Miami Condo Collapse Investigation SETBACKS: Champlain Towers

[@jeffostroff]

🎥 WATCH NEXT: 🎥 How To Install Perfect Kitchen Cabinets DIY Like Pros: kzbin.info/www/bejne/q16ZcqVmfb-KkLc 🎥 Coast Guard Has OFFICIAL OceanGate Titan Sub Transcript: kzbin.info/www/bejne/r3_UoWWVbJWbrck 🎥 OceanGate Titan Sub Debris Video Shows How It Imploded: kzbin.info/www/bejne/mXe0eH2BqLNghsk 🎥 OceanGate Titan Sub Coast Guard Hearing SHOCKING Facts: kzbin.info/www/bejne/n2ippJiea5l_p5o 🎥Coast Guard Video: Titan Sub Salvaged Off Ocean Floor: kzbin.info/www/bejne/mImTZauDmtJmY6s 🎥 NTSB Titan Sub Report: Carbon Fiber Hull Defects, More: kzbin.info/www/bejne/kGjbkpiGop6Enrs 🎥Titan Sub: Fired OceanGate Employees Show What REALLY Happened kzbin.info/www/bejne/jZWYlWiqrr1-m8U 🎥 How OceanGate Titan Sub Realtime Hull Monitor FAILED! RTM: kzbin.info/www/bejne/d3jZhKOAnppgj5I

[@CollapseOfChamplainAndMore]

Thanks for putting this out Jeff.

[@CollapseOfChamplainAndMore]

Champlain collapsed June 24th 2021 not June 21st

[@CollapseOfChamplainAndMore]

June 24th 2021 not June 21st

[@aagc1988]

what about the north towers or towers from the same time/building company? should those not be extensively analized and if they are in any danger evacuate them, analize them then demolish those? sell the land in high price and split that with the apartment owners?

[@PetraKann]

3:00 Not foot pounds. This is a unit of force, pounds force lbf

[@kevinbrooks6078]

Hey Jeff, Thank you for taking your time in keeping the updates coming from the Champlain Towers South Condo and the Ocean Gate Titan Sub Incidents.

[@jeffostroff]

@kevinbrooks6078 thanks for coming back for more kevin

[@maryellerd4187]

Thank you for the updates, keep them coming, please. The extensive time and effort put into their production is appreciated.

[@brandonlink6568]

Since this is is thankfully a rare occurrence I'm glad they're being extremely thorough and learning as much as they can about what makes a residential building collapse

[@electrictroy2010]

@brandonlink6568 IT isn’t rare. Since this condo collapse several other buildings have collapsed. (Fortunately most were evacuated.)

[@mjookie]

It’s the usual story, Do you want it fast or do you want it right? I go for the second choice every time so good on them, it’s a shame that idea wasn’t used in the original and continuing works on the building. And thanks as ever for keeping us up to date..❤️

[@cyclonasaurusrex1525]

Nice job covering the forensic engineering. Fascinating work by some very smart people.

[@MyKharli]

Looks like a boring repetitive job unless your the lead . There's lots of jobs with smart people doing the most tedious of tasks .

[@electrictroy2010]

@MyKharli YEP but some smart people enjoy tedious tasks because they’re curious. Also much of the work is deferred from engineers to technicians (2-year trade school) .

[@PC-Phobic-Jean-Rene]

Thank you for monitoring the SLOW-progress of CTS-collapse Investigation. _A most sad tragedy for all involved, and of course for those who therein-perished._

[@jamesplotkin4674]

There weren't enough re-bar and support columns were undersized, then a lot of extra weight was placed on the pool deck. That, and the water rotting the structure was definitely going to compromise this structure. If they had built to spec in the first place, then maintained it, this deck would not have failed. I don't find fault in the rebar size and strength, but if they just have to test, then go on and do it.

[@Johns-Insights]

Not to mention the extra weight from renovations such as modern shower doors and granite countertops, etc.

[@ifv2089]

Don't think it helped that the materials used was junk.

