考虑火焰辐射的大空间建筑火灾中钢构件升温实用计算方法

对基于集总热容法建立的钢构件热平衡方程进行了参数分析，发现在火焰辐射下对钢构件升温有影响的参数有：大空间建筑火灾中烟气的升温历程和烟气最高升温、火焰面与其正上方钢构件表面微元间的角系数、受火焰辐射钢构件有效表面积系数以及钢构件的形状系数。建立了包含这些影响参数的火焰辐射下钢构件升温典型曲线的数学表达式，通过对精确结果进行拟合，得出了火焰辐射下钢构件升温计算式的待定系数，从而得出大空间建筑火灾中火焰辐射下钢构件升温的实用计算式，该实用计算式避免了直接利用钢构件热平衡方程计算火焰辐射下钢构件升温的繁琐，同时与精确计算的结果吻合程度较好，便于工程技术人员在大空间建筑钢结构抗火设计中应用。

Practical Calculation Method for Temperature Elevation of Steel Members on Flame Radiation in Large Space Building Fire

Based on parameter analysis on the heat equilibrium equation of lumped differential formulation, the parameters for influencing the temperature elevation of steel members under flame radiation were gained as follows： the time history of temperature of steel members, the temperature of smoke in large space building fire, the configuration factor for heat radiation from flame to steel members, the effective surface area coefficient of steel members for flame radiation and the shape and size of steel member. A direct expression involving the above factors for calculating temperature of steel members caused by flame radiation in large space building fire was proposed by cure-fitting strategy on the base of exact solution to the heat equilibrium equation for the temperature and the undetermined constants of the expression were determined. This expression is simple and can be conveniently used for fire-resistance design of steel structures for large space buildings.