大空间火灾中屋盖倾角对温度分布的影响
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摘要
针对平滑无障碍的大空间斜屋盖,基于斜屋盖顶棚射流温度计算模型,分析倾角对屋盖温度分布的影响,给出了10°～30°斜屋盖温度分布近似计算公式。将近似计算公式与FDS模拟结果进行对比,验证其有效性,并结合案例分析水平屋盖温度分布公式用于斜网架时对其应力和位移的影响。结果表明:在距羽流作用中心4.7倍特征半径内或钢屋盖倾角不超过10°时,可忽略屋盖倾角对火灾温度分布的影响;屋盖倾角会导致火源投影点下侧屋盖温度降低,上侧屋盖温度增大,钢屋盖温度最大增幅在7%左右。斜屋盖温度近似计算公式在火源投影点上侧与模拟结果一致性较好,而在下侧则高于模拟结果。采用水平屋盖温度分布计算斜网架温度对其应力和位移影响不大。
Aiming at large spatial inclined roof which is smooth and barrier-free, based on the calculation model of jet temperature for inclined roof, the temperature distribution effected by inclination angle was analyzed. An approximate calculation method was proposed for inclined roof with angles ranging from 10°to 30°. The accuracy of calculation formula was validated by the simulation result of FDS. The stress and displacement of inclined truss influenced by inclination angle were analyzed when the temperature distribution formula was used to inclined truss with an example. The results showed that the influence of inclined roof on the temperature distribution can be neglected when the radial distance is within 4.7 times the characteristic radius or the angle of steel roof does not exceed 10°.The temperature of inclined roof decreases on the underside of projection and increases by 7% on the upside of projection.The result of approximate calculation method is consistent with the results of simulation on the upside of projection but higher on the underside of projection, and the stress and displacement of inclined truss has not change much when the temperature distribution of flat roof was used to inclined truss.
Aiming at large spatial inclined roof which is smooth and barrier-free, based on the calculation model of jet temperature for inclined roof, the temperature distribution effected by inclination angle was analyzed. An approximate calculation method was proposed for inclined roof with angles ranging from 10°to 30°. The accuracy of calculation formula was validated by the simulation result of FDS. The stress and displacement of inclined truss influenced by inclination angle were analyzed when the temperature distribution formula was used to inclined truss with an example. The results showed that the influence of inclined roof on the temperature distribution can be neglected when the radial distance is within 4.7 times the characteristic radius or the angle of steel roof does not exceed 10°.The temperature of inclined roof decreases on the underside of projection and increases by 7% on the upside of projection.The result of approximate calculation method is consistent with the results of simulation on the upside of projection but higher on the underside of projection, and the stress and displacement of inclined truss has not change much when the temperature distribution of flat roof was used to inclined truss.
引文
[1]李国强,韩林海,楼国彪.钢结构及钢-混凝土组合结构抗火设计[M].北京:中国建筑工业出版社,2006.
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[4]倪建生,杜咏,谢超.大空间建筑火灾火源位置对温度场的影响[J].消防科学与技术,2014,33(5):477-480.
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[7]薛素铎,梁劲,李雄彦.大空间建筑火灾空气升温经验公式[J].北京工业大学学报,2013,39(2):203-207.
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[11] GB 50009-2012,建筑结构荷载规范[S].
[12]毕明.性能化设计理念在大空间房中房建筑中的应用[J].武警学院学报,2013,29(8):42-43.
[13] DGJ 08-88-2006,建筑防排烟技术规程[S].
[14] GB51247-2017,建筑钢结构防火技术规范[S].
[15]刘军,刘敏,智会强. FDS火灾模拟基本理论探析与应用技巧[J].安全,2006,27(1):6-9.
[2]李国强,杜咏.大空间建筑顶部火灾空气升温的参数分析[J].消防科学与技术,2005,24(1):19-22.
[3]李国强,杜咏.实用大空间建筑火灾空气升温经验公式[J].消防科学与技术,2005,24(3):283-287.
[4]倪建生,杜咏,谢超.大空间建筑火灾火源位置对温度场的影响[J].消防科学与技术,2014,33(5):477-480.
[5]白音,杨海勇,石永久,等.大空间结构各种火灾场景下的温度场分布[J].清华大学学报,2011,51(8):1122-1127.
[6]田德海.不同羽流模型下网架结构的抗火分析[D].昆明:昆明理工大学,2016.
[7]薛素铎,梁劲,李雄彦.大空间建筑火灾空气升温经验公式[J].北京工业大学学报,2013,39(2):203-207.
[8] CECS 200:2006,建筑钢结构防火技术规范[S].
[9] ALPERT R L. Calculation of response time of ceiling-mounted fire detectors[J]. Fire Technology,1972,8(3):181-195.
[10]张超,李国强.建筑大空间火灾模拟及升温计算简单公式[J].火灾科学,2012,21(2):84-91.
[11] GB 50009-2012,建筑结构荷载规范[S].
[12]毕明.性能化设计理念在大空间房中房建筑中的应用[J].武警学院学报,2013,29(8):42-43.
[13] DGJ 08-88-2006,建筑防排烟技术规程[S].
[14] GB51247-2017,建筑钢结构防火技术规范[S].
[15]刘军,刘敏,智会强. FDS火灾模拟基本理论探析与应用技巧[J].安全,2006,27(1):6-9.