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SF Tower settlement Part II
18

SF Tower settlement Part II

SF Tower settlement Part II

(OP)
"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"

RE: SF Tower settlement Part II

3
Powerpoit/PDF presentation "The Millennium TowerSettlement, Tilting and Upgrade"
by Ronald O. Hamburger, S.E., SECB of Simpson, Gumpertz & Heger.
University of Kansas 5, March 2020
Link

RE: SF Tower settlement Part II

This is a silly question, but if it has sunk 16" how are all the entrance doors still working or if the entrance doors and thresholds are also sinking with the foundations - surely there would be a very noticeable ramp/step down into building?

Explain!

Brian,

RE: SF Tower settlement Part II

I would imagine the building isn't slipping into the Earth like a peg in a hole... there has to be some form of slumping along the edges. Maybe not enough to completely eliminate a threshold tripping point, but surely the surrounding sidewalk is tilting somewhat.

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

RE: SF Tower settlement Part II

There's serious damage to the sidewalks around the building.

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

-Dik

RE: SF Tower settlement Part II

I would like to see settlement and tilt info newer than 3 years old. Retrofit piling was supposed to start in November but no news on that. I wonder if delays will allow the project to pass the fix-it stage.

RE: SF Tower settlement Part II

In July the press reported the tower had sunk a total of 18 inches and was tilting 14 inches. So about 2 inches since the fall of 2016, if I recall correctly. The powers that be, likened the slowing of the sinking to the secession of work on the White Elephant (TJPA) next door.
Serendipitously, the mat foundation extends beyond the only entry/exit affected by the sinking.

Correction: The sinking of 18" & tilting of 14" are from 2018, which according to another article from July 2020, was the last time these factors were made public.

The only entry/exit points affected are the lobby entrance on Mission St. (photo) and the access points on 3 levels between the tower and the podium structure. So the patio, the indoor pool level and basement/garage access. These last three have been a bit of a terror for the HOA & Millennium Partners, as they must be Handicap Accessible. Of course the SF Dept of Building Inspection has been very vigilant of this process, not wanting to be found lacking, as they were from the start.

RE: SF Tower settlement Part II

So does the surface drainage still work? Does water run back into the building?

RE: SF Tower settlement Part II

There have been modifications made since to the entry. The entry from the planter to the doorway has been replaced.

RE: SF Tower settlement Part II

Nice Hamburger report... did they start the remediation on May 1 of this year? It's nice to have loading going down to bedrock... until it does, is there a chance for a seismic event to liquify the soil beneath the building? There seems to be no mention of what will happen if they just leave it and don't repair... no prolonged time sensitive curves showing the increased settlement and/or tilt.

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

-Dik

RE: SF Tower settlement Part II

Thanks... I'd wait until the problem was fixed before signing off on anything... what if the repair is never undertaken or if it doesn't work?

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

-Dik

RE: SF Tower settlement Part II

Quote (Dik)

... until it does, is there a chance for a seismic event to liquefy the soil beneath the building?

The mat foundation sits on young bay mud, below the non-engineered fill layer, which is from 17 to 42 feet thick, across the whole of the site. It would require a sustained, high magnitude earthquake to mobilize the QYBM.
I think the fun really begins when they remove the CDSM shoring wall on Fremont & Mission St and the Play-Doh starts production.

The headline of the SFist article, posted by Jay, is misleading, as most of the $30 million, ascribed to SF Taxpayers will be borne by US, State and Bay Area Taxpayers, including $1 dollar from every vehicle that crosses the SF-Oak Bay Bridge, ticket fares from CalTrain riders & Alameda-Contra Costa bus riders.

The people of SF & SF Government are let off the hook quite nicely. SF Govt's contribution to settling the Millennium Tower litigation was waiving the $3.10/sf/yr sub-sidewalk rental fee for the long-term right of the Millennium HOA to make incursions into the public right of way (Below Sidewalk). About $8500/year.

RE: SF Tower settlement Part II

Screen grab captured from a YouTube video Dec. 10m by a package delivery guy who skateboards (Electric) around SF.
It looks like they are just getting started.

RE: SF Tower settlement Part II

thanks... I was thinking for the settlement to have occured so quickly that there must be a fair flow... maybe not.

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

-Dik

RE: SF Tower settlement Part II

Quote (Dik)

I was thinking for the settlement to have occured so quickly that there must be a fair flow... maybe not

The tower settlement or the litigation settlement?

RE: SF Tower settlement Part II

they could both go on for decades...bigsmile

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

-Dik

RE: SF Tower settlement Part II

From the SkyscraperPage Forum, a couple of photos from Feb. 8, 2021
Link

In these photos they are currently driving soldier pile & lagging shoring.

RE: SF Tower settlement Part II

Now if they had just had this technology in Pisa back in the 12th century...

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 Part II

What are the odds this’ll work?

RE: SF Tower settlement Part II

Quote (Now if they had just had this technology in Pisa back in the 12th century...)


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

RE: SF Tower settlement Part II

Quote (What are the odds this’ll work?)


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

RE: SF Tower settlement Part II

Quote (Dik)

They need to take it to bedrock..

Isn’t the rest of it floating in soil?

RE: SF Tower settlement Part II

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.

RE: SF Tower settlement Part II

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

RE: SF Tower settlement Part II

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.

RE: SF Tower settlement Part II

Why can't I see my attachment?

RE: SF Tower settlement Part II

Quote (epoxy)

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?

RE: SF Tower settlement Part II

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

RE: SF Tower settlement Part II

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

RE: SF Tower settlement Part II

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

RE: SF Tower settlement Part II

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

RE: SF Tower settlement Part II

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=...;

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.

RE: SF Tower settlement Part II

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

RE: SF Tower settlement Part II

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

RE: SF Tower settlement Part II

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.





RE: SF Tower settlement Part II

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

[quote Millennium blames dewatering but the Old Bay Clay doesn't give up its water to freely and is 90 feet bgs.[/quote]

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

RE: SF Tower settlement Part II

Quote (That's when I realised I should have gone into medicine.)

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

RE: SF Tower settlement Part II

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

RE: SF Tower settlement Part II

Looks more interesting, if you cannot get in to fix it. I don't know if the soil is unstable (sometimes a problem with marine clays) It looks like the problem may be a little more difficult than initially assumed. I don't know when it becomes dangerous... California like Florida, only bigger.

East of Winnipeg, a while back, we had a grain elevator fail in Transcona. It was a excellent example of Terzaghi's proposed manner of failure... It happened shortly after he came out with his failure mode. It is likely that Russia knows Winnipeg as being west of Transcona.

I'm sure glad that I wasn't involved.

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

-Dik

RE: SF Tower settlement Part II

Someone needs to publish a new engineering correlation between building list angle and rate of capital appreciation, decline in which was the spark for the mitigation project. It will go negative pretty soon if this keeps up.

RE: SF Tower settlement Part II

You forgot the lol

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

-Dik

RE: SF Tower settlement Part II

Quote (Someone needs to publish a new engineering correlation between building list angle and rate of capital appreciation)


It did wonders for Pisa...

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

-Dik

RE: SF Tower settlement Part II

If you want to reduce settlement in the northwest direction, do not drill 36" dia. piles through the unconsolidated marine clays and old bay clays and give a path to release the excess pore water pressure from the 10' thick matt and pile group sitting on them and thereby increase the settlement instead of slowing it down. I'm no geologist but my god you don't have to be to know this was a very bad idea. We know that the direction of natural excess consolidation is in the northwest direction so lets not drill more holes to give a path to relieve any added pore water pressure in both clay layers.

RE: SF Tower settlement Part II

The 36 inch parts were the casings. The drove the piles inside of the casings. It seems they had thought of the problem but their solution wasn't adequate. Remember, these are the same engineers that blamed the sinking on the Trans-Bay terminal nextdoor so it appears they have been hyper-focused on issues near the surface but now it becomes obvious that the problem is deeper.

For a tangent, there is a naval architect that seems to have trouble estimating the as constructed weight of their vessels. They had to sponson one after sea trials and another required crane assistance to get out of the drydock. Anyways, in both cases the vessels weighed much more than predicted and I wonder if the same is true for this building.

RE: SF Tower settlement Part II

Thanks... problem eluded me... My original thoughts were that the pore water was seeping into the shaft, like a 36" dia well, but the report for the Trans Bay Terminal by Arup 'dispelled' the moisture loss. Our clays are so impermeable that I had no problem with their explanation. I also thought that the thick slab wasn't supporting load and it was used to transfer the friction pile loads to the building... maybe with their failure, it has become a mat foundation too, or maybe it was designed that way (I would normally only use the value for the friction piles and not a combination).

This complicates the 'fix' by a whole magnitude. Has there been a real serious look at the actual dead load of the structure... with all the owner fixings?

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

-Dik

RE: SF Tower settlement Part II

Quote (TugboatEng)

The 36" parts were the casings

Just my point. So the casings were open for the pile driving which allowed a perfect path for pore water pressures in the clays to be releasd and allow faster settlement. The driven piles were not carrying any of the load yet but allowed pore pressure to drive water from the clays, particularly the marine clays, and cause more consolidation. Average pressure on the 10' thick slab and pile group was over 11 kips per square foot according to the presentation of the solution when proposed.

RE: SF Tower settlement Part II

Youda thunk that with all the mimes involved that they would have looked into that type of problem.

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

-Dik

RE: SF Tower settlement Part II

Quote (dik)

with all the owner fixings?

That was exactly the problem on the sponsoned vessel I mentioned. On the first the architect let the shipyard choose the fixings. The second vessel the architect chose the fixing and it did not require sponsons despite otherwise identical construction.

RE: SF Tower settlement Part II

Quote (dik)

Youda thunk
Pore water is not free flowing water it is usually released under excess pressure leading to further consolidation. Pressure on the old clays was in the order of 0.7 x 11000 psf (from pressure bulb under pile group) or about 53.5 psi. Pore pressures were much higher with the building loading than without. All of the pressure was now being released in the direction to increase the differential settlement. I'm betting that they didn't have their piezometers installed yet to monitor pore pressures. Hey I'm just a simple engineer that used Terzagi and Peck 1967 as my soils text book.

RE: SF Tower settlement Part II

I would have thought all water contained in clay, other than that adhered to the clay 'platlets' was in the form of pore water. Our high plastic clays are nearly impermeablej, but they do consolidate (we have a slightly different issue they are still 'springing' up from the last glaciation).

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

-Dik

RE: SF Tower settlement Part II

Clays are impermeable but excess pore water pressure (pressure above insitu levels) will cause clays to consolidate. The younger marine clays would consolidate more and faster than the older bay clays which are directly under the proposed pressure bulb caused by the building pile group. The degree and unevenness of the consolidation of the clays under the Millennium Tower were underestimated from the start so the rate was higher than estimated and the settlements were different over the longest direction of the building. This is pretty basic stuff and predicted settlements are often not correct. Boreholes originally were pretty well spaced out so that didn't help. If I'm wrong then shoot me, looks as if the original engineers were no better. As the old clays consolidate the 10' slab starts to pick up some load and the marine clays consolidate.

RE: SF Tower settlement Part II

Yup... missed that... it's just the relaxation and the new 100' shafts were at about the same elevation as the original piles. I have to look back at the earlier postings, but I thought the upper soil was filled material which could increase the pile loads, too as well as increase pore pressures.

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

-Dik

RE: SF Tower settlement Part II

Like I said I'm no fancy geotechnical engineer but this is pretty basic stuff. The overlying soils were there to start with according to the soil report but the 10' concrete slab less any dirt excavated for it and the basment(s) would be surcharge which is estimated at 224000 kips for the entire structure divided by 100' x 200' size of pile group or 11.2 ksf.

RE: SF Tower settlement Part II

Same here... I wonder why vibrating wire pieziometers, or something of that ilk, weren't installed? I also wonder if they have a real handle on what they are doing?

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

-Dik

RE: SF Tower settlement Part II

Piezometers were to be installed but I'm almost willing to bet they were not installed yet because no loads had yet been transferred to the new piles.

RE: SF Tower settlement Part II

So their original plan might still work but they forgot that upsetting the status quo (pore pressure wise) might result in increased short term settlements; now they need to get a handle on things before they do any more damage. Seal those 36" casings if thy haven't and get their piezometers installed and working at the very least.

RE: SF Tower settlement Part II

I'm out of my depth in this conversation, but I've been following along. Reading the latest news (1" added settlement since the start of installation of reinforcing piles, now 22" of tilt at the top) is scary to a layman, and raises some questions.

Looking at the building structure and foundation as separate elements, with a connection between them (I know this is a vast oversimplification), that connection must have some high level of moment capacity to handle wind and seismic load. With the building now tilted 22", it seems that the side opposite the tilt is now subject to a steady-state moment, to which any wind load or seismic induced moment would be added. I would imagine the moment capacities, especially for seismic loads, are huge - but how far can the building tilt before the added moment applied to the theoretical foundation/structure connection from the tilt puts the building in a situation where the total moment (tilt + wind + seismic) exceeds design capacity? Is this building approaching the point where it will be deemed completely unsafe and unsalvageable?

RE: SF Tower settlement Part II

Quote (Looking at the building structure and foundation as separate elements,)


I don't think you can do that... but, I understand the peer review of the building, did that. I don't know what the 'point of no return' is, but there is one. Unlike the Florida condo, this will not 'collapse into a heap'. If the soil is that sensitive to pore pressure, I'd be really concerned about liquifaction during a seismic event... fortunately SF rarely experiences these... and the engineers have already investigated this outcome.

