Unified Shear Design Equation for Concrete Members Reinforced with Fiber-Reinforced Polymer without Stirrups

Recent shear tests at Memorial University of Newfoundland that were conducted on beams reinforced with fiber-reinforced polymer (FRP) bars without stirrups showed that there is a relationship between the flexural cracking load and the shear capacity of the beams. Based on this relationship, a simple and unified equation for calculating the concrete contribution to the shear capacity of FRP-reinforced beams is proposed. The proposed equation accounts for the effect of shear span-to-depth ratio, axial stiffness of the longitudinal reinforcement, size of the member, and concrete strength. The prediction of the proposed equation has been evaluated by comparing the calculated shear capacity with the corresponding test results of 132 FRP-reinforced rectangular specimens without stirrups. The predictions of the shear capacity using the proposed equation are compared with those obtained using the shear equations in existing design codes and guidelines for FRP-reinforced beams in Japan and North America. It is found than the predictions of the proposed equation are more consistent than those obtained from the existing codes and guidelines.