Influence of Soil-Structure Interaction on Response of a Multi-Storied Building against Earthquake Forces

In the analysis of structures subjected to earthquake forces, it is usually assumed that the structure is fixed at the base to simplify the mathematical problem. This assumption leads to gross error in assessment of overall response under dynamic loads. Past history records reveal that the rate of occurrence of earthquakes is an increasing phenomenon. In recent years, many failure examples of rigid structures resisting on flexible soils made considerable advanced studies in the field of soil-structure interaction. The interaction phenomenon is principally affected by the mechanism of energy exchanged between the soil and the structure during an earthquake. In the present investigation, the location of new capital, Amaravati, of the state Andhra Pradesh is chosen as the study area which consists of different types of soil / rock profiles at different locations. Many high rise structures are expected in future in the new city. The influence of soil structure interaction on seismic response of such high rise buildings is a major concern to incorporate the necessary changes in designing such structures. A twelve storied building (multi-storied building), with lower two stories for parking (soft stories) and the remaining ten stories for commercial and residential purpose, and is chosen for the analysis. This region falls under seismic zone III. Earthquake analysis is carried out when similar structures rests on different types of soils and the results of fundamental time periods, base shears and displacements are compared with the results obtained from fixed base condition. The investigation indicates the necessity of considering soil-structure interaction, particularly when the structure rests on loose soils.