Best Condo Collapse Theories: Me Or Miami Herald House of Cards?

In this video, we compare the root condo collapse root cause that this channel has produced, with the Miami Herald House of cards article. Who is correct, what are the similarities? Who has the most accurate timeline?
Link to Miami Herald Interactive Article "House Of Cards": www.miamiherald.com/news/spec...
📺 WATCH: Sad: Crushed Cars Miami Condo Collapse At NIST Site
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📺 WATCH: Miami Condo Collapse: NIST Investigation Update 11/8 NCST: • Miami Condo Collapse: ...
📺 WATCH: Miami Condo Collapse: Engineers Baffled By Mystery Column:
• Miami Condo Collapse: ...
📺 WATCH: Miami Condo Collapse: Water Attacked Roof, Inside, Pool Deck:
• Miami Condo Collapse: ...
📺 WATCH: Miami Condo Collapse: 4 Engineering Fixes May Have Prevented It
• Miami Condo Collapse: ...
📺 WATCH: Surfside Condo Collapse: New Video Proves Garage Column Fell • Surfside Condo Collaps...
📺 WATCH: Surfside Condo Collapse Exclusive 4K Site Video I Recorded: • Surfside Condo Collaps...
📺 WATCH: Surfside Condo Collapse Site View NIST Video Ground Zero
• Surfside Condo Collaps...
⏱ Table of Contents Surfside Condo Collapse (Click on timestamps to jump to a chapter) ⏱
0:00 Introduction to Miami Herald House Of Cards article and my collapse theories
1:05 Synopsis of Miami Herald interactive animated article on the Condo building collapse
1:35 Discussion on columns thickness
2:40 Concrete support beams in the garage of Miami condo collapse
3:40 Floroplan discrepancies between submitted plans, as-is floor plans
5:55 collapse theories of Champlain Towers South condo pool deck
9:00 Timeline of condo collapse
12:05 Collapsing condo pool deck triggers fire alarm, but no sound?
13:25 Which support column collapsed first?
16:16 Theories on the start of the condo building collapse
17:40 Fitness center collapse origin theory
Maud's Condo collapse Timeline Spreadsheet: CTS Collapse Witness Statements
docs.google.com/spreadsheets/...
The Champlain Towers South condo complex collapse was located at 8777 Collins Ave. in Surfside, FL, which is just north of Miami beach.

[@dawnelehman2592]

Thank you for posting this (and also your prior) video. I am the engineer who led the technical aspects of this study for the Miami Herald. If you look at the article on the modeling, you will see that we do not see damage initiating at Unit 111. Instead, the modeling shows that the damage propagates into the tower at the gym. Structurally, this is logical since the framing at Unit 111 is more robust than the framing at the gym and the connection of the floor framing to the core wall is not sufficient to sustain the demands.

[@jeffostroff]

Hi Dawn, thanks I'm glad you liked the video. The one issue that I see here is that of course I still believe that the third column in the tourist video which is M11.1 was probably brought down by the collapsing pool deck and so that's why I showed in the tourist video that you could see the third column appears to be missing there. So, keep in mind that the very spot where column M11.1 stood is where in 2018 the engineer Morabito discovered the most amount of damage and cracks on the ceiling near unit 111 in the garage and stalactites from improperly repaired grout injections, as well as the grout injection ports were left in the ceiling illegally. I think the beam you mentioned under 111 was weakened, and possibly already under tension as we pointed out in Fiorella's garage video. So, I think that if you take column M11.1 out of the equation, you have a much-weakened support structure in that area that now has an increased load demand on it, plus the rotating beam along the southern edge of the building. Do you think any of this could have reached over to the fitness center connection to the wall there and maybe it all migrated in that direction? I don't know if the simulation can take into account things like that, the cracked and weakened ceiling. Could it take into account for example things like the concrete no longer being rated at the PSI that it was when it was originally poured because of all of these cracks and water intrusion and spalling over the years?

[@thecollapseofchamplaintowe7199]

Thank you Ms Lehman Your Analysis and investigating of this is Brilliant . And congrats to the whole team at Miami Article. If this Visual animations is the future of some articles , then The Miami Herald has risen the bar extremely high ! I had the same theory except I have different columns.

[@billj5645]

@@jeffostroff There may be an element of speculation in where the failure originated because we have no way of knowing or at least quantifying the amount of deterioration of the reinforcing at any given location. The pool deck structure could be modeled and the loads applied to the best of our ability based on planter locations and so forth but there will be some uncertainty in this too because we won't know the as-built thicknesses of mortar setting beds, planter walls, etc. This analysis could show the location that the most overstressed and this could be a clue. However the overstress would be calculated with respect to the reinforcing steel that is on the drawings and there could be locations with very significant loss of section due to corrosion meaning we wouldn't know what location is really overstressed the most based on its deteriorated state. Where the failure originated would have some bearing on which columns in the tower were affected first because the failure would likely progress outward from the origin and it would hit the tower where it hit the tower. Once one location fails it will transfer load to surrounding areas in which case there would be failures there in flexure or in punching shear, and so on as the failures progress outward through the pool deck. I think the nature of punching shear is such that once one span or support fails it not only adds load to nearby critical shear sections it also adds unbalanced moments at these areas and that alone is enough to cause new punching shear failures. The small offset beams around the perimeter of the tower do not have enough torsion capacity to resist this so they would easily fail in torsion allowing the deck slab failures to progress into the tower where the column capacities are now affected.

[@rubyoro0]

So is North also missing those beams? Do they also have that retaining wall?

[@thecollapseofchamplaintowe7199]

@@rubyoro0 interesting question 🤔

[@rendaowe]

So happy to see you give the accolades to the works of the Miami Herald, they need to get an award for their report, for real! Ku-dos to your H beam theory being right on the nose, that had to have solved that feeling that wouldn’t go away. Thanks for great works Jeff, I’ve been following you on this all the way. So glad that I did. Nothing but the facts!

[@jeffostroff]

Thanks, I'm glad you liked it!

[@rendaowe]

@@jeffostroff, Loved it, that’s exactly what happens down through the chains of construction. Build it like the approved plans say to build it!

[@markusgorelli5278]

Jeff, I think you deserve a heap of credit. After all, the Miami Herald would have had access to additional sources of information that you would not have had access to. Yet, you were still able to put together a coherent sequence of events to tie in all the fragments of available info together. I guess the only thing now, is to wait for the official NIST report - although I secretly wish someone could sneak you in to get a peek - not at their report, but at the footage they would have taken as the building was cleared away and the layers taken off.

[@jeffostroff]

I desperately want to see all the Champlain Towers security camera videos

[@EPICRANDOMGUY02]

@@jeffostroff Did anyone make any freedom of information requests for the cctv, or is it not allowed? EDIT- Just saw your reply to another comment about it, I wonder why they havent acknowledged it. Strange

[@jeffostroff]

@@EPICRANDOMGUY02 Yeah it looks like the police just aren't even going to answer people answer people I may try again but they're probably not going to release them any time in the near future maybe even until the investigation has done so it could even be years

[@EPICRANDOMGUY02]

@@jeffostroff I wonder what it shows that they think might affect the investigation, maybe its to try and prevent a cover up attempt by whoever could be most responsible. Also, just like to say been following your videos since it happened and you've done a great job, I'm glad enough people are taking the time to look into this 👍

[@thecollapseofchamplaintowe7199]

According to the lawsuit they don’t exist

[@spaghet_me4518]

I’ve been watching you since the beginning. Thanks so much for keeping up with everything. You are the person I go to for info on the collapse.

