Dynamic responses of reinforced ultra-high performance concrete members under low-velocity lateral impact

This paper presents a combined experimental and numerical study on the low-velocity lateral impact behavior of reinforced ultra-high performance concrete (UHPC) members. Firstly, a total of eleven steel bar reinforced UHPC and two reinforced normal strength concrete (NSC) control specimens with the identical dimensions (300 mm × 300 mm × 2200 mm) were prepared and tested under drop hammer impact. By examining the influences of impact energy (16.66–33.32 kJ) and the axial force (140–1400 kN) on the dynamic damage and responses of specimens, the outstanding impact resistance of UHPC members is validated and assessed quantitatively. Besides, the presence of axial force can effectively improve the lateral impact resistance of the UHPC members, particularly the recovery of deformation. Secondly, based on the commercial finite element (FE) program LS-DYNA, a FE model was established to predict the impact behavior of UHPC members. The Continuous Surface Cap (CSC) model for NSC was adopted, and the corresponding model parameters for UHPC were calibrated based on a series of test data, i.e., static compressive and direct tensile tests, dynamic compressive and tensile tests, triaxial compressive tests, and hydrostatic tests. Furthermore, the generation method of CSC model parameters for UHPC was proposed, which was fully validated by comparing with the present and existing low-velocity impact test data on reinforced UHPC and UHPC filled steel tube (UHPC-FST) members.