Mass casualty building collapse in Miami

[Mach 1 1677]

Crazy to see that deck basically punch through the columns and collapse. 

After the Northridge earthquake in LA, they found many structural failures were due to decks punching through basic columns like that, so they required all columns beefed up with caps to hopefully give enough strength to prevent that in the future.  (These probably wouldn't have even helped Surfside, with the years of deterioration and lack of maintenance.)

[Onboard 2.0 9083]

23 minutes ago, Mach 1 said:

Crazy to see that deck basically punch through the columns and collapse. 

After the Northridge earthquake in LA, they found many structural failures were due to decks punching through basic columns like that, so they required all columns beefed up with caps to hopefully give enough strength to prevent that in the future.  (These probably wouldn't have even helped Surfside, with the years of deterioration and lack of maintenance.)

Probably not ultimately,  but I bet that slab wouldn't have collapsed for several more years with those thickened "suspended footings".  The shear forces at that 6 - 8" thick slab to those columns  must have been immense.  That thickened slab detail would have cut those shear forces down considerably.

Edited July 26, 2021 by Onboard 2.0

[AUS-97HORN 11981]

21 minutes ago, Mach 1 said:

Crazy to see that deck basically punch through the columns and collapse. 

After the Northridge earthquake in LA, they found many structural failures were due to decks punching through basic columns like that, so they required all columns beefed up with caps to hopefully give enough strength to prevent that in the future.  (These probably wouldn't have even helped Surfside, with the years of deterioration and lack of maintenance.)

fair point

but this place was built in the early 80s and the Northridge quake was in '94, so that tech wouldnt have been part of this structure. 

[Onboard 2.0 9083]

2 minutes ago, AUS-97HORN said:

fair point

but this place was built in the early 80s and the Northridge quake was in '94, so that tech wouldnt have been part of this structure. 

 That thickened slab detail is meant to absorb lateral force movement usually so it's probably a seismic zone detail to begin with. That thickened detail wouldn't have been called for in Florida even as a wind loading detail since it was at an on grade slab

[Captainant 28277]

Practical Engineering put out a good technical explainer of known facts and factors leading to the collapse. Interesting watch during your lunch break

 

[atomheartbevo 90400]

[Biff Tannen 45953]

25 minutes ago, atomheartbevo said:

As if we needed more horrific details on this. 

[NorthLoop 14399]

I honestly would've guessed more than 9

[ConferenceRoom 6206]

https://www.nytimes.com/interactive/2021/09/01/us/miami-building-collapse.html

[atomheartbevo 90400]

I'd be nervous about this out on the West Coast.

https://www.latimes.com/california/story/2021-08-31/retrofit-leaning-millennium-tower-san-francisco-halted-sinking

Quote

A retrofit of the leaning Millennium Tower of San Francisco has been suspended after crews discovered the building was sinking at a faster rate during the construction effort. 

The nearly $100-million retrofit was halted Aug. 19, and a two- to four-week moratorium was announced “while we try to understand better the mechanisms associated with the increased settlement rate and available means of mitigating this,” Doug Elmets, a spokesman for the luxury residential building’s homeowners association, said in an email.

Quote

One of San Francisco’s tallest skyscrapers, Millennium Tower has sunk since construction began in 2006 and is tilting. The building is ranked as San Francisco’s sixth tallest building, according to skyscrapercenter.com

Quote

Millennium Tower is in the heart of San Francisco’s South-of-Market district, which has transformed over the last two decades from a forgotten part of downtown to a capital of tech money in the city. Just next to Millennium Tower is Salesforce Tower, the tallest building in San Francisco, as is Salesforce Transit Center, an elaborate bus terminal that will someday connect to Caltrain service to Silicon Valley. 

A problem for Millennium Tower, some structural engineers have said, is that its foundation reaches only to a layer of sand, just above a layer of clay, instead of farther down into bedrock.

