Miami Beach, Champlain Towers South apartment building collapse, Part 07 90

[Seppe]

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[Auri]

If M-10 fails on 1st floor, how does that lead to pool deck collapse before the building? It would seem the occupants of #111 would notice the left corner of their living room explode - or if sheetrock somehow contains that, at least the wind ought to exit the unit, not enter.

It pains me to rely on details from a NYPost article, but if dust was rushing into their unit, perhaps I'd be more inclined to suspect L-10 at basement level.

Or it could be a basement column further south. I'm unsure precisely how well concrete transmits structure sounds. I know it doesn't compress well, so it logically transmits shock very well and could misdirect a listener just like an echo chamber.

 

[1503-44]

Concrete structures transmit sounds from bottom to top or top to bottom very well and are difficult to soundproof. Basically they are echo chambers. You can tell if something fell on the floor immediately above your ceiling, but all other sounds could have origins from the roof to the cellar.

 

[Demented]

I just want to make it very clear, I don't believe in roof first.

It appears the image Optical98 posted of the roof actually doesn't show the roof sweeper. I thought it did, but while looking for that trailer I spotted this in an image I circled of the roof leak and drains that don't do shit but flow once the roof is fully flooded.
Same colors, different machine. Typical of industrial tools.

Optical98, thank you for this picture!

It appears this would have been by the lobby entrance area, on top of the deck? 2 ton tar tank (~800-900psf if left full for next morning as is typical of the area). This wouldn't have been parked under ground in the garage would it have been?

 

[Auri]

It's right around the intended maintenance parking:

 

[Sym P. le]

I just want to make it very clear, I don't believe in roof first.

Frankly, I don't really care what religion you subscribe to but feel free to contribute evidence or reasoned thought to the discussion. I can draw my own conclusions.

Even if I think something or someone is a complete wingnut, a different approach may tweek an open mind towards the true solution to the riddle.

 

[CE3527]

I initially thought collapse along L, then along M, and have come back to L line. Two main reasons. L is more central to the collapse in the video so makes sense the collapse originated in the center. Two, the observable deformation of the room in the ring video is much closer to the L line then the M line. I don't see how the L corner of the room is deforming if failure is occurring along M. It's true though, the progression of the collapse is a discussion of "how", and the real mystery is the initiating event which I still think is rooted in the deck with some combination of bad design, bad construction, and neglected maintenance over 40 years.

 

[bones206]

The simulation seems to show the first elements collapsing are the ground level wall panels. I suppose that would sound like a wall collapsing. I wonder what their basis is for initiating those wall panel failures.

Also the view of the rubble heap from within the garage matches closely what I saw in my squinting analysis of the tick tok video, showing the edge of the slab, planters and the broken M11.1 column and beam.

Edit: looking at a different angle in the video, it seems they have M11.1 remaining standing (under the planter) while M10 collapses early on. This doesn’t match what I believe the tik tok video shows. I’m not sure they accurately accounted for the beam connecting those two columns.

 

[Nukeman948]

But I'm not speculating about the complaint from unit 302 Nukeman, it's contained in the documents. I will find it and add it to give you more CONTEXT.

My point has always been that a picture of items that may have been moved or damaged when they were dug up doesn't tell the whole story. A description of time and location and what led up to the condition they were in can make all the difference.

And the complaint from 302 didn't help much either. Where were the items at the time of the collapse?

 

[taz112358]

2) The penthouse collapsed first, no matter how you look at the pool video (which was activated by movement or has earlier shots not shared with the public) those floors are missing, get that through your head!

This is my big question. Why does the video start the instant of the collapse? The frames just before could tell us a lot. Why wouldn't all footage of this building be released to the public, exactly for the type of speculation we are having to help understand what went wrong.

Florida's Sunshine Laws should hopefully help with all this, they are the most open state in the nation with public info.

 

[Demented]

Frankly, I don't really care what religion you subscribe to but feel free to contribute evidence or reasoned thought to the discussion. I can draw my own conclusions.

Even if I think something or someone is a complete wingnut, a different approach may tweek an open mind towards the true solution to the riddle.

Care to elaborate? What does religion have to do with anything?

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

 

[Spartan5]

It’s an analogy.

Most people here are agnostic.

