Junrui Zhang - 2024 QuakeCoRE Annual Meeting - Fracture Mode II Based Bond-Slip Model for Interfacial Behavior of Large-sized EB-FRP Strengthened RC Systems

Understanding the interfacial bond behavior between externally bonded fiber-reinforced polymer (EB-FRP) composites and concrete is crucial for effective structural strengthening, yet the complexity of debonding, a prevalent failure mode, makes accurately predicting the shear/slip response of EB-FRP systems challenging and in need of further investigation. This study introduces a unified semi-empirical bond-slip model with nonlinear and exponential segments, designed to predict the debond strain of EB-FRP systems by accounting for the concrete compressive strength, and joint geometry of FRP strips in terms of thickness and bonded length. Both 2D and 3D digital image correlation (DIC) systems were employed to investigate the debonding mechanism and measure the complete strain distribution. The bond-slip model is derived from 51 large-sized (1524 mm length, 457 mm width and 152 mm depth) single lap shear tests, specifically under the debonding failure mode, and utilizes the interfacial analytical method of fracture mode II along with multi-variable nonlinear regression analysis. A database of bond strength data from existing 1,659 tests was used to validate the model's predictions. Influencing bond indicators were identified through analytical reasoning, and the proposed model demonstrated accuracy in predicting the debond strain of EB-FRP systems and interfacial fracture energy. These predictions were validated against experimental results and compared favorably with existing complex models. The proposed bond-slip model shows strong agreement with existing research data, demonstrating its accuracy in predicting debond strain and simplifying the calculation of fracture energy and debond strain, thereby offering a practical tool for both academic research and industry practice.