Effect of the bond-slip law on the bond response of NSM FRP reinforced concrete elements

Abstract

The Near-Surface Mounted (NSM) technique with Fibre Reinforced Polymer (FRP) reinforcement as strengthening system of concrete structures has been broadly studied during the last years. In this methodology, it is widely accepted that the bond behaviour between FRP and concrete, usually defined by a local bond-slip law, is a crucial factor for the efficiency of the FRP strengthening system. This paper studies the effect of the bond-slip law shape on the load capacity, the effective bond length, the slip of the joint, and the shear stress distribution along the bonded length, which are essential parameters on the strengthening design. A numerical procedure based on finite differences method to solve the governing equations of the FRP-to-concrete joint is developed and validated. Then, a parametric study is performed. The effect of the shear bond strength, slip at the bond strength, maximum slip and friction branch, on the parameters previously described is discussed.