San Francisco high-rise sinking, tilting

stick n move said:
Someone either just fucked up or the transbay really affected it.
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Please stop trying to pin this on Transbay and don't call it "tunneling" * The Transbay terminal is just a pit with a cavity on its bottom for the future CA HSR station at its bottom. And Transbay hasn't done any tunneling, since the CA HSR approach tunnel is unfunded)

Yes this source is TJPA itself, but the math is airtight, as far as what our default supposition about the sinking is concerned:
By the time the TJPA started work on its [Transbay Terminal] project in 2010, the Millennium Tower had already settled ten inches – four more inches than Millennium’s engineers predicted over the life of the building. The building has continued to settle vertically, now 16 inches, even after the TJPA completed the excavation for the Transit Center. A foundation of piles down to bedrock would have prevented.
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Emphasis mine.

2006 -> 2010 = 10 inches of sinking in 5 years (2" per year)
2011 (Dec) Transbay turns its first shovel full
2014 (Feb) Transbay completes excavation of its foundation
2011 -> 2016 = 6 inches of sinking in 6 years (1" per year)

If anything, sinking has been 50% slower with Transbay excavating next door!

*To be fair, the poster who said "tunneling" hasn't used the term again. There will be new HSR/Caltrain tunnels serving the Transbay Terminal, and there's also a study for a new BART transbay tunnel, so the confusion is likely going to be a constant thing wherever the term "Transbay" is used, but let's try to nip it in the bud.
 
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^Not blaming Transbay. The way short piles work is that the large amount of friction between the soil and the pile allows the pile to support a certain amount of load. This is fundamentally different than the way a deep/anchored pile works, where the bedrock itself is carrying the load (or portion of load). Short piles are a perfectly legit/proven system in many applications, but success depends on the geotech engineer making the correct assumptions about the soil type/packing and other factors - e.g., what drives the amount of friction that will actually exist at the exterior of the pile, thus affecting its load carrying capacity. So obviously some assumption(s) made here didn't match reality, insufficient core tests were made, etc etc... (also these cast concrete skyscrapers are freaking heavvvvy, which of course the engineer should have known...unless eng. was under-informed about other downstream decisions)

The geek in me would love to see what they do. This sort of scheme (below) with tension/compression pile pairs, both anchored to bedrock, with cantilevered needle beams might work. (obv. this picture doesn't exactly reflect this reality...SF MT is on a big mat slab IIRC...but the concept is the same).

cantilever2websitefinal.jpg
 
^^^^^
The right thing to do is TEAR This down and rebuild it before somebody dies.

Insurance companies will try to find a loop hole out of this mess.
 
Regarding Transbay,

Transbay has stated it spent $58 million buttressing the below grade side of Millennium before it (Transbay) began excavating.

Transbay is an entity of the state; that may limit its liability under California law (the sovereign must consent to be sued) particularly if any negligence on its part is only ordinary negligence. (Don't know whether California also caps damages with respect to a successful claim against a state entity.)
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Regarding DeSimone, the structural engineer/ From DeSimone's website:

Tallest reinforced concrete structure on the West Coast.
>Four levels of parking are provided below grade, requiring a 75 ft deep excavation, one of the deepest in San Francisco
>The subterranean levels utilize an internally braced soil cement slurry wall system with soldier piles located five feet on center
>The tower’s lateral system is comprised of a 24-inch thick concrete shear wall core and a partial perimeter moment frame
>The tower is designed using both a Performance-Based Design (PBD) solution as well as a code-based design approach
>A dual system was the best solution due to the higher than normal seismicity at the site
>Because a PBD approach was used, we were able to optimize the design of the perimeter frames and reduced their sizes more than what would typically be allowed by code.
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Regarding seismicity and liquefaction.

