of Classes B and
multiply the calculated load upon
C. For bridges of Class A,
the required beam by six (6), and divide by five (5), the
n searcl
in the "Companion " for a beam to sustain th
e resulting lf)ad.
Plate girders for short spans are to l)e designed according to
exactly the same principles as those laid down for the designing
of floor beams. The details, t
there should be two inclined stiff
00,
the beam, one on each side of the web, their low
over the edge of the bed plate nearest to the centre of th
are the same, except that
ening angles at each end of
er ends resting
e s
IS shown 111
ate
pan,
Th
17-
e distance apart of plate girders should not exceed four-
* Tlie metliod for preparing this table K explaineil in Chapter XIV.
Xf'^
..^. ^
n-.
^.J^ ^
IMAGE EVALUATION
TEST TARGET (MT-3)
1.0 Hfi
I.I
1.25
2.8
1^
•is loK
UUI-
|||| 2.?
1.8
1.4 ill 1.6
p%
(?
.%
7i
7:
/^
Photographic
Sciences
Corporation
23 WEST MAIN STREET
WEBSTER, N.Y, 14580
(716) 872-4503
IN-
ORDINARY IRON II IG I nv AY-BRIDGES.
liiii
teen (14) feet, on account of the difificulty in obtaining joists
lar<;c enough to support the concentrated wagon-loads.
Trussed beams are sometimes made with one trussing-post,
and sometimes with two. To determine the relative length of
the part between the posts in the latter case, —
Let
/j = length of an end division,
/j = length of the central division,
and
/= 2 /j-f- A = length of beam between centres of supports.
The whole beam is now divided into three beams, two of which
may be considered fixed at one end, and supported at the other,
and the third fixed at both ends. If the moments of the loads
do not balance each other over the posts, the rigidity of the
connection there may be considered sufficient to insure fixed-
ness.
The greatest moment for a beam fixed at one end, supported
at the other, and subjected to a uniform load of w tons per
lineal foot, is
\T.i'l{' at the fixed end.
The greatest moment for a beam fixed at both ends is
■^u>l.£ at either end.
Remembering the assumption of the fixedness of the beam over
the posts, it is evident, that, in order to make the moments
over these points a minimum, the two values found should be
made equal to each other, so that
or
and
Again :
therefore
and
11 _ 3/2
2 — '2 1 '
/, = 1.224/j.
/= 2/, -f A= 3.224/1:
/, = 0.31/,
= /(l - 2 X 0.31) =0.38/,
ussing-post,
ORDINARY IRON HIGHWAY-BRIDGES. 73
,)r the length of the central portion should be about four-tenths
of that of the beam between .suj)porls.
To proportion the upper flange of a trussed beam having two
trussing-posts, such as shown in Plate II., Fig. 16, —
Let
d = depth of beam proper,
D - depth between centre line of beam proper and centre line of
bottom cnord of trussing,
7i< = uniform load per foot on beam,
/■= },7c{/^ + I,) = load concentrated over one post,
and let
/, /i, and 4 have the same values as before.
The area of the compression flange of the beam necessary to
resist bendmg only is given by the formula
where C is the intensity of working-stress upon the flange to
be taken from the "General Specifications," p. 13, and A' is
the area of the web.
The stress in either chord of the truss is
D'
Let /f equal the area of one flange of the beam, supposing
that the loads P were really concentrated over the posts, instead
of bemg distributed, then
and
A' + 2^" = area of ideal beam,
C\A'+2A") = F=^^^;
D
where C is the intensity of working resistance to compression.
* For proof of tins formul.-,, see .Apper.dix U, which gives the demonstration fo
r a similar
ili
}i\
\f
74
OKDIN/IRV IRON HIGHWAY-BRIDGES.
It should be about three (3) tons for bridges of Class A, and
four (4) tons for those of Classes B and C. The total area of
the lower flange of the beam should therefore be
If the beam be a rolled one, as it nearly always is, there is no
need of figuring upon the size of the upper flange ; while, if it
were a built beam, it might be as well, for practical reasons, to
make the flanges of the same size, although theoretically a
slight reduction in the area of the upper one would be per-
missible.
For a beam with a single trussing post, the bending-moment
over the post is
and the area of flange necessary to resist bending is, as before.
A =
_ lii/i^
St/C
1//'
P, in this case, is equal to zc/^ ; making the re-action at each end
of the beam, under the supposition of concentrated loading,
The direct compression on the upper chord of the trussed beam
is, therefore,
r-^^=C'{A'+2A"):
and the total area of the flange is
^'L,c"fl + ,c,o-K.
'lii
OIWINARY IIWNHIGHWA Y-B RIDGES.
75
ing-moment
russed beam
The author does not claim that these formulas are exact ; but
practically they will prove to be a great deal more useful than
others theoretically more correct, but also much more complex.
At the end of Chapter XIII., there is given a complete design
for a trussed floor beam with two posts. The reason why it is
not inserted here i.s, that it is necessary to understand the
contents of Chapters X.-XIII. inclusive, in order to properly
proportion the details.
The weight supported by the four hangers that usually sus
tain a beam is that of a panel live load upon both trusses, that
of the lumber in one panel, and that of the beam itself. The
total load divided by eight times the intensity of working-stress
will give the area of the section of a hanger.
Square sections lie more closely to the pins than round ones,
and take up less room in the packing ; but they must always be
upset, which, in short hangers, makes them more expensive than
round ones.
Single beam hangers are allowable in skew bridges, where,
indeed, their use is often unavoidable, or in narrow bridges
with short panels, where there is not much weight to be sup-
ported.
Tables XXII., XXIII., and XXIV. give the sizes of beam
hangers for nearly all bridges without sidewalks.
The most simple manner of finding the size of single beam
hangers for any roadway and panel length is to look in'the table
of hip verticals of the same class for the section required, and
multiply it by one-half of the ratio of working-stresses for hip
verticals and beam hangers: the result will be the area in
square inches of the section of the hanger.
If the floor and joists be of oak, the tables of floor beams and
beam hangers can still be employed by supposing an increase
of one foot in the panel length.
!: f
76
0/WIA'ARV IROiV HIGHWAY-r>Rllh.l-:s.
CHAPTER X.
THEORY OF PIN PROPORTIONING.
if 8
The subject of "bridge pins" is one deserving of more con-
sideration than has been accorded it by engineers, and authors
of technical works. Until 1873, when Mr. Charles Bender, C.E.,
presented his paper on " Proportions of Pins used in Bridges " to
the Amei'ican Society of Civil luigineers, very little was known
concerning it ; the usual custom among engineers when propor-
tioning pins having been to allow one square inch of pin area
for every eight or ten thousand pounds of shear in the section
most subject to shearing-stress. As ]\Ir. Bender states gener-
ally, and as will be shown farther on to be true for iron bridges,
it is not the shear, but the bending-moment, which causes the
greatest tendency to rupture ; so that in any iron structure it
will be sufficient, in finding the sizes of pins, to calculate the
greatest moment induced in them by the various members
coupled thereon, and to proportion accordingly, due regard
being paid to the stresses in the eye-bar heads. Before making
any investigations, it will be well to review and summarize the
most important results of the investigations of others in this
subject.
The principal conclusions arrived at by Mr. Bender are, that,
for a well-fitting pin of large diameter, a pressure on the bearing-
surface of six tons per square inch is not too large ; that for
simplicity it is well to assume that this pressure is uniformly
distributed over the diameter of the pin ; that wrought-iron,
after millions of impacts, may break on the side where the
stress is tensile, but never on the side where it is compressive,
the ultimate resistance to crushing being about thirty tons per
square inch ; that the shearing-stress at the centre of a pin is
ORD/X.i/n- //WX IIICllWA y-URIDCES.
/ /
one and thrcc-cij^hths times the average shear on the whole
section ; that in iron and steel the ratio between the greatest
allowable tensile and the -reatest allowable shearing-stresses
should be as 5 to 4, which would make the uniformly dfstributed
shear 2.91 tons per square inch, to correspond with a tensile
stress of 5 tons per square inch ; and that, owing to various con-
siderations, iron in ]Mns may be strained much more than similar
iron in tension members.
Mr. K Baker, C.K., in " Beams, Columns, and Arches," treats
of pins merely incidentally. He finds, that, for iron in solid
circular beams, the average value of <^ is 11/ where / is the
ultimate resistance per square inch to rupture by tension, and
c/. the difference between the apparent ultimate resistance per
square inch to rupture by bending and /, according to the equa-
tion /''=/+ qi, /'"being the apparent ultimate resistance per
.square inch of the extreme fibre which first gives way ; and,
that for steel, the value of <^ varies between 1.7/ and 1.9/
Professor Burr devotes five pages of his work on " Stresses in
]5ri(lge and Roof Trusses " to the subject of pins, and illustrates
the particular case of a suspension-bridge cable pin, and a gen-
cral case for ordinary truss-bridge pins.
Professor Du Bois, in "Strains in Framed Structures," also
gives a mathematical discussion of how to find the maximum
bcndingmoment.
Table XII. gives the working bending-moments on all the
non and steel pins, and the working-shear on all the steel pins,
which will ever be required for highway-bridges. Having cal-
culated the bending-moment, the requisite diameter for the pin
can he found by looking down the column for the class of bridge
considered, until a bending-moment at least equal to the one
found is reached. The diameter will be found at either end of
the horizontal row thus located. The use of the columns for
shear will be made apparent presently.
The upper and lower horizontal lines in the tables of bearino-s
(lables XXVT. and XXVII.) give the diameters of the pins;
the extreme vertical lines, the necessarv widths of bearing-sur-
tacT at each end of the pins, including both channel and re-
t'lilorcing plates ; and the other vertical lines, the permissible
11'^
78
ORDINARY IRON IIIGHVVAY-BRIDGES.
pressure, on the bearings. The method of using these tables is
the following. The pressure .vhich the pin is to carry is to be
taken from the diagram of stresses. A trial diameter is then
assumed. The vertical column in either Table XXVI. or Table
XXVn., headed by this diameter, is to be followed down, until
a number nearest the pressure to be carried is found. At either
end of the horizontal row thus located will be found the proper
width of bearing. Knowing the width of bearing, diameter and
pressure, the moment to which the pin is subjected may be at
once calculated. Turn, then, to Table XII , and see if this
moment agree with the working-moment corresponding to the
trial diameter. If it does, all right : if not, another trial is to be
made, with a new assumed diameter. After a little experience,
the first trial will be sufficient. A consideration of other de-
tails, such as widths and depths of eye bars, etc., will frequently
aid very much in these trials.
To find the least value of the ratio of the diameter of pin to
depth of eye bar in an 'ron bridge, by considering the tension
in the bar, and the pressure between the pin and bar, —
Let
w — width of bar,
fl'j = depth of bar,
d — diameter of pin,
C = intensity of working compressive stress,
T = intensity of working tensile stress ;
then
and
wd^T = tension in bar,
wdC = compression on pin and eye.
These, of course, are equal ; and, as C = 6tons when T:
tons, there results the equation,
d=y, = 0.833//,,
.1!
i 3!
which shows that the diameter of the pin should never be less
than eighty-three per cent of the depth of the bar. It is possi-
ble, though, that good iron of twenty-five tons tensile strength
will resist more than thirty tons per square inch in comprcs-
ORDINARY IRON HIGmVAY-liRlDGES.
79
sion : consequently d may be taken at o.M^ as a matter of con-
venience.
To find the proportion between width and depth of bars for
the smallest allowable pin in an iron bridge, —
Let the notation be as before, and first let us suppose that
there be but one pair of bars acting at each end of the pin, and
that the total tension be a fixed quantity. The stress in one bar
is iiY/,7', and its moment is wV,7: This must be equal to the
resisting-moment of the pin, which is given by the well-known
equation
d
Here R — \T, / = \-,:r\ and D = r = -, substituting which
gives
Equating the two values of the moments gives
w'd,T = -^nrd\
or
64 d.
Now, to make the diameter of the pin as small as possible,
the moment of the stress must be made as small as possi-
ble ; and, as the stress is constant, the lever-arm w must be
made as small as possible. But the product of rv and d^ is a
constant : so when zv is smallest, d^ must be greatest. But the
greatest value of d^ is {d ; substituting which gives
2 3"'
64
and
64 125
«'i' = o.754«',«,
or about one-fourth of the depth of the bars.
If there be two pairs of similar bars acting at each end of the
pin, instead of one pair, the equation of moments will be
2W%T = -^\nTd»,
8o
o/c/)/.v.i/n- /A'o.v nir.iiwA Y-HRiihiEs.
or
w =
As before, to make d a minimum, re must be made a minimum,
or ,/, a maximum : therefore d = \il^, which, substituted, gives
7t' = 0.194^/p
or about one-fifth of the depth of the l)ars.
For three pairs of simihir bars at each end of the pin, the
equation of moments will be
substituting in which \d^ for r/ gives
7.' = o.i5(y„
or about one-sixth of the depth of the bars.
Finally, if there be four pairs of similar bars at each end of
the pin, the equation of moments will be
which gives
6,w"d^T = i\TTd\
a' = o.i37./i,
or about one-seventh of the depth of the bars.
To find the greatest working shearing-stress (supposed to be
uniformly distributed) in terms of the working resistance to
tension, —
Let 5 = actual varying resistance to shearing, considered
uniforml}' distributed. The greatest value of .V will correspond
to a value of w equal to 0.274^/,; for suppose the moment to
remain at its maximum value, and the dimensions of the bar
to vary (consequently the stress therein also), the tension in
the bar will be greatest for the value of ti' corresponding with
the greatest value of d^ : therefore the shear will also be great-
est for that value.
Equating the tension to the shear gives
: i!
^ minimum,
ach end of
Substituting yiov ,/,, and o.274^«,/) for w, gives
81
and
0-274 (5'/) ^7' =
^^= 0545 7',-
l"l" 'f=S tons, .S"='>7->i; folic IJ,.f ^u
V.I..0 for .V is, acconli,,':, .;.,,'" ';:;r'"L^""™'"'=
;'-• ■' -.V":;; i-" ^e p™,,..,, „,..,„;„;,?,:';, . ,hi:;":;:i
l""li".^'. .t w,ll 1,0 str„„K o,„„,g|, ,„ resist shear ami n" f^
■I-. I"f...c .1.0 pin co.„„ shear, it >v.„„„ eiU.er brei^^ bl b '
11.^ "r en,sh„,K, "r the eye of the Ixir w.nil.l „ivc wiv A si, ^M
.,u-es.,,ation f„r steel bridges, where 7' = i 3/ , „, C- 'r
.....I A' (.he intensity „f working bentii„,.s,re;, = S^T, e,'
./=o.S7]4,/„ t,. = o.i.s,f;,/ and .V-soj- tn,,s 1 ^ .
"'">■ "' »-^'^'n„,s.ress'w„en tb-.^ntstr^.e: ^ ,:';,?'
l.-lin«-hn,it, and the ratio ;; for ,ha, e„„,h,i„n of stress is a.
..s i.uninunn, an<l eonsetpiently the area of the bar, the tension
.heren,, an, the shear „n the ,,in, at their maxin a I . h
.reae., allowable shear is, aecor.lin, ,0 llentl " X - X 7'
">, on a steel pn, n, opposite direetions. or a sin.^ie steel bar
a.:uns a steel bearing, the pin in certain eases wi 1 e ,h, I
:::::u:::Ltr::?is:-' "" •"-'"- ■-- - '- ^■'"'
channels can be found after uli.v-i, h '-"-cwccn post
tars in the bridge ^^'i:^^:^:^ ^^^^Vl^' '"^
- -npletl on the same pin pnll i„ ,he sante direct! nunes
1^*
82
()AW>/.\.l/n /A'<>.\ ///</////./ J -A'AV/^i/A'.V.
as to reduce the hen(lin<;momcnt.s ; and that the dia-jjonal ties
be placed close to the posts, and the beam han^^ers close to
the ties. ICspecial care is needed at the panel point where the
number of chord bars is different in the consecutive panels. It
is possible to arranj^e the bars there, so that there wilt be an
extremely large moment produced, or so that it will be smaller
than at any other panel point of the bottom chonl. The ne<;lect
of any of these precautions will cause an undue bending-moment
on the pin.
The arrangement completed, the next questions to be decided
are, first, under what condition of loading will each pin take
its greatest bending moment, and, second, at what point on
the pin will this be found. In large bridges, and in many well-
proportioned small ones, the bottom chord pins are subjected to
their greatest bending-moments when the bridge is fully loaded.
Under this condition, the stresses in the chord bars can be taken
from the diagram of stres.ses; but those in the main diagonals
must be calculated for the load covering the whole bridge, and
their horizontal and vertical components be ascertained.
After having hail some practice, one will very often be able
by simple inspection to decide at what place the greatest
moment of flexure will exist ; but, if not, it will be necessary
to calculate the values of both horizontal and vertical momenls
at different i)oints, and find where their combined result is a
maximum. As Professor Burr shows, the actual moment is
represented by the diagonal of a rectangle whose sides repre-
sent the vertical and horizontal moments. It is usually more
convenient to square the component moments, aild the results,
and extract the square root of the sum, than to make out a
diagram.
The moments of the stresses can be easily recorded by draw-
ing two curved lines, as shown in the accompanying diagram,
representing the directions in which tlu'
stresses tend to bend the pin, and writing
each moment as calculated under one or
other of them, according to whether it would
|)rotluce ])ositive or negative rotation. The
difference between the sums of each column will give the actual
: 1:
!■'
o/w/x.i/n- /A'o.y ///<;// ir.i r-/,>A7/jf;/;',s-.
83
led bv dr:uv-
horizonal or vertical moment, as the case may be. The ondi-
ii..n that a load covering the whole i)rid-e may not produce the
-reatest moment in the bottom ehord pins is either when there
is a sm-le counter coupled at the centre of the pin, or a main
(liaj;onal coupled at a distance from the member that takes up
its stress. As a rule, single counters and single beam hangers
are to be avoided, on account of the unnecessarily large bend-
in-moments they produce. The size of pin for the hip joint
depends greatly upon the arrangement of the bars which it
couples. In a double-intersection bridge, where there are two
hip verticals, two long diagonals, and two short ones, the best
arningement is to put one pair of diagonals on the outside of
the chord, and the other pair inside, close to the bearing; the
verticals coming next, and being kept apart by a filler. Some-
times it is not advi.sable to couple outside of the chord, in which
case the moment would become so great, that it would necessi-
tate the employment of a pin whose diameter would make the
heads of the eye bars too large for the space allotted them. In
such a case, a steel pin can be used to advantage. IIinr--ed
ends at the hip joints require large pins, for the entire stresses
in both chords and batter braces come upon them with great
leverage, due to the necessarily large bearing-surface. Such
a connection is not advantageous : it is better to allow the
channels to abut. Such hinged ends are a great convenience
in erection, but usually necessitate an increase in the sizes of
the batter braces and the top chords at the end panels. A
detail to obviate this necessity will be given in Chapter XIII.
It is not neces.sary to consider the bending-effect of the
stresses in the lateral rods upon the chord pins, for the wmd
and the live load are not supposed to act simultaneously.
Lateral rods should always be so connected to the chord pins,
that the effect of the stress in the outer one will be to diminish
the horizontal component of the moment on the pin ; i.e., if the
tendency of the chord and web stresses is to bend the pin con-
vex to the middle of the bridge, the outer lateral rod should
IK.int towards the middle ; but, if it be to bend the pin concave
to the middle of the bridge, the outer lateral rod should point
towards the nearest end of the span.
^1;
84
ORDINARY IRON HIGHWAY-liRinCES.
The ends of pins have to be reduced in diameter, so that the
nuts and pin pilots may be screwed thereon. Care must there-
fore be taken in proporiioning small pins to see that sufficient
area be left under the root of the thread to resist the tension
on that section caused by the greatest transverse components
of the stresses in the lateral rods. The principal objection to
the use of large pins is not always the undue weight of the
pins themselves, but the increased size of the chord and tie-bar
heads, and the room that they take up.
On the other hand, it is not always desirable to use the
smallest possible pin, as the width of the bearing is an inverse
function of the diameter of the pin : so if, owing to the neces-
•'ty of a large number of rivets, the re-enforcing plates be long,
. micht be economical to increase the diameter so as to reduce
.le width. Thickening the heads of eye bars has an injurious
effect on the pins, although a beneficial one upon the heads, for
the lever arms of the stresses are thereby increased.
Bridges with weak pins will not necessarily fail by the rup-
ture of the pins. The reason for this is thus stated by Professor
Rurr: "The distortion of the pin beyond the elastic limit will
relieve the outside eye bars of a large portion (in some cases,
perhaps all) of the stress in them. This result will produce
a redistribution of stress in the eye bars, by which some will
be understrained, and the others correspondingly overstrained.
Thus, although the pin may not wholly fail, the safety of the
joint will be sacrificed by the overstrained metal in the eye
bars."
ORDINARY JROA' HIGnWAy-BRWuES.
Ill
so that the
must there-
it sufficient
the tension
components
)hjection to
itrht of the
I and tie-bar
to use the
s an inverse
I the neces-
.tes be long,
as to reduce
an injurious
le heads, for
by the rup-
by Professor
ic limit will
some cases,
,vill produce
:h some will
)verstrained.
afety of the
in the eye
85
CHAPTER XI.
PRACTICAL METHOD OF PIN PROPORTIONING.
The ordinary method of pin proportioning is to figure the
diameters of a few principal pins, and to make the others of
the same sizes. Thus, by inspection, can be found which pin
near the middle of the bottom chord is subjected to the great-
est bending-moment. If there be an even number of panels in
the span, it will be the middle pin ; but, if there be an odd
number, it may be the first or second pin from the middle,
according to the number and arrangement of the chord bars.
The vertical component of the bending-moment on any one of
these pins is so small in comparison with the horizontal com-
ponent, that it may be neglected. For bridges with an even
number of panels, —
Let
T = tension in middle panels of lower chord,
and
u> = the average thickness of chord bars in these panels ;
then, appro.ximately,
— = bending-moment on middle pin.
This formula may be applied, but perhaps with less .ccuracy,
to a bridge having an odd number of panels ; and, if the chord
be properly packed, the error will be upon the side of safety.
With the exception of the chord pins at the shoes and at "the
first panel points from the ends of the span, all the lower chord
pms may have a diameter corresponding to this ma.vimum bend-
mg-moment.
86
ORDINARY IRON HIGHWAY-BRIDGES.
To find the size of the lower chord pin at the first panel
point, use the formula,
H =
Trt)
for the horizontal component of the moment, and the formula
for the vertical component ; t being the intensity of working-
stress for the hip verticals, A their area (S. R.), to be taken
from one of Tables VI., VII., and VIII, <•/ the diameter or thick-
ness of a hip vertical, and d' that of a beam hanger.
The moment given by the formula
applied to Table XII. will determine the diameter required.
This diameter is to be used also for the pin at the shoe.
To find the size of a hip pin, lay off the stresses in one hip
vertical and one end main diagonal to any convenient scale, and
find the value of their resultant by the parallelogram of forces.
This resultant will determine the thickness of the bearing, a
trial diameter being first assumed. It is possible that this bear-
ing will have to be increased, so that there will be enough iron
to transfer the stresses from the batter brace, hip verticals, and
diagonals to the chord, as will be explained in Chapter XIII.
An appro.ximate test of the sufficiency of the bearing in this
respect may be obtained as follows : —
Let
A — the area of the section of the end panel of the top chord,
t/ = depth of cliord channels,
/ = thickness of web of an entl cliord channel ;
then the bearing should not be less than that given by the
formula
2(1
Ne.xt find the distance / between the centre of the bearing of
ORDIXARY IROX HIGHWAY- lU^IDGES.
«7
he formula
the chord and that of the diagonal, also the distance /' between
tiie former and that of the hip vertical, the latter being on the
inside. Calling the stress in the hip vertical F, and that in
the diagonal 5, the vertical moment will be /'/', and the inclined
one .S7. Next lay out these components to any convenient scale
in their proper directions, and find their resultant by the paral-
lelogram of moments. This resultant will determine the diame-
ter of the pin.
If the diameter found agrees with the one assumed, or if it
iloes not agree, provided that the bearing was not determined
by the trial diameter, all right; but if the bearing were so
determined, and the two diameters do not agree, another trial
must be made.
Where there are more than two main diagonals coupleil at
the hip, as is the case in double-intersection and in very heavy
single-intersection bridges, one pair is coupled on the outside
oi the bearing, and the other on the inside ; so that theoretically
the greatest bending-moment is equal to the .stress in the outer
l)ar multiplied by the cHstahce between the centre of the bar
and the centre of the bearing. Ihit practically the moment may
be greater, for the distribution of stresses among the diago-
nals may not l)e as assumed : so it is well to determine The
moment by imagining the outer bar not to e.xist, and proceeding
as explained above for the case of only two main diagonals al
the hip, excepting, of course, that the thickness of the bearing
must be ascertained by finding the resultant of the stres.ses in
the two diagonals and the hip vertical.
To calculate the size of an intermediate upper chord pin, the
wi.Uhs of chord and post bearings are to be determined as shown
m Chai)ler XIII. The former is given approximately by the
last formula, where A is the section of the panel of the chord
on the side of the pin towards the miiklle of the bridge, ami t
the thicl<ness of the corresponding channel. The other is given
I'V the formula
where A, is the area of the section of the post, and h the depth
of one of its channels.
88
o/w/y.'iA'y /Rox higiiwa y-bridges.
Next resolve one-half of the diaj^^onal stress vertically and
horizontally into /' and /'' respectively. Let / represent the
distance between the centre of the diaijonal and that of the ex-
tension plate, and /' the distance between the former and that
of the chord-bearing ; then
V = PI,
II = P'l',
and
M - V'//' + V\
If the bridge be a small one, it will be necessary to calculate
only the size of the pin at the top of the first vertical post from
the end of the bridge, and to make all the intermediate top
chord pins
of th
e same size.
But, if the bridge be a large one,
it will be better to calculate the diameter of the pin on the post
midway between the end vertical post and the middle of tlie
span, and to make all the pins between these places of this
diameter, and all the others of the same diameter as that at the
eml of the first vertical p'>st. After the diameters of the top
chord pins are determinetl, the post and chord bearings should
be tested by applying one of Tables XXVI. and XXVII., al-
though in most cases they will be found ample.
In double-intersection bridges, where the diagonals are halved,
and coupled on pins passing through the middle of the pysts,
the size of any one of these pins may be found from the
moment
M = — ,
I •
Ifi
n
where 5 is the stress on the diagonals as given on the diagram
of stresses, and w the width of one of the main diagonals.
In all pin proportioning it must be kept in mind that the
diameter of the pin is never to be less than eight-tenths of
the depth of the deepest bar coujiled thereon.
The author wisiies to call attention to the superiority (in his
opinion) of the simple method given in this chapter for propor-
tioning lower chord pins by formula over the apparently more
accurate one given in the la?>l chapter.
OKDIiXARY //WA' HIGIIU'A V-HIUDGES.
89
In this method, when the proper proportion of width to dei^th
ol bars is adhered to, the diameter of the pins will be ahnost
e.^ht-lenths of the depth of the bars, and will be great enou-h
to res.st the bending- moments ])roduced by any legitima^'te
metliod of packmg. Moreover, after the diameters of the pins
have been determined, the ehord ean be packed, if it be advisa-
ble, so as to reduce the bending-moments. This supcrabun-
<lance of strength in the pins is obtained at the expense of a
slight increase in the weight of iron ; and the increased sizes
ut heads for diagonals can do no harm, because they do not
enter any limited space, as do the heads at their other ends
J5ut if, by a skilful arrangement of the packing, vvc can so
reduce the bending-moments on the pins, that the diameters
ma)- be made small, and the proportion of width to depth of
bars larger than that found in the last chapter, the pins may
not be as strong as wc imagine them; for we cannot be sure
that al the bars are going to pull as we have assumed that they
w. . It may be that one of the outer bars is a trifle long, and
will not pull at all until the others are well stretched : what
then, becomes of our calculated bending-moments ?
Any one of them may be so greatly exceeded, that the pin
will be strained beyond the elastic limit, and will bend percepti-
bly, so changing the distribution of stress in the panel that one
or more of the bars also may be strained beyond the clastic
limit.
i^ut if the pin be large enough, or more than large enou-h
.t cannot bend perceptibly : consequently the distdbution"of
stress will be much more uniform, even if the bars be of shVhtlv
unequal lengths. ^ ^
90
OJW/.WlAy JROA- UIGIIWAY-BRIDGES,
■ I
J,.
CHAPTER XII.
RIVETING.
The subject of riveting is one, which, like that of pin propor-
tioninf^ has never received its dr.e amount of attention from
bridge designers. Many structures otherwise very strong arc
extremely weak in detail, owing to the insufficient numlu'r
of rivets employed in the connections and to their improper
arrangement. The principal rules for riveting have been given
in Chapter II., pp. 17, iS.
Rivets should be proportioned for bending and for bearing
pressure ; i.e., for any given connection, the number of rivets
necessary to resist properly each of these stresses should be
determined, and the greater number chosen.
Tables XXXVI. and XXXVU. give the working bending,
moments and permissible bearing-pressures for bridges of Class
A and for those of Classes B and C. For the lateral systems kA
both classes. Table XXXVII. is to be used. In these tables
the first and second horizontal lines of vulgar fractions and
decimals give the widths of bearings ; and the other horizontal
lines in the portions pertaining to bearing give the working
bearing-stresses for rivets of different diameters. The rest ot
the tables needs no explanation.
The sizes of rivets ordinarily employed for highway-bridges
are from five-eighths to three-cjuarters of an inch ; though half-
inch rivets are used for very light channels, and seven-eighths
inch rivets for very heavy ones.
The weight of a pair of rivet heads for any diameter can be
found in Table XXIX. It is well to memorize the.se weights.
Where two plates are riveted together, the rivets, driven
when hot, contract, or tend to contract, in length when cooled.
pin propor-
L'lition from
ir improper
ORDIXARV IRON HIGHWAY. nRiPGES. g,
thus drawing the plates together, and produeing a friction which
It IS necessary to overcome before shear can come ui^on the
rivets. Whether this friction will continue indefinitely is doubt-
ful, for rivets occasionally become loosened when the structure
IS subjected to oft-repeated loads : so it is not legitimate to
depend upon the friction in order to reduce the number of
rivets. I'erhaps it is on account of this factor that rivets are
seldom, if ever, proportioned to resist the bending-moments
that come upon them, notwithstanding the fact that it is this
last consideration, which, in most cases, should determine the
number of rivets to be employed.
Again : if the friction were to be depended upon, it would be
only right to allow for the initial tension on the rivets, which
tension is sometimes great enough to force off the heads
_ It will probably have been noticed by the reader, that' shear-
mg-stress upon rivets has been omitted altogether from con-
sideration. The author would hesitate before making the broad
assertion that rivets cannot shear, although it is probable that
bending is the stress which ruptures rivets that are generally
considered sheared. This much, though, he will statl- as the
result of both theoretical investigation and many practical cases
ot designing, that, xvhen rivets arc proportioned foy bcndiug aud
bearing, they ,vill have more than snfficient strenq-th to resist shear
Sharp edges on rivet holes will certainly cut the rivets, but this
IS not shear proper ; and it may be possible that there is a cer-
tain kind of fi.vedness about a well-driven rivet which will make
the bending-moment less than its calculated value
Should the reader wish to verify the statement concernino-
bending and shearing stresses, he can do so by using an intei"
sity of shearing-stress of three tons for bridges of Class A, and
one of three tons and three-quarters for those of Classes B and C
1 he theoretical proof is identical with the one for pins given in
Chapter X.
"Countersinking" is a term used to denote the sinkino- of
nvet heads mto the plate so as to make them flush with its
surface. The least allowable depth for the countersinkino- is a
quarter of an inch, and the least thicknes.s of plate used for this
purpose should be three-eighths „f an inch : fur rivets e.xceedin^^
92 OKDLXANV /AV.V IIIGUVVAY-HRIDCES.
three-quarters of an inch in diameter, these dimensions should
be increased by an eighth of an inch. Rivets may be counter-
sunk at one or both ends.
Making parallel rows of rivets staggered avoids unnecessary
weakening of the parts riveted together.
There has been much discussion as to whether punched or
drilled holes are preferable ; the general conclusion being, that
drilled holes weaken the plates less, and when slightly counter-
sunk, so as to avoid sharp edges, do not increase the shear upon
the rivets, but that punched holes arc so much more economi-
cal as regards shop-work, that, when properly made, they are
preferable to drilled ones. The improvements made of late
years in riveting-machines have increased the efficiency of work
with punched rivet holes.
Should, for any reason, it ever be necessary, in bridge design-
ing, to put a rivet through a plate whose thickness is greater
than the diameter of the rivet, the rivet hole should be drilled.
Machine riveting is preferable to hand riveting, but there are
cases when the latter has to be employed.
Field riveting is nearly always inferior to shop riveting.
When a stress is transmitted from one plate, through one or
more plates, to another plate, the number of rivets must be
increased. The rule given by Weyrauch is, that, "for every
single shear connection, the indirect force transferrence requires
for m intermediate plates ;;/ -f i times as many rivets as for
direct transferrence." Keeping this in view, the designer will
avoid using more than one flange plate in floor beams, or more
than one plate for covering the channels of the top chord.
ORD/xXARy //WA- HlGimAV-URWUES.
93
miecessary
CHAPTER XIII.
PROPOKTIONING OF OTHER DETAILS.
The sizes of stay plates used at the ends of systems of lat-
ticin- or double-riveted lacing are given in Tabic XXXII , and
the sizes of those used at the ends of systems of single riveted
lacing, in Table XXXIII. The headings of these tables fully
explain their use.
Stay plates are to be employed at the middle of posts {vide
Plate II., Fig. 15) when the diagonals are halved, and connected
by pins passing through the posts ; their sizes being taken from
the before-mentioned tables. Stay plates, if they can be so
called, are also to be used on the lower portal struts, for the
purpose of attaching the knee braces.
Pin bearings are .sometimes figured, counting in both re-en-
forcing plates and web; but the latter is often omitted. This
would be necessary when the holes in the web are bored inde-
pendently of those in the re-enforcing plates, for then it is very
inij'iobable that the different holes will coincide; but, when the
re-enforcing plates are riveted to the web before boring, such
a precaution is not only unnecessary, but is a waste of material
Py consulting Table XXVIII. can be found at a glance,
accurately enough for all practical purposes, the thickness of
web of any Union Iron-Mills channel bar, when the wei-ht is
given, or vice versa. '^
Where re-enforcing plates act also as splice plates, there
should be one on each side of the web in order to insure a crood
substantial joint ; although the practice in the building of small
bridges IS to omit the outer plate when the pin bearing does not
demand its use.
The length of a simple re enforcing plate depends upon the
ill
m
94
ORDINARY IRON IJIGHWAY-BRIDGES.
miinbcr of rivets roquircd, and is thus determined, l-'ind, by
dividing tlic stress given on the chagram of stresses between the
various thicknesses of iron which constitute the bearings, the
amount of stress which the plate considered is to carry. It is
well, though, to make a liberal allowance, say twenty per cent,
^or the possibility that the stress may not be divided propor-
tionately to the thicknes.ses. Ne.xt multiply the stress so ob-
tained by the perpendicular ilistance between the central plane
of the re-enforcing plate and that of the plate or web reen-
forccd : the product will be the moment of the stress upon the
re-enforcing plate Divide this moment by the working bend-
ing-moment, taken from Table XXXVI. or XXXVII., for a
rivet of the diameter to be employed for the connection : the
quotient will be the number of rivets required to resist bend-
inc:. Next find, from one of the same tables, the working bear-
ing-strcss for one of the rivets upon a plate of the thickness
of the re-enforced plate or web, and divide it into the stress
which the lallcr carries : the quotient will be the number of
rivets requiretl to afford sufficient bearing. The greater of
the two numbers thus obtained is the one to be employed.
Ne.xt make to scale a drawing of the re-enforcing plate, laying
out the rivets, if it be possible, symmetrically, and thus deter-
mine the length of the re-enforcing plate. In case of a re-
cnforced pin hole, if the diameter of the hole exceed one-half
the width of the plate, it will be necessary to jiut more rivets
in front of the pin hole than behind it ; the ratio of the num-
ber in front to the whole number being equal to that of the
diameter of the hole to the width of the plate.
The method of proportioning splice plates or connecting
plates is somewhat similar. For instance, let us take the jilates
at a joint in the top chord ; which joint, for reasons to be stated
in Chapter XVIII., is always to be placed a few inches to that
side of the pin hole farthest from the middle of the span. The
stress on the portions of the plates to this side of the joint is
that due to the stress in the panel where the joint occurs ;
while that on the other portion of the plates is due to the stress
in the next panel towards the middle of the span. The number
of rivets on each side of the joint will be dependent upon the
ORDIA'ARV IROX niCHlVAV-HRlDGES.
.trcsscs carried by the channel bars of the two adj
95
'I'll
le simplest way to (ind the stress
ply its area by the intensity of working-st
acent panels,
on any channel is to miilti-
from either Table X. or XI. Th
equally, or otherwise, between the outer and
splice the abuttinj,^ channel
sary to resist bendiu';- and be
ress, which was fouml
is stress is then to be divided
inner plates which
s ; and the number of rivets iieces-
uinj;- are to be ascertained in tl
manner explained for re-enforcinj; j)lates.
To determine the length of a cover plate, find in th
manner the number of rivets ///.„/ each su/c of the joint, which
-111 take up the stress carried by the chord i)late, and
le
e same
the cover plate with th
by
plate, and lay out
c rivet si)acing to scale. The stress car-
ried by the chord plate is equal to its .sectional
area multiplied
by the intensity previously found for the channels.
At the hip joint it is obviou.s, that, where the chord and batter
brace are hni-ed upon the pin, the resultant of the thrust in the
battrr brace and the pulls in the diagonals and
^•(|
iial the thrust u
poll the chord, and that the be
figured for this thrust; but, where tl
section of the splice plates mu.st answer two ...,..,_
hrst, their area (neglecting, on account of its bein- "be
citect of the cover plate) must b
verticals must
aring must be
icy are not hinged, the
requirements :
nt, the
10 sufficient to transfer t
the chord a stress equal to that in the first panel ; and
o
that the pin bearing be sufficient {
se
cond.
sioiiy in the diagonals aiu
length of the cover i)late at the h
or the resultant of the t
en-
It carries no stress, simply ad
verticals meeting at the hip. The
ip cannot be calculated ; for
md keeping the rain therefrom
Iding to the rigidity of the joint,
It the posts be figured f(
ate of the chord
)r one fixed end, th
nocting plate for the post ; and
can be extended downward to act
e inner splice
as a con-
ciiuugh rivets used
ail th
in this case there must be
Ml respect to bearing and bending to transfei
i)lat
e compression in the post to the chord by th
c, under
th
e coniiectiiiL'-
e su
llO 11
pposition that the ends of the post channel,^
tnlich
llDo
ot touch the flanges of the chord channels If
so much the better; but it would not be safe
slmuk
II their doing so. The thick
they do
to count
be such that it would not bend bet
ickness of the connecting-p]at(
ween the end of th(
w.
96
f'/.7'/.\'./A')' /h'o.y ii!i:iiw.\y-nRiiH;i:s.
post and tlic pill IkiIc wlu-n the post would be on the point of
riiptiiic by compression. Where the ends of the posts ;ire
fi^^ured iiin;j;cd, which is a decidedly better construction, the
cxtennion plates pass inside the splice plates of the chord, and
are attacheil to the pins. As before, there must be enough
rivets to transfer the stress in the posts to the plate.
The thickness of the re-enforcing plates at the lower end of a
post is determined ' y the bearing recpiired, and their length in
the manner already described, It is l)etter to place these plates
on the inside of the posts ; then, if the llaiiges of the channels
be i)artially cut away, an extra plate (at least three-eighths of an
inch tiiick) can be placed on the outside of each channel. The
reason for cutting away the bottoms of the post channels is
merely to [jack the cliord more closely, and thus reduce the
bending-moments on the pins. lUit, if the method of pin pro-
portioning given in Chapter XI. be adopted, the necessity for
cutting away the channels, to any extent, vanishes ; for at the
middle of the span the web stresses are so small, tliat their
moments are neglected, and the pins at the feet of the other
posts have an excess of strength.
In high double intersection truss bridges with long panels,
the diagonals become so long, that it is convenient to halve
them, and connect the halves by pins. It is then advisable to
let these pins pass through the webs of the ]i()st channels where
the diagonals cross, for the latter then tend to stiflen the pcjsts.
If intermediate struts also be used at the middle of the trusses,
the posts can be figured for half length, with both ends hinged.
On account of the stretch of the main diagonal, there would be
a tendency to deflect the post. If the diagonals were forty-two
feet long, the stretch of the upper half of them would be about
one-eighth of an inch ; so that, to avoid this objection, it will
be necessary to elongate the pin hole that amount on the lower
side, in the direction of the main diagonal. The pin V I'-s
should, of course, be well re-enforced in order to compen-
sate for the material cut from the channels. The stretch of
the counters being less than that of the main diagonals, and the
posts crossed by the heavy ones generally having an excess of
strength, it is <iOi uccessary to elongate the pin holes in the
direction of tl.e 1 ;. 'th 'if the counters.
('/^•n/x.i/n- ,A'ox iin:nuAv_,a„nr.i-:s.
In nearly all iron l)ri<l-,>s (Ir. hatti-r I
•nils fixed at the pedestals (
97
i.e., tliev are ri
nraees are made with
"e plates), although hinj,^,.^ p^dc-stal
tlie aJvanta^^' j^ained by tliel
fftrndy distributed pi
r use is the certa
(idly attached to thi
'110 not unknown
essu
re on the rollers, and the disad
inty of a uni-
a Kroat nierease in the section of the batter 1
I he shoe plate can be attached
I'.v bent plates on the inside, the
iif channels, with
vanta;:c
>races.
t«) the batter-brace channels
outside, or both, or by pieces
oiic flange removed, placed on tli
C' inside, and
:haii-
I . ami U,,„,„ , .|,,ir nances t„ ,1,. ,h„c. „la,
"'it^' IV. The lower end of the b
tiiMied up horizontally, an
plate, as shown on
:itter-brace plate should be
Tl
ie area
of
iveted to the shoe plat
a section of the connecting channel
'"a.le by a plane perpendicular to the d
hraee should be ecpial to the area of
>r greater if the shoe
\\"i'lcl afford ; and there should b
or plate
irection of the batter
one batter-brace channel,
an this
pin require greater bearin- th
stress from the batter-bracc channel to th
'^ enough rivets to transfer thi
>i" I>late. Should the b
shoe plates, as they ought to do, th
iccessary; but such a 1>
:itter-brace channels bcai
10 connecting channel
against the
ere will be more rivets th
Details of sh
•earing should not b
an
oes are shown on i'lates II., HJ., ly
e counted upon.
The rules for proportionmg shoe
,!;i\eii on p. 1 6.
very good connection for the h
rollc
and V'l.
r, and bed plates, c
iro
I'lates III. and IV. Th
I'lider one passing entirely below th
P joint is the one shown on
Miner si^lice plate has five sides, the
:Ue is cut to fit closely to the wei)s of
10 joint ; and the outer splice
hnice channels, bei
the chord and batt
DC
thi?
Is and the rivet heads th
' ■^•'■' "" ^"'- euuKi anti batter-
ng made as wide as the flanges of the chan-
s detail is, that it re
lerem will permit The objection
uiother good detail for tl
■quires a good deal of field
to
rivet inc.
''late II. Ifereth
"f the chord, and
us
joint is that shown
in F
'g- 14.
wh
plates riveted to th
those on
ere are two connecting-plates on the outside
t^vo on the mside of the batter brace, through
se on the chord abut against
ieh the pin passes. Tl
U)
-_ outside of the batter-brace channels"; and
the batter brace abut
against plates riveted to the
'A7V.\'./A') /AV'.\- l/liliniW !
-llh'/PilF.S.
itisu
le of t!u> chord cliaiincls, all ahuUin^ surface
hcini
planed
to fit exactly; so that, when the
in is driven into place, tlie
th
t will be as ri-id as if it were nveled
whole joui
<letail demands neat worknuuis
Of course this
hip, and is consequently
some-
what expensive
counlerbalances
but the satisfactory result attained more than
the extra cost of the shop-work, and there i^
no neee
ssity for figuring on
a hiiiLrei
i ^-xuX at the hip when
Mdpoi
:hord.
lionuu
•ooil me
•hor
the batter brace and the end panel of the top
thod of attaching the upper lateral struts to the
which is illustrated on Plates II., IV,
the foUowini
hortis IS ine iomuwhil;, uim.. .-- ...-■•-
nd VI. Let the web of the upper channel lie upon the cover
plate of the chord, extendi n
thereto
ami
let the uiK
ler f;
beiiv' turned downwan
faces (.
if the lower
Ham
length of the lowei c
pie of inches shorter than the clear roac
ccni
The coiuieclion is mai
to its outer edge, and be riveted
ice of the lower channel, its ilanges
lie in the same horizontal plane as the
:s of the toji chord channels. The
f the lateral strut should be a
way of the bridge.
\annel o
tter
the head being rive
Ic by a plate in the form ol the le
led to the lower Ilanges of the inner cluatl
Is, and the stem pass
channels,
lower channe
be riveted. The thic
of an inch, and the \\'<
iiu
between the tlanges (
if the
1 of the lateral strut, tt) the we
) o
f which it is to
kness of the T-plate shoultl be five-ei-hths
ntrant angles siu
)UU1
be rouiulec
oil with
a radius
ol an inch am
half or two inches
The wiillh ot
the stem s
louk
1h' matle
is ureat as the elis
lance betwt'eii the
f the lateral >lrut will permit, ami Lli
flanges o
equal to the width o
It of the head
f the tlanges of the chord channels
Tl
le num
her of rivets tor either stem or he:
tl must be calcu
1 ilcd for bending and bearing resistances corresponding to the
..•reatest stress that couul ever come upon the channel, which
stress is to be calculated by multiplying the area of the channel
by the intensity found in Table XI.
'a ..ood connection lor the iiUermediale slruts to the posts
is by'means of two l.enl plates at each end ol the strut (vur
ITites IV. an ; \-l.). One le.' of each plate is riveted to the
web of the inner ch.nme! of the post, and the other to the web nt
the I-beam, which i> placed horizontally The vibration rods
ORniXANY tRox jinnin-Av-nRiiKiF.s. gg
arc attached by holts that pass thro„,-h the two connecting-
plates and the wel) of the I-heanv The connection at th^^
upper cm\s of the vibration rod may be similar, if tlie width
nl the T connectmg-plate be great enough to permit of the
jiassage of a bolt.
At tlie intermediate strut connection, there should be cnou"-h
nvels used ,n respect to ben.ling and bearing to transfer the
calculated stress upon the strut to the connecting-plates
If there be but one portal strut at each end of the span it
may be connected to the batter brace by two large bolts passi'n.
through a jaw plate, as shown in Mg. , ,, Plate II. These bolts
■nay have square heads placed so near the sides of the jaw that
t ey cannot turn, the nut having to be screwed upon the ins.de
' ho atter brace. But. if there be two portal struts at each
--' "f the .span, the channels are to be turned around ninety
<legrees. an<I brought nearer together; so that it will be better
n use exter.or bent plates attached to the flanges of the chan-
U.s shown on Hates IV. and VI.. in addition to a single
lai-e bolt through the jaw.
Concerning the best method of connecting the lower lateral
nnls. there ,s much chversity of opinion ; although, in ninetynine
cases out o a hundred, they are attached to the floor iLml
wh.ch are thus made to act as struts for the wind pressure'
-Some brulge designers put bent eyes on the lateral ods, and
■un .jsu^^
^ ohjec lonable, for two reasons : First, the laterals take hold
.he weakest part of the beam ; and second, beu.g attach.U^
- ;'^ --/'-" the pins, they permit of too much vibration,
•^nothe.cle tad ,s o rivet two 4 by 6 inch angles to the web, and
;-;:;;^ P- through the six-inch legs : this is a little better dm
In.' the .same objections apply here. Another is to let the 10 Is
pass U..ough the webs, and through rods and plates bent t ;;;':
-nc .ace ,s perpendicular to the direction of the lateral rod
a- her face parallel to it. and the ot-ier two end faces nr 1 el
';• the web of the beam, to which they are riveted. The^
:'''l- 'ons apply to this, together with two which are sti nTre
"■1-tant vz.. that, as at each connection there are to such
"'-- -^'"- lateral rods from adjacent panels cri:: h
II! Ki B'ii 1- ;'
illirw
lOO
O/wrXARV IROX UICIIWA Y-P.RI nc.F.s.
other the lon-itiulinal components of the stresses m tlie latter
produce a moment tending to revolve the beam about the upper
ed-e of the web. Then, again, the bent plates must be made
solieavy that they would withstand, before bucklmg, the ulti-
mate pull of the lateral rods ; and it is very seldom that such
a detail is made strong enough to stand the ultimate pull of an
inch and a half round rod. Another way is to rivet a plate across
the top of the beam, and two bent plates or large angles opposite
each other, just below the top flange, dropping i)ins through the
jaws thus formed. This is the best arrangement yet employed.
But in the author's opinion all these details are defective, for
the reason that the lateral rods all take hold of the floor beams,
which are simply suspended from the i^ns that are several
inches above them ; so that, unless the hangers be screwed up
very ti-htly, any wind stress in the lateral rod will cause a
rockino°at the point of suspension, and, even if the hangers be
screwJcl up tightly, the tcmhncy to rock still exists. Ihe only
correct place to attach the lateral rods is to the chord pins, ami
their stresses should not he transmitted through the floor beams.^
Then come the questions, MIow shall they be transferred?
and " How shall the rods be arranged so as to clear the joists .
The detail about to be described will answer these questions.
Upon the floor beam place a stick of square timber (about
ei-ht inches for ordinary highway-bridges), and let the ends fit
into wrought-iron jaws, which screw up against the chord pins ;
then fasten the timber every few feet on alternate sides of the
web by half-inch bolts, to the flanges of the beam, and rest
the joists on the timber. The laterals can either be attached by
bent eyes to the chord pins (which would be preferable if then-
diameters do not exceed an inch and three-fourths), or by ordi-
nary eyes to vertical pins passing through the wrought-iro.i
jaws In this way the timber not only acts as a lower lateral
strut, but serves to give additional stiffness to the floor beam;
although the section of the latter should not be diminished on
that account.
Now, what objections can be raised to this method ,'
Some may say that it is a clumsy contrivance, but that is a
matter of taste. Others may suggest thai it reduces an no,,
'^''^'f>/.yANV //WN H/GI/ll'AV-B/UDGES. loi
structure to a combination bridge. Not at all, - no more tlian
the emi^loyment of wood for the floor and joists; because, at the
same time when the latter are renewed, the wooden struts can
be replaced. There is a slight objection for short throu-^h-
sixms y,z., that it reduces the headway; but it would not
greatly increase the expense to add eight inches to the depth
ot the trusses. ^
Another method of avoiding the difficulty is to rivet the floor
beams to the posts. But will not this be equally objectionable }
Certainly such a connection is better for the beams, as it par-
tial y fixes their ends ; but what about the deflecting effects of
u-md stresses and passing loads upon the posts.' The trans
verse components of the lateral rod stresses act with o-r^at
leverage, tor the beams are always attached above the boUom
chords ; and the weight of a heavy wagon coming suddenly
upon the beam must certainly cause the posts to vibrate trans-
versely to the planes of the trusses, but to what extent, and
with what injurious effect upon the posts, it is at present im
possible to say. I.:ven if there be but little known concern-
j"g this attachment, it is certain that a floor beam should never
be riveted to only one of the channels of each post. Such an
arrangement would produce indirect stresses of a destructive
character: consequently the posts should be turned one-quarter
way round in order to let the beam pass between them
•• l.H.r beams in deck bridges may either rest upon the chords,
I'o uing trom the chord pins, or be riveted to the posts In
neither case should they be used as lateral struts when the
lateral rods are attached to the chord pins, because of the lever-
age^that would be afforded to the lateral stresses to produce
It is not customary to calculate the thicknesses of beam-
'•n.^ci plates, for they are usually made from three-fourths of
■nchtoanmch thick for ordinary highwavbridges ; but
n|u cerain assumptions their thicknesses can' be calculated.
tHc load on a plate be consi.lered uniformly distributed over
^' l-t.on between the beam-hanger holes, and if the flange of
;;l;;;'nn>c supposed to take up no bending-stress, the plate
'"■'> '>^ -nsidered as a beam supported at the ends, and uni-
lo:
ORD/XARV IRO.V HIGHIV AY-BRIDGES.
ii
iMi
lflW»s
formly loaded. For instance, take the case of a twenty-foot
panel and an eighteen-foot clear roadway, the re-action at each
end of the beam is about nine tons. Suppose the centres of
beam-hanger holes to be situated on the corners of a four-inch
square, and the plate to be seven inches square, then the bend-
ing-moment is
i)/ = J ?F/ = ^~ X 9 X 4 = 4-5 inch tons.
T? J
The resisting moment is — ,-, where R = 5 tons, / = moment
'^,
(i
of inertia = -^JhP = {..(P, and ^, = "■ Equating the moments,
substituting, and solving, gives <'/ = about seven-eighths of an
inch, a result agreeing with good practice. It is almost need-
less to say that this method is very approximate ; for the plate
is greatly stiffened by the rigidity of the flange of the beam,
while, on the other hand, no reduction has been made for the
beam-hanger holes.
Lacing, or, as it is often improperly termed, single latticing,
is about the most common detail for keeping pairs of channel
bars in line : nevertheless, it must be inferior to latticing,
especially when the lattice bars are riveted together at their
intersection. By inspecting Tables XXXII. and XXXIII. it
will be seen that a system of lacing-bars with one rivet at each
end of a bar requires much larger stay plates at the ends than
does a corresponding system of latticing or double-riveted
lacing.
The actual sizes of lattice or lacing bars for any strut can be
determined only by experiment : it is thought that those given
in Tables XXX. anci XXXI. are so strong, that the struts on
which they are employed would break in the channels rather
than in the bars, and yet not so heavy as to cause much un-
necessary use of material. It will be seen also in these tables,
that the requisite dimensions of latticing and lacing bars depend
not only upon the sizes of the channels which they connect, but
also upon the distance apart of these channels : this is due to
the fact that the bars are subject to compression as well as
to tension. The lengths and weights of latticing and lacing
OKI)/A-AKy /A'C.\- JIlCHWAV-liRlDGES.
103
I moments,
bars can be found from Table XXIX. It must not be forgotten
that these lengths are to be used for cstiinalcs only; as they were
obtained from a diagram, and not checked by calculation.
The smallest trussing-bars used should be no less than a
quarter of an inch by three inches, and the bend for attach-
ment should be no less than three inches long, so as to permit
of the use of two staggered rivets. The heavier the trussed
bars, and the greater the distance between them, the greater
should be the section' of the trussing-bars. At the encts of a
s\ stem of trussing, the bars should be turned and attached, as
shown on Plate II., Fig. 8, and on Plate VT.
The lightest bracket used should be no weaker than a 2.1"
X 2]" 4.9* angle iron, which section is to be employed only
to attach intermediate struts to posts. Where there is no
vertical sway bracing, the stresses on the brackets are to be
calculated as shown in Chapter VI., and the sections are to
be proi)ortioned by using the following table of approximate
intensities of workiuir-stress.
trut can be
I.KXCril (1F STRUT,
]N I'KET.
Intkn^.itiks of Wdkking-Stre
4
6
8
aj" X 2i" L.
3'0
2.0
3" X 3" L.
o -
jr X u" L.
4.0
3-5
3-0
The number of rivets that connect the bracket to the lateral
strut and jjost must be sufficient to transfer all the stress in the
bracket to each of these members.
To prevent the pedestal at the free end of a span from slip-
ping in the direction of the length of the rollers, the latter can
be notched about a quarter of an inch in depth, for a length of
about two inches at the middle, and the shoe plate andVoller
plate be planed down so as to leave projections which will
exactly fill the notches. This detail is illustrated in Plate VI.
For short spans, a sliding-joint such as shown on Plate III.
is to be used.
104
OKi)!.\\un- /Kox iin.nwAY-nRiiHiEs.
When it becomes neeessary to anchor down the expandinj;
end of a bridge, it should be done in such a manner that the
shoe could not rise more than an eighth of an inch : thus the
projection on the luuler side of the shoe plate will be prevented
from being lifted out of the notches on the rollers.
l?ed plates and roller jjlates should be anchored to the abut-
ments by rods with nuts. When the abutments are of stone, a
jrood method of attachment is to drill holes therein just below
the anchor bolt holes in the bed plates, enlarging them, if prac-
ticable, at the bottom. Split the ends of the anchor bolts several
inches, insert small iron wedges in the splits, drive the bolts
into place, so that the wedges force the split ends apart, thus
partially filling the enlarged bottoms of the holes, and pour in
molten sulphur.
In figuring lengths of fillers for pins, a clearance of from a
quarter to half an inch should be made, so as to allow for varia-
tion in thickness of eye-bar heads, re-enforcing plates, etc. : such
an allowance will sa\-e a good deal of trouble in erection. When
the end lower lateral strut is of such dimensions that it will not
fit, without being turned from the vertical between the ttanges
of the batter-brace channels, filling-rings can be used between
the batter-brace webs and the ends of the strut. Such rings
will be necessary, if there be four chord bars in the end panel,
and the outer ones be not let into the channel flanges far enough
to lie against the webs.
In making turn hurkles. n little expense can be saved by hav-
ing only one adjusting-end ; the other having a hole, through
which passes one end of the rod, which is enlarged into a heail.
One advantage of this style is, that the turn buckle can never
be lost from the rod. Such a turn buckle should always be
used on portal vibration rnds, for a reason that will be given in
Chapter XX.
Jaws are not a very desirable detail, although so convenient
that they are often employed. In the first place they have not
a pleasing effect to the eye; and in the second, on account of
the bent plates, are iiaole m ou wcakci lium rnight be esti-
mated. If the flaii.i;es of the channels be cut away, as is some-
times unavoidable, the jiiw plate, from the cut flanges to the
iM
O/W/A'.l/CV JA^OX HlGHH-AV-HRinGES. ,05
bend, should be able to resist more compression than the rest
o the s ru . Such a detail occurs often on the ends of the
struts wh.ch keep the pedestals apart. It is generally diffleult
to make a satisfactory design for this member, as it interferes
.'^V";?'l' rJ^''^'^ ''^^' '°"^''" '^^^•■'-^^ ^y^^*^"^ P'-eviously
(lescrd)ed, all the difficulty vanishes
Concerning the proportioning of eye-bar heads, there is a
variety of both op.n.on and practice. Many specifications call
nr a see .on a the eye ec,ual to one and a half times that of
he bar for welded bars, or one and a third times the same fo
ammered eyes, no,: taking into account the effect which the
Ifcrent rat.os of chameter of pin to width of bar have upon
t e s reng h the eye. Specifications for the better class
' -t radroad and highway bridges have of late made this
d..s .nctu.n but there seems to be some uncertainty as to wha
.s the e.xac effect of each ratio upon the strength. On p. 20 i
given a table for sizes of chord heads, prepared from actua
experiments by C. Shaler Smith. C.E.. who is considered th
X.St Amencan authority upon all matters connected with
he des.gnmg of bndge superstructures. The subject of chord-
head proporfoning is further treated in Chapter XVIII
]>cnt eyes do not make a very good detail, but are 'such a
conven.ence that they are often used by good desLniers If
he .ameters of the rods do not e.xceecl o^ne inch a hre
1-nths, here ks no objection to using such eyes. The prin pal
l;-t to be ra.sed against them is because o^ the eccentri:^^
^^ iK.y g,ve upon the pin nut. This objection n.ay be
n,o.ed by usmg e.ther extra large nuts, or the detail shou". in
:;;■'■ '^'''^' ;r' ^".""-^-" "^ ^'l^tes H. and IV.. in which
bcKt eyes pull aga.nst a piece of channel riveted to the
M ut A stdl greater miprovement is shown on Plate VI. in
;vh.ch a p.ece of bent plate is substituted for the channel • t'h
orm. s o more rivets in the connection, and avoids the pc'^^
h.h.M.t^ha^^.g to .nsert a filling-phue between the channjl and
In connection with this detail, on Plate VI. is another and a
athe, peculiar one. The plate, which was originally in the
""•'" ^'f the letter T, i.s bent .so that the stem n^a^Tbe r veted to
io6
oh'p/.y.u^y i/^'o.\ iih'.iiivA v-nRiiHuis.
the strut c'lianiu-ls, and the lu-ad may afford a lu-arinj; for the
vihration-iixl pin. '\'\\\^ i-oniici-tion is to hi- used whc-n llic hit-
oral strut chaiuu'
Is aiv so small that ihoiv is no room for a
pin to pass thront;)! tho coniu
tin- lowi'i' I
itinj;- T-plalo uliirh attache's
th
hanm-l. W'lu'ii, in-causc of th^-ir lar^o (lianK't(.T, tlu
loWi,'!'
ati'iai roils i.
annol ho attached lo the chord pins, 1
)nt
must he connected hy vertical pins passin;^,- throu^ii the lateral
strut jaws, they must he made lo pull on the midille point of
•h of the latter pins hy usini; a ilouhle eye on one of the rods,
huLie enough to admit the eye of the
eai
\\r
h a space hetween
otiier roil
Phis is to avoid al
tendency to rotate the lateral
strut ahout its a\i«;. The rods can he retained in place hy tillers
ahove ani
hel
o\v,
)Ui;h
>f the moment of the lon-;itudinal com
With this detail. thtMc is a tendency to hreak the jaw tlin
the pni holes, hecausc
ponen
1
I of the Literal rod stress: the jaw plate must therefore
■)e ma(
le wide enoui;h to properly resist this moment
Th
easies
I way lo proportion the plate is to assume its dimensions
and to find its resistance
lo hendinu', neglect ini; the area lost
hy the pin holes (which area is close lo the neutral surface),
anil makini; up for the omission hy providin-- a little extra
resist, mce.
To illustrate the ir.c
Ihod, let us lake a two-inch lateral ro
makimj,' an an
liusses, aiu
ole of forty-live de.t;rees with the planes of the
1 lei the distance hel ween centres of pin l)earinj;s Ik-
si
\ inches. The s
tress on such a rod is 3.14 X 7.5
tons, auu t
he l)eiHlini;-momenl on
thi
pin IS
X
• SS X ,>
.ss.s
mc
h tons, correspomlini; {vide Tahle XII.) lo a ilia
me
ter o
if th
ree inches
and a fourth.
Th
e distance from the axis
of the pin to the centr
e I
>f tin
iaw hearmi;- wil
he .ihout
_|. j"_|- i"-|- ;^" - 5". The lon^t;iludinal component oi tin
stress on the lateral rod is ^3
the momen
55 X 0.7 = 16.5 Ion
s. inakiiu
t on the jaw ahoul 3 X 16.5 = S2.5 inch Ions. The
thickness of the jaw plate should he %\ and let us assume llio
Aviillh to he 7
known formula,
The resislinii-moment is given
hy th
e well-
J/ =
/?/
(>A'/)/x.i/n' /h'ox j"c,nu'A v-nRiDcr.s.
107
WlUTC
A" = 1 1.25 t„ns, / = /,/;,/3 = ji, X V- X (;)•■', and d,=l
Siil)slitutiii<^, f^ivc's
M:
11.25 X tV^X V X 49 X 7 X 2
1 15 incli tons, nearly.
jaw thn'UL;li
^uilinal com
st tlKTcton.'
nu-nt. llu'
(liinciisions,
U' area lost
ral siiriacx'),
little c.Nlra
Tlic (lilfi-iviirc bctvvcfii 115 and 82.5, or 32.5 inch tons, is ,t;rcatcr
than the rcsistin<;-monicnt of the material lo.st by the pin hole:
so the dimensions assumed are ample.
U-nuts are objectionable in every case; for, if th
stronir en
ey are made
oii-h to resist without bucklin<; the ultimate i)nll of
nice.
the rods, they will have ;i very clumsy appear
lion of a cast-iron washer will relieve the bendinj; of the U, but
not tiie appearance: besides, it is better not to introd
iron into a wrou,!;ht-iron structure.
he inser-
uce cast-
It
IS now m o
filer to take up the omitted portions of Chap-
ter IX.
iMi-st, to find the number and distribution of the rivets in the
ilan-es of the beam there designed, let us divide the fifteen feet
between centres of supports, as shown in the accompanying
diagram, and calculate the stresses at the points of division.
a'6"
>< a'o" ) < a'o" >< i'o"> < i'o"> < I'a"
2'f>''
The ro-action at each end is about 8.5 tons, and the uniformly
distributed load about 0.0044 ton per lineal inch. The moment
at the first point of division from the support is
8.5 X 30 - 0.0944 X 30 X 15 = 212.5 inch tons.
At the ne.\t point of division the moment is
^^•5 X 54 - 0.0944 X 54 X 27= 3 21. 3 inch tons,
and at the ne.xt j)oint it is
cS.5 X 7S - 0.0944 X 7.S X 39 -- 3 75.,S inch tons.
loS
0A'/)/A:1 A' 1 • /A'lKV II lull 1 1 \1 i -BAJlKiKS.
From the last equation of Appendix II. we have for the value
of the flange stress at any section,
M
S =
In this case
Dividing each of the moments by 36.7 gives, for the horizontal
stresses at the three points of division, respectively 5.8 tons.
8.74 tons, and 10.24 tons. Therefore, between the centre of
the support and first point of division, there must be enough
rivets to take up a horizontal stress of 5.8 tons; between the
first and second points, enough for a horizontal stress of
8.74 — 5.8 = 2.94 tons; and between the second and third
points, enough for a horizontal stress of 10.24 — 8.74= 1.5 tons.
The vertical pressure upon the rivets of the upper flange is
about 12 X 0.0944 = 1. 133 tons per lineal foot, making the total
vertical stresses for the three divisions respectively 2.83 tons,
2.27 tons, and 2.27 tons. Combining these by the ixirallelogram
of forces with the horizontal stresses last found, gives the total
stresses for each division 6.45 tons, 3.71 tons, and 2.72 tons
respectively.
From Table XXXVI. we find the resisting bending-moment
of a five-eighth inch rivet to be 0.18 inch ton, and the working
bearing-pressure on a quarter-inch plate, 0.938 ton.
Let us first consider the stress of 6.45 tons. It is equally
divided between the two angles, making the stress on each 3.22
tons. The lever arm of this last stress is .](] + /l;) = aV' ^"'^
the moment ^.i X 3.22 =0.906 inch-ton, dividing which by 0.18
gives five as the number of rivets required to resist bencUng.
Dividing 6.45 by 0.938 gives seven as the number required for
bearing. If there be but seven rivets in two feet and a half,
the spacing will be five inches, which would be practically too
great. It is better to space the rivets two and a half inches near
the ends of the beam ; and, if it be thought advisable, the distance
may be increased to foiu" or even five inches near tlie middle.
ORDINARY IRON HIGHWAY- BRIDGES.
109
iMoni the above, wo may conclude that calculating riv?!
.spacin.^; for flanges of floor beams is, as a rule, too much refme-
iiunt lor highway-bridge designing.
If the depth of the beam W reduced near the ends, or if, by
reason of lack of headway biMU-ath the 1
be used, it might be well to -fu tl
iridge, shallow beariis
Next let us make th
irough the above investi-at
ion.
le design for a trussed floor beam, takin;
a twenty-foot panel and a tweiUy-funr foot roadway of a brid'^i
;jives the weight of ai
belonging to Class A. Table XIX
ordi
IK'I-
nary built beam for these dimen
lineal foot : so let
sions as ninety-four pounds
us assume the weight of the trussed 1
)eam
to be eighty pounds per foot, also the length of beam between
centres of supports to be twenty-five feet. The live load will
he
24 X 20 X 100
2000
Table XV. gives 3339 as the number of feet of pine lumber per
panel, the weight of which is
= 24 tons.
3339 X 5
2 X 2000
and the weight of the beam itself is
26 X 80
= 4.174 tons;
2000
= 1.04 tons;
makmg the total load equal to 29.214. or 1.1686 tons per lineal
f<)t)t. Let us use two jwsts. The central panel should be ten
feet long, and each of the others seven and a half feet. Let us
assume the beam to be a 10" 30# I, and the depth of the truss
five and a half feet centre to centre. Then in the formula
3 4>
we will have iv = 1.1686, I, = 10, </ = -f„ nearly, C= 5, P =
.]X 1. 1686 X 17.5 = 10.225, /, = 7.5, r"^3, D=s.S, and A'
;d)out 8x032 = 2.56. Substituting these values gives A + A"
= 3 21 as the area of one flange. The total area of the section
would then be 2 X 321 + 2.56 = 8.98 square inches, which cor-
responds altpost exactly with the area of a thirty pound I-beam.
h
11 I • ' (
I
pit
ifliiri
no
OA'/>/X^IUy /A'(>.\ JlhiJ/UA \-JiRiniJKS.
Tho (k'si^n for llu- post agrees with that shown in Fipj. i6,
riale II., with tlie exception that the end (Uagonals are not
adjustable. The stress on a post is /' = 10.225 tons ; that on
the bottom cliord is
that on the end diaj^onals is
/>^i:cO— 10.225 X 1-69= 1 7.28 tons;
that on the counters is
j'\,/'sLr «' = 0.3 X 10.225 '^ 2.16 = 6.625 tons.
The Mitensity for the tension menilK-rs should be four tons,
making- the sections required for tlie chord bars and main
dtogonals respectively 3.48 and 4.32 square inches. Referrin<;
to Carnegie's " rocket-Companion," p. 94, we find that two
§" X 2\" bars will do for the former, and two \" X 2^" bars for
the latter. From Table IX. we find that two one and a quarter
inch rods will be re(|uired for the counters.
To the stress on a post must be added the vertical component
of the initial tension on the counters, which is about
2 X 1.5 X 0.46 = 1.38 tons;
making the total stress 1 1.605. Before ajiplying Table XL., we
must multiply this stress by about 1.5, the ratio of the factors
of safety for wind bracing and floor-beam struts; making the
total stress 17.407 tons. Using the column for one fi.\ed and
one hinged eiul, we find that a 6" 15* I-beam will be reciuired.
To find the thickness of the pin plate at the end of the beam,
let us assume it at five-eighths of an inch ; then the lever arm of
the diagonal stress will be .1(5 + 5) = •] inch, and the moment.
17 28
3 X -^" — = 6.48 inch tons.
2
Consulting Table XII., we find that the necessary diameter of
pin is two inches and an eighth. Referring to Table XXVI.,
and looking down the column for a two and an eighth inch pin,
we find that the necessary bearing will be, for 8.64 tons, eleven-
sixteenths of an inch. It will be more economical to increase
the diameter of the pin to two inches and three-eighths than
the thickness of the plate to eleven-sixteenths.
OKD/XANV /ROX HIGHWAY-BRIDGES.
\\\
rhths than
Next let us find the number of rivets necessary to attach the
plate to the I beam. The horizontal and vertical components
of the end diagonal stress are respectively
17 28 X 0.8 = 13.82 tons
and
17 28 X 0.6= 10.37 tons.
The first of these stresses pioduces bending; and the second,
direct tension on the rivets, The moment of the first stress is
about
13..S2 X J(!i + i') = 9.5 inch tons,
uhirh. divided l)y 0.493, tlie resistiuf^-moment for a seven-ei;;i,ths
iiuii rivet, ioiind in Table XXXVI., gives twenty as the nmnber
oi rivets to resist bending. To resist tension the number re-
quired will be
5 X 0.6 ~ *^'
making twenty-four rivets in all for the connection. Seven-
eighths inch rivets are rather large for the flanges of a ten-inch
beam, as there is not room for full heads : nevertheless, it is
better to use them, on account of the increased bending resist-
ance.. Using twelve rivets on a side, and spacing them two
inches and a half a])art, will make the length of the plate about
thirty-two inches. It is evident that there is no need of figuring
for bearing in this connection.
.\e.\t let us proportion the connecting-plate over a post,
assuming the thickness to be three-eighths of an inch, and using
live-eighths inch rivets. The moment on the rivets will be
1 1 .605 X ,\ ( 3 + ;. ) = 5 .oS iii,:h tons,
which, divided by o. i.S (the resisting-moment of a five-eighths
inch rivet), gives twenty-eight as the number of rivets required,
or fourteen for each lug. Using staggered rivets spaced two
inchrs apart will make the depth of each lug about fifteen inches.
The number of rivets necessary for attaching the plate to the
beam is partly dependent on the counter stress, and partly upon
the length of plate which we consider requisite for fi.xing the
cn.l of the post. About eighteen inches ought to suffice for
»M{
112
ORDIXARY IROX HICHWAV-BRIDGES.
this purpose. The horizontal component of the counter stress,
including initial tension, is 9.625 X 0.89 = 8.566 tons, and its
moment on the rivets is
S 566 X \{% + f ) = 4.82 inch tons,
which, divided by 0.31 1 (the resisting-momcnt for a three-
fourths inch rivet), gives sixteen as the number of rivets
rec|uire(l. Making them staggered, and spacing them two and
a c|uarter inches apart, would make the length of plate just
twenty inches.
