Relation between Structural classes and BuiltElements within a stream

Hi @Reynold_Chan,

Was just reading your post on the Structural classes again, as I was trying to find something about the link/relation between the Structural and BuiltElements classes. In this part you shortly mention this:

However, this doesn’t really answer my question.

Namely, I would like to know how you envision a workflow in which BuiltElements (BIM) and Structural elements (FEM) are both of importance, e.g. when you would like to create a basic Revit model from a FEM model, or vice versa, do clash detection after changing a model, etc.

For the first example (FEM model to BIM), I think that we could create Speckle FEM elements (Element1D, Element2D), as well as Speckle BIM elements (Beam, Column, Floor, …) from our own FEM object. However, this immediately gives some interesting questions:

  • Would you include FEM and BIM elements in the same commit, or would it be nice to use separate FEM and BIM branches?
  • Should the BIM element that is created from a FEM element share the same applicationId or not?
  • Would it be useful/good practice to maintain a link between corresponding FEM and BIM element, by keeping a mutual reference between the objects? That can be an actual object reference, or a reference by id.

I realise that this is more a discussion than a simple question, but would be happy to hear your opinion on the link between these different elements. Let me know if anything is unclear. Thanks in advance! @daviddekoning @JdB
You might also have some ideas on this topic :slight_smile:


Hi Rob,

There is sort of a Revit Workflow in where if you export the analytical model, it will inherently export a structural speckle object as opposed to built element objects which can be used to recieve into the structural connectors. Likewise you can import some structural objects back into Revit as Revit has some support for the structural object kit.

There’s no direct relationship as of now, and that’s a good discussion you can bring up with us more in our structural discussion review which is scheduled for on Februrary 9th, 2022. (4-5PM GMT)

Just a personal thought in terms of going back from FEM to BIM directly, We’ve had thoughts about this before in terms of just using clash detection to determine objects change but never directly due to too much differences in modelling practices between the engineers and the drafters. (i.e centerline to centerline for FEM but this isn’t true necessarily for the drafters) . Perhaps your last point might be the best way to do it, by keeping a link between corresponding FEM and BIM elements.


Thanks for your response!

So for the structural connectors, you do use the BuiltElements, not the Structural elements? Haven’t tried the structural connectors myself as we don’t use the currently available structural software.

Also agree that there is of course a big difference between the built and structural element. I would see a conversion between them as a ‘one-time action’, to setup a basic FEM model from BIM or vice versa, not as an actual workflow. Regarding the structural discussion, I’d be happy to join!

For now, we will then go with having a sort of mutual reference between the elements, although that still leaves some things to be sorted out. Appreciate the advice!

We use the Structural Elements, not Built Elements. But Revit analytical will export out structural elements as opposed to built elements. You can see it in action in the tutorial post I just made.

If you are seeing a conversion as a 1-time action, we are supporting that already :slight_smile: . It’s a bit more difficult to constantly do the model upgrade, and the holy grail of the one truth one model for both BIM/FEM neither do I think it’s in our short term goals to support that type of workflow.

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Agree that having one fully complete model should not be the goal (at least not any time soon).
I do think that the branches can play an important role in having proper workflows that could integrate/link BIM and FEM in some way, without having them in one commit.
Moreover, where can I find some more about this one-time-conversion?
Is it used to convert between built and structural elements within the structural connectors?

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There’s no official documentation pertaining to this one-time conversion. But it’s implicitly implied that if you’re going from Revit to ETABS that there are currently no links between the elements, or ETABS to Revit that it will usually be a one directional , hence the “one-time action” .

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