Trying to Make 3 Sided Tent Structure

[dgreen.49364]

I am trying to make a tent/awning type of cover that is 3 sided, arced, with the 3 points being at different elevations, 12', 14' and 16'. I am scratching my head on how to go about this. I've attached a pdf. How would you go about using the solid and void tools to make this?
Thanks.

[comhasse]

This is definitely the type of object that Revit is not very good at (for now). To model a tensile membrane accurately you would most certainly need a very specialized software. The next best thing might be a spline patch modeler (Possibly Blender might work). However i found your question challenging enough to try this myself. If you are only trying to get the looks right this may work for you:

In a new in-place family i first created hemispheric shell with the rotation tool. I then added a negative Extrusion with splines tracing the edges of the tent (like a giant cookie-cutter). Obviously a tent-surface is not really spherical but it looks pretty close. If you know the approximate curvature of the tent, you can guess the radius for the sphere. I didn't construct that precisely but you could draw three concentric circles equivalent of the intersection of your three height levels with the sphere to find exact locations for the corner points.

For a saddle-type roof (four corners) you can use a horizontal blend, then trim the edges with splines in the same way. The image shows the generating "curves" in the edit mode of the blend tool. Note that i made them sag in to simulate the impact of the structures dead load.

Hope this helps.

P.S. Some Links about Tensile Structures (http://www.tecnun.es/labcad/membranes/index_main.htm#software) (Including Software)

[Zoltan]

OK.. This is a little complicated, but i did it with a footprint roof and a single slope arrow. A slope arrow in a footprint roof defines a plane that slopes up in the direction of the arrow and intersects the ground plane perpendicular to the arrow. So, to create the compound slope, we need to determine the direction for the slope arrow and where it will end. The tail of the slope arrow needs to be on a line of the footprint. We will start the slope arrow at the lowest point, the 12' vertex and extend it until the head is halfway between the height of the other two vertices - 15'.

First, using Model Lines, draw the arcs on Level 1 and label their vertices with model text for the height at each vertex. This will help us get oriented in 3D.

Now, create Reference Planes by snapping to the end points of the arcs and name the planes A, B, and C. We want to create elevation views perpendicular to the ref planes, so we will create walls using the select lines option and pick the ref planes. Now, the elevation command will be able to point the view to the walls. After the elevations are created, we can delete the walls. Name the elevation views A, B, and C to correspond to the ref planes.

Next he will want to create three levels for the height at each vertex.

By switching to each elevation view and setting our Work Plane to the corresponding ref plane for that view, we will draw Model Lines at each vertex of the triangle of arcs, up from Level 1 to the level for the height at that vertex. Then we will draw two sloping lines from the higher levels down to the lowest level; in this case 16' to 12' and 14' to 12'.

These lines define the plane for the sloping roof. We need to determine a line where this plane intersects the ground plane so we can create a slope arrow that is perpendicular to that line. By drawing a line on the level 1 level line and using the trim command to extend each sloping line until it intersects level 1 we can determine the two endpoints of the line where the sloping plane intersects level 1.

We will now use this line to draw a reference plane starting at the lowest vertex and ending perpendicular. Let's call this plane X. Create an elevation view at this ref plane similar to the others. In this elevation view, we can draw a sloping line that is collinear to the other two lines of the plane and ends at 15'. This will be the line we use to locate the slope arrow projected into the roof's footprint.

Now all we have to do is create a roof by footprint at the 12' level and select the arcs to create the footprint and draw a slope arrow by snapping to the ends of our bisecting line. The spot elevations confirmed the heights at each vertex of the roof.

[stuntmonkee]

Anyone opposed to using topos? This took about 10 min.

it's not exact, but for our side of things, I'm not sure you would need it exact. . . .if you are looking for exact heights, then you would need a diff software I would guess.

[dbaldacchino]

What was your process in using the toposurface? I find it to be a perfectly acceptable representation.

[comhasse]

Stuntmonkee, I can't look at your file, because i am still using R9, but this sounds like a valid idea.

A couple of drawbacks though: you won't be able to schedule this meaningfully, section views are a problem (earth fill), and you can't use it to generate more detailed building elements like curtains walls etc.

[Zoltan]

Would the surface really be curved if it was only attached at three points? Three (non-collinear) points always define a plane. If the tent was attached to 4 or more non-coplanar points, then it would be a curved surface.

[comhasse]

Would the surface really be curved...
Certainly you could build a rigid planar roof, intersecting the three points. But this is about a tent, which will always sag into a curved shape by its own weight. The amount of curvature will depend on the physical properties of the material and the tension applied to the structure, but it will always be there, as long as the material is not rigid.

