&
S5
§
$
USD
T
United States
Department of
Agriculture
Forest Service
Forest
Products
Laboratory
National Wood in
Transportation
Information
Center
General
Technical
Report
FPL–GTR-125
In cooperation
With the
United States
Department of
Transportation
Federal
Highway
Administration
*9. --
sº iS,
-
(
SCIENCE
TG
3 / 0
UD | 19-
30 ol
Standard Plans for Timber
Bridge Superstructures
James P.
Matthew S.
cker
mith








&
<<1.
_T
7 G-
*/O
Abstract
These standardized bridge plans are for superstructures
consisting of treated timber. Seven superstructure types are
included: five longitudinal and two transverse deck systems.
Both HS20 and HS25 loadings are included, along with
L/360 and L/500 deflection criteria.
Keywords: timber bridge, design, standards, superstructures,
plans
/
U./((2-
1–02/
February 2001
Wacker, James P.; Smith, Matthew S. 2001. Standard plans for timber
bridge superstructures. Gen. Tech. Rep. FPL-GTR-125. Madison, WI:
U.S. Department of Agriculture, Forest Service, Forest Products Laboratory.
53 p.
A limited number of free copies of this publication are available to the
public from the Forest Products Laboratory, One Gifford Pinchot Drive,
Madison, WI 53705–2398. Laboratory publications are sent to hundreds
of libraries in the United States and elsewhere.
The Forest Products Laboratory is maintained in cooperation with the
University of Wisconsin.
The United States Department of Agriculture (USDA) prohibits discrimina-
tion in all its programs and activities on the basis of race, color, national
origin, sex, religion, age, disability, political beliefs, sexual orientation, or
marital or familial status. (Not all prohibited bases apply to all programs.)
Persons with disabilities who require alternative means for communication
of program information (Braille, large print, audiotape, etc.) should contact
the USDA's TARGET Center at (202) 720–2600 (voice and TDD). To file a
complaint of discrimination, write USDA, Director, Office of Civil Rights,
Room 326-W, Whitten Building, 1400 Independence Avenue, SW, Wash-
ington, DC 20250–9410, or call (202) 720–5964 (voice and TDD). USDA

is an equal opportunity provider and employer.
5/2/
Ørø.
@4%
Standard Plans for Timber Bridge Superstructures
James P. Wacker
USDA Forest Service, Forest Products Laboratory
Madison, Wisconsin, USA
Matthew S. Smith
Laminated Concepts, Inc.
Big Flats, New York, USA
Introduction
Interest in timber bridges has increased significantly in recent years, primarily as a result of two national
programs established by Congress: the Timber Bridge Initiative (TBI) passed in 1988 and the Intermodal
Surface Transportation and Efficiency Act (ISTEA) passed in 1991. These legislative actions provided
national emphasis on wood transportation structures and resulted in programs focusing on demonstration
bridges, research, and technology transfer. Within the area of technology transfer, a high-priority need
identified by bridge designers and builders has been the development of standardized timber bridge designs
and specifications. By providing the basic designinformation On specific timber bridge types, standardplans
and specifications should assist engineers who are not familiar with timber design.
The bridge plans presented in this publication are part of a series of standardized plans being developed for
timber highway bridges. The plans were developed as a cooperative effort between the USDOT Federal
Highway Administration (FHWA), the USDA Forest Service, Forest Products Laboratory (FPL),and
Laminated Concepts, Incorporated (LCl). The plans include standardized designs and details for seven
timber bridge superstructure types including five longitudinal deck and two beam systems utilizing both
sawn lumber and glued-laminated timber (glulam).
In the development of these designs, every effort has been made to present standardized designinformation
in a user-friendly format and allow maximumflexibility for the use of differentwoodmaterials, species, and
grades. Each set of plans encompasses numerous span length and width combinations, design loadings for
AASHTO HS20.44 and HS25-44 vehicles, and two options for live load deflection criteria. In addition,
information specific to skewed Crossings is provided when appropriate. In all cases, these designs must
be verified by a registered professional engineer prior to construction.
The USDA-Forest Service and USDOT-Federal Highway Administration hereby give notice that the
information hereincontained shall not create any warranty expressed or implied. The person or organization
using this information waives and relinquishes any and all claims against the United States of America, its
officers, employees, and project cooperators, for any loss, damage, personal injury, or death incident to,
or occurring as a consequence of, the use thereof.
Acknowledgments
We express appreciation to Merv Eriksson of the USDA Forest Service, Wood in Transportation Program,
Maureen Mathias (former FPL student engineer), and Sheila Rimal Duwadi of the Federal Highway
Administration for their assistance in the development of these plans.
Comments and Recommendations
Any comments or recommendations regarding these drawings are appreciated and can be sent as follows:
Mail: FPL Timber Bridge Program
USDA Forest Service
Forest Products Laboratory
One Gifford Pinchot Drive
Madison, WI 53705-2398
Fax: (608) 231-9303 or (608) 231-9592
Email: mailroom forest products laboratory@fs.fed.us
Websites: www.fpl.fs.fed.us/wit! or www.fs.fed.us/malwitſ
Specifications
AASHTO. 1996. Standard Spectications for Highway Bridges, 16th edition. Washington, DC:
American Association of State Highway and Transportation Officials. (With 1998 Interims)
AASHTO. 1991. Guide Specifications for the Design of Stress-laminated Wood Decks. Washington,
DC: American Association of State Highway and Transportation Officials.
AASHTO. 1995. Standard Specifications for Transportation Materials and Methods of Sampling
and Testing. Wol. 1: Specifications. 17th Edition. Washington, DC: American Association of State
Highway and Transportation Officials.
M111 Zinc (Hot-Dip Galvanized) Coatings for Iron and Steel Products
M133 Preservatives and Pressure Treatment Process for Timber
M168 Wood Products
M232 Zinc Coating (Hot-Dip) on Iron and Steel Hardware
ASTM. 1996. Annual Book of Standards. Philadelphia, PA: American Society of Testing and Materials.
ASTM A36
ASTM A722
Standard Specification for Structural Steel
Standard Specification for Uncoated, High-Strength Steel Bar for
Prestressing Concrete
ANSI/AITC. 1992. American National Standard for Strucural Glued Laminated Timber, ANSI/AITC
A190.1. Englewood, CO: American Institute of Timber Construction.
ANSI/ASME. 1981. Square and Hex Bolts and Screws (Inch Series) B18.2.1. New York, NY: American
Society of Mechanical Engineers.
AWPA. 1996. Standards. Woodstock, MD: American Wood Preservers' Association.
AWPA C14 Wood for Highway Construction - Preservative Treatment by Pressure
Process
AWPA M2 Inspection of Treated Timber Products
AWPA P1|13 Coal Tar Creosote for Land and, Fresh Water and Marine
AWPA P5 Waterborne Preservatives
AWPA P8 Oil-borne Preservatives
References
Faller, R.K.; Rosson, B.T.; Ritter, M.A.; Keller, E.A. (In Press). Development of Two TL-2 Bridge Railings
and Transitions for Use on Transverse Glue-Laminated Deck Bridges. Washington, DC: Transportation
Research Board.
Lee, P.D.H.; Ritter, M.A.; Triche, M. 1995. Standard Plans for Southern Pine Bridges. Madison, WI: U.S.
Ritter, M.A. 1990. Timber Bridges: Design, Construction, Inspection, and Maintenance. Washington,
DC: U.S. Department of Agriculture, Forest Service, EM7700-8.
Ritter, M.A.; Faller, R.K.; Lee, P.D.H.; Rosson, B.T.; Duwadi, S.R. 1995. Plans for Crash-Tested Bridge
Railings for longitudinal Wood Decks. Madison, WI: U.S. Department of Agriculture, Forest Service,
Forest Products Laboratory, FPL-GTR-87.
Ritter, M.A.; Lee, P.D.H. 1996. Recommended Construction Practices for Stress-Laminated Wood
Bridge Decks. In Proceedings of the International Wood Engineering Conference, October 28-31, 1996,
New Orleans, Louisiana, USA.
Ritter, M.A.; Faller, R.K., Bunnell, S.; Lee, P.D.H.; Rosson, B.T. 1998. Plans for Crash-Tested Bridge
Railings for longitudinal Wood Decks on Low-Volume Roads. Madison, WI: U.S. Department of
Agriculture, Forest Service, Forest Products Laboratory, FPL-GTR-107.
WWPI. 1996. Best Management Practices for the use of Treated Wood in Aquatic Environments.
Vancouver, WA: Western Wood Preservers Institute.
Contents Page.
Summary and Commentary 2
Longitudinal Deck Systems
Nail-Laminated Decks 4
Spike-Laminated Decks 8
Stress-Laminated Sawn Lumber Decks 12
Stress-Laminated Glulam Decks 21
Longitudinal Glulam Panel Decks 28
Substructure Connection Details for Longintudinal Decks 34
Beam Systems
Glulam Stringer and Transverse Glulam Deck - 35
Transverse Glulam Decks for Steel Beam Bridges 46
Miscellaneous Details
Department of Agriculture, Forest Service, Forest Products Laboratory, FPL-GTR-84.
Wearing Surface Recommendations 53
Summary and Commentary
Introduction
These timber bridge standards and specifications apply to superstructure design for highway loading applications. Substructures must be designed and analyzed by a
qualified professional engineer for each specific site. The primary purpose of these standards is to aid engineers who may not be familiar with timber bridge design. The
following information should help the designer by Summarizing key configuration and design features of each bridge system. The designer can utilize these standards during
the preliminary design phase to determine viable timber bridge superstructure systems for their site location. The designer is strongly encouraged to obtain the references
listed on the previous page, especially the AASHTO Standard Specifications for Highway Bridges, and Timber Bridges: Design, Construction, Inspection, and Maintenance
(EM7700-8). A limited number of free copies of EM7700-8 are available from the National Woodln Transportation Information Center located in Morgantown, West Virginia,
and may be Ordered via telephone at (304) 285-1591 or via internet at www.fs.fed.us/nalwit
Design Configuration
These standards include seven different bridge superstructure systems that are adaptable to spans ranging from 10 to 80 ft. Table A summarizes key configuration
information for the bridge systems included in these standards.
These standards permit the use of numerous wood species and wood preservatives, within certain parameters. The wood species, including softwoods and hardwoods,
must be included in the AASHTO or the NDS design tables, and the wood preservative must be compatible with the wood species. Refractory wood species are not allowed
due to poor preservative penetration. The Glulam Stringer and Transverse Glulam Deck system is restricted to southern pine and western species glulam. The use of
waterborne preservatives is not recommended for glulam members.
These standards are best suited for single-span or multiple simple—span bridges. Multiple-span continuous superstructures can be constructed with these standards, but
this requires further design by a qualified professional engineer. Single- and double-lane and non-skewed and skewed bridge configurations are included. Longitudinal deck
systems are most adaptable for spans ranging from 10 to 38 ft. An exception, however, is the Stress–Laminated Glulam Deck system which can span up to 58 ft. The
beam systems include transverse glulam decks On either glulam stringers or steel beams. The Glulam Stringer and Transverse Glulam Deck system includes spans from
20 to 80 ft for these standards. However, glulam stringer systems can be built for spans much longer than 80 ft, but this will require further analysis by a qualified
professional engineer.
Table A. — Bridge Configuration Summary
Superstructure Material || Wood Wood Material º º: º
Type type species | preservative size º SS º º
Nail-laminated Decks" Any 2 in. 8 – 16 10 – 28
->< & Sawn Oilborne
§ Spike-Laminated Decks lumber Any 0ſ 4 in. 8 – 16 12 – 34
O tº listed waterborne Wariable
Tö Stress—laminated Sawn Lumber Decks Iſl type 2 – 4 in. 8 – 16 10 — 34
º
º; wo b AASHTO
B E Stress—laminated Glulam Decks Or 3 – 9 in. 12 – 21 18 – 58
‘5, $2 NDS
C (ſ)
O > tº a tº C © 12, 16
- CD longitudinal Glulam Decks 42 – 51 in. 8-1/2 – 16-1/4 12 – 38 24 28 32
& Glued- SO. Pine Any
Glulam Stringers laminated l andlor Oilborne Stringer sizes 12, 16,
and d timber Western type predetermined 5-118 only 20 – 80 24, 28,
É Transverse Glulam Decks Species 32, 36
E 9
§ § Transverse Glulam Decks Any in Determined
for AASHTO 4 ft 5 – 8-3|4 by steel Wariable
Steel Beam Bridges" Or NDS beam bridge
a – Material size (i.e., face width) availability limits deck thickness. Bridge length limited by deck thickness. Bridge width varied by adding/subtracting deck laminations.
b - Glulam beam may vary from 3 to 9 in. width, but is limited to 21 in. deck thickness (i.e., beam lamination depth) due to stress—laminating concerns with a sinlge tensioning bar at
mid-height. Bridge width varied by adding|subtracting deck laminations.
c - Longitudinal panel width ranges 42–51 in. to achieve different bridge widths: 12 and 16 ft (single lane), and 24, 28, 32, and 36 ft (double lane).
d – Transverse panel width typically 4 ft; panel thickness 5-118 in. Bridge widths: 12 and 16 ft (single lane), and 24, 28, 32, and 36 ft (double lane). Bridge lengths longer than 80
ft are possible but beyond scope of these standards.
e - Transverse panel width typically 4 ft; panel thickness varies; panel length can be adjusted to match roadway width requirements.
f — Wood preservative must be compatible with wood species.
Design Considerations
With few noted exceptions, these standards were developed to comply with the American Association of State Highway and Transportation Officials (AASHTO) 1996
Standard Specifications for Highway Bridges, including 1998 Interims. In addition, these standards are based upon the Allowable Stress Design (ASD) and do not include
any provisions for Load and Resistance Factor Design (LRFD). Refer to Table B for a summary of the bridge design values used in the development of these standards.
Design Loading
Design tables include provisions for AASHTO HS20–44 and HS25–44 lane live loads. Site specific loading conditions, such as seismic and substructure bearing capacity
loads, must be determined and designed for by a qualified professional engineer. Assumed dead loads are 38 |b|ft” for asphalt wearing surface and 10 |blft” for the rail
and curb system. AASHTO also requires a unit weight of 50 |b|ft” for determining dead loads for treated timber members.
Deflection Criteria
AASHTO recommends a deflection limit of L1500 for timber bridge superstructures. Design tables for the five longitudinal deck systems include LI360 and L1500 deflection
Criteria. The larger deflection limit of L/360 is applicable and acceptable for low-volume, low-speed bridge applications, where an asphalt wearing surface would not be
used. Design tables for the beam systems are based on L1500 deflection criteria for the glulam stringers and a 0.10 inch maximum deflection for transverse glulam deck
panels.
Load Distribution
The load distribution criteria used to develop these standards complies with current AASHTO requirements. However, amore conservativeload distributionwidth was used
for nail-laminated decks to minimize delamination after prolonged service.


Table B. — Bridge Design Summary
load distribution" Design values"
Applicable F,
Superstructure Type Used for design AASHTO AASHTO table modification
reference
factors
e iº Tire width + Tire width +
Nail-laminated Decks (deck thickness) 2(deck thickness) Cu Go Cr C,
Spike-laminated Decks Tire width + 2(deck thickness) 13.5.1.A. Visually graded lumber Cu Go C C,
and timbers
**** Lumber Tire width + 2(deck thickness) Cu Go Cr Cis
Stress—laminated Giulam Decks Tire width + 2(deck thickness) l 3.53A g Members stressed e Gu Co Cw
primarily in bending about x-x axis
13.5.3B - Members stressed
longitudinal Glulam Decks Based on AASHTO load fraction method primarily in axial tension or Cu Go Cº
compression about y-y axis
Glulam Stringer with C (15 + tº < panel width Designer does not need to determine member sizes
Transverse Glulam Decks
Transverse Glulam Decks for Steel e 13538. Members stressed
. . C (15 + tº < panel width primarily in axial tension or Cu Go Cº
Beam Bridges º e
compression about y-y axis
a — Load distribution criteria meets AASHTO, except nail-laminated decks, where a more conservative approach is intended; t - deck thickness; see AASHTO 3.30 for tire width
definition.
b - See AASHTO andlor NDS for more information on modification factors: Cw - wet service factor; Co - load duration factor, Cº - bending size factor: C, - repetitive member
factor: Cis-load sharing factor: C, - volume factor, F, - tabulated bending stress (blin').
c - Transverse decks are designed as non-interconnected; see AASHTO for additional information on interconnected transverse decks using steel dowels.
Tabulated Design Values
Tabulated design values are typically found in the AASHTO tables listed in Table B. Additional design values may be found in the following sources: For sawn lumber, the
latest edition of the NDS. For glulam, the latest editions of A/TC 11793 Design Values/Specifications should be used for softwoods and A/TC 119.96 Standard
Specifications for Structural Glued laminated Timber of Hardwood Species should be used for hardwoods.
Modification of Tabulated Design Values
Most design errors occur when the designer incorrectly applies modification factors to tabulated bending strength (F) design values. Therefore, to assist the designer, the
appropriate modifications factors for Fh are listed in Table B for each superstructure type. Modification factors are further defined as follows:
CM Wet service factor Applies to all Fb and E values. AASHTO requires that timber bridge superstructures be designed for wet service
conditions, unless dry service conditions are met (for sawn lumber, see footnotes to AASHTO Table 13.5.1A; and for
softwood glulam, see footnotes to AASHTO Table 13.5.3A). For sawn lumber, dry service conditions are met when
the maximum moisture content in-service is less than 19 percent. For glulam, dry service conditions are met when
the maximum moisture content in-service is less than 16 percent. Typically, dry service conditions only apply to
glulam stringers in the Glulam Stringer with Transverse Glulam Decks system, glulam stiffener beams, and covered
bridge applications.
CD Load duration factor Applies to all Fb values. For vehicle live loads, use CD - 1.15 for all bridge types.
CF Bending size factor Applies to sawn lumber (excluding Southern Pine) 2 to 4 inches thick and to glulam panels where the load is applied
parallel to the wide face of the laminations. See footnotes to AASHTO Table 13.5.1.A.
C, Repetitive member factor Applies to sawn lumber, 2 to 4 inches thick. Use C, - 1.15 for nail- and spike-laminated decks only.
Cls Loadsharing factor
systems. Use Cls - 1.50 (for grades No. 1 and No. 2) and Cls - 1.30 (for select structural grades) for the
Stress–Laminated Sawn Lumber Decks system only. (Refer to AASHTO Guide Specification)
Cy Volume factor Applies to glulam members when the load is applied perpendicular to the wide face of the laminations. This applies
Only to the Stress-Laminated Glulam Decks system, see AASHTO 13.6.4.3.
Member Sizes
The dimensioning of sawn lumber and glulam members can be confusing. The following information is provided to clarify the difference between nominal and net (actual)
dimensions of sawn lumber and glulam members.
Sawn Lumber
Fully dressed, or surfaced on all four sides (S4S), lumber has been planed on all four surfaces. Rough sawn refers to lumber which has not been planed, or
surfaced.
-- tº--
= i
º | Dimensions of sawn lumber deck laminations"
p1 W Surface condition | Thickness, t (in.) Face width, W (in.)
2 |
Ø ſº
% Nominal or 2 4 || 8 10 12 14 16
(4 rough sawn
Sawn lumber Fully dressed (S4S) | 1.1|2 3-1/2 || 7-1|4 9-114 11.1|4 13.114 15-1|4
lamination a – These dimensions apply to sawn lumber used in Nail-, Spike-, and
To compensate for improved load distribution characteristics of Stress–Laminated Decks over Nail-Laminated Decks
Glulam
Glulam bending members are designed differently depending on whether the loads
---W-- causing the bending are applied perpendicular to the wide face of the laminations (as
- l is the case with beams and stringers) or loads are applied parallel to the wide face of
! the laminations (as is the case with transverse and longitudinal deck panels). Glulam
D bending members are specified using different combination symbol tables.
| Beams and stringers are designed using bending combinations that use higher quality
--- laminations in the high tension and compression zones. Beams and stringers are
Glulam beam generally chosen from tables for “Members Stressed Primarily in Bending" (AASHTO
13.5.3A or NDS 5A). Transverse and longitudinal deck panels are designed using
bending combinations in which all laminations have the same strength and stiffness.
Although they are designed forbending, transverse and longitudinal panels are generally
chosen from tables for "Members Stressed Primarily in Axial Tension or Compression"
(AASHTO 13.5.3B or NDS5.B). The reason for this apparent contradiction is that the
deck panels must have consistent strength and stiffness characteristics across their
entire width.
-— Y
------ 4 ft (typical) -----
Glulam panel As stringer width and/or depth of glulam deck panels increases, the use of multiple
piece laminations may become an economical Option. Edge gluing of multiple piece
laminations is recommended for all face laminations.

Net finished dimensions of glulam members
Width (W) Depth (D)
Nominal No. of laminations"
dimension
(in.) 3 4 6 8 10 12 14 16 18 8 9 10 11 12 13 14
Western species Western species
N
nº. 2-1/8 3-118 5-118 6-3|4 8-3/4 10-3|4 12-1/4 14-1|4 16-1/4 | 12 13-1|2 15 16-112 18 19.1/2 –
dimension
Southern Pine Southern Pine
(in.)
g- 3 5 6-3|4 8-1/2 12-3|8 13.3|4 15-118 16.1|2 17-718 19-1|4
a – Actual lamination thickness is 1-1/2 in. for western species and 1-3/8 in. for Southern Pine (fabricators will usually provide either lamination size)
10-1|2 12-1|4 14-1|4 16.1|4 || –
Moisture Content
AASHTO recommends a maximum moisture content of 19 percent for all sawn lumber and glulam members at installation. Drying sawn lumber members to a 19—percent
maximum moisture content is often not enforced by bridge owners, even when it is clearly specified in the contract drawings. As sawn lumber dries in-service, shrinkage
of wood members can cause loosening of connections. When using waterborne preservatives, it is important to re-dry members to a 19-percent maximum moisture content
after the preservative treatment process.
Crash-Tested Rail Systems
Crash-tested bridge railings meeting NCHRP Report 350 are required at many sites but are not included as part of these standards. Crash—tested designs can be found
in the following references: for longitudinal decks, see Ritter et al.(1995); for transverse decks, see Ritter et al.(In Press); for low-volume roads applications for longitudinal
decks, see Ritter et al. (1998).
Camber
A positive Camber, equal to three times the deadload deflection but not less than % inch, should be introduced into the following superstructure systems: Stress–Laminated

Glulam Decks, Glulam Stringer and Transverse Glulam Decks, and Stress–Laminated Sawn Lumber Decks (with butt—joints). It is important to position the topside (which
Stress—laminated Decks systems.
is usually marked) up when placing glulam stringers.
Longitudinal Deck Systems:
Nail-Laminated Decks
imTiº
The bridge superstructures depicted on these drawings were
developed under a cooperative research agreement between
the Federal Highway Administration, the USDA Forest Service,
Nail-Laminated Decks
Title Page
§
©



Forest Products Laboratory, and Laminated Concepts, Inc.
Sheet 1 of 4
*::: cº sº
December 2000
Standard Plans for Timber Bridge Superstructures
Plan, Profile, and Section Views
|
|
Weoring
surfoce,
see Note 9.
Width
L=Bridge spon meosured
c–c of bearings
Length=Bridge length measured
Bridge roiling,
Deck thickness, t, see Note 8.
see Sheet 4 of 4.
[-- Width |
out-out
Width=Bridge width measured
out-out
Substructure shown for
illustrotion only,
see Note 6.
General Notes
DESIGN
1. These drawings are for longitudinal nail-laminated timber bridge decks. The decks consist of a
series of nominal 2-in. dimension lumber laminations that are placed on edge and nailed together on
their wide faces to form a continuous deck. Lumber laminations shall be continuous (full length)
between supports with no butt—joints. The designs are applicable for single- and double-lane and
unskewed and skewed bridges up to 28 ft long. Design truck loading is AASHTO HS 20–44 or HS
25–44, with live load deflection limits of L/360 or L1500.
2. Nail-laminated timber bridge decks are well suited to low-volume road applications. They are less
suitable for high-volume applications where the repetitive traffic loads may cause the nails to loosen,
resulting in lamination movement and excessive asphalt pavement cracking.
3. The designs comply with the 1996 Standard Specifications for Highway Bridges, with 1998
Interims, published by the American Association of State Highway and Transportation Officials
(AASHTO), except where noted. Load distribution widths are assumed to be the width of the tire (as
defined by AASHTO) plus the deck thickness.
4. Minimum required timber design values are provided for single-span bridge lengths of 10 to 28 ft
in 2—ft increments. The required minimum deck thickness for a specific bridge length can be selected
from the table on Sheet 4 of 4, based on material, loading, and deflection
5.Bridge width is variable by adjusting the number of lumber laminations.
6. The design assumes a uniform bearing length of 12-in. at both bridge ends and a span length, L,
measured center-to-center of bearings. A longer bearing length will result in a slightly more
conservative design. Substructure connection details are provided on Page 34.
7. Multiple span bridges may be constructed using a series of simple spans based on the designs
presented in these drawings. Multiple span continuous bridges are also commonly used and may be
more economical but require site specific design. Refer to Page 34 for intermediate support
connection details for both simple and continuous spans.
8. Bridge rail and curb drawings are for illustration purposes only and must be designed based on site
specific requirements. Deck designs are based on an assumed dead load of 10 lb/ft’ for the rail and
curb system. Crashworthy rail designs are available in Plans for Crash. Tested Bridge Railings for
longitudinal Wood Decks (Ritter et al. 1995) and Plans for Crash-Tested Bridge Railings for
longitudinal Wood Decks on low-Volume Roads (Ritter et al. 1998).
9. An asphalt wearing surface with a geotextile fabric or membrane is recommended for most timber
bridge applications. Deck designs are based on an assumed dead load of 38 lb/ft” for an asphalt
wearing surface (approximately 3-in.). Refer to Page 53 for recommended asphalt wearing surface
construction details.
10. These designs are intended for informational purposes only and, due to potential variations in
design requirements and use conditions, should be verified by a qualified professional engineer.
MATERIAL AND FABRICATION
Wood
11. Sawn lumber shall comply with the requirements of AASHTO M168 and may be any species,
provided it is treatable with wood preservatives and tabulated design values are provided in the
AASHTO Standard Specifications for Highway Bridges. The moisture content of lumber shall not
exceed 19 percent at the time of installation.
12. Sawn lumber may be rough-sawn or dressed (S4S). Rough-sawn lumbershall be surfaced on One
side (S1S) to ensure uniform thickness for all laminations.
13. Insofar as is practical, all lumber shall be cut, drilled, and completely fabricated prior to pressure
treatment with preservatives.
Preservative Treatment
14. All lumbershall be treated in accordance with AASHTO M133 and AWPA Standard C14 with One
of the following preservatives:
a. Coal tar creosote conforming to AWPA Standard P1|P13.
b. Suitable oilborne preservative conforming to AWPA Standard P8 in hydrocarbon solvent, Type A
or Type C.
C. Suitable waterborne preservative conforming to AWPA Standard P5. Lumber treated with a
waterborne preservative shall be re-dried to a maximum moisture content of 19 percent.
15. Treated material shall follow the post treatment requirements summarized in Best Management
Practices for the Use of Treated Wood in Aquatic Environments (WWP) 1996) to ensure all surfaces
are free of excess preservative and chemicals are adequately fixated in the wood.
16. Preservative treatment shall be inspected and certified in accordance with AASHTO M133 and
AWPA Standard M2.
Steel Fasteners and Hardware
17. Steel plates and shapes shall comply with the requirements of ASTM A36.
18. Nails shall be common wire or deformed shank conforming to ASTM F1667.
19. Bolts and lag screws shall comply with the requirements of ANSI/ASMEStandard B18.2.1-1981,
Grade 2.
20. All steel components and fasteners shall be galvanized in accordance with AASHTO M111 or
AASHTO M232 or otherwise protected from corrosion.
21. Washers shall be provided underbolt and lag screw heads and under nuts that are in contact with
wood. Washers may be omitted under heads of special timber bolts or dome-head bolts when the
size and strength of the head is sufficient to develop connection strength without wood crushing.
CONSTRUCTION
22. Decks may be assembled by placing laminations on edge and nailing them together along the wide
faces, in accordance with the procedures and nailing patterns given on Sheet 3 of 4.
23. All wood and metal components shall be handled and stored carefully so as not to damage the
material. If damage does occur, exposed untreated wood shall be field treated in accordance with
AASHTO M133. Damage to galvanized surfaces shall be repaired with a cold galvanizing compound
Or other approved coating.
24. The application of a bituminous sealer is recommended to prevent excessive wood checking in
areas where the wood end grain is exposed. Any commercially available roofing cement is effective.
The bridge superstructures depicted on these drawings were
developed under a cooperative research agreement between
the Federal Highway Administration, the USDA Forest Service,
Nail-Laminated Decks
Superstructure Drawings and General Notes






