Miami Beach, Champlain Towers South apartment building collapse, Part 05 111

[SFCharlie]

A continuation of our discussion of this failure. Best to read the other threads first to avoid rehashing things already discussed.
Miami Beach, Champlain Towers South apartment building collapse
Miami Beach, Champlain Towers South apartment building collapse, Part 02
Miami Beach, Champlain Towers South apartment building collapse, Part 03
Miami Beach, Champlain Towers South apartment building collapse, Part 04


SF Charlie
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[Mark R]

If you have a residential unit not tied down you had a jack leg installer. The three I've had at my house were all fastened to the 4 x 4 ft concrete slab first put in for that purpose. Codes if you have any specify it. Guess I have to dowload a Rheem manual. Simply crazy to think you don't bolt it down.

There must be a lot of Jack leg installers around then because I've owned 4 homes in 3 states and none of them have had their outer units bolted down. Several of these homes had multiple units and there were at least 3 different brands of units involved.

 

[jbourne8]

Isn't is also possible the foundation is the problem, and that caused the column to collapse onto it's side from below? It'd make sense then why the inspector doesn't seem to see this problem before it developed. Also, that crane falling across the piles back in the 1980s could have done some minor damage to it, and it looks like it could have fallen around those columns that collapsed.

Couldn't it also just be caused by a sinkhole under the foundation? If the concrete was leaking water down to the garage from the pool deck too, it seems likely that the foundation was doing the same.. perhaps that caused some damage? It was above limestone. It seems very odd to me that this column collapsed onto it's side, but the column next to it puncture sheered and there's nothing that shows that the pool deck was pulling the collapsed column towards the southwest. It looks like the pool deck just fell straight down.

I found this map which seems to say that it's possible.

Some articles also say that Cassondra was in 410 and not 412 -

https://www.usatoday.com/in-depth/g...aused-building-to-fall-near-miami/7795023002/

(Cached version that doesn't require an account:

https://webcache.googleusercontent....-miami/7795023002/+&cd=3&hl=en&ct=clnk&gl=us)

 

[Demented]

A sinkhole opening up in a formal tidal pool? Nah, no way.

Precision guess work based on information provided by those of questionable knowledge
Aerospace/Industrial/Medical/Structural
SoFla

 

[AutisticBez]

So, the pool deck. If the pool deck collapsing is the initiating event, then every single column supporting the pool deck, has to be a clean punching shear. Right? We have the TikTok video, which people claim there is a column that looks tipped over right? Gone, vanished. Where is this column? Would I be correct in assuming that the punching shear is easier to occur then a disappearing column? I mean, those columns look real tough. Like, say what you will about the connecting rebar on the pool deck to the columns, but those columns survived an entire pool deck slamming down on them from above.

So, the pool deck gets super old, it's had it, it collapses to the ground. Somehow causes the entire building to collapse. Right, sure, so then we should find every column still in it's rightful place punching through the pool deck.

There is the opinion that the roof collapsed over the side and slammed into the pool deck. Sure, that's possible, I don't think you can argue either for or against this. Needs more evidence. But, how does the roof crashing into the pool deck, somehow magically destroy a column? It just magically slammed into the exact position on the ground where the column was and Thor's hammered the crap out of it from above?

This isn't obvious, neither of these two could possibly be the initiating event, because we still have a missing column, where is that column? Also, the pool deck above the missing column looks intact right? So, it didn't punch through and then disappear right? It wasn't obliterated by the building falling on top of it. So, what happened to it?

Well, I think this matches with a side collision from a vehicle. You have a vehicle slam into that thing at full speed, and you've got enough of an impact to knock that thing out from under the pool deck. The connection to the pool deck is not much. So, if I am right, then your going to have a dead motorist crushed under the pool deck, inside their vehicle, next to a collapsed column.

But, how exactly does this happen? Well, you think about it, car is coming down a ramp, maybe the driver is tired, being it's late at night, and a foot taps the wrong pedal, and before you know it, it's right through the column. Why is this a difficult concept? It happened to me, old lady next door, she had a V6 she used to park in the backyard under a shady tree. Her meds are making her tired, and she gets in her car, winds the window down, and before she knows it, she's made the car fly 10 meters at speed through a fence and into the next door neighbours garage.

In 10 meters this woman dropping the foot to the floor on grass in her backyard, had managed to cause structural damage to a double bricked garage.

That guys story of "power is out", "left my car down in the garage", "left on my scooter". Something about this seems a bit BS to me. Like, you imagine if the person who did slam into the column, had managed to get out of the area before the collapse, you think they'd want to be honest about the situation, like, yeah, I just killed 150 people by driving drunk / tired into a column.