Let us assume the sections of the re-enforcing plates at the
feet of the posts to be j," X 5"; then the lever arm for the cho'-d
stress will be ^(^ -|- -J) = ^ inch, and that for the vertical com-
l)onent of the end diagonal stress o(| + .} + V) = {o ; making
the horizontal and vertical component moments on the pin
respectively,
.23 inch tons
13.044
and
10.225
1(1
4.79 inch tons.
The resultant moment is
V'(5.23)'+ (4.79)-= 7.09 inch tons.
It is evident, that, to obtain the lever arms used, the chord bars
must be packed on the outside and the end diagonals, between
the chord bars and the post. The diameter of pin correspond-
ing to 7.09 inch tons is 2^'; but a 2]" pin is tlie smallest that
can be used with a 2^" bar. The post l)earing is am|)le, anil
needs no testing.
If we divide the bearing-stress equally between the post and
the re-enforcing plates, there will come upon each of the latter a
stress of 2.9 ; making a moment upon the rivets equal to \ X 2.9
= 1.45 inch tons, which, divided by o. 18, gives eight as the num-
ber of five-eighths inch rivets recjuired for each plate. Adding
two for safety, s])acing the rivets two inches apart, and allowing
room for the eye-bar heads, will make the length of each re-
enforcing plate about si.xtcen inches.
ORDLVARY IROX nrGIIlVAV-nRIDGES. ,,3
The moment on a counter pin is 4.S1 x i{ij -f U) ^ 3 ni inch
t..ns corresponding to a if" pin. % examining Table XX\T
■t u-.ll be seen that a 2I" pin will be required to give sufficient
bcnnng
.r
Ke,errn,g now to the list of details for a trussed beam, oivcn
on p. 30, so as to omit nothmg, we can make out the bill of iron
as follows : —
Uj)l'L'r chord beam
l.oucr clioid bars . .
I'^nd diagonals . . .
Counters
Posts
Connecting.plates . .
Ke-enforcing plates .
i'in jilates
Stit'teners
Tins
I'ins
Fins
Fillers ....".'
Rivet heads , . .
Total weight of beam
4
2
4
2
4
10"
r'
I"
6"
3'/
I"
-5
2-t"
@
3o#I
-4
2i"
O
'5*1
14"
S"
15"
7 3#L
O
O
Q
2#
26'
780*
■3'
150"
■3'
379"
IS'
245 "
5-3'
159"
3'
105 "
16"
44'-
32"
167 '■
8"
30'
10"
25-
10"
20'-
13"
29'-
each
8"
about
50-
2, 191*
1 hc'^ we>gln of a plain beam for the same place would be
-0 X 94 - 3,444, showing a saving of 253 pounds by using a
mssed beam At f^ve cents a pound, this would amount to
sM-.Os; which IS considerably more than the cost of th- field
nvct.ng, and extra trouble in putting such a beam in place A
-nnlar investigation for a trussed beam with one post will show
"''^t he weight of such a beam will exceed that of a corre-
sponding pkun one: so there would be no economy in such a
ilcsign for this case.
1(1 >:
III!
i! t
114
OKD/XAN 1 ■ IKOX men 1 1 '. / ) -/iA'/DUhS.
CHAPTER XIV.
BILLS OF MATERIALS, AND ESTIMATE OF COST.
In making out bills of materials, the list of members given in
Chapter III. will prove of great assistance. By its use, one can
avoid an underci-,timatc due to an omission of any of the parts
of the structure. A good way to make out a bill of material
is to prepare si.\ vertical columns, in the first of which write
the name of the member ; in the second, the number of pieces ;
in the third and fourth, the dimensions determining their sec-
tion ; in the fifth, their length ; and in the sixth, the woiglit
of all the pieces, or, if of wood, the number of feet, board meas-
ure, that they contain.
The following examples will serve to explain the methotl : —
DILL OF WROL'OIIT-IKOX.
Chord channels . . .
12
7"
10,1* [
2,772#
Batter-brace channels .
8
8"
i2i#[
33''/'
3.375 "
Plate
I
X"
4
12"
262'
2,620 "
Post channels ....
8
5"
c>k# c
22^
1.144-
Lateral struts ....
4
4"
r* c
<5'
360 ••
Lateral struts ....
4
5"
6.^# [
•5'
300 ••
Main {liai;onals. . . .
8
r
'T
34'
1.020"
Counters
8
3"
4
3"
35'
5-5"
Etc
""
•
"
2.77-#
3-375 '•
2,620 "
1.144 ••
360 ••
390"
1.020 •■
5-5"
ORDINARY iRox j//i;//ir.n--nA'/jH,j.:s.
BILL OK LUMBKK.
IIS
Joists
Flooring . . ,
liand-rail caps .
Handrail posts.
IJiil) ])lanks . .
1\11\- planks . .
Lateral struts .
55
110
20
30
4"
14"
3"
12"
2"
6"
4"
6"
2"
12"
6"
6"
8"
8"
'4'
22'
4'
no'
112'
•4'
Total number of feet, hoard measure
5/>47
4,620
440
240
440
672
224
r 2,283
It IS to be noticed that it is often convenient, as in the case
of the "Plate" in the "Bill of VVroi.ght-Iron," or that of the
"IIuI, planks" in the "Bill of Lumber." to combine several
lcnt;ths in one.
To the length of each chord bar. main diagonal, and hip ver-
tical IS to be added three feet to allow for the weight of the
licads ; and to that of each adjustable rod about five feet for
the heads, upset ends, and .sleeve nuts or turn buckles Should
greater accuracy be required for the weight of an adjustable
rod. It will be necessary to ascertain what length will be needed
at each end for the heads, and how much for the upset ends
;'nd adjusting-nuts by the followin<'
T.AHLI- OF EQUIVALENT LEXGTMS OF RODS FOR UPSET ENDS,
NUT.S, .SLEEVE NUTS, AND TURN BUCKLES.
h''
-1"
I 1 '
->r
■iV
—ill
^"
-2h"
i"
-4"
I 6 "
-2^
I upset end and i nut
I upset end and i nut
I ujxset i:\u\ and i nut
1 U])set end and i nut
2 u|)set ends and r sleeve nut
2 upset ends and 1 turn buckle
•i
feet of rod
'i
feet of rod
'f
feet of rod
'iV
feet of rod
1
•3
feet of rod
3 feet of rod
I hcse equivalent lengths do not include the lengths of the
I'Psct ends themselves : they represent simply the e.vtra lengths
t" be added to the bar to equalize the weight of the nuts,
slocve nuts or turn buckles, and the e.xtra iron for enlarging
the ends, which arc six or ' "
■ -I
' 'I
('i';lit mcl
loui
ill
ii6
ORD/XARV IROX lIIGIIWAV-BRnyCES.
It is not necessary in a preliminary estimate to find the exact
quantities of materials, so approximations to actual dimensions
can be made. This will be fully illustrated in Chapter XVI.
Before considering a bill of material as finished, it is well
to look it over to sec that no mistake has been made in the
number of the pieces. It is not an uncommon error to put
down only half the correct number.
As soon as the bills of iron and lumber are made out and
checked, the dead load per foot should be calculated, to see
if it agree with the one assumed within the limit specified on
p. 6.
Estimates of cost should be liberal ; for, as a rule, the actual
profits on bridges fall short of the amounts estimated. They
can be made very readily by using a blank similar to the fol-
lowing : —
Estimate on Brittgc across
Lotiith spoilt ft. Ilcli^ht, ft. Clear Roadwayy ft.
.Static Load per lineal ft., lbs. Afoiuiii^ Load per lineal
ft., Ids. A'o. Panels. Loigth Panels. ft.
: I Cts.
@
%
©
@
loads (o
II 'roiis^ht-iron. lbs.
Casl-iron, lbs.
Lumber, ft.
Piles, ft.
Hauling,
Freight
Framing
Falsework
Erection
Spikes
J'aintiri;
Blacksinitliing
Coal
Freight on tools
Travelling expenses ....
Men^s time travelling . . .
Bidding expenses
Teaming during construction
Incidentals
Total cost of bridge . . .
Cost per lineal foot . . .
ORDIXARV IROX HfGHVVAY-nRinarCS.
117
On fair country road.s, a load for a team of horses may be
taken to be a ton and a half of iron, a thousand feet of pine
lumber, or si.\ hundred feet of oak lumber.
The designing of falsework will be treated in Chapter XX.
Its cost will include that of the piles in place, if any be required!
and that of the lumber, to which should be added about three
dollars ])er thou.sand for framing and raising, and a dollar or
more per thousand for taking down. Falsework timber can
generally be sold for something when the bridge is completed :
so a reduction may be made in its cost when the estimate is to
be a close one.
The cost of erection can be found approximately for ordinary
conditions from Table XXXVIII., by multiplying the number
of days' labor there given by the average rate of wages for ordi-
nary bridge hands. It must not be forgotten that there is a
great variation in the cost of erection ; for it depends upon the
locality, weather, skill of laborers, efficiency of foreman, etc.
Those who feel inclined to question the correctness of this
table should make some allowance for the difficulty which the
author has experienced in getting any data whatsoever upon
the subject. Few bridge engineers care to part with the
knowledge which has cost them both time and money
\\^ regard to cost of painting, the same difficulty has been
encountered : so, for lack of more accurate data, the followino-
table will have to suffice. It has been prepared from a few
figures of co^,t of painting, obtained at a time when wages were
a dollar and a half a day.
SrAN
12' roadw.iy.
16' ro.idw.iy
20' roadway.
50'
S6.0O
?7 00
8(9.00
100'
22.00
25.00
2S.OO
150'
-
45.00
51.00
200'
-50'
300'
-
So.oo
125.00
90.00
140.00
1 70.00
24' roadway
$11.00
31 00
57.00
lOO.CO
155.00
1 90.00
IV'lore making an estimate on a bridge, one should endeavor
to ohtam as many as possible of the followin<^
i ^i' B V'. t-
lit
Il8
Oh'n/\AA'\' /AOx ///<;// 11. n-/,'A7/)(;/-:s.
DATA I'OK OESIGNMNG IRON IIK.IIWAV liKIOGE SUPERSTRUCTURES,
AND I-.sri MATING THEIR COST.
Class of bridge required.
Length of span or spans.
Width of clear roadway.
Headway required in clear above floor.
Live load, if different from the ordinary.
Wind pressure per square foot, if different from the ordinary.
Any extraordinary load, such as paved flooring, heavy falls of
snow, etc.
The velocity of passing loads.
Distance of bridge site from nearest railway-station or sea-
port.
Quality and condition of the roads between these places.
Nature of bed of river, and velocity of stream.
Height of lower chord above bed of river.
Cross section of stream at crossing, showing borings, if any
have been made
Angle which the direction of bridge makes with axes of piers
or abutments.
Nature of the country at the site.
Any special difficulty that may be anticipated for the raising.
Kind of falsework it would be advisable to use.
Cost of piles at various places in the neighborhood, if any be
required.
Cost of transport of same to site.
Cost of timber per thousand for falsework.
Probable value of falsework timber after bridge is finished.
Cost of withdrawing piles, if necessary.
Number of lineal feet of piles recjuired.
Number of feet of lumber for falsework.
Cost of spikes, bolts, and nails for falsework.
Cost of driving piles.
Cost of transporting pile-driver to and from site.
Common laborer's wages.
Skilled laborer's wages.
Foreman's wages.
Wages for team and teamster.
ONn/X.lKV IKOX HIGHWAV-nRlDGES.
RUCTURES,
119
Cost of siipcrintcrclcncu by cnt^incer or engineers.
Number of days' teaming on work.
Date when bridge must be finished.
I'robable length of time it will take to raise and complete
)ri(lge.
Chances of fair or foul weather during this time.
Chances of having falsework carried away by a sudden rise or
in icc-gorge.
Chances of a scarcity of laborers.
Chances of sickness among laborers.
Expenses attendant on same.
Cost of tents or other housing for laborers, if any.
Cost of iron at mill or foundry.
Cost of transport of same to nearest railway-station or sea-
port.
Cost of lumber per thousand at mill or market.
Cost of transport of same to nearest railway-station or sea-
port.
I'robable expenses for blacksmithing and coal.
Cost of tools, if it be necessary to buy .special ones.
Wear and tear of plant, and loss of tools.
Loss of bolts and timber.
Actual cost of raising similar structures under similar circum-
stances.
Trax-elling expenses of employees to and from site,
lidding expenses, if any.
Office expenses in preparing plans, etc.*
Advisable allowance for contingencies.
» Tlus is „su.,lly not considered, as it is a constant e.xpense, and comes out of t!,e aiini.al
gross i]rolUs ot the company.
120
ORDLVAKV IKO.y H hi U WAY-BRIDGES.
CHAPTER XV.
ECONOMY.
The first point to be considered, when dccidinj:^ upon the
style of" bridge for a certain stream crossing, is the ninnber ol
spans. It is, in reality, a consideration of economy wliich
determines this ; for the best bridge to l)uild, provided that the
water-way be not too much contracted, is the one for whicli
the sum of the cost of superstructure and the cost of founda-
tions is a minimum. If the water-way be too much interrupted,
the design would not be an economical one, even if its first cost
were the least, because of the risk of washout to which the
bridge would always be subject.
In most cases, there is not much choice concerning the num-
ber of spans, local considerations often determining it ; but there
is occasionally a choice between two or even three numbers.
The only way, then, to decide is to make a rough estimate of the
cost of the superstructure and the foundations for each number;
then, if the choice fall about equally between two numbers, it is
better nearly always to adopt the longer spans, because the
actual expense for the foundations usually exceeds the amount
of the preliminary estimate.
Another preliminary point to be settled is whether it would
be most economical to build an iron, a combination, or a wooileii
bridge. Although this work treats of iron bridges only, still
this is a point which ought to be considered.
The following mathematical treatment of the problem was
given by the late Ashbel Welsh, C.lv, past president of the
American Society of Civil Engineers : —
rv.v>A\-./ -J- /Rox iiiGnWAv-nR/ncEs
121
1" MM' llIK (CMPAKA-nvK r.CONOMV OF TWO HRIDOKS OF niF-
I KKF.NT COST AND I.UKAMIMTV, THAT Wir.L A.NSWKK TMKSAME
I'lKPOSK KOUALLV WELL WHILE TllEV LAST
' Lot The the cost and assumed real value of one of them T
the time it will last, a the compound interest on one dollar 'for
that tune, at whatever rate money is worth to the party paying-
for the hndge, and /. the loss on the bridoe at the end of the
lime T, or the amount which it would take to make it as -ood
as new. Let A' be the real value of the other bridge, C its cost,
/ lis duration, n' the compound interest on one dollar for that
lime, and /.' the loss on the bridge at the end of the time V
or the amount required to make it as good as new. And let Tbc
I he real value of the bridge that would last forever if all cir-
cumstances should remain constant.
' Xow. supposing that the money required for building had
been borrowed for an indefinite time, the actual expense at the
end of the time T to the party paying for the bridge which
would last forever would be aV; and the actual expense at the
ciul of the same time for the first bridge, after making it as
^ood as new. would be aC ^ L. These two quantities are
equal : therefore the hitherto unknown value of V\^
C4-
Z
a
S.mlIal■l>^ at the end of the time T\ the expense for the
bridge which xvould last forever would be a'V; and that for
the second bridge, after making it as good as new, if the cost
luul been the real value R, would be a' R + L' . As before, these
iwo values are equal; and therefore,
T'
V=R^^j.
a
I'iquating the two values of V gives
and
R=C +~-^.
a a'
1,1-!
12:
ORDI C \RV IROX IIICIIW \IY -H RIDGES.
Now, if the value thus found for R be greater than the cost C\
the second l)ridi;e is more economical than the fust ; while, if it
be less, the first bridge will be the more economical.'
The next economic consideration is that of depth of truss.
Upon this subject much has been written, and many investiga-
tions have been made; the general conclusion being, that the
depth should be from one-seventh to one tenth of the span :
some ICnglish writers say from one tenth to one-fourteenth of
the span ; while only one, as far as the author knows, — Benja-
min r.aker, C.l':., in his treatise on "Beams, Columns, and
Arches," — makes it from one fifth to one-seventh of the si)an.
Such investigations being purely mathematical, and involving
the use of the differential calculus, are of little practical value,
as they cannot take into account the numerous variables that
ought to be considered. Not only do the stresses in a truss
vary with the depth, but also the intensities of working-stress
in the compression members. These, again, vary with the
number of panels ; and this variation is according to a law or
laws altogether too complicated to be handled by the calculus.
Again : the intensity of working-stress varies, or should vary,
according to the position and importance of the member.
In view of the complexity of the question, and wishing to
determine the most economic depths for Pratt and Whipple
trusses, the author, about a year ago, undertook to solve the
problem in a practical manner by assuming the most common
clear roadway (sixteen feet), and figuring out a number of dia
grams of stresses, and bills of materials. At first he considered
that It would be necessary to calculate the total actual cost
for every case, but upon further investigation found that il
would be sufificient to figure out the sections and weights per
lineal foot of the different members of one truss, multiply these
by their respective lengths, and sum up the products, neglect-
ing all consideration of details, because the differences in the
weights of the latter balance each other. Thus, if the depth of
a truss be increased by one foot, there would be a little increase
in the weights of the lattice bars and rivets and a decrease in
, that of the pins anil eye-bar heads. These may be taken as
balancing each other, without making any appreciable error.
rMvv.\- //>•)■ //cnx nir.mr.w-nRiin-.F.s. ,23
TiK- im.sl economic Icn-tli of pand was at tlic same tinic
.nvcst,K.itc-cl, and was determined, witl,ni,t preparing; complete
hills of materials, by co.isiderin^^ only those portions of the
structure wiiich are affected by the variation in the number of
panels.
Economy in pony trusses is an element which ou^ht seldom
t(. influence the design, for a good bridge of this kind will .re„.
erally reqiure more iron than the ordinary calculations demand
instead of trying to avoid a little expense, regard should be
paid to obtaui.ng a good distribution of plenty of material in
Older to partly compensate for the lack of rigidity which' is
characteristic of the pony truss. In very wide pony-truss
hrulgcs, especially when the length of span approaches its
superior economic limit, it might be well to make a few calcula-
tions concerning the economic depth; but the number of panels
shou d be regulated by the slope of the batter braces, which
should never be less than two and a quarter horizontal to one
\crtical.
The superior economic limit of the pony truss is not a fi.xcd
quantity, but decrea.ses as the width of the bridge and the load
mcrease, and as the intensities of working stresses diminish
l;..r example, comparing a pony tru.ss and a thn.ugh brid-e of
sixty.five feet span in four panels, sixteen feet clear roadway,
designed according to Class C, there is found a difference of
three hundred pounds of iron in favor of the pony truss ; while
w'th the same span, for a twenty-foot clear roadway, and bridge
designed according to Class A, there is a difference of eleven
nindred and fifty pounds of iron in favor of the through brid-e
I'..r a clear roadway of twelve feet, the superior economic limit
of the pony truss would reach as high as seventy-five feet ; and.
m- very wide bridges, the inferior economic limit of the throuoh
bn'lge would reach as low as fifty-five feet : but, on account^of
> ■guilty, the superior limit of the former may be placed at sixty-
^ve teet ; and, on account of appearance, the inferior limit of the
latter at the same length.
After making out diagrams of stresses, and bills of materials
'"'•"ver one hundred spans, the author came to the followin-^
conclusions : — ="
i I
124
(>A'/>/.\.!/:)' j/:(i.\ I Hi, 1 1 WW v-i',RiiH,i:s,
n\
I till ^'
That if ttu' economic depth he calcuhitod for any span, where
the panel length is twenty feet, or the nearest leni^th helovv
twenty foet, and if the economic depth for the same span, l)ut
with one panel less, be calculated, the latter will exceed the
former by one or two feet.
That, in places where lumber is expensive, it will not be well
to make panels over twenty feet lonj^, or, in places where it is
cheap, to make them over twenty-four feet lonj;, because tim-
bers exceeding tiie latter lenj;th are not easily procured. Then,
too. iji designin<; iron brid<,'es, which are supposed to last indeli-
nitelv, it must be remembered, that, as time j^^oes on, loni;-
timbers will become more and more expensive, and less easily
procurable, even in timber districts ; so that panels exceeding-
twenty feet in length should be employed very cautiously.
For appearance, through spans of one hundred feet and under
should have five panels.
The principal objections to the use of the double intersection
for short spans are, that, as the rods are long and slender, they
will vibrate more than the shorter and larger ones of the single
intersection. Any flaw in a small rod will have a proportion-
ately greater injurious effect than the same sized flaw in a larger
rod. Long and slender rods are difficult to transport, and arc
liable to become twisted and bent ; though this objection can
be partially removed by halving them, and, as the posts are
light, they will spring more under the shock of rapidly moving
loads.
As the width of roadway and the live load increase, and as
the intensities of working-stresses diminish, the inferior limit
of the double intersection may be lowered. The table on p. 8
{rives the limits which the author would recommend.
The common idea among highway-bridge builders, that a
double-intersection bridge should, for economy's sake, have more
panels than a single-intersection bridge of the same span and
loading, is incorrect.
The economic depth for a double-intersection truss is about
three feet greater than that for a single-intersection truss of
the same span, and number of panels.
Tables IV. and V. give the principal results of the before-
oA'/'/.v.iAT /AiKv ///(/// ir. I r-/!Av/)(:/-:s\
I2«
nu'.itioncd iiuvsti-ati<.ns. The first is the ..nc- to he (M-(lin:.nly
iise.l : the .see<-ii<I may he em|)I()ye(l for districts where the tiiii-
her is hirj^e and plentiful.
There seems to he an iinf..unded prejudice in the minds of
cnimiy commissioners and hrid-e sui)ervisors a-ainst Ion- pan-
els. Practically they make a hetter brid-c than do short panels ;
for tlie members are fewer and lar-er, and therefore less affected'
by Haws, besides less subject to vibration, and less hable to
maccuracy of construction. The floor beams and joists bein-
lar-er. there is less probability of often receivin- their ma.xinum"
workin-.loads. The only real objection to Ion- panels is the
extra cost of the joist timbers when they arc to be replaced.
In addition to what precedes, the following general economic
considerations should always receive attention.
Field riveting should be avoided as much as possible, and
designs should be made so that all the parts will come to-ether
readily during erection. ''
Kivets should be spaced with regularity, .so as to facilitate
tile i)unching of the holes by riveting machines.
it is generally better, in through 'bridges, to pack all but the
end chord bars outside of the posts, and reduce the width of
top chord plate to a minimum.
It is not always better to employ the apparently most economi-
cal depth of channels. For instanc . if there be a choice of
using ten or twelve inch channels for the top chords and batter
braces, and if the S(rf/(»/s alone would indicate a saving of sav
three hundred pounds of iron by the use of the twelve-inch
channels, the others would be more economical ; for the twelve-
inch channels require larger stay plates, lattice bars, and
re-enf„rcing plates, besides a wider top chord plate, which would
increase the weights of the cover plates, chord pins, post lat-
ticing, post stay plates, shoe plates, etc., and even add a little
to the lengths of the floor beams.
the beforc-
1^
'
ilH^i
126
ORDLXARY IROX HIGHWAY-BRIDGES.
w
,
1r*
CHAPTER XVI.
COMPLETE DESIGN FOR A BRIDGE.
Let the bridge to be designed have a span of one hundred
and sixty feet, and a clear roadway of fourteen feet with no
sidewalks, and let it belong to Class A. Referring to the table
on p. 8, we see that the trusses should be of single intersec-
tion. On p. 5 we find that the live load should be eighty
pounds per square foot of floor, which corresponds to eleven
hundred and twenty pounds per lineal foot of bridge.
Table I. gives the dead load as seven hundred and forty-two
pounds per lineal foot, say seven hundred and forty pounds.
Table IV. gives eight for the number of panels, and twenty-
four feet for the economic depth.
The diagonal upon 20 and 24 is 31.24, which divided by 24
gives 1.3 for the secant ; and 20 divided by 24 gives 0.833 for
the tangent.
The panel live load, ic, is equal to
1 1 20 X 20 . ^
1 y^ = C.6 tons.
2000
The panel dead load, \\\, is equal to
740 X 20
2000
= 3.7 tons.
Let us assume that about a third of this is concentrated at
the upper panel point, making
W = 1.2 tons.
The sum of the live and dead panel loads, or W", is
5.6 4- 3.7 = 9.3 tons.
2ntratcd at
OlWrNARY IRON HIGHIVAV-BRIDGES. 127
One-eighth of zc is 0.7 ton, which multiplied by i x dves
0.91 ton. ^ '^ ^
The panel dead load multiplied by the secant is
3.7 X 1.3 = 4.81 tons.
//'" multiplied by the tangent is
9-2> X 0.833 = 7-747 tons.
The following table of data can now be written : —
'to
« = 8
/= 20
«'= 24
diag. = 31.24
sec = 1.3
tan 6 = 0.833
71' = 5.6
^^.= 3-7
ilV,= 1.85
ir = 1.2
iw = 0.7
iw sec (9 = 0.91
^j sec 6 = 4.81
^IV^ sec (9 = 2.405
IV" tan ^ = 7.747
^ IF" tan 6= 3.873
Next let us draw the skeleton diagram shown on Plate V
and number the panel points, commencing with zero at the right!
liaiul end. ^
First let us find the stresses in the diagonals, using Table XLI
1 he stress in the counter at the point 2 is
-Pc sec e - |/F, sec ^ = 3 X 0.91 - 3 X 2.405,
a negative quantity, which shows that there is no stress on this
member. Let us mark it zero on the diagram.
The stress in the couiter at the point 3 is
f«. sec 6 - A ^// sec 6 = 6 x 0.91 - 2.405 = 3.055.
Fct us mark this and all succeeding stresses on the diagram
1 he stress m the main diagonal at the point 4 is
V^^ sec e + ^ IV, sec ^ = ,0 X 0.91 + 2.405 = 1 1.505.
That in the ne.\t main diagonal is
V^ sec 6 + UV, sec fl = .5 x 0.91 + 3 X 2.405 = 20.865.
128
ORD/X.IR]- /A'OX IinUlU'A Y-BRIDuES.
That in the ciul main cliaironal is
2i7i' sec + •!//', sec U
!i X 0.91 4- 5 X 2.405 = 31.135.
That in the hatter hrace is
28
7i' sec ti -\- \ /Fj sec ^ = 28 x 0.91 + 7 X 2.405 — 42.315.
That in the middle post is
I,,, _ iJFi + W = 6 X 0.7 - 1.85 + 1.2 = 3.55-
That in the next post is
JLQ
w + \ \]\ + /r = 10 X 0.7 + 1.85 +
1.2 = 10. oc
That in the next is
^§w + •;! \V, 4- W = 15 X 0.7 + 3 X 1.85 + 1.2 = 17.25.
The stress in the top ehord at the panel next to the centre is
1
IW" y^^\- {Y + 2 + 3) W"-^ = SIF" tan 6 = 61.976.
a II
That in the next panel is
(8 - i) IF" tan 6 = ji IV" tan 6 = 58.103.
That in the next is
(72 - Is) ^^"' tan e = 6/F" tan 6 = 46.482.
That in the lower chord at the panel next to the centre is the
same numerically as that in the top ehord at the second panel
from the centre ; viz., —
7UF" tan ^= 58.103.
Similarly, that in the next panel of the lower chord is
6 TF" tan 6-- 46.482.
That in the remaining: panels is
(6 - 2?,) ;F" tan ^ 3.I IV" tan 6 = 27.114.
0/^J)/X.lRV //Uh\ HIGHll-AV-BRinC.ES.
129
A check by moments about the hip gives the stress in the
lower chord at the end panel 3.] //'" tan ^. which shows that
the chord stresses are all right.
Next let us determine if any stiffening be required in the
end panels.
An examination of Table XXV. sh<.ws that the diameter of
the end lower lateral rod is one and eleven-sixteenths inches
Consulting Table IX., we find that the greatest working-stress
that can ever come upon such a rod, including the initial ten-
,sion, is
I4.399 + 2.375 = 16.774 teas.
The cosine of the angle which the rod makes with the planes
of the trusses is about 0.8 : therefore the component of its stress
\\\ the direction of the chord is
16.774 X o.S = 13.419.
Referring to Appendix I., we see that it will be necessary to
assume values for A,h, and r, in order to find the reduced dead
load n ., trom previous experience these values may be taken
as follows : A, = 10, // = 9, and . = 1, making
"^■2 — 370 — = 190 pounds.
The reduced panel dead load will therefore be
190 X 20
2000
= 1.9 tons,
and the stress on the end panel of the windward lower chord
when the structure is subjected to a wind pressure of thirty
I'ounds per square foot of surface, will be
3hlV, tan O = lxi.ox 0.833 = 5.54 tons,
showing that stiffening is decidedly needed. This result could
lavc been predicted with certainty from what was stated in
<■ h;i[)ter IV. concerning Table I.
Xcxt let us find the sections required for the tension mem-
iHTS.
1 30 OKDI.XA A' J ■ /A'( '-\' 11 hill W A J - BRIPGES.
Dividing the stress in the counter at the point 3 by 2 gives
1.528; then, looking down the cohinin marked "Intensity of
Working-stress = 4 tons," we find the nearest number to be
the one corresponding to a diameter of seven-eighths of an inch :
so wc will use two seven-eighth inch rods for this place. In
reality there is no counter needed in the third panel ; but it will
be as well to use a single three-quarter inch rod there to aid in
adjusting the trusses, and to take up the shock of passing loads.
The intensities of working-stress for the main diagonal are
4i^, 4|, and 5 tons. Dividing these into the respective stresses,
we find the sections required as marked on the diagram.
As the lower chords at the first and second panels are to be
stiffened, the intensity of working-stress for the inner bars at
these places will be 4 tons : the intensity for the rest of the
chords will be 5 tons. Dividing these intensities into the
stresses will give the sections required, which are marked on
the diagram. The section for the first and second panels was
obtained by supposing that there are four bars of equal size
used there ; so that the average intensity is 4.] tons.
These two trussed bars of the end panel will not be strong
enough to resist the difference between the C()ni|)ressive stress
of 13.42 tons and the tensile stress of 5 54 tons or 7.88 tons: so
we will have to use an I-beam between them, the trussing-bars
being attached to tiie web. This is a more economical arrange-
ment than two channels laced or latticed. Let us try a 4" I.
Consulting Table XL., we see that for two round ends the
strength of a 4" 10* I is 5 tons, because it is held by the truss-
ing from lateral deflection. Sul)tracting this from 7.88 leaves
2.88 tons to be resisted by the two bars, or 0.88 ton per square
inch, which {vide Table XI.) is by no means excessive.
The stress in the top chord is probably so great that the
minimum width of top plate will determme the packing u,
the bottom chord ; so that the next step will be the i)roiK)rti(iii
ing of the top chord.
Let us take first the stress, 58.103, and try nine-inch chan-
nels, which will give 26\ as the ratio of length to least diameter
Referring to Table X. f(u- both ends fixed, we find 3 226 for 26,]
diameters, so may use 3.222, which, divided into 58.103, gives
ORDINARY IROX HIGJlirA V-nRlDGES. ,3,
.8,03 square inches. From p. ,5 we find that the minimum
.si.e of top plate for nine-inch channels is A"x iii" 00^
sponchn, to an area of 3.59 square inches, ''suhtracti^rt s
from IS 03, and dividing the remainder by 2, gives 7 -.. sauare
.nche.s for the area of one channel. whLh' corrc^s 01;,' to
wc.g t per foot of 24.07 pounds.* Referring to CanJ^'s
"locket-Compan.on." p. 65. we find that ninlinch chapel
vary in weight from eighteen to thirty pounds per foot ; so t e
n.ncnch channels required will be procurable This cakula
-;-; .s not final, for it is not improbable that ten-inc^cl atn Is"
will he found more economical. ^'idunus
The best way to settle the point is to ascertain the average
weight per foot of chord for both cases. Dividing then TT^.
and 61 976 by 3.2^^ subtnrMn<r , ,r. ( u ^' ' ^^ "
,■ , • ^\ ^ ^ ." ^"'^^'^^ctuig 3.59 from each quotient, mul-
t.l) y,ng the remainders by 10. and dividing by 6. ^ives 18 o7
and 36.08 as the weights of the channel bars for' h ? cond and
ourth panels ; which weights are both procurable. Thc^av ra"e
of the three sections will therefore be iy.2s square inches co^r
responchng to a weight per foot of 57-43 pounds. '
It we employ ten-inch channels, the ratio of len-th to least
d-anicter will be 24. tor which Table X. g.ves 3 360 as the !n
t.ns,ty of working-stress. Dividing this 7nto eacf ^f ^^^^
.-.se.s gives 18 40. ,7.35. and ,3.80 as the sections required
Ihc muumum s.ze of top plate (see p. .5) is A"x r'l" cor
ro-sponchng to an area of 3 9. square inches. Subtracting tht
from ,3.80. and mulfplynig the remainder by ^ "ves 16.8
I-nuls per foot as the weight of the channels 'n U e^ 1 p nd
'1- top chore, but the lightest ten inch channel proc , "^1
-■ Carnegie, p. 64) weighs seventeen and a half pound per
f'-t: therefore the area of the section will have to be 4^4
■Mliiare mehes. 4-4i
TlK' a^•erage of the three sections will be ,6.69 square inches
dllwt:" "f '^ ' "^'^'^ '' ''■'' ^"""^'^ i-^ "-'' foot ^
'l.ilucnce between 57 43 and 55.63 is 1.8. which, multiplied by
Th:
8.103. iiivcs
il
111
III
^ftjp
ffi^M
IH
1 i
K: 9
m V'
If
n2
OA'/)/x.un- iROx i//(;nir.\y-i!R/in;Es.
IIIIP^'^
240, the total length in feet of the two top ehorils, gives 433
pounds as the apparent saving of iron in the chords hy usin;;
ten-inch channels: to this must he added the saving in the
batter braces, which could be calculated in the same way. It
is, however, unnecessary to make this calculation ; for we can
see, that, all things considered, it is better to adopt the ten-inch
channels.
The sections and weights of the top chord panels are now to
be entered on the diagram.
It is about time to look to the bottom chord packing, and see
if there be sufficient room inside the posts for the diagonals
and beam hangiM-s; but we must f^rst proportion the diagonals as
marked on the diagram by means of the table on pp. 94, 95, of
Carnegie's " Pocket-Companion," and the hangers by referring
to Table XXII , which shows that I" square bars will be required,
square bars being adopted because there will be very little room
to spare inside the posts. Referring to Table XXVIII.. we find
the width of flange for a 10" 24.15* channel to be 2.63 inches.
Doubling this, and subtracting the product from the width of
plate, leaves 7 24 inches for the width between channels. The
thickness of the inner splice plate will be about seven-si.xtcenths
of an inch; doubling which, adding an eighth of an inch for
play, and subtracting the sum from 7.24, will leave 6.24 as the
distance between inner faces of post channels The thickness
of each inner re-enforcing plate at the foot of a post cannot
exceed half an inch, which would leave 5.24 inches for packing
the diagonals and hangers. For the second and fourth panel
points this will be sufficient ; but at the third there would he
room enough to let the counters in, and not enough to permit
of turning up the sleeve nuts. We can either substitute a single
counter, or widen the chord plate. The former will be prefera-
ble, as the counter stresses do not affect the sizes of the bottom
chord pins, and the central pin of the upper chord should have
an excess of strength in any case.
From Table IX. we find that the size of the counter required
will be i^ig" square.
Ne.xt let us proportion the batter brace. The ratio of length
to least diameter is about 37.], for which Table X. gives 2.639
(>A'/)/A:IA'}' /A'O.V IlICIlWAY-liRIDGES.
m
s are now to
unter required
as the intensity of workings stress, which divided into 42.315
oives 16.03 as the section required. Sul)tracting 3,91, and mul-
tiplying the remainder by Y- gives 20.2 pounds per foot as the
weight of each channel of the batter brace.
Next let us proportion the posts. We see immediately, from
the small stress in the centre post, that its section will be the
smallest ever used, viz., that of 5" ;# channels [vide p. 8): so
there is no need of calculating the section required. Let us
assume six-inch channels for the next post : the number of
diameters will then be forty-eight, and the intensity for two
hinged ends 1.335. which, divided into 10.05, g'ves 7.53 square
inches, corresponding to two 12 55-pound channels. These are
not so economical as seven-inch channels : so we will try the
latter. The ratio is 41 J, and the corresponding intensity 1.656,
wiiich divided into 10.05 gives 607 .square inches, correspond-
ing to channels weighing 10.12 pounds per foot. The smallest
procurable seven-inch channels weigh 10.5 pounds per foot,
which size we will therefore adopt.
I. "t us assume nine-inch channels for the next post, making
tlie ratio 32, and the intensity 2.193, which divided into 17.25
gives 7.86 square inches, corresponding to channels each weigh-
ing 13. 1 pounds per foot. As the lightest nine-inch channels
weigh 14,5 pounds per foot, it will be necessary to employ
these, unless eight-inch channels be more economical Let us
try. The ratio is now iC\ and the intensity r.937; making the
area 8.91, and the weight of one channel 14.S5 pounds per foot,
On account of the smaller sizes of lattice bars and stay plates,
tlie eight-inch channels will prove more economical, in spite of
their larger section : so we will adopt them.
Xext let us proportion the bottom chord, recollecting, that, in
the two end panels, an allowance must be made for one rivet
hole in each inner bar, the rivets being half an inch in diameter.
It is to be noticed that the proportion of width to depth of
chord-bars in the centre panels is about one to five, because
there are four bars in a panel, and that the depth of the end
I'anel bars approaches the limit for stiffened bars,
I'rom Table VL we find the size of the hip verticals to be
KJ
square.
134
OA'D/.y.lNV /A'O.V 1 1 ICllWAV-n RIDGES.
\f
Next let us determine the sizes of the pins.
If we tai<e the average thiekness of one chord bar at the
centre of the span to be \\", we make a little allowance for
accidental thickenini; of the heads.
Substituting in the formula given on p. 85, viz.,
M= -,
2
we find the moment to be 23.56 inch tons, and, referring to
Table XII., determine the size of the pin to be 3^". The least
allowable diameter of pin for a 3J" bar is 3.75 X 0.8 =. 3": so
we will use 3|" pins for the five middle panel points of the
bottom chords. The chord bars of the end panels being neces-
sarily out of proportion, we have to use at the pedestals and
first panel points pins 2|" in diameter, the smallest that can
be used with bars 3|" deep. It may be well to check the
size of these pins. The horizontal component of the moment
I ''T I
on the pin at the first panel point is - X -^^- ^d.'i mch tons,
nearly. The stress in one hip vertical is equal to one-half of the
section required, as given in Table VI., multiplied by the inten-
sity of working-stress for hip verticals, or .] X 2. 14 X 4 = 4.2S
tons. This may be assumed without appreciable error as the
load on a hanger. The sum of the thicknesses of a hip vertical
and a hanger is almost 2 inches, making the lever arm 1 inch,
and the moment, about 4.3 inch tons. The total moment is,
therefore, y'iG.S)- -j- (4!^ = 8 inch tons, which corresponds to a
2|" pin ; so that the diameter previously determined is ample.
Next let us find the size of the hip pin. From the lormula
on p. 86, and Table XXVIII., we find that the appro.ximato
thickness of the bearing is about
M-4
2 X 10
+ 0.3 = 1.02 , say I
The lever arm for the diagonal stress will be 1^'", say i", and,
for the hip-vertical stress, ^" + ^(i" + i Vfi ") — ^^^""t 2", and the
corresponding moments respectively, 15.6 and 2 X 4.28 = 8.6
inch-tons. Laying out these moments in their respective direc-
tions, we find the resultant moment to be about 22.7 inch tons.
ON/)/X.lA'y /KOX llICllUWY-liianGES. 135
which crresponcls to a diameter of 3]". The resultant of the
stress on one end diagonal and one hip vcrtieal, found by dia-
gram, IS about 19 tons. Looking in Table XXVI., vvc find that
a ])earuig of \" is sufficient.
Next let us find Jie size of the next chord pin from the hip
iM-om the formula on p. %G, and Table XXVIII., we find that
the appro imate thickness of the chord bearing is
'17-25
r^io + °-4S = 1-3 1 inches,
and that of the post bearing (p. 87),
8.91
— g- = 1.11 inches.
Allowing a little for play, the lever arms for the vertical and
iiun/ontal components of the stress on a diagonal are respec-
tively 1 and 2|": the components found by diagram are about
•S tons and 6.7 tons respectively, making the moments 8 inch
tons and .5.1 inch tons, the resultant of which is 17. i ^nch tons
corresponding to a diameter of 2^. This is large enough fo,^
a three-inch bar. There is no need of testing for bearin- A
snn.Iar nivestigation for the ne.xt panel point shows that a 2]" pin
will be recpured, which size will also be used for the central pin
By referring to Table XXV., we can write upon the diagram
the sizes of all the lateral and vibrati.^i rods and the sections
"I the upper lateral, portal, and intermediate struts It will b-
sufficient to write the sizes of post vibration rods and interme-
diate struts on one post only, as they are of the same dimen-
sions throughout the bridge.
i'lom ]). 54 we take the formula
)
tn find the stress on the end lower lateral strut between expand-
""■• Medestals. Here
in
n = S
^= 2.375 (seep. 10)
cos 6 = 0,57
_ 7;5 X 3 X 20
2000
2000
59-2
7c' = i-5_^ >50J<^o ^
2000
= 2.25
0-7S
I
m
I ^/)
ORn/X.lA']- Jh'OX IIHUIWAV-nRIDGES.
and r(i7V/r Appendix I) = one-half the lenj^th of span multi-
pHed by the release of pressure per lineal foot on the windward
truss, or
80 X 30 X lo X 9
^ — = 7.2 tons.
15 X 2000 '
Substituting these values gives C„ = 9.2 tons. Assuming four-
inch channels, the ratio of length to least diameter will be 43,
for which, with one fixed and one hinged end, Table XI. gives
an intensity of 2.245 : therefore the section required is 4. 1
square inches, corresponding to two 6.83* channels. It will
be more convenient for riveting to use 5" ;# channels. At the
fixed end of the span a 5" 10* I will answer for a strut between
pedestals.
We are now ready to proceed with the "Bill of Iron," in
making which, close approximations of lengths are allowable.
Let us prepare the blank form recommended in Chapter
XIV., then turn to the list of members given in Chapter HI.,
and fill out the form, proportioning as we go any details whose
sizes have not been previously determined. The filling-out of
the part denominated "Alain Portions" is a very simple matter,
and needs but little explanation. It is to be noticed that the
lengths of the chord bars and main diagonals have been in-
creased by three feel to allow for the weights of the heads, and
those of all adjustable rods by five feet to allow Un- the weight
of the eyes, upset ends, and adjusting-nuts. The intermediate
and portal struts are placed seven feet below the level oj the
upper chord i)ins, so as to allow a clear headway of fifteen
feet.
The size of the floor beam is taken from Table XIX.
The grouping of members having some similar dimensions
is to be observed. It involves considerable economy of labor,
if one has to estimate on many bridges. In filling out the
last vertical column, the tables on pp. 8S-93 and 104-109 of
Carnegie's " Pocket-Companion " will be found very useful.
Let us employ latticing for the top chords, batter braces,
posts, and portal .struts, and single-riveted lacing for the latenil
struts.
'/>'/V.\./AT /A'(;.\- lHuUWAV-liRIlKIE
\17
kofcirin- to Tables XXXII. and XXXIII.
uf stay plates for the top chords and hatter b
iV' X 8", since d = 0.75/?/
that for the middle posts,
i" X 5^", r/ being equal to i.i^D;
we find the size
races to be
ha
t for the next larger ])osts,
J" X 6J", d being equal to D;
that for the larirest
posts,
/fi" X 6J", ^/ being equal to 0.88Z),
that for the portal struts,
}" X 4f , ^/ being equal to i.i8Z>,
tliat for the upper lateral strut;
^" X 8", since ^/ exceeds 2D!
that for the end lower lateral strut.
;nu
i" X 9", ./
:)cm
g equal to about i.5Z>.
It at the hip joint we make the thickness of each inner and
nutcr connectin-plate I", the cross section of the plates
thn.u-h the pin hole by a plane ])erpendicular to the len-^th of
the batter brace will be -reater than either that of the Trntter
)racc or that of the end panel of the top chord : moreover, the
bcarmg will be slightly in excess of that needed to resist
the stresses in an end diagonal and a hip vertical, so we may
conclude that these thicknesses will suffice.
Without committing any grave error, we may assume that the
total stress m the end jx.nel of the chord is equally divided
between the four connecting-plates, making that on each plate
about 1 1.6 tons.
The thickness of the web of a 10" .7.5* channel is 03"
^sce lable XXVIII.) : therefore the lever arm for the stress in
I
'I H 1-
lllll
ll!
.fif.
lit!'
I ;vS
ch'n/x.ih'V /h'lKX II hill WW v-iiRiih;i:s.
a cnnnoctin^'-phitc is il(o.3 -}- o.3;5) =0.338 im-Ii, making the
niotncnt 1 1/) X 0.33S = 3.93 incli tons, whifh divick-d by 0.31 1,
the rosistin^'-ni(iiiu-nt fur a '■'(' rivet, as ^ivcu in 'I'ablc XXXV'I,.
ni\cs thirteen as tlic number of rivets rec|iiire(l to resist l)en(l-
ill^^ I'"roni the same table we fmd by interpolation about \.},()
tons as the bearin^^-resistance for a |" rivet on a 0.3" plate.
The stress tran.sferred to the channel is 2 X 1 1'') = -l-~ tons,
which divitled by 1.36 <;ives seventeen as the number ol
rivets recpiired for bearing;. It will be convenient to u.^e
sixteen rivets, in four rows of four in a row. We can do so
Ic^ntimately, as the calculation calling for seventeen is merely
approximate.
It is evident, without calculation, that sixteen rivets will be
enough for the connecting plates on the batter-brace side ot
the pin hole, for the stress is less and the thickness of web
sliglitly greater.
To make the outer plate fit between the flange rivet heads,
we cannot have it much more than seven inches wide, unless
the said rivet heads be countersunk.
Next let us lay out the hip to scale, as in the accompanying
figure, spacing the rivet holes according to the rules given in
Chapter II., and allowing three inches of length extra for thr
part which connects with the batter brace, so as to i)r()vide for
the i)ortal-strut connection. This api)roximation is accurate
enough for a bill of iron. The circles arc those for the pin ami
the limiting distance for non-countersunk rivets. The rivet
spacing is three inches along the hori/jMital lines.
To calculate the weight of an inner
f !' '">- ^ plate, we may divide it into two jiarts
'^i by the line ///) in the figure, llic
:hJ area of the lower part is ecpial to
the length of CD multiplied by the
^r perpendicular distance between AH
and Gil, anil that of the upper part
by one-half the product of AB and
EF. These dimensions are recorded approximately in the
"Bill of Iron." The length of the outer connecting-plate is,
of course, measured along its centre line.
ou/>/.v.iA'y iRox mGiiivAv-nRin^jEs, ,39
n^c-arca of a section of the four conncctinj^-platos at the
rst .n ermechate ,anel point of the top ehoni 'sho.id .,..
tlua ea of a sect.on of the two chord channels of the third
I'l'icl, or 13.34 square inches. Let us use
two i" X 10" =7,5 ,
and two ^" x 7" = 6.12 j ~ '•'•^^ square inches.
The stress carried by the channels of the third panel is ecmal
o^ hur area nudt.plied by the intensity of wori<in,.stressI or
,v.,4X3.3^>9^44y4 tons; which may be divided equally
between the four plates, making the stress on each plate cihout
.... t.>n. Table XXVIIi. ,ives the thickness of .ll^ of a l^'
-..-3* channel as 0.45 inch, which will make the lever arm
- the stress on the outer plate i(o.45 + 0.43) = 0.44 inch,
.1 the moment 11.2X0.44 = 4.93 inch tons, which divided
a..' «.'^'^''^ "^^^^ ^^ the number of rivets rec,uire<l to
IiKiinnt; ujjon bearmg.
be'takJn ar'''"" ''''' "^ '^' ^"'"' '^" ''''''' "" '^' '^^^""^''^ "^^X
'0-5 X 3.369 = 35-37 tons,
or ai)()ut 8.8 tons per plate.
Thc^levx-r arm is .J(o 3 + 0.43) = 0.36 inch, makin. the mo-
• H nt .S.8 X 0.36 = 3. 17 .nch tons, which divided by 0,3,1 -nves
e^ven as the number of nvets to resist bendin,. Dividin;,7.6
b> i.36 gives thirteen as the number of rivets to resist bearim^ •
or convenience we can call it twelve, as the stress is not quite
M. g,eat as we as.sumed it. It is to be observed that at the h ,
e sun>ose that all the chord stre.s is carried by the conn ^ '
".^-plates. whde at the ne.xt panel point we assume that the
jnnncc >ng.plates carry only the portion of the stress trans-
over Plate ' rr^'^' ""' r'"""'^" '""^ transmitted by the
over plate. The reas(,n for this is, that the cover plate at
tbc .p. ben.g bent, cannot be relied upon to carrv stress.
At the next panel point the stress on one plate'is
14.49 X 3.;,6(;
— I 2.2 tons.
8 i i
11''
Vl%:^
te
140
Oh'n/XANV /A'O.y inuini-AV-BRIDGES.
The sections of the plates will have to be
two T^'
X I
o — S.75 j _ j^ gg gquare inches.
two-rV'X 7" = 6.13)
The thickness of the web is found to be 0.5": therefore the
lever arm is |(o.5 +0.43) =0.46 inch; and the moment, 12.2
X 0.46 =5.61 inch tons, which divided
by 0.31 1 gives eighteen as the number of
rivets for bending.
To find the lengths of the connecting-
plates we must make, as before, a drawing to scale, as in the
accompanying diagram. We thus determine the length of
plates for the first intermediate connection to be thirty inches.
The length of the plates at the next panel point will be greater
by the space required for si.x rivets, or thirty-four inches and
a half, and that at the middle panel point greater by the space
required for eight rivets, or thirty-si.x inches.
Continuing down the " List of Members," we come to the
re-enforcing plates on bottom chord struts. Let us make them
J>J' X 3" in section. It is not worth while to calculate the num-
ber of rivets required to connect them to the web of the
I-beam ; because four five-eighths inch rivets will give an excess
of strength, making the length about ten inches. Next come
the shoe connecting-plates. Let us em])loy the connection
illustrated in Plate VI. From Table XXVI. we find the thick-
ness of bearing for a 2§" pin and a stress of 13.6 tons to be I" \
subtracting from which 0.38", the thickness of web of batter-
brace channels, leaves l" for the thickness of the re-enforcing
plate. Assuming the greatest width of plate in a direction
perpendicular to the length of the batter brace to be sixteen
inches, gives the sectional area of the connecting-plate equal
to sixteen square inches, or that of the batter brace : so, pro-
vided we have such a width, the half-inch plate will answer
the purpose.
The .stress carried by the batter-brace channels is 12.12
X 2.639 = 32 tons, nearly, or i6 tons on one channel. The
iever arm of this stress is .](,] + «) = -Jg", anc. the moment,
T X 16 = 7 inch tons, which divided by 0.493, the resisting-
ORDIXARY IRON HIGHWAY-BRIDGES,
141
nioiiK-nt of a seven-eighths inch rivet, gives fifteen as the num-
])cr of rivets required to resist bending. It is better to use
seven-eighths inch rivets here, on aceount of their large bcnd-
ing-resistance. Tliere is no need of calculatinjr for bearin--
'lo deternunc the dimensions of the connecting-plate, we will
jH-oceed as follows ; t'he distance between the channels at the
shoe being 12.5" — 2 X 2.51" = 7.5".
In the accompanying diagram let us lay out a centre line
AB, and the two parallel lines CD and EF each at the distance
3 1' from AB. h'rom any point A lay
niT the lines ACG and AEH, makin";
angles with AB equal to the inclination
(if the batter brace to the horizontal,
join CE. Draw the lines /A' and EM
parallel to CG and EII, and ten inches a
therefrom : draw also the centre lines
XO and PQ. To allow sufficient clear-
ance for the chord heads, the pin holes
sliould be five inches and a half above
the top of the shoe plate. By crowd-
ing the rivets as near as possible to the flanges of the channels,
\ve are able to use four rows. Laying out the circles for the
pm holes, and limiting distance for rivet centres, we determine
the height of the box plate to be about 14".
If the vertical sides KD and iMF be adopted, the shoe plate
will be 28" long, which is probably too much. To ascertain,
let us find the number, size, and arrangement of the rollers.
The total pressure on one shoe is
, , i860
i X 160 X = 37.2 tons.
2000 ^'
Let us assume the dimensions of a roller to be 2" ■^) by 12".
Turning to Table XXXIV., we find the permissible pressure
on such a roller to be 424 tons, which divided into 37.2 gives
nine rollers. Spacing them 3" centre to centre, and allowing a
projection of i.]'at each end, would make the shoe plate 29"
long. A plate 12]" X 2i)' is not a very good shape. Let us try
rollers 2]'V by 15", the permissible pressure for one of which is
I Mill 118 ^
B i-U p
'I Im
ii? * '
li
142
OA'nLV.lA'V INOX HiaHWAV-BRIDGKS.
5.63 tons ; making the necessary number (37.2 -^ 5.63) seven.
Spacing them 3|", and allowing the same projection as before,
will make the shoe plate 15]" X 25", a better shape. Allowing
the shoe plate to project 3" beyond the front end of the
channels will make the length of the connecting-plate 22",
which distance is laid off from C to R. The perpendicular
distance of A' from AG exceeds 16": so a plate of the shape
CGKRSMHEC, before bending, will fulfil all the require-
ments. To find its weight let it be divided into a rec-
tangle, two triangles, and two parallelograms, as indicated in
the "Bill of Iron."
The next details on the " List of Members " are the re-enfor-
cing plates at feet of posts. From Table XXVI., we find that a
2)\" pin requires, for a stress of 8.6 tons, a bearing of less than
half an inch, but, in order to compensate for a slight trimming
of the flanges of the channels, there must be a plate on the
inside, and another on the outside, of each channel ; and the least
thickness for one of these plates is three-eighths of an inch.
We will not trim the five-inch channels, so will not have to use
an outer re-enforcing plate : this is because there would be no
room for a 3,|" pin through such a plate. The requisite length
for these plates cannot be exactly determined ; for it is impos-
sible to say how much of the bearing-stress is taken up by the
web, and how much by each plate. Let us assume
that the inner plate of the largest post channel
takes up half the stress on the channel, or 4.3
tons. Table XXVIII. gives the thickness of the
web as 0.35 inch. Using |" rivets, and figuring
S for bending and bearing, we find the number of
j rivets required to be nine. Laying out to scale
I the foot of the post, as in the accompanying dia-
^ gram, and allowing five inches and a half between
the centre of the pin hole and the foot of the channel, we find
that the required length of plate is sixteen inches. In the
same way, the lengths of the re-enforcing plates at the feet
of the other posts might be calculated : but it is hardly worth
while ; for, if we make them all of the same length, they will
be sufficiently strong without causing much waste of material.
^
1
ORDLXARY IRON HIGHWAV-nRIDGES. 143
After entering these dimensions on the "Bill of Iron '• we
refer agam to the "List of Members." and, after omi'tting
rc-cnforc.ng plates at middle of posts, eome to the connecting
p a es for lateral struts to top chords. The thickness of these
plates should be |". and the average width of the leo-s .1" The
area of a 4 6* channel is 1.8 scp.are inches, and the'in'tensity of
wo,-k.„g-stress for forty-two diameters with both ends fixed is
by lable XI.. 2.74 tons ; making the greatest stress that could
over come upon the channel r.8 X 2.74 = 4.93 tons. The lever
a™ of th^stress_,s,i(| + |) = ^^ inch, making the moment
]6 X 4-9o - 2.16 mch tons, which divided by 0.380 the resist
,ng-moment for a r rivet, as given in Table XXXVII gives
MX as the number of rivets required for attachment '[o the
atcral strut channel. Although the leverage is a little greater
tor the attachment to the chord-channel flanges, still six rivets
uil; suffice, on account of the liberal estimate for stress, and
us.ng r,vet tables which have a surplus of strength for lateral
system connections. The length of each leg of the T will be
about eighteen mches, for various circumstances will necessitate
wide rivet spacing in this detail.
The stress and leverage being the same in the two attach-
ments. It IS evident that six rivets will be required at each ^d
the upper channel of the lateral strut for connection to chord
Ihere will be just room for this number; putting two through
he channe flanges, and four through the plate between t
channels. Were these not strong enough,
wc could use seven-eighths inch rivets.
The ne.\t item upon the "List" is con-
necting-plates for portal struts to batter
l>'aces. These should have a greater
strength than ordinary calculations would
"Kl'cate, in order to provide against the
niekmg effect of the wind. If we use a jaw plate, as in the
s of the accompanying diagrams, and two bent plates, as
lo second to attach to the flanges of the strut channels
' " ^;f ''" "^^"- '^'■^^^' ''' P--^>- ^^ainst all con-
-'/'■ CD, and /./.. It may be well to test the num-
144
O/^P/X.IKV /A'OX UlCHWAV-BRinCES.
J) AW
i|il
bci- of rivets for the jaw i^late, because it has to act as a
re-enforcinj; plate also. I'irst we must determine the size of
the pin which attaches the vibration rods. The diameter ot
each rod beinp; i|", the greatest working-stress thereon is 7.5
X 0.994 = 7.5 tons, nearly. The lever arm is A(J -f | -f ^) = J".
making the moment |x 7-5 =6.56 inch tons. Consulting
Table XII., we find i '{' ^^ the diameter required. Table XXVII.
shows that there is more than sufficient bearing. Assuming five
tons. upon the rc-enforcing plate, we find the number of eleven-
sixteenths-inch rivets required to resist bending to be
5 x.^^}±J
0.299
= 6,
so that the dimensions in the drawing are sufificient.
Let us assume the dimensions for portal connecting-plates to
brackets and name plates as |" X S" X 18".
The section of a connecting-plate for an intermediate strut
should be |" X 3" ; and we will use three rivets for the connec-
tion to the pos.c, and four for that to the strut : it would be
useless to figure upon these numbers, as the stress is so small.
Owing to the peculiarity of the vibration-rod connection, each
plate will have to be about two feet long, as can be seen on
Plate VI.
Omitting side-brace connection, the next item is the end
lower lateral strut connection to pedestal, which is by means
of a jaw plate |" X 5"- The stress on the strut was found to be
9.75 tons, making 4.88 tons on each channel. The number of
three-fourths inch rivets required will therefore be
0.389
There is no need of figuring for bearing. This would make
the total length of jaw jilate about three feet, as noted on the
"Bill."
For the strut at the fixed end, a plate .]" X 5" X 2' will answer
the purpose.
The next item is the hip cover plate, which we will make of
the same s action as the chord plate, and eighteen inches long.
ORDINARY IROX IfrGHlVA V-BRIDGES.
1.'
2' will answer
1-or the intermediate joints we must calculate the lenoths
of the cm'er plate thus : the stress on the top plate is 3 91
X 3.369- 13 tons nearly; making the moment on the rivets
13 X I'^g =4-o6 mch tons, which divided hy
0.311 gives fourteen as the number of three-
fourths inch rivets required to resist bend-
ing. For bearing, the number required will
be less. The arrangement of the rivets de-
termining the size of the plate is shown to
scale in the accompanying drawing. Next
come the filling- plates. Let us average
those for the top chord at J." thick. For
the thickness of the filling-plates over end floor beams we
"u.st subtract from the distance between centre of pin 'hole
and foot of post the half-depth of the chord heads in the end
l)aneLs, thus,
1^—
1
_- 1 —
17'--*
X X
xj .
X X
X X
X
^
X X
X X
X
X X
X X
y
X X
X X
y
k
X X
^
si
z
5r-^(3l X i! -h20)"= If.
The width will be equal to the diameter of the pin, and the
length equal to that of the pin between shoulders
Next come the extension plates. Let us make them in two
th.cknes.ses, the shorter piece extending down to the stay-
plates. 1- or the largest post, the total thickness will have to be
' ;^' . or 1 1" ; making that of each plate -^-9,", Neglecting the
effect of the stress on the outer plate, the moment ,.. , ,
<"! the rivets will be 8.6 X .' (O. :!5 + o. s6) = 3 gr fl
inch ton.s, which divided by 0.31 1 makes the num- ^'
her of three-c|uarter inch rivets to be employed f
ei|iKil to thirteen. For reasons advanced in Chap- \
tcr XII., we must count in only one half of those ^
nvets wh.cli pass through the double portion of
the plate and the web. Laying off the end of
the post to scale, as in the accompanying dia-
.i^ram, we determine the lengths of the plates to be
twelve and twenty-four inches lespectively The
nv.ts above the line AB are to be countersunk: their use
's sm.ply to make the two plates act as one. We mLdit
i i
lil
;■
IIim'
iiii»i
146
ORD/.yAh')- //cox ///(/////'./ )'-/.' AVM/Y-'.S-.
calculate the required lengths for the extension plates of
the other posts, but it woukl be unnecessary labor ; for if, in
the posts with the seven-inch channels, we use two rows of
three-quarter inch rivets, instead of three, and in the posts
with the five-inch channels two rows of five-eighths inch
rivets, making the plates of the same length, we will provide
suflficient strength with very little waste of material.
The next on the list are the shoe plates, the area for which
we have determined to be I5J"X25": their thickness (see
p. 16) should be I".
To determine the size of the roller plate, we will adopt 3"
X 3" 5-9* angles to enclose the rollers, and allow for a motion
of two inches, which would make the area 2i|"X33": the
thickness should U: I". The area of the plate in square inches
multiplied by two hundred pounds makes about seventy-one
tons, which is nearly double the greatest pressure on the shoe ;
showing that the dimeiv-.ons decided upon are large enough.
The area of the shoe plate multiplied by two hundred pounds
per square inch is equal to 38.75 tons; and, as the greatest
pressure on the shoe has been calculated to be 37.2 tons, it
is evident that we may use the shoe plate as a bed plate by
properly anchoring it to the masonry.
Next come the beam-hanger plates. It will not be neces-
sary to calculate their thickness, as the method was fully
illustrated by an example in Chapter XIII.; and experience
would suggest a thickness of
I'^rom Carnegie's " Pocket-
Companion," p. 126, we find that ^"square bars upset to i^";
and from p. 131 of the same book we see that the longest diam
cter for the corresponding nut is 2.89", say 3"; so that, allowing
1" for clearance, the distance between centres of beam hanger
holes will be /', and the width of plate for full bearing 7". We
can average the lengths of the plates at 8".
The weight of a name plate need not exceed forty pounds.
Next come the latticing and lacing bars. Referring to
Tables XXX. and XXXI., we find for the top chords and
batter braces,
where ^/= o 75 D, tlie bars sliould be iV' X ^l" '>
ORDIXARY IKON niUHU:iV-i;RHKiES. 14;
U)X the middle posts,
where d= \.^D, they should be f X i|"j
for the next larger post,
where ./=Z>, i"x i|";
for the largest posts,
where ^/= o.88Z», 1" X ij"j
for the portal struts,
where,/=i.,8Z), i"x i^i
for the upper lateral struts,
where./>2Z», 1" X 2j-";
aiul for the end lower lateral struts,
wherert'= 1.5Z;, 1" X 2^".
The distance between centre lines of rivets in the chord and
batter-brace channel flan-es is about ten inches; the space
per panel ni chord over which the latticing extends is about
eighteen feet ; the corresponding distance in the batter brace
IS twenty-seven feet : so, if we space the rivet holes for the
latticnig as nearly as possible ten inches apart, there will be
twice twenty-two lattice bars recp.ired for each chord panel
-i one truss, and twice thirty-two bars for each batter brace,
makin- seven hiuidred and eighty-four bars in all. Their
^^^v^\^, from Table XXIX., is found to be 1. 18' + o -'i ;' =
i.;i95', say 1.4'.
We can average the lengths of the lattice bars for the posts
thus : assuming a stretch of nine inches, a spread of eight
nuhcs and a half, and .J" as the width of a bar, gives the total
length ..034 + 0.18=1.214. say M' . The average length of
space on the posts occupied by the latticing is about twenty
cct s,x mches ; making the number of bars per post four times
twenty-seven.
The spread, or distance between centre lines of rivets in
channel Hanges of portal struts, is about six inches and a half,
1 ( 1
fc r
4
!!
\':
■llUlii!'
148
ORIUXARV IROX HIGHWAY-BRIDGES.
and the latticing; extends over about ten feet on the averai^e,
after deducting for various plates ; which would make the num-
ber of lattice bars per strut about four times nineteen. The
length will be about 0.768' + 0.145' = 0.92' nearly.
The spread for the lateral strut rivet centres is eleven inches
and a half; and, as lacing-bars are used, the stretch must be
about si.\ inches and three-quarters in order that the angle
between the bars may be sixty degrees. This distance is
most readily determined by diagram. The length of a bar
is, then, 1. 1 13' + o. 197' = 1.31'- The extent of the lacing is
about eleven feet, making the number of bars per strut twice
nineteen.
For the lacing-bars of the lower lateral strut, the spread of
the rivets is about nine inches and a half, and the corres])ond
ing stretch about six inches. The length of the lacing is about
eleven feet, and the number of lacing-bars twice twenty-two.
The length of each bar is 0.936 '-f o. 197' = 1. 1 33'. s^V 1 1'.
Next mi the "List" comes the chord trussing, of which we
will assume the section to be |" X 3". I^Y ^ I'O".'^!"' approxima-
tion, we can find the average length for one panel of one truss
to be about thirty-three feet. The lengths of the pins are cal-
culated so as to include the weights of the nuts by adding,
in most cases, an inch and a half for each nut. The diameter
of the intermediate vibration-rod pins is assumed to be i^".
The lengths of the bolts include an allowance for heads and
nuts.
To find if there be any anchorage required at the rollci-
end of the bridge, we must compare the overturning and re-
sisting moments, or, what is the same thing, the release of
pressure on the shoe and the weight thereon when the bridge
is empty and there is no wind. In finding the stress on
the end lateral strut, we determined the release of pressure to
be 7.2 tons, and one-fourth the weight of the empty bridge
to be 14.8 tons. The latter being more than twice as great as
the former, no extra anchorage will be required at the expan-
sion pedestals.
As there is vertical sway bracing, the brackets may be light,
Let us make them of 2.]" X 2.]" 4.9* angle-iron, and let them
of which \vc
OA'J)/XAA' J ' I/W.V HIGHU V/ J -BRIDGES. 149
extend vertically and horizontally four feet. Allowin- six
inches at each end for attachment would make the total length
of a bracket about 6.7 feet.
An allowance of ioo# for ornamental work will be sufficient
The equivalent len-th of a beam hanger can be thus approxi-
mately calculated : twice the distance from the centre of the
pm to the top of floor beam equals 11"; twice the diameter of
|.in equals about 6"; twice the depth of floor beam equals 54"-
twice the length of hanger below the floor beam equals 6"'
allowance for two upset ends and nuts equals y^'-, total lcn..th
e(|uals 1 10" = say 9'. '^
Let us average the diameters of the fillers at 31", and their
weight at io# per foot. The average length of filler is not far
lioni 3 . Special fillers will be required at the free end of the
span, so as to keep the lateral strut clear of the batter-brace
channels, also similar fillers at each end of the span to lie
between the outer chord bars and the channels. Let us assume
that the channel flanges are notched out to a depth of one inch •
then the thickness of the last-mentioned fillers will be i J" and
that of the others say |". Let the external diameter be '7"
and the internal diameter 2|": the weight per lineal foot will
then be (see Carnegie, pp. 105-107) 128.3 - 148 = 113 5
Turn buckles and sleeve nuts have already been included,
and there are no connecting chord heads.
Next come the jaws for lower lateral struts. From the cen-
tre of the lower chord pin to the top
of the floor beam being 5.]", the depth
<if the wooden strut will have to be
9"; but the jaws need not be more
than 7" deep, as shown on the accom
panying diagram. The width of the strut need not exceed 7"
>'"■■ that of the jaw plate 6". The thickness of the latter
sh.uild be \ . The greatest stress upon any lateral strut, found
by resolving the stress upon the r,V' lateral rod, is about 7 tons,
which stress has to be resisted by the rivets connecting the
inner and outer jaw plates. The number of rivets required is
7 X .i __
0.3X9"-'^' ''''^'^"'1 ^^'''1 make the total length of the two jaw
-j^
lyv
r^
i^
ISO
ORDINARY IROX HIGllWAV-nRinC.ES.
I';?
plates about 5'. A piece of 6" S.5* chaniK/ will be stron;^'
enough for the bent eye bearing. It is not worth while to cal-
culate the number of rivet« for the combined upper lateral strut
jaw and vibration rod liearins; plate : so we will average the
dimensions as in the " V>\\\ ot Iron."
Next on the " List " comes the angle iron around the edges
of the roller plates, which we will assume to be 3" X 3". weigh-
ing 5.9^* per foot. The length on one side is if, and at the
end say 4|" on each side of the anchor bolt b'^'l'. ; making seven
feet in all for each plate.
Next come the pieces of channels, which we will assume to
be of the sizes marked on the " Bill," and ne.xt the rivet heads,
for which wc will make a separate bill, then enter the total
weight with the other items. Considerable approximation is
used in ascertaining the numbers ; and the fioorbeam rivets are
omitted, for their weights are included in the weight of the
beams. The total length of top plate for chords and batter
braces is about 370' : let us average the rivet spacing therein
at iV\ making the total number 2 X 37° X 12 X ? = 2537.
We may say that there is one rivet for each latticing or
lacing bar for attachment to channels, and one to every two
lattice bars for attaching latticing to latticing. Half-inch rivets
will be used for the latter purpose, so as not to weaken the bars
unnecessarily. Let us assume that half the stay plates are
attached by three-fourths inch, and half by five-eighths inch,
rivets, and that there are six or eight rivets per plate. Let
us average the number at each joint of the chord at sixty-four,
and at each pedestal, not including those through the shoe
plate, at thirty-two ; and let us assume eighteen rivets at the
foot of each post, six per bracket, and fourteen per jaw. The
following will then be the approximate
ORDIA'AIiV IRON H/GHH'A V-BRIDGES,
'51
BILL OK RI\ l/r HEADS.
CONNECTIONS.
2,198 (</ o.oS#= 176*
2,080 @ O.I 6" = 333"
5.715 @o.25"= 1,429"
216 @ 0.40"= 86"
Diameters.
riatt. to chords and batter braces
Latticing and lacing to channels . ,
Latticing and lacing to tiiannels . ,
Latticing and lacing to channels . .
Latticing and lacing to channels . .
Latticing and lacing to channels . .
Latticing and lacing to channels . .
Latticing to latticing
Stay plates to channels
Connecting-plates to channels . . .
Ke-enforcing plates to channels . .
Oinnecting-plates to channels . .
Cimnecting-plates to channels . . ,
Connecting-plates to channels and I
Cover plates to chord plates . . .
Kxtension plates to posts ....
Connecting-plates to shoe plates . .
Trussing to bars
Liackets
jaws
Angle iron to roller plates . . . .
304
190
44
1,084
432
648
96
480
440
180
96
60
84
140
2,198
2,080
r
2,537
784
330
S96
244
80
368
280
196
5715
128
32
56
:i6
Total weight of heads
:.o24#, say 2,ooo# after deducting for coun-
tersunk heads.
Ihc number of spikes requifed will be ten per plank of fioor
(each piank being 9" wide), six per post of Imnd railing, ten per
l)anel for felly plank to flooring, two per joist, and two per jaw •
•" ;i!l, 2,rn2. The spikes shoidd be /;," square by 7" Ion-'
152
O/^niXARV /A'OA' llli.llWAV-liRinCES.
Consulting Carnegie's "Pocket-Companion," p. \2<.), we find
tliat there are 662 spikes to a keg of 150*; so that we requiri.'
four kegs, or to *.
With the exception of the bolt.s attaching the lateral struts to
the floor beams and jaws, each wood bolt must have two wash-
ers ; making in all 385, say 400. Each washer weighs about a
pound.
The weights of most of the nuts have already been included :
let us add fifty pounds for lock \nd pilot nuts.
The total amount of lumber may be estimated in three ways :
first, as in the "Bill of Lumber;" .second, by consulting Table
XV., which gives 2,085 as the amount per panel, multiplying
this by 8, and adding 515, the numbi.'r of fet't in the lateral
struts ; and, third, by consulting Table I., which gives 269 as
the weight of lumber per lineal foot, and multiplying this by
160 X/o- The first two methods are accurate; the last,
approximate.
BILL OK IKON.
Top chord channels . . .
To[) chord ciiaiincls . , .
Top chord channels ...
IJattcr-bracc channels . . .
