IFCs - complex profiles - SEOs

[Anonymous]

So in AUS we still don't have access to AC17, and are left to experiment with AC16.

Trying to write IFCs for a consultant we have learned:
Complex profile walls do not convert properly into the IFC model. The intersections of walls are rubbish.
Complex profiles cannot be connected to roofs or SEOs used, as these do not translate in the resultant IFC file. The only reliable method is the old trim to roof command!
Windows and door in complex profiles do not display properly in IFCs.

As part of our testing we tried creating a simple 'core' in the complex profile, and exporting the 'core only' geometry as an IFC. That too failed.

Advice from GS support is to model multiple walls in lieu of complex profiles(!) - or wait for 17.


Apparently in AC17 there is a new way elements connect - are any users out there able & willing to verify whether these reliably convert in an IFC export?
To anyone at GSHQ who is reading this - advertising open BIM and delivering open BIM appear to be divergent - I hope this is truly addressed in AC17....or we will be left to ponder the viability of AC in the future.

[Marton Kiss]

Hi,

have you had a chance to try this with ArchiCAD 17? It should be available now in Australia.

Is using BREP geometry for complex profile an option for you? It will get you the closes geometry even for complex elements.

Marton

[owen]

If you want 100% fidelity of complex connections such as SEO's, complex wall junctions and the new AC17 Building Material-based Priority Based Junctions then you need to use the BREP Export option in the IFC translator.

This will ensure your model geometry is correct when imported into coordination software such as Navis or Solibri, as well as other authoring applications such as Revit.

There are however downsides to BREPs in IFC2x3 including:

1. Elements are imported into Revit as in-place massings rather than parametric elements. Usually no big deal if you follow the 'reference model' approach to coordination, however it does make graphical control by the receiver more difficult

2. Element relationships may not be supported. One that comes to mind is that Doors/Windows in BREP Walls are no longer hosted by the wall but become 'free-standing' Doors/Windows, so you cannot for example use a model checker to ensure certain wall types only have certain door types used in them (e.g Fire Walls & Fire Rated Doors). Its an IFC Implementers Agreement which i don't think was thought through properly .. and will become increasingly relevant to ArchiCAD users due to AC17's PBJ's requiring BREP method to export.

cheers,

owen