Forest Products Laboratory, and Laminated Concepts, Inc.
December 2000 Sheet 2 of 4
Standard Plans for Timber Bridge Superstructures
Lamination Nail Pattern - Unskewed Crossing
Lominotion Plocenent
Plon View
cº 10–1/2" 18" 6" 18"
18 - | | | H |
t t 1-1/2" t
O O O .-- (typical) O O
| |
FF 18" 18" T 15" 18"
Lominotion 1 Lorminotion 2 Lominotion 3
Side View Side View Side View
Lamination Nailing Pattern-Skewed Crossing
Skew ongle
End of _2^
II J
| 3 Z
| 2 I
| | 1 \
J
| | [? \
b | 1 T)
T-
Lominotion Plocennent
Plon View
O_1 | 18" | | 10-1/2" | 18" |
H | | — a
| • | © O
| t |
| 1-1/2"
| O O A-l- H (typical)
| End of- co
' 10-1/2" 18" lominotion 3 18
lominotion 2
Lominotion 1
Lorminotion 2
Z!
o = b " ton (skew angle)
where o is the offset distonce, in.
b is the octuol lorninotion thickness, in.
to 6" 18” |
T |
|
t
| O O
|
End of F- tºº tºº
lominotion 1 15 18
Lorninotion 3
Notes
1. Nail-laminated timber bridge decks are constructed by sequentially nailing laminations together on their wide
faces until the required deck width is achieved. The mailing involves a repetitive series of three laminations,
as detailed on this sheet.
2. When beginning construction, at least three laminations should be nailed together and attached to the
substructure along one bridge edge. The remaining laminations are then sequentially nailed to the interior face
of this lamination group.
3. Nails should be placed approximately 1-1/2 in. from the lamination edges and ends. Interior nail spacing
is typically 18-in. but may be reduced to fit the bridge length.
4. Nails shall be of sufficient length to penetrate at least 2-1/2 laminations and may be common wire or
deformed shank nails. Deformed shank nails, such as ring-shank or spiral decking nails, are recommended
because they provide increased resistance to withdrawal and improved long-term deck performance. Nails
should be galvanized or otherwise protected from corrosion, particularly if the wood is not treated with an
Oilborne preservative (the oil solvents coat and provide some protection of steel components).
5. Nails may be installed manually or placed with a pneumatic gun. If lamination splitting occurs during nail
placement, lead holes shall be prebored. Prebore diameters shall not exceed three-quarters of the nail shank
diameter.
Deformed shank nails
|ESSSSSSSSSSSSSSS- |TImE
Spiral decking or helically threaded Ring shank or annular threaded
Table 1.1 — Recommended nail sizes for 2-in. deck laminations.
Deck laminations Recommended nails
Nominal Actual º
thickness Suſat e thickness Size len gth Diameter
e condition e (in.) (in.)
(in.) (in.)
S4S 1.5 200 4.0 0.177
2
Rough-sawn 2.0 40d 5.0 0.177
S4S-surfaced four sides; d-pennyweight.
Side View Side View Side View
The bridge superstructures depicted on these drawings were of 7 il- O O o
under a ag ſº Nail-Laminated Decks Nailing Specifications


the Federal Highway Administration, the USDA Forest Service, % C2;
Forest Products Laboratory, and Laminated Concepts, Inc. °sº
Standard Plans for Timber Bridge Superstructures December 2000 Sheet 3 of 4
Table 1.2 – Nail-Laminated Deck Design Table
Bridge || Span AASHTO HS20–44 Loading
Length L
(ft) (ft)
Required
Walue
8 9% 10 || 11% | 12 || 13% 14 || 15%
F.' 1,523 | 1,097 || 918
E' for L/360 || 1.17 0.73 0.56
E' for 1.63 1.01 0.78
F.' 1,882 | 1,357 | 1,137
E’ for LI360 || 1.75 1.08 0.84
E’ for 1.51 1.16
F.' 1,623 | 1,361
E' for L/360 1.51 1.17
E’ for 1.62
F.' 1,590
E' for L/360 1.56
E' for
F.' 1,825
E’ for LI360 2.00
E' for
F.'
E’ for L/360
E’ for
F.'
E" for L/360
E’ for
F.'
E’ for LI360
E’ for L1500
F.'
E’ for L/360
E' for L1500
F.'
E' for L/360
E' for L1500
a — Rough sawn sizes are 8, 10, 12, 14, and 16-in.;
dressed sizes are 9%, 11%, 13%, and 15%—in.
16
8
1,744
1.35
1.88
9%
1,259
0.84
1.17
1,555
1.25
1.74
1,858
1.75
AASHTO HS25–44 Loading
10
1,055
0.65
0.90
1,305
0.97
1.35
1,559
1.35
1.88
1,819
1.80
Minimum Required F.' (lblin") and E’ (x10°lblin’) Walues for Actual Deck Thickness"(t) ranging from 8 to 16-in.
11% | 12 || 13% | 14 | 15% | 16
817
0.60
0.83
917
0.73
1.01
1,020
0.97
1.35
1,158
1.27
1.77
1,481 | 1,329
1.89 || 1.60
Table instructions
The table on this sheet is for determining the required deck thickness for longitudinal nail-laminated timber bridge
decks. The criteria for deck thickness selection are based on the span length, vehicle loading, live load deflection
limit, and material properties for the grade and species of lumber. The table provides the minimum required
allowable design values for bending strength (F,') and modulus of elasticity (E'), based on the vehicle live load, deck
deadload, and an assumed deadload of 10 lb/ft for the railing|Curb and 38 lblft’ for the asphalt wearing surface.
Allowable design values for horizontal shear (F,') are not listed because horizontal shear is not critical for shallow
deck sections. Blank cells in the table denote cases where the required design walues exceed those typically
available or that result in excessively conservative designs.
The table may be used in two ways. When the grade and species of the lumber are known, the designer must
determine the allowable design values for the material, then compare them to the values given in the table. The
allowable design values must be greater than or equal to the table values based on the selected deck thickness,
span length, vehicle loading, and deflection limit. Alternatively, when the material grade and species are unknown,
minimum required F, and E' values may be obtained from the table based on the span length, deck thickness,
loading, and deflection limit. A grade and species of lumber that meets these minimum allowable design walues may
then be selected. Specific procedures for table use follow:
Material Grade and Species Known
1. Determine the required design criteria for
a. span length measured Center-to-center of bearings;
b. vehicle loading, AASHTO HS20–44 or HS25–44; and
C. live load deflection limit, L/360 or L1500.
2. Compute the allowable design walues for the grade and species of lumber lamination using the following
equations:
F, - F. Cu CF Co C, E" - ECM
where
F, - allowable bending stress (blin’) Cu - wet service factor
F, - tabulated bending stress (blin’) Cº - size factor
E' - allowable modulus of elasticity (blin’) Co - load duration factor
E - tabulated modulus of elasticity (lblin’) C. - repetitive member factor
3. Enter the table and select a deck thickness based on the design criteria and allowable material properties
previously determined. The allowable material property values for F, and E' must be greater than or equal to the
corresponding table values for the deck thickness selected. If not, the design criteria and/or material properties
must be revised until acceptable values are achieved.
Material Grade and Species Unknown
1. Determine the required design criteria for
a. span length measured center-to-center of bearings;
b. vehicle loading, AASHTO HS20–44 or HS25–44; and
C. live load deflection limit, L/360 or L1500.
2. Enter the table and select a deck thickness based on the design criteria. Note the required minimum allowable
design walues for F, and E'.
3. Select a grade and species of dimension lumber that provides the minimum allowable design values.
The bridge superstructures depicted on these drawings were *
developed under a cooperative research agreement between ſº
the Federal Highway Administration, the USDA Forest Service,
Nail-Laminated Decks Deck Design Table



Forest Products Laboratory, and Laminated Concepts, Inc.
Standard Plans for Timber Bridge Superstructures December 2000 Sheet 4 of 4
Longitudinal Deck Systems:
Spike-Laminated Decks
TITLETILILLILITITITTTTTTTTTTTTTT
The bridge superstructures depicted on these drawings were º Spike-Lamin ated Decks Title Page
developed under a cooperative research agreement between ſ DY,
the Federal Highway Administration, the USDA Forest Service, i. 37


Forest Products Laboratory, and Laminated Concepts, Inc. *:::: Standard Plans for Timber Bridge Superstructures December 2000 Sheet 1 of 4
Plan, Profile, and Section Views
|
Ponel Width
Weoring
surface,
see Note 9.
H. Length —º-
Stiffener beam (glulom
or steel), see Sheet 3 of 4
see Sheet 4 of 4.
Bridge roiling,
see Note 8. \g
IX Deck thickness, t,
Width
L=Bridge spon meosured
c–c of bearings
Length=Bridge length measured
i
|
IIII
WTW
Width
Out-out
Width=Bridge width measured
out-out
Substructure shown for
illustrotion only,
see Note 6.
General Notes
DESIGN
1. These drawings are for longitudinal spike-laminated timber bridge decks. The decks consist
of a series of nominal 4—in. dimension lumber laminations that are prefabricated into a series of
partial-width deck panels. The panels are placed side-by-side between supports and
interconnected with transverse stiffener beams. Lumber laminations shall be continuous (full
length) between supports with no butt—joints. The designs are applicable for single- and
double-lane and unskewed and skewed bridges up to 34 ft long. Design truck loading is AASHTO
HS 20–44 Or HS 25–44, with live load deflection limits of L/360 or L1500.
2. Deck panels shall be prefabricated at a manufacturing facility by placing spikes with a hydraulic
press into prebored holes as specified in Timber Bridges: Design, Construction, Inspection, and
Maintenance (Ritter, 1990).
3. The designs comply with the 1996 AASHTO Standard Specifications for Highway Bridges,
with 1998 Interims, published by the American Association of State Highway and Transportation
Officials (AASHTO), except where noted. Load distribution widths are assumed to be the width
of the tire (as defined by AASHTO) plus twice the deck thickness.
4. Minimum required timber design values are provided for single span bridge lengths of 12 to 34
ft in 2—ft increments. The required minimum deck thickness for a specific bridge length can be
selected from the table On Sheet 4 of 4, based on material, loading, and deflection.
5. Bridge width is variable by adjusting the width of the deck panels.
6. The design assumes a uniform bearing length of 12 in. at both bridge ends and a span length,
L, measured center-to-center of bearings. A longer bearing length will result in a slightly more
conservative design. Substructure connection details are provided on Page 34.
7. Multiple span bridges may be constructed using a series of simple spans based on the designs
presented in these drawings. Multiple span continuous bridges are also commonly used and may
be more economical but require site-specific design. Refer to Page 34 for intermediate support
connection details for both simple and continuous spans.
8. Bridge rail and curb drawings are for illustration purposes only and must be designed based on
site specific requirements. Deck designs are based on an assumed dead load of 10 lb/ft’ for the
rail and curb system. Crashworthy rail designs are available in Plans for Crash-Tested Bridge
Railings for longitudinal Wood Decks (Ritter et al. 1995) and Plans for Crash—Tested Bridge
Railings for longitudinal Wood Decks on low-Volume Roads (Ritter et al. 1998).
9. An asphalt wearing surface with a geotextile fabric or membrane is recommended for most
timber bridge applications. Deck designs are based on an assumed dead load of 38 lb/ft’ for an
asphalt wearing surface (approximately 3 in.). Refer to Page 53 for recommended asphalt
wearing surface construction details.
10. These designs are intended for informational purposes Only and, due to potential variations
in design requirements and use conditions, should be verified by a qualified professional engineer.
MATERIAL AND FABRICATION
Wood
11. Sawn lumber shall comply with the requirements of AASHTO M168 and may be any species,
provided it is treatable with wood preservatives and tabulated design values are provided in the
AASHTO Standard Specifications for Highway Bridges.
12. Sawn lumber may be rough sawn or dressed (S4S). Rough-sawn lumber shall be surfaced
On One side (S1S) to ensure uniform thickness for all laminations.
13. Insofar as is practical, all wood members shall be cut, drilled, and otherwise fabricated prior
to pressure treatment with wood preservatives.
Preservative Treatment
14. All lumber shall be treated in accordance with AASHTO M133 and AWPA Standard C14 with
One of the following preservatives:
a. Coal tar creosote conforming to AWPA Standard P1|P13.
b. Suitable oilborne preservative conforming to AWPA Standard P8 in hydrocarbon solvent, Type
A or Type C.
c. Suitable waterborne preservative conforming to AWPA Standard P.5. Lumber treated with a
waterborne preservative shall be re-dried to a maximum moisture content of 19 percent.
15. Treated material shall followpost treatment requirements summarized in Best Management
Practices for the Use of Treated Wood in Aquatic Environments (WWPI 1996) to ensure all
surfaces are free of excess preservative and chemicals are fixated in the wood.
Steel Fasteners and Hardware
16. Steel components shall comply with the requirements of ASTM A36.
17. Spikes shall be common wire or deformed shank conforming to ASTM 1667.
18. Bolts and lag screws shall comply with the requirements of ANSI/ASME Standard B18.2.1-
1981, Grade 2.
19. All steel components and fasteners shall be galvanized in accordance with AASHTO M111
or AASHTO M232, or otherwise protected from corrosion.
20. Washers shall be provided under bolt and lag screw heads and under nuts that are in contact
with wood. Washers may be omitted under heads of special timber bolts or dome-head bolts
when the size and strength of the head is sufficient to develop connection strength without wood
Crushing.
CONSTRUCTION
21. Deck panels shall be interconnected with transverse stiffener beams as shown on Sheet 3
of 4.
22. All wood and metal components shall be handled and stored carefully so as not to damage
the material. If damage does occur, exposed untreated wood shall be field treated in accordance
with AASHTO M133. Damage to galvanized surfaces shall be repaired with a cold galvanizing
Compound or other approved coating.
23. The application of a bituminous sealer is recommended to prevent excessive wood checking
in areas where the wood end grain is exposed. Wertical joint surfaces, between deck panels, may
also be coated to minimize moisture penetration. Any commercially available roofing cement is
effective.
The bridge superstructures depicted on these drawings were
developed under a cooperative research agreement between
the Federal Highway Administration, the USDA Forest Service,
Forest Products Laboratory, and Laminated Concepts, Inc.
*S*
@
*Arts of
Spike-Laminated Decks
Superstructure Drawings and General Notes
Standard Plans for Timber Bridge Superstructures
December 2000 Sheet 2 of 4






Deck Panel and Transverse Stiffener Beam Layout
3/4 in. Ø dome heod *N
deck | deck
| |
3/4 in. Ø dome heod *N
||
|
|
Cut – N- Steel stiffener Beorn
ond nut see Note 2.
ond nut
Transverse Stiffener Beam Connection - Steel Channel
Molledble iron ~~/
II
||
Fº-TS- Glulon stiffener bedn,
see Note 2.
Transverse Stiffener Beam Connection - Giulam Beam
Side View
Notes
1. Transverse stiffener beams shall be attached to the deck underside to transfer loads between adjacent panels.
Transverse stiffener beams are placed at midspan and at intermediate locations, while not exceeding a 10-ft
spacing (see Table 2.1). For unskewed crossings, stiffener beams shall be placed perpendicular to the bridge
span. For skewed crossings, stiffener beams shall be placed parallel to the abutments.
2. Transverse stiffener beams shall be manufactured of glulam or steel. For western species glulam, a
Combination Symbol No. 2 beam measuring 6-3/4-in. wide and 4-1/2-in. deep may be used. For southern pine
glulam, a Combination Symbol No. 48 beam measuring 5-in. wide and 5-1/2-in. deep may be used. For steel,
a miscellaneous channel (MC6x15.1) beam may be used. Other glulam combinations or steel shapes may be used
provided they are of sufficient size and stiffness to provide a minimum E'l of 80,000 lb-in'.
3. Transverse stiffener beams shall be attached to the deck panels with 3/4-in.-diameter thru-bolts placed
approximately 6-in. from the panel edges. For the exterior panels, the stiffener beam shall extend a minimum
of 18-in. beyond the panel interface.
Bridge Length
S S S S
T ſ T gº
Iol 191 191 18
'o' 'o' ſo
| | | | |
| | |
É- É. É. |
O O O
gº | | | | | &
Width | | | | | | Ponel width
É. | Hr É.
O 6" O O
| Tº |
| | | |
É. É. É
'o O O 00
L L & I is
Side View
Table 2.1 - Transverse Stiffener Layout
Bridge
Length S
| Bridge Length | (ft) N0. (ft)
| S i S f S ſº S | 12 1 6.0
| | | 14 1 7.0
Sk
eW | | | 16 1 8.0
| Q Q 18 18 1 9.0
lol lol lol
| | | | | | 20 3 5.0
| | | | | |
O O
# f # f # 22 3 5.5
Width | | | | 24 3 6.0
= *—# 26 3 6.5
| | | 28 3 7.0
| | | | { }
Iol Iol
o' 'o' 8." 30 3 7.5
1
|J [] 32 3 8.0
1— 34 3 8.5
Transverse Stiffener Beam - Unskewed Crossings
Plan View
Transverse Stiffener Beam - Skewed Crossings
Plan Wow
S = transverse stiffener beam spacing
The bridge superstructures depicted on these drawings were
developed under a cooperative research agreement between
the Federal Highway Administration, the USDA Forest Service,
Forest Products Laboratory, and Laminated Concepts, Inc.
@
Spike-Laminated Decks
Deck Panel and Stiffener Beam Configuration
Standard Plans for Timber Bridge Superstructures
December 2000
Sheet 3 of 4


10
Table 2.2 – Spike-Laminated Deck Design Table
AASHTO HS20–44 Loading
Bridge || Span
Length L
(ft) (ft)
Required tº tº ſº º wº g e g
º Minimum Required F," (lblin’) and E’ (x10°lblin’) Walues For Actual Deck Thickness” (t) Walues Ranging from 8 to 16-in.
9% 10 11%
F.' 1,053 873
E' for L/360 0.82 0.63
E' for 1.14 || 0.87
F.' 1,264 | 1,049
E’ for L/360 1.15 0.88
E’ for 1.60 1.22
F.' 1,481 | 1,230
E' for LI360 1.53 1.17
E’ for 1.62
F.' 1,704 || 1,417
E' for L/360 1.97 1.50
E’ for
F.' 1,609
E' for L/360 1.87
E’ for
F.'
E’ for LI360
E' for
F.'
E’ for L/360
E’ for
F.'
E' for L/360
E' for
F.'
E" for L/360
E' for
F.'
E' for L/360
E' for
F.'
E’ for L/360
E' for
F.'
E' for L/360
E' for
34 33
12
13%
14 15%
673
0.51
0.71
753
0.68
0.95
859
0.89
1.24
988
1.13
1.56
1,120
1.38
1.91
1,255
1.65
1,395
1.94
a – Rough-sawn sizes are 8, 10, 12, 14, and 16-in. and dressed sizes are 9%, 11%, 13%, and 15%—in.
16
602
0.43
0.60
675
0.57
0.80
770
0.75
1.04
885
0.95
1.31
1,003
1.16
1.61
1,125
1.39
1.92
1,251
1.63
8
1,727
1.60
9%
1,223
0.97
1.35
1,465
1.36
1.88
1,713
1.80
AASHTO HS25–44 Loading
10
1,015
0.74
1.03
1,217
1.03
1.44
1,424
1.38
1.91
1,637
1.77
11%
765
0.49
0.68
918
0.69
0.95
1,076
0.91
1.27
1,239
0.17
1.63
1,406
1.47
1,577
1.79
12
13%
14
15%
16
Table Instructions
The table on this sheet is for determining the required deck thickness for spike-laminated timber bridge decks. The
criteria for deck thickness selection are based on the span length, vehicle loading, live load deflection limit, and material
properties for the grade and species of lumber. The table provides the minimum required allowable design walues for
bending strength (F,') and modulus of elasticity (E'), based on the vehicle live load, deck dead load, and an assumed dead
load of 10 lb/ft’ for the railing|Curb and 38 lb/ft’ for the asphalt wearing surface. Allowable design values for horizontal
shear (F,') are not listed because horizontal shear is not critical for shallow deck sections. Blank cells in the table denote
cases where the required design walues exceed those typically available or that result in excessively conservative designs.
The table may be used in two ways. When the grade and species of the lumber are known, the designer must determine
the allowable design walues for the material, then compare them to the values given in the table. The allowable design
walues must be greater than or equal to the table walues based on the selected deck thickness, span length, vehicle
loading, and deflection limit. Alternatively, when thematerial grade and species are unknown, minimum required F, and
E' walues may be obtained from the table based on the span length, deck thickness, loading, and deflection limit. A grade
and species of lumber that meets these minimum allowable design walues may then be selected. Specific procedures for
table use follow:
Material Grade and Species Known
1. Determine the required design criteria for
a. span length measured center-to-center of bearings;
b. vehicle loading, AASHTO HS20–44 or HS25–44; and
C. live load deflection limit, L/360 or L1500.
2. Compute the allowable design walues for the grade and species of lumber lamination using the following equations:
F, - F. Cu CF Co C, E" - ECM
where
F, - allowable bending stress (blin') Cu - wet service factor
F, - tabulated bending stress (blin’) Cº - size factor
E' - allowable modulus of elasticity (lblin’) Co - load duration factor
E - tabulated modulus of elasticity (blin’ C. - repetitive member factor
3. Enter the table and select a deck thickness based on the design criteria and allowable material properties previously
determined. The allowable material property values for F, and E' must be greater than or equal to the corresponding
table values for the deck thickness selected. If not, the design criteria and/or material properties must be revised until
acceptable values are achieved.
Material Grade and Species Unknown
1. Determine the required design criteria for
a. span length measured center-to-center of bearings;
b. vehicle loading, AASHTO HS20–44 or HS25–44; and
C. live load deflection limit, L/360 or L1500.
2. Enter the table and select a deck thickness based on the design criteria. Note the required minimum allowable design
values for F, and E'.
3. Select a grade and species of dimension lumber that provides the minimum allowable design walues.
The bridge superstructures depicted on these drawings were
developed under a cooperative research agreement between
the Federal Highway Administration, the USDA Forest Service,
Forest Products Laboratory, and Laminated Concepts, Inc.
@
*Parº of
Spike-Laminated Decks
Deck Design Table
Standard Plans for Timber Bridge Superstructures
December 2000 Sheet 4 of 4


11
Longitudinal Deck Systems:
StreSS-Laminated Sawn Lumber Decks
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|
The bridge superstructures depicted on these drawings were º Stress-Laminated Sawn Lumber Decks Title Page
developed under a cooperative research agreement between %
the Federal Highway Administration, the USDA Forest Service, *. 37
Forest Products Laboratory, and Laminated Concepts, Inc. *::::= Standard Plans for Timber Bridge Superstructures December 2000 Sheet 1 of 9


