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“Multifunctional Oil Damper”(Multipurpose) System Developed –Able to Correct Base Isolation Layer Movement After an Earthquake

—Used for first time in Mita Bellju Building—

May 10, 2012Takenaka Corporation

Takenaka Corporation (President: Toichi Takenaka) and Kayaba System Machinery Co., Ltd. (President: Hidekatsu Ishii) have jointly developed a “Multi-Functional Oil Damper System with Jack Function※,” which has the following three functions: 1. a “damping”function, to reduce shaking during an earthquake; 2. a “rock” function, to resist wind force; and 3. a “jack” function, to put back any residual deformation of the base isolation layer (any movement from the original position of the building) after an earthquake. This new system has been used for the first time in the “Mita Bellju Building New Work Project” (in Shiba, Minato-ku), which is expected to be completed on May 31. (The companies have made a joint application to patent this system.)

※Improvements have been made to the multifunction damper developed in 2001, and the oil damper and hydraulic pressure unit have been separated.

Following the Great East Japan Earthquake, the “Field Survey and Research on The 2011 off the Pacific coast of Tohoku Earthquake,” published by the National Institute for Land and Infrastructure Management (an agency of the Ministry of Land, Infrastructure, Transport and Tourism) and the Building Research Institute in March 2012, reconfirmed the earthquake-resistance safety of base isolation buildings, but also announced that residual deformation could be seen in some base isolation layers.

In general, base isolation layers in base isolation buildings are designed so that temporary jacks can be installed if required to correct any residual deformation. However, in the case of buildings which have an isolation layer in an intermediate floor and have an elevator shaft going through the building, even slight residual deformation can cause problems with the elevator operation. In this case there is a need for immediate correction, but bringing in a temporary jack and carrying out the correction work takes a long time.

The base isolation layer in the “Mita Bellju Building” is constructed under the 25th floor (114 meters above ground), so by using this new technology, corrections to any residual deformation can be quickly and easily corrected without bringing in a temporary jack. The performance of the jack function has been confirmed at the site.

This new system can be applied to buildings which have a base isolation layer in an intermediate floor, and it can also be applied to buildings that have a base isolation layer in the foundation. The company hopes to develop use of this system in the future.

Features

1) Three functions in the one system: “damping,”“rock” and “jack” functions

This new system has the three “damping,”“rock” and “jack” functions, which can be selected as required using buttons. If there is any residual deformation of the base isolation layer after an earthquake, by pushing a button and selecting the “jack” function, the base isolation layer can be put back to the correct position without using a temporary jack.

2) Quick corrections can be made to residual deformation of the base isolation layer

Because there is no need to bring in and set up a temporary jack as was required with systems up to now, corrections to residual deformation can be carried out quickly.

Outline

This system is composed of an oil damper for the damping function during an earthquake and the rocking function during strong winds, a hydraulic pressure unit and detachable hydraulic pressure hoses to connect the parts together. When this system is used as a jack, the oil damper is connected to the hydraulic pressure unit with the hydraulic pressure hoses, and the oil damper changes to the rock mode. The jacking operation is carried out using levers inside the hydraulic pressure unit box. The number of oil dampers and hydraulic pressure units is determined by the features of the base isolation devices forming the base isolation layer.

Composition of the oil damper with jack function