As part of my never-ending challenge of producing better 3D backgrounds for MEP coordination I've been trying to export a quadrant based Steel fabrication model.

Here's why:

1) Our Revit Structure model doesn't have all the small connections, angles and slab edge reinforcement modeled.  Our steel fabrication model does.

I got it working, but blew up a couple times in the process... and kept me in the office until 8PM last night (despite the fact I was working on my new Revit monster with 36 GB of RAM and 6 simultaneous sessions of Revit when importing my IFCs)

1) Revit 2009 + IFC import.  Geometry isn't cleanly imported.  Geometry gets unjoined (or can't be created at all!) ultimately, I get columns that disconnect from beams like so:

2) Revit Structure 2009 + Structure extensions + CIS/2 Import

Random small pieces of geometry aren't created.  Others are created with problems identified in the images below:

In orange: Original DWG from steel fabricator

In Grey: CIS/2 STP of same model from steel fabricator.  Imported into Revit, exported as an NWC.

As you can see, the CIS2 RVT is missing the edge of slab & precast embeds.

This is far more troubling -- the slope and attachment points of angle bracing has changed.  I'm actually dealing with some sloped roof drains in this bay, so the CIS2 imported model is useless for this reason alone.

same issue, different location.  All of my small diagonal bracing & kickers are off w/ the CIS/2 RVT model.

The final straw is the large connections for our W14x211 brace frames.

Bottom line?  Way too much detail is lost in CIS/2 --> RVT and IFC --> RVT.

The only geometrically accurate option (even though I lose edge of slab reinforcing bar):

Blank Revit project, import all the DWGs, and deal with the artifacts and "space junk" that happen when Revit attempts to cut a DWG, when I export it along with all of the designers models (which are all native Revit files, and cut rather cleanly... except for Revit MEP, which is another story).