Miami Beach, Champlain Towers South apartment building collapse, Part 05 111

[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


SF Charlie
Eng-Tips.com Forum Policies

 

[gonefishing2]

Parapet is now in basement at same level as fallen patio, or same elevation as near base of punch sheared column. Does not have to be below to set up resonant frequency in patio deck, in my mind......

 

[gonefishing2]

warrenslo where are you???

 

[1503-44]

I certainly cannot discount that possibility. I think it dissapearance is still unexplained. It has not really been explained away either, as far as I know.

 

[MaudSTL]

Yes, 1211. The apartment directly below the section of the penthouse suspected of having a roof collapse.

You may wish to make a correction to avoid future confusion. Elena Blasser and her mother lived in PH 11. Link

 

[gonefishing2]

Of course the pile driving next door, and the effects of the Navy 3.9 explosion, as detected in Miami, all could have been contributing factors along with father time.

 

[gonefishing2]

https://blogs.agu.org/tremblingearth/2011/05/05/swaying-high-rises-and-resonance-frequencies/

Video link above showing high rise movement after 7.9 after shock for visual explanation.

 

[Demented]

If columns can punch shear this patio deck, why the hell can't falling parapet or cantilever do punch shear from 13 stories up???

It most certainly can.

Interesting question, only because I have witnessed a kid in Miami on a job jump off the 6th floor thinking he could special forces swing into the floor below. He was instructed to drop to the floor below by his supervisor, so he did. Thankfully fall harnesses work, but the labor force in Miami is very suspect.

Could there have been a bag of roofing tools and/or rolls tied off to the new anchor points and hung off the side of the building?

Total speculation.

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

 

[Nukeman948]

On Floor 2, all three phases were distributed approximately equally, from a 3 phase 600A 208V sub-main breaker on that floor (this is where individual meters were). That is, 1/3 got phase A 208V, 1/3 got phase B 208V, and 1/3 got phase C 208V. Of course, the 120V went along for the ride.

Perhaps I am being pedantic here but you need two phases and a neutral for each apartment to have 208/120v. Such as 1/3 get A phase, B phase and neutral, 1/3 get B phase, C phase and neutral and 1/3 get C phase, A phase and neutral.

 

[gonefishing2]

[/It most certainly can.

Interesting question, only because I have witnessed a kid in Miami on a job jump off the 6th floor thinking he could special forces swing into the floor below. He was instructed to drop to the floor below by his supervisor, so he did. Thankfully fall harnesses work, but the labor force in Miami is very suspect.

Could there have been a bag of roofing tools and/or rolls tied off to the new anchor points and hung off the side of the building?]

Definitely Plausible with suspect work force..........So the green bundle of roll roofing could have been say the 2500 lb test rig, and tied to roof anchor with rope across top of parapet to really load those cantilevers well?

 

[Demented]

Somehow this planter at ground zero of the collapse manages to remain mostly intact and not be covered in debris. I think it corroborates a slower settlement of the pool deck right in front of the initial building collapse area, and speaks to the completely vertical fall of this portion of the building. It fell completely within its footprint while the portion to the east fell towards the southwest.

To my tired eyes, that portion looks exactly like the view I believe we see from thr tiktok video, and why we do not see particular columns, beams, or fully discernable items from the location other than fallen rock looking structure, draining water pouring in from a similar flow path, and hanging debris.

*shrugs*

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

 

[CE3527]

The green covering could still be seen on the post collapse photos on the un-collapsed portion.

 

[gonefishing2]

CE3527,

Good catch, and there always is the possibility that the first collapse was a roof area above a condo with the green bundle sitting on top So the power flashes could have been an internal failure of roof slab we were seeing before the later events.

But it appears that bundle was sitting near if not on cantilever of 12th floor roof, and you can see where the flying buttress wall for the penthouse crashed down on the potential green bundle in that area

 

[spsalso]

Perhaps I am being pedantic here but you need two phases and a neutral for each apartment to have 208/120v. Such as 1/3 get A phase, B phase and neutral, 1/3 get B phase, C phase and neutral and 1/3 get C phase, A phase and neutral.

Perhaps. But the power to each unit is called single phase.

