A Shear Strength Model for FRC Coupling Beams

Short coupling beams are susceptible to brittle shear failures that need to be suppressed with dense shear reinforcement. To reduce the amount of reinforcement and improve the service behavior, researchers have proposed a solution with steel fiber-reinforced concrete (FRC). However, while this solution is promising, there are no sufficiently simple mechanical models capable of capturing the shear strength of short FRC coupling beams without diagonal reinforcement. This paper proposes such a model based on first principles: kinematics, equilibrium, and constitutive relationships for the mechanisms of shear resistance. The model accounts for five shear mechanisms whose magnitudes are predicted at failure. When compared to 15 tests, the model is shown to capture well the effect of beam aspect ratio, concrete strength and amount of steel fibres.