Miami Beach, Champlain Towers South apartment building collapse, Part 09 139

[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

SF Charlie
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[MaudSTL]

Outstanding effort!

Thank you! I don't think we're going to get any new witness insights at this point, so I wanted to capture what we have been told all in one place and be done with it.

 

[12345abc6ttyui67]

Just a question on the repair of concrete. Again, not my area of expertise here.

When it comes to repair of existing (loaded) steel structures, a great deal of thought has to go into the sequencing and methodology of any repairs, due to the potential to 'lock stress in' to the structure. For example, if we removed a bracing member, any load which had been in the brace would be redistributed to the surrounding structure (assuming no temporary restraints are added to prevent this). Upon reinstallation of the brace, the brace load which had redistributed to the remaining structure doesn't magically make it's way back into the brace, the load remains 'locked in' to the surrounding structure. The brace only becomes 'active' again when the loads increase, or change direction etc.

When it comes to repair of concrete structures, I would presume the same applies? For instance, if some concrete was chipped out of a column for repair, the load in the column would redistribute into the remaining column cross section, and any subsequent repair would not be 'active' until the loads increased. For a predominantly gravity loaded column, could you end up in a situation where, after multiple concrete repairs, the concrete which hasn't been repaired becomes overstressed? I understand temporary shoring is often specified, although I believe that's more to maintain the load path while the repair is completed, although it will go some way to alleviating the issue (once the shoring is removed, the load is distributed over the repair + original concrete).

How much thought/concern is made over this for concrete structures?

 

[warrenslo]

I also see that threaded anchor ran out of depth of concrete it appears?

Those threaded anchors were from the roof anchor guys (Morabito's recommended friends/apparent family) and unpermitted.

shadessadI think we need to realize with MarkBoB2's calculation, that plastic Green and yellow handled bag is just the right 2500 lb static test load for a 5000 PSI rated OSHA roof anchor???

These OSHA anchors shouldn't even be required on old buildings - they screw up beams of new ones!

Also, why are there instructions for full depth slab repair included in the roof anchor permit? What roofer is going to be shoring, doing full depth replacement, and epoxy injection?

Morabito scam...

 

[Demented]

I have no doubt in my mind of a Morabito scam. That anchor work on the roof is suspect. Being on repaired columns and possibly a reaired beam, even more suspect.

Edit: I'm an idiot.
Wait, why did they use 12"x3/4" carbon steel Hit-Z's?

Also we know the upper floors had that lower spec concrete.

The epoxy injection machine was on the roof, for the anchors, unless they neglected to inject epoxy into the drilles holes. Although I do admit I have seen no evidence of repair work, I have seen evidence that the equipment, materials, plans, and ok for major concrete structural repair were on the roof the day before the collapse. That is a red flag. Even if it didn't cause or play into the collapse at all, the work surrounding them is best negligent and processes need to be in place to punish, not reward those who work in such ways.

@MaudSTL, excellent work.

These OSHA anchors shouldn't even be required on old buildings - they screw up beams of new ones!

Oh hell yeah they do.
They did just get to the location of the two repaired columns and repaired/replaced beam on the roof. Just cringy. Don't know where they put them in that location, but that roof slab has had a colorful past.

As much as I have asked around everyone from other crews I know, roofers I know, etc, everyone who was on the roof is tight lipped. And I mean a .501 bolt in a .499 hole tight.

I get the feeling we're going to find some wedge anchors used.

 

[Demented]

@Thermopile
Did they really hit rebar, or did someone oops in the ordering department? 'cause I don't see one of these in those anchor plates. "just gonna send it" - Larry Enticer

I straight up assumed 5/8" all-thread epoxy bolts were what was called out after seeing that is what was used (or possibly sheared off wedge anchors. It's "still" all thread).


"·EXISTING CONCRETE SHALL BEX-RAYED (OR GPR) TO
DETERMINE LOCATION OF EXISTING REINFORCING. NO
REINFORCEMENT SHALL BE DAMAGED DURING
INSTALLATION OF NEW PERMANENT ROOF ANCHORS "

 

[JStructsteel]

@ Thermopile....What was cut with a bolt cutter? These?

 

[Demented]

Cut or not cut, moot. It is clear as day they deviated from the plan. To my arc flashed eyes, they're just simply the incorrect anchors. The epoxy injected ones from Hilti, with the roll around epoxy injector that requires a compressed air source.

I'd snap pics of ours but its in the field.

 

[Demented]

I know my box weighs 2890lbs give or take 100lbs depending on what is in it, sitting on 4sq.in.



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

 

[MarkBoB2]

Can anyone tell me how a roofer would get tarpaper, anchors, and tools like sweepers down onto the roof of the middle section of the building below? The photo shows the penthouse roof highlighted in red. Surrounding the middle section of the 12th floor roof one floor below the penthouse roof is a 4 foot high parapet. I have not been able to find a door to this center section in any rooftop photos even though the drawings show a door in the upper left corner. But even if there is a door, roofers would need to get materials from the penthouse roof over this parapet and down to this area one floor below. It seems to me the only way to do this is by using a davit hoist. This means that a davit hoist was on the roof along with sufficient ballast weights to stabilize the hoist while raising one roll of tarpaper or a sweeper. Could this explain why two hexagonal-shaped weights were found on the debris pile close to column 27?

 

[rodface]

I have gone through the 1979 plan set and made my best effort to order the plans by sheet number.

