seismic structural response of steel frames considering soil-foundation-structure interaction

Prescribed response spectra have been proposed by seismic design codes to consider the effect of both soil and superstructure parameters as well as the seismic zone in evaluating the earthquake equivalent static force. the codes also take into account soil-foundation-structure interaction (sfsi) by modifying the natural period and associated dampingof the corresponding fixed-based (fb) system. although it is believed that considering sfsi is beneficial and can cause reduction in the response of structures, such belief should be supported by several comprehensive investigations to be considered diversely valid for various structures and soils.