New M.E.Thesis Submitted from Civil

Analytical Study of Base-Isolated Soft Storied RC Building by Manjot Singh

Abstract

During earthquakes, a great loss of life has occurred, which may sometime exceed up to mil lions of casualties. Various aseismic design methods and construction technologies have been developed to reduce the effects of earthquakes on structures. The seismic base-isolation technique is a passive response control concept which has been effectively used in buildings from the recent years to reduce the seismic demand. It shifts the time period of the structure from the predominant frequency range of earthquake and simultaneously reducing the inter-storey drift and floor acceleration.  In the present study, a G+4 storey RC framed building with fixed-base is analysed by equivalent load analysis and response spectrum analysis as per the procedure given in IS: 1893 (Part 1): 2002. Then the same building is analysed by using lead rubber bearings at the base to see the effect of base isolators. The isolation system is designed as per the requirements of ASCE/SEI 7-10 and then the equivalent load analysis and response spectrum analysis of the fixed-base and base-isolated building is done in SAP2000 software. The comparison of the total design seismic base shear, time period, absolute and relative floor displacement with storey height is done for the fixed-base and base-isolated building.  The comparison of the bending moment and area of steel in columns and beams with the storey height is also done.  The response of the base-isolated building is less than the fixed-base building for all the parameters considered. The total design base shear is reduced by 30.4% in the base-isolated building and the time period is increased from 0.696 sec to 2.5 sec. The relative floor displacements are reduced with the increasing height in base-isolated building and are less than the fixed-base building. The bending moments and area of steel in columns and beams are effectively reduced in the base-isolated building.