The Application of Base Isolation System as Earthquake Resisting Technology on Mulya Medika Hospital, Samarinda

Indonesia lies within the Pacific Ring of Fire and is therefore prone to seismic activity. Consequently, it is important to adopt structural designs capable of resisting earthquake loads. This study evaluates high-damping rubber bearings (HDRBs) designed per SNI 1726:2019 (Chapter 12) by comparing a base-isolated design with the existing fixed-base configuration of the Mulya Medika Hospital, Samarinda. Nonlinear pushover analyses were performed in ETABS 2022 to obtain base shear, global displacement, interstory drift, P–Δ stability, and performance level. The fixed-base model produced a base shear of 4902,41 kN, while the base-isolated model produced 3753,87 kN, an absolute reduction of 23,4%. Maximum roof displacement in Y direction increased from 28,70 mm (fixed) to 42,04 mm (isolated), whereas maximum interstory drift in Y direction decreased from 27,76 mm to 10,29 mm, indicating that isolators concentrate deformation at the base while reducing relative deformation of the superstructure. Computed P–Δ stability coefficients remain below allowable limits for both models (0,0435 fixed; 0,0863 isolated), confirming negligible second-order instability. Overall, HDRBs reduce seismic demand on the superstructure and improve the structure’s performance toward Immediate Occupancy (IO).