Model 1: EOR-Designed Connections
In this model, the engineer of record designs every connection and shows the result — plate sizes, bolt patterns, weld sizes — on the structural drawings. The detailer's role is to translate those designs into shop drawings without modification. This model gives the fabricator the clearest scope and the lowest risk, but it requires the EOR to do significantly more design work. It is most common on publicly procured structures, institutional buildings, and projects where the owner's standard practice requires EOR accountability for all structural decisions.
Model 2: Delegated Connection Design
The EOR specifies design loads (reactions, moments, axial forces) on the structural drawings and delegates the detailed connection design to the fabricator or their engineer. The fabricator is responsible for engaging a licensed engineer to perform and stamp the calculations. The detailer can produce the drawings, but cannot stamp the calculations unless they employ a licensed PE. This model is common on design-bid-build commercial projects and typically produces the most RFIs when loads are missing or ambiguous.
Model 3: Standard Connection Criteria
Some EORs specify standard connection types — 'all simple shear connections: AISC standard shear tabs, designed by fabricator for loads shown' — and leave both selection and design to the fabricator. This is the least defined model and the most prone to disputes. If loads are not shown, the detailer has no basis for design and must RFI every non-obvious connection. State the governing design model in writing in the contract before detailing begins.