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Condo wreckage hints at less steel in columns than design drawings

nytimes.com

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Re: Condo wreckage hints at less steel in columns than design drawings

#101

Post by PeterisP »

sandworm101 wrote: post #66

Rip open any building short of a nuclear reactor complex and you will find such differences. Nothing, ever, gets built exactly as planned. We have only a few photos, blurry ones at that. Hold off on the conclusions until reasonable evidence emerges.

Sure, changes often are required when plans come to a practical implementation, but they (should?) have to be documented and re-verified by the engineers/architects at least for structural components, and the plans should get updated to match the on-site modifications.

Re: Condo wreckage hints at less steel in columns than design drawings

#102

Post by sjg007 »

Czarcasm wrote: post #92
sjg007 wrote: post #84

Earlier quoted context omitted.

Are you suggesting it’s ok for the contractor to not follow the plans?

Of course it’s not ideal, but in the real world the designs are often impossible or impractical to build. If work halted every time construction workers came across a design that didn’t work, instead of tweaking the design onsite and keeping going, nothing would get built. Source: multi-generational heavy construction family business.

So in the case of a tructural support columns or foundations, How does the contractor insure they are still safe and capable of performing?

Re: Condo wreckage hints at less steel in columns than design drawings

#103

Post by fuzzfactor »

ajsnigrutin wrote: post #36
brandon272 wrote: post #11

Saw a video today of a simulated collapse that suggests a possible failure mode given the likely parking garage collapse that occurred before primary collapse: https://www.youtube.com/watch?v=hynHiWE818c

This is an interesting theory... one would wonder, how come it collapsed at the place, where it only held one slab, and not somewhere under more weight... but i'm not a civil engineer, so yeah... time (and analysis) will tell.

This would also be consistent with less steel being included than originally designed, as was rumored during construction of numerous hi-rises during the boom.

Looks almost like punch-through of all floors simultaneously due to shock, almost as if it was a planned demolition where stuctural supports are compromised with precision to assure orderly collapse.

Only this part of the building fell precisely without any carefuly placed dynamite.

But when buildings are stronger, sometimes intentional demolition projects do not complete the job so thoroughly on the first attempt.

Re: Condo wreckage hints at less steel in columns than design drawings

#104

Post by Tostino »

TheSpiceIsLife wrote: post #83
LeifCarrotson wrote: post #63

Earlier quoted context omitted.

It's also approximately the time when the building will be coldest. If there were any thermal expansion/contraction issues, they would have been at a maximum near 1am. The thermal expansion and contraction of concrete and reinforcing steel are nearly identical, but the steel has much higher thermal conductivity and cools off far faster; perhaps something snapped under tension between concrete that was still holding h…

Wouldn’t the coldest part of the night typically be immediately before sunrise?

All it takes is being cold enough to cause the extra voltage drop.

Re: Condo wreckage hints at less steel in columns than design drawings

#105

Post by ineedasername »

brudgers wrote: post #75
ineedasername wrote: post #69

Where I work an old building had massive plumbing problems for years-- flooded floors. After it happened a few times someone went back to the original plans to see if it might reveal the cause. They were shocked to discover it specified & contracted to have copper pipes. The building had PVC instead. And engineering firm was brought in to make an assessment and determined that the PVC used wasn't even rated for the t…

My William of Occam hat says most likely the Owner approved the change. Shaving money from the materials budget saved money. So yes an inside job as inside as inside can be.

Hard to say-- the owner was pretty damn pissed off about things too. Given what I saw if that, I could more easily imagine an underling dealing with cost overruns & agreeing to let the contractor go the cheap route.

I can also easily imagine that the cost overruns we're overstated and the contractor pocketed the extra profit.

Re: Condo wreckage hints at less steel in columns than design drawings

#106

Post by brudgers »

ineedasername wrote: post #105
brudgers wrote: post #75

Earlier quoted context omitted.

My William of Occam hat says most likely the Owner approved the change. Shaving money from the materials budget saved money. So yes an inside job as inside as inside can be.

Hard to say-- the owner was pretty damn pissed off about things too. Given what I saw if that, I could more easily imagine an underling dealing with cost overruns & agreeing to let the contractor go the cheap route. I can also easily imagine that the cost overruns we're overstated and the contractor pocketed the extra profit.

It's not uncommon for Owners to be pissed off by their own cheaper-now decisions. The Owner and the Contractor spend all day on site talking about how stupid the Designers were...which is easy because all their mistakes are right there on paper.