[@Sean006]

As in most failures or accidents it is often a combination of factors, as you describe.

[@johnbergstrom2931]

@@jamesplotkin4674 But mostly neglect and corrosion.

[@GOPRepubliklan]

@@johnbergstrom2931 Design flaws too.

[@dinosaurdude5668]

The white paint with random black speck pattern is for “Visual Image Correction” . Notice the cameras in the background when they showed the failure of the rebar. The speck pattern unloaded is compared to the same pattern under load. It provides an amazing strain graph , sometimes in 3D even.

[@douglascaskey7302]

Makes sense. We never painted the rebar back in the testing lab when I was studing Civil Engineering back in th elate 70's. It was always a fun day when we got to smash some concrete or tear some rebar apart. 🙂

[@B3TH_anny]

Lol​@@douglascaskey7302

[@dinosaurdude5668]

@@douglascaskey7302 VIC is relatively new tech. I believe it was developed at U of South Carolina in late 80’s or early 90’s. However the computational speed needed wasn’t up to par. In the mid 2000’s computers got way more powerful making the tech viable. It used black and white spectrum 0-255 to essentially create a matrix of numbers from an image (that is why the black specks need to be random). After strain, the computer goes block by block comparing one frame to previous to determine displacement. I hear now they can essentially freeze time to see how projectiles penetrate in 3D (that was true 15 yrs ago, so who knows what they can do now)

[@electrictroy2010]

@douglascaskey7302 IN the 1970s we didn’t have powerful computers that can capture video & manipulate it directly like a visual schematic .

[@CB-vt4ic]

Thank you for continuing to cover this!

[@frednewman2162]

Does anyone else think the way that rebar broke was very strange? There didn’t appear to be any stretch or distortion in the steel before it just snapped! Seemed to just be brittle and not malleable at all!

[@jessicav2031]

Also surprised me. I had heard rebar was junk, but wow. I thought the whole benefit of steel for rebar is that it experiences ductile failure?

[@V100-e5q]

Same here. That looked not like steel more cast iron. I am curious whether this was odd or what the explanation is.

[@wrench8677]

It could be poor quality steel that got contaminated in production

[@1TakoyakiStore]

I suggest watching Slo-mo guys video on testing rebar as that's what it's supposed to look like when it exceeds capacity.

[@ifv2089]

Yeah, steel should bend not snap, acted like iorn, Did it come from China or is that a lie?

[@hopefultraveller1]

Thanks again, Jeff - as ever, fascinating and compelling viewing.

[@Kanesgarage]

Thanks for keeping these stories alive Jeff

[@philiphowell1505]

Hello Jeff, thank you for your update. The only tantalizing thing for me is still those reebars sticking up from the slab behind the H beam, why were they there but no column shown in the photographs.

[@V100-e5q]

Thanks for doing this update for us! Always interesting.

[@rrodriguez9001]

Thank you again for reporting on the status of the CTS investigation. Perhaps you could report on what is happening with the FIU pedestrian bridge collapse.

[@rrodriguez9001]

A video discussing the NTSB findings was posted...I just missed it when it came up. Now that I've seen it, I understand better how that failure occurred. The tensioning, de-tensioning and tensioning of tendon #11 merits more investigation. The design engineer had stated that that member was designed to carry temporary loads during transport, but that eventually it would carry zero load. That's hard to believe. In my opinion there is too much reliance placed on computerized designs. If the software said a member would carry no load (and there is no redundancy) it should raise a red flag to the designer. As it happens the joint between #11 and #12 is where the first failure is believed to have occurred. Little was said about that.

[@TravisTrittFan]

Can anybody explain, three years after the collapse, why we're still seeing cellphone video, recorded off a tv, showing security camera footage of the collapse...and not the actual video file from the security camera harddrive? I have yet to see the original footage shown at the beginning of Jeff's video, they're all the same video taken with a cellphone.

[@ms.shineray]

Hard drives are not made to survive a building collapse. That is not a black box from an airplane.

