在建高层建筑火灾隐患及其预防对策

由于各种因素的影响,当前我国大量装饰豪华的大型在建高层建筑不断兴建,为繁荣我国市场经济起了积极作用。随着大量的高层建筑的出现,高层建筑的防火问题也越来越受到关注。高层建筑大厦层数高、空间大,在建时施工人员密集,一旦发生火灾势必扑救难度大,也不便于组织人员和物资的疏散。本文为此首先探讨了其所存在的隐患,然后提出了在建高层建筑火灾隐患的预防对策,包括合理进行建筑设计、加强建筑施工防火、合理使用装修材料、进行性能化防火预测和加强水喷淋防火。     

大型超市安全疏散设计的初步研究

根据某大型超市的建筑设计方案以及人员分布情况,针对该超市各防火分区之间疏散楼梯分布不均 匀的问题,提出２种改进设计方案。一种是改进防火分区设置,在相邻防火分区之间设置共用楼梯,使得防火 分区的疏散宽度分布更均匀,另一种是缩小相关防火分区的面积从而增加一个防火分区。采用EVACNET４进行 计算机模拟,得到了３种疏散场景下人员疏散的时间。计算结果表明,当防火分区面积比较大时,疏散楼梯在 防火分区四周均匀分布有利于人员疏散;共用楼梯的设置,既有利于人员疏散,又可以提高楼梯的利用率;适 当减小防火分区的面积可以     

防火卷帘对防护工程火灾烟气扩散影响研究

为讨论防火卷帘对防护工程火灾时走廊内烟气扩散的影响,根据相似原理搭建了模型与实体比例为1:4的单室-走廊模型实验台,进行了2个工况的模型实验,分析了走廊内烟气温度分布,研究了不同工况条件下走廊内CO浓度、CO_2浓度及O_2浓度等烟气特性。结果表明,防火卷帘关闭后走廊中最高温度有所降低,走廊中温度竖向分布更加趋于一致,烟气的热分层稳定性降低;卷帘门关闭后导致烟气浓度发生变化的时间提前,且烟气浓度的极值向对人员安全不利的方向显著发展;建议火灾初期和人员未完全逃出防火分区时防火卷帘处于开启状态,当人员安全疏散出防火分区后再关闭。     

内翅板蒸发式冷凝器降膜流动与传热特性

为了增强蒸发式冷凝器板外气液两相流动与传热,基于数值模拟方法对比分析了几种新型的板片结构,研究了板片构型、喷淋水喷淋密度、空气入口速度等因素对气液两相流流体流动及传热性能的影响。结果表明:半圆波纹板有较长的水膜稳定时间和较大的换热面积,换热性能较好;不同板片结构的蒸发式冷凝器具有不同的最佳喷淋水喷淋密度,最佳喷淋密度区间范围为0.48~0.93 kg/(m·s);空气入口速度一定时,半圆波纹板的壁面温度随喷淋密度增大而增大,气液界面温度随喷淋密度增大而减小;当空气入口速度小于2.5 m/s时,空气入口速度的适当增大能够有效减薄半圆波纹板板外水膜厚度,强化换热。     

浅谈钢结构抗火设计

分析钢材高温下力学性能的变化及影响机理，总结了钢结构抗火设计的基本方法及各自的优缺点和钢结构实用抗火设计计算方法的一般步骤，概述了钢结构防火保护方法和抗火设计目标、意义。     

