How to generate EC3 global imperfections on columns

written by Gérald Kota Miquel Fausther

Eurocode 3 (EC3) is the European standard for common structural steel design rules. EC3 standards are used for designing buildings and civil engineering works in steel.

According to EC3, in some cases it is necessary to take into account global imperfections in order to consider possible defects in the plumb of columns during the execution phase of a project.

What the EC3 standard says

The initial geometric defects of columns will result in the application of equivalent horizontal forces on the columns.

EN1993-1-1 §5.3.2 fig5.4

A horizontal force at the head φNed (along the local y or z axis) to simulate the inclination of the post and an opposite force at the foot, so the load applied at the head has no effect on the descent of the load. The value of φ is given by EC3.

Application in Advance Design

Considering EC3 global imperfections on columns in Advance Design is performed in two main steps.

1. The calculation must be activated in the metal hypotheses.

2.  It is then necessary to activate and configure this calculation in the property sheet of the columns.

At the end of the metal expert calculation, the global imperfection forces on the columns are automatically generated in accordance with EC3 and are added to the ultimate limit state (ULS) combinations.

The ULS analysis checks to see if a structure has the capacity to withstand the design load.

In this way, we obtain ULS combinations with the global imperfection forces in one direction (ULS +/- imperfection), in addition to the basic ULS combinations.

If you’re interested in learning more about structural FEA/FEM using Advance Design, contact Graitec Group today and talk to an industry expert.

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