Po>t channcl^s
Post channels
Tost channels
Upper lateral strut channels
I'.nd lower lateral strut channel;
I'ortal strut channels . . .
Chord plate
ISatter-brace plate ....
Intermediate struts, . . .
I.nd lower lateral strut . .
Ilottom chord struts . . .
Main diagonals
Main diagonals
Main diagonals
Counters
Counters
Hip verticals ......
S
8
S
8
4
8
8
10
10 '
10"
10"
10"
5"
I
8"
4"
5"
4"
A"
4'
5"
4"
i"
3«
I
-II
24-15*
17-5*
20. 2#
7#
io.s#
I4.85#
6#
7#
i2.r'
I2i"
8#I
io#I
io#I
23"
3"
3^'
O
D
D
34'25
10,221
S.I"'
So.V^
900
4,Sjo
57(i
l.)0
820
6,307
759
OUD/X.IKV /A'OX ///GI/H'A Y-niUDGES.
^11
!<), we find
vvc rciiviiiL'
al struts to
two vvash-
^hs about a
II inchulcd :
three ways :
Itint; Table
niulti])lyiii,L;
the hiteral
ives 2^)9 as
ing this by
; the last,
io,2::i
5.'/'
56,V^
f
900
t
ii/i
J
f)86
•5'
•5'
4,Sjo
4'
576
140
■5'
S20
25'
6,307
•25'
75V
/
Si;,
I |i|)ci lak'ial rolls , . .
U|)|)fr lateral rods , . .
l'|i|)t.r I.Utral rods . . ,
l.invcr lateral rods . . ,
I Kttir lateral rods . . .
rinvtr lateral rods . , ,
I.owir lateral rods , . .
\ il>r;iiii)ii rods at portals
\ ilu.iiion rods at jjosts .
1 hold bars
I liMid hars
' lii'id bars
I liord bars . . , , ,
lliior beams
Tiiial weight of main portions
Si.iy plates (HI chords and bat-
li T braces
Slay plates on posts . , . .
Stay plates on i)osts . . . ,
Stay plates on posts . . . .
Slay ])lates on u])per lat. struts .
Slay plates on lower lat. struts .
Slav plates on portal struts . .
l'iinnectiiig-i)lates hip inside .
I ■' iiinecting-plates hip inside .
I'MiiRctiny-plates hip outside .
• uniiccliiin-plates int. insidu .
CiiiuH-clinj^-plates int. inside .
CimiRcling-plates int. inside .
CniiiicclinfT-plates int. outside .
CdniR'ctiiin-plales int. outside .
('omR'ciiiii;-plates int. outside .
< 'tiiuiccting-plates, b. ch. struts .
• '"imecting-plates at shoes . .
Kcenforcing plates, ft. of posts
inside
Ki enforcing plates, ft. of posts
inside
Ke-eiil'orcing plates, ft. of posts
inside
Ke-enfnrcing plates, ft. of posts
"iilsidc
Ke-cniurcing plates, ft. of posts
mitsiile . .
4
x\"
4
li"
4
\l"
4
Mr
4
i.'ff"
4
li"
4
I"
S
li"
10
\"
s
■\"
8
\i"
16
\"
r-
\"
y-
s
16
16
20
4
1 6
8
S
S
8
S
4
8
8
4
16
4
S
8
27"
A"
\"
i"
/'„"
i"
\"
1"
-1
H
'■)"
i"
3"
1 ti
iJ."
11!
w
O
o
o
©
©
33"
si"
3i"
Jl"
54i* h. b.
i"
V
r'
S"
si"
6J"
6J"
8"
9"
■aV
9"
4"
-."
/
10"
10"
10"
7"
7"
7"
3"
7J"
0"
10"
8"
7"
S"
6"
S"
29.5'
21'
19'
-^3'
16'
I2i"
loi"
II"
II"
•3i"
It"
8"
3'"
36"
35"
30"
34 J"
36"
30"
34i"
30"
10"
22"
7"
i8i"
16"
16"
16"
16"
16"
3.4SS
557
3S0
10,459
6,104
5;.')r3
27S
32
76
99
150
28
353
204
250
335
'75
204
235
123
42
367
380
'54
ONP/XARV IROX J in; /III' A V~/lN/nGKS.
ConnL'ctinn-platcs, hUcial slnit
to clunds
<.'onin.'Ltiiig-|)l;itcs, portal strut
to batter braces
(,'oniicttiiii;-plates, portal strut
to i)alti'r braces
fonncctiii.n-platcs, portal strut
to bracUcts
(,'onii(.Htin,L;-|)latcs, portal strut
to name plate
ConiRLliii.u-plates, int. strut to
posts
C'oiinectiiiij;-plates, ciul lower
lateral strut
Coiinecling-plates, euil lower
lateral strut
Cover plates at lii]is ....
Cover plates at int. joints . .
l'"illin,i;-iilates at hips ....
FiUiug-lilales at int. joints . .
Filling-i)lates over lieanis . .
I"..\tension plates
l'..\tension plates
K.xtension plates
I'^xtension plates
Extension jilates
I'',xlensinn ])lates
Shoe jilales
kulkr jilates
He.ini-lianger plates . . . .
Name plates
Lattice bars on chord and bat-
ter braces
I, .mice bars on posts . . . .
Lattice bars on posts . . . .
Lattice bars on posts . . . .
Lattice bars on portal struts .
Laciug-bars on upper lateral
struts
Lacing-bars on lower lateral
strut
Chord trussing
Tins, top chord
I 'ins, top chord
I'ins, top chord
i'ins, bottom chortl
Tins, bottom chord
8
i6
4
4
10
8
1 6
4
cS
8
8
8
4
4
4
'J
M
7S4
432
4.3-
216
304
lyo
44
S
4
4
6
10
8
3"
Ml
4
\"
rn
A"
Vr,"
T-r,"
' 4
'.' //
ll!
•I //
ti;
1"
@
1 li
34
3i
2j"
4"
8"
8"
8"
5"
1 2 .',"
10"
10"
-,:■"
8"
8"
7"
7"
5"
5"
I si"
2ii"
7"
40#
If'
,6"
3"
o
3'
3'
8.i"
18"
18"
18"
17"
iCj"
12"
12"
12"
24"
12"
34"
J 2"
24"
-5"
3f
8"
each
1.4'
li'
■r
'i'
0.92'
il'
3.3'
16"
1 8"
18"
22"
I 20"
'S»
f)0
150
f\5
3.1
7«
1S5
?,i
61
360
245
s.s
377
345
191
So
:.57-
844
7SS
3f>S
■tP
S,S
147
120
507
241
ORD/X.IRV IRON HIGI/IVA Y-nRIiniF.S.
155
3'
'5»
3'
120
8i"
"3
18"
[ 60
18"
2>
'50
1.4'
>r
f'3
7^
61
245
NS
377
34 ■-
191
So
-.57-
844
78S
3f'5
HI
SS
6(0
147
I3'3
120
507
241
Tins, ])ortal vibration ....
Tins, |)o:it vibration ....
Molts, name |)lates
liiilts, vibration rods ....
Holts, anchor
Hulls, portal struts to i)atter-br.
Hulls, hand-rail
Holts, lower lat. strut to beams
Holts, lower lat. strut to jaws .
iiolts, folly plank to floor . .
Holts, felly plank to hand-rail
posts
Hrackets
' 'rnaniental work
8
10
4
10
8
8
68
49
28
66
34
14
il"
J?"
1 @
@
II"
@
i"
I'll
l"
ill
4
ill
2i"X2j"
©
\*
5#
8#
©
©
©
©
©
4.9#L
12"
8"
each
each
3'
each
12"
14"
12"
15"
18"
6.7'
74
61
4
50
98
64
100
5S
41
121
75
460
100
^'43
232
12
6
100
97
700
•75
-^3
60
2,000
(JOO
400
Heain hangers
l'7vpansioii rollers
Holler flames, sides ....
Roller frames, rods ....
Hilkrs
2S
>4
4
6
40
8
•4
10
2
14
111
2\"
1 '/
4
I //
@
7"0
7"0
\ii
i
ill
6"
D
2"
io# JK-r ft.
1 13.5* per ft.
113.5* per ft.
6"
14"
S.'#
.S.5#
9'
•5"
22"
17"
-,//
I ' "
5'
12"
7
6"
i'llleis
1-illeis
j.iw plates
jaw plates
Angle iron on roller i)lates . .
I'ines of channels !
Hivel heads
Spikes
• • •
Washers
• • • •
. *
Nuts
• •
. . .
•
■ ■ ■ 1
'I'olal weit'ht of details . .
19,850
57.9' 3
Weight of main portions . .
• •
Total weight of iron . . .
77.763
1
i
I
nil. I, OF LUMIU-.R.
|oi>ts
flooring (e(iuivalent) ....
80
4"
,4"
20'
7.4'''7
160
I ^"
14'
6,720
1 l.iiul rail ....
-•"
(•)"
i l.iiul-rail |)()sts
j-
20'
040
34
4"
6"
4'
Hull planks
16
2"
tj"
20'
640
Iilly planks
' Ucral struts
10
7
6"
7"
6"
9"
20'
14'
960
5'S
'I'olal nnnii)er of feet, board
nieasMri'
17,214
156
OI^D/NAKV JROX lllLJllWA V-H RIDGES.
Tabic I. gives the weight of iron per lineal foot of bridge as
479 pounds, which multiplied by i6o gives 76,640: adding 600
pounds for the spikes, makes the total weight of iron 77,240
pounds. This indicates an error in the table of only seven-
tenths of one per cent, — a very satisfactory result.
If we deduct the weight of the end lower lateral struts, roll-
ers, roller plates, anchor bolts, etc., which really do not come
upon the bridge, in all about 1,400 pounds, the dead load per
lineal foot will be "^W^'^ + 269 = 746; which agrees within six
pounds with that assumed.
It may appear to the reader who has carefully followed out
all the calculations in this chapter, that the designing of iron
bridges, and estimating weights thereof, involve a great deal of
work, and demand considerable time : but such is not necessarily
the case ; for an expert could have made this design in from two
to three hours, because his experience would have told him the
sizes of many of the details and the number of rivets to empiov.
In this chapter everything has been figured out carefully enough
for making \v'orking-di-awings, instead of merely an estimate of
weight ; foi the author considers that it is better to teach the
beginner oxact methods in the first place, and leave him to
vlevciop ipproximate ones as his practical experience increases.
A u!-cful deduction which can be made from the " 15111 of
Iron " in this chapter is the proportion which the weight of the
rivet lieads bears to the weight of the rest of the iron, excluding
that of the floor beanis, spikes, and washers. In this case the
ratio is about ^^^^(^ = 2.92 per cent. The average for a number
of estimates made by the author is 2.85 per cent, the greatest
being 3, and the lfia»t 2.4 per cent. The knowledge of this
fact will save consideiable time for any one who has many esti-
n^a^es of weight to make.
The author at «;n(; time, when in haste, used to figure out the
total weight of , jn portions, and divide by a certain quantity
less than unity, in order to determine tiie total weight of iron,
but has now abandon*.'! the methotl as giving too loo.sc an
ap|/roximation, finding that the correct divisor varies considera-
bly with the leiigtli <A hj)an and the class o' bridge. Tables 1.,
II., and III. give the weights of iron for all cases far more
accurately Ubim will *ny such apinuxiniation.
of brid<ie as
ORDINARY IRON HIGHWAY-BRIDGES.
157
CHAPTER XVII.
BRIDGE LETTIXGS.
The ordinary modus operandi of bridge Icttings is by no means
the most perfect that could be devised.
A couple of months before the letting, advertisements are
inserted in some of the local newspapers, stating that on a cer
tain day at noon, in the county town, at the court-house, there
will be let the contract for building a bridge, or several bridges,
in the county. The length of span and clear roadway are nearly
ahvays given; and sometimes this is all, for the commissioners,
as a general rule, do not know whether they want an iron or a
combination bridge. Sometimes, even, they accept a wooden
oiif after advertising for an iron bridge. Occasionally a very
fan- list of data is advertised, but such is not the rule. In addi-
tion to the local advertisements, circulars are often sent to the
various bridge companies, requesting them to send representa-
tives to attend the letting. Little do the commissioners think,
that in the end the county has to pay the travelling e.\i)enses
of each representative who attends, as well as for his time.
Instead, they .say, "The more, the merrier," and congratulate
themselves when they have a good attendance, thinking, that,
the nu):e representatives, the greater the competition. It may
Ix' ,su in certain cases ; but ultimately some one has to pay each
traveller's expenses, and who but the counties is there to do it >
It is true that mailed bids are received : but they are very sel-
dom accepted, even if the figures l)e the lowest ; for the commis-
sioners are generally unable to resist the combined eloquence
••f half a dozen bridge-men. It would be much better for all
parties concerned if bids were all sent by mail, and if the
awards were made by a competiMit engineer. It would permit
i
, .A
'iM'an,
I 1 r
! I
,
ii
IWi
158
ORDINARY IRON HIGHWAY-BRIDGES.
of the reduction of the staff of each bridge company, the less-
ening of cost to the counties, and, what is more important, the
building of better structures. When, by means of much com-
petition, the contract price for a bridge is reduced to cost, or
even below it, what does the successful (?) competitor generally
do ? Lose money ? Not at all if he can help it : that is not his
way of doing business. He puts up a cheap bridge, cutting
down weight on the details, and shaving as much as he dare on
the sections. The author does not wish it to be understood
that such is the method of the better class of bridge companies.
They generally know better than to let their travelling men
take contracts for nothing ; and when they do get bitten, as they
all do occasionally, they put up the bridge at a loss, and take it
out of the next county where they obtain a contract.
When remonstrated with for collecting a large crowd to
attend the letting of a little bridge, county commissioners have
been known to respond, " You see, we don't know exactly what
kind of a bridge would be best for the place, nor what style of
bridge the money at our disposal will pay for ; and when we get
a lot of you bridge-men here, who know all about it, we are able
to find out exactly what we need." Travelling bridge-men who
know all about it ! Bridge companies are not willing to send
their engineers travelling about the country to attend county
bridge lettings. They cannot afford to pay for this purpose
salaries of two or three thousand dollars per annum, when men
can be obtained to do the work for one-third of that amount.
When an engineer is found at a bridge letting, it is generally
because he has tired himself out at office-work, and needs a
little change.
It is surprising how little the average travelling bridge-man
really knows abo'it bridges, and how incapable he is of giving
advice of any value to a commissioner. What he does know is
how much bridges will probably cost, and this knowledge lie
obtains from the company's engineer. Mis forte is to do tlic
heavy talking, in which it is by no means necessary for him to
stick to the truth.
On the day of the letting, four or five honest farmers (they
LUC honest usually, though there have been and are exceptions)
ORDINARY IRON HIGHWAY-BRIDGES.
159
mc
u'ct to determine upon who shall have the bridge. In some
cases, after the bids are opened, the contract is immediately let
without discussion, to the lowest bidder. At other lettings'
each company's representative is allowed to hold forth, in turn'
before the assembly, and show in what way his bridge' is supe-
rior to the rest.
Some of the arguments advanced are really amusino- One
will say "Mine is the best bridge, for it has the most^ron in
the chords " (Ignoring the fact that his bridge has a less depth
of truss than any of the others). Another says, " My bridge is
the best, because it has the most panels ; and it is an acknowl-
edged fact, that, the greater the number of panels, the stron-er
the bridge." Another will point to the size of his floor beams
forgetting that his bridge has one less panel than have any of
the others. With such nonsense are the minds of the poor
commissioners crammed, until they do not know the difference
between a cumter and a batter brace (in fact, it is more than
probable that they never did know) ; and the result is, either
that the letting is broken up, or that the contract is let to the
one who has done the most talking, and has impressed the most
lalsehoocis upon the understandings of the honest farmers.
Sometimes the commissioners conclude to have the letting
done in style, so engage the services of an engineer. Their
accjuamtance with the members of the engineering profession
being rather limited, they employ to decide for them the county
surv eyor, whose technical knowledge is confined to the use of the
compass and transit, and whose mathematical education never
went much farther than arithmetic. Or perhaps taey will find
some one much looked up to in the county as an engineer, who
iias been plucked at some technical school, and returned home
t«> enjoy the honors of having been a college-man.
As Professor Vose, not long ago. stated in a very able article
luihlishcd in the "Journal of the Association of Engineerin<.
Societies •• and "Van Nostrand's Mag.^irH.." in -r.ier to insure
the l)u,l,i,ng of none but good bridges, there miust be a State
■nspector, whose duty it would be to pass iii<lgment on the
Pl.nis <.f all bridges, before p.Tn,itting them to be erected in
'-K' State. Such an inspedor should be, not an ordinary en-i-
i6o
(V^nrxANv //c(hv iiighway-bridges.
neer, but an expert in bridge designing. He should receive a
handsome salary, and be allowed enough assistance to enable
him to do his work in a satisfactory and efficient manner. His
ter.ure of office should be for life, or for a long term of years,
and should be beyond the reach of politics and politicians. As
long as his work be done efficiently, his position should be
assured to him ; for a man of the requisite experience and ability
would not be willing to accept the position under other condi-
tions.
The letting of bridge contracts to the lowest bidder is the
worst method that could be adopted, even when plans and
specifications are on file ; for the work generally goes to the most
unscrupulous bidder, who will secure his margin of profit by
diminishing the weight of the details. This weight should be
about twenty-five per cent of the total weight of iron-work in
the bridge, and it is quite possible to reduce it to one-half of this
amount.
If ignorant commissioners must have a rule for letting, it
would be better to award the contract to the highest bidder.
But the proper way would be to engage the services of a man
who knows something about bridge construction, and have him
figure out the probable cost of the bridge, allowing a fair margin
for profit. A margin of from fifteen to twenty per cent is not
excessive, even upon a liberal estimate of cost ; for such a
margin by no means represents the contractor's actual profits.
From it must be subtracted, not only a portion of the annual
office expenses, including salaries of clerks, draughtsmen, and
engineers, but also the bidding expenses of several lettings
where the contractor has been unsuccessful. Then, too, there
is the risk of bad weather, high water, rise in ])rice of iron,
delay in shop, etc., any one of which is liable to absorb the
whole calculated profit, to say nothing of the liability of losing
the bridge by a freshet during erection.
When the appropriation is small, it is much better to build
a good combination bridge than a poor iron one, because the
wood-work of the former can be replaced when it wears out ;
while the iron, if properly cared for, is as good as new. Hut a
used-up iron bridge is worth little more than the cost of taking;
OA'DJXA/n- /A'O.V JIIGIIWAY-BIUDGES. .Cn
il^^'l-^vn, and transporting- it to where it can be sold for old
TiK. method of having plans and specifications on file for
cv.ry competitor to bid upon is not a good one. In the firs
1 ace. .t necessitates the sending of engineers to the letting, or
at Ic St ose who are capable of figuring out the weight of a
bndge, thus greatly increasing the bidding-expense • then i
the p ans are at all defective in design, a fi;;t.cL om^
-nvdhng to b.d upon them. It is much better to let elc
company bid upon its own designs
V^ most city bridges and for very large county bridges, it is
- h a bridge company's trouble to prepare special dL n^s •
'-t.lor ordinary county lettings. standard drawings will ansvt .'
^ciy purpose when accompanied by a diagram of stresses and
special specifications. If the letting is to be done by an e.vd
ncer. a plate of details similar to Plate III. or Plate IV. will Se
uf cient but the ordinary county commissioner does not u der
<:r ih s"f '""""^- ^^^"^^ ^^ ^- -hat the bridge
^^'11 ook like. Such a picture as the one given on Plate I
would be very taking with county comnussio^ers. but thJ e s
..rea dea of labor involved in making such a drawing. As
.general rule, a sheet showing side and end elevati.ms an
a plan of either the whole or one-half of the bridge, will b 's
uot when supplemented by a sheet of details
It IS nut unusual for a fancy drawing to take a contract when
thcic are much better and even cheaper structures in com,;:;;:
^ JhyHagram of stresses should be filled out as shown on
Specifications should be quite e.vplicit without bein<^ Ion- o,
-" -ing to a reader of o,-dinary intelligence. The uTh
-u 1 recommend the following or some similar form of
J 6:
OND/XAKY /A'OA' HIC.UWA V-ltRlDuES.
SMITH & WILLIAMS,
BRIDGE ENGINEERS AND BUILDERS,
PITTSBURGH, PENN.
SI'FXIFICATIONS FOR BUILDING A WROUGHT-IRON HIGHWAY-BRIDGE.
ri
Length of Span. — To be feet inches between centres
t end pins
bearings.
Clear Roadway. — To be feet nclies between innermost
portions of trusses.
Live Load. — To be pounds per lineal foot of bridge.
Dead Load. — To be pounds per lineal foot of bridge.
Depth of Truss. — To be feet inches between centre
lines of chords.
Clear Headway. — To be feet
lowest part of overhead bracing.
inches between floor am
Upper Chords and Batter Braces. — To consist of two inch ch;in-
uels, with a plate inch by inches above, and lattice
bars inch by inches, riveted together at tiieir mid-
flle points, below.
Splicing of Joints in Upper Chords. — Sliall be madr l)y a jjlate on e:i( li
side, as shown in the accompanying draw int,^ Tiiesc plates shall lie
of such thickness as to atford sufficient iiearing for tlic pins, and tluir
combined sectional area siiall not be less than that of the ciiannels
which they connect. Xo splice plate to be less than three-eighths i J)
of an inch in thickness. These connections shall be designed •■■"'
the supiiosition tliat the entire stress is carried by the jjlate
rivets, no reliance being placed on abutting ends of channels.
Cover Plates for Choi Js. — Shall be inch by inches !
inches, and sliall contain a^ many rivets on each side of ■'-
joint as will suffice t" carry tiie i;reatesL stress tha: cm ever cnnic
upon tile chord plates.
iiii'!i r
s ami
JHWAY-BRIDGE.
between centres
tween innermost
between centre
ctween floor anil
( >a-/j/a:ia- i - /A'OA- iiuiiiu -,/ J '-nA'/ih;Ks. 163
i'ticI) by
Stay Plates for Chords and Batter Braces. — Shall be
inches.
Posts. - Shall consist of two ciiannels, of sizes as marked on the accompanv-
ing diagram of stresses. The latticing for same shall vary from
;"*:'' ''^: , ,■, 7'^*^^ J-^ ^^^^ ^y inches; the'bar;
bemg riveted together where they cross each other. The posts are to
be attached at their ends to the chord pins, an<l are proportioned for
both ends hmj,a.d. At the upper ends the connections are to be made
by extension plates, each of which is to have a sectional area between
the pin hole and stay plate equal to twice that of the channel to which
It isattached. The entire stress in the posts is to be considered as
c.-irried by the extension plates and their rivets, no reliance being
|.laced on abutting ends of channels.
Upper Lateral Struts. - Shall consist of two channels, ''''?"' of sizes
, , latticed,
given on the diagram of stresses, rigidly attached to the chord.
lacing
^ '''■■ lattice '''^'■'' f""" ^'T"*-' •'^liall vary in section from
^^: ,; /"'^•'^^ '° i"^l> by inches; and the
.stay plates, from inch by inches by
'"'^''^^ '« inch by inches by .. inches
s.
inch
Portal Bracing (at each end of the
o
laced
one
i span). — Shall consist of , struts
, , , two "•'"'^=>»
each composed of two inch channels, as marked on the
diagram of stresses, ,^^^.^^^, „y „ars i„ch by
inches in .section, with stay plates inch by inches
b>' inches; also lour adjustable rods, each inches
m diameter. The struts are to be rigid.- atached to the batter
i)races.
Vertical Sway Bracing(between posts). - Shall consist of two vibration rods,
^■^'-■'' '"ch in diameter, and an intermetliate strut of
inch I-beam, weighing pounds per foot, rigidlv attached to
t..e posts at a distance of feet inches below the
level ot the upper chord pins.
End Lower Lateral Struts. - Shall consist of
Intermediate Lower Lateral Struts. -Shall consist of inch l,v
inch pine timber, lying upon the Moor beams, and well bolted
thereto, and attached by vsrought iron jaws to the chord pins.
• I
ir,4
oN/u.y.ih'v /A'ox iiminvA v-i'>Riin;i-:s.
Side Bracing. — Sliall (onsist of indi liy inch
pound angle iron, well rivitcd to the t(>|) iliord and to tlii' lluor lu-ams.
whicli ari' prolonged feet inches at eaeli end be-
yond tiie trusses for this purpose, as shown on the aecomimnying
drawing.
Bottom Chords. — .Shall consist of eye bars, as marked on the di.igrani of
.stresses, tliose in the two panels next to each end of the span being
trussed.
Main Diagonals. — Shall consist of eye bars of the sections marked on the
diagram of stresses.
Counters. — .Sh.dl consist of adjustable rods with loop eyes, the sections
being as irarked on the diagram of stresses.
Upper Lateral Rods. — Shall be from inch to inches
round iron, attached by bent eyes to the chord pins.
Lower Lateral Rods. — Shall be from inch to inches
round iron, attached eithcf to the chord pins by bent eyes, or to special
pins passing tiuougli the lateral strut jaws i)y loop eyes.
Floor Beams.
Shall be
rolled
iiuilt
licanis inches dee]), weighing
pounils per lineal toot; web inch by
inches; ujiper llanges. two inch by inch
pound angles; lower llanges, two inch by inch
pound anulcs. Stillencrs to be of inch by
inch . pound angles, jier beam, niaele tiush with the
vertical legs of the Hange angles by liHing-i)lates.
Beam Hangers. — Are to be of
four
I'ountl upset
inch iron.
sciuar."
not upset:
there are to be ^^.^^ of them to cacli beam.
Beam-Hanger Plates.— Are to be inch by inches by.
men
Shoe and Roller Plates. — Are to be inches
thick.
Pins. — Are to be of the sizes marked on tlie diagram of stresses. They shall
be turned so as to tit the pui holes within one-liftieth (jl,,) of an inch.
Pin Bearings. — .All jjin bearings ;ue to be properly re-entorced.
; niaikfd on tlic
."s, tlie sections
ORDIXARV IROX IIIGHIVA V-IIIUDGES.
1^5
Brackets. - A straight bracket of i,„h by inch
pound an :le iron is to l,e used to connect each post to tl,e overhead
strut. Ihoseforthf portals are to he ot inch l.v
'"L-h pound
rivets at cacli lik
ui.i,'lc iron The)
be connected by
Chord Heads. - .Shall be of standard shapes, and so strong that the bar will
l.icak in the body rather than in the neighborhood of the eye.
Upset Rods.- Ail adjustable rods, unless otherwise specified. ,o have
heir ends . Hiarged for the screw threads; so that the dian.eter at the
h 'll' .; of .T l"T' ff 1" ""•^--^'-■"'" ^'«^ ^'f -' -ch greater
tl an that .,f the body of the bar, scjuare or Hat bars being figured as if
of ecjuivarnt round section.
Riveting -Riveting shall in every respect be in accordance with standard
authonties; and all riveted connections shall be designed for he
nvets to resist the greatest shearing, bearing, and bending stresses
Expansion. _ .Shall be provided for by .
Anchorage. -At one end of ^^^^ .sp,n, the superstructure is to be an-
chored to the foundations by bolts, each inches
'" •"'^""^'^'•' =^"'' ^' l^^^t feet inches long!
Ca.be. Shall be at least finches when the bridge is empty, and
'" '^-'^^ "iches when fully loaded.
'"°"' ^""'Tiir ^'''" ™""" "^ '""' "^ '"'^'^ by
i'Hh ,,^^,^ joists, dai)ped and spiked on the lateral struts; and the
lloor plank shall be of_ i„ch pine or oak plank laid diago-
nally or square across the bridge, as may be preferred, and well spiS"
1" •''^; J"'-^'-^- ^ f^'lly plank of inch by . ,„ ch nine
Hand Railing. — To consist of
^
.0^. "'>.^;
IMAGE EVALUATION
TEST TARGET (MT-3)
1.0
I.I
u
IM
2.5
2.2
^ IAS IlilM
1.8
1.25
1.4 1.6
♦ 6"
»k
V]
<^
/^
/.
>!^
^^^
#
Photographic
Sciences
Corporation
23 WEST MAIN STREET
WEBSTER, N.Y. 14580
(716) 872-4503
i
!l
1 66
OIWfNARV IROA- HIGHWAY-BRIDGES.
Details of Construction. — All details of construction to lie i)ropcily pro
portioned with clue regard to the various direct and indirect stresses
that may come upon them. All joints to he machine dressed and to
fit perfectly. Riveting in the field to be performed in a skilful man-
ner, using the button set. There shall be no loose rivets in the
bridge.
Quality of Materials. — Iron for tension members to have an ultimate
strength of pounds per square inch, and an elastic limit of
pounds per square inch. Iron for compression members to
have the usual correspondence of strength. All timber to be sound
and of good quality.
Workmanship. — All workmanship to be first class in every respect, and to
be performed to the satisfaction of the engineer or commissioner in
charge.
., 1 88
(Signed)
SMITH & WILLIAMS.
With the diagrams of stresses, plans, and specifications, there
should be handed in, or sent to the commissioner, a proposal in
the following or some similar form : —
To the County Commissioners of County,
State of
Gentlemen, — We the undersigned hereby agree to build, and put in con-
dition for travel, the superstructure of an iron highway-bridge of
spans, across ' i" "i<= bounty
of , State of .according
to accompanying plans and specifications, for the sum of
dollars cents ($ ).
SMITH & WILLIAMS,
, 1 88.
After the contract has been awarded, the successful com-
petitor and the commissioners must sign it, and a bond must
generally be given by the company as a guaranty that they will
complete the work according to the specifications. It is well
for the representative of each company to be provided with
ORDLYARV /A'ChV HIGHHA V-IUUDGES.
l)lank forms for contract and bond. The author would
mend the following for this purpose : —
167
recom-
:T
BRIDGE CONTRACT.
& WILLIAMS.
\ & WILLIAMS.
This Agreement, made and entered into this
nt
lifiilijL' hii
th
day
:t;:::Z--^^:--^^^
Count}- of c» » r
•' , State of
parties of the second part,
Witncsseth That the said narties of thp five . 1
of a
bridge
across
> in said county,
-'':;,:;*Y,',i;: :''""'' """ '--- - ';-„f *--- '■■■■
l»i<k. a, a. ' , °. " ,"' '""■'.'""'■' •i''!"""' '!"■ '"alcrial tor safd
of
ItndL^c CO
A.[). iSS
I'll:
Mi'
l68 ORDIXARY IROX HIGHWAY-BRIDGES.
part contract, and agree to pay to tlie said parties of the first part tlie sum of
dollars, payable as follows :
/// witness whereof the said parties do hereunto affix their seals and
signatures the day and year above written.
L^I^AL.]
[seal.]
[seal.]
[seal.]
BOND FOR BRIDGE CONTRACT.
Know all men by these presents, That we. Smith & Williams of Pitts-
burgh, I'enn., as principals, and
as sureties, are held and firmly bound to the
in the State of in the penal sum of
dollars, for the payment of which, well and truly to be made, we bind our-
selves, our heirs, executors, administrators, and assigns, jointly and severally,
firmly by these presents.
Dated at in the County of
and State of this day of , i88
The condition of this obligation is such, that if the said Smith ilv:
Williams construct bridge in the aforesaid county, according
to llie plans, specifications, and contract hereto attached
tlien this obligation to be void and of no effect, or otherwise to remain in
full force and virtue in law.
Principals.
Sureties.
ix their seals and
ViLLIAMS of Pitts-
ORDINA R Y IROX HlGmVA Y-liRlDCl-S. 1 69
The previous remarks concerning methods of bridge lettin-s
w.ll probably not be altogether approved of by contractor!
Mr A. I. Boiler, C.K., in his treatise on "Iron Highway-
Bridges, writes, '< It will be noticed in the last clause of the
lorin for 'Invitation.' bidders are requested to be present at
the opening of the bids, and hearing them read. This is simple
just.ce. And when one considers the time required to make
plans and estmiates, even for a small piece of work, to say
noticing of the expenditure of money incident thereto with
l-robable travelling-expenses in addition, no fair-minded man
can object to rendering at least what satisfaction may be derived
tn.m the public opening of tenders. Bids secretly opened
always lead, whether justly or unjustly, to the suspicion of
unfair practices, an imputation that can be readily removed by
inc method of publicity suggested, a method which can be
()I)jected to by no one. unless those whose mode of doin- busi-
ness seeks darkness rather than light." This is a clear and
well-stated argument, and it is difficult to propose a method
that will overcome every objection advanced. ii„vvever there
are some points in it that will bear criticising.
iM.r a bridge worth, say, twenty thousand dollars, all that
Mr. Bo ler says is certainly correct. But is it so for a small
c.nmty bridge ? The majority o. county bridges do not exceed
unc hundred feet in length, and they are very often let sino-ly
How long wdl it take, in a well-regulated office, to preplire
plans and estimates for an ordinary one hundred-foot county
hndge. Usually about thirty minutes; at any rate, no more
tnan two or three hours. The work consists in taking out of
their proper places a blue print of the diagram of stresses a
sheet of details, a general plan, and blank forms of specification
and pn.po.sal, then filling out the two latter, and enclosin- all
'" an envelope for the post. The making out of the estimate
ot cost should not take five minutes when the amounts of iron
a"'l lumber, and a complete list of data, are at hand If the
span be of unusual length, as sometimes happens when re-
])lacing an old structure, it may be necessary to make out a
new diagram of stresses, but not to prepare a bill of material •
t"i- every bridge company should have tables of weights of iron'
I
170 OJaJJ.XAKV /A'OX JlIGIIWAY-IiRIDGES.
and amounts of lumber, for all ordinary cases. The actual
cost to the contractor, of an ordinary county bridge of one
hundred feet span and sixteen feet clear roadway, can be seeii
from the following estimate : —
Wrouiilit-iron, 27,900 lbs. at 5c 5l>39S 00
Lumlier, io,8<So ft. at #18 per M '95 84
Haulinj.j, 20 loads, at $1.50 30 00
Framing 7 00
Falsework 25 00
Erection 1 50 00
Paintinij; 25 00
Blacksmi thing 5 00
Coal 2 00
Frcii^ht on tools 15 00
Travellin<:;-expcnscs 30 00
Men's time travelling 20 00
Bidding-ex])enses 40 00
Teaming during construction lo 00
Incidentals 50 00
Total cost of bridge f 1,999 ■'^4
Cost per lineal foot, say 20 00
Adding twenty per cent for profit would make the bridge
cost the county $2,400. Now, suppose there are ten other
bidders present, each of whose expense for time and travelling
is forty dollars ; then there will be an additional four hundred
dollars to be added to the cost of this or some other bridge,
for, as before stated, some one must pay it. Kleven is by no
means an unusual number of bidders for a small span : there
are often as many as fifteen or sixteen.
The estimate for forty dollars for time and travelling-expenses
is not excessive, as the author, who has attended a number of
lettings, can testify.
These four hundred dollars are worth saving, if it can be
done legitimately.
As for bids secretly opened always leading to the suspicion
of unfair practices, it is indeed true ; and there is no way of
avoiding the difificulty, except by having them opened by a com-
mittee of public men who are above suspicion. These could bo
'J£S.
ORDINARY [RON HIGmVAY-IiRlDGES.
I/I
.
The actual
bridge of one
y, can be seen
• ?i,39S oo
• 95 84
30 00
7 00
25 00
150 00
25 00
5 00
2 00
15 00
30 00
20 00
40 00
10 00
50 00
i?i,999 '"^4
20 00
ake the bridge
are ten otlicr
and travelling
1 four hundred
t other bridge,
leven is by no
ill
span : there
elling-expenses
d a number df
g, if it can be
government employees, and residents of the capital of the State,
to which bids for all county bridges should be sent. Ihe duty
of the committee would be merely the opening of the bids, and
the recording of the amounts. The inspector of bridges, who
should also reside in the capital, should then examine the bids,
and report to the county commissioners, which, in his opinion,'
is the best bridge for the money (i.e., which he would advise
tlnm to accept), and which bridges arc up to the specifications,
and which not, leaving the final decision to the commissioners.
A summary of his report should be advertised in certain of
the engineering.papers, say the two which have the greatest
circulation, so as to let the public see that there has been fair
play, and to clear the inspector of any imputation of unfair prac-
tice. The advertising of the report, including the price for each
bridge and the estimated weight of iron in same, would serve
to prevent any connivance between contractors and commis-
sioners ; because any decided departure from the recommenda-
tion of the inspector would immediately awaken suspicion.
No bids without an estimated weight of iron should be
received ; and, should the inspector doubt the genuineness of
the estimate, he could easily check it.
Then, too, the bridge should be weighed at the railway sta-
tion nearest the site ; and, if the weight be found wanting more
than a certain per cent of the estimated amount, the contractor
.should be fined.
\\\ this way the only possibility of fraud would be an agree-
ment between a certain bridge company and all the mem"bers
of the committee for the latter to insert the contract price in
their hid .so as to make it just a little lower than that of any
other competitor. Considering that the committee would be
composed of a number of the most prominent state officials, the
I)robability of such a fraud ever occurring reduces to zero.
i
• the suspicion
e is no way of
lened by a com-
These could be
\72
ORDIA'ARY ]R0,\ IHCllU-AV-nKIDCES
CHAPTER XVIII.
WORKING-DRAWINGS.
I III
The first points to be determined before commencing a work-
ing-drawing are the scale and the size of the paper. The least
scale which it is convenient to use is one inch to the foot, and
the greatest scale for a whole drawing should seldom exceed an
inch and a half to the foot. If a smaller scale than one inch
be used, difficulty will be experienced in writing the rivet spacin"-
between the rivet holes. The width of the i)apcr should be from
three and a half to four and a half, or ever five feet : and, as
for the length, it is better to use roll-paper, and not to cut it
until the limits of the drawing be determined ; for it is a great
convenience to be able to make ajl the working-drawings for a
bridge upon a single sheet
The following is a draughtsman's equipment for making
working-drawings in a methodical and expeditious manner : a
table from four to five feet wide, from six to eight feet long,
and about three feet high ; a pair of steps each three or four
inches rise, and three feet long ; a bevelled steel straight-edge, at
least three feet long ; a beam compass with tangent screw attach-
ment ; a couple of small triangles (rubber ones are the best);
some four-H and six-H pencils ; a little tracing-paper ; a finely
divided duodecimal boxwood scale (the subdivisions being quar-
ters, eighths, and sixteenths); a good box of instruments, includ-
ing a protractor and a pair of hairspring dividers ; and the usual
outfit of rubbers, tiles, pens, etc., that one finds in draughts-
men's ofifices. T-squares, large triangles, and parallel rulers
should never be used in making a working-drawing. The first
can never be depended upon, because of the impossibility of
having both board and T-square always perfectly true ; no
ORDLVARV f/w.V HIGHWAV-BRIDGES. xy^^
wooden ruler can be relied on not to warp ; and parallel rulers
are a delusion.
I'or a few inches it is permissible to turn rioht angles with
truin-les, but for Ion- distances the beam compass should be
used ; and parallel lines can be most accurately drawn by erect-
in- a perpendicular near each end of the original line, and
laying oif on them equal distances. When distances are a little
too great for the triangles, and too small for the beam compass
the large ordmary compasses can be used ; but it will be founcl
that they are seldom required. The four-II pencils are to be
iise.l for writing dimensions, etc., and the si.x-H ones for draw-
ing I'lies. The draughtsman should always have at least one
ot the latter sharpened to a chisel edge for ruling, and another
to a point for sketching. He will find it to be greatly to his
advantage to keep his pencils always well sharpened, for an
error ot the width of a pencil-line will often cause a great deal
of inconvenience. A piece of emery paper or a fine file will be
ound useful for sharpening pencils. The tracing-paper will
be convenient in transferring drawings of similar chord heads
etc. : Its function is merely the .saving of a little time
It is generally better to have both a long and a short scale
The long one may be divided into feet only, the inches and frac-
tions of inches being taken from a diagonal or other small scale
If the draughtsman be not provided with a suitable scale he
can easily prepare a very fair one for himself on a strip ot the
roll of paper upon which the drawing is to be made.
The method of projecting one view of a piece from another
now will not do for working-drawings. owing to the liabilitv of
the triangles to slip. All measurements should be transferred
by the dividers ; and, if there be any probabilitv of the points of
the dividers having been moved, the distance between them
■should be tested by laying it off once more upon the original
length. There should be no more than a single transferrence
of any one distance, for errors often increase, instead of bal-
ancing.
The general arrangement of a working-drawing consists
merely in laying out a plan and elevation of one-half of the
span, leaving at least a foot of space at each end, and six or
a KH na fin
174
ORD/XAKV IROX HIGHWAY-BRIDGES.
1 i I J'i
itiii
I ■ . ,
Hi
eight inches above the elevation and below the plan, if there be
room to spare, with the same distance, or a little more, between.
As it is immaterial if different portions of the drawing cross
each other, provided that such intersection cause no conflictini,^
of the measurements, the various members may be shown in
several \iews alongside of their respective positions in plan and
elevation.
Thus the top chord may be represented in an under and an
upper view above the elevation of the truss, and the batter
brace may be shown in a similar manner above and to one side
of the elevation. Projections of the posts on planes transverse
to the bridge may be drawn alongside and a little below the
elevation of these members, the amount of lowering beini;-
sufficient to bring the ends of the strut clear of the chords.
Attached to the projections of the posts can be shown the inter-
mediate struts and vibration rods, with their connections ; antl
shortened views of the chord bars and diagonals can be placed
alongside their elevations in order to represent the heads clear
of all other members. Passing to the plan, on one side is drawn
the packed lower chord, and attached thereto the lower lateral
rods and struts in half-length ; while alongside the latter can be
represented an elevation of the same with the floor beams
beneath, and an end view of the beams near by. At the other
side of the plan, can be shown half-lengths of the upper lateral
rods and struts in two views, and a projection of the portal
bracing on the plane of the batter braces, and on planes at right
angles thereto. Each detail can be delineated to any required
extent in the neighborhood of its position in plan, elevation, or
both. If necessary, the panel points on one side of the plan
may be brought opposite the middle of the panels on the other
side, in order to avoid too much intersection.
This arrangement, although a good one, is by no means the
only one, and in some cases might not be the best. P'or instance,
in skew bridges it would be well to show the whole of the lower
lateral system in the plan, and the whole of the upper lateral
system above the elevation, in connection with the uppermost
view of the top chord, which should be the plan from above.
Then, again, if the bridge be a large one, the height may be so
OIWIXARV IKOX HlGHWAY-iiRllH-.ES.
•75
great that it will be impossible to show the plan below the eleva-
tion ; in which case it will be necessary either to make separate
fh-.uings for the plan and elevation, or to place one alongside of
the other on the same sheet. In making tracings of the work-
ing-drawing, the tracing-cloth can be shifted about so as to
group similar parts and so as to avoid too much intersection of
(liHerent portions.
i'rovided that any piece be .symmetrical about a plane cuttino-
It ill the middle of its length and at right angles thereto, it uiH
i)c sufhcient to show only one-half of the piece ; and the meas-
urement may be referred to the end of the member, to the
central plane, or to both. Where the same detail is used in more
places than one, it is not necessary to shc-A- it more than once
provided that it be exactly the same in every respect.
As an illustration of how to make a working-drawincr take
the case of the bridge treated in the last chapter, and .Assume
tliat the paper and table are each four and a half feet wide
Lsing the scale of an inch to the foot, the depth of the eleva-
tion will be two feet, and the width of the plan one foot four
mehes Allowing six inches above the elevation, and as much
inore between elevation and plan, will bring the lower side of
tne plan within two inches of the <t^Vr^c of the paper: this
arrangement will do very well. The first step is to draw a line
with the steel straight-edge, as nearly as possible, without takin-
t'- im.cli trouble, parallel to the length of the paper, and at a
distance of two feet si.x inches below the upper edge This
line should be very fine and perfectly straight. It can be made
so by prolonging it half the length of the straight-edge at a
time, and afterwards testing it in several places. On this line
take a ix.int a foot or more from the left-hand end of the paper
as the centre of the end lower chord pin. Lay off along this
hiu' with the greatest possible accuracy the panel length, until
the centre of the bridge be reached: in this case twenty feet
must be laid off four times. At the panel points erect short
!H rpendiculars with the triangles, and on the perpendicular at
the centre lay off the camber, which in this case is three inches
l-'^'c 1). 9). Had the bridge contained an odd number of panels
't would have been necessary to draw the middle panel, and
(II
f
I ■
176
oRp/xA/n- ih'ox iin-.nwA v-nRiDCEs.
lay (iff tilt' caniluT of tlirce intlics at each (MkI of this panel.
Thon, assumiiiL; iIk- ciirvc of the chord to he a parabohi, th ■
fall from the centre to any panel point is e(|ual to the camber at
the centre niulti])lie(l hy the s(|iiare of the ratio of the distance
of the panel point considereil from the middle of the span to
the half-lenji;th of span.
Thus in the case considered, the falls at the first, second, ainl
third panel points will be respectively 3(|)''^, 3(1)''^, and 3(|)''^, or
\X\ i|", and ,''y", makin<;- the hei^dits of these points above the
horizontal line respectively 3" — '•J^", 3" — i|", and 3" — ■,■*,", or
'A"' -i '• '''^'' -lu "' \^''i'<-'li distances are to be laiil out upon the
perpendiculars so as to locate the centri's of the lower chord pins.
The lenj;th of the panels as thus determined differ from those
of their horizontal projections by an inappreciable (piantity. If
there be any len^^thening of the chord, it may j^o against the
play of the i)ins in the eyes.
Ne.\t join the consecutive pin centres, producing them each
way a little more than a jianel length, so as to facilitate the
erection of perpendiculars thereto. Then at each of the differ-
ent centres erect a perpendicular to each centre line meetinj^
there, and bisect the angle between the perpendiculars : the
line of bisection will be the centre line of the post. Great care
must be exercised in turning these right angles with the beam
compasses, two points on each of the perpendiculars being
found, so that if these two points and the centre be iu e.\;Kt
line, the perpendicular may be relied on as correct. On eaih
of these centre lines lay off the depth of the truss, and complete
the skeleton diagram.
A partial check on the accuracy of the construction may be
had by measuring the panel length of the top chord, which
should agree with the length calculated as follows. Let
/ = the increase in tiie ])ancl lengUi of the top chord above that
of the bottom chord,
c = the cainher at the centre of the span,
s = length of span,
^/ = depth of truss,
and
« = number of panels.
OA'D/A'.i/^ y f/wx maim -../ j ■-nmnai.s. , ^y
Then, according to the method ^ivc. in Trautwino's « Pocket-
]^ook/> =-ri. vvhere ./ and . may he measured in ^cct. and c
andM. inchc. The panel length of the top chord will then
Tl,r- {' '' " '''' '^'■•"^■' '^"^^^'^ "f ^he bottom chord
Ih.s s not a certain proof of the accuracy of the vvo,V T vo
consecut.vc post centre hnes might he ec uaily n i td Z
l>c.r correct positions, and on the same side though is u
.c sLnvn ,n the next panel. A certain check mus' be obt
ujuai to each othei. and agree with tluit found by the formula
^=v/'^^-f(/4-^y,
wlitTc /; is the length rcoiihcd
l-r <loi,bIc-intcTsc.cti„n hridKcs, the Icgth of the long clh™
. s can be fot,„„ by the nu-thod given in^Ap,.™, .f " ^
u„ h of the .hagonal as „,an„fact„red sb.m ,1 be one si tv
latnl length by about a thirty-second of an inch
tcNsnin member show the hcnrl^ ult). h • ■• ^.'"^ ^'^ •-^^^''
^^^^^^ ^n the length from c'entre to centre, as shown on
"iHdRier be more convenient, draw out the heads fnllM
wi: '," "" '"^ "'""• ' '"■•' -■ b- '"one titho c,,:, , •
. inoMded that both p„,s and heads diminish to..ether
' "■ hammered heads the method of eons.rne.ion is «ry sim-
Ifililt
I'
178
ORDhXAKy /A'OA ///u Jill' A V-nK/DGES.
pic. It consists in describing, as in Fig. i of the accompanying
diagrams, a circle of radius C/i, equal to that of the pin hole,
and a portion of ai.other circle with a radius CB, equal to that
of the pin hole plus the product of one-
half the depth of the bar HK by the
ratio given in the table on p. 20 ; then
drawing the lines DE and FG parallel tc
the sides of the bar, and at a distance
therefrom equal to CB; and with C as a
centre and a radius CD, equal to t>vice
CB, describing an arc to intersect /;/:'
and FG in the points D and F; finally,
with D and /^as centres, and radii equal
to CB, describing the arcs HL and KM,
tansrent to the sides of the bar at //and
K, and to the outer circle at L and J/.
For welded heads the construction is
as shown in Mg. 2, where the pin hole
and bar are laid out as before. The dis-
tance AB is equal to one-half of UK multiplied by the ratio given
in the table on p. 20 ; and the distance SO is equal to UK, or the
diameter of the pin hole, whichever be the greater. The cen-
tres P and R of the arcs OBL and O'I'M respectively are found
by trial ; then DE and FG are drawn parallel to tlie sides of the
bar at distances therefrom D// and FK, equal to one and seven-
tenths times I'B or KB: and with B and A' as centres, and
radii equal to two and seven-tenths times BB or A'/", or, what
is the same thing, e(|ual to D// plus J'B, arcs are descrihed
cutting /:>/•: in D, and FG in F; finally, with D and /•" as cen-
tres, and with radii equal to DN, arcs are drawn tangent to the
side, of the bar at // ami A', and to the arcs OFL and O'J'J/dt
L and J/ respectively.
These constructions, with slight modifications, are taken from
Trautwine's " Packet-Book."
Next show the iiosts and the attached sway bracing in two
projections with all tiieir details. There should be allowed a
clearance of about an eighth of an inch for the ends of the posts
inside of the chord. The positions for the stay plates should
s, are taken from
OKDIXAR ] • IROX J I hi nil -A J -HRHH; Es. , -jc,
be as close to the pin as possible, allowing a little elcarance for
the diagonals The proper positions can be ascertained from
the general elevation. The lattice bars should be close to the
stay plates : it will not be necessary to show more than a few
of them on each strut, the positions of the others beino- indi-
cated hy their centre lines, as shown on Plate VI This plate
contams a portion of a vorking-drawing for a model of t^he
bridge treated in the previous chapter. The small scale of
thrce-c|uarte.-s of an inch to the foot was chosen so as not to
make the model too large ; and the whole working-drawino- is
not gnen, because of the necessarily limited size of the pla^e *
I ho principal portions are represented ; so that one can, by
studying the plate closely, learn all that it is necessary to know
ni order to make working-drawings ; and students are recom-
mended to give this matter special attention.
Xext show in two projections the top chord and batter brace
u-.th all their details, and give several views of each connect-
.ng-p ate and other detail in the neighborhood of its position on
t e e evat.on. The joints in the channels and plate of the top
chord should be located three or four inches to that side of
each panel point which is farthest from the centre of the brid-^e
- tlKit t e pin holes shall be bored through a single piece, ami
thrnugh the thicker of the two abutting pieces At the hip
I'Hnt It IS of course unavoidable .o bore the pin hole through
the abutting end.s of the chord and batter-brace channel;.
.\cx pass to the plan, where the first thing to do is to draw
parallel to the original horizontal line of the elevation traces of
t.u. central vertical planes of the trusses and of the central
piano n the bridge, locating the panel points verv carefully, and
as nearly as possible vertically, below their corresponding posi-
■;'"^"" tl^e elevation. Then arrange the chord packTni on
<'nc sKle of the plan so as to make the bending-moments on the
Pms as small as possible without luu-ing anv of the chord bars
i"i I at too great an angle with the plane of the truss
a any of the panels have trussed bars, the trussing should
he here shown, and the spacing of the rivet holes for same in
Tliu scale lia^ been fuitlicr raluc.vl by the oiii'Taver
fit^SI'l
liiiii
1 80
ORDIXARY IROX HIGinVAY-BRIDGES,
the chord bars should be represented close to the plan of the
trussed bars. Near the packing should be drawn separate
views of the lower chord pins ; giving their number, cHanieter,
lengths between shoulders, diameters and lengths of reduced
ends, and the total lengths, also the sizes of the nuts.
At the right-hand end of the plan, show the lower latercl
struts, and complete drawings for the floor system, including
beams, beam hangers, beam-hanger plates, bolts, joists, etc.
Generally the floor beams will be all alike : so it will be suffi-
cient to represent half a beam. It may even do to show only
half of a lateral strut, although there are always several differ-
ent lengths of them in a bridge, provided that there be written
sufficient directions to enable the carpenters to frame all the
struts without possibility of error. In writing dimensions, etc.,
upon a working-drawing, it is immaterial from which direction
the writing be read ; that is, it may be read sidewise, upside
down, or in any direction most convenient to the draughtsman.
In making tracings, this matter can be rectified if it be thought
advisable. Full directions for the manufacturer should be writ-
ten on the drawing. On the rest of the plan, show the uj^pcr
lateral struts with their details ; all the lateral rods with their
turn buckles or sleeve nuts, and their eyes in two views ; the end
lower lateral strut with its details, and its connection to the
pedestal ; the whole of the portal bracing with its connections ;
the ornamental work ; and the name plates.
Finally, take the list of members, and go carefully over the
drawing with it ; seeing not only that each piece is represented,
but that there are sufficient measurements given to have it
manufactured.
The following additional directions and hints may be found
useful. Refer each group (if rivets to some local Hue, which is
itself referred to the end of the piece, or some other promiiunt
part. .Show a section of each member, and write the dinien-
sions of all channels, angles, Lbeams, etc., near the secti.ui.
Write along each piece its extreme length or lengths, its len-th
from centre to centre of eyes, and of what it is composed. The
ends of the two pieces of an adjustable rod should l)e separated
by at least three or four inches in the turn buckle or sleeve nut.
ORDLXARV IRON HIGHWAY-BRIDGES.
I8l
Mark what rivets are countersunk, and at which end. If the
scale of the drawing be large enough, the countersinking can
Ik thus represented: draw full parallel lines across the rivet
for countersinking on the upper side, dotted parallel lines for
Ciumtersinking on the lower side, and two sets of parallel lines
crossing each other at right angles for countersinking on both
sides. Be careful to always note how many rights and how
many lefts of each piece will be recjuired, when there arc both
riL;hts and lefts.
Do not forget to write conspicuously the scale or scales of
the drawing. Lay out all bevelled edges on an enlarged scale,
say from half to full size, and mark their dimensions along the
edges, referring all measurements to a transverse line through
some well-defined point, as the centre of the pin hole. The'se
measurements should be checked by calculation. The slight
bevels at the joints of the top chord should be treated with^as
much accuracy as the bevels at the hip joints ; but, as the bevel
is very slight, it will be legitimate to put it all on one of the
abutting ends, making the other a square cut.
The centre lines for lacing-bars on the under side of a strut
should be dotted. In laying out a long row of rivets — for in-
stance, lattice rivets, or those for the top plate of a chord or
batter brace — calculate the distance of some of the intermediate
rivet holes from one end of the strut. Lay out these holes, then
interpolate the others ; because, if the spacing be laid out con-
tinuously from one end with dividers, any error in the span of
the dividers will be multiplied by the number of times the dis-
tance is laid off.
After laying out a complete system of rivets for any member,
check by seeing that the sum of the distances between rivet
holes plus the distance of each end rivet from the end of the
nuinher is equal to the total length of the member. ]\Iake
duplicates of as many ])arls of the bridge as possible, even at
the expense of a small amount of iron, not only to save time in
draughting, but also in the shop, and to facilitate the work
in erection.
Arrange to have as few loose pieces for shipment as possible,
and mark on the drawing of each connecting-piece to what it is
1 82
ORDINARY IROX IIICIIW AY-BRIDGES.
to be attached, or if it 'va to be left loose. Thus the hip con-
necting-plates should be attachetl to either the chords or batter
braces, sometimes to both ; those of the top chord, to that por-
tion through which the pin hole is bored ; those for the upper
lateral struts should be left loose. If there be any reason to
fear rough handling of the iron in transit, it may be necessary
to send some of the connecting-plates separately ; but the more
loose pieces, the more field riveting, and the more field riveting,
the greater the erecting expenses, and the longer the time and
the greater the risk in raising the bridge.
Rivet spacing should be as regular as circumstances will per-
mit ; and all changes in spacing should be made suddenly, instead
of gradually, so as to facilitate the punching of the holes by
machine.
All measurements should be in feet, inches, and the following
vulgar fractions of inches ; viz., halves, quarters, eighths, six-
teenths, thirty-seconds, and sixty-fourths. Workmen do not
seem to understand decimals : so it is better not to use them.
Avoid also the use of the development method, as it is beyond
the comprehension of ordinary workmen.
The length of all main members should be measured on the
drawing, then checked by calculation.
When nuts are placed in a confined position, — for instance,
pin nuts in jaws, — care should be taken that there be ample
room for them to turn in ; as it is very awkward, and sometimes
impossible, to screw up a nut which is stationary, by turning
the pin. Nuts in confined positions may be turned by hammer-
ing them eccentrically.
Be careful to design no connection in such a manner that
there will be rivets that cannot be driven without incon-
venience. This remark is especially applicable to field riveting.
It must be borne in mind, that, no matter how carefully the
bill of iron was prepared, there will be many minor changes
found necessary in making the working-drawings ; but, as a
rule, such changes cannot materially affect the total weight of
iron in the bridge.
ORDINARY IRON HIGHWAY-BRIDGES.
I .S3
CHAPTER XIX.
ORDER BILLS AND SHIPl•L^fG BILLS.
asured on the
When there is neces.sity for haste in building a bridge, as
there generally is in America, time can be saved by sending a
partial order bill to the manufacturers before starting to make
the working-drawings, or after they drc partially pencilled.
Such preliminary order bills should include only those por-
tions which are termed in this treatise "Main Members," and
those details of the sizes of which the designer is certain ; for
instance, stay plates, pins, brackets, and the plates and angles
for built beams.
The length of the main members in the bill should be three-
quarters of an inch greater than will actually be required, in
order to allow for the dressing of rough ends ; and, should there
be any doubt in the designer's mind concerning the e.x-act length
of any piece, he should make the ordered length great enough
to cover any variation which there may be in the design.
Of course, where there are bevelled ends on a piece, the
extreme length plus the allowance for waste must be given.
Where a number of small pieces are to be cut from one large
piece, an extra allowance of length must be made to provide
for the waste in cutting, say from an ei-hth to a quarter of ;in
nich for each short length. After finishing the pencilling for
a working-drawing, the remainder of tlie preliminary order bill
may be made out and sent. It should be divided into the fol-
lowing groups, containing the measurements indicated : —
nmnncls
No.
Depth
Weight per fuMt
length
Kinishfil li;m;ih
f I I
r i '
184 ORDINARY IROX HICIIWAY-BRIDGES.
Ansles No. 'I'liickncss I IjCS-s \ \Vcinlit in;r fool Length 1' iniahed Icnj;!
I-hc,ims ' No. Depth I Weight per foot
Length - Finished length
Plate.
No. Thickness
Widih Length i Finished Icni^th
Eye bars
No. ' Thickness
Depth Depths of lie.ids
Length centre to
centre of eyes
Extren;e Icntilh
Adjustable
rods with
plain eyes
Diameter.
Short I'iece.
Long Piece.
No. : Rod Upset Ciame- j Length of
I end ' tcr pf j loop
I 1 eye
I.ength, Diame-
cenlrc of ter of
eye loeiid eye
Length of
loop
Ix'ngth,
centre nf
eye to end
Adjustable rods j
with bent eyes
No.
DiAMETKK.
Short Piece.
Long Piece.
Rod
Upset
end
Diameter
of eye
length, centre
of liend to end
Diameter I.eiigth, centre
of eye of bend to end
Pins
!
1
1 No.
]
Diameter.
Length between shoulders
Extreme length
Body
Reduced
ends
Rollers ' No.
I.ength between shoulders Kxtremc length
Any details which will not go into one of these groups will
be made of material that the- manufacturer keeps in stock ; for
instance, fillers, washers, nuts, turn buckles, sleeve nuts, orna-
h KiiiihheJ length
Finished length
Vini.shuti Icngtit
ExtrcTiiL' Ic-iiutli
I.ONC, PuiCE.
Length of Length,
ORDINARY IRON HIGHU 'A J '-n RIDGES. , 85
mental work, na.ne plates, bolts, and iron hand railing It
won d not be a bad idea for bridge companies to keep blank
.snn.lar to the foregoing, for preliminary order bills
1 ins should be ordered an eighth of an inch greater in diame
ten than requ.red in the bridge, so that they\.ay be t n^^^^^
clown and shoe plates and roller plates, one-sixteen h of an
inch thicker, to allow for planin- ^"
^IXrr"^' """"'•'^"' ^""™"--'>'' "^ '^-^ ^-^' fro-
No. pieces
Thickness
Width
Length
Kind of wood
]
I.ONG I'lIXE.
A ter the working-drawing is finished, there should be pre-
pa.cd to accompany it a final order bill, in which are to be
grouped all similar pieces, and all their details wh cl are
attached to them in the shop. The following groupin" vv 11
cover any case of an ordinary iron highway-bridge dlw"
according to the method of this treatise:— ^lesigned
lers Extreme length
TOP CHORD SECTIONS.
^Iiannels.
''"IM'lates
Lnver |il,iles .
^lay plates
Lattice bars .
I 'iriiic. ting-plates
No.
No.
No.
No.
No.
No.
Depth
Width
Width
Width
Width
Width
Weight per foot
Thickness |
Thickness i
Thickness
Thickness I
!
Thickness I
Finished length
Finished length
Finished length
Finished length
Length centre to centre of end
rivet holes
Finished length
BATTER KR.'VCES.
I'.xtreme length
Channels .
'l'»P plates
Cover-plates (hip)
^lay plates
Lattice bars .
Cnniierting-plates
•''liuc plates
No.
Depth
Weight per foot
No.
Width
Thickness
No.
Wi.lth
Thickness
No.
Width
Thickness
No.
Width
Thickness
No.
Wi.lth
Thickness
No.
Width
Thickness
Finished length
Finished length
Finished length
Finished length
Length centre tp centre of end
rivet holes.
Finished length
Finished length
1 86
ORDINARY IRON HIGHWAY-BRIDGES.
CHANNEL BOTTOM CHORDS.
Channels
No.
Depth
Weight per foot
Finished length
Stay plates ....
I,acing-bars ....
No.
Width
Thickness
Finished length
No.
Width
Thickness
Finished length
Ke-enforcing plates
No.
Width
Thickness
Finished length
Connecting chord heads .
No.
Depth
Thickness
Length centre of eye lo end,
and extreme length
POSTS.
Channels
1 No.
Depth
Weight per foot
Finished length
Stay plates ....
1 No.
Width
Thickness
Finished length
Lattice bars ....
] No.
Width
Thickness
Finished length
1 No.
Width
Thickness
Finished length
Re-enforcing plates .
1 No.
Width
Thickness
Finished length
Channels .
Stay plates
Lacing-bars
Jaw plates
UPPER LATERAL STRUTS.
No.
No.
No.
No.
Depth
Width
Width
Width
Weight per foot
Thickness
Thickness
Thickness
Finished length
Finished length
Finished length
Finished length
END LOWER LATERAL STRUTS.
Channels . . . . •
I-beams
Angle irons ....
Stay plates ....
Lacing-bars ....
Jaw plates
No.
No.
No.
No.
No.
No.
Depth
Depth
Legs
Width
Width
Width
Weight per foot
Weight per foot
Weight per foot
Thickness
Thickness
Thickness
Finished length
Finished length
Finished length
Finished length
Finished length
Finished Icngdi
PORTAL
STRUTS.
Channels
No.
Depth
Weight per foot
Finished length
Stay plates ....
No.
No.
Width
Width
Thickness
Thickness
Finished length
Finished length
law plates ....
No.
Width
Thickness
Finished length
Connecting- plate to batter-
hrace
No.
Width
Thickness
l.ength of each leg
Connecting-plate for brackets
to channels ....
No.
W: 'ih
Thickness
Finished length
Connecting- plate for name
plates to channels
No.
Width
Thickness
Finished length
^GES.
Finished length
Kiiiisheil lenylh
Finished length
Finished length
th centre of eye Id eml,
and extreme length
C'h;ninels,
I'l.it bars .
O/iDLYAJn' I/W.V HIGHlVAY-niUDGES.
■STIFFKNKI) mr VERTICALS.
Si;iy plates . .
I.,irnij,'-l)ars .
Kctiiforcing plates.
'Inissing.
187
No.
Depth
No.
Width
No.
Width
No.
Width
No.
Width
No.
Width
Weight |)er foot
'I'hickness
Thickness
Thickness
Thickness
Thickness
Finished length
Length centre to centre (if eyes,
and extreme leti^th
Finished length
Finished length
Finished length
Finished length
Finished length
Finished length
Finished length
Finished length
Finished length
Finished length
Finished length
Finished length
Finished length
Finished length
Finished length
Finished length
Finished length
Finished length
Finished length
Finished length
Finished length
Finished length
Finished length
Length of etch leg
Finished length
Finished length
INTER.MEDIATE .STRUTS.
I-hiMins ,
t L' liiig-plales .
No. Depth
No. Width
Weight per fnot
Thickness
Finished length
I.engihofeach leg
MAIN DIAGONALS AND PLAIN CHORD BAR.S.
Nil- Bepth Thickness
Depth of
heads
Thickness 1 Di.atneter of ' Length centre to F.x.n
of heads
eyes
centre of eyes length
HIP VERTICALS AND COUXTER.S.
No.
Sectio
Diameter of en- Lengths of loop
larged end eyes
Lengths centre of eyes to ends, or centre
of eye to centre of eye
LATERAL AND VIBRATION RODS.
No. ' Diam, ' Diameter of U-iigth centre of eye
enlarged end to hend or ioop
Ungth centre of bend or | Length centre of bend or
••■ye to end of short piece | eye to end of long piece
STRUT.S OF TRUS.SED CHORD BARS.
No. of
Sectii
Sizes of
heads
Section of Ungth of Ungth of strn, cen- | Extre.ne length
'"■ssmg I trnssing ' tre to centre of eye of stmt
SIDE nRACING.
^''i. .Scctit
•Size of connecting-plate
Extreme length of brace
IRON HAND RAILING.
No. of posts I Si.es of posts No. of panels I SiVeofp.anel
panel Total length of railing
1 88
Plates
Angles
ORDINARY IROX HIGHWAY-BRIDGES.
nUILT FLOOR BEAMS.
No.
No.
Wi.lth
l-etjs
Thickness
Weight per foot
Finished length
Finished lenglh
1
III', !
lilies
Angles
No.
No.
TRUSSED FLOOR ItKAMS.
I-lie.inis .
Angles .
I'hles .
No.
1 No.
1 No.
1 tepth
I.e«s
Width
Weight per f.ioi Finished length
Weight per fmit | Finished length
Thickness | Finished length
ROLLER AND BED PLATES.
No.
No.
Width
Legs
Finished Thickness
Weight per f(X)t
NAME PLATES.
OTHKK SEPARATE PLATES.
Width
Di.imcter
Thickness
PIXS AND THEIR NIT'--.
Size of nuts
Finished length
Finished length
No.
Dntc.
Finished length
length under head, or extreme leii;;tli
No. Diameter
.Angles .
Channels .
Tee-iron .
No.
No.
No.
BOLTS AND THEIR NUTS.
Size of nuts length under head, or extreme length
BRACKETS.
Legs
Depth
I-egs
Weight per font
Weight per foot
Weight per foot
ORNAMENTAL WORK.
No. of pieces
Description
Extreme length
Kxtreme length
I'.xtrcme length
1
Finished length
Kinislied length
ORDINARY IRON NIGI/IVA V-BRIDGES.
HF.AM IIANOKKS AM) TIIKIR NUTS.
189
N.i. Section
I
Diameter of I Diameter Siie of nuts anil
upset end of eye lockiiuis
No. of nuts and
lock-nuts
Length of one Itg
Finished length
Finished length
Finished length
Finished length
Finished length
KnllclS .
( rii^s-rttcls
>i.k-ii,irs .
No.
SKTS ()[• KOLJ.KUS.
No.
No.
No.
Diameter
Iliametcr
Thickness
Length hc-iwecn shoulders
Length hclwecn shoulders
Width
FILLKRS rOK PINS.
FAternal diameter
Internal diameter
TURN nUCKLF.S A\n SI.KKVK NUTS,
No.
Tap«
Kxtreme length
F.xtrenie length
Kxtreme length
Length
:
F'inished length
I'Lilcs .
(Ilannels,
No.
No.
JAWS.
Width
Depth
Thickness
Weiglit per foot
Extreme length
lixtrenie length
head, or extreme len;;lli
r head, or extreme length
Extreme length
Extreme length
r.xtreine length
No.
Diameter
WASIIKRS.
Diameter
Diameter of bolts
SEPARATE RIVETS.
length under he.ad]
Kind of head Position in bridge j Parts connected
PIN PILOTS.
External diameter
Internal diameter
Some companies send also a complete bill of rivets to be used
in the shop ; but this is scarcely necessary, as it is more properly
the place of the manufacturer to prepare such a bill.
190 ONn/XAKV INOX HIGIin'AV-liKIlH'.ES.
The following form will be needed for the purpose : —
RIVKTS.
MemlMir
No, ni.inicter (.oiiKlli between IkmcIs
1
Kiiiil of heads I'arls tonnectcil
An allowance of three per cent should be made for waste in
shop rivi *s, and from ten to twelve per cent in field rivets.
If the hip verticals he Hat bars, they are to be transferred to
the group of "Main Diagonals, etc." The posts, chord bars,
and diagonals of trussed beams, are included under the general
heads of " Posts," etc.
The corresponding form of " Shipping Bill " is as follows : —
*>!
STRUTS.
Menilier
No. 1 Len>;th ccnlrc to end, ()r extreme len^jth
M.irk
BARS.
Member No. Section Diameter of eyes Size,s of heads Length centre to centre of eyes ; .Mark
Rons.
Member
No,
i
Diameter
Diameter of
eyes
Diameter of 1 Threads \ l^"gth cemre of eye
upset ends : R. or L. , '" ^■"''- '"■ ^'=""-'= "^
eye lo centre of eye
Mark
No.
SIDE BRACING.
No. 1 .Section
K,\treme length Mark
IRON HAND-RAILING.
No. of posts
No. of panels
Mark, ii'aiy
FLOOR-BEAMS.
Extreme length
Mark
I I'jrts conncctcil
\(.\e for waste in
field rivets.
)e transferred to
osts, chord bars,
nder the genera!
is as follows : —
; lo centre of eyes j Mark (
ih centre of eye
rrti, or centre of
lo centre of eye
ORDINARY IRON HIGHWA Y~BRIDGES.
ROI,I.KK AND men I'l ATES.
191
No.
Toniiion (fixed or free cnfl)
M.irk, if any I
NAME PI.ATKS.
c
No.
Dtite
OTHER SEPARATE PLATES.
Position
M:irk
PINS AND THEIR NUT.S.
Nil. ■ Uiamcter
Length between shoirlclers
F.xtreme length
dimensions of end* Mark
nOLTS AND THEIR NUTS.
I'iameter
ni.-,meter of upset ends , Length inrdcr head, or extreme length
:
URACKETS.
Position
Kxtreme length
Mark
:
ORNAMENTAL WORK.
No. of pieces
Description
Mark
BEAM HANGERS AND THEIR NUTS.
^''). Diameter of eye
No. of nuts and lock-nuts
Mark
ROLLERS.
No. of sets
1 1
,1
<
1!
'.\i
'
i' ,
' i
1 1
ii i
\ "
fiji
192
ORDIXA R J • IROX lUClIW '.1 1 -BRIDGES.
FIl.I.KKS rOR IMXP.
No.
External ilhuiictcr I Inlcrnal ilianicler
I^iiRth
Mark
TURN l!L'CKI.i:S AND SI.KKVl-: NUl'S.
No.
Taps
JAWS.
No.
INisilion
Mark
WASIIKRS.
No.
1 >ianiLtcr
niamclcr of bolt
SI".r.\R.\TK RIVr.TS.
No. I Diameter I I.eiiRlh umler head Kind of head i Position in liiidge | Parts conneuted
PIN IMI.OTS.
No. j l-'..\lernal di.unelcr
Intern, d diameter
.Mark
Tlie followinj,^ is the system of maikini;- iron before shipment
which the author would recommend. It should be thoroughly
comprehended by the manufacturer, the foreman i.i chari^e of
ert'ction, and the time-keeper or clerk, if there be either em-
ploved on the work.
Where the work is very extensive, the time-keeper generally
checks the material as it arrives on the ,i;round.
l'"irst, if there be more than one span, each piece of each
span should be marked with a daub of color peculiar to that
span : thus the first span may be white, the second yellow, the
third bl-'c, etc. ; care being taken to choose such colors as will
be readily distinguished upon the iron-work.
The colors may be marked in the last column of each divisimi
'JOES.
