Miami Beach, Champlain Towers South apartment building collapse, Part 04 49

[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

SF Charlie
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[Js5180]

Murph,

For the moment, Building Integrity’s roof collapse video has one serious flaw.

He states that the lights stay on in several of the units as they are falling because the electrical conduit is run vertically from the base of the building.

In fact, it runs horizontally from the 2, 3, 5, 7, 9, and 11 floors.

That doesn’t necessarily disprove the rest of his analysis, but a unit falling 15 feet with a horizontal electrical feed is not consistent with the lights staying on.

 

[Murph 9000]

Fortunately it’s a video with numerous parking bay markers. I may be incorrect in the direction it’s facing, but it’s absolutely west of the shear wall.

https://youtu.be/MmleL6I2T5M

I believe the very first few frames of the video positively identify the location beyond any doubt. In the first frame of the video, there is a double column on the left of the frame towards the back. I believe this can only be columns A.1 and B.1 in row 2.1. That puts the drilling firefighters between columns D2 and D5, drilling east into roughly the E line. I can't see any other combination of columns in the NW quadrant of the basement that fits the framing plan so perfectly. That puts them west of the shear wall line, but in the north half of the structure, north of the shear wall and corridor. Without checking, I think it's roughly under the service entrance / loading dock.

 

[DavPc]

Fortunately it’s a video with numerous parking bay markers. I may be incorrect in the direction it’s facing, but it’s absolutely west of the shear wall.

https://youtu.be/MmleL6I2T5M

At 0:09 I see 117 and 118 on the column for the parking slot markers. That would put this shot at the northernmost row of parking spaces (if the plans are correct) and the camera ends the shot looking east at the attempted rescue. So yes, if it hasn't moved the security office should have still been there. However, this shot from 2020:

shows there has been some reconfiguration. For example the nearest door is now much farther from the elevators so it's not clear if that new door in the pic above still went to a security office or if it was now in an entirely different location.

 

[jbourne8]

Murph 9000, Personally I stopped watching building integrity's videos when he suggested rolls of roofing paper may have caused the collapse heh. He seems to just be reading this thread and regurgitating it, instead of posting his own ideas.. he made that video right after it was discussed in here a lot. And he misses a lot really. The roofing paper was mostly just suggested in here because of the green in the tiktok video, but I think those are just planters on their sides too. But yea.. I do agree the roof is partially collapsed when the surveillance video starts, but that part I'm pretty sure he took directly from screenshots in an earlier thread here too.

If the roof was that collapsed I think the tiktok user would have caught it.. and if a substantial bit of roof was on the ground or was tumbling down the balcony area I don't think Cassondra in 412 would have stopped to call her husband. She also probably would have mentioned that instead of saying that just the pool deck collapsed.. she thought it was a sinkhole if I'm remembering right. I did consider the roof anchors for a bit, but it just doesn't seem to fit. I think the upper levels just collapsed a few seconds before the surveillance video starts, because column 27 has then collapsed and it's putting too much pressure on the rest of the building. The ring video probably starts around 10-11 seconds before the surveillance video starts, based on when they lost power and the tilt of that area. I figure the roof was collapsing during the start of the ring video.. perhaps that's what woke it up. By the time the ring video starts the tiktok users phone is probably no longer recording and they were walking back to their pool area.

And I'm pretty sure that column they're looking at in the basement is 118 btw, they're facing the collapse and trying to rescue someone from the bottom floor. I think they said she was a 14 year old they never reached. It's probably taken from spot 112. Pretty sure this was already discussed earlier in this thread too btw.

I've been watching the live feeds a good deal and I've been a bit surprised how little they've been investigating where things have fallen on the bottom of the rubble pile.. I sort of doubt they spent a lot of time getting the CCTV stuff out. It's probably very difficult to find someone willing to risk their life for CCTV footage, and it might not be straight forward to find.. a lot of time it's stored in a closet.