12
Plan, Profile, and Section Views
High-strength
steel bor,
see Note 8.
Butt-joints,
see Note 9.
Wearing surfoce,
see Note 1 1.
I- Length
TX
Deck thickness, t,
see Note 5.
Bridge roiling,
see Note 1 O.
H
HH
HHHHHHHHHH
Width
Width
L=Bridge spon meosured
c–c of bearings
Length=Bridge length measured
out-out
Width=Bridge width measured
out-out
Substructure shown for
illustration only, see
Note 5.
General Notes
DESIGN
1. These drawings are for longitudinal stress-laminated timber bridge decks. The decks consist of a series of nominal
2- to 4-in-thick sawn lumber laminations that are placed on edge between supports and transversely compressed
with high-strength steelbars. Deck laminations of various lengths may be placed in a repetitive butt joint pattern when
full-span lumber is not available. The designs are applicable for single- and double-lane and unskewed and skewed
bridges up to 34 ft long. Design truck loading is AASHTO HS 20–44 or HS 25–44, with live load deflection limits of
L/360 Or L1500.
2. The designs comply with the 1996 Standard Specifications for Highway Bridges, with 1998 Interims, and the 1991
Guide Specifications for the Design of Stress-laminated Wood Decks, published by the American Association of State
Highway and Transportation Officials (AASHTO), except where noted. Load distribution widths are assumed to be the
width of the tire (as defined by AASHTO) plus twice the deck thickness and have been adjusted by a factor of 1.15
for deflection calculations. The designs are based upon an interlaminar prestress of 100 lblin’ which has been shown
to provide Optimum field performance.
3. Minimum required timber design values are provided for single-span bridge lengths of 10 to 34 ft in 2-ft increments.
The required minimum deck thickness for a specific bridgelength can be selected from tables on Sheet 6 of 9 and Sheet
8 of 9, based on material, loading, and deflection.
4. Bridge width is variable by adjusting the number of lumber laminations.
5. The design assumes a uniform bearing length of 12-in. at both bridge ends and a span length, L, measured
center-to-center of bearings. A longer bearing length will result in a slightly more conservative design. Substructure
connection details are provided on Page 34.
6. Multiple span bridges may be constructed using a series of simple spans based on the designs presented in these
drawings. Multiple span continuous bridges are also commonly used and may be more economical but require
site-specific design. Refer to Page 34 for intermediate support connection details for both simple and continuous
SpanS.
7. Skewed crossings are limited to 15° maximum by AASHTO. Refer to Sheet 4 of 9 for information regarding design
considerations and stressing bar layout for skewed bridges.
8. High-strength steel bars are nominal 518 or 1 in. diameter. The diameter and spacing of bars depends on the deck
thickness and span as shown on Sheet 5 of 9 and Sheet 7 of 9.
9. Butt joints are permitted for longer spans as shown on Sheet 7 of 9. Butt—joints are limited transversely to 1 joint
in every 4 adjacent laminations and are spaced 4-ft longitudinally.
10. Bridge rail and curb drawings are for illustration purposes only and must be designed based on site-specific
requirements. Deck designs are based on an assumed deadload of 10 lb/ft’ for the rail and curb system. Crashworthy
rail designs are available in Plans for Crash-Wested Bridge Railings for longitudinal Wood Decks (Ritter et al. 1995)
and Plans for Crash—Tested Bridge Railings for longitudinal Wood Decks on low-Volume Roads (Ritter et al. 1998).
11. An asphalt wearing surface with a geotextile fabric or membrane is recommended for most timber bridge
applications. For stress—laminated decks, the wearing surface should be installed after the first re-tensioning is
completed (see Note 25). Deck designs are based on an assumed dead load of 38 lb/ft’ for an asphalt wearing surface
(approximately 3-in.). Refer to Page 53 for recommended asphalt wearing surface construction details.
12. These designs are intended for informational purposes only and, due to potential variations in design requirements
and use conditions, should be verified by a qualified professional engineer.
MATERIAL AND FABRICATION
Wood
13. Sawn lumbershall comply with the requirements of AASHTO M168 and may be any species, provided it is treatable
with wood preservatives and tabulated design values are provided in the AASHTO Standard Specifications for Highway
Bridges. The moisture content of lumber shall not exceed 19 percent at the time of installation.
14. Sawn lumber may be rough-sawn or dressed (S4S). Rough sawn lumber shall be surfaced on One side (S1S) to
ensure uniform thickness for all laminations.
15. Insofar as is practical, all lumber shall be cut, drilled, and completely fabricated prior to pressure treatment with
wood preservatives. Refer to Sheet 5 of 9 and Sheet 7 of 9 for information on stressing bar hole layout and diameter.
Preservative Treatment
16. All lumber shall be treated in accordance with AASHTO M133 and AWPA Standard C14 with one of the following
preservatives:
a. Coal tar creosote conforming to AWPA Standard P1|P13.
b. Suitable oilborne preservative conforming to AWPA Standard P8 in hydrocarbon solvent, Type A or Type C.
C. Suitable waterborne preservative conforming to AWPA Standard P5. Lumber treated with a waterborne preservative
shall be re-dried to a maximum moisture content of 19 percent.
17. Treated material shall follow post treatment requirements summarized in Best Management Practices for the Use
of Treated Wood in Aquatic Environments (WWPl 1996) to ensure all surfaces are free of excess preservative and
chemicals are fixated in the wood.
18. Preservative treatment shall be inspected and certified in accordance with AASHTO M133 and AWPA Standard
M2.
Steel Fasteners and Hardware
19. Steel plates and shapes shall comply with the requirements of ASTM A36.
20. Stressing bars shall be 5/8 or 1-in. nominal diameter and shall comply with the requirements of ASTM A722. Order
bars at least 3-ft longer than total deck width. Nuts and couplers for stressing bars shall be provided by the bar
manufacturer and should be re-threaded, after galvanizing, to ensure proper fit.
21. Bolts and lag screws shall comply with the requirements of ANSI/ASME Standard B18.2.1–1981, Grade 2.
22. All steel components and fasteners shall be galvanized in accordance with AASHTO M111 or AASHTO M232 or
otherwise protected from corrosion. Galvanizing of stressing bars shall follow the recommendations of the bar
manufacturer so as not to adversely affect the mechanical properties of the high-strength steel.
23. Washers shall be provided underbolt and lag screw heads and under nuts that are in contact with wood. Washers
may be omitted under heads of special timber bolts or dome-head bolts when the size and strength of the head is
sufficient to develop connection strength without wood crushing.
CONSTRUCTION
24. Decks may be assembled by placing laminations on edge, side-by-side on the substructure. Temporary supports
at butt—joint locations may be required during construction. After placing all deck laminations, steel stressing bars are
inserted into prebored holes and baranchorage plates and nuts are attached. Tensioning of the high-strengthstressing
bars is typically performed with a single hydraulic jack and steel stressing chair in a repetitive manner beginning at One
end of the bridge. When initially tensioning bars, it is important that the full tension not be applied until all laminations
are aligned and in full contact with adjacent laminations. For additional information and alternative assembly methods,
refer to Recommended Construction Practices for Stress-laminated Wood Bridge Decks (Ritter and Lee 1996).
25. Stressing bars shall be fully tensioned to the values specified on Sheet 3 of 9 and Sheet 4 of 9 in accordance with
the following sequence:
1. Initially tensioned at construction.
2. Re-tensioned 1–2 weeks after the initial tensioning.
3. Re-tensioned 6–8 weeks after the first re-tensioning.
It is recommended that the bars be checked and re-tensioned as required, 1 year after construction and at 1–2 year
intervals thereafter until the bar force stabilizes above 50 percent of the design level. If excess bar length is to be
trimmed, leave a minimum of 8-in. beyond the anchor nut to allow for re-tensioning.
26. Allwood and metal components shall be handled and stored carefully so as not to damage the material. If damage
does occur, exposed untreated wood shall be field treated in accordance with AASHTO M133. Damage to galvanized
surfaces shall be repaired with a cold galvanizing compound or other approved coating.
27. The application of a bituminous sealer is recommended to prevent excessive wood checking in areas where the
wood end grain is exposed. Any commercially available roofing cement effective.
The bridge superstructures depicted on these drawings were
developed under a cooperative research agreement between
the Federal Highway Administration, the USDA Forest Service,
Forest Products Laboratory, and Laminated Concepts, Inc.
Stress-Laminated Sawn Lumber Decks
Superstructure Drawings and General Notes
Standard Plans for Timber Bridge Superstructures
December 2000 Sheet 2 of 9



13
Stressing Bar Requirements - Unskewed Bridges
Table 3.1 — Recommended Bar and End Spacings
5/8-in.-Diameter Bars 1-in.-Diameter Bars
Bridge
Length Bar Spacing, End Spacing, Bar Spacing, End Spacing,
(ft) S (ft) X (ft) S (ft) X (ft)
10
S = Bor spocing
meosured center-center. 12
X = End spocing measured from 14
bridge end to center of 1st bor.
16
See Toble 3.1 for bor spocing requirements. 8 2
1 1 1
Roodwoy Q.
20 2
22 1
24 2
26 4 1
A722 steel bor, see Note 2. 28 2
30 1
32 2
onchoroge,
see Sheet 9 of 9. 34 1
Table 3.2 — Recommended Design Bar Tension Forces
Bar Design Bar Tension Force (lb) for Actual Deck Thickness (t) Ranging from 8- to 16-in.
Diameter
(in.) 8 9% 10 11% 12 13% 14 15% 16
Notes 5|8 19,200 22,200 24,000 27,000 28,800
l =l 63,600 | 67,200 | 73,200 || 76,800
1. This sheet provides stressing bar requirements for unskewed bridges. Bar requirements for skewed bridges are given on Sheet 4 of 9.
2. All stressing bars shall be perpendicular to the longitudinal bridge centerline and conform to the requirements of ASTM A722. For a deck thickness less
than, or equal to 12-in., bar diameter is 5/8 in. For decks greater than 12 in. thick, bar diameter is 1 in.
3. Bar spacing (S) is 2-ft for 5/8-in-diameter bars and 4-ft for 1-in-diameter bars. End spacing (X) is based on bridge length and is given in Table 3.1.
Refer to Sheet 5 of 9 for layout of non-butt—jointed decks and Sheet 7 of 9 for layout of butt—jointed decks.
4. Bar tension force is based on deck thickness and bar spacing. Bars shall be tensioned, in multiple passes, to the design bar tension force specified in
Table 3.2. Bars shall be re-tensioned as specified in Note 25, Sheet 2 of 9.
The bridge superstructures depicted on these drawings were
developed under a cooperative research agreement between
the Federal Highway Administration, the USDA Forest Service,
Stress-Laminated Sawn Lumber Decks
Stressing Bar Requirements - Unskewed Bridges


Forest Products Laboratory, and Laminated Concepts, Inc.
Sheet 3 of 9
Standard Plans for Timber Bridge Superstructures
December 2000
Stressing Bar Requirements - Skewed Bridges
X S
Pi—-tº-
S = Bor spocing
meosured center-center
X = End spocing measured from
end of bridge to center of 1st bor.
See Toble 3.3 for bor spocing requirements.
Table 3.3 — Recommended Bar and End Spacings
| |
| | | | | |
| | | | | |
| | | | | |
| | | | | |
| | | | | | 5|8-in.-Diameter Bars 1-in.-Diameter Bars
t—s | | | | | Bridge e g
ITI I HºN | Length Bar Spacing, End Spacing, Bar Spacing, End Spacing,
Roodwoy Q. I I HMS | | | | (ft) S (ft) X (ft) S (ft) X (ft)
A-H E-R-I – | I |
skew I I | | N. | | | | | 10
ongle H | I I I \
-H | ETTY | | | | | 12
I | \
I I I I HA | | | |
I I I I TV
H | | f H | | | 14
I | i i i –Y Interior bor onchorage, see Sheet 9 of 9.
| | I I I =| | | | | 16
| Fă | | |
I | | I I IV | | | | 18 2 1 1
H I . H
H ; | ! | H | | | ASTM A722 steel bor, see Note 2. 20 2
22 1
24 2
Typical bor onchoroge,
see Sheet 9 of 9. 26 4 1
28 2
30 1
Notes 32 2
1. This sheet provides stressing bar requirements for skewed bridges with a maximum skew angle of 15°. Bar requirements for unskewed bridges are given on Sheet 3 of 9. 34 1
2. All stressing bars shall be perpendicular to the longitudinal bridge centerline and conform to the requirements of ASTM A722. For a decks less than, or equal to 12-in.—thick, bar diameter
is 5/8 in. For decks greater than 12-in.—thick, bar diameter is 1-in.
3. Bar spacing (S) is 2-ft for 5/8-in.-diameter bars and 4-ft for 1-in.-diameter bars. Typical end spacing (X) is based on bridge length and is given in Table 3.3. Refer to Sheet 5 of 9 for
layout of non-butt—jointed decks and Sheet 7 of 9 for layout of butt—jointed decks.
4. Because the bridge deck is skewed, bars in the skewed zone are not full-length and must be anchored at interior deck locations using the bar anchorage details given on Sheet 9 of 9. The
number of bars that must be so anchored depends On the bridge width and skew angle. Bar spacing adjustment may be required to achieve full bearing plate contact at the obtuse corner or 5|8
to maintain a minimum 6-ft bar length at the acute corner. Spacing adjustments for bars in the skewed zone should be made based on engineering judgement; however, the bar spacing in the
skewed zone shall not exceed the bar spacing specified in Table 3.3. End spacing may be increased to the bar spacing in the skewed zone.
Table 3.4 – Recommended Design Bar Tension Forces
5. Bar tension force is based on deck thickness and bar spacing. Bars shall be tensioned, in multiple passes, to the design bar tension force specified in Table 3.4. Bars shall be re-tensioned
as specified in Note 25, Sheet 2 of 9.
Bar Design Bar Tension Force (lb) for Actual Deck Thickness (t) Ranging from 8- to 16-in.
Diameter
(in.) 8 9% 10 11% 12 13% 14 15% 16
19,200 22,200 24,000 27,000 28,800
L-E- ºn I sign ºn l isºm
The bridge superstructures depicted on these drawings were *S.
developed under a cooperative research agreement between (2)
the Federal Highway Administration, the USDA Forest Service, %
Forest Products Laboratory, and Laminated Concepts, Inc. o
Stress-Laminated Sawn Lumber Decks
Stressing Bar Requirements - Skewed Bridges
Standard Plans for Timber Bridge Superstructures
December 2000
Sheet 4 of 9


15
Deck Lamination Layouts; No Butt-Joints
5/8-in.-Diameter Bars; Deck Thickness Less Than or Equal to 12 in.
Interior bor spocing (typicol)
1 ft H. ºt-2 t-I-2 t-I-2 *H ft End distonce (typicol)
10 ft
12 ft
14 ft
16 ft
18 ft
20 ft
22 ft
24 ft
26 ft
Bridge length
Notes
1. This sheet shows lamination layouts for decks with no butt—joints and 5/8-in. and 1-in. nominal bar diameters. Use 5/8-in. bars if the deck thickness
is less than or equal to 12-in., and 1-in. bars if the deck thickness is greater than 12-in.
2. Holes in the laminations for stressing bars shall be prebored at the specified bar spacing at the mid-depth of the lamination. For 5/8-in. bars, use a 1-in.
hole diameter. For 1-in. bars, use a 2-in. hole diameter. The hole diameter may be increased 1/4-in. if protective tubing (Sheet 9 of 9) is used.
3. Refer to Table 3.5 (Sheet 6 of 9) for the required deck thickness (t) based on lumber properties, span length, loading, and deflection limit.
1-in.-Diameter Bars; Deck Thickness Greater Than 12 in.
Interior bor spocing (typicol)
1 ft 4 ft .* 4 ft iº- 4 ft * 4 ft f—f 1 ft
H--- | | |
18 ft
20 ft
22 ft
24 ft
26 ft
Bridge length
The bridge superstructures depicted on these drawings were * Jº
developed under a cooperative research agreement between ſº
the Federal Highway Administration, the USDA Forest Service, % Cº E. -
Forest Products Laboratory, and Laminated Concepts, Inc. °sº tº S
Stress-Laminated Sawn Lumber Decks Deck Lamination Layouts; No Butt-Joints
December 2000 Sheet 5 of 9
Standard Plans for Timber Bridge Superstructures





16
Table 3.5 – Design Table for Sawn Lumber Decks with No Butt-Joints
e º Table instructions
AASHTO HS20–44 Loading | AASHTO HS25–44 Loading
Bridge || Span || Required The table on this sheet is for determining the required deck thickness for stress—laminated sawn lumber bridge
Length || L Value Minimum Required F.' (lblin’) and E’ (x10°lblin") Walues For Actual Deck Thickness” (t) Ranging from 8 to 16-in. decks. The citeſia for deck thickness selection are based on the span length vehicle loading Meload deflection
f limit, and material properties for the grade and species of lumber. The table provides the minimum required
(ft) (ft) l l 1 allowable design values for bending strength (F,') and modulus of elasticity (E') based on the vehicle live load, deck
8 9% 10 11% 12 13% 14 15% 16 8 9% 10 11% 12 13% 14 15% 16 dead load, and an assumed dead load of 10 lb/ft’ for the railing|curb and 38 lb/ft for the asphalt wearing surface.
f Allowable design values for horizontal shear (F,') are not listed because horizontal shear is not critical for shallow
Fº 1202 848 702 527 1396 988 819 616 526 deck sections. Blank cells in the table denote cases where the required design values exceed those typically
10 9 E" for L/360 || 0.79 || 0.48 || 0.37 || 0.24 0.93 0.57 || 0.43 || 0.29 || 0.23 available or that result in excessively conservative designs.
E" for L1500 || 1.10 0.67 0.51 0.34 1.29 0.78 0.60 0.40 0.32 The table may be used in two ways. When the material grade and species of the lumber are known, the designer
F.' 1,490 | 1,053 || 873 657 561 1,728 1,224 | 1,016 || 765 655 must determine the allowable design walues for the material, then compare them to the values given in the table.
f The allowable design values must be greater than or equal to the table values based on the selected deck thickness,
12 11 E' for L/360 || 1.18 0.72 0.55 0.36 0.29 1.39 0.84 0.64 0.43 0.34 span length, vehicle loading, and deflection limit. Alternatively, when the material grade and species are unknown,
E" for L1500 || 1.64 || 0.99 || 0.76 || 0.50 || 0.40 1.93 | 1.17 || 0.89 || 0.59 0.47 minimum required F," and E' values may be obtained from the table based on the span length, deck thickness,
F.' 1,785 | 1,264 || 1,049 || 791 677 1,466 | 1,218 919 787 loading, and deflection limit. A grade and species of lumber that meets these minimum allowable design values may
14 13 E" for L/360 || 1.65 1.00 0.76 0.50 0.40 1.18 0.90 0.60 0.48 then be selected. The following procedures are recommended for table use:
E' for L1500 1.39 1.06 0.70 0.56 1.64 1.25 0.83 0.66 Material Grade and Species Known
F.' 1,481 | 1,230 929 796 1,714 | 1,425 | 1,077 | 923 D d d
f 1. Determine the required design criteria for
16 15 E’ for L/360 1.33 1.01 0.67 0.53 1.57 1.20 0.79 0.63 a. span length measured center-to-center of bearings;
E' for L1500 1.85 | 1.41 || 0.93 || 0.74 1.66 | 1.10 || 0.88 b. vehicle loading, AASHTO HS20–44 or HS25–44; and
F.' 1,704 || 1,417 | 1,072 || 919 || 727 | 637 || 520 1,638 || 1,240 | 1,063 | 840 | 737 || 601 || 536 C. live load deflection limit, L/360 or L1500.
18 17 E" for L/360 1.71 1.30 0.86 0.69 0.48 0.40 0.29 1.54 1.02 0.81 0.57 0.47 0.35 0.29 2. Compute the allowable design walues for the grade and species of lumber laminations using the following
E’ for L1500 1.81 1.20 0.95 0.67 0.55 0.40 1.42 1.13 0.80 0.66 0.48 0.41 equations
F.' 1,609 | 1,219 || 1,047 || 829 728 595 532 1,856 | 1,407 || 1,208 || 956 839 686 612
20 19 || E' for L/360 1.63 | 1.08 || 0.86 0.60 || 0.49 || 0.36 || 0.31 1.92 | 1.27 | 1.02 || 0.72 0.59 || 0.43 || 0.37 where F, - F. Cw Cr Co Cls E’ - ECM
E' for L1500 1.49 1.19 0.84 0.69 0.51 0.42 1.77 1.41 0.99 0.82 0.60 0.51 F, - allowable bending stress (blin’) CM - wet service factor
F.' 1,807 || 1,371 1,178 || 934 || 821 || 673 || 602 1,578 1,356 | 1,075 945 || 773 || 691 F, - tabulated bending stress (blin’) 2 Cº - size factor
f E" - allowable modulus of elasticity (lblin) Co - load duration factor
22 21 E' for L/360 1.99 1.31 1.05 0.74 0.60 0.44 0.37 1.56 1.24 0.88 0.72 0.53 0.45 E - tabulated modulus of elasticity (lblin’) Cls - load sharing factor
E' for L1500 1.83 1.45 1.02 0.84 0.62 0.52 1.72 1.22 1.00 0.74 0.62
F.' 1,527 | 1,314 | 1,044 918 753 675 1,509 1,197 | 1,053 | 863 772 3. Enter the table and select a deck thickness based on the design criteria and allowable material properties
f previously determined. The allowable material property values for F," and E' must be greater than or equal to the
24 23 E’ for L/360 1.76 1.40 0.98 0.81 0.59 0.50 1.66 1.17 0.96 0.71 0.60 corresponding table values for the deck thickness selected. If not, the design criteria andlor material properties
E' for L1500 1.94 | 1.36 | 1.12 || 0.82 0.69 1.62 | 1.34 || 0.98 || 0.83 must be revised until acceptable values are achieved.
F.' 1,496 || 1,189 || 1,04 859 770 1,362 | 1,198 || 983 880 & e
f Matěſlal uſade and Sp8CIBS UIlkIIDWIl
26 25 E' for L/360 1.83 || 1.29 | 1.06 || 0.78 || 0.65 1.53 | 1.26 || 0.93 || 0.78 Material Grade and Species Unknown
E’ for L/500 1.79 1.47 | 1.08 || 0.91 1.75 1.29 1.09 1. Determine the required design criteria for
a – Rough-sawn sizes are 8, 10, 12, 14, and 16-in. and dressed sizes are 9%, 11%, 13%, and 15%—in.
a. span length measured center-to-center of bearings;
b. vehicle loading, AASHTO HS20–44 or HS25–44; and
C. live load deflection limit, L/360 or L1500.
2. Enter the table and select a deck thickness based on the design criteria. Note the required minimum allowable
design walues for F, and E'.
3. Select a grade and species of dimension lumber that provides the minimum allowable design walues.
The bridge superstructures depicted on these drawings were of
Stress-Laminated Sawn Lumber Decks Design Table - Decks With No Butt-Joints
developed under a cooperative research agreement between §§
the Federal Highway Administration, the USDA Forest Service, %. Qº


Forest Products Laboratory, and Laminated Concepts, Inc. *::::=
Standard Plans for Timber Bridge Superstructures December 2000 Sheet 6 of 9
Deck Lamination Layouts; With Butt-Joints
5/8-in.-Diameter Bars; Deck Thickness Less Than or Equal to 12 in.
Interior bor spocing (typical)
1 ft H. “Tº “Tº “T. “T. “Tº “Tº “T. "H 1 ft End distance (typical)
18 ft
4 lom. pottern repeats
-*
20 ft
22 ft
24 ft
Bridge length
Notes
1. This sheet shows lamination layouts for decks with butt—joints and 5/8- and 1-in. nominal bar diameters. Use a 5/8-in. bar if the deck thickness
is less than or equal to 12-in., and use a 1-in. bar if the deck thickness is greater than 12-in.
2. Butt-joint layouts are based on a repetitive pattern of four laminations. Butt—joints are limited to one joint in four adjacent laminations within a
longitudinal 4-ft distance. The length of each lamination is noted on the drawings. To facilitate construction, it may be beneficial to slightly reduce
lamination length to provide a 1/4- to 1/2-in. Gap at the butt—joint. For additional information about construction methods, refer to Recommended
Construction Practices for Stress-laminated Wood Bridge Decks (Ritter and Lee 1996).
3. Holes in the laminations for stressing bars shall be prebored at the specified bar spacing at the mid-depth of the laminations. For 5/8-in. bars, use
a 1-in.-diameter hole. For 1-in. bars, use a 2-in.-diameter hole. The hole diameter may be increased 1/4-in. if protective tubing (Sheet 9 of 9) is
used.
4. Refer to Table 3.6 (Sheet 8 of 9) for the required deck thickness (t) based on lumber properties, span length, loading, and deflection limit.
1 ft 4 ft—t—4 ft—f-4 ft—T-4 ft
H | | |
18 ft
20 ft
22 ft
1-in.-Diameter Bars; Deck Thickness Greater Than 12 in.
Interior bor spocing (typical)
H.
*=&
}
4 lom. pottern repeots
=d
f-2 º
er— Bridge length
The bridge superstructures depicted on these drawings were of 7
developed under a cooperative research agreement between ſº
the Federal Highway Administration, the USDA Forest Service, % C2;
Forest Products Laboratory, and Laminated Concepts, Inc. °sº
Stress-Laminated Sawn Lumber Decks Deck Lamination Layouts; With Butt-Joints
Standard Plans for Timber Bridge Superstructures December 2000 Sheet 7 of 9









18
Table 3.6 – Design Table for Sawn Lumber Decks with Butt-Joints
Bridge || Span
Length L
(ft) (ft)
33
Required
Walue
F.'
E' for L/360
E' for
F.'
E' for L/360
E' for
F.'
E' for L/360
E' for
F.'
E’ for L/360
E’ for
F.'
E’ for L/360
E' for
F.'
E' for L/360
E’ for
F.'
E' for L/360
E' for
F.'
E' for L/360
E' for
F.'
E' for L/360
E' for
AASHTO HS20–44 Loading
AASHTO HS25–44 Loading
Minimum Required F.' (lblin’) and E’ Walues" (x10°lblin") for Actual Deck Thickness" (t) Ranging from 10– to 16-in.
10
1,771
1.63
11%
1,340
1.08
1.58
1,524
1.35
1.86
1,714
1.64
12
1,149
0.86
1.19
1,309
1.08
1.49
1,473
1.31
1.81
1,643
1.75
13%
909
0.60
0.84
1,036
0.75
1.05
1,168
0.93
1.28
1,305
1.23
1.70
1,486
1.61
14
796
15%
650
0.36
0.50
744
0.45
0.64
841
0.55
0.78
941
0.74
1.03
1,074
0.98
1.35
1,235
1.23
1.70
1,400
1.50
1,569
1.79
16
580
0.31
0.43
665
0.39
0.53
753
0.46
0.65
844
0.63
0.86
963
0.81
1.14
1,106
1.03
1.43
1,254
1.26
1.75
1,406
1.50
1,564
1.78
11% 12
1,550 | 1,329
1.27 1.02
1.77 1.41
1,759 || 1,510
1.59 1.28
1.76
1,973 || 1,695
1.95 1.55
13%
1,050
0.72
0.99
1,195
0.90
1.24
1,344
1.10
1.53
1,496
1.46
1,702
1.91
14
921
0.59
0.82
1,049
0.74
1.03
1,181
0.90
1.25
1,316
1.20
1.68
1498
1.58
1,720
1.99
15%
751
0.43
0.60
858
0.54
0.75
966
0.66
0.93
1,079
0.89
1.23
1,229
1.16
1.61
1,411
1.46
1,599
1.79
a – Table values have been adjusted with a butt—joint factor (C) of 0.80 for the specified butt—joint layout of 1:4 at 4-ft as shown on Sheet 7 of 9.
b – Rough-sawn sizes are 8, 10, 12, 14, and 16-in.; dressed sizes are 9%, 11%, 13%, and 15%—in.
16
670
0.37
0.51
765
0.46
0.64
864
0.56
0.78
965
0.75
1.04
1,100
0.98
1.36
1,263
1.23
1.71
1,431
1.50
1,604
1.80
Table Instructions
The table on this sheet is for determining the required deck thickness for stress—laminated sawn lumber bridge decks. The criteria for deck thickness
selection are based on the span length, vehicle loading, live load deflection limit, and material properties for the grade and species of lumber. The table
provides the minimum required allowable design values for bending strength (F,') and modulus of elasticity (E') based on the vehicle live load, deck dead
load, and an assumed deadload of 10 lb/ft’ for the railing|curb and 38 lb/ft’ for the asphalt wearing surface. Allowable design values for horizontal shear
(F,') are not listed because horizontal shear is not critical for shallow deck sections. Blank cells in the table denote cases where the required design values
exceed those typically available or that result in excessively conservative designs.
The table may be used in two ways. When the grade and species of the lumber are known, the designer must determine the allowable design walues for
the material, then compare it to the values given in the table. The allowable design walues must be greater than Or equal to the table values based On the
selected deck thickness, span length, vehicle loading, and deflection limit. Alternatively, when the material grade and species are unknown, minimum
required F," and E' values may be obtained from the table based on the span length, deck thickness, loading, and deflection limit. A grade and species of
lumber that meets these minimum allowable design walues may then be selected. The following procedures are recommended for table use:
Material Grade and Species Known
1. Determine the required design criteria for
a. span length measured center-to-center of bearings;
b. vehicle loading, AASHTO HS20–44 or HS25–44; and
C. live load deflection limit, L1360 or L1500.
2. Compute the allowable design values for the grade and species of lumber laminations the following equations
F, - F, Cu Ci Co Cis E" - ECM
where
F, - allowable bending stress (blin’)
F, - tabulated bending stress (blin’)
E" - allowable modulus of elasticity (lblin’)
E - tabulated modulus of elasticity (blin’)
Cw - wet service factor
Cº - size factor
Co - load duration factor
Cls - load sharing factor
3. Enter the table and select a deck thickness based on the design criteria and allowable material properties previously determined. The allowable material
property values for F,' and E' must be greater than or equal to the corresponding table values for the deck thickness selected. If not, the design criteria
and/or material properties must be revised until acceptable values are achieved.
Material Grade and Species Unknown
1. Determine the required design criteria for
a. span length measured center-to-center of bearings;
b. vehicle loading, AASHTO HS20–44 or HS25–44; and
C. live load deflection limit, L1360 or L1500.
2. Enter the table and select a deck thickness based on the design criteria. Note the required minimum allowable design values for F, and E'.
3. Select a grade and species of dimension lumber that provides the minimum allowable design walues.
The bridge superstructures depicted on these drawings were
developed under a cooperative research agreement between
the Federal Highway Administration, the USDA Forest Service,
Forest Products Laboratory, and Laminated Concepts, Inc.
Stress-Laminated Sawn Lumber Decks
Design Table - Decks With Butt-Joints
Standard Plans for Timber Bridge Superstructures
December 2000
Sheet 8 of 9


