Seismic Response of Steel Braced Vertically Irregular RC Frame Considering Soil Structure Interaction

Abstract

Bracing system is one of the structural system which forms an integral part of the frame. Steel bracings have been used extensively as a structural system to resist seismic loads in the recent times due to their passive energy dissipation property. Steel bracing being economical and easy to erect assists to enhance the strength and retrofitting properties of a structure and their effective performance in controlling seismic effects on the structures during earthquake. In the present study the effect of soil structure interaction (SSI) on multi-storied vertically irregular RC buildings on a horizontal soil profile with varying underlying soil types using concentric chevron bracing is investigated. A G+4 story vertically irregular building (with bracing and without bracing) is analyzed as per IS 1893:2002 using ANSYS.v19 software with fixed and flexible foundation. The soil structure interaction effects on the flexible foundation are analyzed and the effectiveness of the chevron braced frame on the seismic performance of the building is studied. Two different combination of the soil profile for the same building with bracing and without bracing and for free headed and fixed headed flexible foundation condition has been analyzed in response spectrum method for Winkler theory. The performance of the building is evaluated in terms of displacement, storey drift and bending moment along the pile and time period. It was found that the chevron bracing with fixed headed flexible foundation significantly contributes to the structural stiffness and reduces the displacement compared to the bare frame and also the SSI effect considering the water table showed more displacement when compared to the structure on saturated hard soils. Time period increases when SSI was considered.