SF tower settlement
SF tower settlement
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RE: SF tower settlement
I sure wouldn't want to be in a building like that during the soon-to-happen next Big One.
Keith Cress
kcress - http://www.flaminsystems.com
RE: SF tower settlement
Max condo value is $10M...
I don't know if the sand is saturated, but, there could also be problems during a seismic event...
Dik
RE: SF tower settlement
Professional and Structural Engineer (ME, NH, MA)
American Concrete Industries
www.americanconcrete.com
RE: SF tower settlement
Link
RE: SF tower settlement
Trouble in paradise that's for sure.
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RE: SF tower settlement
But I had nothing to do with this settlement.
RE: SF tower settlement
That's a pretty strong statement for the transit authority to make...
Time to grab some popcorn.
RE: SF tower settlement
http://www.davidrumsey.com/luna/servlet/detail/RUM...
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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RE: SF tower settlement
I suspect a lot of lawyers will make a lot of money out of this and that's about the only positive aspect all the way around.
RE: SF tower settlement
I guess if you consider such a thing a positive...
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I was a concrete inspector on the BART Lower Market Street Station. I inspected the concrete used in the slurry walls on the south side of Market, 720 feet away from 301 Mission. As I mentioned, I met my wife here. Suppose I was watching her instead of the concrete pour. And as a result, after 45 years of seepage from bad concrete, the millenials had their building damaged?
RE: SF tower settlement
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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RE: SF tower settlement
Well, in your case, let's hope the statute of limitations for arousal-induced negligence has expired.
RE: SF tower settlement
Keith Cress
kcress - http://www.flaminsystems.com
RE: SF tower settlement
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I'm not really trying for some witness per diem, honest.
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Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: SF tower settlement
Excavation is just like BART - cut and cover using soldier piles and concrete slurry walls. Big HSS struts supporting walls during excavation. The excavation is bigger than Lower Market. I presume the walls are structural like on BART, a first at the time. I also read that they consider the Lower Market Street Bart Station to be obsolete. Hey, I just built that thing! The concrete is just reaching its prime.
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Many investment opportunities here...
Mike McCann, PE, SE (WA)
RE: SF tower settlement
Keith Cress
kcress - http://www.flaminsystems.com
RE: SF tower settlement
https://www.google.com.au/search?q=Bologna+leaning...
RE: SF tower settlement
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RE: SF tower settlement
Mike McCann, PE, SE (WA)
RE: SF tower settlement
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You guys crack me up.
Keith Cress
kcress - http://www.flaminsystems.com
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RE: SF tower settlement
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RE: SF tower settlement
Keith Cress
kcress - http://www.flaminsystems.com
RE: SF tower settlement
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STF
RE: SF tower settlement
Seems like there will be a LOT of plumbing and electrical issues here too, not just structural.
Mike McCann, PE, SE (WA)
RE: SF tower settlement
RE: SF tower settlement
It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.
RE: SF tower settlement
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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RE: SF tower settlement
Could the right "seismic event" cause liquifaction of the underlying sand and cause a rapid decline in building stability, or are the underlying ground specifics not appropriate for such a reaction?
Dan - Owner
http://www.Hi-TecDesigns.com
RE: SF tower settlement
It doesn't have to be either/or. We all take it very seriously I'm sure. Especially the structural engineers among us.
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RE: SF tower settlement
RE: SF tower settlement
Suffice it to say that there are a lot of possibilities. You won't find any definite answers here, and as discussed above, this will take years to resolve, if ever.
RE: SF tower settlement
RE: SF tower settlement
Mike McCann, PE, SE (WA)
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I can't believe 16 inches of settlement! I mean are the water/sewer connections failed?
f-d
ípapß gordo ainÆt no madre flaca!
RE: SF tower settlement
Yes, the service connections would present big problems, as would probably a lot of other relationships with the surrounding ground level surfaces.
In a situation like this, servioeability/settlement failure is overriding, and strength is of less importance. Too much settlement can indeed be evidence of negligence. That remains to be determined in this case.
RE: SF tower settlement
RE: SF tower settlement
John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
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The secret of life is not finding someone to live with
It's finding someone you can't live without
RE: SF tower settlement
In just the last moderate SFO earthquake in 1989, Mission District buildings on fill dirt in the bay DID collapse and sink into the ground just for that cause. Saw videos of the entire first floor below ground.
RE: SF tower settlement
Sorry to confuse. . .
f-d
ípapß gordo ainÆt no madre flaca!
RE: SF tower settlement
http://www.pressdemocrat.com/home/6370566-186/lean...
My favorite line,
"said Dodson, an attorney who has helped organize homeowners lawsuits. 'I can tell you that satellite data is way more accurate that digging in the dirt.'" Translation: We don't need no stinkin' surveyors, we got Google maps!"
RE: SF tower settlement
Mike McCann, PE, SE (WA)
RE: SF tower settlement
RE: SF tower settlement
- Condominium
- Flaws that might be huge or not.
- Extremely rich entitled tenants.
Many lawyers are going to get very rich.RE: SF tower settlement
https://www.bloomberg.com/news/articles/2017-02-01...
RE: SF tower settlement
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RE: SF tower settlement
Dik
RE: SF tower settlement
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RE: SF tower settlement
RE: SF tower settlement
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RE: SF tower settlement
Yes
Dik
RE: SF tower settlement
TTFN (ta ta for now)
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RE: SF tower settlement
RE: SF tower settlement
Dan - Owner
http://www.Hi-TecDesigns.com
RE: SF tower settlement
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RE: SF tower settlement
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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RE: SF tower settlement
Dik
RE: SF tower settlement
Dan - Owner
http://www.Hi-TecDesigns.com
RE: SF tower settlement
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RE: SF tower settlement
RE: SF tower settlement
I will only read this thread for shear amusement from now on.
STF
RE: SF tower settlement
Treadwell & Rollo, now part of Langan Engineering. ENR link re aquisition and Langan Engineering website.
Sadly, Vincent DeSimone (founder of DeSimone Consulting Engineers) passed away in November, 2016. Memoriam
RE: SF tower settlement
RE: SF tower settlement
I kind of sympathize with the guy, no one welcomes you reviewing scope beyond your contract.
RE: SF tower settlement
But the lean is 2".
For a 645 ft. (196.6m) tall building the ACI 117 tolerances (for construction) would be on the order of 3" to 6" depending on the direction of the measurement.
So a 2" "lean" here doesn't sound too bad.
For typical wind load deflections, a tall building like this might lean L/500 = 15 inches.
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RE: SF tower settlement
And non-other than Prof Jack Moehle of UC Berkeley:
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Keith Cress
kcress - http://www.flaminsystems.com
RE: SF tower settlement
RE: SF tower settlement
Even as a rookie, if I had been asked to provide an engineering report for a building with substantial subsidence, I would have raised a bit of a flag about having a geotechnical report included with the overall report (and that is not hindsight being 20/20). Because subsidence was a key issue, this would be a significant part of the engineering report.
Dik
RE: SF tower settlement
A somewhat misleading quote on behalf of Cubed SF, IMO. A geotech engineer was NOT hired as part of the internal peer-review (which was primarily initiated to look at the structural framing system pertaining to seismic), however the project did have a geotech engineer - namely, Treadwell & Rollo, as part of the project design team.
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Dik
RE: SF tower settlement
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There was some interesting background information given on the 80 Natoma project in the testimony, which underwent peer-review about the same time as the Millennium Tower project (mid-late 2004).
RE: SF tower settlement
Good link, and a bit long. It explains why the documents weren't sealed and that the prof wasn't a registered SE. In some jurisdictions, a professional can be held to the same standard if the documents are not sealed. I have to review it again; it appeared that the politician stated that the foundation peer review had been undertaken by the prof and this went unchallenged(53 minutes into the hearing). It appeared that the whole purpose of the dialogue was to distance the city from the problem.
Dik
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RE: SF tower settlement
http://sfist.com/2017/03/14/millennium_towers_eart...