Anyway, the Owner's underlings are the Owner if they have the authority to approve changes.

And if you saw the Owner pissed off, then it is not unlikely that they are the sort of person who blames others for their errors.

As for the distribution of the money, everyone probably got some except the Design team...it's the sort of change that the Owner and Contractor collaborate on despite the professional opinions of the Design team. And so the Design team can wash its hands of responsibility since they did not get paid for the extra work of changing the design (which is why the design documents differ from the asbuilts).

Or to put it another way, with any substantial size building everyone was sitting around the table when the option was discussed and the Design team walked the site prior to approving the Contractor's pay requests for plumbing labor and materials.

There are lots and lots of checks and balances in even below average construction projects. Swapping PVC for copper throughout is not the sort of thing that goes under the radar.

Re: Condo wreckage hints at less steel in columns than design drawings

#107

Post by brudgers »

secabeen wrote: post #99
MertsA wrote: post #95

Earlier quoted context omitted.

Yeah that's some pretty widespread spalling on the garage deck. Regardless of what went wrong, I'd be surprised if rust jacking or just plain section loss of the rebar wasn't a principle factor behind the collapse. All of that rebar has just been rusting for an additional 3 years since those photos were taken and it looks like the corrosion was already pretty spread out at the time and no one did anything to address…

Thanks to both of you; this is better analysis than I've seen in other forums.

Conversely, your response to my initial comment was internet ordinary.

Re: Condo wreckage hints at less steel in columns than design drawings

#108

Post by brudgers »

mariuolo wrote: post #90
brudgers wrote: post #40

Earlier quoted context omitted.

Was in AEC in Florida for nearly twenty years. Started in a precast plant. During my MArch studied under one of the top forensic architects in Florida, Chuck Goldsmith, after grad school I worked as a Licensed Plans Examiner, got my Florida Architect License in 2007 - though it is currently inactive since I don’t practice there. So yeah I do know someone with an informed opinion. Concrete beams fail in tension. Likew…

Could it be they thought they had more time to address the problem because the plans showed a different situation than it actually was?

My educated guess is that there is a cadre of local engineers whose market includes similar buildings and that the deterioration was ordinary enough that the engineers could draw on years of experience to say "it is not likely to collapse because other buildings like it have not collapsed."

As I have said elsewhere, the only thing I suspect is unique is that this was the first building to spectacularly fail.

It failed with people in it because there are tremendous disincentives toward saying the sky is falling even when the sky is falling. It's bad for business and it's bad politics.

Or to put it another way, suppose it was bad design or bad soil. Do you think that the same engineers, owners, contractors, and government agents did everything right on every other building? Think of how hard it is to keep salt off of rebar during construction next to the ocean. Now do so when there is every incentive to save money and no incentive to predict catastrophe.

Re: Condo wreckage hints at less steel in columns than design drawings

#109

Post by SilasX »

ClumsyPilot wrote: post #37

Similar to the Grenfell Tower fire in Uk, where over 70 people burned alive. The residents warned that the building was unsafe, fire inspector warned it was unsafe, yet nothong was done. Now investigation is 4 years in and it has been an endless processions of code violations, cost cutting, lost building plans (the company told the court that intern deleted them) and outright fraud by the company that produced claddi…

> The best part is, the builders are not on the hook, the building owner is not on the hook, the management company is not liable, but a leaseholder that bought 25% of the apartment is responsible for 100% of the bill to put things right. Those properties are unsellable, and have become a toxic asset.

Not insurers? Or the owners aren’t required to carry insurance?

Re: Condo wreckage hints at less steel in columns than design drawings

#110

Post by shados »

sofixa wrote: post #93
shados wrote: post #80

Earlier quoted context omitted.

This is unfortunately very common. The building I live in is not that old (about 15 years. I moved in 10 years ago). We have the original plans, which were somehow never registered with the city (which has been part of the permitting process for buildings of this size since long before it was built). The codes to the fire alarms were never registered with the fire department (also a requirement). A lot of extremely v…

> It's not an isolated incident either...that shit happens everywhere. Inspectors get paid, turn a blind eye, profit If something goes wrong, isn't the inspector who signed off liable? Maybe not for damages, but they'd certainly lose their credentials and job. Do they just hope it never happens while they're still at it?

Only if someone can prove it was caused by something they should have caught. Good luck with that.
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