[IFC Export] Problems with IFC (structural view) export

This forum section is only for IFC-related issues
Jesusbill
Posts: 7
Joined: Wed Jun 10, 2020 11:53 pm

Re: [IFC Export] Problems with IFC (structural view) export

Post by Jesusbill »

Hi @balrobs @bernd et al, so I took a look at the file and one thing that needed correction was the "zAxis" property of the curve members. I see that @bernd in his commit has taken care of that, so great to see!! Just to provide the context that this axis must never be parallel to the axis of the curve and should be used to define the orientation of the profile.

Materials, profiles are also missing as well as various connections, some are there but some members have no connection at all. I did some manual modifications and used the "Bonded" scripts that I have created for cases where the connections/supports are not properly defined. This script results in a "bonded" model, let's say applicable to a concrete structure, where there are no double nodes nor internal releases, etc. and it allows to specify a specific z coordinate to create a group of all nodes lying on this horizontal plane, so that one can easily define the support conditions of the base.

With these scripts I did a simple gravity analysis that I show here together with the geometry and mesh created in Salome_Meca. Looks good! :)
test_FreeCAD_1.png
test_FreeCAD_1.png (239.75 KiB) Viewed 5379 times
Test_FreeCAD_2.png
Test_FreeCAD_2.png (545.31 KiB) Viewed 5379 times
PS: @balrobs you say you are not an "instructed developer" but really who is? :lol: don't worry and keep going!
balrobs
Posts: 449
Joined: Fri Apr 24, 2020 8:58 pm

Re: [IFC Export] Problems with IFC (structural view) export

Post by balrobs »

Jesusbill wrote: Wed Jun 09, 2021 8:34 pm Hi @balrobs @bernd et al, so I took a look at the file and one thing that needed correction was the "zAxis" property of the curve members. I see that @bernd in his commit has taken care of that, so great to see!! Just to provide the context that this axis must never be parallel to the axis of the curve and should be used to define the orientation of the profile.

Materials, profiles are also missing as well as various connections, some are there but some members have no connection at all. I did some manual modifications and used the "Bonded" scripts that I have created for cases where the connections/supports are not properly defined. This script results in a "bonded" model, let's say applicable to a concrete structure, where there are no double nodes nor internal releases, etc. and it allows to specify a specific z coordinate to create a group of all nodes lying on this horizontal plane, so that one can easily define the support conditions of the base.

With these scripts I did a simple gravity analysis that I show here together with the geometry and mesh created in Salome_Meca. Looks good! :)
test_FreeCAD_1.png
Test_FreeCAD_2.png

PS: @balrobs you say you are not an "instructed developer" but really who is? :lol: don't worry and keep going!
Hi @Jesusbill,

thank you so much for testing my IFC file!
Considering that my code is at a very early stage and still full of weak points I'm strongly impressed how far you could get with actually generated IFC files from FreeCAD.
Now the points I need to work on in the future are much clearer:
  • correct the "zAxis" of the curve members (probably this error prevented the correct view of my files in some viewers :? )
  • investigate why connection are missing for some members
  • add material properties to surface members
  • add material and profile properties to curve members (my plan is to do this for I and rectangular sections)
In regard to structure supports and internal realeases I will have to investigate further ... ATM I don't see any way to do this in FreeCAD. IMO It will be easier to accomplish this with further processing by an external tool ... we will see :?:

BTW, can you provide me your corrected file please? This could help me :D
balrobs
Posts: 449
Joined: Fri Apr 24, 2020 8:58 pm

Re: [IFC Export] Problems with IFC (structural view) export

Post by balrobs »

I found the reason why connections between structural curved members with coincident nodes where missing :roll:
screenshot.jpg
screenshot.jpg (308.72 KiB) Viewed 5299 times
Now I will tackle down the problems for connections between surface members with coincident edges. When I'm done I will submitt a pull request.
balrobs
Posts: 449
Joined: Fri Apr 24, 2020 8:58 pm

Re: [IFC Export] Problems with IFC (structural view) export

Post by balrobs »

Now also connections between structural surface members with coincident edges should work :D
screenshot.jpg
screenshot.jpg (178.17 KiB) Viewed 5277 times
Here is my pull request: https://github.com/FreeCAD/FreeCAD/pull/4853

Edit: And here my IFC file:
test_structure_with_stairs_SurfaceMember.ifc
(25.77 KiB) Downloaded 118 times
Last edited by balrobs on Fri Jun 11, 2021 7:18 am, edited 1 time in total.
User avatar
bernd
Veteran
Posts: 12849
Joined: Sun Sep 08, 2013 8:07 pm
Location: Zürich, Switzerland
Contact:

Re: [IFC Export] Problems with IFC (structural view) export

Post by bernd »

balrobs wrote: Wed Jun 09, 2021 10:08 pm In regard to structure supports and internal realeases I will have to investigate further ... ATM I don't see any way to do this in FreeCAD. IMO It will be easier to accomplish this with further processing by an external tool ... we will see :?:
Two things I have in mind for years but never started to get my hands on.