RE: SF tower settlement
Dik
RE: SF tower settlement
http://www.nbcbayarea.com/investigations/More-Bad-...
Dik
RE: SF tower settlement
Dik
RE: SF tower settlement
dik: What is your article source for this 'revised' tilt, and what is the magnitude of the 'revised' vertical settlement?
RE: SF tower settlement
SAN FRANCISCO (KRON) — It has become known as San Francisco’s sinking tower, and attorneys representing those who live in the Millennium Tower are seeking more than $200 million from those they say are responsible for the building sinking and tilting.
The tower is sinking 16 inches and tilting 12 inches at the penthouse level, attorneys said.
Most of the other articles indicate 2" still and are dated a year ago; it is not known what actual measurements have been taken.
Dik
RE: SF tower settlement
http://kron4.com/2017/03/29/attorneys-san-francisc...
RE: SF tower settlement
RE: SF tower settlement
I am reminded that the lowest accessible levels in Venice, Italy were at one time second and third floors.
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RE: SF tower settlement
Dik
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RE: SF tower settlement
Dik
RE: SF tower settlement
And DeSimone Consulting Engineers can give their project it's own twist on things. Link
Tubex Grout Injected Piling is probably what they are thinking.
Link
Link
RE: SF tower settlement
Dik
RE: SF tower settlement
"Millennium Tower, the tony but troubled downtown high-rise that made international headlines last year when the secret got out that it’s slowly sinking and tilting, returned to its customary place in the news late Tuesday when NBC Bay Area revealed that the building “has tilted two and half more inches in just the first half of this year, according to new monitoring data.”
Says the affiliate:
The data, compiled by the ARUP engineering firm brought in by officials of the nextdoor Transbay transit terminal project, suggest the structure is tilting twice as fast as it had been in earlier ARUP data.
It is now listing at least 14 inches toward the massive Salesforce building going up nearby on Mission Street. The data also show the building has sunk close to 17 inches at its low point, settling about an inch since the problem emerged last year.
Supervisor Aaron Peskin, who has conducted a series of City Hall inquisitions trying to figure out who dropped the ball on the building’s design, took to Twitter to voice his exasperation.
“Accelerated sinking continues,” tweeted Peskin, then sarcastically referenced Mayor Ed Lee’s efforts last year to reassure U.S. Senator and former Mayor of San Francisco Dianne Feinstein that the city could manage the building’s woes.
In comments to NBC Peskin compared his hearings (which he vowed to continue) as “yelling into the wind.”"
Link: https://sf.curbed.com/2017/7/19/15998338/millenniu...
RE: SF tower settlement
Keith Cress
kcress - http://www.flaminsystems.com
RE: SF tower settlement
RE: SF tower settlement
The parking garage basement of the Mid-Rise Tower was a 75 foot deep excavation. The garage foundation looks to be sitting on a lens of clay while the Tower foundation is on sand. The High Rise sits on 950 - 60 to 80 foot piles with a 10ft thick pile cap with a 35ft to 50ft deep excavation. Unknown is if the length of the piles is quoted as from original ground, top of the pile cap or from excavation grade.
Here is a link to a paper on the structural design of the tower. It doesn't mention the extensive use of GFRP. Link You can see the GFRP in the connection of the Steel Link Beam; here Link & again here Link
This link from CRSI gives some good details about the overall project. Link The first photo on the page gives a good idea of the concentration of piles under the tower. The 4th photo in the series is the podium/mid-rise basement/parking garage. The basement/parking garage photo is from around Summer 2007 and by this stage the very heavy Tower was topping out. The basement used an integral waterproofing admixture, so there isn't anything to stop water once the cracks grow too large. Here's my best 'eye-ball gestimate' of where the 10ft thick pile cap is in relation to the garage excavation. Since the building is leaning away from the garage, you have to wonder if this is when the tilting started. The tower foundation is supposed to be designed for 14kpsf. Wouldn't this be a vulnerable time for the tower to take on a slip circle tilt? If 7ft diameter concrete piles 200ft deep & anchored in bedrock on the South side of the property aren't preventing a Northern tilt, then how is a 75ft deep concrete box on the East side of the property, possibly built on top of a clay lens, suppose to prevent the building from tipping to the West?
The Tower was completed in 2009 and the Transbay Authority, TJPA began excavating next to the Tower in 2011. Before doing so & exclusive to the Millennium Tower/TJPA property line, TJPA took the preventative measure of drilling 181 7-foot diameter overlapping concrete piles all the way to bedrock at a cost of $58 million. Link The Transbay Center excavation is 65ft deep and runs 4 blocks, including along the South side of the Millennium property, with both the Transbay excavation & Millennium Tower project ending at Beale St. Link According to Millennium Tower's attorney (HOA?), the Transbay site has dewatered 5 million gallons/month for most of its duration & the water table has dropped 20 feet. As the TJPA states, their hole in the ground is the size of 120 3 meter deep Olympic sized swimming pools. Then again thier dewatering is enough to fill over 79 of those pools to date. Still, the HOA at Millennium Tower should be worried when the TJPA finally stops dewatering because those cracks in their basement garage are going to be fountains when the water table is recharged. If the dewatering is affecting the clay maybe the Tower will rise back up when TJPA stops dewatering?
The tower had sunk 12 of its 16 inches before the Transbay Center excavated next to the building. Refutation from the TJPA: Link As TJPA sees it, the Tower is just too heavy & sinking into the mud. They are probably right. The Old Bay Mud may be behaving like a pseudo-plastic and yielding gradually, while the garage sits on a (fulcrum) lens of another clay deposit and the pile cap of the tower is squishing the water out of a sand pile.
Maybe I don't understand well enough the nomenclature of Geotechnical Engineering but when I started looking for information on the possibility that disturbed hence less consolidated clay might not produce an elastic response but instead display a prolonged visco-elastic or thixotropic phase; there was very little research. Just bits here and there that the phenomenon does exist in some clay and was noted after the Kobe Quake. That might suggest that resistance piles driven through sand in to dense clay might not be as resistant as planned and that after an earthquake when the clay has experienced liquefaction could, under sufficient load, remain unstable. There is a fair amount of information about clay behavior and high initial shear resistance with some elastic recovery as high as 99% but not all clay has this recovery shear strength. Include the high initial shear resistance with a dramatic loss of shear strength and lesser resistance on recovery & the recovery stage starts looking more and more like thixotropic/visco-elastic behavior and that means deformation under load/creep.
Considering that the City of San Francisco has prior experience with the soils in the area, BART & Muni tunnels & underground stations AND both the City & the Developer knew in advance that the Transbay Center was going to be built, why the developer & why the City didn't determine to build a tower that could stand all on its own is hard to fathom. Seems TJPA was the only party think holistically and to act with anticipation or practice any preventative measures. If I was TJPA, I'd tell the HOA, the Developers & the City of San Francisco that when they have all each spent $58 million, then the TJPA will be willing to discuss what part TJPA will thereafter play. Link
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Multimillion-dollar condos in tilting skyscraper called nearly worthless
RE: SF tower settlement
I'm not a highrise expert, only done 30 storeys, but, looking at the soil profile... I wouldn't like to construct anything tall or heavy in that stuff... there may have been a really good reason that everyone else went to bedrock. Also, only done a little seismic stuff and I have no idea of how a building, founded in that 'stuff' would behave during a seismic event...
There are more clever people out there than I would have imagined.
Looks like they terminated the piling before they hit the 'Old Bay Clay'...
Dik
RE: SF tower settlement
Dik
RE: SF tower settlement
One of the arguments that Millennium Partners has issued regarding their liability is that the residents of Millennium Tower, in effect OWN the tower & the tower's problems.
RE: SF tower settlement
- Condominium. Check
- Extremely wealthy owners. Check
- A good portion of them are probably lawyers. Check
- Owners heavily inve$ted in the project. Double Check
- And real damages. Check
.This one will be in the news and courts for many years. There will be quadruple digit replies to this thread before it goes away.
