Concrete Column Checks

The module performs simplified checks according to the method with nominal curvatures in accordance with EN 1992-1-1, 5.8.8 for columns with circular and rectangular cross-sections. This method replaces the normal bending design if normal compressive forces act on them and effects from second-order theory must be taken into account. Based on the defined buckling length and curvature, nominal moments are calculated separately for each direction according to second-order theory. Together with the moments according to first-order theory, taking imperfections into account, a bending design is carried out for the total moments.

In case of fire, the design is performed according to the simplified calculation method in accordance with EN 1992-1-2, Chapter 4.2, using the zone method.

In this example, the gable column shown by Richter (Fire Protection Design in Solid Construction, 2007) is verified using the simplified calculation method with the zone method according to EN 1992-1-2, Annex B.2.

The cross-section damaged by fire is reduced by a zone of thickness a_z. With this reduced cross-section and the reduced strengths for the remaining concrete and reinforcing steel, a column design is then carried out using the method with nominal curvatures.

The column consists of C30/37 and is fixed at the base. The dimensions and reinforcement arrangement can be seen in the figure.

For simplicity, the same stress is applied for both the design under normal temperature conditions and for the fire scenario. The cross-section is assumed to be exposed to fire on three sides (fire duration T = 90 min.).

Buckling is only examined in the image plane with a buckling length equal to twice the column length (2 · 9.55 m = 19.1 m).

The figure shows the relevant internal forces and the determined reinforcing steel.