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Failsafe System for Seismically Isolated Buildings, Seismic Isolation Fender

Obayashi Develops Failsafe System for Seismically Isolated Buildings; Seismic Isolation Fender® Now in Use in Actual Buildings

Seismic Isolation Fender® Reduces Collision Impact in Seismically Isolated Buildings and Improves Building Safety in Larger than Anticipated Earthquakes

In cooperation with Sumitomo Rubber Industries Ltd. (https://www.srigroup.co.jp/english/index.html), Obayashi Corporation has developed Seismic Isolation Fender, a shock absorber that reduces the risk associated with seismically isolated buildings colliding with seismic retaining walls in large earthquakes with ground shaking that is greater than the level specified by the Building Standards Act and other regulations.
Seismically isolated buildings are designed to sway slowly and significantly during an earthquake. Therefore, there is an appropriate clearance provided between the building and the retaining walls on the ground. In an event of an earthquake defined by the Building Standards Act and other regulations, these structures are designed to sway horizontally within the clearance so that they do not collide with the retaining walls.
However, in an earthquake that is larger than anticipated, the building may collide with retaining walls on the ground. The impact could cause the building to shake significantly, and it could threaten the safety of the occupants and damage the building.

How Seismic Isolation Fender is installed

Mid-story isolation systems, which are not accompanied by retaining walls, sometimes have stoppers to prevent an excessive displacement of the seismic isolator. The same problems could occur if the building collides with the stoppers in an event of a larger than anticipated earthquake.

Example of how Seismic Isolation Fender is installed

Seismic Isolation Fender, which was recently developed, is a shock absorber that is placed between a building and the retaining walls (or stoppers). The shock absorber, made of high-damping rubber, absorbs collision energy through plastic deformation and lessens the impact, thus improving the safety of the building and occupants in larger than anticipated earthquakes. In addition, Seismic Isolation Fender is very inexpensive because it is a simple device consisting of a high-damping rubber block and a metal plate for installation.
The device is intended for new construction of seismically isolated buildings, since it is necessary to consider the width of the device when creating the clearance that is typically required for seismically isolated buildings. However, it can also be used in existing seismically isolated buildings if it suits the existing clearance and site conditions.
Seismic Isolation Fender is already used in the base isolation system of Obayashi Corporation West Japan Robotics Center BCP Office (Hirakata City, Osaka) and Disco Corporation Kyushu Office (Mashiki-machi, Kamimashiki-gun, Kumamoto Prefecture). For mid-story isolation systems, it is used in Park Tower Asuto Nagamachi (Sendai, Miyagi Prefecture), Hiroshima Gas Disaster Prevention Center Building (Hiroshima, Hiroshima Prefecture), Nippon Life Insurance Company Nihonbashi Building (Chuo-ku, Tokyo), and KABUTO ONE (Chuo-ku, Tokyo). With these properties, the device is designed to reduce collision impact to one-half to two-thirds in a large earthquake that produces one and a half to two times the ground shaking which is defined in the Building Standards Act (the occurrence of such earthquake is extremely rare).
To improve the safety of buildings and occupants even more, Obayashi plans to actively market Seismic Isolation Fender as a failsafe system for seismically isolated buildings against unexpectedly large earthquakes.

Collision impact with and without Seismic Isolation Fender
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