IFC Import - Multiple models in same IFC file

[Ben D]

I've been given a structural IFC, containing two submodels in its model tree.  the structural steelwork is in one model, and the trusses and framing are in another model within the same file.  If I open the IFC in Solibri, I can see the elements of both models.  see below screenshot.  the steelwork is in the "Structure 1" model, and the rest in "Building.b.1".

however, when I then import this IFC into Archicad, I can only choose one of the two models to import.  once this has been done, there seems to be no way to access the other model withIn the file and place it within the archicad file.  The only way around this I've found is to duplicate and rename the IFC file, and import it again, choosing the other model.

This seems a bit crazy - I shouldnt have to keep duplicates of the file to access different parts of it.  Is there a way to get archicad to allow you to place different models from within the same IFC?

Any help much appreciated.

Operating system used: Mac Apple Silicon

[Laszlo Nagy]

Can you place the IFC twice as Hotlinks?

[Ben D]

Not really - if I place it again, it doesnt give me the option to select which model to use from the IFC.  it just places a copy of the same model I selected the first time.  As I said - the only way I've been able to place two different models contained in the same file was to 'trick' archicad by duplicating the IFC and renaming it so that archicad treats it as a completely different IFC file and gives me the option to select model on first import.

[Laszlo Nagy]

OK, so, based on what you said, I assume you used the Merge command to import the IFC geometry and merge it into your Project file.

There is another method:

1. Start a new project file, based on the settings of your current project file (not based on the default Archicad template).

2. Merge one model of the IFC into that file. Save the PLN file.

3. Place the PLN as Hotlinked Module into your main project file.

4. Start another new project file, based on the settings of your current project file.

5. Merge the other model of the IFC into that file. Save the PLN file.

6. Place this second PLN as Hotlinked Module into your main project file.

Archicad can handle only a single Building (or, should I say, a single IfcBuilding), so this is how you can bring it all in.

There is another option: Ask the person the IFC comes from to give you two separate IFC files. Or ask them to give you one IFC file that includes all that geometry within one IfcBuilding. Those structures all belong to the same Building, there is no reason they should be in separate IfcBuilding hierarchies in the IFC file.

[CosminF]

Hi,

I ran into similar issue a while ago (received a racking IFC where each span was a separate "building"). So I had to import the same file 40-50 times and merge them manually. Not fun.

I looked back into the topic and saw someone offered a possible solution (using 3rd party IFC viewer/ merger).
https://community.graphisoft.com/t5/Collaboration-with-other/Importing-multiple-ifc-buildings-city-m...

[Laszlo Nagy]

I think it is a completely valid expectation of an architect that the other party provides an IFC with a single IfcBuilding hierarchy. If it is not like that, the other party should be responsible for handling the situation. (Possibly, this is something that needs to be specified in the Exchange Information Requirements - EIR document).

There is an app called Bonsai BIM, it is a Blender Add-On. It uses the IFC schema as its file format, and it enables users to directly modify the IFC elements within it. It may be possible to use it to take an IFC file that contains two or more IfcBuildings, and "consolidate" them into a single IfcBuilding. I have not tried it, but I checked some online sources and based on that, it may be possible to do. Of course, I still believe that if someone does this (because they sending party cannot produce an IFC with a single IfcBuilding hierarchy in it), it should be the party sending the IFC, not the party receiving it.

[Ben D]

Hi Laszlo,

No, I am not using merge.  I am hotlinking a structural IFC into the main design project file so that I can check wall thicknesses, clearances, etc.  I do not wish to merge the IFC into my project file.  File->External Content->Place hotlink.  then select module.  the first time, I add a new module (IFC), and it asks me to select the model within the IFC.  I select the first of the two models contained within the IFC.  I place that into my file and adjust it's position.  Now, I need to add the second model, from the same IFC file.  if i try the same process (add new module) and select the same file, it doesnt create a new hotlink, just links me back to the one I created the first time.  There seems to be no way to get it to select a different model within the IFC.  

having to create and merge multiple archicad files, just to get a simple hotlink to work is a lot of hassle and work, especially when the IFC is being regularly updated.  I don't think this is really a good solution to this particular situation.  when a new file comes in from a consultant, I just want to be able to go into the hotlink manager, point it at the new file and hit update.  Yes, I could ask for two separate IFC's - but this is at best an interim solution. 

IFC allows for multiple models (ifcBuildings) in a file.  Archicad should be able to deal with this easily, but can't.  It should be something very simple for graphisoft to fix/implement.

[Ben D]

Hi Cosmin,

Having all the hotlinked elements end up as morphs or objects is a long way from ideal.  makes the file extremely heavy.

Seems clear it's an issue with Archicad's IFC reader implementation that Graphisoft could easily resolve - but perhaps they aren't even aware it's an issue, or if they are, it's not high on their priority list, despite being what should be a pretty easy thing to fix.

[Ben D]

In my situation right now, getting the structural engineer to give me two separate files is the way forward, and I have asked for this.

In the situation in the thread that Cosmin linked to, where they have many more ifcBuildings in one IFC file, this isnt really a viable option. 

All I'm saying is that if the IFC specification allows for multiple buildings, and Archicad already allows you to select one of those buildings (so it can obviously read the format), it's not a big ask from an implementation standpoint to allow you to have multiple hotlinks to the same file referencing different ifcBuildings.   

[Mats Knutsson]

It's a common issue with Tekla... or rather the Tekla operator. They don't connect building parts to a level thus they belong to the "undefined" building. They do it ok the first submit but forgets they have to do it for all new parts they model in future revisions. Sloppy behaviour... we use Simplebim to correct this (very simple) and resave the IFC. In the best of worlds we make a call to the engineer so that they fix it themselves but it's far quicker to correct it ourselves however irritating. Solibri show whatever geometry regardsless of faulty containment.

We experience this so often I recently wrote a python script that checks for this so we know if we need to correct the IFC before hotlinking. 

Also (sometimes) we use Simplebim to remove unwanted parts from the IFC to make it less heavy. As an example we only want to use the columns from the IFC and use Simplebim to remove everything else. Very simple workflow really but again...hassle for us to do someone elses work.