buildingSMART Forums

Does these attributes are defined by buildingSMART or not?

Good evening everyone.
i was working on IFC export , and faced certain new issue in finding some data in IFC files.
ISSUE1: which Attribute/Entitie store the clear cover or side cover etc. Means covers provided during reinforcement of members like column, beam, slab etc.
ISSUE1: The spacing between the rebars i.e if we provide 10 dia @100c/c where this 100 will store in IFC,
Some software transfer then in proxy or ifcpropertysinglevalue but it is not extracted or connected to any members so impossible to use them.

Major issue : We give material to Structure members as M 20, M25 etc for concrete and Fe500 for Rebars
But again nothing is exported to IFC . we get concrete as label in IFCMATERIAL and again some software give M25 in proxy.
we have attritube like IfcMechanicalMaterialProperties , IfcMechanicalConcreteMaterialProperties etc Why software’s are not using these to store the properties of materials.
Thank you.

Good morning @Tandeep - do you mind attaching an IFC file that you have exported as an example, and also clarifying BIM authoring tool you are using to model your building?

Good Evening
I am sending you a slab (ifc) which is having reinforcement in it.
This file is model in FreeCAD.
I also tried in revit and tekla, results were same.
123.ifc (602.4 KB)

Anyone here having any knowledge about this.
Please help.

AFAIK, it’s not IFC that is to blame, but most viewers don’t show you material information, apart from their name. I know for a fact that I can export the full information about the material from ARCHICAD into IFC, especially now for IFC4, and I can confirm that the IFC file contains this information. But there is no way I can see these properties in e.g. Solibri or BIMcollab Zoom, alas.

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I am not blaming IFC.
Its software which are not doing there work.
buildingsmart must take strict action against them because they are causing too much problems during export/import.
I had also used the ARCHICAD but nothing good found in IFC about materiel, just i got is name nothing else.
Can you share me a small file where material and all its properties are exported by ARCHICAD in IFC

But if we talk about spacing of rebars, i had not found any entity/attributes in IFC schema which store spacing between 2 or more bars.

Here is a fragment of Material Properties as exported from ARCHICAD into IFC4, with the translator set to export Material Properties

#228= IFCMATERIAL('Reinforced Concrete - Structural',$,$);
#235= IFCMATERIALPROPERTIES('Pset_MaterialThermal',$,(#239,#246),#228);
#239= IFCPROPERTYSINGLEVALUE('ThermalConductivity',$,IFCTHERMALCONDUCTIVITYMEASURE(2.5),$);
#246= IFCPROPERTYSINGLEVALUE('SpecificHeatCapacity',$,IFCSPECIFICHEATCAPACITYMEASURE(1000.),$);
#247= IFCMATERIALPROPERTIES('Pset_MaterialCommon',$,(#249),#228);
#249= IFCPROPERTYSINGLEVALUE('MassDensity',$,IFCMASSDENSITYMEASURE(2400.),$);
#250= IFCMATERIALPROPERTIES('AC_Pset_MaterialCustom',$,(#252,#253,#254,#255,#256,#257,#258,#259,#260),#228);
#252= IFCPROPERTYSINGLEVALUE('Embodied Energy',$,IFCTEXT('2.33 (MJ/kg)'),$);
#253= IFCPROPERTYSINGLEVALUE('Embodied Carbon',$,IFCTEXT('0.242 (kgCO\X2\2082\X0\/kg)'),$);
#254= IFCPROPERTYSINGLEVALUE('ID',$,IFCTEXT('ST-06'),$);
#255= IFCPROPERTYSINGLEVALUE('Description',$,IFCTEXT('Description'),$);
#256= IFCPROPERTYSINGLEVALUE('Manufacturer',$,IFCTEXT('Manufacturer'),$);
#257= IFCPROPERTYSINGLEVALUE('Participates in Collision Detection',$,IFCBOOLEAN(.T.),$);
#258= IFCPROPERTYSINGLEVALUE('Name',$,IFCLABEL('My Name'),$);
#259= IFCPROPERTYSINGLEVALUE('Category',$,IFCLABEL('My Category'),$);
#260= IFCPROPERTYSINGLEVALUE('Description',$,IFCLABEL('My Description'),$);

AC23_concretemorph_IFC4Materials.ifc (8.7 KB)

And here is a fragment in IFC2x3… Properties are there in the IFC export.

#236= IFCMATERIAL('Reinforced Concrete - Structural');
#239= IFCSTYLEDITEM($,(#191),$);
#241= IFCSTYLEDREPRESENTATION(#136,$,$,(#239));
#243= IFCMATERIALDEFINITIONREPRESENTATION($,$,(#241),#236);
#247= IFCRELASSOCIATESMATERIAL('1prswmCKtd8CDhgsEfCIVS',#12,$,$,(#217),#236);
#250= IFCPROPERTYSINGLEVALUE('Renovation Status',$,IFCLABEL('New'),$);
#254= IFCPROPERTYSET('20n$Y4ocGFyd$cEFhrKhFB',#12,'AC_Pset_RenovationAndPhasing',$,(#250));
#259= IFCRELDEFINESBYPROPERTIES('1bWoYR_9S5uFHcyLAgC1MI',#12,$,$,(#217),#254);
#263= IFCPROPERTYSINGLEVALUE('ThermalConductivity',$,IFCTHERMALCONDUCTIVITYMEASURE(2.5),$);
#264= IFCPROPERTYSINGLEVALUE('SpecificHeatCapacity',$,IFCSPECIFICHEATCAPACITYMEASURE(1000.),$);
#265= IFCPROPERTYSINGLEVALUE('MassDensity',$,IFCMASSDENSITYMEASURE(2400.),$);
#266= IFCPROPERTYSINGLEVALUE('Embodied Energy',$,IFCTEXT('2.33 (MJ/kg)'),$);
#267= IFCPROPERTYSINGLEVALUE('Embodied Carbon',$,IFCTEXT('0.242 (kgCO\X2\2082\X0\/kg)'),$);
#268= IFCPROPERTYSINGLEVALUE('Name',$,IFCTEXT('Reinforced Concrete - Structural'),$);
#269= IFCPROPERTYSINGLEVALUE('ID',$,IFCTEXT('ST-06'),$);
#270= IFCPROPERTYSINGLEVALUE('Description',$,IFCTEXT('Description'),$);
#271= IFCPROPERTYSINGLEVALUE('Manufacturer',$,IFCTEXT('Manufacturer'),$);
#272= IFCPROPERTYSINGLEVALUE('Participates in Collision Detection',$,IFCBOOLEAN(.T.),$);
#273= IFCPROPERTYSINGLEVALUE('Name',$,IFCLABEL('My Name'),$);
#274= IFCPROPERTYSINGLEVALUE('Category',$,IFCLABEL('My Category'),$);
#275= IFCPROPERTYSINGLEVALUE('Description',$,IFCLABEL('My Description'),$);

