Direct Answer
A structural digital twin is a continuously updated virtual model of a structure that reflects its actual state — combining the as-built BIM model with sensor data, inspection records, and maintenance history. For fabricators, digital twin workflows typically mean delivering an as-built LOD 500 model at project close-out, which the owner uses for ongoing facility management.
Full Explanation
In practice for structural steel, a digital twin workflow means: (1) The Tekla fabrication model is updated to reflect all as-built changes (field modifications, substitutions). (2) The as-built model is delivered as an IFC file to the owner. (3) The owner links the model to their facility management system (Archibus, IBM Maximo, Autodesk Tandem). (4) Maintenance records, inspection reports, and sensor data (strain gauges, tilt sensors) are linked to model elements. The fabricator's role ends at delivering an accurate as-built model, but understanding this workflow helps you price LOD 500 deliverables correctly.
What This Means for Your Shop
As-built model delivery is increasingly an owner requirement on large institutional and infrastructure projects. If this deliverable is in your scope, budget time to update the Tekla model with all field revisions throughout construction — not as a document-after-the-fact exercise at project close.
Common Mistakes
Treating the as-built model as a paperwork exercise rather than a maintained record. An as-built model that doesn't actually reflect field conditions is useless for the owner and creates liability if it's used for future modifications.
Recommended Process
If as-built deliverables are in your contract, establish a process for documenting field modifications as they occur — not at project close. Assign the detailer to update the Tekla model with each field change when it is issued as a revised drawing.