Sinking skyscraper in San Francisco

[Buster28]

Probably some of us have already heard about this story, but my guess is that most have not. The 645 foot tall luxury residential Millennium Tower (same height as 801 Grand in Des Moines), finished in 2009, has sunk 16" into the ground and is leaning 2" off vertical since then. Turns out the pilings that were used to set the foundation on don't even go down 100 feet into the mud (bedrock is about 200 feet down in that location). How this tower ever was approved as-is by a city known for rather extreme (and logical, considering the unpredictable seismic activity in the region) building ordinances and regulations, I do not understand. Initially, blame was placed on the nearly topped-out 1070 foot tall Salesforce Tower across the street, saying the excavation caused the neighboring land to slump, but this was proved to be not true.

http://abcnews.go.com/Technology/wireStory/san-franciscos-sinking-tower-space-43831433

I have always had a love of skyscrapers and the technology and engineering that goes along with them, so I find unusual stories like this even more fascinating. I cannot imagine being one of the people who paid millions for their properties in this tower and the feelings of anxiousness from living there. Would it survive a strong quake? The builders say it's safe, but I don't see how they can say it with a straight face, knowing what they know that it's literally sitting on mud and century-old landfill.

 

[Cycsk]

Fascinating. This level of liability is incredible.

How do you measure something like a sinking building? Can you put a mark on the building and see it an inch above the sidewalk a year later? Or does the sidewalk sink with the building? If so, does the sidewalk sink below the street level? Sixteen inches would be pretty noticeable.

 

[CY88CE11]

Fascinating. This level of liability is incredible.

How do you measure something like a sinking building? Can you put a mark on the building and see it an inch above the sidewalk a year later? Or does the sidewalk sink with the building? If so, does the sidewalk sink below the street level? Sixteen inches would be pretty noticeable.

My guess would be something more sophisticated like measuring against sea level. The sidewalk should be independent from the building, but it's likely sitting on a subgrade that's also poor.

 

[Buster28]

Fascinating. This level of liability is incredible.

How do you measure something like a sinking building? Can you put a mark on the building and see it an inch above the sidewalk a year later? Or does the sidewalk sink with the building? If so, does the sidewalk sink below the street level? Sixteen inches would be pretty noticeable.

The sinking has been noticable at street level from the start. Apparently, they've had to make 'adjustments' to the sidewalk where it meets the entrances into the tower. I don't know if steps or ramps or what has been added, but it would have to be a continual process if it's still dropping. Plus, I'd be worried about utilities coming into the building, specifically gas lines. I've never heard people discuss that aspect of this situation. Aside from a quake, I would think that could be the most serious issue they're facing.

 

[coolerifyoudid]

Incredible story. Thanks for posting it. Dropping a foot and a third in seven years is scary. Add in San Fran being in a seismic hotbed, and this screams impending disaster.

 

[Buster28]

This is a photo of the Millennium Tower sandwiched between Salesforce (tallest in the center of the photo) and 181 Fremont (to the right), just for perspective.

 

[Cycsk]

Here is an interesting story of them finding and correcting similar problems when building the John Hancock Center in Chicago.

http://www.360chicago.com/building-history/

 

[3TrueFans]

Will Italian tourists come here to take pictures pretending to hold it up?

 

[NickTheGreat]

Ooops.

 

[CY88CE11]

The sinking has been noticable at street level from the start. Apparently, they've had to make 'adjustments' to the sidewalk where it meets the entrances into the tower. I don't know if steps or ramps or what has been added, but it would have to be a continual process if it's still dropping. Plus, I'd be worried about utilities coming into the building, specifically gas lines. I've never heard people discuss that aspect of this situation. Aside from a quake, I would think that could be the most serious issue they're facing.

Gas, water, sewer are all in danger with that much settling. Gas is obviously a big concern because at some point, your pipe deflection is going to be too much, and it'll leak/break/burst. Sanitary sewer will at some point be sloping back into the building and causing issues. Not likely yet, but at some point.

 

[jbhtexas]

Will Italian tourists come here to take pictures pretending to hold it up?

Holding it up...no; pushing it over...yes!

 

[BoxsterCy]

Gas, water, sewer are all in danger with that much settling. Gas is obviously a big concern because at some point, your pipe deflection is going to be too much, and it'll leak/break/burst. Sanitary sewer will at some point be sloping back into the building and causing issues. Not likely yet, but at some point.

Gas? Not a problem.

 

[coolerifyoudid]

Gas, water, sewer are all in danger with that much settling. Gas is obviously a big concern because at some point, your pipe deflection is going to be too much, and it'll leak/break/burst. Sanitary sewer will at some point be sloping back into the building and causing issues. Not likely yet, but at some point.

City officials are already talking about a way to channel sewage into Oakland

 

[somecyguy]

Look past even those major infrastructure issues such as plumbing and sewer, etc; imagine the walls in your 750K condo cracking everywhere. Sitting on your couch and watching TV leaning to the side. Laying in bed at an angle. All the annoyances you would have to deal with daily.

 

[CY88CE11]

City officials are already talking about a way to channel sewage into Oakland

The Raiders play at home Sunday, so that shouldn't be a problem.

 

[coolerifyoudid]

Look past even those major infrastructure issues such as plumbing and sewer, etc; imagine the walls in your 750K condo cracking everywhere. Sitting on your couch and watching TV leaning to the side. Laying in bed at an angle. All the annoyances you would have to deal with daily.

Solution:

 

[Cycsk]

Would a two-inch lean at the top of the building actually make a marble roll toward the low side? Seems like that is more an issue of whether the floor itself is level. The marble probably rolls the other way in other rooms and on other floors.

 

[Buster28]

This is a photo of the Millennium Tower sandwiched between Salesforce (tallest in the center of the photo) and 181 Fremont (to the right), just for perspective.

Something I also find interesting is that the 800 foot tall 181 Fremont building in this photo has no central reinforced concrete core for the elevators. It's literally just steel frame throughout, all the way up to the top.

 

[weR138]

https://architecturefarm.wordpress.com/2016/09/15/floating-foundations-out-west/

From Tom Leslie in the Architecture Dept.

 

[Cycsk]

https://architecturefarm.wordpress.com/2016/09/15/floating-foundations-out-west/

From Tom Leslie in the Architecture Dept.

Not surprised that Tom Leslie is in this discussion. I had the privilege of talking Chicago architecture with him once. Glad to have him on faculty.