Performance of code equations compared to experimental data for shear capacity of FRP-RC beams

Current approaches for estimation of shear capacity of concrete beams reinforced with fiber-reinforced polymer (FRP) are generally based on existing semi-empirical shear design equations for steel-reinforced concrete (S-RC). These equations were primarily evaluated based on experimental data generated on concrete beams with steel reinforcement. However, FRP materials have different mechanical properties and accordingly exhibit different modes of failure than steel, making the extension of existing shear design equations for S-RC beams to cover concrete beams reinforced with FRP somehow inaccurate. Currently available methods include ACI 440-06, JSCE-97, CSA S806-02, and ISIS Canada-01. Availability of FRP reinforcement products varies in terms of capacity and modulus of elasticity, which can result in a significant change in behavior. An experimental database of 150 FRP-reinforced concrete (FRP-RC) beams was developped from published literature. Subsequently, this database was used to assess the validity of these four main existing shear design methods for FRP-RC beams. This research investigates the performance of the abovementioned design methods to estimate the nominal shear capacity, V_n of steel-free concrete beams reinforced with FRP bars. Results show that current design guidelines provide a shear strength underestimation in the case of beams without shear reinforcement and a shear strength overestimation for beams with shear reinforcement.