Assigning IfcRels in Bonsai
My colleagues and I are currently using Bonsai to postprocess IFC4.3 bridge files coming from another BIM-authoring software platform. In Bonsai, we are correcting any errors in spatial organization/relationships, as well as class and property assignments.
One thing that has us stumped is how to use Bonsai to create the correct IfcRel of a reinforcing IfcElementAssembly to a corresponding IfcBeam, based on the Alignment-based View [AbV]. Essentially, we're trying to merge models of the concrete reinforcing elements with the model of the concrete elements being reinforced.
Any suggestions?
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There is unfortunately no standard on how to relate reinforcement to elements, see this discussion: https://github.com/buildingSMART/IFC4.3.x-development/issues/205 - the best guess right now is IfcRelAggregates if integral to the element or IfcRelConnects if it isn't.
We have full support for IfcRelAggregates, but we don't yet have an interface for generic rel connects (only port connects, and path connects). However, we do have API support for it so you could script it if you want.
ok. Thanks @Moult
It appears that this is the answer:
https://ifc43-docs.standards.buildingsmart.org/IFC/RELEASE/IFC4x3/HTML/concepts/Object_Composition/Aggregation/Element_Composition/content.html
Yes, aggregates as mentioned above is one of two proposed ways, and is definitely the more adopted (few tools have good connect rel support). But there is nothing explicit in the IFC documentation which is a shame, and it also has the disadvantage of requiring a third non geometric element as the aggregate parent.
Interestingly, the Element Composition CT 4.1.4.1.2 explicitly states its applicability is to IfcBeam. Does this suggest that IfcRelAggregates is not the correct way to connection reinforcement to columns, walls, footings, stairs, railings, or any other concrete component that is being reinforced? Why applicable only to IfcBeam?
Poorly developed and written specification due to lack of organization and focused effort
did you found the solution how to create the IfcElementAssemebly after selecting multiple model elements and its specific spatial node?
I'll have to investigate. We've moved on. Soon I'll post revised results on https://github.com/jwouellette/US_BIMforBridgesAndStructures_DataExchanges
Everyone can sort it out after that.
Still waiting on bSI to finish the MVD work and the vendors to provide proper implementations... but I'm not holding my breath.
this is not the standard way to implement the ifc4.3, they are only using the IfcBuiltElement for everything which is not ideal for infrastructure proejcts.
@tata827 What are you talking about?
@tata827 the breakdown structure looks like this
