Miami Beach, Champlain Towers South apartment building collapse, Part 15 32

[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
Miami Beach, Champlain Towers South apartment building collapse, Part 05
Miami Beach, Champlain Towers South apartment building collapse, Part 06
Miami Beach, Champlain Towers South apartment building collapse, Part 07
Miami Beach, Champlain Towers South apartment building collapse, Part 08
Miami Beach, Champlain Towers South apartment building collapse, Part 09
Miami Beach, Champlain Towers South apartment building collapse, Part 10
Miami Beach, Champlain Towers South apartment building collapse, Part 11
Miami Beach, Champlain Towers South apartment building collapse, Part 12
Miami Beach, Champlain Towers South apartment building collapse, Part 13
Miami Beach, Champlain Towers South apartment building collapse, Part 14

SF Charlie
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[Demented]

Demented, what is an Industrial Engineer? I honestly, don't know. It seems like a fancy title for someone that has a really vague job description, with absolutely no responsibility. IN terms of construction, waste water treatment is chemical, motors are electrical, air is mechanical, and structural is kind of self explanatory, so what do you actually have real word practical experience in?

One who integrates processes, equipment, streamlines processes, so on and so forth. So yes, it's a fancy title for a clipboard warrior/consultant. However that's not what I am and don't know why it displays as that for me when under my profile it states Manufacturing - Metal Fabrication/Welding, Fabricated Metals, Technician.

I never finished my Mechanical or MSE degree. I learned I'd rather build and play with the things I could engineer, rather than engineer them and learn to hate them.
What I have experience in? Mostly trolling while inebriated, Fabricated steel structures, Aerospace machining/welding/design, Bridges, and taking offense to being called dangerous. I do my very best in the field to check the work of guys like you so I can raise any red flag I can to prevent an issue. But eh, you can just call me a dumb welder. Nearly 23 years now of avoiding the stupid accidents/failures on sites that plague South Florida because straight C PE's think they're hot shit. Not a damn thing wrong with admitting fault or admitting you're wrong. We're all humans.

Take your damn blinders off man.

 

[Nukeman948]

...there is an entire floor below that 2'2" elevation, you talk about being an idiot, you define it. Bottom of E-4 is 125' 8" to the top, learn how to add, it is a easy as 1+1=2

Holy cow! You got something right! One whole thing right all by yourself! E-4 does go up to 125' 8"! Congratulations dude! Maybe we all owe you an apology! ... or something.

But wait! There's more!

Not only does E-4 go to 125' 8" like you said, but so does E-2, H-2, and H-4! And those four columns just happen to be where that big old air handling unit was located, 1' 6" above the roof! What a coincidunce!

Well it seems you taught this old retired electrician how to add and subtract and to read these old drawings perty good. Why don't you grab a shovel and measuring tool and show us that secret hidden floor below the parking level.

And through all of this, only one guy thought it was appropriate to call others names like dangerous or idiot and denigrate their job description. Up your game or go home.
I'm a little slow before my morning coffee, please, define "idiot" one more time for me.

[sub]This space intentionally left blank. [/sub]​

 

[FJBnomics]

I am from the land of clay soils and a monolithic concrete slab poured with reinforced thicker edges is common place here to support residential wall loads. I agree a 'Grade Beam' would have been a better solution to transfer the wall loads to the piles, but Champlain Towers was not designed by the Straight A over achiever PE, Architect and Developer Team.

IMO, the torsion load seems like it would be excessive where the wall keys into the thicken/reinforced monolithic slab on grade, from the patio deck loads. Along Building Integrity's Theory the thermal cycling would transfer stress to the edge joint of the slab and retaining / pool deck structural wall.

A good case for the retaining / pool deck structural wall should have been centered on a grade beam IMO, to transfer loads to piles. Then the Garage Floor Slab at grade should have been poured on top of that.