And, honestly, I've known plenty of people to slam into building columns. My uncle did it in an old BMW once. Wrecked the rear of his car big time. The column stayed in place, due to it supporting a 5 story building. In Australia, our columns are super thick, and honestly, I think these columns were probably very thick as well. Just, I don't think they were rebarred well at the top and maybe at the bottom.

The columns might be super strong, so you'll probably find them intact. I think of all the issues this building had, those columns were not one of them. And you tend to over engineer columns if they are going to be supporting the weight of a building. The columns under the pool deck, looked to be a very similar strength to those under the building. With one exception. The columns under the surviving structure were stronger.

You think maybe when they did the columns under the pool deck, they were thinking of the future? Like, in the future you might want to expand the building above the pool deck? It wouldn't surprise me. Like that pool deck is taking up valuable real estate.

On another note, people say the building is in bad shape, but it doesn't actually look that bad, like you can clearly see a bit of money going into fixing the cosmetic appearance of the building. The boards priorities with repairs seems to be entirely based on increasing condo value. If I owned a condo in an old building and was on the board, I'd probably be doing the same thing, getting the hell out of there.

 

[dold]

You reference a narrative about this roof collapse being built by warrenslo and dold… but I don’t recall seeing anything being said by dold to that effect. In fact, they had this to say:

Thanks for backing me up on that. I've always been an advocate of the pool deck collapse mechanism (ref threads 1 and 2), and have found the roof anchor discussion quite tedious.

Id like to comment on the redundancy of modern PT construction. Current codes require a minimum number of tendons (cables/strands/etc) to pass through the core of the column in each direction. This provides redundancy in the event of a punching shear failure as we see in this collapse. The intent being to prevent the failed slab from dropping its full weight onto the slab below - with obvious consequences.

However, even if Champlain towers south had such a system, it isn't really clear if that would preclude a collapse of this nature. To me (and as presented in the youtube video+translation) it seems that the collapse initiated at the pool deck slab somewhere, and caused some sort of perturbation in the columns supporting the south side of the north wing (can't remember the gridline at the moment) ultimately leading to the column buckling. Most likely, in my opinion, caused by loss of support at pool deck level via pool deck collapse.

I feel like at that point, no amount of redundancy can stop the momentum of 12 stories of concrete frame once it starts moving.

The columns and particularly the slab to column joints are just going to get rubble-ized. Consider the photos that show apparent voids at the floor levels along the height of the column stacks. I have no calculations to back it up, but the slab mix was 3-4 ksi and the lower column mixes were 6-7 ksi if I remember correctly. Really just food for thought, but under impact loading, I would expect more of a crushing failure as opposed to an instability/buckling failure. Which appears to be reflected in many photos. A secondary effect of this (also mentioned in the translated YouTube video) is the rotation of the entire collapsing structure about the vertical axis - read: P-Delta).


And about this RTU anchoring business. Current Florida building code amends and SPECIFICALLY addresses the design wind loads on roof top equipment. I think its factor about a 2.5 in Florida vs a factor of 1.9 for the vanilla IBC (uplift coefficient). You're looking at pressures well in excess of 100-150psf for RTUs in that exposure and height AGL. Nobody would consider shielding from a 3.5ft tall parapet thats 10ft away (...probably). I guess none of that matters if it was installed by some unpermitted jack leg.

Even if it was just loose, i have a really hard time imagining a 250lb residential unit just...falling over...then causing a global collapse of a building.

 

[Js5180]

AutisticBez,

One problem with this theory, is that if a car hit missing column, and completely displaced it, the car should probably still be there. And it’s not. It’s the billiard ball or swinging cradle thing.

I think it’s pretty clear that a pool deck collapse weakened the rest of the structure, especially around units x10/x11.

The question is more about what caused an already weak pool deck to collapse. Did it collapse on its own, or was it hit?

 

[jbourne8]

AutisticBez , I think the column is right here, but it's easier to see in the original tiktok video since it's the only object that looks white and this photo has been lightened. I'm less sure about that horizontal column than I was when I made this graphic though.. this was posted in part 4 of this thread too.

If that is a column, the bottom seems to line up well with where a column should be, but it's too covered in rubble to see it. I think if a car had hit it we would see a car here, underneath it or the rubble. But it would have had to hit it with such force.. I don't think a car would be capable of it. And yea, a few stories from the building sound odd.. but that's also how the truth sounds sometimes and they all seem plausible. That guy with the scooter also wasn't the last person in the garage btw, two actors from Argentine were and they had just gotten into the elevator when it went down. They then left the country in a hurry.. but that's also just how rich people act.

 

[Vance Wiley]

Thank you for the building data, Charlie.

 

[Mark R]

Well, I think this matches with a side collision from a vehicle. You have a vehicle slam into that thing at full speed, and you've got enough of an impact to knock that thing out from under the pool deck. The connection to the pool deck is not much. So, if I am right, then your going to have a dead motorist crushed under the pool deck, inside their vehicle, next to a collapsed column.