The project [a small, several story building] site [near Transbay] is located within a Seismic Hazard Zone (Liquefaction Hazard Zone likely underlain by artificial fill). Any new construction on the site is therefore subject to a mandatory interdepartmental Project Review. A geotechnical study prepared by a qualified consultant must be submitted with the EEA. The study should address whether the site is subject to liquefaction, and should provide recommendations for any geotechnical concerns identified in the study. In general, compliance with the building codes would avoid the potential for significant impacts related to structural damage, ground subsidence, liquefaction, landslides, and surface settlement.
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The quotes below are from a recent environmental assessment of a transportation project along Geary Boulevard. The east end of the Geary corridor is the Transbay Center.

Where the original [San Francisco]shoreline has been historically modified at the extreme east end of the Geary corridor, [mear/at Transbay] artificial fill has been mapped from approximately Market Street to the present shoreline to the east of Market Street. The fill is resting on bay mud. The materials used to construct the artificial fills are highly variable and generally consist of clay, silt, sand, and gravel with concrete, brick, and wood debris.
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There is a note that bedrock may be as much as 250 feet below the surface in this area. Apparently there is a valley.

Liquefaction occurs when saturated, low relative density, low plasticity materials are transformed from a solid to a near-liquid state. This phenomenon occurs when moderate to severe ground shaking causes pore-water pressure to increase. Site susceptibility to liquefaction is a function of the depth, density, soil type, and water content of granular sediments, along with the magnitude and frequency of earthquakes in the surrounding region. Saturated sands, silty sands, and unconsolidated silts within 50 feet of the ground surface are most susceptible to liquefaction. Liquefaction-related phenomena include lateral spreading, ground oscillation, flow failures, loss of bearing strength, subsidence, and buoyancy effects.

Lateral spreading is a form of horizontal displacement of soil toward an open channel or other “free” face, such as an excavation boundary. Lateral spreading can result from either the slump of low cohesion and unconsolidated material or more commonly by liquefaction of either the soil layer or a subsurface layer underlying soil material on a slope, resulting in gravitationally-driven movement. Earthquake shaking leading to liquefaction of saturated soil can result in lateral spreading where the soil undergoes a temporary loss of strength. As shown in Figure 4.7-3, the Geary corridor east of Grant Avenue is highly susceptible to liquefaction. [This includes the area at the Transbay Center.]
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Sand boils and lateral spreads have been documented near the old San Francisco Bay shoreline at the east end of the Geary corridor from both the 1868 Hayward and the 1906 San Francisco earthquakes (Knudsen et al. 1997, and Youd and Hoose 1978). Judging from documented cases from historic earthquakes, the potential for liquefaction and lateral spreading is considered to be very high at the east end of the Geary corridor in the vicinity of the historic San Francisco Bay shoreline.
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emphasis mine
 
stellarfun said:
Regarding seismicity and liquefaction.

Sand boils and lateral spreads have been documented near the old San Francisco Bay shoreline at the east end of the Geary corridor from both the 1868 Hayward and the 1906 San Francisco earthquakes (Knudsen et al. 1997, and Youd and Hoose 1978). Judging from documented cases from historic earthquakes, the potential for liquefaction and lateral spreading is considered to be very high at the east end of the Geary corridor in the vicinity of the historic San Francisco Bay shoreline.
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I lived in Oakland when the Loma Prieta hit in 1989 and a good friend of mine lived in South of Market about four blocks west of the Millenium tower site. Back when South of Market was mostly blue collar low-rise shops and artists' lofts. My friend saw sand boils directly in front of his place, little geysers of extremely wet sand spurting up from pavement cracks, about 12 inches high, in rhythm with the quake. His location was a wee tad firmer than the site Millenium is on.

I am gobsmacked that a tower could win approval for what is essentially a floating foundation. Granted, it's a huge mass of concrete, I'm sure they did seismic calculations, etc, etc. But I thought CA had gotten completely away from that sort of system. The old Bay Bridge foundations (east of Yerba Buena Island / tunnel) had exactly that problem. The muck was so deep that back in the 30s, they opted to just plunk immense concrete foundations under each tower instead of trying to get down to bedrock. And then the expansion joints along the trestle had way more slip slide leeway than one normally finds in bridge expansion joints. Turned out not to be enough leeway in the Loma Prieta, hence a section fell. And when they ran the numbers after Loma Prieta (which was only a sort of biggish one), they concluded that the whole thing would fail badly in The Big One. Necessitating the new bridge on that span.

