investigation the seismic performance of structures with underground stories considering the soil-foundation-structure interaction

evaluation of the seismic performance of complex structures is the most important issue by the significant development in seismic analysis methods. one of the important tools in the evaluating seismic vulnerability of structures is using accurate analysis methods such as incremental dynamic analysis to determine seismic demand and capacity of structures. some seismic standards are suggested simplified methods for analysis and design of buildings with underground stries, this paper is studied the seismic performance of this type structures. for this purpose, a 12-story building with three underground stories is designed according to iranian seismic codes. the stiff soil (type ii) is considered under the foundation and the backfill soil is alos assumed to be dense. abaqus software is used for developing two types of models, at the first models the soil media, foundation, walls, structure nad also interaction problems are considered., but at second-model, only 12 above ground stories, with fix-bases is considred. the nonlinear incremental dynamic analysis is used for evaluating the sismic behavior of models. ten far-fault ground motion records are used for time history analyses. the demand and capacity of models are calculated at two limit states, immediate occupancy and collapse prevention, for evaluating the seismic performance of buildings. the results are shown that at collapse prevention limit states, the 5% damped first-mode spectral acceleration and maximum interstory drift at the both of capacity and demand are increased for models that considered the interaction effects and underground stoies.