Miami Beach, Champlain Towers South apartment building collapse, Part 07 90

[Seppe]

Continue...


Previous thread (Part 06)
[link ]

https://www.eng-tips.com/viewthread.cfm?qid=485223

[/url]

 

[Colostruct]

I haven't seen any photos, yet, that show that widespread deterioration of the reinforcing in the deck was occurring. As I have mentioned before, reinforcing "bleeds" like crazy when it is injured. Was someone cleaning up the stains on columns? Was RUSTY water reported to be dripping on cars? Where are the stains on the basement slab?

I continue to wonder if there were serious deficiencies in this construction. We have what appears to be some variations in what we see on our limited photos and what the plans indicated including...a beam at the initial failure zone that is not cast into the slab, beam frames that dropped intact without ties to the slab, missing top reinforcing over columns, apparent horizontal construction joints in structural slab, poor concrete cover, waterproofing failure. That's just what I see from limited photos.

My theory is that the recertification engineer and the remediation construction company walked into a ticking time bomb and had no idea of the extent of the structural deficiencies. Anyone show up late to a game of Jenga? How could one predict that a localized slab deterioration would telegraph into the adjacent building and bring it down?

 

[davefitz]

It seems that there has been a tremendous amount of technological improvement to the process of applying concrete to the fabrication of a building's structural elements since the date of this buildings construction ( 1980). Recently minted engineers might not be aware that there was not available in 1980 super-plasticizers, low cost finite element analysis software, galvanized or epoxy coated rebar,fine pozzolans for reduced permiability, or laser based measurement devices. The NIST analysis of this building's demise ( and the review of all other 30+ yo buildings) will need to keep in mind the level of technology used at that time, and it would not be surprising to find that the actual concrete properties do not meet the design specs due to the likely use of a higher water to cement ratio .

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick

 

[NOLAscience]

The NIST analysis of this building's demise ( and the review of all other 30+ yo buildings) will need to keep in mind the level of technology used at that time

So do we condemn and demolish all of the circa-1980s buildings on the beach in Florida, Alabama, Mississippi, south Texas (and other places)?

This building had at least one design flaw (the "beam" at the change in slab elevation and the lack of isolation of the pool deck and the main building).

 

[spsalso]

The design specs weren't met because of "higher water to cement ratio"?

And THAT'S supposed to be OK?

Of course, the PE and/or architect on the job would be consulted. And he presumably would have approved.



spsalso

 

[dik]

...bad for corrosion resistance.

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

-Dik

 

[spsalso]

Champlain South and the municipal garage in Coral Gables both appear to be/have been short on rebar.

Breiterman inspected and certified both buildings.

I would think that a good place to start inspecting is all the other building Breiterman inspected and certified. Not just buildings older than 40 years, but ALL of them.


spsalso

 

[NOLAscience]

Very common practice here.

Where is "here" (in general terms)?

 

[jayrod12]

Of course, the PE and/or architect on the job would be consulted. And he presumably would have approved.

You'd think so, but you'd be unfortunately surprised at how often water gets added to the truck after the testing even takes place.

There was one time they didn't even wait for the concrete testing crew to leave, so the report I received had notes that although the strength characteristics of the tested concrete were within specifications, water was added to the truck AFTER the test cylinders were cast.

Needless to say, a few angry phone calls were had that day, because I didn't receive the report until 7 days after the pour. So not only did I rip the contractor a new one, but I also gave the testing company a piece of my mind for not calling me the second they saw that happen.

 

[tmwaits1]

I couldn't agree more. Reinforcement that is corroding inside of a concrete slab or beam results in heavy staining, cracking, and spalling of the concrete due to expansion of the rusted rebar. This is incredibly common in Florida and especially with coastal bridges and buildings and is typically visible from a mile away. The video of the sub-level parking walkaraound just doesn't show any of that in the critical area. In fact the only place you see that is next to the pool which stayed up throughout the collapse.

 

[MaudSTL]

Reinforcement that is corroding inside of a concrete slab or beam results in heavy staining…

Raysa Rodriguez (907) took a video in the garage to accompany her 2018 class-action lawsuit. It shows water stains that appear to be rusty.

