Eurocode - steel member fire data calculation
In the 2025 release, we have introduced two new fire design related features, Ambient temperature utilization (at t = 0 seconds of the Fire Limit State) and Fire UDAs.
Ambient temperature utilization
This new feature enables the calculation of critical design values under fire conditions which can be used for the assessment of fire protection requirements. The scope of this release captures values from non-composite steel beam design (assumed restrained for lateral torsional buckling) and steel column design which are essential for the calculation of fire protection.
The ambient temperature calculations can be included in the design checks by selecting Ambient temperature utilization located under Fire proofing in non-composite steel beam and steel column properties.
When this option is enabled the
calculation of the ambient temperature utilization at fire limit state is carried out for
the relevant phenomena depending on the selected member type and considering:
- The load reduction factor prescribed in EN 1993-1-2 Clause 2.4.2 applied to the actions,
- The guidance for resistance under fire in EN 1993-1-2 Clause 4.2
Note: The load reduction factor is
calculated based on the permanent and imposed loading applied to the model and their
respective combination factors. Most notably, the load effect used to calculate this
factor is the total shear in the major direction for beams and the axial load for
columns. The former assumes that a beam is dominated by major axis bending and has
little or no axial force. The latter assumes that a column is dominated by axial force
with little or no moment.
The critical ratio is then reported in the design summary table.
Fire UDAs
The following UDAs can now be added to steel member properties by selecting Populate UDAs on the Design ribbon.
- Exposure
- Nominal fire exposure
- Ambient UR (u0)
- Load reduction factor (nfi)
- Critical temperature
- Imposed loading category
Depending on the selections made under
'Fire Proofing' in the member properties the actual UDA values will also be populated for
non-composite steel beams and steel columns as follows:
- If Ambient temperature utilization is selected, Ambient UR (u0), Load reduction factor (nfi) and Imposed loading category UDAs are populated.
- If Protected is selected, the Exposure UDA is populated.
- For non-composite steel beams only, if Check for fire resistance is selected, the Nominal fire exposure and Critical temperature UDAs are populated.
When the Fire UDAs are used alongside the Enhanced transfer of UDAs between Tekla Structural Designer and Tekla Structures feature, a new workflow for fire data to flow between Tekla Structural Designer and Tekla Structures becomes available.