Beam to truss connection for cable supported structures

Analysis issues
1

Hello,

I am trying to model a cable-supported beam structure.

I need a way of connecting T3D2 elements to B32s. Shared nodes do no constrain the truss in the Z-direction, and including Rigid Body causes a non-convergence.

I can’t use SPRINGAs, as I need temperature dependence for preloading.

Thanks

2

Shooting off the hip here but is it possible to just add a couple of Z restraints on the truss? Don’t know your model but initially there may not be much load perpendicular to the truss?

3

Check this thread:Beams and truss don't connect in Z

4

Thanks! There’s a good 40-50 such connections so was looking for a slightly quicker solution, but will work for now

5

If you don’t mind rebuilding CCX, the fix is a couple of lines in gen3dnor.f. Move beam=.false. from the else clause in line 466 to outside the loop before line 457.

Alternatively, you might be able to work around it by renumbering the elements. Put all the beams at higher numbers than the truss elements.

6

I think that we should ask Guido to change this in his GitHub repo so that Truss and beam elements disconnected · Issue #14 · Dhondtguido/CalculiX · GitHub is finally resolved.

7

I think rebuilding CCX (windows) is beyond me, however your hack with the renumbering worked, but the complete other way around. Trusses after beams work perfectly.

Getting this sorted in a future build would be amazing (thanks in advance Guido!)

1 Like
8

It would be nice but beware there are a lot of other bugs in beam and truss elements, some of them more subtle than this. Be careful to validate your results thoroughly.