13. Effect of Soil Structure Interaction on the Response of a Lumped Mass Model

The dynamic response of the structures, subjected to strong ground motions, depends on the behavior of the soil in and around the structure. The effect of soil-structure interaction is neglected by analysis and designers due to a lack of code provisions. Damage to structures in recent earthquakes has indicated non-uniform distribution of damage, which indicates the effect of soil structure interaction (SSI). In literature, there is no clear consensus on the beneficial or detrimental effect of SSI effect and thus its incorporation in modelling is not prescribed in some seismic codes. In this study, a lumped mass system has been modeled to study the effect of soil-structure interaction. Non-linear time history analysis was performed on this model using ground motions from two major earthquakes in Uttarakhand region. The displacement of the lumped mass was monitored for both cases, i.e., fixed and flexible base conditions. The peak values of displacement time histories are tabulated and plotted versus the corresponding peak ground acceleration. The results indicate that incorporating the effect of soil-structure interaction leads to an increase in the displacement of the structure at certain sites.