Steel Buildings in Europe

Part 6: Fire Engineering 6 - 12 A comparative approach evaluates the level of fire safety obtained from performance-based design in relation to that from a prescriptive approach, to ensure an equivalent level of fire safety is achieved. A deterministic approach aims to quantify the effects of a worst case fire scenario and to demonstrate that the effects will not exceed the acceptance criteria defined. A probabilistic approach aims to show that the fire safety strategy makes the likelihood of large losses occurring sufficiently small. Establishing fire scenarios The number of possible fire scenarios in any building can become large and resources to analyse all of them are usually not available. Therefore detailed analysis must be confined to the most significant fire scenarios or the worst creditable case as it is sometimes referred to. The failure of protection systems should also be included in the fire scenarios considered. In most buildings more than one fire scenario will require detailed analysis. 2.3.3 Choice of optimum approach The choice of an optimum approach for the fire design of multi-storey buildings depends on various parameters, such as geometry, structural features, service function and designers’ knowledge of fire design. Table 2.4 provides some suggestions as to which approach may result in a more economic solution. Overall, for low-rise buildings with a small floor area, the pre-engineered datasheet approach may be the optimum choice. For high-rise buildings with a large floor area or to take into account the benefits of active protection measures, economic benefits may be obtained using advanced calculation models. For most medium size buildings, simple calculation models may result in the most economic solution. Table 2.4 Choice of optimum approach for fire engineering design Features of building Datasheets Simple calculation models Advanced calculation models 1 Building size - floor area per storey, A Small: A < 200 m 2  Medium: 200 m 2 < A < 2000 m 2  Large: A > 2000 m 2    2 Building height – number of storeys, n Low: n ≤ 5   High: n > 6     Most economic solution  Probably an economic solution The use of active fire protection measures, such as detectors, alarms or sprinklers, is beneficial if advanced calculation methods are used. It is noted