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What is the best way to design/detail a large weldment

Question asked by Jeffrey Gardiner on Jan 19, 2020

Looking at designing/detailing a large structural steel weldment framing system.  The design requires a series of erection drawings and fabrication drawings.  I'm comfortable with weldments and assemblies, but looking for the best way to not replicate design efforts.  Specifically:


Fabrication Drawings: need to show each individual part in a welded body (for example a column, its baseplate and any welded stiffeners).  Dimensions/material for each item are shown on a cut list.  The fabricated welded-body (e.g. sub-weldment) would be assigned a part number or mark number (e.g. Column-1A) for steps in the assembly of the larger structure.


Erection Drawings: show how each fabricated body (above) would be assembled into the larger structure.   The erection drawings should show the 10+ items that need to be bolted together, not the 200+ items that were welded together.


I'm looking for the best way to complete this design/detailing effort.  I've previously run a single weldment part file with a single cut list.  This has been sufficient for most of my weldment efforts. 


For this project I have two different ideas, and am looking for feedback:


Option 1:  Design the entire structure as a single weldment part.  Use the solidworks sub-weldment feature to denote fabricated bodies that are welded together in the shop:

  • Pros: 
    • Work in a single part file to minimize design efforts and external references
  • Cons:
    • Would most likely require a single (huge?) drawing file to keep cut list items and cut-list numbering consistent throughout the effort
    • I cannot find an easy way to quickly dump a sub-weldment to a drawing view and detail it.  The only way I could show the sub weldment is using the "select-bodies" feature.  I was thinking about saving to an external part, but that looks to be a manual effort to select bodies and once its saved out from the parent, the file will no longer update.


Option 2:  Have a top level assembly for the entire project. Each shop-fabricated piece (sub-weldment) is a part, with its own shop drawing and cut-list. Each part is assigned a "mark number" for the erection drawing.  The erection drawing is of the assembly with with a parts-only B.O.M.  Parts are identified by the "mark number". If needed, an indented B.O.M. could assist the fabricator with material takeoff.  Option 2 seems like more work during the modeling phase, but more advantageous during the drawing/detailing phase.


  • Pros: 
    • Separate identifiers for cut list items and fabricated bodies
    • Individual drawing files for each part, keeps drawing file size and load time down.  
    • Use assembly features such as smart fasteners (maybe)
    • IMO, assembly mates are more friendly than MBD move/body/copy mates
    • Cut list updates aren't crippling
  • Cons:
    • Kind of...goes against the entire idea/simplicity of the weldment process.  Some parts (e.g. braces) would be composed of a single weldment body.


I'm leaning toward Option 2, but haven't done this approach before.  I would really like to hear everyone's opinion on how they handle large multi-body weldments of steel structures. 


(P.S.  I've read responses in the forum about using, but their website is down so I don't know about that add-in)


Thanks for your insights!