Numerical analysis of dynamic collapse response of beam–column substructures under impact loads

To investigate the collapse resistance performance of steel-frame structures at varying scale ratios, numerical simulations were performed to scrutinize the influence of different scale ratios on the dynamic response of beam–column substructures subjected to impact loads. In this study, two drop-hammer impact tests were modeled and simulated, their results were compared, and the accuracy of the finite element modeling method was verified. Concurrently, a detailed model of a double half-span beam–column substructure was established to examine the effect of impact energy variations (altering the mass and velocity of the drop hammer) on the structural impact force and vertical displacement. This study analyzed variations in the impact force, impact time history, vertical displacement, internal forces, and energy absorption for models with different scale ratios when altering the impact energy. Finite element analysis results indicated that the impact velocity of the drop hammer affected the peak impact force of the substructure, whereas the drop-hammer mass influenced the force plateau and impact duration. Both the impact duration and maximum vertical displacement were positively correlated with the impact of the drop hammer and were approximately linearly positively correlated with the impact kinetic energy, resulting in the establishment of a linear fitting model between the maximum vertical displacement and the impact energy. For scaled-down substructures, variations in the impact energy could be achieved by adjusting the drop-hammer impact velocity (drop height). A proposed scale ratio for the substructure drop-hammer impact anti-collapse test is provided.