Numerical investigation of GFRP-bonded plates with end anchorage systems for concrete beam strengthening: Optimization and performance analysis

The aim of this paper is to introduce a new anchorage system that uses bolts to mechanically fasten the GFRP plate to the concrete substrate, with the goal of preventing debonding and improving overall performance. The study examines the four materials, which include concrete, GFRP, steel (bolts), and adhesive (used for bonding GFRP plates), along with their interfaces. GFRP/concrete, bolt/concrete, bolt/GFRP layer, and GFRP/End GFRP layer form part of these interfaces. For simplicity, the research is primarily focused on the interface between GFRP and concrete, where debonding failure can lead to failure of FRP-reinforced concrete beams. The results were in agreement with the experimental study, indicating that bolts can effectively prevent debonding failure by predicting crack patterns, failure modes, and deformation characteristics. The diameter of the bolts was found to have a significant impact on structural performance, resulting in an increase in ultimate load capacities of up to 162.46%. For 10 mm diameter bolts, the two-layer configuration (2C) was the most effective, but vertical bolt arrangements had better displacement capacity. In addition, by adjusting bolt size and layout, the anchorage system can alter crack propagation paths, potentially shifting the failure mode from flexural to shear, and the system was able to boost load-carrying capacities and improve ductility indexes.