整体结构中两跨钢梁火灾变形性能的试验研究

为研究整体结构中钢梁的抗火性能,利用自行研制的试验炉和相关测试装置,对三层三跨足尺钢框架楼中三层顶一两跨连续梁进行受火试验研究,试验中钢梁受火,钢柱和节点不受火。试验量测了炉体内烟气温度、钢梁和混凝土楼板四等分点处截面沿厚度不同点的温度场、位于炉体外钢梁接点温度、钢梁和楼板四等分点处的竖向变形。结果表明:未进行防火保护的钢梁温度与烟气温度基本一致;升温阶段混凝土板温度滞后于钢梁的温度,停止升温后钢梁温度迅速降低,混凝土板温度仍会升高直至两者温度趋于一致。在整个试验过程中,沿混凝土板截面高度存在较大温度梯度;整体结构中未进行防火保护的钢梁具有很好的变形性能,可以考虑减少防火保护;不同位置的构件由于受到相临构件的约束程度不同,在火灾中的变形性能不同,在抗火设计时应进行区别对待;钢柱虽不受火,在整个试验过程中产生轴向膨胀。     

建筑火灾中人员疏散行为模式探究

俗话说"水火无情",火灾不仅会造成大量的财产损失,更为严重的是会造成严重的人员伤亡。建筑失火是人员伤亡的重灾区,当建筑失火时,建筑中的人的反应行为是影响人员是否能够安全疏散的重要因素之一。在火灾发生时需要能够在最短的时间内将人员安全地从建筑中疏散出去以确保人员的安全,建筑火灾中人员是否能够安全疏散是考量建筑防火设计是否合理的重要考量因素之一,同时,建筑火灾发生时人员的疏散受到人的行为、年龄、性别以及火灾自救能力等多种因素的影响。通过对火灾发生时人员面临火灾所采取的各种反应行为进行研究分析,为后续的建筑防火及人员疏散设计、防火安全评估等都有着极为重要的意义。     

混合流蒸发式冷凝器中鼓泡板片喷淋侧热质传递研究

本文采用控制变量法对混合流状态下的鼓泡式换热板片喷淋水侧的换热性能进行实验研究,分析不同参数对鼓泡板片喷淋水侧热质传递以及阻力性能的影响。结果表明：适当增加喷淋水量可以改善鼓泡板片表面水膜分布的均匀性,提升鼓泡板片的换热效果,建议不低于0.347 kg/(s·m);板片间距从20 mm增至30 mm时,板间空气的进出口压损下降较为显著,随着间距的进一步增大,空气的流通截面积并不会对板间空气的进出口压损产生很大影响;综合考虑,喷淋侧板间距为25 mm、平均截面风速为6.66 m/s时兼顾了压损影响和换热性能,为最优方案;相较于正位布置,板片错位布置更合理,换热性能更好,换热效果是正位布置的1.1～1.4倍。     

基于几何方法的人员疏散最佳路径

防火防灾中的人员疏散研究具有十分重要的意义。传统的方法多采用网格法来确定最佳路径,由于人员个体只能在网格中运动,模拟很难准确。本文首次提出基于几何的人员疏散模型,人可以沿任意方向运动,考虑了人员个体与障碍物、人员个体之间的碰撞检测,按照路径最短的原则确定出了人员疏散的方向和路径,在此基础上,对单个房间内的人员疏散过程进行了模拟。算例结果表明,本文的方法对疏散过程模拟得更真实、更精确,是一种有效的模拟人员疏散过程的手段。     

试论商场建筑防火设计

本文笔者根据自己的工作实践，从防火分隔设计、排烟系统设计、人员疏散安全区的防火设计着三方面探讨了商场建筑防火设计。     

改性硝基胍装药快烤响应特性研究

为了研究改性后的硝基胍装药在生产、储存、运输和使用过程中因意外爆燃而产生的响应特性,采用温度采集仪记录了火灾刺激条件下硝基胍的火球温度变化规律,通过压力测试系统测量了反应过程的冲击波压力,使用热辐射测试系统测量了爆炸火球的热通量,通过Baker公式计算了火球的理论热通量。结果表明:第1发快烤点火后108 s样品发生反应,最高温度为894.3 ℃;第2发快烤点火后142 s样品发生反应,最高温度为960.7 ℃;两发快烤反应持续时间均约为2 s,响应等级均为爆燃。分析快烤响应过程中的冲击波、破片、热辐射毁伤效应发现,热辐射是硝基胍遭受火灾刺激的主要毁伤形式。对比两发快烤及不同距离处的热通量发现,测量值与理论值的规律一致。     