RE: SF tower settlement
Dik
RE: SF tower settlement
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Dan - Owner
http://www.Hi-TecDesigns.com
RE: SF tower settlement
Keith Cress
kcress - http://www.flaminsystems.com
RE: SF tower settlement
Dik
RE: SF tower settlement
Here is a settlement timeline over a period of near 10 years from this source: Link
For combined tilt-settlment data I think ARUP have data dating back to 2009.
RE: SF tower settlement
The Transbay Authority didn't just build a wall, they heavily buttressed the wall. This is why Millennium Partners & Millennium residents focus on dewatering, because the wall works. Millennium residents also accuse the Transbay Authority of attempting to hide the shifting but it may be that the TJPA was unaware of the preexisting condition of the Tower's accelerated settlement when they entered into an easement contract with Millennium Partners and were alarmed at what they were seeing from early monitoring results. My guess is TJPA approached Millennium Partners and Millennium Partners wanted to keep the situation private.
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What is very surprising is the effect the execution of the easement agreement had on the settling rate.
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Dik
RE: SF tower settlement
RE: SF tower settlement
Attached is a copy of the July 2017, City of San Francisco Safety Review of the Millennium Tower Link
The report is the City of San Francisco's interpretation of the 2016 Structural Review with requested follow up analysis performed by Simpson Gumpertz & Heger on behalf of Millennium Partners and is seen by some as a walk back from SGH's 2014 review that concluded 8 of the Outrigger Columns (upper floors) would be over stressed during an earthquake. The 2014 report was seen by some engineers as a sign the building could be "Red Tagged" after a major quake. Link In the City's July 2017 review the focus is on the Outrigger Coupling Beams.
The City of San Francisco vis-a-vis the SF Dept. of Building Inspection, SFDBI has two strikes against it in this affair.
Firstly, the City had previously halted work on a project of almost identical design, 50+ story, concrete building with friction piles (geo-tech by Treadwell & Rollo) at 80 Natoma, citing 'new information' that it was too heavy and sink too much. 80 Natoma was a property directly over the favored path of the CalTrain underground extension to the planned Transbay Center transportation hub. If the tower was built it would be impossible to come back later and tunnel under such a heavy building resting on friction piles. The developer refused to sink piles to bedrock citing delays would compromise project funding. The site was eventually purchased via Eminent Domain for between $58 & $90 million. More than a little speculation circulated that the whole project was always a shakedown.
Secondly, the City's failure to look into the accelerated sinking of Millennium Tower, AFTER they had initiated inquiry & subsequently approved the structure for occupation (sale of condos).
The City of San Francisco & Millennium Partners have a common interest in dissociating themselves from blame. Both Millenium Partners & SFDBI claim there was no requirement for the developer or the Peer Review panel to consider the Transbay Project next door. Link That seems to be in conflict with the Mission Street Development LLC (Millennium Partners) 301 Mission Street - Environmental Impact Report that cited the adjacent proposed Transbay Center project Link and SFDBI's actions at 80 Natoma.
RE: SF tower settlement
Sounds great, and at an inch per year, who knows... settled 18" so far.
Dik
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All was well July 28th; July 29th is out of scope. Does the report contain any useful information?
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Dik
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Early into the pile driving - Photo (A): Link
Looks like pile driving started in the Northwest corner of the lot: Photo (B): Link
Pile driving complete Photo (C): Link
ARUP's illustration of the relationship of the Transbay Center excavation & Millennium Tower Photo (D): Link
Photo of full excavation next to Millennium Tower - Link
In photo (B) note the high concentration of soldier piles on the left side of the photo. In photo (C) the soldier pile are capped with a steel beam & rakers tie to a stepped perimeter wall. What is different about this section of the shoring?
In this Old Tranbay Terminal demolition phase photo you can see that ground water is somewhere around 7 to 12 feet below grade. Millennium Tower is to the right in the photo. The area was used for staging for most of the Transbay Center project. Soil stabilizing fabric was laid & a waste slab poured.
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The seminar was a live webcast, however it was recorded and is available for public viewing here:
https://drive.google.com/file/d/0B6Cv_TTKSlYiMWdZS...
I have yet to view the presentation.
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Dik
RE: SF tower settlement
Maybe it is just his accent, but some of his terminology is not that of a structural engineer.
He speaks about conflict of interest. I think at this point, anybody from UC Berkeley is conflicted.
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With the WTC, there was an excellent thread on Eng-tips that disappeared... don't know if the webmeister was asked to remove it and 'turn it over' or what... it was just gone. A lot of what was discussed on the presentation was there... I didn't realise that a permit was not required and that stuff was 'approved on the fly' by those with a vested interest.
I'm not a geotekkie, and unlike Moehle, I would not have signed off on the foundations... The foundations would have been my first concern. My first posting on this thread ended with, "I don't know if the sand is saturated, but, there could also be problems during a seismic event..." and, is still a concern, and very likely the mode of failure, and, maybe after the first floor is at grade. I'm surprised that the SEAOC has not done a study... if a potential life safety issue, then they are 'obligated' to look into it...
Dik
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He said more than once that there was "no structure" in the WTC, and no columns. Rubbish. And I would take the "no permit" thing with a grain of salt.
Anyone with that many pictures of "my projects", bridges and buildings, is a horn blower.
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As to codes... I don't know, except, that I have never heard a prior reference to design requirements, and never considered that there were no permits if that's the case.
Whatever the issues, there are/were serious oversights made with both structures... not common, in these environs, to design for
747767 loading... I thought and still do that using trusses from a core to an outside 'tube' structure was a neat way to do tall buildings... Light weight and using the outside 'skin', about as stiff as you could make it.Dik
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Disagree about the trusses, if you mean bar joists. They didn't adequately connect the exterior tube to the core, and that is a big reason for the collapse.
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Dik
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womanprofessor scornedRE: SF tower settlement
"where some California engineer reckons that flat slabs should be outlawed in seismic areas. I would agree" Can you elaborate? I would think that the reduction in mass would be beneficial.
Diiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiik
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Dik
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Professors, particularly at upper crust universities blow the horn loudly because it is a pretty cut throat environment despite their use of reserved social graces. If you are not publishing, consulting, designing or patenting, then you had better be stealing the ideas of you grad students or you are not going to stick around long. Unless of course you have a visiting professor gig and then you can go on sabbatical out of the country, while the students pay tuition for your salary & the house the University paid for, which sits vacant for a year - (This really happens).
Seems professor, Abolhassan ASTANEH was hired for about a week by some of the condo owners, before he made this presentation. It really doesn't matter if the professor can generate ground motion modeling to prove that the building is not as safe as De Simone designed and SG&H have asserted. It is safe according to the design criteria supplied by the 1997 UBC and made law at State, County & City levels and was in effect when the permit was issued. Prof. Jack Moehle is not the Engineer of Record so his PEER review is just that, a review, not a absolute declaration. Still he is talking out of both sides of his mouth. The STRUCTURAL ENGINEERS ASSOCIATION OF NORTHERN CALIFORNIA 2015 SEAONC "Guidelines for the Use of Geotechnical Reports" Link , both supports his initially stated position regarding his qualification, "that he looked no further than the tower foundation" & it doesn't. I think he is one of many, who were very excited at building a tall "poured-in-place concrete" building in SF Downtown. You gotta have something to blow the horn about at UC Berkeley. While SFDBI / SEAONC /PEER were working on the Tall Building Initiative & SFDBI AB-032 before the Millennium Tower, they look to have redoubled their efforts since and were possibly racing to close the door after the horse had already left the barn, as in, before the sinking became public.