But, how exactly does this happen? Well, you think about it, car is coming down a ramp, maybe the driver is tired, being it's late at night, and a foot taps the wrong pedal, and before you know it, it's right through the column. Why is this a difficult concept? It happened to me, old lady next door, she had a V6 she used to park in the backyard under a shady tree. Her meds are making her tired, and she gets in her car, winds the window down, and before she knows it, she's made the car fly 10 meters at speed through a fence and into the next door neighbors garage.

If the columns were even close to their design strength in automobile running into them would not knock them down or even severely damage them. Going through a fence and our neighbors garage like you described is completely different, those are much less solid structures.

 

[Js5180]

JBourne,

Column M11 should be about where the word “both” in your graphic appears.

 

[bones206]

I pointed to the wrong beam in my last post. I went back and checked the video again and it was actually the next column line to the east, which was closer to the core drill. Also saw what looked to be a planter drain.

Note the Column at M11.1 is quite smaller in cross section, possibly 12" x 16" - much more susceptible to a vehicular impact. But if that's what happened, the only way we will ever find out is through surveillance video or a confession.

The thing that's nagging in my mind is the column on the left (M10) is supporting the building and the column on the right (M11.1) is only supporting plaza slab. But since they are connection by a beam, if the column on the right (M11.1) collapsed for some reason, the falling slab would cause the beam to rotate clockwise and put a huge bending moment on the left column (M10). That's a plausible trigger for the subsequent building collapse.

 

[SFCharlie]

How many units were there? It looks like the last ones sold went for about $700K. What was the square foot each floor?

Here is some recent info, please see attached file:
It shows:
[tab]the average price for units w/# of bedrooms over the past 24 months
[tab]the average price for units w/# of bedrooms times the # of units that size
and
[tab]the Total of the average price times # units for all units

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[jbourne8]

Js5180, I agree with you? Although, it wouldn't be quite at that word and closer to the 'th' in 'both.' If we're looking at the top of that column in that pic, it's easy to see where the bottom would be if it weren't covered in rubble. It looks like it's still all in one piece.

bones206, Interesting, I hadn't noticed that pipe but it does seem like that could be right under the planters in front of 111.

 

[AutisticBez]

Okay, the columns are strong true? But what if whatever is connecting them isn't? What if it's possible to dislodge a column simply because the connection with the pool deck and the foundation, isn't strong?

The water coming in, would rust and destroy rebar, but it probably wouldn't damage the columns so much as the connection points? Those connection points are super weak. Concrete sheared off the columns easily. But the columns are still there?

If the basement had a lot of flooding, perhaps the rebar in the foundation connection to the columns is even worse? The water has to go somewhere right? So, a vehicle knocking down a column is impossible? Not even flying down a ramp at full speed? Can we myth bust this? Anyone got an old car and an abandoned parking garage to prove this?

 

[Demented]

AutisticBez

What production model car is going to gather enough energy to dislodge that column with at most, 85ft of run-up space on slick concrete from a dead stop? The garage entrance gate was closed too, and those things don't just slam shut. No car took out that column, unless both theories are correct, and a car fell off the penthouse roof onto the pool deck.

 

[AutisticBez]

Anyone else notice that M11.1 is super thin right at the top? There is a beam between M10 and M11.1, but the beam is sitting on a real skinny bit of M11.1 column right?

 

[Demented]

Per the drainage plans, that would indeed be where a 2" planter box drain is called out.

Precision guess work based on information provided by those of questionable knowledge
Aerospace/Industrial/Medical/Structural
SoFla

 

[AutisticBez]

I think a car can do a lot of damage in a short space of distance. Most people don't flat pedal cars. I think in my entire life I've never put the pedal all the way down. Most people don't. An old grandma in a super overpowered 6 cylinder 4 litre plus car, she's probably never flat footed that vehicle. But you know, if you've got a variable cam timing engine, and you flat foot that shit, and it's like warp speed. By the time you realise what you did, you've magically displaced a lot of distance in a short period of time. Most of us regular car drivers, the rpm's sit between 1000 and 2000 most the time. Transmissions tend to keep it low to conserve petrol. But, giving it a 3 or a 4 on the onramp to the freeway. Flat footing that pedal is an entire other story. Come on, even my shitty sedan could wreck a building column. It's nowhere to be seen, you find me a single photo with an intact M11.1

 

[bones206]

That’s just a trick of the light. The column isn’t skinnier at the top.

Column M11.1 failure doesn’t have to be the initiating event. That beam could have simply failed at mid span and it would have had the same effect of applying a bending moment on column M10.

 

[spinspecdrt]

Myth busted. Tree still standing after highway speed impact with mini van.