Seismic Performance of Base-Isolated Buildings with Vertically Staggered Foundations on Hilly Terrain under Near- and Far-Field Earthquakes

Abstract

Rapid urbanization and limited land availability have encouraged construction on sloping terrains, where framed structures remain highly vulnerable to seismic damage. Base isolation provides a proven means of enhancing resilience. This study investigates staggered buildings equipped with isolation systems, specifically lead rubber bearings, under near-field and far-field earthquakes using ETABS models of isolated and non-isolated irregular structures. Results for regular buildings were validated against existing solutions. Slope angles between 0° and 45° were analyzed to assess seismic parameters including vibration period, base shear, storey displacement, drift, and overturning moment. Findings show that near-field earthquakes intensify slope effects, amplifying base shear, displacement, drift, and overturning moment, while far-field motions exhibit lower sensitivity. Base isolation consistently reduced force-based responses across slope angles, though displacement amplification was most pronounced in steep-slope buildings under near-field motions. Overall, base isolation demonstrates strong potential to improve seismic safety and resilience of staggered buildings in hilly terrains.