Residual axial bearing capacity of square steel tubes after lateral impact

The purpose of this research was to experimentally investigate the effect of lateral impact energy, impact location and width-thickness ratio on the residual axial bearing capacity of square steel tubes. In this study, the investigation on residual axial bearing capacity under different lateral impact energy, impact location and width-thickness ratios was carried out. Forty-eight specimens including three specimens untreated for comparison were studied to investigate the influence of the impact energy, loading position and width-thickness ratios on the residual axial bearing capacity of square steel tubes. The failure mode, residual axial bearing capacity, initial stiffness and ductility of specimens were presented. The typical failure modes observed from the tests include that with the increase of load, the deformation of impact location or bottom of the specimens increased and then local buckling occurred. The results indicated that with the increase of impact energy, lateral plastic deformation increased while the remaining axial capacity reduced and the maximum decreasing of bearing capacity reached 21%. The results also show that the impact location and width-thickness ratio exert no evident effects on residual axial bearing capacity of square steel tubes, in other words, impact location and width-thickness ratio possess a limited influence on the bearing capacity of square steel tubes. According to the experimental results, calculation equations were proposed to predict the residual axial bearing capacity for all square steel tubes tested, providing reasonably good correlation with the experimental results. The research results can provide reference for the further research.