Hey @m1234 and thanks for tagging Barry!
Regarding the geometry you have to make sure that the solids do not intersect meaning that you have to clean up the geometry a bit. On top of that why is there a shell inside the geometry? Any specific purpose for that? I would remove that one if it is not necessary.
Another issue is the wrong definition of the master-slave contacts. You would have to define each contact of the beams with another one manually. That was just some small information on the optimization process - @cjquijano or @BenLewis might give you more specific tips!
All the best!