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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

#51

Post by aaron695 »

Syonyk wrote: post #9

> Mr. Kilsheimer cautioned that it is common in construction for the final product to differ from drawn designs. Yes, and there's also a decent history of structural failure, or nearly so, from that particular habit. The Hyatt walkway collapse ( https://en.wikipedia.org/wiki/Hyatt_Regency_walkway_collapse... ) is one of the better known - designed one way, built another so it would be easier and cheaper to build, and…

I'm not a fan of the "Hyatt walkway collapse" as a teaching tool. The mathematics is extra interesting. Not sure it's good for the design failure which people reference. More people die from bad insulation design each year, it's the boring stuff that matters.

The Hyatt walkway collapse was at a big dance party with a fair few people watching from above. Perhaps dancing?

I-35 bridge collapse was rush hour.

What's the peak here? Why 1am?

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

#52

Post by grogenaut »

aaron695 wrote: post #51
Syonyk wrote: post #9

> Mr. Kilsheimer cautioned that it is common in construction for the final product to differ from drawn designs. Yes, and there's also a decent history of structural failure, or nearly so, from that particular habit. The Hyatt walkway collapse ( https://en.wikipedia.org/wiki/Hyatt_Regency_walkway_collapse... ) is one of the better known - designed one way, built another so it would be easier and cheaper to build, and…

I'm not a fan of the "Hyatt walkway collapse" as a teaching tool. The mathematics is extra interesting. Not sure it's good for the design failure which people reference. More people die from bad insulation design each year, it's the boring stuff that matters. The Hyatt walkway collapse was at a big dance party with a fair few people watching from above. Perhaps dancing? I-35 bridge collapse was rush hour. What's the…

If the peak was actually a trigger, in a residential building 1am is about the start when the max people other than a party will be there (everyone back from clubs)

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

#53

Post by cratermoon »

sellyme wrote: post #33
secabeen wrote: post #24

The most important section though is buried in a late paragraph: >Engineers said it seemed unlikely that having less rebar would trigger a collapse in and of itself, even factoring in significant deterioration over many years. An inherent safety factor built into most projects would mean that a slight reduction in steel content would not necessarily lead to disaster. This certainly suggests that there may have been s…

> An inherent safety factor built into most projects would mean that a slight reduction in steel content would not necessarily lead to disaster. On the other hand, it can lead to disaster, which is why that safety factor exists. We're not doing that just for fun.

The space shuttle SRBs were designed with two o-rings, a primary and a secondary. When the primary kept showing signs of burn through, instead of treating that as a problem, it was said that because the secondary o-ring was not burned through, the safety factor was sufficient. But the primary was not designed to burn through. The safety factor did not account for burn through in normal operation, but risk assessments obscured that fact.

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

#54

Post by cnorthwood »

jagger27 wrote: post #39
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…

> lost building plans That's pretty wild. I thought city halls had copies of all building plans from when they were submitted for permit approval.

In the UK the local council (town hall) only holds the plans relevant to making planning decisions, not the detailed construction plans. Private companies can sign off the building safety (known as building control) usually as part of providing a new build warranty on the development (but then one of the biggest providers, Zurich, offloaded their portfolio to a shell company than then went bankrupt under the liabilities due to incorrectly signing off buildings. The whole situation is a major scandal in the UK at that moment)

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

#55

Post by gerdesj »

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…

"Similar to the Grenfell Tower fire in Uk"

No it isn't quite the same. I recently had a look at the docs about Grenfell. That's here: https://www.gov.uk/guidance/aluminium-composite-material-cla...

I haven't quite got to the bottom of whether the standards relating to fire was broken or whether the guidance for builders had a hole in it that allowed for what we now know as sub standard cladding.

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

#56

Post by ClumsyPilot »

jagger27 wrote: post #39
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…

> lost building plans That's pretty wild. I thought city halls had copies of all building plans from when they were submitted for permit approval.

I thought so too

https://www.itv.com/news/london/2020-09-14/grenfell-files-lo...

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

#57

Post by brudgers »

secabeen wrote: post #44
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…

> On the other hand columns fail by buckling when they become too slender…which is effectively what happens when a column loses steel and concrete due to corrosion and spalling. Okay, great. So you're clearly more qualified than I. The above fits with my understanding too. I haven't seen reports that the columns in question were losing dangerous amounts of steel or concrete. Here is the picture from the 2018 report.…

See all that fairly fresh paint?

In the first picture they painted over failed concrete. The pictures are said to be “typical.”

The reasons it wasn’t evacuated at the time were business and politics not comprehensive structural investigation.

You see if the client isn’t paying to find problems below the surface, then they won’t be found. And it is common for clients to not want to find such problems. And for engineers to limit their analysis accordingly.

I know what my professional opinion would have been based on those pictures. It would not have been good for my business given the client profile.

Or to put it another way, those pictures show that what happened had a real chance of happening. That’s not hindsight. It would have caused me grave concerns.

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

#58

Post by ClumsyPilot »

gerdesj wrote: post #55
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…

"Similar to the Grenfell Tower fire in Uk" No it isn't quite the same. I recently had a look at the docs about Grenfell. That's here: https://www.gov.uk/guidance/aluminium-composite-material-cla... I haven't quite got to the bottom of whether the standards relating to fire was broken or whether the guidance for builders had a hole in it that allowed for what we now know as sub standard cladding.

The unquiry is still ongoing, but firstly the fire safety ceritifucate was forged, as second its not just the cladding, there were missing firebreaks, no evacuation route for disabled people, not functioning fire alarms and smoke extraction and countless other issues in the bulding - if it was just cladding half the residents wouldn't have coocked alive

https://www.insidehousing.co.uk/news/news/grenfell-contracto...

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

#59

Post by Scoundreller »

Syonyk wrote: post #9

> Mr. Kilsheimer cautioned that it is common in construction for the final product to differ from drawn designs. Yes, and there's also a decent history of structural failure, or nearly so, from that particular habit. The Hyatt walkway collapse ( https://en.wikipedia.org/wiki/Hyatt_Regency_walkway_collapse... ) is one of the better known - designed one way, built another so it would be easier and cheaper to build, and…

This sounds similar to the Toronto stage collapse that happened. The design spec'd out 3" tubing, but such a thing didn't "exist" (in their inventory) and they used 2".

https://www.cbc.ca/news/canada/toronto/radiohead-stage-colla...

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

#60

Post by Scoundreller »

aaron695 wrote: post #51
Syonyk wrote: post #9

> Mr. Kilsheimer cautioned that it is common in construction for the final product to differ from drawn designs. Yes, and there's also a decent history of structural failure, or nearly so, from that particular habit. The Hyatt walkway collapse ( https://en.wikipedia.org/wiki/Hyatt_Regency_walkway_collapse... ) is one of the better known - designed one way, built another so it would be easier and cheaper to build, and…

I'm not a fan of the "Hyatt walkway collapse" as a teaching tool. The mathematics is extra interesting. Not sure it's good for the design failure which people reference. More people die from bad insulation design each year, it's the boring stuff that matters. The Hyatt walkway collapse was at a big dance party with a fair few people watching from above. Perhaps dancing? I-35 bridge collapse was rush hour. What's the…

> What's the peak here? Why 1am?

I wondered this too. Maybe contraction or rate of contraction?

Sun has gone down, outdoor temperature is dropping, max heat radiation out if the sky is clear, and everybody is home so A/C is on in all units.

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