Miami Beach, Champlain Towers South apartment building collapse, Part 16 24

[dik]

thread815-484587
thread815-484717
thread815-484915
thread815-485059
thread815-485171
thread815-485223
thread815-485379
thread815-485535
thread815-485637
thread815-485844
thread815-486084
thread815-486593
thread815-487022
thread815-488247
thread815-489644

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

-Dik

 

[IanCA]

@thermobaric Understood. Thank you anyway.

The reward is, you will see images I have not seen before, and receive data you have not seen or heard before.

Agreed.

the image of the exposed top of sheet piles in area of interest,

I'm interested to hear what others think but I think the feature highlighted in the image in my 21 May 22 05:30 post is closely spaced rebar rather than the top of the sheet pile.

Cheers.

 

[IanCA]

I am skeptical of the tightrope and compression theories for the south wall

Agreed. Especially considering the condition of the deck-to-wall connection at the Southern wall between column lines G.1 and K.

 

[IanCA]

Here is my first attempt to visualize the elevations.

Thank you very much for taking the time to do that work SFCharlie, it is helpful.

 

[SFCharlie]

Photo
Quote (thermobaric)
area that appeared to drop into sink hole

Since the responders are looking over the wall at the debris, I assume they are standing on the gravel that the construction to the south replaced the street (and walk?) with.
The exposed rebar seems to me to imply that the construction changed the structure of the wall.
I bet they didn't analyze this.

SF Charlie
Eng-Tips.com Forum Policies

 

[SFCharlie]

Some more work in the South Wall Area:

SF Charlie
Eng-Tips.com Forum Policies

 

[Sym P. le]

We don't have any information to conclude that the dip is anything other than a surface feature. A 4" step stemming from slab deformation would be immediately apparent in the garage and alarmingly so.

Note the significant amount of sand (or additional topping) under the tile in the area between the hot tub and the pool. In the first image, it appears that the sand layer tails off to nothing.

 

[SFCharlie]

This is not a tightrope, at least if its functioning as intended.

Yes! That is not the intent!

A stiff slab will sit on its support and sag slightly, imparting a slight bending moment to the support if tied in, or toeing up slightly and pushing out on the support if not tied in.

Yes! A properly designed slab and column design will function like this!

It's only when interior column supports fail that the functional aspect changes to the extent that it acts like a tightrope requiring tensile forces to be resolved with further design implications.

I would have preferred to say "column connections to the slab fail", but yes!

there is no such thing as drooping at the south support

Yes! The "drooping" in the slab, seems to have occurred between the wall and the first column, been worst over the 30 foot span, and between columns.

I apologize for not making myself clear!


SF Charlie
Eng-Tips.com Forum Policies

 

[Sym P. le]

I think I understood you, but it seems people don't connect with the vast difference in support that a continuous wall offers over a slim column.

 

[IanCA]

it appears that the sand layer tails off to nothing

Thanks for the photos. Do you think that was done intentionally to prevent rainwater from draining into the pool and hot tub, perhaps?

the vast difference in support that a continuous wall offers over a slim column

I agree with this in theory, but in practice, if design was weak (a single row of rebar at 12" centers, with minimal engagement), the construction was not well monitored (not considered a critical part of the structure), after years of corrosion, with regions bounded by construction joints, and the deck cracks as shown below (from thread 15), then the deck will be pulled from the wall.

Weak wall-deck connection:

Location of cracks and movement of deck matching photographic evidence (I hope you don't mind me using the version with your markup MaudSTL):

Edit: If the wall-deck connection was as strong as it should be in theory, why did it fail at all? I don't believe there is a mechanism that can achieve the tension cracks seen in the top of the stampcrete in the parking deck if the collapse begins North of column line 15. Can anyone sketch a sectional elevation showing the intermediate positions of the deck components that achieves those tension cracks in the top surface?

 

[Sym P. le]

Unfortunately, from a physical standpoint, that sketch is not realistic.

 

[IanCA]

Unfortunately, from a physical standpoint, that sketch is not realistic.

Please can you be specific? I would like to understand more about your perspective and see if it can be improved at all.

 

[Sym P. le]

It needs a support under the proposed break on the right side of the image.

 

[FJBnomics]

IanCA, I am not sure exactly where in your section view the cracks area located. Perhaps you could add them to the image below, where I show clearly the initial dropped area in MH released phone aligns with 19"x19" slab cut out for pool exhaust fan, thus no continuous rebar attachment to South Wall in North-South Plane which is the 'heavy hitter' of the two way slab... Thus could explain a more localized failure at first, and be source of your crack propagation?

 

[IanCA]

It needs a support under the proposed break on the right side of the image.

That section of the deck is supported in cantilever by the columns to the north:

Remember the crack in the top surface in tension runs from the South-West at planter at column line G.1 to the North-East column at Column line K as shown in the diagram in my post on 27 Feb 22 18:29. Included again here for convenience.

 

[IanCA]

Perhaps you could add them to the image below,

Approximately like this. With the section on column line I.

 

[FJBnomics]

And of course, there is a discontinuity E-W too, at 19"x19" Hole in slab.

A lot of Construction Engineering and Failure Analysis Videos are no longer available on YouTube, indicating the 'Ministry of Truth' had them pulled?

However, the recent ones I watched, suffering thru the noise, I did find nuggets buried in each once, which indicate that I14 and I 14.1 could be the center of initial failure area. He even showed Leman's Assumptions for her model that were way off, and drove the answer the model spit out. I see why you have to throw out the MH model now, based upon invalid constraints input into the model.

He also supports parking deck failing first, then patio deck, then building. He also makes an argument the insurance companies don't just settle out of court for a Billion Dollars without getting some benefit out of doing this. That being they would be able to raise insurance premiums drastically to recoup their payout.

He also shows NIST destroying evidence in a video, and dragging a rebar out of a sample they cut with jack hammers and sledge hammers. Also the fact they pulling samples in the wrong area, and had already destroyed the evidence in the potential root cause area, as if they had already decided what the cause would be.

Tough to listen to his videos, and you will need to keep your fast forward key warm. However, he is receiving information the general public does not have access to.

 

[SFCharlie]

A lot of Construction Engineering and Failure Analysis Videos are no longer available on YouTube, indicating the 'Ministry of Truth' had them pulled?
...
Tough to listen to his videos, and you will keep your fast forward key warm, but he is receiving information the general public are not being allowed to see.

He is excellent at seeking out info for his profession as a youTuber, but he hordes sources very close to his chest. I found this blog by searching with Google for his sources. His 'Ministry of Truth' is probably a copyright complain by the originator of his content.


SF Charlie
Eng-Tips.com Forum Policies

 

[MaudSTL]

He even showed Leman's Assumptions for her model that were way off, and drove the answer the model spit out.

Would you please link to that particular video? I’d like to try to listen to it.

FWIW, I listened to Kai’s early videos, quitting when he started focusing on insults received and starting fights with other YouTubers. But as I recall, he almost immediately after the collapse theorized that the locus of failure was the very area we are currently discussing, based on his construction expertise and analysis of how the punching shear scraped specific sides of the columns and how the slabs “butterflied.” I think Kai intuitively understands materials.

 

[SFCharlie]

I listened to Kai’s early videos

Are you speaking of Kai Kostack?

SF Charlie
Eng-Tips.com Forum Policies

 

[SFCharlie]

Or this Kai

4 months ago
I am working on a video series that will prove magnetic frequency and NOT gravity is what ''holds'' our planets together...

SF Charlie
Eng-Tips.com Forum Policies