Why Steel Doesn't Fit
Field fit-up problems have identifiable causes:
- Hole pattern error on a fabricated member — the bolts don't align with the mating connection
- Member length error — the member is too short to reach both connections or too long to fit in the space
- Cope dimension error — the beam end cannot clear the column flange
- Foundation error — anchor bolts are out of tolerance relative to the anchor bolt plan
- Design change not incorporated — a revised drawing was issued but the old drawing was fabricated
- Model error — the connection geometry looked right in the model but the 3D reality doesn't match the model's assumptions
The Documentation and Notification Sequence
When steel doesn't fit: (1) stop; (2) photograph the condition from multiple angles; (3) notify the GC, detailing PM, and EOR in writing within 2 hours; (4) identify the drawing revision that was used for fabrication and confirm whether that revision was the current approved revision; (5) request engineering guidance before any field modification is made. This sequence creates the documentation record needed to assess cause, responsibility, and cost recovery.
Field Modification Options
Field modifications for fit-up problems include: reaming oversize holes (acceptable if the resulting hole diameter does not exceed AISC limits); field-drilling additional holes (requires EOR approval and inspection); field coping (requires EOR approval for structural members); or fabricating a replacement member (when the original cannot be economically repaired). Every field modification should be documented with an engineering release — a written approval from the EOR stating the modification is acceptable.
Cost Recovery When Steel Doesn't Fit
The question of who pays for the delay and rework depends entirely on cause. If the fabricator used a superseded drawing, the cost is the fabricator's. If the detailer had a model error, the cost is the detailer's. If the EOR issued a revision that the drawing set didn't reflect, the cost may be recoverable from the design team or the owner. Document the cause determination in writing before anyone spends money on a fix. A cost recovery claim that is supported by photograph evidence, drawing revision timestamps, and a documented cause chain is far more likely to succeed than a verbal assertion made weeks after the event.
- Fabricator used wrong drawing revision — fabricator bears the rework and replacement cost
- Detailer model error — detailer bears cost per their contract; replacement member expedited at detailer's cost
- EOR design change not incorporated into drawing — potentially compensable against design team
- Foundation anchor bolt out of tolerance — potentially compensable against concrete contractor or surveyor
- Adjacent trade installation that conflicts with steel in code-compliant location — GC coordination issue; pursue through GC
Tolerance Limits and When Out-of-Tolerance Is Acceptable
AISC Code of Standard Practice Chapter 7 defines the tolerances within which fabricated steel is acceptable without modification. Column plumbness: 1/500 of the story height, not to exceed 1" for exterior columns or 1" + 1/16" per story above 3 stories. Beam camber: as specified; sweep within 1/8" per 10 feet. Column base plate elevation: +3/8" to -1/4". Bolt hole alignment: acceptable if bolts can be inserted without distorting the connection. When a member is outside tolerance, the first question is whether the out-of-tolerance condition affects structural adequacy — which only the EOR can determine. Some out-of-tolerance conditions are acceptable under a written EOR acceptance; others require modification or replacement.
Replacement Member Lead Times — Managing the Schedule Impact
When a fit-up problem requires a replacement member, the time to fabricate and deliver a replacement is the critical path item. A simple beam with standard connections can be re-fabricated and delivered in 3–5 business days from an expedited shop. A heavy wide-flange column with complex connections, moment welds, and a required blast-and-prime may take 2–3 weeks. When the replacement member is on the critical path, consider whether the erection sequence can proceed in a different bay or floor while the replacement is manufactured. The detailer, PM, and erection superintendent should all be in the same conversation when a replacement member decision is made, so sequencing decisions are informed by accurate lead time information.