Miami Beach, Champlain Towers South apartment building collapse, Part 03 148

[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

Thank you

SF Charlie
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[Roga50]

It's simple. Get those who have a conflict of interest out of making decisions on this demolition. From what we are seeing, all of those calling the shots stand to wind up in a court room as a defendant (or being a friend of those who are). Let uninvolved engineering parties call the shots. There is no harm in that. Why is this not being done.

Anyone who lives down here knows just how corrupt these government groups in Dade county are.

In a murder trial, you do not ask the defendant what evidence should be preserved.

Government officials are in a downright PANIC regarding this thing down here (unless you are here you may not see it). We also have tons of experience with storms like Elsa--it looks worse on the media than it actually is. Closing a building for inspection results from 7 months ago should be all the evidence you need... How many more are there? Was Champlain Towers one of them?

 

[warrenslo]

CNN just showed some video of work going on in the parking garage. Two columns each had at least a dozen large shoring devices in place around them. Also shown were two workers with what looked like surveying equipment.

See this is the problem, they need to weaken the columns from west to east to have the implosion take the building west. But the weakest damaged columns are on the eest. So once you take out the columns on the west all that's left is the middle of the building. At that point it's a real lottery if the building falls towards the west (preferred) or East. Furthermore taking the building west like they want will damage sewer and water lines within Collins. And finally, the asbestos cloud is an issue, are they going to wrap the building?!?

 

[warrenslo]

Those anchor points labeled P15, P16 and P17 are all on the cantilevered portion of the penthouse roof

P16 is on top of a column. P15 and P17 are between columns. See the column anchor on the left side of the penthouse (that anchor also could have been the failure point.)

Correction, P15 & P17 are also shown on top of columns, typically these are installed between columns, so this is odd.

 

[aggualaqisaaq]

“In a murder trial, you do not ask the defendant what evidence should be preserved.”

Right, but how do you know what has or hasn’t been preserved thus far?

It’s impossible to say one way or another because not every detail of an investigation like this immediately gets released into the public domain, especially if criminal charges may be involved down the line.

“Closing a building for inspection results from 7 months ago should be all the evidence you need”

This is certainly evidence of incompetence, bureaucratic dysfunction, negligence and possibly even a sign of corruption or undue influence of private interests on local government…but not necessarily of any kind of “cover up.”

 

[davefitz]

The root cause analysis study could have major implications on many ( most?) seaside condos in the US, and that implies there could be major economic / political pressure to place the blame on the isolated roof repairs, so as to limit the financial exposure of the many existing condos. It is constructive that NIST is now involved, and that may provide more credibility to the resulting report, as it implies that the only political adjustments to the report would be thru the specific reps and senators that oversee NIST.

It is hoped that one result of the tragedy would be to move the responsibility for large building inspections away from the local town and to the county. Local mayors and councilmen are a bit too responsive to the entreaties of the developer.

As of this time, the main surprise is how well the different govt agencies have responded in a complimentary manner- the system seems to work well when a polarizing political issue is not involved.

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

 

[SFCharlie]

The chance of them receiving 50 Knot winds is less than 10%, 34 knots less than 20%, and How is the danger to the heroic rescuers (Yes they are heroic!) any more from a 34 knot wind than a demolition (demolitions never go wrong).
(and if people can go in to set charges, why can't they bring living pets out?)

SF Charlie
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[Js5180]

BBC is reporting that an occupant on the 11th floor witnessed such a violent boom that the walls and chandelier were quaking, and a sound like a freight train rushing by:

https://www.bbc.com/news/world-us-canada-57690165

They said they looked LEFT down the hallway and saw the roof slanted in.

The only unit that someone leaving could look left at the damaged section would be unit 1104. The living room of 1104 appears to be intact.

The timing of when they left their unit isn’t clear, but the initial boom they describe sounds a lot more extreme than a slab falling in the garage, especially since they are on the opposite side of the building.

Their account is not inconsistent with a roof event as the initial boom.

 

[BlakeStr]

This building was 40 years old which is 14,600 days, but this collapse happened the day after a crane was loading roofing materials on the roof and the day after fall protection anchors were installed. The parapet detail Warrenslo posted has a 5'-6" cantilever, but when analyzed the moment hinge point should be center of support which is about 5'-10". The slab is only 6" thick and the reinf only #4@13" oc. Using structure dead loads plus 10 psf for roofing material and 30 psf for live load, the factored moment is 4.08 k-ft/ft and the factored capacity is only 3.99 k-ft, so assuming perfect conditions, this was a design error. Add rebar corrosion, which is likely under the hot wet roof, possible damage by the installation and testing of the epoxy bolts, and possible live load overload from roof materials or removed debris stockpiles, and it is highly possible that this cantilever slab failed first. The impact of falling concrete is the weight times the fall distance/deceleration distance. If the height is 120 feet = 1440 inches and the deceleration is 2", a 50 lbs piece of concrete imparts 50lbs x 720 = 36,000 lbs. 500 lbs = 360,000 lbs. Negating wind friction, for a 120' fall, the debris would be traveling 60 mph at impact.