A few others are expecting that they will ascend to heaven while alive aboard a UFO after ingesting fatal doses of phenobarbital and putting plastic bags over their head.

Something like that anyway.

 

[dik]

Bad thing to be... the problem is that one of the main tenets is that the truth will 'never be revealed to you'... not a good thing for an engineer.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Spartan5]

Bad thing to be... the problem is that one of the main tenets is that the truth will 'never be revealed to you'... not a good thing for an engineer.

That’s not a tenet I’m familiar with. [edit: I am familiar with the concept that science and religion are diametrically opposed in that way; that the “truth” is discovered through observation in the former and revealed through regurgitation in the latter. Maybe that’s what you were driving at.]

(As an aside, someday I’d like to help you sort the quote feature. You’re a poster a value and your use of it makes things tough to follow sometimes.)

Agnosticism is of the essence of science, whether ancient or modern. It simply means that a man shall not say he knows or believes that which he has no scientific grounds for professing to know or believe.

We digress. For the sake of the analogy, it’s not necessary to plumb the depths of theology. But we’d both agree that it’s way to be early to professing faith in one particular god or another at this stage of the game. And even once it’s sorted there will still be an unfortunate abundance of Truthers about us.

 

[dragon6172]

This is my big question. Why does the video start the instant of the collapse? The frames just before could tell us a lot.

I believe the assumption is that the footage is from a motion sensitive camera. Meaning there are no prior frames recorded to examine.

 

[dik]

I'm happy with the quote feature... I don't need to attribute the quote to anyone... just note that it was an earlier quote.

digressing... the great philosophers have not sorted things out in several millenia... I likely won't in my short lifetime... I'm part of the ignoranti. I don't worry about such important stuff... and am happy about it.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Spartan5]

digressing... the great philosophers have not sorted things out in several millenia... I likely won't in my short lifetime... I'm part of the ignoranti. I don't worry about such important stuff... and am happy about it.

Philosophy being one thing, and engineering a another, I think we can agree to…

“… follow your reason as far as it will take you, without regard to any other consideration. And do not pretend that conclusions are certain which are not demonstrated or demonstrable.”

 

[Optical98]

I have never stated that I was posting conclusive evidence ...on any hypothesis.

I ask questions and post pictures on different findings, often to help others.

My first post and query was regarding the Generator Room, because there were plans stating that the floor/slab needed reinforcement. Even if the new equipment was never installed, there was indication that they'd found weakness in that slab which is over the ramp entrance area.

Also, many talk about the upper parking collapse on the south end of the building, but don't realize that the North end had a collapse as well. This is why I'm curious about the placement of the crane and large tar kettle. Several witnesses mentioned hearing a loud boom or even an explosion.

Adriana and Roberto Castillero said they saw the ceiling of the garage collapse, THEN looked up and saw people up on their balconies looking down trying to see what happened, she started taping the water leaking in the ramp entrance area and yelling for the people to leave.

Nicolás Vazquez "The smoke, dust, and " unbearable weird smell " also prevented them from breathing normally."

I've never promoted the Roof theory, but I don't dismiss it either. Same for the pool deck theory. I'd love to know what the debris on the ramp was definitively at some point.

As things calm down more interviews will be had and more videos and photos will emerge, we need to stay open minded and willing to discuss there meanings.

 

[MaudSTL]

Adriana and Roberto Castillero said they saw the ceiling of the garage collapse,

This is incorrect. They did not see the garage ceiling collapse. Instead, they heard a loud noise while swimming in the pool, got out and went over, and then saw rubble and a gushing pipe in the garage entrance. Adriana Sarmiento started videoing at 1:18 am.

 

[Tropmet]

There has been a lot of telephone game and paraphrasing of witness statements both in the media and on this thread - but because they were on the spot what they saw and experienced is extremely important and needs to be accurately documented.

The most accurate news stories I read were from the Washington Post (WAPO) and the Associated Press (AP) story printed in The Republic. This was especially helpful regards the Nir family. In addition Sky News had an interview with a significant direct quote from Cassondra Stratton’s sister.

1) 410 Cassondra Stratton / roof work, vibrations and sound of running water

Images from her blog showed that she had moved to unit 410. Also news stories made a point of later saying she was not in unit 412 but established she was on the fourth floor.