[Scott D Davis]

Here's one using a mass blend to set the 3 points at different elevations, then a void to cut the "curves" in the sides of the mass. Roof applied by face with a roof set to be a 1/8" fabric. This example does not "sag" but I think it gives a pretty good representation. Only took 5 minutes to put this together.

[stuntmonkee]

What was your process in using the toposurface? I find it to be a perfectly acceptable representation.


Its pretty simple, really.

1. Dont really wory about the shape at this point. . .worry more about the general slope, and create an even slope with multiple points. (drop 5 or 10 points at each 1' interval instead of just the 2 at the end)

2. after you get the slope you are looking for, split the surface 3 times at each arch from point to point

3. You will then be left with your "tent" shap in plan.

4. Re-Edit the surface, and you will now see the the remaining point as well as the new one along the curves.

5. adjust the interior points to get the desired "deflection" effect. (You may want to add or eliminate some extra points)

6. Your done.

[stuntmonkee]

Stuntmonkee, I can't look at your file, because i am still using R9, but this sounds like a valid idea.

A couple of drawbacks though: you won't be able to schedule this meaningfully, section views are a problem (earth fill), and you can't use it to generate more detailed building elements like curtains walls etc.

Your right on all of these, but depending on the use, it should be too much of an issue.

The biggest hitch would be the site fill, but you can adjust it to 0, and then copy the topo down a fraction of an inch to get a "visual" thickness.

If you need site fill on this section, you may have to revert back to filled regions.

Schedules? Yeah, but you should still be able to get an area no?

Your last hickup had me kinda confused? Not sure what you were refering to with Curtain Walls?

[Zoltan]

Here's one using a mass blend to set the 3 points at different elevations, then a void to cut the "curves" in the sides of the mass. Roof applied by face with a roof set to be a 1/8" fabric. This example does not "sag" but I think it gives a pretty good representation. Only took 5 minutes to put this together.


Could you attach that file, so I can see how you did that?

[Scott D Davis]

see attached ZIP file

[kwong]

Hi

I was also looking for ways to make tensile structures in Revit (see attached), but wasn't successful. Finally did in ACAD using egdesurf and imported it into Revit which has easier control of views.
Would like to hear if someone's found a way of doing this in Revit. Most of the samples seen here look very rigid and as Scott says has no sag.

[Scott D Davis]

Try the new Roof editing tools. You can grab the points of the triangular roof and stretch them up and down to make the tent like structure.

[AP23]

You can use any 3d software to make a tent structure. Just make sure they can export as .sat files. Imported files have their side effects in Revit, but that's another story.

Here is a nice clip to be jealous of http://www.youtube.com/watch?v=o9kTXETSuVo

[kwong]

Thanks for the tip Scott, just tried it on Revit Arch 2008 (first time). However the sides have to be straight lines - I tried it with arcs as the sides & the options are not there.

[Scott D Davis]

Use straight lines in the sketch, and finish the roof. Then use the opening tool from the modeling bar to "cut" the curved sides into the roof.

[adb]

Using Scott's method you can also add several split lines to the roof to represent the sag in the fabric.....if you needed to.

[dpasa]

What I use for 3d modeling, is MoI... A great program, free for now (open beta period). See attachment
www.moi3d.com

[comhasse]

Try the new Roof editing tools. You can grab the points of the triangular roof and stretch them up and down to make the tent like structure.
Wow, this is great, i didn't realize you could create complex curved shapes with the new tools.

Alas, you can't turn such a roof into a roof glazing and you can't apply a curtain system by face based on a roof surface either. Or am I missing something? It really seems the program could do it, they just need to make it accessible.

EDIT: I just tried to export my tent roof to dwg and reimport into a mass, then apply a curtain system by face. It didn't work, i guess the surface is actually too complex for that.

[AP23]

EDIT: I just tried to export my tent roof to dwg and reimport into a mass, then apply a curtain system by face. It didn't work, i guess the surface is actually too complex for that.


It will only work if you export as .sat file.

[adb]

.....and here it is constructed from the 2008 edit roof feature.....sag and all.

Obviously you could get a much more accurate representation by adding more points but you get the idea.

[comhasse]

What I use for 3d modeling, is MoI... A great program, free for now (open beta period). See attachment
www.moi3d.com
I'm a Moi addict myself, haven't used it for my Revit projects though. How do you import into Revit? Do you go through Autocad?

[tjhernacki]

See if this helps. Maybe you can modify it to your needs.

[kwong]

Allen,
Thanks for the example (tent structures2), as they say, a picture tells a thousand words.

[adb]

No problem.

It was Scott's suggestion, I can't take the credit.

That's why he gets the "big bucks". Hee hee.

[kwong]

Allen,
How did you get the elevation values for your points to arrive at such a smooth sag - did you have to calculate to arrive at the numbers or some other way?