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)?
After running the design in RF‑STEEL AISC, I receive error message 1002 - Invalid cross-section of type "Channel" according to F2. What does this error mean?