[@TravisTrittFan]

@ms.shineray The camera footage was taken from a building that was across the street, as shown at the beginning of Jeff's video. Not the actual building that collapsed.

[@ms.shineray]

@TravisTrittFan yes, and that might be the reason why there is so little to show cameras from nearby buildings aren't supposed to be looking at other buildings.

[@TravisTrittFan]

@ms.shineray You're making no sense. There's nothing illegal about a security camera capturing footage of a building from across the street. There's no expectation of privacy in areas the public can easily see with their own eyes. That also doesn't change the fact the footage exists, because it's been recorded and released by a cellphone. There's no doubt the investigators should have gotten the original footage, and I want to know why that's still being kept unreleased.

[@ms.shineray]

@TravisTrittFan Never said it was illegal, I just said there's no more to show, since that camera was not always overlooking there, that camera moves.

[@TheHandyHam73]

During early construction a Crane fell across several Pile Caps severely damaging one which was then hastily repaired with shoddy materials. Even the engineers hired to do the 40 year specified repairs to the Pile Caps after they opened up the sub- area under the Basement slab and inspected it but the condo association didn't listen.

[@TheHandyHam73]

I read through the 40 year recirt plans and found the concrete beam they wanted to install to tie together several Pile Caps reinforcing them.

[@a_trauma_llama2991]

I was wondering about the concrete mixing part...I know that they probably had several companies supplying the pour, and I've seen a local project where the two companies were blaming each other's mixes for a 'bad batch.' Something similar could easily happen, and with this new (to me, anyway) info if they mixed a quik-e batch on the spot that heightens my suspicions. I'm sure there's a way to test all those different samples though to figure out if the low PSI rating was due to the mix or something else.

[@AncoraImparoPiper]

@@a_trauma_llama2991 All concrete that arrives on site is normally slump tested. Each truck's concrete delivery is first slump tested before permitted to proceed to pouring. Surely, this would have been done in this instance? If not, then this is a major failure in carrying a simple standard test that costs only a few minutes and basic equipment. It will therefore be irrelevant who or how many suppliers of concrete there are: slump testing is routine in any concreting job.

[@neilkurzman4907]

No, the condo board listened. But the condo owners didn’t want to pay that kind of money. They’ve been ignoring problems for years and thought they could ignore them a little longer

[@DontCryAboutIt]

Slump testing has nothing to do with the concrete strength. It's for its consistency (flow).

[@williesnyder2899]

Always so detailed, explanatory and fascinating! Your hard word is very appreciated!

[@jeffostroff]

Glad you liked it!

[@allentisthammer4763]

Thank you. I imagine industry experts are holding their breath as I foresee possible reactive recommendations, and underwriter's making policy changes!

[@maryellerd4187]

I really, really appreciate your continued updates. Thank you so much.

[@MrKoenig1985]

During NIST's WTC Investigation (2002-2008) they did use the visuals-organizing software called CUMULUS, developed by Canto, in order to sort, attribute and make photos as well as video clips easily shareable between research-task groups.

[@ABa-os6wm]

What were the findings?

[@electrictroy2010]

@ABa-os6wm WTC got hit by a plane which carried combustible fuel. The intense heat softened the steel support until it collapsed

[@jwneuf]

Rebar seems brittle

[@toma5153]

Yes. I don't know rebar but that straight break without visible necking down and the "sugary" look to the break made me wonder. Would that be typical?

[@yucannthahvitt]

Assuming that was one of the actual tests of the building materials and not stock footage, the full test was not shown so you don't get a sense of the elongation that had occurred already. The extensometer had already been removed so we were only shown the last part of the test. Rebar grades are "Grade X" with X being the minimum yield strength. I am not a high rise structural engineer I am in gas turbines but I would expect higher grades of rebar to exhibit less necking than lower grades.

