Abstract: “In this paper, the effects of soil-structure interaction is evaluated in seismic response of non-geometric vertically irregular steel buildings. Non-uniform distribution of mass along the height of a 10 story steel frame building with fully restrained moment connections is investigated in the framework of random analysis. Frequency-independent spring and dashpot set in parallel was used to involve soil-structure interaction effects in the analysis procedure. The results are compared in form of the maximum mean square value of story drift response. It is observed that foundation flexibility varies demand distribution through structure height. Depend on the position of heavier stories, the maximum mean square value of story drifts change, as well. Compare to the regular structure, mass irregularity through the bottom half stories of structure has the maximum demand difference in case of fixed base model. Among the flexible base structures, mass irregularity of the 5th floor has the maxim”

Keywords: Mass irregularity,Non-stationary random ground motion, Soil-structure interaction, Seismic response, Steel shear buildin