Flexural behavior of damaged reinforced concrete beams repaired with hybrid composites materials

This paper presents an experimental study on the bending behavior of pre-cracked reinforced concrete (RC) beams repaired using hybrid composite materials, specifically carbon and glass fiber-reinforced polymers (CFRP and GFRP). A total of 12 RC beams with identical dimensions (10 × 15) cm 2 in cross-section and 60 cm in length were manufactured. Three beams served as reference specimens and were loaded to failure without being pre-cracked or repaired. These were compared to nine pre-cracked RC beams that were repaired using composite materials bonded to their surfaces, applied in three distinct geometric configurations. This study focused on assessing the effectiveness of FRP materials in repairing damaged RC beams. It also examined the hybrid effect of these materials on improving flexural behavior and aimed to establish the most effective geometric configuration for structural repair. The experimental results highlight the effectiveness of FRP composites materials in repairing damaged RC beams. Pre-cracked beams repaired with FRPs exhibited improved flexural performance compared to undamaged reference beams, regardless of the repair configuration. Additionally, FRP repairs delayed the formation and propagation of initial cracks. Moreover, test findings revealed that RC beams repaired using hybrid FRP systems displayed greater stiffness compared to their unrepaired beams. Specifically, pre-cracked beams retrofitted with CFRP strips on the bottom surface and GFRP strips inclined at 45° along the vertical faces showed a significant enhancement in load-bearing capacity and a considerable reduction in failure deflection, by approximately 57% and 43%, respectively. These findings confirm the effectiveness of using hybrid FRPs in this specific geometric repair configuration.