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

[dik]

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

-Dik

 

[FJBnomics]

Am I missing something here?

From the picture previously posted below, we know water was pouring down the South side of the column, so apparently already a crack on that side.

The compass heading to SW of that one rebar could be the tug from the parking deck area collapse?

 

[Reverse_Bias]

Typical punching shear failures leave a piece of the slab hanging on the column head and more importantly do not cause damage to the column head itself. In this case all of the column heads suffered moderate to severe damage, even the one next to Jacuzzi that still had the back half of the slab attached to it.

I could picture 1 or 2 columns doing this but since it was every deck column, it points to a design or material defect in the columns as well as the slab.

 

[SFCharlie]

Am I missing something here?/quote]
You probably see that as the deck drooped over the column, it bent the rebar down. What's being discussed is that the rebar appeared to have been running north south before it was bent down. I remember posts and video showing that the rebar in the deck also only ran N-S, Not W-E as it should have in the before construction plans.

SF Charlie
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[SFCharlie]

it points to a design or material defect in the columns as well as the slab.

Yes. There was much discussion early on, that the columns were too small, with rebar too close to the surface.


SF Charlie
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[Mark R]

Here's an interesting video I just found from Josh at building integrity which covers a lot of what has been discussed recently, it was actually released on May 16. [URL unfurl="true"]https://www.youtube.com/watch?v=M0UtmbRAL9M[/url]

 

[Sym P. le]

Am I missing something here?

Of course they are bent down but they didn't turn to the north and south form their installed NE/SE/NW/SW directions. They weren't installed in the designed orientation. Not worth three posts explaining if it was even worth one.

 

[FJBnomics]

Of course they are bent down but they didn't turn to the north and south form their installed NE/SE/NW/SW directions. They weren't installed in the designed orientation. Not worth three posts explaining if it was even worth one.

Sorry, I respectfully disagree with you, on this one, at this time based upon evidence reviewed. However, I obviously did not articulate well the kind of details that Construction Engineering & Failure Analysis is looking at for clues in his videos.

Edit: Better to just watch his video's, if interested and can tolerate them. He actually has gotten a lot better since the first one I saw on the New Orlean's HardRock Hotel Collapse. After viewing one then, I quit watching his channel, and avoided it totally, until the last new videos were mentioned.

I could not finish some of the videos I found either, and only posted ones I thought were better and made good points.


EDIT on Two Way Slab Column Offset: The link below quotes ACI 318-11, and says column offset shall not be more than 10 degrees. Again, I think SFCharlie has the ACI Code from 1979, and could perhaps confirm what it said in 1979.

Under limitations, "Column offset of more than 10% of the span (in the direction of offset) from either axis between the centerline of the successive column is not permitted."

https://theconstructor.org/structural-engg/two-way-slab-design-direct-design-method-aci-318/14444/

 

[zebraso]

Construction Engineering & Failure Analysis is saying the bar is torqued because of the horizontal angle between columns. i.e. the bar is not orthogonal to the stresses. I'm trying to digest that.

 

[SFCharlie]

Unlike "kai" (funny, but I don't remember that was his name, when his channel was actually called "structural engineering and wedding photography"), I don't have people paying me to correct my mistakes, so I'm not looking it up. Y'all gona hafta take his word for it.

Construction Engineering & Failure Analysis is saying the bar is torqued because of the horizontal angle between columns. i.e. the bar is not orthogonal to the stresses. I'm trying to digest that.

I got bottle of Tums?


SF Charlie
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[FJBnomics]

Unlike "kai" (funny, but I don't remember that was his name, when his channel was actually called "structural engineering and wedding photography"), I don't have people paying me to correct my mistakes, so I'm not looking it up. Y'all gona hafta take his word for it.

Haha! I actually saw one of his wedding cake video's too! He was proving something, perhaps about lighting in photography of a wedding cake???

I really have no idea what his name is, I just took MaudSTL mentioning Kai, and ran with it. Probably another BAD ASS_U_mption on my part....

Oh well, he needs a name since CE&FA is a mouth full.

Edit: Here is Structural Magazine Recommended details on offset columns. Spoiler alert, additional layer of rebar....

https://www.structuremag.org/?p=14580

 

[zebraso]

I got bottle of Tums?

I'm stocked up on Prilosec, thanks. Not an endorsement. There's a reason why they want the tensile vectors to align with the bar. And I am sure there are plenty of scholarly articles on what happens if they aren't. I'm just trying to formulate in my mind what happens. I'm too lazy to look it up. For starters I am trying to imagine them at 45 degrees. I know it's bad though. I'm not working too hard on it though. And I don't have a slide rule in hand.

Edit: well having found that you must used finite element analysis in the design where the column offset exceeds 10%, I came to a halt. The gist of it I think is that you get a torsional component at the column strips. And it might mean that eliminating that beam was a particularly bad idea. Does that mean that whomever made that choice was bad at finite element? Inquiring minds and all that. This most likely has been looked at over and over at this point.

 

[SFCharlie]

it might mean that eliminating that beam was a particularly bad idea. Does that mean that whomever made that choice was bad at finite element?

Yes! It was a fatally flawed idea. Sorry, but we didn't have FEA back then, I was still working with a team to build a bad assed enough computer to run that "stuff?"



SF Charlie
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[zebraso]

360 was not good enough?

 

[SFCharlie]

Haha! I actually saw one of his wedding cake video's too!

It would have been funny, but at the time there were a lot more weddings and he was (mis?)representing himself as a structural engineer.


SF Charlie
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[Reverse_Bias]

Think it's almost time for a new thread, this one takes forever to scroll.

 

[hokie66]

Don't you think there have been enough threads about this? Nothing but speculation about a structural failure, and not a structural engineer in sight.

 

[SFCharlie]

PLEASE STOP POSTING IN THIS PART 16 PLEASE
Please allow me to move the discussion to Miami Beach, Champlain Towers South apartment building collapse, Part 17, Thank-you.
Someone Please close this post to new postings, or message me how to do this, Thanks.


SF Charlie
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[SFCharlie]

Someone Please close this Thread to new postings, or message me how to do this, Thanks.