Deflection modification factors of multistory buildings considering soil-structure interaction

In this investigation,attempts are made to examine the effects of soil-structure interaction on the deflection modification factor of multistory buildings and to clarify the role of deformable soil on this factor.A comprehensive study is conducted to investigate the effect of inertial interaction on displacement demand ratios in soil-structure systems with different structural characteristics and various non-dimensional parameters,using a simplified interacting model.A two-step regression analysis of the nonlinear,dynamic computer simulation results obtained,leads to a reliable and accurate formula for predicting deflection modification factors that incorporate foundation flexibility.The results illustrate that the application of deflection modification factors derived from fixed-base structures can lead to unsafe evaluation of the structures on soft soil.The proposed formula provides a useful tool for design engineers to incorporate the effect of soil-structure interaction into the evaluation of structural deformations.