# Update of eccentricity definition of a normal force for concrete columns according to Eurocode

When assessing compressed concrete columns you need to take into account the eccentricity of normal force according to Eurocode. There are several components of eccentricity:

- The
**first-order eccentricity** - The eccentricity due to
**geometrical imperfections** - The
**second-order****eccentricity**

A **total eccentricity** is equal to the summation of all of the above-mentioned components.

The national annexes of the Eurocode give different interpretations of the application of the minimum eccentricity defined in EN 1992-1-1 6.1 (4) for a cross-section subjected to a nominal force. In the version of IDEA StatiCa 21.1 and older, a minimum eccentricity corresponding to first-order effects was applied. Some of you may suggest that it leads to a conservative design and oversized cross-sections, while many national codes recommend applying e0 = h/30 or 20 mm for a total eccentricity, not just the eccentricity due to the first order.

That is why an update of the definition of an eccentricity for compressed concrete columns was implemented in the version of IDEA StatiCa 22.0. Now it is possible to choose which approach suits you the best.

A new part, the Application of the minimum eccentricity 6.1 (4) was added to the code settings in the RCS application. Here you can select how to define the minimum eccentricity:

- First-order eccentricity including geometrical imperfections (the same approach as it was in the IDEA StatiCa RCS 21.1 and older)
- Members subjected to normal force without bending
- Total eccentricity (the minimum eccentricity is compared to the total eccentricity)
- Application of the minimum eccentricity is not considered (this condition is off)

The default setting of the minimum eccentricity corresponds to a particular national annex. However, the user is able to change this setting if necessary.

An overview of the default settings of the minimum eccentricity for a particular national annex:

This update has been available since the version of IDEA StatiCa 22.0.

Available in all **Expert** and **Enhanced** editions of IDEA StatiCa Concrete and Prestressing.