Analysis of the New Simplified Bond‐Slip Law for FRP Flexural‐Externally Strengthened RC Beams Through Finite Element Modeling

ABSTRACT This study aims to develop a nonlinear finite element (NLFE) model to predict the response of carbon‐fiber reinforced polymer (CFRP) flexural‐externally strengthened reinforced concrete (RC) beams subjected to a three‐point flexural test. The FE ANSYS code is employed to model both a control RC beam and CFRP flexural‐externally strengthened RC beam, using experimental data available in the literature. A 3D NLFEA incorporating six cohesive zone material model (CZM)/bond‐slip laws is employed to simulate the behavior of CFRP flexural‐externally strengthened RC beam. Out of the six bond stress‐slip models examined, the Ko et al.'s bilinear CZM model exhibits the closest agreement with experimental results, predicting the ultimate load with a minimal deviation of 0.31%, and thus proving to be the most accurate model. The comparison underscores the effectiveness of the Ko et al.'s bilinear CZM model in accurately simulating the behavior of CFRP flexural‐externally strengthened RC beam. Subsequently, a parametric study is conducted to examine the effects of concrete compressive strength, tensile reinforcement diameter, and the elastic modulus of the epoxy resin on the CFRP flexural‐externally strengthened RC beam. Based on the findings obtained from the parametric study, curve‐fitting models were developed using Python programming to estimate the new simplified bond‐slip law for maximum bond stress, the slip at maximum bond stress, and the ultimate slip. These findings formed the basis for constructing reliable predictive models. The accuracy of the models was evaluated using the coefficient of determination ( R ² ).