Structural Fire Engineering
When designing a building, one of the essential aspects of the fire strategy is to ensure that a fire would not cause the structure of the building to collapse, endangering occupants and firefighters.
The conventional way to achieve this is to refer to the standard design codes such as Approved Document B (UK Building Regulations) or NFPA 101 (the main USA design standard that is also used extensively throughout the world). These documents include simple tables giving recommended fire resistance periods for the structure depending on the intended occupancy for the building (Office, retail etc) and the height of the building. That is a very simple basic approach, with very little specific reference to the actual building design, but there are large factors of safety built into these standard codes, so in practice, it will usually provide a safe building
However, in some cases it can end up with significant over-design of the amount of structural fire protection required. For example, tall office buildings often have a three storey high reception area at ground level. In that situation it would be very difficult for fire to affect the structure at ceiling level within that space. The fire load (i.e. the amount of combustible materials) within the reception would typically be very low, and as it is a three-storey high space, the structure would be so far above ground level that flames from any fire that might occur would be very unlikely to reach that high. So a detailed assessment of the structural fire protection requirement in that case would be likely to be able to jusify a significant cost saving.
Exova Warringtonfire can carry out analyses using a wide variety of structural fire engineering methods. The most appropriate method would be selected depending on the particular situation.
EQUIVALENT FIRE RESISTANCE CALCULATION - There are methods available to use the compartment size, fire load and ventilation sizes to determine the potential severity of a fire in terms of a period under the standard furnace fire.
PREDICTION OF FIRE CONDITIONS - Exova Warringtonfire have calcuation methods to predict the potential fire conditions that may occur in a fire within a particular space. From this, it is then possible to calculate the maximum temperature reached by the structure.
CALCUATION OF HEAT TRANSFER TO STRUCTURE - Exova Warringtonfire use a finite element software (SAFIR) to analyse heat transfer through materials such as concrete or fire protection boarding.
ASSESSMENT OF STRUCTURAL RESPONSE OF INDIVIDUAL ELEMENT - Once the maximum temperature of a structural member has been calculated we can then determine what strength it has remaining. From liaison with structural engineers, the response of the structure at these high temperatures can then be assessed.
WHOLE FRAME ANALYSIS - It has long been recognized that the fire performance of isolated structural members is different from that of whole striuctures. Exova Warringtonfire use a computer program called Vulcan that allows an experienced fire engineer to analyse the way that the whole frame would behave in a fire. The program can be used on any steel-framed building, but especially in buildings with floor slabs that are cast in-situ concrete or composite
Structural fire engineering can often lead to improved construction efficiency, operation and safety. Advanced methods can also provide a clear indication of structural behaviour in the event of a fire. The advantages of structural fire engineering can be summarized as:
