Effect of Inertial Soil Structure Interaction on the Seismic Performance of Typical Low to Mid-Rise Buildings of Pakistan

Abstract

Low to mid-rise reinforced concrete (RC) frame buildings are commonly constructed in the urban areas of many developing countries including Pakistan. In conventional modeling practice for the analysis and design of these buildings, the code-prescribed equivalent static force procedure is used while assuming the fixed-base support conditions of a linear structural model. Several studies, however, have shown that consideration of foundation flexibility and the soil-structure interaction (SSI) can significantly influence the predicted seismic performance of buildings. This study is focused on the seismic analysis of typical low- to mid-rise buildings in Pakistan while considering the effects of SSI and foundation flexibility. Using 3 existing case study buildings and considering all the soil types prescribed by BCP 2007, the SSI effects are modeled following the local practices. The seismic performance is predicted in terms of Time Period, Maximum Lateral Deflection, Story Drift, overturning Moment and Base Shear. It is shown that depending upon the soil stiffness and structural characteristics of buildings, the consideration of SSI effects and foundation flexibility can significantly affect the prediction of seismic demands. The result also emphasizes the need to develop simple guidelines for considering SSI effects in the modeling, analysis, and design of typical low- to mid-rise RC buildings in Pakistan.