INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Jobs

SF tower settlement

RE: SF tower settlement

That has got to be a "worst nightmare" scenario starting up.

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

Good thing it's not too tall... only 58 stories... Settled 16" so far and tilted 2". Constructed on mud fill with a slab foundations supported on piles into dense sand.

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

Well, this will be quite the case study on foundation improvements assuming they don't just demo it and start over.

Professional and Structural Engineer (ME, NH, MA)
American Concrete Industries
www.americanconcrete.com

RE: SF tower settlement

For those that don't want to sign up as a member of the SF chronicle. Here's a fox "news" article posted by Tigerguy in the foundation forum

Link

RE: SF tower settlement

Quote (Article)

The HOA added that it is exploring its legal option and could pursue damages from several parties, including the developer, the original design professionals, the original contractors and the Transbay Joint Powers Authority.

Trouble in paradise that's for sure.

Check out Eng-Tips Forum's Policies here:
FAQ731-376: Eng-Tips.com Forum Policies

RE: SF tower settlement

I worked on the BART station construction one block away on Market. During lunch, a group of Archeologists would poke around the excavation and found all the stuff that was dumped from ships moored in the Bay before this area was filled. Lots of those clay pots, apparently used to ship rice, and many small bottles, some still sealed and full. Also met my wife there.

But I had nothing to do with this settlement.

RE: SF tower settlement

Quote (Article)

The transit authority also said the high-rise is made of concrete rather than steel, "resulting in a very heavy building. This heavy structure rests on layers of soft, compressible soil. 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's a pretty strong statement for the transit authority to make...

Time to grab some popcorn.

RE: SF tower settlement

Various places in that part of the city is soft landfill; they used to find ships and whatnot when digging foundations for various buildings. Near as I can tell, that particular high rise is sitting on what used to be Yerba Buena Cove:
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
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers

RE: SF tower settlement

"and has sunk 16 inches and shifted 2 inches to the northwest since opening"- That's from the Fox news article, doesn't say it tilted, but moved sideways?
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

Quote (JStephen)

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

I guess if you consider such a thing a positive... upsidedown

RE: SF tower settlement

Been reading about the engineers and such involved with Flint.
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

Quote (BUGGAR)

Been reading about the engineers and such involved with Flint.
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?

Well, in your case, let's hope the statute of limitations for arousal-induced negligence has expired.

RE: SF tower settlement

Likely tilting because of all the compressing beer cans tossed in the hole by BUGGAR and his cohorts. wink

Keith Cress
kcress - http://www.flaminsystems.com

RE: SF tower settlement

My guess is that the legal settlement may take longer than the ongoing foundation settlement...

RE: SF tower settlement

"Founded on piles bearing on dense sand". There was a drainage system built to collect leakage from the slurry walls around the Lower Market Street Station. What if these dense (previously) sands have been draining through the slurry walls and into the Market Street Station dewatering system and no one knows this?

I'm not really trying for some witness per diem, honest.

RE: SF tower settlement

It will have to tilt a lot more than 2 inches before it becomes a major tourist attraction. It will be some time yet before the Italians become concerned about losing tourist dollars to SF.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: SF tower settlement

The Transbay Transit Center is 90% over budget and considering a special tax on the properties, including 301 Mission, to pay for the bail out. This is just for Phase I of the Project. Funding for Phase II has not been identified. Phase III??

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.

RE: SF tower settlement

A new icon to advertise for tourists for the local money mongerers - The Leaning Tower of San Francisco - And Vegas can take bets as to when it will fall too.

Many investment opportunities here...

Mike McCann, PE, SE (WA)


RE: SF tower settlement

Imagine having property on the now "underside" of that building. <shudder>

Keith Cress
kcress - http://www.flaminsystems.com

RE: SF tower settlement

Obviously someone needs to do pushover analysis if it is leaning left.

Mike McCann, PE, SE (WA)


RE: SF tower settlement

Leaning left from one side; leaning right from the other side. winky smile

RE: SF tower settlement

Ah ha, so the building didn't follow the notes on the drawing, not the engineer's fault!

