New Brunswick Structural Engineer Trouble 4

[kissymoose]

https://www.cbc.ca/news/canada/new-...-engineer-buildings-john-richardson-1.7244456

Summary:
A structural engineer was called in to assess foundation cracks in a 63 unit apartment under construction back in December and concluded there were deficiencies in the design.
He calls the EOR and is informed they have produced many of similar design, then calls the New Brunswick association and hands it over to them.
Since then the engineer's licensed has been suspended/rescinded from multiple associations and multiple lawsuits have been filed.
The city of Dieppe said it has identified 20 buildings associated with the engineer, but who knows what the scope of work is to identify any other deficiencies.

"Match admits to under design of the transfer slab and certain elements, including columns and supports, supporting and connected to the slab..."
"Richardson described the main issue he observed as a concrete transfer slab over the parking garage that's too thin, with too little supporting steel."

 

[canwesteng]

I always get uneasy when I hear about an engineer shooting from the hip and calling something underdesigned by inspection, especially if it's just concrete cracking. That being said, it does seem like an issue here.

 

[Enable]

100% agree with you canwesteng. But as you say there must have been something terribly wrong for the corporate lawyer to file a statement of defense leading with "Match admits to under design of the transfer slab and certain elements, including columns, and supports..."

As in not even remotely arguable. In which case I wonder why the contractor didn't pick it up. I know we get a rap for not being the brightest but if there's one thing we know, it's typical, and based on admitting these kinds of mistakes this must have been all manner of not typical. Maybe the builder wasn't that experienced either?

 

[BulbTheBuilder]

This post is interesting as I was thinking about not long ago (barely 10 mins ago).

There are scenarios where people justify a new design having a demand-capacity ratio (DCR) > 1. In such a scenario, using a yes or no answer, is it under designed?
For a steel design, I might side with them considering yielding, strain-hardening and all, but in concrete? That's different. How do y'all handle situations where you find DCR>1?

I am looking for different opinions to see how others handle such situations. As a young engineer, I consider myself as inexperienced to deem designed OK to save myself since I have seen horrible construction before. There was another instance where the f'c (concrete report) came lower than the design f'c. Also, what if regardless of DCR>1, your building is OK but other party try to use that extenuate a claim on a different scope on the same project.
"If this exceeds the required strength, what shows other elements aren't"
"All decision made sound since she/he decided to go forward this knowing.."
I can just can't deal with those can of worms....

 

[phamENG]

DCR > 1 means that the design does not meet code.

You can go back and reconsider your assumptions. All designs start with some sort of assumptions. The more conservative your assumptions, the less precise your analysis needs to be (in general), allowing you to get to a code compliant, safe design in less time. It's not always the most cost efficient design in terms of construction costs, but it may be the only cost efficient method of design based on your fee and contract terms. If you do that and end up with a DCR > 1, then you may be able to go back and revise some of those conservative assumptions and do a more robust analysis to come with a lower DCR. Engineering judgement is to be used in developing your assumptions and method of analysis; comparison of results to code limits is black and white.

We went round and round on this in some detail recently. The thread was about a significant figures issue relating to DCR and lead to a debate on this very subject.

 

[BulbTheBuilder]

Thanks phamENG, I will also do a search here and find that thread.

 

[lexpatrie]

The first five minutes of The Teacher's Lounge.....

 

[Tomfh]

That discussion was for structures just over the line, eg 1.03. This is presumably a lot more serious than that.

 

[phamENG]

Tom - still applicable to Bulb's question.

 

[lexpatrie]

Overstressed is a fail in the design standard. Regardless of how far over. In the most literal sense.

If you go beyond 1.0, (in Florida) you're expected to clearly disclose that in your design submission. I mention this not because it's a Florida project, I mention this because designing a building where one element is overstressed per code makes that area more likely to fail. We are supposed to hold paramount life-safety. Anything less than full disclosure of "engineering point shaving" is ethically dodgy.

Source: FBPE website, Geach disciplinary action, April 30, 2024.

