Help with figuring out how to model this structure

[Arg777]

Hi everyone, Im an architecture student and have some experience with modeling in 3d AutoCad and very minimal experience with revit and 3ds max. I need to model this structure and I'm having a tough time trying to figure out how to go about doing that.

It is supposed to be an outdoors performance space that is covered by this shell like structure. It's composed of concrete ribs meeting at a point but only in a semicircular shape. The webbing inbetween the ribs have catenary curved arched openings with some of those openings having a lattice structure inside. The top of this hemispheric dome is supposed to be a sort of skylight with mullion work and glass. Here are some sketches of what I had in mind:
photo 1.jpgphoto 2.jpg

Now I started to model it in 3D Cad since that's what I know best but this is a very complicated curved structure where curves dont just happen on one axis but 2 or 3. I was able to somewhat create the ribs but i have no clue how to actually create the shell webbing in between and then cut out the catenary curved arches with lattice work or the skylight component for that matter.

If anyone could help me out on this i'd really appreciate it! If it is easier to do in 3ds max, then I am able to do that too, but I just need some guidance. I've attatched my attempt of this model with the corresponding floorplan.

[ReMark]

The skylight could be created by slicing the ribs and webbing using an extruded arc. The SLICE command utilizing the SURFACE option would do the trick.

As for creating the "lattice work" affect I imagine you would have to create the required profiles, locate them properly (i.e.-relative to the curved webs), extrude them through the webs, then do a subtraction.

That's how I view it. If you are patient I am sure other forum members, more knowledgeable than myself, will post alternate suggestions.

[Arg777]

Thanks ill try those but I still need some more help with this. Especially the webbing because no matter how i do it, it doesn't seem to fill the space in between the ribs, either it leaves a gap or it just overshoots them completely. Anyone else have suggestions?

[ReMark]

I thought you already created the webbing and just had to trim it to fit.

[3D generator]

Catenary curves have the unique property that when suspended they are in perfect tension and when they are flipped to create an arch they are in perfect compression. This means the arch is totally self supporting just by virtue of its geometry. Gaudi was a big fan of this form finding technique.

True catenary (also called funicular) modeling is very challenging to achieve because it deals with the force of gravity on the geometry you’re creating. This requires a live physics engine as well as a geometry kernel working together to create the catenary curves.

Catenary curves can be approximated by parabolic curves but the results will not have the same structural properties.

http://mathforum.org/library/drmath/view/65729.html

This could all be boiled down to the math in a .NET script that you can run inside AutoCAD, but I doubt the results would be very interactive or intuitive. Besides, I wouldn’t have a clue how to do that anyway!

http://through-the-interface.typepad...using-net.html

Your best bet is probably using Rhino with the free plug-ins Grasshopper and Kangaroo. Here’s a video illustrating how this modeling technique would work: http://www.grasshopper3d.com/video/k...atenary-system

[Arg777]

Thanks for the reply but that is all far to complicated for what I am trying to do. I don't need to have the accurate forces or know the physics of it, this is just supposed to be more of a conceptual model if anything. Gaudi is where I get the idea to use the catenary curves and i was able to use a plugin to form them in 2D so although they may not be "true catenaries" they are close enough for what I am trying to do.
As for using rhino, I've never used that program and don't have the time to learn it so I would prefer if the solutions stayed within the bounds of AutoCad or 3ds Max.

[ReMark]

Post what you have accomplished since 19 April. We'd like to see the extent of your progress. Thanks.

[Strix]

I'm intrigued

What are the 'walls' made of? or is it a skylight and webbings with nothing inbetween?

Is this the effect you were aiming for?

[ReMark]

The structure is made of concrete.

[Strix]

The structure is made of concrete.

It is supposed to be an outdoors performance space that is covered by this shell like structure. It's composed of concrete ribs meeting at a point but only in a semicircular shape. The webbing inbetween the ribs have catenary curved arched openings with some of those openings having a lattice structure inside. The top of this hemispheric dome is supposed to be a sort of skylight with mullion work and glass.

Nope - still can't find where the material between the concrete ribs is defined (other than the top of the dome being glass)... have you two had off-forum conversation about this?