RE: SF tower settlement

It goes to show we don't need to be so darn conservative when designing foundations. I'd bet this one well stand well beyond the lives of all the members here and with full occupancy.

RE: SF tower settlement

Geez Dan, don't make everyone play the clickclick game, just post the dang picture directly!

Keith Cress
kcress - http://www.flaminsystems.com

RE: SF tower settlement

Any suggestion on how to prevent the building from sinking and tilting? Would it be possible to jack up columns like in Kansai airport terminal?

RE: SF tower settlement

Why jack it up? Do like in Mexico City. Just install new entry ways in the second floor so that no one is trapped inside when current doors won't open due to earth there. Should cost less.

RE: SF tower settlement

So, in 45 years or so, it will be 57 stories high!

STF

RE: SF tower settlement

Unfortunately, they will have to lower the rent on the bottom story.

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

Rather than make fun of the situation I am more interested in finding out what led to the mistake so that others may not make the same. This is a serious situation I am sure not one of us would want to be in. Any leads on this?

RE: SF tower settlement

I know next-to-nothing about civil/geotech, but is grouting an option on something this big to at least stabilize and stop further sinking? Wow, what a nightmare. I'd hate to think what a seismic event would do this site.

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

Somewhat of a side note, but...

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

Quote:

Rather than make fun of the situation I am more interested in finding out what led to the mistake...

It doesn't have to be either/or. We all take it very seriously I'm sure. Especially the structural engineers among us.

Check out Eng-Tips Forum's Policies here:
FAQ731-376: Eng-Tips.com Forum Policies

RE: SF tower settlement

Could it be that the higher ups wanted to cut cost, opting for foundation slab with piles not going all the way down to bed rock and the structural engineers come up with calculation based on ideal case to justify decision without sufficient core bore data?

RE: SF tower settlement

(OP)
lillliput,

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

OK so we joked a little. However, does anyone have any CORRECT history of construction as well as an on-going record of measurements? Can we learn from any mistakes? Maybe.

RE: SF tower settlement

What makes you think I was joking?

Mike McCann, PE, SE (WA)


RE: SF tower settlement

there is no negligence by running piles to dense sand rather than bedrock. If each pile can develop the capacity it needs in the dense sand, where's the problem? There is a problem designing for some capacity and not documenting that the installed pile developed that capacity. There is also a problem not knowing the performance details of the piles. I mean if the piles remain good against failure, but they required 16 inches of settlement to develop their full capacity, that's a serviceability problem.

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

(OP)
Why do you question the 16" settlement quoted, fattdad? I would think if this was not factful, there would have been a denial by now.

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

I wonder if the parking garage entrance is near the maximum settlement area. It would make the perfect home for Evel Knievel.

RE: SF tower settlement

To say nothing of raising havoc, in one fashion or another, with the handicap accessibility.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

RE: SF tower settlement


Quote (MacGyverS2000 (Electrical))


9 Aug 16 16:59
Somewhat of a side note, but...

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?

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

I don't question the settlement at all! I was just saying the dense sand could be safe for foundation support (i.e., strong enough), but some other layer may settle. So, how did the original design consider settlement if the foundation bears on soil rather than rock? Were the soil layers and their properties estimated (I'd doubt it)? So, it'd be likely that somebody studied the strength and compressibility of the dense sand, the soil above (mud?) and the soil/rock below. I just could not claim because the foundation did not go to rock there was some negligence.

Sorry to confuse. . .

f-d

ípapß gordo ainÆt no madre flaca!

RE: SF tower settlement

Just a stir-the-pot article, no real news:
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

Heck of a project for "Slabjack".

Mike McCann, PE, SE (WA)


RE: SF tower settlement

Dodson is going to be in for a few big surprises over the coming years.

RE: SF tower settlement

This is the perfect storm:
  • Condominium
  • Flaws that might be huge or not.
  • Extremely rich entitled tenants.
Many lawyers are going to get very rich.