OJWlXAA^y /A'OX Uniinr AY-BRIDGES.
I/Onslh Mark
Mark
meter of bolt
ridge i Parts connecttd
Mark
l)cforc .shipment
lid be thoroui;hly
lan i.i charge of
re be either eiii-
-kecper generally
1.
ch piece of each
peculiar to that
jcond yellow, the
ich colors as will
n of each division
1
t
I ' I
,94 ORDLWIKV IRON HIGHIVAV-RRIDGES.
Chord bars to be marked i A, i B, i C, 2 A, 2 B, 2 C, -tc. ;
the numbers corresponding to those on the diagram, and the
letters denoting the position in the panel, A being for those on
the exterior side of the truss, B for those next to the outside, etc.-
Side braces to be numbered to correspond to the panel points
to which they belong, and to be marked R. or L.
Iron hand railing rccjuires no marks except E on the end
posts and panels, if these be different in any respect from the
others.
Floor beams to be numbered to correspond to the panel
]-)C)ints.
Roller and bed plates to be marked R. or L., if there be any
difference.
Name plates require no marks.
Separate plates to be numbered so as to correspond to the
panel points to which they belong, and to be marked R. or I...
if necessary.
Lower chord pins to be marked L. o, L. i, L. 2, etc. ; the
numbers corresponding to those of the panel points.
Upper chord pins to be marked U. i, U. 2, U. 3, etc.; the
numbers corresponding to those of the panel points.
Portal diagonal pins to be marked P.
Vibration-rod pins to be marked V.
Pins at middle of posts to be marked I\I. i, M. 2, M. 3, etc.;
the numbers corresponding to those of the posts.
Lower lateral-rod pins not to be marked, for they should be
shipped attached to the jaws.
Bolts need no mark, but should be boxed before shipment.
Brackets to be marked P. or L (portal or intermediate), also
R. or L.
Ornamental work to be marked R. or L.
Beam hangers to be numbered so as to correspond to the
panel points to which they belong.
Rollers need no marks. , • , ,
Fillers to be marked the same as the pins to which they
'^Tur^'n buckles and sleeve nuts, being attached to the rods
before shipment, require no marks.
)ond to the panel
L., if there be any
OliD/A'ARV //W.y niGHlVA J --BRIDC.ES. , 95
Jaws to be numbered to correspond to the panel points
Vashers need no marks : they should be boxed, or strung on
bolls, betore shipment.
Rivets need no marks, but should be boxed
r.lot nuts need no marks, as there are so few of them required
In addmo,. to these marks, there should be others for those
nK;.nbcrs wh.ch are to be riveted together in the field, and
ulmh are assembled in the shop when the rivet holes pre-
v.ously punched are reamed. These marks should be punched
■nto the n.)n with a steel point, and should consist of one, two
three or four dots upon each of the pieces so assembl d, in
Oder that no piece during erection will be put into the wrmig
correspond to the
i
fr^
w %\
^
'
i
j ,-
1
■
1 >
196
ORDhX^lRV IRON HIGHWAY-BRIDGES.
In
il ■' ' ■
;
11 ■
1
. 1
J
CHAPTER XX.
ERECTION AND MAINTENANCE.
The number of men required to erect an iron highway-brid<];e
will vary from half a dozen to sixty, or even more, according to
the length of span, width of roadway, location, and the time
to be occupied in erection.
For any one bridge, there is a certain number of men which
will be more economical than any other number ; and it is only
experience which will enable one to tell beforehand what this
number is. "
If there are too few hands, the work will lag, and difficulty
will be experienced in handling heavy pieces : on the other
hand, if there are too many men, the travelling expenses, and
the time spent in travelling by the extra men, will be wasted,
and the total amount of effective work tlone by each man per
day will be less.
If, for any reason, there be need for haste, it will be economical
to have a large force of men, notwithstanding the last-mentioned
consideration. For raising ordinary county bridges, the author
would recommend the following numbers of men in a gang : io\-
pony truss-bridges, six men ; for through-spans not exceeding
eighty feet, seven men ; from eighty to one hundred feet, ei-ht
men ; from one hundred to one hundred and twenty-five feet,
nine or ten men ; from one hundred and twenty-five to one
hundred and fifty feet, eleven or twelve men ; from one hundred
and fifty to one hundred and seventy-five feet, thirteen or four-
teen men ; from one hundred and seventy-five to two hundred
feet, fifteen or sixteen men; from two hundred to two hun-
dred and fifty feet, from sixteen to twenty-four men ; and, from
two hundred and fifty to three hundred feet, from twenty-four
ORDINARY IRON HIGHWAY-BRIDGES. 197
to thirty-six men. The long spans require a proportionately
greater number of men, on account of the heavy sections For
the same reason, the numbers given should be increased, if the
bridge be wider than the ordinary size. For city bridges, which
arc proportioned for heavy loads and for smaller intensities of
working-stresses, the numbers should be increased from ten to
twenty per cent. When great haste is necessary, the numbers
.should ])e doubled.
The most economical number of men will depend, too, upon
their skill ; for green hands work at a great disadvantage in
brulge-raising. They do not know how to use their stren-th
and require the foreman to stand over them to show them how
to <!.. their work ; besides, they are often so light-headed as to
be unable to work aloft. Sailors make excellent bridge-men
on account of both their agility and their training, which has
taii-ht them to do in a few minutes many a difificult little piece
of work that ordinary hands would puzzle over for hours
It IS necessary to have a few experienced men in every o-an- •
the more of them, the better, provided that their travelliito^
expenses, and wages when travelling, do not render their
employment too expensive.
The cost of raising a bridge depends more upon the foreman
than upon the men. The best men will fail to do their full
quota of work if the foreman be not energetic. Nor does it
suKice to have simply a good worker for a foreman : he must
know iiow to keep the gang busy, or they will stand by and
look on, while he does all the work. He should also have their
K<HH u-,11, or the progress of the work will be unsatisfactory
I he outfit for a gang to raise ordinary county bridges should
be as follows : —
■ forge, 2 pairs of tongs, 2 button setts for each size of rivets
5 ^In't-l'ins of each necessary size, 2 handle cold chisels, i
aiullc drift p.n, 12 cape chisels, 6 plain chisels, 3 wrenches for
\ nut.s, 3 wrenches for |" nuts, 2 riveting-hammers, i lio-ht
^loc Rc, r heavy sledge, 4 hand lines |" diameter, 4 guy lines
> diameter by 130' long, 2 fall lines l" diameter by no'lon-^
6 to lorope sling.s, 2 sets 8" blocks. 2 snatch blocks, 5 steel
I
198
ORDINARY IRON HIGHWAY-BRIDGES.
crowbars, 3 cross-cut saws, 2 augers i" diameter, 2 augers
I" diameter, 4 augers f" diameter, 3 axes, 2 adzes, 8 timber
trucks, 4 monkey wrenches, 4 chains, 2 crabs, 2 holding-on bars,
3 jack screws, several large wrenches for pins, and, if neces-
sary, a pile-driver with its appurtenances. The ordinary weight
of a pile-driver hammer varies from sixteen hundred to two
thousand pounds ; and the height of the driver is about thirty
feet. The cost for such an apparatus complete is about two
hundred or two hundred and twenty-five dollars.
If the gang be a large one, or if the span exceed one hundred
and fifty feet in length, the numbers of some of the tools on the
list will h.;ve to be increased ; for instance, those of the bars,
ropes, and timber trucks.
Bridge carpenters generally carry tools of their own : so, if
there be much timber work in connection with the bridge, it
will be sufficient to employ more carpenters, and not to pur-
chase a larger outfit of carpenters' tools.
In getting ready to 'erect a bridge, the first step is to prepare
the ground in the neighborhood of the site, so that there will
be room to store the material and for the men to work. When
the iron is received at the site, it should be checked, and niiy
pieces from which the marks have been obliterated should he
re-marked. The iron should be piled systematically, similar
parts being grouped ; and no iron should be allowed to lie uix n
the ground. It should be piled so that there will be no trouhic
in getting at any piece which may be required ; and the parts
to be used first should be placed nearest the bridge site.
The piers and abutments will be supposed to be erected, as
this work does not aim to treat of foundations.
The next step is to put the falsework in place. If the bed of
the stream be dry, or nearly so, the bottom hard, the distance
from the bed to the lower chord less than eighteen feet ; and if
there be no danger of a sudden rise of water with a swift cur-
rent, the floor and joists can be used for falsework.
If the distance from the bed of the stream to the bottom
chord be greater than eighteen feet, and the other conditions
be the same, timber bents on mud-sills will be required. The
size of a mud-sill should vary from 6" by 6" to 1 2" by 1 2", accord
to be erectc(l, as
ORDINAR V IROX HIGH II VI V-BRHJGES. 1 99
in- to the hardness of the ffround, the weight upon the sill, and
the height of the falsework. It is not necessary that the tim-
bers be square. For ground not especially hard, wide timbers
lai.l on their flats are preferable, because they distribute the
])ri'ssure better.
If there be but one tier per bent, two posts will be enough,
when the width of roadway does not exceed si.xteen feet. Tiicsc-
posts should batter about one inch to the foot, and should be
cn\ereil by a cap about 6" by 6" or 8" by 8", long enough to i^-o-
jcet two feet beyond each truss. The upper ends of the po^ts
should lie directly under the trus'ses, and the caps should be
(hift-bolted thereto, i; the roadway exceed sixteen feet, there
should be an intermediate vertical post. The bent should be
braced by diagonal flat timbers, say from 2" by 6" to 3" b)- 8",
according to their length, running in opposite directions, one on
each side of the bent, and bolted or spiked to the posts and cap.
If there be two tiers in a bent, the inclined posts should
batter two inches to the foot (or three inches if there be dan-er
"I High wind), and there should be a vertical post under eJch
miss. liach tier should be bracerl with diagonal timbers, as
before. The greater the danger of high wind, the more effec-
tively should each bent be braced. Alternate consecutive bents
should also be braced diagonally on their outer faces, and all
consecutive bents should be connected by longitudinal horizon-
tal planks well spiked to the caps. These planks will be useful,
in fact often necessary, for the workmen in passing from bent
to bent. If there be more than two tiers per bent, the batter
"1 the inclined po.sts should be three inches to the foot. A
,^o;k1 jieight for each tier is sixteen feet.
Where the bottom is soft, or where the water is deep and
I'lpid, piles will be required to rest the bents upon. There
should be from two to five piles per bent, according to the
width of the latter; a pile being placed below each vertical and
inclined post. These piles should be braced in the direction of
the stream by flat timbers bolted thereto. Any bracing that
mav he given them transversely to the stream shoukf^be at
such a distance above high-water level as to cause no obstruc-
tion to boats, trees, ice, or other floating objects.
Ji
200
Oh'D/A'ARV /RO\ llhillWAV-niilDGES,
If the bottom be bare rock, incaiKible of holdini; piles, the
nnid-sills must again be resortcil to. Tliey should be weighted
so that they may be sunk into place, then drift-bolted to tiie roi k.
This can be done without the aid of a diver. Of course the sills
must be firnily attached to the lower tier before being put do
Wl).
I'he lops of all piles should be cut oif to an exact level, sn
that, when the bents arc- erected, the ui)per surfaces of llu'
upper caps will lie in the same hori/ontal plane.
On these caps should be placed timber-beams stretching from
one bent to the ne.xt, and lying immediately under the trussis:
joists will answer the purpose. It is generally customary to
place the bents under the ])anel points ; but the author |)refers
to jiut them two feet to one side, so that the floor beams may ho
swung into place without taking down the falsework. This
method may, and probably will, recpiire an extra bent at one end
of the span; so, if the bents be expensive, it is better to put one
under each panel point, and remove the ui)i)er tiers before swimm-
ing the floor-beams. The level of the top of the longitudinal
beams should be at least six indies below the feet of the posts,
so as to permit of the use of camber blocks, like those shown
on Plate VII. The angle which the contiguous faces make with
the horizontal (less, of course, than the angle of friction ol the
wood) enables the untler block to be easily knocked out when
the span is to be swung.
The timbers for the caps and posts of the falsework are gen-
erally square, and the sizes for the latter are to be ft)und from
Table XXXIX., after the stresses in them have been ascer-
tained as
foil
ows
Let
\]\ = weight i)er foot of the iron-work of the l)ridge,
W., = average wci,L;lu per foot in lieiglit of one bent of falsework
and the tiniliers whose weij;lit it s\ii)i)orts,
p =: wind pressure i)er sijuare loot,
A = area per lineal fool which the two trusses ])resenl to tlio wind
(it is generally a!)0ut five or six scjuare feel),
A! — the average area subject to wind pressure per foot in height
on one bent, ami its share of longitudinal bracing,
/= i)anel length,
OA'D/NAJiV IRON niGHWAY-lUUiHil'US.
IS strctcliin<r fro
201
:mtl
then
.•„ c.,, c„ etc. = horizontal distance l)otu-ecn centre h'nes of inch-ned
posts niuasured along the caps,
rt'= dejUh of truss,
./,. ./,, d„ etc. = heights of the different tiers commencing at the top
A = vertical distance between centre of chonl and upper
cap of bent,
6 = the angle wliieh the inclined posts make with the ver-
tical ;
pA/= i)rossnre on trusses at each panel point,
/>/t'l/^ = i)ressiire on U])per tier,
/>A',/, == |)ressure on second tier from top,
/.'/V3 = pressure on third tier from top,
aii.l the stresses /'„ F,^, /r, etc., in the inclined posts of the
hrst, second, and third tiers respectively, will be Lnven bv
the equations, ^
L-.-'- + .
sec 6,
/; = c»v:c. + &c.
hcse formulas are obtained under the supposition that the
■nclincd posts are not aided by the vertical ones, which suppo-
■sition IS necessary in order to avoid anibi-uity : it would be
correct, were the falsework on the verge of overturning If
the tunber be green, the error thus made upon the side of
safety .spdvantageous ; but, if the timber be dry and of good
quality, ,t IS permissible to make a slight reduction in the size
K.vcn by Table XXXIX. In applying the table, find the size of
202
oRD/A'AJiy /A'OA' n/ami'Ay-jiR/ih,/:s.
'. its
scjiiarc timber rec|iiirc(l for a stress I\ and lenj^th ^/, sec 0, that
for a stress l'\ ami length d^ sec ^, etc., then take the greatest of
these sizes.
The vertical posts should be .strong enough to withstand a
working-stress given by the equation,
where // is the number of the tier considered, and S the stress
in the corresponding vertical post.
One dimension of the vertical posts should be the same as
the side of the square which is the .section of the inclined posts;
so that the diagonal braces may be flush with the entire faces
of the bents, and be bolted to the verticals without the inter-
vention of filling-pieces.
These equations seem very long, and no doubt many practical
bridge foremen would look upon them with disdain : neverthe-
less, if the falsework is to be designed by any other method
than that of guessing, this is the way in which it should he
done. The more elevated the bridge, the more important does
it be ome to properly proi)ortion the falsework. The values of
]Vi and A' will have to be assumed, or roughly calculated, before
applying the equations. The other quantities are, or shoiikl
be, known. The value of /> may be taken from ten to fifteen
pounds per square foot, unless the situation be mure than ordi-
narily exposed, when it may be taken at twenty pounds.
Bridge companies can afford to risk the chance of a hurricane
striking the bridge before it is swung.
The sections of the caps are generally made the same as
those of the inclined posts. The caps should be dapped to
receive both upper and lower ends of vertical and inclined
posts. The vertical posts should be drift-bolted through the
caps, the bolt being long enough to project five or si.x inches
into each post ; and the inclined posts should be held in place
by wooden splice pieces, one on each side of the bent, project-
ing above and below the cap, and fastened at each end by a
bolt passing through the two splice pieces and the post. This
attachment may be used for the vertical posts instead of the
OKJ)/\.tA'y /KOX HIGIlWAY-Iil^lDaES.
203
h to withstand a
and .S' the stress
drift bolts, if it bo preferred. For additional security against
slippin-, a third bolt may be put throu-h the splice pieces and
the cap; or cleats may be nailed to the latter above and below
at the toe of each inclineil post.
All bolt holes in timber should be accurately located and
bored before the falsework is erected. On this account the
bents should be all built after one pattern, so that the parts
may be interchangeable. If the bents be of different hei-hts
the variation may be effected in the lowest tiers. Holt.s* arc'
always preferable to spikes for connecting timbers, especially
when the falsework has to be taken down, and re-erected for
another span. Care should be taken to avoid any unnecessary
injury to the timber, in order that it may not be sold at too
tjreat a loss after the work is finished.
There should be at least two plank walks on top of the lower
falsework, exterior to the trusses, and a runway midway between,
formed of several joists set on edge for the purpose of brin-in-
out the material thereon upon timber trucks. '' '"^
The posts of the upi)er falsework should rest on the caps of
the lower falsework, a few inches inside of the trusses, unless
the i)ents are placed beneath the panel points, in which case
they should be placed two feet to one side : they should be
attached to the caps by splice timbers and cleats. The hei-ht
of the upper falsework should be such that the upper surfac'of
the caj) wdl be at least si.x inches below the under sides of the
upiK-r chord .sections, so as to pennit of the use of camber
i)l(ieks between.
The author would suggest that the end bents of upper false-
work be made three or four feet higher than the others, and the
use of four posts instead of two (one on the inside, and one on
tlie outside, of each truss), in order to aid in raising and holdino-
ui place the heavy batter braces. After the latter are put in
position, a horizontal timber may be firmly bolted to the bent at
the level of the other bent caps, for the temporary floorin- to
'■^'st upon. Stout beams stretching from bent to bent wil? be
icciu.red as fulcra for the levers by which the chord sections
a>e handled. The ui.per falsework should be braced by diao-o-
iKil timbers, both longitudinally and transversely. The sizes'of
J
204
()A'/)/A.iA'i- /A'ox ///(,// ii'.i r-/.7v'//n;/;.v.
the posts should tjencrally be about 6" by 6" : when the trusses
are hij;h and the chord sections heavy, it might be well to
increase the size to 7" by 7". The caps of the upper falsework
should be deeper than their breadth ; because they have to act
as beams, and may be subjected to considerable shock when
the chord sections are being put in place. The method of
bracing shown on Plate VII. is specially advantageous in this
respect.
In both upper and lower falsework, the diagonal bracing in
planes parallel to the axis of the bridge should, for economy's
sake, be placed between alternate pairs of bents ; tiiat is, every
other space between bents should be braced. The end spaces
shoulil, however, be braced in any case.
Plate \T1. gives an illustration of how the working-drawings
for falsework should be made. For economy of space, the
scale has been taken at an eighth of an inch to the foot ; but it
should, if intended for an actual case of framing, be four times
as great. A drawing of this kind should be accompanied by bills
of lumber and iron, prepared in a similar manner to that given
in Chapter XIV. for the span. Measurements of distances
between bolt holes should be both calculated and scaled.
Those on Plate VII. were simply scaled, as the plate is intended
for illustration only.
The foreman of the work should be provided with a blue
print of the working-drawings for the bridge, unless the type of
structure be one with which he is perfectly familiar. He must
also be provided with a " Raising Bill," which should consist of
a skeleton diagram of one truss, with the following information
written thereon : —
Size of each truss strut, and tie, and mark for same, also number of
pieces of same in a panel of one truss.
Diameters and lengths S. to S. of truss pins, with their marks.
Diameters, lengths, and marks of fillers for same.
Sizes and marks of all separate plates belonging to the trusses, each
in its proper position.
■ »'
.if
sr
O/W/A'.l/n- /A\hV niC.HUWV-lih'llH-.ES.
205
to the trusses, each
A (liafjram for the lower lateral system, giving the following
information : —
Sizes and marks of rods.
riisitions of same, showing which eyes arc to go next the trusses.
Sections, len},'ths, and marks of lateral struts.
Diameters and lengths of lateral pins, if any.
Diameters and lengths of fillers for same.
Si/.es and marks ol jaws, if there be any difference between them.
A diagram for the upper lateral system and portal bracing,
giving the following information : —
Sizes and marks of rods.
Positions of same, showing which eyes are to go next the trusses.
.Sections and marks of lateral and portal struts.
Diameters and icngtlis of jjortal pins.
Diameters and lengths of fillers for same.
1 )iameter and length under head of portal strut attaching bolts.
lie should also be provided with a plan of the bottom chord
packing (the transverse dimensions being exaggerated, so that
the .size of each piece may be written thereon), a bill of bolts,
giving the number and position of each kind, and a clear state-
ment of the system of marking the iron.
liefore starting to erect the bridge, the foreman should study
carefully all the plans, so that he will have a clear picture of
the bridge in his mind's eye, and will not have to be continually
referring to the drawings during the erection. On a work (If
any magnitude, there should be kept on hand a few standard
nuts of each size ordinarily used, so that the loss of a nut 01
two will cause no delay : for the same reason there should be a
tew extra bolts of each size.
The material, as a general rule, is all piled on one side of the
>trcam : the raising should therefore be commenced at the other
side, so that the passage of the material will not interfere with
the work. If there be no objection, the far end of the bridge
should be the fixed one, so as to start from something pernia-
nent ; but this is not absolutely necessary.
To illustrate the method of raising, take, for example, the
2o6
ORDINARY IRON HIGHWAV-nRIDGES.
iiHIl'
M
bridge treated in Chapter XVI., and assume that the founda-
tions, with their anchor liolts and falsework, are in place. The
first thing to be done is to lay out the centre line of the bridge
upon the falsework caps, marking it with a small-headed tack
on each cap, then the centre lines for the trusses in the same
way. This can be done either with a transit, or with a carpen-
ter's chalk-line ; care being taken to make the transverse
measurements to the outer lines exactly perpendicular to th«;
central line. A test of the accuracy of the perpendiculars can
be made by the three, four, and five method, using a tape-line.
Next, mark the exact positions of the panel points upon the
longitudinal beams under the trusses, and place the camber
blocks, levelling over them so as to make the lines joining the
central points of their upper surfaces parallel to the curve of
the chords. It is better to have the blocks a trifle high, say, an
eighth of an inch near the centre, and a sixteenth of an inch
near the ends.
Four small nails will hold each pair of camber blocks from
slipping during the work, and they can be left so as to bo
easily extracted before swinging the bridge. Next transfer the
centre lines of the trusses to the tops of the camber blocks, and
mark accurately the first panel points from the fixed end, then,
starting there, pack the chord bars of both chords. It might
be convenient to have a few hard-wood pins to fit the holes
pretty tightly, so as to aid in getting the bars properly placed
longitudinally.
After the chord packing has made some progress, run out the
two batter braces, and hoist them into place by means of pulleys
attached to the cap of the first bent of falsework, which bent
should have been previously guyed and braced so that it canmit
possibly be disturbed by the effect of the pulleys. As soon a.s
each batter brace is raised, and the anchor bolts pass through
the holes in the shoe plate, the nuts should be tightly screwed
down in order to aid in holding the batter brace in position.
It will not do, however, to rely solely on these, for the
threads of the end bolts might be stripped : consequently a
hard-wood supporting block must be strongly bolted to the two
adjoining posts of the bent of the upper falsework. This block
igress, run out the
ORDINARY IRON HIGHWAV-niUDGES. 207
Should have a bevelled ed-e, the angle of bevel bein- equal to
the slope of the batter brace, so that the iron-work will not rest
on a sharp edge of wood. If the lattice bars interfere with the
hcaruig, as they arc liable to do, rough notches can be cut in a
ninuite on the bevelled face so as to bring the bearing upon the
channels.
Meanwhile the end lower lateral strut, the portal struts, and
the portal and end lower lateral rods, having been run out, the
thiee struts are to be put into place ; the upper ones being re-
tained there by their connecting bolts, and the lower one by the
end pins, which should also pass through the chord bars, fillers,
and end lateral rods.
Such small portions of the structure as pins, fillers, and beam
hangers, should not be brought out upon the falsework until
required for use, for fear of their being lost overboard. Nothing
more will be said about running out these and other sniall por
tions. but it will be assumed that they will be at hand when
wanted. It should be an understood thing between the fore-
man and the men, that any one who drops any portion of the
hridge into the water forfeits a certain amount of his wages
.Such an arrangement will make green hands a little more care-
ful than they are apt to be generally.
As the portal rods are adjusted by turn buckles with sino-le
tap ends, they may be omitted until after the portal struts are
riveted to the batter-braces, because the riveters can then work
to better advantage. They can be left upon the abutment until
ret|iiired.
•Next run out, and hoist upon the falsework, by means of
pulleys attached thereto and timbers used as levers, the end
.sections of the top chords, working them into place by the
lovers, and attaching them temporarily at the hips by bolts,
puttnig in at the same time the end diagonals, but omitting the
liip verticals and fillers, so that room may be left for the hold-
m,-;-on bars. The other ends of the chord sections rest on the
(.amber blocks.
Next run out, and hoi.st into place, the first vertical posts,
Ivttmg the upper ends lie in the open ends of the chord sec-
tions.
?o.s
ORf^X.lR]- /NO.\ lin'.inVAY-BlUDGES.
m
Now start the rivet i;ani;- at work on tlie portal, and let them
follow up the work as it progresses, not leavinij the portal until
they have made the hip attachment, connected the portal struts,
and put the brackets and ornamental work in place.
Next briny; out the second sections of the top chords and the
second set of diagonals. Raise the chord sections into place,
as before, with pulleys and beam levers, holding them there
until temporary bolts are put into a few holes through the con-
necting-plates, filling-plates, and channel webs, and until the
pins are run through the posts, diagonals, and fillers. The latter,
in this case, will not interfere with the riveting.
Ne.xt run out and put into place, as before, the second pair of
posts ; then bring on the third sections of the chords, the third
set of main diagonals, and the first set of counters, putting all
three into place as before, and so on until the end of the bridge
is reached. Meanwhile the wooden lower lateral struts should
have been framed, and the jaws attached to their end's.
Just before the riveters complete the riveting of the jiortal,
the first upper lateral and intermediate struts should be run
out, and bolted into place ; but the upper lateral and vibration
rods should be omitted, as they would be in the way of the
riveters, and can be readily inserted afterwards.
About the time that one-half the span is erected, commence
running out the lower lateral struts and rods, putting them into
place, inserting the hip verticals and fillers, and coupling the
lower chords into their final position, leaving the beam hangers
lying horizontally, so that, when the longiludinal supporting-
timbers are removed, they will drop into their proper places.
A little before the riveters reach the end of the span, the
upper lateral and vibration rods slK)uld be put into place, and
screwed up about the right amount.
When the end of the bridge is reached by the riveters, and
as soon as they have ri\eted the hip connection, and attache,',
the main diagonals and hip verticals, the last couplings of the
bottom chords can be made at the pedestals.
The shoes rest upon the rollers, which should have been put
in exactly transverse to the direction of the bridge, and blocked
so that they cannot move.
ORDIAARV IROX niGini-AV-BRIDGES. 209
The last connection for each truss can easily be made by
raising the h.p either with levers or by jack-screws, and either
pressing against the shoe with jack-screws abutting against
<,cks chained to the roller plate, or by attaching a ptir of
blocKS to the pedestal and first panel-point lower chord pin
After the final coupling has been made, and the riveting is
fin.shec knock out the upper chord camber blocks, so as to
bring a the weight of the upper part <,f the bridge upon the
posts ; then take down the upper falsework
Next knock out the camber blocks of the lower chords, lovvcr-
.n,^^them together gradually so as to bring no shock upon the
X.xt run out the first floor beam to the end of the bridge, and
rcn.ne the runway of the second panel, in order that the beam
nuiy be dropped between the lateral struts and lateral rods, and
swung into place, lowering it beneath the ends of the han-^ers
then raising it up. inserting the filling-plates, putting on%he
anger plates, and screwing up the nuts. lu this way attach
11 t c loor beams, seeing that the hanger nuts are screwed up
rnily but not to such an extent as to endanger stripping thL
'vads. 1 hen bolt all the wooden lateral struts to the iTeams
Iinuigh the holes previously bored, which holes should be at
Ic:.st a quarter of an inch greater than the diameter of the
X.xt screw up every adjustable rod to the proper tension,
u uh can be ascertained by the sound they make when tappec
"illi a hammer. a^^'-
Xcxt uash off any mud or other impurity that there maybe
ho in.n-woik. and give it two good coats of paint wherLer
he —sh will reach. The best kinds of paint to use are lead
-n s, when they can be obtained unadulterated; but they are
""" -^o'l. Iron oxide is a good paint, but requires more fre-
H^'-'t a-newal. The color should be such as to readily show any
M." of r..t : various shades of gray are efficient in L respect
•""1 'He at the same time pleasing to the eye
IlKrc remains nothing now to be done except to put on the
i-^S floor, hand railing, and felly plank, a matter'so simple
210
ORDINARY IRON IIIGIllVA V-BRIDGES.
that it is unnecessary to describe it here ; the only point worthy
of attention being, that the joists should be dapped one inch
on to the lateral struts, and that they should go on so hard that
it will be necessary to drive them into place. This can bo
accomplished by cutting each dap a sixteenth of an inch short,
and bevelling the end of one dap slightly, in order to give the
joists a start when they are being driven down. When they
come to their bearings, they should be spiked to the lateral
struts by a five-inch spike at each end, driven obliquely.
In regard to the flooring, Mr. James Owen, C.E., in a paper
read before the American Society of Civil Engineers, specifies
as follows : " Lay no plank wider than nine inches. This pre-
vents wide joints in shrinkage. Bore all holes for the spikes to
prevent splitting, and put no spike nearer than four inches
to the end of the planking.'^
In long bridges of several spans, it may be economical to dis-
pense with the upper falsework by using a travelling derrick,
running upon wooden stringers, for the purpose of handling the
heavy ''sections. Under these circumstances, the whole of
the portal might be connected while lying upon the falsework,
then hoisted into place in one piece, and supported there In-
shore timbers from the first bent of falsework. The brid-c
should be completed as the traveller retreats : otherwise there
will be difificulty in carrying the members past the traveller.
The material should be brought on cars within reach of the
derrick. , r , , ,
The last thing to be done is to take down the falsework, ami
draw the piles f"om the bed of the stream. The latter is easily
accomplished by a crab on the bridge ; the rope being attached
to the head of the pile, which is vibrated transversely ni all
directions while being lifted by the tension of the rope.
There is no reason why a well-designed iron highway-brul-e,
when properly cared f.-r, should n<.t last forever. Under loads
which are light and slowly moving, compared to those of rail-
road-bridges, the iron cannot possibly wear out ; and, when
properly protected from the weather, it cannot rust. Of course
the wooden parts of the structure must be replaced from time
to time as they wear out or decay.
ORDINAR V IRON HIGH W A V-B RIDGES. 2 \ r
When knots begin to project above the surface of the floor
they should be adzed off, both for the comfort of those drivin-'
over the bridge, and to prevent vibration. After half an inch
has been worn off one side of the planks, they should be turned
over; and when another half-inch has been worn off, or before
bcTqlced '"''"'^ ''''''' ''^"' °^ ''''^"''' ^^ ''"'">'' *^">' should
It would be well for county commissioners to buy all the
liunbcr needed for renewal a year before required for use so
that It may be well seasoned.
Iron bridges should be thoroughly inspected for rust spots at
least once a year; and. if any be found, the bridge should be
rcpauuccl One or two spots in places where something might
have rubbed off the paint may be touched up with a brush ; but
generally speakmg, when rust spots begin to appear, it show
that two good coats of paint are required Immediately
I he adjustable members should be tested occasionally by
tappu^g wth a hammer. This duty should not be intrusted to
an .gnorant workman, who will turn away on the nuts until he
s ears the thread or breaks the rod. . Whenever, in driving over
a bruise, any of th. iron-work rattles, it shows that something is
ou ;f fj-tmcnt. Generally speaking, a well-proportioned
H budge wdl not get out of adjustment unless some one
rit" ff ""'' " '"^" '"^''^^^- ^^'^h combination
bndge. It ,s a different matter, for the shrinkage of the wood
may loosjn the counters.
11!
'm
- ■' < •
APPENDIX L
A NEGLECTED CONSIDERATION IN HIGHWAY-BRIDGE
DESIGNING.
Sim: ciFicATioNs for highway-bridges generally call for strength
to resist a wind pressure of at least thirty pounds per square
foot of exposed surface ; but there are many such structures in
the United States whose trusses would not, unaid-^d, withstand
this pressure. Granting that the lateral rods are large enough,
that the upper lateral and portal struts have sufficient strength
to resist both direct thrust and bending, and even that the lower
lateral rod connection is all that could be desired, still the bridge
may be far from fulfilling the requirements, as the following
investigation will show : —
Let
and
then
/ = the assumed pressure per square foot,
A = the area in square feet per lineal foot of the vertical pro-
jection of that i)art of the structure lying below a hori-
zontal i)lane, whicli passes midway between the chords
of a through Pratt-truss bridge (the windward truss and
hand-rail are not supposed to slielter the leeward ones) ;
/// = IV = wind load per lineal foot for the lower lateral system when
the bridge is empty.
Let
^1 = the total area of bridge per lineal foot exposed to the wind
pressure,
// = the vertical distance of the centre of pressure above the
level of the bed-plate,
/ = the panel length,
"5
Ik
2l6
i\ •
I
I
■ '4
II
1
■'"i
\ > '
\ :
1
f
I:
and
APrKXDIX I.
b = clear width between trusses,
c z= width of one truss,
(/ = depth of trusses,
lV^ = dead load per lineal foot for one truss,
ly^ _ reduced dead load per lineal foot for the windward truss ;
then the overturning moment of the wind per lineal foot is /J,//,
and it has the same effect as that of a couple of lever-arm /; + ,-,
and force,
b-\-c'
that is, the weight per foot on the leeward truss is increased,
and that on the windward truss is decreased, by this amount,
which gives the equation,
n = number of panels in the bridge,
n = number of any panel, counting from the nearest end of
the span ;
Let
and
then
and
IV/ = panel wind load,
IV.,/ — reduced panel dead load.
The compression on the windward bottom chord of the «/*
panel will be
^{n-n^lV-^,
if we consider that the inclination of a lateral rod to a line per-
pendicular to the planes of the trusses is tan - 1 ^. The tension
in the same panel, due to the reduced dead load alone, is
except in the case of the first panel, to find the stress for which
//j must be made equal to two.
APPENDIX /.
the windward truss ;
m the nearest end of
m chord of the nC"
ral rod to a line pcr-
in ~ ^ T- The tension
load alone, is
: the stress for which
217
Now, if this tension be less than the compression just found
tlic chord at the panel considered, if not a compression member'
or If It be not externally aided, will buckle ; for flat bars cannot
ho .died upon, when acting separately, to resist compression
Ihe following inequality should, therefore, hold true : —
{n, - !)(« _ n, + I) J^-'> „.(« _ n,)^^^.
H) inspecting the chord stresses in a few Pratt truss through
i.ndges. It can be readily seen, that, if this inequality hold true
for the second panel, it will hold true for all the others
The three following cases are fair samples of bridges with
wiiKh the author has met in his practice. The wind pressure
assumed is thirty pounds per square foot.
('^ A 140' span of 12' clear roadway is 23' deep, consists of
seven panels, weighs 460 pounds per lineal foot, presents to the
wind about SIX square feet of surface below the middle horizontal
plane for every lineal foot, and about eight and a half square
feet above and below. The centre of pressure is about 8 feet
alx.ve the shoe plate, and the width of the truss is i foot
These data give W^ = 73, and, for the second panel,
W„
and
(«i-0(«-«, + i)7=xg.
W
«i(« - «i)-, = 150.
(2) A 150 span of 14' clear roadway is 24' deep, consists of
cigh panels, weighs 540 pounds per lineal foot, presents to the
wuK about six and a half square feet of surface per lineal foot
lor the lower lateral system, and about nine square feet above
and below. The centre of pressure is about 8| feet above the
shoe plate, and the width of the truss is about i foot
1 hese data give \\\ =117, and, for the second panel,
and '^
n^\n — «i)-j = 167.1.
ft
i8
APPENDIX /.
(x\ A 1 20' span of 16' clear roadway is 22' deep, consists of
six panels, weighs 530 pounds per lineal foot, and presents the
same surface per lineal foot as in the last case. The centre u
pressure is about 7-1 feet above the shoe plate, and the width
of the truss is I foot.
These data give W^ = 146, and, for the second panel,
(«, - i)(«
and
VV
tiiin - tii)-j = 97-5-
In all these cases ^
(«, - i)(« - «j + ^)-f < «i(« - «i)t'
How is it, then, that more bridges do not fail by the bucklins
of the bottom chord under wind pressure ? For two reasons.
First, the probability of a bridge ever being subjected to a
pressure of thirty pounds per square foot over its whole length
is very small ; and, second, that in a well-built bridge, where the
joists arc dapped to the floor beams, the joists would take up
the compression that would tend to buckle any panel of the
chord except the first. , . , , i
In view of the fact of the small chance that a bridge has ol
ever being subjected to the assumed pressure, it would be legiti-
mate to trust somewhat to the stiffness of the joists in cases
where ^ ry
(«, - i)(« - «, 4- i) ^/' < «i(« - «i)T'
and not to make the chords stiffened throughout, except in short
'Ti^, as the joists cannot stiffen the end panels, the chords in
these panels should be proportioned to resist the compression
due to the difference between the longitudinal component of tht
greatest stress in the end lateral rod, including the initial ten-
sion, and the reduced dead-load stress, whenever the former .s
in excess of the latter. It is often well, for the sake of hot
rigidity and appearance, to stiffen the chords in the second
panels when those in the first panels are stiffened.
APPENDIX I/.
219
APPENDIX II.
hout, except in short
and
DEMONSTRATION OF FORMULA FOR FLOOR BEAMS.
Let the notation be the same as given on p. 19, viz. : —
A ^ = area of bottom flange in square inches,
A' — area of web in stiiiare inches,
A" = area lost by a rivet hole in square inches,
ly = the uniformly distributed load in tons,
Z = length of beam in feet between centres of supports,
/? - depth in feet between centres of gravity of flanges,'
T = intensity of working tensile stress in tons.
The moment at the centre of the beam is ^^. Let us take
the centre of moments at the middle of the web, which will
correspond w.th the neutral surface, if we assume, which is
nearly true, that the upper and lower flanges are of the same
area, and are subjected to numerically equal stresses
The moment of the load is resisted by the sum of che moments '
of the flange stresses and those of the web stresses. The sum of
the moments of the flange stresses is
2{A-A")Tx~={A-A")TD.
^ J^hej-esisting-moment of the web stresses is found as fol-
The resisting-intensity of stress on the fibre most remote
rom the neutral surface may be taken equal to T; then that
for any fibre ^^ the distance .r will be, by the common theory
of flexure, -^f. The stress on an elementary area at this
:'A
]
1
gives, for the total resisting-moment of the web,
D
'^7>-=f[(?y- (-?)']=
Equating-moments gives
APPENDIX II.
distance will then be ~bdx, where b and D' are respectively
the width and depth of the web. The moment of this stress is
^-I^.bdx, integrating which between the limits
^ D , ly
;c = H and
^2 2
bTiy
= \ATiy.
= (^A- A")TD ^\A'Tiy.
If we put D for U , we will commit a small error on the side of
safety ; then will
and therefore
^^ = TD{A - A" + \A'),
A-^L iA' + A"
Q. E. D.
If M be the moment at any section of the beam, and R the
intensity of stress on the fibre most remote from the neutral
surface at the same section when the beam is fully loaded, we
can write the equation
M=ARD^-\A'RD,
where A is the area of the top flange, and V is, as before
assumed, equal to D; from which we have
M
D{ATwy
M
S=RA =
4-0
where .S is the stress on the upper flange at the section consid-
ered. This last formula is useful in determining the rivet
spacing in the flanges of built floor beams and plate girders.
APPENDIX HI.
221
y are respectively
it of this stress is
ts
APPENDIX III.
;rror on the side of
; beam, and R the
e from the neutral
is fully loaded, we
id V is, as before
; the section consid-
ermining the rivet
nd plate girders.
METHOD OF FINDING THE LENGTH OF THE LONG DIAGONALS
IN A DOUBLE-INTERSECTION BRIDGE.
Let
then
and
or
/= panel length of bottom chord = GD or DB in the accom-
panying diagram,
c = half increase of panel length in top chord,
d = depth of truss between centres of chords = AB,
a = angle between radial line at panel point and perpendicular
to lower chord ;
• -1 ^
« = sm — ,
a
DE:c::l:d,
DE = i
BG^.G£=.s/^^=2^^''^.
.(LJ".
When the camber is small, BG can be taken equal to 2GD
In triangle A£G, AB and BG are known, also angle
ABG = 90° + 2«.
if
222
APPENDIX ITL
AB + BG:AB-BG\: tan \ [i8o° - (90' + 2a)] :
im\\_BAG-BGA'\;
BAG-BGA = 2tan-i
[^Irli^'^Gs"-")}
Again :
{BAG - BGA) -[■{BAG + BGA) = 2BAG =
{BAG - BGA) H- (90° - 2a), which gives BAG;
also
BGA = 180° - {BAG + 90° + 2«) = 90° - (BAG + 2a) :
finally,
AG= AB cos BAG + BG cos BGA = length of diagonal required.
t w
\ \_BAG - BGA\ ;
(45-.)}
), which gives BAG;
- i^BAG-\-z(t)\
of diagonal required.
( i
!:'■
13' J
ADDENDA.
In an otherwise very favorable review of this treatise by
The America.. Engineer," there was pointed out a serious
halvSr "'"'^ attachment of a floor beam by Jour
In the words of the review, "the inner loop will take neirlv
■not quite all the load at the panel point, when the bridg t
..^t adjusted; and this not only becomes constrained iLf
f int: hr"'""^ f '""'^ ^^"^'^^ '''^''■* The numbe;
1 ^ ? r "^ ''■' ^°"^^^"t'y w^'-king loose, presum-
ably by stretching, m railroad-bridges in which this detail is
used, demonstrates its unsatisfactory character "
The author has long recognized the inequality of distribu-
>on of floor-beam load between the inner and outer hangers
but considered that the low intensity of working-stress on
these members would compensate for the objectionable in-
"luality. Such has been also, in all probability, the opinion of
most American engineers ; for beams, when not riveted to the
posts, are nearly always suspended by four hangers. The fact
the inner hangers working loose can have been only lately
-vered It shows, however, that this detail needs improve'
nt, uKl as hc> aim of this treatise is to design structures
J^^^^^^^o^tjh^^ of so doing is to use single beam
• Main diai;()nal.
221;
226
ADDENDA.
hangers ; but this method will not always work, owing to the
<acat bending-movements which they produce upon the puis.
For instance, take the case of a 20' panel of a Class A bridge
having a 24' clear roadway, and two 6' sidewalks. The weight
supported by each single hanger would be about 23 tons, and
the distance between centres of main diagonals would not be
far from ten inches. These data give a vertical bending-
moment upon the pin equal to 57-5 inch-tons, which aloue
would call for an iron pin 4!" in diameter ; but, when combined
with the horizontal moment, it would require a much larger pin
than a practical designer would care to employ.
The double hangers in such a case are a necessity, but the
connection must be such as to distribute the load eqttally iq^on
them. Such a distribution can be assured by using the follow-
ing detail : — ,.111
On the under side of the beam at each end is attached by
four rivets a plate about five-eighths of an inch thick, six inches
Ion- and as wide as, or a little wider than, the beam flange,
Th£ plate is placed symmetrically to the plane of the truss;
and the middle of the under side is grooved so as to receive
one-sixth of the surface of a pin about two inches in diameter,
which rests in a similar groove on the top of the beam-hanger
plate The lateral dimensions of this plate will be slightly
greater than usual, but the thickness need not exceed three-
quarters of an inch. To prevent the plate from rupture by
bending, there are attached to the under side by countersunk
rivets two angle irons, or plates bent into the form of angle
irons, the vertical legs being connected by countersunk rivets,
which in the neighborhood of the pin pass as nearly as may be
through the neutral surface of the T beam, and elsewhere near
the lower edges of the angles.
As the axis of the pin is parallel to the length of the bndgc
the vertical legs must be transverse thereto. This detail will
be readily understood by referring to Plate VIII. _
To illustrate how to find the sizes of the stiffening plates,
number of rivets required, etc.. let us design a beam-han^er
plate, when the total weight upon the four hangers is ict.
tons The centres of the beam-hanger holes may be assumed
i, 5
ADDENDA.
227
to be situated on the corners of a six-inch square. This would
make the bending-moment on the plate thirty inch-tons, which
would be resisted by the T-shaped section of the two bent
pates combined with the uncut portion of the beam-hanger
P ate below the pin. Assuming the latter thickness i", and
the plate stiffeners to be of 6" X 6" X i" angle iron, would
make the T about 12" X 6f' X i", the centre of gravity of
wh.ch ,s about 5' above the bottom. The moment of inertia
IS, tlierefore,
i', X 12 X (i.o)'^-h 12 X (i.o)^-hTV X r X (5.5)3
+ 5-5 X (2.25)^ = 54-1-.
The resisting moment is given by the equation
M =
d,
so taking 7? = 4 tons.
J/=1J<_14^
43-2.
As the bending-moment was thirty inch-tons, the sizes
assumed are ample.
It will be well to use three-quarter-inch countersunk rivets
(the largest possible), so as to make the different portions of
the T head act together.
There is a tendency to bend the plate in a direction at rio-ht
angles to the one considered, the moment for which is fifteen
inch-f.ns on each side of the pin. This will be resisted by a
couple whose forces act as compression on the top plate of ^he
T, and tension on the rivets near the bottom of the an-les
lakmg the centre of moments at the middle of the top plate
and the distance therefrom to the horizontal centre line of the
nvetj^ioles as 4! inches, will make the tension on the rivets
i,i'? — 3.42 tons. Using an intensity of only two and a half
tons, because of the initial tension on the rivets, will make the
section required 1.37 square inches: consequently two i" rivets
will be sufficient.
l! 1 1
J!
11
228
ADDENDA.
The difference in the total weight of iron per hneal foot
caused by the use of this detail will be from six to ten pound.,
which weight should be added to those given in Tables I II.,
Tnd III., under the heading "Floor System/' whenever this
style of beam-hanger plate is to be employed
It will be noticed in the diagram on Plate V II., that the
floor-beam stiffeners at the support are placed close together
so as to take up the vertical reaction of the hangers transferred
by the auxiliary pin. The sectional area of these stiffeners
should be about equal to that of the hangers.
Plate VIII illustrates a detail by which the foot of a pes
may be riveted or bolted to the floor beam, for the purpose of
aiding the distribution of lower lateral rod stresses among the
chord bars. This is accomplished by means of a jaw plate be-
tween the post channels, and by turning up the ends of the
exterior re-enforcing plates, so as to permit the passage
rivets or bolts. The latter may be considered pre erabc ,
they need not be screwed up very hard, but should ht with
.rcat accuracy in the holes. Their object is to prevent tor-
^ion of the post, but not to aid the beam hangers in resisting
^'^ When this detail is employed, the lower chord pin at the first
panel point should pass through holes bored in bent plates, which
are to be well riveted to the floor beam. _
It is probable that most bridge designers wdl consider this
arran-^ement to possess too much refinement for highway-
bridges, preferring to trust to the rigidity of the joists as sug-
^^'¥here'is'no' doubt, though, about its being a detail that could
be advantageously employed in railroad-bridges.
When ve>rtical sway bracing is used, the detail or t e upper
lateral strut connection, shown on Plate VIII., will be oun
be an improvement on the one previously described, in that it
obviates field riveting. ., 1 „f ti^A
It consists in the use of a double ]aw on the end of t
lateral strut, and two nuts of different diameters the pin be n
aoubly shouldered. The office of the inner and larger
to press the end of the strut against the chord ; and that of
■ I I
ADDENDA.
229
the outer one, to take up the pull of the bent eyes, the injuri-
ous effect of which is mitigated by the inner jaw plate.
When no vertical sway bracing is used, the detail described
on p. 98 will probably be preferable ; because it involves the
spreading apart of the lateral strut channels, and thus furnishes
a greater resistance to bending the strut. The use of the im-
pr()^•cd detail will not affect the sizes of the lateral strut chan-
nels as given in Table XXV.
Plate VIII. illustrates also an improved connection for the
portal struts, avoiding the necessity for field riveting. The
increased depth of the jaw plate at the pin hole is an impor-
tant feature, its object being to resist the bending effect of that
component of the stress in the portal rods which is parallel to
the length of the batter brace.
Whenever the portal rods exceed ij"in diameter, this im-
proved shape of jaw plate should be employed.
n\
n
M
GLOSSARY OF TERMS.
'It Ml
GLOSSARY OF TERMS.
Adjustable Member. — A member of a bridge the length of which can be
iiK K asrd or iliniinishcd at will.
Angle Iron. — Iron rolled into the shape shown in section on Plate II
Apex. — The intersection of a brace with a chord or flange; called al.so a
paiK'l point.
Axis of Symmetry. — A line dividing an area into two parts equal and
.similar to each other, and similarly di.sposed to the line.
Bar. — A piece of iron flat or square in .section.
Batter. — Slope, or inclination, to the vertical; usually measured by the
tan^aiit of the angle, or so many inches to the foot.
Batter Brace. — The inclined end post of a bridge. (Plate I.)
Beam. — A member intended to resist bending.
Beam Hanger. — A rod or square bar supporting a floor beam from a
clion! pin. (Plate I. and Plate II., Fig. 13.)
Beam-hanger Nuts. - Nuts on the ends of beam hangers, serving to press
the tl(,or beam against the feet of the posts or against the chord heads
(Plate II.. Fig. 13.)
Beam-hanger Plate. - A plate placed beneath the end of a floor beam for
thu iRaiii-luinger nuts to rest against. (Plate JI., l"ig. 13.)
Beam-trussing Posts. — Posts for trussing beams. (Plate II., Fig. 16.)
Beam-trussing Rods.— Diagonal rods for trussing beams, (pfate II.
Fitr. if).) '
Bearing. — A resting-place, usually for a pin or rivet.
Bearing- Pressure. — The pressure on a bearing.
Bed Plate. — A plate to distribute pressure upon masonry. (Plate III )
Bending-Moment. _ The moment of a force or forces which bend or tend
to bend a piece.
Bending-Stress. — The stress produced in a piece by bending.
Bent. _ A frame of timber or iron, usually the former, as a bent of false-
work.
Bent Eye. — An eye on the end of a bar, the plane of which makes an
angle with the direction of the length of the bar.
Bevel. _ The slope on the end of a piece.
2,n
'^i
III*
m
234
GLOSSA/^V OF TEM.IfS.
Bill of Material. — A list of various portions of material giving dimensions
and weights, or other quantitative measurements.
Block. —A system of one or more pulleys or sheaves, so arran^^d in a
frame or shell as to multiply the power of the rope passing around tlieni, or
to change its direction.
Board Measure. — The measure of timber, the unit being a piece one foot
square and one inch thick. Timber is sold at so much per thousand feut
board measure, usually written, per M. b. m.
Bolt. — An iron rod with a square head at one end, and a thread and nut at
the other .
Brace. — Generally a strut, but sometimes the term is applied to a tie.
Bracket. — A knee or knee brace to connect a post or batter brace to an
overhead strut. (I'late I. or Plate II., Fig. i2.)
Built-Beam. — A beam made up of plates and angles riveted together.
(I'late II., Fig. 13-)
Burr. — A rough edge or ridge left l)y a tool in cutting metal. The term
is sometimes used for a nut.
Button Sett. — A tool for forming the heads of rivets.
Camber. — The upward curvature of a truss. It is measured by the heigiit
of the middle point of tlie centre line of the lower chord above the line
joining the centres of end pins.
Camber Blocks. — Blocks of wood used in erection, so placed as to be
easily removed (Flate VII.)
Cape Chisel. — A tool for cutting iron. It consists of a rounded edge on
the end of a sliort rod. The edge is very obtuse, so as not to break easily.
Centre of Gravity. — That point of a body about which the weights of pll
the different portions I)alance.
Channel, or Channel Bar.- Iron rolled into the shape shown in section
on I'late 11.. Fig. i.
Check Nut, or Lock Nut. — A contrivance to prevent a nut from turning
when sul)jected to shock.
Chord. — The upper or lower part of a truss, usually horizontal, resisting
compression or tension. (I'late 1.)
Chord Bar. — A member of the chord which is sul:)jected to tension.
(I'late I.)
Chord Head. — The enlarged end of a chord bar, through wliich the pin
passes.
Chord Packing. — The arrangement of the bottom chord of a truss.
Clear Headway. — The vertical distance from the upper surface of the
floor to the lowest part of the overhead bracing. It is a measure of tlie licigiit
of the highest vehicle that could pass through th- bridge.
Clear Roadway. — The horizontal distance, measured perpendicularly to
the planes of the trusses, between the inner edges of the batter l)races. It
is a measure of the width of the widest vehicle that could pass llirougli
the bridge.
..ii:
GLOSSARY' OF TE/iAfS,
235
aterial giving dimensions
i, and a thread and nut at
:tion, so placed as to be
Cleat — A narrow strip of wood nailed to something for the purpose 01
kwwwr a piece of work in its proper place.
Co-efficient of Friction. - A numerical quantity, which, multiplied into
the normal pressure, gives the frictional resistance. It is equal to the natural
tangent of the angle of repose.
Cold Chisel. — A tool for cutting iron.
Column.- A pillar or strut; a long member which resists compression
Component. -One of the. parts into which a stress may be resolved 'or
divided.
Compression. -A stress which tends to shorten the member which is
siilijccted to It.
Concentrated Load. _ A load which is, or may be considered, collected at
one or more points.
Connecting Chord Heads. -Chord heads used to connect bottom chord
channels to pms. (Plate II., Fig. 10.)
Connecting-Plate.- A plate!ised for connecting two pieces
Contmuous Spans. -Consecutive spans connected over the points of
support.
Counter. -An adjustable diagonal which is not subjected to stress bv a
uniloimly distributed load covering the bridge. (Plate 1 )
Countersunk Rivets.- Rivets, the heads'of which are let into one or both
of the plates which they connect, so as to leave a Hush surface or surfaces
Couple. — Two equal and parallel forces not acting in the same line.
Cover Plate.- A plate used to cover a joint, or to connect two pieces of
the top chord plate, (llate 11., Figs. 11 and 12.)
Crab. -A slow-motion machine, worked by a crank for the purpose of
winding a rope x\\Mm a drum, thereby raising a heavy weight.
Dap.— To notch timber onto its bearing.
Dead Load. -The weight of all the parts of the bridge itself, and any
thing tiiat may remain upon it for any length of time.
Deck Bridge.- A JM-idge in which'the passing loads come upon the upper
chords or the upper ends of the jiosts.
Deflection. -Motion laterally, or at right angles ro the length of the piece
it IS also used for the amount of motion, and is generally expressed in inches
Depth of Truss. -The vertical distance between the centre lines of upper
and lower chords. '
Diagonal. — A member running obliquely across a panel. In this work all
the (ha-onals except the batter braces are tension members.
Diagram of Stresses. -A skeleton drawing of a truss, upon which are
wrm, II the stresses in the different members. (Plate V )
Double Intersection. -The style of truss where the diagonals cross the
posts at the middle of their length, as in the bridge shown on Plate 1
Double-riveted Lacing. _ Lacing in which each bar is connected by two
"vets at each end, (Plate 11., Fig. 13,)
236
GLOSSARY OF TERMS.
I I
■^f \[
Drift Bolt. — A round or square piece of iron, usually from one to three
feet long, without head or nut, used to connect timbers.
Drift Pin. — A slightly tapering rod of hard steel, used for making rivet
holes coincide. Its use is more convenient than advisable.
Effective Area. — The gross area of a section, less that lost by rivet or
pin holes; the net area.
Elastic Limit. — That intensity of stress at which the ratio of stress over
strain commences to show a decided change. . For wrought-iron it is from
twelve to fifteen tons.
Erecting-Bill. — A bill of material for a bridge, so arranged as to facilitate
the finding and placing of members during erection.
Expansion Joint. — The connection of pedestal to bed-plate, shown on
Plate 111.
Expansion Rollers. — A set of half a dozen or more turned rods of exactly
the same diameter, placed under the shoe plate at one end of a truss to
permit of expansion and contraction. (Plate II., Fig. 9.)
Extension Plate. — A jjlate riveted to the end of a strut channel, and pro-
jecting beyond it, to permit of the passage of a pin. (Plate II., Fig. 12.)
Eye. — A hole in the end of a member to permit of the passage of a pin.
Eye Bar. —A bar with an eye at each or one end.
Factor, or Factor of Safety. —Tlie ratio of ultimate load to greatest allow-
able working-load. This term is getting out of favor among engineers, as its
use has been somewhat abused. There is no such thing as a factor of safety
for a well-proportioned bridge, for each member should have an intensity of
workinc-stress proportionate to the character and amount of work which it
has to perform.
Fall Line. — A rope used in erection for raising and lowering weights.
Falsework. — Temporary timber work to support a bridge during erection.
Felly Plank. — A guard rail so placed as to catch the felly of a wheel, and
thus prevent the vehicle from striking the truss. (Plate II., Fig. 13.) In
wide bridges a felly plank is often placed midway between the trusses, to
prevent vehicles passing from one side of the bridge to the other.
Field Riveting. — Riveting done in the field, or during erection. It is the
poorest and most expensive kind of riveting.
Fixed End. — An end of a strut so firmly connected as to prevent all motion
of the strut in the neighborhood of the end.
Filling- Plate. — A plate tlie function of which is to make flush two surfaces
(Plate II., Fig. 12.)
Filler. — A small ring of iron or piece of ])ipe placed on a pin in order to
keep in position the members coupled thereon.
Fixed Load. — A load remaining i)ormanently, or for a considerable length
of time, upon a structure or portion of h structure.
Flange. — The upi)er or lower chord of a beam. It is the principal part
for resisting either compression or tension.
Flexure. — Bending.
GLOSSARY OF TERMS.
217
) arranged as to facilitate
to bed-plale, sliown on
re turned rods of exactly
t one end of a truss to
Floor, or Flooring. — That part of the bridge which directly receives the
tr;v>rl. (Plate II., Fig. 13.)
Floor Beam. — A beam to support a portion of the floor and its load.
ll'latu 1. and J'late II., f^ig. 13.)
Forge. — An apparatus for heating iron.
Framing The carpenter work on timber.
Giasticutus Rods. — A term (perhaps unauthorized, but in common use
aiiiimg Imdge builders) to denote a small horizontal rod connecting the middle
points of two adjacent posts of the same truss, for the professed purpose of
lixinu or holding the posts at the middle in order that they may be figured
for halt-length. The benefit derived therefrom is more imaginary than real.
Girder — Any structure to cross a chasm or opening. The term is gener-
ally applied to short structures for places where it is not advisable to use
trusses: for instance, a plate girder, or a rolled girder.
Guard Rail. — See felly plank.
Guys, or Guy Lines. — Lines for bracing the top of a pole, derrick, or any
simihir apparatus.
Gyration — See radius of gyration.
Hammered Head. — A head formed on the end of a bar by hammering.
Hand Lines. — Small ro])es used in erection.
Hand Rail, or Hand Railing. — An iron or wooden frame placed on or
near the outside of a bridge in order to prevent persons or animals from
lalliiiu' therefrom. (Plate IV., or Plate II., Fig. 13.)
Hand-rail Cap. — The upper longitudinal timber or timbers of a wooden
liand-railing. (Plate II., Fig. 13.)
Hand-rail Post. — Post for supporting a hand railing. (Plate II., Fig. 13 ;
Plate IV.)
Headway. — See clear headway.
Hinged End. — An end of a strut connected only by a pin.
Hip. — The jjlace at which the top chord meets the batter brace.
Hip Joint. — The joint of the top chord and batter brace.
Hip Vertical. — A rod hung from the pin at the hip for the purpose of
^^ls]n iiding the floor beam.
Holding-on Bar. — \ lever to hold against one end of a rivet while the
liuh! at the other end is being formed with a button sett.
Hub Plank. — A plank to protect the iron-work of the truss from being
strink by the hubs of passing wheels. (Plate II., Fig. 13.)
I-Beam. — A piece of rolled iron of the section shown ow Plate II., Fig. 2.
Initial Tension — The tension caused in any adjustable member by screw-
ing; lip the adjusting apparatus.
Intensity. — Tiie intensity of a stress is the amount of stress upon a square
iiuli (il section.
Intermediate Strut.— An overhead strut in high bridges, attached to the
posts (it ()p])osite trusses, and lying between the upper lateral strut and
llic ilcxir. In deck bridges, if used at all, it would lie between the upper
and hnvcr lateral struts. (Plate I.)
ittiiii
If
«
238
GLOSSARY OF TEIUfS.
Jaw. — A connection on the end o£ a strut similar to that shown on Plate
II., Fig. 13.
Joint. — A place where two alnitting or lapping pieces are connected.
Joist. — A timlier l)eam that supports part of the Hoor and its load. (Plate I.
and Plate II., Fig. 13)
Knee, or Knee Brace See bracket.
Lacing. — A system of l)ars, not intersecting each other at the middle, used
to connect the two channels of a strut in order to make them act as one
member. (Plate II., Fig. 12.)
Lacing-Bar A bar belonging to a system of lacing.
Lateral Rod. — A tension diagonal of a lateral system. (Plate I.)
Lateral Strut. — A compression member of a lateral system. (Plate I.)
Lateral System. — A system of tension and compression members forming
the we!) of a horizontal truss connecting the opposite chords of a bridge. Its
puri^oses are to transmit wind pressure to the piers or abutments, and to
prevent undue vibration from jjassing loads.
Latticing. — A system of bars crossing each other at the middle of their
lengths, u.sed to connect tiie two channels of a strut in order to make them
act as one member. (Plate II., Fig. 12.)
Lattice Bar. — A bar belonging to a system of latticing.
Leg. — One of the two portions of an angle iron separated from each other
by the bend.
Lever Arm. — The perpendicular from the centre of moments to the line
of action of a force. The lever arm of a couple is the perpendicular distance
between the lines of action of the two equal and parallel forces.
Live Load. — The moving or passing load upon a structure.
Linville Truss (also called " Double Ouadrangular," " Whipple," and
" Double .System Pratt " truss). — A truss with vertical posts and diagonal
ties spanning two panels. It is the truss represented on Plate I.
Lock Nut. — See check nut.
Loop Eye. — .In eye on the end of a rod or square bar, elongated into the
form of a loop, as shown on Plate II., Fig. 16.
Lower Falsework. — The falsework below the level of the lower chords.
Main Diagonal. — A tension member of a truss, sloping uinvard towards
the nearer end of the sjian. Main diagonals in iron bridges are not adjust-
able.
Moment. — The [jroduct of a force by its lever arm.
Moment of Inertia. — Represented by the equation, / - Ap'^ = Zr'-dA,
where // is the area of the section considered, p the radius of gyration, ■.\w\r
the distance of any point from an assumed line lying either in the surtace or
outside of it: in other words, the moment of inertia of a surface about any
a.xis is the product of the area by the square of the radius of gyration ; or
it is the summation of the products of each differential of the area l>y tlie
sc^uare of its distance from the axis. If the axis lie in the surface, the
moment of inertia is called a surface moment of inertia; while, if the axis
tttJili
ii
GLOSSARY OF TERMS.
239
r to that shown on Plate
.re bar, elongated into the
be perpendicular to the surface, the moment of inertia is called a polar
moment of inertia.
Monkey Wrench. — A wrench capable of being adjusted so as to fit nuts
of (lilt'erent sizes.
Moving Load. — See live load.
Mud-Sill. — A timber, usually from 6" by 6" to 12" by 12", at the bottom
of a i)C'nt. It is laid horizontally in a trench, and the posts of the bent rest
upon it.
Name Plate. — A plate of iron placed in a conspicuous position on a
l)ii(ls,'e. containing the name of the maker or designer of the structure.
Negative Rotation. — Rotation in a direction opposite to that of the hands
of a watcli.
Net Section. — See effective area.
Neutral Surface. — That part of a member subjected to bending, which is
iitithLT extended nor compressed. In symmetrical wrought-iron beams, with
equal or nearly equal flanges, it is taken to be at the centre line of the web.
Nut. — A small piece of iron with a threaded core to fit on the screw end
of a bolt, rod, or bar. (Plate II., Fig. 6.)
Order Bill. — A form of bill used in ordering material from the manufac-
tuiTrs.
Ornamental Work. — Fancy work at the portals of a bridge to give it
airhilccturnl effect. (I'lates I. and VI.)
Overhead Bracing. — The upper lateral or vertical sway bracing in
tlir()u;,'h bridges. The term is usually applied to the vertical sway bracing,
if tlicre be any ; if not, to the upper lateral bracing.
Packing. — See chord packing.
Panel. — That portion of a truss between adjacent posts or struts in Pratt
tiu.--s bridges; called also a bay.
Panel Length. — The distance between two adjacent ])anel points of the
.-laiiio ciiord.
Panel Point See ape.x.
Pedestal. — The foot of a batter brace or end post. (Plate II., Fig. 9.)
Permanent Set. — The alteration in length of a piece of material which has
liein ^ui>jected to stress, remaining after the stress has been rem ;ved.
Pillar. — See column.
Pilot Nut, or Pin Pilot. — A nut, one end of which is a truncated cone,
used to ])rotect the thread on tlie end of a pin when the latter is being driven
into place. (Plate II., Fig. 5.)
Pin. — A cylindrical piece of iron used to connect bridge members. (Plate
11 . i'ig, 5.)
Pitch. — The distance between centres of consecutive rivets of the same
Plane of Symmetry. — A plane tlividing a body into two equal and sym-
iiutiiial i)arts similarly disposed in reference to the plane.
Plant. — Tools and apparatus useil in construction.
! I i
240
GLOSSARY OF TERMS.
H ' f
Plate. — A piece of flat iron wider tlian a bar. Tlie common distinction
between the two is that a plate is attached to something else, and acts witii it,
while a bar is an independent member.
Plate Girder. — A beam, built of plates and angles, used to span a small
opening, generally less than forty feet.
Pony Truss. — A truss so shallow as not to permit the use of overhead
bracing.
Portal. — The space between the batter braces at one end of a bridge.
Sometimes the term is applied to the portal bracing, though incorrectly.
Portal Bracing. — Tiie combination of struts and ties in the plane ot tlie
batter braces at a portal, which transfers the wind pressure from the upper
lateral svstem to the abutment or pier.
Portal Strut. — A strut belonging to the portal bracing. (Plate I.)
Positive Rotation. — Rotation in the direction of the hands of a watch.
Post. — A vertical strut. (Plate I.)
Pratt Truss (called also the " Murphy-Whipple," or "Quadrangular"
truss;. — A single-intersection truss with vertical struts and diagonal ties.
Quadrangular Truss. — See Pratt truss.
Radius of Gyration. —The radius of gyration of any surface in reference
to an axis is ;he distance from the a.xis to that point of the surface in which,
if the whole area were concentrated, the moment of inertia in reference to thu
axis would be unchanged. It is therefore equal to the square root of the ratio
of the moment of inertia over the area.
Ream. — To enlarge a rivet hole.
Reamer. — A tool for enlarging rivet holes.
Re-enforcing Plate. — A jtlate used for the purpose of providing additional
pin l)earing, or strength, to compensate for material cut away. (Plate 11.,
Figs. 1 1 and 13.)
Resolve. — To divide a force into component parts.
Rivet. — A short piece of round iron tightly connecting two or more thick-
nesses of metal, and having, when in place, a head at each end.
Roadway. — The passage-way of a bridge for vehicles ; usually means
clear roadway, q. v.
Rod. — A piece of round iron.
Rolled Beam. — An J-beam. (Plate II., Fig. 2.)
Roller. — See expansion roller.
Roller Frame.- A light frame of iron for holding the rollers in position.
(Plate II.. Fig. 9.)
Roller Plate. — The plate upon which the rollers rest, and which itself rcs^
upon the masonry.
Rope Sling. — See sling.
Run. — A line, or string; as, a run of joists.
Set. — The extension or compression of a piece of material under stress.
Shear, or Shearing-Stress. — The resistance which a body offers to the
])assage,or to the tendency to passage, of one section along the next consecu-
tive section.
GLOSSARY O/-- TKKMS.
241
Shipping-Bill. — A list of portions of a bridge, arranged in a manner to
f;uilitate counting and chucking when tlie material is received after shipment.
Shoe. — Another term for pedestal, q. v.
Shoe Plate. — The plate on the under side of the shoe, resting on the
rollers, l)ed-i)late, or masonry.
Side Bracing.— A bracing for pony trusses to attach the panels of the top
chord to the floor beams prolonged, in order to fix the panel points of the
top chord. (Plate 111.)
Sidewalks.- Roadways at the sides of a bridge for foot-passengers on,y.
Single Intersection. — That style of truss in which the diagonals do not
ao>s the posts. It is rejjresented in skeleton on Plate V.
Skeleton Drawing.— A drawing which shows only the centre lines of
in(iii!'(.r.s. such as a diagram of stresses. (Plate \ )
Skew Bridge.- A bridge in which the horizontal lines joining correspond-
in- panel points of the opposite trusses are oblique to the planes of the trusses.
Sledge A heavy hammer, or mallet.
Sleeve Nut. — An elongated nut, the core at one end having a right-hantl
ihrLmI, and that at the other a left-hand thread. Its office is to lengthen or
sh(irt-n a tension member. (Plate II., Fig. 16.)
Sling. — A loop of rope, very useful in erection for making a hasty attac h-
nuTit.
Slope. — Inclination to a horizontal plane.
Snatch Block. — A block with one side capable of being opened for the
insertion of the rope. Its office is to change the direction of the rope.
Span. — The length of a bridge from centre to centre of entl pins or
licarin^s.
Spikes. — Large nails for timber work. (Plate 1 1., Fig. 13.)
Splay. — To spread at one end the two main portions of a member.
Splice. — A joint connected by means of plates.
Splice Plate. — .A connecting jjlate at a joint. (Plate II., Fig. 12.)
Spread. — The distance ajiart laterally.
Staggered Rivets.— Rivets are said to be staggered when each rivet of one
row is opposite to the middle of the s])ace between two rivets of the next row.
Static Load. — Dead load. q. v.
Stay Plate. — A plate always used at the end of a system of lacing or
latticing. (Plate II.. Fig. 12.)
Stiffening- Angle. — .An angle iron used to stiffen the web of abeam. (Plate
11.. i'iv'. I3'l
Stiffener. — A piece of iron used to stiffen the web of a beam : it may be of
an^'lc or tee section. (Plate II., Fig. 13.)
Strain. — The extension or comjiression of a piece of material which is or
lias been under stress.
Stress. — The internal resisting force of a piece of material wiiich is
.•-trainnl.
Strut. — ,\ member which resists compression.
■JAl
(//.(AS-.V./AM' ('/■• /rh'MS.
Sub-Punching. — Tlic punchinj; of livcl lioks wluil) liavc to hu afterwards
vnlaij^ed by roaming.
Sway Bracing. — Bracing transverse to tiie i)lanes of tlie trusses, lis
ol)ject.s are to resist wind pressure, and to prevent undue vibration fn.in
parsing loads, (i'late 1.)
Table of Data. — .\ list of the known circumstances that affect the design-
iiig of a structure.
Tap. — .\ screw for cutting a thread in a nut.
Tee or T iron. — A piece of rolled iron of the section shown on I'lule II.,
l'ig.4. , ,
Tension. — \ stress tending to elongate a body.
ThreaJ. — The spiral part of a screw or nut.
Through Bridge. — A bridge with overhead bracing.
Tie. — .\ tension iniMnber; generally refers to a main truss.
Timber Truck. — A small, strong wooden frame, with an iron roller set
entirely below the upper surface. It is used in bridge erection for moviiii;
large timbers and heavy weigiits along a runway.
Tongs. — Part of a riveting outfit; used for holding and carrying heated
rivets.
Transverse Component. — \ component in a transverse direction ; geiiLi-
ally intended for a component peri)endicular to the jtlanes of the trusses.
Truss. — \\\ assemblage of tension and co.npression members so arranged
as to transmit loads from intermediate i)oints to the ends.
Trussing. — A poor substitute for lacing or latticing. (I'late 11., Tig. S,
r-iate VI.)
Turn Buckle. — .Similar to a sleeve nut, and for the same purpose. The
siilesare open, so that a crowbar maybe inserted for the purpose of screwiin;
tip. Turn buckles are used for larger bars or rods than are sleeve nuts.
(I'late II., Fig. 1 6.)
Ultimate Strength. — The greatest load ;hat a [Hirtion of material can
bear.
Uniform Load. — .V load so distributed over an entire structure, that eiiual
lengths everywhere receive ecpial portions.
U-nut. — A piece of iron, in the shape of the letter U, through whidi passes
the threaded end of a rod, and which affords a bearing for the nut, with room
to screw up the latter. Its use is not permissible in tirst-cla.ss bridge con-
struction.
Upper Falsework. — The falsework that lies above the level of the l.nver
diords.
Upset End. — An end of a rod or bar enlarged for the cutting thereon of
a screw-thread.