19
Stressing Bar Anchorage Details
Steel bearing plote
/ /– outside lominotion,
/ / see Note 1.
| @
/TV
/ \
Steel onchor *—/ \– Hexogonol onchor nut
Bar Anchorage.
Side view
Hºnºioſ, ends
ſº moy be squore
Cut, lominotions_to occept beoring ond \
gnohor, plotes, Bore odjöcent lorrinotion
for nut ond 1 in. bor extension. -r-ſ"
15° moximum skew ++ |-|--
—
I
Bar Anchorage - Skew Zone
Plan View
Tubing extends to
inside edge of bearing plote.
| |\
|Miffl||||ITT
Protective PVC tubing
Neoprene "O" rings
Z\
Nºvºvºviv,
Steel bearing plote, see Toble 3.7
y-- beoring plote, see Toble 3.7
4 x 4 x 3/4 in. steel onchor plote (typicol)
4 x 6-1/2 x 1-1/4 in. steel onchor plote
with beveled hole (typicol)
5/8 in. diometer bor 1 in. diorneter bor
Flot onchor nut Sphericol onchor nut (typicol)
5/8 in. Bar Anchorage 1 in. Bar Anchorage
End view End view
Table 3.7 — Bearing Plate Dimensions
5/8-in.-Diameter Bar 1-in.-Diameter Bars
F. 1-in.—Thick Bearing Plate with 3/4-in.-Diameter Center Hole 1%—in.—Thick Bearing Plate with 1.5/16-in.-Diameter Center Hole
(blin’) Deck Thickness (in.) Deck Thickness (in.)
8 9% 10 11% 12 13% 14 15% 16
550 - 750 8 x 8 9 x 9 14 x14 15 x15
750 - 900 7 x 7 8 x 8 12 x12 13 x13
a – These requirements for compression perpendicular-to-grain values apply only to the exterior (two) laminations along each bridge edge.
Notes
1. The minimum compression perpendicular to grain tabulated stress for the exterior (two) laminations along each bridge edge is 550 lblin'. The interior deck laminations can be of lower
compression perpendicular to grain strength.
2. Anchorage systems shall consist of a steel bearing plate, anchor plate, and a high-strength steel nut. The anchor plate size is 4 x 4 x 3/4-in. for 5/8-in. diameter bars and 4 x 6-1/2 x 1-1/4-in.
for 1-in. diameter bars. Bearing plate size is given in Table 3.7 and depends on the deck thickness, bar spacing, and the unadjusted tabulated compressive stress perpendicular to grain (F.) of
the exterior (two) laminations along each bridge edge.
3. For a 1-in. bar diameter, a spherical anchor nut with a beveled hole in the anchor plate, supplied by the bar manufacturer, is typically used. A flat hex nut and anchor plate may be used at the
discretion of the designer.
4. To prevent corrosion of galvanized stressing bars, protective tubing (see detail this page) is recommended when the laminations are not treated with oilborne preservatives (the oil solvents coat
and provide some protection of steel components) or when the bridge will be subjected to deicing salt. To be flexible as the deck compresses during bar tensioning, two PVC tube diameters are
used with an Overlap section near the center of the bridge which is sealed with 0-rings.
The bridge superstructures depicted on these drawings were ſº
the Federal Highway Administration, the USDA Forest Service,
Forest Products Laboratory, and Laminated Concepts, Inc.
Stress-Laminated Sawn Lumber Decks Stressing Bar Anchorage Details
Standard Plans for Timber Bridge Superstructures December 2000 Sheet 9 of 9








20
Longitudinal Deck Systems:
Stress-Laminated Glulam Decks
The bridge superstructures depicted on these drawings were
Stress-Laminated Glulam Decks
- Title Page
developed under a cooperative research agreement between § DY,
the Federal Highway Administration, the USDA Forest Service, *. Qº
Forest Products Laboratory, and Laminated Concepts, Inc. *:::s Standard Plans for Timber Bridge Superstructures December 2000 Sheet 1 of 7
21


