Steel Buildings in Europe

Part 6: Fire Engineering 6 - 5 2.3 Approaches to structural fire engineering Structural fire engineering design can be carried out using a prescriptive approach, where periods of fire resistance are defined by national regulations, or a performance-based approach, where the designer must quantify the level of risk and demonstrate that it is acceptable. It should be noted that the acceptance of a performance-based approach is dependant on national regulatory authority, who should be consulted at an early stage of the design process. Table 2.1 provides a summary of the tools available for use when adopting either of these approaches. Table 2.1 Approaches for fire design Approach Tools Fire loads (Thermal actions) Fire effects (Member temperature) Fire resistance (Member resistance) Pre- engineered datasheets Standard ISO fire tests to:  EN 1363-1, § 5  EN 1365-2, § 5 Relevant information covered in:  information packages provided by fire protection manufacturers  documents published in Access-Steel  EN 1994-1-2, § 4.2 Steel members to EN 1993-1-2 § 4.2.5 § 4.2.3 § 4.2.4 Composite members to EN 1994-1-2 Simple rules & models Standard ISO fire calculations to EN 1991-1-2, §3.2 Annex D2, § 4.3.4.2.2 Annex E – F, § 4.3.1 § 4.3.4.2.4 § 4.3.4.2.3 Prescriptive approach (standard fire methods) Advanced rules & models Physical models for heat transfer Finite element analysis Physical models for structural response Finite element analysis Steel members to EN 1993-1-2 Simple rules & models Parametric fire Localised fire § 4.2.5 § 4.2.3 § 4.2.4 Consider interaction between structural members and tensile membrane action. Performance- based approach (natural fire methods) Advanced rules & models Natural fire to EN 1991-1-2, § 3.3 Annex A to F Localised, zones, CFD Physical models for heat transfer Finite element analysis Physical models for structural response Finite element analysis 2.3.1 Prescriptive Approach The prescriptive approach is the traditional and still most commonly used method for fire engineering design. It aims solely to provide adequate levels of life safety to meet the fire resistance requirements specified in the national building regulations. Prescriptive regulations will contain requirements that aim to satisfy the core objectives for fire safety set out in Section 2.2. Structural fire resistance Prescriptive regulations require that buildings are subdivided by fire resisting construction. The requirements typically give limits for the maximum size of a single compartment and recommend fire resistance requirements for the