But then what do I know, I am too busy trying to outrun inflation currently...... Current Administration

[highlight #FCE94F]Edit2.0[/highlight]: Perhaps someone could help with the difficult Math. The image below, is a Note on the S1 Structural Drawing. It states the Elevation of the Top of Pile Caps is EL. + 1'5", thus implying the top of the pile caps is [highlight #FCE94F]1'5" above the Reference Elevation.[/highlight] The Section View says top of garage slab is EL. + 2'2". Therefore if I performed the Laplace Transformation Correctly, then the top of the finished garage slab on grade is 9" above the top of the pile caps. Thus if the Edge of the Monolithic Slab Pour is 12", then the turn down portion of the monolithic slab is 3" deeper or lower in elevation than the top of the pile caps under the monolithic thickened slab edge.

 

[FJBnomics]

don't know why it displays as that for me when under my profile it states Manufacturing - Metal Fabrication/Welding, Fabricated Metals, Technician

When you join Eng-Tips you answer the questions shown on the screen shot below. The User Type Field is the field input that gets pasted by your Display Name, rather than your job, industry or job role.

 

[IEGeezer]

@MaudSTL (Computer) 19 Jan 22 03:32:

Thanks for your kind words. I did a quick and dirty time and motion study of Mrs. Monteagudo's movements:

As you can see, there isn't much time for Mrs. Monteagudo do anything else. I think that the seven minutes between the pool deck collapse and the building collapse is not exact. I think that that there is some uncertainty and that time may be between 5.5 to 7 minutes, with 7 being a maximum. The time may actually be closer to between 6 and 6.5 minutes. I think the crack was close to the outside wall and may have been caused by column L9.1, as can be seen in the picture below of the second bedroom. The wall to the left of the column is the wall between the living room where Mrs. Monteagudo was standing and the second bedroom. As can be seen from the time and motion study, the crack reached her at about halfway between the pool deck collapse and the building collapse. Her apartment (611) is also about halfway from the top to the bottom. If the pool deck collapse caused the base of column L9.1 to no longer be supported, then the crack may have started at the top as the column separated from the floor slabs. The step beam at the lobby level also had a smaller section at column L9.1: it only had a vertical section of 16.5 inches between gridlines K and M. West of K and east of M, the step beam had a vertical section of 27.5 inches, so it stands to reason that of the three KLM9.1 columns, it was the weakest at the step beam.

 

[Keith_1]

[highlight #F57900]I am from the land of clay soils and a monolithic concrete slab poured with reinforced thicker edges is common place here to support residential wall loads. I agree a 'Grade Beam' would have been a better solution to transfer the wall loads to the piles, but Champlain Towers was not designed by the Straight A over achiever PE, Architect and Developer Team.[/highlight]

I really do not understand why you would undertake the extra work for a ground slab, either the soil supports the load or it does'nt. If it is a span over a basement, then you would you just pour a few footings and place a grade beam across them,

I think your question is more about span lengths. In general, the max values of unsupported spans are (1) wood truss 14' (2) voided slab = 20' and post tension 30'.

It is not hard it is about distributing a load evenly onto a foundation.


I did a two thousand yard floating matt foundation one time, I started around 10:00pm and had 3 pumps with 2 trucks each until 6:00am, I got stressed because when the sun was about to rise and still had concrete on the way. This is not a thing you can key and do a cold joint.

 

[AusTony2046]

IEGeezer,

If the pool deck collapse caused the base of column L9.1 to no longer be supported, then the crack may have started at the top as the column separated from the floor slabs.

If the column failed at the bottom, would you not expect the first signs of detachment to appear at the bottom first? I would expect that as the column tore itself away from the floor slabs, they would fail progressively upwards.

cheers
tony

 

[MaudSTL]

I think that the seven minutes between the pool deck collapse and the building collapse is not exact. I think that that there is some uncertainty and that time may be between 5.5 to 7 minutes, with 7 being a maximum. The time may actually be closer to between 6 and 6.5 minutes.