With the issues that have come up, my confidence in the protagonists is not at an alltime high.

A more interesting legal issue... do the condo owners face the costs for remedy? I know there was some kind of legal settlement but is there anything that includes proper repair... or can the owners be stuck with the cost for demolition?

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

-Dik

RE: SF Tower settlement Part II

SwinnyGG, good question that I don't have the answer for. But I suspect that the perception of the tilt by the tenants will be the governing factor, not the capacity. You're never going to convince the residents that place is safe and stable.
Also, as the building tilts, the offending piles will be more heavily loaded, exacerbating the issue. Now eventually the clays will settle all they're going to settle, but I don't think the tenants are going to be patient.

RE: SF Tower settlement Part II

Quote (SwinnyGG)

now 22" of tilt at th top

22" sounds like a lot but it is sort of diagonal to the building with most to the north and about half say to the west. So in the 200' depth direction N to S the building leans about 19" or 1.58' / = 0.79' at the midheight assuming the building stays straight with the C of G off by about 0.8 feet. This assumes that the building weight DL + LL is evenly distributed across the width and depth of the building which it probably is not. Different layouts on floors, uneven distribution of mechanical loads, elevator shafts, stairwells could easily throw the C of G off by more. Taking the entire building weight of 224000 kips at an eccentricity of 0.8 feet would result in a moment of 17920 k-ft. The section modulus of the building in the 200 ft direction is (100 x (200^2)) /6 = 666667 ft3. In the 100 ft direction it is (200 x (100^2)/6 = 333333 ft3

Compressive stress on the building footprint is = 224000 kips over 100 X 200 ft2 = 11.2 k/ft2

Compressive stress due to the eccentricity of the building = 17920 kip-ft/666667 ft3 = 0.0268 k/ft2

As you can see the effective stress on the building at the base due to the permanent moment is miniscule in the N-S direction compared to the Dead + Live load given for the entire building. In the E-W direction the moment component would actually be the same at 0.268 k/ft2.

So if I have not made any math errors this much eccentricity is really insignificant at this point in time for the entire building. Increasing rate of settlement could change the story but liquification of the marine clays in an earthquake could suddenly change everything.

RE: SF Tower settlement Part II

Quote (liquification of the marine clays in an earthquake could suddenly change everything.)


That was my concern early in the first thread... and this had been addressed. With the results of these experts, to date, I'm not as confident.

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

-Dik

RE: SF Tower settlement Part II

Quote (22" sounds like a lot)


4' sounds a lot less than 48", too... I wonder what the 'cut-off' point is?

With liquifaction, will it sink? Fortunately it can only go down about 200', so you might be able to exit the building at the 20th floor? lol

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

-Dik

RE: SF Tower settlement Part II

Settlement is not the only potential failure mechanism for piles in soils with a potential to liquefy.

The paper following presents "probable mechanisms of pile failure in liquefiable soils as bending, buckling, shear, settlement or dynamic amplification, and the piles may fail either due to any of the mechanisms or a combination of some or all of them".

Mechanism of failure of three pile-supported structures structure’s during three different earthquakes; Suresh R. Dash Indian Institute of Technolgy Bhubaneswar, India; Subhamoy Bhattacharya University of Bristol, United Kingdom

I wounder what a soils expert thinks about these things?

RE: SF Tower settlement Part II

Quote (Settlement is not the only potential failure mechanism for piles in soils with a potential to liquefy.)


No kidding?a

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

-Dik

RE: SF Tower settlement Part II

Good paper, thanks... I chose vertical translation because it was likely the least onorous to deal with... the existing piles would likely prevent it from going down the full 200'... Maybe you'd exit at the 10th floor?

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

-Dik

RE: SF Tower settlement Part II

For all wondering about the liquefaction potential of the soils at depth, the Colma Formation (bearing layer for the original piles) and underlying Old Bay Clay are not considered liquefiable. The liquefiable soils are at relatively shallow depths, comprised of the artificial fill materials near surface, and underlying young alluvium. The young Bay Mud soils are not classically "liquefiable" per se, either, but can be subject to significant loss of strength during shaking. The probability of liquefaction affecting the tower is quite minimal given all foundation loads are imparted to soils well below likely depth of liquefaction.

RE: SF Tower settlement Part II

Is epoxybot missing?

RE: SF Tower settlement Part II

Thanks...

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

-Dik

RE: SF Tower settlement Part II

"The “perimeter pile upgrade” project, paid for as part of a confidential settlement reached last year, is designed to reinforce the foundation of the 58-story, luxury Millennium Tower after it had been discovered in 2016 that the northwest corner of the structure had sunk 16 inches since its opening in 2009. Fast forward to 2018, an inspection revealed the building had descended an additional two inches."

I wonder what happens when the confidential settlement agreement doesn't work... maybe the additional settlement was included in the settlement. lol

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

-Dik

RE: SF Tower settlement Part II

Quote (apper.42)

22" sounds like a lot but it is sort of diagonal to the building with most to the north and about half say to the west.
- Actually the majority of tilt is to the west.

DeSimone's project foundation calculations submittal gives a load of 14.8 ksf for a 106' x 140' piled foundation. The plan view submitted by Lera/ENGEO for the previous solution, the symmetrical piling upgrade, was for the as-built, 103' x 153' piled foundation for 14.58 ksf.





Here is a comment from the 'expert' panel that reviewed the current Perimeter Pile Upgrade for SFDBI. Part of the commentary is in regards to work done by Lera/ENGEO.



Here are a couple of links to articles in Structure Magazine. One by Ron Hamburger of SG&H and another by the Slate geotech people.

I thought the ground profile the perimeter piles will pass through was interesting.

This paper on the Geology of San Francisco gives some interesting characterization to Old Bay Clay and Cloma Sand Hydraulic Coefficient.
...Hydraulic Conductivity:
The hydraulic conductivity of the Colma Formation is generally lower than would be expected based on the
typically fine to medium grain size of the strata. This probably results from the material in the interstitial
space between the sand grains that can contain silt or clay particles, in addition to calcium carbonate
cementation and iron oxide precipitation. Hydraulic conductivity values for the Colma Formation typically
range between 1x10-5 and 1x10-3 cm/s (Johnson, personal communication). While sandy zones at the higher
end of the hydraulic conductivity range are common, the overall character of the Colma Formation is that
it more often exhibits conductivity values toward the lower end of this range.

The hydraulic conductivity of Yerba Buena Mud/Old Bay Deposits strata will depend on the textural variations in the strata (i.e., sand or clay). While the overall depositional setting for the Yerba Buena Mud/Old Bay Deposits was a marine environment resulting in predominantly fine-grained deposits, significant yet discontinuous lenses of sandy material are quite common. As such, the sandy horizons generally exhibit hydraulic conductivity values between 6 x 10-4 and 2 x 10-3 cm/s (Johnson, personal communication). These values are relatively large; however the limited extent of these lenses cause the overall hydraulic conductivity of the deposit to be dominated mostly by the clayey strata where the hydraulic conductivity is typically lower, with values ranging between of 10-7 and 10-5 cm/s (Johnson, personal communication). END

The ground between the Out-rigger Super-Cloumns on Fremont St. seems to be quite complicated. Maybe they should of hired Michael D. Holloway from Insit-u-tech, the Geotech who performed PDA & CapWap on the tower Indicator piles to the 'Expert's' review of the Perimeter Pile Upgrade; since he's the only person who was involved in the 301 Mission Street project that thought the PDA & CapWap showed more ground investigation was warranted.

As for the replenishment of ground water to the general vicinity of Fremont & Mission streets, shoring walls for the Transit Center & Salesforce Tower block Rincon Hill from draining to north toward Mission St., and Mission St. from which is the bottom of an ancient ravine. The Transit Center & Salesforce Tower shoring/cut-off walls, two in each direction, penetrate 5 to 15 feet into the Old Bay Clay. Then, there is the -90' tower/podium shoring wall, without a vertical gradient above -25. The Transit Center & Salesforce tower are underground levies, blocking groundwater recharge.



A proper representation of the piles in profile along Fremont St. shows the shortest spec'd piles, don't reach a sand layer, based on Treadwell & Rollo's original bore logs.


The yellow points represent 2/3rds the pile length, exclusive of the mat.


RE: SF Tower settlement Part II

Is this what we're looking at? Looks really good for liquifaction...

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

-Dik

RE: SF Tower settlement Part II

The tower is between Mission & Howard but yeah, they are right over the middle of the ravine.

RE: SF Tower settlement Part II

A geotekkie may have a better handle on the foundations; I've only done a few seismic projects and none of them where liquifaction was an issue. Doesn't look good from here, and the red box sticks up 3x as high. It's time they got 'the big one',too. I don't know if the building is to scale horizontally... just a WAG.

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

-Dik

RE: SF Tower settlement Part II

Millennium Tower is 645' tall, 150' wide on Fremont Street, and 110' wide on Mission Street. Dimensions approximate.

The proportions of the above ground part of the red rectangle look right to me.

The red rectangle has the below grade part at about 415' deep. THAT seems a goodly ways off.



spsalso

RE: SF Tower settlement Part II

I thought the piles were only about 100' long, not 400', and that bedrock was about 200' down.

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

-Dik

RE: SF Tower settlement Part II

"I thought the piles were only about 100' long, not 400', and that bedrock was about 200' down."

Ah, I see where I made a mistake. The top of the red rectangle is NOT the top of the building, though it DOES seem reasonable to assume that. Over on the left, there's a height scale, with the top of the rectangle ending at about 200'. So the building got several hundred feet chopped off, so as to fit.

The piles do seem to be the correct length at about 100'.

And since the x and y axes are not equivalent, the assumption that the proportions would be equivalent is incorrect.

The red rectangle's width, however, is incorrect. In the drawing, it is about 500', as opposed to the more correct width of 150'.


spsalso

RE: SF Tower settlement Part II

...makes it even worse, then...

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

-Dik

RE: SF Tower settlement Part II

Here is the Karp-Kardon report from 2019 predicting what's happening to the tower now: http://www.lbkarp.com/mi/Millennium%20Report%207-1... He and Kaplan wrote this report for the City of San Francisco in 2019.

He was interviewed recently here:

https://www.nbcbayarea.com/investigations/local-en...

The most important item he is worried about is with all damaged soil as well as the damage to the R/C structure (see damage to the shear wall in this photo below from Karp's site) he thinks there is a very high risk of seismic collapse.


His firm's site here: http://www.lbkarp.com/mi.html has many important Geotech reports , photos, etc on the piling solution.

I am looking forward to seeing comments on how the building will perform during a future M7.3 quake from Hayward Fault to the east or M8.3 San Andreas Fault to the west.

RE: SF Tower settlement Part II

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

Do you know that this Berkeley Professor who is probably the most responsible person for this fiasco blames God for it. See the 2017 story here: https://www.nbcbayarea.com/news/local/professor-wh...



I guess if the tilting happened after Corona, the virus would be blamed...

RE: SF Tower settlement Part II

sad...

On the Karp-Kardon report extremely good post... BPS...

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

-Dik

RE: SF Tower settlement Part II

Quote (epoxybot)

Actually the majority of the tilt is to the West

Using this and assuming 20" or 1'-8" of the tilt is to the West then redoing my calculations for the increase in pressure on the pile group due to the tilt and using the actual as built dimensions of 103' in the east west direction, 153 in the NS and the total DL+LL = 229700 kips.
The moment in the EW direction is = (1.67 ft/ 2) x 229700 kips = 191800 K-ft. The section modulus in the EW direction is 153 x (103^2)/6 ft3 = 270530 ft^3.
Stress due to DL+LL = 229700/(103 x 153) = 14.58 ksf
Max. stress due to the EW tilt is then = 191800/270530 = 0.71 KSF

Calculations Revised to assume mass at C of G of entire building ie at 0.5 x 1.67' lean at centre of mass.

Permanent stress on the pile group footprint is therefore almost 5% of the total pressure. This extra stress is then a significant percentage of the average pressure on the pile group and will add to the tendency for settlement to the West, accelerating the rate of settlement.

Drilling of the 36' and 20" diameter casings for the proposed solution on the West side of the building resulted in the following :

1) Reducing the average overburden on the West side thereby decreasing the upward average force on the matt foundation due to overburden and actually increasing the general tendency to settle Westerly.

2) Lower the water table as saturated overburden is removed thus decreasing the buoyant force on the matt due to the water table resulting in a tilted water table under the matt.

3) Decreasing the total pressure in a line along the matt allowing increase pore water pressure in the shallow marine clay and the deep Bay clay to flow more easily thus increasing tendency to consolidate.

All of these effects led to a swift increase in settlements which caused a halt to Implementing the "chosen" remedy for the building.

At first I thought that the chosen remedy could still work if they moved quickly enough. After reading the Karp-Karden report of 2019 as posted by Student Forever I am convinced that the chosen remedy is completely flawed. This is reinforced by remembering from Dr. Davenport my 4th year structural dynamics professor (The "dynamics" consultant on the World Trade Center) that uneven foundation conditions and weak torsional resistance of the foundation and building can lead to major dynamic failures during severe earthquake or even wind events.

Stop what you are doing guys, do the right thing.

RE: SF Tower settlement Part II

That the California Professional Engineers Association has said nothing, speaks volumes... so much for their edict of looking after the people of the State... blowing smoke it would seem... and California has too much of that already.

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

-Dik

RE: SF Tower settlement Part II

I attended a seminar on wind and earthquake loading about 50 years back by Davenport and Dalgleish; same guy?

