<p>This study introduces a methodology for monitoring the seismic performance of base-isolated buildings by investigating the influence of varying maximum isolator displacement from 100&#xa0;mm to 600&#xa0;mm on the nonlinear response of the base-isolated building under near-field earthquake ground motions. This research study explores the dynamic variation of maximum isolator displacement (D_max) and its effect on key seismic performance indicators. For this purpose, a 5-storey reinforced concrete building frame is selected with lead rubber bearing as an isolation system. The non-linear time history analysis is carried out to evaluate its impact on the overall response of the base isolator. The results revealed a decreasing energy dissipation as the isolator displacement increased. The base shear is decreased by 51.3%, storey displacement reduced by 68.7%, interstorey drift ratio is reduced by 55%, storey acceleration reduced by 68%, and plastic hinge rotation reduced by 77.71% in a base-isolated (BI) building as compared to a fixed base. Moreover, the results highlight the existence of isolator displacement beyond which the response becomes saturated and adds less benefit. The insights gained provide valuable guidance for performance-based design of lead rubber bearing systems, offering a critical step toward advancing the safety, cost-effectiveness, and seismic resilience of base-isolated buildings globally.</p>