Vibration Rod. — A tension member for vertical or i)ortal sway bracing.
(I'late 1.)
Washer. — A piece of cast or wrought iron to distribute the ])ressure of a
I ol; head or nut over tiiiiluT. ' I'lato il.. Fig. 6.)
li hiivf to 1)C' aderwanls
;s that aiicct the dcsigii-
tion shown on Plate 11.,
GLOSSAh'\- OF TKAWfs.
243
Web. — The portion of a truss or beam I)etwcen the flanges. Its office is
piiiiripally to resist shear.
Welded Heads. - Heads first worked into shape, then welded on the l>ars
Whipple Truss. — .See Linviile truss.
Wind Shakes. — Cracks in timber caused by the wind while the tre
e was
Working-Drawings. -iJrawings containing all the measurements neces-
sary lor construction.
Working-Stress. - The stress, usually the greatest stress, to which a i.iece
1.1 nial.rial is or should be subjected. Sometimes incorrectly employed for
iiiliiisiiy of working-stress.
Wrench. — A tool for screwing up nuts.
ling and carryiug healed
HHij
1
•'aBBBt
i
■i ■
i
.i
INDEX.
•Sa
111
<i
INDEX.
Allowance for waste, 68, 183, 190.
Anchorage, 8, 104, 148.
Aiifilf irons, 19, 146.
Area opposed to wind pressure, 6, 4S.
Jiars, best proportions for, 79, 80, 89.
Hatter braces, limiting slope for. 7.
Hattcr-brace plates, minimum dimensions
of, 14.
Pattfr braces, proportioning of, 6j, 132.
Hattcr-bracc sections, 1 1, 63.
Heam-liangcr plates, ij, loi, 146.
•'(.•am lian.ners, 23, 75.
licains, wooden, 23, 67 ; Tables xiii., xiv.
Bearings, 21, 77, 93; Tables xxvi.-xxviii.,
xxxvi., xxxvii.
Bearing-stress, 13, 76,
lit'd plates, 16, 104, 146.
lieiuling effect of wind on posts and bat-
ter braces, 9, 52.
BciuliMg-strcsses, intensities of, 13, 78.
Iit;nts, 199, 200, 203.
Best iiroportions for bars, 79, 80, 89.
Hi'Vfis, iSi.
Hills of iron, yi, 113, 114, rsi, 152.
ol lumber, 115, 155.
of rivets, 151, 190, 192,
of bolts, 188, 191, 205.
Bills, erecting, 204, 205.
order, 183, 185.
shipping, 19a
Bolts, 23, 24.
Bond, 168.
Bottom chords, 59,62,66, 215.
Braces, side, 7, 164.
latter, 7, 9, 14, 6j, 133.
Brackets, 22, 53, 103, 148.
Uridge lettings, 157.
Bridges, classification of, 5.
styles of, 7, 38.
liuilt Hoor beams, 12, 19, 68, 107; Tables
xix.-xxi.
Camlier, 9, 175, 176.
Camber blocks, 200.
Carpenters' tools, 198.
Cast-iron, 24.
Cast-iron portals, 58.
Channel bottom chords, 11, 66.
Channels, properties of. Table xxviii.
Checking, method of, ri6, iSr, 182, 198.
Chord bars, 59, 62, 66, 79.
Chord heads, 20, 177.
Chord l)acking, 62, 81, 132, 179, 206.
Chord jjlatcs, 14, 63,
t'hord projiortioning, 64, 129, 130.
Chord sections, i r. 59, 62, 63, 66.
Classification of bridges, 5.
Clear headway, 7.
Clear roadway, 6.
Closed columns, 56.
Columns, formula for, 12.
Complete dcsinn for a bridge, 126.
Comprossive stresses, 12.
Connecting-plates, 15,94-99, 137-144.
Connection for lateral systems, 10, 98-100.
Continuous spans, 9.
Contract, form of, 167.
Cost, estimates of, 116.
Cost of bidding-expenses, 170.
of blacksmithing, 170.
of eiecticni, iiy.
247
i!
248
INDEX.
Cost of falsewDvk, 117.
of franung, 1 17.
of hauling, 117.
of Uimljcr, 68.
of painting, 117.
of jiilc-drivcr, 198.
Counters, 12, 40, 41. 46, 59- 61, 127. 132-
Countersunk rivets, 91.
Cover plates, 16, 95, 144'
Cutting off flanges of channels, 23, 59,96.
Data, table or list of, 3S, 1 18.
Dead load, 6, 32, 126, 156.
Deck bridges, 46.
Demonstration of floor-beam formula, 219.
Depths of truss, economic, 3S, 124; Ta-
bles iv, V.
Design for a bridge, 126.
Details, jiroportioning of, 75, 86, 93, 136.
Diagonals, length of, 177, 221.
Diagrams of stresses, 40, 127 ; Tlate v.
Diameters of rivets, 15, 90; Tables .\.\i.\.,
xxxvi., xxxvii.
Dimensions, marking of, iSo, iSi.
Distributi(Mi of material in struts, 59.
Double-intersection bridges, 7, 44.
Draughtsman's equipment, 172.
Draughtsmen, hints to, 180.
Drawings, working, 172,
Economic depths, 38, 124.
Economy, 57, 59, 120.
Effect of wind pressure on members, 9,
48,99, 215.
End lower lateral-strut connection, 104.
144.
I'.nd lower lateral struts, 10, 56, 65, 135.
I'.nd panels, stilfen-.l, 11,62, 66. 129, 215.
Eipiipment, draught.unan'.i, 172.
for raising gang, 197.
i:,|nivalent length for iU-'ada, nuts, etc., 115.
lueeting-bills, 204, 205.
I'',recting-gang, 196.
Erection, 196.
Estimates of cost, 1 16.
Iv\pansion, S.
l'"..v])ansion joint, 103, 104.
l-lxpansion rollers, 21, 103, t4l, 20S.
l':xtension i)hites, 16, 96, 145.
19, 68, 107 ; Tables
Eyes, 20, 105.
ICye-bar heads, 20, 177, 178.
Falsework, 198.
Falsework pillars, sizes of, Table xxxix.
Felly plank, 23, 67.
Field riveting, 24, 92, 125.
Filling-plates, 145.
Fillers, 104.
Final order bill, 185.
Flanges, 19, 68, 107.
Floor beams, built, i:
xix.-xxi.
details for, 19, 30, 71, no.
limiting depth for, 19.
riveted to posts, lOl.
rolled, 12, 71.
trussed, 30, 72, 109.
Flooring, 23, 210, 211.
Floor system, 67.
Foremen, 197, 204.
Form of bond, 168.
of contract, 167.
of projiosal, 166.
of specifications, 162.
Formula for built beams, 19, 219
for coUinms, 12.
fcjr trussed beams, 72.
Framing falsework, 117, Z03.
Friction, riveted plates, 90.
shoe, 8, II.
Functions of J-beams, 55, 56.
Cas-jiipe i-lruls, 36.
Cieneral specilkations, 5.
Girders, 18, 19, 71.
Cuard rails, 23,24. •
Hammers pile-driver, 198.
Hand railing, 23, 24, 67.
Hangers, I)eain, 12, 22, 75.
Heads of eye bars, 20, 177, 17S.
Headway, 7.
Hints to draughtsmen, 180.
Hip connection, .'•;3, 95, 137, 138.
Hip verticals, 12, 14. 59- 6' ! Tables vi.-
viii.
Hub pUuik. 23.67,115.
I-beams, 13, 55. 56,71.
L\/)i:x.
249
S, 20, 177, 178.
liars, sizes of, Table xxxix.
23. C".
(, 24, 92, 125.
, 145'
)ill, 185.
58. 107.
built, 12, 19, 68, 107 ; Tables
xi.
ar, 19, 30, 71, HO.
depth for, 19.
;o posts, lOI.
2,7'-
30. 72, 109.
, 210, 211.
1, 67.
17, 204.
id, 168.
act, 167.
nsal, 166.
ficatidiis, 162.
■ Imilt lieams, 19, 219
nuns, 12.
sed beams, 72.
scwork, 117, 203.
■etcd plates, 90.
I II-
if I-beanis, 55, 56.
pile-(lii\er, 198.
ig, 23, 24, 67.
earn, 12, 22, 75.
yc b.irs, 20, 177, i~?>-
1 ■
aiiulUsmen, iSo.
L-tion, .S3, 95, 137. '3^-
lis, 12, 14. 59. 6'i 'I'al'l" ^i'-
, 2;,. fl7.l'5•
3, 55. jC'. 71.
Im linatioiis of lattice and lacing bars, 15,
Iiulirect transferrence of stress by rivets,
92.
Inilial tension, 10; 'I'able i.\.
lii^lni'tion, 21 1.
liitL-nsily of bearing-stress, 13, 76.
of bending-stress, 13, 78.
of compressive stress, 12.
of tensile stress, 11, [2.
Iiilermediatc strut connection, 98, 144.
Iiitinnediate struts, 51, 56,65; Table x.xv.
imn, bills (jf, 71, 113, 114, 151, 152.
cast, 24.
hand railing, 23, 24.
weight of, 33, 155, 156.
Jaws, 22, 100, 104, 106, 143, 144, 149.
JiMiu, sliding expansion, 103, 104.
Joints, top chord, 94, 139, 179, 20S.
Joists, 2^, 67, 209; Tables xv.-x^•iii.
KiKcs, or knee braces, 22, 53, 103, 148.
I ,iliiir in erecting, 117.
in framnig, 1 17, 19S.
[,.uing-bars, 15, [02, 146, iSi ; Table xxxi.
i.aleral-rod connection, 10, 99, 106.
Lateral rods, 14, 4S, 6r ; Table xxv.
strut connection, 98, 104, 144, [45.
struts, 9-1 1, 49, 56, '.',65, 135; Table
xxv.
svstems, 48, 61.
l.atlire bars, 15, 102, 146; Table xxx.
I.tngths, limiting, 6, 7.
of diagonals, 177, 221.
of lattice r.nd lacing bars, 102 ; Table
xxix.
ol span, 6, 7.
lAtlini; bridges, 157.
Limiting depths of pony trusses, 7, 123.
depths of lloor beams, 19.
lengths of span, 6, 7.
sizes of sections, 8, 57.
slope of batter braces, 7.
Limit of clear roadway, 6.
Li-t of data, 38, 118.
of mend)ers, 28.
LiM' loads, 5, Ti^i, 37, 126.
Ltiads, deatl, 6, ^2, 126, 156.
Toads, live. 5. 32, t,7, 126.
snow, 35, 46.
for wooden beams. 67 ; Tables xiii.,
xiv.
Lock luits, 22.
Loop eves, 20.
Lower end of post rc-cnforcing, 95, 142.
Lumber, amount per panel, Tables xv.-
xviii.
bill of, 115, 155.
list of members, 28.
iNLain diagonals, 59, 177, 221.
members, 55, (x).
Maintenance of bridges, 211.
Marking iron, system of, 192.
of dimensions, 180, iSi.
Material in struts, distribution of, 59, 64.
Materials, bill of, 71, 113, 114, 115, 151,
'52, 155.
tests of, 25, 26.
Measurements, method of recording, 180,
181.
Mend)ers, list of, 28.
Method of erecting a bridge, 196.
of (inding lengths of diagonals, 176,
of reccjrcling measurements, 180, 181.
Nfcthods of checking, 116, 181, 182, 198.
Middle of |)ost connection, 96.
Minimum dimensions of chord and batter-
brace plates, 14.
Xanic i)lates, 24.
Xeglccteil consideration in highway-
britlgc designing, 215.
Xumbc" of men recpiired for erecting
bridges, 1 17,
Nuts, 22, 115.
( )ak lumber, weight of, 6.
use of tables with, 61, 75.
Order bill, tinal, 185.
prelimin.irv, 183.
( )rnamental work. 141).
Outfit for draughtsman, 172.
for erecting-gang, 197.
Lacking, chord, 62, 81, 132, 179, 206.
250
INDEX.
i' |i
T';iiiitin!T, 25, 117, 209, 211.
raiifl lengtli, most economic, 38, 123, 12S.
of toj) chord, exact, 176.
rilc-drivcr, 19S.
Pilot mits, 84.
Tin bearing. 21, 77.93-
I'iiie lumlier, 6, 23, 24.
Pin holes, 21.
I'in pilots, 84.
Pins, proportioning of, 76, 85.
steel, Si, 83.
working bcnding-moments, etc., for,
Table xii.
Plant, 197.
Plate girders, 7, 19, 71.
Pony trusses, 7, 123.
Portal-strut connection, 99, 143.
Portal struts, 52, 54, 61, 65 ; Tabic xxv.
Posts, 9, 40, 41, 43, 45' 46- 59. 64. 133'
Posts, hand rail, 23, 67.
Post sections, II, 58.
Practical method of pin projjortioning, 85.
Pieliniinary order bill, 183.
Proportioning of batter braces, 63, 132.
of beam-hanger plates, loi.
of beam hangers, 75.
of bottom chords, 62, 66, 128.
of brackets, 103, 14'^-
of built floor beams, 68.
of chord bars, 62, 66, 1 28.
of counters, 60, 127, 130.
of details, 75, 86, 93, 136.
of end lower lateral struts, 65, 135.
of expan.sinn rollers, 103, 141.
of falsework, 19S.
of floor system, 67.
of hip connection, 95, 135.
of intermediate strut counection, 98,
144.
of intermediate stmts, 65.
of joists, 67,
of knee braces or knees, 103, 148.
of lateral rods, 14, 61.
of lateral-s'.ut connection, 99, 103,
143. 145-
of lateral struts, 61, 65.
of lateral systems, 60.
of lower end of posts, 96, 142.
of lower lateral struts, 65, 135.
Proportioning of main truss members, 60.
of middle of post connection, 96.
of pins, 76, 85.
of portal-strut connection, 99, 143.
of portal struts, 61, 65.
of posts, 64, 133.
of re-enforcing plates, 93, 96.
of rivets, 91.
of rolled beams, 71.
of rollers, 103, 141; Tables xxxiv.,
XXXV.
of shoes, 97, 140.
of side bracing, 7.
of sway br.icing, 61.
of top-ch<ird coimection, 94, 129.
of top chords, 63, 1 28.
of trussed beams, 109.
of upper end of post connection, 95,
MS-
of upper lateral-strut connection, gS,
143-
of upper lateral struts, 61.
of vd)ration-rod connection, 98, 105.
of vibration rods, 61.
Proportions for bars, best, 79, 80, 89.
Proposal, form of, 166.
(Quality of workmanship, 25, 166.
Ratio of width to depth of bars, 79, 88.
Recording of measurements, 180-182.
Reduction of ends of pins, 84.
Re enforcing plates, 16, 93, 96, 142.
Rivet heads, 90, 150; Table xxix.
Riveting, field, 24, 92, 125.
rules for, 17, 90.
Rivets, bending-moments, etc., for. Tables
xxxvi., xxxvii.
bill of, 151, 11/3, 192.
countersunk, 91.
diameters of, 15, 90.
in llanges of beams, 20, 107.
Rivet spacing, 18, 20, 107, 181.
Roadway, clear, 6.
ki)d>, eipiivalent lengths for upper ends,
etc., 1 1 5.
Roller plates, 16, 104, 146.
Hollers, 21, 103, 141.
I Rules for riveting, 17, 90.
INDEX.
25'
f main truss members, 60.
f post connection, g6.
85.
rut connection, 99, 143.
ruts, 61, 65.
^ 133-
ing plates, 93, 96.
I.
;anis, 71.
103, 141 ; Tables xxxiv.,
7, 140.
cing, 7.
icing, 61.
d connection, 94, 129.
(Is, 63, 1 28.
beams, 109.
ml of i)ost connection, 95,
ucral-strut connection, 98,
iteral struts, 61.
n-ro(l connection, 98, 105.
n rods, 61.
r bars, best, 79, So, 89.
of, 166.
kmanship, 25, 166.
to depth of bars, 79, 88.
neasurements, 180-1S2.
nds of pins, 84.
lates, 16, 93, 96, 342.
D, 1 50 ; Table xxix.
24,92, 125.
17,90.
^■moments, etc., for. Tables
cxxvii.
I, !</), 192.
nk, 91.
of, 1 5, 90.
of lieams, 20, 107.
18, 20, 107, 181.
r, 6.
■nt lengths for upper ends,
5-
1(1, 104, 146.
,3, 141.
ting, 17, 90.
Scales, 172, 204.
Sections, limiting sizes of, 8.
Sections of members, 8, 11.
Shearing-stress, -^-j, 80, 91.
Shipping-bill, 190.
Shoe connection, 97, 140.
plates, 16, 97, 140, 146.
Side bracing, 7.
sj/c.-. of floor beams, Tables xix.-xxi.
of hip verticals, Tables vi.-viii.
of joists. Tables xv.-xviii.
of lacing-bars, Table xxxi.
of lateral rods. Table xxv.
<if lateral struts. Table xxv.
of lattice bars. Table xxx.
of pillars for falsework. Table xxxix.
or pins. Si, 86, 134.
of portal rods, Table xxv.
of portal struts. Table xxv.
of rollers, Tables xxxiv., xxxv.
of sections, limiting, 8, 57.
of stay plates. Tables .xxxii., .\,\,\iii,
of vibration rods. Table xxv.
Skclctiui diagram, 40, 44.
Skew bridges, 3, 75.
Sleeve nuts, i r^.
Sliding expansion joint, 103, 104.
of pedestal, 8.
Snow load, 35, 46.
Spacing, rivet, 18, 20, 107, l8l.
Specitications, 5, 1G2.
general, 5.
on tile, 162.
Spikes 23, 151, 210.
Splice |)lates, 15,94, 139.
Star iron, 58.
Mav plates, 137; Tables .xxxii., xxxiii.
Sleel pins, 81, 83.
Suffeiied bottom chords, 11,62,66, 129,
-•15.
hip verticals, 14.
Milfeners, ic), 70.
Stresses on batter braces, 9, 41, 45, 52, 54,
12S.
on beam hangers, 75.
oil bottom chords, 41, 43, 45, 128, 215.
on brackets, 53.
on built beams, 107.
on chords, 41, 43, 45, 12S, 215.
Stresses on counters, 40, 45, 127.
on double-intersection trusses, 44.
on end lower lateral struts, 10, 54, 135.
on falsework, 200.
on floor beams, 73, 107.
on hip verticals, 41.
on intermediate struts, 51.
on lateral systems, 48.
on lower lateral rods, 49.
on lower lateral struts, 49.
on main diagonals, 40, 45, 125.
on pins, 76.
on portal rods, 51.
on portal struts, 51, 53.
on single-intersection trusses, 38.
on sway bracing, 61.
on top chords, 41, 43, 44, 128.
on trussed beams, 109.
on trusses, 3S.
on upi)er lateral rods, 49,
on ujjper lateral struts, 49.
on upper lateral systems, 48.
on vibration rods, 51.
Structure, test of, 26.
Styles of bridges, 7.
Sway-bracing, 9, 48, 61.
System of marking iron, 192.
Table of data, 38, 118.
Tee-iron, 19, 58.
Tensile stresses, intensities of, 11, la.
Tension, initial, 10; Table ix.
Test of structure, 26.
Tests of materials, 25.
Thicknesses of webs of channels, Table
xxviii.
Threads, 14.
Timber, 23, 25.
Tools used in erection, 197.
Tojvchord connection, 94, 129.
joints in, 94, 139, 179, 208.
panel length of, 176.
Top chords, 41, 43, 44, 63, 128.
Truss, economic dejjth of, 38, 124.
Trussed beams, 30, 72, 109.
Trusses, pony, 7, 123.
Trussing, 14, 103, 148.
Turn buckles, 22, 115.
Turning-in of channel llangos, 58.
I
252
LXDKX.
Units, 2.
Upper end of post connection, i6, 95,
faiscwoik, 104.
lateral rods, 14, 49, 61.
lateral-strut connection, 9S, 143.
lateral stmts, 9, 11, 49, 61, 65.
Upset rods, 14, 115, 165.
Vertical sway bracing, 49, 61.
Vibration rods, 51, Ci.
Washers, 22, 1 1;2.
Waste, allowance for, 68, 1S3, 190.
Web stiffening;, t9, 70.
thickness of. Tabic xxviii.
Weights of materials, 6, 6S.
of iron, total, in bridges, 35, 155, 156;
Tables i.-iii. I
of rivet hcatls, 151. 156; Table x.xix. !
Widths of flanges of channels, Table
xxviii.
Wind pressure, amount of, 6.
area opposed to, 6. 48.
effects of, 9, ^S, 99, 215.
Wooden hand railing, 23.
lateral struts, 10, 100, [49.
Working bearing-stresses, intensities of,
'3- 76.
bending-stresses, intensities of, 13,76.
compressive stresses, intensities nf
12; Tables x., xi.
drawings, 172.
loads for wooden beams. Tables .\iii.,
xiv.
shearing-stresses, intensities of, 76.
tensile .stresses, intensities of, u.
Workmanship, 25.
Wrought-iron, weights of, 33, 71, [31, i ;;,-,
156; Tables i.-iii.
INDEX TO ADDENDA.
f!cam-hangcr plates, 226.
Fioor-beam connection to foot of post,
228.
Floor-oeam stiffeners, 22S.
Foot of post connection to floor beam, 228.
Improved beam-hanger plates, 226.
Improved portal .strut connection, 229.
upper lateral strut connection, 228.
Lateral strut connection, 228.
Portal strut connection, 229.
Proportioning of beam-hanger plates, 226.
Stiffeners for iloor beams, 228.
40
50
_6oJ
70
80'
90
100
no
120
130
140
160
170
180
190
200
210
22cF~j
230
_240
2503!
'260 __j
270_|
280 Ij
290_J
300 1 1
f channels, Table
nt of, 6.
6, 48.
9, 215-
23-
100, r.|9.
sscs, intensities of.
ntensitics of,
'3.76.
ses, intensities of,
i\.
)eanis, 'ral)le>
.xiii..
intcnsities of,
76.
tensities of, i
of. 33. 71. '3'
' ' 5:>
A.
■onncction, 229.
coiniection, 23,S.
1, 228.
229.
langcr plates, 22IJ.
IS, 22S.
TABLE I
OT OF IRi
CLASS A,
18' Roadway
6pan„
rERAi. J Floor
STEM, 1 System.
40
20
50
20
60
"lO
70
- S7
80
-■;<
90
-4Q
.49
no
- 55
120
■5' .
130
- 57
140
'5°Z
- 61
160
170
i8o~
190
200
210
220
230
240
250
260
270
280
290
300
77
S4
86
86
80
^7
89
/i
fl
TABLE I.
TABLE OF WEIGHTS PER LINEAL FOOT OF IROr
GLASS A.
Span. 1
i
iKl^^aliS.
1-
: '43
12
Lateral
System.
Roadway.
1
14
Roadway.
16'
Roadway.
18
Roadway.
Klckik
System.
Limber.
193
194
1S7
'93
200
219
230
24.
D. L.
400 j
404
423
469 '
-ST3-I
Trusses.
I,ati;kal
System.
1 LOOK
Svste.m.
LlMUKR.
I). L. .
, 'I'mssES.
Latkrai.
SVSTKM.
Floor
System.
Ll'MUEK.
,D. L.
Trusses.
'53
192
184
'99
-'4 „
'» -» 1
-,)-
279
Lateral
System.
20
20
FiJJOR
System.
Lumber.
40
26
' 30
! '45
20
20
39
41
- ' /
21S
210
"217
407 j
'47
20
20
30
54
47
48
54
_ 74
54
242
244
443
4S8
500
526
541
575
636
266
50
16S
!54
161
-or
2:0
20
.50
'75
442 !
i 182
68
268
60
44
164
170"
30
52
57
459_
473
486
' '74
1^1 8rr^
200
221
242
266
233
::42
30
57
53__
4')
5S_ _
51 _
-_54 _
86
257
70
49
45
43
30
44
69
65
266
276
291
""
?0
::S
1S2
221
48
45
45
50
46
53
49
53
6f.
40
40
225
241
2(>9
25«
50 1 250
50 ! 26(')
47 1 308
'
90
29
522
5S2 "
64
'
100
43
30
39
41
39 "■
47
61
336
3'4
336
3'4
no
42
33
32
518 '.
240
2fxS
298
i 320
|_354
370
53
48
54
50
286
308
285
308
692
"714
754
779
f'3
120
44
55' '
2(^)
_25,S__
269
269
2|;S
6.5
644
295
330
48
51
3'7
l346_
~'374~
62
64
130
52
49
35
230
57S i
602
42
41
140
34
241
672
703
745 '
1 354
! 390^
i 389
4'3
426
461
491^
489
49
50
Al^
i36
150
— . —
44
55.
■ 69
74
7"
80
Ji _
286
77 7
-s
""79"*
Sr
Hi
83
83 '
84 _
Sli
>S()
<p
89
1
66
3'4
336
160
43^
5'
55
53
55
53
55
54
55
-3S8—
2S6
308
811
'822
Z857:
87C>
.^.922 i
90,5
_ 04('
962
1012
'053
1077
-__399_
440
_470 ^
_509_
S07_
549
' 587
621
661
603
739
780
"826"
872
1
64
170 '
!
;-_374___
395
424
74
45
43
67
3'4
180
-- —
t
72
75
26()
773 1
64
O9
336
3'4
190
—
1
45
25S 796 i
286
308
286
r 308
286
200
: i
7"
79
76
79
78
Si
67
7'
68
72
."^
73
1 72__
71
^ ■»
/ -
7'
336
3'4
_336_
3'4
210
-
!i 1
220
n 1
1
514
548
57S
230
, ! 1
240
— - - ■■
—
54 i .'^OvS
5; 3°8
"54 308
336
3P
3.36
250
,__j
—
641
260
i
1
80
2-0
280
336
336
336
290
i
i j
300
i
TABLE I.
:. FOOT OF IRON PRATT TRUSS HIGHWAY -BRIDGES.
CLASS A.
18
Roadway.
20
Roadw
ay.
LlMnER.
D. L.
22
Roadway.
24
Roadway.
Span.
<l)SSES.
SVSIKM.
20
20
30
57
^}_
4') *
49_
55*
St
57
= -54_
61
77"
-s
79 I
St
Si
~'^3"
«3 "
«5
S(p
' SC-
SI)
90
S9
Fl.Of)R
System.
68
Lumber.
D. L.
482
535
545
Trusses.
Lateral
System.
20
Floor
System.
Trusses.
_'59__
300
202
203
216
Lateral
System.
1
Floor
System.
Lumber.
1
D. L.
: 559
616
Trusses.
168
20^
Lateral
System.
Floor
System.
■ 87'""
105
1
Lumber.
D. L.
153
266
2f)8
-57
161
201
207
72
290 _
292
528
582
21
23
—
30
63"
S9
79
315
2 1
■_339
. 34'
327
600
' 664
40
50
60
70
80
go
192
21
81
90 317
22
I'''4_
86
30
100
82
78 ^
74
2S0
290
_30'~
325
628
646
-"683
743
116 304
640
..2'S
210
223
30
67
63
'.36
696
.■w_
6y
65
266
276
580
598
626
686
60
92
"89
3'S
663
.^'05 L_339 ^
113 1 -!';2
____7'o_ :
739 1
7S4
214
221
S'3
5'
327
681
23-^
64
61
291
336^
243
242
274
S3
52
56"'
86
86
" 89
88
35'
733
253
293
33<^
374
436
55
110
107
■"376 ""
249
267
SO
S3
60
.S9_
71
74
__364
34-^
364 "
__342__
404
382
807
834
53
60
58
66
,._.432
410
S-6 ,
911 :
966 ;
1009
100
279
63
3'4
__336__
3'4
^13''' '
70.1
75«
300
-335 __
372
„ J97
764
S06 i
841
: 8S4 "
3^3
"3
no
no
j 120
i 130
140
_-'5o__
160
3'7
62
72
350
391
388
404
..382
890
432
3t«J_
64
773
8r4
_75
63
9'
919
IIS i 410
.)'J9
6X
66"
72
__364__
342
62
69^
90
90 ' 404
93 1 382
93(>
966
"^''035
436
64
7'
"4 4.32
___"7 410
116 1 432
1028
1067
374
3'4
336
80S
"860
40c
41S
457
482 ~
66
75
876
933
957
—429 __
457
476
399__
64
85
88
87
73 3f'4
9>
95
404
502
^_ ^96 _
99
98
11.39
422
67
64
69
3'4
^_«7.-»_
912
77
74
342 ■
497
, 524
^. 93. _
92
95
93
96
._95_.
98
96
99
.98
lOI
100
! /°3^ _
101
382
1060
1108
1132
1189
546
120
119
410
116S
170
180
190
200
210
220
230
240
250
260
440
336
3"4
364 i
1000
95 ; 404
-_^?8 _,__382
96 , 404
576
621
662 "
662
696
'752'
802
_ 859,
.904
959
1002
1062
nil
432
I3l8
470
927
5'9
90
79 : 342 1
77 ; 3f'4 ■
1023
1076
io6i
I "3
5'''4
101
-9?
102
lOI
r .'04 ._
103
'03
106
^los""
'07
106
122 i 410
(247
5o<)
67
7'
68
72
7.1
0()
_72
71
^ ■>
/ -
7'
_ 336
3'4
_336_
3"4
336
3.3''
,53<^
336
986
968
1029
1051
1 103
"1149
1177
1230
554
555
589
"73
7>S
75-
798
84. _
892
93''
88
91
603
-605 _
644
12!
7_ 432 __
410
'307
1 291
',345
1384
507
So
342
_364
342
97
" 96
382
124
549
90
93
94
93
96
95
98
96
_ 77 _
404
1232
'23
432
5'^7
So_
ii4«
1190^
1250
1282
"1335^
'.375
•4.32
•472
, 6S9
733
782
821
874"
919
._973__
1020
loi 382
1263
'324
1380
1417
__'478
1520
1580
1623
125
124
139
_I26
'30
129
'32
'3'
_4'°^
432
432
02 I
78 3C4
81 1 364 ,
So 3f'4
83 : 3''4
_.98__._
102 ^
404
'453
i5'8
1558
66 f
404
Cm
loi 1 404
l-'°5 J '.404 ^^
103 404
106 404
.._4.32 __
432
739
1621
270
280
7 So
336
336"
336
1268
1318
1362
Si
"84"'
82
3^-4
3''4
3''4 '
432
4.12
432
1663
,S26
1727
290
,S72
104
404
'774
300
-1
-4
11.
F IRON ]
S B.
r'
—
Jway.
P_ .
SF
.M.
Ll'MllBK.
I), t
266
47v
1
ilkS
SK^
~257'^'
5 lie
266
55':
. =76__
56*.
2<)l
S'lk,'-
1
33<'
"5;
1
3'4
66',
1
_'336_..
7'.'.
1
3'4
7^'(
I
336_^.
7()»<
3'4.
78r
_ 336„
81;
3'4
82„
_336_
86;
3'4
J_87
3,V'
9"
3M
9a
336_
94
3'4
(/.
-
}i<>
100)
33'-
1 104!
1 3;"
10-
! ^;"
T 1 1
1, ',<>
1 I.)
' 1 iS
.;>'
u:
E II.
F IRON ]
S B.
r'
iway.
24'
Roadway.
Sf
Span.
1
1
,
<K
M,
!
Ll!MIIEK.
l>. I 1..
Tri.'sses.
I.ATHRAI.
SVSTKM.
^^:i^. '— ■
1). 1..
j
266
2(>S
257
266
276
2()I
•»7i33
5i;S9
S«io4
'43
' 184
1S4
'79
1 '94.
, 226
21
78
339 ^
341
567
• 129 1
(152
7C0^
746
_ 40
! 50
1 70
1 80
' 90
22
94
30
67
62
122
3=7_.
..3.W
352
376
SS'23
5fH44
5')l.S7 !
_ 94..
lOI
98 ■"
>>
- —
33(>
3'4
3.16
0570
66:9,
7 "41
200
297
327
53
60
58
96
101
43.2
410
^A3^
861
()09
100
no
i 120
9<)
432
-' —
3'4
330
3U
336
314
33*'
7-'<)5
i 3"S
64
71
103 1 410
105 1 410
<)40
988
r -,,89
1 ""10.S7'
1078
1 122
1144
U_'30
; 140
: .50 j
160
170
180
i 190
200
76te^
78^0
8 1 '162
82,S2
SO:25~
1«7:43
9 "03
397
409
43'
4(>S
492
t— S3?__
: 563
96
99
'■98
104
107
106
.432
410
I.432_
410
1 432
101
I0<)
- —
3M
3' 4
_9?!77
_ 94,28
•/"SI
564
596
641
102
lOI
104
III
410
! ii8i
'233
1261
210
1 220
: 230
no
432
112 1 410
33"
100J05
(>So
102
i '"
. . 432
1319
240
-'._
53<^
33"
104*52
10" Sj
1; 725
701
105
'03
i "5
1 "3
43-
1 ~ 1
1 10;,
250
260
,V,<'
1 . 1 ;,
807
10<)
! i.r, ! 4>'
1 .1 V '
7ro
2 ' ;,;(.
"4.<)4
842
.OS
i IIS 13-
' I4^'l
280
' ^\(>
I iiSiij
i, 891
'07
iiS t;,2
IS43
290
3 vP
122.48
9-''
10<l
iir 13-
1 s'^o
' 300 ,
1
—
TABLE II.
TABLE OF WEIGHTS PER LINEAL FOOT OF IRON I
CLASS B.
40
5"
60
;o
80^
90
;ao
'.10
:20
:;o
;40
oO
:6o
:-o
:So
igo
:90
210
230
240
2jO
200
2-0
;!,-.
250
ICO
197
2l6
48
44
49
30
29
32
239 !
2->2
3'
!
. 1
1
:
—
TABLE 11.
700T OF IRON PRATT TRUSS HIGHWAY- BRIDGES.
CLASS B.
IMAGE EVALUATION
TEST TARGET (MT-3)
//
&r #D ^' ///„
1.0
I.I
!lfiM IIIIIM
1^ IM 112.2
S l£ III 2.0
118
1.25 1.4 1.6
^
6"
►
m
^
1
//,
/y,
:^^»>>
/^
Photographic
Sciences
Corporation
#4
^^"'4
V
4^^
A
6^
%*■
'^^
23 WEST MAIN STREET
WEBSTER, N.Y. 14580
(716) 872-4503
ABI
OT (
CLA
18' R(.
Spai
rKRAL
Fi
40
>TEM.
SVJL
-
20
i"
20
•■
bo
JO
70
r 80
57
'
S<
40
♦y
♦9
120
55 '
5'
no
57 '
140
ISO
54
ibo
J 70
n
7S
190
'9
{I
200
U
220
<3
2,0
<3
240
^S
250
260
'4
^6
^(t
270
280
V
2qo
»7
^00
W
J
'9
' .
ABI
OT (
CLJ^
i8' R(.
Spai
24' Roadway.
Span.
rEKAL
iTEM.
40
—^-20
Kl 1
SviUMBER. D. L.
Trusses.
Lateral
SYSTE.M.
Sl^^il I^-B--
D. L.
315
536
139
21
71 339
557
40
60
■ 70^°
-80 57
-90 5^
-,oo»9
-..0*9
301
56s
172
22
85
„32S
327
594
50
304
593
172
172
30
no
629
60
_3'S
623
67
86
339
656
70
327
333
357
644
■83
62
92
351
681
80
665
210
55
89
87"
358
705
90
711
238
272
^300"^
53
38s
757
1 100
120 55
- .30^5.
.40 57 -
.50 5=*
1 "
100
341
357
736
60
92
366
78s
828
no
774
58
90
385
120
130
34 «
801
337
66
94
366
858
-357
832
862
3(>i
._ 64 __
7'
93
385
899
140
341
374
96
3(^
901
150
n
357
884
392
96
94
385
961
160
- 'r 'If"
341
904
425
99
97
366
9S2 1 170 II
,90 ^-f-
357
.341
933
958
998
984
442
98
96
385
1016
180
190
i 200
1 210
220
230
' 240
[ 250
1 260
' 270
280
290
30ft
t
481
lOI
99
102
101
104
99 i 366
1042
'2.0 ^i—
220 ■^ —
.. 357
34'
5"
98
385
1088
508
536
577
612
"653-^
68s
lOI
366
1072
.357
1023
1050
i094~
100
385
tii7
240 J —
" 2S0 "*
34'
•357
(02
366
385
1 144
102
101
104
1 195
26^ ^6-
J80 ^9
"290 *7
w »^ -
•9
.357
... .,357
^.'■38_
1162
ios_
'03
385
1242
102
'O5
104
107
106
385
1271
,357
,157
.._;357
357
1207
">235
727
106
385
385
.385'
385
'3'9
J.346
1399
758
804
105
107
1283
.35.
838
106
143'
TABLE 111.
TABLE OF WEIGHTS PER LINEAL FOOT OF IRO^
CLASS C.
12 Roadway.
14' Roadway.
16' Roadway.
18' Roadway.
Span.
no,c<:,-c Lateral
iRlSSts. SYSTEM.
sLr,. Lumber.
D. L.
Trusses.
Lateral
System.
i
D. L.
410
Trusses.
Lateral
System.
Kloor
System.
LUMBHR.
V. L.
Trusses.
143
Lateral
System.
20
Floor
System.
49
Lumber.
266
40 143 20
-5
'93
368
494 i
143
20 1 33
217
143
161
20
40
241
431
50 I'll 20
29
194
161
20
35
208
414
20
45
232
448
167
20
57
72
255
5o 140 30 42
187
389 144
30 47
210
421
148
•58
30
62
45
234
464
490
'58
167
30
57
257
70 I4.S 49
So 149 45
27
193
409 '53
52
37
217
451
54
241
247
249
272
58
54
266
271
24
198
409
158
48
34 222
455
166
50
42
498
S'2
545
_^79_
194
206
53
90 1J9 43 24
198
418
170
181
45
34
223
465
181
47
42
49
49
52
274
;oo 169 43 23
217
446
45
32
245
497
'93
47
39
49
301
no 180 48 26
206
455
•97
50
34
232
S08
213
S3
42
257
560
23'
55 ' 52
290
120 198 44 25
217
479 1
219
46
32
245
_53Z-__..
559
239
268
48
40
272
594
256
St 50
_30'_
290
130 JI9 52 28
206
500
244
260
285
298
S3
35
232
245
__-32._
245
54
43
_==57__
272
257
272
617
284
57 53
140 :-!,2 49 27
217
520
49
34
S«3
289
49
42
647
301
54
51
301
290
-_J°'
150
53
66
36
601
3'6
55
45
668
327
61
54
160
35
639
11'
69
43
710
344
77
52
ro
3'8
74
37
., 232
656
33'
74
46
44
257
272
703
729
343
78
SS
290
ibo 1
; 1
3>8
72
75
35
245
665
342
76
35<'>
79
53
56
30 '
290
:qc
j
340
37
232
679
370
80
46
257
748
409
81
81
200
390
386
76
44
272
767
763
54
301
210
!
79
76
46
257
405
426
83
83
57
290
220
230
1
405
45
272
793
810
55
301
1
433
456
79
46
257
457
483
5'5
538
85
84
86
^ SO "
^)
87
58
290
240 1
1
78
81
45
272
846 j
878
^ 897
56
301
250
1
484
46
272
272
59
301
260
1
505
80
45
56
59
_30'_.
301
270 '
280
1
1
! 1
574
603
638
668
i
1
1
1
1
1
57
301
301
301
290
90
89
59
57
300 <
1
1
TABLE 111.
. FOOT OF IRON PRATT TRUSS HIGHWAY -BRIDGES.
CLASS C.
i8' Roadway.
20' Roadway.
22' Roadway.
24' Roadway.
Span.
USSES.
Lateral
System.
20
Floor
System.
49
Lumber.
266
D. L.
465
Trusses.
Lateral
System.
Floor
System.
Lumber.
290
D. L.
— . , 1
Floor
System.
Lumber. D L.
Trusses.
Lateral
System.
Floor
System.
Lumber.
D. L.
'43
146
174
168
20
60
503
530
148
21
! 64
315
536
139
21
71
339
557
40
ib7
20
30
57
255
__4_89_
21
67
278
178
175
22
74
301
565
.72
22
85
325
594
50
60
iS«
72
257
507
30
83
280
551
30
94
304
593
'72
172
30
110
327
629
ib7
57
58
266
540
172
60
68
290
582
177
63
76
315
623
67
86
339
656
681
70
80
'79_„
53
54
271
55°
562
599
623
•83
204
56
64
295
591
190
59
75 1 327
644
'83
62
92
351
!94_
49
_ 52
274
5'
62 308
618
2T3
2:^b
S3
73
333
665
210
55
89
87""
358
70s
1 90
206
49
49
301
225
254
SO
58 329
656
52
70
357
711
238
272
53
385
757
100
23'
55 1 52
290
56
61 1 3'6
682
269
58
73
341
736
60
92
366
785
828
no
256
5' 50
301
653
277
53
59
329
3'6
713
738
294
56
72
357
774
300
58
90
385
120
130
2S4
57 53
290
679
305
60
62
327
63
75
341
801
337
66
94
366
858
301
54
5'
301
290
702
322
59
59
329
764
344
62
74
357
832
862
363
64
93
_J85_
899
140
150
327
61
54
_„348_
66
62
_3l6
_ 7l7
380,
69
77
34J
374
71
96
366
901
344
77
52
_JO'
769
337
365 '
379
85
60
329
806
367
90
75
357
884
392
96
94
385
961
160
343
78
55
290
761
88
63
3'6
827
397
93
92
78 1 341
904
425
99
97
366
082 i
170
3S^>
79
81
S3
S6
301
290
784
808
87
61
329
851
412
77
357
933
442
98
96
.385
ior6 ;
180
3SO
411
90
04
316
876
447
95
80
341
958
481
lOI
99
366
1042
I go
409
81
54
301
840
"830
436
88
62
329
910
475
93
78
81
357
998
5"
99
98
385
1088
200
405
83
83
57
290
432
9'
65
3>6
899
47'
496
533
96
341
984
S08
102
lOI
366
1072
210
220
230
240
250
260
270
426
55
30'
860
455
90
62
329
931
95
80
357
1023
536
577
lOI
100
385
i"7
457
85
58
290
885
489
93
65
3'6
958
9,8
96
83 34'
1050
104
102
366
"44
483
84
86
86
" »<;
87
56
301
919
553
91
63
66
329
329
996
1037
565
81
357
1094
612
653
68s
t02
lOI
385
"95
5' 5
59
301
956
976
94
603
630
669
99
9^^
lOI
84
82
_3S7_
357
_"38_
1 162
105
'03
104
385
1242
53'^
56
59
30 «
30 •
577
93
64.
67
329
1059
1 100
102
105
385
1 27 1
574
1019
612
96
329
85
357
1207
123s
727 106 1
385
I3'9
603
57
30'
1044
644 95 1
05
68
66
329
329
tI29
1173"
700
742
100
«03
lOI
83
357
758 105
104
38s
385
385
'346
280
638
90
89
59
57
301
30 '
1084
(III
682
98
86
357
1283
•35'
804
107
107
'.399
143' 1
!
2go
668
713
96
329 raoo j
774 j
84
357
838
106
106
30f>
\
niBMIMIMIf
TABLE IV.
ECONOMIC DEPTHS AND
PANEL LENGTHS.
Span.
So'
yo'"
100'
No. of
Depth.
Panels.
SlNC.l.K
NTBRSECTION.
Dnimt.E
NTEKSKCTION.
5
5
S
6
16. ?'
18'
-
20'
no'
120'
21'
6
21'
26' .^
'30'
.40'"
'50'
i6o'
.70'
i8o'
.90'
200'
210'
7
22'
7
23'
8
23'
26'
8
9
24'
27'
29'
26'
9
27'
30' _
32'
' 33'
34'
35'
10
! 10
i
220'
-'30'
"240'
250'
260'
270'
280'
290'
I II
' 12
36' ^
12
38'
^39'
13
'3
40'
14
14
'S „
'; '5
41'
■ 42'
; «' - --
44'
1 .
PI
m
£>i>.''%tiLE£££M»
TABLE V.
ECONOMIC DEPTHS AND
PANEL LENGTHS.
Span.
.So'
90'
100'
No. of
Panels.
1
Depth.
SlMil.R
Intkksh niiN.
If).!'
IS'
DoiiBl.E
Intkkski rioN.
5
5
5
20'
no'
120'
1 ,?o'
140' '
5
81'
22'
22'
23'
24'
25'
5
6
6
26'
'50'
\(yo'
i;o'
i.so'
190'
200'
2 1 o'
220'
2 ;o'
2.(0'
250'
2(X)'
7
27'
7
S
8
2.S'
27'
30'
2S'
32'
34'
35'
36'
9
10
10 ~
37'
P'
10
1 1
1 1
40'
■
41'
42'
270'
2.S0'
2()0'
JOO'
13
12
'3
13
43'
44'
4.S'
4(/
MHi
'%
''^^^S
A
■^B c- -
n
1
9f '
II
*
m\
'
-xlpl-
-n
TABLE <
In which tlic
wDfkiii^-strcs
The uppc
;i()iis ri<iuii"C(
Panel '*
Length. RoaJ'
IC
0.01
i.oo
/
2 r'
12
1.09
'-- li
13'
l.iS
1
/ i
2 \%
14 !
1.27
„
f
2 4
15
\
i.3(.
' 16'
a r
\
1.45
/
2 V
«7
'•54
18'
2ir
..64
; 2 ij'
19'
'■7.^
'21"
20'
i,S4
21'
- '"
I.V5
2 lA
2.07 I
23'
34'
h'.1
: 'I'
2.29 I
I
\
TABI
111 whic
\\iiikii\i^
The
;iiiii.s tl'i
Panel
I
>3'
'4'
'5'
i5'
17'
18'
'9'
I ^
23
\»
\
24
TABLE VI.
TABLE OF SIZES OF HIP VERTICALS FOR BRIDGES
OF CLASS A,
III which thi' hvt,' load i>. owe liiiii(lr(.'(| pdiiiuls ]n-v st\udiv foot of tioor, ami the
\\nrkiiij;-.strt'ss on the verticals is lour tmis to liu' s(|iiarc inch.
'i'lic ii|>|»i'r fi,L,Mircs i;ivi- the sizes nf the hi|. vi'ilicals ; the lower ones, the sec-
; idiis mniired.
Panel 12' I4' 16' 18' 2o'
Length. Roa Iway. Roadway. Roadway. Roadway. ; Roadway.
ic
•3'
'4'
■5'
16'
'7'
18'
'9'
-• I "CI
0..JI a"
2 fn
1.00 □"
J i"G
1.09 n"
2 H"a
I.lSu"
2 ir'u
1.27 a"
22
23'
24'
2 S'a
1.36 a"
2 ;"a
1.43 a"
2 iru
1.04 a'
2 \Va
2 1" □
r..S4 a'
J l"U i
-■ 'yn
2.0; CJ" J
2 i.'.'a'^r
2.i.sa" I
2.2() n" I
2 fn
i.ooa'
"2 fro"
l.lfjD"
2 H!"ir
1.26 D"
2 fiT
1.370"
2 i"a
1.48 D'
2'-B''d
i.SyO"
^ irn
I.2I D*
1.33 a'_
1.45 u"
2 5" □
i.3sa"
2 !?□
1.64 a'
2 rn
1.51 n*
2 H" □
1.69 a'
2 i"D
i.SoD"
2 i"a
1.91 a"
2 r'a
2.02 D'
2 ii^B'a
2.14 D'
■nra
«.sf» a"
2 n"a
i.fxSd"
2 I'D
i.Si D»
2 I'D
j-gin'
2 ^ya
2.0s a"
2.r7 a"
2 . r D^
2.29 D"
77i"a"
2.43 D'
2 ir'D
1.77 a''
2 I" a
1.90 a*
2 ■,>-," n
2.04 D"
2 lya
2.18 a"
2 iji"a
2.32 D"
• 3 \ra
1.66 0'
2 i"q
1.S1 D'
2 I" a
1.95 D"^
"2' I, "5" a
2.10 :!"
—— -n
22'
24'
Panel
Roadway.
Roadway.
Length
2 ir'D
1.67 D'
2 i"a
1.S4 a"
10'
2 I'D
2 I'D
U'
1.84 D'
2.03 n"
2 r'a
2.00 a'
2 ■,',''0
2.19 a"
12'
2 ii»»"n
2.16 D"
2 li'a
2.36 D"
13'
2 li'a
2.32 D"
2 ii"o ^
2-53 D" •
2 ii"a
2.27 d"
7 .l"a
2.40 D"
2 il'a
2-53 □"_!
2 ift'a !
2.6.S a' I
2 -A" a
2.-,SD"
-• '.Va^
2.73 n"
2 ri"n
2.S7 □"
I7i" a""
3.01 n"
: 'i"a
I ,i6 a"
2 iiV'o
2.(>i a'
2.760"
2 i}"a
2.92 n"
• 2 i^"a
3.00 a"
2 lA'D
3.27 D"
2 1 ■■'. " n
2.71 c"
2 ii"a
2.s6a"
2 lY'D
3■°^ 0"
2 iA"a
3.45 □"
2 .ft' a
"2 .ft ''"a"
3-3" n "
2 .J" 7^
2 iT'n
3-74 o"
2 iV'a I
2.99 P" ;
2 «ft"a
3-1'' O" I
2 .ft"D 1"
3.34 □' I
3' 54 CJ" i
"'2 If a I
3v4 G" '
2 irt"a '
3.95 □" J
2 T^"a"'''
4.16 a"
3'27 D"
2 .t\,"a
3-4('0"
2 .r'a
2 <i',"a
3.87 a"
7irt"n
409 a"
2 il"u !
4.3; o" I =3
«7'
18'
19'
20'
21'
22'
2 li'a
4.56 n"
24'
TAB
In \vh
uiukir
Ih
I Kills r
Panel
Length
! II
13
14'
■5'
16'
17'
i 'f
■9
12'
23'
TAB
In wli
\\(M kir
Th
h Ills r
Panel
l.uiiKth
I
12
! '3
I -
; 14'
'5'
16'
! '^'
J -s'
'9'
^3
J '1
TABL
lii whict
uMi kino-.;
The 1
tiiMis rccj-
! Panel
Length.
10'
I
! «i'
12'
I 13'
>4'
■^ 1
.6' I
■7'
1 8'
19'
22'
■!3
-4
TABLE VII.
TABLE OF SIZES OF HIP VERTICALS FOR BRIDGES
OF CLASS B,
In which tlio live Io;ul is one huiuhcd pnuiuls per sciuare foot of floor, and the
udikin^-stress on the verticals is ti\e tons to the stjuare inch.
The upper figures ;4ive the sizes of the hip verticals ; the lower ones, the sec-
' n'lis recpiired.
Panel 12'
Leng
'4
i6'
10
! II
I 12
^3
'h. Roadway. Roadway. Roadway.
I8' 2o' 22' I 24' I Panel
Roadway. Roa.lway. Roadway. ' Roadway. I Length.
2 r a
0.72 a"
2 i"a
0.79 a"
2 f''a
0.86 a"
7 i" a"
0.94 a"
2 fa
1. 01 a"
2 fa
i.os n"
2 \f,"a
t.isa"
2 ir □
1.30 a"
- 5' a"
I.^SC"
Ti'~a~
2 f n
2 f n
0.84 a'
0.96 a"
2 fa
-' fa
o.(;2 a"
1.06 a"
2 fa
-^ f,V'n
1.00 n"
r.isn"
i.os a" '
'2H''"a~\
1.17 a" i
:: H"o •
1.260" !
1.35 a"
- \ro
1.24 a"
2 i"a
1.34 a"
7";" a
■-t-1 g"
I r.09n"
'■ - ircTT
1.20 D" I
I '-.i' g" :
1.41 g"
2 l"a
i-s-g"
■: W'a
t.02 n" ,
2 5" a
i.43_g"
2 I'a
I.S2 a"
..61a" 1
1.71 a" : r
I I.
■'g
.•>•> g"
2 {>"a
- i.V'g
1.74 g"
2 i"a
1.830"
2 I " a
I. Si a"
: i"a
1.91 g"
2 I" a
2.01 D"
7 ..'.rg"
2.11 a'
2 j''a
1.54 g"
1. 04 a"
1.7 ya"
2 \"a
I. S3 a"
2 I" a
r.94 g"
- i,'.i"D
2.00 D"
- 'rV'g
2.1S a"
2.29 a"
2 H'-a \
r.7jg" I
2 I" a
' ''Ssg" !
I 2 i"o
S 1.9CD" '
2.07 D"
I 2 i^,,"n ■
j 2.ic)n"
I 2 ii"o
r - <rc! '
I 2.4C n"
I 2 t^"a i
I 2.60 n" ;
I.. -2 0"
- r^'
2 (" a
1.44 aj'_
- I.; -
'•.=i5g"
Ijrg"
1.67 a"
: i"D
i.SoD"
2 i"a
1.93 a"
:.05 D"
3.17 g"
^ ■r'g^"
.:.J9g"
: il"g
:.12 n"_
- iu"g
-'•57 g"
2 V'a
^•34_g^'
2 rg
'•47 g"
2 n"a
'•59 a"
2 l-r' a
1.72 g"
2 I'a
..85 a"
2 i" a
1.98 a"
2 i^'a
2.12 D"
2 r,',,"a
2.26 a"
2 .i"g
2.39 □"
2 i\"a
2.53 a"
2 r'g
'•45 □"
2 [fa
i.()o a"
'•74 a"
2 i"a
1.S8 a
10'
II'
12'
2 ra
2.02 a"
2 'I'r/'g
2.16 a"
2 ij"n
2.31 a"
rrfa
2.46 a"
» , '3
14'
15'
16'
'7'
2 'I's'g
2.61 a"
18'
2 ii»,"a
2.67 a"
2 If a
2.83 a"
2 !,'.."a
2 If a
3.00 D"
2 -i' n
j.sr, n"
2 'I'/D
3-'7n'
- 'fa Lj
2.76 a"
2 i|"n
2.<)2 n "
2 if a
3.01)0"
2 i^f a
19
3 2S 0"
2 'A'g
147 D"
'a
-'.41 n"
2 'I'/g
2.-4 n"
2 «l"a
?3 C
2 iT'g
3.65 o"
22'
23'
24'
I
\'
lo'
II'
12'
13'
14'
'5'
16'
'7'
iS'
as'
22'
23'
24'
ffc-^i
TABLE C
In which the I
"tress on the
riic upper
tiiiiis reciuired.
Panel
12'
Length.
Roadw
lo'
2 f'l
0.60 Z
II'
2 :l"i
o.()5 C
12'
2 f,
C.71 C
13'
, ,i
:: •}"[
14
'5'
16'
>?'
18'
■9'
o.S;, C
2 I" I
0.S9 C
2 I" I
- I I
I I 01 c
-r'i
1.0; c
- 1
1 . 1 ;, C
-■ U"
i.-'>. C
23
24'
- 4"
i-ll C
I.;;
I
S M M ii * ^
im
r
Panel
Length.
i
1 10'
: ii'
i
1
■ 12'
'3'
>4
'5'
i6'
1
18'
'9
20'
2!'
-
^Itf^^
.*.-«
TABLE VIII.
TABLE OF SIZES OF HIP VERTICALS FOR BRIDGES
OF CLASS C,
III uhk-h tlu' live loail is cii;hty pDunds per square foot of floor, and the workinj;-
-ircss on the verticals is five tons to the sciuaic inch.
The upper figures give the sizes of the hip witieals ; the lower ones, the sec-
tions retiuired.
Panel
Length. [ Roadway.
10'
'4
Roadway.
'3
'4'
'5'
,,r\ 2ro
o.<)5 n"
2 f n
o.fx3 n"
2 r a
0.6s D"
2 fa
0.690"
0.7 s D"
2 }"n
C.71 0'
2 i" a
0.S2 n»
2 J" a
c.77 □"
2 fa
0.S9 n"
2 |"n
0.S3 n"
2 f n
0.S9 n*
2 }"n
0.97 D"
2 }"n
1.04 n"
2 fn "
0.98 a"
2 f □
20
Roadway.
2 f n
1 .CO G "
2 I'D ""
1.10 a"
22' 24' Panel
Roadway. Roadway. | Length.
2 fn
1. 12 n"
'7'
18'
19
23
24'
2 f a
MI n"
.11 n
13" □
.19 D"
- I" a i
i-oi n" j
1.07 n" i
2 fa '
1.13 D" I
- ira
1. 2 1 n"
2 fr'D :
1.2S n" i
—r, 1
- 4 n :
r.;,6n" i
2 i" □
'•44 a"^ j
- Vn
-^ ira
1. 18 D"
2 H'a
1.25 a"
2 IT a
1.32 D"
-^ V'a
1. 41 a"
'^
U
"n
1
J7
□"
2
i
•a
1
35
a"
2 I" a
r-jon"
r.jS a"
- ir"~a'
1.67 n"
2 r'a
1.4,5 a"
2 i" a ^
1-5' a"
2 1 .i " n
- \ro
1. 7 1 □"
2 1" n
1. 8 1 n"
2 !"□
1.90 n'
2 i"n
2.00 n"
1.07 D"
=^lra~[
1. 16 a"
"2H"a'^:
__>;=s_a"_;
"2 fa \
'•34 g" j
2 fa ^"'
1.42 D"
2 U"a
j 1.22 D"
2 \r a
^■j3 a"
2 i"n
1.43 a"
2 i.rn
1.20 ;"
2 ii'a
1.3, Q'
2 j'T
1.403"
2 j'a
1.50 a"
i.io Z"
10'
13'
2 r'a !
1.54a" !
r^r'^a
1.65 a"
1. 51 a" t
2 H'a
1.70 a"
- Kra
I 1.(0 a"
I ^fr a
I 1.70 a"
[ 2 I " lJ
j I .yo o "
\2 i"'n
I 1. 91 D"
2 i"a
2.02 a"
2 13
1..S1 3"
2 ra
1.02 a"
2 i,vF
2.03 y
^ 'A' a
2.ir,a"
2.2S 3"
3fr'a
1.76 a"
2 i"n
1.87 a"
2 i"a
1.99 a"
2 'h"a
2.11 a"
16'
2 iiV/'a
-_--3p"
'2 7j"a"
2.36 a"
2.50 a" j
19'
ar
aa'
2 'A" a i
2.13 a" _
- 'i's"'J
2.24 n"
2 IJ'D
2..10 a"
"2 iyp7
2.~: -J"
2.64 D"
T^h"a~
2.rs G"
If ^-M,
II
12'
«3'
14'
'5'
16'
11'
18'
19'
20'
23
Sl»— w™.
TABLE C
In whicli the
stress on the
The upper
tioiis re(|uire(l.
Panel
12'
Length.
Roadw
2 f 1
10'
0.60 C
II'
2 i"i
0.65 C
12'
2 r'l
0.71 c
13'
2ri
t.77!:
,^'
2 ft
«5'
16'
»7'
18'
19'
20'
23
21'
o.S;, C
' 2 f~|
0.S9 c
" 2 r'l
0.05 c
-• I" I
I 01 C
3 f 1
1.07 c
■. Iff t
- ( '
1 . 1 ;, c
i.-M r
- I.i"
i.jS z
2 l"\
- v'
i-tt c
t
1 .4^
■>-^*tf?%;^;.,<*''Mj&?--
I
10'
II'
'3
14
'5
U-
17
18'
19
20
23'
h
^"'-^^^MiV^iUj/^^
TABLE VIll.
TABLE OF SIZES OF HIP VERTICALS FOR BRIDGES
OF CLASS C,
111 wliii-li the live load is eighty pounds per square foot of floor, and the workinj;-
>tress on the verlieals is the tons to the si|u:irr null.
The u\)\)vv tijiurcs give the sizes of the hip \iitieals; the lower ones, the sec-
tions reiiuired.
Panel
la'
Length.
Roadway.
10'
2 f D
0.6o D"
II'
2 fn
0.65 n"
12'
2 f □
C.71 D"
'3'
2 fa
<-77 □"
14' I 16'
Roadway. Roadway.
«5'
16'
«7'
1 8'
19'
20'
2 fa
: 0.S3 a"
' 2 f "ni^
0.S9 n"
2 fa
0.1)5 a"
2 r'a
r 01 a"
- _ .
2 fa
2 fa
o/k) a"
0.79 n"
2 fa
2 f n
0.7s a"
0.S7 n"
2 :t" a
2 fa
0.S2 a"
o.<>5 a"
2 fa
2 fa
0.89 D"
i.oj a*
2 ^"0
2 fa
0.97 n"
...in"
2 fa
2 ir'n
1.04 a"
1.19 a"
2 fa
1.07 a"
2 }*"□
1.16 a'
2 H"n
1.25 a"
23'
21'
2 fa
1.07 a"
. 1 » r-i
- I ■'^
1.1;, a"
2 vrn
I.-' I n"
- \Va
i.jS n"
2 r'n
I. Via"
- i"n
i..t.t a"
2 fa
I. II a"
1.18 a"
7]ra"
1^25 D"
1.32 a"
2 fa
1.41 □''
"2 r □
1.50 n"
2 U"a
1.27 a"
T 2'"j"a^
' 1.35 a"
1.43 a"
•l"o
r.si n"
- ir'n
i.(.i n"
.71 a'
'n
I-;;
2 !?,"□
1.5'^a"
2 ira
i.f)7 a"
a ir'a
1.7 ^ n"
2 i"n
I. Si a"
2 I'a
up a*
2 I" a
J. 00 n"
2 jf a
1.70 a
2 r'n
i..^'o n"
-• r'a
i.yi a"
2 ra
2.0; a"
2 1,^5" a
2.13 a"
2 \i\-,"n
2 irV.'n
2 I A" a
2.0.5 □"
2.23 a"
2 i,'«'a
2 ira
2.i()n"
2.36 a"
2 ii"a
2 If a
2.2S -"
2.50 a"
2 ifn
2 I h"
2.40 G*
2.64 a"
2 if a
2 iA"n
^ ~ ■, ^f
2.7S r,"
2 if a
vo.^ n"
.... .,.„*.-* v...i.
In
tlic
In
the
!
f
it a
Ji,
1
TABI
In tons of two ti-
the initial tension
u
Intensity
OJ
Stress =
E
Q
r
i.2r)S
\r
1.451
i" \
1 .650
n" i
1..SS5
i" 1
J.140
■i^"
2.423
"S"
2.726
' 1 i "
3.057
-1"
3.40S
' xV
3-7S7
4.190
4.f.i7
1 ',"
; -k" i
5.o(xS
5-547
■ 1.1" :
6.04(>
6-573
If 1
7.120 '
ij-r i
7.fK)5
, 1 i '■ '
S.294
' iir' !
«.9»7
j" '
9.568
-'^"
10.239
A"
' 1 o.( );;S
- 1 •'
11.057
1 H" ^
1 12.404
! -'ft" ,
i '3-'7S
--r'
1 '3-')70
,7 »
-Vfi
' l-~'t,i
A"
1 vl>-,"
■■•"*«•#<.■
■ TABLE IX.
TABLE OF GREATEST WORKING STRESSES,
]n tons of two thousand (2,000) pounds, on adjustal)le round and square rods, exclusive of
the initial tensions ; also the initial tensions.
u
e
Q
f
7 "
!i"""
'A"
■i"
' iV
ti"
1 1"
'}.'." 1
i|r' ;
If 1
1;' '
- 1 •>
> * ''
- 1.1
-i" '■
-h"
-]'■•<
-V
Intensity of Working
Stress = 4 tons.
1
Intensity of Working
Stress =; 5 tons.
Intensity c
Stress -
©
)f Working
7.5 tons.
1
Initial T
ensions.
u
it
1 1
Q
J"
liV" '
"I"
i w
; 1"
I ifV
,''^""
■ i"
i ';v' "
1 •-, ■,» —
; 'H'
'f
'iii' ,
1 ij" " 1
! 'H"
i 2i"
2^"
I 2 A"
! 2i" '
2,\" '
u
01
1. m
3-574
4-'57
4.789
5-4:^i____
(1.230
I 7-0.38'
1 7.904
r 8.830
9-814
10.850
j 11-956
1.3-117
®
—1
I.26S
~ '-45'
1. 6 so
2.140
2-423 "
i-5'7
1.710
2.178 '
2.507
2.815
.3_-76o
4-303
.|.S(K5
6.205
6:931 "
0.500
: 0.025"'
0.63 s
0.794
0-953
1.846
1 1.970
2-257
2-576
2.927
3-308
3620
4.163
2-875
.3-284 __
3-730
j 0.750
! 0.875
1 1.000
2-405
2-730
3.0S7
1.111
1.270
4.216
1.125
1.429
2.726
3-476
4-740
1.250
1.588
1.746
3-057
3-»94
5-305
1-375
1.500
1.625
3.40S
3-7«7
4-347
4-636
5.140
5-675
5-908
„iL'5S0__
7-2.10
7-95'
8.710
7-704
s-523 ~
9.3«7
10.29S
1.905
2.064
4.82S
4.190
5-341
1.750
2.22*1
4f'i7 S-*^'^!^.,
5.o(kS 6.4(0
1 6.240
6.836
1.875
2.000
2 381
2.540
"-253
'4-335
5-547
7.065
7-463
9.508
12.256
15.611
16.947
, 18.342
2.125
2.699
6.04(1
7.706
8. 119
'0.345
^„.i3^P4___
15-540
16.726
2.250
2.858
3.016
6-573 8-.376
8.8aS
11.223
2-375
7.120
9-077
y.8io
10.571
9-527
10.276
12..38
19-794
2.500
2-625
3-3,i4
3.493
7-(m
13-092
21 .305
22.874
8.294
8-9' 7
' 9-5('''^
10.239
11.056
14.085
17-959
_i'>237
20. 5(1 J
23-3-1')
24.811J
2(1.321
20.476 _
;j.Si ;
2.750
3.000
'i-36i__.
12.190 1
11.867
1 vl iS
24.503
2(1.190
3.651
3.810
12.708
13-580
14..,83
1 '5.4'7
16.380
'7-.?75
18.400
'9.457
1CI.|I)0
17.300
18.450
i<).f)40
~ 20867
_22.23S___
23.440
24.780 i
-'ii.i;o
13-047
27.935
29-7,39
31.003
' 3.3.524
3-125
3-250
.3-.375
3-500
3-969
4.128
4.2S(,
4445
4.604 __
4-763_
4.921
5.C80
! io.<)3S
1 1 -657
12.404
'3-936
14.854
.5,807
1 13.17s i I6.7S8
1 35-504
3625
3-750
__3:S75
4.000
1 3.()70
1 v'.;(.
17.801
_j8rs4T::
37-541
3<).(i40
41 r'ls
I
4"
1
'
L t
2
2
2
2
^
INIANNEL STRUTS.
Ratio,
/, to D.
IHii S)®
Ratio.
A K. /'.
64
64i "
65
66
^■'..
10
loi
1 rr"~
1 ni
4.20! i.4t9
4-I4! 1-377
4.1 M i-3S6
4^oS: 1.335
4-05,: i-.VS
4.02^ 1.296
3.99.; 1 .276_
3.96; 1.256
3.901 1.219
3.S7: 1.200
3.841 1. 182'
3.Sii 1.165
_3-7'^' '-M-S
1.569
'•553
'•53«
'•523
12
id
'5
■5i
i6
17
1-508
66.i
67
67.1
68
68i
'■493
1.479
1.464
1.450
'•435
6.ji
70
1.421
: '-407
'■393
70J
71
'•379
1.366
I7J !
_,V75> '•"30
■'■"-' _L-1' -3 „
3(19; 1.097
3.61 >; i.aSi
3-63: J .064
3.60; 1.04S
7..L.
72
' 7-^
73 '
1 73.'
i 74
'•353
IS
"' i
iM-i
20
1.340
1 1-3-7
i-3'4
1.301
! I.2S8
.-ol
x"' i-o.v'.
:\':
'•-"n
::i
21.1
21\
,1-5 1. i-oi.S
y\\.. 1.003
3 |Si o.<)SS
;,.',;' o.>);(
I 75r
"7C>
7'V, ,
1.2(13
i"'-\si
: 1.23S
1.220
j -xi
3.-IJ' 0..)()0
7'^ J
I.2r4
1.202
! -M
3.31K 0..)', i
7S
i.itii
-'■t'
.l-viC O.')J0
- ^ ,
1.171)
^5
3.311 o.i)07
3.2S: 0..S94
3.2^; o.S.sf
"'1
s<->
1 . 1( i.S
1 1 V
I.I |(.
27 1
1 - 1
5.2 2( O.SuS
319} 0.856^
3.r-( o.S(.|
S.i
Si
Si
1.124^ 1
1 , 1 1 1
tj ® i ® I
1. 130
I.! 16
1. 102
I .aS8
'•075_
1 .0(32
'•04 9
1.024
I.OII
O.IY)')
o.(j87
0-975
0.96;,
0.951
0.939
0.()2S
0.1)17
O.(i0li
o .S>)5
Jo.SSs
0.S7.1
o.si).)
0.S54
o.S.14
o.S-vt
0S24
o.S 1 4
0.S05
o.7')5
0.780
0.-77
o.7(i.S
<\"5>.)
0.750
0.741
0.832
0S20
0.809
0.797
0.786
_°-Z75.
0.765
0-754
_^-Z44
0-734
0.724
0-7 '4
0.704
0.f)<)|
o.'iS5
r.676^
0.067
1.658
0.649
0.640
0.032
0,02 I
0.01 (}
0.60S
0.600
0.592 ■
0.5S4
0-57*^
0.569
0.5<i2
0-555
0.54S
o. 5 ) I
05.il
0.527
0.^20
I
^Ha
, '^■-J^:'~ '/»«»i«»**««i«***"
INTENSITIE
Ratio,
A to D.
Uti
1 !%•
O d
10
1
1
4.205
4- 140
3.900
i 10^
4±75
4-103
3-'M7
~\\
i 4-145
; 4.066
3-')04
Mi '
4.IM
i 4.029
3.S(,2
i:: 1
^__'»:°L^5
' 3-993^
3„Sm
I2i
' 4-05;,
i 3-95^'
.5-775
'.)
i_i:°f3_^
1 3-9 '9
3-73-
'■3L..:
3-993
3.8S2
3.aS,S
i '"*
,Vr/'2
,?S45
3-<'45
'-(i ;
,v93- '
3-«07 1
3.()0i
'5 i
3.901
3-770
,._3-557
'5i :
3-.S72
3-732
3-5'4
■ K)
;vS4>
3-<''')5 '
3-470
I'.i
;,.Sir
._ 3/'57 -
3-4 -'4
i 1-
3-7.SI
3.620 I
_3-5'\3
.1:^^^
3-75'
.V34>
1^
.vr-i
3-54''>
3--')5
ISJ
.•,.(.92
_3.5aS '
_3-252
ly
3.6()2
J-471 ^
3.209
'"J. I
3.632
3-434
3.1(1(1
, '° 1
3.()Q2
3-397
_.v'-'3
20) J
"3-573~"
.3-360 1
3.0.S0
1
.1-51?
3-323
3.03S
2^\
,v^l 1
3.2S6
_ 2.91)0
'', i
_J4«5^J
.3-250
"j-9S3
32i ;
3.456 '
.V2I4
2.912
1 -:? . 1
3-4-"'
3- '78
2..S7.
-r?i
,i-,)'):
314-
2.,S30
:^4
__ 3-.i''9
3. 1 G() 1
_2.7.;o
' 2-»rj
3-340 i
3.070 :
2.750
-^S
3-i'i
3■<^^^
2.710
-5!.
_3.^x^ ;
2-<)')<)
2.670
, ^6 j;
J-- 54 !
2.964 1
2.6 ;o
:f,i •
V-'jd
2.')2f)
2.:^n\
J"
3i,),s .
2.S.,5
-■^i'l
-Ti ii
3-f70
^ 2..S(iO
.•515
TABLE X.
INTENSITIES OF WORKING-STRESS FOR CHANNEL STRUTS.
CLASS A.
[0
I I
11.^
12
I I
ill
I >
Id
K.i
IS
|S)
I')
:i
-' ' i
2 "*
22\'
dd..«
ii»3>
#(§
1
.(.JO 5
.1.140
,v90O
■t-'7=;
4.103
J-947
.(.i.i;
.|.o66
3-904 1
, .(.III
.1.029
3.862 1
4.0S5
3-'W.5
;,.Si9
Ratio. ..- —
z to /;. i aa
-(■o,s;,
-♦-023
3-993
.V9.P
C3®
OdD
1 Ratio,
I to I).
HIS
2.826
2-477
46
2.241
2.792
2.441
47
47i ^
2.219
-^759
2.404
2.368^
•■332
2.297
2.198
2.725
2.176
2.692
2.659
48
48.J
2.15s
2. '34
2.627
2.262
2.227 ~
-A'93_
2.160
2.127
2.094
2.061
49
2. 113
-•595
__19i_
5°
sol
2.092
--53'
2.072
2.051
2.500
5'
2.031
2.46(j
2.43S
52
52^
2.011
1.991
2.408
2.030
'-97 1
-^378
1.999
53
1.952
2.34S
1.968
-1-S37Z
1.908
1.849
1.820
S3k
••933
2.318
54
1.914
2.289
S4i
1.895
..S76
1.839
2.260
55
2.203
5Si
56 '
-147
J.I19
'•793
1.765
•-73S
S6i
57.
