SHEAR-STRENGTH OF REINFORCED-CONCRETE MASONRY BEAMS WITH WEB REINFORCEMENT

The shear and flexural strength of reinforced concrete masonry (RCM) beams without web reinforcement has been investigated previously by various researchers, and it has been found that the behavior of RCM beams is very similar to that of reinforced concrete (RC) beams, where the existence of shearing forces would cause a sudden, premature, nonductile failure. To eliminate this type of failure, web reinforcement is needed, as recommended by different design codes. The objective of the experimental study presented in this paper is to investigate the effect of vertical web reinforcement on the behavior of RCM beams and to assess its contribution to the shear strength of RCM beams. A total of 20 RCM beams with web reinforcement was tested The cracks in RCM beams propagated along the vertical and horizontal joints; thus, the nature of the crack propagation limits the effectiveness of vertical web reinforcement. Calculating the contribution of vertical web reinforcement using the truss analogy approach similar to RC beams overestimates the contribution of vertical web reinforcement. The limits set by ACI 530/ASCE (1988 Codes) for the shear stress of beams with web reinforcement for working stress design may not provide an adequate margin of safety.