- add more structural properties to Arch objects to be able to input loads and connections
- a connection between FreeCAD Arch and FreeCAD FEM

ATM the user would have been to do all this manually. It is possible to input some connections and loads too, but this is very cumbersome for a building analysis model. The idea would be to put in these informations not in FEM but in Arch and than have some connection between Arch and FEM which would generate all the FEM objects automatically.

Furthermore the FEM solver Calculix is limited for beam analysis which is very very important in structural analysis fields.

cheers bernd
User avatar
bernd
Veteran
Posts: 12849
Joined: Sun Sep 08, 2013 8:07 pm
Location: Zürich, Switzerland
Contact:

Re: [IFC Export] Problems with IFC (structural view) export

Post by bernd »

bernd wrote: Mon Jun 07, 2021 9:44 pm
balrobs wrote: Sun Jun 06, 2021 9:58 am - BIMcollab ZOOM shows some problems with StructuralSurfaceMembers for IFC4
I will get in contact with the support.
I got a first answer ...

... Please check if the program is listed in the buildingSMART International Standards Implementation Database.
BIMcollab ZOOM should support files made in any of the programs in this list.



To my surprise either FreeCAD and IfcOpenShell are on the list :D. Hopefully this wil convince them ...


screen.png
screen.png (13.98 KiB) Viewed 5198 times
User avatar
Moult
Posts: 321
Joined: Sat Jan 05, 2019 11:46 am
Contact:

Re: [IFC Export] Problems with IFC (structural view) export

Post by Moult »

Before assuming it is a problem with zoom, we should check it first. The BlenderBIM add-on can help isolate issues. Jesusbill would you like to investigate? There were a number of issues already mentioned, perhaps those should be fixed first? Sorry I haven't had time to investigate myself.
I also blog about 3D rendering, architecture, software and other on thinkMoult.com. RSS / Atom feed available for your convenience.
balrobs
Posts: 449
Joined: Fri Apr 24, 2020 8:58 pm

Re: [IFC Export] Problems with IFC (structural view) export

Post by balrobs »

bernd wrote: Fri Jun 11, 2021 8:14 am
bernd wrote: Mon Jun 07, 2021 9:44 pm
balrobs wrote: Sun Jun 06, 2021 9:58 am - BIMcollab ZOOM shows some problems with StructuralSurfaceMembers for IFC4
I will get in contact with the support.
I got a first answer ...

... Please check if the program is listed in the buildingSMART International Standards Implementation Database.
BIMcollab ZOOM should support files made in any of the programs in this list.



To my surprise either FreeCAD and IfcOpenShell are on the list :D. Hopefully this wil convince them ...



screen.png
Thanks @Bernd for the info!

I will continue to work on the already mentioned issues but it would certainly help if also @Jesusbill could have a deeper look at my latest sample IFC file in order to exclude serious errors contained therein.

Here is the result when loading it into the lastest BIMcollab ZOOM version! Everything I write to the file so far is there except the StructuralSurfaceMembers :?:
screenshot.JPG
screenshot.JPG (56.92 KiB) Viewed 5147 times
Cheers
Jesusbill
Posts: 7
Joined: Wed Jun 10, 2020 11:53 pm

Re: [IFC Export] Problems with IFC (structural view) export

Post by Jesusbill »

@balrobs looks good, I have downloaded the latest version of your model and will investigate as @Moult suggests for any inconsistencies, other than what I wrote the other day.
Regarding my modifications for the analyses I showed, I only changed the IfcStructuralCurveMember entities manually changing the last attribute (zAxis) to be #6 (global X) instead of #7 (global Z). Then I used the ifc2ca script to obtain the json file and in there I made some more modifications to assign materials and profiles missing. So, that is why I did not upload anything. But since I will investigate your latest file in BlenderBIM, I will add materials and profiles in there so that hopefully I will have a more complete IFC file I can share here.
balrobs
Posts: 449
Joined: Fri Apr 24, 2020 8:58 pm

Re: [IFC Export] Problems with IFC (structural view) export

Post by balrobs »

Thanks @Jesusbill for supporting my journey :D Your help is very precious to me!
In the meantime I also managed to write FreeCAD-materials with their structural properties and their structural members relations to IFC.
But I have to make some more tests and maybe reconsider my way of doing it, because at the end I realized that FreeCAD already writes out materials for the architectural model. Since in FreeCAD it's possible to export a hybrid model (both architecture and structure) I have to be careful not to create any duplicates with the materials.
This is my usual FreeCad model with different materials and its (for now) created IFC file (only structure):
Screenshot.png
Screenshot.png (71.5 KiB) Viewed 4959 times
Cheers
test_structure_with_stairs_SurfaceMember.ifc
(27.28 KiB) Downloaded 125 times
Post Reply