Shear Strength of Large Concrete Members with FRP Reinforcement

Increasing interest in the use of fiber-reinforced polymer (FRP) reinforcement for reinforced concrete structures has made it clear that insufficient information about the shear performance of such members is currently available to practicing engineers. This paper summarizes the results of 11 large shear tests of reinforced concrete beams with glass FRP (GFRP) longitudinal reinforcement and with or without GFRP stirrups. Test variables were the member depth, the member flexural reinforcement ratio, and the amount of shear reinforcement provided. Results showed that the equations of the Canadian CSA shear provisions provide conservative estimates of the shear strength of FRP-reinforced members. Recommendations are given along with a worked example on how to apply these provisions including to members with FRP stirrups. It was found that members with multiple layers of longitudinal bars appear to perform better than those with a single layer of longitudinal reinforcing bars. Overall, it was concluded that the fundamental shear behavior of FRP-reinforced beams is similar to that of steel-reinforced beams despite the brittle nature of the reinforcement.