Numerical Investigation on the Seismic Performance of a Multistorey RC Building under Increased Seismic Demand Using Lead Rubber Bearing Isolation

Objectives: To examine the seismic behaviour of an Reinforced Concrete (RC) building for Seismic Zone II while investigating the effectiveness of Lead Rubber Bearing (LRB) isolation system for that structure in Seismic Zone V.

Method: The G+8 RC building is designed in ETABS following IS 456:2000 and IS 1893:2016. After verifying its safety under Zone II seismic loads, the building is analysed under the more severe Zone V conditions, where several structural members get fail. An LRB isolator is designed in ABAQUS and incorporated into the ETABS model. The building’s performance is evaluated using parameters such as base reaction, storey displacement, storey drift, time period, beam bending moment, beam shear force and column axial force.

Findings: The structure was safe under Zone II loads, whereas several members failed under Zone V seismic loading due to increased seismic demands. Compared to Zone II, increases of 260.2% base reaction, 260.6% storey drift, 252.1% storey displacement, constant time period, 148.3% bending moment, 105.6% shear force, 15.1% and 4.3% axial load in two selected columns were observed. With LRB isolation, reductions of 46.9% base reaction, 13.3% storey drift, 8.68%bending moment, 22.4% shear force, 14.9% and 11.1% axial load were achieved, while storey displacement and time period increased by 66.1% and 97.3%, respectively, compared to the fixed-base Zone V structure. Consequently, the failed members satisfied the design criteria after isolation. Novelty: It is evident from the study that there is an effective way to enhance seismic performance through the use of LRB base isolation system in order to increase seismic capacity without altering member size in low-seismic structure. Keywords: Seismic Performance, Multistorey Reinforced Concrete Building, Lead Rubber Bearing, Base Isolation, Storey Displacement