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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[bones206]

Yea I didn’t see the planters until someone had enhanced the photo to just the right lighting and contrast. But once I saw it I couldn’t un-see it.

 

[gonefishing2]

So bones206, if what you are seeing is correct, we definitely have slab failure before beam total failures

 

[Js5180]

Microwizard,

There is evidence that the pool deck collapsed, but there is no evidence as to its cause. It’s also several minutes prior to the main collapse.

There is also evidence, in the very first frames, that the roof parapet has fallen much further than its adjacent slab to the east. That same visual evidence shows that it sheared free of the M column row, while the next portion of the slab to the east stayed up, supported apparently by the M columns.

I don’t think any of the above is disputed, but if it is, please correct me. The above doesn’t mean the roof fell on the pool deck, necessarily, but I’m trying to line up the undisputed facts first.

I am not invested in a particular theory, but what’s problematic to me is that the lights in some units below are still on, despite the suggestion that the x11 units had already fallen 2-3 stories.

What’s also problematic is that Josh/Building Integrity attempted to disprove an early roof event by claiming that the electrical runs are vertical from the basement. That is clearly wrong. The rest of his theory could turn out to be correct, but right now, it’s going to need some maintenance (which I presume he will do as he’s done before with changing facts).

So that leaves us with an unexplained absence of a very specific roof slab and parapet in the early video frames, along with an unexplained pool deck collapse. How did roof slab K/L/M shear so completely from roof slab M/N/O/P at the M column lines, if M10 had sunk several stories?

Yellow arrow points at M boundary between those slab areas:

 

[waross]

Comment on the roof fell theory:
The deck had deteriorated to the point that multiple columns punched through simultaneously.
Debris fell from the top of the building and caused the deck to suffer multiple punch through failures.
My disbelief:
An object falling from the top of the building with enough energy to cause a punch-through of 10 or 12 columns may be much more likely to penetrate the rotten concrete of the deck, without causing a complete collapse.
Or, alternately, the falling object would likely penetrate the deck and leave a large hole, whether or not it triggered a complete failure.
Very little of the debris from the collapsing building fell on the pool deck.
Did something from the roof fall onto the pool deck and trigger the collapse?
Possible but highly unlikely.

Comment on the vehicle impact:
It is known that the concrete and the rebar in the columns was severely degraded.
The objections to the vehicle strike theory may be based on a column of normal strength.
These were not normal strength columns.
I don't know what the original safety factor was, but let's assume a safety factor of two.
As the column degrades, the safety factor drops. The higher the safety factor, the longer the time for the factor to drop to one, but with progressive deterioration, eventually the safety factor will drop below one.
With no safety factor it may not require a high energy trigger to cause one column to fail.
That failure will transfer loads to adjacent columns and slab connections with not enough residual safety factor to prevent a punch through.
Could a vehicle, striking a badly corroded, deteriorated column with almost no safety factor have triggered the collapse?
Possible and highly likely.

Or;
Eventually, in the absence of an external trigger, unequal thermal expansion and contraction may have triggered the collapse.
Possible but highly unlikely.

Another thought on the "soft" concrete and a vehicle impact. This is more of a question than a statement.
With the "softer" the concrete, more of the load must be carried by the rebars.
If a vehicle impact crushed the soft concrete, could it also have bent some of the rebar out of the vertical plane and taken the load bearing capacity of the column below the actual load?
Comments invited on this possibility.
I have seen very poor concrete and I have witnessed concrete samples being taken inappropriately. (As the inspector was placing the sample cylinder in the trunk of his car, the mixer operator was spinning the water valve wide open to increase the slump. The test strength of the test sample had no relationship to the actual concrete strength as placed.)

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[gonefishing2]

Js5180, I see parapet and perhaps penthouse cantilever missing, and perhaps the lower paraphet, and cantilevers in the middle area. I have studied similar picture angles of building before collapse, and I see the middle cantilevers and parapets in plane with the East ones.

 

[AtomixPro]

Regarding the HVAC units falling theory, the great number of units dangling off the still-standing wing, by what appears to be their electrical or refrigerant lines, indicates that they wouldn't readily roll off the roof. Even the sudden jolt these experienced as they were tugged between their roof attachments and their elec/freon lines wasn't enough to bring them down. Perhaps something else rolled off, but the HVAC units seem unlikely.

 

[spsalso]

I found this interesting photo taken June 30:

spsalso

 

[gonefishing2]

Would racking of structure from construction next door, and 40 years of under-nourished slab and column connections caused enough deflection and flex to make rebar fail due to work hardening and salt water decay?

 

[dik]

This showed up in my earlier post where he was using less than optimal concrete strength and 3/4" cover for repairs... gotta shake your head sometimes.

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

-Dik

 

[Demented]

That rebar wasn't coupled together was it?

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

 

[mb3928]

Another piece of evidence against the roof collapsing first, that I haven't seen anyone mention yet: no fire alarm until during/after the collapse. The garage was the only floor without a flow switch per the 1979 plans. A collapse anywhere would have broken a sprinkler pipe. Breaking a sprinkler pipe anywhere other than the garage would have activated a flow switch, and set off the fire alarm. Only a collapse in the garage could have broken a sprinkler pipe without setting off the fire alarm.

 

[Demented]

Would racking of structure from construction next door, and 40 years of under-nourished slab and column connections caused enough deflection and flex to make rebar fail due to work hardening and salt water decay?