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

-Dik

RE: SF Tower settlement Part II

So maybe they gotta drill some holes on the OTHER side of the building, and start pumping water out on that side to bring the building back to level(er). Yeah, it'll sink more on that side, but maybe it won't fall over from tippin'. Then when they get all the proper piles in, they can jack the building back up a foot or two, to match the sidewalk. Or just leave it, and add some steps. And maybe some attractive planters--those worked so well in the Champlain.

Shouldn't the people who did the design work for this operation be living in the building, until it's fixed?



spsalso

RE: SF Tower settlement Part II

Quote (dik)

I attended a seminar on wind and earthquake loading...

Yes same guy, my fourth year (1966) structural dynamics prof. and dynamics consultant on the World Trade Center, brilliant guy who ran the boundary layer wind tunnel at University of Western Ontario (UWO) in London, Ontario, Canada. Also expert on eddy shedding, engineered mechanical damping and effect of building movements on occupants etc.

Link to more info : https://www.eng.uwo.ca/news/davenport.htm


RE: SF Tower settlement Part II

apper.42,
Thank you for posting Alan Davenport link. I did not know him in person, but, knew what he has done in wind engineering. It was great to read the material. He was truly the father of the modern wind engineering, especially wind tunnel testing of buildings.
Thanks

RE: SF Tower settlement Part II

Quote (Student Forever)

You are welcome. As you can tell from my graduating year I am no longer a student but believe that I'm probably a forever Engineer.

Western's latest wind tunnel is located off campus, is hexagonal, and allows study of tornados and hurricanes.

RE: SF Tower settlement Part II

Here is a great article:

"The man who saved the Leaning Tower of Pisa, By Andy Pearson 14 September 2000" with this link: https://www.building.co.uk/focus/the-man-who-saved...

The man is John Boscawen Burland CBE FRS FREng (born 4 March 1936), an Emeritus Professor and Senior Research Investigator at the Department of Civil and Environmental Engineering of Imperial College London.

Part of the story quotes him as :

"The problem Burland faced was to correct the lean without causing the tower’s collapse. The tower was so delicately balanced that the team charged with saving it dared not touch the ground on the south side, the direction in which it leans. “It was not an underpinning job,” says Burland. “Any interference with the ground on the south would have brought it crashing down – and I’d have had to take up selling ice-creams in the piazza,” he jokes."

dik,
your comment about California Professional Engineers Association starting with "That the California Professional Engineers Association has said nothing, speaks volumes... " is right on the spot and it is much worse than you think. The designers of the MT and peer reviewers and the designers of the retrofit should all be fired, their P.E. license taken away so, they can get a job as Professor Burland stated above, "selling ice-cream in the piazza ( i.e. Sales Force Plaza)in front of Millennium Tower!

I visited the Pisa tower in 1990's when they were doing the retrofit with a European colleague who was involved with the international team led by Prof. Burland. The solution was, as explained in the story, not to touch the soil under the building, especially on the south side that was settling more and causing the tilt. But in Millennium Tower, these naive Designers, and Peer Reviewers of the design, have done just that, disturbing the soil under the side that is tilting (the N & W side). In Pisa Tower, they had added weight on the north half of the foundation opposite of the side that is settling. I took pictures and if I find them I will post, but, for now, enjoy this historical evidence (not really!) below of how the engineers made the King happy by saving him some money! Maybe the designers of the N&W pile solution and their peer reviewers tried to make the Millenium Tower developer (Millennium Partners) happy, instead of trying to make the building safe for a major earthquake regardless of how much it will cost, or if it cost too much and not technically doable, pay the owners the value their condos had before the tilting was detected, evacuate the tower, demolish the tower (very slowly and carefully!) and rebuild it correctly or turn the lot to a nice park! This approach will satisfy the first Canon of the NSPE Code of Ethics for Professional Engineers which states: "Engineers, in the fulfillment of their professional duties, shall hold paramount the safety, health, and welfare of the public."


RE: SF Tower settlement Part II

I've seen one similar with the note, "...and we can save 100 lira if we don't get a soils report."

A funny thing about Pisa is that it was settling as it was constructed. The envelope has a curve in addition to the tilt; they made the supports on the 'sinking' side a little longer, so it would still be level. I don't know if this was a conscious effort or just a consequence of building the supporting walls 'plumb'.

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

-Dik

RE: SF Tower settlement Part II

Thanks...

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

-Dik

RE: SF Tower settlement Part II

Apparently, for the Pisa Tower also, a sudden tilting has occurred due to disturbing the soil on the leaning side by the Architect causing the suden leaning. Please see the highlighted part below (from the same Burland Paper https://www.building.co.uk/focus/the-man-who-saved....

RE: SF Tower settlement Part II

Apparently the "Mediated Settlement" wasn't so mediated after all. bigsmile

The photo of the repair work is actually from the parking garage and it may be the 5th/bottom floor of the garage, involving the north wall of the parking structure. You can just make out the paint for a parking stall.

RE: SF Tower settlement Part II

Quote (apper.42)

Western's latest wind tunnel is located off campus, is hexagonal, and allows study of tornados and hurricanes.

Lots of amazing facilities at UWO. The Three Little Pigs is my favorite though, if only for the name. Unfortunately, only ever had the opportunity to use the wind tunnel during my studies but that was quite neat!

CWB (W47.1) Div 1 Fabricator
Temporary Works Design
Toronto, Ontario

RE: SF Tower settlement Part II

Does anyone have a copy of this correspondence; it seems to have been pulled...

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

-Dik

RE: SF Tower settlement Part II

I haven't seen that document but from the project description, it is the 'Original' tower. The original tower had 4 basement levels across the entire site. Think partially compensated foundation. It was also described as sitting on a mat foundation & tower piles.
The original design did not present an excavation problem for the TJPA.
Millennium wasn't able to get PG&E to move their existing utility vault under the old 129 Fremont. If they tried to build the existing vault into the basement tower, the first two floors of the basement would add up to -25 feet of excavation. Instead, they cut 3 floors off the tower basement and added a 5th to the Podium/Mid-rise. They went as deep as they could for 1 basement level, then went with a cantilever slab over the old utility vault and built a new utility vault in the basement of the tower to replace the one they were building over. Building over an PG&E easement isn't allowed. So they replaced it with the one now in the tower basement. The new scheme was Webcor's idea.
Final EIR gives the same project description. It changed in 2005, just 10 days after the TJPA received final approval for the current alignment.
It is odd that, that Planning Dept. document didn't end up in the Final EIR.

RE: SF Tower settlement Part II

The four basements and the 10' thick slab may have 'pushed' the pile end tips into the old firm clay to help a little bit.

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

-Dik

RE: SF Tower settlement Part II

Quote (Enable)

Lots of amazing facilities at UWO...
Thank you for the post great pictures of the facilities, had never seen good pictures of the 3LP and the WindEEE Dome even though i've been to every reunion but one since '66. Facilities such as these for wind, wave tanks that can duplicate any kind of sea state, snow drifting test facilities, soils research facilities, technological advancements and others leave the weakest link as the clients and the engineers and architects trying to balance clients goals with financial constraints and too often forgetting their duty to the public.

RE: SF Tower settlement Part II

"...forgetting their duty to the public."

And to themselves.



spsalso

RE: SF Tower settlement Part II


I had missed this news report on how stoppage of pile operation actually was forced on the project while Ron Hamburger, the EOR of pile retrofit was downplaying the importance of the sudden settlement. Read the full report: https://www.nbcbayarea.com/investigations/millenni...

RE: SF Tower settlement Part II

Quote (Student Forever)

I had missed this news report...

Amazingly incompetent, in my opinion, do more of the same thing expecting a different result, until things are even more screwed up than when they started. Never screw with the soils on the side that the building is sinking the most; worst possible thing to do. They should have used the solution proposed by Karp-Karden in their report of 2019, much safer and apparently about the same cost as the Hamburger group fix.

RE: SF Tower settlement Part II

Why is it that the media..., NBC mostly, can get access to communications between the parties to the Perimeter Pile Upgrade but they can't ask tough questions about the number of perimeter piles being reduced from 52 to 42 and why have they advanced the production pile installation, if they haven't achieved a successful indicator pile?

RE: SF Tower settlement Part II

not being political, but it seems that reporters aren't interested in news or critical reasoning, anymore.

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

-Dik

RE: SF Tower settlement Part II

Quote (epoxybot)

Why is it that the media..., NBC mostly, can get access to communications between the parties to the Perimeter Pile Upgrade but they can't ask tough questions about the number of perimeter piles being reduced from 52 to 42 and why have they advanced the production pile installation, if they haven't achieved a successful indicator pile

I'm no fan of the current level of truth-seeking in today's journalists... but I think expecting them to very clearly understand the highly engineered pile system, at a level where they can criticize the design or implementation, is a huge ask. They aren't engineers, and reading drawings and understanding what needs to happen are not second nature to them.

RE: SF Tower settlement Part II

Journalists are being fed information from an insider. We don't know who this insider is or what their intentions are. The journalist is not knowledgeable enough to properly vet this information, they can only pass it along.

RE: SF Tower settlement Part II

I'm pretty sure you're correct, Tug...

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

-Dik

RE: SF Tower settlement Part II

Permit application 202107194668 filed on 7/19/2021
Revision to PA# 201812047402,to reduce the quantity of piles from 52 to 42,to reduce the vault extents accordingly,to relocate the piles 8" farther from the building face,to modify the locations of piles to avoid existing utilities,to increase the pile diameter in the rock socket form 20"to24".

Permit application 202107194670 filed on 7/19/2021
Revision to PA# 2018-1207-7828. To abandon Indicator Pile No. 1 and to add Indicator Pile No. 2, with a rock-socket diameter of 24 inches, located 8 feet to the north along Fremont Street.

Permit application 202107194671 filed on 7/19/2021
Revision to Permit Application No. 2018 12 07 7819, to revise the excavation and shoring extents due to the relocation and reduction in quantity of permanent piles, to avoid conflict with the indicator pile, to relocate the shoring struts, and to modify the corner waler connection detail.

RE: SF Tower settlement Part II

More Hearings..., Maybe.

NBC: SF Supervisor Calls for Hearing Over Troubled Millennium Tower Fix

“The sinking and tilting tower Millennium is back,” Peskin told his colleagues Tuesday afternoon, “and it is time to reopen investigatory hearings on that matter, particularly in light of continuing and ongoing revelations at the Department of Building Inspection.”

SFDBI is under investigation by the FBI..., again. This time for former SFDBI Director Tom Hui accepting 'gifts' for permitting. The investigation of SFDBI & Director Hui, sprung from an investigation of the Director of the SFPUC for a number of corruption scandals that has seen the SF City Administrator, Naomi Kelly, resign after her husband, who also works for the City was charged.

Just a recap: Back in September 2016, one month after news broke of the settling & tilt of the Millennium tower and after SF Supervisor Peskin had held the 1st of 11 hearings on the settling of the Millennium Tower, Peskin noted with skepticism, that all of the reports being prepared are being paid for by parties that have an interest in the high-stakes legal cases that are sure to ensue.

At the 2nd hearing on October 28, 2016: “It looks like it’s been extremely lawyer’ed,” Peskin said of SG&H’s 2016 report, “which I hope gives you all some amount of concern.”

This 2016 report had omitted SG&H's earlier concerns about the mat foundation & degree of potential damage to the Outrigger Super-columns during a seismic event, noted in the 2014 preliminary report.

Then in mid 2017 Supervisor Peskin signed the authorization to commit City funding for the "Supplemental Report for Foundation Settlement Investigation" prepared by SG&H. SG&H, author of the two previous reports, to which Peskin had made the dubious attributes, was hired by Millennium Partners legal representative, Paul Hastings, LLP.

The City commissioned report, according to Peer Review chair and Stanford Professor, Greg Deierlein, was the first report that was to include an examination of the piled foundation. The description of the piles and their reinforcement/fixity to the mat contained gross errors. Errors that are hard to afford the suggestion of being a mistake. No one picked up on the error and as SG&H had been working on the so-called 'cheaper' Perimeter Pile Upgrade scheme simultaneously to the report; settlement of the Class Action proceedings swiftly followed.

On October 21, 2020 following settlement of the Class-Action case, Supervisor Peskin had this to say about the court proceedings. “Not a penny of city general fund money went into the settlement,” Peskin said.
At least not directly.
“No money is coming from the city general fund, but a lot of money is coming from Uncle Sugar — the United States of America,” Peskin said.

The entire Perimeter Pile Upgrade scheme was reviewed by SFDBI's EDRT panel of 2 Structural & 2 Geotechnical engineers, Greg Deierlein, Chair, Marko Schotanus, Craig Shields & Shah Vahdani. SFDBI gave approval to the 'Voluntary Structural Upgrade' PRIOR to settling of the class-action lawsuit. One has to wonder who at Paul Hastings, LLP & Millennium Partners made the decisions about what SG&H was allowed to know & access while preparing the Perimeter Pile Upgrade scheme?

What's that expression about doing the same thing over & over again and expecting a different outcome?


RE: SF Tower settlement Part II

NBC: Millennium Tower Officials: Fix Work to Resume ‘Shortly' (video)

Millennium Tower Manager, James Zaratin assured residents they’re working with the fix engineers and the city’s engineering design review panel to refine drilling methods to minimize the ground disturbance.

But San Francisco Supervisor Aaron Peskin is skeptical. He said Wednesday he will summon experts to assess the plight of the building during the as-yet unscheduled hearing that he called for Tuesday.

“There’s a lot under this rock and I’m about to shine some light on it,” Peskin said, adding that he no longer trusts the current engineering review panel. It was that panel that vouched for the fix back in 2019 and has continued to support the fix team’s efforts.

