过火坍塌建筑火灾调查中起火部位的认定分析

文章先分析了过火坍塌建筑火灾特征,随后介绍了过火坍塌建筑起火部位认定要点,包括统筹规划、扩展取证范围、分阶段调查、大胆假设论证,最后介绍了过火坍塌建筑起火部位认定工作基础保障,包括提高火调人员专业理论、基层指战员积极参与、打造稳定人才队伍,希望能给相关人士提供有效参考。     

一起过失引起的重大电气火灾的调查

通过一起过失引起的电气火灾的调查,分析火灾现场的痕迹物证;通过充分调查取证,准确认定了起火时间、起火部位、起火点和起火原因,并总结了火灾事故教训,对同类火灾事故调查处理工作具有一定指导作用.     

高温火直接作用下钢梁抗火性能试验研究

为研究高温火直接作用下钢梁的抗火性能,对其进行了高温火直接作用试验;同时,以受热时间作为变化参数,对比分析了高温火直接作用和按ISO 834标准升温过程钢梁的轴力、跨中挠度及耐火时间。结果表明：高温火直接作用与按ISO 834标准升温下,钢梁破坏端面的微观组织及升温过程的受力和变形存在明显差异;无论有无防火涂层的保护,当温度800℃时,高温火直接作用下钢梁的最大轴力比按ISO 834标准升温的增大76.9%以上;同时,防火涂层厚度对钢梁的耐火时间也有影响,无防火涂层时,钢梁的耐火时间小于20min;有防火涂层保护时,随防火涂层厚度增厚,两种高温作用下,钢梁的耐火时间相近,但防火涂层厚度不足15mm时,耐火时间相差20%以上;当防火涂层厚度为15mm时,在温度约800℃高温火直接作用下,其耐火时间为26min。     

防火卷帘代替防火墙时其钢构件耐火保护问题的探讨

通过分析高层建筑和大型结构建筑防火分区中 ,钢质防火卷帘代替防火墙的优缺点 ,结合目前建筑市场上的施工现状 ,对防火卷帘和耐火性进行分析 ,提出了双轨特级卷帘钢构件的耐火保护问题。建议采用新材料硅酸钙防火板对其钢构件作包覆耐火保护 ,并初步确定了耐火保护结构方案     

钢质防火门耐火性能提高的途径

钢质防火门是一种与防火窗 ,防火玻璃隔断相配套的防火设施 ,它适用于高层建筑 ,宾馆 ,医院 ,库房等消防安全重要场所。它与防火窗 ,防火玻璃隔断配套 ,不仅能阻止火的蔓延 ,还可以避免发生火灾而造成的严重经济损失。五常防火门厂自 1986年生产防火门至今 ,一直重视防火门的耐火性能 ,因其直接影响到防火门的质量和耐火性能的提高。1　耐火性能的分析　　 1986年我厂防火门上马后 ,就送到国家固定灭火系统和耐火构件质量监督检验中心进行耐火性能检测 ,可检测结果丙级都没有达到。国家标准规定 ,消防产品三年必须到国家指定的检测部门检测…     

On the fire resistance of structural steel elements derived from standard fire tests or by calculation

