I'm not very knowledgeable about SW Simulation, so I can't help much with your mesh problem, but looking at the picture, I would think that you would be much better off running a beam simulation instead of a solid simulation. The next option would be to simplify your model to surfaces and then use shell elements. This may get a bit tricky where you join the pieces together, due to the offsets.
Check interferences - mesher doesn't like them.
get rid of the components you done need - braketes and fasteners.
Think hard about what you want the analysis to tell you then adjust the model to give you that.
Zdravko, Before I have question, How to force value? (1,400 N/m2 or 1,400 N/m)
In case, you can mixed mesh for contruction. (Suface and Beam element)
The force is 1400 N/m2
Could you please say me what I should do?
Thanks in advance.