There’s no doubt that the Timeline estimates the time of key events, as the only true time stamps we have that are accurate to the second are the 911 calls. We do have several times that are credible, but not accurate to the second:
[ul]
[li]1:10 AM The Nirs heard what they called the first collapse. Sara Nir was WhatsApping and has a time stamp that she repeated in multiple early interviews.[/li]
[li]1:14 AM Sara Nir went to the lobby to complain about the banging and so-called first collapse. She was still WhatsApping and it gave her a time stamp. Sara repeated that time in multiple early interviews.[/li]
[li]1:18 AM The reported time stamp of the Adriana Sarmiento’s video of the garage.[/li]
[/ul]

You can calculate a fairly accurate time the building collapsed from Gabe Nir’s 911 call of 1:21:57 AM…and that’s assuming that the recording we have of that has not been edited. I calculated it once, but can’t recall what I came up with…if memory serves me it was something like 1:22:20-something.

We have no way to calculate an accurate time for any of the other main events. That’s why the Timeline uses ~, <, and > to indicate approximately, earlier than, and later than, just so we can derive a plausible sequence without claiming that we actually know exactly what time an event occurred.

 

[SFCharlie]

you can just call me a dumb welder.

Demented, there is no such thing as a dumb welder, anymore than there are any "old, bold pilots"!

SF Charlie
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[Keith_1]

Here is the timeline, 10 years ago there was a problem that everyone new about but were told it would be 10 million to fix it, which the Board thought would result in a few hundred dollars in increased fees, and that little sum posed a threat to their little fiefdom, so instead of loosing the only power that they have ever known in their entire lives, decided it was better pay a property management company $200,000 per year to tell everyone "it is all good we got an expert", because we paid a few hundred dollars and go PE stamp.

In my opinion, that PR, or any licensed person need to be criminally liable when something like this happens. You put your signature and a stamp and knowingly lie, your ass should go to the worst prison for the rest of your life.

It really pisses me off that so many "professionals" looked at this structure and knew that it was a structurally, and did nothing, simply because they made money to do so.

The pictures of those beams pre-failure, drive me f* crazy, that building official should be in the worst prison cell, and share a cell with a huge dude named tiny (play Berry white for effect)

There is a point where professionals need to be held accountable, I hate that the "stamp" actually provides no protection to people.

I'am not a troll, I just think you are misguided in where you are trying to assign blame, it is not with the architect, strutcrual or GC, it is the "professionals" after words that are at fault.

All they had to do was remove some pavers and reapply the membrane every 12 years, it is just like painting -- it prevents most problems, and is ultimately the cheapest thing you can do. It is not fancy like, new wallpaper, pool furniture which boards have no problem spending homeowners money on, but basic maintence is way out of the budget.

The "stamp" should be something that the general public can rely upon, and unfortunately they can't.

This thread should be a discussion amongst professionals, as to how we should self regulate and formulate a clear set of codes and regulations that punishes people that allow something this to happen.

 

[Demented]

Keith,

Which report from 10 years ago are you referring to? I'm assuming that'd be 2011? The Morabito report was 2018, so only 3 years prior to the collapse.

Also the membrane was repaired/replaced, twice. Once in the 1990's, once in the mid 2000's. As far as how well of a job the crews did, that was discussed previously and the quality of work was questionable at best, but still given the stamp of approval by the same firm both times.

Precision guess work based on information provided by those of questionable knowledge

 

[SwinnyGG]

It really pisses me off that so many "professionals" looked at this structure and knew that it was a structurally, and did nothing, simply because they made money to do so.

...

I'am not a troll, I just think you are misguided in where you are trying to assign blame, it is not with the architect, strutcrual or GC, it is the "professionals" after words that are at fault.

I'm having a hard time understanding why you're so insistent that:

1) Both the design and construction of this building were perfectly executed

2) The professional engineers who evaluated the building over the last decade somehow bear blame for the collapse

To the first point - I think it's relatively clear from first principles (and from the published opinions of consultants after construction, ie Morabito) that the entire design approach of the pool deck - horizontal suspended slab with horizontal waterproofing topped with topping slab/pavers/planters/etc while not making any provision whatsoever for drainage - was a huge design error. That's on the original architect and structural EOR, and is not the fault of consultants who evaluated the building later.