AC23_concretemorph_IFC2x3Materials.ifcxml (38.1 KB)

Firstly your IFC is Zero , it not having having any member to whom material was assigned.

The values which are in IFCPROPERTYSINGLEVALUE are only for this ifc file and software we imported from.
It will not import in any other software and not viewed in viewers.
building smart have a particular entity for material properties but they are not used by any software’s.
as i already told

we have attritube like IfcMechanicalMaterialProperties , IfcMechanicalConcreteMaterialProperties etc

why they are not used by software or ARCHICAD you are talking about.

Hi @tandeep, sorry for the late reply. I see you are using FreeCAD. I can help you with this, but I will need more information, but this forum is not the right place for detailed individual vendor support.

Can you please post here: https://forum.freecadweb.org/viewforum.php?f=39

Please include:

  1. A copy of your FreeCAD file that we can use to replicate the issue
  2. Which version of FreeCAD you are using
  3. Attach the IFC you have exported from it
  4. Explain the issue again on that forum post for completeness.

Please also send me an email (I have messaged you my email address) with the thread link, and I will help you debug your issue and make sure that FreeCAD authors the IFC file as expected.

Hi @Moult
I am not just talking about FreeCAD.
I had examined this in Revit, ArchiCAD, FreeCAD, AecoSIM, etc , basically i checked these on main BIM softwares but no one is providing me that information.
If we talk about spacing between the 2 bars, i checked and find no ifc attribute which can store spacing between 2 bars.
For Materials properties we have attributes but no software is using that attributes, so why building smart is not taking any action on them.

Well i am also there on FreeCAD forum and will discuss there also.

It sounds to me like those participating in this conversation are talking past each other. I think I understand Tandeep’s frustration. He is asking about two particular properties of reinforced concrete: the clear distance between reinforcing bars in a member (bar spacing), and the distance from the bars nearest the outside face of a reinforced concrete element to that face of the element (the concrete cover of bars). It has been said that the problem is not with IFC. However, the lists provided by stefkeB of properties exported to IFC4 do not show any data representing these distances (or much else in the way of geometric properties for that matter), so they do not address Tandeep’s problem.

I would think the first question to ask is whether the source model includes data fields representing spacing and cover, or whether those distances are only modeled as 3D geometry. If the latter, the user of the IFC file would need to find those two values in the geometry of the IFC file, rather than in the list of IFCPROPERTYSINGLEVALUEs, or Tandeep’s modeling software would need to automatically interpret those values from the model geometry, create property data fields for them, and insert the values there, or Tandeep would need to create those fields and enter the data manually before exporting to IFC.

If the IFC file must contain numerical values for cover and spacing, the second question to ask is whether this translation of model geometry to numerical values for cover and spacing is happening, or the appropriate fields and values have been vested in the source model some other way. If not, then the problem is that the property data Tandeep is looking for in the IFC export never existed in the modeling software to begin with. If it is happening, and there are numeric properties with the correct values and units representing these two distances in the source model, then one could deduce that something is getting lost in translation, and look for the source of the problem.

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@Lighthart

I would think the first question to ask is whether the source model includes data fields representing spacing and cover

I had tried this on many BIM software which provides rebars facility.
Data is entered in that software, but nothing is exported to IFC , as till mine study i did’t found any attribute given by BuildingSmart which stores values like spacing between bars and cover etc.

So First job is of BuildingSmart to define particular attribute and syntax of it,
Then only software vendors will implement it .
Thank you

IFC files takes numerical data also Like we can talk about XDim, YDim or Depth and many more also.
If we talk about Units they are well arranged in IFC , we get that is IFC that units are in mm or metre and then every values are according to it only .

Rest you have any other query in my problem then please ask i will be happy to answer it.

Thanks for your reply.

And if we talk about implementation of IFC i had tried maximum BIM software that are available in market , They all are useless in structure point of view, as too less structure engineers are working on IFC implementations that’s why IFC owners don’t know minor/major problems of reinforcement, and which structure engineers are facing all way.
NO authority is taking care of it .

Looking back at your question, I see e.g. following IFC PropertySets.

Pset_ConcreteElementGeneral.ConcreteCover at the element level (e.g. IfcWall)
Pset_ReinforcingBarCommon.BarSpacing at the rebar level (e.g. IfcReinforcingBar)

The question is if you can control your structural design software to fill those in automatically. Not sure if many software gives you that control, but it is possible with e.g. ARCHICAD.

Ok, I will try to check it. and will see what will import in IFC.