Seismic Response of Steel Frame by Considering Soil-Structure Interaction under Seismic Sequence

Seismic sequence as a result of occurrence of strong and moderate earthquake ground motion in a short time strongly affects the seismic response of structures. This kind of excitation causes, in many cases, more deteriorated effects compared to the corresponding single ground motion. The aim of this paper is to investigate the effect of seismic sequence of earthquake ground motion on the seismic responses of steel moment frame structures considering soil-structure interaction (SSI). To this end, four steel moment frames with 8 and 16 stories are considered each of which have three and six bays. Soil-structure-interaction is considered by employing dampers and springs having specified damping and stiffness through cone method. For modelling SSI effects, three types of soil based on standard 2800 are considered.  The time history of responses show that the relative displacement of structure is increased when the structure is subjected to the seismic sequence. As a result, the damage induced to the structure. It is noteworthy to say that the effect of seismic sequence is more in soft soil. The obtained responses show that a special attention should be paid for designing of steel structures in high seismic zone when they are subjected to seismic sequence excitation. Furthermore, soil-structure-interaction is an important parameter that should be considered for such conditions.Therefore, it is recommended that the effects of seismic sequence and soil-structure-interaction should be accounted for better estimation and evaluate accurate responses of steel shear frame.