Study on progressive collapse resistance of corroded RC continuous deep flexural members strengthened with BFRP sheets

Durability degradation is a primary cause of failure in reinforced concrete (RC) structures. To mitigate this issue, externally bonded fiber-reinforced polymers (FRPs) have gained widespread attention due to their substantial impact on enhancing structural performance. This study investigates the effect of externally bonded FRP sheet on the anti-collapse performance of RC continuous deep flexural members under chloride ion erosion. Specifically, the study uses basalt fiber-reinforced polymer (BFRP) sheet, known for its excellent resistance to chloride ions, to reinforce corroded RC continuous deep flexural members. Quasi-static tests were conducted on four RC substructure specimens with a scale ratio of 1/3. The load-displacement curves, failure modes, and key beam deflection curves of both uncorroded specimens and corroded specimens—both without reinforcement and with different BFRP reinforcement methods—were compared. Additionally, the collapse performance of the structures was analyzed based on ductility and energy equivalence principles. The results show that corrosion and reinforcement did not alter the specimens' resistance mechanisms, which all exhibited beam, compressive arch, and catenary mechanisms. The use of BFRP reinforcement can significantly enhance the catenary action, but the effect of improving the compression arch action is very limited. At a 10 % corrosion rate, the ductility, energy dissipation, and safety reserve capacity of the specimens decreased by 14.0 %, 26.7 %, and 15.0 %, respectively. BFRP sheet reinforcement effectively restrains concrete expansion and enhances the shear capacity of the structure. The reinforcement schemes for specimens C-10-R1 and C-10-R2 increased the ductility, energy dissipation, and safety reserve capacity by 2.40 %, 1.19 %, and 13.43 %, and 29.20 %, 46.89 %, and 16.97 %, respectively. Compared with specimen C-10-R1, the reinforcement effect of specimen C-10-R2 was more pronounced. BFRP sheet plays a crucial role in improving the anti-collapse performance of corroded RC continuous deep flexural members and provides a valuable reference for the collapse resistance reinforcement of corroded RC deep flexural members.