Answer:
The stability analysis for plate structures can be converted into a pure stress analysis if the calculation is performed according to the second-order analysis and the imperfection required by the standard has been applied to the structure.
Using the RF‑STABILITY and RF‑IMP add-on modules, you can create imperfections (or a predeformed FE mesh). The type of imperfection depends strongly on the structural component and the corresponding standard. For members that have been modeled as a plate structure, you can use the values from DIN EN 1993‑1‑1:2005 5.3. For planar surfaces, you can use For example, you can use the values from DIN EN 1993-1-5:2006, Annex C. For shells, the problem is much more complex and there are different approaches. I would advise against the generation of imperfections and perform the plate buckling design using the MNA/LBA concept according to DIN EN 1993‑1‑6, which does not require the application of an imperfection.
Wenn beispielsweise das Flächenmodell eines Stahlträgers nachgewiesen werden soll, können Sie z. B. wie folgt vorgehen:
- Select a load with relatively high axial forces (compared to other internal forces in the load case), in most cases you can use the self-weight load case or a load combination with the corresponding self-weight. It may be necessary for each load combination to have an individual imperfection.
- Lastkombination nach Theorie 1er Ordnung berechnen und als Grundlage für RF-STABIL verwenden.
- Mit Hilfe von RF-STABIL die erste Eigenform eines globalen Versagens finden.
- Use the calculated mode shape as a basis for an imperfection using RF‑IMP. It is possible to apply 1/300 of the beam length as an amplitude, for example.
- Create a load case combination that uses the created imperfection as a basis and is calculated according to the second-order analysis.
- Perform a stress analysis using this load combination, which is also the stability analysis of the structure.
