Shaking table and pushover tests on subway station improved by truncated columns

Abstract

Previous studies have demonstrated that reducing earthquake-induced damage to central columns in underground structures can effectively prevent the collapse of overall structures. Truncated columns (TC) are less likely to experience severe damage during lateral deformation because the partial release of the constraints at both ends of the columns helps maintain their integrity. This approach can effectively enhance the seismic performance of the overall underground structures. In this study, pushover and shaking table tests were conducted to investigate the seismic performance of a subway station using TC columns compared to that using the cast-in-place columns (CC). These tests aimed to examine failure modes, structural stiffness, lateral deformation and load-bearing capacities, acceleration and deformation responses of the underground structures. The results from the pushover tests indicated that the initial stiffness of both structures-those with TC and with CC-was equivalent. On the other hand, the shaking table tests showed no significant differences in the dynamic responses of the two types of underground structures under small earthquakes. However, the vertical ground motions exacerbated damage to the structures. Although the lateral load-bearing capacity of the structure with TC is somewhat lower, the movements between the column ends and beams during loading enhance the structure’s ability to adapt to the deformation of surrounding soil due to the release of column end constraints. As a result, the seismic resistance of the overall underground structures is improved. It is important to note that the ceiling slab and sidewalls in the structures with TC are more likely to crack during earthquakes, thus requiring additional efforts to prevent leakage. The findings of this study provide experimental evidence that supports the seismic control of underground structures.