Formation of multiple plastic hinges in concrete flexural members with segmented hybrid reinforcement

This study investigates the formation of multiple plastic hinges in concrete flexural members through pushover experiments and theoretical analyses. In the tests, two or three plastic hinges were formed in the lower regions of the members by incorporating segmented hybrid reinforcement with steel and fiber-reinforced polymer (FRP) bars. Ductile failure dominated in the traditional steel-reinforced plastic hinge, which remained the preferred mode. Theoretical analyses showed that a gradient distribution of flexural strength along the member height was created by the segmented hybrid reinforcement. The formation of multiple plastic hinges became possible when the flexural strength gradient matched the distribution of external bending moments. The elastic FRP bars continued to carry tensile force after steel yielding, enabling a sustained increase in post-yield flexural strength and supporting the stable development and regulation of plasticity and failure modes across multiple hinge regions. The research results demonstrated that members with multiple plastic hinges are characterized by distributed inelasticity and a controllable ductile failure mechanism. Compared with their traditional counterparts, members with multiple plastic hinges exhibited substantially improved deformation capacity and energy absorption under monotonic loading.