火灾下大空间结构温度场的数值模拟分析

Numerical Simulation Analysis on Temperature Field for Large-space Structures under Fire

大空间结构近年来在我国得到了迅速的发展,然而,我国原有防火规范常常无法满足该类结构防火设计的需要。目前性能化设计方法是防火研究领域的发展趋势,而结构内部温度场的准确计算与否是其中非常关键的重要环节。笔者利用流体动力学计算软件FLUENT对不同火灾曲线和火源功率下,典型尺寸模型的温度场随时间与空间的分布情况进行了计算模拟,并与我国《钢结构防火技术规程》(征求意见稿)中近似公式计算结果相对比,同时对规范中未规定的火源功率可否使用已知值采用线性插值方法求解进行了讨论,并深入分析了此简化计算公式存在的局限性。

Large-space structures have developed rapidly in China. However, relative fire preventien codes and regulations in China usually could not meet the requirment of this kind of structure. Perfomance-based design method has been the developing trend in fire preventien research field, and whether the temperature field has been accurately calculated is the key step. A widely used CFD soft package FLUENT was employed to make computational simulation to temperature distributions brought by divergent fire curves and heat release rates. Comparisons have also been made between the results of numerical method and of simplified formula in Technical Code on Fire Safety of Steel Building Structure （Consultative I）Draft） in China. Finally, discussions for whether the linear interpolatien method could be applied to unknown fires in code by known ones were made and limitations to simplified formula were analyzed in-depth.