EFFECT OF BASE ISOLATOR ON THE STRUCTURAL RESPONSE OF REINFORCED CONCRETE MULTISTORIED BUILDING UNDER SEISMIC LOADS

This study investigates the effect of base isolator on the structural responses of multistoried reinforced concrete building under time history earthquake loading. In the present study, six-storied reinforced concrete buildings with both conventional and isolated bases have been modeled. Conventional building has been modeled with fixed support whereas base-isolated building has been modeled incorporating rubber bearing near the base of all columns. Modal analysis has been performed to get an idea of possible mode shapes of the building. After that time history analysis has been performed in order to investigate the effect of seismic loading on the building structure with respect to time. The structural responses of time history analysis such as time period of different modes, storey displacements, storey acceleration, and base shear have been obtained from both conventional and base-isolated buildings. Finally, a comparative study of structural responses has been carried out between those two structures. It has been found that fundamental time period of base-isolated building is increased by 28% compared to conventional building. Moreover, base shear value of the base-isolated structure is reduced by 69% and top storey acceleration is decreased by 75% compared to conventional building. This study reveals that isolation system reduces seismic responses significantly.