Using the “Buckling Mode” imperfection type and the “Automatic” source type, you can have RFEM and RSTAB automatically determine geometric equivalent imperfections. This is based on the mode shapes calculated using the Structure Stability add-on. The initial bow can be specified as a relative value or based on EN 1993-1-1.
RFEM/RSTAB determine the load combinations in two consecutive steps: First, the structural analysis and linear stability are performed, and the magnitude of the imperfection is determined for each governing stability mode. Next, the combination is calculated using the derived geometric equivalent imperfections in both the positive and negative directions for each stability mode.
This provides you with standard-compliant results based directly on the model’s actual buckling and mode shapes, without the need to determine the imperfection values yourself.
