Miami Beach, Champlain Towers South apartment building collapse, Part 12 60

[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

SF Charlie
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[TheGreenLama]

@MaudStl
It looks to be 3 column lines from south edge-- 12.1 --and about 2 west of pool--between L & M.

 

[SFCharlie]

You could also just go with “sharp and forthright.”

I was thinking of the condos, not the comments. I guess I'm the one who's archaic. Sorry.

SF Charlie
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[SFCharlie]

I thought (dangerous, I know) that if FDOT was researching in 2017, that maybe there were some results by now. I googled each of the topics, and, sure enough, each had a published paper. I downloaded all four. The one I felt was most applicable (Durability Evaluation of Ternary Mix Designs for Extremely dot dot dot ) is attached below:

If you wish, I would be glad to upload any or all of the following:
1. Performance Improvement of High Early Strength (HES) Concrete for Pavement Replacement Slabs
2. Effects of Blast Furnace Slag Characteristics on Durability of Cementitious Systems for Florida Concrete Structures
3. Development of Calcined Clays as Pozzolanic Additions in Portland Cement Concrete Mixtures


SF Charlie
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[gonefishing2]

I was thinking of the condos, not the comments. I guess I'm the one who's archaic. Sorry.

I prefer considering myself 'Vintage' rather than archaic.......

 

[SFCharlie]

A brief but apparently recent drone shot of the CTS slab with NIST at work

Good catch
I'm glad someone is keeping a watch on the research and investigation.
Please like and comment on the video. They can use the support.


SF Charlie
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[MaudSTL]

It looks to be 3 column lines from south edge-- 12.1 --and about 2 west of pool--between L & M.

Thank you! I am so used to looking at the plan drawings and counting down from the top that it threw me off to see a different orientation.

I guess I'm the one who's archaic.

I think plenty of us are no longer young whippersnappers.

 

[Red Corona]

That drill rig is over L12.1 I believe. That's one of the columns under the pool deck (but not the building) that puncture sheared and remained standing, so I'm not sure why it's of interest.

 

[SFCharlie]

Sorry, I couldn't help myself...

SF Charlie
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[Nukeman948]

I'm not so sure that is a drilling rig. And that blue rectangular object looks to be sized to fit inside the black framework. And that crane is big enough to drop that blue object through the frame for seismic testing of some sort. (just spitballing here.) Maybe getting a baseline on that column or maybe they suspect it started there. I need more pixels.

 

[SFCharlie]

I need more pixels.

Yes, we all do...

SF Charlie
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[SFCharlie]

I managed to squeeze out a few more (no pixels were harmed in the making of this power-pointy)

SF Charlie
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[TheGreenLama]

The name of the company listed on the side of those trucks would be very useful.
Edit: It doesn't look like ground penetrating radar. Wonder if it's water related?

 

[SFCharlie]

I've attached the unadulterated frame from the downloaded video. Please describe any process you may use to enhance it.
(Anybody local have camera, will travel?)

 

[SFCharlie]

Re: Aggregate, Remedies
Starting about page 20, the attached presentation discuses
'Corrosion-Resistant High-Performance Materials' CR-HPM

 

[Vance Wiley]

This would be easy if the code or comments had simply stated that column capacity is limited to steel contribution of no more than (some) %Ag. I see a reason for limiting the maximum contribution of the reinforcing.
The key word in this is the word "Lap" which creates a zone with twice the amount of reinforcing. The comment specifically states the purpose of limiting the % of reinforcing is to avoid congestion and facilitate the concrete placement. I can see congestion and small spacings causing poor concrete at a lap section with too much reinforcing - 16% is a lot of the column area and bars will be close together. Some cases require the large aggregate be removed and the first portion of the pour be a slurry with higher cement content. Normal practice is to lap with the bars in contact and the dowels from below oriented to the interior behind the bars above and that helps a bit.
From the commentary "Longitudinal reinforcement in columns should
usually not exceed 4 percent if the column bars are required
to be lap spliced, as the lap splice zone will have twice as
much reinforcement if all lap splices occur at the same location."
I do not read anything there which prohibits a maximum of 8% "at any section" if the bars are not lapped.
The practical workaround is to use splice couplers and keep the bars aligned with the dowels from below. There will no doubt be some discussion of whether the added size of the coupler should be considered as increasing the percentage of reinforcing at the coupler location. I would say technically it does and practically it does not have to, therefore the working % for the column must be less than 8%. This can be fudged by splicing the coupler splices at different heights starting maybe one coupler height above the previous pour. This complicates things and probably should be avoided. BUT if aggregate size allows and mix properties of slump and consolidation efforts are successful, that should be allowed.
The best solution is to avoid highly reinforced columns and just make the column larger, thereby easing the difficulty and increasing the likelihood of success.
Perhaps this has been discussed within the Concrete Design industry and that would be interested to see. Ultimately the EOR is in charge and can decide whether to take advantage of the ambiguity or go conservative and increase the column size.
I would recommend a larger column if a design was closing in on 8%Ag working reinforcing. But then there are architects who want skinny columns.

 

[CE3527]

In the drone video, the blue box is over the "missing" column in the Tik Tok video.

 

[AusTony2046]

Surely that "Blue Box" is what we in Oz call a "PortaLoo" ??

 

[SFCharlie]

Surely that "Blue Box" is what we in Oz call a "PortaLoo" ??

I admit that was my first thought also, but in this frame from the video the aspect ratio seems wrong.

SF Charlie
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[AusTony2046]

Could it be a Tardis?

 

[SFCharlie]

Could it be a Tardis?

Ah,definitely, that's it!


SF Charlie
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