I feel for the condo owners, they may have hired good litigation attorneys but they are lost when it comes to making relevant arguments concerning the defects of the tower and their attorneys don't seem to know what is a good plan of attack either. The design requirement for a maximum considered earthquake is that the building not fall down and people are able to safely exit the building. It could subsequently be red-tagged but as long as it protected life & limb, then mission accomplished. So coming up with ground motion simulations that are not embodied in the UBC are irrelevant. It is not the Structural or Seismic or Wind design of the BUILDING, that needs scrutiny, it is not the building at all. It is the shoring & bracing, the group depth of the pilings, the effect of the pressure bulb from the pile group on the soil beneath & around the piles, the method the piles were driven & order of placement, if the sides of the foundation were included in the resistance calculations, the soil characterization used in the geotechnical reports, the geotechnical calculations and which UBC piling loading criteria was chosen, the excavation & dewatering of the parking structure/basement, the sequence of building a heavy tower and then starting to dig a very deep excavation immediately adjacent to the tower when the foundation was already exhibiting rapid settlement even before they began the excavating. Maybe they should have started with the parking structure basement & later the tower. Too much deflection of the West podium basement shoring wall would have been bad for friction/resistance bearing piles, the same for too much dewatering. These are all the vulnerabilities that relate to the sinking & tilting. These 2 photos, taken on the same day 8/19/2007, give an idea as to the dichotomy of the tower and adjacent basement structure's progress. By this time the tower had settled 3 inches. I think there were 23 floors on the tower when the podium basement excavation began.
Treadwell & Rollo only gave a 50/50 endorsement of their own settlement predictions. With a confidence level like that, how is any foundation consider NOT a performance design, regardless of UBC design criteria? You really have to wonder if SFDBI is out of it's depth and just looking for a CYA engineer's stamp when it comes to shoring, piling & foundations. They don't seem to have in place the same internal structure for foundation review that large cities on the East Coast have in place.
Clearly prudence was exercised concerning the effect of weight of the building and ground pressure on the adjacent basement shoring by the General Contractor, Webcor Builders. Before they began excavation of the parking structure basement they bolted heavy steel strongbacks to the footing of Millennium Tower & then welded them to the solider pile/CDSM shoring to support the upper reach of the Westward diaphragm wall. It does appear that they used used tie-backs lower down on the shoring wall. Blue Dots in photo: Link The piling contractor augured each pile 40 feet from a working elevation of about 10 to 15 feet below grade, so there wasn't a lot of upper pile confinement generated from the pile driving. Since it appears that pile driving started on the North side of the foundation, this would be where the piles with the least confinement & lesser capacity would be located. It just seems that with less skin friction due to auguring that the potential for shorter piles to heave is greater once remaining and/or deeper piles are driven & reach the deeper soil that was undisturbed by the augur. The piles range from 61 feet to 90 feet according to SFDBI Raymond Lui. So perhaps only around 20 to 50 feet of that is below the mat foundation. If you look at the cross section illustration De Simone used for a SEAONC presentation of the project, the scale of the piles beneath the tower is more on the order of 150 feet deep, when they should be just a bit deeper than the podium basement foundation.
The 2003 Final Environmental Impact Report, Page 247 Link included an acknowledgment that dewatering was a concern on this project for which the the City of SF was empowered to enforce a requirement for ground settlement monitoring, special inspections & even a halt to the work if settlement was beyond anticipated values. So when the SFDBI testified that they had no way to compel the developer to include a geotechnical engineer to be part of the PEER review, they are not being completely honest. The dewatering/ground settlement monitoring - special inspections could have compelled the developer. It seems SFDBI passed on this Special Inspection, otherwise they would have (?should have?) known a month after the tower foundation was poured that the structure was on the move and long before the podium basement excavation commenced. To later sign off on an occupancy permit, having failed to implement a monitoring scheme or failing to "INSPECT" the special inspectors reporting is just seems like double negligence. Perhaps too much myopia from staring at plans all day?
SFDBI is also not being truthful when they say they had no cause to consider the Transbay Center project during plan review. It was acknowledged in the 301 Mission Street EIR, page 159 Link and the final design was a hybrid of Alternative E-1 of the EIR, which itself was the result of conversations the developer's design team had had with the TJPA about the Transbays Center, over an anticipated 5 foot encroachment on to the southern Millennium project property line. Why even have an EIR if the Building Dept. Plan Review section isn't going to use it to carry forth the City's expectations? The global lack of recollection by the SFDBI is also questionable. There is a close knit Major Projects Permits/Plan Review unit to handle tall buildings. According to SFDBI Quarterly & Annual Reports there were then only 3 to 4 tall building under construction & about 7 in various stages of plan review. Finally, SFDBI has an internal peer panel "Permit Coordination Division", to assess the department's own compliance of permits. SFDBI 2004-2005 Annual Report, page 39 Link
At the time of the 2003 Final EIR the tower was likely a steel frame structure and the building elevation cross-section showed 3 floors of parking under the tower & 3 under the podium. Page 157 Link So the tower foundation & the podium foundation were both of equal depth but neither as deep as the 5 floors of parking now under the podium. So this much deeper excavation should have spurred the SFDBI to be more attentive to dewatering & the tower foundation. Steel tripled in price over a years time and then too SF was desperate to keep major developments within the Transbay redevelopment area on track. They needed kick-starter projects to generate developer interest for the later sale of Transbay properties to fund the Transbay Center. Include that during testimony on 80 Natoma the SFDBI somewhat bemoaned the lengthy PEER review process of performance designed buildings before the SF Building Inspection Commission and the stage was set for another 80 Natoma-like concrete high-rise but of a prescriptive design, that would sail through the Plan Review dept with a degree of deference. You even have to consider that some bias may have occurred, at the excitement & prowess over the daring feat of building a tall "concrete" tower in earthquake country. The real failure is that, search as I might, I can't find that SFDBI has even one geotechnical engineer on SFDBI permanent staff. Seems they are only hired on PEER review panels or short term contracts. It also seems like any time pointed questions about SFDBI & geotechnial reviews are asked, they habitually give indirect answers that never touch upon the gist of the question. The SFDBI responses in the minutes of this August 30, 2004 Building Inspection Commission meeting regarding 80 Natoma are practically boilerplate in resemblance to their ambiguity over 301 Mission Street. Link All the while the Millennium Project is under permit review. SFDBI 2004-2005 Annual Report, Page 35 Link
This is where Jack Moehle really is not helping. When he told SF Supervisor Peskin that he was asked to right a project close out letter for 80 Natoma and that he was instructed to leave out the nature of the SFDBI Stop Work Order investigation over 80 Natoma regarding geotechnical reports that claimed the project would sink, certain things fell into place. Treadwell & Rollo had gotten in the last word, where they challenged the data used for opposing their own geotechnical report & the design. With no resolution to the reason for the Stop Work Order & a letter from the developer's design team reporting the property under purchase & the 800 Natoma project abandoned, there wasn't any precedent for the SFDBI to apply prior work as a measure of discrimination. While Jack Moehle may not recall off the top of his head, what discussions took place regarding the desired composition of the letter or who participated in the selective content, I'd be surprised if he doesn't have it all in one of many black & white marbled composition books filling a number of drawers of one of his filing cabinets. This is where the real ethics questions begin and they all point to the City of San Francisco, the Developer, the design team & the PEER Review panel, TJPA is way off in the distance. Although it would be interesting to see ARUP's projected dewatering gradient map for the surrounding area. The attorney for the larger body of condo owners going after TJPA loves to scream bloody murder about TJPA dewatering but the siltation tanks he harps about on the TJPA site south of the Millennium property were for the entire TJPA dig. There is an 8 inch diameter "common" pipe running atop the TJPA shoring the entire length of the project feeding those tanks. They don't represent the West excavation dewatering by TJPA at all. It was the last dig and the tanks were removed/moved.
