Research on failure modes identification of concrete-filled steel tube members subjected to lateral impact

Concrete-filled steel tube (CFST) members are susceptible to impact loads throughout their life cycle. It is vital to develop an extensive and efficient technique to distinguish CFST damage degree since the high impact energy will severely harm CFST columns. The sectional stress and strain profiles were investigated numerically using LS-DYNA model in this research, then a theoretical method of CFST dynamic flexural capacity was established considering strain rate and steel tube circumferential pressure. Based on steel ultimate strain, an analytical approach to resistance-deflection constitutive model consisting of CFST elastic, plastic, and cracking stages was presented. The mechanics model of CFST local deformation was derived using geometric relations. A two-degree-of-freedom model was applied to solve impact response, then the flow of identifying CFST failure modes was proposed adopting maximum deflection and resistance-deflection constitutive model.