FRP U-Wraps for Mitigating Plate-End Debonding in FRP-Strengthened Beams: Finite Element Modeling and Parametric Study

Concrete cover separation (CCS) is a common type of delamination failures that occurs at the plate end in reinforced concrete (RC) beams strengthened in flexure using fiber-reinforced polymer (FRP) materials. The effectiveness of FRP U-wrap anchorage has been demonstrated in mitigating CCS failure, resulting in increased utilization of FRP composites for strengthening purposes. The current study presents the development of a nonlinear three-dimensional finite element (FE) model using ABAQUS software in order to simulate the flexural behavior and debonding failure of FRP-strengthened RC beams end-anchored with vertical FRP U-wraps. The cohesive zone model (CZM) is used in the developed FE model to predict the debonding failure of the anchored beams, considering the influence of relevant parameters. The validation of the FE model was achieved through comparisons with experimental data from the literature, which demonstrated good agreement. A parametric study was then conducted to investigate the impact of the design parameters of FRP U-wrap on the behavior of the anchored beams. The examined parameters included the width, layout, and height of the vertical FRP U-wraps. The findings of the FE parametric study have revealed that to successfully prevent plate-end debonding, it is critical to not only use the required area of vertical FRP U-wrap but also carefully consider the U-wrap layout. The FRP U-wrap should be placed at the plate-end region covering the concrete tooth created by the shear cracks, and the U-wrap layout should consider the detailing recommended in this study.