Evaluation of Soil-Structure Interaction on RC Framed Irregular Building Under Varying Ground Conditions

During an earthquake the behaviour of any structure is influenced not only by the response of the superstructure, but also by the response of the soil beneath the structure. Structural failures in past have shown the significance of considering the impact of Soil-Structure Interaction (SSI) during analysis and modelling of structure in high seismic zones. The present study focuses on the influence of SSI in the analysis and design of an irregular 12-storey reinforced concrete frame building with and without shear wall. For integrating the effect of SSI, Models simulating three different soil-foundation conditions based on shear wave velocity with supported underneath raft, pile and raft-pile foundation using spring-dashpot mechanism and a fixed base condition for comparison purposes is carried out. Earthquake motion in response spectrum corresponding to zone V of IS 1893:2016 design spectrum is used to excite the finite element model of soil-foundation structure system. Responses in terms of variation in time period, base shear and storey displacement obtained from the analysis of the SSI models are compared with that obtained from conventional method assuming rigidity at the base of the structure. The results show that SSI effects in the dynamic behaviour of the structure are significant in altering the seismic response with a major increase in the vibration period as well as increase in the system damping and other structural parameters in comparison with the fixed base model, which does not consider the supporting soil-foundation.