Shear Strength of Fiber-Reinforced Polymer Reinforced Concrete Beams Subject to Unsymmetric Loading

This study is concerned with the determination of the effects of shear span-to-depth ratio (a/d) and beam depth, or size, on the concrete contribution to the shear resistance of beams longitudinally reinforced with carbon fiber-reinforced polymer (CFRP) bars. One of the distinguishing features of the study is the unsymmetrical nature of the applied load, which creates two distinct a/d ratios in the same beam and allows the effect of the a/d ratio on shear strength to be clearly seen. Six simply supported large size CFRP reinforced concrete beams without shear reinforcement were tested, each under a single concentrated load. The test variables were the a/d ratio, varying from 1.0–11.5, and the beam depth varying from 200–500 mm. All the beams failed in shear, but the failure load and location for some of these beams could not be predicted by the shear design recommendations of American Concrete Institute (ACI) Committee 440. The reason is that these recommendations do not account for the effects of a/d and beam size on shear strength. Suggestions are made for the inclusion of these parameters in the shear design equations.