To the second point, the Morabito report released in 2018 is relatively clear, in my opinion, that rapid deterioration of the pool deck due to failed waterproofing (due primarily to an original design which was not sloped and included no drainage provisions of any kind, and secondarily to less-than-stellar maintenance after substantial completion of the building) was in progress, and needed to be addressed promptly if the progressive degradation of the slab was to be corrected. That report was also relatively clear that the previous attempts to repair structural concrete elements in the parking garage had failed, and that major repair to many garage columns, beams, and areas of the first floor deck were also urgently needed.

I don't think it's reasonable to expect that a consulting engineer who performs a building evaluation and provides his report promptly is also expected to be responsible for the execution of the recommendations in that report.

Bad design, half-ass maintenance, and terrible decision making by property management are the main factors in this disaster. It's possible that badly executed construction is a factor as well, although that is harder to know; when a final report is released we may know more on that front.

 

[Jeff Ostroff]

IEGeezer Great analysis on her steps and timeline inside her unit after awakening to the noises. But you left out 10 minutes to do the hair! LOL

AusTony2046,you asked:
"'If the column failed at the bottom, would you not expect the first signs of detachment to appear at the bottom first? I would expect that as the column tore itself away from the floor slabs, they would fail progressively upwards."

Construction materials do very strange things under stress. And the first column that I think failed was M11.1 outside the Nirs’ unit 111 patio, under the planter, and as shown in the tourist video, M11.1 was the missing column in the garage. Once that M11.1 fails you have the most added load stress on the columns L10 and M10, or as some people refer to them L 9.1 and M 9.1 above.

So at this point, the building isn't really collapsing but it is stressing and moving, likely shifting a little bit to the side, maybe sagging an inch or two, and so the crack Ileana Monteagudo saw on her Unit 611 living room wall was the result of this movement manifested in the drywall which is very weak, to begin with. The drywall is not strong, but the paper and under stress will crack easily.

So Ileana Monteagudo’s living room drywall likely just snapped a little bit and tore due to the movement of the building even though the building had not crashed yet. Maybe the building started to drop an inch and most unit drywalls are intact, but 611 is where the stress manifested itself. Look at the Ring video from 711, there were no cracks on the wall until it was collapsing as the camera cut out. Yet Ileana Monteagudo saw cracks 7 minutes prior, one floor down in 611.

One thing we can all agree on is most of the noise cracks and damage that people heard and survived happened in the "11 stack" of condo units.

I still believe that the first three columns to go were K, L, and M right under the 11 stack. Of units. So this aligns with everything that we have so far on this.
And remember AusTony2046, that we don't know that there weren't other cracks in other units not reported. There may very well have been cracks in Sarah Nirs unit we just don't know maybe the kids didn't see it maybe they heard the noise and just got out or didn't notice it. But we can't discount the fact that there must have been cracks in a few other units as well.

 

[IEGeezer]

I did not mean to question your timeline. I was focused on the "Seven Minutes" that the Miami Herald has published as the time between the pool deck collapse and the building collapse. I read but did not comprehend your previous comments about the 1:10 AM vs the 1:14 AM timing. Thanks to your comment, it is now clear to me that the time between the pool deck collapse and the building collapse may be as much as 12 minutes (i.e. from 1:10 AM to 1:22 AM). I was trying to come up with an estimate on when the crack formed in Apt. 611, based on Mrs. Monteagudo's testimony. However, I have a hard time expanding my time and motion study of her movements to 12 minutes. If you look at the video of the visit to Unit 611 on 17 July 2020, they walk the long hallway from the elevator hallway to Apt. 611 from 0:42 to 1:05, a time of about 23 seconds. I measured that hallway at about 83 feet in length, which at 2.2 ft/sec would take about 38 seconds (the elevator hallway is another 52 feet in length for a total of about 135 feet). That is the only independent measurement I could find of my time estimates.

I don't question the timestamps. However, there are 3 different computer clocks: Whatsapp, Tik-tok and the 911 computer. Nevertheless, I wouldn't think that they would have differed by more than a minute or so - not 4 minutes.

 

[IEGeezer]

AusTony2046 (Electrical)[/b] 26 Jan 22 01:51 If the column failed at the bottom, would you not expect the first signs of detachment to appear at the bottom first? I would expect that as the column tore itself away from the floor slabs, they would fail progressively upwards.]