[@A_Lion_In_The_Sun]

What about the addition of the penthouse? It wasnt in the original plans, and if I recall, it was added to the plans after construction had started. Surely that would have put some extra strain on the structure

[@deborahkennedy1398]

Thanks very much Jeff for continuing to cover this investigation. From a not technological person at all-you’ve made all these videos and explained everything so well that even I understand! And that’s really saying something!! I live north of Florida but I’ve always been interested in finding out what happened here-something that should NEVER have happened! My continued prayers for all the victims and their families 💔💔🙏🙏❤️❤️ Thanks very much Jeff! I appreciate all of your research and videos on this catastrophe.

[@carmisti]

2160 videos!!! Sweet! Thanks, Jeff; you were listening.

[@jockmccartney30]

Differential settlement caused by aggressive dewatering on the immediate adjacent South property line was the final straw that dropped the building already severely structurally weakened.

[@danlowe8684]

Agreed. And the new building ended up being much larger and much closer to CT after city sold the road right of way separating the properties to the developer. The sheet piling being vibrated in and out, only 10 feet away, too.

[@davefoc]

Does a delay in the NIST report affect the families and other stake holders? Maybe, but the general scenario of what led to the collapse is known to a level that is probably good enough to sort out which parties are liable for the collapse. The super detailed investigation going on now is probably more about identifying issues that might impact new building designs and other existing buildings that might have design or construction weaknesses not necessarily related to what caused this collapse.

[@electrictroy2010]

They already got a massive payout from the building & construction company next door

[@scruffy4647]

Makes you wonder about that concrete structure (Mllenium Tower) in San Franscisco and all the foundation trouble they're haviing. Surfside had prior inspections that pointed out severe deficiencies. Apparently, there was not enough money to correct in a timely matter. Really sad for the people that perished.

[@electrictroy2010]

@scruffy4647 THEY had the money, but residents kept voting “no” to repairs. The condo president resigned out of frustration, because he knew the situation was dangerous, but residents didn’t want to spend the money. That cheapness cost them their lives.

[@FunWithBricks1932]

Love your content!

[@davef.2329]

Nice work, Jeff. Thanks.

[@michellesummers]

Thanks for the update! We think your analysis was on the money with both the condo collapse and the Titan sub! Great work!

[@mariemccann5895]

Excellent work Jeff, thanks for posting.

[@greatsilentwatcher]

Longer investigations are good for revealing what happened as well as contributing to investigative experience.

[@alphalima6810]

it wasn't the construction quality, it was the neglect of maintenance, and inspection.

[@markmaki4460]

Yes, this has moved from practical prevention to pure research. I guess it keeps people employed.

[@SianaGearz]

If it wasn't a quality issue, then why was concrete with unusually low compressive strength recovered from the site?

[@beeble2003]

@@markmaki4460 Given the cost in spilled blood, don't you think it's important to learn as much as possible from each incident?

[@neilkurzman4907]

No, it was all of these factors. It wasn’t just one thing that made this building full. It was the design, the construction, the maintenance, the additions, etc.

[@stevewhite3424]

​@neilkurzman4907 Shhhh! Don't you.realize that those two Einsteins have it all figured out. They are just now waiting for the onrush of lawyers coming to hire them to provide their expert testimony in the hundreds of lawsuits.

[@begging4music]

Always good to see You and a new video 😊.

[@3chorses]

Great work on this O Bro, I wonder how many core samples they took on that mud when it was being poured? 1700 PSI...geez.

[@DrJuan-ev8lu]

In their full scale test model they have failed to add in the side pull from hanging deck. This could be significant in causing buckling failure of that particular building collum itself and spread of failure to other collums. At least they are working with the critical point where the building itself began to collapse. But FEA analysis should show that failure of one collum does not bring down the whole building.

[@Ουρανία-ψ7σ]

Did not hear or see anything about Miami condo collapse . Ty for covering it

[@JelMain]

And finite element analysts are not like taxi drivers, going to wait until you're ready. It's a rare skill, and much in demand..

[@PearlCottage]

Every time I watch these videos and see the intact pool . I can only imagine what it would have been like to be in that pool and the tower collapsing in front of you.

[@V100-e5q]

Might be breathtaking, literally. All the dust that was in the air.

