Additional Shear Strength of RC Beams due to Compression Reinforcement

The shear strength of RC beams is composed of the strength provided by transverse reinforcement (Vs) and concrete (Vc). According to a literature search, no existing shear strength model considers the contribution of compression reinforcement. Only a few discussions on the effect of compression bars on the shear strength of RC members have been conducted in the literature. This study investigated, in detail, the influence of compression reinforcement through experimental testing and finite-element (FE) modeling. First, two groups of beams with different compression reinforcement ratios were designed and tested. After that, a robust FE model was developed, and the effect of compression reinforcement on the shear strength of RC beams was numerically evaluated. The accuracy of the FE model was verified using the test results. The mechanism of the compression reinforcement was analyzed using a conventional truss model. A systematic parametric study was subsequently conducted to investigate the combined effects of compression reinforcement and other critical factors on shear strength. It was concluded that the effect of the compressive reinforcement on the shear strength is comparable to that of the tensile reinforcement. Finally, the research findings were integrated into developing a new model for the additional shear strength of RC members owing to the compression reinforcement.