[@ToriHartman]

Jeff, a proud moment for me to see your work acknowledged! I have watched EVERY single one of your videos, and one thing kept coming to mind, over and over... In retail stores, when supplies are delivered, each item is counted, and accounted for. Even Starbucks counts and track the "beans". And on movie sets, script supervisors watch over each moment of dialogue in the script. yet, on construction sites, they may deliver a few short - or they pour the cement and they miss a few rabars... it seems so odd that an industry that is in charge of securing safe buildings where people live... 1. where's that person scanning each item into the computer? Then those items are assigned to one column - and checked off on the design loaded into a computer. When they come back to lunch, they see 7 items delivered, and they cannot move forward with that structure for that day. To have a few full time workers overseeing each computer entry -- who work for an independent company -- the the city requires being hired -- when a discrepecy is entered - the people who need to know -- get a signal. All I'm saying is... that while the building plans in a tube are the image that the public has of construction sites - I am shocked that in this day - we are not able to put ALL plans, deliveries, each detail of a build - on a computer. Isn't saving one life worth making a change? just thinking... thank you for all your hard work.

[@jeffostroff]

I am hoping that this will be the wake up call that the entire industry sits up and takes notes on to avoid something like this from ever happening again and it really takes a partnership of the architect, the engineer, the city inspectors, the building maintenance managers, the homeowners association, and even the owners who normally don't like to have anything to do with the meetings and the association but they should know what to look for when they're driving into their garage every day so they can keep the homeowners association on their toes.

[@ToriHartman]

@@jeffostroff Yes! It is a partnership. Well said.

[@jeffostroff]

Link to Miami Herald Interactive Article "House Of Cards": www.miamiherald.com/news/special-reports/surfside-investigation/article256633336.html

[@innagottadavida8538]

The Miami Herald should be thanking you for posting this link. A lot more people will see their excellent interactive article because of it. I found it quite fascinating.

[@Fourthegoodofall]

From the ring video in 711, it appears to me that the building may have been sagging in the middle, as the box on the left suddenly leaned toward the right. However, the debris falling seemed to change direction a couple of times, indicating that the building was shifting. I am wondering if the 10s fell first, as victims from the 11s seemed to be found sooner. Perhaps that is because of the instability of the standing portion, or perhaps because they fell first. But I agree, in the surveillance video, it appears to collapse first right in the middle, where the 11s are. The video from Building Integrity regarding the damage to the south wall during construction of 87 park and sidewalk, where chunk of the wall are missing and filled in with gravel, appears to line up with the damage shown in the “House of Cards” video. The overlay you did of the garage entrance video from CTS North does show that the M11.1 column is not in place in the enhanced tourist video. It is possible that multiple columns along the south wall of the building had fallen when the pool deck collapsed, which could be the reason for the shifting described by Gabe Nir and which probably caused Maria Iliana in 611 to wake up and check her living room. As for what triggered the deck to fall, it appears to be the accumulation of stresses, like when the masking tape on a Christmas card finally loses its grip, and the card falls from the mantel. The sounds heard by Elena Blasser in 1211 the previous night and these heard by Gabe Nir’s sister in 111 at 11 pm are definitely telltale signs of trouble. Morabito’s report definitely raised some alarms, especially after core samples were taken and he was concerned about destabilizing the building by doing further work on the pool deck. It is a mystery that two engineers living in the building were not alarmed. Great job with pulling all of these resources together, raising questions, and providing detailed analysis, excellent graphics, and possible causes.

[@jeffostroff]

Good summary thanks

[@jonclassical2024]

Another solid video Jeff, thanks! I am very motivated to review the Miami Herald "House of Cards" story. I think you still have a solid point on the "missing 3rd" column in the line-up photos comparing North condo building to the tourist video...I hope you get a chance to speak more to the people at the MH about this. Judging from what you showed of their work...it does look fantastic and I hope they do win accolades for doing real investigative work, lacking in so much of journalism today. I also loved your "I've be there" descriptions of what really happens on job sites and even the "as built's" may not be always accurate! ....like the rebar didn't get delivered, lets go to lunch, in the afternoon, oh, just pour the concrete with the few pieces we put in. (who's gonna know!) I was involved with hotel construction (owners Ops team pre-opening) years back and the stuff that goes on is unbelievable!

[@jeffostroff]

Thanks for watching Jon, glad you liked it!

[@willschultz5452]

Thanks again Jeff!!! Your research and reporting are top notch!!!

[@jeffostroff]

Glad you like them!

[@TheBloodOfJesusChannel]

Thank you again for another informative and accurate video on the bridge and Champlain towers! I watched each as they came out!

[@jeffostroff]

Thanks, I'm glad you liked it!

[@markwonders3485]

What struck me most about the Herald presentation and analysis was that they gave a meaningful explanation for security guard Shamoka Furman's statement that it started with a "boom, boom, boom." That never made sense to me -- the sound of the pool deck falling in would have been more of one big "Whooooom!" The Herald's expert associated the individual "booms" to failures of individual pieces of rebar connecting the pool deck to the perimeter wall, and even threw in a recording from a lab of what such failures sound like -- "boom boom," indeed. That seemed to be a basis for their conclusion that the connection between the pool deck and south perimeter wall, where failed rebar ends apparently are visible, was the initial failure point. It makes sense, I guess, as far as it goes -- and it does tie in nicely with the claims in the lawsuit that point to the vibrations and drainage from the 87 Park project as causal factors. That said, a lot of their other analysis was familiar to me already from your videos!

[@erichaynes7502]

I guess it could be three points giving way in a domino effect, boom!, Boom!, BOOM! Shamoka is one of the few earwitness to the collapse so her statement is very significant. I will say I didn't know much about the pool deck/south wall connection being the possible initial failure point but it's believable. In short, the pool deck was so waterlogged and badly maintained it literally was an accident waiting to happen.

[@jeffostroff]

Yes and I have read reports then in situations like this people often have a Thai hard time articulating into words the exact sounds that they heard and so the interpretations can be quite varying. For example she made two 911 calls and on one of those calls she told the operator there was an earthquake.

[@thecollapseofchamplaintowe7199]

@@jeffostroff yup ur frontal lobes fire and the rest of your brain shuts Down. Fight or flight. Nothing in your mind is thinking clearly apart from escaping the threat. So much so that people can lose control of their bladder etc . TMI 🙊 Pretty primal. I know a vet That has no clear memory of a situation he was in. I won’t put it here . But he says looking back it’s like you only have memories like “snap shots”

[@booterone1]

Excellent update Jeff, thanks for the views.

[@jeffostroff]

Thanks, I'm glad you liked it!

[@tylercorr22]

Great video. That was smart of Miami Herald to engage you in this, as your channel has tons of subscribers that otherwise wouldn't have found their article.

[@jeffostroff]

Very true!

[@LakeNipissing]

Thanks for the link to the Miami Herald article. *_Happy New Year_* I can listen to your calm voice describing this disaster for hours!

[@jeffostroff]

Thanks, I'm glad you liked it!

[@clouddancerss]

Excellent as always! Thank you for doing these!

[@jeffostroff]

Glad you like them!

[@Mark-ct5lq]

Another great video Jeff. Thanks for the link to the "House of Cards" article.

[@jeffostroff]

Any time Mark

[@chesshead3943]

Impressive analysis, thanks!!!

[@roubinekibinian1578]

Great Job Jeff . You did an ammazing job . I think your analysis is the best one 👍

[@jeffostroff]

I appreciate that Roubine, thanks!

[@patrickmorrissey2271]

Great job on this.... I really feel like you & Josh are doing by FAR the best work on this...... In a perfect world, NIST would bring you guys in to see what they have...... I have no doubt you could shed some light on it.... btw I am loving the Husky toobox I got over christmas... Thank you for your videos on tool deals.... I saved like $300 bucks on that, and that box is sweet..... so, thanks for all you are doing, I appreciate it.