Editorial side note: The truss design engineer is the person who should almost always be doing truss repair designs and issuing sealed repair drawings, especially when it's a new truss and the truss design engineer is readily identifiable. They have the software and the intricacies of the original design, (eccentricities on any joints) and the "homefield advantage". Same concept applies to open web steel joists.

This particular one has a 30% overstress, so obviously that's "too far" for their taste. Just how far over is "too far"? Time will tell. Maybe.

"Failure to comply with the procedures set forth in the Responsibility Rules as adopted by the Board of
Professional Engineers shall be considered as non-compliance with this section unless the deviation or
departures therefrom are justified by the specific circumstances of the project in question and the sound
professional judgment of the professional engineer."

"(8) A professional engineer shall not be negligent in the practice of engineering while performing duties as a
special inspector. Negligence is herein defined as the failure by a professional engineer to utilize due care in
performing in an engineering capacity or failing to have due regard for acceptable standards of engineering and
special inspection principles. Failure to comply with the procedures set forth in the Responsibility Rules for
Professional Engineers Providing Threshold Building Inspection, as adopted by the Board of Professional
Engineers, shall be considered non-compliance with this section unless the deviation or departures therefrom
are justified by the specific circumstances of the project in question and the sound professional judgment of the
engineer."

Source: Florida Board of Professional Engineer's Web site, 61G15, F.A.C As of August 10, 2018, accessed Jun 30, 2024

61G15-30.001 Purpose.
The Board has adopted these responsibility rules pursuant to Section 471.033(2), F.S., to safeguard the life,
health, property and welfare of the public by promoting proper conduct in the practice of engineering and due
care and regard for acceptable engineering principles and standards. The Board considers that professional
engineers may avoid disciplinary actions by observing the procedures set forth herein. Failure to comply with
these rules may be considered as noncompliance with subsection 61G15-19.001(4), F.A.C., unless the deviation
or departure therefrom is justified by the specific circumstances of the project in question.

Now, have I found anything that is that specific, anywhere? NO. Why? Because disciplinary actions (the only thing most of us have access to) don't go into the nuts and bolts and identify things in that detail.

Here's what I have for you - (and many of the Florida disciplinary actions involve that deviations element), read for yourself. There are usually other issues, but the deviations element comes up fairly often.

Church collapsed twice during construction, engineer had no calculations whatsoever (from my read of it), and eccentricity on a footing was not considered, creating significant overstress on the footing. Masonry was over stressed, and roof-wall detailing for shear transfer from roof diaphragm to shear wall was missing.

Source: FBPE, Haug disciplinary action, December 14, 2022.

Roof-wall detailing for shear transfer from roof diaphragm to shear wall was missing. Incorrect parapet height, missing calculations for some masonry elements, etc.

Source: FBPE web site, Borujerdi disciplinary action, December 13, 2023.

There are also a number of OSHA reports involving building collapses by Mohammad Ayub that discuss structural engineering in detail and various "overstress" calculations. You can follow the breadcrumbs to the original reports from the Structure Magazine article. Structural Collapses During Construction, 1990-2008 Lessons learned, Ayub, December 2010.

Many of these involve poor construction techniques and inadequate curing/shoring, but many of the full-on collapses had significant engineering mistakes that contributed to the collapse (Harbour Cay, collapsed during construction in 1981, springs to mind, as does that 2007 Jacksonville, FL, Parking garage collapse during construction, (Berkman Plaza II) and the FIU pedestrian bridge in 2018...). One might consider, if the engineering design had been better, would the goofy construction technique have "limped through" construction without a fatal collapse? Would the construction errors have permanently damaged the structure to the extent it would have collapsed later on when it approached design loading conditions? If the construction technique had been better (longer curing, longer shoring and reshore "loiter time") produced "strong enough for the moment" and lead to a failure (due partly or mostly due to poor engineering) let the structure "limp through" construction to an eventual collapse much later in time when the loads finally approached the design load in the "perfect" location (Station Square, Burnaby BC collapse during the store's grand opening, springs to mind there).

 

[BulbTheBuilder]

Thanks for sharing those links and articles, lexpatrie. Very insightful

 

[lexpatrie]

No worries it's kind of related to something I'm already doing so consider it bycatch.

