Effect of adhesive properties on the bond behaviour of externally bonded FRP-to-concrete joints

Abstract

The influence of adhesive properties on the bond behaviour of externally bonded fibre-reinforced polymer (FRP)-to-concrete joints is the focus of this paper. First, FRP-to-concrete double-lap shear specimens were tested with different types of bonding adhesives. The test results indicate that when softer adhesives are adopted, the peak load, interfacial fracture energy and FRP effective bond length increase while the peak shear stress decreases. Then, a finite element (FE) model including the adhesive layer was proposed to further investigate the influence mechanism of the adhesive properties. A numerical parametric study indicates that the adhesive tensile strength, ultimate strain, elastic modulus and thickness all have varying degrees of impact on the bond behaviour of FRP-to-concrete joints. Finally, a bond-slip model that considers the adhesive elastic modulus is proposed based on experimental and numerical results. To validate this model, a comprehensive test database that includes 128 FRP-to-concrete joints with different adhesives was collected. The proposed model has been shown to have a higher accuracy and lower dispersion than the existing models for the prediction of the peak loads of FRP-to-concrete joints with different adhesives.