How to arch a truss

[Reitveld]

Hello,

 

I’m in the process of creating a arched truss system (similar to what is shown here: http://www.architectureweek.com/2001/0815/building_3-2.html ) I have created a flat truss both in AutoCAD and in Viz and have tried with both models to bend the truss upward to create the arch.

 

My problem is that I can not seem to find the right command for doing this. The BEND command only warps the outside corners of the truss, not the middle. The PATH DEFORM moves the entire truss along the arched path, but does not bend the truss. I’ve tried using an FFD but this does not seem to give good results (I only achieve a bell-curve arch)

 

Has anyone had to bend a series of shapes? If so, how did you go about it? Any thoughts or ideas are welcome!!!

 

Thanks,

 

Patrick

[kid]

BEND should work provided you have enough segments along the length of the top and bottom chords of the truss.

 

if your top and bottom chords are just tubes with no segments along their length the BEND modifier has no where to bend them, if that makes sense.

[Chad Warner]

The other thing to mention is that sometimes I have to rotate the bend gizmo 90 degrees one way or the other in order for it to bend in the direction I want....that might be part of your problem also.

 

-Chad

[STRAT]

 

http://www.maxforums.org/thread.aspx?tid=246015&r=4

[tcorbett]

Years ago I built an arched truss similar to the one pictures for a class project. It was a triangular truss, in a true arc.

 

1. Model a triangle. The corners should be at the center point of the steel tubes. Model the arc that your truss will follow.

 

2. Loft the Triangle, using the Arc as a path. Set your number of shape steps to 0, and the number of path steps to satisfy the number of segments you want to see in your truss.

 

3. Convert the lofted triangle to an editable mesh, then create lines for your cross bracing.

 

4. Apply the lattice effect to the shape.

 

(This works well for distant views, but the lattice does not hold up as well upon close inspection. To design for close views, set up 3 new lines for the arced tube by using the lofted triangles edges, and loft a circle about each. Then lattice the lofted triangle shape with a smaller radius shaped.

[tcorbett]

Found a couple of (tiny) images of that project.

[Reitveld]

Tcorbett: This is a great technique you outlined!!! It quickly creates a truss system without a great deal of fuss. My only problem is that I’m a bit lost on step 3. How do you ‘attach’ the lines to the mesh in order for the lattice effect to work on both the mesh and the new lines? I’ve tried (and failed) to use the attach button (in the mesh edit area) and the group command did not seem to achieve the desired results either. May I ask for a bit more help in this area. Cheers

 

Strat: (others should follow his link to understand my ramblings) Your words of wisdom (and example) has made be reexamine the array command (I don’t seem to use it much in Viz due to my CAD work) but I can’t seem to find anything about arraying to a path/spline. I’ve tried attaching an object to a spline (like what you do with a camera) but could not find a way to duplicate the object. Could you give me another hint (or a kick in the butt) as to where I should look for such a technique.

 

Thanks again!!!

[Chad Warner]

I think the command you are looking for is the "spacing tool" It allows you to distribute objects along a spline.

 

-Chad

[tcorbett]

... How do you ‘attach’ the lines to the mesh in order for the lattice effect to work on both the mesh and the new lines? ...

 

Hmmm.... you can't. D'oh. Been a few years since I have used that method.

 

What I should have said is to make the shape an editable poly, not an editable mesh.

 

Then with the "Edge" selection, under the "Edit Geometry" rollout, there is a "Create" command that will let you draw new edges in. Snap to your vertices, and truss away!

[STRAT]

chad answered ur question. you seek the spacing tool. thats how i did it

 

[mhinks]

I like the structure you got there. would be good to see the full model if there is more!

[STRAT]

i'll think about it

 

i did the whole model over 5 years ago using viz 1 to render it. very dated it looks now.

[Reitveld]

Thanks for the help guys. Here is my crude model with the truss system. thanks again!!! The spacing tool seems to work best for me at this time. I'm going to keep working on the techniques you guys outlined.

 

 

Cheers and Thanks again!!!

[STRAT]

looking good m8. keep us updated on it

 

anyway, as mentioned, here are the original images my truss was modelled for. it's a designer shopping outlet in Berlin. (no built).

 

excuse the quality only these were rendered over 5 years ago in viz 1, even before i used fakiosity.