topic Re: Base Quantities with IFC export in Collaboration with other software

Base Quantities with IFC export

stefan — Tue, 09 Jan 2018 10:57:15 GMT

I was wondering which elements are actually capable of receiving Base Quantities upon IFC export?

E.g. a column exported as IfcColumn has Base Quantities, but when classified as IfcPile, the same column does not carry Base Quantities.

Re: Base Quantities with IFC export

stefan — Mon, 22 Jan 2018 15:12:44 GMT

Is this a limitation in ARCHICAD or a limitation in the IfcElementQuantities class? I don't think that IFC is limiting us here.

An IfcElementQuantity defines a set of derived measures of an element's physical property. Elements could be spatial structure elements (like buildings, storeys, or spaces) or building elements (like walls, slabs, finishes). The IfcElementQuantity gets assigned to the element by using the IfcRelDefinesByProperties relationship.

Re: Base Quantities with IFC export

Laszlo Nagy — Tue, 23 Jan 2018 12:38:18 GMT

I asked this from the guys at GS HQ and they told me this is a limitation of IFC.
So yes, an IfcColumn has base quantities, but an IfcPile does not:

http://www.buildingsmart-tech.org/ifc/IFC2x3/TC1/html/ifcsharedbldgelements/lexical/ifccolumn.htm
http://www.buildingsmart-tech.org/ifc/IFC2x3/TC1/html/ifcstructuralelementsdomain/lexical/ifcpile.htm

BuildingSmart documentation contains these informations about what IFC Element has what kind of Base Quantity information in it. ARCHICAD then has to implement these capabilities/limitations to be IFC-compliant.

Re: Base Quantities with IFC export

stefan — Tue, 23 Jan 2018 16:02:52 GMT

OK. I see. I can understand this, but it is a bit unfortunate, as we now may have to populate custom IFC-fields with these quantities (I think I can map them from the IFC Scheme manager).

Solibri calculates quantities when loading, but that occurs outside of the IFC file. SimpleBIM also calculates quantities and can store them as custom property sets.

But these are not a real solution for our case (allowing architects to upload IFC models with quantities for LCA evaluation).