冷弯薄壁C型钢承重组合墙耐火性能简化理论模型研究

Simplified theoretical model on fire performance of load bearing cold-formed steel wall systems

冷弯薄壁型钢组合墙在国内外逐渐应用于低层及多层房屋结构的承重单元,其抗火问题亦得到日益关注。针对该类型承重墙的耐火性能开展简化模型理论研究,提出可考虑墙体各组成层不同热物理特性及墙覆板脱落影响的组合墙隐式差分传热模型,以及组合墙热-力耦合简化模型,并以此进行墙体受火传热、时间-变形曲线模拟,以及破坏模式、耐火极限的预测。所提出组合墙传热及热-力耦合模型均通过前期完成的冷弯薄壁型钢承重墙耐火试验进行验证,模型预测结果与试验结果整体吻合良好。根据组合墙抗火简化模型,进行国内常见低层冷弯薄壁型钢承重墙体耐火性能模拟,提出分别具有30、60 min耐火极限的冷弯薄壁C型钢组合墙横截面形式、荷载水平及其构造措施,实现该类型墙体实用抗火设计。

In recent years,cold-formed steel（ CFS） wall systems have been increasingly utilized as load-bearing structural components in low and mid-rise buildings. The fire performance of such wall systems has become an important concern in fire safety design. A theoretical investigation on the simplified model of load-bearing CFS wall systems under fire conditions was carried out. An implicit thermal response model which considers the influence of thermal physical properties and fall-off of different boards was developed to predict the heat transfer across the cross section of CFS wall systems. In addition,a thermo-mechanical response model was presented to predict the timedependent lateral deflection,failure mode and fire resistance time for CFS wall systems in fire. Both the thermal response model and thermo-mechanical response model were validated by previous fire experimental results of loadbearing CFS wall systems. Based on those simplified models,the fire performance of different CFS wall systems was simulated. Both the configuration details and corresponding load levels were given for CFS wall systems with the fire resistant rating of 30 and 60 min. Hence,the practical fire resistant design of such wall systems was developed and should meet the fire resistant requirement of low-rise buildings in China.