Debonding detection in FRP-strengthened concrete structures utilising nonlinear Rayleigh wave mixing

Abstract

This paper reports an investigation on the use of Rayleigh wave mixing method for the debonding detection in concrete structures strengthened with externally bonded fibre-reinforced polymer (FRP) composite plates. A three-dimensional (3D) finite element model is developed to simulate the propagation of Rayleigh waves in FRPstrengthened concrete structures. In this model, the frequency domain of the transmitted waves shows the generation of second harmonics and combinational harmonics on account of debonding. The numerically simulated results are then experimentally validated with carbon fibre-reinforced polymer (CFRP)-plated concrete blocks containing two different sizes of debonding. Based on the experimentally verified numerical model, parametric studies are then conducted, where a nonlinear debonding crack growth parameter is proposed. The nonlinear Rayleigh wave mixing method is proven to be practical, reliable, and sensitive for detecting debonding at bonded concrete-FRP interfaces in FRP-strengthened reinforced concrete (RC) structures.