[@jeffostroff]

Thanks Patrick! NIST has a bunch of smart guys, and they have all the materials that collapsed, they don't need me

[@georgiazettakaragianni9832]

Great video, as always!

[@jeffostroff]

Glad you enjoyed it!

[@RuthTaty_]

Quite beautiful, interactive report. I’ve watch all your videos on the Champlain Towers which is how I became a fan of yours. Great job 👏🏼 Ps: I also think it they don’t want to use that column as evidence because they make think the “lack” of that column could just be a shadow cause by all the debris. But I agree with you.

[@jeffostroff]

Glad you like them!

[@gtaelement137]

Hi . Thank you for the update 👍

[@jeffostroff]

No problem 👍

[@faronrich9381]

Thanks for the information about the Miami Herald presentation. I live on the other side of the country, so I have to look for information about the collapse myself. I feel for the survivors and families of the victims. It seems that, like most disasters, it was a series of events, not just one that brought down the building.

[@jeffostroff]

Glad to help faron

[@TheBloodOfJesusChannel]

EXCELLENT EXCELLENT JOB AGAIN JEFF!!! Thanks!!

[@jeffostroff]

Glad you enjoyed it

[@TheBloodOfJesusChannel]

@@jeffostroff your expertise as an engineer is always evident as you show us the obvious to you causes of these disasters! One can have full confidence that we know what in all probability happened and why! Others should be so well versed/ knowledgeable! Seriously thanks!

[@kenworcester4387]

Thank you Jeff!

[@jeffostroff]

Thanks, I'm glad you liked it!

[@dereksellars]

You are Dead Right on everything!!! I've watched a few others, and they are nowhere close to yours, in my opinion. You laid out every detail in an Awesome format, I can't believe they have never contacted you. Or maybe I missed it. Thanks, Jeff :) headed your way on the 16th- to Treasure Island for a few days. It's TOOOOOOO Dam cold here in Iowa....

[@jeffostroff]

I would love some of that cold for 2 days, snow too

[@dereksellars]

@@jeffostroff I don't know about that, it's like 15 below wind chill here tonight.......BRRRRRRRRRRR

[@tricky0001979]

When I saw the video and it was based on the article I hadnt seen I went and read it and it was so well done, I thought about the crank YTuber who claimed people were stealing his ideas I bet he would of seen that article and claimed they stole his work like people cant think about things for themselves. Great video keep up the good work.

[@jeffostroff]

Thanks Richard, glad you liked it!

[@cynthianorthdakota505]

I am hooked on yr KZbins … tyvm Very relatable topics… My POV= It’s appears a lot of free driveways or basements where created with the aggregate products skimmed off this job… 1st) concrete that doesn’t stick to rebar is not mix correctly. Sounds like it was thinned out… as you said, the rebar was clean consistently. That’s the first major clue? Evident evidence without doubt. 2) supporting beams in different sizes will create a collapse overtime. hence the centripetal force load on the lighter beams will cause a collapse. 3) beams that are painted to red could designate, being altered. 4. It is possible that the beams were thickened over the years. They really need some old photos. 5. The roof and what was supposed to appear as indentations of valley creating drains.Vs pictures available after the collapse. I could see it the first time that the roofs were altered so much over the years..That drains weren’t where they were supposed to be and they definitely did not have those dome drains making it top-heavy. 7) because I have to share Y W the world…. How They we’re not required to use Steel beams.. or where they.. Have Y found the blue prints that explain the … I have yet to see the structural design, n materials .., last would old maps show this was a garbage dump prior.. just a thought in response to the way, the building fell and landed after the collapse like there was no ground underneath it hence possible garbage just a thought thank you very much for your platform

[@cynthianorthdakota505]

7) i’m making the seven because I have to share you with the world. However, the way the debris fell and sunk like so low so quick it’s almost like it was built on top of the garbage dump. Maybe you could look and see if that was a garbage dump at one time when surprise me thank you very much.

[@pattyfoster6987]

Thanks for sharing that info. I believe the Herald should have hired you on that team. Your analysis sound correct. Great stuff man.

[@jeffostroff]

I appreciate that! They got some good PHDs on there, but as an engineer with good root cause analysis experience I do enjoy analyzing failure modes and providing corrective action.

[@sadfiremccraven4579]

Thanks for an update it's nice to know the truth about things like this and what actually happened

[@jeffostroff]

Thanks, I'm glad you liked it!

[@remotecontrol1082]

Let's all hope somebody learns something this time!

[@mixedupmenopausaladhd3999]

Thanks Jeff as always. Your eye in this has been tremendously keen. I hope you, Dr Lehman, and Josh do a panel discussion together someday. Maybe picking apart NIST’s findings 😄 Do you think the card table effect that Gabe describes offers any explanation re: the mystery column by the H Beam?

[@jeffostroff]

Great suggestion!

[@jackwhite6030]

very good as always....

[@jeffostroff]

Thank you! Cheers!

[@thecollapseofchamplaintowe7199]

Another fantastic video. As usual. Yes I believe McGuiness was there because they only got one of the permits ( safety anchors ) that day when they’d been working on the roof for awhile . I think your both kinda right. I believe though that the deck ripped from the pool deck wall first though. When I saw the corroded hooks that was all that holding that section of the pool deck up from Kilsheimers pics was likely the trigger.

[@jeffostroff]

Good call!

[@lindarunge4119]

Thanks again for clear concise explanations.

[@jeffostroff]

Glad it was helpful!

[@charleso8826]

good video Jeff

[@jeffostroff]

Thanks, I'm glad you liked it Charles!

[@erichaynes7502]

Thanks Jeff, another great video. I wonder if the pool deck was already at 100% load what was the % when it finally collapsed? Also, the creaking and cracking before the collapse, is this caused by a beam above the parking garage bowing or a beam crunching/crumbling? I guess it's probably both. Finally, I bet the Miami Herald used a ton of info from you videos for their investigation!

[@jeffostroff]

Herald had their own engineers from the second day after the collapse. But yes I would tell early one a few sites were inspired by some of my earlier videos

[@erichaynes7502]

@@jeffostroff Wow, I'm impressed the Herald was on the case so quick, I thought good reporting was dead. Still, if they get an award or 2 you should as well!

[@dawnelehman2592]

Yes. I know I did. The videos are informative.

[@sportsmom165]

@@dawnelehman2592 my daughter is a hydrologist for the Forest Service in the PNW. She paid for college as a rappeller on a Forest Service helitack crew aka wildland firefighter. She also works on BAER (burned area emergency response) teams. Of course she was noticing the water coming up from underneath that was pumped out. As she understands, Florida has a high water table. She was wondering if the concrete columns can soak up water from the bottom too, much like a tree.

[@sportsmom165]

@@dawnelehman2592 thank you for being a woman in STEM & highly regarded.

