Preliminary Structural Sizing — early-stage structural sizing preliminary workflow
Preliminary Structural Sizing produces concept-stage member sizes—beams, columns, slabs—from the architectural Revit model for early feasibility, BOQ, and architect-side coordination. It applies each firm’s preliminary-sizing rules, keeps detailed design and sign-off with the structural engineer of record, and is available now as a Labs engagement under MSA + Appendix.
- Concept-stage member sizes produced from the architectural model in hours instead of weeks.
- Sized structural concept feeds early BOQ and architect–structural coordination conversations from Day 1.
- Detailed design, code compliance, and the engineering stamp remain the structural engineer of record’s responsibility.
From “ask the structural engineer” to read-the-model.
Workflow today
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01
Architect ships concept
Week 0. The architect locks the massing model and floor plates in Revit or Rhino, then exports a coordination set. Structural grids are tentative, spans are approximate, and there is no reliable basis for early BOQ or structural cost checks.
Week 0 -
02
Architect emails the structural engineer
Week 1. The architect emails the structural engineer: “Can you size members for the BOQ?” The engineer fits the request between live projects, often recreating parts of the model in their own Revit Structure or analysis tool just to run a quick pass.
Week 1 -
03
Sizing comes back days later
Week 2+. A senior structural engineer spends hours assigning preliminary sizes to beams, columns, and slabs, based on internal rules of thumb and past projects. The result arrives as marked-up PDFs or a rough Revit structural model that still needs refinement before any formal design step.
Week 2+ -
04
BOQ delayed; coordination delayed
Week 3+. The architect’s BOQ and early cost plan wait on the sizing pass. Coordination with structure drifts a full design cycle, and the team postpones conversations about spans, transfer beams, and column locations until the structural engineer has time to respond.
Week 3+
Workflow with VitruAI
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01
Run the agent on the architectural model
Day 1, ~30 min. The team runs the Structural Sizing Agent on the architectural Revit model and the firm’s preliminary-sizing rules—typical spans, span-to-depth ratios, and assumed floor loadings. The workflow fits alongside existing Revit integration practices, using the same shared parameters the BIM team already maintains.
Day 1, ~30 min -
02
Agent emits sized members
Day 1. The workflow produces sized beams, columns, and slabs as a structural concept model, tagged with the specific preliminary rule applied to each member. Outputs can drive early BIM-to-BOQ automation and give the architect a structurally informed starting point without touching detailed design or code checks.
Day 1 -
03
Architect reviews and uses for BOQ / coordination
Day 1–2. The architect and BIM manager review the sized members, adjust any outliers, and lock a concept-stage structural scheme for BOQ and coordination. The model supports early structural–architectural coordination discussions—span changes, column shifts, and core adjustments—before the structural engineer invests detailed design hours.
Day 1–2 -
04
Structural engineer refines for detailed design
Week 1+. The structural engineer of record imports the concept into Revit Structure or an analysis tool, treats the sizes as a starting point, and then performs full code-compliant design and documentation. They retain full responsibility for calculations, code compliance, and the engineering stamp, using the preliminary pass to focus their effort where it matters most.
Week 1+
Preliminary Structural Sizing — FAQ
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Does this replace the structural engineer?
No. This workflow produces preliminary, concept-stage member sizes for feasibility and BOQ only. Detailed design, code compliance, and the engineering stamp remain entirely with the structural engineer of record, who uses the output as a starting point rather than a finished design. The intent is to shorten the architect-side feasibility loop, not to change the structural engineer’s scope or liability.
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What design code does the sizing apply?
Each Labs engagement calibrates the workflow against the firm’s own preliminary-sizing rules, usually span and depth ranges drawn from historical projects and past designs. It does not run full code-compliant calculations or replace a proper structural analysis package. The structural engineer still applies the relevant building code and formal design methods before issuing any signed documents.
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Does this output go into the structural engineer’s tool?
Yes. The preliminary structural sizing outputs to Revit Structure via the VitruAI + Revit integration or as IFC for other tools. The structural engineer can then refine member sizes, adjust framing layouts, and run full analysis directly in their preferred environment. This keeps the early pass aligned with how the engineer already documents and coordinates structure.
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How does this relate to code compliance checks?
Preliminary structural sizing focuses on member sizes for feasibility and BOQ, not on formal code checks. For building code questions on the architectural model, firms pair it with the Code Compliance Agent to review layouts against the relevant regulation library. Structural code compliance remains part of the structural engineer’s detailed design workflow, outside this preliminary sizing pass.
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Can this link into broader BOQ and coordination workflows?
Yes. Firms typically connect preliminary structural sizing into their BIM-to-BOQ automation pipeline so early quantities reflect a realistic structural scheme. They also use it alongside structural–architectural coordination workflows to test span changes or column moves while still at concept stage. The Structural Sizing Agent sits as a tool the architect and structural engineer both use, not as a replacement for either discipline.
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When does this ship as a productised release?
This workflow sits on the roadmap and is available now as a Labs engagement under MSA + Appendix. Productisation depends on calibrating against multiple firms’ preliminary-sizing rules and confirming it fits different regional practice patterns. Early partners help define templates for rulesets, Revit families, and export formats that later customers can adopt with less configuration.