Miami Beach, Champlain Towers South apartment building collapse 151

[bugbus]

Partial collapse of 12 storey apartment building in Miami Beach:

https://www.google.com.au/amp/s/

http://www.dailymail.co.uk/news/art...-building-collapses-sparking-huge-search.html

Was built in 1981. Not much information as yet.

Building profile:

https://www.miamiresidence.com/surfside/champlain-towers.htm

 

[jrs87]

https://www.townofsurfsidefl.gov/do...intenance-anchor-system.pdf?sfvrsn=bc2a1194_2

 

[Mark R]

I've seen several posts referring to the changing of the rooftop HVAC. While that's very obvious in the photos that have been posted just because a new unit is larger doesn't mean it's heavier. In many cases newer HVAC equipment, as well as many other types of equipment, are much lighter these days because of new materials and "value engineering". It's certainly something that needs to be looked at but certainly isn't a smoking gun IMO.

 

[jrs87]

Something is not adding up. Pool deck and garage seem to not have been on the agenda. Roof and facade were.

https://news.sky.com/story/miami-bu...ching-for-answers-and-accountability-12342076

 

[WannabePESE]

The interior columns have over 500,000 pounds of dead load in them. Assuming a conservative safety factor of 1.2, while it wouldn't meet code, the columns should be able to support an additional 100,000 lbs of load before failure. I don't feel that an RTU would cause a collapse of this magnitude. Failure of the pool deck or garage slab causing an increase in unbraced length seems more plausible given the deferred maintenance.

 

[Spartan5]

The take away from the Reddit thread is that there was a collapse in the garage 2-3 minutes before the whole things came down. It was felt by the resident of unit 111 at 1:19 am. There was a larger jolt and shaking that prompted the family to evacuate the unit and flee the building. The catastrophic failure happened at 1:22.

Sounds like there was a column and slab failure in the basement with a few minutes of load redistribution before there wasn’t anywhere left for it to go.

 

[jrs87]

Security video of higher quality and starts a second or too earlier.

https://www.reddit.com/r/Catastroph...f/champlain_towers_south_condo_collapsing_in/

 

[epoxybot]

Just for the record, Epoxy Injection of cracks resulting from corrosion of rebar, is not a viable solution to repairing the crack or remediating the corrosion. It is just kicking the can down the road.

 

[warrenslo]

Nearly all of the upper-level columns in the remaining portion of the building sit on transfer beams between the first and second floors.
The three exposed columns where the parking slab fell (J12, J14, J15) are larger than necessary for architectural reasons below the second floor, likely why this portion of the building did not collapse.

The columns in the collapsed portion were at minimum dimension all the way down, hence they would be first to fail with deterioration, settling, etc.
ALL of the columns in the initial collapsed portion are Type C at the exterior and Type G at the interior.
These columns have quite a bit of rebar at the lowest levels 12 x #11 in 16 x 16 (Type C) and 10 x #11 in 14 x 18 (Type G.)
Both types near the maximum reinforcement ratio, once concrete spalling occurs they would theoretically be over code allowed ratio and need to be strengthened.
But, they weren't strengthened due to parking, to enlarge columns reduces parking space size or the space altogether, so the HOA technically wasn't allowed due to zoning laws.

In addition, they appear to have been overloaded. According to the plans provided, the columns were not designed for the penthouse addition.
The column schedule mislabels floor 12 as the penthouse.

The penthouse addition drawings show the penthouse at the roof level or floor 13 (the elevator to the penthouse from floor 12 does not appear to have been added, instead the corridor was extended to the main elevators.)
The area under this corridor collapsed first.

Finally, the recertification documents note the structural steel supporting the HVAC system had isolated rusting.
Failure of the HVAC steel would have caused exactly the type of collapse we saw (see my prior post above.)

-W

 

[MHnkl]

I wonder if the column with the wide crack was along column line 10, where the failure originated?

 

[Mark R]

Finally, the recertification documents note the structural steel supporting the HVAC system had isolated rusting.

The question is when was that review of the supports for the HVAC done. Considering we have documentation that the equipment was replaced within the last 2 years it seems hard to imagine that the supports would be in that bad a condition that rapidly.

 

[IEGeezer]

Finally, the recertification documents note the structural steel supporting the HVAC system had isolated rusting.

The review you quote showing rusting of the HVAC system was supposedly done between 8/01 and 9/06/2018 but was not received by the town of Surfside until "5:35 PM on June 24, 2021."