[@billj5645]

There are some engineering issues with the analysis performed by the Miami Herald. Some of my comments will relate to the Miami Herald analysis and article, some will relate to this video. Columns in one area were bigger than columns in another area, that doesn't mean that the smaller columns are insufficient. The small columns under the east wing are sized fairly close to what they need to be to support the weight of this building. They may look thin, but there are also not very tall since in a parking garage or condo the floors are not very far apart. Office building and industrial buildings can have columns 2 or 3 times as tall as these in which case a small column could be a problem. The Miami Herald story does not conclude that the columns are too small, only that the reinforcing spacing is an issue and this particular issue is a gray area in the building code, the reinforcing in these columns does not violate the building code. The columns are probably the part of the original building that was designed closest to what was required. In the plaza area there are some beams that were removed between the permit drawings and the final drawings. The problem is that these beams were not strong enough for the job they needed to do. The version of the drawings without the beams is stronger than the earlier version of the drawings with the beams. Having a beam or removing a beam might be important, but all beams are not created equal and you have to also do calculations for the strength of the beam before you assume that it would be important to the strength of the building. In fact some of these beams would have been very much overstressed if they had been constructed. I'm writing that without the beams the slab would be stronger, but still not strong enough for the required loads. The Miami Herald engineers are correct in that this slab would have been overstressed from the beginning. Since it was covered up by waterproofing and pavers nobody could have seen the cracking in the top of the slab over the columns. Anti punching shear rebar? Who made that up? Certainly not a real structural engineer. Don't listen to what other youtube channels say about his. There is no such thing, you will not find it in any reinforced concrete textbook, you won't find it in the 1977 ACI building code, you won't find it in the 2019 ACI building code. In 1977 the main way of reinforcing a slab against punching shear was to use steel shearheads and they most certainly did not have these in the Champlain Towers drawings. More recently a product called stud rails has been invented and is widely used as punching shear reinforcing. The Herald article discusses punching shear due to insufficient reinforcing steel. There is no engineering basis for this in concrete textbooks, concrete design practice or concrete building codes. The steel was in fact not placed as required by the drawings but the biggest deficiency with respect to punching shear capacity was insufficient slab thickness and this goes back to the original structural design. Is the fitness center weight important? The weight of all of the materials on top of the structure outside of the pool deck would be very much heavier than the weight of the equipment in the fitness center. This includes the planters, the dirt, the pavers, mortar, grout, and additional concrete topping. And the concrete slab under these materials is similar thickness and reinforcing to the concrete slab under the fitness center. So if the fitness center is of concern then the pool deck loading is of even more concern. The Miami Herald article mentions interaction between the ground floor slabs and the basement walls, as if the slabs are pulling on the walls. They have omitted one important thing and that is that generally it is the other way around- dirt outside the building pushes against the basement walls and they in turn push against the ground floor slabs. So the interaction is pushing not pulling. I suspect they omitted these loads from their computer analysis. This is the reason that Allen Kilscheimer told the city after the collapse that the basement walls were still in danger of collapsing- the dirt outside was still pushing on them and they no longer had the ground floor slabs to lean on. The graphics in the Miami Herald article show how a system like this would normally be constructed however the text in the article and the photos from the site show that the building might not have been constructed this way. The original structural drawings are very skimpy on how this would be constructed and did not show the reinforcing to be placed in the way that it should be placed to properly reinforce a connection like this, however even if built as the drawings show it would not have failed as stated in the Miami Herald article. The article goes on to talk about reinforcing steel failing as damage spreads across the deck. Again they have overlooked the interaction with slab movements with shear stresses around the columns. It is more likely that as one area of slab deflected that the rotation at the columns increased which in turn increases punching shear stress and causes punching shear failures to progress across the pool deck. This could happen if the connection from slab to basement wall failed but it could happen in similar fashion if one of the slabs decided to have a punching shear failure under a planter just outside of the tower. The small beams under the planters wouldn't stop this, the small beam along the edge of the tower wouldn't stop this, and it would continue under the tower at which point the columns would lose their bracing and could fail in buckling.

[@jeffostroff]

Good insight, thanks!

[@thecollapseofchamplaintowe7199]

@Bill J can we snag you for our research group ? Your knowledge and analysis is impeccable ! 🙏

[@thecollapseofchamplaintowe7199]

I agree with that too. It’s more about column spacing at lack of tie beams

[@billj5645]

@@thecollapseofchamplaintowe7199 Maybe

[@thecollapseofchamplaintowe7199]

@@billj5645 if you click on this profile . It will go to my channel . The links are in the comments there 😉

[@stevephillips6106]

Good work.

[@jeffostroff]

Many many thanks

[@ianjeffery3762]

I think building Integrity did a great video on missing beams as a result of removing the step from the 1st floor car deck to the pool deck, and with the removal of the step came the removal of some load transfer beams

[@jeffostroff]

Yes I saw that video of his back in August

[@ianjeffery3762]

@@jeffostroff my first ever reply from a KZbin celeb 😃

[@ianduhfixsinclair2739]

BUT... deleting those beams, freed up $$ for more and MORE shiny marble in the lobby... that's what real-estate scammers call a "win-win"... /sarc/

[@JasonFlorida]

I would be extremely interested in what the simulation showed with having those missing beams installed as well as the other what ifs... for example; what if they did all 24x24 columns, or even 18x18? Very interesting video, thanks a bunch for sharing. I would have never seen the Miami Herald's animation if not for you Jeff

[@jeffostroff]

lad to help!

[@additudeobx]

Thanks Jeff, Straight Up Man...

[@jeffostroff]

Thanks, I'm glad you liked it!

[@jenjenjennyful]

Really interesting video and comparison of theories. I think they may be right about the large planter above the missing beam playing a big role in the pool deck collapse. But I think you are correct that the column along the south wall was crushed/knocked down, and that was the straw that broke the camel’s back, so to speak, causing the first part of the collapse (NOT at the fitness center, but more along the “11 stack”). Very interesting comparison. And I agree the graphics in this demonstration are excellent!

[@jeffostroff]

Thanks, I'm glad you liked it!

[@PeterZiobrowski]

I recently found your videos, and think they are well done, and draw reasonable conclusions. I think we need to have a discussion about the fire protection systems. Sprinkler flow should trigger an Audible alarm, like a pull station or a smoke detector. typically there will be a flow switch at the intake for the sprinkler system, and one per floor, so the panel can indicate where the flow is. you want the panel to alarm on flow, since that likely means a head has been activated due to heat, which can happen before a smoke detector activates. the post collapse video seems to show a strobe activated, but there was no audible tones. this makes me wonder if the system was working properly to begin with, or if it was left in alarm due to a fault, and had been silenced. This is all somewhat dependent on what code required in 1980. Im in Canada, so we put dry sprinkler pipes in attics, so they dont freeze and burst. the system includes a compressor, that pressurizes the pipe, and holds the water back. when the power goes out, the air eventually bleeds out, and the pipe fills with water. this triggers a sprinkler flow alarm. sometimes the panel will reset, other times you need to shut down the sprinkler valve, or silence the alarm if the panel wont rest out of alarm, and have a technician look at it. If we had sprinkler flow in the garage per the tourist video 7 minutes prior to collapse, and that sprinkler flow triggered an alarm, there is a good chance residents would have evacuated prior to the collapse. ( i would also be curious if anyone thought to activate a pull station, especially after the pool deck collapsed, but before the tower came down.)

[@rufkutdiamnd]

Excellent video again Jeff and to Dawn thanks for your deep dives and putting it into terms that a regular person can understand. Could the creaking noises have been started by the bottom of the gym area starting to sag? Also what about that 4th beam that doesn’t show in the overlay of the from earlier?

[@georgiazettakaragianni9832]

@jeffostroff, Shamoka Fuhrman, the night security guard said she thought the sounds before the collapse were from the elevator which was across her vestibule. The elevator was by the gym. Also, Elena Blasser from 1211 who died in the collapse told her son she heard creaking noises the previous night. Her condo was closer to the gym area and over the columns which collapsed first than to the south perimeter wall.