I had thought that engineers had lost faith in that general concept of a huge mass of concrete instead of reaching for the deep rock. Apparently I was wrong. I'm still really stunned though. I was on firmer ground in the Loma Prieta, and I am to this day still awed at how liquid the earth became. I don't care how big that foundation mass is, with the muck it's sitting on, I cannot comprehend how it will stay vertical in The Big One.

Are there other SF towers using that style of foundation? I thought they generally ran pilings to bedrock?

All that is aside from the settling issue, which may or may not be the Transbay work next door.
 
In an 8.0+ magnitude earthquake could a building like this just fall? In that case it would be another 9/11, just this time caused my mother nature and not by terrorists.
 
West,

There are claims that MT-SF is not the only SF tower not grounded to bedrock. It may be that with changes in code post 9/11, the structural engineers thought the thick concrete mat and the reinforced concrete core was enough. The code changes started becoming effective in 2009.

After the tower began leaning, which was before occupancy, the city's building inspection department write to Millennium, asking what was going on? The reply to the city by DeSimone, the structural engineer is missing from the files. The San Francisco Board of Supervisors is holding a hearing later this week on why the city approved occupancy for a building that had begun to lean. It seems likely that San Francisco will pass an ordinance prohibiting this construction method, at least in seismic-risk areas.

The Board of Supervisors is rightly concerned that the city will be joined as a defendant, for awarding a certificate of occupancy. The condo owners will all swear they relied on that certificate when purchasing a condo, and would have never bought if the city had not issued the certificate.

The fire department is concerned that the elevators will go out of plumb, and be useless. Don't know if there is an engineering solution to out-of-plumb elevators in an occupied tower, and if there is, how long is the tower uninhabitable while the fix is made?

To my mind, the condos are essentially worthless at this time. No one has proposed a fix, let alone who will pay for it. So even if I bought a million dollar condo at a distressed prince of $100,000, I have no friggin idea of how much any assessment on the condo owners will be for the fix. Even if the condo owners first fix, and sue to recover their costs from all/some of the defendants, that could take years.

The following quote is with respect to a 110 year old, small two story house, no basement, on Rincon Hill. It is to be demolished.
According to the proposal going before the commission, "the building was constructed using a foundation with footings that were set directly on top of loose sand fill. As the building continues to settle, the footings have cracked and will continue until the foundation fails."
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And finally, from Shanghai, one month ago. Excavating next door, no buttress. 'So it goes', or rather, 'over it goes'.

18mllsnbhj7pwjpg.jpg
 
That is all some serious risk, stellarfun, and I agree with your assessment of it.

This becomes an issue for us on the Winthrop Square bid by Millennium. This situation in SF is the kind that could, in a worst-case scenario, go blasting past their liability coverage limits, including whatever umbrella coverage they carry. I like the work they've done here, but if I was underwriting them as a project sponsor of something as big as their Winthrop Square proposal, I'd have some serious questions for them.
 
Could the windfall from this put Millennium out of business?

They'll probably loose hundreds of millions from this.
 
Millennium blames Transbay for pumping out groundwater.

http://www.bizjournals.com/sanfranc...lennium-tower-developer-sinking-tower-sf.html
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tysmith, major developers typically create a separate, legal entity for each project, to minimize financial problems at one site from materially affecting other properties.

When the last of the MT-SF condos were sold several years ago, the legal entity that built the building, sold the condos, and paid off the investors, may have dissolved. Those legal entities don't last forever. The legal entity probably created a modest reserve to pay for future claims. Following dissolution, I would think Millennium Partners would have become the successor in interest, the payer of claims, and the party to be sued.

