建筑大空间火灾模拟及升温计算简单公式

Simple formulae for calculating the gas temperature in large enclosure fire environment

钢结构经常用于建筑大空间环境。因为使用和功能要求,建筑大空间内通常无法设置防火墙来阻止火灾的水平传播,而是通过设置燃烧岛、防火舱及防火隔离带等措施将可燃物限制在一定区域内。大空间内可能的火灾为区域火灾。给出了模拟大空间火灾的理论模型和升温计算简单公式。公式基于火羽流相关理论,并引入工程相关常数得到。通过工况分析,考察了两种不同火灾场景,公式的计算结果与场模拟软件FDS结果进行了比较,二者符合良好。所给出的公式形式简单,式中参数的物理意义明确,推荐用于实际工程计算。

Steel structures are widely used in large enclosure. Limited by its performance and functions, a large enclosure is usu- ally not permitted to be departed by fire walls for preventing horizontal {ire spread. Instead, fire loads in the large enclosure are controlled in a special area by using the concept of island, cabin or isolation space in performane^based fire safety design. As a result, the potential fires in the large enclosure are characterized as localized fires. This paper proposes simple formulae for cal- culating the gas temperature in large enclosure. The formulae are based on the classic plume theory with adopting the common- ly used constants in engineering. Case studies for two different fire scenarios are conducted. The calculated results agree well with those by the simulation results using the software of FDS. With a simple form, the proposed formulae are recommended for practical usages.