[@jeffostroff]

I believe the creaking was further west of the gym by 2 condo units. Elena Blasser, 64, was the woman who told her son Pablo Rodriguez that she heard creaking noises in the building the night before the collapse of the condo. It is absolutely no surprise to me at all that she was located in unit 1211 and as you know any of the units that ended with the number 11 is what we call the “11 stack”. And from what we had seen most of the people that did escape with their lives were people in the 11 stack who heard noises in the hour or so leading up to the collapse of the condo building period now we don't know why ilena did not wake up and hear the noises when the building was about to collapse and then try to escape. It is possible they were trying to escape and just got caught up in it

[@georgiazettakaragianni9832]

@jeffostroff Yes, the people who survived were near the location of the sounds. I'm sure others heard them but didn't manage to escape. I read people were found in corridors.

[@rubyoro0]

@@georgiazettakaragianni9832 Link to corridor info?

[@bellaladonna]

Binge watching- most extensive channel on surf side collapse

[@jeffostroff]

Thanks, I'm glad you liked it!

[@motorTranz]

The Herald should have used your analysis if they didn't. Another great analysis Jeff! Thank you!

[@jeffostroff]

Glad you think so!

[@HardDriveGuruOfficial]

Huh... I thought I had seen all your Champlain Towers videos, but I guess I missed one!

[@dawnelehman2592]

For those who are interested, this discussion includes sounds of reinforcement fracturing during the testing of a scaled reinforced concrete wall. The bars in this wall are approximately the same size as the bars in the slab-wall connection. kzbin.info/www/bejne/fqq1lYudbampm5I

[@jeffostroff]

Yes that is a whole new area of study that many people likely had no thought of except for the family of the one lady who heard the creaking sounds the day before the collapse. Would like to see more vide/sound of concrete failing. The example shown we could not really hear the audio too well, and would like to see examples back to back to hear differences in rebar cracking vs concrete cracking, vs a crack developing in the wall of a condo unit, like Maria Iliana Monteagudo in unit 611 saw.

[@dawnelehman2592]

@@jeffostroff We are conducting a slab column test soon and I will ask the graduate student conducting the tests to record the sounds. In the lab, the hydraulics are loud so it might be hard to hear but we will see what we can do. The connection we are testing is aimed currently at new design, but I am writing a proposal to investigate new rehabilitation methods for corroded and degraded flat-slab structures. This connection is one of many methods we will investigate to increase the connection strength and the slab strength and stiffness.

[@washingtonradio]

The Herald's graphics were excellent and they give a reasonable explanation as to details of the collapse. Obviously their account is geared to the general public who would want a relatively high level explanation of what happened.

[@jeffostroff]

Yes I liked their graphics and a lot of people thanked me actually for posting this video because they said they would not have found out about that Miami Herald article had they not seen it here on the video.

[@michaellefevers4248]

Thanks Jeff! I followed your series from the beginning. I'll go back and watch their presentation as well. One thing that did cross my mind with the size of the initial supports being 24x24 and the rest smaller. Is it possible that the earlier columns were put in, and an inspector signed off on them..... only to cut corners and put smaller columns in later? Or, do you think the project may have had budget over runs and they thought that the smaller columns would still be safe, not knowing that 30 years later people would be redoing their units and using the the really heavy materials you mentioned? In the end, regardless of column size and unit weight, would the water penetration have brought it down anyway, just further in the future?

[@jeffostroff]

No the real deal with those 24 inch columns is the fact that that part of the building has the large shear wall along the elevator shaft and staircase. And so they added a whole lot of extra beam support on the second level and this requires of course extra thick columns down in the garage level to support all of this extra weight of concrete beams so that is why that part of the building had 24 inch columns.

[@innagottadavida8538]

Josh Porter from the channel Building Integrity explained that the reason that part of the building had thicker columns was likely due to the fact that there was a driveway and parking lot above those columns and they were thicker to handle the dynamic load of cars driving around above them.

[@notgreatnotterrible48years63]

The house of cards interactive article is incredible

[@jeffostroff]

yes good graphics

[@sk8razer]

4:50 is a fascinating (stock image) scene

[@ajtony1313]

Thank you for another great video. You have stated that the initial collapse may have occurred under the planters, and the stressed beam and column under the planters possibly fell first. I recently saw a diagram of that area in the New York Times 3D animation, and it showed that the stressed beam was attached to the sides of the columns using mortise and tenon joints. Is this a common joint used for concrete columns and beams?

[@jeffostroff]

Yes that is a common means of connecting the beam to the columns and one would hope there'd be enough of the thick rebar rods to make that connection possible getting ready to type. but remember a lot of us think that beam was under quite a bit of water intrusion because of all of the peeled paint on it so the question is if that concrete beam starts soaking up water over the years and you could see the patches on the ceiling all around it from the plastic corrugation to protect the cars from getting the water dripping on them. How soft did that concrete get? did it lose its PS i rating that it was originally designed for question mark those are the questions i have period

[@billj5645]

The mortis and tenon is functionally what is used sometimes but the mortis would normally be the full size of the beam, not smaller like a tenon typically is so in this situation it would not be practical because the column is not large enough. The proper terminology would be "beam pocket" or "shear key" and would be more commonly used when connecting to a larger surface where you could form the pocket without compromising the thing that you are connecting into. In the Champlain towers situation it should have all been poured at the same time. The columns would be poured up to the underside of the pool deck structure and stopped, and they would stop at different elevations because some places they support beams, some places they support slabs, etc. The column reinforcing would continue up to where it is supposed to stop. Then the formwork for the floor would be constructed and when concrete for the floor is poured it would fill in the columns as well. So standing in the garage looking up at a column with a beam framing into it, there would be a construction joint occurring lined up with the bottom of the beam. This gives the beam the strongest connection to the column because there is no form of joint going through the beam. The column is in compression across the horizontal joint that goes through it so there is no problem with that joint either. With this garage interior being painted it would not be possible to see these joints in the finished structure, in unpainted concrete sometimes they are easier to see.

[@chiefinspector7280]

I wanted to add a few item to the CTS investigation. The main step beam connecting the building and the desk was reduced in depth from 2’-6” to 1’-6”. Other area of the step beam may have been shallower. This resulted in a massive overload. When the planter beams were torn loose from their anchorage to the step beam and column it caused damage which sent a seismic wave up to the penthouse. It appears the first failure was mid height at the penthouse which had been weakened by the drilling in of anchors recently. If you noticed the south west portion of the tower lacked planter beams that could have caused that portion of the building to collapse. the deck collapsed and punched cleanly through at the columns. So this points to the planter beams being one mechanism of failure of the stability of the structure. ICC and Florida multi trade licensed Building inspector

[@jeffostroff]

interesting insight

[@MajorCaliber]

I'm just glad that Duh Developer--who was not even a US Citizen--made a ton of money by "value engineering" the steaming pile of CTSouth pool-deck down to zero safety margin... so I'm sure there's "nothing to worry about" at his other masterpiece, CTNorth... _rolleyes_

[@1952jjp]

Jeff, you were totally correct in the assumption of the missing column at the base of the ramp. But my question is, could this column have been so pivotal to the collapse? Why was it undersized? Or absent from the final drawings? It looks like the engineering firm that designed the building was using the 'fall back support' mode, where all the outward weigh and force projections, were directed toward a common "stand pin", to absorbe all the inward weight and pressure, and was added as a last minute red line, but not large enough to support the load? Just my opinion.

[@jeffostroff]

Remember that column sits right in an area where the most amount of damage in leaks and cracks on the garage ceiling were found three years before the collapse and of course got worse according to the engineer. So you take out that one column and suddenly all of the other week columns are now asked to carry the burden of the existing wound which they probably were not prepared to do. Also the collapsing pool deck likely might have wakened or taken out another column or two as well.

