Answer:
Orthotropic surfaces are non-linear and cannot be designed in the RF‑STEEL Surfaces add-on module. It is possible to get a full stress analysis in RFEM for orthotropic surfaces defined with the orthotropy type "Constant Thickness" and compared to limiting stresses manually. For all other orthotropy types, the program is not aware of the geometric properties for the surface at every FE mesh point that are needed to calculate stresses. An extensive and detailed FE model would need to be created. See FAQ 2468 for an example of this. Surface types need to be set to "Standard" to be designed in the add-on module.
