Structural Fire Engineering deals with specific aspects of passive fire protection in terms of analysing the thermal effects of fires on buildings and designing structural members for adequate load bearing resistance, i.e. the structural fire resistance.

The well known practices include the provisions of fire protection systems to steel members and additional concrete cover to reinforced concrete members.

In fact, SFE covers a wide range of levels of knowledge and competence. A generic SFE analysis and design shall involve fire modelling, thermal analysis and structural analysis. However, the theory and procedures for analysing structural behaviour under fire conditions is much complex compared to those for structural analysis and design at normal temperatures. Simplified approaches become an important option to most practitioners. For convenience, the procedure of SFE analysis and design can be divided into three levels of complexity.

The simplest procedure is given in most conventional building codes. Generally, building codes specify the fire resistance required for structural members and classification of construction based on the results of standard fire tests. Information on member dimensions and construction details with respect to fire resistance ratings is provided. The key feature is to keep the structural members “cool” from the heat of fires. The designers need only apply specified construction features to satisfy the code requirements, and require little or no knowledge of fire and structural engineering. This procedure is prescriptive-based.

Steel beam and column protected by concrete

The second procedure involves the calculation of structural fire resistance based on the empirical or theoretical relationships. Basically, the mechanical properties of the structural materials at elevated temperatures are incorporated into the traditional structural theory to develop a rational analytical procedure for predicting structural behaviour under fire conditions. This procedure, in a manner analogous to design at normal temperatures, is performance-based and provides more flexibility to designers.

The third procedure involves the assessment of three basic aspects comprising the likely fire behaviour, heat transfer to the structure and the structural response. The overall complexity of the procedure depends on the assumptions and analytical methods adopted to predict each of the three design aspects. Although this procedure normally needs to be performed by experienced structural engineers with the help of professional computer programs, it provides a platform for innovative design and construction features.

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