- 1 -
中英文对照外文翻译
(文档含英文原文和中文翻译)
外文文献外文文献: :
贫血的食补方法Designing Against Fire Of Buliding
ABSTRACT:
This paper considers the design of buildings for fire safety. 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. 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 rviceable environment. It is therefore possible to directly influence 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 verity by the incorporation of fire safety systems such 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 verity is unique to the consideration of fire within buildings since other loads such as wind and earthquakes are directly a function of nature. The possible approaches for designing a building for fire safety are prented 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 structure are considered
in the context of current regulatory requirements. The principles and assumptions associ- ated with various approaches are discusd.
根号的运算1 INTRODUCTION
Other papers prented in this ries consider the design of buildings for gravity loads, wind and earthquakes.The design of buildings against such load effects is to a large extent covered by engineering bad standards referenced by the building regulations. This is not the ca, to nearly the same extent, in the ca of fire. Rather, it is building regulations such as the Building Code of Au
stralia (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.
The purpo 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), whilst at the same time,putting such approaches in the context of the current regulatory requirements.At the outt,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.This is becau fires can have a direct influence on occupants via smoke and heat and can grow in size and verity unlike other effects impod on the building. Notwithstanding the comments, the focus of this paper will be largely on design issues associated with the building structure.
Two situations associated with a building are ud for the purpo of discussion. The multi-storey office building shown in Figure 1 is supported by a transfer structure that spans over a t of railway tracks. It is assumed that a wide range of rail traffic utilis the tracks including freight and diel locomotives. The first situation to be considered from a fire safety perspective is the transfer structure.This is termed Situation 1 and the key questions are: what level of fire resistance is require
d for this transfer structure and how can this be determined? This situation has been chon since it clearly falls outside the normal regulatory scope of most build-
ing regulations. An engineering solution, rather than a prescriptive one is required. The cond fire situation (termed Situation 2) corresponds to a fire within the office levels of the building and is covered by building regulations. This situation is chon becau it will enable a discussion of engineering approaches and how the interface with the building regulations regulations––since both engineering and prescriptive solutions are possible.
2 UNIQUENESS OF FIRE
卡农d大调2.1 Introduction Wind and earthquakes can be considered to b Wind and earthquakes can be considered to be “natural” phenomena o e “natural” phenomena o e “natural” phenomena over which designers ver which designers have no control except perhaps to choo 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. Dead and live loads in buildings are the result of gravity. All of the 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 failure.
The nature and influence of fires in buildings are quite different to tho associated with other“loads” to which a building may be subjected to. The esntial differences are described in the following ctions.
2.2 Origin of Fire
In most situations (ignoring bush fires), fire originates from human activities within the building or the malfunction of equipment placed within the building to provide a rviceable environment. It follows therefore that it is possible to influence the rate of fire starts by influencing human behaviour, limiting and monitoring human behaviour and improving the design of equipment and its maintenance. This is not the ca for the usual loads applied to a building.
2.3 Ability to Influence
Since wind and earthquake are directly functions of nature, it is not possible to influence such events to any extent. One has to anticipate them and design accordingly. It may be possible
to influence the level of live load in a building by conducting audits and placing restrictions on contents. However, in the ca of a fire start, there are many factors that can be brought to bear to in
fluence the ultimate size of the fire and its effect within the building. It is known that occupants within a building will often detect a fire and deal with it before it reaches a sig- nificant size. 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 brigade, the majority will be limited to the room of fire origin. In帝都泱泱
土字旁的字oc- cupied spaces, olfactory cues (smell) provide powerful evidence of the prence of even a small fire. The addition of a functional smoke detection system will further improve the likelihood of detection and of action being taken by the occupants.
Fire fighting equipment, such as extinguishers and ho reels, is generally provided within buildings for the u of occupants and many organisations provide training for staff in respect of北京马拉松
煤气爆炸the u of such equipment.
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.Fires can also be limited by the fire brigade depending on the size and location of the fire at the time of arrival.
2.4 Effects of Fire
The structural elements in the vicinity of the fire will experience the effects of heat. The temperatures within the structural elements will increa with time of exposure to the fire, the rate of temperature ri being dictated by the thermal resistance of the structural element and the verity of the fire. The increa in temperatures within a member will result in both thermal expansion and,eventually,a reduction in the structural resistance of the member. Differential thermal expansion will lead to bowing of a member. Significant axial expansion will
be accommodated in steel members by either overall or local buckling or yielding of local- id regions. The 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 (e Section 4.3.5).
With the exception of the development of forces due to restraint of thermal expansion, fire does not impo loads on the structure but rather reduces stiffness and strength. 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.
Heating effects associated with a fire will not be significant or the rate of loss of capacity will be slowed if:
(a) the fire is extinguished (e.g. an effective sprinkler system)
(b) the fire is of insufficient verity –– insufficient fuel, and/or
(b) the fire is of insufficient verity
(c)the structural elements have sufficient thermal mass and/or insulation to slow the ri in internal temperature
Fire protection measures such as providing sufficient axis distance and dimensions for concrete elements, and sufficient insulation thickness for steel elements are examples of (c). The are illustrated in Figure 2.
The two situations described in the introduction are now considered.
3 FIRE WITHIN BUILDINGS
3.1 Fire Safety Considerations
The implications of fire within the occupied parts of the office building (Figure 1) (Situation 2) are no
w considered. Fire statistics for office buildings show that about one fatality is expected in an office building for every 1000 fires reported to the fire brigade. This is an order
of magnitude less than the fatality rate associated with apartment buildings. More than two thirds
of fires occur during occupied hours and this is due to the greater human activity and the greater u of rvices within the building. It is twice as likely that a fire that commences out of normal working hours will extend beyond the enclosure of fire origin.
A relatively small fire can generate large quantities of smoke within the floor of fire origin.
>组织生活会与民主生活会的区别
