To enhance the problem a bit, I created a simple 2d truss (attached)
All beams are hinged at the ends. The rectangle measures 500x500mm.
Look at the displacements, what am I doing wrong?! I know I could treat the profiles as Trusses, that's working fine. But why can't I use beams? I would like to use beams, because in different stages would like to make some joints rigid and some not.
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