Seismic fragility assessment of an underground structure based on the experimental data from shaking table tests

Abstract

Classical seismic fragility assessment of underground structures always develops fragility curves or surfaces by analytical approaches, which is based on a suite of numerical simulations. In this study, a novel approach for seismic fragility assessment of underground structures based on experimental data is proposed, in which optimal intensity measure (IM), fragility curves and surfaces of underground structures can be simultaneously obtained. A set of shaking table tests of a subway station structure are firstly carried out to provide experimental data for optimal IM identification and fragility function construction. The results indicate that the peak ground acceleration, peak ground velocity and acceleration spectrum intensity are potential optimal IMs for fragility assessment of the underground structure, because they have the most or second correlated, practical, efficient, and proficient parameter values. Then, different scalar fragility curves and vector fragility surfaces in terms of different limit states are obtained. Different fragility probability results can be inferred from different fragility curves that developed by various earthquake IMs. The results also demonstrate that vector fragility surfaces have ability to offer more complete and robust information for probabilistic seismic performance assessment of underground structures than scalar fragility curves. The proposed approach and the obtained results provide the basis for addressing the entire framework of seismic resilience assessment of underground structures.