export for structural analysis

[jfudo1892]

I'll start off by saying that I'm new here, and I'm a structural engineer. I've been working in revit for a coule weeks now, and I'm starting to appreciate its abilities and potential.

Ok, I've fully modelled in revit the framing for a large church building (relatively complicated layout). Took a couple days, but it looks great. In an attempt to save time, I want to export the steel framing (all located in its own workset) to a single line 3D DXF file. I've found that by going into the 3D view, then exporting from there, I can get a dxf of the framing, but all the beams and columns shapes are shown. If there was a way to do this while leaving a clean line drawing my efforts would be greatly reduced.

I don't know 3D autocad very well, and I can't figure out how to fix it there either. Is there anyone out there that has successfully converted framing to a finite element analysis program?

Any insight would be appreciated.

[Scott D Davis]

This is a question for Greg Cashen. He was on vacation last week, not sure if he's back yet. Drop him a PM or eamil.

[David Sammons]

I am currently experimenting with exporting a DXF file from Revit and importing the structural geometry to a structural analysis and design application (SAP2000). So far I have not had much success but I will let you know if I make any progress.

Dave S.

[PeterJ]

If what you require is essentially a stick diagram then you should just be able to set the view resoltuin to coarse and then export. I have not played with 3D export so I don't know what you will guess, but it should work.

[gregcashen]

I can do this...sort of ;) ... in Multi-frame. Don't know about other tools, but I would guess it's pretty similar based on past experiences. Here's what you do...

1) Open a 3D Framing view with nothing visible but the framing and columns.

2) Export view as DXF. Because Revit structural framing members have these nasty offsets that cause the beams to hold back from the supporting member, the stick model will also have gaps between the elements, so...

3) In autocad, join all the joints together so there are no gaps (this could also probably be done in the analysis program, but I find that to be tedious sometimes...so I use autocad, which is slightly less tedious).

4) Save and open the DXF in the analysis program.

5) Rotate/Move the model to the proper orientation.

6) Repost here with results...;)

[aggockel50321]

Has anyone looked at the new XML export available in 6.0?

Try one & take a look at the file. Might be useful.

[jfudo1892]

I've tried exporting the stick frame in coarse mode, but my structural program (ram advanse) can't open it. I noticed another potential problem, that is the beam will show up in that stick diagram at its base level. Doesn't consider offsets. My building is very irregular, some of my offsets are 3 or 4 feet. That doesn't work so well.

I think I will just build my model for now and hope that in the futer Revit will be more accomodating to structural engineers. There are many items on this list...

Thanks for the help.

[gregcashen]

I think I will just build my model for now and hope that in the futer Revit will be more accomodating to structural engineers. There are many items on this list...

I think it will be VERY accomodating to engineers in the future. I have a lot of wishes too!

[nmangon]

I want to add some suggestions to Greg’s workflow:
What we did recently is that we changed the medium representation of beam families.
We assume here that we do not need the medium view representation. We simplified the beam by just having a stick view representation. We also removed all the “nasty offsets”.
So we built the model in Revit and used coarse and fine view to generate drawings and we used medium views to generate dxf for analysis packages.
We generated 2D plan view dxf and we imported them in Etabs. Then we built objects (beams, columns) in Etabs.
I have attached a bitmap of the 2 models and also the beam family.
You can also generate 3D dxf. Now the problem is, do analysis packages can read 3D dxf? Some can and some can’t. General purpose finite element programs should be able to do it but building design packages will be more likely to read 2D plan views dxf only.
Without telling you too much information, I can tell you that in the future you will be able to exchange objects between Revit and analysis packages.

Nicolas Mangon
Revit Structural Product Manager

[David Sammons]

Nicolas,

This is very exciting - particularly since you are looking into the interface with ETABS (and hopefully Computer and Structures, Inc.'s general purpose analysis and design application SAP2000)!

Did you import a 3D or 2D Revit dxf to ETABS to create the ETABS model?

Dave S.

[nmangon]

We generated 2D plan view dxf and we imported them in Etabs. Then we built objects (beams, columns) in Etabs.


Nicolas Mangon

[gregcashen]

The beauty of Multi-frame is that it imports the 3D dxf quite nicely. The downside is that no one in the states uses it...:( With Nicolas' beam family and my method (assuming the tool you use will import 3D dxf's or dwg's), the workflow would be very straightforward.

[nrenfro]

Coming at this from the residential architectural side our structural consultants are using a program called Optiframe http://www.optiframe.com/index.cfm/fuseaction/pages.pagehandler/pageID/1 do any of you know anything about this product or have an idea whether or not the program will be able to communicate efficiently with Revit? The power of Revit as a Architectural tool will be how well it can coordinate with consulantance software packages.

[nrenfro]

How are you importing the Etabs model back into Revit. Do structural members have any imbedded intelligence? As I mentioned before Most of what we do is Residential, but the field is changing rapidly. There is a lot of pressure to panelize, and this is going to require a much tighter coordination then has previously been required.

[tyler.kawahara356150]

Link is broken

[Dave Jones]

Link is broken

not surprising...it's 6 years old. You might want to check this link

http://downloads.seapine.com/pub/papers/CuststoryOptiframe.pdf