So far SF Supervisor Peskin has wasted a year on Structural Safety when the building code already gives assurances that in it's current state the tower is still well within design & safe. When SG&H reports on the structural integrity of the pilings & foundation, they are speaking of the seismic safety performance. The report has nothing to do with dispelling the fact that in the tower's "semi-static" state of rest on the ground, it is sinking & tilting. That is beyond the scope of their report. It is time for the Structural guys to step aside & have the Geotech guys do their song & dance. Seems like it is the developer, Millennium Partners that wants to keep everyone focused on the building instead of what is under it. Same as during the permitting. Typical realtor behavior, "don't look at the crack over the doorway, look at these new countertops & tile". Millennium Partners seems to keep pushing the "Building is Safe" message to perhaps escape the grasp of the California Real Estate Disclosure Law, which the condo owners need to push, as akin to the "Calif Automobile Lemon Law" (Song-Beverly Consumer Warranty Act). The fact is that Millennium Partners was selling something "as New" that was in fact highly likely to need remedial work performed to such an extent that the building is a Lemon. The question is whether SFDBI's issuance of an occupancy permit endorses the "as New" representation & nullifies the real estate disclosure law. The only thing that is certain is that SFDBI is too busy demonstrating the complexity of their bureaucratic cognitive dissonance to know one way or the other.
RE: SF tower settlement
Dik
RE: SF tower settlement
I suppose the City has its hands full protecting criminal immigrants, and doesn't have time for mundane issues like buildings tilting.
RE: SF tower settlement
RE: SF tower settlement
MAYOR NEWSOM AND SUPERVISOR PESKIN ANNOUNCE APPOINTMENTS TO DEPARTMENT OF BUILDING INSPECTION COMMISSION
Link
S.F. home in Twin Peaks collapses during disputed expansion
http://www.sfgate.com/bayarea/article/S-F-home-in-...
Link
Investigation and Mitigation Report on Incident Occurring at 125 CROWN TERRACE
http://sfdbi.org/sites/default/files/125%20Crown%2...
RE: SF tower settlement
The "Expert Panel" is in many respects a Mulligan, a do-over, if you will for a full 3 member PEER review of the structural integrity of 301 Mission St. One would expect that, the City of San Francisco being under the microscope would steer well clear of even a hint of Conflict of Interest. More especially, those who formed the Expert Panel but you will have to decide for yourself. What caught my eye after having looked at many documents was panelist: Craig Shields, President at Rockridge Geotechnical. Craig Shields, opened shop in 2006 after leaving TREADWELL & ROLLO where he had worked since 1989, virtually from T&R's inception. Before that he worked with Frank Rollo Sr. at Harding Lawson Associates. Link
You really have to wonder what Mayor Ed Lee was thinking.
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Just read the last link... there was a geotekkie, but not an independent one... and part of the party...
Dik
RE: SF tower settlement
Does the geotextile seen in the photo I posted on Oct 2nd represent the tumbled shoreline of Yerba Buena Cove?
1840's San Francisco was a lumpy place of sand dunes.
If you are interested here is a video (1+ hrs) Link about how the dunes were moved about and how it affects buildings in SF.
Creeks would travel under the sand occasionally breaking the surface. If the early illustration is to be given any credence, the creek was capable of sufficient water volume to transport heavier sediment/sand far enough to create a sand bar at its mouth. Arguably, the creek is still there. This 1853 map Link seems to indicate that the location just opposite of the present day Millennium Tower was in a state of being filled in but in 1857 the site of the Millennium Tower was impounded. Link It seems San Francisco's early land speculators sometimes had problems filling in the marshes and parts of the bay. They would haul sand & build it up to elevation, send for the city's building official, only to come back the next day and see that all their work had subsided below the waterline.
Today, just across the other side of the Transbay Center is the 181 Fremont St. Tower. The geotechnical & foundation design are the work of ARUP and their reasoning for the foundation design recommendation is worth contemplating. Link The TJPA installed CDSM shoring that penetrated the Old Bay Clay by 10 to 20 feet. It was supposed to prevent a dramatic drop in the water table outside the excavation. When BART was built, they did things differently, recharging the ground outside their excavation to maintain the water table.
Finally, here is a link to all the SF Government Audit and Oversight Committee - Building Standards in Seismic Safety Zones hearings PLUS the records. Including the Oct. 18th testimony of De Simones Structural Engineer of Record, Derrick Roorda. Roorda came across as a decent guy but he was a bit gratuitous to Treadwell & Rollo on the rate of the buildings sinking. The actual SG&H 2017 report, and Treadwell Rollo's original geotechnical report, idealized ground profile & pile driving plot. Link Item 16. Comm Pkt 101817 - LARGE FILE is the sum of all the preceding item numbers and the contents list at the beginning of the pdf is conveniently hot-linked for browsing. De Simone provides a more detailed view of the settling rates but they also play politics ascribing the "commencement" of TJPA construction activity as playing a role when the only work being done was demoltion, site work, CDSM shore wall placement & the buttress wall. It would be a year later that actual excavation took place. Much like all the players who ignore the original settlement forecast and refer to the latter as though the original is a of no consequence. Coincidentally, Treadwell & Rollo were the on sight Environmental Soils firm working for TJPA while the shoring & buttress wall were being built.
During the SF Government Audit and Oversight Committee - Building Standards in Seismic Safety Zones hearings, Supervisor Aaron Peskin has asked almost every group of witnesses about some mythical letter from InSituTech. No one has indicated that they have any recollection of the letter. Unfortunately, it doesn't seem to be part of the records, to date. InSituTech was a small geotechnical consultancy in Orinda, CA, about 40 minutes from SF & run by D Michael Holloway, PhD. He went to work for Dan Brown Associates as a field consultant for the TJPA buttress wall. He has an interesting resume, you can view it on his LinkedIn profile. He has spent most of his career as a piling consultant in the field. Link It would be great to know what he may have observed & what he wrote to the DBI. Supervisor Peskin plans to hear testimony from former Treadwell & Rollo people. He mentioned Frank Rollo but it is Christopher A. Ridley of the present Rollo & Ridley who was the Millennium Tower Geotechnical Project Manager. Link I'd rather hear from D Michael Holloway. Records show the building weighs 220,000 kips, sadly Peskin did not ask what was included in that figure. After looking at the piling plot, the pile driving did start in the Northwest corner of the lot and between the plot & a photo from an earlier post, the piles concentrated around the core appear to be less than 3 pile dia. apart. Link
RE: SF tower settlement
In that link, I find a statement that:
"an equivalent top down load of 14,000 kips was applied by Loadtest."
Now, that makes me curious just how you go about doing that...
RE: SF tower settlement
"Using three 24-inch O-cells on a single plane, an equivalent top down load of 14,000 kips was applied by Loadtest."
Here is a link to the O-Cells Link
Here is Loadtest's write up of 181 Fremont. Link
RE: SF tower settlement
Short answer: They're putting a hydraulic cylinder at the bottom of the shaft and jacking using end bearing on the bottom versus skin friction on the sides to hold it in place. So it doesn't involve putting umpty thousand tons on top of the pile. Also, in one of those links, they did show a "load frame" that was presumably for that purpose, but it was 2,500 tons.
RE: SF tower settlement
What is the significance in the shear wave velocity?
Dik
RE: SF tower settlement
Dik
RE: SF tower settlement
Here is a basic explanation of seismic waves. There are two types, body waves & surface waves. Surface waves are slower, have greater amplitude, travel farther & destructive capacity. Link
When I was looking at the Dames & Moore idealized soil cross section Link , I wondered if the profile of the "Upper Sands with Clay Lenses" was the result of a past earthquake and that possibly the "Loose to Medium Dense Silty Clayey Sand" lens at bole hole F503 was a sand boil from the quake. The sand profile looks a great deal like a surface type, slow moving "Love Wave". So an earthquake wave trap in motion in the sand.
RE: SF tower settlement
RE: SF tower settlement
Dik
RE: SF tower settlement
RE: SF tower settlement
Dik
RE: SF tower settlement
Preview: Jerry Dodson takes 60 Minutes for a stroll in the basement. Something the CBS 60 Minutes preview shows that the can't be observed in previous photos of the crack gauges, is a difference in plane from one side of the crack to the other.
RE: SF tower settlement
https://www.atlasobscura.com/places/leaning-towers...
