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弾性すべり支承耐火被覆工法の耐火性能

馬場 重彰*1・道越 真太郎*1・藤野 宏道*2

免震装置を建物の中間階に設置する場合,耐火構造の柱として耐火性能を担保する必要がある。積層ゴム支承,LRB支承,高減衰ゴム支承等の免震装置では,耐火構造の大臣認定を取得した耐火被覆工法が商品化されている。しかし,弾性すべり支承に関しては大臣認定品が存在しない。
そこで,弾性すべり支承耐火被覆工法の2時間の加熱実験および有限要素法による温度解析を実施した。その結果,積層ゴム表面およびすべり材表面の最高温度は約120℃および約100℃であり,性能担保温度(150℃)以下であるため,弾性すべり支承の荷重支持能力は確保できると考えられる。また,有限要素法による熱伝導解析を実施した結果,各構成材料の熱特性および空気層内の輻射を考慮することで実験結果を概ね表現できていた。なお,本工法は,2時間耐火の国土交通大臣の認定を取得した。

キーワード:  弾性すべり支承,積層ゴム,耐火被覆,有限要素解析,耐火性能

*1 技術センター 建築技術研究所 防災研究室
*2 設計本部 構造設計第一部

Fire Resistance of Fire Proof System for Elastic Slide Bearing

Shigeaki BABA*1, Shintaro MICHIKOSHI*1 and Hiromichi FUJINO*2

When installing a seismic isolator device in a building, the device must satisfy fireproof requirements as a fireproof construction column under the Building Standard Law. Seismic devices, such as laminated rubber bearing, lead rubber bearing and high damping rubber bearing, have fireproof systems authorized by the minister. However, there is no authorized fireproof system for elastic slide bearing. Therefore, heating experiments for 2 hours of the fireproof system using elastic slide bearing and temperature analysis by the finite element method were carried out.
As an experimental result, the highest temperatures of the laminated rubber and the slide material surface were about 120 ℃ and about 100 ℃, respectively. It was below performance security temperature (150 ℃), so it was thought that the load-bearing capability of the seismic device was sufficient in fire. Moreover, as an analytical result, the experimental results were able to be well expressed by taking account of the radiation and the heat characteristic of each constituent material.
In addition, this fireproof system acquired authorization of the Land, Infrastructure and Transport Minister for 2-hour fire-resistance.

Keywords:  elastic slide bearing, laminated rubber, fire proof, finite element method, fire performance

*1 Disaster Prevention Research Section, Building Research Institute, Technology Center
*2 Structural Engineering Department (I), Design Division