Research on Base Isolation for Seismic Retrofitting of Adjacent Structures Connected with a Large Floor

Seismic isolation has been proven to be an efficient approach to seismic retrofitting of structures based on the concept of reducing the seismic forces by lengthening the structural fundamental vibration period. However, superstructures may collide with each other under seismic excitation as the top displacement increases in the case of base-isolated adjacent structures. The relative displacement of top floors of superstructures is decreased more effectively by connecting the isolation layer of adjacent structures with a large floor, compared with the method to increase the width of seismic joint by using building monolithic movement technology. A specific engineering of base isolation for retrofitting of existing adjacent frame structures is studied in this paper.

Seismic response was evaluated for the structures in different cases by time-history analysis. Parametric studies are performed in order to achieve the laws of top displacement difference of superstructures influenced by the change of dynamic characteristic of towers in the case of base-isolated multi-tower structure with a large floor.

The results of extensive numerical analysis verify the effectiveness of isolation with a large floor in minimizing the forces from earthquake and protecting the top story from crashing into each other, which has important reference value for application of retrofitting with isolation technology on adjacent reinforced concreted frames.