creating trusses (?)

I am trying to create 2 trusses from 3 points: A, B, and C.(please refer to the attached pictures)

one requirement is that the bottom cord of truss 1 must be the tangent of the truss2, which means that the curvature of truss 1 should inform the shape of truss 2.

I tried to create arcs using points A and B, and B and C, first, but i don't know how to control the curvatures of the arcs and how to have that AB arc inform the shape of the BC arc.

Can anyone tell me what I should do to create arcs with between 2 points with a specific curvature? Or is there any better and easier ways to start ?

Thanks,

Yan

Attachments:

3a.jpg, 479 KB
3b.jpg, 55 KB
3d.jpg, 330 KB

Replies to This Discussion

Permalink Reply by Jon Mirtschin on July 12, 2010 at 1:59am

Hi Yan,

A perfect example of a structure beneficial to model in Grasshopper. I'm not sure what project your images are taken from, but it's quite similar to the roof system for the old Eurostar terminal at Waterloo (London).

I'd really like to add a blog post (http://geometrygym.blogspot.com) tutorial as an example of how I'd generate it (if it helps). Although it will be utilizing the structural plug-ins I've developed (and not a pure Grasshopper solution, others might provide that).

Hopefully later today or tomorrow I'll have it posted.

http://www.grasshopper3d.com/forum/topics/truss-from-a-surface-and-a is another example of generating geometric trusses if you want to study in the mean time.

Cheers,

Jon

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