RE: SF Tower settlement Part II

Peskin is such a terrible person to get behind. However, he knows lawyers and I think he sees this as a chance to promote his image. He knows the lawyers are wrong and the truth will surface. (I don't like using speculation in the professional forum so please accept that I am labelling this comment as pure speculation).

RE: SF Tower settlement Part II

Concur... and without speculating, I don't think that Peskin will come out of this 'lilly white'. The Karp-Kardon report of a couple of years back makes a lot of sense, and the City was well aware of it, it would appear. I think they have just bought a very expensive fix, by ignoring it... without speculating. To reiterate, that the professional association is silent, speaks volumes.

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

-Dik

RE: SF Tower settlement Part II

Link to the 9-9-2021 interview with the former President of the Structural Engineers Association of Northern California (SEAONC), Emily Guglielmo.
https://sanfrancisco.cbslocal.com/video/5981786-wo...
The current President of SEAONC, Kevin Moore, is a senior principal at Simpson Gumpertz & Heger

RE: SF Tower settlement Part II

So the Millennium Tower building managers and presumably the residents have been SOLD on the fix by Hamburger and company while things just continue to go downhill. At least three apparent "experts" in the field never have agreed with the approved fix and the City previously ignored them (shame on them??) so will they listen now?? Is this just a ploy to get the City off the hook for ignoring the previous warnings. I have no idea but what they are doing so far has made things worse. We all know what crazy is!! Give credit to Hamburger for being a great salesman, but is he a good engineer, I have no idea but in my humble opinion the stakees are too high to not check it out.

RE: SF Tower settlement Part II

The other proposal, by Karp-Kardon, also had some unknowns/complications. It relied on jacking in piles within the perimeter, using the building mass to jack against. Buildings don't much like massive loading applied upwards, so it was unexplained how that would be accomplished.

RE: SF Tower settlement Part II

I'm pretty sure that would be considered and with a 10' thick mat foundation, there is likely some latitude. I was curious about the manner of jacking and the equipment used. No matter how you cut it, it's still a bit of a mess, and still not fixed.

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

-Dik

RE: SF Tower settlement Part II

Loved the interview with Ms. Guglielmo.

"...no cause for alarm..."



spsalso

RE: SF Tower settlement Part II

2

Quote (hokie66)

The other proposal, by Karp-Kardon, also had some unknowns/complications.

Here is a complication regardless of remedial scheme.



It is a very big assumption that the shoring wall would settle along with the tower. Then, there is the entirely new seismic response that goes without discussion.

When the news broke that the retrofit was being paused, the new amount of settlement was given as 2 inches & 5 inches of tilt. Since then, the media has been saying, 1 inch of settlement. SF Supervisor Peskin is still saying 2 inches.

I wonder if the perimeter piling has reached the Colma Sand Hump yet?



Here is a link to the retrofit monitoring plan by Slate. Courtesy of LB Karp's Millennium Debacle webpage.

One of the members of the expert panel, Shah Vahdani, Ph.D. was on the 80 Natoma Peer Review, chaired by Prof. Jack Moehle. He was asked to write a letter for the 80 Natoma Peer Review panel, stating his opinion of the foundation for 80 Natoma, which was being called into question for the exact same concerns as 301 Mission.
He wrote a half-in/half-out answer. You can read some of his opinion in this SF Building Inspection Commission Meeting, (Item 6. Paragraph 16). He wrote his response while Myers Construction & Treadwell & Rollo designed the foundation relying on only one boring for the entire site.

While 80 Natoma was under Peer Review, the original 301 Mission St. tower, with 4 basement levels, had already been through Peer Review. SFDBI Plan check in March 2003 was working on MEP plan review when MSD/Millennium put their building on hold. I believe they had received a big NO on moving the utility vault.

MSD/Millennium probably had a stroke when 80 Natoma had their building permit suspended. They rushed out and hired Prof. Jack Moehle, 80 Natoma Chair, right in the midst of the 80 Natoma court battle; in order to "Prescription' their New tower project to the SF 2001 building code. Make no mistake, SFDBI was their to help.

But before MSD/Millennium hired Prof. Jack Moehle, Millennium was stuck. The PG&E vault was going no where. If they stayed with the 4 level basement project, so the PG&E vault could fit into level B2; levels B1 & B2, combined, would have been -25 ft in excavation depth. Along came Webcor with a solution!

Webcor no longer includes Millennium Tower as a featured project but I have the text of the page, as follows

Webcor: Webcor brought significant value to the project by eliminating the subterranean parking area under the high-rise tower and then sequencing the excavation into two phases. This enabled the high-rise tower erection—the longest item in the schedule—to begin earlier, saving the owner 8 months on the schedule and $6 million in construction costs.
The building’s size and location required a massive foundation system with 10-foot-thick pile caps and a 3-foot-thick core wall. The site also required a highly unique, internal cross bracing system to eliminate off-site movements and support an existing building on the south side. [End]

Fun Fact: Production pile driving started in early March of 2006 for the 301 tower. That year, San Francisco broke its March rainfall record, totaling over 9 inches for the month.

Here is a hydrological study of San Francisco and an excerpt I thought was worthwhile.
Geohydrology, Water Quality, and Estimation of Ground-Water Recharge in San Francisco, California 1987-92

Excerpt:
Modeling from SF Municipal water table recharging results indicate that areal recharge rates for water years 1987-88 for the seven ground-water basins range from 0.32 to 0.78 foot per year.
• Modeling from SF Municipal water table recharging results indicate that areal recharge rates for water years 1987-88 for the seven ground-water basins range from 0.32 to 0.78 foot per year.
• A comparison of the highest horizontal hydraulic conductivity (31 ft/d) with the highest vertical hydraulic conductivity (5.1 ft/d), which can be assumed to occur in the same materials, indicates that the minimum horizontal-to-vertical anisotropy may be about 6:1. The range of horizontal (5 to 31 ft/d) and vertical (0.0018 to 5.1 ft/d) hydraulic conductivities indicates that the coarse-grained deposits that control horizontal flow are relatively continuous, and that fine-grained deposits that control vertical flow are relatively discontinuous. Storage coefficients (table 1) indicate unconfined conditions at depths less than 100 ft (0.01 to 0.32) and confined or semi-confined conditions (0.00024 to 0.0082) at depths greater than 100 ft.
• A linear relation between rainfall and runoff from pervious areas was established such that a threshold rainfall amount had to be surpassed for runoff to occur. The threshold value was assigned based on soil type, ranging from 3 in/mo for clayey soils to 9 in/mo for sandy soils, with a slope of 0.9. [End]

It would have been nice for everyone if a decision had been made to work with only one Elevation reference. It is impossible to keep track of groundwater elevations when they keep switching between bgs, NAVD88 & SF Datum.




RE: SF Tower settlement Part II

In that interview that was posted earlier, and in it the former SEAONC president Guglielmo says about Millennium's misery that "there is no cause for alarm" , if you go to the video-time of 3:50, Supervisor Peskin says (for the first time?) that all options are on the table and the building might be dismantled (i.e. demolished). The URL is again below. I hope, when and if ( it is getting likelier every day) it comes to demolition, before the demolition starts they have Gugliemo stand there and continuously just say, "but it is safe, no cause for alarm" until all reporters have left. At the same time have Hamburger and Co, and Deierlein (the head of Peer Review panel approving the "Settlement-accelerating Retrofit" do something standing there next to Gugliemo. Any suggestions for anyone on what Hamburger and Deierlein should say at the site the day demolition starts?

https://sanfrancisco.cbslocal.com/video/5981786-wo...

RE: SF Tower settlement Part II

dik,
Speaking of reporters, Jaxon van Derbeken is quite good at investigative reporting on engineering problems. If I remember it correctly, he discovered the anchor bolt fractures in the new Bay Bridge, a few months before it opened. He also discovered and reported on the fracture of welds at the base of the main tower. He also was the one that in 2016 reported the sinking and tilting of MT for the first time. You are right he might have had some insiders to give him the scoop and then he did his job by checking the info with engineers who are very knowledgeable and choose to talk to him.
Our profession owes him a great debt of gratitude.

RE: SF Tower settlement Part II

Thanks... no cause for alarm...pipe

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

-Dik

RE: SF Tower settlement Part II


Promise, this is the last "no cause for alarm" until Hamburger, Deierlein, Moehle, SEAONC ex-president Guglielmo ,or ...say it again ... I just couldn't resist....


RE: SF Tower settlement Part II



It is interesting to go back and watch this CNN (https://www.cnn.com/2021/07/05/us/san-francisco-mi...) in June which had a title of " Surfside catastrophe raises concerns about San Francisco's sinking Millennium Tower".

In the video, Ron Hamburger says: "Millennium Tower was designed to stringent earthquake resistance standards and is a much tougher form of construction than typical buildings in Florida, which are not required to be designed for earthquake resistance," he added. "I can state with confidence that settlements experienced by Millennium Tower have not compromised its stability and safety." piece where Ron Hamburger says: "I can state with confidence that settlements experienced by Millennium Tower have not compromised its stability and safety."

Let us go back about a hundred years and see what the shipping company owning the "unsinkable" Titanic said: .. the New York office of the White Star Line was informed that Titanic was in trouble, White Star Line Vice President P.A.S. Franklin announced ” We place absolute confidence in the Titanic. We believe the boat is unsinkable.” By the time Franklin spoke those words Titanic was at the bottom of the ocean.

Meanwhile, the band on the Titanic kept playing, even as the ship sank. From Wikipedia:
"After the Titanic hit an iceberg and began to sink, Hartley and his fellow band members started playing music to help keep the passengers calm as the crew loaded the lifeboats. Many of the survivors said that Hartley and the band continued to play until the very end. Reportedly, their final tune was the hymn " Nearer, My God, to Thee ".

I think Ron Hamburger, Greg Deierlein, and SEAONC's past president Guglielmo, and other members of the band will continue playing the safety music while the unsinkable tower sinks. I hope their last hymn will not be " Nearer, My God, to Thee " while any occupant still is inside and has not gotten out.

dik:
I took the liberty of changing the thoughtful line you put at the bottom of your posts: "Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?" to this: " Rather than think foundation settlement and sinking and tilting as engineering, think of it as the wrath of God. Feel any better?" But, I did not feel any better. Why in the world, God would do this to the Tower, unless he really liked to get millions of dollars to lawyers on "settlement" settlement litigation, and engineers who would come up spending millions on a retrofit solution that would not work causing even more millions given to the lawyers and those engineers and help to protect their jobs until he ( The God Almighty) hears Hamburger, Deierlein, and SEAONC's past president Guglielmo, sing his (God's) favorite hymn " Nearer, My God, to Thee "..

RE: SF Tower settlement Part II

Quote (dik)

Thanks... no cause for alarm

Karp-Karden predicted in 2019 that exactly what has happened to MT would occur if the external pile solution was used. Also, as I pointed out in an earlier post, the external support on only two sides of the building could lead to unpredictable results in an earthquake due to torsional effects. I believe that Karp-Karden's internal solution would not have resulted in any added settlement and could have reduced differential settlements; unfortunately now it could be too late. As far as I know no new statements have come from them. Could MT work out to be one of the biggest engineering disasters ever without loss of life. Failures that have resulted in loss of life such as Champlain Towers of course much worse, Millennium Towers would only lead in monetary loss.

The building has not failed yet but all of the engineers involved from the very beginning have failed in their responsibility to everyone involved. What the hell is happening these days, just disgusting.

RE: SF Tower settlement Part II

Has anyone considered freezing the foundation soil with liquid nitrogen? Maybe ridiculous but I'll put the for case:

1. cost: Nitrogen is < $1.00 a gallon delivered in bulk so a few million bucks buys a lot of it. Drilling a network of small pipes into the clay around the piles would be easier than the current scheme. Soil is a reasonable insulator. A reticulation/ recompression system in the basement would keep it running economically* once the required freezing was attained. *For current throw-money-at-problem-in-desperation values of economical anyway!

2. Frost heave/ice lensing: yes frozen soil characteristically behaves badly but there is a vast literature in theory and practice: its habits are known and can be modelled. Annual variation in freeze and thaw could be managed out. Soil moisture input could be managed by strategic dewatering if desirable. The geothermal heat flow is low, measurable and stable, and the cooling rate is controllable by location and by depth with an intricate enough cooling network.

3. Even if ultimately unreliable frozen soil is stronger than unfrozen and ice moves slower than water. Freeze it now (enough to form a supportive framework around the nitrogen pipes anyway) then drill in proper rock-founded piles at your leisure.

(C) AusG 2021, invoice in the mail.

RE: SF Tower settlement Part II

It's a cheaply built building intended to maximize profit during initial leasing. How much is it worth to save? Not soil freezing valuable.

RE: SF Tower settlement Part II

Quote ("the former SEAONC president Guglielmo says about Millennium's misery that "there is no cause for alarm"")


I really like the line... I think she did the profession a great disservice with that statement... and one that will go down in the annals of engineering if this does not workout well. The position of SEAONC adds credence to what has occurred so far, and is a good example of 'bad engineering'. Time for them to be replaced.

I have no idea of how this will work out, liability wise, if a fix is not part of the solution. I think that Peskin is trying to minimise this, but I think he's in too deep.

I'm curious to know how to drill down (even for freezing pipes), based on the first fix attempt. There's a matter of regelation with ice. Does anyone recall the early childhood experiment of using a weighted wire to cut through an icecube that's in the freezer. I'm not sure how a large frozen mass in a 'bowl of jello' would fly in a seismic event.