The most accurate description of Cassondra Stratton’s conversation with her husband was an account from her sister, who was interviewed by Sky News. No other news story had specific quotes of she said and in order. The interview quotes the short video interview with the sister word for word, as she was standing on the beach in front of the collapsed CTS. The video interview is included in the article.

First, Cassondra was on her balcony (which afforded a clear view of the pool deck) upset, and calling her husband in D.C, waking him up. Perhaps she was awake and on the balcony because she had heard the same loud noise that prompted Sarah Nir in 111 to run to the lobby and Maria Iliana Monteagudo in 611 to wake up. We don’t know what it was but we do know it upset her. We don’t know how long they talked before the pool deck failure. In a Herald article her husband said, “She was frantic.” And from a Local10 article “Suddenly he heard his wife, Cassondra, speaking frantically about their oceanfront condo building trembling.” According to her sister, Ashley Dean, this is what she then said, seemingly interrupting their conversation:

“Suddenly she says, 'honey the pool is caving in, the pool is sinking to the ground'," Ashley recounts.
"He said 'what are you talking about?' And she says, 'the ground is shaking, everything's shaking' and then she screamed a blood curdling scream and the line went dead."

In a reference to a WAPO article, this was a quote from Ashley: “She screamed bloody murder and that was it,” Stratton’s sister, Ashley Dean, told The Washington Post.”

Ashley talked to Cassondra’s husband Michael (both flew to FL to wait at Surfside). Given the circumstances, it is very likely that he remembered the last portion of the conversation well, repeated it to her, and that she repeated it verbatim.

This suggests there was first something that made her go out on the balcony at that late hour. Something made her “frantic” according to her husband but we don’t have any quotes on what that was, and how long they talked about it. Perhaps it took some minutes while she attempted to explain it and perhaps he tried to calm her down. While on the balcony talking with her husband she first observed the collapse of what we know is the pool deck. Then it appears that very shortly after the pool deck collapsed the building began shaking and then that section of the building began to fall. Many other articles reversed the order of these two things in their paraphrasing of the phone conversation, or left one of them out.

This account is actually in line with the experience of the Nir family once you get to the accurate reconstruction of events that they experienced (I will explain that the mother’s account was embellished and inaccurate in several ways).

In addition, there is this additional information in the same interview with Ashley Dean: “My sister told me about all kinds of water leaks and people on her roof with heavy equipment.”

And from the WAPO article:

Days before the collapse, Stratton, 40, the model and yoga instructor who went silent after calling her husband in Denver, had told family members that “something was wrong” with the building, according to Dean, her older sister. Stratton, who remains among the missing, had seen water damage and worried about the heavy equipment she saw being lifted to the roof for repair work, Dean said.

Other residents had expressed concerns, too. Elaine Sabino, a transplant from New York who had lived in the tower’s penthouse for two years, complained in recent weeks “about the construction on the roof,” said her brother-in-law, Douglas Berdeaux.
Sabino, who is also missing, “said it was vibrating her unit,” he said. “She even went up to talk to the construction manager and told them whatever they were doing was making her rooms vibrate. She said she was worried that the ceiling was going to collapse on top of her bed. She also said she heard water around the elevator. A manager went up to her unit with her and looked around, and told her they’re doing some work, but everything was okay.”

Also, Fiorella Terenzi who lived in Champlain Towers East and who had a clear view to CTS, was quoted in a NYT article, “Ms. Terenzi said she had seen heavy equipment on the roof of the south tower for the past two weeks.”

Out of the many possible causes of the collapse, the prior two weeks of roof work to install the anchors for window washers by drilling into the columns of the building, using what observers identified as “heavy equipment” and creating vibrations in the concrete structure over a two-week period just prior to the collapse, and the account of hearing running water from inside the building and Stratton’s unspecified “water damage,” has to be considered a factor. The work having just been completed, the roof inspection, apparently expedited, had occurred on Wednesday with the building failing only hours later. Could load or vibrations from this roof work have further weakened the columns in the basement in the area of the building that fell first, if the basement columns were already compromised? Remember that vibrations from road work and the load of materials placed on the roadway were factors in the fragile non-redundant-design 35W bridge failure, causing the failure below the bridge deck of the supporting structure. I felt it was a good idea to add this, as some, reading my post, made an assumption that was not correct and jumped to a wrong conclusion. In fact I am not making any hypothesis about the failure but only mentioning possible implications from the survivor’s stories, which also tell us there was indication of a failure / collapse just before the pool deck failure, and perhaps many other earlier subtle signs in the previous days. This would be more likely than not.

