Modal Pushover Analysis for Seismic Performance Assessment of Underground Structures

Pushover analysis as an efficient nonlinear static analysis method has been widely applied to the seismic inelastic performance evaluation of above-ground structures. Although it has the main advantage of high computational efficiency compared to nonlinear dynamic time-history analysis (THA), the assumption that the fundamental mode dominates structural response limits its application to long-period structures. Improved pushover analysis has been developed to consider the higher mode effect, named modal pushover analysis (MPA), but all research mainly focused on buildings and bridges. Since the mechanical behaviors of the underground structures and above-ground structures under seismic exaction are not exactly the same, so far, MPA suitable for seismic performance assessment of underground structures still has not been developed. Therefore, the aim of this investigation is to develop MPA for the seismic performance assessment of underground structures. A prototype subway station structure and a soft site are used to study the applicability of the developed MPA and compare it with the traditional pushover analysis procedure and nonlinear THA. Numerical analysis results of the subway station illustrate the applicability and potential of the developed MPA for underground structures.