Answer:
In RFEM 5 and RSTAB 8, it is possible to define the effective length factors that are then applied in the add-on modules.
If the aforementioned message appears, the entry for the coefficients was set to 0 in an old version. Due to this incomplete member definition, calculation in the main program is not possible. To fix this, enter a value > 0.
If the effective length factors are still not relevant for the design, you can select the entire model and then open the "Edit Member" dialog box by double-clicking the member. Then, set the factors to the default value of 1.0 in the "Effective Lengths" tab.
