Applying Seismic Isolation to Buildings in Japan — Retrofitting and Middle-Story Isolation

Since the Kobe earthquake in 1995, Japan has constructed a number of seismically isolated buildings based on codes and governmental appraisals. NIKKEN, a Japanese architectural and engineering firm, has designed more than 130 buildings using various seismic isolation methods, including base isolation, middle-story isolation, and retrofitting. Some projects involved improving the seismic safety of historic buildings by retrofitting them with base isolation systems while preserving the buildings' original designs. Other projects involved incorporating middle-story isolation systems into high-rise vertically multifunction buildings. This paper describes the practical designs of these examples as well as the details of their systems.