[@electrictroy2010]

@V100-e5q Imagine being INSIDE the building as it collapsed. If you look at the collapse video, you can see one room went from dark to light (someone turned on the light). They rode inside that room as it fell downward .

[@Iconoclasher]

Makes me wonder if they're looking too much. They'll end up with a few hundred thousand possible points of failure and they'll never really know which one was the cause. I think it was Jeff in a previous video that showed what happened, and far as that goes it's probably a 95% probability. I can live with that!

[@jimgraham6722]

Thanks Jeff, great discussion as usual. Rebar reinforced concrete likely only has a safe life if there is any risk of tension and/or corrosion which is usually the case. Pre stressed is the better way to go if an indefinite life is required, particularly designs that allow the cables/rods to be individually replaced when they start to lose strength and/or tension. Pre stress in these circumstances is more akin to a fail safe structure. With concrete always in compression, the structure can be maintained indefinitely, the Pantheon in Rome is the classic example.

[@majikglustik9704]

That's a beautiful kitchen, Jeff. Kudos!

[@markknister6272]

Great work. Thank you.

[@K.C.Fizzicyst]

I did see them. I appreciate those uploads.

[@TitaniumTurbine]

He was talking to everyone by recommending his prior videos, not just you. 😂

[@gerbil7771]

My dad worked at a engineering shop that had a puller like that. We pulled apart a 2" piece of round bar and it was shocking to watch as a kid. They used it to pull test composites.

[@Sean006]

Just because something stood for 40 years doesn't mean it will remain standing for another 40 years. Using that hypothesis buildings would never fall down once they have stood for a few years. That was a very slick video produced by the testing company.....they are trying to justify something, probably either the time taken or the cost.

[@DL-cs6fz]

You are my Go-to engineer/ genius, for all things condo collapse and Titanic faux-sub. Thank you for all your work!

[@ForTheBirbs]

I'm medically retired from Australia's science organisation CSIRO. Well done on your presentation of the data.

[@toma5153]

Hi CSIRO. Just a great organization. Been to visit your colleagues Melbourne way from the U.S in 2006ish. Never did see a kangaroo.

[@ForTheBirbs]

​@toma5153 cheers! Lol

[@tommybutler2454]

This is extremely fascinating, to see these people, going through all this, and finding answers. Idk how they do it, but am so glad we have people who can ! It is amazing ! And God bless them for what they do. It will surely save lives. ❤ 🙏

[@jessicanicolebelmonte6252]

I find it extremely scary that some piles have barely 5.7% of the required compressive strength: 170 psi instead of the required minimum 3'000 psi, according to the testimony at 7:45.

[@paulnewell927]

That was 1700 . 57%

[@helpyourcattodrive]

I’m from Miami. Very interesting.

[@KayInMaine]

Who remembers the horror of seeing the collapse on the surveillance camera? Still haunts me! So creepy!

[@vailewalders1395]

This is the freakiest thing, the moment before I saw your video, the Champlain Towers South collapse popped into my head don't know why, I wasn't looking for it, didn't know you were going to do a video on it, didn't see any clips, hadn't heard anyone talking about it in a long time, I was just fooling around on my Chromebook looking at You Tube videos at random, and here was your video, now I'm freaked out

[@TitaniumTurbine]

This happens to me sometimes too, but it may have been in your suggested/recommended list but you didn’t see it at the time… but your subconscious did.

[@vailewalders1395]

@@TitaniumTurbine The only thing in a list if I had seen it which I didn't was the listing of all my You Tube channel subscriptions, in that list is "jeffostroff" as well as all the others I'm subscribed to but it didn't include anything about content

[@v.roni007]

Hi thanks I am enjoying you content.

[@major__kong]

I'm an engineer and I don't quite understand the depth of this analysis and testing. Not even the NTSB takes this long. At the end of the day, I think all this is going to prove is, if the building had been built correctly as designed and according to the code of the day, we wouldn't be having this conversation. Maybe the goal is to discover how poorly a building can be built and maintained and still not collapse.

