Miami Beach, Champlain Towers South apartment building collapse, Part 03 148

[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

Thank you

SF Charlie
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[Roga50]

Here's the video on the planter piping and waterproofing: Link

 

[Santos81]

Can anybody identify the three circled features, they were not there a year before

L-R

Towel

Woman stretching

Patch covering Test Probe A

I think the pool contractor on site days before would have noticed a gaping hole in the slab.

 

[JohnRBaker]

Another apartment complex in Florida has been ordered evacuated as a precaution after city officials became concerned over a recent report about the buildings:

North Miami Beach building deemed unsafe, evacuations ordered

A Jan. 11 report on the Crestview Towers condominium complex said it "was structurally and electrically unsafe."

https://www.nbcnews.com/news/us-new...=939436973772504317&utm_medium=Email Sailthru

John R. Baker, P.E. (ret)
EX-'Product Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[Js5180]

The comments about the tests on the roof being 25% of each anchor at 5,000 lbs instead of all anchors at 25% of 5,000 lbs is very interesting.

At some point, doesn’t the slab act like a bow and arrow, so that it could be cracked if the two anchors are pulled together hard enough? What amount of force would it take to crack a 6” slab from two points 20 feet apart? Are we talking orders of magnitude more than 5,000 lbs?

It would be very interesting to know if and when this test was carried out.

...

I also think it’s premature to dismiss the broken roof theory simply because it wasn’t reported by any witnesses. It really wouldn’t have to be obvious to them.

How large an object would have to fall off the roof to cave in the pool slab? That’s the real question.

If you say the slab could have collapsed entirely on its own under its own weight, then any falling object whatsoever could have broken it. Could a single CMU do the job? A few hundred pounds? And a falling object wouldn’t necessarily need to hit every balcony on the way down. The roof cantilever is big enough that an object could easily clear every balcony.

At the starting time of the only video we have of the collapse, the rear penthouse parapet is unaccounted for. It can be theorized to simply have already started falling vertical, but as of right now, the video is not sufficiently clear to be able to say that. When that roof eventually comes back into view, as its folding over the collapsing stack, we can see what looks like a brand new coat - pure black, with no ballast on it yet.

A collapse of the rear penthouse, being recently worked on, and throwing a modest chunk of parapet wall off the edge, could have easily caved in the pool deck near unit 111.

Bystanders who ran out when the deck collapsed would not have seen a falling chunk of wall, nor would anybody on the ground have visibly noticed a collapse of a portion of the penthouse. Whether the floor of the penthouse could have survived the collapse of the roof, I can’t say. But nothing appears to disprove a rooftop event preceding the collapse.

 

[dik]

FWIW...

https://www.dailymail.co.uk/news/ar...condo-collapse-supports-pool-deck-theory.html

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[dik]

easy... coring on an angle...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Js5180]

If I’m not mistaken, the person who they were in verbal communication with was from unit 204, and would have been next to the generator and above the fuel tank. They could not save her because of the fire. The theory that the fire came from the generator and/or fuel tank sounds plausible.

 

[Torai]

Towel
Woman stretching
Patch covering Test Probe A

Plausible, looks like some other people walking around. Unfortunately the foliage in the planter hides the shadow which can reveal height/vertical profile.

For example, you can see which pool loungers are reclined up and which are flat.

 

[IEGeezer]

Js5180[/b] How large an object would have to fall off the roof to cave in the pool slab? That’s the real question.]

If a 500 lb (~250kg) HVAC unit were to free fall to the lobby level, it would hit with a force of 828,100 Newtons which would be about 186,164 lbs-f. I used this calculator:

http://hyperphysics.phy-astr.gsu.edu/hbase/flobi.html.

I assumed a falling distance of 111 feet, which is 125 ft for the penthouse level minus 14 feet for lobby level or so. I assumed a stopping distance of 0.1 meter to maximize resultant force. Question: would the HVAC unit go right through the slab, or would it collapse it?

I don't know that there is any evidence that anything free fell onto the lobby level slab from the penthouse. Just figuring.

 

[rapt]

Just saw the new drop panel proposal shown by GPR_Tech post on 2nd July.

Not sure what benefit the remedial designers thought they were going to get from that!

 

[spsalso]

There was very roughly 400 gallons of gasoline in the collapsed part of the garage, plus a fair bit of flammables in the debris.


spsalso

 

[Murph 9000]

Question: would the HVAC unit go right through the slab, or would it collapse it?

I don't know that there is any evidence that anything free fell onto the lobby level slab from the penthouse. Just figuring.

If you're talking about a scenario of the big HVAC somehow falling off the edge of the building onto the pool slab (prior to the major collapse of the building), that's impossible. The big HVAC was on a support frame sitting on columns E2,H2,E4,H4. That is to the north of the elevator shaft and penthouse corridor. The penthouse corridor can be clearly seen in the collapse video as being mostly intact in its original location at the start of the collapse. It provides a solid barrier between the HVAC unit and pool slab, in addition to the implausibly large distance from the south parapet. The big HVAC unit falling probably could have triggered a collapse of the slab, but there's just no way that happened. It also would not have ended up on top of the rubble, roughly where columns I2 & I4 were.