Interestingly there has been two phase electricity, also. But since you need 4 wires to run two phase but only 3 wires to run 3 phase, I doubt it's in much use anywhere.


spsalso

 

[gonefishing2]

And we know it was flat slab above condo picture sliding door windows, therefore no beam under where that green plastic is sitting other than of course the aluminum frame of the sliding glass door. So a bundle there is 'Suspect Labor' or “suspect Manager” error, or common place in American these days, unfortunately

 

[jbourne8]

I think the video was motion triggered.. because the original starts with a "no video" screen -

https://www.youtube.com/watch?v=K6ea90YGGBg

Also, they could have easily added another 10-20 seconds to this video and it still would have been small enough to email without having to do much work to it.

But how these get triggered is by percentage of movement.. so they won't pick up palm trees, etc, swinging in the breeze. They're meant to pick up movement of a person in the foreground, so anything smaller than about that size is unlikely to get caught. It probably triggered at this moment because the movement was finally big enough to look like a person. It seems like the trigger probably missed a second of the movement as it turned on too, which is why we see the roof already collapsing down when it first starts.

Also, PH-11 and 1211 are the same apartment btw. And the roof theory seems sort of unlikely because of how far that collapsed column is from the roof area. Something would have had to have fallen from the roof, moved over a few feet on the way down so it fell right above a column, and somehow damaged it so much that it's not easy to see in the tiktok video.

I'm also curious about Demented's question earlier:

Does anyone by chance know what the theoretical compressive strength of column M11.1 should have been in an ideal environment?

 

[gonefishing2]

My security cameras have sensitivity setting. They are at soffits of structure, and sensitivity is limiting range too. My front one sees street but is set to ignore that range and focus closer to front door area. However, significant movement at street could trigger them. Vertical motion downward would be more visible and much larger area of movement

 

[Nukeman948]

Perhaps. But the power to each unit is called single phase.

Interestingly there has been two phase electricity, also. But since you need 4 wires to run two phase but only 3 wires to run 3 phase, I doubt it's in much use anywhere.

You can call it single phase if you want, but you need three wires to get dual voltages. American homes have dual voltages as well and have two phase wires and a center taped neutral. That's how it's done and it is the same with three phase systems.

Two phase power is still in very limited use, mostly for old elevator service in old buildings in cities like Philadelphia. My 1932 code book has a diagram that shows how to wire a two phase 5 wire transformer. ( see also Scott-t transformer connections for 3 phase to two phase 5 wire).

 

[gonefishing2]

jbourne,

Things don’t just stop in their cold tracks where they land. There is multi-axis vectors involved, and of course bounce and roll effects. Drop a ball off roof and I bet it does not end up in same spot as it first impacted the ground.

 

[julootamu]

spsalso states "Interestingly there has been two phase electricity, also. But since you need 4 wires to run two phase but only 3 wires to run 3 phase, I doubt it's in much use anywhere."

There is 3 phase supply wiring to the building (Wye or delta) . No 2 phase in this building (Theoretically possible but surely not here in this century. You are right that 2 phase non-existant in USA today) Depending on internal wiring connection/ transformers supplies one phase loads in the building. Some three phase power distributions have 4 wires (neutral as well as three hot conductors). I worked for an electric utility. All loads in building condos likely 1 phase. Only large motors (3 to 5 hp and above would run directly on 3 phase power.

Lots of flxibility to the end user but in this size building the utility supplies a 3 phase service which can be made to supply single phase appliances.

Has little to do with the why the structure collapsed. Need a better video of collapse for starters. Otherwise will take months.

 

[Jedidad]

Hello,

Several days ago someone posted a link to a YouTube video by an architecture professor (in Argentina?) that was very well done. He posted an updated video yesterday and I haven't seen it linked or discussed here yet so I thought I'd post the link:

https://youtu.be/c-1wwF_STiY

I don't speak Spanish but I turned on closed captioning and in the Options I chose to auto-generate captions in English. I was able to get the gist of what he was saying.

I'm not a structural engineer, rather I'm a Cybersecurity Engineer, but I'm finding the discussions here fascinating.

Cheers,
Tony