Guided wave for debonding detection in FRP-retrofitted concrete structures

Abstract

Applications of fibre-reinforced polymer (FRP) composites for retrofitting, strengthening and repairing concrete structures have been growing dramatically. FRPs have high specific strength and stiffness compared to conventional construction materials, e.g. steel. Ease of preparation and installation, resistance to corrosion, versatile fabrication and adjustable mechanical properties are other advantages of FRP composites. However, there are serious concerns about long-term performance, serviceability and durability of FRP applications on concrete structures. Therefore, structural health monitoring (SHM) in FRP-retrofitted concrete structures must be given special consideration. Proper defect detection methods are a crucial part for SHM. This paper presents a study on investigating the application of guided waves for detecting debonding between FRP and concrete structures. A three-dimensional finite element (FE) model has been developed to simulate generation and propagation of guided waves in FRP-bonded concrete elements, and scattering at debonding. Absorbing layers have been developed to provide a computationally efficient tool for investigating guided wave propagation and scattering characteristics in FRP-retrofitted concrete structures. Phase and group velocities arecalculated from FE simulations and then compared with results obtained from analytical solutions. To examine the wave scattering features at the defect, debonding between FRP and concrete issimulatedin the FE model. The FE model isthen used to investigate the feasibilityof guided waves on debonding detection.