Multiscale Study on the Bending Performance of the Hybrid FRP-Reinforced Track Composite Slabs

Abstract This study conceptualizes the track slab and self-compacting concrete filling layer as a composite system designed for equal service life, grounded in the mechanical characteristics of track slab structures. Using theoretical models, a comparative analysis was performed on reinforcement configurations and crack widths under three design methodologies: the limit state method, the equivalent stiffness method, and the performance-based design approach. Track composite slabs reinforced with steel, basalt fiber-reinforced polymer (BFRP) bars, and hybrid fiber-reinforced polymer (HFRP) bars were then fabricated and tested to evaluate their flexural performance. Drawing on the results of HFRP–concrete pull-out tests, an interface bond–slip constitutive model was subsequently developed. Based on this model, numerical simulations of the track composite slab were conducted. The findings indicate that performance-based design can effectively reduce the reinforcement ratio of HFRP while ensuring adequate crack control, thereby balancing structural performance with cost efficiency. Compared with BFRP reinforcement, replacing steel with HFRP bars enhanced the load-bearing capacity of the track composite slab by 100.57% and improved the ductility index by 8.89%. Moreover, the developed bond–slip model accurately captured the mechanical response of HFRP-reinforced track composite slabs, highlighting the value of service-life design principles and performance-oriented methods in advancing new-type ballastless track structures.