建筑镀膜玻璃热炸裂原因浅析

什么是建筑镀膜玻璃热炸裂？ 当镀膜玻璃自身受热不均匀，冷热区之间形成温差，导致非均匀膨胀或收缩，形成的热应力大于镀膜玻璃的边缘抗拉强度时，玻璃通常会发生破裂。镀膜玻璃热应力破裂的特征明显，极易区别，这种破裂有时也称为热炸裂。     

建筑玻璃的热炸裂机理探讨

建筑玻璃的热炸裂问题,实质上是温度应力导致玻璃缺陷发展造成的断裂,所以对其炸裂机理的研究应从两方面着手,即分析产生温度应力的原因,温度应力场的性质和玻璃本身的缺陷与裂纹发生发展的过程。本文以亚运村五洲大酒店工程为实例,综合分析了日照,热吸收,非均匀温度场,非均匀膨胀造成温度应力的机理,并在温度场呈抛物线分布假设下对玻璃板的面内应力场进行计算,应用连续介质力学原理得出最大热应力数值计算公式和发生部位预测。在理论研究基础上,本文针对建筑玻璃设计与施工,提出防止热炸裂的有效措施,经在工程中总结,指出热炸裂现象是可以避免和减轻的。本文得出的结论,对玻璃制造单位与设计,施工单位以及用户都具有实际意义。     

火灾现场中高温窗玻璃遇水炸裂痕迹研究

对普通高温玻璃遇水炸裂的形成机理和特征进行研究.模拟火场条件,将3 mm和5 mm厚的窗玻璃在不同温度下加热10 min和30 min,分别用直流水和喷雾水射水冷却.结果:①受热温度越高,出现贯穿性裂纹越多. ②在较长的受热时间下,水冷却致表面裂纹较多且深.③3 mm厚玻璃遇水冷却炸裂,裂纹比较规则;5 mm厚玻璃遇水冷却炸裂,裂纹无规则,且出现多层裂纹. 结论:玻璃受热温度越高,受热时间越长,玻璃越厚,遇水冷却产生的裂纹数目越多.     

高度不同的中空玻璃破裂行为及热炸裂痕迹研究

对距火源不同高度的中空玻璃破裂行为及热炸裂痕迹进行研究,分析迎火面和背火面的温度、热应力、裂纹形态及玻璃热炸裂痕迹等参数。玻璃板厚度为6 mm,尺寸为600mm×900mm,空气夹层厚度为6mm。对比不同高度处玻璃在5、10、15、20、25、30min的温度变化曲线。结果表明:迎火面和背火面上距离玻璃底端36cm处温度最高。迎火面玻璃在底端热应力较小,容易破裂;背火面玻璃上高度与长度比值约为0.4的位置热应力最小,最容易破裂。迎火面多从底段边缘处开裂,背火面在左右两侧被遮蔽边缘开裂。迎火面玻璃热炸裂后碎片表面无同心纹,形成的裂纹整体呈"蝌蚪"状;背火面玻璃裂纹为树枝状放射性裂纹,短直密集,无同心纹,裂纹断口光滑,断面上未出现弓形纹。     

火场消防射水造成的窗玻璃破坏痕迹分析

为了研究消防射水后的窗玻璃破坏痕迹,进一步丰富火灾调查基础理论,通过模拟火灾现场中窗玻璃受消防射水破坏试验,观察窗玻璃的破坏过程和碎片形态,探讨窗玻璃破坏痕迹在热作用和消防射水两个不同阶段的痕迹特征和形成机理,分析了消防射水后窗玻璃破坏痕迹在火灾原因调查中的应用,提出了消防射水后窗玻璃碎片具有微裂纹和齿状断面两种特殊痕迹特征,并探讨了此类痕迹的形成过程和物证作用。     

普通玻璃和钢化玻璃破坏痕迹的微观形貌分析

选择典型的普通平板玻璃和钢化玻璃作为研究对象,利用火灾痕迹物证综合实验台、箱式电阻炉模拟室内火灾的热环境,制备了两种典型玻璃的破坏痕迹,通过电子扫描显微镜(SEM)观察玻璃破坏痕迹的微观形貌。实验结果表明:玻璃种类对机械破坏痕迹的微观形貌有一定的影响,钢化玻璃的裂纹比较密集,裂纹比较深;而普通玻璃的裂纹的纹痕比较明显,在扫描电镜下观察时裂纹棱角比较突出,并且呈"人"字形的树杈状分布。温度对玻璃的机械破坏痕迹和受热破坏痕迹的微观形貌影响有所不同,尤其是对机械破坏的断面痕迹的影响,机械破坏的普通玻璃在受热后的玻璃断面失去了弓形纹特征。钢化玻璃遇水炸裂产生的纹痕随着温度的升高,裂纹由密集逐渐变得疏松,纹痕也越来越明显。     

