热-力耦合作用对建筑结构火灾安全的影响

结构火灾安全可以避免建筑物在火灾中坍塌.火灾热环境影响建筑结构的响应,传统的标准火灾环境有一定的局限性,不能完全适用于若干真实火灾场景.因此有必要开展真实火灾环境下建筑结构的热-力响应特性研究,发展有效的工程工具来设计经济安全的结构.近来,性能化的结构火灾安全设计评估方法和相应技术发展迅速,该文给出一种综合考虑热-力耦合作用的结构火灾安全设计评估方法及相应流程.首先通过建筑和燃料特性来预测可能的火灾热环境特性,然后再分析构件和结构的热响应和力学响应特性来判定结构是否会失效,以及可以降低热和力影响的预防失效措施.该文通过案例分析将该方法应用于某中庭钢结构屋顶的防火保护,得到经济合理的防火涂层设计,满足有关防火规范的安全等价要求.

Coupling Thermal and Mechanical Effect on structural Fire Safety

Structural fire safety is crucial to avoiding building collapse during a severe fire. Thermal environment produced by the fire affects structural response significantly, and the standard environment used for these conventional fire resistant tests is limited for some real fire cases. Thermal and mechanical response of building structure exposed to a real fire has not been well-understood yet. Coupling thermal and mechanical effect on structural fire safety should be studied carefully to develop useful engineering tools for cost-saving and safe structure. Methodology and technology of performance-based design and assessment for structural fire safety have been developed rapidly. In this paper, framework of structural fire safety design and assessment, with the coupling thermal and mechanical effect considered, will be introduced. Thermal environment will be predicted by considering fuel characteristics and building geometry, then temperature rise and mechanical response of structure will be analyzed to check whether the structure fails or not. A case study has been conducted to demonstrate the assessment process of steel roof structure in an atrium building. Reasonable area and thickness of fire protection coating were designed to meet the equivalent requirement of specific fire code on fire resistant level.