Rigid Connection - Karamba

Hi Guys, I need your help for a simple question that I'm not be able to solve: I need to connect a reticular element to the section of a steel beam, and to do that, I want to create rigid link, so I created a line element from the end/start point of the beam (as in picture attached), but I don't know how to make them follow the section beam deformation. Moreover if I don't connect a cross section to this vertical element, they don't move and stay in linear position.

I also read about the possibility to use springs, but I really don't understand how can help me in this case.

Hope someone can help me.

Leonardo

Attachments:

1.PNG, 783 KB
2.PNG, 357 KB

Replies to This Discussion

Permalink Reply by Karamba3D on October 15, 2018 at 2:07pm

Hi Leonardo,
I have tried a similar example (see attached definition).
My first finding was, that a spring is not the right connection element in this case, since it connects two nodes without taking account of the kinematic relation (see manual).
When using a beam element it works better, but there is still a gap which opens with increasing scaling factor for the displacements. The reason is, that the nodal displacements are calculated assuming small displacements whereas the transformation of the beam mesh is done on the basis of large rotations.
Best,
Clemens

Attachments:

KarambaTest_cp_RH6.gh, 45 KB

Permalink Reply by Leonardo on October 16, 2018 at 4:15am

Hi Clemens, thank you so much for your help. I understand what you explained, but now I don't know how to proceed: so I have to use a sufficient stiffness cross section for the vertical connector in order to have those point constraint, am I right? In that case, can I hide only this cross section, but not the Principal Beam cross section of the model?

Leonardo

Permalink Reply by Karamba3D on October 17, 2018 at 2:12pm

Hi Leonardo,

the constraint will only work for small rotations. When you scale up the rotations a difference in the displacements of the rotated cross section and the node where the tie attaches will show up.

You can set the visibility of elements via the 'ModelView'-component by providing the identifiers of the elements you want to see at the 'Ids|Breps' input-plug.

Best,

Clemens

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