Steel Buildings in Europe

Part 7: Fire Engineering 7 - 6 3 PRACTICAL FIRE ENGINEERING OPTIONS IN THE EUROCODES 3.1 Current design approaches Using the fire parts of Eurocodes [8,9] , single-storey buildings can be designed using either the prescriptive approach or the performance-based approach applying fire safety engineering principles [10] . The prescriptive approach is mostly applied to fulfil standard fire resistance requirements usually prescribed in national fire regulations. It gives a safety level that is relatively easy to achieve and implement. However it may be conservative, in requiring the use of important passive fire protection to fulfil the required fire resistance rating. This approach is usually carried out for the design of relatively simple buildings and structures. As an alternative or when allowed by national regulation, the performance- based approach can allow to assess adequate measures to satisfy a set-out of defined fire safety objectives, such as stated in paragraph 2.1, and the corresponding performance criteria. Using structural fire engineering, engineers can assess the necessary fire resistance to structure in order to avoid the spread of fire and/or to prevent a premature structural collapse. As regards the single-storey buildings, the main structure could be designed to remain stable under fire exposure conditions long enough for the occupants to escape. Such an approach takes into account the severity of fire exposure by appropriate estimations of actual fire loads and fire development parameters, which may be calculated from the building activity. The performance-based approach provides flexibility when selecting technical solutions to meet the fire safety objectives, but usually requires the use of sophisticated design tools. Engineers and designers using advanced calculations models need to be properly educated in their use and in their limitations. As fire safety engineering allows for highly efficient designs, with little unassigned reserve capacity, an experienced user is required to ensure that appropriate models are used. Where national fire regulations authorise the performance-based approach, regulatory bodies may require that the fire design is checked by a third party. The fire performance of a whole structure, or a part of it, is carried out by following, for a given design fire scenario, three successive steps of structural fire engineering [1] .  Fire Analysis. To calculate the thermal actions/exposure - Fire models.  Thermal analysis. To determinate the heating rate and temperatures on structural members - Thermal models.  Structural analysis. To calculate the mechanical response of structural members- Structural models.