[@metatechnologist]

You have the fitness center plus the marble in the entryway that should be nearby. Iirc the entire entryway was covered in marble. How much do each of those tiles weigh?? In the lawsuit (mentioned in another engineering channel) the HOA board was concerned with redoing the entryway (which may have taken place) while there were residents worried about structural issues. Those residents had decided to replace board members and had started to actually do so but it was too late obviously to stop the collapse.

[@jeffostroff]

Yes the whole situation is such a shame because the engineering changes they were going to make I think would have really helped out this building if it had just held up long enough for them to make these changes I think everything would have been OK

[@Goldenrod636]

I didn't know about the article because I only get my information about this from you.

[@jeffostroff]

Thanks, I'm glad you liked it!

[@mjohnson9563]

Most important thing is that this is not a forgotten topic. Most buildings collapse due to earthquakes and during the construction phase. So this type of collapse is very abnormal and off the charts. Trying to determine the mechanics of failure on the CTS collapse has been a huge undertaking and at this point there have been a few engineers who have been involved in determining what fell when and how including Jeff, Dr. Lehman and Josh over at Building Integrity as well as a few others who I do not remember. Weather it was the gym floor that went first or the 11 stack, that building was doomed when that pool deck start falling down. Thank you again Jeff. I am going to side with you in that the column near unit 111 started going first but then again, I am just an average joe.

[@jeffostroff]

Thanks and keep in mind all of us even the smartest engineer is an average Joe without having access to all of the debris like NIST has. So we can't run tests on the concrete to determine which columns were the weakest and what was truly going on inside of the material.

[@ED-es2qv]

FYI, a weight stack that is 200 pounds is a big one, and 500 would be huge even for the Ranger gym. Most of them have a spread base that covers more floor than two men talking. In other words, a place people line up close together is probably in as much danger as a gym. My Jeep weighs 6500 pounds, and puts more than half that on the front tires. Parking is definitely a big load.

[@jeffostroff]

Weights combined with failing concrete makes it more unpredictable as to the stability

[@patstokes7040]

At 8:30 you talk about the rebar and how you needed 4 bars per side but when you look at photos that clearly show the column that the pool deck punch threw there are only 2 rebar per column not 4.

[@MajorCaliber]

Silver Lining: imagine how SAFE whatever new condo gets built on this sacred CTS site will be! Imagine how many eyeballs--professional and amateur--will be scrutinizing every detail, every day, every step of the way! The Josh and Jeff fan clubs will form a harsh and unforgiving peanut gallery! Every load of concrete delivered and placed will be recorded on 40 smartphone videos! Everyone will be a critic!... "Fred, does that slump look right to you?"... "You're right Debbie, approved drawings say 6-inch max slump, but that soupy slop looks more like 9 or 10 inches... you wanna blow the work-stop whistle, or should I?..." :D

[@jeffostroff]

I'll even be taste testing the concrete while it is poured!

[@MajorCaliber]

@@jeffostroff Good to have a calibrated TONGUE! We'll go undercover on the screeding crew, measuring cover depth, making our own test cylinders... we'll have drones hidden in our lunchbox, that we fly over all rebar and formwork before the ready-mix trucks show up... ;')

[@starlite528]

Fire sprinklers have a waterflow sensor at the valve that triggers the fire alarm after about 45 seconds (pneumatic time delay.) So yes, waterflow is always supposed to activate the building fire alarm.

[@jeffostroff]

Still strange why no one heard the alarm, unless someone had the warning siren disabled

[@starlite528]

@@jeffostroff Whatever the case, the strobes were at least partially working up to the upper levels. Depending on the fire alarm system, you can silence the audible devices from the fire alarm panel while the strobes continue to flash until you clear and reset the system.

[@starlite528]

Come to think of it, wasn't the lobby still standing? The Fire Alarm Control Panel is usually either in the lobby itself or in a utility or mechanical room nearby. There should be a submittal to the fire marshal showing the location of all the fire alarm equipment. If the engineers on site were able to recover the fire alarm panel itself, that will have the event log of every action performed on the panel.

[@bobh6728]

At 3:15 you show the H beam. Where are the columns that held it up? From the perspective of the picture it looks like it move straight back a foot or so to clear the columns. If that column on the right with the red base could be shown to be one of the columns that held the H beam it would verify the spot.

[@jeffostroff]

The columns that held up the H beam have all collapsed but if you look at the endpoints of the H beam you will see remnants of the columns there sticking a little bit out of the ground so the age being basically slid about 12 inches north and then down the columns

[@Dilberto88]

This all goes back to Nathan Reiber and his notorious cutting of corners. Thanks, Jeff!

[@jeffostroff]

Thanks, I'm glad you liked it!

[@helengarsed3979]

From Australia Jeff just watched this Video at 4.17am.I noticed Mike Bell sent u his comments as i had watched his 3D last year on Champlain Building Collapse.He had sent me a Red Heart liking my imput to his Video.Just wondering what u thought about what he had to say ? As u know i have put my imput to it.But when the Security person and a woman was in Office and she said heard noises and like cracking in the Building and then the Cars fell down from carpark and then in the underground Carpark there was a Strange looking Beam on a angle like Bowed and dont know what was above it.But it may have Broke taking a Column Down and snowballed to another Column and with 16×16 thin Columns to make room for more Parking this may have been the starting of the Collapse.As was the Gym put in later as i really dont think has anything to do with Gym.Plus wondering why that Man was on Roof the Day before Champlain Building Collapsed ? You Jeff have been doing a Great Job with all the work on your Videos and hope it has been looked at by Higher Powers that are taking U on board.Have also been watching Josh on Intergrity as well.U both have been doing a Wonderfull Job and Hoping the inverstergating and understading of all u imputs are taken into Consideration.Good Luck.😇🦋

[@jayyoutube8790]

A drop in water pressure is what trips the alarm. Happens at work all the time

[@PeterShipley1]

You mentioned there's a plan to strip down and redo the pool deck. given the buckling in the collapse of the building do you think it's possible that had it not collapsed when it did It might have failed when they removed structure for the pool deck?

[@jeffostroff]

I heard but have not confirmed it I have not seen any homeowners association meeting minutes, that the engineer might have told them last year that they found the damage in the pool deck was too much to be able to repair it. So who knows what they would have planned they would have I know they were working on emptying out the garage and moving everybody parking across the street. If that is correct that says to me they were going to put a whole bunch of shoring in the garage underneath the building and then they probably could have removed the pool deck without any consequences to the building because the shoring poles would have taken all of the load.

[@minnahumble2294]

I think it’s possible that the “missing column” is actually there in the tourist video. It looks like that planter box came down around it in a punch sheer and smeared it with mud.

[@minnahumble2294]

But in my scenario I have to admit that I cannot explain that white pole lying sideways. Is it a shaft of light? Is the column gone and part of the beam fail there? Maybe part of a drain pipe?

[@jeffostroff]

Not very likely that it would perfectly coat the column with mud.

[@Mickt6]

Hi Jeff I am wondering why the pool still up I don't think it will be use again

[@jeffostroff]

Since it stayed intact they probably left it there so they can study it further if they need to

[@amberw144]

Thank you for not using a victims name in your title to draw views.

[@jeffostroff]

I know exactly who you're talking about. He was spamdexing the titles on numerous of his videos

[@amberw144]

@@jeffostroff it’s just wrong.

[@JBoo]

The most accurate person covering this

[@jeffostroff]

Thanks, I'm glad you liked it!

[@metatechnologist]

Interesting on the fire alarm. There's more than one type. The photoelectric smoke alarm wouldn't be able to detect the difference between smoke and dust.

[@jeffostroff]

I think this one went off from the loss of water pressure in the pipes

[@chiefinspector7280]

The under designed step beam which was supporting the south building columns lost equilibrium and undermined the columns resting on it.

