When determining the effective cross-section properties according to EN 1993‑1‑1, EN 1993‑1‑5, or EN 1999̩1‑1, SHAPE‑THIN displays a warning message saying that the effective widths are only determined for straight elements. What does this mean?
What are the options in RFEM 5 or RSTAB 8 for determining the ideal elastic critical moment for lateral-torsional buckling for any cross-sections and systems/loads? Is it also possible to design flat steel (brackets, flat steel stringers of staircases)?