Plan, Profile, and Section Views
High-strenth
steel bor,
see Note 8.
Full-spon
glulom beam
lominotions
Weoring surfoce,
~~~ Note 1 O.
[-- Length |
Length=Bridge length measured
Width
L=Bridge spon meosured
c–c of bearings.
out-out
Width=Bridge width measured
out-out
Substructure shown for
[o] [o] […] [c] […]
v2
Tºs-L-T
Bridge roiling,
TX see Note 9. `AT
Deck thickness, t
see Note 5.
H HHH FFFFFFFFFEEEH H H-H H HEEEH
Width
|
illustrotion only, see
Note 5.
General Notes
DESIGN
1. These drawings are for longitudinal stress-laminated glulam timber bridge decks. The deck consists of a series of glulam
timber beams with widths ranging from 3– to 8-3/4-in. that are placed on edge between supports and transversely
compressed with high-strength steel bars. The glulam beams shall be continuous (full length) between supports with no
butt—joints. The designs are applicable for single- and double-lane and unskewed and skewed bridges up to 58-ft long.
Design truck loading is AASHTO HS 20–44 or HS 25–44 with live load deflection limits of LI360 or L1500.
2. The designs comply with the 1996 Standard Specifications for Highway Bridges, with 1998 Interims, and the 1991
Guide Specification for the Design of Stress-laminated Wood Decks, published by the American Association of State
Highway and Transportation Officials (AASHTO), except as noted. Load distribution widths are assumed to be width of
the tire (as defined by AASHTO) plus twice the deck thickness. The designs assume an interlaminar prestress of 100 lblin’
which has been shown to provide Optimum field performance.
3. Minimum required timber design values are provided for single-span bridge lengths of 18- to 58-ft in 2-ft increments.
Deck thicknesses (or beam depths) are specified for standard Southern Pine and Western Species glulam sizes ranging from
12- to 21-in. The required minimum deck thickness for a specific bridge length can be selected from tables on Sheet
5 of 7 and Sheet 6 of 7, based on material, loading, and deflection requirements.
4. Bridge width is variable by adjusting the number of glulam beams or individual glulam beam width.
5. The plans assume a uniform bearing length of 12-in. at both bridge ends and a span length, L, measured
center-to-center of bearings. A longer bearing length will result in a slightly more conservative design. Substructure
connection details are provided on Page 34.
6. Multiple span bridges may be constructed using a series of simple spans based on the designs presented in these
drawings. Multiple span continuous bridges are also commonly used and may be more economical but require site-specific
design. Refer to Page 34 for intermediate support connection details for both simple and continuous spans.
7. Skewed crossings are limited to 15° by AASHTO. Refer to Sheet 4 of 7 for information regarding design considerations
and stressing bar layout for skewed bridges.
8. High-strength steel bars are 1-in. nominal diameter. The diameter and spacing of bars depends on the deck thickness
and span as shown on Sheet 3 of 7 and Sheet 4 of 7.
9. Bridge rail and curb drawings are for illustration purposes only and must be designed based on site-specific
requirements. Deck designs are based on an assumed dead load of 10 lb/ft’ for the rail and curb system. Crashworthy
rail designs are available in Plans for Crash-Tested Bridge Railings for longitudinal Wood Decks (Ritter et al. 1995) and
Plans for Crash-Wested Bridge Railings for longitudinal Wood Deck on low-Volume Roads (Ritter et al. 1998).
10. An asphalt wearing surface with a geotextile fabric or membrane is recommended for most timber bridge applications.
For stress—laminated decks, the wearing surface should be installed after the first re-tensioning is completed (see Note
24). Deck designs are based on an assumed dead load of 38 lb/ft’ for an asphalt wearing surface (approximately 3-in.).
Refer to Page 53 for recommended asphalt wearing surface construction details.
11. These designs are intended for informational purposes only and, due to potential variations in design requirements and
use conditions, should be verified by a qualified professional engineer.
MATERIAL AND FABRICATION
Wood
12. Glulam timber beams shall comply with the requirements of AASHTO M168 and ANSI/AITC A190.1 and shall be
manufactured to an industrial appearance grade using wet-use adhesives.
13. Any species of glulam may be used provided it is treatable with wood preservatives and tabulated design values are
provided in the AASHTO Standard Specifications for Highway Bridges. Combinations should be selected from the
"members stressed primarily in bending" table.
14. Insofar as is practical, all glulam shall be cut, drilled, and completely fabricated prior to pressure treatment with wood
preservatives. Refer to Sheet 3 of 7 and Sheet 4 of 7 for information on stressing bar hole layout and diameter.
Preservative Treatment
15. All Glulamshall be treated in accordance with AASHTO M133 and AWPAC14 with one of the following preservatives:
a. Coal tar creosote conforming to AWPA Standard P1|P13.
b. Suitable oilborne preservative conforming to AWPA Standard P8 in hydrocarbon solvent, Type A or Type C.
16. Treated material shall follow post-treatment requirements summarized in Best Management Practices for the Use
of Treated Wood in Aquatic Environments (WWP 1996) to ensure all surfaces are free of excess preservative and
chemicals are fixated in the wood.
17. Preservative treatment shall be inspected and certified in accordance with AASHTO M133 and AWPA Standard M2.
Steel Fasteners and Hardware
18. Steel plates and shapes shall comply with the requirements of ASTM A36.
19. Stressing bars shall be nominal 1-in. diameter and shall comply with the requirements of ASTM A722. Order bars
at least 3-ft longer than total deck width. Nuts and couplers for stressing bars shall be provided by the bar manufacturer
and shall be re-threaded to ensure proper fit after galvanizing.
20. Bolts and lag screw shall comply with the requirements of ANSI/ASME Standard B18.2.1–1981, Grade 2.
21. All steel components and fasteners shall be galvanized in accordance with AASHTO M111 or AASHTO M232 or
otherwise protected from corrosion. Galvanizing of stressing bars shall also follow the recommendations of the bar
manufacturer so as not to adversely affect the mechanical properties of the high-strength steel.
22. Washers shall be provided under bolt and lag screw heads and under nuts that are in contact with wood. Washers
may be omitted under heads of special timber bolts or dome-headbolts when thesize and strength of the head is sufficient
to develop connection strength without wood crushing.
CONSTRUCTION
23. Decks may be assembled by placing glulam timber beams on edge, side-by-side on the substructure. After placing all
glulam timber beams, steel stressing bars are inserted into prebored holes and baranchorage plates and nuts are attached.
Tensioning of the high-strength stressing bars is typically performed with a single hydraulicjack and steel stressing chair
in a repetitive manner beginning at One end of the bridge. When initially tensioning bars, it is important that the full tension
not be applied until all glulam timber beams are aligned and in full contact with adjacent glulam timber beams. For
additional information and alternative assembly methods, refer to Recommended Construction Practices for Stress.
laminated Wood Bridge Decks (Ritter and Lee 1996).
24. Stressing bars shall be fully tensioned to the values specified on Sheet 3 of 7 and Sheet 4 of 7 in accordance with
the following sequence:
1. Initially tensioned at construction.
2. Re-tensioned 1–2 weeks after the initial tensioning.
3. Re-tension 6–8 weeks after the first re-tensioning.
It is recommended that the bars be checked and retensioned as required, 2 years after construction and at 3–5 year
intervals thereafter until the bar force stabilizes above 50 percent of the design level. If excess bar length is to be
trimmed, leave a minimum of 8-in. beyond the anchor nut to allow for re-tensioning.
25. All wood and metal components shall be handled and stored carefully so as not to damage the material. If damage
does occur, exposed untreated wood shall be field treated in accordance with AASHTO M133. Damage to galvanized
surfaces shall be repaired with a cold galvanizing compound or other approved coating.
26. The application of a bituminous sealer is recommended to prevent excessive wood checking in areas where the wood
end grain is exposed. Any commercially available roofing cement is effective.
The bridge superstructures depicted on these drawings were
developed under a cooperative research agreement between
the Federal Highway Administration, the USDA Forest Service,
Forest Products Laboratory, and Laminated Concepts, Inc.
@
Stress-Laminated Glulam Decks
Superstructure Drawings and General Notes
Standard Plans for Timber Bridge Superstructures
December 2000 Sheet 2 of 7



22
Stressing Bar Requirements - Unskewed Bridges
|
|
|
|
|
|
—H
|
|
|
|
|
|
Plan view
Table 4.1 – Bar Spacing and Design Bar Tension Forces
S = Bor spocing measured
center-center, see Toble 4.1.
X = End spocing measured from bridge end
to center of 1st bor, see Toble 4.2.
Roodway Q.
1 in. Ø ASTM A722 steel bor.
Bor onchoroge,
see Sheet 7 of 7.
Bar Spacing,
Deck Thickness, t S Design Bar Tension Force"
(in.) (ft) (lb)
12 57,600
12.3% 59,400
13 /, 64,800
13 * 4 66,000
15 72,000
15 1/3 72,600
16 % 79,200
177/6 85,800
18 64,800
19 % 69,300
19 % 3 70,200
20 5/3 74,250
21 15,600
a-Based upon 100 lblin’ deck interlaminar prestress.
Notes
1. This sheet provides stressing bar requirements for unskewed bridges. Bar requirements for skewed bridges
are given on Sheet 4 of 7.
2. All stressing bars shall be perpendicular to the longitudinal bridge centerline and are 1-in. nominal diameter
high-strength steel bars conforming to the requirements of ASTM A722.
3. Bar spacing (S) is specified in Table 4.1 based on deck thickness. End spacing (X) is based on bridge length
and is given in Table 4.2.
4. Bars are placed through holes prebored at mid-depth of the glulam beams. A hole diameter of 1-3/4-in. is
recommended. The hole diameter may be increased to 2-in. if protective tubing (Sheet 7 of 7) is used.
5. Bar tension force is based on deck thickness and bar spacing. Bars shall be tensioned, in multiple passes, to
the design bar tension specified in Table 4.1. Bars shall be re-tensioned as specified in Note 24, Sheet 2 of 7.
Table 4.2 – End
4-ft Bar
Bridge Length, L
(ft)
18
20
22
24
26
28
30
32
34
36
38
40
42
End Spacing, X Bridge Length, L
(ft)
1
2
1
2
1
2
1
2
1
2
1
2
1
(ft)
32
34
36
38
40
42
44
46
48
50
52
54
56
End Spacing, X
(ft)
2.5
2.0
1.5
2.5
2.0
1.5
2.5
2.0
1.5
2.5
2.0
1.5
2.5
The bridge superstructures depicted on these drawings were of T
developed under a cooperative research agreement between @
the Federal Highway Administration, the USDA Forest Service, w ©.
Stress-Laminated Glulam Decks
Stressing Bar Requirements - Unskewed Bridges




Forest Products Laboratory, and Laminated Concepts, Inc. *nº of
Sheet 3 of 7
Standard Plans for Timber Bridge Superstructures
December 2000
Stressing Bar Requirements - Skewed Bridges
S = Bor spocing for full-width bors
meosured center-center, see Toble 4.5.
X = End spocing measured from end of
bridge to center of 1st bor, see Toble 4.4.
Notes
1. This sheet provides stressing bar requirements for skewed bridges with a maximum skew angle of 15°. Bar
requirements for unskewed bridges are given on Sheet 3 of 7.
2. All stressing bars are perpendicular to the longitudinal bridge centerline and are nominal 1-in.-diameter
high-strength steel bars conforming to the requirements of ASTM A722.
3. Bar spacing (S) is specified in Table 4.3. Typical end spacing (X) is based on bridge length and is given in Table 4.4.
| |
| |
| |
| | |
| | |
|
| ſ Hººk | 4. Because the bridge deck is skewed, bars in the skewed zone are not full length and must be anchored at interior
I I + HºN deck locations using the bar anchorage details given on Sheet 7 of 7. The number of bars that must be so anchored
H : HN | | | depends on the bridge width and skew angle. Bar spacing adjustment may be required to achieve full bearing plate
H | |- =\ –H | | Roodwoy Q. contact at the obtuse corner or to maintain a minimum 6-ft bar length at the acute corner. Spacing adjustments for
#. H | | | EN | | | | bars in the skewedzone should be made based on engineering judgement; however, the bar spacing in the skewed zone
H | f | HM | | | | shall not exceed the bar spacing specified in Table 4.3. End spacing may be increased to the bar spacing.
I I y Yg w \
I I T I I \
H I : H ! A. | | | 5. Bars are placed through holes prebored at mid-depth of the glulam beams. A hole diameter of 1–3|4-in. is
Á i : : : W | Bor onchoroge, see Sheet 7 of 7. recommended. The hole diameter may be increased to 2-in. if protective tubing (Sheet 7 of 7) is used.
I I I I
H | t f t TV | | | | 6. Bar tension force is based on deck thickness and bar spacing. Bars shall be tensioned to the design bar tension
H | i i i H | | | | specified in Table 4.3. Bars shall be re-tensioned as specified in Note 24, Sheet 2 of 7.
I A. I I I TV
F : | | | == | | | 1 in. © ASTM A722 steel bor.
Table 4.4 – End
º, º jºgose,
See Snee OT /. te * & tº
Plan view Table 4.3 — Bar Spacing and Design Bar Tension Forces Bridge * l End * X Bridge * l End * X
| Deck. Thickness, Bar Spacing, 3.
t S Design Bar Tension Force 18 1 32 2.5
(in.) (ft) (b) 20 2 34 2.0
12 57,600 22 1 36 1.5
123% 59,400 24 2 38 2.5
13 A 64,800 26 1 40 2.0
13 * 4 66,000 28 2 42 1.5
15 72,000 30 1 44 2.5
15 Mé 72,600 32 2 46 2.0
16 % 79,200 34 1 48 1.5
17.7/s 85,800 36 2 50 2.5
18 64,800 38 1 52 2.0
19 % 69,300 40 2 54 1.5
19 % 3 70,200 42 1 56 2.5
205% 74,250
| 21 15,600
a-Based upon 100 lblin’ deck interlaminar prestress.
The bridge superstructures depicted on these drawings were dº Stress-Laminated Glulam Decks Stressing Bar Requirements - Skewed Bridges
developed under a cooperative research agreement between (4 ń. ng eq
the Federal Highway Administration, the USDA Forest Service, WGZ;
Forest Products Laboratory, and Laminated Concepts, Inc. *nº ot Standard Plans for Timber Bridge Superstructures December 2000 Sheet 4 of 7
:




24
Table 4.5 – Stress—laminated Glulam Deck Design Table
Table Instructions
AASHTO HS20–44 Loading | AASHTO HS25-44 Loading
Bridge || Span e tº º { } e tº The table on this sheet is for determining the deck thickness for stress—laminated, glulam bridge decks. The criteria for deck
Length || L Required Minimum Required F.' (lblin’) and E' (x10°lblin") Walues for Actual Deck Thickness” (t) Ranging from 12- to 21-in. thickness selection are based on span length, vehicle loading, live load deflection limit, and the material properties for the species
(ft) (ft) Walue and glulam combination. The table provides the minimum required allowable design values for bending strength (F,') and modulus
12 | 1.23% | 1.3% | 1.3% | 15 || 15% | 16% 177/8 || 18 || 19% | 19% || 12 || 12% | 1.3% | 1.3% | 15 15% | 16% | 177/6 || 18 || 19% | 19% of elasticity (E') based on the vehicle live load, deck deadload, and an assumed deadload of 10 blft’ for the railing|curb and 38
f |b|ft’ for the asphalt wearing surface. Allowable design values for horizontal shear (F,') are not listed because horizontal shear
Fº 919 || 855 || 595 | 665 1,063 || 989 804 || 769 || 625 | 613 is not critical for shallow deck sections. Blank cells in the table denote cases where the required design walues exceed those
18 17 || E' for LI360 || 0.69 || 0.61 || 0.45 0.42 0.81 || 0.73 || 0.54 || 0.50 || 0.37 || 0.36 typically available or that result in excessively conservative designs.
E’ for L/500 || 0.95 || 0.85 || 0.63 || 0.59 1.13 | 1.01 || 0.75 || 0.70 || 0.51 || 0.50 The table may be used in two ways. When the species and glulam combination are known, the designer must determine the
allowable design values for the material, then compare them to the values given in the tables above. The allowable design values
F.' 1,047 | 974 || 793 || 759 || 619 || 607 1,208 || 1,123 914 || 876 || 718 || 699 must be greater than or equal to the table values based on the selected deck thickness, span length, vehicle loading, and deflection
limit. Alternatively, when the species and glulam combination are unknown, minimum required F," and E' walues may be obtained
20 19 || E' for LI360 || 0.86 || 0.77 || 0.56 || 0.53 || 0.39 || 0.37 1.02 || 0.91 || 0.67 || 0.63 || 0.46 || 0.45 from the tables based on the span length, deck thickness, loading, and deflection limit. A species and glulam combination that
meets these minimum allowable design walues may then be selected. The following procedures are recommended for table use:
E' for L1500 || 1.19 | 1.07 || 0.78 || 0.73 || 0.54 || 0.52 1.41 | 1.27 || 0.93 || 0.87 || 0.64 0.62
Species and Glulam Combination Known
F.' 1,178 || 1,096 | 894 || 857 || 699 || 686 1,356 | 1,262 | 1,029 || 985 | 803 || 788 || 643
f 1. Determine the required design criteria for
22 21 || E' for L/360 || 1.05 || 0.94 || 0.69 || 0.64 || 0.47 || 0.46 1.24 || 1.11 || 0.82 || 0.77 || 0.56 0.55 || 0.40 a. span length measured center-to-center of bearings;
E' for L1500 || 1.45 | 1.30 0.96 || 0.89 || 0.65 0.64 1.72 | 1.55 | 1.14 | 1.07 || 0.78 || 0.76 || 0.56 b.vehicle loading. AASHTOHS20-440 HS25–44 and
C. live load deflection limit, L/360 or L1500.
F.' 1,314 || 1,223 999 || 958 783 || 768 626 1,509 || 1,404 || 1,146 | 1,098 || 897 || 880 || 719 || 597
2. Compute the allowable design values for the species and glulam combination using the following equations:
24 23 || E' for LI360 || 1.40 | 1.25 || 0.92 || 0.86 0.63 || 0.61 0.45 1.66 | 1.49 || 1.09 | 1.02 || 0.75 || 0.73 || 0.53 || 0.40
F.' - F, Cu Cw Co E’ = E Cu
E’ for L/500 || 1.94 | 1.74 | 1.28 | 1.20 0.87 || 0.85 0.62 1.52 | 1.42 | 1.04 || 1.01 || 0.74 || 0.56
where
Fº 1,496 || 1,393 || 1,138 || 1,091 | 893 || 876 || 718 || 598 1,304 || 1,250 | 1,021 | 1,002 || 819 | 682 || 671 F, - allowable bending stress (blin’) Cu - wet service factor
* , e * 2 .
26 || 25 | E' for L/360 || 1.83 | 1.64 | 1.20 | 1.13 || 0.83 || 0.80 || 0.58 || 0.44 1.43 | 1.34 || 0.98 || 0.96 || 0.70 || 0.52 || 0.51 § - tºº lºssº. C, -volume factor
E" - allowable modulus of elasticity (lbſin Co - load duration factor
E’ for L1500 1.67 | 1.57 | 1.15 | 1.11 0.81 || 0.61 1.99 || 1.86 || 1.37 || 1.33 || 0.97 || 0.73 || 0.71 E - tabulated modulus of elasticity (lblin’)
F.' 1,307 || 1,253 | 1,026 1,006 || 825 | 688 || 677 1,435 | 1,173 || 1,150 941 || 783 || 771 | 661 642 3. Enter the table and select a deck thickness based on the design criteria and allowable material properties previously
determined. The allowable material property values for F," and E' must be greater than or equal to the corresponding table values
28 27 || E' for L/360 1.52 | 1.42 | 1.04 || 1.01 || 0.74 0.55 0.54 1.69 | 1.24 | 1.20 || 0.88 || 0.66 || 0.64 || 0.50 || 0.48 for the deck thickness selected. If not, the design criteria and/or material properties must be revised until acceptable values are
achieved.
E' for L1500 1.97 | 1.44 || 1.40 | 1.02 || 0.76 || 0.75 1.72 | 1.67 | 1.22 || 0.92 || 0.89 || 0.70 || 0.67
F.' 1,481 | 1,420 | 1,163 1,141 || 936 || 780 || 768 || 661 || 642 1,328 || 1,303 || 1,067 || 888 || 874 || 750 | 729 Species and Glulam Combination Unknown
30 29 || E' for L/360 1.85 | 1.74 || 1.27 | 1.23 || 0.90 || 0.67 || 0.66 || 0.51 || 0.49 1.52 | 1.47 | 1.08 || 0.81 || 0.79 || 0.62 || 0.59 * & tº tº . º.
1. Determine the required design criteria for
E' for L1500 1.76 | 1.71 | 1.25 || 0.93 || 0.91 || 0.71 || 0.68 1.50 | 1.12 | 1.09 || 0.86 || 0.82 a. span length measured center-to-center of bearings;
a – Western species glulam sizes are 12, 13%, 15, 16%, 18, and 19%—in.; Southern pine glulam sizes are 12%, 13%, 15%, 16%,177/6, and 19%—in.
b. vehicle loading, AASHTO HS20–44 or HS25–44; and
C. live load deflection limit, LI360 or L1500.
2. Enter the table and select a deck thickness based on the design criteria. Note the required minimum allowable design walues
for F, and E'.
3. Select a species and combination of glulam that provides the minimum allowable design values. Glulam combinations should
be selected from the "members stressed primarily in bending" table.
The bridge superstructures depicted on these drawings were
developed under a cooperative research agreement between Stress-Laminated Glulam Decks
Stress-Laminated Glulam Deck Design Table
the Federal Highway Administration, the USDA Forest Service,

Forest Products Laboratory, and Laminated Concepts, Inc.
Standard Plans for Timber Bridge Superstructures
December 2000 Sheet 5 of 7
Table 4.5 – Stress-Laminated Glulam Deck Design Table, Continued
AASHTO HS20–44 Loading | AASHTO HS25–44 Loading AASHTO HS20–44 Loading AASHTO HS25–44 Loading
Bridge || Span Bridge || Span
Length l Required Minimum Required F.' (lblin’) and E' (x10°lblin") Walues for Actual Deck Thickness” (t) Ranging from 12– to 21-in. Length L Required || Minimum Required F.' (lblin’) and E' (x10°lblin') Values for Actual Deck Thickness"(t)
(ft) (ft) Walue (ft) (ft) Walue
15 || 15% | 16% 177/6 || 18 19% | 19% | 205% 21 15 || 15% | 16% | 177/6 | 18 19% | 19% | 205/6 || 21 19% 19% 205/6 21 19% 19% 205/6 21
F.' 1,304 || 1,279 || 1,049 || 876 862 742 721 637 61.2 1,195 || 996 980 842 817 720 692 F.' 1,634 1,589 1,408 1,354 1,518
32 31 E' for LI360 || 1.52 1.48 1.08 0.81 0.79 0.62 0.59 0.48 0.45 1.29 0.97 0.94 0.74 0.70 0.57 0.54 50 49 E' for LI360 1.92 1.83 1.49 1.39 1.68
E' for L1500 1.50 1.12 1.09 0.85 0.81 0.66 0.62 1.79 1.34 1.31 1.03 0.98 0.80 0.75 E' for L1500 1.93
F.' 1,448 || 1,421 | 1,166 || 974 959 826 802 709 682 1,327 | 1,106 || 1,089 || 935 909 801 770 F.' 1,504 1,447 1,621
34 33 E' for LI360 || 1.79 1.74 1.27 0.95 0.92 0.72 0.69 0.56 0.53 1.52 1.14 1.11 0.87 0.83 0.68 0.63 52 51 E’ for LI360 1.64 1.53 1.84
E' for L1500 1.76 1.32 1.28 1.00 0.96 0.78 0.73 1.58 1.54 1.21 1.15 0.94 0.88 E' for L1500
F.' 1,293 || 1,081 | 1,064 916 891 787 753 1,462 | 1,226 1,207 || 1,037 || 1,008 || 889 854 F.' 1,602 1,542
36 35 E' for LI360 1.47 1.10 1.07 0.84 0.80 0.65 0.61 1.76 1.32 1.28 1.01 0.96 0.78 0.73 54 53 E' for LI360 1.79 1.68
E’ for L1500 1.53 1.49 1.16 1.11 0.90 0.85 1.83 1.79 1.40 1.34 1.09 1.02 E' for L1500
F.' 1,428 1,193 | 1,175 | 1,012 || 984 870 827 1,353 | 1,332 1,145 || 1,113 || 982 943 F.' 1,702 1,639
38 37 E' for LI360 1.68 1.26 1.23 0.96 0.92 0.75 0.70 1.51 1.47 1.15 1.10 0.90 0.84 56 55 E' for LI360 1.95 1.83
E' for L1500 1.75 1.71 1.33 1.27 1.04 0.97 1.60 1.53 1.25 1.17 E' for L1500
F.' 1,565 | 1,309 || 1,289 1,111 || 1,080 || 955 902 1,483 || 1,460 | 1,255 | 1,220 | 1,076 | 1,034 F.' 1,737
40 39 E' for LI360 1.91 1.43 1.39 1.09 1.04 0.85 0.79 1.71 1.67 1.31 1.25 1.02 0.95 58 57 E' for LI360 1.98
E' for L1500 1.99 1.74 1.51 1.45 1.18 1.10 1.82 1.74 1.42 1.33 E' for L1500
F.' 1,426 | 1,404 || 1,211 || 1,177 | 1,041 | 1,002 1,614 | 1,589 || 1,367 | 1,329 || 1,173 || 1,127 a – Western species glulam sizes are 15, 16%, 18, 19%, and 21-in.;
42 || 41 || E' for LI360 1.62 | 1.58 || 1.23 | 1.18 || 0.96 || 0.90 1.94 | 1.89 | 1.48 || 1.41 | 1.15 | 1.08 Southern pine glulam sizes are 15%, 16%,177/6, 19%, and 20%—in.
E" for L1500 1.71 1.63 1.33 1.25 1.96 1.60 1.50
F.' 1,546 | 1,523 | 1,313 || 1,277 | 1,130 | 1,087 1,482 | 1,440 | 1,272 | 1,222
Refer to Sheet 5 of 7 for table instructions.
44 43 E' for LI360 1.82 1.78 1.39 1.33 1.08 1.01 1.67 1.60 1.30 1.22
E' for L1500 1.93 1.84 1.50 1.40 1.81 1.69
F.' 1,643 | 1,418 || 1,379 || 1,221 | 1,174 1,598 || 1,553 | 1,372 | 1,319
46 45 E' for L/360 1.99 1.56 1.49 1.21 1.13 1.87 1.79 1.46 1.36
E' for L1500 1.68 1.57 1.89
F.' 1,525 | 1,483 || 1,313 | 1,263 1,669 | 1,475 | 1,418
48 47 E' for LI360 1.73 1.65 1.35 1.26 1.99 1.62 1.52
E' for L1500 1.87 1.75
The bridge superstructures depicted on these drawings were
developed under a cooperative research agreement between
the Federal Highway Administration, the USDA Forest Service,
Forest Products Laboratory, and Laminated Concepts, Inc.
@
*nº of
Stress-Laminated Glulam Decks
Stress-Laminated Glulam Deck Design Table
Standard Plans for Timber Bridge Superstructures
December 2000
Sheet 6 of 7
|


26
Beoring plote, see Toble 4.6
/ |ſ 4 x 6-1/2 x 1-1/4 in. onchor plote
/ |
/ |
Bar Anchorage
Side view
Cut lorninotions to occept bearing ond º:
onchor plotes. Bore odjocent loninotion
for nut ond 1 in. bor extension. —ſ-T
N _-HTT
—T
r_T Is ºx a
*E.
–
º
t_
+-k
º
-
tº
|-
tº
.
_º
15 moximum skew
Bar Anchorage Embedded in Skewed Zone
Plan view
Bar Anchorage
End view
Tubing extends to inside
/ edge of bearing plote
Sphericol hex nut
Table 4.6 — Required Plate Dimensions
strength.
/ l |TN
||||||NE
Protective plostic tubing
eoprene O-rings
overlop
Protective PVC Tubing for Galvanized Bars
Section view
FCL Range FCL Range
Deck 560 thru 650 lblin’ 650 thru 800 lblin’
Thickness Spacing
(in.) Bearing Plate (in.) | Anchor Plate (in.) || Bearing Plate (in.) | Anchor Plate (in.)
1 in. Ø ASTM A722 steel bor
12 12 x 16 x 1 12 x 1.4 x 1
12% 12 x 17 x 1 12 x 15 x 1
13%
13 x 17 x 1 13 x 15 x 1
13%
15 4 x 6% X 1% 4 x 6% X 1%
1.4 x 17 x 1
151/3 15 x 15 x 1
16% 16 x 17 x 1
177/3 16 x 18 x 1 16 x 16 x 1
18 15 x 15 x 1 4 x 6% X 1% 1.4 x 14 x 1
19%
19% 4 x 6% X 1%
15 x 15 x 1
205/6
21
Notes
1. The minimum compression perpendicular to grain tabulated stress for the exterior (two) glulamlaminations along
each bridge edge is 560 lblin'. The interior glulam laminations can be of lower compression perpendicular to grain
2. Anchorage systems shall consist of a steel bearing plate, anchor plate, and a high-strength steelmut. The anchor
plate size is 4 x 6–112 x 1-1/4-in. for all cases. Bearing plate size is given in Table 4.6 and depends on the deck
thickness, bar spacing, and the unadjusted tabulated compressive stress perpendicular to grain (F.) of the exterior
(two) glulam laminations along each edge.
3. To prevent corrosion of galvanized stressing bars, protective tubing (see detail on this page) is recommended
when the bridge will be subjected to deicing salt. To be flexible as the deck compresses during bar tensioning, two
PVC tube diameters are used with an overlap section near the center of the bridge that is sealed with 0-rings.
The bridge superstructures depicted on these drawings were
developed under a cooperative research agreement between
the Federal Highway Administration, the USDA Forest Service,
Stress-Laminated Glulam Decks
Stressing Bar Anchorage
*|





Forest Products Laboratory, and Laminated Concepts, Inc.
Sheet 7 of 7
Standard Plans for Timber Bridge Superstructures
December 2000
Longitudinal Deck Systems:
Longitudinal Glulam Panel Decks
|
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|
|
The bridge superstructures depicted on these drawings were
developed under a cooperative research agreement between
the Federal Highway Administration, the USDA Forest Service,
Forest Products Laboratory, and Laminated Concepts, Inc.
Longitudinal Glulam Panel Decks
Title Page
Standard Plans for Timber Bridge Superstructures
December 2000
Sheet 1 of 6


28
Plan, Profile, and Section Views
Wearing
surfoce,
see Note 9.
Width
L=Bridge spon meosured
| c–c of bearings
| Length
Length=Bridge length measured
out-out
Width=Bridge width measured
out-out
Tronsverse stiffener beam (glulom
or steel), see Note 5.
Bridge roiling,
see Note 8. \g
IX. Deck thickness, t,
see Note 5.
IIII
WTW
Substructure shown for
illustrotion only,
see Note 6.
|
|
|
|
|
--r— Width
General Notes
DESIGN
1. These drawings are for longitudinal glulam timber decks. The decks consist of a series of glulam panels
that are placed side-by-side between supports and interconnected with transverse stiffener beams. The
designs are applicable for single- and double-lane and unskewed and skewed bridges up to 38-ft long.
Design truck loading is AASHTO HS20–44 or HS25–44, with live load deflection limits of L/360 or
L|500.
2. The designs comply with the 1996 Standard Specifications for Highway Bridges, with 1998 Interims,
published by the American Association of State Highway and Transportation Officials (AASHTO), except
where noted. Load distribution is based on a load fraction (as specified in AASHTO) applied to each panel
based on the panel width and bridge span. Deck panels with multiple-piece laminations are assumed to
have unbonded edges.
3. Minimum required timber design values are provided for single-span bridge lengths of 12- to 38-ft
in 2—ft increments. Deck thicknesses are specified for standard Southern Pine and Western Species
glulam sizes ranging from 8-1/2 to 16–1|4 in. The required minimum deck thickness for a specific bridge
length can be selected from tables on Sheet 5 of 6 and Sheet 6 of 6, based on material, loading, and
deflection requirements.
4. Design calculations are based on actual deck panel widths of 42-in. for single-lane bridges and
50.9-in. for double-lane bridges. Bridge widths are variable by adjusting the number and width of deck
panels as shown on Sheet 3 of 6.
5. Deck panels are interconnected with glulam or steel-channel transverse stiffener beams
through-bolted to the panel undersides. Refer to Sheet 4 of 6 for transverse stiffener beam layout and
connection details.
6. The design assumes a uniform bearing length of 12-in. at both bridge ends and a span length, L,
measured center-to-center of bearings. Alonger bearing length will result in a slightly more conservative
design. Substructure connection details are provided on Page 34.
7. Multiple span bridges may be constructed using a series of simple spans based on the designs
presented in these drawings. Multiple span continuous bridges are also commonly used and may be more
economical but require site-specific design. Refer to Page 34 for intermediate support connection details
for both simple and continuous spans.
