Ah, yet another city/county commission involved in this cluster*; it's a wonder anything gets done in SF. IMO it is another distraction ploy away from someones brainless approval of the TTC platform design which currently has Caltrain and HSR use completely separated. This is grossly inadequate to support existing and future Caltrain service. Hopefully someone will rediscover crossovers.
The big losers, of course, are local transit patrons; construction of the planned pedestrian tunnel from the TTC to BART (which passes alongside the Millennium Tower) will not proceed until some resolution is agreed upon.
Links to my Google Maps ---> Sunset Route overview, SoCal metro, Yuma sub, Gila sub, SR east of Tucson, BNSF Northern Transcon and Southern Transcon *** Why you should support Ukraine! ***
Not much new except unding is being held up for additional engineering for the tunnel from the terminal to the present Caltrain terminal. Still a lot of wealthy persons are going to sue every body. But most likely the builder who used concrete instead of steel making it twice as heavy and not sinking piling to bedrock.
Wonder if ther would be some way to retro active instal bedrock pilings ? Probably some demo to get access ?
http://www.sfchronicle.com/politics/article/Sinking-SF-high-rise-prompts-panel-to-delays-9312425.php?ipid=gsa-sfgate-result
blue streak 1Now what happens ? 1. Unit values probably are going to drop like a rock ?
No, more like compressed concrete and fill. </rimshot> The Millennium Tower developers need to plan for the current second floor to be the new lobby. </rimshot> The cost of the Tower was about $350M (at least until now).
blue streak 12. Is this like many condo agreements that the owners will have to pay for repairs ? 3. What can the repairs be ? Pump in grout ? Sink cassions thru basement pad to bed rock ? Would like other ideas ?
Not sure if it will scale, but the actual Leaning Tower Of Pisa had its foundation stabilized successfully by removing soil from the opposite corner. If all else fails, one of the sfgate commentors suggested building flying buttresses across Mission St. The web site of the design firm (DeSimone Consulting Engineers) shows selected details. Hope DeSimone has a good 'Pearl Harbor' file on this project.
blue streak 14. Wonder if building developer disclosed to Transbay that building had sunk 10 " ? If they did not will it be very hard to hold Transbay at fault ? 5. Did Transbay general contractor determine what if any sinking of the building had occurred ?
The TJPA response to the Millennium Tower lawsuit has a good timeline of events and TJPA proactions, hope that the trial jury makes note of that. Per the above link in order to protect the Tower, a $58M buttress was built that "consists of 181 overlapping reinforced concrete piles, each seven feet in diameter and drilled to bedrock."
BTW there are other very tall structures under construction nearby to track; the Salesforce Tower at 415 Mission is adjacent to the Transbay Transit Center and Millennium Tower and will be the tallest building in San Francisco at 1070 feet.
August 8 update (sfchronicle): How Low Will It Go?
CSSHEGEWISCHCSSHEGEWISCH wrote the following post 2 days ago: It happened in Chicago in 1942. The steeple of Holy Name Cathedral acquired a slight but visible lean to the southwest at the time the State Street subway was bored in 1942.
When the Fed's replaced the old Chicago Post Office building in downtown Chicago (Between Clark & Dearborn, and Adams & Jackson) they started excavating the basement space and before they put shoring in, Jackson St started sinking.The new buildings on the site did have cassions down to bedrock but the 'BLUE CLAY" that constitutes most of the top fifty feet of the soil in downtown Chicago is like playdough. It squeezes and flows like braunswager out of its tube when under pressure. So when the land under Jackson Blvd no longer had any side support, it sank. Slowly but traffic pushed and the pavement over weeks sagged and cracked. After it was noticed, sheet pilings were driven down at the property line and strong support tubes were used to brace the the sheet pilings. The buildings constructed after the Federal Buildings (like the Sears {Willits} tower) were built all included the sheet pilings when excavation started and all also are built with cassions to bedrock. It looks like they use old tank cars as "sleeves" to line the cassion holes as they drill them.
Most houses are supported on footings on stable soil. Some buildings are supported on floating foundations such as Frank Lloyd Wright used for the Imperial Hotel in Japan which was designed to support the hotel and survive (it did) an earthquake. The San Francisco case looks like the designer was using a floating foundation design but overloaded it. The soil could not support the load and the building weight caused the soil to be displaced allowing the slow sinking of the building. I wonder what soil tests were done before the design and why the engineer didn't realize the problem.
