Miami Beach, Champlain Towers South apartment building collapse, Part 15 32

[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
Miami Beach, Champlain Towers South apartment building collapse, Part 12
Miami Beach, Champlain Towers South apartment building collapse, Part 13
Miami Beach, Champlain Towers South apartment building collapse, Part 14

SF Charlie
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[MaudSTL]

I am not sure why this story is being detailed now. However, USA Today has published a long piece about the effort to save Valeria Barth (204.) Here is an archived version of Surfside rescuers heard her voice, tried for hours to save her. Then officials buried her story. The Timeline has included the basic facts of Valeria’s survival and the failure of her rescue since July, so there will be no Timeline updates based on this piece.

>>>>>Edit: Because of its helpful graphics, I added the link to the archive to the Timeline on Row 63.

 

[AutisticBez]

My question is, who owns the pathway? It's technically owned by 87 park right? So, they did work that left part of the wall vulnerable to water intrusion?

As for the gravel, wouldn't this automatically be the lowest point because water can sink into the gravel? The lowest point would be under the gravel at the waterproofing? If it had waterproofing.

I think there is a good chance the failure started at the south wall. Water intrusion at the wall could definitely have gotten into the rebar.

As per NV5, I guess this might be introduced as evidence. But still, they never bother to inspect the wall? Check for damage? It's also very possible to have damaged the wall during works.

This is also perhaps the only possible target of a lawsuit to get back any money.

 

[TheGreenLama]

I was following the Herald's approach laid out in their article up until I read this:

"While inspection reports indicated that the pool deck had suffered potentially debilitating water intrusion, concrete degradation was not factored into the model. The concrete was modeled at full design strength."

I can see why they approached the problem this way. They don't have access to the site materials. They'll get some useful baseline numbers from their analysis. But in the end all their work will likely have to rerun. Their analysis focuses entirely on the rebars (missing or degraded) as being the sole source of the failure. I believe this is a flawed approach.

 

[MaudSTL]

@TheGreenLama, another major flaw is that the model is based on approved plans rather than as-built, because of course they also had no access to as-built plans or the ability to prove/disprove structural flaws such as the failure to resupport the step between the parking and pool decks that Jinal Doshi discovered, etc.

 

[Sym P. le]

I'm not sure that I follow the heralds train of thought. Their edge conditions either lead to or start with a 1.5 inch downward deflection of the south edge of the slab. That would be to say that the continually supported south edge is weaker than the thinly supported column connections. I also struggle with the concept of the south edge slab rebar shearing.

 

[AutisticBez]

It may not be entirely possible to know if the failure started at the south wall, but I think it's worth considering. And maybe they know more about this then the public. But question, if they knew there was a problem at the south wall, why didn't they do anything about it?

Here is something else, the original street would have had drainage. This is something the path didn't have.

 

[Jeff Ostroff]

The pool deck failure has 4 main possibilities that I see:

1) It could have started at the south wall from weak connections and propagated north toward the building.

2) I tend to lean toward the idea that it started at the building and propagated south toward the wall. Ground zero would be the planters outside the Nir's condo Unit #111, because that is where most of the previous damage and repairs and issues were reported, the palm trees were there, root balls poking through drainage pipes, overweight planters, etc.

3) Others have proposed that the fact that there was a beam in the design that was removed over near the covered above-ground parking, that the collapse could have started there by the above-ground parking and propagated in all directions.


4) Then finally is the other theory that it started up against the shear wall/gym area due to the weak attachment of the pool deck slab to the shear walls.

One thing most of us agree on is that based on load calculations and the theory that this pool deck was near 100% load as-built, combined with weakened and degraded concrete no longer rated at the as-designed PSI, this was one large punching shear waiting to happen. So no matter where the pool deck failure started from and propagated to the other ends, all it took was one spot for it to separate, and once you have that, the slab design meant to add support to the structure became its Achilles tendon, actually dragging the rest of the pool deck down with it in whatever direction it propagated in.

 

[Keith_1]

Demented, stated that "Steel sheet pile walls have a life expectancy of what, 40 years in a highly corrosive environment before they're at 10% uncorroded mass?"

My response is as long as the concrete "retainment walls" cure who cares what happens to the sheet piles because they are basically designed for zero compressive load. Sheet walls are nothing more than a means to an end, be it to excavate for the purpose of forming and pouring caps, grade beams ,under-grade slabs or whatever else. When you can dig to the water table with a hand shovel, there is no other choice than to put in sheet walls, drill a few point wells, and dewater. Trust me, on the beach it is like I said, "a kid trying to build a sand-castle on the beach.

You as dangerous as the people that are responsible for the loss of so many lives. This building failed due to a complete, and in my opinion negligent failure to maintain the membrane.

 

[Demented]

Sheet piles are also used to stop/slow/divert the flow of underground tide water down here. One of main reasons we drive them (and leave them with a 30 year inspection) and have been in newer ocean front/water crossing construction, especially in certain tidal and reclaimed areas and those that have been subject to massive land erosion.
Heavy hot dip galvanizing with tar coating is awesome for keeping that water out for a long long time, but not many people do that.

