ifc2ca short presentation
Given that today the time went by very quickly with all the interesting questions that were raised I did not have the opportunity to show anything about IFC2CA, I made this video to show how to create all the scripts and run a simple portal example that is the official file from buildingSmart. If there are any questions or anyone wants to know more let me know, I will be glad to answer
Shout-outs to people who wanted to hear about this: @yorik @brunopostle @theoryshaw @bitacovir
Am I right to think that we are not ready to author these IFC files in blender or freecad yet? I imagine that indicating fixity and connections has a special procedure.
Did I also hear that there are IFC objects that are otherwise identical? E.g. ifcmember and ifcstructuralcurvemember , and we have to use one or the other?
Amazing @Jesusbill thanks a lot for recording that!
There is not much work needed in FreeCAD to be able to export such IFC files with members and nodes, basically most of what's needed is there already. We can already build beams and columns with a "node" axis, which can be connected to other members. I'll try to build a prototype...
@brunopostle What I gathered is that you have two categories of objects, structural ones (IfcStructural*) and "not structural ones" (Walls, columns, members,...). You can export both in a same IFC file (that is, two IFC objects per column/beam), but there is no way to relate them together AFAICS (But, after all, why couldn't we use an IfcRelAssociates here? That needs some testing)
And in codeaster only the structural ones will be used.
@brunopostle Yes we do not have a front-end support for the moment, this is all back-end development.
Yes it needs to indicate a geometry, associate connecting elements and define connectivity conditions (for example internal releases for pinned ends in beams) and external conditions (fixity) for the connection. The external supports shouldn't be a great problem but the internal connections could be potentially a pain in the a.. in the sense that all internal connections must be defined in the ifc file which means that it will be needed to find and define intersection geometries between elements (for 1D (line) elements maybe easier but for 2D (surface) elements more challenging.
It is actually mandatory to use the IfcStructuralItem entities (IfcStructuralMember and IfcStructuralConnection) which are then part of an IfcStructuralAnalysisModel which is then part of the IfcProject but independent of the IfcBuilding etc. (here all the entities of the structural analysis domain https://standards.buildingsmart.org/IFC/RELEASE/IFC2x3/FINAL/HTML/ifcstructuralanalysisdomain/ifcstructuralanalysisdomain.htm).
I think one can then link an IfcStructuralMember to an IfcMember, while it is also possible to have a 3D "Body" representation of an IfcStructuralMember, but I am not very acquainted with all these possibilities for the moment.
@yorik this is great to hear!
@Moult how would you relate an IfcProduct with its counterpart IfcStructuralItem? Any idea? We could define an #osarch standard here :)
@yorik could it be IfcRelAssignesToProduct? (https://standards.buildingsmart.org/IFC/RELEASE/IFC4/ADD2_TC1/HTML/schema/ifckernel/lexical/ifcrelassignstoproduct.htm)
Could make sense to you?
@Jesusbill @yorik it is indeed RelAssigns, although I could not find it explicitly spelled out in the IFC documentation. I've also confirmed with Jon Mirtschin (from Geometry Gym, who has a structural background). In particular, this is his code for reference.
Yes, i used an IfcRelAssignsToProduct, looks exactly made for that!
I've created a page for documenting and/or linking to this work https://wiki.osarch.org/index.php?title=Structural_Analysis_Format_(SAF)
That would be cool to do this. Actually I have never seen this. I do not know if this even is intended to do. AFAIK it is not intended to save Structural Analysis View and Coordination View into one file. Although structural engineering software AxisVM exactly does it, but they do not relate them each other. If we would relate them we would go to another step. We could define attributes to the geometry as we do in FreeCAD FEM transfere them to the analysis mesh and use the mesh for analysis. ATM there are two worlds in IFC, the geometry and the analysis mesh. But in most analysis software one defines solid geometry too. Just the axis are connected in any analysis software.
@bernd IfcRelAssignsToProduct is the way to do it... we just need to... do it :D