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Millennium Tower is tilting, sinking

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Re: Millennium Tower is tilting, sinking

#141

Post by aidenn0 »

Artlav wrote: post #12
cheeze wrote: post #3

What is the risk? Does this make the building more dangerous because it's in an earthquake-prone area? Obviously this doesn't sound good, but the article mentions that there is no threat to safety of occupants. Is it merely aesthetic?

Uneven sinking is not good - doors/windows won't close, walls would crack, and so on. It does not take much to seize things, however buildings are usually designed to take a little of it. The rate at which it's sinking is the alarming part. But i would be mostly alarmed about earthquakes - the thing sits on sand. Proverbial or not, that would make it very susceptible to soil liquification. Imagine a stick with a weig…

When I read that it was built on fill, liquification was my first thought. Doesn't SF have limits to building sizes in liquification zones?

Re: Millennium Tower is tilting, sinking

#143

Post by astrodust »

WalterBright wrote: post #23
Someone1234 wrote: post #20

Earlier quoted context omitted.

Loving your attitude. I often feel like with a lot of building (big and small) there is insufficient evaluation of site factors. For example: Is there a hill above the site? THAT needs to be evaluated (sometimes they do, sometimes they don't). Is the site on a traditional floodplain? If so what actions have been taken to redirect the water flow? Does the system have the capacity to move the water away? Is the site it…

I did a lot of things to reduce risk. None were expensive. I watch other houses go up in the neighborhood, and they do none of them. My most expensive mistake was not having a geothermal heading system installed when the yard was all dug up anyway. I could have had it essentially for free, and save 30% on the heating bill.

What type of system were you evaluating? I'm not sure why this isn't a common feature in homes, as I've only seen it done on more industrial scales (e.g. mid-sized condos).

Re: Millennium Tower is tilting, sinking

#144

Post by astrodust »

jondiggsit wrote: post #79
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, for one, would rather be building on sand rather than clay. Clay is an absolutely terrible substrate for construction. Not to mention it does not drain. Hills don't become saturated with water... the water tends to flow to ze bottom of ze hill, where it will saturate things. I'd be curious to know what exactly you are draining into... drywells and clay are not friends. - High-end residential builder here

Clay can be a total pain in the ass to work with, it's more stubborn than concrete to remove, but you'd be hard pressed to find a material more solid to build on than rock. What's your beef with clay?

The kind of glacial packed clay mentioned in this article is the sort of stuff even a power shovel has trouble with. It looks like light coloured slate, dry, brittle, and dense.

I'm not sure what your preference for sand is other than it's easy to work with. That stuff can shift, it bloats when wet and heaves with frost, settles like crazy under pressure. Sure, it's easy to remove, but it's so variable I have no idea how you'd get anything to stay level on top of it.

Re: Millennium Tower is tilting, sinking

#145

Post by duaneb »

zubat wrote: post #72
djsumdog wrote: post #17

The article doesn't talk about the how this practically affects the entrances to the building. Do the doors have to be adjusted for such a drastic sinkage, or are buildings somehow designed so this isn't noticeable to the public?

I don't know what skyscrapers do but throughout SF one can find smaller houses that have subsided. They dealt with the problem by adjusting the sidewalk and adding ramps, some of which are absurdly steep now.

That explains so much.

Re: Millennium Tower is tilting, sinking

#147

Post by SeanDav »

> "The Millennium’s engineers anchored the building over a thick concrete slab with piles driven roughly 80 feet into dense sand. "To cut costs, Millennium did not drill piles to bedrock,"...

They built a skyscraper, on sand, in an earthquake zone!!! What the heck were they thinking?

Consider me completely unsurprised that the building is sinking and tilting.

Re: Millennium Tower is tilting, sinking

#148

Post by madaxe_again »

Someone1234 wrote: post #20
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…

Loving your attitude. I often feel like with a lot of building (big and small) there is insufficient evaluation of site factors. For example: Is there a hill above the site? THAT needs to be evaluated (sometimes they do, sometimes they don't). Is the site on a traditional floodplain? If so what actions have been taken to redirect the water flow? Does the system have the capacity to move the water away? Is the site it…

Watching videos of the aftermath of the floods in Maryland the other day was telling - the main street had been entirely washed away, exposing the foundations of the buildings. The modern constructions essentially had none and were hanging in mid-air over voids. The older buildings were all sat upon massive and well dressed masonry.

In short, people account only for risks they have experienced firsthand. When you don't see flash floods or earthquakes for generations, you get lax. Sadly we tend to wait until after disasters to learn, and yet we still forget.

Re: Millennium Tower is tilting, sinking

#149

Post by pja »

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?

I thought concrete buildings without steel frames came down instantly in earthquakes. What am I missing?

Concrete buildings without sufficient bracing at the corners where supporting beams meet floors fail pretty much instantly in earthquakes for sure, but if you put bracing supports in at the corners then that makes them much, much stronger. You’re probably thinking that concrete buildings just collapse from your experience of post-earthquake film footage from countries with poor governance where building firms can cheap out on the construction (lets save 15% of our material costs by skipping the bracing!) and their buildings inevitably collapse when the next earthquake comes along.

Re: Millennium Tower is tilting, sinking

#150

Post by rurounijones »

madaxe_again wrote: post #148
Someone1234 wrote: post #20

Earlier quoted context omitted.

Loving your attitude. I often feel like with a lot of building (big and small) there is insufficient evaluation of site factors. For example: Is there a hill above the site? THAT needs to be evaluated (sometimes they do, sometimes they don't). Is the site on a traditional floodplain? If so what actions have been taken to redirect the water flow? Does the system have the capacity to move the water away? Is the site it…

Watching videos of the aftermath of the floods in Maryland the other day was telling - the main street had been entirely washed away, exposing the foundations of the buildings. The modern constructions essentially had none and were hanging in mid-air over voids. The older buildings were all sat upon massive and well dressed masonry. In short, people account only for risks they have experienced firsthand. When you don…

DO you have a link with visuals? sounds fascinating.
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