I think that we also have to give weight to the statement that Cassondra thought that something was wrong with the building. It is frankly an odd thing to say as she said she loved living there. A very odd thing to bring up in conversation. In addition, from a CNN article,

Pablo Rodriguez, whose mother and grandmother are among at least 99 missing, said his mother called him to report "creaking noises" she heard a day before the building collapsed. 
"She just told me she had woken up around 3 [or] 4 in the morning and had heard like some creaking noises," he told CNN's Erin Burnett. "They were loud enough to wake her."

And from another WAPO article:

“I was telling my mom how this place is great, the house is great, everything is great,” Gabe [Nir] said. “But then slowly, when you live there, you start to notice the small creaks and the small issues the building had.”

There was the water that pooled in the parking garage after rain, he said, and the uneven pool-deck pavement. Sometimes when he stepped on it, water would seep through the cracks.

This suggests that there were signs that something was wrong with the building and that the failure may have started some time before the actual collapse, and that this may have been during the time roof work was occurring. It would be helpful to know what day the roof anchors were installed over the x11 units and if those were done last, as perhaps vibrations might have traveled down through the building at that time to possibly weakened columns in the basement level. Also - the uneven and waterlogged pool deck area that Gabe Nir would have been most likely to have walked on and most often would have been the patio right outside their unit.

2) 611 Maria Iliana Monteagudo

There appeared to be two separate failures that can be deduced from Ms. Monteagudo’s account. The first woke her up but she could not articulate what it was. From a WAPO article:

Monteagudo, 64, was asleep Thursday morning when a strange feeling woke her. “It’s like something supernatural woke me up. I felt something strange…”

She continued:

“…I thought, 'Oh, I forgot to close the sliding door to the balcony, and the wind is making the noise,’ ” she said. “I tried to close the sliding door, and it felt like the building was moving. The door wouldn’t close.”

Then Monteagudo heard a crack. There was a line in the wall coming down from the ceiling — about two fingers wide. “Then it started getting wider and wider as I watched,” she said. “Something said, you have to run. You have to run immediately.”

No kidding. A crack running down the wall getting wider and wider…that would indeed make you want to run. Her account also mentions movement of the building. The x11 units were becoming racked (the window frame out of true) and the wall was actually splitting open. A crack was also heard in the 711 Ring video but the collapse occurred only seconds after that, so this must have been an earlier crack, because she did not leave immediately. Surprisingly she did a number of things then in spite of saying she left immediately, things that must have taken perhaps thirty seconds to one minute before reaching the stairwell, and that must have taken great presence of mind considering the circumstances:

“I ran to my bedroom, and took off my robe and changed into any dress and any sandals. I ran to the dining room table, I got my purse and my credit cards. I took the key, I blew out the candle that I light every night for Guadalupe of Mexico,” she said. “I blew out the candle, just in case.”

What can we conclude from this? That section of the building was beginning to fail. We know the pool deck failed prior to this from the parking garage video. We know there was a short period of time between the pool deck failure and the building failure from the Nir accounts. Ms. Monteagudo’s account continued:

Monteagudo ran to the stairs, descending quickly. Between the sixth and fourth floors, there was a noise — and she realized the building was falling. Monteagudo worried that she would be crushed. “I thought if it’s coming down, and it’s coming down, down, down like a domino effect,” she said. This mirrors the sound from the 711 Ring video of several distinct separate floor failures right at the end.

In a video interview she said that she thought that three seconds had passed between the time she entered the stairwell and the time the building collapsed. If she ran from her unit, perhaps 15 to 30 seconds occurred before she entered the stairwell. She must have been running because she said that she had already gone down at least one flight in three seconds.

