For the final calculation, you should activate the "Steel Design" add-on in the Base Data, which allows you to carry out the design directly in RFEM. Furthermore, make sure that you have selected the combination wizard that performs the calculation according to the second-order analysis, taking into account the imperfections.
Since the section proof replaces the stability design, it is mandatory according to the German National Annex to use the partial safety factor γM1.
The setting of whether to use γM0 or γM1 is specified in the Ultimate Configuration.
In the "Steel Design" table category, open the "Ultimate Configuration" tab. You can create a new configuration by double-clicking in a table row. Deactivate the stability analysis there and activate the utilization of γM1.
You can use the
button to assign the ultimate configuration to the individual objects, such as the stair stringer.