8. Bridge rail and curb drawings are for illustration purposes only and must be designed based on site
specific requirements. Deck designs are based on an assumed dead load of 10 lb/ft’ for the rail and curb
system. Crashworthy rail designs are available in Plans for Crash—Tested Bridge Railings for longitudinal
Wood Decks (Ritter et al. 1995) and Plans for Crash-Wested Bridge Railings for longitudina/Wood Decks
on Low-Volume Roads (Ritter et al. 1998).
9. An asphalt wearing surface with a geotextile fabric or membrane is recommended for most timber
bridge applications. Deck designs are based on an assumed dead load of 38 lb/ft’ for an asphalt wearing
surface (approximately 3-in.). Refer to Page 53 for recommended asphalt wearing surface construction
details.
10. These designs are intended for informational purposes only and, due to potential variations in design
requirements and use conditions, should be verified by a qualified professional engineer.
MATERIAL AND FABRICATION
Wood
11. Glulam deck panels shall comply with the requirements of AASHTO M168 and ANSI/AITC A190.1
and shall be manufactured to an Industrial appearance using wet—use adhesives.
12. Any species of glulam may be used provided it is treatable with wood preservatives and tabulated
design walues are provided in the AASHTO Standard Specifications for Highway Bridges. Deck panel
glulam combinations should be selected from the tables for "members stressed primarily in axial tension
or compression".
13. Insofar as is practical, all glulam shall be cut, drilled, and completely fabricated prior to pressure
treatment with preservatives. Refer to Sheet 3 of 6 and Sheet 4 of 6 for layout details.
Preservative Treatment
14. All glulam shall be treated in accordance with AASHTO M133 and AWPA Standard C14 with one
of the following preservatives:
a. Coal tar creosote conforming to AWPA Standard P1|P13
b. Suitable oil borne preservatives conforming to AWPA Standard P8 in hydrocarbon solvent, Type A or
Type C.
15. Treated material shall follow post-treatment requirements summarized in Best Management
Practices for the Use of Treated Wood in Aquatic Environments (WWPI 1996) to ensure all surfaces are
free of excess preservative and chemicals are fixated in the wood.
16. Preservative treatment shallbeinspected and certified in accordance with AASHTO M133 and AWPA
Standard M2.
Steel Fasteners and Hardware
17. Steel plates and shapes shall comply with the requirements of ASTM A36.
18. Bolts and lag screws shall comply with the requirements of ANSI/ASME Standard B18.2.1–1981,
Grade 2.
19. All steel components and fasteners shall be galvanized in accordance with AASHTO M111 or
AASHTO M232 or otherwise protected from corrosion.
20. Washers shall be provided under bolt and lag screw heads and under nuts that are in contact with
wood. Washers may be omitted under heads of special timber bolts or dome-head bolts when the size
and strength of the head is sufficient to develop connection strength without wood crushing.
CONSTRUCTION
21. Longitudinal glulam decks are typically constructed by placing the center panels first, then placing
the outside panels. Stiffener beams should be attached as the panels are placed, but connecting bolts
should not be tightened beyond hand tight until all panels are in place.
22. Glulam panels may swell slightly in the transverse direction due to moisture content increases
in-service. In constructing supports, space should be left at the bridge edges to allow for possible lateral
expansion. Provisions for longitudinal expansion, parallel to traffic, are not required since little expansion
will occur in this direction.
23. All wood and metal components shall be handled and stored carefully so as not to damage the
material. If damage does occur, exposed, untreated wood shall be field treated in accordance with
AASHTO M133. Damage to galvanized surfaces shall be repaired with a cold galvanizing compound or
Other approved coating.
24. The application of a bituminous sealer is recommended to prevent excessive wood checking in areas
where the wood end grain is exposed. Wertical joint surfaces, between glulam panels, should also be
coated to minimize moisture penetration. Any commercially available roofing cement is effective.
The bridge superstructures depicted on these drawings were
developed under a cooperative research agreement between
the Federal Highway Administration, the USDA Forest Service,
Longitudinal Glulam Panel Decks Superstructure Drawings and General Notes
*







Forest Products Laboratory, and Laminated Concepts, Inc.
Standard Plans for Timber Bridge Superstructures December 2000 Sheet 2 of 6
Deck Panel Layouts
Notes
1. Deck panel layouts on this sheet are for single-lane bridges of nominal 12– and 16-ft roadway widths and double-lane bridges of nominal 24-, 28–,
and 32-ft roadway widths. Actual bridge widths wary slightly from nominal widths depending on the panel width, which is a multiple of the standard
lamination thickness.
2. Actual bridge widths are given in Table 5.1 based on 1-1/2-in.—thick laminations for Western Species glulam and 1–3|8-in-thick laminations for
Southern Pine glulam. The nominal bridge width (X) assumes a 1-ft wide curblrailing along each deck edge.
3. Load distribution for longitudinal glulam deck panels is a function of the panel width. These designs are based on a panel width of 42-in. for
Single-Lane Bridges single-lane bridges and 50.9-in. for double-lane bridges. Panel widths larger than the assumed values result in a slightly more conservative design which
is typically negligible for the widths given in Table 5.1.
4. Refer to Sheet 4 of 6 for transverse stiffener beam layouts and Sheet 5 of 6 and Sheet 6 of 6 for deck thickness requirements.
X
Y I Y Table 5.1 – Deck Panel Summary
| |
IX. W G. WI e * Western Species Glulam Southern Pine Glulam
Hº- Nominal Nominal Total (1-1/2 in. thick laminations) (1–3|8 in. thick laminations)
< | | Roadway Bridge Number
Width, Width, Of Panel Width, Bridge Width Panel Width, Bridge Width
Y X Panels W Out-Out W Out-Out
12 ft Roadway Width 16 ft Roadway Width p p
End view (ft) (ft) (in.) (ft) (in.) (ft)
12 14 4 42.0 14.00 42.6 14.20
16 18 5 43.5 18.13 44.0 18.33
= Nominol bridge width (out-out)
= Nominol roodwoy width 24 26 6 52.5 26.13 52.3 26.13
Deck ponel width 28 30 7 51.0 29.75 52.3 30.47
Double-Lane Bridges 32 34 8 51.0 34.00 50.9 33.92
X X
ſº Y ſº ſt ſº Y ſº
| | | | | |
IX. We WI IX. WL IX. Wo Ç M
-- | | | | —l | | | | |
24 ft Roadway Width 28 ft Roadway Width 32 ft Roadway Width
End view End view
The bridge superstructures depicted on these drawings were Longitudinal Glulam Panel Decks Deck Panel Layouts
developed under a cooperative research agreement between
the Federal Highway Administration, the USDA Forest Service,
}

Forest Products Laboratory, and Laminated Concepts, Inc.
Standard Plans for Timber Bridge Superstructures December 2000 Sheet 3 of 6
Transverse Stiffener Beam Layout
Notes
3/4 in. Ø dome heod bolt 3/4 in. Ø dome heod bolt 1. Transverse stiffemer beams shall be attached to the deck underside to transfer loads between adjacent panels. Transverse stiffener
beams are placed at midspan and at intermediate locations, while not exceeding a 10-ft spacing (see Table 5.2). For unskewed and skewed
|| || crossings, stiffener beams shall be placed parallel to the abutments.
|| Slot holes | Slot holes tº g e tº e e
| in chonnel in glulom 2. Transverse stiffener beams shall be manufactured of glulam timber or steel. For Western Species glulam, a Combination2beam measuring
deck deck || 6–3|4-in-wide and 4-1/2-in.-deep may be used. For Southern Pine glulam, a Combination 48 beam, 5-in.-wide and 5-1/2-in.-deep
| | | || may be used. For steel, a miscellaneous channel (MC6x15.1) beam may be used. Other glulam combinations Or steel shapes may be used
||
|| provided they are of sufficient size and stiffness to provide a minimum E'l of 80,000 lb-in'.
Cut wosher Steel stiffener Beom –74– `s Glulom stiffener bedn, 3. Transverse stiffener beams shall be attached to the deck panels with 3/4-in.-diameter through-bolts placed approximately 6-in. from
onci nut see Note 2. gº / see Note 2. paneledges. For the exterior panels, the transverse stiffener beam shall extend a minimum of 18-in. beyond the panel interface. Bolt holes
Molleoble iron wosher in the transverse stiffener beams shall be slotted (twice bolt diameter) in the direction of the stiffener beam length to allow for possible
ond nut deck panel swelling.
Steel Channel Connection Glulam Beam Connection gº wº
Side View Side View Table 5.2 – Stiffener Requirements
Bridge Number Stiffener
Length Of Spacing, S
(ft) Stiffeners (ft)
Bridge Length | Bridge Length | 12 1 6.0
S S S S | S | S º S R S | 14 1 7.0
| | 16 1 8.0
Skew | | | 18 1 9.0
[] ſ | tºº | 90
É. É. É. 18 & & & 18 20 3 5.0
O O O O O O
| | | | | | | | | 22 3 5.5
| | || | | | | | | | | 24 3 6.0
191 Iol 191 19, 19, 19,
º º º ſº ſº ſº 26 3 6.5
º ſº | | |
Width Ponel width Width
| | | |-- | | | | | | º | | 28 3 7.0
É. Hº- §—==} = *—# 30 3 7.5
O 6" O O 'o 6” 'o 'o ge
| Tſ' | | | || | 32 3 8.0
| | || | | | | | | | |
É. É. :- 1% Iol Iol 34 3 8.5
O O O Go o' 'o' 'o' 00
L L L 18 |J |J [] 18 36 3 9.0
38 3 9.5
eºs S – Transverse stiffener beam spacing
Transverse Stiffener Layout - Unskewed Crossings
Transverse Stiffener Layout - Skewed Crossings.
Plan View Plan View
The bridge superstructures depicted on these drawings were of T L 0 a ſº 0 º
under a 89 ñº ongitudinal Glulam Panel Decks Stiffener Beam Layout
the Federal Highway Administration, the USDA Forest Service, % Cº
Forest Products Laboratory, and Laminated Concepts, Inc. °sº Standard Plans for Timber Bridge Superstructures December 2000 Sheet 4 of 6

31
Table 5.3 — Longitudinal Glulam Deck Design Table for Single Lane Bridges
Table Continued
AASHTO HS20–44 Loading AASHTO HS25–44 Loading
Bridge || Span Minimum Required F.' (lblin’) and E’ (x10°lblin") Walues
Length || L || Required for Actual Deck Thickness” (t) Ranging from 8–% to 16–%—in.
(ft) (ft) Walue
8% | 8% | 10% | 10% | 12% | 1.4% | 16% || 8% | 8% | 10% | 10% | 12% | 1.4% | 16%
F.' 891 842 1,088 || 1,028 || 720 | 688
12 11 E' for L/360|| 0.73 || 0.67 0.92 || 0.84 || 0.49 || 0.45
E" for L1500|| 1.02 || 0.93 1.27 | 1.17 || 0.68 || 0.63
F.' 1,061 | 1,003 || 705 674 1,290 | 1,220 || 855 || 817 | 635
14 13 E’ for LI360|| 1.01 || 0.93 || 0.54 || 0.50 1.26 | 1.15 || 0.67 || 0.62 || 0.42
E" for L1500|| 1.41 | 1.29 || 0.75 || 0.70 1.75 | 1.60 || 0.93 || 0.86 || 0.58
F.' 1,235 | 1,168 || 822 786 612 1,496 || 1,413 || 993 || 948 || 737
16 15 E’ for L/360|| 1.32 | 1.21 || 0.70 || 0.65 || 0.44 1.65 | 1.52 || 0.88 0.82 || 0.55
E’ for L1500|| 1.83 || 1.68 0.97 || 0.91 || 0.61 1.22 | 1.14 || 0.77
F.' 1,411 || 1,335 | 941 900 702 1,6U9 || 1,132 || 1,082 | 842 || 631
18 17 E’ for LI360|| 1.67 | 1.53 || 0.89 || 0.83 || 0.56 1.92 | 1.11 | 1.04 || 0.70 || 0.44
E" for L1500 1.23 | 1.15 || 0.78 1.54 || 1.44 || 0.97 || 0.62
F.' 1,505 || 1,063 || 1,017 | 794 1,273 || 1,217 | 948 712
20 19 E' for LI360 1.89 || 1.09 || 1.02 || 0.69 1.37 || 1.27 || 0.86 || 0.55
E’ for L1500 1.52 | 1.41 0.96 1.90 | 1.77 | 1.20 || 0.76
F.' 1,188 || 1,136 || 889 || 670 1,417 | 1,354 || 1,057 || 795 621
22 21 E' for L/360 1.32 || 1.23 || 0.83 || 0.53 1.65 | 1.53 | 1.04 || 0.66 || 0.44
E" for L1500 1.83 || 1.70 | 1.15 || 0.73 1.44 || 0.91 || 0.62
F.' 1,316 || 1,259 || 986 || 745 1,167 || 879 688
24 23 E' for LI360 1.74 || 1.62 | 1.09 || 0.69 1.37 || 0.87 || 0.58
E" for L1500 1.52 || 0.96 1.20 || 0.81
a — Western species glulam sizes are 8 %, 10%, 12%, 14%, and 16 %—in.;
Southern pine glulam sizes are 8%, 10%, 12%, 14%, and 16%—in.
HS20-44 HS25-44
º * Required Minimum Required Wales
(ft) (ft) Walue t Actual ºº:: º
anging from 8–% to 16–%—in.
12% | 1.4% | 16% || 12% | 1.4% | 16%
F.' 1,114 | 842 663 || 1,315 || 991 777
26 25 E’ for LI360 || 1.41 || 0.90 || 0.60 || 1.76 | 1.12 0.76
E’ for L/500 || 1.96 1.24 || 0.84 1.56 | 1.05
F.' 1,268 || 959 755 1,127 | 884
28 27 E' for L/360 || 1.75 1.11 0.75 1.39 0.94
E' for L1500 1.54 || 1.04 1.93 || 1.30
F.' 1,078 || 849 1,265 || 993
30 29 E" for L/360 1.35 || 0.91 1.68 || 1.13
E' for L1500 1.87 | 1.26 1.57
F.' 1,199 || 945 1,404 || 1,103
32 31 E’ for LI360 1.59 || 1.07 1.99 || 1.34
E' for L1500 1.49 1.86
F.' 1,322 || 1,042 1,214
34 33 E' for L/360 1.84 || 1.24 1.55
E’ for L1500 1.72
F.' 1,147 1,333
36 35 E’ for L/360 1.42 1.78
E’ for L1500 1.97
F.' 1,267
38 37 E" for L/360 1.61
E’ for L1500
Table instructions
The table on this sheet is for determining the required deck thickness for longitudinal glulam timber decks for single-lane bridges
(14- and 18-ft nominal widths). The criteria for selecting deck thickness are based on span length, vehicle loading, live load
deflection limit, and thematerial properties of the glulam panels. The table provides the minimum required allowable design values
for bending strength (F,') and modulus of elasticity (E') based on the vehicle live load, deck deadload, and an assumed dead load
of 10 lb/ft’ for the railing/curb and 38 lb/ft’ for the asphalt wearing surface. Allowable design values for horizontal shear (F,')
are not listed because horizontal shear is not critical for shallow deck sections. Blank cells in the table denote cases where the
required design walues exceed those typically available or that result in excessively conservative designs.
The table may be used in two ways. When the combination and material species of glulam are known, the designer must
determine the allowable design values for the material, then compare them to the values given in the table. The allowable design
values must be greater than or equal to the table values based on the selected deck thickness, span length, vehicle loading, and
deflection limit. Alternatively, when the combination and material species are unknown, minimum required F, and E' values may
be obtained from the table based on the span length, deck thickness, loading, and deflection limit. A combination and species
of glulam that meets these minimum allowable design values may then be selected. The following procedures are recommended
for table use:
Material Combination and Species Known
1. Determine the required design criteria for
a. span length measured center-to-center of bearings;
b. vehicle loading, AASHTO HS20–44 or HS25–44; and
C. live load deflection limit, L/360 or L1500.
2. Compute the allowable design values for the glulam combination and species using the following equations:
F, - F. Cu CF Co E" - ECM
F, - tabulated bending stress (blin’)
C; - size factor
Cw - wet service factor
where F, - allowable bending stress (blin’)
E' - allowable modulus of elasticity (lblin’)
E - tabulated modulus of elasticity (blin’
Co - load duration factor
3. Enter the table and select a deck thickness based on the design criteria and allowable material properties previously
determined. The allowable material property values for F, and E' must be greater than or equal to the corresponding table values
for the deck thickness selected. If they are not, the design criteria and/or material properties must be revised until acceptable
values are achieved.
Material Combination and Species Unknown
1. Determine the required design criteria for
a. span length measured center-to-center of bearings;
b. vehicle loading, AASHTO HS20–44 or HS25–44; and
C. live load deflection limit, L/360 or L1500.
2. Enter the table and select a deck thickness based on the design criteria. Note the required minimum allowable values for F,"
and E'.
3. Select a Glulam Combination that provides the minimum allowable designvalues. Glulam combinations should be selected from
the "members stressed primarily in axial tension or compression" table.
The bridge superstructures depicted on these drawings were
developed under a cooperative research agreement between
the Federal Highway Administration, the USDA Forest Service,
Forest Products Laboratory, and Laminated Concepts, Inc.
tº
@
Longitudinal Glulam Panel Decks
Design Table - Single Lane Bridges
Standard Plans for Timber Bridge Superstructures
December 2000 Sheet 5 of 6


32
Table 5.4 – Longitudinal Glulam Deck Design Table for Double-Lane Bridges
AASHTO HS20–44 Loading | AASHTO HS25–44 Loading
Bridge || Span Minimum Required F,"|blin") and E’ (x10°lblin") Walues
Length || L Required for Actual Deck Thickness” (t) Ranging from 8–% to 16–%—in.
(ft) (ft) Walue
8% 8% | 10% 10% | 12% | 1.4% 16%|| 8% | 8% | 10% 10% | 12% | 1.4% | 16%
F," || 986 || 932 || 653 || 624 1,207 || 1,140 || 798 || 762
12 11 || E' for L/360 || 0.82 || 0.75 || 0.44 || 0.41 1.03 || 0.94 || 0.54 || 0.51
E" for L1500 || 1.14 | 1.05 || 0.61 || 0.56 1.43 | 1.31 || 0.76 || 0.71
F," || 1,170 | 1,106 || 776 || 742 1,426 1,348 || 944 || 902 || 700
14 13 || E' for L/360 || 1.13 | 1.04 || 0.60 || 0.56 1.41 | 1.29 || 0.75 || 0.70 || 0.47
E" for L1500 || 1.57 | 1.44 || 0.83 || 0.78 1.96 || 1.79 | 1.04 || 0.97 || 0.65
F,' || 1,356 | 1,282 | 902 || 862 | 671 1,647 | 1,556 || 1,092 || 1,043 || 811 || 606
16 15 || E' for L/360 || 1.47 | 1.35 | 0.78 0.73 || 0.49 1.85 | 1.69 || 0.98 || 0.91 || 0.62 || 0.39
E" for L1500 1.88 || 1.09 || 1.01 || 0.68 1.36 | 1.27 || 0.86 || 0.54
F," || 1,545 | 1,461 | 1,029 || 983 || 766 1,241 | 1,186 || 922 || 690
18 17 || E' for L/360 || 1.87 | 1.71 || 0.99 || 0.92 || 0.62 1.24 || 1.15 || 0.78 || 0.50
E’ for L1500 1.38 || 1.28 || 0.87 1.72 | 1.60 | 1.08 || 0.69
F.' 1,158 || 1,107 || 864 || 650 1,392 || 1,330 | 1,036 || 776 || 606
20 19 || E' for L/360 1.22 | 1.13 || 0.77 || 0.49 1.52 | 1.42 || 0.96 || 0.61 || 0.41
E" for L1500 1.69 || 1.57 | 1.06 || 0.68 1.97 || 1.33 || 0.85 || 0.57
F.' 1,290 | 1,233 || 964 || 726 1,544 || 1,476 | 1,150 | 864 || 674
22 || 21 || E' for L/360 1.46 | 1.36 || 0.92 || 0.58 1.83 || 1.70 | 1.15 || 0.73 || 0.49
E’ for L1500 1.89 | 1.28 || 0.81 1.60 | 1.02 || 0.69
F.' 1,424 || 1,362 | 1,065 || 803 || 630 1,266 || 952 || 745
24 || 23 || E' for L/360 1.92 || 1.79 | 1.21 || 0.77 || 0.52 1.51 || 0.96 || 0.65
E’ for L1500 1.68 || 1.07 || 0.72 1.34 || 0.90
a – Western species glulam sizes are 8 %, 10%, 12%, 14%, and 16%—in.;
Southern pine glulam sizes are 8%, 10%, 12%, 14%, and 16%—in.
Bridge
Length
(ft)
Span
l
(ft)
Required
Walue
F.'
E’ for L/360
E" for L1500
F.'
E' for L/360
E’ for L1500
F.'
E’ for L/360
E" for L/500
F.'
E" for L/360
E" for L1500
F.'
E’ for L/360
E’ for L/500
F.'
E’ for LI360
E’ for L1500
F.'
E’ for L/360
E’ for L1500
12%
1,201
1.56
1,364
1.94
Table Continued
HS20-44
HS25-44
Minimum Required Walues
for Actual Deck Thickness" (t)
14%
907
0.99
1.38
1,031
1.23
1.71
16%
712
0.67
0.93
810
12%
1,424
1.95
14%
1,071
1.24
1.72
16%
839
0.84
1.16
Table instructions
The table on this sheet is for determining the required deck thickness for longitudinal glulam decks for double-lane bridges
(26-, 30–, and 34—ft nominal widths). The criteria for selecting deck thickness are based on span length, vehicle loading,
live load deflection limit, and the material properties of the glulam panels. The table provides the minimum required allowable
design values for bending strength (F,') and modulus of elasticity (E') based on the vehicle live load, deck dead load, and an
assumed dead load of 10 lb/ft’ for the railing|curb and 38 lb/ft’ for the asphalt wearing surface. Allowable design values for
horizontal shear (F,') are not listed because horizontal shear is not critical for shallow deck sections. Blank cells in the table
denote cases where the required design values exceed those typically available or that result in excessively conservative
designs.
The table may be used in two ways. When the combination and material species of glulam are known, the designer must
determine the allowable design walues for the material, then compare them to the values given in the table. The allowable
design walues must be greater than or equal to the table values based on the selected deck thickness, span length, vehicle
loading, and deflection limit. Alternatively, when the combination and material species are unknown, minimum required F,"
and E' values may be obtained from the table based on the span length, deck thickness, loading, and deflection limit. A grade
and species of glulam that meets these minimum allowable design values may then be selected. The following procedures are
recommended for table use:
Material Combination and Species Known
1. Determine the required design criteria for
a. span length measured center-to-center of bearings;
b. vehicle loading, AASHTO HS20–44 or HS25–44; and
C. live load deflection limit, L/360 or L1500.
2. Compute the allowable design walues for the combination and species of the glulam using the following equations:
F, - F. Cu CF Co E" - ECM
F, - tabulated bending stress (blin’)
Cº - size factor
Cu - wet service factor
F, - allowable bending stress (blin’)
E' - allowable modulus of elasticity (lblin’)
E - tabulated modulus of elasticity (lblin’)
Cp - load duration factor
where
3. Enter the table and select a deck thickness based on the design criteria and allowable material properties previously
determined. The allowable material property values for F, and E' must be greater than or equal to the corresponding table
values for the deck thickness selected. If they are not, the design criteria and/or material properties must be revised until
acceptable values are achieved.
Material Combination and Species Unknown
1. Determine the required design criteria for
a. span length measured center-to-center of bearings;
b. vehicle loading, AASHTO HS20–44 or HS25–44; and
C. live load deflection limit, LI360 or L1500.
2. Enter the table and select a deck thickness based on the design criteria. Note the required minimum allowable values for
F, and E'.
3. Select a Glulam Combination that provides the minimum allowable design values. Glulam combinations should be selected
from the "members stressed primarily in axial tension or compression" table.
The bridge superstructures depicted on these drawings were
developed under a cooperative research agreement between
the Federal Highway Administration, the USDA Forest Service,
Forest Products Laboratory, and Laminated Concepts, Inc.
@
Longitudinal Glulam Panel Decks
Design Table - Double Lane Bridges
Standard Plans for Timber Bridge Superstructures
December 2000 Sheet 6 of 6



33
Suggested Substructure Connections
Notes
* * 1. This page presents suggested substructure connection details for longitudinal timber deck superstructures with timber abutments.
Deck | | If concrete abutments are used, threaded bolt inserts or anchor bolts, cast or drilled into the concrete, should be used. Connections
eC | | Deck should be designed to resist appropriate design loads (including seismic) and be based on site-specific conditions.
H 1/2-in. gop & ſº - º & e º ſº tº . º
| 2. These five longitudinal deck system standards assume 12-inch bearing lengths at all supports. Site-specific seismic conditions
= = \Z[= = - may require additional bearing length. All bridges should be evaluated by a qualified professional engineer for AASHTO seismic
| Bockwoll requirements.
|| plonks
Z 6 x 6 x 1 /2-in. 3. Superstructures should be attached to the substructure soon after placing the timber deck, except stress-laminated decks should
Continuous full-width not be connected to the substructure until after the first bar re-tensioning, due to possible transverse deck movement.
4. Deck attachment bolts should be 3/4-in. nominal diameter and have dome-type heads. Bolt holes should be pre-bored to a diameter
of 13/16-in. The transverse spacing of connectors to anchor the superstructure to the substructure should not exceed 4-ft over the
width of the bridge.
5. Steel angles should meet the requirements for ASTM standard A36. The use of transversely slotted bolt holes will allow for
Thru-Bolt Abutment Connecti On Steel Angle Abutment Con nection transverse movement of the deck in-service and is recommended, especially for glulam decks.
Side view Side view 6. All steel components should be galvanized in accordance with AASHTO standards M111 and M232, or otherwise protected from
corrosion.
7. All borings done after preservative treatment should be field treated, in accordance with AASHTO M133, with an appropriate wood
tº e ſº tº * preservative.
Minimum bedring length is 12 in. for all coses
All bolts ore minimum 3/4 in. Ø 8. The use of neoprene bearing pads, 1/2-in. minimum thickness, is recommended for concrete abutments. Plain elastomeric rubber,
50 to 60 durOmeter, should be specified. Timber decks on timber abutment caps do not usually require bearing pads.
Premolded joint
/. filler
ƺ (~\ AºA
Deck II II II
| | Deck |
|| || ||
| | || |
| t
1/2-in. gop Z 6 x 6 x 1/2-in. continuous full-width ||
||
||
||
The 24 in. bearing length shown \
includes o 12 in. cop plus steel
ongles. Verify odequocy for site
specific seismic conditions.
Multiple Simple Span Bent Connection Continuous Span Bent Connection
Side view Side view
The bridge superstructures depicted on these drawings were of T Longitudinal Deck Superstructures Substructure Connection Details
developed under a cooperative research agreement between 14 ń. 9 pe

the Federal Highway Administration, the USDA Forest Service, w C2;
Forest Products Laboratory, and Laminated Concepts, Inc. *nº dº
Standard Plans for Timber Bridge Superstructures December 2000 Sheet 1 of 1
Glulam Stringer and Transverse Glulam Deck
Beam Systems:
The bridge superstructures depicted on these drawings were
- * Glulam Stringer and Transverse Deck Title Page
developed under a cooperative research agreement between §
the Federal Highway Administration, the USDA Forest Service, *. Qº
Forest Products Laboratory, and Laminated Concepts, Inc. *:::s Standard Plans for Timber Bridge Superstructures December 2000 Sheet 1 of 11
35


Plan, Profile, and Section Views
Glulom diophrogms, see Note 5.
Glulom deck ponels, see Note 4.
| L |
Length
|- Roodwoy Width —
|; 1–
|
N. Glulom stringers,
Steel or glulom diophrogm,
see Note 5.
Wearing surfoce,
see Note 9.
L=Bridge spon meosured
c–c of bearings
Length=Bridge length measured
out-out
Width=Bridge width measured
see Note 5.
out-out
Substructure shown for
illustrotion only,
see Note 6.
Bridge roiling, see Note 8.
General Notes
DESIGN
1. These drawings are for glulam stringer bridges with transverse glulam panel decks. The designs are
applicable for single- and double-lane and unskewed and skewed bridges up to 80-ft long. Design truck
loading is AASHTO HS 20–44 or HS 25–44 with a live load deflection limit of L1500.
2. The designs comply with the 1996 Standard Specifications for Highway Bridges, with 1998 Interims,
published by the American Association of State Highway and Transportation Officials (AASHTO), except
where noted. Glulam stringers were designed assuming dry-use conditions (CM - 1.0), except for
bearings which were assumed to be wet-use conditions (CM = 0.53). Stringer design live load deflection
is limited to L1500. Stringers should be specified with a minimum camber equal to 3 times the dead load,
but not less than % inch. Glulam deck panels were designed as non-interconnected panels continuous
Over more than two spans. Glulam deck panels may also be interconnected using steel dowels (refer to
AASHTO for detailed design information). To account for the effects of span continuity, maximum
moment and deflection are reduced to 80 percent of equivalent simple-span walues. Deck panel design
live load deflection is limited to a maximum of 0.10-in.
3. Minimum required timber design walues are provided for single-span bridge lengths of 20- to 80-ft
in 2-ft increments. Stringer configuration and size requirements for both unskewed and skewed bridges
are given on Sheet 3 of 11 for single-lane roadway widths of 12– and 16—ft, and on Sheet 4 of 11 for
double-lane roadway widths of 24- and 28-ft, and On Sheet 5 of 11 for double-lane roadway widths
Of 32– and 36-ft.
4. Deck panels are 5-118-in.-thick (6-in. nominal) and are typically 4-ft wide. The number, width, and
layout of deck panels for unskewed and skewed bridges are shown on Sheet 6 of 11 and Sheet 7 of 11,
respectively. Deck panels are attached to supporting stringers with 5/8-in. diameter dome-head bolts
and cast aluminum alloy deck brackets as shown On Sheet 8 of 11.
5. Lateral support for stringers is provided by glulam or steel diaphragms. Diaphragm layout and
connection requirements are given on Sheet 9 of 11 for glulam and Sheet 10 of 11 for steel.
6. The design assumes a uniform stringer bearing length of 12-in. at both bridge ends and a span length,
L, measured Center-to-center of bearings. A longer bearing length will result in a slightly more
conservative design. Substructure connection details are provided on Sheet 11 of 11.
7. Multiple span bridges may be constructed using a series of simple spans based on the designs
presented in these drawings. Multiple span continuous bridges are also commonly used and may be more
economical but require site-specific design.
8. Bridge rail and curb drawings are for illustration purposes only and must be designed based on site
specific requirements. Deck designs are based on an assumed deadload of 10 lb/ft’ for the rail and curb
system. Crashworthy rail designs are available in Development of Two Il-2 Bridge Railings and
Transitions for Use on Transverse Glue—laminated Deck Bridges (Faller et al. In Press)
9. An asphalt wearing surface with a geotextile fabric or membrane is recommended for most timber
bridge applications. Designs are based on an assumed dead load of 38 lb/ft’ for an asphalt wearing
surface (approximately 3-in.). Refer to Page 53 for recommended asphalt wearing surface construction
details.
10. These designs are intended for informational purposes only and, due to potential changes in design
requirements and use conditions, should be verified by a qualified professional engineer.