The fix will be an interesting engineering achievement. Legislation has to be put in place to protect condo owners.

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

-Dik

RE: SF Tower settlement Part II

Quote (But, I did not feel any better. Why in the world, God would do this to the Tower)


He didn't... Kronecker comes to mind, "Natural numbers were created by God, everything else is the work of men."

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

-Dik

RE: SF Tower settlement Part II

The condo owners have insurance. The only legislation that will come of this is insurance companies trying to push the cost on to taxpayers.

RE: SF Tower settlement Part II

insurance to protect those from building collapses due to? I suspect there will be a lot of 'denied claims' resulting from this and the Florida one. These problems caused by the negligence of the professionals or the city.

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

-Dik

RE: SF Tower settlement Part II

Buildings can be condemned before they collapse.

RE: SF Tower settlement Part II

Worked really well in Florida...

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

-Dik

RE: SF Tower settlement Part II

Two questions:

1. If it comes to demolishing the MT, how can they do it safely? Explosives cannot be used right?

2. Does anyone know what type of seismic analysis Hamburger and Co. did on MT that was reviewed by Dierlein? Is there anything available on it publicly? If they did the seismic analysis, did the model include the presence of damage to the vertical bearing/shear walls (as the photos posted on this thread show) as well as cracks and damage in the outrigger beams and in the foundations?

RE: SF Tower settlement Part II

Quote (Student Forever)

If it comes to demolishing the MT, how can they do it safely? Explosives cannot be used right?

Probably with top-down disposal as described in this YT vid (start at 2:08). But to do that safely, they have to start while it is still safe for the disposal teams to work inside the building.

https://youtu.be/b-H7E-KQgHQ?t=128

Edit Add: Or like this:

https://www.youtube.com/watch?v=97QqO2Mdi88

RE: SF Tower settlement Part II

Quote (The position of SEAONC adds credence to what has occurred so far, and is a good example of 'bad engineering'.)


That SEAONC has not commented on her statement is tacit approval... which is even worse.

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

-Dik

RE: SF Tower settlement Part II

Some may view it as "extremely reckless and inappropriate" to have built a building that is falling over, and not being able to fix it.



spsalso

RE: SF Tower settlement Part II

...and perhaps a little unprofessional?ponder

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

-Dik

RE: SF Tower settlement Part II

The "Hamburger solution" results in asymmetrical support to bedrock on two sides of the building which means that lateral shaking in any direction due to earthquake is going to lead to the c of g of the building moving eccentrically to the hard support from the piles to bedrock. The resulting torque on the building would probably be well above any design torque because of the sudden change in foundation conditions. The natural frequency of the building due to torsion will probably be totally different than due to lateral loadings and any damping built into the building probably is not designed for high twisting of the building. From almost any source, uneven foundation support is a no-no in high earthquake zones due to unpredictable torsional effects. The diagram in the link is my attempt to show the uneven support and tendency to cause excess torsion in the structure. This could cause irreparable damage to the building if not specifically checked for this. Not sure my link is working correctly.

RE: SF Tower settlement Part II

Here is from SEAONC website:

"[SEAONC] Mission: To advance the practice of structural engineering, to build community among our members, and to educate the public regarding the structural engineering profession.

Vision: A world in which structural engineers are valued by the public for their contributions to building a safer and stronger community."

It looks like for the Millennium Tower, SEAONC has failed in every aspect of the "Mission" statement, and for the "vision", by not making any statement on Millennium Tower's sickness, The current SEAONC President Moore has gone blind and does not see, and the past SEONC President Guglielmo, has gotten blurred vision. Know a good eye doctor to recommend to them? If you know, send the name to SEAONC Directors too.

By the way, it is not just SEAONC in northern California, that has failed so far in its Mission and lost its Vision at least in this case. Has anyone heard anything factual from the other three local structural engineers associations in Califonia (SEAOSC, SEAOCC, SEAOSD)? SEAOC (the umbrella organization) has also settled (no pun intended) in deadly silence on MT settlement.

In its SEAOC Strategic Framework posted here: Phttps://cdn.ymaws.com/www.seaoc.org/resource/resmg... , it has the following under [SEAOC] Values:

"Values:
• Practice:
o Technical development and advancement of knowledge
o Structural engineering excellence
o Professional ethics and integrity
o Sustainability and resilience

None of the above is practiced in Millennium tower by those who caused this failure, all are SEAOC members, some even leaders, and senior members. They are saying to junior members: "Do as I say, not as I do". The quote first appeared in print in 1654: “Preachers say, do as I say, not as I do” (John Selden, Table-Talk: Preaching ). Parents have been saying it to children ever since.(from: https://idioms.thefreedictionary.com/do+as+I+say%2...)

RE: SF Tower settlement Part II

Quote (Student Forever)

Warnings About San Francisco Millennium Tower Repair Plans Raised Before Work Began

Guglielmo quote from the sound bite:

Quote (Emily Guglielmo)

“… the engineering techniques are very consistent. We do these on houses in San Francisco all the time. Underpinning, moving loads and foundations is very traditional.”

Okay, so this is simply a very tall house. Nothing to see here. All good smile

RE: SF Tower settlement Part II

Ya... really tall...

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

-Dik

RE: SF Tower settlement Part II

Quote (dik)

Ya... really tall

Yes the building is tall 605 ft without the mast but it has a minimum base width of 105 ft so the slenderness ratio is about 5.8 which is well below the 7 that we were taught was about the practical limit (for straight sided buildings). I believe that 605 was the planned height before the 16" settlement. The original World Trade Centre building without the mast was 1368 feet and the base was somewhat more that 200' on each side giving a slenderness ratio of 6.8, close to the maximum that I was taught many moons ago. These newer tapered buildings can obviously overcome this old ratio of 7.

So yes it is tall and fairly slender but Not overly slender. It is however heavy, heavier than any other building in SF with a non bedrock foundation (they are predominately steel). Other buildings with similar foundations exert less than about 3 kip/ft2 on the foundation but Millennium Tower exerts 14.2 k/Ft2 plus approx. 0.7 K/ft2 from the overturning moment due to the lean resulting in almost 15 k/ft2. The pressure from Millennium tower is much higher than the consolidation pressure that was applied the the old bay clay so of course it will consolidate further.

RE: SF Tower settlement Part II

Where is the Mayor of San Francisco London Breed in all of this? Now we know:

"San Francisco Mayor London Breed seen partying at a nightclub without a mask, report says" Los Angeles Times here:https://news.yahoo.com/san-francisco-mayor-london-...

Why Supervisor Peskin is trying so hard, while Mayor is not settling down from her maskless dance and partying?

She, the elected official charged with the safety of San Franciscans, including those living in the tilting Millennium Tower, also thinks "there is no cause for alarm".

RE: SF Tower settlement Part II

SF... you just couldn't contain yourself, I guess...

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

-Dik

RE: SF Tower settlement Part II

“The Engineering Design Review Team (EDRT) did receive and review the letters from Karp & Kardon and Dr. Pyke as part of the EDRT’s review of the permit request for the foundation retrofit designed by SGH (Simpson, Gumpertz and Heger). At that time, the EDRT asked SGH to respond to the points raised by the letters about SGH’s retrofit design and the EDRT was satisfied with SGH’s responses to those points.”


Since it's not a matter of national security (Or IS it???), it would sure be swell to see SGH's "response to the points" (mentioned above) and how EDRT expressed their satisfaction.

"Sure. Great charts, nice colors! Let's DO this thing."

Might want to ask if they're STILL satisfied, and if not, what caused their change of mind.



spsalso

PS: My mom would have recommended writing thank-you notes to K&K and Pyke.

RE: SF Tower settlement Part II

Here is a link to all the bore logs taken so far. They begin on page 52 of the PDF. Treadwell & Rollo's B-4 & Cotton Shires SD-2 are the closest to the current boring operation. SD-2 looks interesting at the junction of the Colma/Marine sands to the Old Bay Clay.
Courtesy of LB Karl's 'Millennium Debacle' webpage.

RE: SF Tower settlement Part II

In response to spsalso, here are the Hamburger (non-)responses to Pyke's 2019 comments (I am a newbie and not sure how to attach it so I have included it - why it was copied to Naomi Kelley, I have no idea - Pyke says that not only did they not contact him but that he had not seen this until a couple of weeks ago):


25 July 2019

Dr. Gregory Deierlein
318 Parkside Drive
Palo Alto, CA 94306

Project 147041.10 – Millennium Tower, Perimeter Pile Upgrade
Comments from Dr. Robert Pyke

Dear Dr. Deierlein:

This letter responds to comments raised by Dr. Robert Pyke in an e-mail, and attached memo, forwarded by the City Attorney’s office to Mr. Peter Meier on 23 July. I prepared these responses in consultation with Mr. John Egan, who serves as my principal geotechnical consultant for our work on this project.

The e-mail raises three primary points associated with Mr. Egan’s characterization of the site and
recommendation of MCER ground motion spectra. Specifically, these are:

1. Characterization of the site as Site Class D rather than E.

This point was extensively reviewed by the EDRT and is addressed in the comment log under comment 34.

2. Use of 80% of the default spectrum specified by the building code, rather than relying on site specific study, noting that ASCE 7-16, which will be adopted by the City of San Francisco in January 2020 will require site specific study.

In the course of their geotechnical study, Mr. Egan and his support team did indeed perform site-specific response analysis to develop a response spectrum appropriate to the foundation level of the Tower. ASCE 7 requires that when site-specific response analysis is performed, the resulting spectrum cannot be taken as less than the 80% of the default spectrum. Mr. Egan’s site-specific response analysis resulted in a spectrum with spectral ordinates generally less than 80% of the default spectrum, but with longer- period (i.e., 2 sec ≤ T ≤ 4 sec) energy content exceeding 80% of the default spectrum; thus, the greater of the 80% limit or the site-specific response study was adopted as the recommended spectrum, as required by the building code. This was reviewed by the EDRT and is logged as comment 3 in the log.

3. Dr. Pyke’s personal belief that characterization of ground shaking at the site using the Vs-30 parameter will underestimate the likely energy content of shaking in the period range 1 to 1.5 seconds. Dr. Pyke notes that Engeo’s proposed design spectrum did have increased energy content in this period.

We note that the building’s fundamental period of response is approximately 5 seconds
and more than 60% of the building’s mass is mobilized in modes that have periods in




excess of 3 seconds. Only 20% of the building’s mass participates in the period range between 1 and 1.5 seconds. Regardless, in the course of our design, we evaluated the building for Engeo’s ground motions as well as those recommended by Mr. Egan. The building performed adequately for both sets of ground motions.

Dr. Pyke’s memorandum dated 17 July raises the following technical points:

1. An allegation that our team purports that a disproportionate fraction of the building’s weight is carried by the perimeter columns, and this fails to take into account the sequence of construction.

We are not sure what Dr. Pyke is referring to. We have never made statements suggesting that a disproportionate amount of the building’s weight is carried by the columns. We independently computed the amount of building weight carried by the individual columns and the central core and compared these with similar computations made by DeSimone Consulting Engineers in their original structural design. Our calculations suggest that roughly 45% of the building’s weight is carried by the central core and 55% by the perimeter columns. This is consistent with distributions of load we have observed in other tall buildings.

2. The suggestion that transfer of 20 percent of the load form the existing piles to the new piles would result in immediate rebound of about 1 inch.

Geotechnical analysis conducted by Mr. Egan and his team confirm that approximately an inch of rebound will occur when the load is removed from the building. We concur that this will not occur immediately, but rather may take approximately 1 to 2 years to occur, consistent with the time-dependent rebound behavior of clay soil when overburden confining stress is reduced. The expression of immediate recovery of settlement alluded to was made in the context of the 40-year period over which our team has evaluated the building’s future settlement behavior.

3. Arresting the settlement of the north and west sides of the building while the center and the south-east corner of the building continue to settle can only increase the stresses in the mat that underlies the building and the outriggers when the mat is already dished and cracked, and the condition of the outriggers is uncertain.

In the course of our design, we conducted extensive analyses of the post-retrofit settlement of the building, and the effect of this settlement on the mat foundation and structure. These analyses suggest that post-upgrade settlement will counter the settlement that occurred to-date and in the process of doing so, tend to relieve, rather than increase, stresses which have accumulated to-date. We have demonstrated through our extensive analyses, reviewed by the EDRT, that the mat is capable of resisting stresses associated with the addition of the new piles, as well as the building’s response to MCER shaking, as specified by the building code.


4. The proposed fix cleverly provides for backing off the underpinning of the north and west sides of the building, should settlement of the south-east corner catch up with and overtake the settlement of the north west corner.

While it is true that the design would accommodate reduction in the amount of jacking applied along the north and west sides, this was never the intent of the pile head detail. Rather, the intent of this detail was to allow jacking of additional force onto the piles if rebound resulted in reduction of the effective jacking force. We note, however, that since the settlement experienced to-date is due to consolidation of the underlying soils, as the building settles, the consolidating soils will ultimately become normally consolidated and the rate of settlement will naturally diminish significantly with time. In fact, this behavior is evident in review of settlement data collected over the past 18 months.

5. The proposed fix creates an asymmetrical foundation which is bad enough under static loads but will create unpredictable and likely adverse response under seismic loads.

The perimeter pile upgrade adds vertical and lateral stiffness and strength to the foundation along the north and west sides of the building foundation. We have extensively and rigorously studied both effects in our analyses of the design. The upgraded building does not qualify as an “irregular” building under the definition of the building code. Further, the building’s response to earthquake motion is superior with the perimeter pile upgrade in place, compared with that of the un-retrofitted building.

