Impact and Residual Capacities of Ultra-High-Performance Fiber-Reinforced Concrete Beams with Steel Rebars

Abstract

This study aims to investigate the structural impact and residual performances of ultra-high-performance fiber-reinforced concrete (UHPFRC) beams. To this end, eight large-sized steel bar-reinforced UHPFRC beams were fabricated and tested under quasi-static and impact loads. Impact load was applied using a drop-weight impact test machine, where the incident kinetic energy and impact velocity were 4.5 kJ and 4.2 m/s, respectively. Residual flexural performance after impact damage was evaluated by comparing the flexural performances of undamaged beams. Results demonstrated that the impact and residual capacities were significantly improved by including 2 vol.% of steel fibers. The beams with longer steel fibers (Lf = 19.5 and 30 mm) exhibited better impact and residual performances including a lower maximum mid-span deflection and a higher residual moment capacity than those with shorter fiber (Lf = 13 mm). Finally, the residual capacity of UHPFRC beams was closely related to the maximum mid-span deflection under impact and the quasi-static flexural behavior of the undamaged beams