I can't disagree with you. Nevertheless, Mrs. Monteagudo's testimony is very credible that the crack formed from the ceiling to the floor and not the other way around. I was just trying to find some structural explanation of the witness testimony. It is devilishly difficult to try to reconcile the witness testimony to what was likely to have happened structurally.

 

[MaudSTL]

I don't question the timestamps. However, there are 3 different computer clocks: Whatsapp, Tik-tok and the 911 computer. Nevertheless, I wouldn't think that they would have differed by more than a minute or so - not 4 minutes.

No worries. I didn’t think you were questioning time stamps. I just wanted to clarify what standards I used in assembling the Timeline from reported accounts. There are very few time stamps, but the good news is that they are in nearly perfect sync with UTC and with each other.

Computer systems use Network Time Protocol (NTP) to sync their clocks with UTC. So any variation among the WhatsApp, TikTok, and 911 systems would be in milliseconds (as a result of packet latency) rather than seconds or minutes.

>>>>>Edit:

…it is now clear to me that the time between the pool deck collapse and the building collapse may be as much as 12 minutes (i.e. from 1:10 AM to 1:22 AM).

Please have a look at the Detailed Data tab in the Timeline to avoid going down a rabbit hole. Based on witness statements, the crashing sound that the Nirs heard in 111 and Shamoka Furman heard in the lobby at 1:10 AM (which they called the first collapse) was not the same as the pool deck collapse at ~1:15 AM (which they called the second collapse).

Also…were you thinking about doing a time and motion study of Sara Nir’s movement from 111 to the lobby at 1:14 AM? There are links in the Detailed Data tab that can help you with what Sara stated she did. It might help estimate the time of the pool collapse better than ~1:15 AM. The Miami Herald House of Cards infographic shows their version of where Sara was WhatsApping in 111 before she left to go to the lobby.

 

[MaudSTL]

Tonight’s Town of Surfside meeting will decide how much money the Town is willing to spend on their investigation. They seem to be moving away from “we want our own study ASAP” to “nah, we’re willing to wait for NIST.” From the Miami Herald, “Surfside shouldn’t cut ‘blank check’ for court-ordered collapse inspection, mayor says”

https://www.miamiherald.com/news/local/community/miami-dade/article257691963.html

 

[Jeff Ostroff]

IEGeezer Yeah that drywall in Ileana Monteagudo’s living room failing from the ceiling down to the floor I think makes perfect sense in this scenario, because the southern edge of her living room where the sliders are or the windows is the location toward where many people theorized that the three columns that dropped initially in the collapse from the security video from 87 Park next door. That security video shows that the southern edge of the condo likely fell first.

if this is indeed the case in the southern end of the living room falls first, it likely was collapsing only an inch or two by the time Ileana Monteagudo saw the crack in her living room, and so the crack would start at the ceiling and work its way down to the floor, because the southern end of her condo is falling first.

 

[IEGeezer]

@Jeff Ostroff (Electrical) 26 Jan 22 18:08

There is a difference between when the pool deck collapse happened and when the building collapsed. There is a consensus that the building collapsed about 1:22 AM, based on a 911 call. The difference arises based on whether the pool deck collapsed at 1:10 AM or 1:15 AM.

According to


According to the Miami Herald

The wonderful timeline that MaudSTL has put together is in agreement that the Nico Vazquez and Gimena Accardi drove through the garage before 1:15 AM.

If the collapse happened at about 1:15 AM, then Mrs. Monteagudo would not have had time to do her hair. If you have any suggestions how the time and motion study could be improved, I would be most appreciative.

EDIT: I am assuming that the pool deck collapsed at 1:15 AM or so and that the pool deck collapse and NOT the first collapse is what woke Mrs. Monteagudo up. The time and motion study is necessarily speculative, because it cannot be determined when Mrs. Monteagudo woke up. The rest of it is estimated, but not speculative.

 

[IEGeezer]

There isn't enough detail in her testimony, but the distances to the lobby are the same. It would have taken her about 30 seconds to go to the lobby from Apt. 111. And about 30 seconds back to Apt. 111 from the lobby.