Miami Beach, Champlain Towers South apartment building collapse, Part 08 20

[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

SF Charlie
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[gonefishing2]

I can now see why Surfside would be releasing the permitted work orders on file concerning Champlain South. It is a great way to build a defense of this was a developer/builder/engineer/architect/condo association/maintenance contractor issue, and not one Surfside could be responsible for.

 

[gonefishing2]

Demented, I am sure all the 'small' aggregate fits nicely in those 1/8” to 3/16" slots?

Edit: And I am sure we dado every foot or two?

 

[spsalso]

I suspect the statute of limitations of 10 years mentioned in this topic does not apply to criminal charges.


spsalso

 

[spsalso]

Sprinkler heads in Monterey:

https://www.latimes.com/archives/la-xpm-1986-03-20-mn-21571-story.html

I suppose he's out of jail by now. Wonder what he's up to.

Nope, never worked with the guy.


spsalso

 

[spsalso]

Interesting side note hear for Sparky's, is that the galvanized plumbing pipe was used for earth ground back in the day. When Galvanized under ground water pipe from street to house was replaced with PVC, very few folks were savvy enough to realize they just lost their earth ground......

And in lots of cases, the earth ground now followed the black iron gas line to earth ground. Guess what happens at corrugated flex connections to gas lines, during lightning storms??? If not properly grounded.

"Back in the day" there was no earth ground, as knob and tube was not a grounded system then.

Now, back in MY day the galvanized (or copper, as I have now) pipe coming to the house was ONE of the system grounds IF it was long enough and made of metal. There was also a ground rod. There was also a bond at the service to the incoming utility neutral which was almost always grounded "out there".

IF the water pipe ground no longer worked, and IF the ground rod connection failed, and IF the utility ground failed (yes, it happens), then you've lost your official ground(s). And fun and games can commence. Since "all metallic piping systems" must be bonded to the electrical ground system, a metal gas line would indeed be connected to that potentially ungrounded system. And quite possibly the water lines in the house would, too.

I fondly remembering working on a '70's house that had been replumbed. I found a short length of pipe where the original electrician had attached his water pipe ground clamp. The plumber hadn't moved the clamp to his new system. Just 4' of pipe under the house with a ground clamp.


spsalso

 

[Optical98]

Demented, we've contemplated where they may have stored the large tar kettle at night... someone earlier that he'd seen them stored inside condo garages even.

Could it be stored and locked behind this utility gate? And where does that lead to? Is it a room on the 1st floor or does it go into a garage storage area? On the plans it looks to be called a Transfer Vault? It doesn't make sense they'd have those gates at the end of the lobby hallway. The window in front of that truck is the Kitchen off of the Rec Room.

I think there was a fire in this area.

 

[gonefishing2]

With the invent of DC controlled AC motors, I have seen lots of houses built in the 1930’s to 1970’s or so, where primary meter base ground was inadequate and decayed. And main house ground was galvanized pipe. Back in the day, black iron pipe was nippled to device or copper flare tubing was last mile connect. But then came corrugated thin wall flex for last mile on gas appliances. I have repaired gas leaks in corrugated flex gas connections where the lightning energy burned a hole in flex gas line. Black pipe can handle surge. In our area, meter base requires two 8 foot ground rods, bonded together and black iron must be bonded to same meter ground so flex is protected.

Edit DC motor controllers are very sensitive to voltage change. 70 volt spike can kill controller.

PS 1930’s is not necessarily limiting range, just my typical experience range.

 

[Nukeman948]

Interesting side note hear for Sparky's, is that the galvanized plumbing pipe was used for earth ground back in the day. When Galvanized under ground water pipe from street to house was replaced with PVC, very few folks were savvy enough to realize they just lost their earth ground......

Driven grounding electrodes made of copper rods or galvanized pipe have been the primary grounding means for a very long time in dwelling units. It is required to bond to metal plumbing pipes and gas lines where available as a secondary grounding means. Local electrical inspector told me not to bother bonding to the gas line on the last house I did. Sometimes we do what the authority having jurisdiction wants even if we don't agree.

I have never seen PVC used for city water to house connections but I'm sure that method us used in some locations.

 

[gonefishing2]

1/32” tolerance.

