Workflow for fire design of steel members by the simple method

The internal forces are obtained from global analysis at ambient temperature. The forces are modified according to mechanical loading at elevated temperature, usually by reduction from the resistance limit state. The basic principles of steel structure fire design by simple elemental design are defined in Cl. 4.2 of EN 1993-1-2:2005.

How to calculate the fire resistance of a steel member using IDEA Statica?

1. Check the asked fire resistance period
   The national fire safety rules demand the asked fire resistance period for each type of structure.
2. Define your fire loading
   The action of the fire on the structure is represented by the thermal action for which EN 1991-1-2:2005 gives different possibilities. One of these possibilities consists of time-temperature relationships. Another possibility is heat flux to predict the temperature in the steel members. There are nominal temperature-time curves, parametric temperature-time curves, zone models, computational fluid dynamic (CFD) models and localized fires in order to represent the temperature of the fire compartment.
3. Calculate the temperature in your member
   It is possible to calculate the temperature in your member using Cl. 4.2.5 in EN 1993-1-2:2005 step-by-step procedure. The inputs for thermal analysis are the coefficient of heat transfer by convection (depends on fire curve), resultant emissivity (depends on steel type) and section factor (depends on cross-section and heating surface). The recommended time interval is 5 seconds for calculation. There is a simple equation provided by standard EN 1993-1-2:2005 to predict the temperature change in protected and unprotected steel members and it assumes an equivalent uniform temperature distribution throughout the cross-section.
4. Transfer your mechanical loads from global analyses
   The user should define the acting forces on the member in combinations based on Ch. 4 in EN 1991-1-2:2005 requirements. 
5. Calculate the resistance
   Finally, the software provides the fire resistance of steel member at the required temperature to users. The uniform temperature distribution is used in the model.