Direct Answer
A federated model is a combined BIM that links individual trade models (structural, architectural, mechanical, electrical, plumbing) into a single coordination environment without merging them into one file. Each trade maintains and updates its own model; the federation just references them together. The GC's BIM coordinator typically manages the federated model, but the structural team (detailer/fabricator) is responsible for keeping the structural component current.
Full Explanation
Federated models are assembled in Navisworks, Revizto, Trimble Connect, or BIM 360. Each IFC or native file is loaded as a separate layer, preserving each trade's ownership of their model. Clash detection runs across all layers. For steel, maintaining the structural layer means delivering timely IFC updates whenever the model is significantly revised. A stale structural layer in the federated model leads to coordination decisions based on old information.
What This Means for Your Shop
Your obligation in a federated BIM workflow is to keep the structural IFC export current and push updates to the CDE on the agreed schedule. Falling behind means other trades are coordinating around an outdated steel model and may generate conflicts that don't actually exist — or miss real ones.
Common Mistakes
Submitting the initial IFC and then never updating it, even as the model goes through multiple revisions. The federated model must reflect the current steel design, not the original design.
Recommended Process
Agree on an IFC update schedule at project kickoff (typically matching major design milestones). Set a calendar reminder to push updated IFC exports to the CDE at each milestone. Notify the BIM coordinator when updates are posted.