Designing Against Fire Of BulidingWord下载.docx

1、This paper considers the design of buildings for fire safety. 这篇论文研究的是建筑防火，It is found that fire and the associ- ated effects on buildings is significantly different to other forms of loading such as gravity live loads , wind and earthquakes and their respective effects on the building structure. 火作

2、用在建筑上与重力荷载，风荷载以及地震力对建筑结构的作用有很大的不同。Fire events are derived from the human activities within buildings or from the malfunction of mechanical and electrical equipment provided within buildings to achieve a serviceable environment. 火是由于建筑内的人类活动或者机械鼓掌，建筑内的电器引起It is therefore possible to directly influenc

3、e the rate of fire starts within buildings by changing human behaviour, improved maintenance and improved design of mechanical and electrical systems. Furthermore, should a fire develops, it is possible to directly influence the resulting fire severity by the incorporation of fire safety systems suc

4、h as sprinklers and to provide measures within the building to enable safer egress from the building. The ability to influence the rate of fire starts and the resulting fire severity is unique to the consideration of fire within buildings since other loads such as wind and earthquakes are directly a

5、 function of nature. The possible approaches for designing a building for fire safety are presented using an example of a multi-storey building constructed over a railway line. The design of both the transfer structure supporting the building over the railway and the levels above the transfer struct

6、ure are considered in the context of current regulatory requirements. The principles and assumptions associ- ated with various approaches are discussed.1 INTRODUCTIONOther papers presented in this series consider the design of buildings for gravity loads, wind and earthquakes.对比于其他研究重力荷载，风荷载和地震力对建筑的

7、影响，The design of buildings against such load effects is to a large extent covered by engineering based standards referenced by the building regulations. 建筑物针对这些负载设计很大程度上涵盖了建筑法规的工程设计标准。This is not the case, to nearly the same extent, in the case of fire. 万一发生火灾，事实并非如此。Rather, it is building regulatio

8、ns such as the Building Code of Australia （BCA） that directly specify most of the requirements for fire safety of buildings with reference being made to Standards such as AS3600 or AS4100 for methods for determining the fire resistance of structural elements.相反，澳大利亚建筑法中明确规定了建筑防火的安全标准，比如用AS3600或者AS41

9、00的方法来确定结构构件的耐火程度。The purpose of this paper is to consider the design of buildings for fire safety from an engineering perspective （as is currently done for other loads such as wind or earthquakes）, 这篇论文研究的目的是从工程的角度去考虑建筑的防火设计（和现在所做的风作用力和地震作用力一样），whilst at the same time,putting such approaches in the

10、 context of the current regulatory requirements.于此同时把这类方法应用到现行的规范要求中。At the outset,it needs to be noted that designing a building for fire safety is far more than simply considering the building structure and whether it has sufficient structural adequacy.首当其冲需要注意的是设计一幢防火的大楼仅仅简单考虑建筑结构或是否有足够的结构性是远远不够的

11、，This is because fires can have a direct influence on occupants via smoke and heat and can grow in size and severity unlike other effects imposed on the building. 这是因为火不像其他因素它能通过烟雾和热量直接影响住户并且可以扩散从而增加其严重性。Not withstanding these comments, the focus of this paper will be largely on design issues associ

12、ated with the building structure.不只是这些论点，这篇文章的主旨将集中在建筑结构的设计问题。Two situations associated with a building are used for the purpose of discussion. 本篇文章选用一栋大楼的两种情况来讨论，The multi-storey office building shown in Figure 1 is supported by a transfer structure that spans over a set of railway tracks. 图1所示一栋多层

13、办公楼用转换结构跨过了一条铁路，It is assumed that a wide range of rail traffic utilises these tracks including freight and diesel locomotives. 这是假定了广泛轨道交通作用在这些轨道上同时考虑了运费和内燃机。The first situation to be considered from a fire safety perspective is the transfer structure.第一种情况从防火安全考虑，就是转换结构。This is termed Situation 1

14、and the key questions are:这就是情况1，主要的问题是： what level of fire resistance is required for this transfer structure and how can this be determined?哪种等级的防火需要用这种转换情况以及怎样去确定它？ This situation has been chosen since it clearly falls outside the normal regulatory scope of most building regulations.它显然不属于大多数建设法规

15、的监管范围，所以已经被确定。An engineering solution, rather than a prescriptive one is required. 我们需要的是工程解决办法而不是指令性的。The second fire situation （termed Situation 2） corresponds to a fire within the office levels of the building and is covered by building regulations. 第二种情形（称为情况2）相应的建筑官方等级This situation is chosen b

16、ecause it will enable a discussion of engineering approaches and how these interface with the building regulationssince both engineering and prescriptive solutions are possible.选择这种情况是因为它可以讨论工程学方法以及怎样和建设法规相接，因为工程和指令问题都能解决。2 UNIQUENESS OF FIRE火的独特性2.1 Introduction2.1 介绍Wind and earthquakes can be con

17、sidered to be “natural” phenomena over which designers have no control except perhaps to choose the location of buildings more carefully on the basis of historical records and to design building to resist sufficiently high loads or accelerations for the particular location. 设计师不能控制被认为是“自然”现象的风和地震，只能

