I'm trying to perform a simulation on a series of pipes and flanges (all hollow). for better performance and shorter time spending I decided to use beam element, which should makes sense because of geometry of my assembly. first I joined all parts in assembly in one part and saved it. then using this new part I started a simulation but when I clicked on "Treat as Beam" it calculated joints like this:

which obviously is not what i had in my mind. how can I change location of joints to place them in end of each side?

was joining all parts into one part a good idea at all?

thnx