Continuing from the article:

When Monteagudo finally escaped from a door, there was water up to her ankles, and cables floating in it. She ran into a security guard. “He told me, ‘Mama, mama, let’s go, this is an earthquake,’ ” Monteagudo said. “I said, ‘No, it’s not an earthquake, it’s the building falling down.’ ”

There was a wall she needed to climb, then an abyss several feet wide. The security guard urged her to jump. “But I couldn’t jump,” she said. “I saw a piece of column, and I put a foot on it, and I climbed over and found myself in the middle of the street.” She emerged from the building in the visitors parking area.

It sounds like she was able to get to the basement, get past the debris at the bottom of the stairwell mentioned in the escape of the Aguero family, and then oddly ran into the security guard. Since there was no egress between the lobby and the stairwell, and the front door locked when the electricity went off, it is not clear how the security guard found a way to get down to the basement to escape. Perhaps the large lobby windows had broken providing an exit down. But it sounds like they both were able to climb debris in the sunken parking garage area in such a way as to climb out in the front of the building rather than to the rear and to the beach as the Aguero family had done. That part of the building, the valet parking, was not enclosed, was open to the elements, so any part of it that fell, and perhaps it fell all the way to the front of the building, could have provided escape along the edges of the valet parking area by climbing upward as she described. Climbing out along the front would have led to the street.

1) 111 Nir family

The Nir family observed three separate failures: an extreme crashing sound in their unit, the pool deck failure outside the lobby, and the building failure, in that order.

Sarah Nir gave extensive a detailed interview to CNN. But several things in that interview immediately stood out as odd or unlikely, which were subsequently contradicted from her childrens’ accounts. Her children’s accounts provided more accurate detail than hers.

The first thing that did not gibe in her account was, “it’s really a wall separating my apartment to the security guy.” The door to unit 111 is located near the end of a corridor and to reach the security guard, in the lobby, she would have had to go down the corridor and then take a left (and apparently, looking at an image of the lobby, then open a swinging privacy door to enter the lobby from this back hall), where the security guard desk was located nearby.

She had described the loud noise that prompted her to go to the lobby and talk to the security guard as, “a smash the wall is collapsing, the wall above me.” From other accounts we learn what her two children heard and experienced at that time and after she left the apartment. In a video interview her 15-year-old daughter Chani said, “I went to take a shower and I came out of the shower dried myself and I was about to get dressed and hear like a big boom and I was like oh no something’s not right and I just ran out of the bathroom and I checked and I thought the whole ceiling was like collapsing.” This must have been as her mother was walking out the door to go to the guard desk, or just after. Significantly, both mother and daughter described the sound as that of something collapsing and the daughter expected to see the entire ceiling had fallen when she came out of the bathroom! From this we can assume it was an extraordinary sound. Both also took the sound to come from above.

The son, 25-year-old Gabe, was in the kitchen. In an article from CBSNews,

…they all arrived back at the building just before 1 a.m., he said. That's when the family started hearing loud noises. Gabe said it sounded like construction…”As soon as she goes down to the front, I hear this loud rumble. Like, you feel like an earthquake is happening right in front of you," he said. 

From The Republic:

Down on the first floor, recent college graduate Gabriel Nir had just finished a late night workout and was in the kitchen cooking salmon. The rest of the family would normally be asleep, but his 15-year-old sister had just returned from babysitting and was in the shower, his dad was out of town and his mom had just come home from an event.
They all heard the first thunderous rumble. They knew the building was undergoing construction and had been irritated by the incessant noise, but this felt different.
Sara Nir, their mother, ran to the lobby, asking the security guard if she’d seen anything.
Back in the kitchen, thick, concrete dust came rushing into their apartment from the patio windows near the pool. The ground was shaking as 25-year-old Gabriel ran to the bathroom.

“We have to go now!” he screamed to his sister. They ran to the lobby,…

From CBSNews:

Gabe told his sister to leave the apartment with him…

So we know that right after Sara Nir left the apartment, her children left for the lobby as well - in a hurry - because the building was rumbling and shaking and concrete dust poured into their apartment from the patio sliding glass doors. This is completely at odds with Sara Nir’s account, in which she runs back to the hallway, looks down, and sees her children were lackadaisically idling by the front door of the apartment where they had to be spurred into action by her to rescue them, as we see from her CNN interview and a WAPO article, below. This is the second inaccuracy in her story.