Sinking concrete pilings to bedrock is standard practice for high-rises in Chicago. Some go down about 150 feet or more below grade level. I'm not sure why this wasn't used in this case.
Paul of Covington Now it is 16 inches lower. It sank ten inches the first two years then six inches in the last six years. -snip- Did the sinking slow down because of ground compression,or did the transit center work slow it down?
Now it is 16 inches lower. It sank ten inches the first two years then six inches in the last six years.
-snip-
Did the sinking slow down because of ground compression,or did the transit center work slow it down?
My intro to Materials Science class at Cal had a couple of days or so on soil mechanics. One topic was settling in the Bay fill where the settling progresses logarithmically, i.e. fast at first and slowing as time goes on. A specific example was the Toll Plaza for the Bay Bridge, which had been completed in the late 1930's and was still measurably settling when I was taking that course in 1973. The settling of the tower seems to be following this rule.
With 20/20 hindsight, it does sound like sinking some pilings to bedrock would have been a good idea. That would have likely required that the entire weight be born on the pilings as the settling process would eventually transfer most/all of the weight to the pilings.
Randy Stahl Number 6 . E Bay stores selling wooden furniture shims will do well
Number 6 . E Bay stores selling wooden furniture shims will do well
Randy,
Building is kind of heavy, so probably need oak wedges like the wrecker carries, or did back in the day.
Mac
blue streak 1 Now what happens ? 1. Unit values probably are going to drop like a rock ? 2. Is this like many condo agreements that the owners will have to pay for repairs ? 3. What can the repairs be ? Pump in grout ? Sink cassions thru basement pad to bed rock ? Would like other ideas ? 4. Wonder if building developer disclosed to Transbay that building had sunk 10 " ? If they did not will it be very hard to hold Transbay at fault ? 5. Did Transbay general contractor determine what if any sinking of the building had occurred ?
Now what happens ?
1. Unit values probably are going to drop like a rock ?
2. Is this like many condo agreements that the owners will have to pay for repairs ?
3. What can the repairs be ? Pump in grout ? Sink cassions thru basement pad to bed rock ? Would like other ideas ?
4. Wonder if building developer disclosed to Transbay that building had sunk 10 " ? If they did not will it be very hard to hold Transbay at fault ?
5. Did Transbay general contractor determine what if any sinking of the building had occurred ?
Assuming these figures are correct:
When the building was built in 2008, the builders predicted it would sink six inches in its lifetime.
When work began on the transit center in 2010 (2 years later) it had sunk ten inches. (Maybe its lifetime was about one year.)
I'm wondering if they breathed a sigh of relief when work started on the transit center, and there was someone to blame.
_____________
"A stranger's just a friend you ain't met yet." --- Dave Gardner
The Old Terminal was a classic in a town that has no sence of history-
https://www.google.com/search?q=transbay+terminal&safe=strict&rlz=1C1KMZB_enUS704US704&espv=2&biw=1600&bih=752&source=lnms&tbm=isch&sa=X&sqi=2&ved=0ahUKEwi5mLKVsKbOAhWDSyYKHbvCDNIQ_AUICCgD&dpr=1#imgrc=iemeViGQaWteRM%3A
blue streak 11. How is a 2 inch lean measured ? Surface to top of building ? 2. According to the articles and map the lean is away from the Transbay terminal ? 3. Maybe the terminal buttress did its job too well ?
San Franciscans are perhaps the most clever and creative people I've ever met. It can't be long before we hear the promotion of a new tourist attraction, "The Leaning Tower of San Francisco." "First there was Coit Tower, now there's the Leaning Tower of San Francisco!"
Perhaps some engineers will think BIG and build a flying buttress or two across Mission Street to keep the building from leaning some more. Such a buttress might have to be 20 or more stories high! Just imagine!
A new skyscraper that sinks and leans. Aren't you glad you don't have to pay the mortgage on this building?
We supposedly love accountability in America, but apparently not for highly paid professionals. I bet no one is ever named, shamed, fined, or de-licensed, let alone jailed for this example of massive professional ineptitude or malfeasance.
Poor people really are held to a totally different standard of justice.