MATERIAL AND FABRICATION
Wood
11. Glulam shall comply with the requirements of AASHTO M168 and ANSI/AITC A190.1 and shall be
manufactured to an industrial appearance grade using wet-use adhesives.
12. Glulam stringers are limited to Western and Southern Pine species treated with a suitable oilborne
preservative. Refer to Sheet 3, 4, and 5 of 11 for stringer designations and sizes. Stringers consist of
glulam bending combinations with horizontal laminations. Deck panels consist of glulam axial
combinations with vertical laminations.
13. Insofar as is practical, all glulam shall be cut, drilled, and completely fabricated prior to pressure
treatment with preservatives.
Preservative Treatment
14. All glulam shall be treated in accordance with AASHTO M133 and AWPA Standard C14 with one of
the following preservatives:
a. Coal tar creosote conforming to AWPA Standard P1|P13
b. Suitable oilborne preservative conforming to AWPA Standard C28 and P8 in hydrocarbonsolvent, Type
A or Type C.
15. Treated material shall follow post-treatment requirements summarized in Best Management
Practices for the Use of Treated Wood in Aquatic Environments (WWPl 1996) to ensure all surfaces are
free of excess preservative and chemicals are fixated in the wood.
16. Preservative treatment shall beinspected and certified inaccordance with AASHTOM133 and AWPA
Standard M2.
Steel Fasteners and Hardware
17. Steel plates and shapes shall comply with the requirements of ASTM A36. Cast aluminum alloy deck
brackets shall comply with the requirements of ASTM A356.
18. Bolts and lag screws shall comply with the requirements of ANSI/ASME Standard B18.2.1-1981,
Grade 2.
19. All steel components and fasteners shall be galvanized in accordance with AASHTO M111 or
AASHTO M232 or otherwise protected from corrosion.
20. Washers shall be provided under bolt and lag screw heads and under nuts that are in contact with
wood. Washers may be omitted under heads of special timber bolts or dome-head bolts when the size
and strength of the head is sufficient to develop connection strength without wood crushing.
CONSTRUCTION
21. All wood and metal components shall be handled and stored carefully so as not to damage the
material. If damage does occur, exposed untreated wood shall be field treated in accordance with
AASHTO M133. Damage to galvanized surfaces shall be repaired with a cold galvanizing compound or
Other approved coating.
22. Stringers are often placed with bearing hardware attached. During stringer placement, diaphragms
are attached and connections are hand-tightened to allow for minor adjustments as remaining
diaphragms are placed. After all diaphragms are placed, and alignment is verified, connections should be
securely tightened.
23. Deck panels should be placed after stringers and diaphragms are set and secured. A common
construction procedure is to place the first panel at midspan, then sequentially place remaining panels
outward toward the abutments. Attachment hardware should be hand tightened as the panels are placed,
then securely tightened after all panels are placed and aligned.
24. The application of a bituminous sealer is recommended to prevent excessive wood checking in areas
where the wood end grain is exposed. Tops of glulam beams and vertical joint surfaces, between glulam
deck panels, should also be coated to minimize moisture penetration. Any commercially available roofing
cement is effective.
The bridge superstructures depicted on these drawings were
developed under a cooperative research agreement between
the Federal Highway Administration, the USDA Forest Service,
Forest Products Laboratory, and Laminated Concepts, Inc.
Glulam Stringer and Transverse Deck
Superstructure Drawings and General Notes
Standard Plans for Timber Bridge Superstructures
December 2000 Sheet 2 of 11




36
Stringer Configuration and Size - 12-ft Roadway Width
24 in.
14 ft out-out width
X
12 ft roodwoy width
/ 5–1/8 in. deck
XL
See toble below for
stringer size bosed on
bridge length
4 ot 40 in. spocing
Stringer depth, d
—-
--|H-Stringer width, b
|
Table 6.1 — Glulam Stringer Sizes for Single Lane Bridges with a 12-ft Roadway Width
24 in. —-
18 ft out-out width
Stringer Configuration and Size - 16-ft Roadway Width
X
16 ft roodwoy width
y--wº in. deck
XL
See toble below for
stringer size bosed on
bridge length
|
|-
5 ot 42 in. spocing
|
Stringer depth, d
Table 6.2 – Glulam Stringer Sizes for Single Lane Bridges with a 16-ft Roadway Width
–|-saw width, b
|
Stringer Dimensions (in.)
Bridge Bridge e e
Length Span Southern Pine Southern Pine Western Species
24F-W3 26F-W3 24F-W4
(ft) (ft) HS20–44 Loading | HS25–44 Loading HS20–44 Loading | HS25–44 Loading || HS20–44 Loading | HS25–44 Loading
b d b d b d b d b d b d
20 19 16% 177/8 16% 177/3 16% 19%
22 21 177/3 19% 177/8 19% 18 19%
24 23 19% 22 19% 205/6 19% 21
26 25 22 23% 22 23% 21 24
28 27 23% 24% 23% 24% 24 25%
30 29 24% 26% 24% 26% 25% 27
32 31 6% 26% 287/8 6% 26% 27% 27 6% 28%
34 33 27% 6% || 30% 27% 8% 28% 6% 28% 30
36 35 287/6 315/3 287/8 30% 28% 31%
38 37 30% 33 30% 315/3 30 33
40 39 315/3 34% 315/3 33 31% 34%
42 41 33 35% 33 34% 33 36
44 43 34% 37% 34% 35% 34% 39
46 45 35% 38% 34% 37% 36 36
48 47 37% 39% 35% 38% 37% 37%
50 49 38% 38% 371/3 39% 39 39
52 51 397/3 397/8 38% 38% 37% 40%
54 53 397/3 39% 397/3 39% 37% 42
56 55 38% 41% 38% 41% 39 43%
58 57 39% 42% 38% 425/3 40% 8% 45
60 59 41% 8% 44 39% 42% 42 45
62 61 41% 45% 41% 8% || 44 43% 46%
64 63 42% 45% 42% 45% 8% 45 48
66 65 8% 44 46% 42% 46% 46% 49%
68 67 45% 48% 8% || 44 46% 48 51
70 69 46% 49% 45% 48% 49% 48
72 71 46% 49% 45% 49% 49% 49%
74 73 48% 48% 46% 46% 51 51
76 75 48% 48% 48% 10% | * 48 10% 52%
78 77 49% 10% 49% 48% 48% 10% || 49% 54
80 79 10% || 46% 50% 49% 49% 51 55%
Stringer Dimensions (in.)
Bridge Bridge º g *
Length Span Southern Pine Southern Pine Western Species
24F-W3 26F-W3 24F-W4
(ft) (ft) HS20–44 Loading | HS25–44 Loading || HS20–44 Loading | HS25–44 Loading || HS20–44 Loading | HS25–44 Loading
b d b d b d b d b d b d
20 19 16% 19% 16% 177/6 16% 19%
22 21 177/6 19% 177/6 19% 18 19%
24 23 19% 22 177/6 20% 19% 21
26 25 22 22 19% 22 21 22%
28 27 22 23% 205/6 23% 22% 25%
30 29 23% 26% 23% 24% 24 27
32 31 24% 287/8 23% 26% 25% 6% 28%
34 33 26% | 6% 287/8 24% 6% 27% 6% 27 30
36 35 6% 27% 30% 26% 287/6 28% 31%
38 37 287/8 33 6% | 27% 30% 30 33
40 39 30% 33 287/8 31% 33 36
42 41 3.15% 34% 30% 33 34% 37%
44 43 33 37% 3.15% 35% 36 39
46 45 34% 38% 33 37% 37% 36
48 47 35% 39% 34% 38% 39 37%
50 49 37% 37% 35% 39% 36 39
52 51 38% 38% 37% 37% 37% 40%
54 53 39.7/6 39% 38% 37% 39 42
56 55 37% 41% 39% 38% 40% 8% 43%
58 57 38% 425/3 37% 39% 40% 45
60 59 397/8 8% 42% 38% 41% 42 46%
62 61 41% 44 39% 8% 42% 8% 43% 48
64 63 42% 45% 39% 44 45 49%
66 65 8% 44 46% 41% 45% 46% 51
68 67 44 48% sy 42% 46% 48 48
70 69 45% 49% 44 46% 49% 49%
72 71 46% 46% 45% 48% 51 49%
74 73 48% 46% 45% 49% 48 51
76 75 49% 10% 48% 46% 46% 10% 49% 10% | 52%
78 77 10% | * 49% 48% 10% 46% 49% 54
80 79 46% 50% 49% 48% 51 55%
The bridge superstructures depicted on these drawings were
developed under a cooperative research agreement between
the Federal Highway Administration, the USDA Forest Service,
Forest Products Laboratory, and Laminated Concepts, Inc.
ſº
WCZF
*res of
Glulam Stringer and Transverse Deck
Stringer Configuration and Sizes-Single Lane
Standard Plans for Timber Bridge Superstructures
December 2000 Sheet 3 of 11

37
Stringer Configuration and Size - 24-ft Roadway Width
24 in. —- |
26 ft out-out width
24 ft roodwoy width
2^ 5–1/8 in. deck
7 ot 44 in. spocing
Table 6.3 — Glulam Stringer Sizes for Double lane Bridges with a 24-ft Roadway Width
See toble below for
stringer size bosed on
bridge length
| Stringer depth, d
—- H-Stringer width, b
Stringer Dimensions (in.)
Bridge Bridge e *
Length Span Southern Pine Southern Pine Western Species
24F-W3 26F-W3 24F-W4
(ft) (ft) HS20–44 Loading | HS25–44 Loading || HS20–44 Loading | HS25–44 Loading || HS20–44 Loading | HS25–44 Loading
b d b d b d b d b d b d
20 19 177/6 19% 177/8 19% 18 19%
22 21 19% 22 177/3 19% 19% 21
24 23 22 22 205/6 22 21 22%
26 25 22 24% 22 23% 22% 24
28 27 24% 26% 23% 26% 24 25%
30 29 26% 27% 26% 27% 25% 28%
32 31 27% 6% 30% 27% 6% 287/8 27 6% 30
34 33 6% 287/6 315/6 287/8 30% 6% 28% 31%
36 35 30% 33 6% 30% 315/3 30 33
38 37 315/3 34% 315/3 33 31% 34%
40 39 33 35% 33 34% 33 36
42 41 34% 37% 34% 37% 34% 37%
44 43 35% 38% 35% 38% 36 39
46 45 371/3 39% 371/3 39% 37% 37%
48 47 38% 38% 38% 37% 39 37%
50 49 39% 39% 38% 38% 36 39
52 51 38% 4.1% 397/3 397/8 37% 40%
54 53 397/3 42% 38% 41% 39 42
56 55 39% | 8% 44 397/3 425/3 40% 8% 43%
58 57 41% 44 4.1% 8% 44 42 45
60 59 425/3 45% 41% 45% 8% 43% 46%
62 61 8% 44 46% 42% 46% 45 48
64 63 44 48% 8% | * 46% 45 49%
66 65 45% 49% 45% 48% 46% 51
68 67 46% 46% 45% 49% 48 48
70 69 48% 48%. 46% 46% 49% 49%
72 71 48% 49% 48% 48% 51 51
74 73 49% i 49% 49% 49% 48 52%
76 75 46% 10% 50% 49% 10% 49% 10% 49% 10% 2,
78 77 10% || 48% 52% 10% 48% 507/8 51 54
80 79 49% 52% 48% 52% 52% 55%
Stringer Configuration and Size - 28-ft Roadway Width
22.5 in. —-
30 ft out-out width
28 ft roodwoy width
2-8-ve in. deck
8 ot 45 in. spocing
See
toble below for
stringer size bosed on
bridge length
| Stringer depth, d
—- |H-Stringer width, b
Table 6.4 – Glulam Stringer Sizes for Double Lane Bridges with a 28-ft Roadway Width
Stringer Dimensions (in.)
Bridge Bridge Southern Pine Southern Pine Western Species
Length Span 24F-W3 26F-W3 24F-W4
(ft) (ft) HS20–44 Loading HS25–44 Loading HS20–44 Loading HS25–44 Loading HS20–44 Loading HS25–44 Loading
b d b d b d b d b d b d
20 19 16% 19% 16% 177/6 18 19%
22 21 177/3 205/6 177/6 19% 18 21
24 23 19% 20% 19% 20% 19% 22%
26 25 22 233% 205/3 23% 21 24
28 27 23% 24% 23% 24% 24 25%
30 29 24% 26% 24% 26% 25% 27
32 31 26% 287/8 26% 27% 27 6% 28%
34 33 27% 6% 30% 27% 6% 287/8 6% 28% 30
36 35 6% 287/8 315/3 6% 287/8 30% 30 31%
38 37 30% 33 30% 3.15% 31% 34%
40 39 315/3 34% 31% 33 33 36
42 41 33 35% 33 34% 34% 37%
44 43 34% 37% 34% 35% 36 39
46 45 35% 38% 34% 37% 37% 36
48 47.00 37% 397/8 35% 38% 39 37%
50 49 38% 38% 37% 39% 36 39
52 51 39% 397/8 38% 38% 37% 40%
54 53 37% 39% 39% 39% 39 42
56 55 38% 4.1% 38% 41% 40% 8% 43%
58 57 39% 42% 38% 42% 42 45
60 59 41% 8% 44 39% 42% 8% 43% 46%
62 61 41% 45% 41% 8% 44 43% 48
64 63 8% 42% 45% 425/3 45% 45 49%
66 65 44 46% 42% 46% 46% 51
68 67 45% 48% 8% 44 46% 48 48
70 69 45% 49% 45% 48% 49% 49%
72 71 46% 46% 45% 49% 51 51
74 73 48% 48% 46% 46% 48 10% 52%
76 75 49% 10% 48% 48% 10% 48% 10% 49% 52%
78 77 10% 46% 49% 48% 48% 51 54
80 79 46% 50% 49% 49% 51 55%
The bridge superstructures depicted on these drawings were
developed under a cooperative research agreement between
the Federal Highway Administration, the USDA Forest Service,
Forest Products Laboratory, and Laminated Concepts, Inc.
Glulam Stringer and Transverse Deck
Stringer Configuration and Sizes - Double Lane
Standard Plans for Timber Bridge Superstructures
December 2000
Sheet 4 of 11

38
Stringer Configuration and Size - 32-ft Roadway Width
54 ft out-out width
32 ft roodwoy width
2^ 5–1/8 in. deck
:
See to ble below for
stringer size bosed on
bridge length
|=
| 9 ot 45 in. Spocinq
Table 6.5 – Glulam Stringer Sizes for Double Lane Bridges with a 32–ft Roadway Width
sº depth, d
—- | H-Stringer width, b
Stringer Dimensions (in.)
Bridge Bridge Southern Pine Southern Pine Western Species
Length Span 24F-W3 26F-W3 24F-W4
(ft) (ft) HS20–44 Loading HS25–44 Loading HS20–44 Loading | HS25–44 Loading HS20–44 Loading HS25–44 Loading
b d b d b d b d b d b d
20 19 177/3 19% 16% 177/8 18 19%
22 21 177/6 205/6 177/3 19% 18 21
24 23 19% 20% 19% 205/6 19% 22%
26 25 22 22 20% 22 21 24
28 27 22 24% 22 23% 22% 25%
30 29 24% 26% 23% 24% 24 27
32 31 24% 27% 24% 26% 27 6% 28%
34 33 26% 6% 287/6 26% 6% 287/8 6% 28% 30
36 35 6% 287/8 30% 6% 27% 30% 30 31%
38 37 30% 33 287/8 315/3 31% 34%
40 39 31% 34% 30% 33 33 36
42 41 33 35% 315/3 34% 34% 37%
44 43 34% 37% 33 35% 36 39
46 45 35% 38% 34% 37% 37% 36
48 47 371/3 397/8 35% 38% 39 37%
50 49 38% 37% 371/3 397/3 36 39
52 51 397/8 38% 397/6 37% 37% 40%
54 53 371/3 39% 35% 38% 39 42
56 55 38% 41% 371/3 397/8 40% 8% 43%
58 57 397/3 42% 37% 41% 42 45
60 59 397/8 8% 44 38% 42% 43% 46%
62 61 41% 45% 39% 8% 4.25% 8% 45 48
64 63 8% 42% 46% 41% 44 46% 49%
66 65 44 48% 42% 45% 46% 51
68 67 45% 48% 8% 42% 46% 48 48
70 69 46% 49% 44 48% 49% 49%
72 71 48% 46% 45% 49% 51 51
74 73 48% 48% 46% 45% 48 10% 52%
76 75 49% 10% 49% 48% 10% 46% 10% 49% 54
78 77 10% 46% 49% 49% 48% 51 55%
80 79 48% 50% 49% 49% 52% 55%
25.5 in. —-
/T 5–1/8 in. deck
38 ft out-out width
36 ft roodwoy width
Stringer Configuration and Size - 36-ft Roadway Width
|
See toble below for
stringer size bosed on
bridge length
| |Sunse depth, d
|- –
10 ot 45 in. spocing
Table 6.6 — Glulam Stringer Sizes for Double Lane Bridges with a 36-ft Roadway Width
—- H-Stringer width, b
Stringer Dimensions (in.)
Bridge Bridge Southern Pine Southern Pine Western Species
Length Span 24F-W3 26F-W3 24F-W4
(ft) (ft) HS20–44 Loading HS25–44 Loading HS20–44 Loading HS25–44 Loading HS20–44 Loading HS25–44 Loading
b d b d b d b d b d b d
20 19 177/6 19% 16% 177/9 18 19%
22 21 19% 20% 177/8 19% 19% 21
24 23 19% 22 19% 20% 21 22%
26 25 20% 23% 205/6 22 22% 24
28 27 23% 24% 22 23% 24 25%
30 29 24% 26% 23% 26% 25% 6% 27
32 31 26% 27% 24% 27% 27 30
6% 6%
34 33 27% 30% 26% 6% 287/8 28% 31%
36 35 6% 287/8 315/3 6% 27% 30% 30 33
38 37 30% 33 287/8 315/3 31% 34%
40 39 315/3 34% 30% 33 33 36
42 41 33 35% 315/3 34% 34% 39
44 43 34% 38% 33 35% 36 36
46 45 35% 397/8 34% 37% 39 37%
48 47 37% 37% 35% 38% 36 39
50 49 38% 38% 37% 37% 37% 40%
52 51 39.7/6 39% 39% 37% 39 42
54 53 37% 41% 39% 38% 40% 8% 43%
56 55 38% 425/3 37% 39% 40% 45
58 57 39% 8% 44 38% 41% 8% 42 46%
60 59 41% 44 39% 8% 425/3 43% 48
62 61 42% 45% 41% 44 45 49%
64 63 8% 44 46% 41% 45% 46% 51
66 65 45% 48% 8% 42% 46% 48 48
68 67 45% 49% 44 48% 49% 49%
70 69 46% 46% 45% 49% 51 51
72 71 48% 48% 46% 49% 48 10% 52%
74 73 49% 10% 48% 48%. 46% 49% 52%
76 75 46% 49% 48% 10% 48% 10% 51 54
78 77 10% 46% 50% 49% 49% 52% 55%
80 79 48%. 52% 10% 46% 49% 52% 57
The bridge superstructures depicted on these drawings were
developed under a cooperative research agreement between
the Federal Highway Administration, the USDA Forest Service,
Forest Products Laboratory, and Laminated Concepts, Inc.
*S*.
@
*nº of
Glulam Stringer and Transverse Deck
Stringer Configuration and Sizes - Double Lane
Standard Plans for Timber Bridge Superstructures
December 2000
Sheet 5 of 11

39
Deck Panel Layout for Unskewed Bridges
Bridge length
ºms sºme sºme ºm me = m me me me m me ame ºn s = m = ** = * * * = * * * * = m. me me me sm s = * * = * * * * = ** = ** = * = he “ - - - - - - - - - - - -
-C
*
Cy * *m, m sºme m. me am m = m, m = * * * = ** = * = * * * * * * = mm. m wºme ºm me mass = * * * * * * * = - mº m = * * * sºme mºss m = * = * * * * = * * * * = ** = ** = *
C
Q2 * = - sºme me sm m = * = = - * = * = * = * = * * * = ** = = * * = * = * * * * = * = * = * = ** = ** = * = - - - - - - - - - - - - - - - - - - - - -
Top
C
O
Cl
->< H — — — — — — — - - - - - - F – — — — — — H — — — — — — — — — — — — — — — — — — — — H — — — — — — — — — — — — T — — — — — — — — — — — — —
O — — — — — — — — — — — - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - k- — — — — — — — — — — — — — — — — — — — — H – - - - - -
Q)
To
3
O –8— — — — —8–1— — 8- — — —8 + — — — — — — — — — — — — — — — — — — — 4- — — — — — — * = ** = a- = — — — — — — — 4 — — — — — — — — — — — — —
~ Tois sºme º ºs º-©H-5 * = *_* = * * * = m. m. mºss me me m ms me me me m me sm sºme m = * * * * * = ** = * * * = m. me me = | * * * * * * * * * *= m, sºme mºs º mº sºme ºs m. m. * *
> S
º N_
*5 Typical ponel-to-stringer connection, see Sheet 8 of 11.
S] H ––––––––––––––––––F–––––––––––––T ––––––F––––––––––––– F ––––––H––––––
.C. He me = sºme m = m. sº sºme sº - - - * * * = * m sº me m. m. ºm me me mºm, — sm, mº me m. m. me mºm sºme m = - me - me me m = mm mm. ºn mºme me me = * = * = * * = m. m. me me sm - me mºs sº mº
sº
p
3:
§ * = m ms m = - me sºme sºme sº sºme m = He - - - sme = ** = = m, amº am - suº me - sº- = - sº- - - * = ** = = - - - = = - - - - - - - - - - - - - - - * = - - - - = * =
º }= me me sº- a sº sº- smºs = * * = * * * * = * = ** = me me mºm ammº m = – * = sº me sº sº sº º R = R = * * | * = ** = me sm em. m = * * * * * * = me me me ºm, sº m emº me mº ºm º º
*-
CO
}= m = * = * * : * * = * = a- - - m a.m. ºne sºme me m = m, me m me me — — — — — — — T — — — — — }* * * * * = m. º me me me me me me = * = sºme sº me wº
X X
End Interior deck ponel width = 48 in. End
pone panel
width width
Plan view
Notes
1. This sheet depicts glulam deck panel layouts for unskewed bridges. Refer to Sheet 7 of 11
for deck panel layouts for skewed bridges.
2. All deck panels are 5 1/8-in-thick with a standard interior panel width of 48-in. The
required number of interior deck panels and the end panel width (X) are based on bridge length
and are given in Table 6.7. Panel length is equal to the Out-out deck width.
3. Deck panels are attached to the supporting stringers with cast aluminum deck brackets and
5/8-in.-diameter bolts as shown on Sheet 8 of 11.
Table 6.7 – Deck Panel layout
End Panel
Width,
Number of
Interior
Panels
The bridge superstructures depicted on these drawings were
developed under a cooperative research agreement between
the Federal Highway Administration, the USDA Forest Service,
Glulam Stringer and Transverse Deck
Deck Panel Layout - Unskewed Bridges


Forest Products Laboratory, and Laminated Concepts, Inc.
Sheet 6 of 11
Standard Plans for Timber Bridge Superstructures
December 2000
Deck Panel Layout for Skewed Bridges
Notes Table 6.8 – Deck Panel layout
1. This sheet depicts glulam deck panel layouts for skewed bridges. Refer to * Skewed No. Of
e Sheet 6 of 11 for deck panel layouts for unskewed bridges. Bridge End Panel i.
| Bridge length | Length Width, X Panels
2. All deck panels are 5 1/8-in-thick with a standard interior panel skewed (ft) (ft)
width (W) of 48-in. (see Detail A). The required number of interior deck panels 20 4 3
and the end panel skewed width (X) are based on bridge length and are given in
Table 6.8. The perpendicular deck panel width (W) varies based on skew angle 22 3 4
and is calculated using the equation in Detail A. Panel length is equal to the 24 4 4
Out-Out deck width measured parallel to the skew.
26 3 5
3. Deck panels are attached to the supporting stringers with cast aluminum deck 28 4 5
brackets and 5/8-in.-diameter bolts as shown on Sheet 8 of 11. 30 3 6
t; 32 4 6
O
# Typicol ponel-to-stringer connection, see Sheet 8 of 11. 34 3 7
: 36 4 7
# 38 3 8
§ 40 4 8
OD ongle, 9 42 3 9
44 4 9
46 3 10
48 4 10
50 3 11
52 4 11
54 3 12
X | | X | 56 4 12
Skewed g e e "Skewed
end ponel Interior skewed deck ponel width (Ws) = 48 in. end ponel 58 3 13
width width
60 4 13
Plan view
62 3 14
64 4 14
66 3 15
Ø
68 4 15
Wp Wp = (Ws * Cos @) for interior ponels 70 3 16
Wp = (X • Cos @) for end ponels 72 4 16
where 74 3 17
Wp = perpendiculor ponel width (in.)
Ws = skewed ponel width (in.) 76 4 17
X = skewed end ponel width (see Toble 6.8) 78 3 18
Ø = skew ongle
: | 80 4 18
Detail A - Panel Widths
Plan view
The bridge superstructures depicted on these drawings were of T Glulam Stringer and Transverse Deck
developed under a cooperative research agreement between
the Federal Highway Administration, the USDA Forest Service,
Forest Products Laboratory, and Laminated Concepts, Inc.
Deck Panel Layout - Skewed Bridges
Standard Plans for Timber Bridge Superstructures
December 2000 Sheet 7 of 11



41
Deck Panel Attachment Details
1 in. long-T
hole slot
H |-3 in.
1 in.
Deck Bracket
Side view
5/8 in. dome head bolt
ſh. E3/8 in. (typicol)
T
3–3/8 in.
A -l — –A- — —A- — –A- — l- A
|-4-1/8 in–
Deck Bracket
End view
II T
|| ||
Il
S
| 5 in.
Cost oluminum olloy 1-1/2 in. |
deck brocket Continuous / 3/4 in.
routed groove
Glulom stringer
Deck Panel Connection Groove Option
End view Side view
Deck Panel Connection Placement - Unskewed Bridges
48 in. End ponel width, X
diometer
Notes
1. Deck panels are attached to the supporting stringers with %—in.-diameter dome-head bolts and cast
aluminum alloy deck brackets. The deck brackets are typically available from glulam manufacturers and bridge
N-9/ 16 in. hole suppliers. For additional information on the cast aluminum deck brackets and other deck attachment
alternatives, refer to Timber Bridges: Design, Construction, Inspection, and Maintenance (Ritter 1990).
2. As shown on the drawings, deck brackets connect to stringer sides in *- by 8-in. slots or in continuous
%—in.-wide grooves.
3. When placing the deck panels, brackets should be attached to the stringers and nuts hand tightened. Nuts
should not be completely tightened until all deck panels are in place and properly aligned.
Routed slot-'
Slot Option
Side view
Deck Panel Connection Placement - Skewed Bridges
See Sheet 7 of 11 for nomencloture.
* * n Continuous routed
1-1/2 in * * = In Routed slot 1-1/2 inj 1-1/2 i ſOOV
ºs º ºsmº ºme me me *H ------9.-- --&== ºtº-3 J/ =====?-----Hº-> ========E===== ~ groove
emº, º ºs ===T- º Q stringer _[Fif TTTTTTTT — — — Q: stringer | A L_ — — {- Q stringer —4gº ºs º ºs º- tº— — =4== Q stringer
-F#-------F#5------- -C-T-7-71 – — — — — — — — — — — ++5=- º 1 ft 1 ft º 1 ft He y O
6 in.--| |-|--|--|--|--" |- 6 in. 6 in.— — – H-6 in. I I | ° 2,
tº 6 in e 6 .
~TS_ ~TS 6 in ºn.
-— Ws = 48 in. WS = X
Interior Panel End Panel
Plan view Plan view Interior Panel End Panel
Plan view Plan view
The bridge superstructures depicted on these drawings were of T O |
under a ag 14 W Glulam Stringer and Transverse Deck Deck Panel Attachment Details
the Federal Highway Administration, the USDA Forest Service, Ž
Forest Products Laboratory, and Laminated Concepts, Inc. Standard Plans for Timber Bridge Superstructures December 2000 Sheet 8 of 11







42
Glulam Diaphragm Layout
Bridge length
Table 6.9 – Diaphragm Spacing
I Bridge length I
5 ft D | D | D 15 ft D = Diophrogm intermediote |3 ft ſ Intermediate
D D D 3 ft e tº
spocing (see Toble 6.9) | f f f Bridge e Spacing,
I I I I Length Required D
I I I I I TI I (ft) Number (ft)
6 in. offset l l l |
(Typicol) // I | | | // 20 2 14
Skew P-4– At , I / 22 2 16
ongle, 9
sºlſ|| | | |// 24 2 18
II. " wr II
/ / | l l / / 26 3 10
I I
I I I II 28 3 11
/ / l l l / / 30 3 12
| | I
III I / 32 3 13
// || | | || || 34 3 14
LI I I f * I I 36 3 15
/ / | | / / 38 3 16
I I I I I I
I I I / 40 3 17
42 3 18
Unskewed Bridges Skewed Bridges 44 4 12.67
Plan view Plan view 46 4 13.33
48 4 14
Diaphragm-to-Stringer Connection Notes 50 4 14.67
1. This sheet depicts glulam diaphragms. Refer to Sheet 10 of 11 for steel diaphragms. 52 4 15.33
Stringer spocing, S * –5–1/8 in. 2. The number and spacing of diaphragms depends onbridgelength and is based on requirements 54 4 16
Dioph lendth Stringer for beam stability and alignment. This design limits diaphragm spacing to 18.5-ft. If beams 56 4 16.67
| topnrogm leng | are rigidly attached to an end wall, such as timber backing planks, the diaphragms can be
| & e & º º 58 4 17.33
tº / e uniformly spaced. If beams are not rigidly supported at their ends, diaphragms must be placed
4 in. Diophrogm within 3-ft of the bridge ends. See Table 6.9 for intermediate diaphragm spacing and the total 60 4 18
• {-|-FH-4 # ſº number of diaphragms required. 62 5 14
# $ 3. All diaphragms are 5–7%—in.—thick glulam and may be the same combination symbol as the 64 5 14.50
$ | | E / deck panels or the stringers. Alternatively, Southern Pine Combination 48 or Western Species 66 5 15
§ g Combination 2 may be used as diaphragms. Diaphragm height is equal to the stringer depth
g ã minus 8-in. Diaphragm length is equal to the clear distance between stringers minus V6-in. 68 5 15.50
5 E E E E EE E E E E E E E E = E E E E E E E E E E E E E = .9
(/) | H – 7 O 4. Diaphragms for unskewed and skewed bridges are placed perpendicular to stringers. 70 5 16
4 in. \ Adjacent diaphragms are offset to allow placement and access to connection hardware. For 72 5 16.50
| \ unskewed bridges, the typical offset distance is 6-in. For skewed bridges, the offset distance 74 5 17
1 in. squore ply rout, will wary depending on the skew angle.
Molledble iron wosher top ond bottom 76 5 17.50
3/4 or 7/8 in. diometer tie rods & (typicol) 5. Diaphragms are attached between stringers with %– or 7/8-in. diameter tie rods that extend
Stringer tº * * * * * e 78 5 18
te through the diaphragms in 1-in-square ply routs. The ply routs are centered on the diaphragm
width, b idth and |ly placed at the third ſlue line from the diaph d b 80 5 18.50
width and are ſlenerally placed at the third ſlue line from the diaphraſſm top and b0tt0m. &
End view Side vi Q y p g - phragm top
The bridge superstructures depicted on these drawings were of 7 Glulam Strinder and Transverse Deck Glulam Di m
Uſ/O ºf a ag ſº 9 aphragm Layout
the Federal Highway Administration, the USDA Forest Service, % C2;
Forest Products Laboratory, and Laminated Concepts, Inc. °sº Standard Plans for Timber Bridge Superstructures December 2000 Sheet 9 of 11


43
Steel Diaphragm Layout
Table 6.10 – Diaphragm Spacing
Bridge length Diophrogm intermediote º Bridge Length |
spocing (see Toble 6.10) ſ Bridge * Intermediate
3 ft. D | D | D 15 ft 3 ft, I D I D 5 ft Length Required Spacing,
| | | | | | / / (ft) Number D
I I / I (ft)
I I I I I /
l | | | 20 2 14
I ſ I
Skew I I I R f f I / 22 2 16
* || || | | // 24 2 18
I I l | H 26 3 10
ſ ſ y y 28 3 11
I I I I I II
/ / l l l l 30 3 12
| | |
I I , Aº ITI I 32 3 13
// || | || || 34 3 14
III" * I 36 3 15
/ / | l | / / 38 3 16
1—# # # H– 40 3 17
42 3 18
Unskewed Bridges Skewed Bridges 44 4 12.67
an view 46 4 13.33
48 4 14
Diaphragm-to-Stringer Connection 50 4 14.67
52 4 15.33
Stringer spocing, S Stringer Notes 54 4 16
| Diophrogm length | 1. This sheet depicts steel diaphragms. Refer to Sheet 9 of 11 for glulam diaphragms. 56 4 16.67
| | 58 4 17.33
4 in 2. 2. The number and spacing of diaphragms depends on bridge length and is based on requirements for * >
m. ºlº º ^ e imſ ºr m. ^ —T * = ºr º beam stability and alignment. This design limits diaphragm spacing to 18.5-ft. If beams are rigidly 60 4 18
To <S S.S. <-2 <S º 5 attached to an end wall, such as timber backing planks, the diaphragms can be uniformly spaced. 62 5 14
£ S 3. lf beams are not rigidly supported at their ends, diaphragms must be placed within 3-ft of the bridge
§ ‘o ends. See Table 6.10 for intermediate diaphragm spacing and the total number of diaphragms 64 5 14.50
To | e | <> E → required.
§ * g 66 5 15
On E
5 e Nº. 2 2. 3. 3. Diaphragms are welded from steel angles and plates and shall be galvanized Or otherwise 68 5 15.50
or, - all- aſ « 2’ \ TSS Y iº mim aſ < → *S protected from corrosion. Diaphragm height is equal to the stringer depth minus 8-in. Diaphragm 70 5 16
\ K: —l & —l- length is equal to the clear distance between stringers minus Vé-in.
J \ | | 4 in. 72 5 16.50
t * 4. Diaphragms for unskewed and skewed bridges are placed perpendicular to stringers. For unskewed 17
3 x s lſ). pote wosher 3 x 5/8 in. plote bridges, diaphragms are aligned and connected through the stringers. For skewed bridges, adjacent 74 5
(exterior stringer only) gº diaphragms are offset a distance that depends on the skew angle. 76 5 17.50
3 x 3 x 3/8 in. steel ongle 78 5 18
3/4 in. hex head bolt 5. Diaphragms are attached to the stringer with%—in.-diameterbolts that extend through 13/16-in.
prebored bolt holes in the stringers and diaphragms. 80 5 18.50
End view Side view
The bridge superstructures depicted on these drawings were * Glulam Strinder and Transverse Deck Steel Diaphragm Layout
developed under a cooperative research agreement between ſº 9
the Federal Highway Administration, the USDA Forest Service, %



Forest Products Laboratory, and Laminated Concepts, Inc. *::::= Standard Plans for Timber Bridge Superstructures December 2000 Sheet 10 of 11
Bearing Connection Details for Glulam Stringers
Stringer width
Unskewed Skewed plus 1/4 in.
4 x 6 x 1/2 in. steel ongle
| / , Z-3/4-in.-dio. thru-bolt – T–T
1/2 in. thick side plote |- 2 in.
© # = + = t © / S © welded to bose plote NH — — — — —EH-
gº Eº / -
3/4-in.—dio. tº &
| onchor bolt / 6 in. min.
| 4 in.
I ||| \\ III
| / N. |
1/2 in. thick bose plote 3/4 in. thick elostomeric
beoring pod
Bearing Clip Configuration Steel Plate Bearing Shoe
Plan view End view
Deck ponel
Stringer tº Fill gop with joint filler
1 in gop —H. y-Dºº: ponel
.* Stringer
12 in. minimum bearing length
Bockwoll
12 in. minimum bearing length
. bolt
Steel bearing clip
3/4-in.-dio. onchor bolt
4—in.—dio. thru-bolt
Timber cop 3/4-in.—dio. thru-bo
Steel bearing clip
3/4-in.—dio. onchor bolt
Timber Substructure Connection
Side view
Symmetricol
obout
Spon greater thon 50 ft Spon 50 ft ond less
r
2 in.
– F –
N
2 in.
8 x 4 x 1/2 in. steel ongle-sº – E –
L– 6 x 4 x 1/2 in. steel ongle
-
3/4 in. thick bearing pod-sº LT 1/2 in. thick bearing pod
| HT-S
| | || IIIT)
|
| `s
1/2 in. thick steel bose plote
Steel Angle Bearing Shoe
End view
Notes
1. This sheet shows several suggested substructure attachment details that are commonly used for glulam stringer bridges.
Attachment details for specific bridges may wary and should be verified based on site-specific loads and other design
requirements. For additional information, refer to AASHTO Standard Specifications for Highway Bridges and Timber Bridges:
Design, Construction, Inspection, and Maintenance (Ritter 1990).
2. This standard assumes 12-in. bearing lengths at all supports. Site-specific seismic conditions may require additional bearing
length. All bridges should be evaluated by a qualified professional engineer for AASHTO seismic requirements.
3. The number of attachment bolts used with the bearing clip to fasten the stringer to the abutment sill will depend on specific