Otherwise, I agree with you. Maybe the unit wasn't anchored properly and a jolt loosened it, so that it wasn't the trigger but it helped precipitate the collapse. The reddit thread said there were two jolts about 3 minutes apart. Alternatively, it simply fell when the building fell and it wasn't involved in the collapse. Corrosion failure of an overloaded structure wouldn't be surprising. If the margins of safety had been greater, maybe many lives might have been spared. Finding that the columns weren't designed for the penthouse addition is a smoking gun.

 

[warrenslo]

IEGeezer: Beginning of the report says: "This report was not formally submitted or authorized by the property owner Champlain Towers South Condominium Association, Inc., as required by Section 8-11(f)(iv) of the Miami-Dade County Code."

 

[Mark R]

IEGeezer: Beginning of the report says: "This report was not formally submitted or authorized by the property owner Champlain Towers South Condominium Association, Inc., as required by Section 8-11(f)(iv) of the Miami-Dade County Code."

I saw that also and wonder who paid for and authorized the study if it wasn't the Condominium Association?

 

[IEGeezer]

warrenslo: You are correct. That's why I said supposedly. Providing a report two years late and hours after the collapse raises eyebrows.

 

[Murph 9000]

I saw that also and wonder who paid for and authorized the study if it wasn't the Condominium Association?

It looks to me that Morabito submitted it after the collapse, but originally prepared it alongside the 2018 report he did for the Condo. I'd guess he sent it in to be as helpful as possible and avoid any appearance of concealing anything from the investigation.

On the rooftop HVAC unit, I don't believe it's at the root of the failure. The photo of the steel frame corrosion in this unauthorized form report doesn't look severe enough to fail in 3 years. The location, directly north of the elevators does not fit with the start of the collapse in the security camera looking across from the new building to the south. The collapse of the upper levels appears to initiate around the x11 apartments and ramp to the parking garage, in the middle of the wing. The section closest to the elevators appears to be pulled into the collapse later, presumably pulling the HVAC unit and frame down with it.

"Gabe" from apartment 111, directly over the lower end of the ramp, seems to be saying that the pool deck slab out in the open had visibly collapsed while the building was still standing. He was able to escape with his family after seeing that, before the collapse. That progression doesn't really fit with the new HVAC unit being at the root. It suggests that the exterior pool deck failed at a column, progressed towards the x11 apartments, then pulled out a column or two below apartment 111.

 

[warrenslo]

 

[warrenslo]

On the rooftop HVAC unit, I don't believe it's at the root of the failure. The photo of the steel frame corrosion in this unauthorized form report doesn't look severe enough to fail in 3 years. The location, directly north of the elevators does not fit with the start of the collapse in the security camera looking across from the new building to the south. The collapse of the upper levels appears to initiate around the x11 apartments and ramp to the parking garage, in the middle of the wing. The section closest to the elevators appears to be pulled into the collapse later, presumably pulling the HVAC unit and frame down with it.

The HVAC unit was replaced with a larger and most likely heavier unit in a different location after the 2018 inspection.

Do we know which column on the x11 stack failed? Assuming it was a corridor column as the collapse seemed to start there. Those columns had an extra floor added to the roof for the walkway to the penthouse addition. The corridor column part of the collapse furthest to the east had both the penthouse walkway and HVAC frame added to it.

-W

 

[waross]

Thanks for the catch, ingenuity.
Correction made.
Central American concrete. I once pulled over too far to the right and my door and rocker panel clipped a concrete pedestal that had once supported a lamp standard.
There was little damage to my truck. There was a lot of damage to the concrete.

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[Keith_1]

The only design flaws in this building that I can possibly see is a lack of slope and water infiltration on the parking deck. This is not an engineering problem, it is a licensing and accountability problem. For the most part every issue that caused this structure to catastrophically fail could have be easily been remediated.

If a column failure, or major deck damage is documented and not addressed for years someone needs to go to prison. That column alone should have been immediately shored up, ask questions later.

This was an entirely preventable event, thank god for extremely conservative redundancy factors, or we would see alot more of this.

 

[Murph 9000]

Do we know which column on the x11 stack failed?

I don't think the current public evidence gives any certainty around that. To me, the security CCTV from the south makes it look like the K,L,M columns were first to go in the upper collapse, probably rows 4,8,10 (I'd guess row 10 first, but it might have started at the corridor row 4).

The red HVAC support frame looks to be the same for both old and new. It appears to span E & H columns in rows 2 and 4. There's also the I series of columns between it and where I believe the earliest upper collapse is visible.

There's a fair bit of interpretation / guesswork above, trying to interpret the distant CCTV image which is looking diagonally across to it and it's all very quick. We can't rule the new HVAC unit out as one of many contributing factors, it just doesn't look to me that it was at the root of the failure or part of the early progression.