A more viable theory involving falling objects would be the parapet from the roof of the south west quadrant of the penthouse. The disposition of that parapet is uncertain in the collapse video. It may be up at the top of the facade before the major collapse, or it's possible that it may have fallen down onto the pool/patio/plaza slab. The timeline for any possible fall is equally uncertain. If it did fall, it might have been mere seconds before the facade and major collapse, or it could have fallen minutes earlier and be responsible for collapsing the slab. We need the 15+ minutes prior to the major collapse from that CCTV camera, if it exists. There's no conclusive evidence right now around the parapet (or the cantilever section of roof).

 

[Santos81]

Plausible, looks like some other people walking around. Unfortunately the foliage in the planter hides the shadow which can reveal height/vertical profile.

In all seriousness, without better resolution images of the area, identification of the west and center areas of intrigue with certainty is difficult. The east anomaly is the patch/temp cover for the Windsor Probe Test. Thinking back on some previous experiences in the area with some of the same characters in this story, the center is probably a black cleanup bag stuffed in the bore hole and spread out with sandbags around the perimeter. There may or may not be a plug fitted, but it wouldn’t really make any difference. To the west, additional sandbags as that planter wall is really just a step.

I may have missed it in the earlier threads, but has anyone caught on to the fact that planters in the pool area have been significantly enlarged at some point in time?

Those punch test result images in the planter areas are, well, curious.

 

[warrenslo]

The roof cantilever is big enough that an object could easily clear every balcony.

THe Penthouse and 12th floor roof extend over the two windows where the collapse appeared to start.

When that roof eventually comes back into view, as its folding over the collapsing stack, we can see what looks like a brand new coat - pure black, with no ballast on it yet.

The roof over the penthouse is brand new roof paper in photos post-collapse.

{quote IEGeezer]If a 500 lb (~250kg) HVAC unit were to free fall to the lobby level[/quote]
The large HVAC unit moved to be over the remaining building in 2019 flipped over due to supports of its steel frame failing and was on the top of the pile upside down several floors up.

The residents were complaining about the structural engineer who seems to be related to the roof anchor contractor 3 days prior to collapse in this email:

My concern is Morabito Consultants would recommend demolishing the remaining building to eliminate any evidence. Due to the transfer slab on the second floor, I believe most of this building is stable with enough shoring. It was stable enough to resist progressive collapse. Most of the shear seems to be in the remaining building. In my opinion, they should have shored the accessible parts of this building on day one.

As the inspection records the city has posted only go to 2019, I have sent this to the city. If the anchors installed that day were over x11 stack we have a very solid hypothesis.

 

[OSUCivlEng]

Sorey asked for an audit and review of all high-rise condo buildings above five stories to determine if they were in compliance with the county and city 40-year recertification process and certified as safe for occupancy on June 29.

After department files showed Crestview was not in compliance, an inspector went to the building on Friday to follow up.

That same day, the Crestview Towers building manager brought a recertification report dated Jan. 11, 2021, to the North Miami Beach Buildings Department, where the association’s engineer deemed the property unsafe.

Wait, what? Am I reading this correctly? The association's engineer deemed the Crestview building unsafe in January?

https://www.nbcmiami.com/news/local...cuated-after-structure-deemed-unsafe/2486856/

 

[Mark R]

Mayor authorizes demolition of remaining units at Surfside condo collapse site as death toll grows to 22

 

[Roga50]

Wait, what? Am I reading this correctly? The association's engineer deemed the Crestview building unsafe in January?

Is there a mechanism (or better, REQUIREMENT) that when an engineer sees conducts an inspection and identifies a building that is unsafe, they can immediately go to the city and get the building red-tagged and closed? (if not, there should be IMHO...) From the things we're seeing down here, it seems like the answer is either No, or it's not being enforced (or the inspectors are being ignored)

 

[Santos81]

My concern is Morabito Consultants would recommend demolishing the remaining building to eliminate any evidence.

Morabito has no say in the matter. It’s still an active search and recovery mission with multiple Federal, State, and County Investigations in the early stages. Until it’s forensically cleared and evidence taken to the secure location, the site must be viewed no different than any other mass casualty crime scene. This includes FOIA requests. Until they’re deemed no risk to any investigation, they won’t release them.

 

[OSUCivlEng]

I wonder how they got 13" cores out of a 9" slab.

Drilling took place up to a foot down in order to determine the structure of the concrete below. The work 'yielded some curious results as it pertained to the structural slab's depth' - but the reason as to why the results were 'curious' was not explained

https://www.dailymail.co.uk/news/ar...condo-collapse-supports-pool-deck-theory.html

 

[Js5180]

Warrenslo - definitely looking more at the parapet(s) although it’s hard to rule out an HVAC unit as the round object in the garage debris.

The parapets have the mass, they are likely to be minimally reinforced CMU, and they’d come off easily enough. Looking at the ones on the ground and they are generally broken into fairly small parts, far removed from their roof slab which stayed mostly intact. And you are right - the only balconies under them were the 12 and PH.

Also, at the time of the collapse, the upper x11s are the only units with lights on. That could be a coincidence, or not.

Still, I’d like to better understand what kind of force on the roof it would take to break a 6” slab, either with dead load or an anchor test.

Finally, as far as the covering the evidence, I suspect there are a lot of parties who’s litigation chances improve if the building is demolished. I’d expect the plaintiffs’ lawyers to seek an injunction delaying the demolition, provided the building survives the next storm.