RE: SF tower settlement

boo1 - that is a good article and fairly described all the challenges, both engineering-wise and in terms of the legal issues.

Check out Eng-Tips Forum's Policies here:
FAQ731-376: Eng-Tips.com Forum Policies

RE: SF tower settlement

great... and I'd be somewhat concerned about the hairline cracks in the basement...

Dik

RE: SF tower settlement

(OP)
Thick hairs, those.

RE: SF tower settlement

LionelHutz:

Yes

Dik

RE: SF tower settlement

So if this issue was settled out of court, would it be a settlement on the settlement?

RE: SF tower settlement

I was thinking, micropiles to rock and secured in the slab foundation. Would the poor soil offer enough restraint to preclude buckling. Lets try to think of some remediation.

Dik

RE: SF tower settlement

IR, perhaps we should come at this from a different angle rather than straight on? I'm leaning towards a simple solution.

Dan - Owner
http://www.Hi-TecDesigns.com

RE: SF tower settlement

curious. has anyone heard who the geotech firm was on this? i know DeSimone was structural but haven't seen any reference to the geotech. FYI... they have a new geotech in now who was not related with the original construction.

RE: SF tower settlement

That settles it.
I will only read this thread for shear amusement from now on.

STF

RE: SF tower settlement

Quote (garthsoilsguy2)

curious. has anyone heard who the geotech firm was on this?

Treadwell & Rollo, now part of Langan Engineering. ENR link re aquisition and Langan Engineering website.

Quote (garthsoilsguy2)

i know DeSimone was structural...

Sadly, Vincent DeSimone (founder of DeSimone Consulting Engineers) passed away in November, 2016. Memoriam

RE: SF tower settlement

This one only settled 14 inches before it was "dealt with."

RE: SF tower settlement

A structural engineer did a review of the building design, but only the building, not the foundation.
I kind of sympathize with the guy, no one welcomes you reviewing scope beyond your contract.

RE: SF tower settlement

Just curious here - it says that the tower has sunk 16" - that is "significant".
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.

Check out Eng-Tips Forum's Policies here:
FAQ731-376: Eng-Tips.com Forum Policies

RE: SF tower settlement

Quote (JedClampett)

A structural engineer did a review of the building design, but only the building, not the foundation.
I kind of sympathize with the guy, no one welcomes you reviewing scope beyond your contract.

And non-other than Prof Jack Moehle of UC Berkeley:

Quote (Curbed SF)

“The interest was to do an internal review to ensure that the structural system selected was suitable,” Moehle told city lawmakers at Thursday’s hearing. “[So] that if there was a formal peer review for the city later that most questions would be dealt with already.”

RE: SF tower settlement

And this from 2004 about 80 Natoma SF proposed 50-story tower that was NOT constructed Link:

Quote (Bizjournals)

A 50-story building is heavy. If constructed, the 80 Natoma Building would impose 13,000 pounds per square foot on the soil below it. Moreover, if the developer went ahead with his plan to use short (70-foot) piles to support the building, the bottom of his piles would lie just above a 90-foot layer of compressible clay. Geotechnical experts concluded that imposing such loads through the piles to the clay would cause the clay to deform and the building to settle several inches. Unless the developer were to extend his piles another 100 feet or so to bedrock, there is no getting around this.

RE: SF tower settlement

Link to C & C of SF video testimony of Prof Jack Moehle dated 2/2/17 - all 2.5 hours! Link

RE: SF tower settlement

(OP)
I had the same thought, Keith. But I'm not betting.

RE: SF tower settlement

From Curbed, "Moehle says he inspected the high-rise’s design from top to bottom—but no lower than the bottom. A geotechnical review—i.e., an assessment of the condition of the soil under the building site—wasn’t part of the process, because no one ever hired a geotechnical engineer."

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

Quote (Cubed SF and dik)

...because no one ever hired a geotechnical engineer.

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.

RE: SF tower settlement

Unless Cubed is misquoting Moehle, with the problems encountered, a 'new' independent geotech firm should have been retained to make the report complete and to address any concerns.

