SF Tower settlement Part II 18

[1503-44]

"Appreciation has dropped to 2%"
Well that's less than inflation, but more than interest rates.

Although as I said, probably nobody bought in for either of those reasons.

“What I told you was true ... from a certain point of view.” - Obi-Wan Kenobi, "Return of the Jedi"

 

[dik]

Most people aren't aware that Pisa is 'curved'... the masons built it plumb as it settled... building a 'curve' into the structure.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[dik]

They need to take it to bedrock... They've looked into it... but I have a concern about liquifaction in case of a seismic event.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Tomfh]

They need to take it to bedrock..

Isn’t the rest of it floating in soil?

 

[TugboatEng]

It's interesting, there is quite a bit of settlement in SF. My friends working as operating engineers in SF have had to renew connections due to utilities due to the large amount of settling experienced. Much of the city is built on fill. The fact that Millennium tower has favored a side to settle on could be why the Trans Bay Tube constructors are interested in settling themselves.

 

[dik]

My understanding... and the reason for the settlement... I don't know how you address the difference in stiffness between the two types of foundations.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[epoxybot]

San Francisco has some of its utilities resting on piles to prevent them from settling with the fill. When you see a blue topped fire hydrant, it is part of the emergency/cistern based fire fighting system established after the 1906 earthquake. All of that system rests on piles.

Mission Bay is the one of the newest development ares in SF and they have a huge problem with ground settlement.
Link

Attached is a pile map showing the depth of piles driven. The white piles are cut short, the blue piles are Re-strike quality piles. There are more (re-strike) piles on my map than listed by Treadwell & Rollo, as I added all piles with less than a hundred blows in the last 5 feet and then went through the list and added some piles with descinding blow counts; which appeared to have blown through the crust layer between Colma/Marine sand layer & a Marine Mud layer. It is the short cut piles that will prove the most resistant to the scheme proposed by SG&H.

 

[epoxybot]

Why can't I see my attachment?

 

[Tomfh]

Mission Bay is the one of the newest development areas in SF and they have a huge problem with ground settlement.

What is this area built on? Is it some sort of reclaimed land? How has it settled so much so quickly?

 

[epoxybot]

Yes, Mission Bay is all fill. There is an interesting film "Erased Landscape" about the filling in of Yerba Buena Cove & Mission Bay. Link

 

[epoxybot]

Link to the Engineering Design Review Team's Comment Log for the perimeter pile upgrade.

 

[dik]

The last comment is nearly 2 years old... anything more recent?

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[epoxybot]

Updated Presentation by SG&H of the Settlement, Tilt & Repair to the University of Minnesota.
There are a few new slides plus some photos of work. Presently they are working on the "Indicator" pile on the corner Mission & Fremont streets.

Link

 

[epoxybot]

Looks like the perimeter pile work has had some hiccups. I'm a bit surprised this upgrade work is getting so little coverage from local news outlets. These permits were only posted to SFDBI's permit page for 301 Mission in the last week.

https://skyscraperpage.com/forum/showthread.php?p=9198852#post9198852;

As much as it has been stated by Millennium & SFDBI that the tower was built to code, I stumbled across this tidbit the other day. See page pdf. page 54 Link

By the time new plans had cleared SFDBI plan check, 16 floors & 19 levels of core had built.

 

[dik]

Thanks Epoxybot for the update on this project.

Neat report... it would be nice to see Other SF Buildings with that type of Foundation be shown on p9 showing their width and height to compare. It maybe not germaine. Some queries/comments, though...

It's nice to see the causes shown on page 10... I understand that ARUP looked at this a while back during construction of the Transbay Terminal and that most of the settlement had already occured. Tilt wasn't mentioned... maybe just a recent afterthought.

I'm not sure what the references to the pile loads are. I don't know the reference of the 1175K and 1227K loads on page 26 and what the actual design load is.

I'm not sure of what happens in an earthquake if the North and West sides of the building are on bedrock? I would think this would introduce a massive eccentricity.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[hokie66]

Interesting that their favorite costs for change orders are either $1.00 or $50,000.00.

 

[epoxybot]

I suppose I could have elaborated more on the document link I posted. It is from the Peer Review done by Hardip Pannu during the construction of the tower and the subsequent testing of Baugrid.
The SFDBI letter on page 54 of the pdf. explains that the results of testing of Baugrid showed that it would not be equal to a 1:1 replacement. Hardip Pannu & UCB Prof. Jack Moehle subsequently wrote a Peer Review letter of acceptance of Baugrid based on Performance-Based Design.

Over and over Millennium Partners, DeSimone & Webcor AND later SG&H & the city's own 2017 301 Mission Seismic Safety Review Peer Review panel have described the tower as Prescriptive-Based (Code) Design. It just isn't so. All the vertical elements & tie-beams are built with Baugrid. The tower was 16 floors & 19 core levels up when the test results were finally determined. Naturally, SFDBI did not retain the 4 binders of Superstructure calculations nor the 2 binders from Baugrid Peer Review. There are other elements that push this building into the Performace-Based catagory, including the 1st such use of 10,000psi concrete, along with a SCC admixture. Also, throughout the original construction Peer Review, Hardip Pannu of Middlebrooke-Louie, is asked to perform Non-linear analysis to resolve issues which break from ACI & the building 1997UBC/SF2001 code.

A geotechnical engineer, Laurence B, Karp, wrote to SFDBI regarding the Lera/Engeo "symmetrical upgrade" vs the SG&H/Slate asymmetrical (Perimeter Pile Upgrade) Link.

