Date of Award

Spring 1998

Document Type


Degree Name

Doctor of Philosophy (PhD)


Civil & Environmental Engineering


Civil Engineering

Committee Director

Zia Razzaq

Committee Member

Isao Ishibashi

Committee Member

Gene J.-W. Hou


Fiber Reinforced Plastic (FRP) structural members are rapidly gaining impetus in civil engineering applications. Also, thin-walled open beams with I-shaped, channel, and other types of sections are of practical importance to both structural analysts and designers. This dissertation presents the outcome of a detailed experimental and theoretical investigation of the strength and stability of FRP composite beams. Three- and four-point loading tests are conducted on FRP I- and channel section beams. The behavior of these beams is studied under gradually increasing static loads up to the maximum load-carrying capacity corresponding to either material cracking or flexural-torsional instability. First, the theoretical analysis is formulated using an equilibrium approach based on a system of flexural and torsional differential equations. Next, a central finite-difference scheme is developed and programmed to solve the coupled system of the differential equations of equilibrium. In addition, a buckling load formula is developed for the case of four-point loading based on an energy approach, including the load height effect. The theoretical analysis based on the equilibrium approach is found to be in good agreement with the experimental results. The buckling load formula is also found to be in excellent agreement with the experimental buckling loads. Lastly, a Load & Resistance Factor Design (LRFD) approach is presented and its use demonstrated by means of practical analysis and design examples.


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