Seismic isolation retrofit of existing two buildings was completed first in Japan at the end of April 1997. Isolation works were done at mid-story in one building, and at the base in another building. These buildings were originally built in 1964 and have been used as the training-center of Taisei corporation. Seismic diagnosis revealed the poor seismic resistance capacity of both buildings. Seismic isolation retrofit was chosen as the best counter measure compared to scrap/build and conventional strengthening from the view point of budget, work time and unspoiled usage of buildings even under construction. The planning and work procedure are described.
