3D truss model problem in Karamba3D due to 'Rigid body modes'


I am building Gh codes for 3D trusses nowadays, and I would like to analyse them also in Karamba.

My problem is that I can’t figure out how to give different cross sections to different elements (flanges/all other beams).
Whatever I try, it says ‘Rigid body modes’ during analysis. I assume it has to do something with line intersection points (the model seems to be collapsing) but I just can’t find a way to handle this properly.

  • If i intersect all the lines and put them in ‘Assemble Model’ , it is working fine.
  • If I separate lines to different branches, intersect them and put the results in separate ‘LineToBeam’ components, then it crashes.

Any suggestions how to overcome this issue?

(The columns, braces are derived from division points of the flanges so the end points should be connected perfectly)

Karamba_truss.gh (41.4 KB)

Thank you in advance!

Hi @Petozso,
you need to split the lines at their intersections and the plug them into the assemble model. It is strange that the file is crashing. However make sure that the input for the Elements are flattened.

Yes there were some intercestion and tree management problems but I solved them so now it is working as it should be.

Solution if anyone needs it in the future:
Karamba_truss.gh (44.7 KB)

that is great to hear!