Miami Beach, Champlain Towers South apartment building collapse, Part 04 49

[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

SF Charlie
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[gonefishing2]

You can see peeled paint all the way up to the panel too

 

[spsalso]

Fresh water may not damage a jeep. Is it still fresh water after it has percolated through that concrete-like substance overhead?


spsalso

 

[jbourne8]

Yea, it's possible. The building may have even installed them, so the pipes wouldn't drip on people in the walkway. They had a lot of strict rules there it seems about what you could do with the main common areas.

 

[jbourne8]

The video at the bottom (not the top) of this article is interesting too.. one of the residents documented that the pipes were leaking in the garage in 2018 -

https://nypost.com/2021/06/30/gripp...antic-escape-from-collapsed-florida-building/

Seems like it was probably taken from parking spot 113 though, and not the collapsed portion. Perhaps they're the pipes for irrigation for the front planter beds?

 

[hokie66]

Rain water leaking through a concrete slab can without doubt damage the paintwork of a Jeep, or any other vehicle.

 

[Mark R]

Looking at the drawings I’m bothered by them calling the rebar “wire mesh”. I feel it would be more appropriate to call it structural steel.

I think what they are talking about is actually WWF not rebar. It's mentioned in reference to the topping slab which is only 2½" which is to thin to put a tide rebar mat in. I don't mention what the reinforcing is in the structural slab.

 

[gonefishing2]

Yea that rusty rebar looks nasty.... And I love the duct butter fix on the cracked pvc pipe

 

[dold]

I'm not sure if it was mentioned yet but I wanted to add this because I just found it. It's their minutes report from their October 2020 meeting. It looks like they did exploratory demolitions and there's some photos in there.

Just reading through the presentation starting on page 55 of the Oct 2020 meeting minutes will give you a good sense of what condition the overall building and systems were in that time. It appears to be more detailed than the field reports we've been reading.

 

[apper.42]

If I was assigned to evaluate the safety of a building over 40 years old in a marine environment and with known problems in the deck waterproofing with at least 10-12 psf of superimposed load due to added overlay of pavers and a waterproofing layer, deteriorating balconies and a leaky roof, my priority would be to test the strength of the existing concrete in these locations. To accomplish this I would have concrete cores taken from the pool deck, roof slab and balconies. For the pool deck probably two groups of 6 cylinders each at the very minimum. Possibly more to be added depending on results. The roof would probably require another 3 at the very minimum in the wettest areas and another 6 from the worst looking and most poorly drained balconies. More to be taken later if deemed required.

The cores should be taken, visually inspected, prepped and tested in accordance with ACI 214.4R10 (Reapproved 2016). Results would be interpreted and adjusted if necessary for L/d ratios and variations in samples. Besides ACI 214 there are several publications and even Utube videos on coring, inspecting for aggregate, voids variations in diameter of each core, testing and interpretation. These strength tests along with a visual inspection sounding and other tests should give a much better of the structural condition than used in the 2002 repairs and the 2018 report by Morabito. Other inspection should probably include masonry parapet walls and any masonry shear walls and a quick check of the building loading and capacity if required.

If results found were as bad as I suspect then immediate shoring of parts of the structure would be appropriate until structural and other repairs or evacuating the building could be completed. Hopefully investigators will find enough in tact concrete from the critical locations to complete some strength tests.

 

[Murph 9000]

Hopefully investigators will find enough in tact concrete from the critical locations to complete some strength tests.

There's also evidence from CDI. Mark Loizeaux has 50 years experience of old concrete columns. Mark and his driller (presumably also a world class expert on what 40 year old concrete is like) both commented that it seemed very "soft" in places.

 

[bones206]

Has anyone figured out the mystery of the drop caps shown on the original plans? The video seems to confirm that drop caps were not provided. The plans are frustratingly silent on what those dashed line outlines represent, but I don't know what else they would be besides drop caps. Seems like a huge potential gaff in the design and/or construction.

And I still see the beam deflection, sorry. The stains on the left third of the beam do sort of suggest some nominal level of flexural/shear cracking as well. It may be nothing, but it's another data point in the area of concern.

 

[Js5180]

That deflection is towards the center of the photo.

Of two general types, that would be “pin cushion” distortion, rather than “barrel” distortion.

A showing that barrel distortion is inconsistent with the camera would prove the point. And I’m pretty sure a phone camera distorts away from the center, in the barrel shape.

 

[MikeJ65]

Speaking of that beam, is it just me, or does it look like natural concrete when the rest of the columns/ceiling are painted white. Is it possible that this was an older repair?

 

[dold]

Has anyone figured out the mystery of the drop caps shown on the original plans? The video seems to confirm that drop caps were not provided. The plans are frustratingly silent on what those dashed line outlines represent, but I don't know what else they would be besides drop caps. Seems like a huge potential gaff in the design and/or construction.

I would have to assume the dashed lines are designating the column strips. Bars specified over columns must lie within the column strip. But I havent seen any explicit definition of that on the plans.

 

[Santos81]

There's also evidence from CDI. Mark Loizeaux has 50 years experience of old concrete columns. Mark and his driller (presumably also a world class expert on what 40 year old concrete is like) both commented that it seemed very "soft" in places.

Upwards of 50% loss in strength. Moribito had additional cores taken as well earlier this year for lab testing. It obviously was severe enough to hault all non-roof concrete restoration due to concerns with placing equipment on the plaza slab.

Alyn submitted his preliminary recommendations based on evidence collected so far. I’m not sure if it’s been added to the Public documents. Strong emphasis on new geotechnical surveys to compare with original geo core samples and concrete deterioration from tidal saltwater intrusion in below grade areas.

Concrete core samples ONLY after scanning to avoid compromising structural reinforcement.

Where CTS was constructed is a rather unusual location geologically, having been a natural tidal pool that was later enlarged before being filled to construct CTS.

 

[bones206]

dold - the lines representing column strip extents is pretty obvious in hindsight, thanks for clearing that up.

 

[aggualaqisaaq]

This pic comes from the report Pengawin linked above. It’s the test probe area in front of the 111 planter…

Is it just me or does there appear to be some sagging near the edge? Is that normal?

“NOOK-yoo-ler. It’s pronounced NOOK-yoo-ler.”

 

[Lizard7709]

You are correct. I’ve been reading too much way too late at night. I don’t like that they drilled through the bar. From my understanding, the plans show parts of the pool deck that have #4 and parts with #5 at the planters and column areas.

Reading the notes on the repair drawing they have a section that shows they are supposed to take steps to prevent from drilling through bar like that in the “core drilling” notes. I’m not seeing this note in the 2020 document, but since it’s a memo it might not be displaying all the pages.

Reading what Murph said above about the concrete having a reduced strength, I feel that may explain the sudden nature of the failure. Although it’s too early to know if that was the cause of the failure. I am genuinely curious about the foundation and what there is to learn about it’s condition.

 

[dik]

Don't read too much into this... because of the alkalai concrete, some oil base coatings don't fare well with concrete... I also see this in painting HDG material sometimes... there is a saponification going on sometimes.

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

-Dik

 

[dik]

A new report...

https://www.cnn.com/videos/us/2021/...ebof-vpx.cnn/video/playlists/top-news-videos/

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

-Dik