As narrated by the press, MT-SF began sinking beyond expectations before Transbay did anything next door. Thus, IMO, Millennium can't and won't escape at least some financial liability. There will be finger-pointing between Millennium Partners, Handel, and DeSimone, and their respective insurers. The Millennium group of defendants will then collectively point fingers at Transbay, which, as a state entity, may have no or limited liability for any actions it took, or failed to take. You probably need to prove that any Transbay negligence was more than simple negligence to get big money out of Transbay, and IMO, that's a high hurdle.

The condo owners could sue the city, alleging that a certificate of occupancy should not have been given.

What is to be revealed is whether Millennium applied political pressure to get the certificate of occupancy. That DeSimone's letter to the city is now mysteriously missing, hints that the letter, in the current light, might prove embarrassing to DeSimone, the city, or both.

As West indicates, the liability cloud that now hangs over MT-SF could affect the ability of Millennium to secure financing for major new projects, or significantly increase the cost of financing. The ability to finance, and the cost of such, could be favorably affected if Millennium has sufficient equity in any buildings that it does own as the equity could be used to pay claims that potentially may amount to hundreds of millions of dollars.

If the legal entity that built MT-SF still exists, it is probably a candidate for bankruptcy. How a bankruptcy would affect Millennium itself, I don't know.
 
Wow:
one of the possible solutions proposed by an engineer whom homeowners have consulted is to lessen the weight of the building by lopping off the top 20 floors.
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From: https://www.bostonglobe.com/news/nation/2016/09/23/san-francisco-millennium-tower-gives-residents-sinking-feeling/49OQyojO6Baee2eLIGfAjP/story.html

I have a hard time believing that is more feasible and cost effective than underpinning, but, as we were saying, these reinforced concrete skyscrapers are extremely heavy.
 
The Globe article is a reprint of a NY Times article. The article answers why DeSimone's letter is missing, because the city building inspection office was not required to keep such letters.

At the time, the city apparently had no expertise with respect to the adequacy of the design, nor, supposedly, was it required to have such expertise. This is a possible defense to the city issuing a certificate of occupancy.

Millennium said nothing about the sinking (already underway) to prospective purchasers before they bought.
 
No matter how Millennium spins this---The blame game is on.

Millennium is definitely responsible at some point---They are the developers of the site and should have hired compement people to review the foundation.

If I was Millennium at this point I would knock the building down and rebuild it.
I would gather every group involved including city/state officials for approving the site as the development continues and try to reach a compromise before this gets really ugly.

Start taking the loss on this because this could be very harmful for Millennium reputation.

If Millennium walks away from this scenario that tells you what type of people we are dealing with and I would not let them build in our city because you know how they handle problems that exist.
 
I'm assuming this building needs to be knocked down.

Has there ever been a development of this magnitude that would have to be knocked down? (Any other case studies)
I'm thinking they take a 200+% Loss on this development I'm not sure how these deals are structured but this could cause bankruptcies for companies .
 
If the city attorney is able to prove the 'fraud' claim, its highly likely that MP could be left holding the bag. Insurers don't typically pay out to the insuring party when the party has engaged in fraud.
 
MP seems to be a private company---- Most likely they would probably take the company into bankruptcy:

I'm not sure how deep their pockets are to take this type of hit.
 
TheRifleman said:
I'm assuming this building needs to be knocked down.
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Why do you keep saying this? I agree as much as everyone that this is a train wreck, but knocking down a 58-story building is really, really expensive (not to mention ALL of the condo owners would need to be bought out, and/or paid off via a class action suite or something).

If you're gonna spend hundreds of mil, why knock it down?
Hundreds of millions can save the building. You can essentially build an entirely new foundation system, to bedrock, for that kind of money.

Remember, buildings always settle. It's just that this one is doing it much too quickly. Stopping/slowing the settling to an acceptable level will work just fine. The structure of the above-ground part of the building is not what's being questioned here.
 
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