LIMIT STATE DETERMINATION FOR A SUBWAY STATION STRUCTURE BY INCREMENTAL DYNAMIC ANALYSIS¹⁾

The seismic performance of the underground structures, is not well studied, while on the other hand, the seismic limit state determination is important for a performance-based design. In this paper, four limit states are defined in terms of the deformation and the waterproof performance of the structure while the maximum story drift angle (θ_max) is selected as the characteristic indicator according to the feature of the subway station. Based on a multi-story subway station in Shanghai, a two-dimensional finite element model of the soil and the structure is established and the seismic limit state of the subway station is investigated using the incremental dynamic analysis (IDA). Finally, the relation curve between the seismic intensity measure PBA (peak acceleration at the base of subway station) and structural performance indictor θ_max is established and the thresholds of θ_max for this subway station are obtained in the four limit states.