Flexural behavior of RC beams strengthened with prestressed GFRP bars and ECC

Purpose To overcome the limitations of conventional strengthening methods in terms of crack control and durability, this study aims to propose a novel hybrid strengthened beam (GESB) composed of prestressed glass fiber-reinforced polymer (PGFRP) and engineered cementitious composites (ECC). The proposed system aims to achieve comprehensive enhancements in the crack resistance, stiffness and load-bearing capacity of reinforced concrete (RC) beams. Design/methodology/approach A refined numerical model for the hybrid reinforcement beam was constructed, and its reliability was validated through comparison with experimental results regarding failure modes and load-deflection curves. Further, based on the validated numerical model, key design parameters were studied, including GFRP reinforcement ratio, prestress level and ECC layer thickness. Additionally, a multiple linear regression analysis was employed to establish relationships between various parameters and flexural bearing capacity. Findings The study indicates that the increase in GFRP reinforcement ratio and prestress level enhances the ultimate bearing capacity of GESB. As the reinforcement ratio increases, the ultimate load-bearing capacity of the GESB improves by 6.82%–19.86%. Specifically, the ultimate load-bearing capacity of GESB-30-20-12 is 19.86% higher than that of GESB-30-10-12. Although ECC layer thickness has a relatively minor impact on structural load capacity, it can enhance structural ductility through a multi-crack steady-state cracking mechanism. Originality/value Finally, a theoretical calculation model for the flexural bearing capacity of GESB was developed; predictions from this theoretical model showed discrepancies with experimental data within an error range of less than 8%, demonstrating its validity. This study provides a reliable solution for efficient strengthening of existing RC beams.