Date of Graduation


Document Type



Statler College of Engineering and Mineral Resources


Civil and Environmental Engineering

Committee Chair

Hota V. S. GangaRao

Committee Member

P. V. Vijay

Committee Member

Mark L. Skidmore,


Glass fiber reinforced polymer (GFRP) composites have the potential to replace the existing conventional materials in Civil Engineering like steel and concrete. Such potential can be attributed to the numerous advantages GFRP composites have over conventional materials. Some of the advantages are: high strength-to-weight ratio, corrosion resistance, low life cycle cost and maintenance, nonmagnetic and electronic transparency. As the application of GFRP is on the rise, the need for developing accurate design equations for these materials has been imperative. The GFRP composites are manufactured through pultrusion and although they have numerous advantages they are less stiff than similar profiles made from aluminum and steel. Hence they are more susceptible to elastic buckling than steel profiles of similar dimensions owing to their high strength to stiffness ratio. Because of their geometrical (thin-walled sections) and materials (i.e. E-glass fiber bonded with polymer matrix) properties, the FRP composite undergo large deformations and are vulnerable to global and local buckling failures before reaching their ruptured strength. A long slender beam under bending may exhibit lateral torsional buckling by a combined twisting and lateral bending of the cross section. The existing lateral torsional buckling load equations for isotropic materials were modified for GFRP materials (considering them to be orthotropic) and a new prediction model was presented in the current research. Multiple LTB equations from several sources were considered and the LTB load was calculated and compared with the equations presented in this report. The LTB results for FRP composite beams predicted by other sources were inaccurate leading to the development of the new critical buckling load model. The critical LTB load was predicted to be within ±15% for all the sections used to analyze. The results were also validated with the models simulated in ANSYS, a finite element analysis software. In the current research GFRP frames were tested under transverse loads in the lab and the acquired data was analyzed to identify the critical LTB load for the frames and their LTB response was studied by altering the connection details