火焰厚度对钢筋混凝土柱耐火性能的影响

Effects of flame thickness on the fire resistance of concrete component

为正确评估火焰厚度对钢筋混凝土构件耐火性能的影响,以矩形截面四面受火柱为研究对象,以标准火为受火条件,采用数值分析方法研究构件表面和试验炉壁面温度,分析火焰厚度对构件耐火性能的影响。结果表明:炉壁温度略低于构件表面温度,不会向构件辐射传热;火焰厚度越大,构件温度越高,承载力越小,对硅骨料混凝土该现象尤为明显;因标准耐火试验炉炉腔尺寸较小,其试验结果可能过高地估计了构件的抗火能力,建议在耐火设计与评估中考虑实际火焰厚度对结构的影响。

In order to evaluate the effects of flame thickness on the fire resistance of reinforced concrete component correctly,rectangular column exposed to standard fire on four sides is studied by numerical analysis method so as to reveal the temperature of component surface and furnace wall and the effects of flame thickness on the fire resistance of component.The results indicate that the surface temperature of furnace wall is lower than that of component,and the radiation heat will not be transferred from the furnace wall to the component surface;the bigger the flame thickness is,the higher the temperature and the lower the bearing capacity of component is,especially for the silicon aggregate concrete.Because the size of furnace in standard fire test is small,the test result may over evaluate the fire resistance capability of components.The suggestion is that the actual flame thickness should be considered in the design and evaluation of fire resistance.