Karamba Rigid slab connected to shear walls

Hi everyone,

I am trying to find eignenvalues to a construction and I am having issues with connecting the slab to the walls of the building.

I import a floor plan from CAD then extract middle lines from the walls to create a karamba model. I am trying to create an automatic process that calculated the eigenvalues on a simple model depending on the floorplan.

However, I am stuck with the slab to wall connectivity. My slab goes crazy when I try to find the eigenvalues or try to analyze the model for gravity loads. I get the following warning:
“1. There are 3 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.”

Example of my slab translating when calculating eigenvalues:

I tried adding springs to the slab in many different ways, however I can’t wrap my head around the connectivity. Especially if I go with more floors, the example I uploaded is for 1 floor only, but if I copy the floor plan 3,4 times to get 3 or 4 floors, I have more issues.

Any feedback would be helpful. Thanks!

Rigid slab + shear walls.gh (41.1 KB)

Hi, your geometry is not internalised so we cannot debug your definition. However a good tip when connecting slabs and walls you can use the MeshBreps component - 3.8.1: Mesh Breps - Karamba3D 1.3.3

Thanks for the response Matthew,

I will upload the geometry also, I forgot to upload in the original post.

Frankopanska.3dm (516.1 KB)
Rigid slab + shear walls.gh (40.2 KB)

I managed to connect the Slab to the top points of my wall using Mesh Brep. However, I am getting large translation values on some walls when calculating the eigenvalues. So, I am not sure did I connect the right points to the slab using Mesh Breps.

Rigid slab + shear walls.gh (39.4 KB)


your plates are not connected properly. Please refer to this script where you can use the MeshBreps component to connect your meshes using shared vertices.

Rigid slab + shear walls-mt.gh (52.8 KB)

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