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Millennium Tower is tilting, sinking

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Re: Millennium Tower is tilting, sinking

#61

Post by JosephHatfield »

wahern wrote: post #29
WalterBright wrote: post #7

My house is on a steep hill, and Seattle has a reputation for hills sliding away under heavy rain. Before building it, I hired 3 separate geologists to evaluate the site. After digging holes, they said the site was sitting on "glacial till", which is clay that was compacted by about a mile of ice, and said there was nothing to worry about. Paying them was worth it for the peace of mind. (Turns out the till was so har…

I live in the Outer Richmond district of San Francisco, which was built on sand dunes. Most houses in my neighborhood were built in the 1920s and 1930s, +/- a decade. I was told by a contractor that it's extremely common for houses to have shifted considerably, sometimes by several feet. Mine certainly has, though not nearly that bad. Most of the houses are built on concrete foundation walls that go about 3 feet into…

The city is currently requiring many owners of soft story buildings in the Outer Richmond district to pay for seismic refitting.

Re: Millennium Tower is tilting, sinking

#63

Post by jessaustin »

rwallace wrote: post #56

"it's not steel-framed and instead uses a concrete design" I thought concrete buildings without steel frames came down instantly in earthquakes. What am I missing?

Steel reinforcement inside concrete is not the same as a steel frame outside concrete?

Re: Millennium Tower is tilting, sinking

#64

Post by tedunangst »

spikels wrote: post #49
vonmoltke wrote: post #35

Earlier quoted context omitted.

What here is misinformation?

A few examples: - Foundations of tall building must go to bedrock - not true. - Large buildings settling is unusual - not true. - Earthquake safety has been compromised in this case - not true. The structural engineering of tall buildings is complex. Multiple large engineering firms were involved in the design and construction of this building. Curbed (owned by Vox BTW) took the SF Cronicle article and cut out the mo…

I see a lot more comments asking if earthquake safety has been compromised than comments saying that it has.

Re: Millennium Tower is tilting, sinking

#65

Post by RGamma »

This brings me back to a question I have frequently asked myself: What do you do with unsafe or old skyscrapers? How would you raze such a thing? What if it falls over, breaks apart or breaks in on itself (9/11 gives an idea)?

To a layman (with slight acrophobia) skyscrapers seem pretty fragile, and I'd much rather have them built into the ground than towards the sky, but obviously they're holding up in general and I'm interested to see what happens with this one: Hope that it stops tilting or sinking? Raze it before anything bad happens?

Re: Millennium Tower is tilting, sinking

#68

Post by gnopgnip »

WalterBright wrote: post #7

My house is on a steep hill, and Seattle has a reputation for hills sliding away under heavy rain. Before building it, I hired 3 separate geologists to evaluate the site. After digging holes, they said the site was sitting on "glacial till", which is clay that was compacted by about a mile of ice, and said there was nothing to worry about. Paying them was worth it for the peace of mind. (Turns out the till was so har…

>I can't conceive of building a 58 story building on sand in an earthquake zone There are ~ 8 stories of concrete underground that is is built on. It would be another ~12 stories worth to get down to bedrock. Someone screwed up here but there are plenty of buildings that don't go all the way down to bedrock and are just fine. Maybe if they would have went with a lighter steel frame construction instead of concrete or if the building wasn't so tall the foundation would be fine.

Re: Millennium Tower is tilting, sinking

#70

Post by Animats »

was_boring wrote: post #37
Finnucane wrote: post #31

Earlier quoted context omitted.

Most of our big coastal cities are like that. Boston is about twice as big as it was in colonial times; all of the Back Bay is landfill. A lot of Cambridge is landfill. And yes, most of the taller buildings cluster around the more solid bedrock areas closer to downtown. But the engineering principles needed here aren't unknown--cities like Las Vegas and New Orleans have modern buildings that are much taller than were…

To add on, Chicago and New Orleans are both built on swamps, and the outer edges of New York are filled in -- making land for cities isn't the issue with the tower.

The tallest buildings in Chicago have foundations drilled down to bedrock. The Sears Tower (now Willits Tower) is built on bedrock. The Trump Tower [1] has pilings down to bedrock. The John Hancock building has foundations down to bedrock, even though they had to go down almost 200 feet.[2]

How unusual is 83 floors in earthquake country without foundations down to bedrock?

[1] http://faculty.arch.tamu.edu/media/cms_page_media/4433/trump... [2] http://khan.princeton.edu/khanHancock.html

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