Temperature in the concrete
According to DS-EN 1992-1-2 (Danish annex to EN1992-1-2), Annex B2.
Modeling fire exposure for a cross-section entails treating the cross-section as being reduced, meaning the original concrete cross-section is reduced by a damaged zone at the exposed sides. The temperature in a reduced rectangular cross-section θM depends on the fire exposed sides as shown in the table below.
| δT+δB+δL+δR | δT+δB | δL+δR | θM |
|---|---|---|---|
| 1 | 1 | 0 | θ2,2h(0,t) |
| 0 | 1 | θ2,2b(0,t) | |
| 2 | 2 | 0 | θ2,h(0,t) |
| 0 | 2 | θ2,b(0,t) | |
| 1 | 1 | θ2,2z(0,t) | |
| 3 | 2 | 1 | θ2,z(0,t) |
| 1 | 2 | θ2,z(0,t) | |
| 4 | 2 | 2 | θ2,z(0,t) |
For a cross-section with flanges, we determine temperature θM for both the body and the flanges. The cross-section is divided during the calculation according to Section properties, into a body of width b (body width) and height h (original cross-section height) and a flange with width bf and height hf.
For cross-section with variable width or height of flange, we use the value in the middle of the cross-section. For a circular cross-section, the temperature in the reduced cross-section is