Dik

RE: SF tower settlement

It makes me curious who recommended what. On much smaller projects it is very common to have a geotechnical report that says "You can do it this way, and may have this problem or you can spend more and do it this other way and have less problem", etc. There's quite often a calculated risk involved, and the geotechnical reports I've seen more often reported both options with pros and cons, or went the more conservative route if there was any doubt.

RE: SF tower settlement

If you listen to the testimony of Moehle [Link] City and County of SF Supervisor Aaron Peskin asks Moehle why he did not stamp/seal his internal peer-review report, and also why was he was not an SE.

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

Ingenuity:
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

RE: SF tower settlement

would appreciate if anyone can provide some information on the ground profile below pile toe, especially clay thickness/depth.

RE: SF tower settlement

from one of the links, "Moehle wrote that "On the basis of my review, it is my opinion that the foundation design is compliant with the principles and requirements of the building code, and that a foundation permit can be issued for this project." The statement is a little confusing because Moehle clearly recuses himself from having any involvement with the foundation. If his statement is correct, he is stating that the foundation is... and, that a foundation permit should be issued.

Dik

RE: SF tower settlement

Current articles indicate it has tilted 12" and not 2"...

Dik

RE: SF tower settlement

Quote (dik)

Current articles indicate it has tilted 12" and not 2"...

dik: What is your article source for this 'revised' tilt, and what is the magnitude of the 'revised' vertical settlement?

RE: SF tower settlement

The one lawsuit indicated the 12" tilt and there was this news article:

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

Flexural cracking in concrete is very bad. Since concrete has a low tensile strength, reinforcing steel (rebar) is added to increase its ability to carry loads that would otherwise cause it to crack & lose its load carrying ability. Flexural cracking in concrete can lead to bond loss to reinforcement. Considering this is happening at the base of the structure, it is not a good situation. Gluing it back together with a structural epoxy is very slow & expensive. The cracks seen at the surface do not fully represent what might be going on inside the concrete. Fleural cracks can fold back on themselves, creating an interwoven network of cracks that are difficult to penetrate using standard gravity hydraulic injection techniques and require a very low viscosity epoxy with a long working time & exceptional patience & experience by the technicians.

RE: SF tower settlement

Any problem left ignored long enough will stop being a problem. Sometimes the cessation of one problem causes the start of another, but that's for others to deal with.

I am reminded that the lowest accessible levels in Venice, Italy were at one time second and third floors.

RE: SF tower settlement

See linked article. It seems like the this was the solution all the time, but it sure won't be easy.

RE: SF tower settlement

Without going to bedrock, I'd be really concerned with liquifaction of the supporting soil.

Dik

RE: SF tower settlement

(OP)
Piling to rock is good, but I wonder about their numbers. They are talking about 100 bored piles, each 10" to 12" in diameter. To me, that doesn't sound like the capacity to jack up that building.

RE: SF tower settlement

It's OK Hokie... They did the sums on it, just like the original foundation...

Dik

RE: SF tower settlement

LERA certainly knows tilting buildings Link
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

Epoxybot: With extreme settlement, the building with a twist, just screws itself into the ground.

Dik

RE: SF tower settlement

From the news,
"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

Clearly the Salesforce building should be modified to take the load then a 'skyway' needs to be built between them.

Keith Cress
kcress - http://www.flaminsystems.com

RE: SF tower settlement

They should have just built it with the flammable cladding. It'd be that much lighter, then when it burned, nobody would care if it was sinking or not- in fact, the more the better in that case.

RE: SF tower settlement

Here is a link to a cross section of the soil conditions commissioned by Transbay Joint Powers Authority TJPA for the neighboring Transbay Center. Link TJPA are a greater bay area, regional authority, so you can imagine the other parties would love for the Transbay Center to be partly/mostly to blame for the Towers settlement & tilt. Considering the circulation of water in & out of SF Bay, the ground section should largely be indicative of what lies beneath the Millennium Tower project. The Tower takes up the block between Fremont St. & Beale St. Horizontally flip the building section below, to overlay the soil cross section in the above link to get an idea what is going on.


