New optimized plastic redistribution
If you intend to use the New optimized plastic redistribution, here's what to check in your FEM-Design model.
Supported structural elements
The New optimized plastic redistribution options for PREFAB are, at the moment, only available if the FEM-Design model contains nothing but: plane walls, trusses (which must only go from element to element, so no passing through multiple walls) and line supports. This means slabs, bar elements, point supports, etc. can't be in the model.
As a solution, slabs need to be modelled as covers. Columns/beams can either be solved in a separate model with reactions converted to loads, or modelled as shells with careful consideration of edge-connections.
It's on the development plan to support bar elements.
Analysis setting
PREFAB doesn't need the non-linear results from the FEM-Design analysis to do the new plastic redistribution, so it's highly advised to save your time by going to Setup by load combinations... and deselecting NLE and PL – they're on by default.
You can also control which load combinations are read by PREFAB using the Calc setting.