大空间钢结构抗火性能的简化计算方法

Simplified model for fire behavior in large space steel structures

温度场计算是大空间钢结构抗火性能计算的重要环节,已有的计算方法较为复杂。该文提出了火灾升温阶段不同位置构件温度的比例关系与其相应位置空气温度的比例关系相同的假设,并将这一假设推广至降温阶段,实现了火灾升温和降温阶段结构温度场的简化计算。一个平面网架结构的抗火性能计算表明:简化方法与精确方法的计算结果符合良好,可用于大空间钢结构抗火性能计算。

The temperature distribution is a key to analyzing fire behavior in large space steel structures.However,most available calculational methods are rather complicated and not suitable for design analyses.This paper presents a simplified method based on the assumption that the temperature ratios in the structure components are the same as the air temperature ratios at the same locations during the fire temperature increase phase.The assumption is also extended to the cooling phase to develop the simplified calculational method for the temperature field in the structure during the temperature increase and cooling phases.Numerical simulations for a lattice grid structure using the simplified method agree well with predictions using the conventional precise approach.Thus,this simplified method can be used to predict the fire behavior in large space steel structures during the design phase.