The publication of the "Pre-Standard for the for Load & Resistance Factor Design (LRFD) of Pultruded Fiber Reinforced Polymer (FRP) Structures", hereafter referred to as the "Pre-Standard", established the standardization of the design of structures in pultruded FRP composite. Furthermore, a standard developed through a voluntary consensus process (namely, ASCE/SEI 74) was recently submitted for public review and is completing the publication process. While the Pre-Standard and ASCE/SEI 74 established pultruded FRP composites among the standard design materials for construction in the United States, the two documents are not exhaustive, and additional research is needed for several design issues. At this crucial time for the standardization of pultruded FRP composites in construction, this thesis presents a collection of experimental, analytical, and statistical studies with the aim of further incentivizing the advancements of the structural design of pultruded FRP composites. The primary research goals can be summarized as follows: The derivation of strength reduction factors and reliability of the LRFD equations for connection design; The measurement of the tensile behavior of pultruded FRP composites and derivation of an equation for the tensile strength and elastic modulus at varying angles of loading relative to the pultrusion; The measurement of the flexural modulus of pultruded FRP profiles and the contribution of shear deformation to flexural rigidity; The development and testing of a novel lapped, adhered semi-rigid connection to promote the implementation of more versatile structural framing solutions; and The proposal and reliability analysis of novel predictive models for the design of lapped, adhered semi-rigid connections within the boundaries of the LRFD methodology. The findings of the research, provisional proposals for future editions of ASCE/SEI 74, and examples of applications in real-world projects designed by the author are also detailed herein.