Dynamic response of FRP-UHPC hybrid bar reinforced concrete column against the lateral impact

Due to the advantages of high strength-to-weight ratio and corrosion resistance, fibre-reinforced polymer (FRP) bars have been widely investigated to reinforce concrete members. However, due to the brittle nature of FRP bars, the FRP bars reinforced concrete (RC) members are susceptible to brittle failure when subjected to extreme impact loads. This study uses a novel FRP-ultra-high-performance concrete (UHPC) hybrid bar to replace the FRP bars in RC members to increase their impact-resistant capacities. The FRP-UHPC hybrid bar comprises a central FRP bar, an external confining FRP tube, and a UHPC filler. As compared to traditional FRP bars, this hybrid bar exhibits higher ductility, load-carrying capacity and shear resistance capacity. The dynamic response of hybrid bars reinforced concrete (HBRC) column against the lateral impact was numerically investigated in this study. Numerical models were developed and validated using the existing test data, and the dynamic responses, including the damage pattern, impact force-time histories, and mid-span deflection-time histories, were analysed and discussed. The simulation results indicate that the HBRC column exhibits ductile behaviour against the lateral impact and outperforms the FRP bars RC column in terms of impact resistance capacity. Furthermore, parametric studies were carried out to investigate the influences of different variables on the lateral impact behaviour of HBRC columns. Finally, the damage levels of HBRC columns with varying parameters were numerically evaluated, and an empirical formula was proposed.