Problems with connecting intersecting beams in Karamba3D

[parametric_engineer]

Hi,
I’m trying to create a hinged connection between the two beams as shown in the image.
The problem is that when I define a hinge at the intersection, the cantilever part of beam B is no longer bending-stiffly connected to the rest of beam B and the system becomes kinematic at that point.

I only want to release the bending moment connection between beam A and beam B — how can I achieve that?

Thanks!

[matttam (Matthew Tam)]

Hi, did you use the Beam Joint Agent component, as this allows you to define joints between elements

3.4.2: Beam-Joint Agent | Karamba3D v3

[parametric_engineer]

Hi Matthew,

Yes, I used the Beam Joint Agent component.

Here is my Grasshopper definition — I marked the crucial part in red.

When I change the cantilever length from 0 to a positive value, the cantilever part of the beam becomes kinematic.

My goal is to release only the bending moment connection between the two intersecting beams, while keeping the cantilever segment rigidly connected to the rest of its beam.

Thanks in advance!
pavillon.gh (96.9 KB)

[cp1 (Clemens Preisinger)]

Hi @parametric_engineer,
I see three possible ways to model this connection:

1. Introduce an extra connection element, as shown in the vertical section below:
   
   
   
   This can be implemented either by manually creating extra geometry in Grasshopper or by using Karamba3D’s Felting-component (see here). The joint can be on either end of the connection element.
2. Add torsional joint in the horizontal beam as illustrated in this ground view:
   
   
   . It’s important to ensure that the horizontal beams are not free to rotate about their own axis. A simple way to achieve this is by assigning a small torsional stiffness to the joint.
3. Reduce the torsional stiffness of the horizontal beam via a ModifyElement-component to a small value(see here). This option is only suitable if the beam’s torsional stiffness is not essential for your structural analysis.
   – Clemens