Ultimate behavior of CFRP strengthened RC flat slabs under a centrally applied load

This paper presents an analytical and experimental investigation for evaluating the punching shear strength of two-way concrete slabs externally bonded by CFRP composite sheets. First, the punching failure mechanism and the parameters governing this failure mode are discussed and an analytical model for punching failure of reinforced concrete slabs developed by Menétrey [Synthesis of punching failure in reinforced concrete. Cement Concrete Compos 2002;24:497–507] is presented. Based on numerical simulation, this model allows the treatment of slabs considering the dowel effect contribution of steel reinforcement. The generalization of this model to the case of slabs externally bonded by CFRP laminates requires the consideration of biaxial behavior of composite sheets resulting from two-way slab boundary conditions. Finally, the theoretical extension is applied to predict the ultimate punching shear strength of eight slabs with several levels of CFRP reinforcement and designed to fail in shear. The results show good agreement between the predicted and experimental values.