Perhaps this doesn't apply, but with tech.. usually the simplest answer is the right one. It seems like the simplest answer here is just that the column that's collapsed in the tiktok video (between spaces 27 and 28) caused the entire collapse within a few minutes. All of the rest might just symptoms based on how it happened to fall.. but it seems like it was going to collapse at that point no matter what. When CDI said that the concrete was soft too they were probably just talking about the foundation where they were drilling, which seems like it was never tested by MC.

Also, this is probably the most interesting thing I've seen on the live feed.. I think this is the column between spots 77 and 76. Interesting that it seems to have fallen in the same direction as the collapsed column in the tiktok video, which is right next to it. It seems odd that these columns could have fallen to the southwest if they fell with the pool deck and it collapsed straight down.

Perhaps Cassondra's description was right and the column collapsed by a sinkhole, pile issues, foundational, etc too. It just seems so bizarre that a column could topple over like that if it wasn't coming from below it.

 

[1503-44]

A column failing in buckling will fail in the axis of the longest (remaining) effective length, KL/r, unless it was acted upon by an outside lateral force, which would mean it failed in bending caused by that lateral force, not buckling. If the column's lateral restraint was removed (supposedly by the failure of the pool deck), and it failed in buckling, it would most likely fail towards the item that was providing that lateral restraint. Did they fail in the direction of the pool deck? Then it was pulled by the pool deck, there should be some evidence of stretched bars at the connection point, or if not, then it lost lateral restraint in that direction and buckled without help of lateral pulling by the deck, or some combination of both. If its a clean break, no evidence of bars being pulled out of the column (the column looks like a pencil point) then most likely an axial loaded buckle failure. IMO.

 

[Santos81]

I believe the very first few frames of the video positively identify the location beyond any doubt. In the first frame of the video, there is a double column on the left of the frame towards the back. I believe this can only be columns A.1 and B.1 in row 2.1. That puts the drilling firefighters between columns D2 and D5, drilling east into roughly the E line. I can't see any other combination of columns in the NW quadrant of the basement that fits the framing plan so perfectly. That puts them west of the shear wall line, but in the north half of the structure, north of the shear wall and corridor. Without checking, I think it's roughly under the service entrance / loading dock.

In other words, working into the collapsed lobby.

The trash room and chute were in the same location as shown on this plan. The security room didn’t exist. The mail room was moved south and a closet added north (after deciding against a separate UPH elevator in that location).

 

[jbourne8]

The lady in 111 said that security was right on the other wall from her apartment in one of her interviews btw.

 

[MJCronin]

This seems to be a fun paper that will be very very popular in Miami for the next few weeks ...

There are limitations to Ground Penetrating Radar in detection of rebar details in reinforced concrete structures !!!

An excerpt from the paper ....

It should be noted that GPR does not directly measure the diameter of a rebar, cable or conduit [10]. GPR when used with the larger diameter of rebar, can produce a stronger reflection of the radar wave. Due to signal wavelength, any object under 2″ (5 cm) in diameter is a “dot” with no visible size [10]. It should be noted that the reflection strength depends on several factors such as depth of the slab, area of slab and properties of concrete and steel. Thus, it is very difficult to obtain an accurate measurement of diameter of rebar in concrete.

https://www.sciencedirect.com/scien...thod can be accurate,top rebar diameter [11].

MJCronin
Sr. Process Engineer

 

[TugboatEng]

Ultrasound has a shorter wavelength. Interestingly, this study was done in Florida.

https://journals.sagepub.com/doi/abs/10.3141/2251-13?journalCode=trra

Somebody will have to pay to find out if it was effective or not.

 

[SFCharlie]

the best explanation I have yet to see so far.

This is an excellent video, 300K views, 20K Likes
WHAT was the CAUSE of the MIAMI building COLLAPSE | Teacher explains moment of COLLAPSE and FALL
Worth your while to watch even without understanding the Spanish

SF Charlie
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[KingBobo]

This seems to be a fun paper that will be very very popular in Miami for the next few weeks ...

Although this particular paper is focused exclusively on GPR, I would guess that X-ray imaging and destructive testing will be NIST's tools of choice for investigating the as-built reinforcement situation at Champlain Towers South. But no doubt there will be a huge uptick in demand for both GPR and X-ray inspection services throughout the region. Perhaps everywhere.

