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Miami Beach, Champlain Towers South apartment building collapse, Part 06 131

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SFCharlie

SFCharlie

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Apr 27, 2018
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Possible initiating event to look at.
Failure starting at the pool slab construction joint after 40 years of failed waterproofing - corrosive chlorides concentrated through a pathway directly to top layer of reinforcement (that were under tension) corroding each of the rebars until the slab finally failed... starting the cascade of the events leading to the complete collapse of part of the building.
TOP layer of reinforcement appear to be closely sheared off along this construction joint.
.
Capture_jnlxj6.jpg
 
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Has anyone noticed in this YouTube video that the column in front of the camera, and the column line further from the camera, are not aligned?

20210715_column_misalignment_tuhlbb.png


Is this shown on the plans? I don't recall seeing a grid misalignment like this, but maybe I missed it. If so, any idea why it would be misaligned?
 
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Agreed, that construction joint looks bad. It looks to me like the top reinforcement was terminated at the joint. There are possibly bottom bars, which look they were laying on the form work and not chaired up. No dowels, construction joint was not roughened. I saw a picture of the lobby deck at the south wall and it looked poorly constructed as well.
 
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tmwaits1 (Structural) said:
Below is a comparison between the north bldg columns and the south building along with views down the respective ramps.
Click to expand...

That shows that the ability to see even the base of the far perimeter wall from the street from a standing position is questionable (blocked by beam) assuming the fallen deck is not also in the way. I was wondering if the people that took the video were sitting by their pool and lower and have a deeper view. I am not confident the back wall is what people see when they talk about the tictok image. I have seen several references to it.
 
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GPR tech - there seems to be a lot of reinforcement missing from that joint. In addition to top and bottom reinforcement, there was also supposed to be a #4 dowel at every 2 feet, right in the middle. Can't see any of it in the photo. This does seem to be good evidence of deficient construction (not conforming to plans or best practices). May be more of that to come based on the field investigations.

Capture9_e8fmcv.png
 
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tmwaits1, the north building isn't quite identical in that area btw. If you watch the north and south tour videos, they seem to show a different layout for the beams and the step down to the pool deck.

Tropmet, it is definitely not too large to be a planter.. also, no column exists in that location, but a planter probably does. You might want to review old posts, since this was already discussed to death and I drew in the column locations using perspective based on both ratios and the north building and they both lined up at the same spot. It's probably around part 4 or 5.

clouditguy, correcting the technical information about the camera seems a bit pointless, but I highly doubt this camera was sending two RTSP streams. I've never heard of any company doing that, and it would only make it more troublesome for the app to try and sync the data as it would have no real data on when it was sent, only when it was received.. so you'd then be stuck fixing your videos manually. This camera is pretty dumb and I'm confident it was only sending one stream.. but it is possible for it to only send video or audio down that one stream if the other part isn't available. The delay would still be about 100ms regardless of how many streams it's sending anyways. If the other end is in Florida it could even be substantially quicker.. that's more of an average going across the continental US. Keep in mind too.. this isn't 1080p or higher. It's 720 and 8.5 fps.. that isn't much video to send really. The total size of the original video from twitter is only 816k. If this wasn't how video worked, you'd be able to feel the delay in your video calls.

The user said it as recorded at 1:22am, so it happened within a minute of the building collapsing.. and after the tiktok videos were taken. If the 911 calls are a good judge of exactly when the building collapsed (the last one I posted of the 45 min transcript gives the seconds of when someone called at 1:21 and you can hear it collapse), it was right at 1:22am. But yea.. I don't see the point in discussing this one that much really, how I synced them up is off by a second at most.

I think it's really odd people can't see the camera slide to the right too.. maybe you guys are viewing it on your phones?
 
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jbourne8 (Computer) said:
I drew in the column locations using perspective based on both ratios and the north building.....
Click to expand...

I can't recall this being done in the vertical plane. Maybe I missed it. I have see a 2d view from above that projects a view projected onto the floor plan. The problem is knowing the height of the camera.
 
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Promise this is my last "ring" vid post. Just watched jbourne8's enhanced video. I got a sense of side to side shaking (like an earthquake) instead of leaning one way or the other. The other thing that came to mind is if you're in a train or subway, you can see the cars in front of you moving left or right before the movement gets to you. I tried to line up the the left corner wall at seconds 7, 11, and 12 in the video - and at least based on this exercise there appeared side to side movement

Capture11_siqv4d.png
 
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Tmwaits1,

I see the difference. Those 12x16 columns are rotated 90 degrees. To be honest, if a car hits a 16 inch column its going to be much stronger then a 12 inch column.

The columns in south should have been rotated like North. They would clearly have been stronger in this direction. Perhaps they learnt their lesson after south?

I think its a clear design error to have those columns rotated in that way. Once you see it, you can't unsee it too. Why?
 
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jbourne8 (Computer) said:
Wow, a different building in Florida had a roof collapse today
Click to expand...

Interesting coincidence.... or this is Miami-Dade? Pretty soon they won't be able to find enough engineers to keep up with emergency inspections. Lots of hysteria.
 
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Noticed something today I did not notice before, in the Ring video from 711 the particles/drywall dust fall from the ceiling from left to right (from column line K to column line L) - after the slab/column along grid line K initially fails. We do not know how much longer after the video ends the main collapse occurred as the video would end with electricity or data loss - the camera slides to the left at the very end of the video. To me, this appears as if the exterior facade slowly peeled away, I believe this was the same crack moving across the ceiling 611 saw (before deciding to run for her life.)

-W
 
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Jbourne8 said:
Someone posted the ring video on youtube and enhanced the audio yesterday.. kind of interesting -
Click to expand...
A LOT of audio signal is lost in that video. It's been made louder, but not enhanced. The original video posted on twitter has the best audio quality compared to all of the reposted.


Has anyone been able to find any post collapse images of the north side of the 8701 property?


Precision guess work based on information provided by those of questionable knowledge
 
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Demented (Industrial) said:
Has anyone been able to find any post collapse images of the north side of the 8701 property?
Click to expand...
What are we looking for? Damage to 8701 was limited to dust and light debris. Palm trees shielded view of lower collapsing floors. Drone pic day of collapse:
download.aspx
 
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Demented said:
I'm assuming based off of dimensional call-outs for 3'6" and 48" of piles, the 2'2" slab elevation for the parking/basement level, 4" pile to cap recess, and 32" pile cap height.

The simple fact that depths of the piles are called out makes no sense to me.
Click to expand...

T.O. Basement Slab (8”) : +2’10

T.O. Concrete Framing Basement: +2’2

T.O. Footing: -2’2

B.O. Footing: = Depth of Pile Cap

T.O. Pile: = B.O Footing +4”

B.O. Pile : As required








 
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