 

[MarkBoB2]

SwinnyGG said:

It's also, in my opinion, VERY unlikely that this entire situation is going to be resolved because someone finds one little piece of bent rebar, or whatever. This failure, as far as we know today, was the result of systemic failures across the entire lifespan of the building from the initial design phase through construction, maintenance, and monitoring right up until the collapse.
In any event, I'm not sure what your intent is in continuing to belabor this point, but your posts appear to have a definite conspiratorial bent. I'm not sure why that is, but I think you're focusing on one tree rather than the forest.

Why do some engineers want to look at objects in photos? The answer is that a trigger for the collapse has not yet been found, and the engineers looking at photos believe that they can see what triggered the collapse. This does not imply a conspiracy on the part of these engineers. They are merely trying to help determine the cause of the collapse, just like the many structural engineers who believe they already know the cause of the collapse. In fact, one might wonder if there is a conspiracy on the part of some engineers to avoid considering any cause of the collapse that might place the blame on their specific profession’s responsibilities in the collapse.

If one cannot find a trigger for the collapse, then one can never know whether the true cause of the collapse has been found. This leaves the public with a very uneasy feeling about building security. For example, Morabito Consultants’ report warned that Champlain Tower South was structurally deficient, citing spalling with exposed rebar in the pool area, spalling on the balconies, spalling on the drive ramp, and water collection in the parking area and on the pool deck. Yet, the pool area still remains standing today without losing a drop of water after everything else has collapsed, the drive ramp has never collapsed on its own, no balcony has ever fallen on its own, and drains were put into the pool deck ten years ago. The water in the basement parking area was a real concern of all building residents, but it was never addressed how this problem would be fixed. Instead, a large part of the Morabito proposal was involved with non-structural improvements, like installing roof anchors, repairing stucco, repainting, replacing air conditioners, and improving planters at the building entrance. It almost seems to the public like the Morabito report was using mild structural problems as a way to scare the residents into paying a larger sum for what is essentially cosmetic repairs.

When the public hears about how structures are compromised by water causing spalling, they wonder why the Champlain Tower East hasn’t collapsed when spalling in one of its basement columns was far worse than the spalling seen on any column in the Champlain Tower South parking basement. When the public hears about how structures are compromised by water pooling in the basement garage, they wonder why the Marriott Inn Surfside hasn’t collapsed when it had several feet of water in its basement garage, yet the Champlain South building collapsed when it had only a few inches of water in its basement garage. Since these other buildings are still standing when their structural problems appear to be far worse than those of Champlain Tower South, the public gets an uneasy feeling about not only whether the true cause of the collapse has been found, but whether structural engineers truly understand why buildings collapse.

Somehow we must reassure the public that structural engineers know how to design buildings that do not collapse, that foundation engineers know how to control water intrusion into basements, that construction companies are held to rigid standards that avoid collapse, that inspectors are honest and knowledgeable about the building specifications, and that building maintenance personnel adhere to the original design specifications. One way to reassure the public that this process is being followed is to find the trigger for this building’s collapse. Another way is to strengthen regulations when they are insufficient. One thing that comes to mind is a regulation about certifying the building’s foundations relative to water ingress. Another might be to identify the person responsible for controlling roof loading during maintenance work, deck loading to prevent adding sand and paving tiles without removing the original tiles, and floor loading during condo unit improvements. Another regulation might be to demand x-raying when taking cores at regular intervals or when drilling into the cement structure to install objects like roof anchors to avoid damaging the rebar. Yet another regulation might be to inspect roofs and decks after a heavy rain to determine if water is removed promptly and thoroughly.

In summary, I would like to repeat the submissions of tmwaits1 and Colostruct above:

22 Jul 21 19:36
Quote (tmwaits1)
This is a good question to ask from the laypersons perspective so I will try and answer it based on my experience in design analysis and inspection of reinf conc structures for almost 30 years. The problem with a scenario where there is no trigger as you describe where the plaza deck has deteriorated and suddenly goes from stable to complete failure in less than about hour is this. Reinforced concrete almost never fails in this short of time without obvious signs of structural distress days, weeks months or years before the actual failure. In fact this is baked into the way reinforced concrete is designed such that failure is not brittle but gradual/ductile so that action can be taken prior to catastrophic collapse. Practically speaking, if there was no trigger then the slab should have shown more signs of deterioration like chunks of spalled concrete on the floor of the parking garage and heavy, noticeable cracking of the slab and beams well before the night of the collapse. The area where the failure occurred seems like a heavily trafficked, well lit part of the parking garage so you would think that problems in this area would have been noticed even by someone with zero knowledge of structures. I'm not saying it couldn't have collapsed without some trigger, nor that the slab wasn't underdesigned and deteriorated, but the evidence makes me lean more towards a trigger of some sort.