Fire and Corrosion Resistances of Intumescent Nano-coating Containing Nano-SiO2 in Salt Spray Condition

The nano-concentrates and fiame retardant nano-coating were prepared in thhis study. The effect of nano-SiO₂ on the corrosion resistance and fire resistance of ammonium polyphosphate-pentaerythritol-melamine (APP-PER-MEL) coating was investigated by differential thermal analysis (DTA), scanning electron microscopy (SEM), effective thermal conductivity (λ/d), X-ray photoelectron spectroscopy (XPS) and fire protection test. The chemical action and endothermic effect of ammonium polyphosphate, pentaerythritol and melamine in traditional flame retardant coating were damaged by salt spray condition, whereas the flame-retardant additives in the nano-coating demonstrated the good chemical interaction in salt spray condition. The uniformly dispersed nano-SiO₂ particles could improve corrosion resistance of the coating, and hence nano-coating could remain the good fire-resistant properties even after 500 h salt spray test.     

Thermal Analysis of Thermal Protection System of Test Launch Vehicle

In this paper, a thermal analysis of the thermal protection system (TPS) of test launch vehicle (TLV) is explained. TLV is heated during the flight due to engine exhaust plume gas by thermal radiation and a TPS is needed to protect the vehicle from the heating. The thermal analysis of the TPS is conducted to predict the heat flux from plume gas and temperature of the TPS during the flight. To simplify the thermal analysis, plume gas radiation and radiative properties are assumed to be surface radiation and constants, respectively. Thermal conductivity, emissivity and absorptivity of the TPS material are measured. Proper plume conditions are determined from the preliminary analysis and then the heat flux and temperature of the TPS are calculated.     

热辐射对消防服热防护性能及耐久性的影响

为探讨低热辐射对消防服用织物热防护性能及物理机械性能的影响,选用两种常用消防服用外层织物,利用远红外石英灯管辐射仪,以不同的辐射强度(6.5kw/m2和9.7kw/m2)对织物分别进行5、10、20、30min的辐射,利用NI虚拟仪器记录辐射时织物表面温度,并测试其各项物理机械性能及TPP值变化。结果表明:当织物表面温度低于织物纤维玻璃化温度时,织物在半小时内能保持其68.9%～84.6%的撕破强力,且TPP值增大,即热防护性能变好;而当织物表面温度达到纤维玻璃化温度时,织物断裂强力及撕破强力随辐射时间增加显著下降,但其TPP值仍增大。     

基于空腔辐射效应的钢索截面温度场分析

该文基于传热学基本理论及ABAQUS数值传热分析平台,以圆柱壁的截面径向导热热阻和空腔热阻代替平壁导热热阻,分别建立了四面受火工况下具有空腔几何特征的钢索截面升温理论及数值传热模型,得到考虑空腔辐射传热效应的无防火保护钢索截面升温历程,将其与具有等效截面圆钢的升温历程比较,研究表明:截面尺寸和空腔辐射效应对钢索截面升温历程有显著影响,空腔辐射效应在火灾升温初期加快了钢索截面的升温速率;最终在钢索热传导理论分析及数值模拟基础上,建议了钢索截面升温计算式,从而准确确定火灾升温历程中钢索材料性能衰减程度,正确评估预应力张拉结构中钢索的抗火承载力。     

Thermal–mechanical modelling of laminates with fire protection coating

This paper presents a modelling approach to analyse the protection provided by passive and intumescent surface coatings on glass fibre reinforced laminate substrates exposed to fire. The modelling involves a multi-stage analytical approach: (i) thermal analysis of heat transfer from the fire through the surface insulation coating, which includes decomposition and expansion in the case of an intumescent material; (ii) thermal–chemical analysis of heat transfer through the fibreglass laminate substrate (beneath the fire protective coating), including decomposition of the polymer matrix; and (iii) thermal–mechanical analysis of softening and failure of the laminate under in-plane tension or compression loading. The modelling approach is validated using experimental temperature and strength data from fire structural tests performed on woven glass–vinyl ester laminates insulated with passive (ceramic fibre mat) or organic intumescent surface coatings.     