关于玻璃幕墙在安装和使用过程中玻璃炸裂问题的专题报告

本文描述了玻璃幕墙安装和使用过程中玻璃的炸裂现象，分析了玻璃炸裂产生的原因，提出了解决问题的措施。     

火场中玻璃裂纹特征与破坏条件的关联性

模拟制备了普通平板玻璃在火场中热应力和机械应力破坏下的痕迹,对痕迹的宏观特征进行了分析,研究了火源强度对热破坏玻璃痕迹的影响,以及玻璃碎片裂纹特征与受力方向的关联性。实验结果表明,玻璃热炸裂时均以玻璃中间边缘某处为集中点,形成一根贯穿玻璃的主裂纹和几根向不同方向蔓延的分裂纹;火源强度越大,树枝状裂纹主干根部产生的分裂纹越多,且越向主裂纹聚集;裂纹拐角处弓形纹特征和碎齿状裂纹出现位置与受力方向有着紧密的关联性,而现场勘查仅依据碎齿位置和弓形纹特征是不准确的。     

建筑玻璃热炸裂机理的研究

本文采用有发元法全面求解了建筑玻璃的日光照射下产生的温度场和应力场，详细研究了建筑玻璃炸裂机理和特性，所得结论与实验是一致的它们对建筑工程玻璃炸裂的定性具有指导意义。     

火场中的玻璃

一块普通的玻璃很难引起人们的注意。倘若你将一块普通玻璃在火中加温，而且是逐步升温，直到炸裂、熔化，中途你可以浇上水，而后，你仔细观察，会发现过火玻璃有很多特点，这些特点很可能成为火调人员调查火灾原因的重要证据，我相信这些会引起你的兴趣，不妨试试，下面本文将就玻璃在火场中的特点来叙述其在火调中的作用。我们要想依据火场中的玻璃中查找火因证据、线索，就必须从玻璃破坏的痕迹入手，确切地说是在热作用下玻璃破坏的痕迹。l、玻璃的热变形普通平板玻璃主要由二氧化硅、氧化钙及少量的氧化钠、氧化铝等组成，它不象钢化…     

热荷载作用下玻璃破裂影响因素的显著性研究

综合分析了影响浮法玻璃破裂的各种因素,利用封闭腔室玻璃破裂模拟试验装置进行了7因素2水平正交试验.结果表明:玻璃厚度、玻璃边缘平整度、辐射源升温速率对玻璃的破裂影响很大,玻璃平面尺寸、遮蔽表面宽度影响次之,而框架内填充物(石膏粉)厚度和辐射源距离影响较小.温差和热应力的中位数分别为129.2℃,69.13MPa.     

Assessment of a model development for window glass breakage due to fire exposure in a field model

This paper presents a model development for the prediction of window glass breakage and fallout in a field model. Glass breakage is based on the temperature difference and the allowable glass breaking stress; and glass fallout is determined by a preset number of successive breakages. As a validation, generally good agreements are obtained between the numerical predictions and the data from a compartment fire experiment. The predicted glass surface temperature and the adjacent gas temperature are within 10–25% of the test data. For fire sizes of 170, 280 and 390 kW, the time of initial occurrence of glass breakage are shown within reasonable range of the experimental results. For the 680 kW fire case, the model shows an earlier glass fallout time, however, the predicted glass temperature at fallout is around 450 °C and is consistent with previous experiments. Further research to improve the model is discussed such as on radiation modeling and the criteria of glass breakage and fallout.     

Validation of a numerical model for curtain walls with MVHS during free burning

Glass breakage of curtain wall coverings during a fire can promote the spread of a fire in high-rise buildings. Prior to the development of sprinklers to prevent and delay glass breakage, it is necessary to identify the breakage mechanism of curtain wall glass panes and to establish a numerical model to simulate various fire situations using sprinklers to design effective sprinkler systems. The present study was conducted to establish a numerical model and analysis procedures to simulate fire situations. First, curtain wall was installed on one side of a testing chamber that was 3 m (L) × 3.2 m (W) × 2.4 m (H), and a free burning experiment was conducted using heptane. The same experimental conditions were simulated using a numerical model employing the modified volume heat source (MVHS) model. To analyze the validity of the numerical model, the air temperature inside the room and the surface temperatures of the curtain wall Al frame and glass panes calculated by numerical analysis were compared with experimental values, and the location and timing of the initial crack were compared. Thermocouples were installed on the Al frame and the glass surface to measure the surface temperature of the curtain wall during the fire for approximately 100 s after the onset of the fire. Additional thermocouples were installed to measure the air temperature inside the room to verify the results of the numerical analysis. A numerical model using the MVHS model was established to analyze the overall temperature distribution and the behavior of thermal stress on the curtain wall caused by the fire. MVHS calculations were based on measured fuel consumption, and the numerical analysis results were compared with the experimental values. We confirmed that the temperature calculated using computational fluid dynamics (CFD) was in good agreement with the temperature measured in the experiment. The temperature distribution and thermal stress of the curtain wall up to the point of glass breakage were reviewed using a thermal stress structural analysis that employed the results of the CFD analysis with MVHS. The time required to reach the temperature required for glass to break in the numerical analysis and the time required for the first crack to occur in the experiment were identical. The crack positions obtained from the numerical model and experiments were also the same. Overall, our results showed that the numerical model using the MVHS model is suitable for predicting curtain wall breakage and temperature distributions inside a space during the fire.     

