Steel Buildings in Europe

Part 7: Fire Engineering 7 - 8 as a general design tool; they would be required in compartments with complex geometries or with high and irregular ceilings. Conditions of use will be briefly detailed in Chapter 6. 3.3 Heat transfer analysis Once the thermal actions are calculated, the thermal transfer to the structural elements has to be calculated. Thermal models, which will be used, should be based on the acknowledged principles and assumptions of the theory of heat transfer. Different modelling can be used according to the assumptions and needs. In the thermal models, there are the analytical rules allowing obtaining an estimation of uniform temperature across-section, mainly for steel elements. There are also advanced calculation methods based on either finite elements or the finite difference method, allowing determination of the 2D or 3D temperature distribution in structural members (through the cross-section and along the length). Advanced models can be applied for any type of structural member analysis in fire design. Thermal models will be briefly detailed in following chapters. 3.4 Structural analysis From the temperature fields previously obtained in the structural members and from the combination of the mechanical actions loads in case of fire the structural behaviour can be assessed following one of the three possible approaches:  Member analysis, in which each member of the structure will be assessed by considering it fully separated from other members. The connection condition with other members will be replaced by appropriate boundary conditions.  Analysis of parts of the structure, in which a part of the structure will be directly taken into account in the assessment by using appropriate boundary conditions to reflect its links with other parts of the structure  Global structural analysis, in which the whole structure will be used in the assessment