Nonlinear behavior analysis of flexural strengthening of RC beams with NSM FRP laminates

This paper proposes an analytical method for predicting the nonlinear behavior of reinforced concrete (RC) beams after flexural strengthening with near surface mounted (NSM) fiber reinforced polymer (FRP) laminates. With a gradual increase in the beam curvature and a step-by-step numerical integration method, an algorithm model was designed for predicting the load-deflection response of RC beams strengthened with the NSM technique. Based on the bond mechanism between the NSM FRP laminates and the surrounding concrete, the available calculation methods of the load bearing capacity of RC beams with NSM FRP laminates were derived according to the bearing capacity model for the strengthened RC structure with FRP materials. Using the proposed model, the load-deflection responses of five flexural strengthened RC beams with NSM carbon FRP (CFRP) laminates were analyzed and verified against the experimental results. The presented results indicate that the proposed model based on the available test data can accurately analyze the tensile stresses of the NSM CFRP laminates. Moreover, the results prove the feasibility of the designed algorithm model in precisely predicting the nonlinear behavior of RC beams strengthened with NSM CFRP laminates. The proposed algorithm model could provide a much needed link between structural design and nonlinear behavior analysis of RC structures strengthened with the NSM technique.