Seismic performance of a high-rise base-isolated RC shear wall building on near-fault deep deposit

The 2008 Wenchuan earthquake significantly accelerated the adoption of base isolation in seismic-prone regions in China. While traditionally used for short-period structures on stiff sites, base isolation has also been increasingly applied to high-rises on soft soils. However, most current designs still rely on conventional methods used in the past. This paper investigates the seismic performance of a 26-story base-isolated shear wall building constructed on a near-fault site of deep alluvial deposits near Beijing. A numerical model incorporating soil-structure interaction (SSI) is developed to evaluate the combined effects of seismic isolation and deep site conditions on structural responses. The results indicate that base isolation effectively reduces the lateral force demands of the superstructure, even in the presence of deep soils. However, the soft site tends to amplify the horizontal and rotational deformations of the isolation layer, increasing the risk of isolator failure during major earthquake events. Meanwhile, the routine design method tends to underestimates these responses. These findings highlight the necessity of considering both SSI effects and a more refined assessment of soil nonlinearity in amplifying seismic motions in the design of high-rise base-isolated buildings on soft soil.