Earthquake Resilience in Low-Rise Concrete Buildings: A Study on the Effectiveness of Base Isolators

Earthquakes pose significant challenges worldwide, causing severe structural damage, loss of life, and socioeconomic disruptions. To mitigate seismic effects, base isolators have emerged as an effective design strategy for reducing structural damage by decoupling buildings from ground motion. This study investigates the seismic performance of a low-rise concrete building equipped with base isolators, focusing on the influence of isolator mass, stiffness, and damping ratio on key structural responses, including the base shear, natural period, and inelastic storey drift. A symmetric three-storey building was analysed using linear time-history analysis. The ground motions were scaled according to the Indonesian Seismic Code (SNI 1726:2019) to reflect local seismic hazards. Base isolators were modelled as joint springs, and variations in mass (15, 30, and 45 kN), stiffness (1500, 3000, and 4500 kN/m), and damping ratios (20%, 30%, and 40%) were systematically evaluated. The results reveal that increasing the stiffness of the base isolators significantly increases the base shear and inelastic storey drift, whereas higher damping ratios effectively reduce both parameters. Variations in the isolator mass have a minimal impact on the structural response. Additionally, the natural period of the building remained constant across different damping ratios, highlighting the dominant role of the mass and stiffness in the period determination. These findings emphasise the importance of optimising isolator properties to balance seismic performance and structural safety. This study provides critical insights into the design of base-isolated buildings and offers a valuable reference for enhancing the resilience and safety of structures in earthquake-prone regions.