A Comparative Study of Base Isolation and Interlayer Isolation Applied to a Twin Tower Shear-Wall Structure with Enlarged Basement While Considering Various Tower Heights

Abstract

Nowadays, engineers tend to apply seismic isolation technology into certain buildings to control the structural story drift, in order to protect the precision instrument inside or to maintain the integrity of the buildings during rare earthquakes. The application of seismic isolation technology in a Twin tower shear-wall structure with enlarged basement(2TSSLB) located above ground level has been studied by many researchers, but there is still relatively little research on which seismic isolation scheme is better for 2TSSLB when it has different tower heights, this forms a research gap. The main purpose of this article is to compare the story drift of this 2TSSLB using base isolation and interlayer isolation schemes under three various heights of towers. There are nine models in this study, which represent 14-story, 11-story and 8-story non-isolated structures, base isolated structures and interlayer isolated structures. In this study, ETABS was used for modelling, and those models were analyzed by the combination of response spectrum method and time history analysis method. Finally, on the premise of meeting the standard requirements, the story drifts of each model obtained under αmax (maximum horizontal seismic influence coefficient) =0.45 was compared. It is found that the story drift of these 2TSSLB with various heights has decreased significantly after using the isolation technology. Furthermore, the story drift of 2TSSLB using the interlayer isolation scheme with the isolation layer set on the top of the enlarged basement located above the ground level is lower than that of 2TSSLB using the base isolation scheme. The average story drift of the interlayer isolated structure is 18.5% lower than that of base isolated structure when this 2TSSLB consists of 14-story towers, this number becomes 30.7% when this 2TSSLB contains 11-story towers, and it increases to 31.9% when this 2TSSLB has 8-story towers. This implies that for the 2TSSLB structure, the structure adopting the interlayer isolation scheme has more safety redundancy than the structure adopting the base isolation scheme even if the tower heights changes.