18、通过历史记载更加仔细去选择建筑物的位置或者提高建筑物的承受强大荷载能力。Dead and live loads in buildings are the result of gravity. 建筑物静荷载和或荷载都是是由重力产生的，All of these loads are variable and it is possible （although generally unlikely） that the loads may exceed the resistance of the critical structural members resulting in structural fai

19、lure.所有的这些荷载是可变荷载并且有可能（尽管不常见）通过关键构件的阻力造成结构性的破坏。The nature and influence of fires in buildings are quite different to those associated with other“loads” to which a building may be subjected to. 火灾的性质以及其对建筑的影响与其他荷载存在很大的不同。The essential differences are described in the following sections.这些关键不同点将在接下来的章

20、节作描述。2.2 Origin of Fire2.2 火灾的源头In most situations （ignoring bush fires）, 在多数情况下（排除丛林大火），fire originates from human activities within the building or the malfunction of equipment placed within the building to provide a serviceable environment. 火灾源头来自在建筑内的人类活动或内部的装置的设备故障提供的环境。It follows therefore tha

21、t it is possible to influence the rate of fire starts by influencing human behaviour, 可以通过约束人的活动来影响起火的发生率，limiting and monitoring human behaviour and improving the design of equipment and its maintenance. 限制和监视人类行为和改进设备及其维护保养。This is not the case for the usual loads applied to a building.而建筑物的正常荷载不用

22、这么做。2.3 Ability to Influence2.3 影响能力Since wind and earthquake are directly functions of nature,因为风和地震是自然直接作用，it is not possible to influence such events to any extent.人类不可能对他们的活动产生很大影响，One has to anticipate them and design accordingly.仅仅能预测和以此设计。It may be possible to influence the level of live load

23、 in a building by conducting audits and placing restrictions on contents.可以通过审计和限制容积来影响建筑活荷载等级。However, in the case of a fire start,然而在火灾发生之初， there are many factors that can be brought to bear to influence the ultimate size of the fire and its effect within the building.可以通过很多因素来影响火灾的最终规模和火灾对建筑的影响程

24、度。It is known that occupants within a building will often detect a fire and deal with it before it reaches a sig- nificant size.大家都知道建筑物里的住户经常会在火蔓延到更大的范围前将它扑灭。It is estimated that less than one fire in five （Favre, 1996） results in a call to the fire brigade and for fires reported to the fire brigad

25、e, 据估计不到五分之一的火灾需要报警，the majority will be limited to the room of fire origin.大多数都在火灾源头的房间得到了控制。 In occupied spaces, olfactory cues （smell） provide powerful evidence of the presence of even a small fire. 在封闭的空间里，对火花的嗅觉（味道）可以为火灾的发生提供强有力有理的证据。The addition of a functional smoke detection system will furt

26、her improve the likelihood of detection and of action being taken by the occupants.烟雾监测系统的安装将更进一步提高火灾监测的可能性从而住户可以第一时间采取行动。Fire fighting equipment, such as extinguishers and hose reels, is generally provided within buildings for the use of occupants and many organisations provide training for staff i

27、n respect of the use of such equipment.在建筑物内都有供用户使用的消防设备，如灭火器，消防栓等，也有很多机构提供如何使用这些消防设备的训练。The growth of a fire can also be limited by automatic extinguishing systems such as sprinklers, which can be designed to have high levels of effectiveness.自动灭系统也可以限制火灾的蔓延，如自动喷水系统有很高的效率。Fires can also be limited

28、by the fire brigade depending on the size and location of the fire at the time of arrival.火灾也可以由消防队员控制，依据火灾发生大小，位置和到达时间来确定。2.4 Effects of Fire2.4 火灾的影响The structural elements in the vicinity of the fire will experience the effects of heat. 火对建筑材料的影响是火周围热效应的结果。The temperatures within the structural e

29、lements will increase with time of exposure to the fire, 建筑材料的温度会随着火灾时间的增长而升高，the rate of temperature rise being dictated by the thermal resistance of the structural element and the severity of the fire. 建筑材料温度升高快慢程度取决于隔热材料和火势大小。The increase in temperatures within a member will result in both therma

30、l expansion and,eventually,a reduction in the structural resistance of the member. 随着温度的升高，材料会热膨胀从而导致整个结构破坏。Differential thermal expansion will lead to bowing of a member.不同程度的热膨胀会导致材料变形，Significant axial expansion will be accommodated in steel members by either overall or local buckling or yielding

31、 of local- ised regions. 无论是整体或局部弯曲变形部位，重大轴向扩张被安装在钢材料上。These effects will be detrimental for columns but for beams forming part of a floor system may assist in the development of other load resisting mechanisms （see Section 4.3.5）.这些作用将会对柱产生破坏影响，但是组成楼面部分的横梁可以发展产生其他的负荷抵御机制（见章节4.3.5）。With the exceptio

32、n of the development of forces due to restraint of thermal expansion, 力量的发展归咎于fire does not impose loads on the structure but rather reduces stiffness and strength.火灾不会增加结构荷载而是降低它的硬度和刚度，Such effects are not instantaneous but are a function of time and this is different to the effects of loads such as earthquake and wind that are more or less instantaneous.不同与像地震和风这类短时间作用的荷载，火灾的作用效果不是瞬间的，而是一个长时间的作用。Heating effects associated with a fire will not be significant or the rate of loss of capacity will be slowed if:在下列情况下，火灾的热作用不显著或者蔓延速度变慢：（a） t