S7i
1.8 21
1.S03
2.0()2
-•.06;
-' ■039
o'3
1.0S7
1.1X12
M2
I ss-
1.8(13
8;u
1,81;
t.710
1 .684
17.58;'
J -^31
1.607
'•5«3
'-55«
1S09
1 .486
1.46,1
1-112
5«
i.7r)8
_ SS-1
59 _,
"S9i
60
'-751
'•734
1.717
1.700
f)0i
1.683
6,
1.666 1
6..^
i.'>49 :
62
^'3
I -"32
1.616
1.600
1.584
,1
\
-s„
INTfiANNEL STRUTS.
Katio,
/. I.) D.
Gill
10
4-367
'0^
4-343
II
4-3 '9
^^\
4.294
\z
4.270
I2i_
4.245
' .1
.\.220
\
INTENSITIES
Ratio,
/. I.) D.
10
IfiiO
"*
®©
4-/'7
4.299
l-'43
11
4-343
4-3 '9__
4.26S
__4.ro5
_ 4-237^
4.067
Hi
4-94
4.20f)
4-029_
1 1
4.270
4-'75
3-992
.2i
l4;245_
4.142
3-950
'3
4.220
4.1 10
3-9 '4
'.3i___
..'♦•.'91_
4.077
3-875
1 1
l.Kx)
l.045_
3-836
Mi-
4.144
4.012
3-795
's i
4.1 18
3979
_ 3-755_
15I
4.o<).S
.v<)4^>
3-714
i()
4.o().S
3-913
3-674
,r,,i_|
4.042
3-879
__3A33
'' __.'
4.015
3-S45
3-5''-'
'7)
_.!•<)' K)
.VSi,
3-55'
IS 1
__3-0''t
J-777 :
3-j'o_
iSi '
3-'»>''
^3-743
3469
!■)
.)•')'-'
3-70.S
3.428
n»J
VSJSd
,v''>74
3'387_
JO
3.,S(,o
3-<'40
3-346_
-'Oi
3-\V>
V(')o6
3305
Jl
;v'So7
3- =171
3.J64
-Mi
3-7.SI
3-537
y--:^ '
ti
3-755 ;
.1-502
3''82_
-V',
3-7 ^S
3-4f>S
3- '42
" 1
3-702
.)-433
3.I02_|
, 1 '
',,•17(1
3-.VI.S
;,.o()2 (
-'t
,!■''!')
3-VM
3-o.:3 1
-•■('.
;.!._•;,
.;■!-■')
J.. ^3 1
-■5
.v3'i'>
,v-'»5
-"»3_i
-•-.'.
3-.vO ,
;,.2;)i
•■'m '■
^(^■■" II
3-544 !
_3---7 i
"2.864 ■'
.hi_ :
3-5'Sli
3 I'M
2.S2fi^
"' - -- il
. 3"»9i
3.1(0
2.7S8 1
i7K.ii
3-465
3- '27^
2-750 !
TABLE XL
INTENSITIES OF WORKING-STRESS FOR CHANNEL STRUTS.
CLASSES B AND C.
iuC
2.712
2.674
Katto,
/, to Z>.
■a I
1®
®®
i.6i6~
'-593
1.570
1.547
'•525
'•503
r.4S2 '
..40, I
1.440
1.420
1.400
r.3So1
i.36o"'|
'•342 i
'■323
'•305
1.286
1.268
1.250
. '•'99_
1.182 j
1.166"
Ratio,
L to D.\
mm
■ ®
0.976
0.963
0.951
0-939
0.926
,v»;4
46
_2.-.5S' 2
2.529 2
040
016
992
968
944
921
898
64
644
1.842
1.327
J.O()l
46J
47
47 i
1.826
1.312
.)-02S
2.638
2.602
2.507 I
65
6si
66
1.809
1.792
1.297
1.282
j.()95
2.485 _i^
2.463 I
2.</)J
48
1.776
1.760
1.267
>.253
2.930
2.529
48i
2.440 I
66i
0.915
0.903
0.S91
0.S79
0.867
2.S97
2.494J
2.459
49
2.418 I
67
67]
68
1.744
i ■■7^8_
, i-7ti
1.238
'•-23
1.209
2.,S6.,
49i
SO
50^
2.396 >
2.374 I
875
853
83 >
2.S32
2.424
2.S00
2.390
2-356
2-323
2.289
2.2S7
2.225
2-353 '
68i
69
I 1.696
'-'95
1.1S2
2.76.^
5'
2-333 '
809
>87'
1.681
1.665
1.650
0.856
0.845
0.834
0.824
0.813
-•73S
5>i
52
S2i
2.312 I
69i
70
1.168
2.707
2.292 I
2.272 I
2.251 I
2.231 I
2.21 1 I
766
745.
724
703
'683"
665
648
626"
604
■•IS4
2.676
70i
1.636
t.140
1.127
2.f.46
S3
71
1.622
1.607
2,015
2-193
2. 161
2.130
2.100
S3^
7ii
1.115
-.'•'°3
1.090
1.078
0.803
2.585
S4
S4i
72
1.591
0.792
~ 0.782
0.762
0.752
-■55'^
2. 191 I
2.I7I I
2.151 I
2.132 1
i 72i
1-577
•-563
'-549
1-534
2.526
S5
ssi
73
2.496
2.069
2.039
73i
74
1.066
1.054
1.042
1.019
1.007
2.467
56
2.439
2.010
564
2.1 13 I
585
566
744
1.521
„''S07_
1-493
1.479
0.743
2.4 1 2
i.98r|
1.952
1.924
1.896
I.S69
1.842
I.SI5
I.7S9 1
1-763
••738
1.712
t.6S8
1.664^
r .640
57
57i
2.094 I
75
0-734
2.;,S;;
2.075 '
547
754
0.725
-•35S
58
1 2.056 j I
1 2.037 I
2.019 •
529
5"
493
475
45S_
441
424
407
39'
375
.^59
1.149
'•'.?4
1.1 iS
..103 "
i,oS8
^ '-073
1.059
76
, 764 _
; 77
0.716
2.,\zn
S8i
1.466
0.996
0.985
0.974
C.963
__o.953
0-943
0.922
0.707
2.;,oi
59
_.'-t53_
1.440
1.426
~J4'3
0.1 «>s
2=73
59i
60
1 6or-
2.000 I
1 .9S2 1
..964 !"1
1.946 r
1.028 I
1.910 1
1.893 '
1.876 1
: 774
o.(xS9
:.:\--.
! 78
o.(')S 1
.'..MS
784
79
o.'i-';
-M'l.'
61
62
1.400
O.Ods
J.KK)
1-045
'■°3'_,
1.017 i
O.OC)0
794
1.388
•-376
0.65-
2.140
: 80
0.649
2.115
62i
63
63i
L 8°i
St
'•363
••3S>
0.912
0.641
2.0<p
0.902
0.S91
0-633
.•.065
1.859 1
343
si4
1-338
0.624
T>
K
i
T/
■m
V.
TABLE OI
AND ST
STRESS]
g
(«
Q
C\.\»* A
J
S-9
-•i"
:•'
•i"
.S4
<j.i)
=r_
"S
i' "
1 t ^ '*
-^
! i.v.>
» t "
'5-.5
^i"^
_^ '"-s
,"
i<)'i
ir~
i__"-5
.>v'"
1 25-3
■_.-«••?
vi"^
I .?'<'
}V
1 35.'.
M''
' .v^..s
'*'_
4^.«
■i"
! 47-1
li"
S'-7
ir
S<'-5
rr
I (.1.7
■li"
1 07.1
li"
! 72.S
ii"
7S.<)
li".
S.So
^
j 1)3.0
a'"
i <)<). 1
- 1 "
1 (W J. ^
- 1 "
^ 1,
lll.',
-T"
I )0.0
« 5'>o
TABLE XII.
TABLE OF WORKING BENDING MOMENTS FOR IRON
AND STEEL PINS. AND OF WORKING SHEARING-
STRESSES FOR STEEL PINS.
M
i
! ft
1
\\"
>'v
if
'*—
-•i" '
-•r
- n
Resisting Moments for Bending.
Kl.,
Resisting Shearing-
Stresses.
W
E
5
lUllV.
Su
!
.S|l l-,!..
1
a.i« A.
Cl,i»!>f< L.ncr.il
H Anil C. { Synlcm.
C'Iam a.
Cla»iM;»
CUu A.
CtauMi
H and C.
1
3.1
■I
!
' 2.9
1
1
! .V
.}•;
J-o
\""" .: "
8.5
II.O ,
'i*
2j"
" _-
2i"
2?"
3'
3i"
4.0
4.8
1
5.9
40 5.9
III 7.2
~ 7,, H.S""-
"
7.S
i)..S
II.S
1
■
■
.. . «3:3
12.1 15.2
7-1
8.9
10.6
12:6'
' .4.8 "
17.2
19.9
22.9
"It ll-- i3w
17.2
8.4
9.9
10.5
1^3
134
'f""^ _, '54 i
i<r 11 i7-« i
19.3
15.8
21.3
-4'
>>S
144
18.4 :vo
i 18,9
23.6
^r
1 1.1-3 .
16.6
21.3
JO.Il
20.8
26.1
?"^
u
, Iff
,vi"
15-3
^_ '7-S __
19.9
1 i2.5
1 25-3
19.J
21.8
24-5
28.0
1 22.9
28.7
36.3
34.'J
35.1
3'4
34-2
37-'
40.1
43-2
46.5
34.8 I 29-8
3 '.8
36.0
45.0
27-3
38.1
33-7
i 29.6
3t-6
37-9
40.5
SO.C
1 32-0
1 3r
5V
3i"
1 31"
\ 3f"'
, 31"
i '♦".-
! 41*
' 4i'
4i"
4V
2S.3
i .V <>
354
424
45-3
5<^-'' i 34-5
39-5
474
50.(1
(\\.2
.37- '
,?r i 35-'
43-8
S2.6
56.2
70.1
7--f'
85.()
39.8
49-9
48.5
53-5
(..(.J
6;. I
(kS.5
4».7
53-4
ti"
a"
42.8
i _j47il:
45.6
57.0
58.9
70.6
75.4 ')\-:
82.7 10 -,.11
90.4 1 1 .;.o
98.7 >-;v4
48.6
60.7
64.6
S'-7
54.8
58.1
64.6
;(i.S 70/)
68.6
oi-r 77-1
' 72.8 <)I.O
7^-7
107.4
1165
134.1 w 61.5
I4.vi> i 65.0
76.9
81.3
)J" iS;.') lo6.()
[2G.2 i;-S ' r.S.; 1 S;.6
1 vi ^ 1"^'' 1 r-'-i i 'JO-'
;'■ ji ()2.0 115,0
1.17.2 , IS4.0
r 58.(1 M1.S.1
1 1701 -'13.0
li 75-8
94-8
5"
' 5]"
Si"
5i" ,
sr 1
5f
6'
!
it 79-7
99-6
104.6
;J" 1-1.; i 1;, ;.!
II 83-7
>.■■ "1-3
^V '■•-•s
1429
18.' -':S.7 '' 87 .8
\tyC,.o -1-" 9'-9
;;o(),(i 96.1
_'_\| 100.4
1 :!.!>i.'i 1! '04-f<
ro<i.7
114.9
15.V'
1
6'"
|i '5"'"
1 254-4
1
i
II .09.3
i
^4
//' =
lino 1
lattc
>
ii
FOADS THAT CAN BE
iTr.iutwine's formula. /('— ,.„ where
//'=1():
Ti.Mm, and in rij;ht or It't't haiiil vertical
line for -"r, and a horizontal line through the
latter, ir
8'
21" ^ 22"
i i
-3"
24"
!
().o.44 io.3').S
11.882 1
13.500 :
8'
9'
10'
1 7.14') S.Jii)
1 5.7.S8 ' 6.655
; 4.7S4 5. 500
9.3S8 .
7.604 1
6.285
10.667 j
8:640
7:141' i
9'
LJ0'„
u'
II'
1-2' ]
{ 4.0JO 4.622
342s 3-98S
5.281
4.500 !
3.880 '
6.000
'"5,112
12'
13'
! t4'
isH
'4' 1
2.953 3-396
4.408 ;
15'
i6'
'7' "1
2-573
2.600
3-3^0
2,971
3.S40 .
.3-375
2.9S9
«5'
16'
«7' .
2.261
2.003 ; 2.303
2.631
1 8' i 1 i.7'^7
2.054
2.347
2.667
18' 1
>9' ;
1.603
..S43
2.106
2-393
19'
20'
1.447
1.664
I. (JO I
2.160
20'
2l'
i-3>3
1.509
1.724
1.959
1 21'
t
22'
1. 196
•-.375
1.57 1
1.7S5
22'
2.V
1 1.094 1 I-2SS
>-43!L
•-633
- 23'
24' '\
1.005 i '-'56
1.320
1.500
24'
25'
25' 0.926 1 1.065
1. 217
1.3S2
26' : 0.S56 ! 0.')S5
'j'-S.
1.278
26'
27' h__0:Z?4,_ 0.913
28' J j 0.73'^ _| 0.849
29' 1 1 o.6,SS , 0.791
"•043
0.970
o.()04
1.185
• 27'
: 28'
1 29'
1.102
1.027
30' o.'i.t;; 0.7.(0
o.S4i;
0.1)1 <>
30'
\'
FOR FINDING THE S
■|k
tads bciiij;" those which will ]'
//'=z]();ul in tuns, // = depth ot bi'ani in
T(i find the sate ilistribiited luad fo
line for k'n^th of span. The number fo
latter, miilliplied bv the witlth of beam ii
I
' S"
9"
10"
II"
I.
8'
0. soo
0.7 r 2
0.977
1.300
I.(
9'
1 10'
o.,v)5
0-1-0 i
0.5^3
0.4 5f)
0.772
0,625
1.027
~O.S32
I.;
I.C
II'
la'
0.2h4 .
0.222
0.1 Si)
o-.i;?
o-S'7
0.434
0.370
o.CkSS
0.492
0..^
0-.3I7 ^
0.270
0.7
13'
o.(
14'
1(15
0.2}}
0.319
0.425
0.
15'
0.14.'
O.203
0.278
0-370
0..
16'
17'
0.l2t,
I 1 1
0. 1 7<S
0. 1 5S
0.244
0.215
o.3-'5_
0.2S.S
0..
0-,
18'
>9'
0.01 )l)
O.O.SI)
o.u6
0-I93 ,
0.173
_ 0.257
0.230
0.
0.
20'
o.aSo
0.114
0.156
0.20>S
0.
21'
22'
07 ^
O.Ottd
0.10;,
0.01)4
0.142
0. 1 29
0.I.S9
0.172
0.
0.
23'
o.o.S()
0.1 iS
0.157
0.
24'
0.079
0,109
0.145
0.
25'
26'
27'
0.100
0.123
0.114
0.
._°-°93.
0.
0.
28'
0.106
0.
29'
30'
i
0.
■-O'-JWp:-
TABLE Xlll.
BINDING THE SAFE UNIFORMLY DISTRIBUTED LOADS THAT CAN BE
BORNE BY PINE BEAMS.
d^
Is hrin- those which will pnuhice a (Ictlcctinn ol only 4^0 "'' ^'^^^ ^P^"' calculated hy Trautwine's formula, W - |^^.^. where
(ins, ^/ = depth (if beam in inches, ami / -:-- len-th of span in feet.
Ihe safe distributed load for any span, h.ok m tiie upper horizontal line for depth of beam, and in right or left hand vertical
of span. The nuiuber found at tiie iniersection of a vertical line through the former, and a horizontal line through the
led bv the width of beam in inches, will ^i\e the load re(|uired.
|vSrJ'r'''«(»l
jr-.
liiK'
litti
'^*Msii'
..u™^
p LOADS THAT CAN BE
c'd by 'l'raut>vinc's forimi!:!, //'.
Mo/
.„ whore
pth of l)c;im, ;in(l in ri-lit or left li;iinl vertical
Iji,^. ic foniier, and a horizontal line through the
lalte
I
')
20'
21"
22"
23"
16.531
24"
- . 1
1
1
IO.S70
.2.5S3
14.467
.8.781;
'^ .'-
.1
M-SSS
9.()42
'•-43'
r 3.062
14.841
9'
.'■*-
.''-
__ 6-957
5-749
«-053
6.655
9.259
10.5S0
"S.744'
12,021
9-935
i:__to'
n'
7-652
.-'
4.831
5-592
6.430
7.347 1
8.34S
12'
,.5
.|.ii6
__:v549
4-765
_.J.IO(J
5-479
.. 4-7-4
6.260 ^
5-.i97
7-"3
6- '33
' 13'
14'
.' '
3.092
3-5^9
4-"5
4--0J
5-34;,
15'
i''
2.7. s
3.146
3-'"7
4-133
4.691 >
16'
i'
2..(07
J.7S(,
3.204
3.061
4.1^1)
17'
1
1
_ -147
-'•4X5
2.S58
3-265
3-7 '0
i 18' 1
r
_L9i7 _
2.231
2.56;
2-<)3"
3330
19'
;'
'-739
2.013 :
2.315
J. (.,,5
yOO^
20'
'•577 !
I.S26 1
2,0<>S
2-3W
2.7 2()
ai'
'-437 !
1.664 I
'-9' 3
2.186
2.4S5
22'
;S
i-;,'5
1.522 ,
'-750
2.000
-'•--■1
23'
'■>5
i..'oS
i.3i>S ,
1.607
'-\r
J.0S7
24'
/■I
1,113
l.2.S,S ,
I. ,81
1 .tM(3
1 .gj ^
25'
1 J
1 .020
i.tyi 1
>-369 !
••565 i
1.7 7S
26'
,s
0.954
1.105
1.270
1 45'
i.'M'»
27'
,ll
0.S.S7
1.027
i.rSi
1-34')
1-533
28'
,''
o.Sj-
o,'):;S
I.IOI i
1.258 '
1.429
i ag'
.'.)
*■ . . >
■ N i ;
i.rj'i
' '">
i.r/'
30'
i
Trvs
FOR FINDING THE
TIk' loaJs hciiii^ thosr whifli will
//'-- load ill tons, r/ = (k'i)th of beam
To tind thr safe (listrihutcd load
liiK' lor kn;;tli of span. The number
latter, multiplied bv the width of beam
1
1
9'
lO'
n'~i
8"
0.695
_9:SSo_
0.445
o.3()8
0.309
9"
10"
1
II "
1.809
1.430
"•157
_ 0.957
0.804
0.685
" o.59r"
I
0.991
0.783
0.634
.^°-S-4.
0.440
0.375
Q.2S2
O.24S
0.2IC)
0.196
0. 1 76
0. 1 58
0144
0.131
0.120
0.tI0
'•3S9
1
■■°74_
0.S70
°-7 19_
0.604
0.444
0.340
0.301
0.241
0.2 J 7
o.I97_
0.179
0.164
0.151
0.129
H
la' 1
1
' _ '3'
'4'
' 0.263
0.227
-
1
15' o.iijS
16' 0.174
1 17' 0.154
18' ! 0.137
19' 0.123
20' 0. 1 1 1
0.452
0.400
o.3.';7
0.321
0.289
■
1
21'
22'
23'
24'
25'
26'
27'
28'
29'
30'
O.IOI
0.092
0.262
_o^239_
0.219
0.201
0.185"
0.171
o.ifo
O.I 48
—
^w
'H
B
H-
^B.
'-
-"- —
1
-..-
•'^ I
\
i
TABLE XIV.
FINDING THE SAFE UNIFORMLY DISTRIBUTED LOADS THAT CAN BE
BORNE BY OAK BEAMS.
.a.ls iK'in- th.^se whirl! will pnuluc. :, (lcfk'cli,,n of only ,i,t •'» tli'- span, calculated bv Irautwinc's formu'i IT^ '^'^- where
,,,,.,.. ' ' 1 1.5/^'
n tons, ^/ = depth ol beam in mcho, and / = length of span in feet.
1.1 the .safe distributed load tor any span, look in the upper horizontal line for depth of beam, ami in ri-ht or left hand vertical
,th ol si.an, Ihc number b.und . the intersection of a vertical line through the f.,rmer, and a horizontal line through the
plied by the width of beam in inches, will give the load reciuired.
n
9"
10"
1 1"
_T.8o9
1.430
1.157
0.9S7
0.804
0.685
' 0-59''"
0.452
0.400
0-357
0.321
0.289
0.262
0.^39
0.219
0.201
0-185
0.1 f)0
0. 1 4S
,2"
2.34S
'3"
i 14"
1
■5"
16"
■7"
18'
19"
20''
1
21"
22"
23"
24" 1
^s.
0.99'
0.634
0.440
o-37_.S
0.32;,
'•3S9
'•°74^
0.S70
0.719
0.604
"oTsfr
0.444
0.386
0.340
0.301
0:26s"
0.241
0.1 <)7
o.i7<)
0.164
J=-9^*S_,
__3'7-S
2.946
4-5«S
3-623
5-565
4-397
.J-562
2.944 ^
6.675
S-274
__4-272
3-53'
7.924
9-3 '9
__7-36j^
_5-964_
4.929
_4:^'4L
3-529
'
IC.S70
' S.5S8
6.957
5.749 '
4.S31
4116
_J-_549
3.092
^2.718
_„-l407~_
__2a47
1.927
'•739
'.577
'•437
_I2.583
9.942
8.053
_L4_467_
11.431
9.259
J6.53'_^
13.062
10.580
8.744
7-347
18.783 !
_i4.84i ;
12.021 !
9.935 '
8.348
8'
9'
>io
'-"^SS i 2.359
6.261
_5-o7i^
'4.191
MS
j68
1 50;, i.'in i 2.386
2-93S
2.425
2.038
to'
J.242 , 1.579
1.972
.'■^57 _
6-655
7-652
II'
12'
joy
1.044
0.889
0.767
0.668
1327
2.474
2.108
2.967
3-522
_-5:.S9i_
4-765
4.109
6-430
1. 130 ' 1.412
«-737
1.497
2.52S
3.001
5-479
6.260
7-"3 '
6.133
5-343 \
4.696 i
4-159 1
13'
-!/
C.849
1.217
1.817
'-5S3
_l'39i
1.232
1.099
0.987
2.179
..899
2-5S7
"=54
3-043
2-651
4-724
5-397
14'
15'
16'
17'
18'
9A
0.282
0.24S
0.2 19_
0.196
0. 1 76
1.060
_'j.3°4_
1. 146
1.015
0.906
3-579
3.146
2.786
4.115
.3-617
4.702
74
-_9-5^7,. _^°-74''>
0.932
1.669
T-478
1.318
1. 98 1
2.329
4- '33
.vt
0.520 0.661
0.464 0.589""
0.4 1() , 0.529
0.376 0.477"
_o.34i ! 0.433
0.31 1 1 0.395
0.284 j 0.361
0.261 i 0.332
0.826
0.736
•-755
2.064
3.204
3.661
Si
1-565
1.841
1.65:
_2-4«5_
2.231
2.8 58
3-265
2-93'
2.645
3.710 1
3-330
3.005
2.726
2.4fi5
2.274 '
2.087
; 1-92.?
! I-77S
1 '-649 ,
' '-5.13
UM29.|
'■3,'/>
11.
0.661
0.813
r.183
1.405
1.268
2-565
19' '
20'
21'
22'
23'
24'
25'
i 26'
1 27'
r 28'
r 29'
ti
^ 0..58
1 44
0. 1 3 1
0.t20
O.I 10
0.596
0.541
^ °-493 "
0.451
0.734
0.665
0.606
_°;S09,
0.470
434 _
0.403
__o-374
0-349 i
0. ^.-6
0.891
1.068
1.491
2.013
1.826
2-3'5
01
0.808
0.736
0,673
.0:969^
0S83
0.808
0.742
0.684
1.150
""1.048"
1.23:
2.098
2-399
'.)-'
1.664
'•9'3
2.186
2.000
—
0-959
0.881
1.12S
'•3'5
1.522
'-7 50
0.1 51
0.411
0.617
0.570
_o.527
o.4,S9 1
__o.454 i
0.424 !
c. ;ci'i
'■03i
1.208
1.1 13
1 .02()
0.954
O.8S7
0.827"^
1.398
..288
1.607
'•837
0.129
0.240 0.306 1 0.3S2
0.222 0..'S2 0.353
o.joii 0.2(12 ; 0327
0. 11)2 O.J).( 1 0.304
0.81 1 0.954
0.750 0.88:
0.696 ; 0.8 i.S
0.647 761
.48.
1.369
1.270
"1.181
1.693
'-565
1-45'
1-349
_'-A58 _
1.175
0.632
0.586
. °-S45
0.508
0.4- q
1. 191
1. 105
1.027
J_p.95S3
S()5
0.17')
o.-'j;
c -' 1 •
0..-84
0.603 ;
563
0.700
l.IOl
l.02()
Pa
Let
i I
I
I
I
1
1
1
1
I
\'
\
i
OF CLASSES A AND B
" ^ , /•'!
12"; ami ^iiard rails, 6"x6
Pa
Ler
I
I
I
>
J
1
Roadway,
24' clear, j
'" ' i
1 201
No. of
Joists.
•3
Size of
Joists.
,5" X 10"
No.
rai!
per
Hand-
Posts
panel.
Panel
Length.
!0'
11'
12'
I
'3'
14' 1
1
15'
16'
17'
18'
19'
20'
21'
, ,3/
24'
•y
1382
I4S4
1710
>3
\ 3" X 10" !'
>3
3''X'o",
3" X 12" 1
13
'3
—
1782
i y X \2"
205()
2136
•S
•3
' 3" X '2" 1
3">^'4"
-tX)
;,oSo
3339
»S
3" >< 14'
16
1 3" X 14*
I 4
'S
17
14
4" X 14"
1
"• 1
4 , '
i
4«x 14*
467 -•
J
4* X 16"
6
16
1 18
20
4* X 16*
6
j 4' X 16"
4" X If."
\ 6
m
-. I
"K
i
TABLE OF PINE LUMBE
I'loorin- 3" thick; hand-rail \u
Panel
Length.
Roadway,
12' clear.
No. of Roadway,
Joists. 14' clear.
No. of
Joists.
Road
16' cl
10'
II'
12'
691
776
1
8
sr
806
842
'}02
1 944
S
8
i 99
i 10.)
'3'
i 990
1 1 10
S
' -.\
W
lOJd
7 ; ..5^
S
'-7'
15' '
16'
1 rSo
'--I
•.^'S
9
8
\ '45'
<,57f>
,yj
17'
18' !
19'
1 |00
MP
i
TV,
8
'5('5
1670
9
Tjc
10
lS,,i
8
I 1950
9
2 '57
20'
21'
1
') 1
i 2aS5
2177
1
.0 1
S
2.V)2
7 1
J (20
22'
23'
24'
1
S
2.536
9
25«5
10
27S«
3024
12
.15 -S
OF PINE LUMBER
TABLE XV.
REQUIRED PER PANEL IN BRIDGES OF CLASSES A AND B
(including waste material). a ainu ti
.rin^ 3" thick ; han.i-ail posts. 4"x6"X4'; hand rail. tw.. pi.ccs. 3"x6"; huh rails, y'x.:"; and .au
■A^ydn] rails. 6"x6''
1
3. of Roadway.
if^ts. 14' clear.
1
No. of
Joists.
Roadway,
16' clear.
1
7
776
8
sr.i
7
902
8
i .
8
S
9
8
1 998
7
I 944
i 1046
7
IIIO'
I j;,o
" "5^
1278
s
i;,iS
'4S<J
;-
>37<''
■ S2S
i
9
10
1730
J
1670
.84,
!
1950
2aS5
2177 1
2336
9
10 i
8
9
-'5;
2.(20 j
)
ir
1:; i'
■^1
30-4
No. of Roadway, No. of Roadway, No
Joists. 18' clear. Joists. 20' clear.
II
Ro
24
\
>
IDGES OF CLASS C
2" ; and ^aiard rails, 6"xC)".
Roadway,
24' clear.
No. of
Joists.
Size of
Joists.
No. Hand-
rail Posts
per panel.
Panel
Length.
IJOI
'3
,?" ^ 10"
r „
1 3" X 10
10
II
i;,S-'
•3
'454
'J
j 3" X 'o"
13
13
ifiii)
'3
! 3* X '0' ;
1 lyio
«3
1 3' X 12* i
3" X >2"
4 !
»4
—
13
«5
jrsS
•5
3" X '^"
16
-',5^7
'3
3" X 14*
1 '7
:4f)2
14
3" X 14"
'> 4
1 18
20
- 1
3730
15
3' X 14'
^'/■J
>3
4' X 14*
3393
>3
' 4' X If/
6
21
1
3465
'^
: 4' X 16'
6
' 22
.V"!.?-'
'4
4" X 16" ,
'
23
.)I(K3
.6
i 4' X 16'
! ^
I 24
J
^
1
TABLE OF PINE LUMBER REQU
(inclu
Floorinj;- 3" thick ; hand-rail posts, 4"x6"X4'; ha
Panel
Length.
Roadway, No. of Roadway, No. of Roadway, No. of Roadwa
12' clear. Joists. , 14' clear. Joists. 1 16' clear. Joists. 18' cleai
10
11'
12'
13'
14'
15'
16'
17'
18'
19'
20'
21'
22'
23'
24'
691
SoO
S42
94'
ioj6
ijif)
I s ^'1
IO.S5
1
7
"133
7
|()fX)
7
2236
S
■
rrC'
s
902
8
944
8
ros4
8
..5.^
8
1270
8
1360
9
1502
8
1 1544
8
1740
9
I-
1899
2400
2ri7
2502
2672
8
8
8
9
10
86;
998
1046
1 167
1278
1408
1504
1667
f7'S
1924
2II2
2420
24')S
276S
2944
9
10
9
10
9
10
94''
1094
II4S
12S0
1404
■; '5t''
jl \(<.\S
■ 1
I iSS()
2178
2325
2663
-7K
.)034
33 1 1
TABLE XVI.
LUMBER REQUIRED PER PANEL IN BRIDGES OF CLASS C
(including waste material).
id-rail posts, 4"x6"X4'; hand rail, tw pieces, 2"X6"; hub rails, 2"x i:"; and guard rails, 6"x6".
of
ts.
Roadway,
i6' clear.
j -, .
86 1
! 998
No. of
Joists.
9
9
9
Roadway,
18' clear.
94C
1094
No. of :
Joists.
Roadway,
20' clear.
No. of
Joists.
M
II
II
Roadway,
22' clear.
1116
1286
No. of ,
Joists.
12
1 2
Roadway,
j 24' clear.
1:01
13S:
'454
No. of
Joists.
'3
•3
•3
Size of
Joists.
_„.. _.._.__.
! 3" X 10"
No. Hand-
rail Posts
per panel.
1
1 2 i
Panel
Length.
10'
10
1031
ro
1190
3" X 10"
3" X •o"
i
4
1
: 4
1 11'
1
12'
13'
1046
1148
ID
10
10
1250
•352
it67
9
1280
1404
•393
II
•504
1656
1 .822
19S4
12
1 2
1O19
i-S:
•3
'3
; 3" X 10"
4
1278
•530
II
..
12
II
12
i 3" X 12"
4
14'
1408
1504
1667
9 i
10
'^ i
9 1
.0 j
1 '546
164S
.8J2
10
1684
'79-
12
14
12
i960
:i:S
•3
'5
•3
' 3" X 12"
! 4
15'
1 1
3" X 12"
4
1
i6'
17'
10
•997
2162
'-r-7
3" X 14"
4
•7'S
; 1886
10
2120
2291
2546
2752
•3
2462
-730
14
1 3" X 14"
4
18'
!
; 1924
2112
2.78
2325
12
2362
•3
II
•4
•5
i 3" X 14"
4
19'
20'
j
9
10
10
10
2539
2965
3393
•3
1 4" X 14"
4
2420
> 24C)8
276.S
-944
10
1 1
' 2663
2:17
.1034
.vV14
2907
II
II
1 **
3150
, 32.6
35(if'
1 2
12
•3
'5
•3
; 4" X 16"
i
6
21'
22' 1
i
1 . ,
1
'
2967
3300
' 3465
•3
'4
16
4" X 16"
6
II
'3 i
4" X 16"
6
6 1
i
3616
•4
3S88
! 4" X 16"
I
\
I
I VluvA
! Length.
'9'
T^ PANRIDGES OF
joists and llo'y.i'. i, , ;,.„ „
puard-rail, 6") ^^' ''''''''' ~^'''' '^■■'> ^.11, .V'xr.v
The upper fij ^vaste ,
Pan.-l
Ltnglh.
Roadway,
12' clear.
No. of ). of I Size of No. Hand- „
Joists. lists, ji Joists rail Po?ts Panel
I " per panel, length.
\
TABLE OF PINE AND O.
Joists and floorint;' of oak, and other lumber pine
an 1 f;uard-rail, 6"X6''.
Tlie upiKT figures in each rectangle are for pin
-
Panjl
Roadway,
No. of Roadway,
No. of
Roadway,
N
1 Ltngth.
i
12' clear.
Joists. 11 14' clear.
Joists.
16' clear.
Jc
1
1 51 ,
; 117
/
' 1 ;<>
•1S3
S !
,56
550
1
200
200
8
200
' .\>^^
7
5f'5
G43
f
1 JOO
200
8
1
200
i "'
■>35
7
620
70s
; :jS
22S
s, 1
22S
'3'
1 61s
7
712
S09
' :!j.S
2 28
8
22S
'l'
-5"
7
7
770
256
«75
^
, i
S
256
'5
730
1 S45
960
, ,
j;()
1
i 7
25.)
8
256
' "
^1(1
944
1072
,
JS,(
2.S4
8
284
'7
ciJO
/
; loll,;
1207
f i8'
JS4
284
8
284
i».Si
, /
1 "34
1287 1
'9'
3'-
1142
7
1 >3'8
S i
i
3'2
"495
•o'
3'-
1-53
7
1 312
1447
8
3'-
1640
,
35'>
-
r^s"
s
356
1-100
/
; "''5
lS;,o
22'
35"
1 fii
3^4
7
35'>
1709
3^4
8
, 1
^ 35<'
, '93'^
,
1 7
' 8
384
'^J
1 ;S()
1S29
2072
Vi-t
11S4
3«4 1
^V
'"11
1992
9
1
2368 1
TABLE XVII.
OF PINE AND OAK LUMBER REQUIRED PER PANEL IN BRIDGES OF
CLASSES A AND B.
oak, and other lumber pine. Flooring 2.]" thick; hand-rail posts, 4"X6"X4'; hand rail, two pieces, 2"X6"; hub mil, 2"X 12
:ach rectangle are for i)ine, the lower for oiik. The ciuantitics include waste material.
oadway,
.' clear.
1
No. of
Joists.
Roadway,
16' clear.
No. of
Joists.
Roadway,
i8' clear.
No. of
Joists.
Roadway,
, 20' clear.
1
No. of
Joists.
Roadway,
22' clear.
No. of
Joists.
I "^
Roadway,
24' clear.
1
1
No. of
Joists.
Size of '
Joists.
1
No. Hand-
rail Posts
per panel.
2
Panel
Length.
1 ;(>
8
156
200
643
200
705
9
'J i
9
!
9
If-
617
10
156
683
1 200
798
II
II
'50
750
'5''
Si 7
13
2.!"X8"
2i"Xl0"
10'
200
8
8
200
200
790
228
906
10
10
10
200
875
1 -°°
' 953
13
4
XX'
ta'
13'
14'
1 '5'
' 16'
1 ■/
200
620
200
87.5
228
i '003
32S
10S5
256
1190
256
1328
1 284"
! '494
i :S4
. '^"3_._.
i 3'2
i 3'2
t 2027
' 356
2260
: "356 '"
__239L
384
255«
• .3«4
2Sd.,
II
200
960
I 2
1 200
! '045
13
4
22^
7'-
'-'s"\
228
1 800
II
22S
IIOO
I 2
1 2
I "*
228
1197
22S
r2.,5
»3
13
2|"Xir' ;
1
4 ;
2JS
770
" 1 960
8 ' =56
i 1072
S '^^
1207
^' . "284""
'^ 1287
8 i! 3' =
228
9S0
j~ 256 ~~
'075
1200
'""' Is.i ■'"
1 ',;o
10
10
I i
2J8
1 1190
2^"X 12"
4
1
2's,6
9
1
9 1
II
II
I 256
1 1305
! 2S6
i '4.56
!"""2^6
1 'I'O
2^6
1 5.S4
'3 i
13 '
2.|"XI2"
4 1
i
250
944
10
I "^
3" X 12" !
.1 1
28.,
10(1;
9
9
10
II
i 284
1 1637
284
1746
312
2025
I "^
1 2S4
' 2S4
1S99
•3
3" X '3"
^ !
~28r'
1 1 "i.i
2S4
; 14.10
3'-
_ 1672
'833
356
2045
356
i 21(1?
.vS4
23 '5
3^4
.'did
10
10
11
II
I 2
'■'
3" X '4" j
4
1 18'
;.'-
i;i^
12
i -''2
i 2202
13
3r'xt4" :
4
1 '''
\ 20'
1
21'
22'
! 23'
.V-
1 1.1"
J
8
31-
1640
"" 356"
! 1830
: 35"
i '93'''
i 9
10
10
10
10
12
3'2
2220
35''
; 2475
i 356
i 2O18
1 384
2801
384 ^
3112
I 2
3' 2
' 2.113
13
4" X 14"
^
.>.=;|'
S
1 — ^ —
9
9
1 9
1 1
II
11
I 2
1 2*
14
20i)O
'3
4" X ,5"
6
■' 35(i
1 2845
3^4
' 3044
384
33'JO
13
. 4" X 16" 1
i
4" X 16"
6
350
1709
8
•3
! 6
3^4
1H29
.3''^4
• 99-
8
i 3S4
2072
3^4
2368
9
1 1
'3
15
4" X 16"
6
24'
r n
\
Panel
Length.
10'
n'
12'
13'
14'
15'
16'
18'
19'
20'
21'
22'
I
23'
24'
i
ANEL IN BRIDGES
loistshand rail, two pieces, 2"xCi"\ luib rail, 2"x i-";
iiul oriKirc
atcrial.
Panel
Length.
lo'
ii'
12'
pof
,ts.
1 •
Roadway,
24' clear.
No. of
Joists.
Size of
Joists.
No. Hand-
rail Posts
per panel.
i
2
Panel
Length.
156
200
200
101;,
228
1159
228
'-57
256
1420
2 5(>
I. (So
2.S.1
1722
2S4
.1'-
20 so
22(12
.55"
2SlS
35"
2757
3«4
,i'04
>3
i 2J"X8''
2 1 " X 9"
2i"X9''
1 — - - -
i 2i"Xll"
2j"X.2'' i
10'
I.?
4
11'
12''
13'
14'
15'
16'
17'
4
1
13' j' '
14'
15' : '
13
'3
4
4
4
1
•3
'3
■3
1
j 16'
1
! 17
1 I
!
1 »
2j"X 12"
1 3" X '-■'
1 , - . - -
i ^ ^ '-^
;," X 14"
3^X14"
! 3i"=<'4'
' 4" X 14"
;, 4" X 16"
4
4
i '«'
i 4
4
1 4
18'
19'
1 20'
'3
>3
14
: 19'
ao'
2a'
23'
24'
21' ' 5
1
22' i 5
1 .
23 -
1
6
•4
'3
' 6
! 6
24'
! 2
4" X !()"
: ' 6
If
JS
TABLE OF PINE AN
foists and tloorin^^ of oak, and other lumber
iiid jTuard lail, 6"x6".
The uiipcr tiguix's in each rectangle are for
1
Panel
Length.
Roadway,
12' clear.
^ 4j7 '
200
,88
1 200 i
i S.8 I
228
594
22S
64^
-5"
730
-.56
760
2S4
, 888
1 284 ,
950
312 i
' 1060
3'-
1 172
35"
I2V)
1 s
' 3^4
1586 _
384
1616
>4o. of Roadway,
[oists. 14' clear.
No. of
Joists.
8
Roadway
16' clear
lo'
11'
12'
13'
14'
15'
16'
17'
18'
19'
20'
21'
22'
i
23'
24'
7
7
156 i
4.S3
,56
550
200
565
200
()0O
228
688
8
200
643
8
200
r,83
7
8
228
783
"y"\
228
747
8
228
849
, 1
/ 1
7
7
256
' 845
2 -^0
j 8S0
284
1027
\" ^84
1098
8
8 !
8
960
-"256
1000
j ^84 "
; I i(>6
2S4
; 1-46
7
3>2 i 8
1225
3'= i 8
: >353 J
3>2
i390_
3'2
" 535
7
35" ' 8
' 1 '!44
356 9
; 'f^94„_ 1.
384 i 8
'829 ; ^
35*'
■738
8
7
35"
1907
384
2072
7
3M 8
1S(,.,
384
21 12
—
TABLE XVIII.
JLE OF PINE AND OAK LUMBER REQUIRED PER PANEL IN BRIDGES
OF CLASS C.
ol oak. and other lumber pine, iqooring 2,1" thick ; hand-rail posts, 4"X6"X4'; hand rail, two pieces. 2"X6"; hub rail, 2"X 12";
in each rectangle are for pine, ihe lower for oak. The cjuantities include waste material.
Roadway,
14' clear.
No. of
Joists.
Roadway,
16' clear.
No. of Roadway, No. of
Joists. 18' clear, i Joists.
Roadway, No. of I Roadway,
20' clear. Joists. 22' clear
No. of
Joists.
' ' .., i- ' c- £ No. Hand- p__.i
Roadway, No. of 1 Size of ^^-^ p^^j^ Panel
24' clear. Joists. I Joists. ^^^ ^^^^^j Length.
Panel
Length.
lu I ' I
i
I
J
t i"» .i»j M
f
Panel
Ituiltlicim, ().'# |)fr fool
Wcl), yx-^o"
ir.> fl 1 -.1 " V ^^ - -tt. -.
lUiilt-hcmii, ().)J# |)ti foot
\\t\,,\"XT,0"
.«'
i
.''■' ! Kiij.lw.iv. li I'li.ir
1..- t.«I
I.'" (-■•I
; v>« I. .
!.•" (.■•I, Ml l<,' V.«I, ,M
I lliillt lit'.iiii, |i« |iii liuit lliiill In.iiii, I
Wdi, I'xi.)' Wil.. J"<jj
l'|i. ll., .' j"x .'J" \.%» .in«li' \ I'll. rt.. i :' '
I., rt.. 1 -•' X r |« .mull' I- H„ 1 j'X 1
JIJ" l.'«I. Ml !<.' V>«I, Ml
""!' t"!«I
I •■,,.•« I,...
i;. III! III. nil. r!* I" I '■•■•<
Uih. I'X |S'
I I'll. -• j"x .•!" V5«.im'.lf
I ll , J .'"x ;(• \ «• mull'
ly I--*!. ■'!
IIiiiIi-Ihmiii. I'll* I'll I. Mil
W.I,, i'x |S-
I I', ll,, .' .'"x Jj" IS* .iiiuK*
I ll , -• •■•' ,r .|« .inuli'
!.•■ I-'*!. Ml
I'llllt Ih'.IMI, |I« |»I ImmI
Uil., l"x i,|'
I |., It., -• .•'xjl" vi;«.iiinli
I ll, .' : » i" i« .iiiulv I
!.•■ (-■•I Ml
r.iiilt Ikmih. i-'l* pit l"il
W.I., I'x.m"
I i- ll, i J'x.'}' ?;«,inKi>
I ll . .• .'"x i' .()» ,llllilt•
|y■|-•»I. Mr I
laiili Ik.1111, 44# |ur I'm..!
Will, [-x.-r
I p. ll, .• .•'x.-J' 1 ;»,lll^lr
I ll . -• j'X )• 4« .lin;k-
I," ;r*I, .M
|; nil 1.1- nil, i;* I'll ImmI
Wil., l"x jj'
I |i. ri, J J'x.'i' i.;#4iinlr
I . rt., J j"X i'4«,iiikU-
I ;' no* I, M.
Iiiiili-l'f.iiii, |''1» |iir (,"'!
Wtl., ('xji'
I p. rt., .• 2"xjj" v.s**"*;!''
I I., rt.. .: -•' ~< '," 1» -I'luli-
1 5* ^'^ !• ''
Hiiill-U.iin, !*<« pil (m.,1
W.I,, >'xj('
Ip, A.,1 l'' 4" )■$» .ingk'
I , rt , ; j"x r i« .iii»!U'
i;' 5o« I. Ml
liiliil-lif.llll, \<0 piT ImmI
Wil.. \- ' 2S"
I p. rt., : j'X •[" y!i» .inKk-
I ll,, ■ .''X ;■ .|«.inf;lc
k" ;,*I. Mf
l;ilill Inaill, V* |»1 fMMl
Wtl., y Jl,"
Tp. rt., J J"x jj" v,S*'i»".l''
I , ll , .' .-'x (• 4# .iiikIi;
I ;" 50» I, iir
, P.iiilt l.iaiii. V* i'l'i f""'
Will, l"x .-s"
I p. ll., ; j"x i".l«.iiiKle
I ll, -• .'i'x i'.).!*:"!),!!'
1 ;■ ?,-.« I, Ml
Pun! Ik-.IMI, 5-'# plT ImmI
WM., l"x.>fi"
I |,, rt., J i'y \' ,|« -injiii'
I, rt , J .'J* ' ;" I 4».in«lt'^
P.inli 1.1 .1111, ;;« pit (mm!
\', . I.. J"x :r'
1 ;, ll , .• j'X (' |« .iiml'-
I ll., J .•4'xj"4.,|#.iii«l>.-
I J" l.'«I. Ml is" V1«I, Ml
llllill l,t' nil, |.'|« pir ImmI llllill I'l.llll, ;
Will, I'X. -o' ; Wl-ll, J"X;|
I p. rt, -• .'"x jj" j,5«,innli. I'p, A.,1 j"»
I., rt, -• J*x ," |II,iiikIc l,.rt,.»j"x
ij'4J»I.
I J 4J» ^, Ml
I'llill lit'.lln, ,| I* pil ImmI
Will, I'X.i
'iS'SO#l.Mi
llllill lit.iiii,
A.i Will, I'X.'-,
I p. rt,. -• J'X.'J' 4.s«,lll|;lr I'p. rt., J3"'
I., rt., -• .-'x \- i«.iihu- I., rt., : j"x
'5* so*r '"
llllill In'. nil, (S* pii Im..i
Will, l"x ..•"
|,'50#I,,
Iliiill'liiMiii,
Will. I'xj
Will, l"x ■:• Will. I'X ji
rp. rt., .' j'x.'i" vs«,i"hI' I p. rt., ii''
1. rt.. .' i"x V' («.inKli' I., rt., JJ'X
. 5"* I. ■
Itiiili-hiatii,
Will, |"X;i
lluili 1,1 .nil, ,|i* pn ImmI
Will, I'x.v,' Will, |-X;i
I P rt., -• j'x.M" v-,«.iH.;li Ip. rt. ja":
I., rt, .' j'X ;,• («.ihKl' I I- rt., 2 i|''
!<,' ;m«I, MI .
i^iuiiLi.*.. i^!«p.M-. '"'•'?:•"'•
W.I,, I'X js- ^'''■' '*:
i|-.".---'-«-'!'.v^*'^"«i^' ,'',, :',r,
I., rt,. J J'x.)'.t)»,iiiBle^ ^1. II. . Jj
It* (o*T, iir I ,. ., ,
.1 i.i .»« . i f . llllill lii.nu,
lluill lii.llll, <0» pir ImmI j
Wil., i"<Jli' ill .'
Ip, rt,JJ■x.•l',s«.l„^u■| l"'■•;;
l,.H,. jj'x,'.,«.i„nk ji-".-'- >«
i;" ;o»I. Ml I .
,, , , - . . I'.inlt I't.im.
liinli l.r.nn, 5I« I" I .... ,.^ ,
...... • I \\ ill, 1 X J,
l-p.rt,.Jj'x.," ,«.nu,l.- : ',, ."^^^
I. rt. J Ji'M^l |» .m^;lc J '""••■ -^ '■_
I.'Vf^'"'. I , '""iit'-".
\v''h,rx';.r'" ;\vci..rx,.
Ip. rt, J J"x ^'4».iiikIc
I, rt , J Ji"" r I 1* •mull'
llllill Iv.iiii, ^;» p.r f.i.il
W,|.. I'x j;
I p. rt , J j'X i' 4« .mt'.li'
I., fl., 3 Jl'X3•4.4».^nBl'-■
ll>. rt., J j"
I., rt., J J"x
IliilU-lx.nii,
Will, I'X ,
I- p. rt., J j"
l.rt., J i"x
r.iiili-lii-.im, Vli* l"-i '""' liiiili l".ii".
Will, J-xj;' [Will, I'xj
I'p. rt„ J Jj'x f i,.(« .iiii'lr I'prt, J Jl
I., rt.. 3 s'Xj' s#.inKli:
U rt.. 3 3j'
K .,1 Iway. 12 Cliar.
llinl|.|i.Miii, >;!» pi I fM.iI HiiillliiMin,
\V,|,, l"v..s- jW.l,, I'xi
Cp, rt., J j"». Jj" t 5»."'t;l^- ' I' 'I. - -"
I., ll . J j'X r s»-i",i;li: '■■ "■ -• -l"
liuili liiMiii, ^'>i* pii I'l'il 1 liuiiil'i.iiii,
Wll., I'XJ.,' IWlb, I'X:
I'p. rt,, J j'X jj" 4.-,» .n.Klc I r|,. rt., J j"
1,. rt„ J j'x.ii' vi«."iKl>-- il-rt.. 33")
lillill-I.IMlM. S.S(« p. 1 ImmI Hllill llialll,
iwi'li, J-x;,o' W,l., I'X,
I I'p.rt, J jr^-r l•l»•'"^■.''■ ' I'- "•- -i
jl.. ll., J j.|«xj|" vi«-i"i'li- 1.. rt„ j.i';
I |liillil«,nii,'il(# pii ImmI ' lliilli-licani
IwM,, I'/p" \V,I., I'X
I'p, rt., J -■';< r <»# aiif,!.- Ip ll,. J i
1.. rt„j Ji'''-.i"''7*-'">'.li' jl., rt, j/;
K,M,lway. 14' Clear. Roailw
TAbLL XIX.
TABLR OF FLOOR BEAMS.
CLASH A
I J- (■•I, ■■.
Kii.iilw .u lb' Ctr.ii
Km..,Iwjv, mcii^r, Koj.Ujy. joClt«r, KoaJway, 13' Cliar. | Ko«away, >4' Cltur. iJiig'l,
■■• • •- I ••• ■ I'x >•' "til, I X J"* Will, ^ X |o j Wtl), I X )o
Wd., l'*i'»" \Vil.,l"»---- IWvM'x:,' ,":»., , "^'•■kM"' i Wtl.,rx.lo'
I., rt.. i .'x ,,' U..nKk- ' I.. «.. » :•>« .' W .»«l» I.. H.. » r X .,' U a„Kk. '■ "• ' '^ ** » »• •""<''• '• " ■ ' -'l ' ■■ I ' "S* -"«"■ 1 '• "- ' »"x .«' 7.^# ..-ml
llV|.'«I. "t IS'V>*I. ■• H'.S"«I. "I
lliilll Nmiii, |.'l«|ni I liiiilllK.iii,, I »iiir I.Mil lliiill Kmiii, kj* pir I..m1 ""iI'I«.'mi. >.:»]"< f IIuMi.Ih.imi, (.|J» i«r loot
Wil., I'xjn- I Wth. fx;,' Wil., |"xj(," \V<I., ("xj./ Wil., I'x^,'
I'l'. Il, -• .•"« Jl" V5«>>»kIi' l'l>- ri. J -■•- Ji' 1.5«.iiik1i- . I'l'. II-. J -•">< )' ■(• .i"»',lf ^ ''• " ' ' •*" ^i' + "i* "'»•'' ' !'■ "■• • ■'''*.)' '■• ""W'*^^
l,.rt, jy'x (• l».i"Klf |l..rt.. JJ'x,'.,#anRW l..rii,a jfxy.)|« ; I H • .'x ,1' , -« ,„:,|, I .1, • •'■- i'6.7#»ngl.
Illllll In, 1111, n;« p. r f lluill.lR'.lMI, 'i|J» \wt lout
Ulltlll'
I angl«
W.l„rx.., \V.I,,|-x..,' ' ^^''"1 "^f , , )\'I.|'VK Wd,,l'x.,o'
I 1. tl . <"x.r ..« iMul, lull •• •!■ n».iiiuU l*^'''"' ^- ** ' H««iik1'^' I I' il. ••-•'xY' S«''"kI'' I |.. 11., 33-x ,''(«.invlf
I'll,! ; VxV'. .'*' ; .',1 ;v- , ,■ ,^U_.| '■• "■• ' ^'^^i' '••"•^"^ , ■ ■ "•; >'^ >" ^^ ■•:::'^ ' "•• '£y_r.:*j^^
Illllll Ik'.iiii, is* 1'>i I
\\<l., l"xj<" Will, J'x;
U l|.. il, .• j'x.'f isW.iiii;!. l|i, 11., J j" ■ ;J" .i.5*>'iml^'
I 11,. .■ .•" < l" (» .Ihnlr I.. 11., i J'X )' |» .lliKl''
n" V* I. "1 I V i;o«I. ' 1
Huili Ik-.iiii, (i» pi'i loni Miiililiiaiii, ,:» pii (mil
Will, l"«.M' Wil'. I'x.- ,'
U I |i II. .' J"x.M" V^*'"!-'.!' I'l'. ll. -• -•■ • 1' («.inKli.'
^ I,. Il . -• .■■ X i' |» .iiikI, , I,. II.. } i\'f 1' I |« .iiitjlf
' n" ?(>• T, "I , , I
, , , .._ , . liii i-lii'.iiii, ;;»|"i l'"ii
1.11,11 1.1,1111. isi« |i.T 1-..1 ;
Will, 1">.'S' ' '
, -■ , . » 1 I I' Il . .' J • !' 1« .iiikU'
Il I p. II.. -■ .• «-• vs».iii>;l. I . . 1
. , . , « I I . - .'! ■ i II* .1 lulc
■~i H' Ko* I. "1
tliilllln.lin. so* I'lf '""'
Will, J' ■< jiV
Il I p !l.J .-'x.'!' ] s« .ihkIi'
1 , Il . .• .'"x 1" .{« ,iiij;li-
IS" sr*!. "I
r.iii!i 1.1.1111. SI* I ' ' i""i
Muili 111 im "o* iH-r fiiiii Hiiill l>iniii, ssl* pii fm.' , llultl U'.im, 0:« per fmn riilli luam, 6ri« I'lr fiiul
' '' ' ' "' ' "■-•"" Will, I' X JO- Will, |"x p"
Uli.ll,. .' jfx ,' v'(*^iiinl' I p. 11., ).fxj*7,j«aiinlf
I,, rt., J jJ'xjJ'(,.5«aiiBU I II.. J3»x/7.7#anglc
Will. I'x.'S"
l[>. Il„ J .•'■xV.i,s«.>"j;li-
I,, rt., JJi'X.r .S».ii'Kle
Itiiilt'lii'iiiii. ssi* pir ('><>t
Well, J'x.n'
I'p, rt., -• .•'■> .'i' ,|.5#.inKli'
I.. Il , 2 .'"x 1' s* angle
lliiillln.im, 5;* 1'^'' '""'
Will, l"X;.i'
l!p.ll., J :"x:lV( s«anKle
I.. II., js'x.d' s..5« angle
lliilliliiMin, fi)J» per (mil I'.iiili.licain, 70* per limi
Will, I'x p' Will, I'x jo"
I'p, ll„ : .•'X I'fHi.niiKlc t p. rt, .' I'x ii'7,;#aiinli'
1.. rt., 1 Jj'xy <i,7(|laiiKlc I.. 11., i i'Xf ».)m angle
lluill lii'.im, ifi4 ptr fiiiil I lliiili liiain. fit,>t per (mit r.iilll luam. 75# per fiiut
Will, J'xio' , Will, l"x 10' Will, iSj'x vt"
llnllllieam, 67)* pi 1 I
Well, l"x p'
lip, rt., J i"x )• 7. j# angle
L. rt. -• i" r :-» M<y\<-
10'
II'
Illllll 111. nil, 70* pel (mil
Well, I'x 10'
I'p. rt , i I'x \\" :.:*.innle
l„ rt„ I I'x rs.|»aiigle
Ilnlll l«ani, 75* |« r (mil
Well, ,'„"x,„'
I'p.rt,,.' jf X;J''fi,s»,iii^lc
I,, rt,. J r'x.f 7,.'# iin^'.lt
llnilllieain, 7.S* pir (mil
Well, i^'X.id'
I'p, rt,, : ^'x )l"(i,4»anKle
L. rt., iyx3''7.j#,inHle
Hnlll'lieani, S|# per (mil
Well, i',,"x i.S"
I'p, rt., 2 ^''X •j''4.s«angle | Ip, rt,. } J'X^J' (1,4 angle I p, ll.j ;j''x il")!.;* angle 1 I'p. rt,, .' i'x ij'(i.4« .iiigle
I.. rt„ J i'x i|' 5..1«angle ] l„ rt. : fx f 7,j# angle I II. j fx 1' 7.:* an^le ] I.. Il,, j .f xj" 7,j# .lll^le
Huilt-lHain, fio# per (mit
Well, J'xio"
Ip, rt,, .' -•■'X )" 5# angle
I«rt, a .j'X )' 5,i)»;mglc
lliiilllii.iin, ;iil« |ii 1 (""I liiiili lieani, fi^J* inr (mil
Will. I'x 10
Illllll liiain. drj* per (cmt I uiltliiani, 76J# per (mil
Well, t'x )o" \\il', r'd'x.-iS'
Tp. rt, 2 ;»'x 1' 7,:#anKle I ji rt,. j jj'x .•j'(i,s»angle
I., fl., J 3'x 3" 7.7# angle I rt,, 1 j'X j" 7.j# angle
Illllll lieani. 70* per (mil Hnilllieani. 78* per diot
Wei), J"x p' Will, yx J,'
:" :: ' : wiii, i- ><...,■ wu., i"x,o' weh. j-xp- w.i,, ,',,''Xi(.
, ''; ' '^^ , . , 'ip, rt, .■-•■-.M' 4,s» angle I'p, rt„ 2 .')'x.,- 5,5* angle ; I'p. (I., j fx ,J' 7,7* ,,ngl. I ;., H„ 2 2-x il* (,,.|» .nigle
' '"l ' "' r * '• ' ^""' I., rt,, 2 2-x ij- 5,j» angle I,, rt., 2 jj-x-l' <^-5« a"Kl«-' ! !-• «■. : ,f>< .i" !<t» •ingle I.. lU 2 j'xj" 7.2# anslc
is' so* I, iir
Illllll 111, nil, S-'* per I'll. I
W. I.. \"-< :('r
,li- Ip, rt . 2 2''x !'4«.ingle
1., Il . -• .'Tx i' II* .ingle
I llllill li.-.iiii. S'l* l"f fi»>'
W,l.. i'x:;'
i I p, ll„ 2 2"^ r .|» .ingle
''' il.. rt., 1 3j'X.)"4.4».1liglc
' lliiilllie.iin. ;,S« per lo"l |:iiilr-lie.nn. ("is* |)er (mil
I Well, I'x V
Will, I'X 50'
I I'.iiill-lii.iiii. Sli« per (■"'1
1 Well, J-X27''
<li-
.1 I'p, rt„ 2 2j"x ^" 4,4* angle I'p, rt, 2 21' m' s.;* angle
I., rt,, 1 J'Xj" 5* .mgle
I'p. rt„2 i"^:\' 4, s« angle I'p. rt., 2 2'x 3I' fi,)* angle
I., rt., 2 2'x ;!' s,.i# angle 1., rt„ 2 i'x / 7,2* angle
Hnililie.im. i'># per (out liuilt-lieain, f/ij* per (nut
Well, r'^.P' ' ^^'''''' rx,3"'
I'p. rt., 2 2 ' X )" 5* angle Lp, rt., 2 21'' X j' r..7» .ingle
l„ «.. s 3'X j" 5.i>» angle i I,, fl., 3 j'XjJ* 7.7* angle
_ _ 1
linill.lie.ini. ii;« per (""I Hiiill-lieani, (*)» jier (not
Well, J''*<r'" Will. |"X p'
I'p, rt . 2 .rx^" 7.2* .ingle
I,. 11., J j"Xj"8.4#aiigle
lliilll-lieain. 75* per (mil IIiiilt-lH'ani, .Sl« per (mit
Well, I'/X Vt" Well, rj'XlS'
I'p.rt,, 2 2f X2i|'(i,.s«angl. I'p. rt.. 2 2"x ,l'ri,4*angle
I., rt,. 2 J'X)' 7,2* angle l„ rt,, 2 .fx )" 7,2* angle
Ilnlll III ,1111, ,s.'i« p< r Imii
Well, ,'',,"xj,S''
I'p. H„ 2 2rX3''fi,7#angle
I ■ 11,, 2 r'<.ir77#a"Klc
I'liilt-lii ,1111, .S(i* per (mil
Well, ,'„"x>S'
I'p, rt.. 2 j'x 55" 7,7«.iiigli
I.. fl.,^3'XJ"S..(*angle
'3
L. rt.,i2j''x2|'6.5# angle
I'.ullt.lie.inl, SSl* I'll I'l"' liniltlieani, !.;(* per (i"'l
Will, I'v.-'S"' : Well, 1-x,,''
I'p. rt., 2 j'xjJVi s« .niglf ' I', tl, 2 j'x -,'(*. ingle
I.. II., 2 2''x i' 's#.iiigle III,-' 'l'- ;" ii:#.ingle
i
Unlit lieani, s''!« per (nut llnilt'-lie.iiii. i.s» pir (mil
Well, l"x i<
lliilll-lieain. 70* per fnnl
Well. I'X p"
rp, II., 2 I'x jl"; 7# angle
1,. rt.. 2 fx i" S.,|» angle
Uniltlieam. 764* jwr d
Will, fi/X,;"
l'p,rt„2 2rx2j'ri,s« '■ III l'p.rt„ 2 2i"x 5' (-.,:« angle
I,. rt„ 2 3'X3" 7.2#aii.;i. I I,, fl., 3 3'X3l'' 7.7* angle
Ilulltlicam, 82l# per (mil
Well, />,'x.,S'
llnllllie.ini. 7.S# per I I llnlll-lieani, S(i# per (""l
Will. t'',."'<,V'" Well. ,»,,''X3.S'
I'll, rt,, 2 2'xj|'(i..|*,ii'. 'i| lp, rt„ 2 3'x !j' 7.7#angk
l„ rt„ 2 3'X3' 7,2* ,111.;!' I,, rt,, 2 3'X j' S,.|« .angle
Illllll lieani, 75* per (not
Well, ,''fl"X vi"
Itulll-lieani. 7oi# per t' ■ '
Well. ^,-X;7'
l■||, rt„ 2 2-x 5|"l,.,,«.llil
I., rt., 2 3'X )' 7.2«.iiH'.K
Ilnlll beam, ,S2l# per (i"ii
Well, ^/XiS-
I'liilllieam, S<)# per fnnt
i Well, ,■',., "xj.S'
I'p, rt,. 2 3''X3"8,.|« angle
l„ rt.. 2 .j"'*.!!' y* '""git'
llnilt-lieam, i)I# per (mil
Well, r'./x.vS'
I'p. rt, 2,V'x ,i"iri»,iii^k
1„ rt,, 2 i"x (" ii.7» ;iiinle
IllllltlnMni, I).)* pel l""l
Well. ,'..,' X3S''
lp, II., 2 3'X4''i),7«,in(',l.
1„ rt,, 2 3°X3J'' io,.|* aiiiji
Hiiilt Kani. .Sf)» per fimt
Well. ,VX;S-
Ip. 11,. 2 3 ■ X !'' ,S,4« angle
I,, rt., 2 3"X3l" y# angle
Uniltlieam, 91* per (out
Well, i-'.-XiS-
VV, I, I " X 2.,' W.li, l" X ,„ ' Well, ,', • X ,4' Well, f,x 3V j ^^ eii, ,-, • X 3h •
I'p II • •'X2i'' i,5#,ingle rp,rt..2 J'- ■,l'l..4#aiigle|rp,rt„22f X2i''(..s«angle;rp.rt„22j"X3'(i,7*,i.Kle,l'p,il,.23'X3j''i,«.ingle
I rt '• •'X3l' 5,3* angle I.. II. 2 I'x ;' 7 2# angle I I.. rt„ 2 3' X 3- 7,2* angle 1.. rt., 2 3'X3j' 7,7« angle , 1,. rt. 2 3'x 4" i,,;* angle
Hullt lieani, i>S» per font
W'll'. ,•■„■ X3S"
l'li,ll.,2 )''x,-,!'ii-.l» angle
I., rt., 2 i"x jj" 1 1,7* angle
llnilllieain, ioi# per (out
Well, iV.'XjS'
I'p, ll . 2 3"X4'' 11,2* aiii;U
1„ rt,, 2 3''X4' 1 2.7* .mgle
lliiill-liiMin, S^i* I" I I'
Well. I'x,
I'.iiill I'l.iiii. '-,' = pii (""I I liiiill lie.iin. 7(il# pii ("I'l I Ilnlll lieain, Ss* 1
' ""■-•■' W'lli, /i,,,"X3S'' 1 Well, ,'.,'X3S" | Weli. ,
W'.l., i"> 31 ■
Well. iV,"X,s'
■am, Ss* per l.'.l Hnllllu am, f)4« per f'loi ! Ilnlll liiani, I0|» pel l.i"l
- ■"" Well. ,'.,'X3S" W'eli. ,^,.,"X3,S'
I'p, rt.. 2 3"x 4' .i.7« angle I I'p. rt.. 2 3l"x |" u-S.nv.le
Well 1"^ '" \\ili, 1 > ;i. wen. J-,; A i^ ..ll., f,,, ^.ji . I., -.r- I..
I',, li ■ -r < •(- I -« .nigli II'- Il . - -•'.■ ■ ;■• (■-* ■"'kI^' I I'P- "•• - -i'x 2i''(..5»angle I I'p. rt.. 2 ^'x^' 72* .iii..!. I'p, rt.. 2 3-x 4' .,.7« angle I'p. rt.. 2 3S-X , ' 1 2« .in,le
I. ll„ 2"2l"X2|'' SI* ...i^'l"-' ; 1- rt,. 2 3"; .[. 7 7«.'»>!l^' 1 I" II" -■ -i'x.r 7-2# angle j I.. 11., 2 3"X3'' 8.4* angli I. rt„ 2 3'X3i' to.,,* angle I., rt„ 2 3i X4' I3.'*.n'gle
I liiiil, 111 „„ <i>l« „. , l""t ' lliiill-lieani, 1 -■= p. r L-.l : H l-eam, 7S# pel (uol ' llnill-lie.ini, SC* per (""i nnlli-lieam, .>S# per foot lluill-lieam. ICX* per ("..1
' ' Wili.l-. ,-,..'■ W'll, ,V"x,„" iWili, ,"„-X3S' ! Will, ,'■.,• x,S" {Well. ,V''X3S"
x ;i'r,..,#aiii'.le; Tp. rt. 2 ,\~'-}\' ; ;3 •'!'.■'• ; lp, rt.. 2 3''X3.rio..|#anjL j Tp. :!.. 2 4j"- .f I2.ii».i
W. Il, I"/ p"
I'
n, ,1 ■ •"' i-|*.ingl.- 1 I'. H. 2 i"- r ;■-!» •"'>;l^ Iprt. 2 2-X3i',V.,#,i,iKle; rp. rt..2 3-X3i- ; ;= ■'i'.> j 1 p.n..2 3-x.!i io.|«:anj,le ; l p. :.. 2 4 "4 .2.i,*.,i.K.e
1, ,|.,V4"'X3'(,.7#.ingle jl.,rt,2 rxr::#..ngl«^ I . rt. 2 i'x 3" 7 -•# ..ngle :l..rt.,2 v'x 3- S..,» ..m;Ie , I.. 11,. 2 3'x 3i- u,7# ..ngle | 1„ rt„ 2 3i '< 4 i.V'.#;.ugle
14
'5'
18'
22'
23
24
K.-ailway. M' Clear, ' Roailwav if.' Cle .r. K.niilwav, i8' Clear Roailway, ao' Clear Koailway. 22' Clear,
Koailway. 24' Clear. ,';,'";„,
»1.
\
•«Si>
■■-^ . m
^^fflj'w
%
\
i
w
Pail. 1
Koailway. 12 Clear.
,!■>« I
u, yM\
lo' ,;o# I
^o\■ y\*\
l:iiilt hum, iSia |n-r I'.int
Wil., l"x t
Roailway, 14' Clear.
ioJ",iil#I
Kuailwa
IJ".|J#I,.,
Ituilt-lic.nti,
Will, l"xi,
Up. II., I 2"
I., n., -• c"x
18'
■9
1::" .l-'*!, iir I ;'.(:# I.'
Iluillln'.im, jSJ* per fool lluilllH.iin,
Well, J'Xi.S" ; \Vil>, 1' X:,
I'p. 11., 2 .:"x:!>' ;,.5* •'"«!'■ ' I'l'- ''•■ - -"
I.. 11.. 2 j"xj.i";,.s#.in);le I- ll., -• .-"x
ij'.i:#I, or ;i3".So»I'
li\iilll>eai\i, viS* l"r f""' i liiiill-'"-!"'.
\Vcl>, J'xiS" ' : Well, I'xj
Cp. fl, .- j'x.'l' v.S«.iiinle I p. 11., -• i"
I., rl,, .• .-"x ;■' |# .mule . I., ll., J 2")<
!-•' .|j#i. .11 ij";;"*!.!
liuilllu-.iin, .|i* pel f""l I lUiiU-Ueain,
Wei., rxh," IWel.. I'x:
fp. ll., 2 yx.'i" _^.5#an(;le Tp. ll., J 2"
I., tl., -' yx;,'' ,)# allele . 1,. il„ .' :'>
i.'".ir#I, ..1 lV'.^o»I.
lUiill l.eani, i-'l* per f....t lliiilll.. am,
I Wei., !"< -o ' i Web, V'x:
|..ll, .- .'"X _-r •,.^«.inule ' Tp, ll., -■ --"x i\' ;.5# ai.};le I'p. ll., -■ :'
1 . ll , 2 '"x -y v>» an.ule I., ll , J :"x ;■' I* ■>"(;>>■■ i l- I'-. •: 2")
ir .i.'«I. ..1 ,ii"5o»I, ..r j' 5" .10*1.
Piiili-beam. 3Sl« pi 1 l.n.i Huili-he.im, .|:1« p.r f.i.>t liuilllie.ini
Uel., fXis" i Wei., }"x JO" IWel., l"x.
Ip. ll., • .'"x.-r .v;«anule Tp ll,. • .-"x.'r v^*•l",l;le Tp. ll.. : .'
I 1! . ' J X iV \\1t .^ll^;le I., ll, 2 .-'x '/ .(* allele : I., ll., J .' ' ^
1,- |;3 I, ..1 1^" :;o»I, ..r [15' 50*1.
Pmlt-l.eain, vi!* per f""l M.i.ii-I.e.im, .( |* p. 1 f'.'.t liiiill lie.im
Well, )"x,S- W.I., I'xji" ,\Vel., 1"X
Ip. tl., z j'x 'i' v>«-'"e.l'' l"l'' 'I. - 2"x;i\v.;*.»i'Kl>-' I'P- "•• - -
1,- ll., : 2"x ;' .|«.ii,Mle I., ll., 2 2"x^"4# allele , I., ll.. -• sj"
I .'" .(2* I. ..r 1 S" .^o* I, ..I ! I .V 50* X
lli.ill-lie.im, V)** per f.".l Huiltl.. am, .(5* pel f.".! liuiU l.eani
Wei., l-><'^" ' Well, I'x 3-" W.I., I'x
, Tp. ll , .' j"x :Y ;.;» .iiiBle I'l'. ll., 2 -•■x .-r vi* -'"Kle Ip- ll . •! ^
I I., ll., -• i'x j' 4#,lllKk- j I., fl.. 2 I'XJ- .)« ailKle I 1.. tl.. 2 2"
"i2'42»I,..r |l.S'.5o#i,..r | l!„i|,.l,..am
: P..iili-|.e.im. .|i# pel fo.,i liiuli-I.e.uii, ,|i« I'er I. ...I | ^^.^^^
Wei., r XI,,- Well, r >■-■.' !(■ ,1 , ,
fp. ll, 2 2"X2r.!.;«.m^;l. fp. II. 2 2-x,r .v;*--"'.''.!'- ,',, ', ,.
