Development of the EBROG strengthening technique for RC beams using hybrid CFRP–BFRP and U-wrap anchorage

This study aims to improve the EBROG technique by incorporating a U-wrap anchorage with and without side grooves and utilizing a hybrid fiber-reinforced polymer (HFRP) composed of CFRP and BFRP to achieve high load capacity while reducing brittle failure. The effect of reducing groove length is also investigated. The results showed a clear improvement in the performance of all strengthened beams compared to the reference beam. HFRP provided a good balance between strength and deformability. The simplest strengthened beam, containing three longitudinal grooves, achieved an 86% increase in ultimate load with only a 20% reduction in deflection. Beams incorporating the U-wrap achieved even better results, delaying the first cracking by up to 169% and increasing the ultimate load by 157%, while also achieving maximum deflection. Approaching the reference beam, the U-wrap restricted the concrete cover and transformed the separation from the edges into U-wrap-free areas. It also increased the area under the curve by up to 53%, indicating an improvement in ductility and an improvement in stiffness by 82%. Reducing the length of the longitudinal grooves achieved results similar to full groove beams, indicating the possibility of reducing the length of the grooves. HFRP improved the overall structural performance. It also reduced the strengthening cost because BFRP is less expensive than CFRP. Adding U-wrap to the EBROG technique is a highly worthwhile addition. The study compares experimental results with analytical models from ACI, fib 90, and previous studies. It found convergence with certain analytical models; however, modifications are required to align them with EBROG technology.