Dynamic response and post-impact damage assessment of steel reinforced concrete columns under lateral impact loads

Steel reinforced concrete (SRC) columns exposed to collision risks need to be designed to resist impact loads. Since SRC columns are key vertical load-bearing members, assessing collapse risk and residual capacity of columns after impact is essential. This paper studies the impact resistance of SRC columns subjected to horizontal impact loads and the residual mechanical properties of impact-damaged columns under axial load. First, dynamic impact tests were performed on five SRC columns to study the influence of impact location on the dynamic behavior of the SRC columns. The impact process, damage patterns, impact forces, and lateral displacements were analyzed to elucidate the working mechanism. Test results show that the damage mode of columns converts from shear-dominated damage to flexure-dominated damage as the impact height increases. Then, static compressive tests were performed on one undamaged SRC column and five impact-damaged SRC columns to obtain the failure modes and axial load-carrying capacities. The findings demonstrate that impact-induced damage patterns affect final failure modes observed in residual axial compression tests. Finally, finite element (FE) models were established and validated against the results of both impact and axial compression tests. The FE model was used to obtain the distributions of sectional shear forces, sectional bending moments, and impact energy among each component of the SRC column, as well as to analyze the influences of axial load ratio and impact velocity on impact behavior. Based on the result of the FE analysis, an empirical formula is proposed for predicting the residual strength of SRC columns after impact.