Work hardening unlikely. Salt water decay, without a doubt.

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

 

[julootamu]

I can't understand no flow switch in the garage as that is where I would worry about sprinkers being set off by a car fire.

 

[pellucidar]

Another piece of evidence against the roof collapsing first, that I haven't seen anyone mention yet: no fire alarm until during/after the collapse. The garage was the only floor without a flow switch per the 1979 plans. A collapse anywhere would have broken a sprinkler pipe. Breaking a sprinkler pipe anywhere other than the garage would have activated a flow switch, and set off the fire alarm. Only a collapse in the garage could have broken a sprinkler pipe without setting off the fire alarm.

The penthouse wasn't yet in the plans in which the garage had no flow switch, at least not on the page I posted.

 

[gonefishing2]

I am not in Florida, and the Surfside Document Link has been unaccessible from my location for several days.

This is URL I am getting 404- File or Directory not found.

https://townofsurfsidefl.gov/depart...erk/champlain-towers-public-records-documents

Have they moved the files to another location, or is site down, or have Politics intervened after reading this forum???

 

[Js5180]

Thermopile - exactly. The floors are still in plane.

Mb3928 - Did the alarm EVER go off?

 

[waross]

If the garage had a deluge system, a broken water pipe may not trigger an alarm.
Some deluge systems use open sprinkler heads and a second dry, air pressurized pilot system.
If a head on the pilot system operates, the dropping air pressure allows a water valve to open and supply water to all of the wet sprinkler heads.
Deluge systems are often used for vehicular areas. A typical system only supplies water to the head that has overheated. A deluge system supplies water to a zone including the area of the head that triggered the flow.
A flow switch is not required. The alarm may be generated by a limit switch on a part of the main water valve, and a broken water line may drain accumulated water but it will not initiate the main water flow.
The alarm may also be initiated by a pressure switch responding to the dropping pressure in the pilot line.
This may also start an auxiliary pump.
Don't assume that a broken sprinkler pipe in a parking area will have the same result that would be expected in a building sprinkler system.

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[jbourne8]

If that white object on the floor isn't a column, where is the column? It seems pretty unlikely that it fell behind column 27, as there's nothing pulling it in that direction. The pool deck near it also fell straight down, and wasn't pulled by the column anywhere. The column is really the only object that we know exactly where it should be, and it's missing. In my opinion, that's the only really interesting thing about that tiktok video since it's such low resolution. Also, column 28 must at least be partially in this photo because of it's proximity to column 27, and we know that one was a sheer puncture.

Is there a reasonable explanation for why half of the column would be smashed into bits if something fell from the roof or if the building suddenly deteriorated beyond some small cracks that day? It seems to make the roof theory the most implausible one. We get a good view of this column in the 2020 tour too and it looks like it's in great shape, same with the columns closest to it. No matter where you think the column is, in the tiktok video it looks like it was completely separated from it's rebar down below. What could even cause that? This column was barely under any load, and the column under load is still standing. Good point on those white rocks too, it would make more sense if they were from column 27.

I think if you look closely you can also see the straight yellow line of paint near the bottom of that column, but that would just place the column even further from where it should be if that's the case. Something more like this, with mostly the top missing. Perhaps the top of it stayed attached to the horizontal column above and that's why we can't see all of it? But I can't quite make sense of it separating from the rebar completely at it's bottom, and it being so far from where it should be. There just isn't enough rubble near it to have pushed the column around at all.

And that surveillance photo isn't proof of much, since the video doesn't start at the beginning of the collapse. It's impossible to know for sure what happened in the seconds before it.. it's just a guessing game when it comes to the roof first theory because there's so little proof that was the case. Most people report only hearing two smash/crash/boom sounds before the building completely collapsed.

 

[jbourne8]

Thermopile, you can find them here now -

https://surfside.one/public-records-search/

No clue why, but that site was setup a day or two before they took the other one down so it was probably just a migration to a better site for them.

 

[microwizard]

I am not invested in a particular theory, but what’s problematic to me is that the lights in some units below are still on, despite the suggestion that the x11 units had already fallen 2-3 stories.

No more than 1 story. As you have seen the analysis on youtube by Building Integrity, you have seen he accounts for all the upper floors - there is no collapsed penthouse, it is right there in the image. We can't see well enough to see that the parapet wall is still there, but it is not obviously missing.

Josh made an error wrt the electrical wiring, but his statement that one frame later (40 milliseconds?) the lights go off anyway. That doesn't seem unreasonable. To make the roof collapse work, something on the roof has to come loose, jump over the parapet and land at the exact right spot below to weaken the patio deck. That seems far more problematic than explaining the lights staying on a fraction of second longer than might be expected.

Building Integrity also does a great job analysing the roof and showing it was not overloaded. The argument that drilling roof anchors or a proof test weakened the roof is just speculation, there is no evidence. While work on the roof might be a good place to start an investigation, it turns out there is nothing in it and it was indeed coincidence.

The simplest theory that fits the majority of known facts is a collapse initiated in the basement. Making the roof collapse theory work requires too much speculation about events we do not have clear evidence for. It really seems like trying to make the facts fit a theory. At the very least, it is premature based on what we know so far. It's possible the investigation will find a smoking gun in the rubble, but there is just nothing significant enough right now.