[@billj5645]

Maybe it's academic at this point. They know what the deficiencies were in the original design and construction but that doesn't explain exactly where the failure started and how it progressed through the tower. I'm a structural engineer and I have my theories but I'm waiting to see what extensive analysis shows. My theories are based on what I've seen from the drawings and what I've seen in various youtube videos. I don't have access to all of the as-built conditions that NIST has from all the different pieces of the building.

[@alilonghair7792]

My theory is that they are looking into it at a greater depth than required due to the other 2 Champlain towers still standing. If they are modelling actual size building segments for load testing, there must be something that doesn't add up that they are seeking confirmation of. Otherwise, it would be hard to justify the extra expense and time of doing so.

[@NiallWardrop]

I agree, not sure what the point is of this level of analysis. We know how to build things that don't fall down, we also know that it was obvious that this building was in a bad state but nobody did anything effective about it. If they really wanted to avoid a repeat then a fraction of the time money and effort put into inspection and enforcement of new and existing buildings would be actually useful.

[@geoff_va1]

This is what happens when you have the budget of a government agency. Tax dollars!

[@beeble2003]

@@NiallWardrop "We know how to build things that don't fall down" Yes. And we know this because, when one does fall down, we don't satisfy ourselves with "Yeah, it obviously wasn't built right, so build better next time, builders." Rather, we look for any secondary causes so we can learn as much as possible from each spillage of blood.

[@ThejasonJaw5442]

Best ocean video's

[@Newman0791]

Wow. Interesting study. I was in close proximity of a gentleman who was a specialist in the “ART” of recommending and developing all ranges of concrete, who at the time formulated slabs for International Airport Runways 6’-8’ thick, if I’m correct. He had give me a brief 101 of manipulating concrete for various strengths in direct relation to a wide range of purposes and characteristics. Thanks for your insight!

[@ConcertShutterbug]

Do building collapses typically take 5 years to a final report?

[@CollapseOfChamplainAndMore]

No they are delaying it on purpose

[@PearlCottage]

​@@CollapseOfChamplainAndMore Why?

[@cuttheknot4781]

Dog and Pony show. They already know who their boss is (most powerful force leaning on them).

[@KnightRAF-407]

⁠@@PearlCottagemy guess is because the report is going to be a disaster for a lot of people who own condos built in the 70s and 80s (even more so than what we already know has been) and they want to make damn sure all their ducks are perfectly in a row and perfectly documented for the inevitable lawsuits that will probably be flying for decades

[@neilkurzman4907]

@@cuttheknot4781 Let us know who their bosses? And why they’re delaying it since you seem to have this information.

[@stevejones7574]

What about the issue of not enough reinforcement rods, and/or their placement and connections inside the beams? Substandard concrete is a given with the 30 year history of MASSIVE corruption when this tower was built. The corruption was widespread, and after Andrew's destruction made it obvious to anyone paying attention that a massive number of inspections were being signed off but not performed (competently), the Dade County Commission was disbanded, and Miami-Dade came into existence. That has been 30 yrs; thankfully, I don't have any clients involved with Dade construction any longer.

[@timothynelson3841]

In all the videos I’ve watched of the collapse, only once did I see mentioned the tons and tons of marble, granite, and travertine added during upgrading of the building. It was originally designed for framing, drywall, wood and structural concrete. Tiles added to the balconies was just a fraction of the added weight of remodeling. The immense added weight exacerbated the deterioration issues resulting in a collapse that was hastened by lack of study.

[@jonathanleonard1152]

How about a report on repairs of ocean front concrete residential structures, anywhere in the USA? We might be surprised to see the costs involved.

[@Brooke95482]

CalTrans concrete mix: Fill a cubic yard box with rocks. Add gravel while shaking the box but keep the volume at one cubic yard. Then add sand while shaking the box, but keeping the volume at one cubic yard. Now add cement, while keeping the volume at one cubic yard. This typically takes 4 sacks. This will provide very high compressive strength concrete. A "5-sack" mix can be made as above, but without any rocks. This mix can be pumped through smaller diameter hoses and so is a lower cost and faster process. But it is not as strong as the above mix.

