Date of Award

Spring 2024

Document Type


Degree Name

Doctor of Philosophy (PhD)


Civil & Environmental Engineering


Civil Engineering

Committee Director

Zia Razzaq

Committee Member

Mojtaba B. Sirjani

Committee Member

Shahin N. Amiri

Committee Member

Herish Hussein


Presented herein is a study of the stability and strength of pultruded glass fiber reinforced polymer (Glass FRP) beam-columns with an I-shaped cross section subjected to biaxial bending and torsion including shear and warping deformations. Three coupled differential equations of equilibrium including second-order effects and geometric imperfections are formulated and solved using a finite-difference scheme. Laboratory experiments are also conducted on glass FRP members with applied torsion; axial load; combined axial load with biaxial bending; and combined axial load, biaxial bending and torsional moment, respectively, for comparison to the theoretical predictions. The theoretical results agreed well with the experiments for the cases of the axial load and applied torsion. The theory and experiments provided nearly the same stiffness characteristics for the members under combined axial load, bending moments, and torsional loading; however, the ultimate experimental loads were found to be controlled by excessive cracking and deformation of the bottom end connection. The theory is used to quantify the warping and shear deformation effects on the member strength. Finally, an interaction expression involving the axial load, biaxial bending, biaxial shear, and torsional moment is formulated for possible practical use.


In Copyright. URI: This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).