- 學位論文
設有天井的建築物火災垂直延燒及排煙性能影響參數之研究
The influence of parameters on the vertical spread of fire and the exhaust of smoke in buildings with patios
摘要
建築物天井功能為採光與通風，但在火災發生時天井可能成為排煙豎井，此時天井於煙囪效應下，熱煙往上竄，可能會流入接連空間，造成垂直延燒之虞。然而過去建築安全相關法規對天井之防火安全並未規範，如設計不當或欠缺安全管理，火災發生時可能造成人員嚴重傷亡與財物損失。此類火災傷害案例如2008年5月25日新北市xx華城社區3樓之火災，熱煙經由天井往上排出造成垂直延燒，為典型煙囪效應火場危害高樓安全，造成10樓3人死亡，但火場3樓僅有2人試圖滅火受傷。 本案經過火災後現場實地勘察及了解案場狀況，建立案場之電腦模型涵蓋各空間佈置情形，後進行火場電腦模型成功重建火災過程，研究發現天井內延伸物為垂直延燒之主因，並提出未來減少火災傷害之設計與管理要點。本研究電腦模擬結果與火場鑑定報告相當接近，也凸顯出天井之防火安全管理之重要性。本案例研究成果也呈現初始火場在煙囪效應中性面之下或之上為不同之火場劇本，進一步以天井煙囪效應進行相關主題研究。 本研究建築模型參考以上案例，電腦模型考量鄰近天井公寓內之傢俱與佈置，包含和式房間、主臥房、客廳及廚房等等相關隔間，內部主要可燃材料如沙發、床墊傢俱等，其他可燃物假設為裝潢材料，桌椅及和室設為雲杉類木材。初始起火點為居室放置之易燃物品，研究發現，造成火場水平延燒有效熱釋放率約為1.0MW，低熱釋放率未造成延燒現象。公寓水平延燒時面臨天井窗戶未關閉或模擬溫度達200℃窗戶玻璃燒毀，熱煙流入天井以煙囪效應經由天井排放至大氣中，本研究發現其它樓層受到煙燻，但無垂直延燒災情並無擴大。本研究同時發現若天井內有易燃延伸物，煙流受到天井內延伸物之影響造成蓄壓蓄熱、易有高溫燃氣進入上方樓層公寓造成跨樓層延燒效應。 煙囪效應中性面以下樓層發生火災時，經研究結果顯示，天井內有延伸物材料為易燃物時，煙流受到天井內延伸物之影響產生蓄壓、燃燒加上煙囪效應，造成其他樓層延燒機率高且嚴重；跳樓層設置不燃材料延伸物，因蓄壓及煙囪效應亦會發生其他樓層延燒現象，但情況較為輕微。但當火警發生時所有面向天井窗戶關閉，延伸物材料為易燃物且長度達1.0m及0.5m，易產生火災跨樓層延燒問題，如火災熱釋放時間較長，稍延後仍會造成延燒現象，其他長度較小延伸物，並未造成跨樓層延燒現象。 中性面以上樓層發生火災時，經研究結果顯示，天井內設置延伸物為易燃物長度達1.0m時，火災時將造成跨樓層延燒現象，受害僅為火場上方的樓層。雖其火災危害不若中性面以下樓層嚴重，但仍不容輕忽。本研究之成果可供一般10樓以下天井式建築物防火安全管理、設計及既有建築改善參考。
並列摘要
Patios in buildings function as natural lighting and ventilation, but may be as smoke shafts in case of fire. In case of a fire due to the stack effect of the patio, fire may spread vertically to the rooms adjacent to the patio. However fire safety of patios has rarely been specified in the building codes. In case of a fire serious injury and loss could be caused by the fire spread via the patio. Such a case was the fire in the xx Building in Taiwan on May 25th in 2008 that caused 3 deaths on the tenth floor. The initial fire site however was on the third floor and ironically only two persons injured trying to put out the fire. The above building fire was reconstructed using computer modeling. The building plan and the actual fire scenario were built into the computer model. Results of site investigation were also considered in the study of the above fire case. The computer modeling found that the main reason of vertical spread of fire was due to the extended objects in the patio. The computer reconstruction of the fire was found to be close to the official report of the fire case, and also the site investigation. The computer model used in this study considered the combustible materials, such as sofa, mattress, furniture, decoration materials, tables and chairs, etc. The actual setting of the rooms in the apartments such as bedrooms, living room and kitchen was also built into the computer model. The origin of fire was flammable items placed in the bedroom. The computer model shows that effective heat-release rate above 1.0MW would cause horizontal fire spread in the room. This study also found that the spread of fire in the room would increase the fire size rapidly. The windows facing the patio were set to be broken at 200℃, and then the thermal plume would flow into the patio the smoke effect. It was found that with a clear patio smoke may get into other floors that have windows open but no vertical fire spread. It was found in the simulation that with any extended objects in the patio, the hot smoke would cause fire to the upper floors and further increase the total fire size. The stack effects were investigated further. In case of fire on the floors below the neutral plane with extended objects in the patios, the fire would spread across floors due to the heat accumulation at the obstruction. The extended objects being combustible or not would have the results. However it was found that when the windows facing the patio were closed and the extended objects were in combustible, fire spread could be slowed significantly. In case of fire on the floors above the neutral plane with extended flammable objects of 1m or 0.5m located in the patio, fire would spread to the upper floors. In comparison the fire spread was less serious than that in the case of fire on the floors below the neutral plane. The results of this study would be useful to the building managers and designers, in case of buildings with patio and less than ten stories.