Double-Chord Truss in Kiwi!3D

Plug Ins Kiwi
1

I am trying to use Kiwi!3D to analyze trusses for a research paper on bamboo construction. However, I am having a lot of trouble modeling anything beyond the most basic truss structures.

This what the truss I need to model looks like:

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It has two top chords and two bottom chords, with the webs sandwiched in between and attached with bolts. This is the most important aspect of the truss to model (the truss type and dimensions we’ll adjust parametrically, and the materials we’ll input later.)

I’ve been trying to model this in Kiwi, but I’ve only been able to model a very simple single-chord truss successfully:

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1D Howe Truss - Kiwi3D Analysis.gh (28.9 KB) (Successful)

I tried modeling a double-chord truss using shell elements (with only vertical webs to start with), but it only applied the force to the top two chords, as you can see in the image below. Obviously this is because it doesn’t know the geometries are connected, but even adding ConnectingPoints didn’t help.

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3D Howe Truss - Kiwi3D - Ununioned.gh (68.0 KB) (Unsuccessful)

I tried modeling a double-chord truss with beam elements, but it only returned either (1) no deflection or (2) weird results, depending on where I placed the point loads.
No deflection:

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Weird results:
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1D Howe Truss - Kiwi3D - Double Chords.gh (34.4 KB) (Unsuccessful)

Does anyone know how to tackle this problem? I have a hunch that it has to do with ConnectingPoints and Coupling Features, but I haven’t had any luck with either of those. I’m particularly confused by Coupling Features-- I have no idea how to set the Group IDs and Coupling IDs.

Thank you!
Orion

2

hey, kiwi can only couple intersecting geometries. If you want to model 2 distinct top beams, you have to add short coupling beams without refinement inbetween the beams (ideally at the real joints). Otherwise, you could just model one beam with the stiffness of two tube sections next to each other with the section by numbers component.

connecting points pull two points together, coupling features determine which geometries are interscted with each other in order to find possible couplings.