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? bigsmile

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

RE: SF tower settlement

Thanks epoxybot...great post. "The first photo on the page gives a good idea of the concentration of piles under the tower. The 4th photo"... they don't mention the type of teaspoon used to place the concrete in photos 3 and 6...

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

As condo owners, are they responsible for maintenance costs? (part of condo fees?) as registered owners... even if they walk away...

Dik

RE: SF tower settlement

dik

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

I've said it before, and maybe even on this thread. Condominium projects are litigation magnets. And this one is the perfect storm.
  • 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

Jed... you'd think with all the lawyers that they would be able to 'plot a course' to wind this up... surprised the SEAOC wasn't a little more proactive. I guess no one wants to say anything for fear of it coming back to bite them... Read the ARUP report and thought it was very technical and very well done. A real concern is how this building might lay down in a serious seismic event... and, maybe FEMA will pick up the insurance tab...

Dik

RE: SF tower settlement

Would it be cheaper for everyone to put in re-leveled floors than fix the building? My old house had issues with a door not closing correctly because the ground was shifting. A contractor wanted to fix the foundation, I just adjusted the door hinge.

RE: SF tower settlement

The expectation is that re-leveling will soon be 90 degrees after the building lays down. Not only is the tilt increasing, the tilt rate is increasing. This is not a situation that ends well. Has anyone make a graph of the two factors or has the data been too poorly collected to make a useful prediction?

RE: SF tower settlement

I wonder at what point 90 degrees looks imminent and they begin to de-construct the tower to prevent it...

Dan - Owner
http://www.Hi-TecDesigns.com

RE: SF tower settlement

When do you start bailing your corporation out of the neighboring buildings?

Keith Cress
kcress - http://www.flaminsystems.com

RE: SF tower settlement

... or at least those in the direction of tilt <G>. Is there a site that has a running record of the settlement and tilt and rates of these? You'd think someone would be monitoring this.

Dik

RE: SF tower settlement

Quote (3DDave)

Has anyone make a graph of the two factors or has the data been too poorly collected to make a useful prediction?

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

According to one observation by a geotechnical engineer, sorry I didn't save the link, one problem is that the Transbay Authority, TJPA did too good of a job with their secant pile wall. The wall does too good of a job of resisting earth movement and without similar resistant walls on the North & West sides of the Tower, North & West is where the ground is shifting.
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.

RE: SF tower settlement

Perhaps the original plan was the tower would be on bedrock by slowly lowering itself thorough the muck, but the asymmetry introduced by the new construction has upset that plan.

What is very surprising is the effect the execution of the easement agreement had on the settling rate.

RE: SF tower settlement

Dave... nearly spilled my coffee...

Dik

RE: SF tower settlement

Another concern is that earthquake can cause liquefaction of the soil which would be catastrophic because the piles do not go all the way to bedrock.

RE: SF tower settlement

Correction: In my post on 25 Aug 17 01:44, I alluded to GFRP rebar in photos for the Millennium Tower reinforcement but after more searching it now seems that Baugrid is produced using smooth steel bar. The smoothness of the bar & the color of the surface corrosion on the bars led me to believe I was seeing GFRP.

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

All is well... at this time. From the report, "To an extent consistent with the scope of our review, our professional opinion is that the foundation settlement experienced by the Tower has not appreciatively affected the safety of the building at this time."

Sounds great, and at an inch per year, who knows... settled 18" so far.

Dik

RE: SF tower settlement

Quote (report)

Further, the review is
limited to evaluation of the current condition of the Tower and does not address the effects of
future settlement or other changes that may occur to the Tower in the future.

All was well July 28th; July 29th is out of scope. Does the report contain any useful information?

RE: SF tower settlement

stevenal... nothing of substance... nothing to give you a warm fuzzy feeling...

Dik

RE: SF tower settlement

That ought to increase the value of those condos.

