Estimating delegated connection design

How the AISC Code defines it

AISC 303-22, the Code of Standard Practice, is the default trade-practice document for most U.S. structural steel contracts. Section 3.2.3 says the owner's designated representative for design (the ODRD, usually the structural engineer of record) must indicate one of three options for each connection:

Option	Who designs	What the estimator should expect
Option 1	ODRD shows the complete design in the structural documents	Plates, welds, bolts and geometry are on the drawings. Take them off.
Option 2	An experienced steel detailer selects or completes the connection from tables, schematic details or AISC Manual tables	Detailing cost, not engineering. Material depends on loads shown.
Option 3	A licensed engineer working for or retained by the fabricator designs it	Engineering fee, substantiating calculations, review cycles and material you can't see yet

Two points from the Code's commentary matter at bid time. First, projects can mix options by connection type. Shear tabs might be Option 2 while moment and brace connections are Option 3. Second, Option 3 is not normally meant for connections a detailer can select without practicing engineering. If a spec delegates "all connections" on a simple frame, that's worth a question.

Find it in the documents

Read these before you count anything:

• Structural steel specification (usually 05 12 00). Search for "delegated design," "connection design by fabricator," "licensed engineer," "signed and sealed calculations," and "substantiating connection information."
• Structural general notes. Notes like "connections not shown shall be designed by the fabricator's engineer for the reactions indicated."
• Plans and schedules. Beam end reactions, moment and axial forces or a connection force schedule mean someone other than the EOR is expected to complete the connections.
• Submittal section (01 33 00 and the steel spec). Calculation formats, sealing requirements and review periods.
• Seismic requirements. If the lateral system falls under AISC 341, check which connections are prequalified, which need testing or special detailing, and who is responsible.

Conflicts are common. The drawings may fully detail some connections while the spec delegates "all connections not shown." Write down which option you're assuming for each connection type.

What the EOR owes you, and the RFI if it's missing

When Option 2 or 3 is specified, AISC 303-22 requires the structural documents to provide:

• Project-specific conceptual connection details for the order of magnitude of forces.
• Any restrictions on connection types.
• Loads: shears, moments, axial forces and transfer forces, enough to design the connection.
• Whether loads are given at service or factored level.
• Whether LRFD or ASD governs.
• What substantiating connection information is required.

If loads say "use 50% of uniform load capacity" or reactions are missing, the engineering scope is undefined. Ask by RFI. If there's no answer by bid day, state your load basis in the proposal.

Scope the engineering

Price the engineering from a quote, not a guess. Give your connection engineer the drawings, specs and a connection count by type:

1. Count connection types: simple shear (single plate, double angle, end plate), moment, vertical and horizontal bracing, column splices, base plates, truss and transfer connections, and specials.
2. Count unique conditions, not just instances. Engineering effort scales with the number of distinct designs. Detailing and fabrication scale with instances.
3. Representative samples. Under Option 3, the fabricator must submit representative samples of the substantiating information for all connection types early, and the ODRD confirms them in writing. That's an extra submittal and review step before approval documents. Put it in your schedule and your fee.
4. Review cycles. Assume a number of resubmittals and say so.
5. Sealing and licensing. The engineer needs a license in the project's state. The Code's commentary discourages sealing every shop drawing sheet. If the spec requires it, it adds cost and should be clarified.

Price the connection material and risk

The connection material on an Option 3 job isn't drawn yet, so the estimate carries an assumption. Common ways to handle it:

• Per-connection allowance by type from your history, for example pounds of plate and bolts per typical shear connection, per moment connection and per brace connection.
• Percentage of member weight, a quick rule of thumb some shops use for simple framing. It's less reliable on braced or moment frames, where the connections can be a large share of the shop hours.
• Stiffeners and doublers. Column web doublers and stiffeners at moment connections are expensive. AISC 303 Section 3.2.4 covers member reinforcement at connections. Find out whether the EOR has already checked for it or left it to the connection designer.

Illustrative scope for a mid-size braced frame building (Option 3 for moment and brace connections):

Connection type	Unique designs	Instances	Basis
Single-plate shear	14	620	Option 2 from AISC Manual tables
Moment (flange plate)	6	48	Option 3
Vertical brace gusset	9	72	Option 3
Column splice	3	40	Option 2
Base plates	5	64	Option 1 (shown)

Get the engineering quote on the 15 Option 3 designs plus the representative-sample submittal and two review cycles. Carry material by instance and type. Shop hours follow the instances.

Connection design software

Connection engineers use software such as IDEA StatiCa, RAM Connection and modeling-integrated tools to design and document standard connections efficiently. Software can lower the engineer's fee and turnaround. It doesn't tell you what's delegated, how many connections there are, or how many review cycles to expect. Those are still estimator inputs.

Write the basis into the proposal

Your proposal should say:

• Which connection types you've treated as Option 1, 2 or 3.
• The load basis you assumed where loads weren't given.
• The number of submittal and review rounds included.
• That changes to design loads, framing or connection types after award will be priced as changes.
• Whether member reinforcement (stiffeners, doublers) is included and on what basis.

That paragraph is what lets you recover cost later if the review process or the loads change.

Where RenderDraw fits

Counting connections by type across framing plans, elevations and details is slow. RenderDraw's AI takeoff proposes members and connection-related quantities with the source sheet on every row and sends uncertain items to review, which gives you the count your engineering quote and material allowance depend on. You decide the options, allowances and risk.