6. The proposed fix requires complex and difficult construction on City property which houses many existing utilities and ties backs and will require new dewatering.

The required construction is neither complex nor unusual. It requires installation of drilled piles around the perimeter of the building. Piles of this type are routinely employed in building construction. The tie-backs, which will be cut, were installed to permit the original excavation for the building’s construction. They serve no purpose at this time and were intended to be sacrificial when installed. No dewatering will be required to enable the construction. Ground water will be controlled by soil grouting as has been successfully done in the construction of other nearby projects.

Sincerely yours,

Ronald O. Hamburger, SE Senior Principal
CA License No. 2951
I:\SF\Projects\2014\147041.10-301S\WP\027ROHamburger-L-147041.10.jdi_Response to Comments.docx

cc: Shah Vahdani Craig Shields Marko Schotanus Tom Hui – SF DBI
Naomi Kelley – City Attorney

RE: SF Tower settlement Part II

Walnuts,

Thank you.


spsalso

RE: SF Tower settlement Part II

The EDRT Comment Log and all comments there to, no longer matter, since the foundation has changed from 52 Piles to 42 piles. Dr. Pykes first comment seem to increase in validity.

The shenanigans at SFDBI clearly continue. SFDBI pumped out the revised building permits, just before news broke of the tower settling another..., 1 or was it 2 inches. Who knows?

Slate is a new company. They were formed from a few recent graduates, led by Debra Murphy; they all jumped ship from Sage. Sage Engineers was later purchased by Gannett-Fleming. Perhaps the decision makers at Sage decided, once the 2017 Seismic Safety Report. commissioned by the City of SF, was done that the liability of where SG&H were headed; wasn't a selling point. I chuckled when I looked up John Egan's LinkedIn page. He was given senior status as Sage, until they parted ways. Now he is an independent consultant but he lists himself as Senior Principal. I guess his shadow is a Junior Principal. 301 Mission is their meal ticket.

RE: SF Tower settlement Part II

"The required construction is neither complex nor unusual." Ronald O. Hamburger

So, then, the job was a piece of cake; and if it failed, the designer was a total incompetent and shouldn't be trusted to tie his/her own shoes. Or so it seems implied.




spsalso

RE: SF Tower settlement Part II

dik and all,
I took the last cartoon on the "there is no cause for alarm", this is so sad, that even though I tried to have a little humor to move away from the gravity of the situation, it is impossible not to think and worry about the occupants of this and surrounding buildings, and what can happen when the Hayward or San Andreas fault ruptures in Northern California? I hope Peskin will be able to remove the clueless Hamburger+Deierlein pack and bring in knowledgeable experts such as Karp-Karden and Pikes.

RE: SF Tower settlement Part II

SF: No need to explain...

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

-Dik

RE: SF Tower settlement Part II

Quote (Walnuts)

In response to spsalso, here are the Hamburger (non-)responses to Pyke's 2019 comments

Reply to question number 5. is complete bull; the building is probably symmetrical as far as earthquake but the c of g of the building is eccentric to the stiffer resisting piles on the perimeter causing huge torsion in the building in a quake. If we had the exact layout of the external piles we could easily calculate the total torque of the building around the group. We know approximate weight of the building, that it is symmetrical as per Hamburgers own words and we know the approximate g force in an earthquake from hamburgers own spectrum/frequency data so how hard is this to calculate.

To approximate the c of g of the external piles I took a line of piles 150' long on the 153 ft side and a line 100' long on the 103' side with these being about 5' from the edge of the 10' thick pad (cannot find this dimension on the conceptual drawing. This makes the c of g of the pile group about 45' South of the North edge of the pad and about 20' East of the West edge of the pad. Plotting this on a scale dwg. results in the distance between the c of g's varying from a maximum of 43' with the load direction at the maximum distance, 30' with the lateral load in the weak direction 90 deg to the long axis, 31' with the load in the strong direction at 90 deg to the short axis and as little as 0' if the load is along the line btwn the c of g of the building and the c of g of the external pile group.

Torque at the base will potentially be huge and I'm not sure if they calculated the natural frequency of the building in torque which could make things worse.









RE: SF Tower settlement Part II

The revised pile layout is in page 4. Here

RE: SF Tower settlement Part II

Thanks to epoxybot who beat me to it. It seems that the reduction in the number of piles might be due more to the presence of existing utilities rather than the performance of the indicator piles? Does anyone know where one can find information on what actually happened with the indicator piles?

RE: SF Tower settlement Part II

I would think that any repair would have to honour the existing stiffness of the building... to minimise any torsional component.

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

-Dik

RE: SF Tower settlement Part II

Going back to Hamburger's responses to Pyke, which I posted above. Here is a specific example of obfuscation. First we need to see the prior response in Comment No. 34, which is referenced in Hamburger's first No.1 but was not included.



That text from the Comment Log refers to two figures that were included in Supplement No. 34, one of which is a shear wave velocity profile obtained in a nearby boring for the new bus station:

But in 2018 in the Egan / Slate geotechnical report it is indicated that the shear wave velocity profile that they used for analysis of the site response was as shown below - note the softer top which makes it Site Class E - the input motions for the structural analyses were defined at the base of the perimeter mat but the building code says that site classes are "based on the upper 100 feet (30 m) of the site profile" - the building code generally does a poor job of coping with embedment but that's another story:


And the ERDT signed off on this reply ????

There is a reference in the comment log to an updated geotechnical report in 2019 but I have not seen this and I don't think the shear wave velocity would have been changed. Why? Because another dirty little secret is that the Slate site response analyses were so bad that SGH ended up using the site response analyses, using this same profile, that had been done by ENGEO for LERA! This is noted in the 2018 Egan / Slate geotechnical report and elsewhere.

RE: SF Tower settlement Part II

Again from LB Karp's "Millennium Debacle" webpage. A letter from SG&H to SFDBI.

SG&H:
...Installation of a first indicator pile, immediately to the west of the building, along Fremont Street,
initiated in early February 2021. As reported in Slate Geotechnical Consultants, 14 May report,
the contractor was unable to maintain the rock socket in an open condition sufficiently long to
allow placement of instrumentation, reinforcing and grout. The contractor proposed an alternative
installation method, using a cased rock socket, which was used to install a second indicator pile,
nearby, and which was successfully tested on 19 April 2021.

RE: SF Tower settlement Part II

Thanks to epoxybot for the summary of what happened with the indicator piles but has anyone seen the results of the second indicator pile. They cut the number of piles from 52 to 42 based on one load test? I still suspect that the problem with utility locations had something to do with it. That was one of the points that Pyke made back in 2019. To which Hamburger responded "The required construction is neither complex nor unusual". He made no comment on utilities but did say "no dewatering will be required to enable the construction", which was not true. See Slate's monitoring report:



Although the drop in groundwater may not have been nearly as important as the "loss of ground" caused by the way they installed the casings.

RE: SF Tower settlement Part II

Here is another nice plot from Slate:



So, why did they not put the installation on pause by say the end of June when it was obvious things were going off the rails? Likely they would still be digging themselves in deeper were it not for Jaxon vdB's initial report on NBC Bay Area news.

RE: SF Tower settlement Part II

Quote (First we need to see the prior response in Comment No. 34, which is referenced in Hamburger's first No.1 but was not included.)


Is there a link to the EDRT comments?

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

-Dik

RE: SF Tower settlement Part II

Dik, the questions posed by the ERDT are attached to their letter to DBI but not the responses. I have a copy of the completed document which has the responses in it but a number of the responses refer to various "supplements", I guess supplements to the SGH 4 volume report. I don't know how much of this is on Larry Karp's web site Link but that's the best source that I am aware of.

RE: SF Tower settlement Part II

Thanks...

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

-Dik

RE: SF Tower settlement Part II

Quote (Walnuts)

So, why did they not put the installation on pause...
To put it as politely as I can they are .. the last four letters of your screen name.

RE: SF Tower settlement Part II

It almost appears that they have no solution on hand and are in a bit of a panic mode...

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

-Dik

RE: SF Tower settlement Part II

Question for

Quote (Walnuts)


Could they fill the 36" casings x approx 100' with a mixture of 50% scrap steel or scrap iron @ 490 lb/ft3 and 50% normal wt. concrete @ 145 lb/ft3 where the inner casings have not been sunk to bedrock. This would increase the overburden pressure by say 317 lb/ft3 to give a load of = 3.1416 x 1.5^2 x 100 x (317-120) = 139K of added overburden/pile. So 42 piles x 139 k = 139 x 42 = 5838 k of overburden on the lower sides of the building. This is in addition to the estimated 120 lb/ft3 removed as soil and water from the pile boring. Added pressure on the firm layer above the old bay clays would be 19.7 ksf which would tend to push up on the pile group.

Could this assist in to undoing the damage they have done so far with their drilling. Do your geotech thing here for me.

RE: SF Tower settlement Part II

Sorry apper.42, I think that would make it worse. My own thinking is that they should abandon the Perimeter Pile Upgrade and look at freezing the Old Bay Clay as someone has suggested earlier in the string.

RE: SF Tower settlement Part II

Do you think it is possible to freeze the soil and while it is frozen, to go in an do a proper piling job?

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

-Dik

RE: SF Tower settlement Part II

Agree that they should abandon the exterior solution but I assume they will at least have to fill the 36" casings with concrete or gravel.

With lensing in clays being so.... unpredictable freezing is risky and so expensive to maintain. I have seen fairly firm clay (shear strength > 1500 psi) in a split basement with water in the lower level where frost heaved and split an 8' high 9" concrete wall and 18" x 5" footing virtually 4 feet vertically at the boundary between the frozen and unfrozen level. I think a majority of the sudden extra settlement was caused by removal of overburden and groundwater but I am no geotechnical engineer.



RE: SF Tower settlement Part II

Quote (so expensive to maintain)


not permanent... only temporarily until the 'fix' can be done. I'm not sure what the fix is... but for seismic reasons, I would think it would have to be symmetric with the structure.

We've had instances where water can be contained in clay at -40C in a supercooled state because the clay is so tight the ice crystals cannot form.

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

-Dik

RE: SF Tower settlement Part II

Maybe an upcoming Terzaghi can do a study similar to the Transcona grain elevators...idea

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

-Dik

RE: SF Tower settlement Part II

On November 19, 2020 Ron Hamburger gave a presentation titled Understanding San Francisco’s Millennium Tower Investigation and Retrofit. It used to be on SEAONC's website but no more.

Under Emily Guglielmo, SEAONC gave their 1st Virtual Convention from Dec. 2nd-4th.
This was the teaser...

...SEAOC's first-ever virtual convention will take place December 2, 3, and 4, 2020. Making the transition to a fully virtual convention is no small task, and the convention committee and presenters have worked hard to make the sessions engaging and accessible. The dual-track technical program is filled with over 30 compelling presentations, opening with a session by Professor Greg Deierlein of Stanford University about the work of SimCenter, and closing with a presentation by Ron Hamburger on the Millenium Tower Perimeter Pile Upgrade. PDH credits will be available for sessions that are watched live. [End]

The "Proceedings" include a paper by SG&H, which is shamelessly loaded with blame for all the surrounding properties and very little to say about the poor foundation.

Whoops! Here is a link to the video. (Scroll Down)

Okay, the video is definitely worth a watch.

RE: SF Tower settlement Part II

Quote (epoxybot)

SEAONC
I was just watching the Ron Hamburger talk when my city felt the largest earthquake ever recorded here. 5.9 but only very minor damage as the epicenter was miles away. No serious seismicity from that area ever before.

RE: SF Tower settlement Part II

FYI, AusG is talking about Melbourne, Australia.

RE: SF Tower settlement Part II

Quote (SEAOC 2021 CONVENTION, September 22-25, Technical Presentations do not include Millennium Tower.)


Not even as a 'what not to do'?

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

-Dik

RE: SF Tower settlement Part II

So the 2020 Virtual Convention video takes forever to load. At about 26 minutes into the video, Ron Hamburger describes the 3 foot thick section of the mat. I have transcribed, this portion for posterity.

Ron Hamburger:
...What’s important to understand here, as to why the building is tilting; I talked before about the 3 foot thick portion of the mat, at the south end of the structure that is soil supported.

As part of the construction of the Transbay Terminal to the south, the team that developed the Transbay Terminal, constructed a deep buttress wall immediately to the south of the Millennium tower site and the intent of that buttress wall was to protect the Millennium tower against soil movement beneath it; as the excavation for the train box, beneath the Transbay Terminal, occurred.

We believe that the southern end of this 3 foot thick mat is hung up, on this buttress wall, which was constructed adjacent to the Transbay Terminal.

Which is why it is not settling much.

Whereas the rest of the building is settling quite a bit.

And this explains a bit, why the building is tilting as much as it is, to the north & to the west.

When we looked at the behavior of the mat under dead & live loads and opposed settlement, using this refined non-linear model, we found the building was behaving very well indeed and there was almost no non-linearity that was visible, except at the juncture between the 3 foot thick mat & the 10 foot thick mat, at the south end of the structure.

There we see that a plastic hinge has formed, in the mat, as a result of those steep contours that are occurring at the south end.

Basically, what has happened is that the bottom layer of reinforcement in the 3 foot thick mat, which extends into the thicker 10 foot mat, HAS YIELDED, allowing the 3 foot thick mat and the PG&E vault to rotate, relative to the building.