RE: SF tower settlement

Description of the shoring work for the Millennium Tower & adjacent 5 level parking structure basement. Webcor Builders: The garage is an internally braced soil cement slurry wall system with soldier piles 5’ OC and the High Rise foundation is a soil cement slurry wall system with soldier piles 5’ OC with a few rakers and the balance of the hole supported with a single row of tiebacks. Both of these perimeter wall systems are augured 3’ diameter overlapping holes creating a continuous wall.

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.


RE: SF tower settlement

On Tuesday, October 3rd, 2017, UC Berkeley professor, Abolhassan ASTANEH-ASL, gave an Ethics Seminar: "Did the Unethical Conduct of Engineers and Academics Contribute to the Tilting and Sinking of the Millennium Tower?"

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.

RE: SF tower settlement

Really good article... I don't envy the position Abolhassan has taken... but, I think he's correct. At Harvard, he'd have been turfed.

Dik

RE: SF tower settlement

(OP)
Maybe there is some validity in some of his opinions, but he is a blowhard. Although he promised to limit his discussion of the WTC, he spent more than half the time talking about it. Then his only conclusion about the Millennium Tower was that the piles are too short. We all know that already. Ethics? He stated he doesn't know about geotechnical issues, but then proceeds to comment on the piling.

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.

RE: SF tower settlement

Blowhard or diehard or whatever, he raises some very good points for both the WTC and Millenium... call him Don Quixote... He likely feels 'slighted' and the presentation was his vindication. I've never seen a 'flat plate' with an 11" slab... contributes to the mass and rate of settlement...

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

RE: SF tower settlement

(OP)
11", and thicker, flat plates are common in my environment. That's what our builders and developers want. Simple, it is. He called it a flat slab, one example of my reference to terminology.

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.

RE: SF tower settlement

A flat slab in these environs is one with drop panels or slab bands or a mix...

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 747 767 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

RE: SF tower settlement

(OP)
Yes, that is my definition as well. I think the floors of Millennium are flat plates, but he called them flat slabs. I saw a report this morning about the Mexico City earthquake, where some California engineer reckons that flat slabs should be outlawed in seismic areas. I would agree, if there are not cores or shear walls, but the statement was misleading.

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.

RE: SF tower settlement

They can be adequately connected... bar joists may be the correct term (more likely) depending on how they are fabbed... My only reservation about bar joists is that they have a large surface area for fire resistance protection... on impact (like a plane), the fire proofing can be 'knocked off' leaving little or no protection. Prior to the 'attack' I thought the approach was real 'neat'. I still think it can be workable... my tallest building is less than 1/4 the number of storeys of the WTC... and, not what I would call a tall building...

Dik

RE: SF tower settlement

Hell hath no fury like a woman professor scorned

RE: SF tower settlement

Hokie66:
"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

RE: SF tower settlement

(OP)
I think the issue is the use of flat plates supported only by columns, with no other lateral system. But just to say flat slabs should be outlawed is ridiculoua. The old flat slab has a place in our tool kit.

RE: SF tower settlement

This is diverging the discussion a bit.. but this dude's assertion is that WTC building failures were due to unethical or, at best, ethically ambiguous behavior by its engineers? Really?

RE: SF tower settlement

jgKRI: The part I got from his presentation was that there were some questionable decisions made with any peer review... and, if his information is correct, then I concur with some of his criticisms.

Dik

RE: SF tower settlement

2
Sorry I got carried away...,
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

You didn't get carried away... to paraphrase your effort, "It's a mess and no one is moving forward at fixing it." I guess it's a problem with self-regulating agencies, that unless someone files a complaint, they have no reason to undertake an investigation of their own. Thanks for the excellent 'write up'.

Dik

RE: SF tower settlement

(OP)
Great post, epoxybot. If only some of those professors at UC Berkeley had the same ability to sort through the chaff and get to the real issues.

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

If these people still live here,in San Francisco, the tenets on this highrise should be able to manage.

RE: SF tower settlement

San Franciscans have reason not to have a lot of confidence in their building officials. The owner of this property & the manager of the company doing the work was a former President of the SF Building Inspection Commission & the EOR was also a former BIC President.

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...



Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close