Yikes!
http://julianh72.blogspot.com
RE: SF tower settlement
RE: SF tower settlement
Dik
RE: SF tower settlement
Scariest moment to me (in the 60 Minutes story): the attorney get together. So many of them, it takes (IIRC) 30 minutes to get down everyone's name.
RE: SF tower settlement
As in all other structural elements, the capacity of piles is not the full story. Serviceability, as in deflection and settlement, can't be ignored.
RE: SF tower settlement
True. But I doubt the SE ignored that. In fact, they had a settlement estimate that the building was supposed to see over a 100 year period. (4" if memory serves.) To be sure they considered that level of P-Delta. (In the wind or seismic cases at least.)
Nobody is really owning up to it (as per the story on 60 Minutes).....but my gut instinct is the piles are in a strata that isn't what they anticipated.
RE: SF tower settlement
Way back in this thread, I linked to the Ocean Tower in South Padre Island, TX. The piles carried the load to compressible materials and they compressed. This is sounding more and more like that.
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RE: SF tower settlement
Here is an table of contents.
RE: SF tower settlement
Millennium Tower has sunk 17 inches and tilted 14 inches since its completion in 2008. Satellite images suggest the residential high-rise — home to more than 200 multimillion-dollar condos — will continue to sink two inches per year.
link: http://www.businessinsider.com/cost-to-fix-leaning...
RE: SF tower settlement
https://www.nbcbayarea.com/news/local/Gaps-in-Wall...
RE: SF tower settlement
Dik
RE: SF tower settlement
San Francisco city building inspectors have issued a citation against a tilting 58-story residential tower for an apparent fire safety risk.
KNTV of San Jose reports the Department of Building Inspection issued the violation notice last month for the Millennium Tower after consultants found the tilting building was exacerbating gaps between the facade its concrete and steel core.
Experts say smoke and flames can shoot through such gaps, making it easier for a fire to jump to a higher floor.
The fire safety hazard warning was part of a December 2016 report commissioned by the Millennium Homeowners Association after a condo owner complained of a mysterious odour.
City officials issued the notice a week after the TV station reported on the warning."
Link: https://www.ctvnews.ca/world/leaning-tower-of-san-...
RE: SF tower settlement
There has yet to be any disclosure by Millennium Partners, DeSimone, Treadwell & Rollo or Webcor Builders as to why the building is sinking & tilting. I have been through the information the SF Government Audit and Oversight Committee has on their site & I guarantee you that they are not being as forthcoming, as they could be. Even the SG&H 2017 "Supplement" commissioned by the SF Mayor's Office - 301 Mission Seismic Safety Committee is flawed. For starters the bore hole used to characterize all the piles isn't even under the tower. It is 25 feet to the east of the tower under the podium. Why not use any of the 5 bore holes that are under the tower? Other than that they pass through more clay and less sand at inappropriate elevations.
Spending millions of dollars on an exploratory remedial program when you have yet to fully examine the cause is imprudent. To what extent the HOA is being led down this road by Millennium Partners or other parties is a mystery. If it is a judge who is urging the homeowners to work towards a remedy at the expense of knowing all the facts, then that is unfortunate. I can guarantee you Millennium Partners, DeSimone or Treadwell & Rollo or Webcor Builders all know why the building is tilting & rotating.
SFDBI is no innocent party either. We have all seen the photos of the cracks & crack gauges in the basement. So on Tuesday February 9 2009 SFDBI's Deputy Director Raymond Lui writes to DeSimone regarding excessive Settlement of the Tower. On February 11 & 12 (Thurs & Fri) SFDBI Field Inspector for Major Projects, District 1: Yuang-Tam Chiu makes site verification inspections at 301 Mission. Yet SFDBI Tom Hui & Ron Tom have stated in testimony before the SF Government Audit and Oversight Committee that everything looked fine and no signs of settling were observed. But all the cracks were there! From 24 to 29 April 2009 ARUP installs 103 crack monitoring gauges in just the basement of Millennium Tower, only 79 Days since SFDBI's Ray Lui wrote Settlement Inquiry Letter. On 11 August & 19 August 2009 SFDBI Field Inspector Yuang-Tam Chiu does a Pre-Final & Final Inspection at 301 Mission. There are Crack Gauges! Crack Gauges Everywhere!. 156 days since the TOC was issued. 103 crack gauges are visible along the walls of the Tower Basement Level B-1. Mostly clustered on the North & South ends of the building. Not one request to see any surveyor data or reports. Final Inspection Approved.
If the Mat foundation is already cracked as Ron Hamburger at SG&H speculated in 2014, then where do they begin installing piles, since coring large diameter holes in the mat "could" make matters worse? The HOA should at least do some Pulse-Echo Testing of the foundation before they get too far into the piling scheme. Having to position & re-position equipment in a basement in order to satisfy a charted installation designed to prevent additional damage to the mat could greatly increase the time & expense. Has Millennium even told them that corrosion control is going to be needed long-term? The ground water is brackish. It isn't particularly expensive but it is a consequence of cracking in the foundation.
RE: SF tower settlement
It looks like The Millennium Tower HOA is moving forward with an objective to stabilized the Millennium Tower. LERA & Swinerton Builders are the team overseeing the work. Documents on file for 301 Mission at the SF Planning Dept. website show they will be coring possibly two penetrations through the 10 foot mat foundation at the north end of the tower, approx mid tower.
They will also be opening up the the wall of the parking structure at parking level 2, cutting two 3 ft by 3 ft openings, in order to determine if the tower has come to rest on the soldier piles of the CDSM shoring wall between the tower & the podium structure. In Treadwell & Rollo's 2005 Geotechnical Report, T&R had recommended that since the CDSM shoring wall was to be directly beneath the mat foundation, the shoring wall should be at least 12 inches below the mat, to avoid interference.
The tower may or may not be resting on the shoring wall. If it is, that will at least give engineers something to think about but if it is not, then they will have to consider the consequences and how much time they have before it does and matters become more critical. The soldier piles were about 1 foot higher than the CDSM shoring. In hindsight one would think the developer's team ought to have given thought to cutting the soldier piles down, since Treadwell & Rollo's second estimate for additional settlement of the tower was still a large number AND they knew or should have, well before the last level of the parking structure was poured, that shoring wall interference could be a factor. As soon as the last struts of the podium were removed the tower settlement accelerated. The building was sinking at 0.020 inches a day.
Apart from the Millennium Tower being, at one time, the tallest, heaviest building west of the Mississippi, it can possibly claim another first. I'm not really sure. Has there ever been another building to exploit an "Outrigger/Cellular Box Grade Beam"? Okay, it wasn't really intended to be an Outrigger/Cellular Box Grade Beam? It was supposed to be a 3 foot thick cantilever slab off the south end (Transbay terminal side) of the 10 ft thick mat that would fly over a 15H?x15Wx100L ft., PG&E utility vault but once the building started sinking there was going to come a point where the compacted back-fill would push back. You can see the vault in these two photos.
In the document package at the SF Gov website for the public hearing by the Government Audit and Oversight Committee, initiated by SF Supervisor Aaron Peskin, there is vague mention of the PG&E utility vault and the Millennium Partner's legal team geotechnical engineers, Sage Engineer's efforts to calculate the subgrade modulus of the soil beneath the vault. Later in the SG&H 2017 supplemental seismic report, it is less clear, stating Sage is working on providing the subgrade modulus for the "soil supported" cantilever slab at the south end of the mat foundation.
It would be easy for most people to be confused as to what is being discussed in either instance because the B1 basement of the tower was also constructed with an almost identical PG&E utility vault directly over the one that was buried beneath the former 129 Fremont St. before the properties on the block were merged into 301 Mission for the condo project. Sage Engineers & SG&H might want to consider 4.3 to 4.6 x 10-6 as a modulus. Not that I have any basis for suggesting a proximate soil subgrade modulus but I think that might be a reasonable approximation of the Young's Modulus of 5000 psi compressive strength concrete.