1.. ll, 2 -•" X ',■ .|» .uiKle , 1- ll-. -• •:'■'' 1" t* -"'K'e- , ''__'"
I ,- , .a T ..r ll" SO* I. "f i> •.. 1
I- 4--* !■ ■" [J ' ■»■' 1 lluill-lieaii
i liiiill-ln.im, 42i« per f....l llmlt-lie.ini, 4.* j.er f....l ^^.^^^ ...^
: Wei., i" ' --O- Wei.. I'x 2^ ,. '',,
1 l-p. ll, 2 2-x 2r 15« .ii.Kle ^ l-p. ll , 2_2'x 2i\?.5* »"«le , '^j _ ' ",
I., ll, 2 2"x ;,• .t#.mKle
I 15" V,»I, ..r
I., ll, • I'y- \'' 4#annle
I \' V* J, <
lUiitl-hean
Uiiili-I.e.ini, n« per f""t llmll-l.e ,1111, soJ» per I....1 \^^^^ y^
Wei., r^-i' Web, I'X^f'" I-,, ,1 ,
l-l.. ll, 2 2-X21- v;«ani.le I'p. ll, 2 2'x 2i" 1^« aM,-le 1. ;;;
p. I
1.. ll.
;■ |# aiiKle I.- tl-. -' -' * )" 4* •'iik1>;
I., ll, 2 2'
iVv-»I. "1 ^,0;,.«I, ..1 'ituili-K-aii
llmli-lnam, 4;* per l""l Hmll-li. .1111. ';2» per I....I ^^.^^^
Wei.. T"--' iWel.. rx24' I-,, t'l -
fp. ll.,2 2'X2r •,.5»aiH',le l-p. ll. 22" xjj' 4- S#.->iH',le '' ■/,
I., tl , 2 I'f-s' 4» allele
is" v.#I. ..r -
limit l.eaiii, -tC* per fmil
Wei., i'x 2i-
I., ll.. 2 2''x ',!" .;■•,« -1";
Hiiilt-lieam. i;2l# per (....I lliiill-i.e.ii
Wei., l"X2s' Wei.,!""
Tp. II, 2 2''x2r4 >#-iiii'ie rp.ti., 2 .
I tl, 2 2-X (M#.">M.l'- ['•■"•-- .1 -i ^
|>"V«I.'" I |l,iiltl.i-.iiii, q;» i'er I....I limit l.eai
P„„lll»..m. p-i»pei (....1 ,^^.,,, J.., „,. W.l., r>
Wel.,rx-r , ri.. tl, • 2"X2r I sSaiiKle rp 11,2
r,,.il,2 2 «2l ;s«...el. I „,,..x,J',.,«.,„j;le 1.11.2 J
I, tl.
-■"- !" I#-
I'.in.l
IS' i'l*!. '•' |l„illl.>-am. SI*).. 1 l-.l I'.uill-lH'il'
I'-eil 1" ■ I '* I" ' ' ■ ' Well, i"X 27* \V el.. I":
^^'' ''■*""''' ,. » 1 i-p.ii...'-'-x-l-|-^*'"H'i' I'P "■•J
I |, ll,2 2"x:l" !.s« mul.- I 1^1 .-.-x il- s,t« in,.,l. I..ll,22
I., ll, 2 2"x i" 4«anKli 1
Kna.lway. 1 a CI ar
K.M lw.iv, 14 CI. .11
Koal
TABLE XX,
TABLE OF FLOOR BEAMS.
CLASS B
Roailway. M' CU'ar. Koaitw.iy, lO' Clear. Roailway, i8' Clear. Roailway, 20' Clear. KuaJway, 22' Clear.
Roadway, 24' Clear. i,''^"^!
' ^ Length.
loj- ill* I
|J".|.'#I, i>r
l(uill-l)c.ini, 3SJ# per font
Wth, J'X iS-
I'p. II.,; j"x.vi';,.f;* •'»«'>-■
I.. Il, .' j'> -vl" .'vS* •!"«''■
1J".(.'#I, nr
llnill.|ic.\iM, .|i,J# |ii-r fniii
Weh, l"xi,|' '
Ip. 11., : : ' :l",v.S*.>iit;li-
I.. 11., J _• X ;" .|#.iMv.le
i;'.,:#I,„r
Huill.lii.itn, \},\^ per fiiDt
Well, \" X .-o"
I'p. 11., J :"x jI" v5* •'|'k1<.'
I., ll., .! .'" X j" 4# .-iiikIc
|J".|:#I. or I 15" 50* I "f
lliiilllieain, Vll* I'l' l'"ol ; liuiltlie.lm. 15# per f.i.il
Well, J"x |S" ! Will, 1"> .-i"
Ip. ll , -• -•">< -'l' v.i*-i"Kl^' I'l'- ll' - -■ < -1" .Vli* '""K'^'
1.. ll,. -• -•" x ,\" |» .ui.nle 1 I., ll., .: -• X ;" .)# angle
1:" .|j»I, ..1 ;i3"5"*I."r
lliiill he.iiii, .(i« per f.M>t : lUiilllieain, .|ii# per fciul
Wei., yy. M' : Wei., |"x:y'
I'p. ll., -• '"x.-r 3. ;« angle l].. ll., : y x:r' j.;* aiigk
1., ll., 1 ::"x ;■' .)# angle . !.. ll., -• : ' ■ i" I* -'"K't'
IJ".!-'*!, MI ' 15" 50#I, "r
linill beam, i-'lS per foot ' Hnil|.|ieain, .(:S# I'er (o.it
Wei., l"X.-o ' I Web, |"x j;"
.;lo ' I'p. ll., -■ :!"x zV i.5» angle V\: ll., -• :' x zV 'vSWangli
le jl,. ll, .' n'x;- .(». ingle | I., ll, -• ;" x ;' 4#juigle
1 15' 50*1, •■! 1 1 5" 50* !• "I-
il ' Unill.heani, .|.'1« pir Inol | ItnillI.e.iMi, |.)« per f.iol
! Weh, J"x:c- i Wei., fx,;"
igle fp ll.. -■ j"x.-r ; ;«.inule I'p. ll., -' .• " x : J " j. 5* •''»«1'^
Ir 1. ll. .: j"x ," 1* angle : 1.. ll., J -• ' x t' 4* angle
1^" v.»I, or I r.i' :;o»I, or
,1 l;ii;il-lie.lnl, .(,|« p. r font lUlill lie.iin, ;ii#perfo.il
\V,I., i'X.-l" , Wei., i'X.M,'
,glr I'p. ll., J ::'x.'J" v;*.rngle I'p. II.. ^ .' ' x •,' .i# angle
I., ll, r 2" X ;,'.(« angle , I., ll., .: jT < ;" |..l* angle
I ;" \ot\. Ml ! 15" 50*1, Ml
.1 liiiili l>. am, -i^* per I'mmI llnill l.eain, ;i !« pi r ImmI
.Well, J-X2:"' Wei., I'x-;-
igle I'p. n., : :'x .'!' ,vi* ■'"Kle t'l'. ll . .: '-" < -T \->* ••>"«l'-'
I., tl.. 2 3"x ?" !« .ingle , I., ll., -' ;"> ;' 5* •■•"kI'-'
l.S' 50* L '"■ j Hiiiliheam, ;-'l# I'cr f.iMi
1 I lUnlt.lie.un, .)(* per lui.l | ... .,, i"x ••!.''
... 1. 1 ,• ^. . >* I ' ^
15" 50*1, iir
lliiilt.lii'.ini, .i'.# per fmit
Wei., l"x j:"
I'p. II., J i'^i\' .).5#angl
1.. ll., .' j"x j" |# angle
15" ifM I, (.r
r.itill luMin, .(S.l* per I'omI
Wei., I x.-.|" '
., ., , 1.,. , . i I'inll lieani, ?.(# per fmit
r.uilM.eain, 5ol# per flint ,,. , ,, ,
Well, V'XJd'
Well, J'X27"
,. , ■ , ,, ^ , ' !'■ II.. 2 .I'X l" .».i# angle
L'p.ll.,.yx..4'j.s#..ng|. , „.,...l'x,"5Vangle
I.. II., .' 2" X 5"., Wangle \ S ^* h
15" 50* I, or
l:nill.l.ea,n, s\\* l>^r f....t ' l''"l'-'«^»n<. 55l# 1'" foot
Weli,J"x..,« Weli,i'x../
Iliiill-licain, 5.SJ# per foot
Well, }"x 30"
Up. fl., :: 2"X25"4,5#aiiglc
I.. H., 2 2"X3j" 5.3# angle
Huilt-lieam, 62# per foot
Well, J' X 30'
lp.ll.,.-y'x:i" 5;#.nngle I'p. ll., . ."x -i'+S* angle ' I'- H- = ='X:i" 4.;# angle Vp.ll.,. ^J'x j'5-5#-->ngle
11'
I., ll., J J' X 3 " ;|#'.u.gle I I.. II., .' zV X 3" 5# angle_ ' "'• - -i "^ 3° 5# angle
15' 50* T, or I
llniUlie.mi, ;ol# ii.'t fuol 1 ''"i"''".'-"". 54j# pcr foot |;,nli.bcain, 57# per foot
Well, r'x.O'" iWel,,l-x:!7' \V,h,}'X3o'
I'M 11 . ."x-r •c«inele"-'l'''l"""''=l ■'■■'5*^"'^'' I >. ll., 3 =' X .;r 4.^^ .angle
1.'h.!; ; "xr i*;n*o ' i '■■ "'• = =rxyjW^ l . .l..--^'X3i-,3*.angle
l:'nil|.l!.nm,"si !# per foot | ""il'-l'^'a"'. 5Si# 1'" foot i;,i,l,.l,ean,, Tx* per foot
Wel,,i"xr4''' Wcli,rx=S" U>l,, i-X3o"
l-p. 11., 3 3'X:r.,.5#angle^'l''"" - ""''-i -fS* angU I ,. il., : 2-X3' ;# .-.ngle
I., tl, 2 2j"X3" ;#angle j '- "" ^ =i">^3'' 5# a»Kle I ll , i^'^i' 5.9# angle
I, ll., 2 2}"X2}"6.5#.inglc
IJuilt-lK'ain, 63j# per foot
Well, }"X30''
Up. tl., 2 2"X3" 6# angle
1.. n., 2 2j"X3"6.7#angle
1
Huilt-licani, ri5# per foot i
Web, J'X3o"
L'p. ll.. 23' X3»fi.5# angle !
L. fl., 2 3"X3" 7.2#angle
13'
lUlillbe.iln, 5:1# pel f.M.I ; lluill.beain, 57* per foot , r.iiilt-lieani, 62# per foot llnill beam. (r\% per foot
Web, 1"X25' Well, j"X2i)' W.b, J'xio" Web, i'Xjo"
I'p. ll., 2 2"X2J' 4, 5» angle • I'p. ll., ; 2"x :J' 4.5* angl« IV il , 2 2i''X3' 5.5# angle
I,, tl, 2 2i"X3' 5« angle ' I., fl., 2 2"X3l' 5.3* angle I ll., 2 2}"X23" 6.5# angle
*> I o, J ^ iu
L'p. ll,, 2 3"X 3" 7.2# angle I
1.. fl., 2 3'X3J" 7.7#angle I
'4
ISuiltbeam, vij* l"^r foot j llnill beam, 59# per foot buill-lieam, (,},\* |icr foot HniH-lieam, 70* per foot
Well, i"x:i,' i Web, )-'X;o' Wib, i-X3o'' Web, ("Xjo* ,
l'p. fl., 2 2'X2l"4.;#anglc!L'p.fl., 2 2r'X2r.t.9#angl. i ]. fl., 2 2'X 3" 1* .angle ^V'^- - .'i'x 34" 7--# angle
1.. II, 2 2j"X3'5#.ingle 1 I,, fl., 2 2-X3i" 5.3* an;, - I il., 2 2j"X3' i'.7# angle j I- fl- 2 3"x 3" S.4# .angle |
liuilt-beam, 75* per foot
..en, * 'v ->J ..en, 4 '^ ^ ,. . i., ^ " .>" .»eij, j-j ^3'*
l'p. ll, 2 2"X 24' 4.5* angle l'p. fl., 2 2'X3' 5* angle Ip. fl., 2 3"X 3" b.s* angle l'p. fl., 2 2fx 2j"(i.5# .lngle
l.. fl., 2 2l'X3' 5# angle 1.. fl., 2 3"X3" 5.9#anglc I fl., 2 3"X3" 7.2# angle
I'.uili beam, "# per foot 1 linilt-beani, b2# per foot ' liailt-lieam, 70* per foot
Well, I" X 2./' ; Web, J" X 30' Web, J' X 30'
llnill-beam, 555* per fooi lluilt-beani, 6o# per foot liuilt-beam, CjJ* per foot
Web, \' X 2.S' Web, J" X 30" W >b, \ ' X 30'
.. »...,» ... 1 ,, .t __«,..»-*. 1. 1.. .1 . .n ^ ,» ,■ .^^ 1..
lUiilt-lieani, 76J# per foot |
Well, IX2.;' i Wei), J X30 "en, t ^3" ^^ il'. T'.!"x 35" j^,
l'p. fl„ 2 2rx 2I' 4.<)# angle' l'p. fl., 2 2J-X 3' i;.5# angle l'p. ll, 2 3'X3i" 7.7* angle L'p.fl.,2 2j"x 2:i"6.5*angle
I.. fl., 2 2r'x 21" 5.,)* angle I I,, fl., 2 2}'x 2}' (i.5# angle L. I, 2 3"X3'S.4#angle , L. fl., 2 3''X3' 7.2^ .mgle .
Uiili.beam, s^* per fool j llnili-bcam, (n,\* per fo, 1 : l;nilt.lie.am, 75* per foot liuillbcam, 78* per foot
Web. J"x,o' iWeb, J'Xio" Web, |»j'X34'' | Web, ,■•,'■ x 36'
' .•..".-■■' i-r I Web J X'!,' Wei., J X',o j W el., J X. ;o "en, fj -v j4 | ■■>■■. m ".v
hVeb, \-S2i' 1^. • , ,->,,,.^.5#a„(,U l-p.tl,2 2rx:r'4..»#angle l'p, fl.. 2 2"X5"r*an i. i I'p.fl., 2 2;'x 2rf..5# angle : Up. «.. 2 2i"x 2^' ('..sSangle
„g|.. l'p, fl.2 2"x.-r3,5«angle , ^^ , ,-x a'" =.,# angle | I., fl., 2 2rx 2^ 5.4* angle |l,. fl., 2 2.4' X 3" f,.7# ..n.. I . ll, 2 3-x 3- 7,.* angle I., fl., 2 3' x 3- 7.2# angle
j I,, fl., 2 2"x i" 4#,ingle _ ! ' - -
lit
ngic
15" i;o# I, or j |.,||||.|„..|,„^ ^,|# |„,|- f,„,| ! II, lilt, beam, (o* pel foot ' llnill-beam, b;* per 1.
linill-beam. .p# |ier foot ^^.^^^^ ^.^ . - j ^y^.,^^ j.^ ,,,. ^y^.,,^ l"X3o"
^^'•■''' rx25' |. ,'| , ."y,l'4.5#angleiUp. fl,2 '''x ij' i;.,* angle l'p. ll, 2 2'X 3!- (.,.1* ,1
Up. II, 2 2'x2l 3-5*»"*;l^' , I.. „., , ,»x if' 5.5« angle | I,, fl., 2 f '^ i" .s..;# .mgle . I,, fl., 2 3"X3' 7-»->"-
L fl., 2 2"X3' 4»angle -' |
IJuilt-beam, 76i# per foot
Weh, ft" X 35'
Hiiilt-beam, ,Si# per foot
Weli,ft'X3,S'
Up.fl.,2 2J"'x2f"fi.5#aiigle;Up.rt.,2 2f X2j"fi.5«angle
I., tl, 2 fxy 7.2« angle I L. fl., 2 3''X3" 7.2# angle
18'
■ 9
I5'50#l.o, i;„i;i.beain i;;«p.ifoot ' llnilt.be.un, fii i# |.. 1 fool ! llmlllieam, fi7j» p. 1 i.
t I llnill-beam, sol* per lo.il „•.,!, i-yvS i Web, ("x ,0' Web, I'Xjo-
Web, J'X2(." " '
Web, J'X2l." ,.|, ij^ , ,;v,jv,.5#.,„^ii.lrp,fl„22l''X5' .;.i;#.ingle:i'p.fl„22rx3-::»
ngle Up. ri„ 2 2'x 2i' 3,-,* angle ^ ^ __,^ , ^ |^, ^ „ _ , ,.^^j. f,^^ _^,,j,|^, | , „^ _, ^-^ 3!' 7.7s ..
I.. 11.2 2" x; 4* angle '^
llnill-beam, 7S# per fool | Ituill-be.am. Si;* per foot
Web, ft' X 3(1" ! Web, ft'X3,S-
I'p. ll, 2 2'X3l" fi.4# angle , Up. ll, 2 \"-<f 7. 2# angle
1 , fl., 2 ;,"y }," 7.2# angle
IS" v.»I.oi
ltuilt-b( am, i;2» per fool
Well, J'X24'
Itnilllieam, v* per foot
Web, ("x:,,-
Wel.,rx2r U|i.fl.,2 2i'"'2r,|.'(«angle;U|., fl., 2 2"X3'l*,ingle
ngle , Uii. fl.. 2 2-x .J 4.S# angle ' '^ - ,^^ „^^ , ,..^_,, (,^,^ ^,„^,
Iliiilllieam, fi3l« per foot | llniltbeam. 70* per I'...
Web, fxp" j Web, J'xjo'
U].. fl., 2 3"X3r7.7«.
lluilt-bcam, 711,1* per foot
Web, ft'X37'"
l'|i. ll, 2 2"X3l'6.4#angle
L. fl., 2 i"X3' S,4# angle
Uii. fl.. 2 2"x .J'4.S# angle ^ ' ^'^ -■' ,: _ ;^^^|^. ' ^ ^^] ]-,^ ^.. (,,^ ^,„^,^. I ^ „ _ , ^.'^j. s.4#,„v.'- I. fl.. 2 3'X3' 7.2* angl
I., ft., 2 2''X3l'' v.«'1"kI<' , - - !
I»am,,2j«,ierf.io, l.nilt-be.im. ,s« pe, foot I llnil, b. .u„. o;# per foot ' Ilnillbeiin, 7.« per f- l^nl,-lie,i,n^ Si* pe, loot
Web, l-x._s" Well, i-X3o- W , b, i ' x ,o' Web, ft'X54 Web, rtX3,S
llnill beam, S(># per fool
Web,ft-X3S" J,,
Up.ll, 23" X3i'7.7#. angle
I., fl., 2 3"X3",S.4#angle
lliiill-be.im, .Si)# per loot
■Web, ,»,"X3S'
rV'^^^^'.-WwIeT fl^'^r>>r,.|*angU :;; 2V;U-<M*a,,gle: X^ .■ l'p. fl.! 2 2-x 3r .M*angle Up. ll, 2 3-x 3" S.4* angle
:"«'' t.'fl,";^-X3l^.;;!::u ;..' fl !:^i5,^j*3!,;;:4.^, ,.',,.,: 3" X 3- 7.2* V l'l.^rx3^^*ang;, I., fl., 2 3' X 3" 7.2* ..ngle ... tl. 2 3-x 3 r 9* angle ,
1, i.-i .*peri ib,i,.-i..,..p...io,., '^.......,.^.. -;--M*.- is'ft"^.r""""" ^!:;:-:p^-'-
W.l'.i-^"" . '^•'■•1'^;?". ,._.. ,.. ,'.''';,'.,;:.,.,.,*.. ',-„,;':.rx.r„..*,K . rp,„.,.,l-x 3- n.7# angle l U,.. H,, 2 3-x 3r"» angle
I fl.. 2 3'X3l-7.7#angle 1,. fl., 2 j"x 4' .).7# -mgle
'" Iw.bl'vo- Web, rX30' Web, l-x,o' Web, ,;, X35
i,-,, ,1 . .-y .1" , -^tt.iiiele l'|. fl, 2 2-x il' .;.•,# .mgle Up. fl.. -• ■l-x ,' (.,7#aiigle Up.fl.,22j X2I (:;»
""^''' I ,1 '. ."x ,[•" ,. ,« angle , 1.. ll. 2 ,'■ x ,- ;..|» .."Kl^' !■■ »■. -' -l" x 31" 7.7* angle j I,, fl., 2 3"x l' 7-2* an;
23
p.mlibeaiii. i;i«|"i loot Iluill beam. 11 ;a per fool
'* Well, rx 27- ^^''l
Iliiilllieam, (■«)# per foot ' llnill-beam, -S« pel f.
W.b, \--x io- , Will, ,■•,,'
Uuli-beam, S-s» per b.oi ' llnilibeam, ii4« per fool
Web. ft-X!>*-
:*]B'::f;:;:£ ;^:ii;-':.:i'sf l^J'^v^Vis^:^' :^v!v;^x:i '-;"n-^i-';,;.::f r';,:';;-i^i^;;:j::S
Koa.lwav, 14 I'll .11
Ro.i Iw.iv ,1. Cb- ir.
Rna.lwav. 18' Clear. Roa.lwav. W CI. ai Roa.lwav. 22' Clear. Roa.lway, 24' Clear,
U.mel
l.ellglll.
M
Panel
Length.
T^?
i
i< ^^B?*-*
\
Panel I
Roadway, 22' Clear.
RoaJway. „• Clear. ^^^^^
i
I
^^|^*"*Jrgp^?S!jB^*.-
J-
\
I
)
Lr ■•.h KiLulway. w Clear. Roadway, 14' Clear,
.■■,(* I
"!«I
in- v-^i
10" JO* I
10" ,^o# I
loi- jij#l
I
>9
2i
»1
i;"4J«I, or
IWiill'lH'ani. .?Sj« pel fiiiit
k/ '.oa I I Well, J"X iS"
l|>. a. 2 :"x-\" !.!;» .in};li'
1.. tl., 2 ;"x jj" ^.5«.■lll^U■
|i;".i:«I. ...
: liuill l.l.llll. iSJ* p.'l I.I..1
I' !'J«I Wfll, \"X iS'
1 Tp. II., 2 2'y- -r ;, 5* .iMv.li'
I 1,. 11., r j-vjj" .v.';«.iivl'
|i;-4^«I. "i
lj".io#I i \Vcl>, J'x iS'
lip. II., .• j'xrj ";,.!;« .inglc
I 11. II.. .• .'"X 5* 4*anylc
i I.-". I .•*!,.. I
' IUiill-l>c.nii, 4I# per foot
loi" jijal I Well, I'Xi.,'
] I'p. II., 2 .I'x.-r.v.'i*. ingle
I., n., J c'x f 4»an^;k•
l.•"4J#I, ..t i-'- .i-'aj, ,.r
lliiilt 1>c.iin, 3>>5* pi 1 I. ."I r.iiili lie.im, |-'t« ].et (....i
Well, J"X i.S- ' Wei.. 1"X -o"
I'p. Il , • .;"x .•!" ).^» .innle I'p. ll.. -' -'■x.'J" j..;" ■'"Kie
I, ll., -■ 2">i2\" j.5« angle | I., ll., 2 .-'Xj' 4* angle
I-" 4-'* !• "f ";" i°*J.- '"
lliiill-lK-.im, iSJa p. I (....1 1 lliiili-lieani, 4.'J* |.ei P.,ii
Will, l"x iS" ; Well, \'x 20'
I p. ll., -• .'"xji" V5# angle ' Iji. ll.. -■ 2~ < 2\" v5*-'ngle
!■ ll ■ " -■"■< -T 3-5* •■>"«'"•■ '•■ "■■ - -"" i' -l* '"'y'^'
|.-"4J#I. ..1 ; 15" 50* I. "I
l:iiili-lie.irii. ;.iS* 1"-' '""' ' l'inl'l"-'>"i. 11* P'''' f""'
Wei), J"xiS" Will. J"x:i"
1 p. ll.. : .!"xjj" v5» angle lip. H., 2 2' X 2\' V5* ^ngle
1 , ll , J J"x j" 4# angle j 1.. ll., 2 I'xf .|» angle
12" 4J#I, III : i>' 50#I. iir
lluill-lie.lln, Vl!« per fmit i limit tieam, 4^» |ier f.i..I
Well, }"x l.S' " : Well. J'Xjj'
I p. rt., 2 2'y- -•}■ ;.s# angle fp. i) , .• .-"x .M" ■,.;* .mgli
1 I.. II.. .' 2'x •;■ 4» angle ' I., ll., J j'x ;" |» angle
I •' 42# J, 111 15" 50* I. iir
Kiiilt-lieani, 4i# per fuol j Ituill-lieam. .{Crit per (....1
Wet., )"X !.)■ i Well, J'x.-;'
' fp. ll., J .:"x.'J" ,i.|;»aiiglei ('p. II., ; :'x .'J' ;,.;» .ingle
I , ll,, 2 -'"x f 4# angle ; I., ll., • 2" x ;" 4* angle
MJ'4.-#I, ... I5'5'->«L"1
|:iiili licani. .\:\1i |ier fnot j lluilllieani, 47 J# |ier I....1
Well, }'y jo' i Well, J-K-'l'
I p. ll., -■ 2'x 2V' !.5» angle I'p. ll.. -■ .'"xji" V5* angle
1 ll. J j'x i' 4#angle ! I., ll. ,-•-•" x ;' 4# angle
'i" .VJ"!. "I i 15' SO* I.'"
ilu.ll lieani. 4|» pel (mil , linilllieain, ,1.|* pel I....1
Wei., j",-:.-!" ! Well. J'XJ5'
I p, ll,. :: ;" ' -r i,s*an;;le Tp. H.. .! .'"x -J' ; :;» .mgle
1. ll.
i' i» .I'lrl
l„ ll..
,1» ,ingle
. ;" 5o« I. 1.1 I ;" ;t* I, ..r
P.iiilll.ea In* per r...l Hililtlieain, 5oJ# pel (....l
Will. \"X22'' ■ Well. J-X.'d-
I p ll. -• J-X -J" J na.iilgle t rpll. J J-x .•)' i,5».lllgle
I ll ,.•.•■'';" 4# angle I., ll, .■ .•' X j" 4» angle
Pan-l
LenK'li
Roa Iway. I J Clear.
Koailway, 14 Clear.
Koailwa'
iy'4.'#I."
Iluill'lu-ain,
Well, \"x,i-
Ip. ll., : .'":
I.. II., -' j'x
ij'.i:»I,i,
lUiill-lieam,
Well, l'Xi>
I' p. tl., J 2">
I., ll.. -• -••x
IJ"4J#I, n
t'.nilt-lieatn,
Well, i"xt(
Tp. ll, J -•":
1.. ll., .' j"X
ij" 4J«I, a
I'liilt-lie.nn,
Well, 1"X|,
I p. ll., -•;":
I., ll., J .'"X
!i-'"4-#I.e
' lliiill.l.eain.
Well, \'X2<
Ip.ll., -•-•"
. I . II., J 2'y.
' ' ':•" .SO* !• '
Hililllie.tm.
Well. \'X2
l-p. II.. .' 2-
j I.. II., J J"X
I "5" 50* I. f
' Huilt-beani.
' Web, 1 " < -•
' I'p. ll., 2 2'
I.. Il„ .' -•"x
I s" V^ I, I
llnill I., am,
Will, yX2
rp. ll,. -.•"
I., ll., J J"X
1 1;'' 50# I. I
llnill-lieani.
Well, j'x -
rp.ll..--.-'
1,. ll., ; J"X
j 15' 50*1.'
' Iliillllicam,
Well, J'x J
L'p. II., 2 2"
I.. II.. 2 'J';
' 1 5' 50# I, .
Illl.ll-l.e.ini.
Wei., i"^-
Ip.ll., .-.•■
i I.. 11., 2 4"
I'.nilt-lieam.
Well. \" • .•
rp.ll.jr
l„ ll. -• .'"X
I lliiiUliram.
' Wil.. 1"X2
r,. ll.,.. -'•
I.. (1., .: -•" X
I
limli III ...n.
Wei., \'x:
Ip. II,, • -•-
I.. (I., - - ■
n.iilt !ie,im.
Well, \'X2
l-p II,, .. 2'
I„ ll. .• -•">
kiw,
TABLE XXI.
TABLE OF FLOOR BEAMS.
CLASS C.
Roiiilway, 14' Clear. Roailway. 16 Clear. Koailway, i8' Clear.
Roadway, 20' Clear. Kuailway, «' Clear. Roadway, 24' Clear. Len"*h
I 10" ;o# I
I 10" iri# J
loj" .ill* I
I.'".1J#I, (.t I2"4J#I, iir
IWiilt-luMin, ii)l# ptr flint I liuilt-lii-.nii, .ni# per font
Well, }"xi,S' " i\Vel,. I'X.V
I'lK II., .• .•"\.-i," vs* .iiiKle I l'|i. II., 2--"xjJ' j,5#,„,kIc
I.. II., - ■'- ' - -" - ' ... - -»--• -
'5".So#I. "r '"5"5o*I.i>r 1 1, ■„ . ,^ , ,
Huil..|Ka,„, .,8J# per fn,„ 1,,„|, wL, ;,# p.r f„„. I ''"'■''"'"'• 5^^* 1- """
'■- Wdi, i"X24" W.I., |-x,(," \,.,^f ,. ^ ,
.^ .•;■■ .VS# .-."Kle i I'p. II.. = .-x ..J- j,5# angle I'p. 11., 2 2" X 2]' .v.S«.."m1' I'l.. H., .- .-'x .^l' ,.5#.-»nglc I '';, "■; ^.' "^.'^ '/i ..'''''r
.-1 ,;..S# .innlc il.. ll..;:2"X.i'4#aimle I.. 11., j ^'x 5' .,# ,,nj;le I il, : ..'x ,' 4» .niKle i'-""--XJt 5-,i» -"'Ble
i.''.(2«I, ,ir ij",(:#I, ..1 15"50«I. iir i;v5«I, ...
Iliiill-hi.iiii, .(o'a i.ii f.ii.l nuill I..Mni, |-,* per f....t llciilli.eaiii, 49j# per (....I linh liiani. 5)# per fi...t liuilllitani, ;;# per font
Well, J'X IS" Weh. \'X2,- I Wei., i'x .'5' Ud., i"x .f," 1 Wel>, i"x -•./'
I'p. II., .' J"x.-|, ;.!;« ant;le Ip. ll.,
I., ll., .• 2'xf I* an
"III. I *jp , wel., I X jj- Wlh, JX-f)" j ■•-■■. ( " -J
«anj;le Ip. ll., .' yy ,{■■ ;.5«aii«lc ] I'p. ll., 2 .•" X ij' 3.^* ai.cl. I p ll., .. .''X j" .|# angle i l-'i''"-- 2'x 2\' .is# m^W
igle^ |l..Jl., J.-"x.iV|«anKle I., ll., .' j'x / 4« an^le 1. ll., J j'x .J' 4.5# angle '■ "•. 2 J'Xjf 5.3* .in«lc
i;"4.'«I,..r i5'5o«I,..i i5"5o#I,..r 1
r.iiilt-l.eani, 41 J» per f....l Huilll.e.im, 41* per f..iil ' ll.nll lie.nn, 5oJ# per f....l '''"H I'™". 53* \"--' '""» i li"dl-lH:im. i>i\« per t I
Wei., 1"X.-..' Wei., j"Xj(j" Wcl., 1"X2(." ; Wei), V'Xp' ! ,y
I'p. ll., J yx .^J' ,,S#.'nj;l.- ^ I ■ "■• - -''^•'" ■'■5* ••>"«'<'•
I,. II., ; J"x ," 4# angle ' ' ' ''• - -I'x .V 5* »"«!<-■
Wei., J'xio"
I'p. ll., -• ■"Xjl" i.5«ai.Kk I'p, ll, : ^x .-J" V5# .mgle
1 ll., : -•'■ X j" I* angle , ].. ll., .• j " x f 4# angle
i:' 4.-«I, i.r 1 1 5' 50* I. or
.1
lliiill l.e.iin. 5SI* |.ei li...t r..ull-lie,iMi, |i la per fc.i.l 1 lluill-lie.iin, .|7# pet f.M.I
Wei., 1"X |,S-" Wei.. l"Xi.,-" i Web. 1"X.'5'
I p. ll, J j"x -J' V5» aiii;!.' I p. ll., J 2" ^ 2]' ;,.5*ani.,le . Up. ll., 2 .-"x j J" 3. 5* angle
1,. II., :; 2' X jj" V5« angle I., ll., -• -■" ^ ;,' ;» .mglc 1 t,. ll., : j'x 3" 4# angle
Well, }'x.-4''
L'p. tl., 2 :;"x.'J" 3.5# :int;le
I., ll, 2 j"X3"4#aiii;lf
j i:" 4J*I. ..r ! t:!" 4J»I, ..I i 1 5" 50* I, ,.i
I llniltl.e.m., 3^ J* p.-i l..'.t ' 1 '.11 ill. In am. \\^^ pt r f.ii.t l.nilt-Iii'ani. .(S^ft per f.n.t
I W.I., 1 "X i.S" " Wcl., I'^.T," '
Ip. ll., J -•■ x.-r 3 5* aiii'l. Ip. ll., : _■'<.''" •,.5# angle
1 I,, ll., -• J'X.'J'' 3.5«angli ■ 1. ll., .' : ' ^ ; ' i« angle
112" 4;* I, or i^'^o*!. ..r ! 15" 50*1, (.r
' r.nill-l.e.iin. 3i).i* per f....l llnili-lieani, 45* per fni.t , Muilllieani, 50!* per P.i.l
Wei., i'x I.S" " Wei., ("x:!- ;Weli, l"x:o'
I I p. ll.. -■ .■"x:J-3.|;« angle l'p. ll.. ; .■■"^: 53. 5* angle : l'p. ll., -' i'x .•{" 3..>* -uml'
I I . ll. .• -■" X 3" 4# .ingle I 1.. ll, :! 2" X 3- ,# angle I., ll, : -'"x 3" 4* angle
1:" 4.'« I, i.r |l5"50»I,or 15'50#I,or
' lluili-l.e.ini, 4i» per fi.i.t ' lUiill-lieani, 41* per font Kiiiltlieam, 51 J# |)er f.>..t
j Wei., J"x K,' Well, 1 ".'.-•.•- 'i Well, J"X-4'
jrp. ll, J J'x.-r 3.5* angle l'p. ll, .• j"*:'." 5.i# angle : l'p. ll, 2 ^''xjj" 4.5#angli
I., ll, ; ;"X3' 4«angle I ,. ll. : j' < ;' i* angle : I,, ll, 2 ifx 3' 5* angle
i-'l-'I.'T i^'SO*I.'.i !>5"50*I."i
lliiill he.ini, t.'l» per li...t llnill I.Lani, |-|3 per (-..,1 ; lliiilil.! ..111, ^.-l* pet (....I
Wei.. l"x.'o" " Wil., \"y 2]' ' Weh, J"x.-5'
. l'p. ll. : j'x.'l" 3.;« .ingie l'p. ll, ■ .' ■ .M " 3.5« angle l'p. ll, -• j"x .ij" 4.,#ang].
I I., ll. 2 2'xy 4# angle I., ll. -■ .'' ■ ;' 1» angle | I,. 11., 3 :\"Xi' 5# angle
H'SoWT. nr K"io»I. .11 I I, ., , .4. , .
, , , ,^ .. , , - . . liuilt-beam, ^5J# per I1...I
I I'.inltl.eam, 4.v(# pet Pi.it lliiilt-lieani, yiS |ier In..! , Y" '
. 1.. ll, = 2" X ," 4# angle ; I ,. ll, .' .-X , 4* a.^gle _^'" --*'*■' 5* ••"t^'-
15" 5o#I, or
llnH'tlieani, ,jj# per f..nt ''"iH-'H'^"', 5.|J.« per fn.-t
Wei., I'X;!,' W.l.. l"Xj,S-
I'p.ll, 2 2-x ," l#.''ngK "I'' "'• - .;"xn"l-5#-'"Kl'.-
I., ll, 2 2"X2V 4.S# :mgle ' ■ ''■• - -i"^ 3" 5# •'"kI<-'
L'p. ll, 2 j'X^i" 4. 5# angle
1.. ll, 2 2'x ;(' 5.-,# angle
liuilt-heani, Co* per font
Wei., rx.P" I ,3'
Up. 11,2 2" X 3" 5# angle
I.. t1.,2 3"X3"5.,j«..ngle I
llnill beam, 53!* pet I....1 KiiiU-I.e.im, ;5i# pet l..nl lUnltl.eam. (.:« per f.i..t
Web, J"XJ(." W.I.. t"X2,/' . Web, J' X 30''
l'p. ll, 2 2"X2r 4.;#.M.:l 1 |.. 11,2 2-X2J' 4.5* angle j l'p. ll, 2 2i"X3" 5.5#atigle
I., ll., 2 2fxf 5# angle I. ll, 2 2l"X3' 5» .ingle I., ll, 2 2i"X2J'' (..j* angle
llnill beam, 544* per l....t biiili-beani, ^7* per |....t llnill-beam, (>,]k* per ln,.t
Web, J"X27'' Will, J'Xp" Web, J'Xjo"
l'p. ll, 2 2"X2j-4.5«ai..:le I p. ll, 2 2" x 2*' 4.5* aiigU 'l'-"- - :"x 3" i*.ingle
I., ll, 2 2i"Xf 5# angle I. ll. 2 2'x^y 5.3# angle | '•••'•• - .: J " x .5 ' <'';* •'"KI';
liniltl.eani, 55}* per f....t I'.nilt-beani, ('k)# ]iet f.n.l . limit-beam. '.5* per foot
Web, }" x 28" Well, J" x 30" j Web, i ' x 30"
l'p. ll, 2 2"X2i'4.5»angl. l'p. II, 2 2'X3" s* angle < I p. ll. 2 3"x 3' ('..5* .mgle
I,, ll, 2 iJ'X 3" 5# angle I., fl., 2 3'X3" 5..j# angle : I., ll. 2 3"X3" 7-* "'gle
4le
W5-5o«I.nr .5' SO* I."' H.,il,-l.e.„n. .,l*l.erf....,
I llnilibeain, .|4# per fnnl ' limit-beam, v.l* per font ,,.^ ;
Web. J"x--." Well, rx2V' ■, ;' -l 1- * 1
j ip. 11:2 2-X2r 3.5* angle, up. ll. 2_2~x ■ 4# angle \\ '-^VJ ^'^ ;^.:;;t
jl,.ll.. 2 2'X3-.,#angle j I.. II, 2 2V' x 3' 4.4* angle \f-»-'-- X^J 5-.l» .mj-l^
llS"i;o«T. or is' so* I. or 1. 11 ,• . .
1 , ,. , , ,„ . . Mill 1.1 am, ssJ* pel I.II. I
1 limit l.e.im.4^«l"r (n-l limit-beam. 51 i» per I.... 1 1 ■■ v v"
Web. J" x.. 2' Web, I" X 20- ;^''';l ""f
ip.ii:2 2-x2r,..».o,g., rp.ri.,2 2-x3 ,*.,ng,e ';,":v,;^i^*:f
i I.. ,1, 2 2'x ,- ,« anglc_ , I.. II, 2 2\-X i ,.,« angb- ,^"^^l
limuf .i!o.% per f,..,t ' ;^:1;'^:': ^ ^' ''' ' ' WebT-.f "" '""'
up.V2'2-x2r.vs*.>ngii 'I-''-"- '5*-Ki.' u,:.;i.,2 2rx.r-,...*..ngi.
I., ll, 2 2'X3".,#.-ingle
Ipil.
1. ll. .'.'■■, a angle
1. ll. 2 2J"X2|" v.(#.ingle
gle
IS'Sr^I, ..r |l!uilllK-am, -,2'aper b.ni llnill I... im, s.S# per I..1.1
ll,„lt.|ie.,m,47l*lie. l-H |^^.^,^^ j.,,,^^, • ^,^.,,, j-, ,,;.
)^'''', '"":',' I- » , il'p ll,2 2-X2) ,.S#.'ngle Up.d.,2 2i-X2l",...#.mgl,
lp.ll.22X2i I5».i"gle ,'„ ...,,,.^,, , „ .,,■■, .r = ,a„.,.l,.
I., ll, 2 2'x ;• 4# angle
, I.. II, ■ .•''X3I' ;-,# angle I..
,. |» .mgli
"5'St>*I."f : limit b. ll", '■-• per (....I llnill l..-.im. («# per font
llmll-liea ).»« pec f....t ^^.^^^ _, Web. I'Xj.r
T^''^""":-' ,. , , l'p. ll. ■ • na.mgle l'p. 11,2 2'x, i"-v.i#a..r.U
i5"so#I,nr ■ l;„ilt br.im, 5s# I'T f""«
biillt-beani, 5ol» pel |....t .,'l'
Web, J'X2l.''
;li-' t'pll. 2 2"x :\" PS* angle
Well, 1"X2S'
l'p. ll.
t'.niltbcam, fn \1t per fnot
Well, yx ,0'
llmil-iie.im. ;;# per |....t Itnilt-I.i .tm, 02# per b.(.t
Web, i"X2.)" Web, J''X3o''
l'p. tl, 2 2" X 2i' 4.sa ai.fl l'p. ll, 2 2I" X 3" 5.5* angle
I., ll, 2 2"X3}' 5.3# angle 1,. ll, 2 23"X2}"6.5#angle
lliiill-beani, yi# |ier (... 1 liniltbeain, 63^* per font
Web, I'Xjo" Web, J'X 30"
l'p. ll, 2 2J'x 24'4.i)#ange| l.'|..tl., 2 2"X3'(*angle
I., ll ■ .. - .-
Ilnilt'beani, C.7J* |.er loot
Well, }'X3o"
Up. ll,2 3"X3"7.2«angle
I.. 11., J3"X3i"7.7#aiigle
llnilt-lieain, 70* per foot I
Web, J' X 30" ;
Up. ll, 2 3" X 34" 7.7* angle I
2 2"X3J" 5.3a angle 1.. tl, 2 24" x 3° (.7* angle ; I,, ll, 2 }"'<:," .S.4# angl
liiiilt beam. f:2* p. I 1 llnill-beam, (.74# per font Miiilt-beani, 71.4* I'er l....t j
Web, i " X 30" Well, \" X 30" , Web, ,55" x 35" ;
I'p.ll, 2 2\"x;i' s-S#i"i-l. Up.ll, 2 }'X]' 7.2# angle j Up.ll.,2 2f X 2}" (i.5#angle
I,. II, 2 2i'x .!i'0.5# .oi^le : I., tl, 2 j'x jj' 7.7* angle '•■ "■. = 3'x j" ".-'* anglf
lluilt-beani, 6il# per f.- 1 ' liuiltbeani, 70# pet foot ' llnill-Iicam, 7S# per font I
Web, J- X ,o' , Well, I" X 30" Web, ,>/ X 3(1'
' Up. ll, 2 3"X34' 77* angle I'p-ll. 2 2"X3|" 1,. i* .uigi.-
I, ll, 2 X'x f ,s.4# .ingle ; I., ll, 2 i'x X' 7.2* .mgle
Up. ll, 2 2"x \' i*aiiL!
I., ll, 2 24' X 3" (..7*,m;
llnill b. on, (.5* per 1.."!
Web, l"x 30"
Up. ll, 2 2"X3l '(..4a m.
I ■ ll, 23" X 3" 7.2#.nigl.
llnill l.i.im, (<.l* p. I !■■
Web, i'Xja'
Up. 11,2 24''X3'l..7a,i:
I- 11-. -'j'X,3r7-7«-i".--
. I
linilt-beani. 75* per font j llnilt-be.in;, Si« per foot |
Well, ,\"X34'' I Web, ,';."X3.S' ;
Up. H.,2 2fX2J"(..s* angle' Up. ll, 2 2'x 3!' i..4a angle
I,, ll, 2 i"x f 7.2# angle j 1.. ll, 2 fxf 7.2» angle
I '
llniltbcani, 7(.la pir l....! Ilnilt-beain, .S2l# pe' t,...t
' Web, |>,,,"X3s Web. ,';.,"x3S"
I Up.ll.,2 2i'X2(-r..j#.ingle Up. ll. 2 24''X3'(..7#.inglei
I,, fl., 2 3"X3' 7.2#angle I., ll. 2 3'x 34' 7.7* angle
Unilt Iieam, fiO# per (•■
Web, J"X3o"
l.S# angle Up.ll, 2 24" X i" s.5# angle Up. ll. 2 3-X3"7.2#ai
, 1., Il.j 2->. i|' ;#angle l." ll. 2 2- x j)' f, .,« angle j l. fl.. 2 3" x 3" ,S..,# .m:;i.
I, ll, 22 X3 4» angle ' ^; __j
Roadway. 14' Clear. Rna.lway, 1 Clc:ir. R.ia.lway, i8' Clear. Roa.lway, Jo' Cle.o
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300 1
IMAGE EVALUATION
TEST TARGET (MT-3)
W.
//
{./
^.A^
"%
1.0
I.I
■ 50
M
1.8
1.25
1.4
1.6
-^— 6" —
►
Photographic
Sciences
Corporation
23 WEST MAIN STREET
WEBSTER, N.Y. 14580
(716) 872-4503
.5^"^%*
f/.
i/.
^
J
a
SAiw;
ItivorkDni Upper horizontal line shows diameter of pin.
•'ticaB (
-g : '-
3i'
si'
5i'
sS"
51"
5r
6"
1 J0.i3 0_
11.40 I
J 2.66 3
.13-92 '4
16.41; 6
17-723
^20.250
21.52;!
i-4-05 "4
1^5-3> -S
•6.5SJ6
,..7.848
' .55-44 5
!,i7.:07?;
' |lo-5o^.
' il3-03 5'
t5-5f^'i5,_.
,8.of) 8
|i0.6jp
.3
iV
¥
r
-
--
26.20
28.22
30-23
28.88
29-53
31.64
30.94
32-34
32-25
33-00
33-75
34-50
36.66
_35::25
37-45
36.00
J8^5_
40.50
42.75
I"
34-27
36.28
_35-?'_
37-13 i
35-86
i 'vV
1 'V
1 ir
! ''rt""'
37-97
38.81
39.66
38-30
39- '9
40.08
40.97
43-'3
■ 45-28
47-44
41.86
40.31
_ 42j33_
44-.34
46.36
41.25
43-3 >
45-38
47-44
42.19
44.06
4(1.27
45.00
47-25
_i-»:3?_
4O.41
48.47
49-50
48.52
49-59
50.67
5';75„
58.50
63.00 '
■"67V50"
48.38
49.50
50.63
5'-7S
52.88
52.41
56.44
60.47
64.50
^•8-53
72.56
53-63
57-75
61 .88
- (j6.oo
70-13
74-25
54.84
59.06
63.28
. <^7-5o_
■71.72
75-94
56.06
"6038""
57.28
61.69
6<j.o9
64 .rK)
69.00
73-3'
77.62
_7ojo_
74.91
79-3'
83-72
; 88.13
92-53
96.94
72.00
76.50
8 1.00
""85.50
1 2'
i 2^'
i 2V'
2i"
76.59
80.63
84.66
88:69
92.72
96.75
1 100.78
104.S1
108.84
78.38
82.50
~ 86.63'
"90-75
_94:88_
<«.oo
r io7.:5
111.38
115.50
'23-75
So. 16
'"8I.38
88.59
92.81
97-03
105.47
109.69
Ti3.9i
iiS.n
122.34
J 26.^56
81.94
86. 2 5
90.56
_94:87-
99.19
J.°3.- S0__
107.81
1 12.12
1 16.44
■:o.7"5;"
125.06
j 90.00
r 94-50
2*"
i 2r"
i 2r
1 99-^-^
101.34
J05-73.
j 1.0.16
114.56
118.97
123-38
127.78
'_i93:50_
10^00
11 -'.50
11 -.00
121.50
liOOO
1130.50
i Li5 0o_
J39:5o_
1 144.00
21"
-i —
1 -^
- ♦—
1 1-
4 ;-
' i'
3V
112.88
ii6.yi
129-37
132.19
. .'3i-59.
—
^'
>^*,!
V I
TABLE FOR FINDING THE NECESSAKY
TABLE XXV
WIDTH OF BE
Having
given the total pressure on
said s
urface,
and the diameter of
the pi
n. This table is calculated for a working comipressive stress of 6 t
Vertical 1 les of inches show width
CT.A.SS A.
■i"
•r'
li"
H"
2"
2i"
zi"
2|"
2i"
1
2i"
2f
2F
f
3*"
3r
3*" i"
31'
3r
34"
4- 50
4.88
5-25
5-63
6.00
6.38
6.75
7-59
8.44
9.28
7-13
7.50
7.88
8.25
8.63
9.00
9-38
9-75
10.13 ).5o
10.88
11.25
11.63
5.06
S.48
5.91
6.33
6.75
7-17
8.02
'8.91 '
S.44
9-37
8.86
"9.84
10.83
9.28
9.71
10.12
10.55
10.97
n.40
:.8i
12.23
12.66
13.08
i"
H"
S'63
6.oq
" 6.57^
7-03
7-5°
7-97
8.77
10.31
10.78
11.25
11.72
12.19
12.66
13-92'
;-i3
1359
14.06
^•53
6.19 i 6.70
7.22
7-73
8.25
9.80
10.31
11-34
11.86
12.38
12.89
13-41
:44_
14.95
15.47
1 5^98
6.75 1 7.31
7.88
8.44
9.00
9-56
10.13
10.69
11.25
II. 81
12.38
12.94
13.50
14.06
14.63
15-19 -75
10.31
16.88
17.44
"7-31 i 7^92"
7.88 1 8.53
S.AA i O.U i
8-53
9.14
9-75
10.36
10.97
11.81
11.58
12.1)1
12.80
13-41
14.02
14.63
15-23
15.84
16.45 .06
17.67
18.28
18.89
9.19
9.84
10.50
II. 16
~ 11-95
12.47
I3.I..
13-78
14.44
15.09
15.75
16.41
17.06
17.72 1.38
19.03
19.69
20.34
Q.84
lO-SS
11.25
12.00
12.66
- '3-36
14.25
14.06
14-77
15-47
16.17
16.88
17-58
18.28
18.98 1.69
20.39
21.09
21.80
l" 1 Q.OO
9.75 ' lO.W
11.25
12.75
13-50
14.99
15-75
16.50
17-25
18.00
18.75
19-50
20.25
.00
21.75
22.50
23.25
iX" ! 9.56
i"o.:i6 '■■
" II. 16'
"•95
..■.-•7S__
13-50
13-55
14-34
15.14
15-93
16.73
17-53
18.33
19.13
19.92
20.72
21.52
•31
23.11
23.91
24.70
"ij" '' 10.13 '°-'5' '
1T.81 "
12.66
^ 13-36 "
14-34
15.19
16.03
16.03
16.87
17.72
18.56
19-41
20.25
21.09
21.94
22.78 ;
:63.
•94
24.47
25.3'
26.16
27.61
TX"" ■ ' io.6q~
11.58 j 12.47
1425
15-14
16.92
17.81
17.80
18.70 .
19-57
20.48
21.38
22.27
23.16
24.05
J'S-»3_
26.72
1 11.25
12.19 1 '313
14.06
15.00
15-94
16.88
18.74
19.69
20.63
21.56
22.50
23.44
24.38
25-31
1.25
•56
27.19
28.13
29.06
1 u,S
12.S0 1 n.78
1477
15-75
16.73
17.72
18.70
19.67
20.67
21.66
22.64
23.63
24.61
25-59
26.58
28.55
29.53
__30:52 .
if" 12.38
I'i.'' '
'341
14.44
15-47
16.50
17-53
18.56
19.59
20.61
21.66
22.69
23.72
23.72
24.80
24.75
25.88
25.78
26.95
26.81
28.03
27.84 ;
.88
29.91
.^J°i94_
_3h97_
14.02
15.09
16.17
17-35
18.00
._''1:.3J3_
19-13
19.41
20.48
21-55
22.64
29.11 J
.19
31.27
32-34
33^42
16.88
20.25
21.38
22.48
23-63
24-75
25.88
27.00
28.13
29-25
J°i38 -^
•55L
32-63
3i75
34.88
20.52
21.94
33.16
24.36
25.59
26.81
28.03
29.25
30-47
3'-69_
32-91 ,
•13 _
■75
35^34
36^56
37^78
40.69
23-63
24.94
26.23
27-56
28.88
30.19
31-50
32.81
34-13
35-44 ,
37-97 ,
38.06
_ 39-38 _
I J"
-- -
26.72
28.10
29-53
30-94
32-34
33-75
35.16
_j6i56__
40.78
42.19
43^59
"" i
i
1
29.97
31-50
33-00
34-50
36.00
37-50
_J9-84_
42.19
. J9-oo^
40.50 ».0" 1
43^50
45.00
46.51
35-06
36.65
„38/2S„
41.44
^43-03 J
1.03
46.22
'48".g4
47.81
50-63
49.42
i
38.81
40.50
43.88
__15:56 ¥21.^
52^32
21"
-i"
44-53
46.32
48.76
4S.09 -
.50
51.66
J4^3«„
53.44
_-5'^-25_
55^23
1
— - - --
. J?L^3 J
__5**::14_
2|"
i _,_._.
-
—
■I.J
57.09
59.06
61.88
61.04
6395
2j"
2*"
-•
J
i._
3»
"3T'
3i"
3i"
"3l"
3i"
31"
4"
i — ' —
—
!
; 1
■ i
1
11 ;
1
1
1
1
_„
-^
— .
TABLE XXVI.
^ WIDTH OF BEARING-SURFACE AT EACH END OF PINS,
g coniipressive stress of 6 tons per a" on the projection of the semi-intrados upon a diametral
[ les of inches show widths of bearings.
CTASS A.
plane.
Upper horizontal
line shows diameter
of pin.
i"
31'
31'
34"
4"
4F
4k'
41'
4i'
4f'
4}'
4F
5'
54'
Si'
51'
5i'
5l"
5J"
54"
6"
).50
10.88
11.25
11.63
12.00
12.38
12.75
13-13
13-50
13.88
¥
.81
12.23
12.66
13.08
13-50
13.92
14-34
'477
15-19
15.61
16.03
"i7;8r
i"
•'3
I3S9
14.06
M-53
15.00
15-47
15.94
16.41
16.88
17-34
18.28
20.63
•44
14-95
15-47
15.98
^6.50
17.02
17-53
18.05
18.56
19.08
19-59
20.11
W
75
.06"
10.31
16.88
17.44
18.00
18.56
19-13
19.69
20.25
20.80
21.38
21.94
22.50
23.06
23-63
i"
17.67
18.28
18.89
19.50
20.11
20.72
21-33
21.94
22.54
23.16
23.76
24.38
24.98
25-59
26.20
1
4"
•38
19.03
19.69
20.34
21.00
21.66
22.31
22.97
23-63
24.27
24.94
25-59
26.25
26.91
27-56
28.22
28.88
29-53
1.69
20.39
21.09
21.80
22.50
23.20
23-91
24.61
25-31
26.01
26.72
27-42
28.13
28.83
29-53
30-23
.30.94
31.64
32-34
l"
.00
21.75
22.50
23-25
24.00
2475
25.50
26.25
27.00
2774
28.50 29.25
30.00
3075
31-50
32.25
33.00
3375
34-50
35-25
36.00
■31
23.11
23-91
24.70
25.50
26.30
27.09
27.89
28.69
29.47
30.28
31.08
31.88
:, ■■'^'■
33-47
34-27
35-0'
35-86
36.66
37-45
_3?f5_
40.50
IT^"
■94
24.47
25.83
25-3'
26.16
27.00
27.84
28.69
29-53
30.38
31.21
32.06
32.90
33-75
34-59
35-44
36.28
37-13
37-97
38.81
39-66
26.72
27.61
28.50
29-39
30-28
3'-'7
32.06
32-94
33-84
3473
35-63
36-52
37-41
38-30
39-'9
40.08
40.97
41.86
4275
'A"
.25
•S6
.88^
27.19
28.13
20.06
30.00
30.94
31.88
32-81 i 3375
34.68
35-63
36.56
37-50
38-44
39-38
40.31
41-25
42.19
43-13
44.06
45.00
I}"
'A"
•r
lA"
•i"
ir
'f
28.55
29-53
30.52
3'-50
32-48
33-47
34-45
35-44
36.41
37-4'
38-39
3938
40.36
41-34
42.33
43-31
44-30
45-28
46.27
47.25
29.91
30-94
3 '-97
33-00
34-03
35-06
36-09
37- '3
38-15
39- '9
40.22
41.25
42.28
43-31
44.34
45-38
46.41
47-44
48-47
49.50
.10
31-27
32-34
33-42
34-50
36.00
35-58
36.66
3773
38.81
39-88
40.97
42.04
43- '3
44.20
45-28
46.36
47-44
48.52
49-59
50.67
5175
.50
32.63
3375
36.56
34-88
37-t3
38-25
39-38
40.50
41.62
42-75
43-87
45.00
46.13
47-25
48.38
49-50
50-63
5175
52.88
54.00
•'3.
75
:38~
35-34
38.06
3778
39.00
40.22
41.44
42.66
43.88
45-08
46.31
47-53
51..8
48.75
49-97
51.19
52.41
53-63
54-84
56.06
57-28
58.50
39-38
40.69
42.00
43-31
44-63
45-94
47.25
48.55
49.88
52.50
53-8'
55-13
56.44
5775
59.06
60.38
61.69
63.00
40.78
42.19
43-59
45.00
46.41
47-Si
49.22
50.63
52.02
53-44
54-84
5"6-25
57.66
59.06
60.47
61.88
63-28
_ 64.69
69.00
66.09
67.50
ii"
an
43-50
45.00
46.51
48.00
49-50
51.00
52.50
54.00
55-49
57.00
58.49
60.00
61.50
63.00
64.50
66.00
67.50
70.50
72.00
2"
1 2i"
i 2i"
•63
46.22
47.81
49-42
51.00
52.59
54-19
55-78
57-38
58.96
60.56
62.15
63-75
65-34
66.94
68.53
70.13
71.72
73-31
74.91
79-31
76.50
81.00
•25
4S.94
50-63
52-32
54.00
55-69
57-38
59.06 ] 60.75
62.43
64.13
65.81
67.50
69.19
70.88
72.56
74.25
75-94
77-62
.88
51.66
53-44
55-23
57.00
58.78
60.56
62.34 1 64.13
65.90
67.69 : 6946
7'-25
73.03
74-81
76.59
78.38
80.16
81.94
83.72
85.50
2J"
2t"
.i;o
54-3«
56-25
58.14
60.00
61.86
6375
65-63 , 67.50
69-37
72-83
71.25
73-»«
75-00
76.S8
78-75
80.63
82. 50
84-38
86.2 5
88.. 3
90.00
■',i
57.09
59.06
61.04
63:95^
63.00
64.97
66.94
68.91 I 70.88
74-81
76.77
78-75
80.72
82.69
84.66
86.63
90-75
83.59
90.56
92.53
94-50
6 1. 88
66.00
68.06
70- > 3
72.19 ! 74.25
76.30
78.38-
80.13
82.50
84.56
86.63
88.69
92.81
94.87
96.94
99;«00'
•■4 »._
69.00
71.16
73-i'
75-47
77-63
79.77
81.94
84.08
86.25
88.41
90.56
92.72
94.88
97-03
99.19
iot.34
-i°57/r
lyf<Xl6
fi 14.56
118.97
/ioj-jo
lOiS.oo
24"
J
-— -
74-25
76.50
78-75
8r.oo
83-24
86.71
85.50
89.06
87.74
90.00
92.25
94-50
96.75
99.00
101.25
105.47
103.50
107.81
112.12
82.03
84.38
91.40
95-05
9375
97-50
96.09
98.44 ; 100.78
'03.13
1 IIJ.W
3i"
90.18
92.63
99-94
103.78
102.38 1 104.S1
107.25
109.69
i 11 --00 ' r,i"
■
98.71
101.25
106.31 108.84
111.38
115.50"
119.63
113.91
I 18. 1-!,
I 22.^4
II 6^44
i '2'-5>-' 1: Xi"
107.64
ito.25 i 112.88
1 16.91
■'_-0.7i_
125.06
123-38
' 120
4'
127-78
i 130.50
j '3500
J'
3*"
3i"
1 4'
12375
I26A6
129.37
132.19
1
1
133-69
136.59
139-50
i
1
i
i
1
1
144.00
♦
\
■
31"
12.19
"1371
XVII.
' BEARING-SURF
•ompressivc stress of 7.} Don a diametral plane. Upper
lines of inches show vvidl
AND C.
I
f I
0'
TABLE XXV
TABLE FOR FINDING THE NECESSARY WIDTH OF BE
Hiving given the total pressure on said area, and the diameter of the pin. This table is calculated for a working compre:
horizontal line shows diameter of pin. Vertical lines c
CLASSES B AND
TABLE XXVII.
' WIDTH OF BEARING-SURFACE AT EACH END OF PINS,
ted for a workinj; compressive .stress of 7.} tons per n" on the projection of the semi-intrados upon a diametral plane.
r of pin. Vertical lines of inches show widths of bearings.
CLASSES B AND C.
Upper
-i"
3" '
-1
3i"
3i" 1
3r
12.66
14-24
3i"
.1*
3:1"
7,1"
"4-53
16.35
18.16
4"
4J"
4i"
41"
4r
4-3"
A\"
4i"
5"
A"
¥
H"
4"
W
V
10.78
1
11.25
12.66
11.72
13.18 :
r2.i9
13-7'
13-13
>3-S9
14.06
15.82
15.00
_'S:47_
17.40
J5:?4 .
17-93
16.41
16.88
18.94
21.09
J7-34
19-S'
21.68
„-3:^5_
26.02
^8.18
17.81
20.04
18.28
18.7s
21.09
23-44
25-78
28.13
30-47
32-81
12.13
_ ■4-77_
16.41
~i8^r
19.69
21-33
15.29
16.99
18.69
„-°-39__
22.09
16.88
18.46
20.57
13.48
14.06
14-65 ;
'5-23
16.76
1S.28'
19.S0
i5.82_
17.40
18.98
20.57
17-58
18.75
20.63
>9-34
19.92
20.51
22.27
22.85
14.S2
15-47
16.88
16.11 1
19-34
.9.98
2 1. So
23.61
21.37
21.91
23-9'
25.90
27.89
29.88
31.86
33-87
22.56
24.61
26.66
28.7.
23.20
' 25-3^1 '
27-42
29-53
24-49
25.14
27-42
16.17
17-58 .
21.09
22.85
24.61
26.37
28.13
22.50
24.38
23.20
25-14
27.07
26.72
17-52
18.28
"19.69
19.04 1
21.97
28.9s
29.71
18.87
21-33
22.15
22.97
23-79
25-49
27.19
25-43
26.25
30-35
3i-'7
31-99
34.28
36-56
38-85^
20.21
21.09
22.S5
24.38
25.(JO
27.42
23-73 .
25-3'
26.89
24.6 r
26.25
27.89
27-25
29.06
"30.88~
28.13
30^00
3f.88
33-75
29.00
>-94~"
32.87
30.76
32-81
.3' -64^
33-75
32-52
34-69
36.S6 '
39.02
41-19
33-40
35-63
37-85
3S-'6
I"
21.56
22.50_
23-9"
25-3'
"26.72
28.. 3
29-53
23-44
24.90
26.37
27-83^
29.30
30.76
_32-23
33-69
_35d'>
38.09
41.02
43-95
46.S8
49.80
37-50
39-84
42.19
22.91
28.89
29.88
34-86
35.86
•A"
li"
24.26
28.48
29-53
3'-i7
«32.8i
30-59
_32.29
33-98
31.64
32.70
34.80
35-86
36.91
37-97
40.08
41-13
25.61
28.95
30-47^
3' -99
3.3-52
_30.o6_
31.64
33-22
34-80
. 3^-39 .
37-97
33-40
.35-'6_
36.91
_ 34-5J__
36-33
38.14
35-63
36-74
37-85
39-84
41.84
38-96
40.0S
42.19
42.30
44-53 "
43-42
44-53
lA"
li"
lf^T"
li"
26.95
37-50
39-38
_j8-_f'7_
40.61
41.02
43-07
45.12
43-36
45-53
47.70
49.86
52.03
45-70
46.88
49.22
28.30
34-45
35.68
-44-30^
46.41
48.52
46.76
47-99
29.65
30-94 ,
32-34
33-75
36.56
_39^38_
42.19
45.00
47.8.
_36-oj)_
37-73
37-38
39.08
38.67
39-96
41.25
_J3'L3_
45.00
48.75
52-50
5'-25
42-54
44-47
43-83
48.98
_ S?-_27__
52-56
54.84
51-56
31.00
35-04
36- S6
40.43
42.19
.._4i78_
43-59
47-23
50.86
45-82
47-17
51.21
53-9I
56.25
•A"
•i"
,r
If"
•r
2"
"2i" '
1--.14
39-38
40.78
50.27
54-14
58.01
47-81
51.80
49-22
53-32
50-63
54-84
53-44
')5-04
39.61
42.66
4i-'3
42.66
44.18
45-70
56-37
57.S9
59-41
60.94
37-73
44-30
45-94
47-58
49.22
55-78
57-42
61.52
59.06
60.70
62.34
63-98
65-63
40-43
45-70
48-75
5' -80
54-84
47.46
50-63
49-22
52.50
50.98
52-73
54-49
59-77
63.28
65.04
66.80
68.56
70-31
79-69
43- '3
54-38
56-25
..J8:i2_
61.76
60.00
"^63.75
67-50
71.25
75.00
78.75
61.S8
65-74'
69.61
63-75
65.63
67-50
69-38
71-25
73-'3
53-79
56-95
^55-78
59:06
57-77
59-77
67-73
71.72
75.70
69-73
71.72
73-71
78.05
75-70
77-70
61.17
63.28
65-39
69.02
73-83
75-94
So. 16
82.27
84-38
2\"
2r
6o.i2_
62.34
__-^i-S7__
67-97
66.80
73-4«
77-.?4
77-93
80.16
82.38
"86772
84.61
86.84
89.06
70.31
72.66
79.69
83-67
82.03
86. 1 3
_„90^3„
94-34
84-38
88.59
92.81
S9.06
93-52
91.41
95-98
93-75
98.44
2i"
2|"
2j"
73-83
76.29
81.21
91-05
95-39
,
82.50
85.08
8S.95
87.66
91.64
97-97
100.56
103-13
_
97-03
99-73
104.06
108.40
102.42
105.12
107.81
^-. - —
98-44
101.25
106.8S
109.69
112.50
117.19
3"
3i"
3i"
3i"
— —
105.47
i"-.\3
114.26
118.83
115.78
121.86
123.40
126.56
I
■li
,-•"[.(•.
'5"[ '
F
Thick- 1
ness of j
Web in
Inches.
0.250
_i'l?7S
0.300 1
_o.3-'5
1 0.350
' 0.375
1 0.400
L?4-'5 !
|_o.450
1 0.475
0.500
; 0.525 i
0.550
! 0.575
0.600
i 0.625
0.650
L2:^7'5
' 0.700
i "0.725
'0.750
0.775
i_o.8oo
p
w
A
F
W
A
oo
—
60,
,^54
106
1
«*J
f«,
30.00
3072
3 '-72
3--7-'
3.5-72
'^2.7f~
2-73
2-75
2.7S
2.80
■"2.S3"
2.«5
2.S.S
2.93
2.95
^^-'^
3-00
303
3-05
3.08
__3-'o
.l-'5
3-20
354
9.00
9.22
y-52
9.S2 '
10.12
ro.42
— -
I06
\
40.00
r 4 1.25"
1 42.50
1 43-75
4500
: 46.25
! 47.50
._4«75.
5000
~S'-2S~
52-50
53-75
55-00
j 56-25
i 57-50
L..,5f<-75
60.00
3-53
3-5f'
,^58
3.61
3X)C
3.68
3-7'
3-73
(XD
35
12.00
^ 12.3s
-2.75
'3-13
'3-5°
13.88
14.63
15.00
"15.38^
10
3472
.5f>-72
37-72
3«:72
3<>72
40.72
14--72
43-72
44.72
85
6o'~
35
10
10.72
11.02
II.J2 .
11:62
I 1 .92
12.22
»2.S2
12.82
13-12
3-76
3.78
3-81
•— ' —
'575„
r6.i3
1.3-42
16.50
3-83
0.825
_4.S72
_ 46.72
47-72
4S.72
49.72
13-72
14.02
14.32
14.92
16.88
3.86
3.88
3.01
3-').i
0.850
_o^75
0.900
^0.925
" 0950
-■—
17-25
<7-<>3
18.00
i\
k I
»
~rr
Thick- I
Web in I
Inches.
4" [•-■'•
W
605
1.S2
0.0:5
0.67
I' 3'
1.92
6.71
2.03
7.00
2.10
os-^
■1" £■/■■■
5"[-'-
F
ly
A
2.13
2-23
2-33
F
'■75„
'•77
1.80
1.83 "
1.8s
1.87
1.89
IF
7-02
744
7.8s
8.27
A
2.1 1
- ■ F--
1.62
7.08
.-•4i_!
7-74
1.69
2.24
7-36I
2.49
1.65
1.67 1
1 72
I-74
1.70
8.0S
8.4 1
2.43
2-53
-2.63"
••77
1
8.74
^
1
9.00
^•1°^.
— — _-
i
1
1
- -
—
1
— ^
1
—
j
i
1
1
i
i
— —
1
1
1
—
1
i
1
1
1
i
! i
_
0.050
•f -
5"C ■'
1
5" [ ■ ^'•■
i^
," [ , ./.
(," [ . //.
/•
IF
j1
W
A
F
1.94
..96
A
F
IV
10.46
1096
11.4(5
II 96
12.46
1296
""1346"
A
3 '4
329
3-44
.rs9
374
3-89
4.04
'•"S
7-02.
744
7-8S
3.11
1.69
9.08
273
2.S5
2..;8
3.10
3-23
8. 58 2.57
1.81
1.84
1.86
—
1 77"
1.80
2.24
'2.36"
2.49
172
1.74
«.77
950
9.91
'0-33
•0-7J
11.17
11.58
9.0S
9 5°
2.72
^.2.8S_
1.S3
8.27,
2.01
2.04
1.85
1
1,87
1.89
.
3-3S
348
3.60
_ 2J36 _
. /2°9
2.11
j
.
/ !
1 -^
!
12.00
12.42
12.83
'3.2 5
.3.68
14.00
1
13.96
14.46
14.96
4.19
tt-34_
449
479
-
373
3.85
2.14
2.16
3.9«
2.19
2.21
_2l2.3_
15.46
'4.20
— .-.
1
1 _
1
,
—
,
1
L .. .^
-
—
— .
—
— .
—
—
- ,
1
1
.
i
.
i
1
- —
--- '. ..--
1!
1
M-auM-
. FINDING
the \vcij;ht per
TABLE XXVIII.
THE DIMENSIONS OF UNION
oot in pounds, A the area of section in square i
IRON MILLS' CHANNEL BARS
nches, and F the width of flange in inches.
,
7" [./.'.
S"[.W.
S" [ . />'.
y" [ • ^-i-
9" [ • /"-
10" [ . A.
10" [ . /.'.
' \ .1 \ /■•
ir
^i
A
IV
A
/'•
t
A
/
;v A
F
ly
A
F
IV
A
/
I - .-
r-
2.30
2.32
—
12.79
J.84_l 2.02 ]_ _ __
4.04 204 .j 16.00
4.80
'4.98
" S..8 -
5-40
2.43
2.45
2.52
0.)
„4^3
2.30
13.46
"7-50
5-25
2.
68 1 4.40
2-33
i4-«3
4.24
2.10
16.59
14-50 1 4-35
2.50
5-58
16.00
4.80
18.33
S-So
2.
j6
01
4.58
14.79
1546
__4:44_
4.64
'7-25
2-35
i9-Jo
_.__S-.8J_
6.03
2.48
2.50
19.17
5-75
■^
4-75 i 2.3S
2. 1 2
17.92
5-38
237
20.10
20.00
6.00
2.
-l-i).5
2.40
-
18.59
•9-25
s-ss
2.40
2.42 1
1
20.85
6.26
2-53
2-55
2.58
2.60
2.63
2.65
2.68
20.83
6.25
2
5. 10
2.43
5 78
21.60
6.48
21.67
6.i;o
2.
'59.
'7
3i_
)2
5.28
2-45
19.92
S-98
2-45
2.47
2.50
_22-35_,
23:10
23.85
24.60
_^S-3S_
26.10
26.85
671
6-93
7.16
22.50
6-75
2.
S-(5
2.48
20.89
6. 1 8
23.33
7.00
2.(
563
5.80
^i5° .