This is my experience also. I don't design large concrete structures of the type that failed. But, I have observed "failing" concrete decks and retaining walls where degradation of the reinforcing is causing distress.

I have also observed connection failure and can see that those failures can be sudden. In these cases the failures can be traced back to insufficient design or poor construction. They can reach a point of degradation or minor over load where failure can occur suddenly. This is not as common in concrete as it is in steel since the connections are commonly integral to the construction of the individual elements (beam and column reinforcing continuity). But, if this continuity is not provided in the design (such as grossly undersized reinforcing or inadequate development length of reinforcing) I see a potential for sudden failure.

BUT...This structure waited around until the rehab crew shows up and then falls down immediately. This is just too much of a coincidence to me. Something happened to trigger this event IMO.

 

[gonefishing2]

Spsalso, Aren’t the main panel neutrals and grounds connected, thus grounding of meter base grounds neutrals and later day ground wire. Even after knob and tube, I have lived in houses with only two wires to outlets, with no ground wire.

BTW, I have experienced first hand a ‘Floating Neutral’ while working on HVAC unit at condo complex. Wood frame condo’s. Between my earth grounded butt and my hands, I discovered I was least path of resistance. I explained floating neutral to customer and why he had to get Condo Association to fix, before I could fix his unit. I referred him to an Electrical buddy, who came out. Later after electrician fixed floater, customer told me, he thought I was blowing smoke up his ass talking about floating neutrals.

Edit: Customer told me it was a building transformer problem. My buddy told customer he saw so many code violations while testing for floating voltage, that he was never there. And immediately inform your condo association.

 

[Vance Wiley]

Not so far " back in the day " here - the power pole beside my driveway was smoking - from below the ground,
Power company was called - the next pole with transformer had lost its ground, there was a covered ground line attached to the smoking pole and heading below grade, and its connection was not secure.
So there is current thru grounding conductors.
I have always been a bit fascinated by the "earth ground" as a return to complete a circuit. How many amps of 450KV ( or something like that) are returning to a large generating plant? O M G we are electrocuting our only planet !! This is WALLY all over again. Disney predicted this !
And due to the resistance in the earth, heat is created in the ground and causing global warming ! So the seas rise and condos fall. I need to talk to the attorneys for the condo owners.

 

[zebraso]

I have always been a bit fascinated by the "earth ground" as a return to complete a circuit. How many amps of 450KV ( or something like that) are returning to a large generating plant?

The earth is an excellent conductor when you factor in the cross sectional area involved. Also given the formula for power the higher the voltage the lower the current if power is constant.

 

[gonefishing2]

Optical98, The service drive is directly behind the area you circled in green. Once in that area to the immediate right or corner location appears to be the electrical transformer vault feeding power to the building.... Not a Transfer Vault.

Edit: All of that is on first level, not garage level. I imagine the transformers are still filled with flammable liquids???

Quick Duck Duck Go yields this quote: "Liquid filled transformers can be filled with a variety of liquids with mineral oil being the most common choice for outdoor use, though oil filled transformers can be used indoors if enclosed in a vault."

Good old mineral oil has so many uses!!! Being phased out though in a lot of application like AC or HP compressor lubricants.....

 

[spsalso]

Spsalso, Aren’t the main panel neutrals and grounds connected, thus grounding of meter base grounds neutrals and later day ground wire. Even after knob and tube, I have lived in houses with only two wires to outlets, with no ground wire.

Yes, there is ONE point in a building where they are connected: at the service. This is also where the grounding electrode conductors (ground rod, water pipe) land. The gas lines can be bonded (bonded being slightly different than grounding) anywhere accessible, usually at the water heater.

Grounding in houses and other small buildings grew in interesting ways. I've seen both knob-and-tube and early romex with 18 ga bare copper wire strung separately and wrapped around a box mounting nail (Yuk!!). Also, for awhile, although the outlets were grounded, non-grounding receptacles were used. Things have definitely improved, though I'm NOT impressed with AFCI. At this time.