Link to article containing video

 

[Roga50]

So do we condemn and demolish all of the circa-1980s buildings on the beach in Florida, Alabama, Mississippi, south Texas (and other places)?

It may (partially) come to that. Insurance companies are going to have a lot to say about it. If nobody will put policies on a building, it realistically will become a demolition project. There is already talk that a lot of insurance companies down here are watching this VERY closely.

 

[gonefishing2]

There is a reason for all the polycarbonate panels at the garage ceilings...........Perhaps rust diversion was one, after Association paid for car repaints, and of course you need to clean up rust stains for perspective buyers.

I assume Florida is a Buyer Beware State?

Lots more core sampling is coming to Florida.......

 

[Red Corona]

> @Colostruct - As I have mentioned before, reinforcing "bleeds" like crazy when it is injured. Was someone cleaning up the stains on columns? Was RUSTY water reported to be dripping on cars? Where are the stains on the basement slab?

Have we seen any photos of the top rebar of the pool slab? The water infiltration theories relate to rebar that's well hidden and wouldn't be visible from beneath.

Though I do agree that most of the rebar we have been able to see has looked relatively unrusted. There doesn't seem to be as much in the real building as in the specs in places, but that's a different question.

 

[Aapob]

Is it possible that those columns were cast too tall for the lowered pool slab?

 

[gonefishing2]

From the photos I have seen of the rebar in the patio deck, they actually look to be in good shape. I noticed the patio deck columns had what looks like some sort of coated rebar in them. Thus could it be the rusting was not that bad in the slab as a whole, but rather it was just the layered pour that was the big issue?

Edit would not take as much rusting to delaminate a layered top pour with rebar only 3/4" down

The top of the enlarged areas of pool gutter system, that looked so bad in photos, was actually a maintenance rework according to the surfside permit documents, and not original. They poured on top of cut off walls, it appeared.

Link:

https://uc3f9146c21b4c345522c07de6f...zGQgSVwEfBPX9-pprqoZT44E2unCl1LzM9-j06zU/file

https://www.miamiherald.com/news/local/community/miami-dade/miami-beach/article252750773.html

 

[Demented]

@Aapop,
Long by just enough for someone to have dropped a tape from the top of the form and forget a very important dimensions?

Unlikely, but not impossible.

Precision guess work based on information provided by those of questionable knowledge

 

[MaudSTL]

In the 1995 to 2000 time span, apparently the major water issue was saltwater from below instead of fresh water from above. William Espinosa, who was maintenance manager during that period, said,

“I remember having some exposed rebar all the time,” Espinosa said. “They would come in, plaster it up with cement and then it would reappear in other spots. But nothing like a real big, big crack or anything like that. My biggest issue, which was it was just the water. The amount of water would come in there. It was all saltwater,” he said. “It was coming from the ocean.”

Skipping ahead 20 years, the 2020 garage video and the 2018 MC evaluation both show many examples of epoxy ports in the garage ceiling, which were then painted over or hidden behind plastic water diversion shields. Gabe Nir told the WaPo, “There was the water that pooled in the parking garage after rain, he said, and the uneven pool-deck pavement. Sometimes when he stepped on it, water would seep through the cracks.”

Could the epoxy injected into the most distressed parts of the slab have helped accelerate the delamination of the layer containing the top rebar?

 

[bones206]

Some recent research findings on a punching/delamination slab failure mode:

https://www.structuremag.org/?p=11552.

I wasn't previously aware of this mechanism.

 

[gonefishing2]

@MaudSTL,

That testimony is pointing clearly to a floating concrete canoe, on a larger scale than the ones engineered by engineering students in my college dark ages.

 

[MaudSTL]

The garage was being attacked both from above and below. The deck slab was under constant assault by rainwater and salt spray. The garage slab was under constant assault by saltwater intrusion and tidal pressures. The subsidence that occurred between 1993 and 1999 could not have helped. The garage video shows a long crack in the floor, and large area that appears to have been patched at some point.