2-53
.^"55
21.25
21.92
~22.^
6.38
24.17
7.25
2.(
6.58
2.52
... ..„
7-38
25-00
7-50
2.(
6.78 1 2.55 I
7.61
25-83
7-75
2.(
23.26
6.98
■^■57
2.60
2:62 "
7-83
8.06
2.70
2-73
26.67
8.00
1 •
23.92
7.18
...
27-50
8.25
2-;
i
2459
7.38
27.60
8. 28
2-75
28.33
8-50
1 ■
! 25.25
7-58
2.65
28.35
8.51
8.73
8.g6
2.78
2.80
29.17
30.00
8.75
2.-
1 25'92
778
2.67
29.10
29.85
9.00
2.{
1 26.59
7.98
8.18
2.70
2-83
! 27.25
i 27.93
2.72
i
1
8.38
-^_._-jZ5___
1
~-
1
_
(
1
1
1
1 "
1
—
1
1
1
,
s.
A
10' [ . /.'.
10" [ . C.
12" I. A.
12" [./,'.
.2"[.C.
•5"L ''
Thick-
ness of
Web in
Inches.
F
W A
F
W
A
F
W
A
F
W
A
F
w
A
F
vv
1
A
/'■
0.250
20.00
20.67
Coo
1 0.275
1 0.300
1 0.325
1 0.31:0
17-50
S-25
2-43
2.56
2.52
'8-33
5-50
2.46
6.20
2.58
20.00
6.00
3-01
22.54
6.76
3-01
19.17
5-75
2.48
21.50
6.45
2.61
i 23.54
706
3-04
i
20.00
6.00
2-5'
22.33
6.70
2.63
1 24.54
736
3.06
-^
1 0.37s
i 0.400
20.83
6.25
_ 2 53
2.56
^-3-i7__
6-95
2.66
! _..=5-54
__26.54_
27-54
7.66
7.(u)
8.2'^
_309
3"
i
21.67
6.i;o
24.00
7.20
2.68
30.00
3072
0425
22,50
6.75
2.58
24.83
7-45
2.71
3-'4
9.00
9.22
2-7'
0.450
i 0.475
1 0.500
|..°_-S25
1 0.550
0-575
0.600
0.625
n-ii
7.00
2.6,
1 25.67
7.70
2-73
2.76
2.73
28.54
8.50
3.16
2-73
1
■ ■
24.17
7.25
2.63
1 26.50
7-95
29-54
8.86
319
3'-72
9.52
2-75
1
25.00
7-50
2.66
! 27.33
8.20
_32-72
33-72
9.82
2.78
40.00
12.00
3-53
2S-«3
7-75
2.68
28. 1 7
: 29.00
8.45
2.8 1
i
1
10.12
2.80
2-83
41.25
12.38
3-56
26.67
S.oo
2.71
8.70
2.S3
2.86
34-72
10.42
42.50
'2-75
'3-'3
3-58
3-6.
3-63
27.50
8.25
2-73
L29-83_
i 30-67
8-95
9.20
35 72
10.72
2.85
43-75
28-.33
8.50
2.76
2.88
2 91
.36-72
M.02
2.88
45.00
'3-50
t
-.-?-i7_,
30.00
8.75
2.78
31-50
9-45
37-72
38-72
11.32.
2.90
46-25
13.8S
3.66
0.650
0.675
0.700
!?•_"- 5
0.750
0775
o.Soo
9.00
2.81
l,--2,l
9.70
2.93
i 1
11.62
2-93
47.50
'4-25
14.63
3.68
11^
__2,2,-'^l
9-95
2.96
1
i
39-72
40.72
41.72
42.72
ir.92
2-95
1 48.75
34.00
10.20
2.98
.
12.22
2.98
5000
15.00
'5-38
3-73
_34;83^.
10.45
_3:0L_
12.52
3-00
3-03
_5i:2S _
52-50
3-76
3-78
12.82
'5-75
43-7^
13.12
3-05
3.10
53-75
16.13
3-81
1
44.72
13.42
55-00
56-25
57-50
16.50
3-83
0.825
0.850
0-875
0.900
0.925
0950
4572
'3-72
16.88
3.86
1
I
46.72
14-02 I 3.13
'7-25
3.88
47-72 1
'4-32 1 3- '5
14.62 1 3.18
58-75
'7-63
.3-91.
3-93
i
48-72 1
49-72 1
60.00
18.00
14.92 j
3.20 j
!
1
1
'^4
^^tim-
Ft
I'N
—
.1
-t
-5
_■!
5
S
5
y
■/
— t
■' i
\ !
_)
-_<
— -i
t
— \
(
(
l<
I(
t
1
I(
IC
2C
2C
-'
J
m
?<
Width,
in
inches.
Weight per
in Dound
foot,
C
End
allow-
ance
for one
; bar.
Rivet-
Heads.
1
1 '
__
i"
h"
i!"
— _
4'
5"
6"
6r
7'
7r
8"
8]" ~
</
9i"
lo"
ioi"
11"
up"
12" " " 1
TKR, IN
INCHES.
OF TWO
HEADS, IN
I'Ol'NDS.
™~
i5
'•2S
0.14s
0-153
0.161
i
o.oS
__.
1.36
1.46
' ••57
1 Tri
0.12
0.16
0.20
0--5
0.32
0.40
0.47
— .
1-95
—.._
—
0.180
\h
I
""
^
1.67
1 1-78
i 1. 88
2.aS
2.21
2-34
0.1 88
.
2i
2i
23
2i
2J
0.197
~
2.97
3- '3 ;
3-29
3-44
0.215
0.223
2.47
2.60
H
— ♦
o.2;fi
0.250 I
0.258 ;
266
0.274 !
0.2S2 (
_t
12.1'' i
.3" i
•3i" ;
' t'
14^^
ts' :
■ sM
! I()"
I
o-.^5
-5
2-73
2.86
i ^?
1
.3
5
300
"3-26
3.f«
3
3i
3l
3?
3i
35
3^
33
1
4i
.1-75 ■
3-9« ;
* 1
i
1
1
3y)
4.06 1
0.291 ,
-4 :
1
4.22 1
4'"J
. - 1
4.S5 j
5.00
5.1(1
299
iSi"
"20' 1
20^" !
21"
21 r i
J
0.30- :
0'3'5 '
0.332 1
0.340^
— 1
1
-_
-- --
!
— 1
1
1
0.34S
-
!
I !
m
ii^
TABLE OF LEI
Weigl
Approximate Lengths, in Feet, betw
TABLE XXIX.
TABLE OF LENGTHS OF LATTICE OR LACING BARS.
Weight per foot of same, and weight of rivet-heads.
ximate Lengths, in Feet, between Centres of Rivets.
TABLE XXIX
TABLE OF LENGTHS OF LATTICE
Weight per foot of same, and weight of
■
OR
rivct-h
LACING
ead.s.
BARS.
Approximate Lengths, in Feet, between Centres of Rivets.
990_
009
031
11"
I Li"
12"
1 2 J"
•3"
i3V
14"
144"
•5"
I c'"
16"
i6i"
17"
• 7-i"
18"
i8i"
19"
•9i"
— -
r!o27
1.119
1.^38
1. 157
1. 180
1.204
1.045
1.065
1. 08 1
1. 104
1. 122
i.T7"s^
•-•95
1.21S
"..238"
-
1. 214
074
t02
r28"
153
1.086
I. no
1.230
1.250
1.269
1 .289
••307
••327
'-347
1.548
•-587
'•■45_
1. 169
i-194_
1. 219
••364
••399
••135
1. 160
1. 187
1.274
1.309
'•383
1.420
1.440
1.456
'•475,
••495
••5^7
••538
1.494
• •S^4
1.226
1.252
1.261
1.284
•-295
1.320
'•332
_i-353_
•-.377
•-367
r.402
1.388
1.426
1.458
'-53^
••567
1.602
1.625
1.640
1.678
1-739
181
210
.240
.268
.300'
■33^
■395
.428
I 2 1 3"
1.242
1.246
1.270
Z'^75.
1.306
1.312
••344
1.414
1-447
1.471
1.494
1.478
1.502
•-553
1.572
1.5S8
1. 610
1.661
1.700
'•774
••793
••338'
1.362
1.369
1.404
'-4,57
..644
1 .6S0
1.720
•-75S
1.S30
1.268
1.298
1.329
1.300
^■33^
••395
1.428
••459
1.485
■-5'4
1-527
••559
_'-58i_
1.610
1.596
1.619
1.644
1.630 1 1.667
1.650 1 1.689
^ ••704
1.7:5
•-739
1.776
1.814
1.850
'•329
1 .356
1.388
••357
1.388
1.390
1.422
1.422
'•453
1.518 1.550
'•759
•-795
•-833
1.868
1.450
' 1-477
1.480
i.546_
r.5'72
'-577
1.679
1.714
•-738
_^749_
••77'
_J:""9_
1.S07
~f.829
1.S17
1.851
1.888
_'-357..
_J-390__
J-422 ,
J -453
1.419
1.448
1.509
1.540
1.567
._L-.595_
1.623
1 .650
1.604
1.630
'-657
'•637
1.664
1 .670
'•704
1 .840
_'-'^"7._
••_9L3_
1.422
1.450
1.448
1.476
1.506
••5.16
'•599
1.627
1.652
1.697
• •730
1.762
1.786"
1.811
••7'i5
1.864
1 .900
1.936
••477
1.50C
•■535
••565
••565
••593
1.689
I.7I4_
1.742
••723
••753
1.SJI
1.852
1.887
r.923
1.956
1.480
1.509
••5.3<^
1.567
••599
1.6S1
••745
1.776
_J.-^-^-_
i.8t6
1.902
1.928
1.911
••935
1.944
1.969
1.978
•459
1.485
1.514
1.540^
• •572
••595
1.627
•-657
1.689
~f.723"
'-753
1.786
_':623_
1.652
"1.681
1.714
_J-745
1.776
1.811
1.842
_l876_
1.911
1.944
1.680
1.710
1.771^
1.S05
•■835
1.863
I.iS(i()
i.,S()5
'-'J- 5
2.003
•494
1.518
1.546
1.680
1.710
1.709
1.740
1.769
1.800
1.801
1.83.
1.960
__L994
2.028
.527
••55°
__l--577__
1.610
1.604
••637
1.630
1.G64
_i.697_
••730
1.762
1.740
1.770
i.8?o
1. 861
1.892
1.956
1.988
2.023
2053
:S59_.
.596
f'3o
.667
l7_°'L
•739
V.584
1.742
'•76';
i.Soi
1.800
1.830
1.829
1.859
1.890
1.8 sy
1.889
1.890
1. 92 1
1.951
1 .9M0
2.009
~IK°37l
2.0(17
1.9S2
2.016
2.042
2.070
2.100
2.046
2.081
1.619
i.650
1.689
1.644
1.670
1.771
1.920
_ 1-950 _
•-977
2.013
2.038
"2.068
2.098
2.1 27
2.156
2.187'
2.219
2.2.^9
2.077_
2.109
1.679
1.704
1.805
••835
1.83,
1.863
1. 861
1.892
1.920
1.948
2.102
"2.131
2-133
_J-7i4_
1.749
• •73«
1.921
1.950
1.9S0
2.013
_L977_
2.009
2.008
2.037
2.161
1.725
1.77 1
1.807
1.840
1.877
_l-79S_
1.S29
"T.864~
1.900
1A93'''^
_'//'9_
2.005
2.040
2.076
~^27n4
1. 82 1
1.852
1.887
1.869
1.902
1.895
1.928
1.960
1.994
2.028
2.061
1.925
r.956
1.9S8
2.022
"2^053 "
2.089
2.122
2.TT5'"
2.1S9
2.225
••95'
1.982
2.016
2.046
2.081
2.115"
2.129
2-159
2.189
'•7 59
1-779
1.8.7
1.S5.
2.038
2.068
2.01 )S
2.156
2.187
2.219
776
.81.)
'•795
'•8^,3
'•935
_K969
2.003
-i037__
2.071
2.106
2.140
2.042
2.070
2.100
2. 1 29
2.186
2.216
2.244
••923
2.077
2.102
2.131
2.161
2. 192
_J;J59
2.1S9
2.2.M
2.216
2.244
2.273
;s5o"
.886^
;02S
1.868
1.888
••9'3
1.947
" 1-983
1.956
1.978
2.109
"2^140
2-^33
2.165
2.244
2.276
_---73._
2.304
2-303
__l-.?05_^
1.940
1.926
1.990
2-013
2-3.33
1-959
2.026
2.060
2.04S
2.083'
2.120
2.095
2.129
2.146
2:179
2.214
^ 2.248
2.172
2.229
._."--4 .
2-257
2^253
2.2S4
2.280
12.313"^
2-,M3
2-374
: 18"
2.308
1-337.,
__ 2.334
2.364
^^.-■3(>3_.
•959^^
1-977
2.034
2.020
_Ji!S7.„
2.094
2.206
2.240
2.273
16"
-•393_
2.016
2.099
=••34
2.164
2.200
Mi"
2.264
2.297"
2.288 1 2.319
2.368 ! 2.39()
2.400 2.428
1
-•42 5 _
ol"
2.051
2.070
2- 153
2.178
2-324
2-319
2-455
1
12',"
•3"
•31'"
■4"
1 - " » r 1 "
i6i"
.7" 1 '7/'
1
iS.i" 1 19"
, '9'/'
.
1
Width,
in
inches.
Weight per 1
in pounds
Foot,
End
allow-
ance
for one
bar.
Rivet-Heads.
iSi"
19"
•9i"
20"
20 V'
21"
21.^"
22"
1
DlAME-
TKR, IN
INCHES.
Weight
OF TWO
IIE.MIS, IN
POUNDS.
o.oS
i8"
v
■h"
■ill
4"
4V'
5"'
5i"
6"
I-2S
0.145
i
•.36
0.153
0.161
'1
It',
0.12
6i"
7"
• J
1.46
••57
•■95
5,
0.16
0.20
0.25
74"
8"
9"
n'"
9/
10"
lOi"
O.I 80
- ■
■
2
..67
1.78
1. 88
2.08
2.21
0.188
1.678
1739
1.700
••774_
•793
2i
0.197
IS
I
a
0.32
0.40
1.720
I7SS
1.830
1.850
1.867
1739
1.776
1.8 1 4
1.886
1.940
.'•^59
••977
2.016
2.051
2.070
^2.094
2{
2?
2h
2.34
2.97
3.'3
0.215
0.223
0.231
•759
••795
••'^33
1.868
1.905
11"
2-47
4t
0.47
0.55
•779
1.817
1. 85 1 1.888
1.926
•-959
1.996
_2.o34_
2.057
Hi"
12"
1.807
1.840
..877
••9>3
1.947
1. 983
2.020
2.60
I
1.829
1.864
1.900
r.923
1.936
1.969
2.005
2.040
2.076
2.099
2.120
2.140
2- 134
2. '53
2.17S
2.200
I2L"
,.852
1.887
1.956
1.990
2.026
2.060
13"
2i
273
2.86
3.29
0.250
1.876
1.911
••935
1.960
".'988"
1.969
1994
2.022
1.978
2.013
2.048
2.071
2.083
i3->"
•4" "
~.4i"
2?
3-44
0.258
1.902
2.003
'2.028
2.037
2.106
1.928
2.061
2.122
2.129
"1.155"
2.164
o7
3-00
.5 (v^
1 ^ ■,r,r.
• .c)S6
2053
2.089
2.189
2.22 s
■5"
'5i"
16"
"i6.i"
1.982
2.016
2.042
2.046
2.077
2.081
2.US
2.146
'~2Tr72^
2.179
_ 2-214
2.240
2.248
2-273
3
3i
!
1
3-^3
3.26
3.39
375
3-91
1 0.274
O.2S2
—
2.109
2.140
2.206
2.0 1 J
— —
2.038
2.070
2.102
2. 131
2^33
2.165
2.199
2.229
__=fS7_
2.284
2.204
2.29-:
2.068
2.100
2.161
2.192
2.224
2.253
2.280
2.2S8
2.319'
2.343
2.368
2.396
2-324
2.349
_ 2.374
2.400
72428;
2-445
_-4«2
2.510
2-543
2-570
2. 596
3\
33
4.06
0.291
2.098
2.129
2.159
2.189
3.221
nV
2.127
2.156
2.187
2.219
2.249
2.313
2-337
2.364
18"
4.22
1 0299
2.156
2.1 86
2.216
_2.244_
2.273
2^303
2.276
2.30S
2-334
1 84"
3i
'
2.187
2. 216
2.244
2.304
2-333
4-38 '
4-54
4-69
0.307
2.219
2.244
2.276
2.273
=•304
2.363
2.393
2.423
2.450
2.47S
2.509
2^543
2.425
• 9-^'
20"
Vo.i"
21"
21I" "
22"
3?
35
3l
4
1
0.3 '5
0.323
2.249
_-i-333__
2^3''3
2^393
2^425
2-455
i •91."
2.362
2.392
2.423
2.452
2.4S2
2.392^
2.422
2.450
2.4-9
2.510
20.i"
2.452
2.470
_-:5°9_
2.542
2.570
211"
1
2.280
2.308
'2.337
"-•3f'S "
2^334
2.364
2.396
2-3^3
2-343
4.S5 ; 0.332
5.00 : 0.340
2-374
j..\oo 2.428
1
iS"
1
iS.i" i 19"
20"
21"
22"
1
5.16
' 0.34S
J:
H
^
TABLE
CHA>
SPAC
/) = (!
;k'cs i>f c
tiVL'ii. the
;o!itaitiinj
/)
4"
6"
7"
8"
9"
10 '
12"
«5"
'1
TABLE XXX.
TABLE OF SIZES OF LATTICE BARS FOR
CHANNELS OF VARIOUS DEPTHS, AND
SPACED AT VARIOUS DISTANCES.
/' — (k'ptli of clKinncl, ;ui<l ,/ = distance between inner
cs ..f ciiannels. If tlie value of d lie between the values
•,rn, the size of lattice bars is to be taken from the column
i'ltainin^ the luxt /aixts/ value of (/.
/>
4"
5"
6"
7"
8"
9"
10"
12"
Sizes of Lattice-Bars.
</=zD </ = 1.25/? ' '/ = '-5^ '/ - '^S^^ : "' '■
iD
\" ^ 'i"
i" X >l"
k" X JS"
V X 'J"
A" x'4"
{%" X 2\"
3" X jj"
J" X It"
\" X U"
1" =< >(■'
1" X Ij"
i'4"x 14"
X \\
X
1"
X ,r' i" X .f
X l|" }" X li"
V X ,r' i" X .4" j"_^-"
I" x_|r
(
X 2"
X i"
A'xir ' A'x 2^" rt"x 2r
^"x:i- ^"x^r'ift"^^
■J" X zV' i" X 21"
A"x"2i"
a I
t^
!•
^>l'
TABLE
NEL!
AT V
I) -(
I,m.'s ot »,
,ivi'ii, till
rniitaiiuii
n
4"
5'_
6"'
7"
8'
9'
10 ■
12 '
15''
!•'■ • ''-'"'l-' ■'HI l|l.l,JI|.iJj,i^WBK*
TABLE XXXI.
TABLE OF SIZES OF LACING-BARS FOR CHAN-
NELS OF VARIOUS DEPTHS, AND SPACED
AT VARIOUS DISTANCES.
n — (lci)tli <»t" i-'haniu'l, and </ = distaiui.' hftwcL'ii iniuT
iiaci's (if (.liaiiiicls. If the value of li lie between the values
Jveii, the size of UKMiij;-bars is to i)e taken from the eolunii
I containing the inxt /ti/xisf value of </.
/>
,/ --: /)
Sizes ol Latiiifj-Bars.
,/ : \.l-^/) ,/ = I.5/J ./= 1.75/^
1
4"
r X iv'
1" X ,!■' i 1" X ,T" V X -'"
1" X :{■
5'
6"
7"
8'
r X ,t'
i' X 3*
i" X 3^*
xV X :r
i« X 2"
r X 2i»
^"X2r
I'/'x-i' , A"x..i-
^" X 2f ^'xlir
A'x.i'
ll-/ X -M"
rV" X 2f
r\"x.f
9"
lO'
y X -i"
,Y X 2i'
.V," X 3"
A' X 2f
r X 2f"
Vxa'
r X .•;■•
r X 3"
12"
15" '~
r X J"
V X ^,r
r X ,;r
i" X 3i"
;.. V ,-
I
•^^'
C/3
<
<
H
J
CQ
<
K
a
« t
C/3
<
<
H
o
J
<
:r
I/.
C
■:r. 2
.E «
-I
^ i ^ .
Si
■- ;^ rs
3 ^ >^ c
- j: 75 "J
.E i '^ ?
rr C r; — ^
— rj V *--
-c .j; C C o
^ \\ T. > ■=.
c
rt
j;C
~ c — ~»
X3 II X - C
S.
u
••
<«
&
>.
m
W
1/1
u
N
« t »») ♦'♦Oi -f' ^' n
lA
T»^
TC'i *^^ ■•#• ' ^^
'/I
'»
1
\
"1
■
"1
«f
1
"
* • ' « ,► • « i
"I "■' O t>., t-. W5 » On'
i i . I I ) I
'1 fO "1 '•) f») r^ "f
M I j ! I ^
T^
f^i f*) f1 rn r1 '^ r-, .,. .f
"T •** • '"¥• "*" 11* ■*» «iw —
I i I I , I I !
t! f1
*^ n
fO — -r
Ssl^ 2
l>.'~!!»
"** ''Vi"'V *U •** •**"
» » » «
» 1 C o : M I >o
/I
If
'i
- tu
- O
\
E 1 .
I)
i
I
t
'K
'•} ii
W
fc
cr.
H I
«
- -^ ->
:r. o
y >
tc
tr, -^ j::
V "J
"1 IxvO
U I
o «
1 -^ « ta
tr
■^•^a"={sl<
« "i! r^.
O t^
t-^;o ' f^ c-
t- ■
!
1
!
i I
"-I
ft
— ir>
t
o
»
J
T
IT' ?
• H"^ "^,< <i -^i ■•
i/"j 'O ^'"^ 'C
r^ « i 1^ O o
tf}
t^, CN O - '1
fl^o : ""• ss
S; fc t t
■^ -*-t «M .
o vo vo >: ~
t » t t
. L- L- l^lj.
-T LO, u-1 v£ .>2 ^ ^
■V. c •/: c
»- !L- * '
'• "". c o
!
w
l"(irnui
the (Iki
Uia.
\
D.a.
1^
'I
■ormii
BRIDGES OF CLASS A.
l;i^ f roller in inches. The first aiul last vertical liiie;
ivc
the diam'^'i'-" l»~''nussil)Ie pressures on the rollers.
M"
;,.(V5
3.85-5
J. 1595
4-^4'L^
9.11 i
4- 1.)
4.4
^^'L
>()!
!l 4.5>«='
' 4.v>0-
4.,S4
4'1
6i
.Si
5.00OO
lo"
_9:63
10.13
10.37
lo.fio
10.S3
tt.27
I. 4S
I I .1 ic )
I r.c»
12.50
C5'
9-47
<>S4
10.20
10.57
975
10.13
10.50
lO.SS
10.02
10.40
10.67
10.79
11.17
10.28
11.07
11.46
•0.53
10.78
10.94
11.19
M.45
1 \.6()
'1.34
11.61
11.87
11.75
12.02
11.02
12.29
Il.2f)
1 > 1 ■»
12.56
11.50
1 1 .92
'^■.y
__'--^-...
ri.72
12.17
12.40
12.62
•3.07
II.OI
1 2.S6
'3-3-
IJ.Ki
[2.(1;,
1 ',.10
i,v;i>
I2.3S
12.S;
';v.i3
13.S0
!:;._;()
',)07
'3-55
14.04
12.7.)
>3-^9
13.78
14.27
13.00
•3-50
I |.0O
14.50
28'
o-').i
1.56
1.86
2(»
3.20
378
4^03
4.28
±JiiL
4.76
5.00
2f
JLt"
I?
11"
Di
/
TABLE OF PERMISSIBLE PRESSU
I'ormula, /- = o.J5V'<7, where /- is the pressure in tons per Hue:
tiie diameters, and the upper and lower lines the leii-ih ot roll
3-3»
•54 I
3-64
3.'^5
4.68
4.-6
4.S4
4.<)2
3-64
_3^9
3-77
4.1
3-89
4.2
4:°'_
4.3
-( I 1
4-S
4,24
3-95
i 4-oS J
4.IS
_ 4-35 _
4.46
4.56"
4.66
4.76
4.86
4.96
4.24
1 A^^3
44«
__4-5L
4-59
5-oS
S-'4_
5-4L
5-5°
5-30
5-4'
J- 5'
5.6.
5-7'
5.S1
5.91
6.00
5'74
5.sr)_
5-97
6.o8_
6.19
6.40
6.^0
D;a.
6.ig_
"6.31
643
>55
6.66
"678"
6.S9
K"
6.63
6.76
"6.89
7.26
"7.3'^"
7.5c
6.93
_. "^f) „
7.07
7.21
7 OS
7.4S
7-5'
7.(y)
7. SI
7.95
7.62
. >S.O(i
7-75
8.23
- .s-
8.00
16'
8.50
S.I
S.(
H-5
8.7
s.s
().0
t8"
TABLE XXXIV.
WISSIBLE PRESSURES ON ROLLERS FOR BRIDGES OF CLASS A.
. „.cssu,.. in .ons per Im.al inch „f roller, and ,/ ,l,e clian,c.cr „( roller in inches. The «>»' ;'»'' J-'^;"'''^'' '""^
.er lines the len-lh .if rnller,s. The inlern,ecli,ae spaces c.ntain ll.c pemnss.ble pressures on the tollers.
I
\
lf»
TA\,
1 Orniuhi
Dia.
ii to"
-fk
4'i
.l--'>-
■l-l-
■4-<">
t.
S-oO
i.,
\s...'^
U^
.v.K
;
_?•■'',
k
5'5^,
/t
' _ S'<'i
ft;
5- 74
?-\5
Da
in'
ta\es of classes b and c.
iirniul:i
roller in inches. The first and last vertical linos
i!K' i.ianj^j^. [HMMiiissihlc [)rcssurcs on the ••oilers.
iDia.
ID a.
rr r.t
26"
27"
-1-4-
■I.5V
4-9i
-M' i
5-53-,
5-85 I
10"
I0.,]4
10.70
11.05
11.7J
12.04 I
'-■35 j
t2.66
I2.<)() I
'.5--5 r
I ;,.;•< I
I (.0<)
Mo
l.l.(.J
0.M5
10. V)
10.75
I r . I ;,
I I ..\'!
ir..S4
l-M'l
I .'.5.'
I-;. 17
14.07
I4-V'
1 5.^:0
10.;, t
10.72
11.10 1
io.7(.
1 l.lO
"•55 '
11.16 1
1 II.CKJ 1
II >>
1 1 .i>S
IJ.41 1
' 1 -93
iJ.jS
1J.S2 1
12.30
12.75
1 •3-2' '
\:M
1 ■,. 1 ;,
1 -yCtO 1
1 voo
IMS
i.i'C 1
M'34
'3.^3
113 1 1
iUk
14.1.S
1 1.(k) I
I'v-I')
1 I-5I
1 5.0;, 1
'43'
1 1-^4
i;.r 1
14.(..'
15.111
1 5.70 1
14.1)1
1 5.47
1 i().o2 ; 1
1 ; _M
i;.-S
i(..;,4 1
1 ^ :;o ,
II 1.07
i().65 1
15.78 1
16.37
! i^-QS ; '
1.48
2.40^!;
2:,s7
3-67 I
.(.06 ;
t4> '
4.Sj i
5.19
.v55 '
5.')o
0.24
Dia.
11'
I ■>"
'»
6.57
6<)0
-•54^
JS'
-i'
1 't "
-A
,1
3r
-.1 '
3i"
D;a.
4
V-
TABLE OF PERMISSIBLE PRESSURES
I'ormula. / = c).,:;i 25VV, whciv / is the pressure in tons per 1
'■;<• dianietcrs, and the ujiper and lower lines the len-tli of r
Da.
10"
1 1 "
\2"
'3
14"
•5"
16"
I ~''
l^
. —
■
1'
3..,s
4.13
4.2«
.I.4J
4.56
4.0(:i
1 -'1
!.;,S
4^51_
4.71
' 4. so
5. CI
5.i()
4-59
4.7S
4.96
5- '3
5-30
5.47
5-f'3
4.98
5. IS
5-36
S74
5.98
6.20
6.42
6.12
6.51
■•03__
7-^7
7v4
7.()7
6.
5-79
6.37
6.61
6.85
_7.07
^ 7.29_
7..S0
7-
5-37
5:56^
5-75
_ 5.92^
6.09
" 7
S-99
6.19
6.3S
6.s6
/
6.63
6.83
7-03
7
" s
s
.\.S2
■•30
5.7.S
6.26
(•••74
7.22
771
S.|.i
s
„ -•'■94_
5.06
viS
5'57
5-70
5-93
6.0S
6.22
6.42
6.92
709
7.26
7.60
7-77
7.91
S.io
S.29
S.p
S.I.I
8.S1
s
6.5S
6.74
_ 9
9
_;.;,o
5-^3
6.36
6.S9
7,42
7-95
S.48
11.01
9
5.41
;.');
6.50
7.04
7.58
S.I 2
8.66
i)..'0
1)
;.;:;
1 i.os
6.63
7. IS
S.29
S,S4
'i-,W
9'
^cv,
(i.:!o
6,76
7-3-
7.S()
S.45
9.01
O.vS
10.
-74
1 •■■;-'
(i.Sc)
7.46
S.04
S.Ol
<Mil
n.-(>
10
5..S5
'■■43
1 1 "
7.OJ
7.(0
13"
S.iS
14"
S.77
.5"
y-35
l()"
17"
10
n.i.
10"
IS
TABLE XXXV.
:ble pressures on rollers for bridges of classes b and c.
the pressure in tons per lineal inch of roller, and d the diameter of roller in inches. The first and la.st vertical lines
>\ver lines the len,i;lh of rollers. The intermediate spaces contain the permissible pressures on the rollers.
■ 5"
S74
5-98
6. 20
f,.42
16"
6.12
>7"
7.03_
7'^7
18"
.9"
7.57
20"
7.66
'7.97
8.27 '
8. 56
8.84
9.11
9-.l«
9-f'3
9.88
10.60
10.83^
11.05
11.27
11.69
21"
22"
=3"
24"
25"
26"
27"
28"
29"
30"
Dia.
i
)
0.89
__7:'7
1AA_
7.70
8.04 ! S.42
8.80
9.16
9.10
"9.56
9^57
9.96
10.34
10.70
11.05
_":39
11.72
9^95
10.36
10.34
10.76
10,72
II.IO
11.55"
11.48
11.95
12.40
>i"
1 'i"
! 2"
' 2j"
i
6.37
6.61
6.85
7.07
__7-29
7.50
S-37
8.68
8.99-
9.28
■9.S7
lO.tl
8.76
11.16
)
7.85
8... 3
8.40
8.6 s
__'^:'>' '
9-39
9.62
10.07
"10.28
9:4i_
9.72
10.02
9.51
9.S4
9.92
10.61
10.75
11.13
II. 16
"•55
11.58
11.98
11.99
)
12.41
12.82
13.21
13.60
•3^97
^ 14.33
14.69
_ J 5:03
._i5i7_.
15.70
12,84
)
6.63
' 6.83
7-5'
__7:J1_
"•07
S.M
8.0 r
8.St
<).0I
<>:o
9. vS
' .>.76;
9.94
17"
7.96
^ ^-'^^
S.44
8.67
8.89
9.12
9-33
9.S4
974
9.94_
io.i4_
io.;,3
10.52
iS"
10.17
10.48
10.78
11.08
n.36
11.49
"■93_
12.30
12.66
13.00
•.3^34
12.38
12.75
i3-'3
13.48
'3^S3
14.18
13.26
14.06
'-M5~
14.82
'5- '9
'5'55 1
__15-9_o_i
16.24
!
10.93
11.21;
1T.56
11.86
12.15
12.44
12.72
12.99
n.84
12.19
12.S5
I3^i7
13.48
)
7.03
7.22
7.41
7:60"
777
7-95
_ 8.I2
S.29
845
8.61
' «77^
,5'
_io.3i
10.60
10.87
2\"
\
__77i__
^7:9 L
8.10
12.04
'2-35
12:66
1 2.96
'3-25
13-53
13.81
14^09
'4^35
14.62
2|"
2i" ■
3"
10.63
10.88"
1 1.13
"•37
11.60
11.83
1 2.06
12.28"
)
11.14
11.40
n.66
11.65
11.92
12.19
I2^4S
_'3^67
'3^99
)
8.2(J
8.48
8.66 "
9.01
_>'9
935
16"
^•5>
14.84
15.16
15^47
i5^78
'3^78
14.07
_'±36_
14.65^
lli'93_
15.20
I4^3'
14.62
14.91
11.91
12.15
12.39
1 2.63
12,86
22"
to. 50
12.71
13.26
16.02
16.57
16.90
17,22
"7^54
1 3J"
3r "
3i"
I
10.70
10.91
II. II
12.96
I3'4S
-J
13-52
•3-78
^•C'3
'S^So
15.78
16.34
16.07
16.65
16.95
16.37
28"
19*
20"
21'
24"
23"
26"
-.-"
-/
29"
30"
Dia, :
1
J
I
BL
RIV
Beari
\"
()88*
57S^
094
(109
867^
1-5
BLE X
RIVET T
CLASS
Beanng-strcsse
■\"
ir
— - —
(.SS'
0.719' ' c
578"
2.696 1
2.<X)6 I
0<)4
.V-3S_^
r^-
.^505 J
(lOtJ
K74 ;
S67
4.044 , <
1 125"
!■•.
I 156" ; I iSS"
in
u
',ia
.r
] :in'
I.-'JO"
n
6.750 '
7 T-
S.cKi s,.
.fl
(
• "• 'T- iMitim M i l il l llil l T""'
It.
u
U
a
I " i
J
1 ■
1 i "
1"
1 J
1 c
._,J-'.
1 '. '
. «
liliMllM.-
M'lMKNTS
IS I.NCH
TUNS
j
[
1
! 0250*
V n
32
S It
18
0.344'
r
0.375'
0.406"
1.219
1372
1524
1.677
, o.43»'
0.469"
0.381"
3'3''
0093
0.131
I.So
23<)_
0.31 1
0305
'.'It
()o;
73(1
o..S,s"5
1 04()
°7S0_
o.i;3S
I '03L_j
1 ' '25 !
; 1 219
0.844
0950
'055
ribi
0.938
1.055
1 290
1 524
l(.4l
"•75S
.875
' ■•>■;.)
2. no
J 032
1 161
1.289"
1 125
1.266
1 406
1547
1688
1 .829"
''969
2.110
27250
2.31)1
- xV
J-3'3 .
1.477
1 641
' 1.805
1.969
1 -''33
1.407
'■S«3
>7S8_
-i:934_
2.110
1.419
r.266
1 548_
1677
1.S05
"i-934
2.063
2.102
2 32 1
1.829
1981
2.2S6
T438
2 500
2.742
'•372
2 286
'3'2 .
1 406
1 500
1 ;<M
1 i,\-
1 477
I 582
1687
1 7' 13
I Si,,S
, 2.2()7
, 2.401
1 2625
2.461
26.37
2.8.3
27S9
2..>S9
,vi'M
TABLE X:
RIVET TA
CLASS 1
Bearing-stresses i
r
W"
0.406"
1. 219
1372"
1 524
1,6-7
" 1 .S29
l.>Si
2.2S(,
243S
2 51)0
2.74.'
A"
O.43.S''
i.477_
I 641
'•'r>l''JL.
2.297
2625
27S')
ii"
0,469*
V
0.500*
0.531*
0.563*
w
r
0.625"
w
11"
0.719*
J'
j-jys'
0.594*
0.656'
O.c'kSS*
0.7s
i-^S
1.407
■•5«3
1.75S "
'•'AM
2.110
2286
1.500
' I.6S8 '
I-S751
2.'jf.3
2.350
2.625
.2.S13
3.000
3.1SS"
3 375
•594
- L993_
2.192
2-39«
2.590
2,789
2.<>S9
1.188
3.586
r.688 1.782
1 .899 2.005
2.no ' 2.227
2.1 10
A-344_
2.579
2.813
3.047
3.2S1
3S'<>
3-750
3-9X5
1.210
i.:(i6
2.578
2.836
3.0',i4
3.(0)
3.867 ^
41^5
4,VS3
.(I'll
2.6(j6
2.966
3.235
3-505 _
.3-774
4.044
1 406
2.461
' 2.708
2.954 ""
3.200
3-445^
3.692
3-938
4-430
2, Si
' 547
I (vSS
2.321
_y3i_
2.74^
2.952
3.164
2.450
2.673
3-37
1 .829
2.895^
.3' 17
3-.340
3-65
1 (/«;)
2.1 10
2.461
2 6.?7
2-813
2..J89
3'6|
.1').]
4.JI
2. 2^0
3-,376 3.563
3:5«7__| .V7S6
3.797 ! 4.oaS
4-313
4-5S3
4.S,2
4. so
4.7S
i;.o6
\
I)
1
Ts
[
vS"
:t
it
'1
3LE x:
ilVET TA
ASSES B .
Bearing-Stresses
w
i
vS" j 0.719" ' 0.7;
•',3
J-J70
3-5
»o
: I
1 _ ^•707_
•t-o-H _
\ 4-7 '6
4.9:
it
5.054
5-2;
;'i
5-,5"J'
S.r3;
■1;
5.7 2«
5-9;
■ 1
6.005
6.y.
Ik"
1. 1 25"
'3i
' III
'Hi
i\"
.156" ; i.iS.s" I, J 19" i ,.2-0"
S.43S
9-4'A?
i
1
i
ZZI~
I
— - — - - - \"~ -
')757
ir.ojo ro.jS4 10. ;.|.S
c
a
Q
_r
u "
\\"
i
1 ■;
I"
w
-i!_li'«M
!i
/
I I
I
TABLE XXXV
RIVET TABLE.
CLASSES B AND (
Henoing-!
MOMENTS i
IN IN1.H i
TCJNS
o.ii;
0.164
r
HI
I ■'
■A"
0.225
0-^99
0.389
0/3 1 7_
0.759
0.')20
1 . I 04
1.311
i" i
, 0.250"
^Y
A" 1
0.313"
0.344"
r 1
0.375"
Ji"
0.281"
0.406"
1
0.938 i 1.055
..,72
1.2S9
1.406
1.758
1.929
2.100
2.281^
-•46.M
2-637
2.8 1 3
2.9S9_
3.164
1-523
1.055 ; i-is?
i-3'9
l-45'_
1. 61 2
':7i.4_
\ 1. 172
'■3'9
1.465
1. 61 2
1-759
_i.905
2.051
2.98_
2.491
1.905
1 1.289
1.45'
1.771
i.930_
2.093
2.256
2.418
2.579
2.740
2.901
2.093
, ' .406
1.583
2.2S1
__'_-?i3_
1 .640
1.758
1.875
•■7'5
1.S46
1-978
2.1 10
2.474
2.6()()
"2.857
3-047
1 .'/)2
2.242
3-23^
J 109 2.374
2.63.S
3-428
Bearing-stresses in tons.
1.64 1
i.S46_
-'.051
-•.2 5f)_
-•.461
.•.S7I""
3.07 6_
,v28i_
,v486_
i w .
i"
0.500"
1T»
hi
0-531"
A"
0-563"
19"
12
r
iV H"
li"
0.719"
J"
0.750"
ii"
0.469"
0-594"
0.625"
0.656*
0.68.S"
0.781
1.758
1.978
2.,.j8l
2.418
2.637
2.857
1.87 s
2.110
1.988
2.240
2.491
2.740
2.100
2.222
_ 2-3-44__
2.637
2.930
3-223
3-516
3.809
4.101
4-395
4.688
4-98V "
5-274
3-077
3-585
_3:692__
_3i999„
4.306
4.614
4.922
5-230
2.369
2.638
2.902
" 3-I65 '
3.428
3.691
3:9j6^^
4.220
4-t84
2.503
2.784
3-063
3-~34'
3.619
3-896
4-'75
_3-_2-'3_
3-5-16
3,S(j8
_4.i.p
4-5""
_4-834
_5-'5'>
5-4:9
•
2-344
2.579
3-370
3-S16
3-707
3.868
2.8 1 3_
3-047
2.989
3-238
3.486
3-736
3-985
4-235
4-483
4.044
4-380
4.219
4-395
4-570
4.761
3.070_
3.296
3-516
3-7.36
3.281
.■3;S16;
3-750
4. aw
4.716
5-054
5-39'
5.728
4.921
5-273
_S-62S__
5-977
6-328
5-i2(
S-4<),1
4-454
4-733
5.01 1
5.86c
6.22f
3-955
4.748
5-538
5.801
6.065
6.59?
^ABLE XXXVII.
RIVET TABLE.
CLASSES B AND C.
Bearing-stresses in tons.
Diameters.
i w
u" : r
M"
W
0.813"
II"
0.844"
*"
2 0'/
0.906"
w
0.938"
w
1"
1. 000"
i^V
•1^"
^iV
«l"
I .1 »
'52
•A"
1. 1 88"
-^" 1 T
0.68S"
0.719" 0.750"
—. : 1
0.781"
0.875"
0.969"
1.031"
1.063"
1.094"
r.125"
I.I 56"
1. 219"
1.250" ,
a"
" r
- J.
H"
i"
If
3-2^3
3-5l6
•
J-37„o__
3-5>6
-
3-707
3.868
._4-39S_
5.126
5-493
5.860
6.226
6.592"
4-570
4-95'
5-33'
5-713
6.094
1 i
' 1
4.044
4.219
_4-747^_^
5.142
_ 5-537^
5-933
6.329
4-923
6.358
6.812
_4-"P__
4:38o_
_±570_
4.921
5-273
_ .S;333 _
5743
5-948
6.373
6.797
7.222
7.647
6-153
- ^''WJ^
7.031
7.47'
4-5"
. _4-834__
4716
5-054
6.562
7-031
7.500
i
6.153
6.563
6.973
7-3^3
8.J04
5-' 56
5-391 5.625
7.266
7-735
7.969
8.438
8.966
9-493
--
5-479
5.728
5-977
6.328
6.475
6.856
_.'^7_25
7.120
7.720
7.969
8.438"
S.219
8.702"
8-3.^,6
S.967
8.7 1 7
9.757
i
5.801
t
6.065
7.910
8.174
9.229
10.020
10.28.J
10.5^8 i
I
\
r\
'Hi
12
10'
('0'
.So'
100'
1 lo'"
l-'O'
1-0'
I So'
lip'
RoaJwaj
Hi
•(O-
•So'
i
^^^
/
bpan
I
50'
<)0'
So'
100'
IJO'
l-o'
i.'Sr'
190'
::.)o'
-TO
JOO'
TABLE XXXVlll.
LABOR IN ERECTION.
do'
70'
So'
i;o'
100'
I 10'^
I Jo' "
I ;o'
I ro'
ii«i'
1-0'
l,V'
uyV
-M '. '
.'|o'
-•V/
W'
104
I I
no
.•S4
I IS
' I -
170
-0.1
-,V'
. vi 5
.v.)
-1".
310
5 ^"
r ;o
I. So
-I ;
.•50
. » ' 5
.!">
-110
540
650
"10
770
8.50
S»IO
IP
KV)
'0
\<i(')
11)0
200
-v;"
239
J()4
2;S
^ot
1 ' 7
.'■} '
.>5' '
.i~ 'I
.i'i5
Jir
■i >■ <
404
^ 4^^
5'7
544
"0
f^iOO
(ij ',
USll
7--
■fi
7S,S
■^13
S;(,
S-i)
<)22
040
(jno
I if,
JIO
-'^1
■115
57'
MM
< It r-)
io.;o
r
j =
I
Table!
TONS OF
^'"g-strcss, J i„
I-engtl
lor
Ml/^l JO.OJ
A
-<)-\:
,,) ->^-A-,
I
TABLE XXXI)
TABLE OF WORKING-STRESSES. IN TONS OF 2000 POL
Calculate! by the fumu.Ia/'^ ''''''-^y wla-rc /' is c.|„;.l l„ Hk- w<.il<i„K.stro.ss. J tho area in
I -f U.004
D I
y;!*
1
i I.lMlgtll
1
1.10
1 .<ir
4
4i
.t.,,s
5"
5i"
0"
14.10
7"
_I7^42
7i"
21.24
25-3H
8i"
29.90
9"
34.79
9i"
40.05
10"
45.f'<''
: loj"
5i.fi.f
II"
57.96
I.J"
64.64
12"
v^ 1
,',.02
'<■}'
..«-53
II. ir
71.6c
'•74
4.14
j.iSli
7^95
10.43
'330
|6.5()
20.20
24.34
3S.65
33-4«
lS.6i
44- 11
50.02
5<J.27
62.87
(h),S2
••59 „
1 j(-.
3'55
3-83
5.07
. 7.45
'1.95
«>8o
9.21
•-••55
n.S4 "
iS.fxj
14..SO
19.32
I.S.27^
33.07
_ 27.44
26.2(>
32.12
3.1.S4 "^
37^^8
35.79
43.62
41.13
48.42
46.83
54J9
53.90
61.10
59-33
67.97
66.15
o.;(i
' ■ ' •
-•'" _.
3.2.1
4'7.5
(>.5i
.*<.(.5
1 1.17
14.07
'7^37
21.05
25^'3
29.51)
34.43
3().66
' 45^2f>
49.59
47.W
57.58
6|.2S
1 1 1
o.;o
0.64
1,1 1
2,01
l.M.
3.01 1
2.S5
4.41
|I3_
li.lO
5.72
.S.14
7.(i()
'^^•55
'1-97
•334
ij.i.l
10.51
' .S-70
1 20.0S
34.03
32.1)1)
! 2.S..]S
.IV •'
4.V72
42.22
5S.''<4
54.13
6...45
(0.64
0.-,i)
1.7.1
.v^>7
.SvV^
/ •-•*
.1.42
M..|.)
'4.y3.
lS.3()
3I.(>S
, 26.04
30^59
35.48
.10.75
46.42
5-'.45
58.S6
1 J
0.;;
0..). p
1 .(ij
2..1.S
•,.t<2
5.05
(i.Si
S.I II
1 II.3.S
14.21
17.43
31.03
25-01
29^39
3416
.i9.3-
44.87
j 50.80
1 57."
0.51
0.1)2
1.51
-■,V)
.v.V.)
4-75
'M3.
S.44
i_l0.79
'3^52
16.62
30.11
2.V<>S
2S.25
32..S()
37^9't
43.37
49.19
SS.58
i ;
0.4S
0.S5
I..1I
2.I.S
.^I9
4.4S
().0S
7.W
1 10.26
13..S7
I5.S()
«).24
22Sy.)
27.14
3'-('7
3''^5')
41.91
47.61
53.70
' OJ
-^.-if _
o.Sc
1 ,;,.'
2.0;
j.Ol
4-2,?
5--'->
7 •5''^
'>74
12.27
\ ' .V ' 5
I.S.tl
22.05
36.07
30.49
1 35^30
40.49
46.08
52.05
1 1
0.42
0.75
1.2-1
li»2
2.,S3
3'W
5'44
7.19
9.27
ll.(K)
'4.47
17.(1.
21. 1?
25.06
2')..V'
, .Vt'O.)
39. '2
4.|.59
SO-4 5
I ; '.
0.39
0.70
'•'7
I.Sl
2.07
3-78
5.16
(1..S3
«.82
11.15
; •3^.\?
Ki.SS
20.29
24.09
28...7
1 ,i2.8.1
37.79
•y.'4
! -iS.,SS
'3
J?-.37_^
O.fiT)
I.IO
'•7 1
-■.''.1
3-5«
4 •■*<■)
-.4'!
S.40
10.(14
' '3^22
l(..|l>
I'M"
33.16
27,22
31.68
• 3''. 52
1 4^.75
47..17
1 ; ', '
o-.H
0.02
I.C4
r .( i2
-■.]'>
.i-39
4"t
(. iS
.S.OI
10.17
12.65
13.11
1 S.49
IS.70
-I t -n
26.26
■?0. t!6
-■9.47
2S.45
35.28
,54.0s
32.93
40..W
39.08
37.82
45-.^9 ■
4.1.47
43.0S
10' '
0.32
0,59
0.()S
'•5.5
2-27
3-22
4..I2
.,ss
7.<->4
9-7 •
14.85
17^95
2':,.2U
i(-.l'
0.30
^-?',5S_
o-T,
i|5
-•'.^
",.0()
.1.20
r.iKi
7.29
9.2.)
II. ro
14.2.)
17.24
20.()0
24^.?4
1 7
0.21)
0.52
O.S.S
'•,57
J.Cl
2.1)1
;,.9S
^ ,\^
(i.i)(i
S..SS
11.11
i.5''7
'"•57
I9..S3
2.V4''>
27^45
31..S4
3f'.59
41.75
I '"!'
0.27
0.50
0..S3
1 .;,(.)
I'M
-'•77
;,S,
:.IO
(.(.;
S.50
10.65
13.12
•5^93
1 9.09
22.61
26.50
30.77
35-4 •
40.45
1 iS'
0.20
0.4;
0.-9
1.24
I..S3
. -•''■•__
.v''4
1"''7
(1 ;()
S.I 5
10.21
1 2.60
1 5.32
..S.,!.S
21.S1
25^59
29-75
,34.28
.59.20
' J^il
0.25
0-45
0-75
i.iS
1.76
-■•52
.v47
1.1.1.
(..10
7.. So
i).So
12.11
'474
17.71
21.04
24.72
2.S.76
3,?. '9
37-99
1 M
C.23
0.4.1
0.71
1.12
\.(>S
2..|0
.V.?2
|.|(,
S.S4
7-J9
9.41
11.64
14.19
17.07
20.29
23.88
27.82
.32.13
36.82
\n\
0.22
0.41
0.<vS
r.o;
1.(0
2.29
;,.i.S
127
S.()0
7. IS
9-05
11.20
•3'''7
l(..4(.
i().i;i)
23.07
26.91
31.12
35-70
0.21
_o^y)
0.65
1.02
••53
2.19
3-04
1.09
5^3S
6.t/j
8.70
10.78
•3'^7
1 5..SS
iS.ijj
22.50
26.04
.50.15
,54.61
, joV
0.20
0. ■;-
0.(t2
O.yiS
i..|(.
2.10
2.91
v<)2
5.1(1
( ..( .2
S.V'
10. vS
I2.(..)
1 5.32
1S.27
21.56
25.21
21J.20
33-57
1 -:i
'Jv).>
0.59
0.> )]
1.40
2.01
2. So
>■ . /
4'i>
''■.i7
S.05
10.00
12.24
i4-7'»
1 7. (.5
20.86
24.40
28..30
.32.56
°A~^^
0.57
0.S9
■•.U
1.92
2.(l.S
;.l.2
4.7(.
"•13
/•75
9.64
il.Si
11...-S
17.0(1
20.18
23.<'3
27.42
3 '-59
' ■' -'
C.^,2
O.-yl
O.S( )
1.29
I.S5
•^•57
.5-47
4-57
5.IJ0
7-47
9.29
1 l..|0
i.'v7')
lf..^O
").53
22..SS
26.51)
,30.65
i jJl
0.52
O.Sj
1.24
I.7S
2.47
"v34
4.41
V<H)
7.20
.S.i),
1 I.OI
i.v.i.;
1 ;.i)()
iS.()o
22. IS
25-7')
29-75
- 1 !
0.50
0.79
l.lS
r.71
2-37
1 f 1
4.24
5'I7
(1.1)4
S.(,5
io.(.;,
I2.,S.|
1 5.44
1S.51
21.49
25.02
2S.SS
-.U' f!
0.4.S
o.7()
1.14
1.04
^-•-9
v09
4-0.)
5.^0
(1.70
S.V-
10.27
1 2.47
'4^').i
'7.7t 1
20.S4
-4 ,57
28.05
^4' H
0.4()
0.73 _
1.09
I.5S
2.20
2.99
3^'>.^
5.10
().4()
S.oS
'i-'i.i
12.06
'4-17
17.19 j
20.21
2.5^55
27.24
1 -5
■--- - -
0.70
o.()5
1 .05 _
I.OI
o.9,S__
o.(»4
0.91
o..S,S
0.S5
I.S2
'•47 '
I.41
..36
i.,;2
1.27
'•23
1.19
1.15
.2. 1 2
2.05
1.97
i.<p
1.84
..7.S
t.6()
1.6 1
^ -••^7__
-•/ 7
.MkS
2.5S
J. 50
J.42
-•■>.>
2.2()
2.19
VSo
'"^•f'5
3^.=;4
3^4-
3.20
.v'O _
3.0U
2.</)
l.'i--
4-,';'>
^4.21)
4.15
4.02
;,.S9
(1.25
(>.0.|
'" 5.S4
S.(.5
.S-47
5.29
5.12
4^'>7
4. Si
7. Si
7'55
7., 30
7.06
(..S4
6.63
6.42
(..04
i).(.i
9.00
' •'^•71
S.4.1
S.lS
7.')4
7.(«)
7^t7
11.67
11.51
IO-9.S
IO.(.l
10. 21)
10.00
().(.S
<»-.i9
().I2
1-1.02
i;,.'io
'3' '7
12.77
i2.;,i)
1 2.02
1 1.07
"•3.1
1 1.00
i(i.(.6
16.15
1 5.67"
15.20 i
14.7(1 1
'4,53 i
1 5.112 :
1.5.52 '
'.(•'I
19.60
19.02
"lS.47
'7-93
17.41
ll).92
l(..14
15.119
1 vvl
--•''*7__
21.57
20..)5
20. 56
I9.-I)
19.25
'■^•73
iS. 22
2(i..|6
^sr !
24.99
1! ^rr'
- - —
2 1-,;<:'
■ -'r -t
-3-6.5
- ,'
—
22.1)9
22.,56
"
—
,
2 1 .76
21. iS
J, -'^,
Ml
..5f.
J. I 2
2..SI
;,.(.(.
4.()7
5.S(,
7 • 2 .5
S.S3
10.70
'2.-7 1
Ivl2
'773
20 (.2
"
. -— -
.._
^ —
•■5'
1..16
1.12
2.05
1 .99
' -93
2.72
-•57
341
4^53
4.40
l-'7
5.6IJ
5^S-'
5^.v
7.04
6.S.1 j
i,.(,5 1
S6j
,S.5(,
•^■'3
10. 41)
10. 1 1
').^3 ,
12.42 1
12.10 1
11.7.. 1
14.71 _
' 1.50
' 3-VI3
17.25
i6.,So
i(>.;,(i !
2O.0S
IV-S7
■
|i).0(l
- — -
'•37
1.S7
'•77
2.4<)
2.42
-•35
v24
.V'S
^•o()
4.15
_4-03
;v92
5^2 1
5.117
49.?
6.46 j
(1.2S i
6.11
7'')i
7-'")
7.4.S
<).57
9.31
9.0(1
11.44
11.14
lo.S-i
'3-.S«
'.)•-' I
i 2.,S8
JS^94
'.S.r5
15.14 I
i,S.5S
iS.ii
1767
'
- ^
-
'•7' _
*
2.2S
2.16
2.10
2..>S
2.S.)
2.Sr
2-7 1
VSi
.v70
,v''0
4'7')
4.1.(1
(•54
|.|2
.S-79
5.64
5^4')
7.29
7.C9
6.1)1
(^■•73
S.S2
S.5.)
'^•37
S.I 6
1 0. 5 1
10. .50 1
10.04 1
9- 7 9 1
12.54
12.2,5
1 1 .92
1 1 .65
14-76 j
'4-.5y 1
14.04
i,5.(xj
17.22
l(i..So
i().40
16.00
^
I 13i'""i
1 M'' '
"
2.0.1
-'■'17
2.10
'v\-
3^,15
(•,ii
.1.19
.v3.^
S.21
6.:(.
6..10 j
7^'»6 I
7-7'' '
9.55
9.5' 1
' ' 31 !
1 1 .07 1
'3^.5''
'3^o5
1 5.02
15.25
1 1-'
1 x-V"
. _
-•.VI
2.\U
1-24
;,.Mi i
.1.09
.V'»S
4.97 !
(..24 1
(.oS ]
7-^7 ;
7-.v'^
i).09
.N.S7 .
1 o.So i
10.155 j
12.74
12.41 I
14.S9
'I-.S5
l 5./
1
- .,
voS
;.i)o
4^>i.5 {
.v')| i
7.-I
S.(j()
1 0. 50 1
12.15 1
14.22
1 V ■
;.oo
.V79
4-~2
y~')
7-o;
■"^•4.^ ■
lO.Od
11. S7 1
' 3-89
2.93
3^70 1
l.(« 1
.vO.S 1
(,.S7
S..'(.
.;.S,5 ,
1 1 .60 1
'.5-.t8
i
1
; -
. ___.
2.'.() i
,v'" !
1
■;•.•■) 1
(171
(.,;;;
S.Od
7.SS \
9.r«D
9.. 59 i
"•.54
1 1.09
'327
'3' 2
1 "W^"
- j'
,M 1
l..'S
"i ■ - 7
II. tw
7.70
.).iS
1 0.S4
1 2 70
i
.V V' <
i-i'i 1
.V ' 5 i
(..21.
7-5.)
S.97
10.(0 i
'243
rjA'
1"'
1
!
'
.|.09
.vC.> 1
().12 ;
7^,V. 1
S.7S
10.57
12. H)
ABLE XXXiX.
)NS OF 2000 POUNDS, FOR SQUARE WOODEN PILLARS.
K-strcss. A ll.c a.va in a imlu's. /. tlu- I.„^th in inches, and JJ the length ni side <.f s.marc in incncs
f
\
TAE
I
Len^
I
(>
s
lo
I ..'
I 1
III
IS
^ Bit
TABUD AS STRUTS IN LATERAL
l\
Length
in I
.,' loH J
s#i.
1
(,
s
10
I J
M
III
iS
-•■)
Ji'i
-•S
to
MDK-
WAV*.
I 1..'
<).-'
7-4
6.0
S-o
.».o
-•5
2.0
'•7
••5
'•,1
I.I
o.<r
o.S
o.S
0.7
o.r.
KiK.K
WAVH
IV-'
I ',.0
'■^•7 1 1 ;
I'.e I!
iri.
13.3
I I .()
I 1.0
10.5
1 0.0
''•5
,s.,s
_S.3
"7.7
6.7
(>.0
5.(1
5.0
.SlDR-
WAV*.
lo.S^
lO.J
l).0
7-t
S-9
4.S
.|.0
2.0
I.S
1.6
1.4
t.2
1.0
o.y
0.8
0.7
0.6
0.6
o.;
KlXiR.
WAVH.
io.8_
lO.f)
10.)
lO.J
10.0
7 9.8
s.s
Length of Strut
in feet.
n i) ® ®
10
12
It
5.S
.v.>
"5.0
4.8
4.3
4.0
.50
1.5
1
',.0
t-5
().G
3
3
4
<).o C)
10.,
7 1
' »4 I
(6
8.0 ^
r8
7-5
20
7'0
22
6.6
34
6.2 :i 26
12
'5-0
1
32
34
;
36
3«
1
40
16.5
1.
18.0
12
H)S
'3
21.0
't
22. ,
'5
24.0
16
25-5
t7
27.0
«8
2S.5
JO.O
.i9.
20
1
■
I^HK^HDI^HH
TABLE OF APPROXIMATE WOR
1
L
ength of S
in feet.
trut
7" 20#
!•
7" l'^# I-
f~\
f
SlIIK-
F.IH.K-
SlDK-
Ki)(;e- I Si
.
\^
■.^ v^
\S \\s.
« \v^.
» W-.
WAYS. w
-
=^-
-
^. _
1 1 '""
I
-''•7
27.0 1
24.2
24.5 M 2
•y
'■5
1
JIl.t
26.9
-'-1-0
2.}..(
1
vO
-'
-\vO .
26.7
22.7
-I'.l
(.
■'•'_
■5^"
23.0
26.S
21.0
24. J 1
s
(i.e.
I
20.^
26.2
1S.7
2.|.0 1
10
7*5
5
I.S..'
26.0
16.5
^,v7 1
12
0.0
('.
'5-7 ^
-5-7
'1
i-t.5
_ 2;,.5 1
1 I
'°i_
/
_'3-7 _;
25.2
..^'-•5_
23.1 1
1 1
1 J.O
,s
r2.o
2.1.7
1 1.2
■> > —
|S
1 ',.;
t)
10.3
2-1.2 1
')■:
■>->■*
' J
''>'^
10
->o
23-7
,S.s
^!''i —
i *
10.5
1 1
s.o ;
23.0
7- >
1 "■•
iS.c
1 J
7.0
--■.1
(..5
'o-i:2 z
i'>5
21.0
i 1
1 1
(i.j
21.7
-M.l
>• /
'^.a
20.2
j.>
i<).^
V-
15
16
'■0
20.5
4i
1.S.7 ^,
.t.o
I s.o
^ *
-5'.>
17
(.0
li|.2
.V ^
'7-i .
■,l)
27. c
I.S
. '-^
IS.I,
"v-
170
;^
.•S.5
10
.V-:
I.S.O
vO
II 1.3 : __
10
.lO'O
20
.vO
'".74 i
27
16.0
TABLE XL.
PROXIMATE WORKING LOADS FOR I-BEAMS USED AS STRUTS IN LATERAL
SYSTEMS OR SWAY BRACING.
20# I.
7" iS# I-
()■' II*
I
; 6" ..;
i
5#I 1
1
#i.
5" 'o* I.
j!
1" io» I.
4" 8# 1-
i
1
Length of Strut
in feet.
F.DC.K-
wws.
SlDK-
W.WS.
24.2
24.0
22.7
21.0
Kni-.E- . 1
WAYS.
^""347^1
24.4 J 1
24.2 '
SlI.K- j
WAYS. i
21.2
20.0
I, So
1 5.S
'3-7
"■7
IOC
S.7
7 ■ ^
(..,
___S-7
)•-'
3 7
3-?
]■[•
■J "i
■» 1
2.0
KlM.R-
U AVS.
21.6
Ji.S
J 1 .2
:i
J0.7 _
JO. 2
i'i-7
t'l-2
I S.7""
iS.l
i-.o
II. :
i v5
1 i.o
|| =;
1 (0
130
IJ.3
SmK-
W.WS.
KiHM.:-
VVAYS
18.2
i8.r
18.0 "
17.9
'7-7
'7.5
17.1
SlDl-;.
WA\s.
16.0
'37
1 1.7
97
8.0
Kdc.e-
WAVS.
[6.0
SlllE- ' EUGE-
' WAYS. j WAYS.
SlDK- 1 F.IK.E- '
Side-
ways.
Edge- i
WAYS.
mm
413 ®
® 9
27.0
18.2
'7-7
.fi.s
1 5.0
'3--
i_ "■s„
9.2
8.0
6.7"
i 5.O.
4.S
4.0
3-5
3>
-•7.
2.0
1.7
13.8
,3.8
'J-5 '.V5
!-•" 1 3--'
11,.: 13.0
10.8
10.8
I
26.9
26.7
LS-9.
'57
11. 1
1 9.7
13.0
12.8
10.2
"9.0
10.6 i
"10.4 ;
2
" "4
6
„._'-5.
3-0
I
2
26.5"
'5-5
14.9
12.6
9.2 '\ 12.7
74
10.2
4.5
3
2(1.2
^lS.7 "1 24.0
16.5 2;,.7
i 8.1 : .2,4
74 ■ i^o I S'9
1 0.0
9.8
8
6.0
4
2f).0
6.7 12.2
6.0 j 12.2
"5^ 11.6'
4.0 1 1 .0
3- 'O'S.J
j.S 10.0
4.8
10
7-5
5
' ^v"
1 1.2
-3-'
65
54
4.4
' ^3-6
3-0
14-5
14.0
I.VS
'3-0 ^
._ ■-•5
12.0
II. s
i 54
\ - 37. _.
3'0
12.0
~ri.7"
4.0
.^2
9-3
12
9.0
6
""' 2^2 '
.6.7
16.2
'S-7_;
•5-2
8.8
14
16
18
10.S
7
~'- ' 2:1.7 ■■
"•3
10.8
10.4
2'S
8.4
12.0
8
9
10
II
-4-
().; 32.2
7.5 ! 21.2 1
■y- ' 20.2
4.S 1.S.7
4.0 iS.o
.;.; 17.;
2.0
8.0 I
'3-5
-V7
^^ 2-5
! 2.2
1 2.0
-•- , 9-5 , '•»
7-5
20
15.0
-3-0 ,
.4.7__
14.2
13-7
_ '-_-Z__
I 2.2
2.6
2..5
1 2.0
1.8
1 0.0
9:6
9.2
\S.7"
S.I
2.0 : 8.8 j
, ..6
7.0
6.6
22
16.5
1 .- S.2 1
..; .-77-
1-3 7-2
>■' i 6.7
0.1) ' 6.3
0.S j 6.0
0..S ' 5.6
■7 '0.7; 5-- _
O.h 5.0
; .4
24
18.0
12
1 1.0
10.4
')7
y.o
8.2
7-5
1 1.6
'•5
1.2
6.2
26
__'9-.S_
21.0
'3
' 1 I
I.O
5-8
28
14
'^O ^ '
1 .6
1.4
1.0
o.y
' 0.9 5-3
30
^ 22.5
24.0
'5
''■3 1 7-'5
1 I.I 1 6.8
1 I 6.2
0.8 5.0
1 °7 J.:S„_
0.6 4-5
0.6 4.2
32
16
34
25-5
17
11.7
ri.2
10.7
10.2
> H)-
36
27.0
18
.]•- '""
16.0
C.7
'9
^ : 18.0
! 3-0
i ^-7
■ O.f)
38
j 30.0
0.8 1 5. 1
' 0.5
4.0
40
20
> ' 174
Ml
Twp < llol
h.'ll.im (
li.ittc I l;i.i
Diagonal
I'ovl criiin
I I'ciSl (DihIs
'RUSSES.
tv
\'
\
\
\^
\
{ 4
\
\
\
e \
\
\
\
\
\
: J . J
\
\
8 Panel.
Memi'
Tuii ri„.r.l
IV,
" i 8
6
_ri
8
9 Panel.
w
Multiply by
W'.
I'.'-iioiii ( ii,,i J.J ji
"I 3i Ji
" " ; 6
7
9
')
10
10
10
lO
_ — ... .
4
4
4
4 i
tan
• .Utcr lli.U(.'
I 'i.igiiii.ll .
74 1 7i
V 3* , V
7
7
<)
9
10
10
r
o
f
.u
l'"-l ri'Iiruiiji V
-'i
I'nst (DiHk r V
it i ~~k
V ' i
-4
s«t ».
1
¥ ! a
I o ! To the .'♦tre** ..n
i' -^ ■— - ^ each post mu^^^
be .uiileil JJ",
i
STRESSES IN SI
w = panel live load on one truss,
U\ = panel dcail load on one truss,
Jf"=upiKM- panel dead load on one truss,
= inclination of diagonal to vertical.
1
3 Panel.
■
4 Panel.
i
5
Member.
70
-
1
„ i
7V
2
70
Tup Chord .... I
I
2
3
t» i* , . 2
.1
'• .... 3
(t ti 1
1
•i
r.'itt.uu Chord ... I
i
i •
I
t
It It <>
1
1 1
I
>i
1 -,
1 , "
" • ■ ■ 3
i
1
" " ... 4
It li , . C
I'.attcr IW.uf . . . .
f
I
S
'i
'^
1 Diagonal ...... I
i
1
i
4. t
1
3
i
4
5
--
1
6
I'(jst ('I'liriuiglil'.iidKc) 1
i
i!
.i (. i. 1
" . 3
i
t
l'.»t (Dcck-Hridnc) . i
-»-
1 -
ti tt t. 2
i_ _^
.1 t. It ,
i
1
1
!■
TABLE XLI.
STRESSES IN SINGLE-INTERSECTION TRUSSES.
I on one truss,
d on one truss,
cad load on one truss,
diaironal to vertical.
anel.
4 Panel. \
5 Panel.
1
6 Panel.
7 Panel.
. 7T
8 Panel. i
9 Panel.
Multiply by
;F.
w
... ^
Wx i
2
w
3
w
f^'.
IV
s
6
u<
n\
7t;
1
,
2
3
4
4
5
6
6
7
9
10
10
4
4
7 ij
tanff
3
3
4i
4i
6
:i ; 7i
9
— . , j
6
6
8
s
10
Ti
2
^4
4
4
10 ,
I
I
->
3
3
74 1 74
i
4 1!
-
i
4
li
-
2
3
3
5
6
3
3
4
5
6
7
9
7 i
— ;
--^--1
!
1
i
1!
10
10
4 !:
■ 1
— —
I
'J
2
O
— I
^
2i
1
¥■
3
! ¥ 1 3i
i ¥
'
_ i ;
¥
«
2
I
— 1
¥ i J I
-- --1 ■
k
¥
4
^
i^"^
t
! ■ 1
1
»
1 i -^
¥ 1 °
'
—
1
-'i
-2 ■
^ ¥
_ ^ ___— .
■: T. s-^.;
i
-i
g
i, i
I
! '.^
1 'i
¥
2
4 1 _i
t ,1 i T
¥
¥
¥
I
J
-i
To the stre** ow
1 —
1
¥
¥
'i -i
J^
2
i
I
Ibe added W.
^ -i
r
o
~j - -
\ V i
II \ 'A i-\ \
i
1
1
1
f
\
J /SSES.
13 Panel.
w
11
l5
W
W
v/-
14 Panel.
w
I 3
I)
1 1.'
13
; 1 r
13
15 Panel.
mJ
Mi
.8i
23i
W 1
i8i
23i
w
w
%'
^4i
24i
6i
6i
<'i
Mi
.Si
'>i
Mi
I SI
W
w
w
w
^"5^
Multiply hy
t.in a.
STRESSES IN D
;i> — panel live luad n\\ oik- truss,
//', ~ panel tleail Unvd on one truss,
/r'^iijiper panel dead load on one tiuss,
u = inclination of short diagonal in \iriu'al,
13 = inclination of Ion;; diaj^niuil to VLilual.
MEMBER.
Top Choii
U It
(1 II
. .
. • 7
— -
— —
-^ ^-
littnin ('
hcl.l .
. . I
II
kl
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7 Panel.
• 3 ;
• 4
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8 PuiKl.
Panel.
V
V
V
V
/r,
r4
V
s ;| ¥
11
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II
II
. . 6
II
II
. • 7
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Diammal . .
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7
9
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10
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TABLE XLII.
STRESSES IN DOUBLE-INTERSECTION TRUSSES.
truss,
' truss,
(Ml (MR- tlllSS,
. (lual t(p \riii(.';il,
,oU.il t(l Vl'llUcll.
■J f
i
1\
lM;il(«I.
<
\
^
DOUBLE INTER
WROUGHT IRON HlC
-> f i ■
vv ;;?
. ;:?
;■ ■iff"
,H-
DOUBLE INTERSECTION
DUGHT IRON HIGHWAY BRIDGE
lMiit(»I.
X
^*
♦J
f
.y
^i^:y^'-':^ ".ell
HO'
,11""'
"'*
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I.
I
\
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h-u, I
IM.ilo II
i-tn.i
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- -
^
^
^
^
1
i-
f
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u.
II
I
GENERAL DESCRI
5*^
3 O
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1 .)-. .-..itltiiiU^SiUi
GENERAL DESCRIPTIVE PLATE OF DETAILS
i\
(i
N.
I'lalclll,
is
J
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t-
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K
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DETMLS FOF
IRON HIG
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^
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V
J J 2_i— i-i-^-
_J_J_J__J,'J!
i ,.
io
O J
"q" o o o j\-> J o Q !_ j;
o
DET/^ILS FOR A PONY TRUSS
IRON HIGHWAY BRIDGE.
PlaU'IU.
^■r'..-'^—-^-
\
O O O y -» . J ■> S~>,O...J:
o cTo o J Q o oo o_2_2
-51-^7
11
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■/ri/liifi/l/ /ooJ.
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I'Uih'V
RIES At
'A
■laGHWAY
CU A.
Wl
1
I •
DIAGRAM OF STRESSES
POR A
160' SPAN IRON HIGHW
CLA.SS A.
^v
? /O" J IS' JOSOv,"
Total,>r. U 41 fj'
/ •%•</,",' 7'/. .? .0/ a^
T()t(,/Srr /7 25 n'
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lit mi l.piKilh
Dr/tf/i of Trit.y
hire 1.11(1(1
Dcdil 1,(1(1 tl
Wind I'lTS-Vd"
S/l OF STRESSES AND SECTIONS
PliUrV.
POR A
O' SPAN IRON HIGHWAY BRIDGE.
CLASS A.
^^.
/jY /4.4!)n'
S'er. /S. 40 n"
/8.40\\
.kj
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o.6t }
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PORTION
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WORKING DRAWING
FOR A 160 FT. SPAN
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