[@cspringer6832]

I work in aerospace. That rebar failure looks very brittle. Is that typical for rebar? Most steels we use in aerospace would show a more ductile failure?

[@bcatalogrecords]

jeff, do these guys really need to wear the hard helmets at the desk when they're measuring rebar?

[@AminaZaira777]

I was there 16 hours before the collapse, the additional roofing materials for repairs added weight to the structure, some 10,000 lb. Horrible moment in history, I’m lucky to be alive.

[@jeffostroff]

Many people thought that it had something to do with it, but the materials were all on the stronger part of the building that survived

[@jed1729]

When they poured concrete from this Tower did they send a side pieces of concrete to be tested later on that's done today or was that not in doing then and now when they built these towers

[@criticalevent]

I think it's been pretty satisfactorily explained what happened.

[@kmagnussen1052]

Is rebar suppose to be that brittle? I would have thought it would have been more ductile.

[@brianerock]

Very competent forensic engineering

[@scottieb1]

Does anyone know the keyboard dude is using at 5:49?

[@BigBen621]

At 3:08, "lbf" is pounds force, not foot pounds as you said.

[@shannonlucille7477]

this still gives me nightmares

[@andy6041]

In 1981 a crane collapsed cracking the foundation of that building but yet they kept building it . You can find the video in KZbin showing a large crane over weighted slammed down

[@rogergriffin9893]

Perhaps some of the concrete weakened over time due to environmental factors? Too much extra weight was on the pool deck. But I still think that periodic inspections should have detected potential problems.

[@craigpridemore7566]

I'm obviously not an engineer because I'd never thought about stretch when testing rebar. I'd thought about bend and break, but never stretch. It's obvious after you hear it...🙄

[@TH-1207]

Fron that picture depicting the Miami linestone and the piles, etc. could the limestone have been a contributing factor? The linestone underlying Florida is pretty rotton and subject to collapsing forming massive sink holes. A small collapse under a support column could possibly initiate a collapse of a building.

[@danburch9989]

8:00 "A chain is only as strong as its weakest link." Once that one 1700psi colum failed, all of the load it was supporting was transferred to adjacent columns and over time, the domino effect took place. My opinion.

[@tedsmith6137]

lbf is NOT foot/pounds of torque. It is pounds/force applied. You should know that.

[@tgschaef]

I came looking for this correction. Imperial system suffers from using pound for both mass and force. A one pound weight from earth would have 1/6 lbf on the moon, but still 1 lbm.

[@beeble2003]

@@tgschaef Right, but the issue here is that he said foot-pounds instead of pounds force. Foot-pounds is a unit of torque, not force.

[@beeble2003]

Note that it's foot-pounds, not foot/pounds. "/" would indicate division, but torque is force multiplied by distance.

[@tgschaef]

@@tedsmith6137 yeah, I was clarifying why the designation was important. Not many outside of a science/engineering training would even know there was a difference.

[@calebmurdock2028]

Jeff, why does the pull strength (tension strength) of rebars matter? Aren't they supposed to provide lateral strength -- i.e., to give the concrete some tensile strength? Indeed, it seems to me that they would be called on to provide more compression strength than pull strength.

[@eagle94haslanded]

I hate upper kitchen cabinets. They should just be shelves. You made them double decker. Thems fightin words brother.

[@arthurcoleman6908]

Thanks for the update, Jeff. I think the weakness of the garage piles is red flag and aligns with your theory on the collapse, along with the weight of the planters on top. I'm not an engineer but I still believe that high-tide saltwater intrusions played a role in the weakening of the piles and rebar, and led to the collapse?

[@tcpratt1660]

Looking at the labeling for the July and August 2024 Structural Tests in the NIST on the 12 September 2024 NIST PDF update, the July image is labeled "at UMN", and the August image is labeled "at UW". But I cannot easily find confirmation as to what universities are referred to in those images. Does anyone have that information? Thanks!