Due to high costs, a fire resistance test of a load-bearing structural element is usually limited to one test specimen — in a few countries, to two test specimens. Accordingly, there are no possibilities of evaluating the test results statistically.For a single test specimen, the actual quality of the structural material represents a random sample from a wide variety. This applies also to the initial imperfections of the structural elements. In consequence of this, a standard fire resistance test is generally carried out on a test specimen with a load-bearing capacity which is greater — most often significantly greater — than the load-bearing capacity related to the characteristic values of the mechanical material strength and of the imperfections of the structural member. In current practice, no corrections of the test results with respect to this are made.In a conventional analytical design, a determination of the load-bearing capacity of a structure at room temperature conditions is based on the characteristics values of the strength and imperfections. Extended to a structural fire engineering design, this procedure will give an analytically determined fire resistance of a load-bearing structural element which is lower — normally essentially lower — than the corresponding value derived from a standard fire resistance test.Available methods for a simplified calculation of the temperature of fire exposed steel structures are, as a rule, based on the assumption of a uniformly distributed temperature structure at each time of fire exposure. The ECCS Recommendations for an analytical design of steel structures exposed to a standard fire follow this kind of approach. For certain types of steel structures, for example, beams with a slab on the upper flange, a considerable temperature variation arises over the cross section as well as in the longitudinal direction during a fire resistance test. A simplified, analytical method, which neglects this influence, gives a further underestimation of the fire resistance in relation to the corresponding result obtained in a standard fire resistance test.The described discrepancies between an analytical and an experimental determination of the fire resistance are further discussed and analysed in Sections 2 and 3, with particular reference to different types of steel structures. The discussion is focussed on the loading and restraint conditions, the scatter of material properties and geometrical imperfections, and the temperature variation over the structure or structural element. The discussion is summarized in Section 4 and alternative methods of correction are outlined briefly for obtaining an improved consistency between the analytical and the experimental approaches.In Section 5, one of these methods is further developed to a design basis which can be applied easily in practice. Principally, the method is characterized by a correction of the analytically determined load-bearing capacity, based on the characteristic value of the structural material properties, the characteristic value of the imperfections of the structure, and a uniformly distributed steel temperature across and along the structure. Two different sequences of the design procedure are dealt with, defined according to Figs. 10 and 11. The resultant correction factors, ? and κ, belonging to the respective sequences, are given by Figs. 8 and 12 for columns, isostatic beams, and hyperstatic beams. The straight line curves in Figs. 9 and 13 show corresponding, simplified relationships for the ? and κ factors.The derived method of correction must be characterized as an approximate approach. This is in consequence of the present state of knowledge, which does not allow a solution of high accuracy. The task to develop a correction procedure which leads to improved consistency between an analytically and an experimentally determined fire resistance, should also be seen in the context of the inadequate reproducibility of the standard fire resistance test.     

起火部位与火灾原因无关的一次短路分析

起火部位一次短路熔痕鉴定结论的证据审查是火灾原因认定中重要的环节.通过具体案例,对起火部位处与火灾原因无关的一次短路熔痕分特殊空间位置熔痕、陈旧性熔痕以及持续电源下的熔痕进行讨论,对其形成机理进行归纳总结,供火灾事故调查分析参考.     

高速列车起火车厢位置对火灾发展趋势的影响

运用FDS软件建立高速列车火灾模型,设置4种工况分析热释放速率及温度的变化,探究火源所在车厢位置对列车内火势发展的影响.结果表明:起火车厢位于列车前列时,车厢内发生的轰燃现象作用范围大、破坏力强,救援困难;随着起火车厢位置的后移,车内气流抑制轰燃现象的发生并有效稀释车厢内的可燃气体及热量,人员逃生可能性增大.     

火灾下防火装饰一体化钢梁抗火性能研究

为研究采用防火装饰一体化构造的钢梁在火灾下的温度场和承载力,通过基于ANSYS软件建立的分析模型对不同截面尺寸和不同耐火极限的钢梁进行抗火性能研究,并给出了计算钢梁承载力的简化公式,公式计算结果与有限元结果吻合情况较好.     

三面受火钢柱的抗火性能分析

应用ANSYS软件计算了钢柱在标准的升温模式下的温度场,分析了在三面受火作用下钢柱截面的温度变化情况。然后,利用ANSYS的耦合分析,将温度场导入结构分析中,进一步分析研究了在火灾下的钢柱截面温度分布对钢柱附加挠度的影响以及钢柱扭转变形发展规律,推导了由于温度效应引起的钢柱附加挠度的计算公式,为钢结构的抗火设计提供一定的参考价值。     

浅谈轻钢结构建筑的火灾危险性及对策

介绍了广泛应用于工业、民用的轻钢结构建筑的种类和特点,举例分析了钢结构建筑的火灾危险性和危害性及其在火灾中结构坍塌的原因,提出了增强轻钢结构建筑防火能力的对策.     

钢质防火门加强筋和铰链对耐火性能的影响

防火门耐火极限取决于其耐火隔热性和耐火完整性.钢质隔热防火门的耐火隔热性与门芯材料的导热系数和门扇厚度相关,而耐火完整性大都与防火门的结构设置相关.防火门的加强筋和铰链等结构设置不合理,会导致门扇变形过大,进而造成防火门耐火完整性的丧失.通过有限元方法对防火门耐火性能进行分析,并优化其加强筋和铰链的设置,可以降低防火门...