Renovation Award of Excellence: Shinjuku Sumitomo Building, Tokyo
Kojun Nishima
President
Sumitomo Realty & Development Co., Ltd., Tokyo
Satoshi Onda
Director
Nikken Sekkei Ltd, Tokyo
Respect the Legacy, Re-Energize the Neighborhood
The Shinjuku Sumitomo Building, completed in 1974, was the first to exceed 200 meters in the Nishishinjuku district of Tokyo. Starting around 20 years later, the surrounding buildings began to replace outmoded equipment, renovate, and upgrade in accordance with updated earthquake-resistance codes. The Sumitomo Building’s owner decided not only to update and upgrade the building, but also to roof over the public space of the site, to enliven the connections between the building and the surrounding neighborhood, as well as inject new energy into the area as a whole.
The long-span structure covering the formerly outdoor plaza was conceived to both reinforce the existing structure, with columns positioned in the plaza and as needed along the tower periphery, while also realizing vast column-free spaces that would be appropriate for various kinds of events. Utilizing the existing framework of the building as much as possible in order to keep costs down, the columns supporting the large roof were placed strategically where they would most effectively reinforce the existing structure, facilitate replacement of existing equipment, and require minimal reinforcement. To assure that the large roof would not affect the difficult-to-reinforce existing structure of the high-rise tower, it is structurally separated by expansion joints placed above ground. Using the maintenance spaces at the three corners of the existing building, a construction method was planned for the vibration-control reinforcement that would not disturb the tenant offices. The plan made it possible to achieve a seismic retrofit without installing cranes or other temporary equipment on the tower exterior.
