SEISMIC RESPONSE OF COMPOSITE BUILDING FRAME WITH ALTERNATE BRACING SYSTEM CONSIDERING SOIL STRUCTURE INTERACTION (SSI)

Abstract

Conventional fixed-base analysis ignoring the effect of soil-flexibility carried out for the seismic design of buildings may result in unsafe design. Therefore, the effect of SSI is an important issue from the viewpoint of design considerations. Thus to evaluate the realistic behavior of structure the soil structure interaction (SSI) effect shall be incorporated in the analysis. In seismic analysis provision of bracing system is one of the important option for the structure to have sufficient strength with adequate stiffness to resist lateral forces. The different configuration of these bracing systems alters the response of buildings, and therefore, it is important to evaluate the most effective type and location of the bracing systems in view point of stability against SSI effect. In present study, two RC building frames, G+10 and G+15 with six different combinations of steel bracing system at alternate locations incorporating the effect of soil flexibility is considered in order to investigate the effectiveness of bracing system to control SSI. The seismic analysis is carried out using equivalent static method as per IS 1893-2002 The study is carried out using Elastic continuum approach(ECM) The influence of SSI on various seismic parameters and the flexural parameters are presented. The changes in all these parameters due to provision of steel bracing system are studied in order to evaluate its effectiveness in controlling the SSI effect. The study reveals that, steel bracing system plays important role to control SSI effect and it is observed that diagonal bracing placed at mid periphery are more effective, in resisting seismic load considering SSI.