Karamba Analyze issue

Grasshopper Karamba3D
1

Hi everyone,
I’m a structural engineer and I am just starting to play around with Grasshopper and Karamba.

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I am facing an issue with the Analyze component. I’m getting the following error message:

“1. There are 18 rigid body modes in the system. This means some parts can move freely without causing deformation.
Try to use the ‘Eigen Modes’-component and activate the display of local coordinate axes: The first eigen-mode will be the rigid body motion.
If this does not help, check whether you have a pinned support directly attached to a hinge. A hinge introduces an extra node which may cause the problem.
When analyzing a flat shell structure one has to lock the rotation perpendicular to the plate in at least one node.”

I have looked for a solution online but although finding many threads about this topic, none of the solutions have worked. I would really appreciate it if someone could have a look at the attached file and give me a hand.

Many thanks,

Akira
KAD frame GH.gh (21.0 KB)

2

do you have any hinges applied to the ends of beams? what are support conditions?

3

Hi, your beams are not split at their intersections. Karamba3D does not recognise that there is a connection at that point (similar to all FE softwares) and therefore your structure is kinematic.

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You can use the ConnectedParts component to check if there are parts of your model which is not connected:

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KAD frame GH_mt.gh (35.5 KB)

best,
Matthew

5

Thank you very much for fixing this Matthew!

However, I can’t really see what is that you did. Where or how did you put connections between elements to stop it from being kinematic?

Akira

6

You need to make sure your beams are split at their intersections.