The Breakage of Float Glass with Four-Edge Shading Under the Combined Effect of Wind Loading and Thermal Loading

The glass breakage in high-rise building fires may be significantly influenced by both the compartment fire and the environmental wind. In this work, float glass panes supported by the frame with a dimension of 600 × 600 × 6 mm³ were employed to study the glass breakage under the combination of wind and fire effects. The first breaking time, glass temperature, crack patterns, and fallout were obtained. With an increase of wind speed, the average value of temperature difference between the mean temperature at the heated exposed side and that at the ambient shaded side decreased gradually when crack initiated. The average time to first crack was maximum without wind loading and decreased gradually as the wind speed increased. Comparing with the glass breakage only under thermal radiation, the combination of environmental wind accelerated the glass breaking. The present results suggest that the wind effect should be considered for building fire protection in the window glass design.     

封闭阳台对夏季室内热环境的影响

论述了封闭阳台的夏季热过程。从构成建筑室内热环境的4个要素的角度出发,简单分析了封闭阳台在夏季对室内热环境产生的不利影响,针对如何降低封闭阳台对室内热环境的不利影响提出了几点建议。     

建筑用防火玻璃的表面处理技术

介绍了建筑用防火玻璃的分类、技术要求和技术特点 ,着重讨论了普通平板玻璃通过表面的物理和化学处理方法 ,提高玻璃表面应力状态对玻璃耐热冲击的影响 ,使普通单片玻璃做成具有防火、耐火功能的单片防火玻璃     

Fracture behavior of a four-point fixed glass curtain wall under fire conditions

The cracking and subsequent fallout of glazing could significantly affect compartment fire dynamics by creating a new opening for air to enter. Twenty-four 1200×1200×6 mm³ soda-lime glass panes in eight different fixing forms were heated by a 500×500 mm² N-heptane pool fire to investigate the influence of fixing conditions on glass breakage and fallout. The time of crack initiation, behavior of crack propagation, heat release rates, central gas temperatures, glass surface temperatures and loss of integrity of the glazing assembly were investigated. The relationship between fixing form and crack behavior is discussed, based on the experimental results. The results show that all the cracks initiated at the supporting point and intersected rapidly, causing glass fallout. Mechanical stress caused by supporting pins and thermal stress caused by glass temperature difference (ranging from 48 °C to 159 °C) are the causes of breaking for this kind of curtain wall. It is concluded that various fixing locations have a significant effect on glass breaking. Among the eight cases, the glass panes whose supporting points were located at 10 cm (Case 1) or 5 cm (Case 8) from the edges performed best: these support locations are recommended in practical engineering because of the good fire resistance and structural beauty of such panes.     

泡沫玻璃外保温墙体窗口周边传热试验研究

采用大型耐候性试验装置实测2种泡沫玻璃外保温墙体窗口周边的热流密度的结果表明,2种泡沫玻璃外保温墙体的窗口周边热流密度偏差"面砖系统"窗口周边达29.59%";涂料系统"窗口周边热流密度差达34.51%,传热不均匀性较大。当试验温差△t≤10℃时,窗口周边的传热能力相差近35%,热应力及其衍生问题不容忽视。因此,在外保温墙体窗户设计、施工、材料选用时,应尽量采用断桥窗框,降低热桥效应,提高节能效果。     

玻璃涂膜在既有建筑节能改造中的作用

门窗玻璃对建筑围护结构的节能有着重要的影响,通过控制玻璃散失的热能可以有效减少建筑能耗。文章通过某建筑外窗玻璃进行现场涂膜改造过程的实时记录,直观显现玻璃涂膜隔热层控制外窗热辐射的效果,并分析其降低空调负荷、增加室内热舒适性以及在既有建筑节能改造中的作用。同时分析了可逆性的玻璃涂膜用于保护建筑节能改造的可行性,探索保护建筑在不改变外立面历史原状的原则下提升节能效果的有效方式。