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What it calculates
- The degree of utilisation μ0 = Nfi,Ed · γM,fi / (A · fy) and the critical temperature from eq. (4.22).
- Steel heating under the ISO 834 curve, the hydrocarbon curve, the external fire curve or your own curve, with the shadow factor ksh.
- The time to reach the critical temperature and the fire resistance class achieved (R 15 to R 240).
- The protection thickness (sprays or boards) required for the target class.
Input data
- The section (I/H, CHS, SHS, RHS, round bar) and the steel grade.
- The tension force in the fire situation Nfi,Ed.
- The exposure, the fire curve and the protection.
Example
HEA 200 (HE 200 A) tie in S355, with a tension force of 600 kN in the fire situation, exposed on four sides, ISO 834 curve, γM,fi = 1.0.
| Quantity | Value |
|---|---|
| A | 53.83 cm² |
| μ0 = 600 / (53.83 · 35.5) | 0.314 |
| θa,cr | 656.9 °C |
| Unprotected (Am/V = 211.0 m−1, ksh = 0.618) | 16.5 min, class R 15 |
| Mineral fibre spray (λp = 0.12 W/mK, ρp = 300 kg/m³), for R 60 | 11.5 mm |
How it is calculated
A member in tension has no instability, so the critical temperature follows directly from the degree of utilisation, with the formula in the critical temperature guide. Steel heating follows eq. (4.25) for an unprotected member and eq. (4.27) for a protected one; see section factor and fire protection.
Information material summarising EN 1993-1-2. The results must be checked by a designer; they do not replace the text of the standard, the National Annex or verification by a qualified engineer.