We’re not seeing cracking in the mat in that area because the cracking is on the underside, of the mat.
The plastic rotation is very small, on the order of .4%, which is why we are not seeing any crushing or spalling. [END]

I can't believe he said these things to a group of engineers. To begin with, the buttress wall is behind a shoring wall built by the TJPA's Buttress-Shoring & Excavation Contracted builder, Balfour-Beatty Infrastructure. That didn't take place until mid 2011.

The 103 crack gauges, were installed in the tower & podium/garage BEFORE the Certificate of Completion (Aug 09) was issued. Years BEFORE the TJPA's shoring wall & buttress wall even existed. To my mind, the cracks in the basement east & west basement walls near the south end of the foundation are the result of the same forces acting on the mat. Ron Hamburger's statements and John Egan's Mat Grillage sound and look dodgy. But equitable.

It just doesn't fit with Gregory Deierlein's assertion that all the deformation in the mat took place BEFORE the tower was open to occupancy.



RE: SF Tower settlement Part II

Thanks epoxybot! I think when Hamburger says "hung up" he just means that the vault is close enough to the shoring wall that it has to overcome some traction on the wall in order to settle. But that is not very likely. Maybe for a very quick settlement, but over time it would creep down if it wanted to go down. There are two much more likely explanations for the differential settlement: (1) the intermediate sand layer is not a single uniform layer. It is a layer of mixed deposition and variable thicknesses. Also the "crust" of the Old Bay Clay is likely of variable thickness having been eroded non-uniformly before the sands were deposited on top of it. This is all "known". (2) The second possible reason is more speculative but if the enhanced rate of settlement during the perimeter pile installation is due to the OBC oozing into the casing, as seems to be suggested by Dr Vahdani, doesn’t this suggest, along with the overall pattern of continuing settlement, that a creep bearing capacity failure is occurring in the OBC? This might explain why settlement continued for at least two weeks after the pile installation was put on hold – at that point I think the 36-inch casings were all tipped in OBC – and why the extensometers show continuing “settlement” in the OBC? Again, this is a bit speculative but the tendency for a creep bearing capacity failure (you push down on a soft clay and it bulges around the outside of the loaded area - classic soil mechanics), would be resisted much more on the south side (the bus station) and the east side (the podium building with a garage underneath it). It would be interesting to know if the intersection of Fremont and Mission has come up at all.

RE: SF Tower settlement Part II

Is anyone else wondering why anyone involved (AHJ, principal engineers, etc) are talking publicly about the project? I mean, it's a complete clusterfuck and everyone is going to be sued. Part of a condition of our insurance is generally not to impair our insurance company's ability to defend once we know of or should have reasonably foreseen that a suit would be forthcoming. Don't you think statements about causes/failure/whatever even if well intentioned, may potentially void insurance coverage if they turn out to be wrong (and most will be just by the nature of this thing)?

I appreciate people willing to talk from a general interest perspective. But I really think the hole they are digging themselves is quite deep and tilted (pun intended)

CWB (W47.1) Div 1 Fabricator
Temporary Works Design
https://www.enable-inc.com/

RE: SF Tower settlement Part II

I get the impression they knew about the 3 foot thick portion of the mat cracking before the 2017 City of San Francisco - SG&H Report. Why wasn't it in the 2017 report?

RE: SF Tower settlement Part II

Quote (I can't believe he said these things to a group of engineers.)


ROTFLMAO comes to mind... it's kinda rude though... but, other engineers would understand and would appreciate it.

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

-Dik

RE: SF Tower settlement Part II

At which point does the hamburger lose all credibilty?

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

-Dik

RE: SF Tower settlement Part II

Quote (dik)



At which point does the hamburger lose all credibilty?



Glad you asked. I think here:

Quote (spsalso)



"The required construction is neither complex nor unusual." Ronald O. Hamburger

So, then, the job was a piece of cake; and if it failed, the designer was a total incompetent and shouldn't be trusted to tie his/her own shoes. Or so it seems implied.




spsalso

RE: SF Tower settlement Part II

Quote (Walnuts)

.... but the tendency for a creep bearing capacity failure (you push down on a soft clay and it bulges around the outside of the loaded area - classic soil mechanics),

This is why I suggested earlier to restore the overburden pressure and counteract this bulging into the casing and causing it to bulge out and under the pile group and counteract the sinking. You did not think that this would work; I think that the overburden removed for the 3' casings is the main reason for the increased settlement.

RE: SF Tower settlement Part II

Quote (dik)

At which point does the hamburger lose all credibilty?

I'm not sure but his career is probably "fried" or possibly BBQ'd

RE: SF Tower settlement Part II

Hamburger seems to have proposed that the tilt of the building is caused by the "flap" on one side being held up by a retaining wall--hence it rotates about that point.

So how's about we build a retaining wall on the OTHER side, scab on a bunch of concrete, and lift like hell with the hydraulics? Or perhaps a whole lotta prybars being used by the homeless being paid the new minimum wage. Just a thought.

Proof of concept has already been demonstrated by the first "flap". According to Mr. Hamburger.



spsalso


RE: SF Tower settlement Part II

Quote (hamjohn)



Tilting Millennium Tower in San Francisco Faces New Plumbing Problem

https://www.msn.com/en-us/travel/news/tilting-mill...



As someone who has spent a few hours in proximity to drain pipes, I will speculate that the Engineers who designed the drain system did not leave any "slop" for correcting these problems.

What you want: "Don't worry. We'll just cut this section out and fit a new one with some more slope. Two hours, tops! Who's buyin'?"
What you don't want: "Ya know, if they'd only left a little room here and some space there......."

I look forward to being corrected.


spsalso

RE: SF Tower settlement Part II

apper.42, I thought you were suggesting filling the 36-inch casings with heavy material. That might help reverse the extra settlement caused by the faulty installation of the perimeter piles, or might not, we don't have enough information so we are speculating on what happened, but if the "creep bearing capacity failure" is correct, you would have to surcharge Fremont and Mission Streets. I doubt that that is practical. But I agree with you that the hamburger is more than overdone at this point.

RE: SF Tower settlement Part II

The expression in these environs is, "done like a turkey."

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

-Dik

RE: SF Tower settlement Part II

I suspect the structure has some serious seismic issues. I'm not big on seismic, but the building is tall and is founded, rather shallowly IMHO. A seismic event is relatively unpredictable. In the event of one, there could be some serious loss of life for those in the building as well as those on the ground. For this reason alone, I would think that the city of San Francisco should be looking for an immediate response to the 'leaning tower' problem. They need to get some serious and good geotekkies out on site, immediately.

Else, California, could outdo Florida.

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

-Dik

RE: SF Tower settlement Part II

The 'fix' of putting piles down to the bedrock only in one corner of the building certainly seems like it will give it a pretty serious 'seismic issue'. The whole concept of building large buildings on partially consolidated clay seems pretty dodgy in the first place, but presumably the engineers have considered that for all the other buildings around there.

> I will speculate that the Engineers who designed the drain system did not leave any "slop" for correcting these problems.

When you're trying to put utilities into a building you're going to assume the building is a fixed point, and pack things in as tightly as you can. I can't really blame the internal engineering for not allowing for the building floors no longer being horizontal!

RE: SF Tower settlement Part II

"...pack things as tightly as you can."

Yeah. What could go wrong?


spsalso

RE: SF Tower settlement Part II

Quote (spsalo)

tightly as you can."

Just like a junction box that's too small.

RE: SF Tower settlement Part II

> What could go wrong?

I dunno but it's almost certainly the next guy's problem, not mine!

RE: SF Tower settlement Part II

Link to 301 Mission Street - Millennium Tower Retrofit Documents:
https://sfdbi.org/reports

RE: SF Tower settlement Part II

Quote (hamjohn)



Link to 301 Mission Street - Millennium Tower Retrofit Documents:
https://sfdbi.org/reports


A person could wonder why the contents of reports 11, 13, 15 are all copies of report 9.

And a person could wonder why the contents of reports 18, 20, 21 are all copies of report 19.


Are reports ending in 9 so remarkably important that they should be shown repeatedly, instead of the correct ones?




spsalso

RE: SF Tower settlement Part II

I'm stumped about the Too Big concept. The auger fits inside the casing. What am I missing?

RE: SF Tower settlement Part II

I was also stumped at first but then I discovered that the auger does not go inside the casing - at least not for the 36-inch casings. They only used that big auger to drill the first 20 feet of so so that they can set the first length of casing. Then they push (crowd) the casing down, attach new casing lengths with a special fitting of some kind, and use a bucket to remove the top of the plug. I have no idea how they judge what to remove and how much plug to leave in, but the ERDT has suggested leaving a longer plug and making sure that there is a positive hydraulic gradient. I thought all this was elementary. I know less about the 24-inch casings but I think they admit to over-drilling them, so I guess Legacy are going to Home Depot to buy a slightly smaller auger, or whatever it is, for that.

RE: SF Tower settlement Part II

Well, all work except drilling some soil borings at the N-W corner. Even that seems to have triggered a bit more settlement and tilt!

RE: SF Tower settlement Part II

So far, the only use I have found for this chart is noting Mission Street Development/Millennium Partners/Paul Hastings LLP/SG&H/Slate efforts to continue to disguise the construction phase as problem free.

RE: SF Tower settlement Part II

Is that leaned 1/2" or settled 1/2"... just curious.

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

-Dik

RE: SF Tower settlement Part II

I like the prominent leaning arrow in the Slate logo. They were made for this project. "Better Slate than never!"

RE: SF Tower settlement Part II

Currently, the tower is tilting 22.5 inches towards Fremont and 9 inches toward Mission. Under Hamburger’s analysis, the building can tilt 6.5 inches more to reach the 29-inch threshold on Fremont and three inches to reach the 12-inch Mission threshold, and still remain seismically “safe and stable.”

https://www.nbcbayarea.com/investigations/millenni...

RE: SF Tower settlement Part II

In response to epoxybot, it has been "tared out". For instance, there have been various reports of up to 6 inches dishing of the mat during construction but these have basically been buried. Hamburger mentioned that in his first ever draft report and then it disappeared for a long time. However, it has resurfaced in some of his recent comments in the comment log.

In response to hamjohn, the lateral roof deflections were about 16 inches to the west and 7 inches to the north when they started the PPU, so in each case they have so far used up about half of their own margin of safety. One of many big questions is why did they keep going so long?

RE: SF Tower settlement Part II

Serious question: How likely is it that there is already a team of engineers working on a disposal plan for the building? It would seem to be prudent to have a variety of contingency plans at the ready, up to and including disposal.

RE: SF Tower settlement Part II

Is that before or after it falls... if they have contingencies, from a legal point of view, they were planning for the collapse and may be more liable in the event someone is hurt and they didn't do very much. They may already be in that situation. This is already a lawyer retirement project...and you have lots of rich people with lots of 'big' lawyers.pipe

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

-Dik

RE: SF Tower settlement Part II

Quote (Currently, the tower is tilting 22.5 inches towards Fremont and 9 inches toward Mission. Under Hamburger’s analysis, the building can tilt 6.5 inches more to reach the 29-inch threshold on Fremont and three inches to reach the 12-inch Mission threshold, and still remain seismically “safe and stable.”)


and what happens at 29-1/4"? I'm not into seismic designs other than a few simple projects... but, the current structure does not look really great. That 'bowl of soup' it's sitting in doesn't look particularly nice, to me.

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

-Dik

RE: SF Tower settlement Part II

oops... 24"

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

-Dik

RE: SF Tower settlement Part II

Here we go again. Why would victaulic type connections not be even faster than bolting (if indeed the time to splice the casings is actually the problem) only 4 bolts does the job and its water tight; I assume they would be attached above ground level so victaulic type couplings using collars welded on the thinner casings should not be a problem unless the casings are so thin that distortion would be a problem. Victaulic couplings are available up to 255 in. diameter. In the end the casings probably don't have to cary any compressive load.

Bolts, collars or couplings sticking out may in fact all be a problem by enlarging the hole outside of the casing. Even bolts will protrude about 1/2 in.

They still obviously have no real clue if this will work and they are quickly running out of acceptable added settlement. Hamburger will be dead meat if he is wrong again.


RE: SF Tower settlement Part II

Another update on NBC last night Link I don't think it says this in the clip, but the text on the web site says "Patrick Hannan, spokesman for the Department of Building Inspection, said the drilling expert, Dan Brown, was hired last week to evaluate the testing plan. “He’s been providing feedback and insight on the planned proposal going forward,” Hannan said." Which is good, but if the design team had any sense of their limitations, they would have done this before they started! And, it doesn't address the fact that the perimeter pile upgrade is nuts.

RE: SF Tower settlement Part II

From the link, you almost wonder if they know what they are doing... I'd be meeting with a 'bunch' of good geotekkies and engineers and see what suggestions they can offer and see what information is still required. This is urgent; you want to have spare time 'at the other end'. It doesn't seem that the hamburger has a clue.

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

-Dik

RE: SF Tower settlement Part II

You'd almost think the hamburger has a vested interest in the outcome...ponder

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

-Dik

RE: SF Tower settlement Part II

The Millennium Tower Association that represents homeowners is still not commenting. Interestingly though, we found an online presentation that Hamburger did in February for students at the University of Minnesota that seems to confirm property values are at the core of all this. In it Hamburger points out “There is no reason structurally that the building needs to be upgraded. Homeowners needed a major retrofit to ‘revalue’ their units.

https://www.msn.com/en-us/money/realestate/update-...

RE: SF Tower settlement Part II

Quote (dik)

You'd almost think the hamburger has a vested interest in the outcome...