*I have removed all North-building plans.
*I have split each set (AC,E,P etc.) into a separate PDF.
*There will usually be more than 1 of any given sheet; sometimes this is because 2 identical copies were scanned in, but sometimes there are changes indicating that revisions were made.
*I have attempted to arrange these multiples in chronological order but make no guarantees.
*I have added a PDF with the 4 sheets showing pocket park plans for both buildings for completeness' sake.
*About 133-135 of the sheets in the upload set were devoted to the North building. Nothing stood out as missing from the sets below but I have not checked exhaustively.
*Certain penthouse sheets do not have a legible title block and were excluded based on the shorter corridor suggesting that they belong to the North building.

I will edit this post to include all sets as I upload them. Upload complete. Main (architectural) plan set is split into two sets of 15 sheets to stay under upload limit:

8777_Arch (30 sht)_(shts 1-15)

8777_Arch_(30_sht)_(shts_16-30).pdf

8777_AC_(9_sht).pdf

8777_E_(11_sht).pdf

8777_FP_(3_sht).pdf

8777_New_PH_Addt_(6_sht).pdf

8777_New_PH_Addt_(9_sht).pdf

8777_P_(11_sht).pdf

8777_S_(14_sht).pdf

8777_SP_(3_sht).pdf

Pocket parks.pdf (plans for both buildings, 4 sheets)

 

[SFCharlie]

Lots of roofing work going on.....

Same image with more pixels
[sub]I see some digital artifacts that make me think there was some (small) amount of enhancement.[/sub]

 

[rodface]

@Thermopile cheers sir. Hope this helps others glean more information about the building and the history of changes with reduced likelihood of a) missing information from later drafts and b) confusion with North building.

Things that stood out to me while going through these:

*Penthouse set seems to have many more revisions. Lots of changes around the passageway/elevator area. I noticed the details for that concrete beam supporting the large AC unit (it's in either P or PH, I wasn't sure how to arrange those. There are sheets labeled "P" as well as "P-1").
*The changes to the pile cap drawings, S1 through S3, are striking. Notably I could not find a "final" copy of S1 (only the draft version "S1 of <blank>" is present). I believe someone more knowledgeable has raised this point in one of the older threads.
*The S set shows at least 2 distinct revisions.
*I often wonder about the story behind the distinctive fountain shown on ARCH-6. Victim of cost-cutting?

 

[pellucidar]

For your convenient reference, I compiled the significant witness events we know about into a spreadsheet with links. I wish I could interview some of them to gain more clarity.

Rows 5 & 6 seem to have the wrong times on them.

 

[rodface]

@SFCharlie

Here is the highest res I could find for that image, uploaded as attachment to preserve quality:

https://files.engineering.com/getfi...=a8884ded2b31eb8963acec1f7cda5452f6c7bd57.png

 

[Demented]

Sorry for phone potato, but would anyone like to talk about that 3.4 earthquake or what ever it was?

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

 

[rodface]

@MarkBoB2

Don't know the answer to your question but I wanted to point out that Bing Maps has true aerial views that provide more detail than Google's mushy 3D:

Don't know if this link will work:

Bing maps 8777 Collins

You can get here by searching for the address in Bing Maps and clicking the "bird's eye view". There is a compass at lower right that allows you to rotate the view around.

 

[Murph 9000]

I have not been able to find a door to this center section in any rooftop photos even though the drawings show a door in the upper left corner.

It is beneath the elevator machine room, according to the plans, so hidden from most external angles. Given that the machine room access stairs are on that section of roof, it's very unlikely that the door was omitted; far more likely it's just hidden from view by the machine room. The machine room has to be easily accessed by both mechanics and firefighters.

 

[Murph 9000]

Sorry for phone potato, but would anyone like to talk about that 3.4 earthquake or what ever it was?

It wasn't an earthquake, but equivalent to a 3.9 from explosives detonated on the surface beside a new carrier, to intentionally hit it with a high energy shock wave and see what falls off, bends, or breaks. Importantly, it wasn't on the earth's crust, so doesn't travel like a normal earthquake would.

It was only a 3.9-equivalent, which isn't all that big (it's a logarithmic scale). It was also 100 miles away. I'm not a seismologist or geologist, but I'm quite certain it could not have hit the tower with any significance. The inverse cube law and 100 miles should make it clear that the energy was gone by the time it reached the tower. It was reportedly 40,000 lbs, probably something like modern Torpex since it's the navy, probably up to about 150% of the power of TNT (taking a guess, WW-II Torpex was about 150%, H6 is about 135%).

 

[SFCharlie]

Here is the highest res I could find for that image, uploaded as attachment to preserve quality:

Thanks!

SF Charlie
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[MarkBoB2]

Thank you, rodface, for the link to Bing maps and for the instructions on how to get a "bird's eye" view. I had tried for weeks to find this, but gave up thinking one had to pay somehow.

And thank you, Thermopile, for the photos of a roof hoist. It doesn't make much difference to me what the hoist looks like. I am more interested in knowing whether one existed on the roof at the time, and whether it required hexagonally shaped weights for ballast. The weights found near column 27 were hexagonally-shaped and were on rods like the weights shown in the photo you posted. Thermopile, can you please repost the photo of the roof hoist with weights that you once showed, but then the removed?

By the way, also found near column 27 was an unmounted davit base that looks like an OSHA anchor, but has a hollow tube held up with three triangular flanges welded to the tube and the base. This may mean that the roofers had not yet installed the davit base, or that some other hoist design was used instead, such as the one you identified.