From the CNN interview:

The minute I say what are you doing about that it is a big boom and I was running to see where the sound come from and I saw all the garage collapse. … I ran back to the hallway and I saw my two kids standing next to the door they’re just in front of my apartment and don’t move. And I was screaming it’s an earthquake an earthquake and I was thinking very fast … So my daughter was looking at me and said but I am with my bathrobe and I said I don’t care run run! run as much as you can.

From the WAPO:
An earthquake, she thought, dashing back toward Unit 111, toward her kids.
Gabe, 25, a night owl, had just pulled salmon from the oven, while 15-year-old Chani was fresh out of the shower. The two stood gaping at their mother from the doorway of the apartment, drawn out by the commotion.

These following two different NBC6 articles indicate that her two children were in the lobby with her when the valet parking and nearby pool deck collapse occurred. Both said that they saw this collapse, which to them was the “second” collapse.

From an NBC6 article: “The first collapse happened, and me and my mom and sister went out," Nir told NBC 6 just hours after Champlain Towers South partially collapsed Thursday morning. "We see the collapse happening on the poolside and I saw a bunch of cars going inside the car garage, so I panicked, my mom panicked, everyone panicked."

From an NBC6 article: “We heard like another boom, while we’re still in the lobby, then we ran outside, and we see the whole pool area is just gone,” said Chani.

The third inaccuracy in Sara Nir’s CNN interview is something that I found hard to believe as soon as I heard it: “the security guy he was shocked he didn’t know what to do I said call the police and he said but what is the address of this building? He didn’t know he was so confused. And I say 8777 and he say no no no write for me and I tell my son write for him and he wrote and we ran out of the building and I told my kids run as fast as you can.”

They have seen the building is collapsing and they are about to run for their life, yet the mother asks her son to oblige her to write down the building address for a security guard that doesn’t know the address and doesn’t understand it when you say it and insists it has to be written down, doesn’t call 911 immediately and doesn’t seem to know what to do in an emergency? This did not happen as she described.

From the WAPO:

Fleeing the faltering building that night, the Nirs yelled at the security guard to call 911. The stunned guard asked for the address, reaching for a pen and paper. “I said, ‘Listen, forget about it,’” Gabe said, and he hurried away.

From The Republic:

…We have to go now!” he screamed to his sister. They ran to the lobby, where their mother urged the security guard to call 911. The guard couldn’t remember the address so Gabriel phoned. “Please hurry, please hurry,” he begged.

So we see that the more realistic scenario occurred, where Gabe phoned in a 911 call himself and they had no time to write down an address.

While in the lobby both children noted that they saw the Argentine actors, a couple. In the Chani CNN interview she says, “We were the first family out and there was like another family they came from the elevator and they’re like you don’t even understand we felt like rumbling inside the elevator.“ In the WAPO article, “As they fled, the Nirs said, they saw a man running to the doors, pushing a stroller. A couple was near the elevators, the woman struck speechless.” This indicates that this couple was aware that something was happening to the building while they were in the elevator going from the basement to the lobby. They emerge from the elevator to an already collapsed pool deck and dust filling the lobby.

Sara Nir’s CNN interview continued:

…I told my kids run as fast as you can. Crossing the street we cross Collins we just cross Collins God watch us God was waiting for us to leave the building. And then another big boom then we didn’t see anything it was suddenly white after the big boom and it was white dust all over and I thought I am by myself in this world. And I thought we were still running and I told my son call the police again call the police again. Probably my son was looking he was very curious to see I didn’t tell them to watch what is going on in the back but probably he looked and he saw the building collapse. But I say it’s an earthquake we don’t know what is safe where the ground is safe run and we still running and running. I couldn’t breathe I couldn’t do anything and I said God help God help and I didn’t know what to do. We had been really running like three four blocks away from the building and then I need to breathe…

In the story from The Republic, it is Gabe Nir who takes action in his account. It seems he ran outside for a minute to get a better view of the collapse of the valet parking area:

Outside, he noticed the car deck had caved into the parking garage. Car alarms were blaring, emergency lights were flashing and water was rapidly filling the garage where pipes had burst.
He ran back to the lobby, where the choking dust cloud was making it difficult to see. Residents from upstairs were running out the door screaming, many still in pajamas, one man pushing a baby stroller.
It was getting harder to breathe. The rumbling intensified, as he pushed his mom and sister safely into the street.
“Run, run,” he ordered.
Tiny rocks and bits of debris pelted his head as he turned back to face the image that still haunts him.
“I saw the building turning into a white dust,” he says.

