Impact behavior of concrete-filled steel tube with cruciform reinforcing steel under lateral impact load

Abstract

The objectives of this research are to investigate the behavior of cruciform steel-reinforced concrete-filled steel columns under impact load through experimental and numerical studies. The effects of impact velocity/height, axial pressure, thickness of steel tube and boundary conditions on the impact resistance of composite columns are studied through the tests of 16 specimens. The detailed progressive responses were recorded, including deformation mode, impact force-time history, deflection-time history and axial force-time history. Based on the test results, the impact resistances of steel-reinforced concrete-filled steel tubular columns and concrete-filled square steel tubular (CFST) columns are compared. In addition, FE models of the composite column are established using ABAQUS and validated based on experimental data. The strain rate effect of steel and concrete is considered in the model. The results show that the outer square steel tube effectively protects the internal steel-reinforced concrete. In the impact energy range of 17.02–51.08 kJ, the specimens only suffer minor bending deformation, which shows their excellent impact resistance. The ultimate plastic strain energy of square steel tube (EPT), cruciform steel section (EPS) and concrete (EPC) accounts for 56.4%, 18.2% and 25.4% of the total energy dissipation, which suggests that the steel tube (EPT) is the main energy dissipation mechanism of concrete-filled square steel tube columns.