Investigation on the Impact Response of Concrete Beams Reinforced with Hybrid Steel-BFRP Bars

An appropriate hybrid form of steel and fiber-reinforced polymer (FRP) bars in reinforced concrete members can prevent steel corrosion and ensure capacity and ductility. To investigate the impact resistance of concrete beams reinforced with hybrid steel and basalt FRP (BFRP) bars, a three-dimensional numerical model was developed that takes into account the strain-rate strengthening effect. The validity of the numerical model was first verified. Subsequently, drop hammer impacts were simulated on 10 concrete beams reinforced with hybrid steel-BFRP bars to determine the influence of the BFRP bar proportion and position on their impact resistance. The results indicated that the level of concrete damage in the hybrid bar-RC beams is between those of the concrete beams with steel bars and concrete beams with BFRP bars. As the proportion of BFRP bars increased from 0 to 1, the peak impact force and internal force of the beams linearly decreased by 20%, the reaction force linearly declined by 50%, while the peak midspan displacement linearly increased by 20%. Except for the midspan deflection, the comparable degree of damage among beams with four different bar configurations indicates the equivalent impact resistance of the beams. The change in the frequency of the hybrid bar-RC beams before and after impact loading can reflect their impact resistance.