Abstract:
To investigate the mechanical properties of hybrid fiber-reinforced concrete tunnel segments reinforced by GFRP bars, static bending tests were conducted on three steel-polypropylene fiber-reinforced concrete segments with different GFRP reinforcement ratios. The failure modes, bearing capacity, and crack propagation mode of the specimens were obtained. Considering the interface bonding between the GFRP bars and hybrid fiber-reinforced concrete, finite element models of the segments were established using ABAQUS, and the effects of different hybrid fiber content and reinforcement ratios on the flexural bearing capacity of the segments were analyzed. The analysis results indicate that the failure of hybrid fiber-reinforced concrete segments reinforced by the GFRP bar are mainly caused by the penetration of the main crack at the mid-span and the fracture of the GFRP bar. Increasing the reinforcement ratio of the longitudinally tensioned GFRP bars can effectively enhance the bending capacity of the segments while keeping the fiber volume fraction constant. In numerical calculations, a finite element model considering the interface bond-slip between the GFRP bars and hybrid fiber-reinforced concrete can more accurately simulate the cracking load, ultimate load and, bending stiffness of the specimens. Increasing the volume fraction of hybrid fibers effectively reduces the reinforcement ratio of the segments and improves the deformation resistance of the segments at the same load-carrying capacity. Through regression analysis, a calculation equation for the relationship between fiber dosage and reinforcement ratio is proposed, and the theoretical calculation results agreed well with the numerical ones.