From his website page "Millennium Tower Debacle" I gather that Mr. Karp was working on behalf of Jerry Dodson, an toer condo owner/engineer/attorney, who was part of one of two major litigation groups of tower residents. Jerry Dodson was of a mind that Millennium Partners & SFDBI were the parties principally responsible for poorly performing tower. You can find DeSimone's 4 volume foundation calculations & Treadwell & Rollos 2 geotechnical reports on his website. The second of the 4 volumes includes more of Hardip Pannu's peer review communications with DeSimone and reveals a greater extent to Prof. Jack Moehle's 'Consultant Work' on the project.

There were obvious inconveniences to the symmetrical pile upgrade and also an extended time element. The symmetrical plan called for installing piles down through the mat, first to the west side of the tower/core, to halt settlement and reverse the tilt; followed by installing the remaining piles to the east side of the tower/core, at a later date (years). Then a smear campaign was initiated to inflate the cost of the Lera/Engeo proposal. It maybe that the figure that went from $100-150 million to $450 million in the press was subsequently used to arrive at a settlement figure; wherein the class-action members get to devy up the 'undisclosed amount' that goes beyond the cheaper SG&H retrofit.

One of the entries to the Engineering Design Review Team's Comment Log (posted above Feb 25 2021) inquired about the results of Lera/Engeo's investigation of the current relationship between the tower podium shoring wall and the bottom of the towers mat foundation. The gist is that if the tower tilts back to the east by 2 inches, it will come to rest on the shoring wall. SG&H response was that the weight of the tower would then cause the 3 foot think 180 foot long 90 foot deep shoring was to settle. The 'experts' of the Engineering Design Review Team seemed satisfied with this answer, while completely ignoring that it results in an entirely new seismic condition. Just imagine a 10 foot thick concrete trampoline.

The 2017 City of San Francisco's Peer Review of SG&H's investigations resulted in a report by Standford Prof. Gregory Deierlein which stated that all the deformation of the mat foundation took place before the end of 2009. The year the building was finished & open for occupant.

Millennium Tower's HOA hired Cotton-Shires geotechs in late 2016 to examine the building and while we don't know what was specifically said at the meeting that followed, resident Pamela Buttery later exclaimed to news reporters; that 'they had been told by the engineer (Cotton-Shires), that the tower was too heavy for its foundation'. Of course Millennium blames dewatering but the Old Bay Clay doesn't give up its water to freely and is 90 feet bgs. And then the TJPA & Saleforce Tower used Cut-Off shoring walls. Post construction settling is the result of deformation of the Old Bay Clay. Nobody involved disputes this.

It needs to be remembered that when the tower was only 11 or 12 floors up, Webcor tied the east side of the foundation to the tower/podium shoring wall and then proceeded to stack 30 more floors on the tower (131 million pounds). All the while excavating a 56 ft deep hole in the ground immediately adjacent to the tower. From court records it is seen in emails that Webcor notified Treadwell & Rollo that the tower had shifted to the east shortly after tying the tower to the shoring wall. So the tower was sinking, drifting and the foundation tied to the wall by 25 each H-beams tied to the shoring walls soldier piles. Ron Hamburger is wrong if he thinks the shoring wall will settle if the tower comes to rest on the shoring wall. It has already borne a good deal of the tower's weight. Obviously not the entire 131 Million pounds was carried by the shoring wall.

I think it is safe to say that everything that is wrong with the tower became manifest during it construction.

From my post of May 26 2021, linking to a presentation by Ron O. Hamburger at the Univ. of Minnesota; I extracted the SG&H's forecasted settlement map and I overlaid it onto my Low Pile-to-Mat Fixity map, which I built in Excel. It is concerning. In a discussion before the SF Government & Oversight Committee's Hearings into the 301 Mission St. settling, the chair of the city's Peer Review team, Gregory Deierlein, stated that previous investigations by SG&H had not looked at the piling, so that was something they wanted to have reviewed. SG&H got the reinforcement in the top of the piles completely wrong. They is a worrying cluster of piles just outside the south-south-east portion of the shear-wall/core and near the south-east super-column that have only half of their 8 each #9 rebar in the tops of the piles. These piles were driven to refusal with 3 to 6 broken piles within the area with piles of reduced pile-head rebar. And then their is the buried PG&E vault.

The piles that were driven to refusal short of their design elevation represent "Hard End-Bearing Piles" in a field of soft piles. At least two engineers have speculated that piles under the tower may already have been damaged and that was without knowing any of what I've written. Since the tower is only 2 inches above the tower/podium shoring wall (10 inches of settlement), then these piles have either settled with the Old Bay clay or something worse had happened to them.

I sent my concerns to SFDBI's Gary Ho and his Head of Plan Review...que the chirping crickets.

 

[dik]

I'm surprised... do they really have 'Prescriptive-Based (Code) Design' for a building of that size? and

this is consistent with ARUP. I've never been involved with one of their projects but based on what I'm familiar with they are better than 'top drawer'. A class mate of mine worked with them for a few years... he left and worked in a brewery; the pay was much better.

Also a young engineer I worked with at Crosier's was with them (over 50 years back)... He was the first IStructE guy I met... also top drawer. I was going to join, but got layed off first. That's when I realised I should have gone into medicine.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[JedClampett]

So you made the choice to deal with sick people (engineers), instead of physically sick people.

 

[dik]

Thanks, Jed... needed that. Hehehehehe... sorta deserved it. I decided to go into engineering on my way out to university to register... not a deep thinker.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[geochase]

The "fix" has been halted....

https://www.nbcbayarea.com/investig...x-of-san-franciscos-millennium-tower/2639941/