Office building featured in case study of ACI 562 webinar by NCSEA
Office building featured in case study of ACI 562 webinar by NCSEA
(OP)
Yesterday I attended a pre-recordered webinar by our local SEA on ACI 562: CONCRETE REPAIR CODE presented by Dr. Keith Kesner and one of the three (albeit brief) case studies presented was an office building as follows:

After a few minutes of 'googling' I identified the building and its location, but I won't share it here.
5 floor levels, repetitive, simple, rectangular plan layout. What was the EoR thinking?
It was repaired/strengthened at a cost of more than $20M (there were building envelope, plaza deck and other issues too). Obviously there were lawyers and insurance companies involved and the EoR settled.
This post may be somewhat more appropriate in the Engineering Failures and Disasters forum, except that it does not fall into the classic definition of failure/disaster, but oh-boy what a screw up.

After a few minutes of 'googling' I identified the building and its location, but I won't share it here.
5 floor levels, repetitive, simple, rectangular plan layout. What was the EoR thinking?
- Span-to-depth (L/D) of 60!
- 12" square columns for a 5 level building
- No drop panels, caps.
It was repaired/strengthened at a cost of more than $20M (there were building envelope, plaza deck and other issues too). Obviously there were lawyers and insurance companies involved and the EoR settled.
This post may be somewhat more appropriate in the Engineering Failures and Disasters forum, except that it does not fall into the classic definition of failure/disaster, but oh-boy what a screw up.






