Seismic Performance Evaluation of Multi-Story Subway Structure Based on Pushover Analysis

Since the seismic performance of a modern subway station remains unclear, it is of urgent need to clarify it through a simple, yet rigorous method. So far, the pushover analysis is a powerful tool for evaluating the expected seismic performance of building and bridge structures. It is a static elasto-plastic method, so no complicated constitutive model is needed. In this paper, a static pushover analysis is conducted on a multi-story subway structure in Shanghai through the general purpose finite element code, ABAQUS. An inverse triangle displacement pattern obtained from non-linear dynamic time history analysis is determined as the lateral load pattern and is imposed on the side wall of the structure in pushover analysis. The damaged plasticity model and idealized elastic-plastic model are adopted for concrete and rebar, respectively, to trace the nonlinear behavior of the materials. The numerical results indicate that the deformations of some floors of the underground structure are different from those of a surface structure because of the large floor-to-column-stiffness ratio. Furthermore, the seismic failure mechanism of a subway structure is a global one, and the columns on the bottom floor are the vulnerable spots where flexural failure, rather than shear failure, occurs.