1:4缩尺厂房中功率火灾试验研究

Medium Power Fire Test Study on a 1:4 Scaled Portal Frame Building

为研究局部火灾作用下大空间建筑内火源、热烟气以及室内空间和钢构件温度场的发展及分布规律,设计建造了一个缩尺比为1∶4的门式刚架厂房模型,在模型内开展相当于中功率火灾的小规模火灾试验.试验过程中测量了模型内部各关键位置的热空气和钢构件温度,并采用《建筑钢结构防火技术规范》(GB51249-2017)给出的钢构件温度场计算公式对试验中构件升降温进行计算对比.结果表明:热空气温度峰值从火源正上方向四周逐渐减小,沿跨度方向两侧温度分布基本对称.局部火灾下建筑内部空间明显可分为热烟气层高温区、次高温区和热烟气层以下区域.钢构件温度沿截面方向分布较均匀,其温度变化明显滞后于热空气.对于处在热烟气层以下的钢构件,其温度场计算需要额外考虑火焰的直接辐射作用.

To investigate the fire development,smoke movement,and temperature development within the whole building and steel members,a 1 ∶ 4 scaled portal frame building was designed and built for a medium fire test. The temperatures of the hot gas and steel members were measured in the test. The formulation recommended by 《Code for fire safety of steel structure in buildings》(GB51249-2017) was used to predict the temperature-time curves of steel members. The test results indicate that the maximum temperature of hot smoke decreases from the fire origin to the surrounding zone and distributes symmetrically on either side of the roof ridge. In the case of localized fire,the space in the building can be divided into high temperature zone of hot smoke layer,sub-high temperature zone and zone below the hot smoke layer. The temperature distributions within the steel sections are approximately uniform. The tem-perature variation of steel members lags behind that of the surrounding hot gas during the growth and decline stage.Meanwhile,the effect of flame radiation on the temperature elevation of steel members under the hot smoke zone needs to be considered in addition.