Assessment of Soil-Structure Interaction Effects on Seismic Behavior of Isolator and Mass Damper Equipped Buildings

Abstract

This study examines the impact of Soil-Structure Interaction (SSI) on the response of seismic-isolated buildings. Reinforced concrete office buildings with different heights are studied. The High Damping Rubber Bearing (HDRB), Lead Rubber Bearing (LRB) and Double Sliding Pendulum (DSP) isolators are utilized to isolate the buildings base. Also, Tunned Mass Damper (TMD) is implemented at top of buildings to improve building response. Soft, medium and hard soils are modelled using direct and substructure approaches. On the other hand, the influence of foundation type on buildings response is examined. The results indicate that considering SSI in soft soil reduces base shear of 6-storey building by 30%, but increases top storey displacement from 128 mm to 182 mm. It is found that base isolators are more efficient in reducing base shear (41-66%) than TMD (10-25%). Simple equations are suggested to calculate the fundamental period based on building height. The soil layer near the foundation, around 75% of the building height, primarily determines the building's response. Therefore, soil investigation can be restricted to a maximum depth of 75% of the building height. Finally, it is found that using pile foundation in soft soil alters building response to resemble that in hard soil conditions.