Date of Award

Fall 2012

Document Type


Degree Name

Master of Science (MS)


Civil & Environmental Engineering


Civil Engineering

Committee Director

Zia Razzaq

Committee Member

Duc T. Nguyen

Committee Member

Stella Bondi

Call Number for Print

Special Collections LD4331.E542 K66 2012


This thesis presents the outcome of a theoretical and experimental study of the behavior of Fiber Reinforced Polymer (FRP) I-beams susceptible to lateral-torsional instability or when subjected to biaxial bending. Laboratory experiments involved application of vertical and horizontal static loads to a 4 x 4 x ¼ in. I-beam with various lengths, and the resulting displacement, twist, and strain were recorded. In the vertical direction, the beam was loaded from different reference load heights with respect to the shear center of the beam. The governing biaxial flexure and torsion differential equations were modified to account for the presence of initial imperfections and subsequently solved using a central finite-difference scheme. The theoretical predictions of the beam behavior were generally found to be in good agreement with that observed in the laboratory. It was also found that retrofitting the beam with a layer of Kevlar fabric on the tensile flange provided some lateral resistance; however, it did not result in any significant influence on the major axis flexural or torsional stiffness. The reference load height has a very significant effect on the instability load of the beam. A comparison between the experimental data for uniaxial bending and design equations in a proposed ASCE-FRP Standard for lateral-torsional buckling showed that these equations are conservative only when flexural resistance factors are applied. There remains a need for further research to develop and expand this standard.


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