The subgrade modulus is indeed a tricky number. The shoring wall for the Transbay terminal is directly along the south (100 ft side) of the PG&E vault and is 90+ feet deep, followed by the buttress wall extended to bedrock, while the CDSM tower/podium shoring wall is 80 feet deep & directly at the east end of the vault, the north side of the vault has 10 to 15 feet of open soil (under a portion of the cantilever slab/B1 Basement) between the vault and the mat foundation and the mass of the soil enveloped by the piles below the mat. Then only portion not completely influenced by confinement is the west end facing Fremont St. here the shoring wall is no where near as deep, perhaps 35 to 40 feet SF Datum.
Using a round number of 100 pcf for the soil removed for the old vault and that of the new tower basement, the soil supporting the old PG&E vault is about 2.5 to 3 million pounds light of equilibrium. If one was looking for a reason why the building was tilting to the north..., a type 3 lever & fulcrum (correct me if I'm wrong) might have something to do with it. "Outrigger/Cellular Box Grade Beam"~®" any suggestions for a more elegant name?
Speaking of equilibrium, once the excavation for the tower basement was fully compensated by upper floors, the building was "by weight" perhaps only 3 stories tall when it started sinking.
One really has to wonder what is being done to resolve this issue since PG&E needs to show due diligence in defending their easement rights. When ARUP inspected the basement of Millennium Tower, they were not granted access to the new PG&E vault in the B1 basement. When one considers that half of the 103 crack monitors are positioned on this end of the building, where the 3 foot cantilever slab joins & prys away at the mat foundation, you have to wonder what the condition of the concrete inside of the vault looks like. There was some strange activity along the 301 Mission/TJPA property line back in March 2017. The underground work looks like it extends beyond the 5 ft TJPA/301 Mission easement but there doesn't seem to be a permit at SFPUC, SFDBI or SFDPW. I would hate to think the TJPA & Millennium were doing corrective work through back channels without the public knowing who is paying for what.
The screen wall in the photo approximately represents the limits of the 5 ft TJPA easement onto the 301 Mission property line.
Both DeSimone & SG&H have stated that the basement walls of the tower play no role in the seismic response of the tower and while this may be true, it still doesn't address the issue that the cracks in the basement walls of the tower are structural cracks and the walls of the basement are 15 foot high retaining walls. Unless all the service lines leading into the tower arrive above ground, it cannot be stated that the tower is prepared for a large earthquake. For a little perspective, if you assume that what is above the basement was just a 5 story wood frame condo building, then the condition of the basement walls would have resulted in this structure being yellow tagged after the Loma Prieta earthquake. So how did a really heavy 58 story building with a "Yellow Tag" grade basement get an occupancy permit? There are probably upwards of a thousand property owners that could attest to having to seek out an engineer and take corrective action for damage sustained equal to what can be seen in the basement of 301 Mission. Maybe San Francisco City Hall can get the world's first Office of Resiliency to explain.
If one takes a look at the pile driving record for the tower and maps it out in excel it really doesn't look too bad. There are vulnerabilities (soft piles) and the mat of the heavy tower does deflect where these piles are located but it is tough to conclude that these appear in sufficient numbers, in group to explain the westerly tilt. At least not without some precipitating cause. Treadwell & Rollo indicated in their letter responding to an inquiry by SFDBI's Raymond Lui, that the extended dewatering of the soil during excavation might explain the settlement, it seems that would be at least one possibility. Fremont St & Mission St both appear to have settled at some point proximate to the timeline of the project and Webcor Builders took out a SFDPW permit to reset manholes on Mission St in 2009 while closing up the project. The manholes on Mission St have been paved over & later reset at least once again since 2009.
What about the shoring walls of the tower? Do they contribute to the tilting? The shoring walls on Mission & Fremont are comparatively shallow, perhaps -35 to -40 feet deep from SF Datum(the base of the tower mat is -24 ft). The eastern shoring wall is sandwiched like a keel, between the tower & podium is between at 80 & 90 feet deep and backed up by the 57 ft deep x 5 level basement parking garage. Finally the south end of the tower doesn't have a shoring wall but does have a concrete bubble beneath it bobbing on Young Bay Mud.
In one of my early posts I pointed out the 40 or so, "strong-backs", for lack of a better name, that overlay the top of the soldier piles on the tower/podium shoring wall. I assumed they were tied to the tower mat foundation and welded to the soldier piles to provide additional cantilever support during early excavation. Later I realized they needed to float, in order for the building to be allowed to settle evenly. So were they floating or were they welded to the soldier piles? The tower was at 42 floors when the last of the cross bracing struts & strong-backs were removed. The lack of soil directly behind the upper tier of lagging caught my eye early on as well but I don't know how much to attach to this. Did the soil drop from the bottom of the mat foundation as a result of aggressive dewatering? The following photo is from end of May or early June 2007. The building had settled about 2 inches.
SFDBI when questioned by SF Supervisor Aaron Peskin about why they did not consider the impending Transbay Center project in their evaluation of the Millennium Tower foundation, responded that they only review what is within the property lines. This makes sense but in the case of 301 Mission, the very concise wording of the SF planning permit, right up to the last paragraph of the planning motion, called for the "Joimt Use" of the property. In essence the Transbay Center was figuratively 5 feet inside the 301 Mission project property line. "Joimt Use" is legal lingo commonly found in easement agreements. The easement agreement between Mission Street Development aka Millennium Tower & Transbay (TJPA) wasn't executed until after the tower was built but in 2002 when the TJPA was consolidating their options for the path of the Transbay Center rail alignment with the site of the old Transbay Terminal, there was a fair deal of back & forth between Mission Street Development, DeSimone, Handel Arch & Caltrans & the TJPA about alternatives & the 301 Mission Tower project, including some fairly detailed schematics. (It somewhat calls into question Myers Dev. argument that the TJPA was unresponsive to communicating in like fashion regarding 80 Natoma). Ultimately, the planning motion that approved the 301 Mission St. development was based on Mission Street Development's "PROJECT SPONSOR PREFERRED"(Alternate E-1) citing joint use & incorporating a 5 foot wide TJPA easement along the length of the southern 301 Mission property line.
SFDBI's response came with reference to California Civil Code 832 pointing to “Each Coterminous Owner is Entitled to Lateral & Subadjacent Support” as cause to disregard development on adjoining property when evaluating the merits of an individual project. One problem for SFDBI is that for more than 20 years the SF Planning Dept. has been issuing planning permits that call for areal groundwater & settlement monitoring, specifically citing the Special Inspections section of the building code. The 80 Natoma project specifically called out for a recommendation by the Geotechnical Engineer regarding groundwater & settlement monitoring as a "Condition". In the case of 301 Mission, Mission Street Development volunteered, stating they would follow the recommendations of presented in the Final Geotechincal Report for the 301 Mission project. Treadwell & Rollo had a long list of recommendations, including groundwater & settlement monitoring. I think it is fair to say that streets settling & PG&E utility vaults with buildings resting on top of them represent Environmental Impacts that SFDBI has failed to consider. Apparently because the street is beyond the property line, it is the City of San Francisco & taxpayers responsibility to provide "Lateral & Subadjacent Support".
Far from SFDBI finding safe harbor in citing CVC 832, they may have isolated themselves. As a Coterminous Owner, the Transbay Center was equally entitled to "Lateral & Subadjacent Support", perhaps more so because the 301 Mission St project, at least on paper does not receive clearance for an SFDBI building permit, vis-a-vis the SF planning motion approving the 301 Mission St development without the inclusion of the "PROJECT SPONSOR PREFERRED" & "Joint Use" stipulation. When you delve into the history of Lateral & Subadjacent Support, another phase pops up and that is "soil in its natural state". In the case of the Coterminous properties of 301 Mission & the Transbay Center, the natural state would historically be soil in a state of rest. The last time it might be said to have moved was 1989. But by virtue of the continued settlement problems at 301 Mission brought about by construction on the property, which precede the Transbay Center excavation, the soils of the 301 Mission street property cannot really be consider to be any longer at rest. One could actually look at the TJPA shoring wall and subsequent Buttress Wall as extraordinary remedial measures to protect the TJPA project from the instability of the ground of the adjoining property.