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

 

[Keith_1]

Demented,

In this area there is absolutely no bedrock, it simply does not exist. In this coastal area there is absolutely Zero reclaimed land. What we do have is extremely course sand, hence friction piles are par for the course.

The water table is at best 7 feet below grade, if you attempt to excavate 20 -25 feet as in this structure it would be physically impossible to do the excavation without sheet piles and dewatering. I'am trying to tell you that this is a practical construction method and not a structural design issue.

Like I said you are dangerous

 

[Keith_1]

Demented,b

Wellpoints and multiple 300hp pumps, with containment booms / sheets for environmental containment are simply what it takes to do the job. There is alot of water that you have to get rid of to do anything below grade in SE costal Florida. There is a really good reason that homes do not have basements in the area, and that there a very few undergrade structures in the area. I do know of one attempt for a multi-story underground parling ~*50ft currently under construction, and it is a 18 month, 20+ million cluster f@#k.

 

[Keith_1]

Jeff Ostroff (Electrical)14 Dec 21 16:37
The pool deck failure has 4 main possibilities that I see:

[highlight #729FCF]1) It could have started at the south wall from weak connections and propagated north toward the building.
[/highlight]

The "wall" is not a compressive member, it is strictly a retainment element, the load is on the piles

[highlight #729FCF]2) I tend to lean toward the idea that it started at the building and propagated south toward the wall. Ground zero would be the planters outside the Nir's condo Unit #111, because that is where most of the previous damage and repairs and issues were reported, the palm trees were there, root balls poking through drainage pipes, overweight planters, etc.[/highlight]

The planters, the grass, the pavers, all set on top of a piece of concrete, the membrane between each of those elements led to the observed spalling, and the eventual failure of the beams. A building that losses the trasfer points of load will fall down. The only failure point is the membrane.
[highlight #729FCF]
[highlight #729FCF]3) Others have proposed that the fact that there was a beam in the design that was removed over near the covered above-ground parking, that the collapse could have started there by the above-ground parking and propagated in all directions.[/highlight]

Who really cares, one single point of weakness is not an issue, especially when the load was successfully transferred for 40 years


[/highlight][highlight #729FCF][/highlight]
4) Then finally is the other theory that it started up against the shear wall/gym area due to the weak attachment of the pool deck slab to the shear walls.

Simply confuse

 

[Demented]

Keith, you clearly have no idea what I'm talking about.
I know what piles are, what sheet piles are, and what they're used for. I don't think anywhere I said they're a bad or unpractical idea. Unpractical to service if their use is also to block waterflow from the lower foundation and piles, but that's the only drawback. Most buildings are knocked down and rebuild before anything ever becomes an issue though on the projects I've been involved with that required them for that use on the shore. I've only once see a property drive new sheet piles, but this was after some pretty bad land erosion and signs of settlement closest to the shore after a hurricane, as well as on a manmade island. We have lots of those artificial islands; not sure how you can say we have no reclaimed land here.
When water starts to flow through and erode the sand around the PIF, pre-cast, steel casing, sheet, H, or composite miles, you start to lose your friction. On a building with documented settlement with horrid pile plans with pile changes after ground breaking, it's hard not to consider issues with the piles, especially when we know water is easily flowing under the property.

"This building failed due to a complete, and in my opinion negligent failure to maintain the membrane."
I'm curious who you blame for the failure to maintain the membrane.

 

[Keith_1]

The sad thing is I don't think yuu know what a membrane is?

 

[Demented]

A barrier. In the context in which you're referring, the waterproofing membrane on/in the deck and exterior of the building if you consider the latex exterior a membrane. The one that was repaired/replaced 2 or 3 times. Curious who you blame for the lack of maintenance. I know who I see fault in with the membrane. Go on now. Mr. Dangerous wants to know.

 

[Optical98]

Lool...*waits for the name change*

Wth is he on about?...

Jeff Ostroff

I'd go with #4 being the closest IF their scenario has any merit, their model is lacking many factors.

 

[MaudSTL]

Here’s an archived version of the Miami Herald’s Grand jury: After Surfside collapse, require frequent inspections, stricter association rules.

 

[Keith_1]

Ok, this a pointless conversation. Gooday

 

[dik]

Just off the press...

https://miamisao.com/wp-content/uploads/2021/12/GRAND-JURY_202112151434-1.pdf

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

-Dik

 

[Demented]

About time they recommend structural guys do the structural inspections and the sparkys do the electrical stuff, not just any PE, and want to punish those who lie on inspection reports.

"36. We recommend that DBPR amend its practice and stop the dismissal of complaints which contain both criminal violations and regulatory violations."
That'll be a cold day in hell.


There was a meeting yesterday regarding a motion for the Town of Surfside to be an inspecting party allowed to store debris and perform invasive/destructive testing.

https://ctsreceivership.com/wp-content/uploads/2021/12/Notice-Of-Hearing.pdf

"19. The Court has recognized the Town as a potential defendant and as an interested governmental agency, and has treated it as such with respect to site access."