Steel Buildings in Europe

Part 6: Fire Engineering 6 - 8 EN 1993-1-2 provides a table of critical temperature data expressed in terms of the degree of utilisation. Data for the design of a range of steel concrete composite beams and columns is also provided in tabular format in EN 1994-1-2. Product-specific tabular data is commonly available for fire protection materials that can be applied to structural steelwork. The required thickness of fire protection is usually expressed as a function of fire resistance period, section factor and critical temperature. Many other building products, such as steel decking for composite floors, also come with product specific design tables. Simple calculation models As an alternative to tabular data, the designer may choose to carry out simple calculations to determine the resistance of a member after a given period of fire exposure. The fire action is taken as the standard temperature-time curve in the Eurocodes. The resistance of the member depends on the level of applied load and loss of material strength under fire conditions, and is calculated according to the Eurocode rules. Simple calculation models are most practical when used to justify the design of unprotected steelwork, usually in circumstances where the fire resistance requirement is R30 or lower. Where protected steelwork is required normal tabular data provided by fire protection manufacturers is more efficient. The disadvantage of these calculation models is that their application is limited to individual structural members and does not allow for the interaction between the structural member and the surrounding structure. Advanced calculation models Advanced calculation models use both engineering fundamentals and finite element techniques to carry out structural fire design. Thermal and structural responses to fire actions may be determined using advanced physical models. This type of analysis normally leads to a more economic solution than both the prescriptive approach and the simple calculation models. This method helps designers to develop more innovative solutions for building structures and it often proves that it is safe to leave some steel members unprotected without compromising the fire resistance of the structure. Advanced calculation models demand a considerable amount of calculations to be carried out and require significant expertise from the designer in terms of structural fire engineering and finite element techniques. Classification of lining materials National regulations impose controls on the materials used as lining for the walls and ceilings of buildings. These materials must resist the spread of flames across the surfaces and must not contribute significantly to the fire in terms of heat release or smoke production. Lining materials are categorised on the basis of the result of reaction to fire tests.