A Model for Fire Fighting Activities of Community Residents Considering Physical Impacts of Fire Suppression of Water Application Keisuke HIMOTO*, Kenji IKUYO**, Yasuo AKIMOTO***, Akihiko HOKUGO****, Takeyoshi TANAKA***** *Graduate School of Engineering, The University of Tokyo, 113-8656 Tokyo, Japan ** Housing Administration, Osaka City Government, 530-8201 Osaka, Japan *** Graduate School of Science and Technology, Kobe University, 657-8501 Kobe, Japan **** Research Center for Urban Safety and Security, Kobe University, 657-8501Kobe, Japan ***** Disaster Prevention Research Institute, Kyoto University, 611-0011 Kyoto, Japan Abstract A physics-based urban fire spread model formerly developed by the authors was refined by considering fire fighting activities of community residents. The model is based upon the zone concept in which properties of gas inside compartment, component of buildings in urban area, is assumed as uniform. Mitigation of fire hazard due to water application is evaluated by incorporating following consequences of water evaporation into the conservation equations of compartment gas : (A) cooling of compartment gas ; (B) dilution of compartment gas ; (C) cooling and wetting of fuel surface. Initiation time of water application, which is a predominant factor of success and failure of fire suppression, is evaluated as a sum of detection time of fire, assembling time of residents, and preparation time for equipment use. The proposed model was applied to simulate fire spread behaviors in a hypothetical urban area where 121 buildings of identical configuration were aligned in a regular pattern. Case studies were carried out in order to investigate effects of anticipated critical parameters such as fire detection time, and number of water supply port.
Fig. 1 Energy conservation relation in a water discharged fire compartment. Fig. 1
Fig. 2
Fig. 2 Time rate change of burning area of combustibles in relationship to water application. Fig. 3 Fig. 3 Restriction of target buildings of fire fighting activity due to circumference conditions.
Fig. 3 Fig. 4 Fig.4 Initiation and duration of fire fighting activities.
Fig. 5 Configuration of the compartment and water application condition. Fig. 5 Fig. 5 Figs. 6, 7, 8 Fig. 6 Fig. 7
Fig. 6 Predicted compartment fire behaviors in case (A). Fig. 8 Fig. 7 Fig. 7 Predicted compartment fire behaviors in case (B). Fig. 8 Predicted compartment fire behaviors in case (C). Fig. 9 Table 1 Table 2 Table 1 Parameters used in the calculation
６ ０ Table 2 Calculation conditions for urban fire Fig. 9 Alignment of buildings in the hypothetical urban area and locations of water supply ports. 消防水利 W1 W2 W3 W4 の位置は Fig. 9 に示 す通りであり いずれも出火建物から等距離にあるも のとした また比較のため 消火活動が行われない場 合 条件 X についても計算を行った ５ ２ 計算結果および考察 条件 X A5 C5 につい て 火 災 が 拡 大 し ていく様子を出火後４ ０分が経過した時点から４ ０分ごと に描いたものを Fig. 10 に示す ただし 燃焼中の建 Fig. 10 Fire spread behaviors in the hypothetical urban area. １ ６
Fig. 11 Fig. 12 Fig. 11 Time transition of burnt or burning buildings. Fig. 12 Relationship between detection time and number of burnt or burning buildings.