In the Steel Joints add-on, you can determine the initial stiffness Sj,ini according to Eurocode and AISC. This can be done for the selected members with reference to the internal forces N, My, and Mz.
In the Members tab of the input dialog box of the Steel Joints add-on, you can select the desired internal forces via a checkbox. Multiple selection is possible! For these internal forces, the stiffness analysis is carried out with a positive and a negative sign.