Plate end debonding : a modified approach to predict stress in FRP–concrete bond

An important failure mode of RC beams retrofitted with FRP plates is plate end debonding. Design codes provide equations for estimating shear stress at the plate end, but none of these equations include the FRP to concrete width ratio. This paper suggests an improved equation for calculating shear stress that includes the width ratio. The new equation was obtained by fitting 3D nonlinear FEM results to a proposed relation and provided a clearly improved prediction of the shear stress. The simulations also showed that a large width ratio and an adhesive of low stiffness decrease the risk of debonding.