RE: Office building featured in case study of ACI 562 webinar by NCSEA
L/D still up there at > 45, but better than 60!
RE: Office building featured in case study of ACI 562 webinar by NCSEA
Come on, you have to tell us more than that.
I would think that $20M repair due to strength and serviceability issues is a failure. It does not have to fall down to be a failure, that is a collapse! Severe Strength and serviceability problems means it has failed 2 Limit States.
RE: Office building featured in case study of ACI 562 webinar by NCSEA
RE: Office building featured in case study of ACI 562 webinar by NCSEA
It is indeed.
Yes, you are right. When the building in 2010 was classified by as 'imminently dangerous' and closed, it has failed.
I found several reports of the building via some google-digging. Some very detailed reports in documentcloud.org, which I won't share to protect the guilty, but here is a brief summary pertaining to the PT slabs. There were also issues with the building envelope and facade too, related to the slabs design shortcomings:
2. PT was balancing 200% of self weight in many shorter spans;
3. Measured midspan deflections of 4" in dominant long spans;
4. Punching shear demand/capacity ratios of 3+; See photo below! One reports mentioned that closed-tie 'shear heads' were used but I can not confirm this.
5. Axial shortening of +1-1/2";
6. In-situ concrete compressive strengths of less than 4,000 psi after 10 years;
7. Numerous construction-related defects too.
8. Lateral force resisting system was also undersigned.
Original construction cost was about $30M in 2000.
RE: Office building featured in case study of ACI 562 webinar by NCSEA
My point is that such things happen all too often. My firm was involved in the investigation of the failure of a parking garage under construction in Jacksonville, Florida in December 2007. Underdesigned and marginal construction. One person died.
RE: Office building featured in case study of ACI 562 webinar by NCSEA
I recall reading the NIST report some time back on the Harbour Cay collapse. I also remember reading in another reference to this collapse (Feld & Carper, 1997) that the structural engineer was a retired NASA engineer who hired another retired NASA engineer to perform the calculations and Prof Norbert Delatte made a point that:
And this by Gene Corley:
RE: Office building featured in case study of ACI 562 webinar by NCSEA
I'm not sure I completely agree with Corley. The SE does not guarantee that mistakes won't be made, though I do agree that the more rigorous the exam process, the lower the chance of missing one of the "fundamentals" of a design. I'm pretty sure that when that failure occurred, there was no SE licensure. I was hired by an attorney for the rebar producer to review the rebar shop drawings and compare to the design. Had just gotten started when the whole thing was settled.
RE: Office building featured in case study of ACI 562 webinar by NCSEA
I found this OSHA report on that project. Link to OSHA Report. Some horrific collapse photos.
True. Reduced but not eliminated. Experience matters.
RE: Office building featured in case study of ACI 562 webinar by NCSEA
This was the first thought that entered my head when I viewed this thread. For the life of me, I can't understand why some kind of minimal, qualified, anonymous, third party review isn't required for each and every building constructed everywhere. Heck, you could probably still buy an afternoon of Bill Baker's time for $1500 which wouldn't even amount to 0.1% the cost of a modest building. And I'm sure it wouldn't have taken Bill fifteen minutes to pick up on the deficiencies here.
I've worked for a lot of firms in a number of jurisdictions including one of the laxest out there, Canada. In my opinion, none of the following is adequate QC:
1) internal firm QC. Everybody likes money.
2) government official QC. They're generally not serious structural engineers.
3) rockstar university professors (talkin' to you California). Also generally not serious engineers.
4) Quantitative checks at the expense of experienced judgement. Quantitative checking usually amounts to junior people checking easy/non-critical things. It also doesn't add enough value per dollar to make sense.
5) Relying on the SE licensure gauntlet. It helps but even the California SE process is superficial compared to being a practicing structural engineer in my opinion.
I used the Bill Baker example only semi-facetiously. I bet even a mandatory 60 minute review by an experienced third party would eliminate almost all problems like this.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Office building featured in case study of ACI 562 webinar by NCSEA
I think maybe even a first year grad at SOM's office would have picked up on the punching shear, and related issues, within a cursory review...
RE: Office building featured in case study of ACI 562 webinar by NCSEA
Not disagreeing at all, but making rules does not necessarily help
I know of a very small country in Asia where a full independent design review of every structural design is required by qualified design reviewers before the design is approved for construction. These reviewers tend to be older experienced engineers. And they do a very thorough design check. They go through every line of the designers calculations and pick up the smallest mistake.
Unfortunately they do not check that what is in the calculations is actually on the drawings!
Ingenuity,
You got a couple of comments in there before I could. I assume it suffered from all of the problems you and I have been warning about for about 20 years?
- Designed by average moments
- with banded distributed tendon pattern
- allowed for live load reduction
- with a tension stress at supports close to the tensile strength of the concrete based on average moments.
- assumed uncracked under this average moment condition for deflections
- and no normal reinforcement added in the bottom because stress less than the limit
- Designed using a computer program that the designer did not understand in an area of design that he did not understand with supervisors who did not understand
- and deflection calculations were based on a long term multiplier
- with no consideration of restraint effects
Making Punching Shear work must have been fun on 12" square columns with a 8-10" slab on 38-40' grid!
RE: Office building featured in case study of ACI 562 webinar by NCSEA
95% of structures can be reasonably reviewed in a few hours on a couple of pieces of paper. You check the math on the major gravity and lateral systems using rough loading, then you qualitatively review the detailing to make sure important things have been captured in the design and that there's a load path. During that review, you identify anything that looks non-standard or is critical to the load path and do rough numbers on those.
Then you sit down with the design engineer and ask questions about weird things you found, or just about the choices made. That gives you an idea of whether the design was thought through and whether the engineer actually understands what they did.
That's enough to catch dangerous levels of negligence and doesn't get you captured in someone else's math.
I don't care if a review catches a member being a size too small, or deflection being out. I care if there's a life safety issue or the designer doesn't know what they're doing.
The number of times I've caught massive misunderstandings in seismic load application, blind use of software that spit out a number that was off by an order of magnitude, or lack of attention to load paths in delegated engineering is terrifying and dangerous. However, it's also obvious on a reasonably high level review.
RE: Office building featured in case study of ACI 562 webinar by NCSEA
RE: Office building featured in case study of ACI 562 webinar by NCSEA
I agree. For internal review, do a somewhat thorough design drawings review, do some brief independent hand-based calcs, mark-up a set of drawings with questions for the engineer/designer, and maybe ask the engineer/designer submit the design calcs purely to see if it is orderly and rational, not to review the actual detailed numbers.