[@jeffostroff]

Yes that is what Miami herald pointed out.

[@geraldinekiefer2827]

Thanks, Jeff and a question. When the middle section of the building collapsed it appears that the rear part (looking from the camera position) went milliseconds(? ) later. Could this be because the gym area (in the front) collapsed first and transmitted the failure from front to rear?

[@jeffostroff]

Yes I thought the same thing as well and that does make sense because if those columns in the front part of the building facing the camera fell first then that part of the building is going to drop and that will propagate the collapse backwards so it makes perfect sense that the rear part of the building in the video is going to be the last part to drop even if it's just my very small delay.

[@PowderMill]

The fire alarm company owner stated that smoke detection was not heavily implemented The FACP monitored sprinkler system water flow detection devices, manual pull stations and some scattered smoke;p/fire detectors.

[@davewelch151]

I agree that the pool deck collapse likely started due to missing beams. But I believe the building was brought down by the excessive attachment of BMA beam to column m-10. The actual build of the BMA did not take into account of the floor step, and consequently the M-10 connection was 11 inches deeper than it should have been. This extra depth likely contained rebar.

[@jeffostroff]

That's an interesting angle for sure!

[@markknister6272]

“As designed” and “as built” and “actually done” are four different things. And additions later after letter of occupancy….

[@jeffostroff]

Don't forget as neglected

[@ianduhfixsinclair2739]

@@jeffostroff *OOOOOHH!* ... snap! BURN!... ouch, that's gonna leave a mark on the many lawsuits!

[@surf2257]

12:05 This one was obviously a water flow alarm and a pressure alarm. Means that you have at least 1 sprinkler head working. Once in front of the control panel you will see where. Control panel send a fire call to the alarm monitoring company and is supposed to trigger a sound and visual alarm in the whole building...

[@jeffostroff]

Yes all of us wonder why no sound

[@brnmcc01]

@@jeffostroff Communication and data wires severed when the first parts and planters fell and shorted something out is what I'm thinking.

[@michaelpease6248]

A water flow alarm sounds an exterior alarm bell or gong and notifies alarm monitoring. In a high rise it could also activate the fire alarm on the floor of and the floor above and below activation. Floors without the fire alarm are to remain in and wait for the fire dept to issue evacuation. This is done to not overwhelm evac routes or impede fire dept access.

[@surf2257]

@@michaelpease6248 Yes, and the gong only works because of the water flow. But no sound at all.

[@gregessex1851]

I look at those drawings and am so grateful that we use the Metric System in Australia. There must be errors made when dealing with measurements that involve things like fractions and difficult conversions.

[@jeffostroff]

They may seem difficult for you but it's just normal math over here for those of us using the imperial system. It's not likely they made any math errors it's likely they simply left out designing in the proper amount of rebar rods, or maybe using the wrong concrete those sort of things.

[@gregessex1851]

@@jeffostroff I understand that there may not have been any errors in this case but more broadly it has to be more common for mistakes using the old units. The risk is lower in an air conditioned office with qualified Engineers doing the design with all the checks and balances but it certainly gets higher as you transition to semi illiterate steel fixers on site in 45C heat working off dirty paper drawings.

[@mixedupmenopausaladhd3999]

@@gregessex1851 we draw conversions in black Sharpie on our arms. Works well till we sweat it off. But that would never happen at 45 deg… Seriously though, this is probably a calculable stat. Probably a well studied question.

[@gregessex1851]

@@mixedupmenopausaladhd3999 I should have said 45 degrees in proper units 😂

[@terrybuckley1556]

The multiple booming sounds make perfect sense. I have been in hurricanes and wind storms and heard tree roots snap underground. Very loud. Rebar snapping would be even louder.

[@jeffostroff]

Yes, and they also heard the building creak the day before which is eerie too

[@terrybuckley1556]

@@jeffostroff Do we know if the puddle the pool contractor saw in the parking garage was a recurring problem or was it new. If it he puddle was new it may be connected with the creak.

[@MatthewJamesCrouch]

I am curious what your assessments of the fourth sister condo to the Champlain trio - the Mirage at 8925 Collins Ave - will be. If it wasn't for your work analyzing these tragic events I feel like this entire event would have been successfully "memory holed" by now. Lastly has there been much information made available yet on the density and strength of concrete core samples analysis?

[@jeffostroff]

I heard they were going to check the Mirage also. I would be nervous

[@billj5645]

The managements of those other buildings should find a qualified engineering firm, someone with experience in designing those types of structures, and have the drawings for their building analyzed. No disrespect to staff at the University of Washington but it is possible that they aren't in the day to day business of designing reinforced concrete buildings.

[@WhittyPics]

I think you are right. That 3rd column is missing.

[@jeffostroff]

This could shift where the focus of the failure is

[@CelineNoyce]

I agree because of the Ring Camera and the fact that so many people were saved in the 11 block... something alerted them all.. suspicious that it started there.

[@jenjenjennyful]

Can anyone tell me where I can read more about the “sounds” that Sara Nir’s daughter heard earlier in the evening around 11:00pm? Or anyone’s description of sounds heard inside the building in the days and nights leading up to the collapse?

[@jeffostroff]

Best sourc eis this video interview they did on CNN a few days after the collapse kzbin.info/www/bejne/Z5jMlmOOi7R5opI

[@jasons8479]

It's possible the 3rd column was not visible in the video because the ceiling (underside of the pool deck) holding the overhead lighting to illuminate the column was now on the floor. Just a hunch.

[@jeffostroff]

Anything is possible, but remember we can see the 4th column behind it which is 20 feet behind that column so if we can see the 4th column, then we would of course be able to see the third column

[@braden1373]

Just a note, an alarm from a flow on the sprinkler pipes will trigger an alarm just the same as a pull station, this will automatically alert the monitoring company, who per policy will alert authorities. The only way flowing water in a sprinkler pipe won't trigger a general alarm is if you have a faulty device.

[@braden1373]

And a flow detector doesn't differentiate between a head busted through heat, or damage, or contact with a foreign object. Anything that breaks one open, triggers an alarm on the panel. So the damage seen in the tourists video was possibly an alarm trigger event.

[@geraldinekiefer2827]

With the missing column you researched adding to the process of destruction.

[@jeffostroff]

I always wondered if the building would still collapse if M11.1 had held its ground

[@KarynHill]

Forensic engineering-the process that creates new regulations and determines culpability out of tragedies. And now so much of it can be done by smart people with KZbin channels and smart people at media companies, helping the rest of us understand what happened. Priceless.

[@jeffostroff]

Yes, I hope it helps everyone learn so we can all be able to see when something is wrong

[@KarynHill]

@@jeffostroff It has made me more aware when I'm in a parking garage. And it has made me second guess my interest in buying a condo. I want to be the only one responsible for decisions about maintenance in my home.

[@omry77]

Very curious to know if the surviving tower with the 24x24 columns was the first to be constructed. It looks like they either ran out of materials or they didn't switch back to 24x24 columns after creating some narrower columns for the pool deck. Is there any info about the building order?

[@jeffostroff]

I doubt that any of that surviving tower wasn't afterthought in terms of engineering. A lot of people are unaware but the second level has a huge number of extra support beams likely because of the large shear wall that exists on this tower along the elevator and stairs. And so to support that huge shear wall going all the way up you need to have all of these extra beams on the second level, and those need to be supported by larger columns. I just wish they had used those larger columns in the other building because chances are it might have survived.

[@KB4QAA]

OY: The workmen did not change the size of the columns. Both the larger and smaller columns were specified in all the drawings.