Essentially, the property at 301 Mission was like a car that hadn't moved since 1989, the tires deflated & having flat spots, the oil pan with sludge, the brakes possibly rusted a bit to the calipers or discs. Even a car that sits overnight is harder to push the next day than one that has just come to a complete stop. The Millennium team not only got the car rolling but when they all stopped to celebrate, it kept rolling. The TJPA just represents a gentle downward slope in the road. It all comes down to the coefficients of static and kinetic friction. It is far easier to push a car that is already rolling than to get the car rolling in the first place. Whatever minuscule portion of responsibility could be attributed to the TJPA excavation would require some very elaborate modelling.
Then again the Transbay excavation itself can only effect soil at a given distance from the excavation. The excavation was 60 feet deep. At 30 feet if you draw a 45 degree angle back up and towards the tower, it intersects the side of the 10 ft mat foundation. That is why Millennium bangs away at dewatering because the areal effects of dewatering can be larger. It is just that there was so little rain fall during the Transbay excavation, it may be difficult to point to groundwater gauges and blame the TJPA. 40% of downtown San Francisco's ground water comes from leaky sewer pipes. Welcome to the Golden State!
The Millennium residents cite the Non-disclosure Agreement between the TJPA & Millennium but the responsibility was Millennium's. For the TJPA to say anything that would diminish the value of the 301 Mission project would have been grounds for a lawsuit. It doesn't help that the attorneys representing the Transbay Joint Powers Authority were from the City of San Francisco Attorney's Office much to the objection of many at the TJPA. No doubt SFDBI was worried about being seen as a party that could damage the prospects for the tower project but they still had a responsibility to see the cracks in the basement structurally repaired before issuing a certificate of final completion. There is no way around the fact that the certificate was improperly issued.
In 2014 the City of SF replaced the sewer line in Fremont St, claiming it was old and had probably needed to be replaced for some time but in 2011 in preparation for the Transbay Center project, utility lines were run immediately adjacent to the sewer line and if it was in such a bad state, it would have been dealt with then. It is more likely that the sewer line was damaged by the rotation of the Millennium Tower. Here is an April 2014 on the Microsoft Map page suggesting rotation, more are found on Google Maps in Nov. 2014 & later. The curb in front of the bus stop on Fremont St was in a preliminary state of failure. Even for the curb to be in this condition in 2014 took at least a year or two for this degree of deterioration to manifest. It has progressively been snapping like a candy cane for the last 4 years. It begs the question, what do the people at the SFPUC & SFDPW know and how long have they known. Has anyone been hurt at this bus stop? Why has it gone untended for so long? The building appears to be plowing a 35 foot wall of fill and mud in front of it.
April 2014
Nov 2014
July 2015
Oct 2017
I'm sure there is more that I have left out since my last post but this is the bulk of what I've learned. In fairness to Millennium Partners, I do feel for them. In their preliminary EIR, they had plans to move forward with the project in 2002/2003, maybe they were hoping to open under a Luxury Hotel Brand, maybe the PG&E Land Office & utility vault was holding the project up. When the project was finally approved by the SF Planning Commission in July 2003, it still had a 4 story basement/parking garage beneath the tower. The Treadwell & Rollo soils investigation is almost entirely based on the data from 2001/2002 & a 4 level partially compensated mat foundation. In May 2004 Niaz A. Nazir Ph.D. - Managing Principal for DeSimone Consulting Engineers SF & Chief Engineer for 301 Mission Project passed away unexpectedly. Enter Derrick Rhoorda to take over for DeSimone. When you consider that Millennium Partners subsequently brought in Jack Moehle to make sure the project was up to snuff, you might begin to appreciate how Millennium Partners might feel like they did their best and are not happy about the outcome.
SFDBI really is the Reno 911 of Building Inspection Departments. If you have a weekend to burn, you won't be disappointed reading San Francisco news items about the scandals that permeate both SFDBI & the Planning Commission. I think what is perhaps the most stunning and overlooked part of the Millennium Tower debacle is that SFDBI does not have a Geotechnical Engineer or Civil Engineer to pass muster on Chapter 18 of the Building Code. They don't even have easily to find guidance or an Administrative Bulletin on their website concerning Geotechnical Requirements. There was an effort from 2001 to 2004 to craft a Geotechnical Administrative Bulletin but it died in the Structuaral Subcommittee of the Code Advisory Committee in the hands of Hanson Tom. He had been asked to invite Frank Rollo to address the Structural Subcommittee regarding a Geotechnical Administrative Bulletin. Did he make the invite? If I was an SF homeowner who paid a ridiculous sum for home in San Francisco & was required to higher a Geotechnical Engineer to put an addition on my home, only for SFDBI to ignore the work in the report I would not be happy.
San Francisco has the Maher Ordinance for portions of San Francisco that are built on bay fill & they have Supervisor Aaron Peskin's Slope Protection Ordinance but they don't have anyone on staff that has the required knowledge & experience to actually review a Geotechnical Report. The city with the most infamous & dramatic examples of what earthquakes can do to a city doesn't feel compelled to hire one Geotechnical Engineer at SFDBI. Since Millennium Tower they have crafted, not a Geotechnical Administrative Bulletin but a more rigorous Structural - Tall Building & Performance Design Administrative Bulletin, essentially engineering their way around, doing the obvious. Now, they require not one but TWO geotechnical engineers or some such nonsense. Seattle, Los Angeles, San Diego all have well developed Geotechnical Teams in their building departments but not San Francisco. Even San Jose, which doesn't have much need for a Geotechnical Engineer has a City Geologist that decides if a project requires deeper scrutiny.
It is not just SFDBI, it is the City. A look an employment website confirms the Bay Area has more Geotechial Engineers than anywhere else in the world but when SF needed one for the 301 Seismic Safety Committee PEER Review, apparently the only one they could find was a former founding employee, 16 year alumnus of Treadwell & Rollo who started out with Frank Rollo Sr. at Harding/Lawson pre-1989.
There was a time that a former SFDBI employee was forging an Architect's & a Structural Engineer's seal on documents submitted to SFDBI. Supposedly it took years for his former colleagues to become suspicious. If he had chosen a Geotechnical Engineers seal, he might still be at it.
Before the City of San Francisco decides to waste any more time on Administrative Bulletins, they need to hire a Geotechnical Engineer. It also doesn't take an Administrative Bulletin to require that going forward all Major Buildings & PEER Review Kick-off meeting will be attended by all engineers of record on the project, including the Geotech. The City of San Francisco deservedly should have to deal with this mess on its own. The TJPA did all their due diligence.
The SG&H 2017 Seismic Report Supplement largely crafted to address the suggestion by Sen, Dianne Feinstein that a committee be formed to investigate the troubles at 301 Mission is a bit sloppy, considering the company that authored it & the people impaneled by the City to review the data. The Long-term Static Axial Pile capacity is described at having it's lowest capacity to the North & East but it appears to be to the North & West, which is an area that SFDBI expressed concern about. Also, the description of the tops of the piles in the report has the numbers jumbled in two different parts of the report and the description is not in agreement with the shop drawings supplied by the pile producer. While most of the numbers on the pile shop drawing are in mathematical agreement, there is a number shown at the sum of the strands that is clearly not correct.
SG&H describes the piles as having 8ea x 23ft-6in of #8 or #9, suggesting 12ft-3in could be removed with 12ft-3in left to develop pile capacity. In fact there are 4ea x 23ft-6in of #8 & 4 ea x 7.5ft #9 bars grouted into 17.5ft sleeves. It isn't so much that there are a large number of piles that were cut but that SG&H really fails to explain with clarity how the piles are up to the task or how many are deficient. There was something else that was off about the report but it escapes me at the moment.
RE: SF tower settlement
It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.