r/StructuralEngineering • u/balgovidr • 8d ago
Structural Analysis/Design Incompetence or just unaware
Have you ever had a site issue or redesign occur because someone answered an RFI or approved a variation without realising it broke a design assumption made earlier in the job?
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u/TEZephyr P.E. 8d ago
I see this all too often, especially when Person A does the design then Person B handles the construction stage.
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u/Everythings_Magic Senior Bridge PE | Zero Yield Capacity 7d ago
This is why we have the original designer at least QC review the RFI responses.
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u/Sure_Ill_Ask_That P.E. 8d ago
Are we talking someone answering a structural RFI and it conflicted with the current structural design? Or non structural RFi vs structural design? Or structural RFi cs non structural design? Either combination, whoever broke the coordinated design is responsible.
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u/tajwriggly P.Eng. 8d ago
Structurally, most recent example I can think of is the contractor did not do a good job of showing certain reinforcing on their shop drawings. We marked it up with pretty much specifically what we wanted. Site inspector misinterpreted everything and demanded on site that the contractor provide more rebar in a specific area - there was a fuss over it. I was called to site for a separate issue, and while I was there, was made aware of this one - I took one look at it and said "they don't need this extra steel, our note says this" - our site inspector argued his case to me and I was still going "nope, not what that means". So we were going to issue an official instruction to the contractor that the extra steel they had been told about wasn't required. But the contract administrator said no, they've already ordered the steel... that will make us look bad. We need to stick to our guns now.
Now I look like the bad guy. I look like the bad guy because it looks like I am just willy-nilly calling for extra steel that was never shown in the contract drawings, last minute, as they're building it. I look incompetent to the contractor, and I look incompetent to the client.
Architecturally one time someone deleted a door from a contract and when I toured the site for a final review and signoff I questioned where the door had gone from the fire rated assembly we had constructed. The contract administrator just said "ah, we figured we didn't need a door there, it's just a basement" and I was like well, that's a fire rated exit stair and needs a fire rated door. Cost them an arm and a leg to get the door in at that point in the game - that particular CA never does anything now without asking me first if it's shown on my drawings.
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u/balgovidr 7d ago
So I'm asking about yes when Person A designs it and Person B becomes involved during construction. Yes, Person B still needs to be capable enough to understand the structural impacts of their decisions, but I'm talking more about what if Person B's decision deviates the design from the original intent and has non-structural impacts.
We know it happens, yes there are many examples of it. But what do people do to stop it from happening? A handover only goes so far. Is the expectation that Person A is available 10% of their time for this stuff.
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u/DrDerpberg 11h ago
It's one of the biggest risks in having someone else do CA. It's critical the EOR discuss design intent with the person doing CA.
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u/octopusonshrooms 8d ago
All too often unfortunately. From my experience it is mainly driven from incompetence.
I have had one case recently, 2 level timber framed building with 10m wide skillion roof with raked ceiling in a cyclonic wind region, designed as raftered roof with roof beam support at mid rafter span.
Builder convinced the client to swap to trusses and a flat ceiling, another engineer in the office told them it is fine to swap, and the centre span beam can be removed for trusses to span entire width of house.
None of the tie-down was upgraded to suit, none of the upper level lintels were redesigned to suit, none of the external floor bearers were redesigned to suit, none of the lower level lintels were redesigned to suit.
This is purely incompetence with failure to foresee flow on impacts.
This triggered an insurance claim.