Fire protection design by means of the analytical method for steel, reinforced concrete and aluminum structures with the FireSafe module

The analytical method as described by the Fire Prevention codes makes explicit reference to the Eurocode for the analysis of sections with different materials.
The FireSafe module implements the thermal analysis of the sections of any material, and with particular automatism for:

ü reinforced concrete sections;

ü aluminum steel sections.

The fire protection design against R (Resistance) requirement for structures therefore takes place in two phases: the estimation of the resistant capacity of the element (beam, pillar, etc.) in the existing configuration, which is carried out automatically by the program through sectional checks, and checks on the entire element.

The second set of tests is of fundamental importance, since an element should withstand the forces of design in section, but not exceed for example the Eulerian stability at the element level.

In the event that the first phase does not involve the complete verification of the analyzed elements, these can be recalculated to the fire including a protective (for example plasterboard, calcium silicate panels, intumescent paints, etc.) in order to lower the temperature of the section subject to thermal analysis for the design time (eg t_final=90 minutes) thanks to the insulating layer, and thus decrease the degradation of the mechanical parameters associated with the structural part.

The first phase is extensively described by the articles linked above, for each type of structural material.

The second is supported starting from the new version 2.1 of NextFEM Designer, which allows you to apply the protective layer, of a material chosen from the new library included with the program, to the desired section.

To select a non-structural covering material, first select Assign / Design Materials and choose the "Fire Protection" library. Last but not least, it is possible to start thermal analysis both with the standard fire curve (ISO 834) and with the external fire and hydrocarbon curves.

Then, from the Edit / Sections mask, apply the coating with the command right button / Section Cover, specifying the thickness when required.

The thermal analysis conducted for that section will include the added protective layer, as in the next figure. At the same time, the non-structural coating layer has no effect in the structural analyses carried out in the main model. The layer of protective material will be taken for all elements having that section, for which the exposure to fire set in the mask "Fire verification" will be uniform for their length.

The sectional verification will therefore report an increase in resistance compared to the bare section. In the section, the coating part is not reacting for the purpose of calculating the strength.

With the FireSafe module it is therefore possible to manage in a fully automated way the fire design of structures, both new and existing, using analytical method and non-linear thermal analysis of sections.