 

[Roga50]

If they are declaring it is a recovery rather than rescue (which is what they really are saying, without saying), then they can pull the rescuers out, cordon off the area (just like it is now) and that building can sit there for MONTHS while a proper investigation takes place, with no real danger.

As for the surrounding condos, they should be evacuated, too, until we find out what went wrong. So no need to worry about danger there, either.

The real danger is they are afraid of what they'll find, I believe...

I'd rather see the NIST engineers get up there and say that THEY approve of the demolition. NOT Dade county and even Florida politicians.

 

[Js5180]

BlakeStr - how do we know there was a crane loading the roof? It isn’t present in the early pictures post-collapse.

Also - if the cantilever collapsed and most of it landed on the 12th floor roof - that’s a drop of 10 feet or so. How likely would the building initially survive that?

 

[Mark R]

As for the surrounding condos, they should be evacuated, too, until we find out what went wrong. So no need to worry about danger there, either.

Since you live in Florida I'm sure you'd be more than willing to pay the taxes to pay for the residence of all the other condominium complexes to stay in 1st class hotels for another year or 2 while the investigation is completed!

 

[BlakeStr]

The next of kin and the health department would want those bodies removed before decomposition. Properly imploding the still standing building will preserve the collapse site vs if the building is left to stand it is like;y to collapse onto the existing debris. The two engineers brought in, Musser Rutledge and KCE may already know the details and sequence of the collapse as they are privy to information that is not shared with the public.

 

[RickyTickyTavi]

the slab is only 6" thick and the reinf only #4@13" oc. Using structure dead loads plus 10 psf for roofing material and 30 psf for live load, the factored moment is 4.08 k-ft/ft and the factored capacity is only 3.99 k-ft, so assuming perfect conditions, this was a design error. Add rebar corrosion, which is likely under the hot wet roof, possible damage by the installation and testing of the epoxy bolts, and possible live load overload from roof materials or removed debris stockpiles, and it is highly possible that this cantilever slab failed first.

Minor clarification of the drawings might be needed, the steel was called out as #4@13. But the notes state that bars shown on the framing plan are top bars, in addition, unless noted otherwise. The top steel, which would be more pertinent to the bending moment for the cantilever was typically much higher is shown on the penthouse framing plan. The bars called out are top bars and would be in addition to the #4@13 call out. I think the steel for the cantilever is much a decent amount higher than #4@13

 

[BlakeStr]

JS5180, I read on this thread page 1 I believe, that a crane had been on site the day before the collapse. The question raised in that post was where had the crane sat? I apologize if in error, but based on the fall protection plan drawings, it looks like the roof is mostly encircled with cantilever slabs. Some of these slabs have balconies below, but the balconies are not continuous.

 

[Js5180]

Ricky - what about the PH roof?

A poster on Reddit has correct my account of the 11th floor occupants. They were in 1106. Which puts even more wall between them and the pool slab.

 

[Roga50]

Since you live in Florida I'm sure you'd be more than willing to pay the taxes to pay for the residence of all the other condominium complexes to stay in 1st class hotels for another year or 2 while the investigation is completed!

1st class hotels? Lol. They are housing the evacuees at the county fairgrounds... Probably in a tent city (not sure on the tent city, though, but I don't believe there are buildings at the fairgrounds).

 

[Js5180]

BlakeStr that would be a pretty big crane to reach over the cantilever sections, since surely they wouldn’t park it on the slab in front of x10/x11 (the only place without a cantilever).

I’m not disputing it - just trying to figure out where it would have been, and whether it’s still there. The roof does not appear to have any wheeled carts, so it’s a really interesting question - how the hell did everything get up there and to different spots?

 

[BlakeStr]

The notes posted by Warrenslo say 8" slab floors and roof, but the parapet detail shows a 6" slab. This may be why Morabito said to verify the slab thickness. Note 6 says for reinf at cantilever #4@13". If this was additional it should say additional.

 

[Mark R]

Quote:
Since you live in Florida I'm sure you'd be more than willing to pay the taxes to pay for the residence of all the other condominium complexes to stay in 1st class hotels for another year or 2 while the investigation is completed!

1st class hotels? Lol. They are housing the evacuees at the county fairgrounds... Probably in a tent city (not sure on the tent city, though, but I don't believe there are buildings at the fairgrounds).

That's one thing for a temporary relocation of the residence of the building that collapsed however it certainly something that would not be acceptable for residents of other buildings if you start effectuating all of them. I'm sure he wouldn't move from me million-dollar condominium to a tent because the government told you to.

 

[RickyTickyTavi]

Note number 3 says reinf shown is top bar.