SEISMIC PERFORMANCE OF UNDERGROUND SHALLOW SUBWAY STATIONS IN SOFT SOIL

In the recent years there was a great improvement in the development of underground structures. Besides increasing the costs of construction، as well as the importance of the safety of transportations made the stability of structures against risks of earthquake very important. Underground structures behavior is different from super-structures due to their enclosure in soil or rock، so they have experienced a lower rate of damage than super-structures. But recent damages attracted more attention to the seismic analysis and design of underground structures. In this paper، the effect of earthquake and the importance of seismic analysis will be described and the seismic analysis method is presented briefly first، and then the simplified model analysis of Hashash is used، so two metro stations structures under two different levels were linearly analyzed، then pushover analysis method is used which is a simple and static non-linear analysis method in seismic analysis and design of structures. In this non-linear analysis، target displacement is computed by simplified frame analysis model. The finding of this study showed that the structure behavior was remained elastically in a large extent using this method. Hence، the design of the structures based on the performance level or reduction of the moment extracted from the Hashash Method is recommended.