Hybrid isolation–damping systems improve structural resilience under near-fault ground motions, yet their application to plan-irregular buildings with strong torsional effects remains limited. This research investigates the seismic resilience of reinforced concrete (RC) frame buildings having plan irregularities. Fixed-base and lead rubber bearing (LRB) isolated models were developed employing three effective damping ratios, and nonlinear time-history analyses were performed using two ground motions of similar magnitude but varying PGA/PGV ratios, in accordance with Indian seismic standards. Increasing LRB damping from 20% to 25% reduced isolator displacement and inter-storey drift, while 30% offered limited additional benefit and higher accelerations. An optimal damping range of 20–25% provided balanced seismic performance.
