Creating Roofs for Structural Engineer

[rmcelvain.103137]

Hi,

I am a structural draftsman working with Revit Structure. We are currently doing a project with an architect who uses ArchiCAD and he is importing our structural model into his.

I have no idea how to tackle this sloped structure though. I know I can create a roof and attach my members to it but could someone give me some pretty thourough direction on how to create the roof shown in the attached images?

Thanks in advance,

[sbrown]

I would build the roof as triangles, using the slope arrow tool to set the spot heights. Or use the mass tools to create the roof shape, then use roof by face to create your roof. For your beams you will set up ref planes or grid lines along each axis, then create an elevation attached to those grids and draw you beams following the roof slope. Then your bar joists can be placed using the bottom of the roof as your work plane.

[rmcelvain.103137]

I would build the roof as triangles, using the slope arrow tool to set the spot heights. Or use the mass tools to create the roof shape, then use roof by face to create your roof. For your beams you will set up ref planes or grid lines along each axis, then create an elevation attached to those grids and draw you beams following the roof slope. Then your bar joists can be placed using the bottom of the roof as your work plane.
Scott,

When using the slope arrow tool, it appears that I am able to only use 1 per roof segment. What can I do if I've got different spot elevations at each corner of the triangle?

[david.kingham]

Something like this?
It's really a pain to create warped roofs/structure right now. I've talked to the structure developers about this (specifically nicolas mangon)...hopefully they will have something in the next release but who knows

[sbrown]

I've allways been able to get by with the triangles, establishing a constant height around the perimeter and a slope arrow to the drain. sometimes there is a slight gap between the valleys but its almost always un perceivable. However if you need to create a truely warped roof, I would do it with inplace families or masses, Use a blend in section to define each end of the roof, then a void in plan to cut the triangle shape. Complex yes, so we need a roof by spot elevation command, so currently the easiest option would be to use topo surfaces point by point, export to acad, import as mass, then roof by face.

[Rols]

I ran into this last week.
I tried to "simplify" it by making a parametric mass family that was an adjustable triangle with adjustable z coordinates at each corner. It worked fine, but when I placed it into a project and then tried to make a roof by face, it would work sometimes and not others. I couldn't quite figure it out.
In the end, we ended up using blends as Scott described.
I'll gladly second the request for a roof spot elevation tool.

[rmcelvain.103137]

Blends and Warps and Points :shock:

I'm going to chew on these replies for the rest of the day and see if I can actually get them to work!

Thanks for the direction,

[nmangon]

Thanks for the feedback.
we are well aware of the issues that you mention and we are working on it

[lev.lipkin]

A few issues of using a parametric mass family for roof by face. You can pick face, create roof for each face, or pick a few faces and create one common roof which spreads all faces. The difference is in geometry when roof 'plates' meet: separate roof will have jump on other (opposite to mass face) side along 'meeting' edge. Roof that spreads a few faces would try to miter surfaces (which might cause failure).
Another reason for geometrical failure is that pick face roof tries to build vertical faces connecting top and bottom face which might require extension of the face, and the extension might get curved away. I wonder if you could post examples of failures here (if small) or send them to Support.
Thanks for your help.

[dbaldacchino]

First of all, thanks to all the developers for posting on this forum and thread. I think it's really nice to see that...thumbs up!


Something like this?
It's really a pain to create warped roofs/structure right now. I've talked to the structure developers about this (specifically nicolas mangon)...hopefully they will have something in the next release but who knows
David, how did you define planes for the joist members?

[david.kingham]

Just created a framing elevation and manually rotated the ref plane into the correct position, not pretty at all, although the final product is pretty nifty lol

[dbaldacchino]

Haha I know, you impressed me. The process isn't pretty. We've been experimenting and noticed that when you change the roof slope in a linked file, beams get detached and it's a real pain to associate them back to the slab. If you change the slab in a RS model, the beams rotate just fine. But when it comes to warped roofs, there is no one plane. There's a unique line at each section, so you have go through the hoops you did, essentially defining a plane for each beam. Bummer :-/