Hyperbolic Roof Segment andStaight Line Generators

[Tom Weir]

Hi all,

We are designing a new hold room for an Airport project. I am stuck trying to create part the roof. Sloping beams are required to slope the corner bays for drainage purposes.

The roof diaphragms at the corner bays warp creating hyperbolic roof segments. Using straight line generators the beams are all created as straight members. (Elevations are 0" at grids D4/DB, D5/DB, D5/DD, and +10" at grid D4/DD on the attachment)

What is Revit's opinion on creating hyperbolic roof sections using straight line generators? It is fundamental to most roof systems. Is it somehow not possible because of the structure of the code or something? The geometric principles seem obvious.
Is it something they are working on?

Is there a solution I have overlooked other than making everything braces? Is there some workaround I could use making two triangular sections and using slope angles to approximate the warped roof segment?

I can't seem to come up with anything that will get me through the job....

Thanks and have a great day...

Tom Weir
Los Angeles

[Chris DiSunno]

How about drawing it using Topography? It will mess up the functionality of skylights etc. but you can still punch holes with pads.

[Steve_Stafford]

I don't think I fully understand what you want to see...are you describing something like this roof?

[Tom Weir]

Maybe topography would work, might get me through the day. Thanks.

Steve,
Take a rectangular piece of paper. Fix 3 sides to a flat surface. Then lift up the fourth edge. It creates a curved hyperbolic surface.
We slope the framing but the members are not bent or curved that support the surface. They are generated as straight lines.

Thanks.

[Dimitri Harvalias]

Tom,

Hyperbolic roof planes are easy to create using blends. Create a work plane at one edge and then sketch the start of the blend as a level section. Create the end of the blend with one corner at the base level and the other at the top level. Go to the plan and just pull the one edge to the total length of the roof required.
The tricky part is getting the beams to follow the slope of the roof. You can find the correct plane by doing a series of sections or creating a series of ref planes at the beam locations. Place beams at those locations, rotating them until they are at the correct plane. This seems like a huge pain to me.
If you are just looking to represent the assembly with something you can use a combination of curtain system and blend. Creat the blend for the roof and then use the edges to create a curtain system. Use mullions to simulate the beams and purlins and then just select all the curtain panels and make them 'empty'. Looks pretty good but "it ain't real man!"
It would be nice if the beam system tool allowed for warped decks to be created.