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受限空间火灾环境下玻璃破裂行为研究

Behavior of Glass Breakage in Enclosure Fires

【作者】 张庆文

【导师】 范维澄; 张和平;

【作者基本信息】 中国科学技术大学 , 安全技术及工程, 2006, 博士

【摘要】 玻璃因其透光、轻便等独特优点广泛应用于各种现代建筑中,然而在建筑防火设计中往往成为薄弱环节。玻璃构件在火灾环境下容易破裂并脱落形成通风口,从而加剧火灾的燃烧过程并向建筑中的其它区域蔓延。 本文针对前人建立的玻璃破裂温差判据仅适用于大的边缘遮蔽宽度和足够快的加热速度,不能满足玻璃构件防火设计的需求,以及某些特殊建筑玻璃构件防火设计出现的困难,开展受限空间火灾环境下玻璃破裂行为研究,发展适用范围广泛的玻璃破裂判据,研究玻璃构件防火设计的性能化方法。 基于ISO9705全尺寸实验台,对受限空间火灾环境下玻璃破裂行为进行实验研究。对于厚度为4mm和6mm的浮法玻璃以及厚度为6mm和10mm的钢化玻璃,在不同火源功率条件下,测量了燃烧室内气体温度、玻璃近壁面气体温度、玻璃暴露表面温度、玻璃遮蔽表面温度、玻璃表面热通量以及玻璃的破裂时间和破裂模式等参数,分析了玻璃破裂与其表面温度分布等参数的关系,建立了浮法玻璃首次破裂时间分别与烟气温度、热释放速率和热通量这三个关键参数之间的关系。通过实验数据分析表明,浮法玻璃尺寸越大,厚度越小,形成开口的几率越大,钢化玻璃的耐火性能个体差别较大,并且厚度越大,耐火性能越好。 针对玻璃的种类及其安装方式,建立了能够指导防火设计的玻璃破裂的热通量判据。该判据适用范围较广,并且在推导过程中进行了保守的假设,用于分析玻璃火灾环境下破裂行为时具有一定的安全余量。 模拟计算与实验结果的对比分析表明,FDS模拟获得的玻璃暴露表面温度比实际值略高,BREAK1模拟的玻璃首次破裂时间要比实验结果早,且这两种工具获得的结果比较保守,可以为分析火灾环境下玻璃的破裂行为提供参考。 通过将研究结果应用于玻璃构件的防火设计,确定了玻璃构件防火性能的判据和玻璃防火性能的计算工具和方法,提出了针对建筑玻璃构件防火设计的性能化方法。

【Abstract】 Glass, for its unique advantages of transmission, is widely used in various modern architectures. However, glass often becomes a weak link in the fire protection design of buildings. Window glass breaking plays an important role in compartment fire dynamics as the window acts as a wall before breaking and as a vent after breaking.The criterion of temperature difference for glass breakage suggested in previous work can only used in those cases with large shading and fast heating. However, it can’t fit some requirements for the glass components during the design of fire protection in most other cases. In this work, a new criterion for glass breakage is developed, namely, the heat flux criterion, which can be widely used in most cases. In addition, the method of performance-based fire design is also proposed for glass components.Based on the ISO9705 full scale experimental setup, the glass breakage behavior in an enclosure fire environment is analyzed. With the float glass of 4mm and 6mm thick as the experimental targets, the work measures the following parameters under the conditions of different fire sources: enclosure gas temperature, local gas temperature, exposed glass surface temperature, shaded glass surface temperature, glass surface heat flux, the glass breakage time and breaking patterns. The relations of glass breakage and parameters like the glass surface temperature distribution are analyzed. The relations between the first breakage time with respectively gas temperature, heat release rate and heat flux are also studied. The results show that vents can be more easily formed for larger and thicker glass. In the case of toughened glass, their fire resistance show distinguished difference among themselves. In addition, the thicker, the better fire resistance.In terms of the type and installation of glass, the heat flux is used as the criterion of glass breakage for edge-protected and edge-exposed glass to guide the design of fire protection. This new criterion can be used for various glass components. What’s more,

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