Quote

In October, the homeowners association, Millennium Tower Assn., announced plansfor the engineered retrofit of Millennium Tower to “prevent any significant future settlement of the skyscraper.” The plan involved installing 52 concrete piles — or columns — that would anchor the building to bedrock, 250 feet below ground.

 

[Dendox 102]

5 hours ago, ConferenceRoom said:

https://www.nytimes.com/interactive/2021/09/01/us/miami-building-collapse.html

is there a spoiler?

[Hanrahan 1306]

2 minutes ago, Dendox said:

is there a spoiler?

Spoiler

Get hosed, wanker.

 

[bolverk 30095]

57 minutes ago, Dendox said:

is there a spoiler?

It's one of those fantastic interactive scroll through stories that reveal specific shit that was fucked up.

The New York Times created a 3-D model of the tower based on the original design drawings. That model, combined with a review of documents and interviews with structural experts, reveals how design errors, last-minute changes, dubious construction practices and years of worsening deterioration could have all contributed to the collapse.

This pretty much sums it up: Bad design and shoddy construction.

The 3D model they walk the viewer through shows you what specifically was fucked up, most of which was the supporting elements in the garage and under the building (e.g., not enough rebar in some places, too much in others, not enough support beams and too narrow support columns underneath the part that collapsed, water seeping up and weakening piles, concrete was crumbling and cracking, failed waterproofing, palm tree containers built into the concrete deck allowing roots to penetrate and clog pipes and damage walls/pavers, no slope on deck to allow water to drain...).

Most of this was known prior to the collapse. How they let it remain occupied is beyond me.

[Dendox 102]

Thank you bolverk.  the other surly assholes were just that - surly assholes. 

 

 

[Onboard 2.0 9083]

7 hours ago, atomheartbevo said:

I'd be nervous about this out on the West Coast.

https://www.latimes.com/california/story/2021-08-31/retrofit-leaning-millennium-tower-san-francisco-halted-sinking

 

Yes, let's save some construction costs by not founding our skyscraper on suitable bearing capacity soil. Who's gonna find out ?

[atomheartbevo 90400]

1 hour ago, Onboard 2.0 said:

Yes, let's save some construction costs by not founding our skyscraper on suitable bearing capacity soil. Who's gonna find out ?

Always a good sign when they go to fix it and it sinks a little more.

[Updawg 2365]

A good earthquake will set it back straight.

[ConferenceRoom 6206]

4 hours ago, Dendox said:

Thank you bolverk.  the other surly assholes were just that - surly assholes. 

 

 

Hateful and mean-spirited. 

[Updawg 2365]

Thank you bolverk.  the other surly assholes were just that - surly assholes. 
 
 

Yeah. That was pretty a cool article

[Onboard 2.0 9083]

2 hours ago, ConferenceRoom said:

Hateful and mean-spirited. 

Congrats, you've summed up the bestest, most endearing Surly traits.

[Onboard 2.0 9083]

7 hours ago, bolverk said:

It's one of those fantastic interactive scroll through stories that reveal specific shit that was fucked up.

The New York Times created a 3-D model of the tower based on the original design drawings. That model, combined with a review of documents and interviews with structural experts, reveals how design errors, last-minute changes, dubious construction practices and years of worsening deterioration could have all contributed to the collapse.

This pretty much sums it up: Bad design and shoddy construction.

The 3D model they walk the viewer through shows you what specifically was fucked up, most of which was the supporting elements in the garage and under the building (e.g., not enough rebar in some places, too much in others, not enough support beams and too narrow support columns underneath the part that collapsed, water seeping up and weakening piles, concrete was crumbling and cracking, failed waterproofing, palm tree containers built into the concrete deck allowing roots to penetrate and clog pipes and damage walls/pavers, no slope on deck to allow water to drain...).

Most of this was known prior to the collapse. How they let it remain occupied is beyond me.

I was speculating about small conc. girders in the slab pours after seeing the piers, and the rebar left dangling from them after the conc slabs failed.