火灾下明框浮法玻璃热破裂的数值模拟研究

Numerical Simulation of Exposed Framing Float Glass Thermal Performance in Fire

玻璃的热破裂行为对建筑火灾的发展和蔓延具有显著影响.本研究使用ABAQUS有限元数值模拟软件,基于实验数据,构建数值模型,对明框浮法玻璃在火灾下的温度场、应力场、破裂时间和裂纹起裂位置进行精确计算和预测.本研究首先通过传热分析得到玻璃的温度场并与实验结果进行对比验证;再借助顺序耦合的热应力分析方法,计算得到玻璃内部的应力分布,并发现火灾下明框浮法玻璃最大主应力为拉应力,主要位于玻璃边缘区域.模拟结果发现,当温差产生的热应力达到玻璃表面所能承受的临界拉应力时,玻璃会发生起裂现象.该研究根据计算的应力分布成功预测玻璃首次破裂时间,模拟结果与4组对应实验的平均绝对百分比误差为10.2%,结果吻合较好.该研究发展并验证了明框浮法玻璃火灾下的数值预测模型,揭示了明框玻璃的热破裂机理,为进一步更加精确的玻璃热破裂行为的预测提供技术支撑.

Thermal breakage of glazing systems has significant influence on the compartment fire growth and development. A finite element numerical investigation was carried out with ABAQUS for accurate calculation and prediction of the cracking of exposed frame supported glass. First,based on the temperature profiles of the experiments,the simulated glass surface temperature field was calculated and found to agree well with the actual measured temperature. Second,the thermal stress analysis was conducted by the sequentially thermo-mechanical analysis method. It was found that tensile stresses located at the edge of the glass dominated the maximum principal stresses. When the thermal stresses reached the critical tensile stresses that the glass surface could endure,crack initiation would occur in the glass. Besides,the stress results were used to predict the first breakage time of the glass. The average error was 10.2% between numerical and experimental results. The study develops and validates a numerical model for exposed frame supported glass under fire and demonstrates the mechanism of glass breaking behaviour. Moreover,it may provide technical support and reference for the accurate prediction of glass thermal breakage.