[@fionanatalieholden5965]

Jeff, well done on another superb vid. You never disappoint us. Thank you for all your hard work and brilliant insights. If I had a teacher like you at school I don't think I'd have ended up the thickie I am! 😹😹😹

[@genepozniak]

Why press the concrete but pull the rebar?

[@Aviation.Safety.]

I'm retired NTSB . Big deal, right? These NIST inspectors are amazing, IMO...and way more intensive than any investigation I've been a part of....except TWA Flight 800.

[@GeneralKenobiSIYE]

There was almost no plastic deformation at all before it popped... It looked like broken cast iron rather than steel. With how that rebar broke, wouldn't it make concrete more brittle rather than ductile?

[@rcsontag]

The delay must be due to finding extraordinary evidence that demanded more extensive testing.

[@daniellassander]

Working at the hustling pace of tectonic plates moving.

[@KOZMOuvBORG]

5:39 Young's modulus (Stress vs Strain)?

[@ZEOPHYTE72]

Jeff, at 3m:08s into the video, we’re talking pounds-forced (lbf) not foot-pounds, correct??

[@kokoprojekt9934]

I saw the design documentation of the building, materials from the implementation and a lot of films after the catastrophe. The building had many design, execution and operational defects. However, it stood for 40 years and would probably continue to stand if it were not for two cardinal mistakes. The first mistake. The ceiling of the terrace by the pool from the axis 10÷15 and from the axis J÷Q was not concreted during the construction of the high part of the building. There, a crane was driving on the floor of the garage. This ceiling was made only after the construction of the high part of the building was completed. A fragment of the ceiling of the terrace by the pool to the N axis was made correctly, but the remaining part that collapsed was made incorrectly. Here, after concreting the floor slab to the level of the upper reinforcement, a break was made and after the concrete was set, the upper reinforcement was added over the columns and the rest of the upper part of the floor slab was concreted. This break caused the upper part of the floor slab to never connect to the bottom concrete of the floor slab. I am amazed that this defective ceiling lasted 40 years and did not collapse sooner. The lower slab without upper reinforcement bent a lot in the spans between the columns and cracked because there was not enough of this lower reinforcement. The upper part of the slab also cracked between the columns. The second mistake. The one-storey external structure of the building should be separated from the high part of the building, because these two blocks work completely differently. They are not compatible. Then a poorly built terrace could collapse without consequences for a tall building.

[@WhittyPics]

I thought this story was over. Is the sister building still safe?

[@leonard530]

I think connection failure played a role in the complete collapse of the tower. As to why the building collapsed so completely

[@johnnychang4233]

Was the rebars pre-tensioned inside the concrete?

[@billj5645]

There was no prestress or post tensioning indicated in the structural drawings. Rebar is typically not involved in prestressing or post tensioning, they use much higher strength steel for that. Most of it looks like a form of cable and not deformed reinforcing but there are some special made deformed bars that can be post tensioned. They will have roughly 2.5 times the strength of normal reinforcing steel.

[@johnnychang4233]

@@billj5645 So the function of rebars inside concrete without any tension are acting like dampeners for vibration?

[@sqike001ton]

And here I thought this one was over and they determined that the major cause was lack of maintenance

[@davidrasmussen2975]

That failure crack plane appears to be brittle and not the expected ductile material that rebar is.

[@minxythemerciless]

The actual numbers need to be run against the design safety margin for the component. For foundations and principal structural elements in a building that is 3x. That is they are built to withstand 3x the maximum design load.

[@Jeph629]

Florida is a good place to assess concrete strength. Some years ago engineers criticized the construction of the Skyway Bridge across Tampa Bay saying its concrete was specified with limestone aggregate* as opposed to granite----making it weaker than standard specifications would warrant, and certainly more prone to acid-condition breakdown. (*Limestone is a Florida product; granite would have to be imported from the northeast. Politics.) The bridge was built around the same time as the condo.