Evaluation of Parameters of Bond Action between FRP and Concrete

This paper presents the evaluation of parameters describing bond action between fiber-reinforced polymer (FRP) and concrete in RC structures strengthened in flexure. The parameters were evaluated on the basis of fitting nonlinear finite-element results to experimental results from literature. Three-dimensional (3D) finite-element simulations were used to account for transversal effects without introducing any geometry-related correction coefficients in the material model. The parameters defining the material model, describing bond action, were initial stiffness, shear strength, and fracture energy of the FRP-concrete interface. Bilinear, trilinear, and exponential curve shapes were evaluated. The parameters were related to concrete tensile strength and shear stiffness of the adhesive. According to the analysis, the models provide a good estimation of ultimate load and strain distribution in FRP compared with test results. The results showed that whether the bond-slip curve was assumed to be bilinear, trilinear, or exponential has a minor effect.