Assessment of structural steel from the World Trade Center towers, part IV: Experimental techniques to assess possible exposure to high-temperature excursions

Recovered structural steel from the World Trade Center was examined as part of the National Institute of Standards and Technology investigation to provide data on potential temperature excursions seen by the steel for input and validation of the fire and thermal finite element models. While numerous experimental techniques were appraised for use during this study, two proved to be practical: assessment of the primer paint on the structural elements and examination of the steel microstructure. Results from these two techniques are presented. Evaluation of primer paint from 21 exterior panel sections, which represent approximately 3% of the panels from fire-involved floors, was conducted and indicated that only three locations may have experienced temperatures over 250°C. Steel microstructures taken from these and other areas on exterior panels exposed to pre-collapse fires showed no evidence of exposure to temperatures exceeding 625°C for times longer than the detectable lower limit of 15 min. The lack of high-temperature excursions observed during this analysis may be related to the protection afforded by intact spray-applied fire-resistant material on the components at the time of exposure.     

Modeling of explosion thermal radiation

The hydrodynamic and radiation processes accompanying explosions of chemical explosives and fuel-air mixtures have been considered. Computer modeling of the radiation from a fire ball of explosion and a flame of diffusion combustion of a hydrocarbon fuel has been performed. The dependences of the heat flux density from the region occupied by explosion and combustion products on its temperature and geometric characteristics have been determined. Thermal load distributions on targets of different orientations in the vicinity of the energy release zone have been obtained. A comparison of the thermal parameters on radiation detectors with the criteria of thermal affection of people and ignition of combustible materials has been made.     

Insulating capacity of fly ash pastes used for passive protection against fire

This study deals with the possibilities of recycling different combustion sub-products into usable products for passive protection against fire. We studied conventional combustion fly ashes from different types of pulverized coal in thermal power plants, which have a long tradition of applicability in construction, and ashes from new energy production processes based on other fuels, such as biomass, in an effort to find new applications for them. In order to be able to carry out this study, we developed a methodology that allows us to (1) predict the insulating behaviour of pastes comprising ashes, binders and other additives, (2) know what contributions each of the components makes and (3) considerably reduce the time required to test potential products with fire-resistant properties.     

新型耐火耐候钢材高温力学性能与本构模型研究

采用标准试验方法,对首钢集团生产的楼承板用SQ410FRW耐火耐候钢冷轧钢带进行稳态拉伸试验,以测定其典型高温力学性能指标,包括钢材高温弹性模量、规定塑性延伸强度、抗拉强度、断后伸长率和断面收缩率。通过非线性回归方法得出相应的高温折减系数表达式,包括弹性模量折减系数、规定塑性延伸强度折减系数和抗拉强度折减系数。根据试验应力-应变关系曲线,回归得出基于Ramberg-Osgood模型(R-O模型)的应力-应变本构模型,以用于后续有限元参数化建模过程中对结构构件的温度场分析和顺序热力耦合分析。试验结果表明：绝大多数拉伸试样均在平行段内或标距段内发生断裂,且断后伸长率随温度升高呈现总体增大趋势;高温弹性模量、高温规定塑性延伸强度和抗拉强度在600℃及以下时降低较少,均保持在常温名义值的60%以上,基本满足耐火钢的力学性能指标要求;基于R-O模型的应力-应变本构关系表达式的拟合优度均在90%以上,与试验应力-应变曲线吻合良好,故提出的本构模型可用于相关钢结构或组合结构构件的有限元抗火分析。