Predicting Flexural Fatigue Performance of RC Beams Strengthened with Externally Bonded FRP due to FRP Debonding

Abstract

In this study, an analytical model is proposed to predict the flexural fatigue behavior of reinforced concrete (RC) beams strengthened with externally bonded (EB) fiber-reinforced polymer (FRP) laminates due to FRP debonding. The proposed model is capable of predicting the bond stress of EB FRP-concrete interface, flexural fatigue behavior, tensile strain of EB FRP, and beam deflection while considering bond heterogeneity due to different levels of fatigue damage. A trilinear bond-slip relation is adopted to represent the hardening, softening, and residual phase of the FRP-concrete bond stress. The fatigue bond degradation is characterized by a strain-dependent relation using available test data and incorporated into a one-dimensional mesh with appropriate boundary conditions to obtain the closed-form solution. To validate the proposed model, test results from several existing studies are compared with reasonable correlation. The parametric study shows that higher concrete compressive strength and axial stiffness of FRP with larger diameter steel rebar could be beneficial.