[@MajorCaliber]

Cast-in-place (CIP) structures like CTS are "layered up" one entire floor at a time, and yes, all the column sizes were specified before a shovel ever hit the sand. Watching that collapse video though, it's easy to imagine that CTS was built as 4 separate towers, but that's just a result of its *WEAK-ass NON-redundant* design, and what Controlled Demolition Inc. called "very soft" concrete, aka "Mafia-mix" concrete. #BlameReiber

[@gamevids4181]

I thought the Miami Herald report was excellently done and pretty thorough with good explanations for the average reader. Despite the differences in theories I would be hard pushed to decide which one is likely to be most close to the actual facts - and of course many of your theories are shared by the Herald article too, so not so different. I do believe your version of the timeline is much more likely - and warnings were evident a day or two before the collapse. Arguably warnings were evident even before that! What both of you also have in common is that it has become very apparent indeed that the collapse was almost all probably due to initial design flaws, inspections lacking thoroughness, and general neglect and abuse of loading designs over the years. The Herald article didn't mention the penthouse either which undoubtedly caused a lot more stress on the already under-specced components. Or in other words: the eagerness by some to try and blame 87th Terrace for all the woes associated with CTS, seems a little bit "clutching at straws" to me, honestly.

[@jeffostroff]

Yes I'm still on the fence about whether the penthouse caused any issues because the architect had it in the plans already. The issue about the penthouse was that they were trying to scoop by and build that 13th floor in a city that doesn't allow 13 floors. So I don't think it's so much of an issue of was it too much weight on top of the building, I think it was already designed in they were planning that 13th floor all along. I think we will see from the NIST computer modeling and testing whether they think it will cause a problem or not' cause as you know the PSI rating of the concrete is higher at the lower part of the building by the garage and the higher up you go the less PSI rating you need.

[@chiefinspector7280]

Jeff, You can trace the path of the mystery column as it impales the slab with its rebar.Test were done in the past that rebar can easily penetrate concrete just as a shot pin will. There could have been 300,000 pounds driving the rebar it! I think it is clearly the only rational explanation.

[@jeffostroff]

Only problem is these rebar rods are straight up from the floor, and the k column was 5 feet over, so it would have penetrated at an angle

[@chiefinspector7280]

@@jeffostroff Right I think it flipped over as the bottom of the column looks like it is still on the H beam.

[@MajorCaliber]

Just to clarify, when you say a 12" x 16" or even 12" x 24" column is "no stronger" than a 12" x 12" column, that only applies to a *buckling failure* mode, IN the direction of the narrow 12" dimension. Under normal vertical compressive load--and in terms of *punching shear* failure mode--a 12" x 24" column is indeed TWICE as strong as a spindly 12" x 12" column. Of course a ROUND cross-sectional column is the most efficient strength:mass ratio, also most resistant to buckling in ALL directions, BUT... requires either expensive reusable forms, or expensive (cardboard) sacrificial single-use forms... #BlameReiber

[@jeffostroff]

Yes, my explanation was due to the fact that I believe we had that shearing forces of the falling pool deck pull to one direction. But you are also right that thicker columns are better when the building is standing under compression load, and no outside forces trying to yank the rug out from under it.

[@MajorCaliber]

@@jeffostroff True that. _pssst!_ Hey Jeff, got a deal for you on a unit in CTNorth... ocean view... won't last long! ;')

[@MajorCaliber]

_... won't last long!_ see what I did there?... yeah, I'll burn in Heck for that... esp. if "something happens" in the future... =:O

[@thunderrobots1980s]

i think that mystery rebar column may not have ever been a column or at least not one that was ever there , but rebar from an upper level column or just some plain rebar that got shoved into the ground by the force of the collapse

[@jeffostroff]

But it was in too straight

[@thunderrobots1980s]

@@jeffostroff in theory it could have slammed straight down

[@stackfire9601]

Jeff did you go to primary school in pahokee Florida? 1978-1981 ? I remember a school mate same name...

[@jeffostroff]

No I was down in Lauderhll, then lauderdale lakes

[@d.e303-anewlowcosthomebuil7]

powdery concrete...any testing of it?

[@ianduhfixsinclair2739]

RE: OVERloaded, UNDER-designed pool-deck: if you look at the pool-edge coping at CTNorth vs the many pics of CTSouth swimming pool, it's obvious that over the years CTS kept *layering new pavers OVER the old ones* (to "save" money), while CTNorth did it correctly, i.e. excavating the old schlock, down to the structural slab, THEN applied the new topping + pavers... that is to say, CTS coping is FLUSH with the BUILT-UP pavers, while at CTNorth the coping looks original, i.e. standing "proud" of the pavers by several inches... OMFG. #ZeroTownOversight

[@jeffostroff]

It looked from some of the photos we saw of CTS that there was only one layer of bricks. But there was at least 1" of sand

[@westbayoutdoors123]

Catch me up here... Has anyone gone in and measured the exact location of the mystery pier, either by direct measurement or by drone footage? Seems to me that pier being out of synch with the beam(s) is evidence that the building rotated upon failure. The alternative explanation is that a pier popped up out of nowhere. Or did I miss something? In any case, it should be straightforward to measure its location against the drawings, and not against the debris.

[@RJFPme]

There was a lot of corruption with the inspections process during construction. It took many many people in charge to overlook the grave mistakes/ negligence that occurred from the beginning.

[@jeffostroff]

From the cocaine cowboy era

[@billj5645]

There is too much speculation about corruption in the inspection process. Even today inspections at a construction site are not what people think they are. Now things like fire alarms and toilet stalls, city inspectors understand what those things are and what they should look like, but a mat of reinforcing steel with bars of different lengths at different levels going in multiple directions, that is a whole different matter. I can look at the original structural drawings and immediately spot areas where they left out required reinforcing but standing on the jobsite is a different thing and if someone is not intimately familiar with all aspects of reinforced concrete design they might miss a few things.

[@flamoby]

@@jeffostroff I was about to say the same thing. Miami in the 80s was built on cocaine

[@MajorCaliber]

There was at least 2--and possibly 4 or MORE--security video cameras overlooking the pool-deck. I can understand those recordings not being released to the PUBLIC at this point, but surely they could be made available to Dr. Lehman, w/ the usual NDAs in place. Obviously Kilsheimer and NIST need these also. (Hard to believe there weren't also some cams at the Solara/Blue-Green Hotel that captured key events that night. )

[@georgiazettakaragianni9832]

I believe they were four security cameras on the deck, and at least one, maybe two at the picnic/garden area which lead to the beach.

[@jeffostroff]

There were security cameras in the garage as well. I have stared at the Google Street views of the hotel next door and surprised that I can't find a single security camera anywhere there on the outside of the building unless they are super tiny and hidden which is amazing to me.

[@MajorCaliber]

@@jeffostroff I know, right? OTOH, there's some kind of lobby that opens out onto their hotel pool area, and I was thinking there might be an INDOOR cam aimed out towards the pool/88th St...? It's Mi-AAAAAM-ee... sometimes you just gotta slip a Jackson to the right concierge. ;')

[@thecollapseofchamplaintowe7199]

@@MajorCaliber and if only you could of been this In the group. And not be a make believe person. Because here you have some very interesting insight

[@thecollapseofchamplaintowe7199]

@@MajorCaliber that’s the problem MiMo. You provide such great information on this thread and then act a fool in the group. And what’s with the ghetto talk ? You are intelligent and articulate well. If you don’t like the platform then why are you on it and risking my group. ?

[@chiefinspector7280]

And lastly where are all the required structural wall sections required on the plan?? Without these the contractor was engineering the building as he went along.

[@lockbert99]

Wouldn’t it be illegal to have any changes from the approved “as designed” to the “as built”? Who’s to say that the changes were immaterial?