 

[jbourne8]

This reddit post has the best write up I've seen on the history of the building's permits in the 80s -

https://www.reddit.com/r/Catastroph...cw/champlain_south_tower_timeline_of_building

 

[pellucidar]

For the Spanish video, you can turn on autotranslate of the closed captions in the video settings (the gear icon). H/T reddit.

 

[Santos81]

The lady in 111 said that security was right on the other wall from her apartment in one of her interviews btw.

That’s not what Ms. Nir meant by her statements, rather that her unit was closest to the front desk.

It’s not a guess as to where it was located. The CCTV monitor and Fire Control Panel are a dead giveaway.

 

[SFCharlie]

WHAT was the CAUSE of the MIAMI building COLLAPSE | Teacher explains moment of COLLAPSE and FALL
Worth your while to watch

Attached: a Microsoft word file with 2 columns auto-caption Spanish and google translate English
Someone Please correct it. Thanks.

SF Charlie
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[Spartan5]

This is an excellent video, 300K views, 20K Likes
WHAT was the CAUSE of the MIAMI building COLLAPSE | Teacher explains moment of COLLAPSE and FALL
Worth your while to watch even without understanding the Spanish

Thanks for sharing. Dude has some chops. A few observations:
A. What a great model he has. How do you think that was generated? Time? Pretty neat.

B. I’m glad he added a caption of the word pandeo because I heard something completely different.

C. I thought he was using graham crackers to demonstrate punching. Then I thought he was going to build a whole physical model out of them.

 

[jbourne8]

Ah, the hard drive and server don't have to be located near the monitor btw. It could have even been stored offsite.. the monitor doesn't really tell us that much aside from that being a spot where they observed the feeds. They could even have a second or third monitor in another room connected to it too.

Sarah Nir explains the location in this video -

https://www.youtube.com/watch?v=1gie0XVOFl0

and says "so I ran to the security guy, that I live in the ground floor, so it's first floor. So it's really a wall separated between my apartment and the security guy." She also confirmed he heard the sound, which would make sense if he was located closer. I sort of bet from her description that the security guy was actually in one of the manager offices and he also had access to the monitors in there, and that's perhaps where the drives/servers were located. Usually they're behind a locked door and then a locked closet as well to keep people from tampering with them.. and they're almost never just tucked away behind a front desk. It's also very unusual to have a security monitor that's in your front lobby that shows all of your camera locations as this makes it too easy for anyone trying to slip past them.. which tends to be trivial if you've seen the entire feed. I bet that front desk monitor only showed a feed of the front driveway by default. The front desk was also probably staffed by a valet guy really, instead of security. They also had a 24/7 concierge that may have used that desk. But security, valet and concierge seem like too many people to share that one desk.

In the notes from one of the 2020 meetings they mentioned that they were going to rearrange the manager offices as part of their 40 year re-certification, and it might have already been reconfigured from the original plans. It being around the recreation/party room sort of makes sense.. since they only allowed access to it with reservations and it was only open certain hours. I'm still wondering what happened to the security guy and if he made it out alive, since he hasn't done any interviews.

 

[SFCharlie]

since he hasn't done any interviews.

He is probably being paid well not to do any interviews...

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[Santos81]

He is probably being paid well not to do any interviews...

SHE did survive by crawling out the valet window and went back in to help residents out through the lobby rubble.

 

[Murph 9000]

One of the many plans out there showed a management office on the eastern side of the gym. I think it was either in recent permits or the 40 year recert stuff. It was where apartment 110's living room would have been, if that part wasn't configured as saunas, locker rooms, and gym. That would be literally through the wall from the Nir's bedrooms in 111.

If the servers were in there, they are still deep in the pile. If there's sufficient value in them, hard drives can prove to be very robust and data potentially recovered from them. Basically, as long as the drives just got buried, soaked, and the circuit board destroyed, but didn't take a catastrophic direct hit, the data may be recoverable.

Edit: See page 39 of 8777-collins-avenue---preliminary-review-plans-for-40-year-re-certification.pdf which shows the office in the gym. Dated April 2021, and I don't know if it was actually there or moving there during the refurbishment.