loading requirements. Bearing clip bolt holes may be slotted or oversized as necessary to allow for stringer rotation and
construction tolerances, provided there is adequate restraint to resist applied loads.
4. Bearing pads, when needed, shall be a minimum 50 durometer neoprene with a minimum thickness of 1/2-in. (see detail On
this page).
5. When attachment is to a concrete support and backwall, a minimum 1-in. Gap should remain between the superstructure and
backwall to allow for possible expansion of the deck due to increases in moisture content. The gap should be filled with an
expanding joint filler to prevent debris and water from passing through to the bearings.
The bridge superstructures depicted on these drawings were
developed under a cooperative research agreement between
Glulam Stringer and Transverse Deck
Bearing Connection Details
the Federal Highway Administration, the USDA Forest Service, % ©.
Forest Products Laboratory, and Laminated Concepts, Inc. °sº
Standard Plans for Timber Bridge Superstructures
December 2000 Sheet 11 of 11









45
Beam Systems:
Transverse Glulam Decks for Steel Beam Bridges
º
The bridge superstructures depicted on these drawings were
*9'" - Title P
developed under a cooperative research agreement between ſ º Glulam Decks for Steel Beam Bridges itle Page
the Federal Highway Administration, the USDA Forest Service, *. 37
Forest Products Laboratory, and Laminated Concepts, Inc. *:::s Standard Plans for Timber Bridge Superstructures December 2000 Sheet 1 of 7


46
Plan, Profile, and Section Views
Steel bedn
Abutment
Glulom deck ponels, see Note 4.
Weoring surface,
see Note 7.
|- Roodwoy width
|: _Tº glulom deck,
see Note 5.
I I I I I I II
Effective deck design spon, see Poge 3 of 7.
Design Spon=See definition detail
Length=Bridge length measured
out-out
Width=Bridge width measured
out-out
Substructure shown for
illustration only.
Bridge roiling, see Note 6.
General Notes
DESIGN
1. These drawings are for transverse glulam decks on steel wide flange beams or
steel plate girders. The designs are applicable for unskewed and skewed bridges
with deck thicknesses of 5- to 8-3/4-in. Design truck loading is AASHTO HS
20–44 or HS 25–44 with deck live load deflection limited to 0.10-in.
2. The designs comply with the 1996 Standard Specifications for Highway Bridges,
with 1998 Interims, published by the American Association of State Highway and
Transportation Officials (AASHTO), except where noted. The effective deck design
span is equal to the clear distance between supports plus one-half the width of one
support, but not greater than the clear span plus the deck thickness. The deck
Overhang, measured from the deck edge to the center of the Outside beam is limited
to 2.5-ft. A longer overhang is permissible provided the design is verified by a
qualified professional engineer for actual loading and deck material properties. All
transverse glulam panels were designed assuming single-piece laminations.
3. As specified by AASHTO, transverse glulam decks that are placed upon two or
three steel beams are designed as simple spans. Transverse glulam decks that are
place upon four or more steel beams are designed as simple spans but maximum
moment and deflection are reduced by 20 percent to account for the effects of span
continuity. The transverse glulam decks included in these standards were designed
as non-interconnected panels. Transverse glulam decks may also be interconnected
using steel dowels (refer to AASHTO for detailed design information).
4. Deck panels are 5- to 8-3/4-in-thick (standard Southern Pine and Western
Species glulam sizes) and are typically 4-ft wide. The width and layout of deck
panels are shown on Sheet 4 of 7 for unskewed and Sheet 5 of 7 for skewed
bridges. Attachment of deck panels to supporting stringers is with 5/8-in.-diameter
dome-head bolts and deck clips or angle brackets as shown on Sheet 3 of 7.
5. Minimum required timber design walues are provided for deck spans of 2- to 9-ft.
The required minimum deck thickness for a specific deck span can be selected from
tables On Sheet 6 of 7 (for decks On 4 or more steel beams) and Sheet 7 of 7 (for
decks on 2 or 3 steel beams), based on material, loading and beam spacing.
6. Bridge rail and curb drawings are for illustration purposes Only and must be
designed based on site-specific requirements. Deck designs are based on an
assumed dead load of 10 lb/ft’ for the rail and curb system. Crashworthy rail
designs are available in Development of Two T1-2 Bridge Railings and Transitions
for Use on Transverse Glue-laminated Deck Bridges (Faller et al. In Press).
7. An asphalt wearing surface with a geotextile fabric or membrane is recommended
for most timber bridge applications. Designs are based on an assumed dead load of
38 lb/ft’ for an asphalt wearing surface (approximately 3-in.). Refer to Page 53 for
recommended asphalt wearing surface construction details.
8. These designs are intended for informational purposes only and, due to potential
changes in design requirements and use conditions, should be verified by a qualified
professional engineer.
MATERIAL AND FABRICATION
Wood
9. Glulam deck panels shall comply with the requirements of AASHTO M168 and
ANSI/AITC A190.1 and shall be manufactured to an industrial appearance grade
using wet-use adhesives.
10. Any species and combination of glulam may be used provided it is treatable with
wood preservatives and tabulated design walues are provided in the AASHTO
Standard Specifications for Highway Bridges. Deck panel glulam combinations
should be selected from the tables for "members stressed primarily in axial tension
Or compression".
11. Insofar as is practical, all glulam shall be cut, drilled, and completely fabricated
prior to pressure treatment with preservatives. Refer to Sheet 4 of 7 (unskewed
bridges) and Sheet 5 of 7 (skewed bridges) for layout details.
Preservative Treatment
12. All glulam shall be treated in accordance with AASHTO M133 and AWPA
Standard C14 with One of the following preservatives:
a. Coal tar Creosote conforming to AWPA Standard P1|P13
b. Suitable oilborne preservatives conforming to AWPA Standard P8 in hydrocarbon
solvent, Type A or Type C.
13. Treated material shall follow post-treatment requirements summarized in Best
Management Practices for the Use of Treated Woodinăquatic Environments (WWPl
1996) to ensure all surfaces are free of excess preservative and chemicals are
fixated in the wood.
14. Preservative treatment shall be inspected and certified in accordance with
AASHTO M133 and AWPA Standard M2.
Steel Fasteners and Hardware
15. Steel plates and shapes shall comply with the requirements of ASTM A36.
C-clips should comply with the requirements of grade 30 cast iron.
16. Bolts shall comply with the requirements of ANSI/ASME Standard
B18.2.1–1981, Grade 2.
17. All steel components and fasteners shall be galvanized in accordance with
AASHTO M111 or AASHTO M232, or otherwise protected from corrosion.
18. Washers shall be provided under bolt heads and under nuts that are in contact
with wood. Washers may be omitted under heads of special timber bolts or
dome-head bolts when the size and strength of the head is sufficient to develop
connection strength without wood crushing.
CONSTRUCTION
19. All wood and metal components shall be handled and stored carefully so as not
to damage the material. If damage does occur, exposed untreated wood shall be
field treated in accordance with AASHTO M133. Damage to galvanized surfaces
shall be repaired with a cold galvanizing compound or other approved coating.
20. Deck panels should be placed after stringers and diaphragms are set and
secured. A common construction procedure is to place the first panel at midspan,
then sequentially place remaining panels outward toward the abutments.
Attachment hardware should be hand-tightened as the panels are placed, then
securely tightened after all panels are placed and aligned.
21. The application of a bituminous sealer is recommended to prevent excessive
wood checking in areas where the woodendgrain is exposed. Werticaljoint surfaces
between glulam deck panels should also be coated to minimize moisture penetration.
Any commercially available roofing cement is effective.
The bridge superstructures depicted on these drawings were
developed under a cooperative research agreement between
the Federal Highway Administration, the USDA Forest Service,
Gulam Decks for Steel Beam Bridges
Superstructure Drawings and General Notes



Forest Products Laboratory, and Laminated Concepts, Inc.
December 2000 Sheet 2 of 7
Standard Plans for Timber Bridge Superstructures
Effective Deck Design Span Fabrication Details
Per AASHTO specificotions, the effective deck design spon sholl be equal to the clear distonce 3/8-in. e
between beam flonges plus 1/2 the width of one flonge, but not greater than the clear | 3-in. |
distonce between flonges plus the deck thickness. – H |
Glulom deck N F-
| s *- ==– Deck thickness, t |
– | | 3/4 in.
|- -] º º º slotted
Cleor hole 4—in.
distonce Beom flonge
.# thickness
& |- sm m Z
~ Steel b >
eel DeCrn | l
I
2.5 ft |-- “LL TH TET
see Note 2 (Sheet 2 of 7). º Ç 1/4-in.
To determine required deck thickness, Ti2+,-,
See Tables 7.1 and 7.2. —T Iſl.
* = e º 'º - e º 'º -> -T – – F – — — — — —
Deck Attachment
Notes Steel Angle Bracket
1. For steel beam flanges less than %—in.—thick, use a grade 30, cast 2–3/4-in
iron "C" clip. For steel beam flanges greater than %—in.–thick, use | e |
an A36 steel angle bracket.
5/8 in. Ø dome 2. Both connector types should have slotted holes sized to two or O O O O
heod bolt three times the bolt diameter. See details on this page.
Deck ponel |
/ 3. For connector hole placement on glulam deck panels, see Sheet 4 cº 3/4 in.
T-7 of 7 (unskewed bridges) and Sheet 5 of 7 (skewed bridges). T slotted
Ş § sº hole
ſh G.
Steel ongle Cost-iron "C" clip for
brocket beam flonges less thon
or equal to 3/4 in. thick | | T | A/ L________ * * * * * * * * *
[−1 |
Thru-Bolt Attachment Cast-iron"C" Clip
End view
The bridge superstructures depicted on these drawings were of T lul Deck r | Beam Bri S Definition & Deck Attachment
Uſ!COſ a 89 14 is, Glulam Decks for Steel Bea dges pan
the Federal Highway Administration, the USDA Forest Service,
Forest Products Laboratory, and Laminated Concepts, Inc. Standard Plans for Timber Bridge Superstructures December 2000 Sheet 3 of 7


48
Glulam Deck Panel Layout - Unskewed Bridges
Bridge length
Notes
* = - m me = * * * * = sm sºme ºn is m ms tº mº m ºn me me me = ** = m. m. m. ººms smºs = |* = * * * * * * * * * *m nº sm ammº ºme ºne me º }* = ** = * * * * = * * = * * 1. This sheet depicts glulam deck panel layouts for unskewed bridges and deck attachment details. Refer to
Sheet 5 of 7 for deck panel layouts for skewed bridges.
JC
# IIIIII IIIIIIIIIIIII IIIIII]IIIIITIIIIIIIIIIIIIIIIIIIIIIIIIIIIII 2. The required number of interior deck panels and the end panel width (X) are based on bridge length. Interior
Top panels have a standard width of 48-in. End panel width depends on bridge span but shall not be less than 3-ft.
5 Deck panel length is equal to the Out-out deck width.
Cl
# }= * = a- - - - - - - - - - * * * = ** = ** = , = * * = * = | * = * * * = - = = * = * = * = * = * = = * = * = < * = * = * = - e = = = * = - 3. Deck panels are attached to the supporting stringers with cast-iron "C" clips or steel angle brackets as
º shown on Sheet 3 of 7. "C" clips are commonly available from glulam bridge suppliers and are suitable when the
5 —"— — — — — . 4- — — — — —”-- — — — — — — — — — — — — — — — — — —l— — — — — — — — — — — — — — — — — — 4- — — — — — — — — — — — — beam flange thickness does not exceed 3/4-in. Angle brackets are normally fabricated from A36 steel angles
e- Hea- - - - -R = - T - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - IIIIIIIIIIIIIIIIIIIIIIIII d can be made for any flange thickness.
t; cº- -g T-d- S. and Can De made 10r any flange thickness
º N_
t; Typical deck ponel ottochment, see detoils below ond Sheet 3 of 7
Ol k- — — — — — 4- — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — —
el F-----T-----T------------|------------------|------T------ |e me -- ~ * = -
§
B
*] --— — — — — — — — — — — — — — — — — — — — — — — — — — — — —l— — — — — — — — — — — — — — — — — — l--— — — — — — — — — — —
# ------4-----|----- *} = ** = = ** = - = = = - = |* * = = - - - - - - - - - - - - - - - - - - - - - - P = ** = = = -
Ö
End Interior ponel width = 48 in. End
ponel ponel
width (x) width (x)
Plan View
48 in. End ponel width (X)
3/8 in. for "C" clip 3/8 in. for "C" clip
F' in. ongle brocket —ſ 1 in. ongle brocket
------9----------92–- --9–------------Q.--
*= * * = mºmmams mºme Q stringer gº ºs T — — —— Q stringer
--o----------.of------- --a---------------6--
1 f
6 in. —- | t 1 ft | 1 ft -— 6 in. 6 in. —- |- – -— 6 in.
Attachment Spacing - Interior Panel
Plan view
The bridge superstructures depicted on these drawings were of 7 Glulam Decks for Steel Beam Bridges Panel Layout - Unskewed Bridges
developed under a cooperative research agreement between ſº ñº 9 9
the Federal Highway Administration, the USDA Forest Service, % ©.

Forest Products Laboratory, and Laminated Concepts, Inc. °sº Standard Plans for Timber Bridge Superstructures December 2000 Sheet 4 of 7
Glulam Deck Panel Layout - Skewed Bridges
Bridge length
Notes
1. This sheet depicts glulam deck panel layouts for skewed bridges. Refer to Sheet 4 of 7 for deck panel
layouts for unskewed bridges.
2. The required number of interior deck panels and the end panel skewed width are based on bridge length.
Interior panel skewed width (W) is 48-in. End panel skewed width depends on bridge span but shall not be less
than 3-ft.
~ 3. Deck panels are attached to the supporting stringers with cast-iron C clips or steel angle brackets as shown
8 On Sheet 3 of 7. "C" clips are commonly available from glulam bridge suppliers and are suitable when the beam
# Typicol deck ponel ottochment, see detoils below ond Sheet 3 of 7. flange thickness does not exceed 3/4-in. Angle brackets are normally fabricated from A36 steel angles and can
J. be made for any flange thickness.
#
3:
Q)
# */ H-----4-----4------------------------|-----|-----4-----4-----
Ö Skew H - - - - - + – — — — — — — — — — — — — — — — — — — — — — — — — — — — — —H — — — — — — — — — — — — — — — — — — — — — — —
ongle, 9
©
*mº ºms º ºs ºs s = ºm me mº ºms m º ºs me = * = * * * * * * * * * * * * * * * * =me ºne me sºme º ºs º ºsmºs sºme ºs m. ºnº º ºs º º sºme º gº º sºme sºme º sºme mºm º º sº me ºme ºme sºme C
Wp = Ws " Cos tº
©
| where
| 6 = skew onqle
End ponel Interior skewed ponel width (Ws) = 48 in. º º / Ws A Wp = ºo: panel width (in.) e
skewed width skewed width / Ws = interior skewed ponel width = 48 in.
Plan View
%
*s . W.
°os ZO `s,
‘Sy
Ø Ø
-----º-Hoº-º-- * = ± 9ffset_______3_ Offset = 3/8-in. for "C" clip
tº-º-º: smº. | {-º-º-º: Q Stringer A amºe Q Stringer = 1 -in. for ongle brocket
ºr sºme mº me me m = m. sºme eme me ammº ºme mºm sºme me sm m º ----------------4-
º 1 ft | 1 ft º 1 ft y
| | y-
| 6 in. 6
6 in 6 in *.
WS = 48 in. —- WS
Attachment Spacing - Interior Panel
Plan view
The bridge superstructures depicted on these drawings were of 7 | O Panel Skewed Brid
©S
developed under a cooperative research agreement be ſº Glulam Decks for Steel Beam Bridges Layout 9
the Federal Highway Administration, the USDA Forest Service, % C2;
Forest Products Laboratory, and Laminated Concepts, Inc. °sº Standard Plans for Timber Bridge Superstructures December 2000 Sheet 5 of 7




50
Table 7.1 – Design Table for Bridges with Four or More Steel Beams
Effective Minimum Required F.' (blin’) and E' (x10°lblin?) Values for Actual Deck Thickness" Ranging from 5– to 8%—in.
º HS20–44 Loading HS25–44 Loading
º 6% 8% 51/3 6%
(ft) F. F.
2.00
2.17
2.33
2.50
2.67
2.83
3.00
3.17
3.33
3.50
3.67
3.83
4.00
4.17
4.33
4.50
4.67
4.83
5.00
5.17
5.33
5.50
5.67
5.83
6.00
6.17
6.33
6.50
6.67
6.83
7.00
7.17
7.33
7.50
7.67
7.83
8.00
8.17
8.33
8.50
8.67
8.83
a – Western species glulam sizes are 5%—, 6%—, and 8%—in.;
Southern pine glulam sizes are 5-, 6%—, and 8%—in.;
Table instructions
The table on this sheet is for determining the required deck thickness for transverse glulam decks supported
by four or more steel beams. The criteria for selecting deck thickness are based on the effective deck design
span, vehicle loading, and material properties for the species and combination of glulam. The effective deck
design span is equal to the clear distance between beam flanges plus one-half the width of One flange, but
not greater than the clear distance between flanges plus the deck thickness. Live load deflection is limited
to 0.10-in. for all deck thicknesses. The table provides the minimum required allowable design walues for
bending strength (F,') and modulus of elasticity (E'), based on the vehicle live load, deck dead load, and an
assumed dead load of 10 lb/ft’ for the railing|curb system and 38 lb/ft for an asphalt wearing surface.
Allowable design values for horizontal shear (F,') are not listed because horizontal shear is not critical for
shallow deck sections. Blank cells in the table denote cases where the required design walues exceed those
typically available or that result in excessively conservative designs.
The table may be used in two ways. When the combination symbol and material species of glulam are known,
the designer must determine the allowable design walues for the material, then compare them to the values
given in the table. The computed allowable values must be greater that the table values in Order to select the
corresponding deck thickness. Alternatively, when the combination symbolandmaterial species are unknown,
minimum required F, and E' values may be obtained from the table based on effective deck design span, deck
thickness, and vehicle loading. A grade and species of glulam that meets these minimum allowable design
values may then be selected. Specific procedures for table use follow:
Glulam Combination and Species Known
1. Determine the required design criteria for
a. effective deck design span and
b. vehicle loading, AASHTO HS20–44 or HS25–44.
2. Compute the allowable design walues for the combination symbol and species of glulam using the following
equations:
F, - F. Cw CF Co E" - ECM
where F, - allowable bending stress (blin’) Cu - wet service factor
F, - tabulated bending stress (blin’ C; - bending size factor
E' - allowable modulus of elasticity (blin') Co - load duration factor
E - tabulated modulus of elasticity (blin’)
3. Enter the table and select a deck thickness based on the design criteria and allowable material properties
previously determined. The allowable material property values for F, and E' must be greater than Or equal
to the corresponding table values for the deck thickness selected. If not, the design criteria and/or material
properties must be revised until acceptable values are achieved.
Glulam Combination Symbol and Species Unknown
1. Determine the required design criteria for
a. effective deck design span and
b. vehicle loading, AASHTO HS20–44 or HS25–44.
2. Enter the table and select a deck thickness based on the design criteria. Note the required minimum
allowable design values for F, and E'.
3. Select a glulam combination that provides the minimum allowable design walues.
Glulam Decks for Steel Beam Bridges
Design Table - 4 or more Steel Beams
The bridge superstructures depicted on these drawings were *
developed under a cooperative research agreement between ſº DUS,
the Federal Highway Administration, the USDA Forest Service, % &
Forest Products Laboratory, and Laminated Concepts, Inc. *::::=
Standard Plans for Timber Bridge Superstructures December 2000 Sheet 6 of 7


51
Table 7.2 – Design Table for Bridges with Two or Three Steel Beams
Effective
Deck
HS20-44 Loading
Design
Span
(ft)
3.00
3.17
3.33
3.50
3.67
3.83
4.00
4.17
4.33
4.50
4.67
4.83
5.00
5.17
5.33
5.50
5.67
5.83
6.00
6.17
6.33
6.50
6.67
6.83
7.00
7.17
7.33
7.50
7.67
7.83
8.00
8.17
8.33
8.50
F.'
608
631
653
676
699
722
744
767
790
813
836
859
882
905
928
951
975
998
1,021
8%
0.55
0.60
0.65
0.71
0.78
0.84
0.91
0.99
1.06
1.15
1.23
1.32
1.42
1.52
1.62
1.73
1.84
1.96
2.08
F,
611
632
653
674
696
717
739
760
781
803
824
846
868
889
911
933
955
976
8%
a – Western species glulam sizes are 5%, 6%, and 8%—in.; pine glulam sizes are 5-, 6%—, and 8%-in.
b - Bridges with only two steel beams must use an effective deck design span greater than 6.33-ft.
F,
5%
HS25-44 Loading
F.'
761
823
885
946
Minimum Required F.' (lblin’) and E' (x10°lblin') Values for Actual Deck Thickness", t, Ranging from 5- to 8%—in.
6%
Table Instructions
The table On this sheet is for determining the required deck thickness for transverse glulam decks supported
On two or three steel beams. The criteria for selecting deck thickness are based on the effective deck design
span, vehicle loading, and material properties for the species and combination of glulam. The effective deck
design span is equal to the clear distance between beam flanges plus One-half the width of One flange, but
not greater than the clear distance between flanges plus the deck thickness. Live load deflection is limited
to 0.10-in. for all deck thicknesses. The table provides the minimum required allowable design walues for
bending strength (F,') and modulus of elasticity (E'), based on the vehicle live load, deck dead load, and an
assumed dead load of 10 lb/ft’ for the railing|curb system and 38 lb/ft’ for an asphalt wearing surface.
Allowable design values for horizontal shear (F,') are not listed because horizontal shear is not critical for
shallow deck sections. Blank cells in the table denote cases where the required design walues exceed those
typically available or that result in excessively conservative designs.
The table may be used in two ways. When the combination symbol and material species of glulam are known,
the designer must determine the allowable design values for the material, then compare them to the values
given in the table. The computed allowable values must be greater that the table values in order to select the
corresponding deck thickness. Alternatively, when the combinationsymbolandmaterialspecies are unknown,
minimum required F, and E' values may be obtained from the table based on effective deck design span, deck
thickness, and vehicle loading. A grade and species of glulam that meets these minimum allowable design
values may then be selected. Specific procedures for table use follow:
Glulam Combination and Species Known
1. Determine the required design criteria for
a. effective deck design span and
b. vehicle loading, AASHTO HS20–44 or HS25–44.
2. Compute the allowable design walues for the combination symbol and species of glulam using the following
equations:
F, - F. Cu CF Co E" - ECM
where F, - allowable bending stress (blin’) Cu- wet service factor
F, - tabulated bending stress (blin’) CF - bending size factor
E' - allowable modulus of elasticity (blin' Co - load duration factor
E - tabulated modulus of elasticity (blin’)
3. Enter the table and select a deck thickness based on the design criteria and allowable material properties
previously determined. The allowable material property values for F, and E' must be greater than or equal
to the corresponding table values for the deck thickness selected. If not, the design criteria andlor material
properties must be revised until acceptable values are achieved.
Glulam Combination Symbol and Species Unknown
1. Determine the required design criteria for
a. effective deck design span and
b. vehicle loading, AASHTO HS20–44 or HS25–44.
2. Enter the table and select a deck thickness based on the design criteria. Note the required minimum
allowable design walues for F, and E'.
3. Select a glulam combination that provides the minimum allowable design walues.
The bridge superstructures depicted on these drawings were of 7
developed under a cooperative research agreement between ſº
the Federal Highway Administration, the USDA Forest Service,
Forest Products Laboratory, and Laminated Concepts, Inc.
@
Glulam Decks for Steel Beam Bridges
Design Table -2 or 3 Steel Beams
Standard Plans for Timber Bridge Superstructures
December 2000 Sheet 7 of 7



52
Asphalt Wearing Surface Construction Details
Symmetricol Roil ond connecting hordwore
obout omitted for clority.
compocted thickness
|
1-1/2 in. minimum compocted thickness Approximately 3 in.
|
wº * ... • . . e e . - a © ... -- & g
©e * * •- \ • • tº ºs - Riº ſº tº ** * * * , a, , . - g e e° e e ** * ~~~ y d : º *IA - • e * ,
\ \ | \ block
1 – 2 N_
wº-". ------. • •. , “.. •” .. ... - ...---------H te © . percent crown - Nº.
Scupper
\- deck \– fobric or tockcoot, see Notes 1, 4, ond 5.
Aspholt povement, see Notes 1, 2, ond 5.
Cross-section view
Aspholt loyer zº Aspholt loyer _*
||
0- deck | S & Tronverse deck | S
|| [-nº- Gh F-1
Glulom bedn
Glulom stiffener, see Note 8.
Steel bedn Steel stiffener, see Note 8.
Longitudinal Stiffener Options for Beam Bridges
Notes
1. These asphalt wearing surface details are recommended for most applications involving the timber bridge
superstructures included in these drawings. A crowned asphalt wearing surface, when used in combination with
a waterproof asphalt layer, or membrane, will shelter the bridge from moisture and potential deterioration. In
low-volume traffic applications, the use of an asphalt wearing surface may not be warranted. For additional
information about wearing surfaces for timber bridges, refer to Timber Bridges: Design, Construction, Inspection,
and Maintenance (Ritter 1990).
2. Bituminous asphalt should be dense-graded and is typically the same mix design specified by state and federal
agencies with responsibilities for road paving and maintenance. The asphalt should be placed and compacted to a
minimum thickness of 1%—in. at the roadway edge, and approximately 3-in. at Centerline.
3. For proper wearing surface bonding and performance, the surface of the timber deck should be clean, dry, and
free of excess wood preservative. Excess preservative is normally not present when the treating specifications and
procedures recommended in these drawings are followed. If there are accumulations of preservatives On the deck
surface, applying a surface blotter before paving can greatly improve geotextile and asphalt bonding. The blotter
should be removed from the deck prior to paving. Leaving the deck unpaved for a period of 30-45 days will also help
remove excess preservative and solvent from the deck surface.
4. Preformed waterproof paving membranes are typically a geotextile fabric or mesh embedded in rubberized
asphalt and should be installed according to the manufacturers' recommendations. Prior to selecting a membrane,
compatibility of the membrane material with the wood preservative used for the bridge deck should be verified.
Paving membranes should never be used in direct contact with pentachlorophenol treated wood. Improved
performance may result when the membrane is placed between two asphalt layers. This is typically accomplished
by placing an initial asphalt layer that is crowned as required. The membrane is placed on this initial layer and a final
1- to 1%—in.–thick uniform asphalt layer is placed on the membrane.
5. Preformed waterproof membranes may not adhere well to oilborne—preservative-treated timber bridge decks
and the rubber may be incompatible with treatment chemicals. A waterproof layer can be created using asphalt
cement or polymer modified asphalt emulsion in combination with a standard paving fabric and asphalt hot mix.
Performance—graded asphalt cement and paving fabric should be applied in accordance with AASHTO M288–99,
Section.9, and Appendix A6. Polymer modified asphalt emulsions may also be used if residual asphalt content meets
the residual application rate recommended by the fabric manufacturer. Sufficient time must be allowed and
appropriate weather conditions must exist for emulsions to cure prior to the application of fabric. Asphalt cement
will normally be applied at a rate of 0.25 gallons per square yard before placing fabric. Polymer-modified asphalt
emulsion would be applied at a rate of 0.37 gallons per square yard to obtain the same asphalt residual. The
emulsion must cure until the water has evaporated before placing the fabric. Asphalt hot mix would then be placed
and compacted between 250 and 320°F. Polymer modified asphalt emulsions should not be used in direct contact
with pentachlorophenol-treated wood.
6. When the bridge deck will be paved on low-volume, unpaved roadways, it is recommended that approach
roadways be paved a minimum of 50-ft in each direction, or beyond the approach guardrails, to facilitate roadway
maintenance.
7. For stress—laminated bridge decks, it is recommended that asphalt paving not be applied until after the first bar
re-tensioning has been completed.
8. For beam bridges, inter-panel movement, or differential deflection between panels, can be minimized by installing
a deck panel longitudinal stiffener beams (glulam or steel, see figure at left). This stiffener beam is placed midway
between longitudinal bridge beams. Stiffener beams shall be continuous over at least two, but not more than four
panel joints (due to moisture changes). See detail on this page and refer to Page 31 for more information regarding
End view types and sizes for stiffener beams.
The bridge superstructures depicted on these drawings were of 7 O O o G o
developed under a ti hag t bel ñº Wearing Surface Recommendations Asphalt Wearing Surface Construction Details
the Federal Highway Administration, the USDA Forest Service, % Cº
Forest Products Laboratory, and Laminated Concepts, Inc. °sº Standard Plans for Timber Bridge Superstructures December 2000 Sheet 1 of 1

53
ſiliili
3 9015 O5199 6752
675
"WIT-02-0060"