Shear design of FRP reinforced concrete beams without transverse reinforcement

A simple and rational model for the prediction of the shear strength of FRP reinforced concrete beams without shear reinforcement is presented. The method is based on the principles of structural mechanics and on the experimentally observed behavior of RC beams at shear-flexural failure. It is assumed that, just before failure, the shear is resisted exclusively by the concrete flexural compression head at the critical section, placed at the tip of the shear crack closer to the support. Failure is considered to occur when the principal tensile stress at the concrete head reaches the concrete tensile strength. Simple design equations are provided, which explicitly account for those parameters governing the shear strength, such as the concrete tensile strength, the amount of longitudinal reinforcement ratio and the ratio between the elastic modulus of the longitudinal reinforcement and the concrete. The accuracy of the proposed method has been verified by comparing the model predictions with the results of 144 tests on CFRP and GFRP reinforced concrete beams and with a previously published database on steel reinforced concrete beams failing on shear, providing better results than those obtained using the design equations of current codes of practice, which are mainly empirically based.