Residual strength of CHS short steel columns after lateral impact

The purpose of this research was to experimentally investigate the effect of lateral impact on the residual axial strength of circular hollow section (CHS) columns. In this study, forty-eight specimens including three specimens left untreated for comparison were studied to investigate the effect of the impact energy, impact location and diameter-thickness ratio on the residual axial strength of CHS columns. The failure modes, residual axial strength, initial stiffness and ductility of impacted specimens were reported. The test results indicated that lateral impact has an evident effect on axial compression behaviour of CHS columns. With the increase of impact energy, the lateral plastic deformation increased and the residual axial strength reduced. In addition, the reduction of axial strength of specimens reached 40.98%, compared with that of specimens untreated. The results also show that the impact location has an evident effect on the axial bearing capacity of CHS columns, and through the analysis of the effect of diameter-thickness ratio on the residual strength of CHS columns, it could be observed that specimens with large thicknesses, have a better performance of impact resistance. Based on the extensive experimental analysis, calculation equations were proposed to predict the residual axial strength of CHS columns tested, providing reasonably good correlation with the experimental results. The research results can still provide the basis for further theoretical and relevant finite element researches.