Speaking of knob-and-tube, the installation quality was generally far above most work these days. And the design was really quite elegant and reasonable. I generally suggest my customers leave it alone in places like bedrooms and hallways.

BTW, I have experienced first hand a ‘Floating Neutral’ while working on HVAC unit at condo complex. Wood frame condo’s. Between my earth grounded butt and my hands, I discovered I was least path of resistance. I explained floating neutral to customer and why he had to get Condo Association to fix, before I could fix his unit. I referred him to an Electrical buddy, who came out. Later after electrician fixed floater, customer told me, he thought I was blowing smoke up his ass talking about floating neutrals.

Some fun, eh? I've run into it once in an auto repair shop. They were getting all kinds of voltages that were NOT 120. Turns out their water pipe ground was not working (and being an old building, there was no other grounding electrode). But there was of course, more. The job of that water pipe ground was NOT to clamp the neutral to ground. It ALSO turns out that the utility had a bad ground for THEIR supplying neutral. First response was "It's not us; it's you." Further discussion convinced them to come out and fix their problem. And I secured the ground clamp. And billed my (happy) customer.


spsalso

 

[Optical98]

Thermopile,

And right below that area we see it partially dropped into the parking garage... and we can see the trash containers that were probably housed behind the service gates, ready to wheel out on collection days.

And large pipes that used to connect to the Generator room, seen broken.

 

[Murph 9000]

As-built it was almost certainly an oil filled / oil cooled transformer. On one of either the site or basement plans, there's a subterranean oil tank for it below / near the transformer vault. I could be wrong, but I think it's below the basement slab, and there was an access manhole somewhere outside the building.

The vent on the solid wall to the right (west) of the service entrance is for the transformer vault.

It is roughly where the stubborn post-collapse fire was. Transformer oil could have been fuel for that, but that's pure speculation.

 

[spsalso]

Not so far " back in the day " here - the power pole beside my driveway was smoking - from below the ground,
Power company was called - the next pole with transformer had lost its ground, there was a covered ground line attached to the smoking pole and heading below grade, and its connection was not secure.
So there is current thru grounding conductors.
I have always been a bit fascinated by the "earth ground" as a return to complete a circuit. How many amps of 450KV ( or something like that) are returning to a large generating plant? O M G we are electrocuting our only planet !! This is WALLY all over again. Disney predicted this !
And due to the resistance in the earth, heat is created in the ground and causing global warming ! So the seas rise and condos fall. I need to talk to the attorneys for the condo owners.

Yes, grounds are interesting. In theory, all the neutral return current in a house travels out through the overhead (or underground) neutral wire. BUT. That neutral wire is also connected to your water pipe and ground rod. There is NOTHING to stop happy little electrons from choosing that route to travel home.

My house had a galvanized steel "foundation cap" at ground level. Right near a ground rod and the water pipe clamp. And that galvanized steel gradually disappeared over the years in a radial pattern centered on those two items. It's been replaced with copper.

You wanna talk ground return? Consider electric railroad locomotives. They pick up from a single overhead wire, and return ONLY through the earth. 5000HP, 25,000V, 150A.

Yup, lotsa electrons going about their business.


spsalso

 

[zebraso]

Speaking of knob-and-tube, the installation quality was generally far above most work these days.

Yeah, I did not replace it for the ceiling light circuits (low amps) in my home and would have to rip out ceilings. For everything else yes because the power consumption these days for everything has gone up from the time K&T was in use. Plus the age of the wire is a factor. No problem with insurance depending on where you are and the usage. Not starting a discussion on that (hopefully).

Edit: oops wrong source for quote. Meant to quote spsalso (Electrical)

 

[Murph 9000]

And right below that area we see it partially dropped into the parking garage... and we can see the trash containers that were probably housed behind the service gates, ready to wheel out on collection days.

Yes, that's roughly at the inner end of the service corridor / dock. The surviving columns, where the slab has only dropped about a foot are D2 and D5. Hidden in the collapse, not far into it are E2 and E4 (E5 does not exist). If you catch the longer video showing firefighters drilling there, you can positively identify the location from the unusual double column on the left at the start of the video. That's A2 & B2, if memory serves.