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Development of a Long-Period Earthquake Motion Risk Assessment System for Superhigh-Rise and Base-Isolated Buildings

—Assessing the need for countermeasures in 10 minutes—

May 1, 2013Takenaka Corporation

Takenaka Corporation (President: Masahiro Miyashita) has, in response to the tentative proposal concerning countermeasures for long-period earthquake motion announced by the Ministry of Land, Infrastructure, Transport and Tourism, developed TRAIN®-L, a long-period earthquake motion risk assessment system that can screen (abstract) the need for a countermeasure for a building struck by long-period earthquake motion over approximately 10 minutes.

Recently the Ministry of Land, Infrastructure, Transport and Tourism studied legislating countermeasures for long-period earthquake motion for superhigh-rise and base-isolated buildings. When this legislation has been enacted, owners of superhigh-rise and base-isolated buildings will be obligated to predict structural damage for each building by long-period earthquake motion calculated by a method stipulated by the national government, and take countermeasures as necessary. Takenaka Corporation uses TRAIN-L to assess whether or not a building requires countermeasures in only 10 minutes. In a case where a countermeasure has been judged to be necessary, it permits a more detailed diagnosis and the proposal of a countermeasure such as introducing a damper to reduce shaking of the building, so that damage by the long-period earthquake motion will be mitigated, allowing the building to be used without fear.

Takenaka Corporation has created a database of all necessary information concerning superhigh-rise and base-isolated buildings which it has designed and constructed, and it can respond immediately even after the anticipated long-period earthquake motion has been revised. The system can also assess any building including those designed by other companies if it can obtain ground information about the building site and the earthquake motion, etc. used to design the building.

Takenaka Corporation has established a menu of soft to hard responses to long-period earthquake motion, including (1) advance surveying, (2) simple diagnosis, (3) detailed diagnosis, and (4) retrofitting. In the future, Takenaka will continue to give total support to reassure its customers and to prolong the lifetimes of their buildings.

The legislation

At the end of 2010, the Ministry of Land, Infrastructure, Transport and Tourism announced a tentative proposal of a countermeasure for long-period earthquake motion for use in existing superhigh-rise buildings and base-isolated buildings. It conducted further consultations in response to the Great East Japan Earthquake of March 11, 2011. The Building Standard Provision Promotion Project, intended to improve and revise the Building Standard Law and related legislation in 2011 and 2012, was expanded to include a study of Great Earthquakes along the Nankai Trough, and it is predicted that legislation to establish countermeasures to deal with long-period earthquake motion will be provided in the future.

When this legislation has been enacted, building owners will be legally obligated to request a designer to study the response to long-period earthquake motion of superhigh-rise and base-isolated buildings they own, and if necessary, retrofit the buildings.

Outline of TRAIN®-L

Based on the tentative proposal for countermeasures by the Ministry of Land, Infrastructure, Transport and Tourism, the following studies will be performed.

1. Calculation of the long-period earthquake motion in the engineering bedrock of the ground of a building site.
2. Calculation of the long-period earthquake motion of the ground surface considering the effects when earthquake motion is amplified by the surface ground.
3. Comparison of the scale of the earthquake motion adopted for the design with that of the long-period earthquake motion on the ground surface for a cycle at which it is assumed that buildings shake easily.
4. If the long-period earthquake motion is lower than the earthquake motion adopted for the design, the structure body will not be harmed.

TRAIN is a registered trademark of the Takenaka Corporation.