From the WAPO: They surged out the front entrance and onto a quiet Collins Avenue.
The dust was everywhere, like a sudden sandstorm, burning the Nirs’ eyes and throats. Gabe pulled his shirt to his face. Over a six-minute call, he remembers telling the 911 operator, “You guys need to come here ASAP.”

From an NBC6 article: “It was at that moment I saw the ground shaking. I felt something was happening," Nir said. "At that time, I had to run out. I told my mom, my sister, 'everyone, start running,' and so that happened. Everything started, out of nowhere, like cement, dust, sand coming out."

From an NBC6 article: “We heard like another boom, while we’re still in the lobby, then we ran outside, and we see the whole pool area is just gone,” said Chani. … “So we’re all just running across the street and the second we got across Collins, we hear like a huge boom and we see white dust particles following us, there were like three parts of the collapse, I think that was like the last collapse and I was like, whoa,” said Chani.

From CBSNews:

Gabe told his sister to leave the apartment with him, and when they got to the lobby, they joined their mom and started to run. As Sara and Chani ran from the building, Gabe called 911. 
"I'm on the phone with 911. I see cars going inwards, underneath the building — underneath the building is the car garage. And next to the pool area, you just see everything just sunk down below, underneath. And I hear car alarms going off, I see lights flashing everywhere. And I remember telling 911, 'I can't explain anything right now, you guys have to come here ASAP,'" he said. 
"I remember screaming to my mom and my sister, 'Run, run, just run for your life,'" Gabe said, adding that he heard screaming from others and it felt like a nightmare.
“I didn't know where to run. You couldn't see anything. It was like a sandstorm. Just white, concrete dust," he said. 
The 25-year-old caught up with his mom and sister and they continued to run from the scene. He thought the cause of the collapse was a gas explosion and wanted to get a safe distance away.

So what can we conclude from the Nirs’ accounts? The “first collapse” that they identified was a significant sound that resulted in building movement, rumbling, and most importantly, significant dust, which Gabe thought was concrete dust, quickly entering the apartment from the patio door area. Both the mother and daughter said the sound came from above. All three say they previously heard “construction” noises. In the six months they had lived there, perhaps they had been exposed to construction noises from renovations in nearby units. Perhaps they were referring to the recent two weeks of construction on the roof of the building. We can conclude this could have been one of a number of things. First it literally could have been late night construction occurring in unit 211 or another nearby unit above them that resulted in a collapse. Secondly it could have been the first significant step of the imminent building collapse and it may have only sounded like it came from above. Third, it could have been that the first portion of the pool deck to collapse was right outside their patio doors.

We know that the “second” collapse they describe, the collapse of the valet parking and the part of the pool deck that was adjacent, came fairly quickly after the first. We know this because Sara Nir had only just begun to talk to the guard about the noises and her children who had rushed out of the unit just after her also witnessed this.

We also know that the building collapse - the “third collapse” in their account - came fairly soon after the pool deck collapse, both from Cassondra Stratton’s phone conversation with her husband and from the Nirs’ accounts.

From the Monteagudo account we know the x11 units were coming apart shortly before the building collapse and that Gabe Nir felt movement - shaking - in unit 111 before leaving.

 

[microwizard]

Witness statements are notoriously inaccurate. What is reported in the media is rarely what the person actually said, and then you have translation issues on top. I don't believe any forensic analysis relies on them. The answers are obtained by close inspection of the rubble, which is why samples have been taken for analysis. Courts of law may rely on witness evidence, but engineering is done with measurement and numbers.

I am open to the idea of roof-first collapse, it is a valid possibility, but still have seen no evidence for it. The security video that shows the collapse does not show the penthouse collapsed, but the whole building collapsing. At least without the first frames (which indeed are missing), the video is not definitive and can be (and is) interpreted both ways. The roof-first theory also requires a longer sequence of coincidental events. The garage collapse theory only requires chronic fatigue of garage level columns, and given the evidence of water encroachment into the basement, remains the simplest and most likely theory.