Answering on questions ASD to RSA link questions:
- Link made an automatic placement of elements on space. Some of them like purlinks on rafters are analytically linked but RSA does not confirm it while elements has no common nodes. When it happens (like elements laying on other) it needs that nodes to be connected by Rigid Link. This is not phisical, the geometrical dependency of displacement between the nodes. Here in such situation it was generated automatically.
- I assume that during link definition you left the Plates->Panels check box option OFF (as default). Please try with ON and define the material of plates. Be careful leaving the default structure type as Frame 3D in RSA. With plates it should be Shell.
- It seems like the structure is not consistent or unstable. It never is possible to guess by this error. Must be checked. On my simple default test (I assume very close to yours) my structure was full of short elements acting the bended bolts of connections. It might be the geometrical disorders' sign of such linked model.
Truly said, in case of this kind of connection with brackets, this stiffener is not so important for connection strength.
Jakub, you are right. I've made some tests with other structural program, and there is no difference with the second stiffner.
Please accept my apologies.