 

[BulbTheBuilder]

I am enjoying reading forensic reports and structural failure articles. It kind of always puts me in check aside learning how slight mishaps can greatly affect structural integrity

 

[EngDM]

Overstressed is a fail in the design standard. Regardless of how far over. In the most literal sense.

I'm curious how various OWSJ suppliers get away with showing 1.03 and 1.04 on their calcs if this is the case? Further, Forte allows members to pass when they are above 100% as well, and also when they just barely fail the deflection checks they implement.

 

[Tomfh]

I'm curious how various OWSJ suppliers get away with showing 1.03 and 1.04 on their calcs if this is the case? Further, Forte allows members to pass when they are above 100% as well, and also when they just barely fail the deflection checks they implement.

You’re right that it’s a common (albeit debated) practice, and that this alone illustrates that a slight overstress is distinct from a severe overstress, regardless of the fact that both fail code.

 

[lexpatrie]

Different not in the sense it fails code. As to probability of failure, yeah, maybe. Is somebody going to do the monte carlo simulation to show it's only 5% more likely to fail or something? Because I've never seen that done.

What I have seen done is treating the dead load as partly imaginary, so the joist they pick is wrong. I'm talking ballasted roofs designed for say, 10 psf when the rock itself is 10 psf.

Joists now have default camber.

My issue with these 1.04 approaches is whenever I'm looking at somebody's calculations, there's an error or two, a dimension that's a bit short, etc. The 1.04 easily turns into 1.1, 1.2, or 1.3 with a few slips of attention. Or they muck up the thermal factor and use 1.0 on a ventilated R49 roof, and ALSO consider it wind-swept with Ce = 0.9 when there's a parapet on three sides. So there's goofs on the load side that help make the failed selection work, and then there's a mistake in the length, etc. etc. etc.

I've never had FORTE pass a failing section. Usually it's the opposite, a fail when the section works and I have to diagnose why it's throwing a fail.

There was an SJI seminar on joist reinforcement where they got into the 1.04 1.05 sort of discussion, but I watched those all in January so I can't say which specific seminar had that discussion.

 

[EngDM]

I've never had FORTE pass a failing section. Usually it's the opposite, a fail when the section works and I have to diagnose why it's throwing a fail.

See below two examples. Not sure why they allow this.

 

[Craig_H]

I think that it's relatively safe to guess that this transfer slab is loaded to a UC of more than 1.04 (or whatever number you want to argue the semantics of). The regulator is using "serious deficiencies" in its statements, and I doubt that term is being swung around carelessly.

The New Brunswick association said in a June 7 statement the suspension was based on "allegations of serious deficiencies in the design of multiple buildings, both constructed and under construction."

Service level loads in apartments are typically well below the code defined levels, even when live load reductions are applied. If visible cracks and signs of distress were evident on a walkthrough, and the whistle-blowing engineer was concerned enough to contact the provincial regulator, there's a major issue here. Even worse is that the article makes it sound like construction loads were causing the excessive cracks in the transfer slab:

Just before Christmas, Richardson toured the building and said he saw more cracks than he considered normal. In Richardson's opinion, the building wasn't safe for construction work to continue.

I went through something similar last year, where I discovered design deficiencies causing distress in a ~20 year old building that are likely replicated on a number of similar buildings. It is my understanding that my provincial regulator is currently investigating, so I won't say much more. I am reassured to see news stories like this, as I feel they provide some guidance for how we as engineers need to handle these situations when we are unlucky enough to stumble into them. Needless to say, it was a stressful period of time for me, and case studies helped guide my decision making significantly.

I hope that the outcomes are well documented by the regulator. Guidance on how to handle these situations is scarce.

 

[lexpatrie]

Erm.

Well, 14.06/13.81 = 1.018, I suppose there's a truncation in the guts of their code, so when it chops it off to 1 decimal it's a 1.0 and passes. I haven't had this happen personally but I use English units, so that's another possible source. So now we're back to Chancey, Sputo, Minchin, Turner?

 

[lexpatrie]

my provincial regulator is currently investigating, so I won't say much more.

This is the way.