著者

横井 鎮男

出版者

Japan Association for Fire Science and Engineering

雑誌

日本火災学会論文集 (ISSN:05460794)

巻号頁・発行日

vol.15, no.2, pp.38-51, 1966 (Released:2013-08-21)

参考文献数

4

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If the fire spreads from one floor to upstairs in a building, both floors will be enveloped in the flame. Suppose that the space of both floors are communicated with stairs opening. The author has had a question whether, in this case, one common neutral layer appears to both floors or neutral layers appear in each floor respectively. After the big fire broke out in Tōkyū Kaikan in Tokyo, 10th April 1965, the author inspected the state after the fire. This fire broke out in the 7th floor and soon it spread to the 8th floor. Judging from the track of the smoke, attached on the wall of the building, the author found out that neutral layers existed in both floors respectively.After that, the author attempted to calculate the positions of the neutral layers with a brief model building expressed in Fig. 1 and Fig. 2. This building has a window in each floor. and both floors are communicated with a stair case, whose horizontal opening area is S.The results of calculation gave the following conclusions :(1) The positions of the neutral layers depend on the position and size of the window, the room temperature, the ratio of the area of the horizontal opening of the stair to that of the floor.(2) As the value of this ratio increases, the position of the upstairs’ neutral layer drops down and that of the downstairs’ rises. If this value of ratio exceeds a certain value, the neutral layer does not exist in upper floor but it looks as if it existed in the lower floor.(3) As the value of this ratio approaches 1, this virtual neutral layer nearly coincides with the neutral layer of the lower floor. In this case, it looks that a common neutral layer exists to both floors.

著者

横井 鎮男

出版者

一般社団法人日本建築学会

雑誌

日本建築學會論文集 (ISSN:03871177)

巻号頁・発行日

no.46, pp.92-96, 1953-03-30

被引用文献数

1

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大火災の火流の性情に関する研究の一環として火先線の風下に於ける平均温度の分布を調べた。基木方針としては藤田金一郎博士の提唱される「市街地の乱れた風によつて熱が拡散されつゝ風下に運ばれる」という考え方に従い、上昇気流がある場合の熱の乱流拡散の方程式を立て、これを近似的に解いて、模型実験の結果と比較した。更に結果の式のパラメーターの数値を仮定して市街地の大火の場合を計算した結果、風下側の地上の温度は平均値としてそれ程高くはならず、延焼の危険はこの平均温度で予熱された後に、火線方向から稍下向の強い風が10数秒継続したときに大きいのではないかと思われる。