Theoretical Model for Calculating Shear Strength of Fiber- Reinforced Polymer-Reinforced Concrete Beams

This paper investigates the shear behavior of concrete beams longitudinally reinforced with fiber-reinforced polymer (FRP) bars. Beams with and without glass fiber-reinforced polymer (GFRP) stirrups are analyzed in the paper. Results of 93 large-scale FRP-reinforced concrete beam specimens were shortlisted, and the experimentally determined shear strengths were predicted using the available design algorithms in the literature. Modified Compression Field Theory, which can successfully predict the shear strength of steel-reinforced concrete members, was revisited in this study to incorporate the low-modulus and high-strength behavior of FRP bars. The proposed model gives an average predicted-to-experimental strength ratio of 0.96 with a coefficient of variation (COV) of 13% for beams without any transverse reinforcement and an average strength ratio of 1.00 with a COV of 16% for beams reinforced with GFRP stirrups. Keywords: concrete contribution; fiber-reinforced polymer (FRP) members; FRP stirrups; Modified Compression Field Theory (MCFT); shear strength.