According to this news on MSN, the builders had predicted that the building would sink six inches in its lifetime, but it had already sunk ten inches when work started on the transit center in 2010.
http://www.msn.com/en-us/news/us/contractors-luxurious-new-san-francisco-high-rise-is-sinking-tilting/ar-BBv96fF?li=BBnb7Kz
Some questions for inquiry probably others as well.
1. How is a 2 inch lean measured ? Surface to top of building ?
2. According to the articles and map the lean is away from the Transbay terminal ?
3. Maybe the terminal buttress did its job too well ?
3. Did the seller's disclosure document to buyers note that total anticipated sinking would be just 10 inches but as of now over 16 inches ? What was the sinking rate disclosed to buyers ??
4. Did disclosure document state building on pilings that were not sunk to bedrock ?
5. Did disclosure state building would / is heavier than normal steel buildings of same height ?
6. Did disclosure state building is in a potential liquidfaction zone and did the area liquify in the 1906, 1989 quakes ?.
matthewsaggie The Planning Commission vote would have been in reference to the land use for the building, not the technical design and construction techiques. They have no liability unless they went around some policy they had in place prohibiting such a large building in an old fill area. On the other hand, the SF building standards department (whatever its properly called), along with the design and construction engineers probably should have their checkbooks out.
The Planning Commission vote would have been in reference to the land use for the building, not the technical design and construction techiques. They have no liability unless they went around some policy they had in place prohibiting such a large building in an old fill area.
On the other hand, the SF building standards department (whatever its properly called), along with the design and construction engineers probably should have their checkbooks out.
Nope, no department other than the S.F. Planning Commision would have approved the design, it's just the way thing work out here and it keeps the process simpler for developers, however it does make it harder for those on the Planning Commision as they have to perform two jobs instead of just one.
Here is an article with a picture of what happens to buildings when an earthquake causes liquefaction of saturated soils, like what the towers were built on.
https://en.wikipedia.org/wiki/Soil_liquefaction
SF also had these type of problems in the 1989 earthquake.
MikeF90 vsmith The foundation of the Tower, however, consists only of a concrete slab supported by short piles that fail to reach the bedrock below. That foundation is inadequate to prevent settlement of a building with the weight of the Tower." That is 99% the more likely culprit, aka cheap corner cutting developer. That, and the S.F. Planning Commission voting 4-1 to approve the deficient design. The sfgate article has a map showing a trace of the former shoreline. Excavations in this area occasionally uncover old ships.
vsmith The foundation of the Tower, however, consists only of a concrete slab supported by short piles that fail to reach the bedrock below. That foundation is inadequate to prevent settlement of a building with the weight of the Tower." That is 99% the more likely culprit, aka cheap corner cutting developer.
That, and the S.F. Planning Commission voting 4-1 to approve the deficient design. The sfgate article has a map showing a trace of the former shoreline. Excavations in this area occasionally uncover old ships.
Gee - building into what had been the Bay. Who would ever have thought the land would be unstable. [/sarcasm]/
Never too old to have a happy childhood!
The lawyers have got to be salivating by the bucket full! A good, and rich, time will be had by all. Popcorn, popcorn.
vsmithThe foundation of the Tower, however, consists only of a concrete slab supported by short piles that fail to reach the bedrock below. That foundation is inadequate to prevent settlement of a building with the weight of the Tower." That is 99% the more likely culprit, aka cheap corner cutting developer.
Have fun with your trains
When did construction on the terminal begin? Is there any record of how much the building has sunk each year since its construction?
Some one has a lot of explaining to do unless they have already left the country .
Correct this if wrong but did the worse damage during the 1906 earthquake occurr to building built on fill and sediment and not anchored to bed rock ?
Wonder if the dewatering for the transbay terminal caused the pad to sag ?
Another question is how deep is the lowest basement and how does that compare to the Terminal ? Is the high rise's total weight more or less than excavated soil ?b
It happened in Chicago in 1942. The steeple of Holy Name Cathedral acquired a slight but visible lean to the southwest at the time the State Street subway was bored in 1942.
Real nice. This is something you expect in a third world country NOT the United States. I thought the SFO high rise codes was they were to sink piers to the bedrock (or am I thinking Manhattan?), if so, how can this happen?
http://www.foxnews.com/us/2016/08/01/swanky-san-francisco-high-rise-sinking-tilting.html
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