I think Hamburger was trying to get his two cents in for the evening broadcast. SF Gate & The SF Chronicle are sister organizations and frequently coordinate with KPIX/CBS.

RE: SF Tower settlement Part II

didn't know that... thanks. Don't you hate it when you did a deeper excavation for yourself?

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

-Dik

RE: SF Tower settlement Part II

Quote (epoxybot)

...trying to get his two cents in ...
What is the cost these days of a couple of billion in professional liability insurance; a bit more than two cents I will bet. Oh, I see, you just declare bankruptcy and move to the East coast where bedrock is closer to the surface. This just gets more insane every day.

RE: SF Tower settlement Part II

I think Hamburger is a bit disingenuous in suggesting that the pile installation was finally stopped on his recommendation: "On the day that I recommended that the 36 inch pile installation stop, the Millennium Tower HOA instructed the contractor to stop, in line with my recommendation." Surprisingly, I think it was actually the ERDT who showed at least a little backbone and forced both the halt of the 36-inch casings and the subsequent halt of the 24-inch casings/piles. The history is: July 29, Greg Deierlein sends an e-mail to the DBI complaining that the suggestion that work be halted, with which they agree, has not been acted on. August 2, they put the 36-inch casing on hold. August 19, there is a meeting at which the design team offers nonsensical responses to ERDT questions about the causes of the enhanced settlements. August 22, the 24-inch casings/piles are put on hold.

RE: SF Tower settlement Part II

apper.42,

That wouldn't work well, as SGH is based in Massachusetts. Besides, with the possible exception of this building, their record is outstanding.

RE: SF Tower settlement Part II

I'm a bit confused about the start date for this project. AECOM entered an agreement to sell Shimmick Construction in December to a small-mid sized private equity firm. It completed the transaction in January. I can't tell if Legacy Foundation was part of the sale.

AECOM bought Shimmick in July 2017. So did AECOM bail on a $2B+ liability and did Sage Geo, which was purchased by Gannet-Flemming, do the same? Or does AECOM still hold the liability?

AND this is an ironically fun read: An Unsuccessful Urban Deep Excavation in Soft Soils

RE: SF Tower settlement Part II

Shimmick and Legacy now have the same address in Irvine so I assume that Legacy escaped from AECOM along with Shimmick. I did not realize that AECOM had bundled the remnants of MK and the Washington Group in with Shimmick, but I had assumed that AECOM would end up losing their shirt like MK did. But I guess the accountants who run AECOM were smart enough to get rid of the construction entities before that happened. I don't think that John Egan and the people who left to join Slate when Gannett Fleming bought SAGE were there long enough to incur much liability, but I hope Slate and SGH have good insurance! More than the standard $5 million E&O insurance that I understand Treadwell & Rollo had. But the key thing is that MSD (the Millennium Partners subsidiary that was the developer of 301 Mission St), as part of the mediation agreement, took out insurance to cover satisfactory completion of the fix. I wouldn't want to be holding that policy!

RE: SF Tower settlement Part II

Quote (AND this is an ironically fun read)


Hehehehe... but, that was in SanFrancisco...pipe

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

-Dik

RE: SF Tower settlement Part II

dil - I found most of the bullet points, as to what went wrong, to be strikingly similar to the issues at 301 Mission.

RE: SF Tower settlement Part II

Funny... that's why I 'laughed'... I noticed the same similarity, and my earlier comment about the hamburger being 'done'...

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

-Dik

RE: SF Tower settlement Part II

This photo from ENR on Sep. 29 2021, somewhat suggests that revision of the number of piles from 52 to 42, resulted in abandonment of work in progress at the southern limit of the Perimeter Pile Upgrade.



RE: SF Tower settlement Part II

John Egan’s report of June 23, 2021 stated the sum of 36” casings on Fremont St. would be completed by June 25, 2021. Why risk another 36” pile on Fremont St., which is the most problematic source of settlement?

RE: SF Tower settlement Part II

epoxybot, location 33 where they are going to do the test 36-inch casing is the third pile on Mission Street. They did finish the 36-inch casings on Fremont back in June. If they keep the water level up, settlement of the corner should be minimal unless there is "heave" into the tip of the casing of the OBC. They have dismissed that as a cause of the increased rate of settlement but questions in the comment log suggest that Shah Vahdani likes it. He may be right. Almost certainly it is not vibration. That makes no sense for several reasons.

RE: SF Tower settlement Part II

There are better mimes than ours at work...ponder

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

-Dik

RE: SF Tower settlement Part II

Walnuts, I would hope so but the text of the NBC report states Fremont Street.

RE: SF Tower settlement Part II

epoxybot, good catch! I had seen / heard that report but did not catch the error. I am pretty sure that Jaxon knows it is on Mission, but he just misspoke. I have seen the letter from SGH to Patrick O'Riordan with the final "protocol" and it has an error saying they will stop if the settlement of the north-east corner exceeds 1/4 inch (increased from 1/8 inch in the draft). I am pretty sure they mean the north-west corner. Not their worst mistake! I don't think that they will come close to 1/4 inch for a single 36-inch casing so this might just be a "false flag" which will allow them to claim great success. But SGH stick to saying their expectation is that settlement will not exceed 1/8 inch (reasonable) and lateral deflection of the roof will not exceed 1/4 inch (ratio of 2 - other work near the north-west corner has shown tilt to settlement ratios of more like 4 or 5.) I am not sure that the test will prove anything!

RE: SF Tower settlement Part II

It may seem silly, but can they put 'well points' down on the side opposite the tilt and draw ground water off to maybe 'right' the tilt?

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

-Dik

RE: SF Tower settlement Part II

Quote (dik)

...but can they put well points down...

Rather than lowering the high side I think it would be better to try and raise the low side by trying to recharge the water table on the low side to replace all the water removed when wet sand was removed from the 36" casings. They also removed considerable weight of overburden. Any increase in the water table would increase the buoyant force on the bottom of the raft on the low side. Most of the conductivity in the sand is in the horizontal direction. Slight excess pressure of 5 to 10' of head on the injection system might be effective without liquifying the sand layers.

RE: SF Tower settlement Part II

Until they investigate the cause of the southeast corner of the tower driveway's 'phenomenon', as to why this area defies settlement; I think they are just asking for trouble. The southeast corner must have a lot of Young Bay mud under pressure. The current tilt tends to confine the mud on the east side, while squishing mud out the west side.

When I look at Slates ground profile, showing the Colma sand hump, I wonder if the sand hump and the even larger Young Bay Mud 'bulge' are the result of the tower's southeast behavior.

The Marine sands and the Colma sands are both aquifers. The lower Young Bay Mud is only 10 feet thick & very plastic.

This, from John Egan's June 18, 2021 report of piezometer readings...
Piezometers
Several sharp increases of piezometric head have been observed in the PB-1 piezometer at a depth of 85 feet bgs (located in the Marine/Colma Sands). The spike on May 15, 2021, between 6AM-12PM corresponds to a known influx of water onto the crane mat/sidewalk during installation of the 36" casing as the auger is retracted and soil is removed. The Building Engineer for the Tower also noted water infiltration into the basement. Similar increases were not observed in SB-1 and PB-2, as these piezometers are not situated close to the source of this water influx.

Additional spikes were observed on May 28, 2021, June 1, 2021, and June 7, 2021, all between 6AM and 12PM, and on June 11, 2021, between 6AM-9AM. The cause of the May 28 and June 1 spikes is not known, but likely is similarly due to an influx of water as described above. The spike on June 7 corresponds to advancement of the 36-inch casing for Pile #27 to a depth of ≈89 feet feet bgs and on June 11, the spike corresponds to advancement of the 36-inch casing for Pile #28 similarly to a depth of ≈89 feet feet bgs and observed water addition; both Piles #27 and #28 are located in close proximity to Piezometer PB-1.

For the piezometers in the Old Bay Clay (OBC), piezometric head at the PB-1 piezometers was influenced (increased) by the installation of the nearby Indicator Piles and has exhibited a general trend of decrease (dissipation) since then. Small increases of the head in the PB-1 piezometers at depths of 105 feet bgs, 120 feet bgs, and 135 feet bgs was observed on May 17, 2021, but piezometers at greater depths were not noticeably affected. Advancement of the 36-inch casing for nearby Pile #25 achieved its tip depth of ≈102 feet bgs on that day. Sharp decreases in the PB-1 piezometer at 105 feet bgs was observed on June 7, 2021, between 3PM-6PM and on June 11, 2021, between 6AM-9AM and 12PM-3PM. The decrease on June 7 corresponds to advancement of the 36-inch casing for nearby Pile #27 to a depth of ≈101 feet bgs and the decreases on June 11 correspond to advancement of the 36-inch casing for nearby Pile #28 to depths of ≈89 feet bgs and then ≈103 feet bgs. The decreases may be result of release of water from OBC into the casing, as the length over which the head loss occurs is much shorter after removing the soil inside the casing. [END]

Serendipity would have it that LB Karp was on-site taking pictures on June 15th and you can see the results of the water influx, on hat date. Photo 1 & Photo 2

Post from SF tower settlement (Part 1)

BUGGAR (Structural) 23 Sep 18 00:56
Bay Mud really is interesting stuff. The contractor approaching the Lower Market Street Station used a tunnel shield in the Bay Mud and the muck (mud) was routed through the face of the shield through a large tube like so much cookie dough. Of course it was referred to as elephant shi*

My questions, is whether the Lower Young Bay Mud is leaking water from the Colma Sand aquifer, upwards into the Marine Sands, during drilling operations, where the horizontal conductivity is greater and the water more readily disperses over a wider area, resulting in volume loss. This would be around the outside of the casing. Subsequently the Lower Young Bay Mud 'heals' around the casing, shutting off the water leak from the Colma Sands.

RE: SF Tower settlement Part II

It might be a tad easier to remove water than to add it...

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

-Dik

RE: SF Tower settlement Part II

Hamburger and his group appear to have done a great job in removing groundwater and overburden and relieving pressure at the sand OBC layer and possibly between the sand and Young Bay Clay. This is why I think that probably overburden pressure should be restored and possibly increased depending on competent geotechnicaL assessment or review and that the water table should be raised if possible. Perhaps a verification is needed to see if the SE corner is actually hung up on the adjacent basement, which I personally doubt just because of the force that would require it to hang up would breach the basement

RE: SF Tower settlement Part II

If the Leaning Tower is "hung up" on an adjacent basement, that implies construction on someone else's property. By someone.

If the adjacent basement was there first, as it would have to be, it's interesting that the new builders either decided to build on top of the intruding structure, or did not actually know it was intruding. Or even built on someone else's property themselves.

"The required construction is neither complex nor unusual." Ronald O. Hamburger


spsalso

RE: SF Tower settlement Part II

They only talk about vertical settlements and lean at the top in N and West directions, not sure if they have monitored any lateral movement of the entire building in any direction. With the soft bay clay is it possible that the piles are slightly S shaped and the building has moved laterally. So far I have assumed that measurements are relative to some fixed vertical datum and some horizontal fixed coordinate system but have not seen any lateral measure to some fixed point. Oh, right is anything really fixed sitting on this geological formation if piles do not go to rock.


RE: SF Tower settlement Part II

...and what sort of P-delta effect would that have?

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

-Dik

RE: SF Tower settlement Part II

If the tops of the piles are fixed at the 10' thick slab the tilt of the building would tend to bend the tops of the piles so that they curve slightly out to the East. If the piles are not fixed the tilt would tend to crush the edge of the pile tops. Since the tilt of the building is at about 0.3% ie .003 ft/ft this would mean that no matter if fixed or pinned the strain in the piles at the top would be .003 in/in which just happens to be the strain limit for ultimate design. Since the base slab is apparently dished this could mean that the slope on the East side of the building could be greater than 0.3%. So some of the building settlement could be from failure in the tops of the concrete piles to various degrees across the building. There certainly could be a lot going on here at once; enough to confuse the engineers.


RE: SF Tower settlement Part II

Dug up this picture from a 2016 article written by Alex Weinberg P.E. then of NY. The included photo clearly show the 14" square pile tops protruding into the 10' thick pad with dowels already coming out of the tops to transfer load to the base slab. It would thus appear to me that the piles are virtually fixed at the slab which means that the building tilt will be transferred as moment into the piles. Since the piles are designed for axial load it is possible that the combined bending and axial load would overstress the piles. Since there are no details of the pile reinforcing it is not possible to check this theory but the tilt of the building would result in about 0.003 in/in of strain in bending only without axial load.

RE: SF Tower settlement Part II

Since it's been asserted that there is some sort of basement structure holding up the "uphill" part of the building, might it not be wise to search for a corresponding basement on the "downhill" or "sinking" side? Say, across the street. And rest that side of the building on it.

Clever minds will note that there is a street (just previously mentioned) between the tilting building and the needed basement.

FLYING BUTTRESSES!

Yup. Works for cathedrals. Mostly.

Best part is you could keep using the street. After construction.

No. There's something even BETTER. It would make the building actually visually interesting.



spsalso

RE: SF Tower settlement Part II

Quote (spalso)

...It would make the building actually visually interesting.

Oh, yeah! Just think of what they would do for the units they pass through on the way to the concrete core. Huge interior decoration potential!

RE: SF Tower settlement Part II

Quote (hpaircraft)



Oh, yeah! Just think of what they would do for the units they pass through on the way to the concrete core. Huge interior decoration potential!


I think the better route would be to make those newly subdivided units into Affordable Housing. Yes, there'd be less income for the property, but the points gained for Social Justice would offset that, I think.

spsalso


Herb Tarlek: "Do you know what we in sales call problems? Opportunities."

RE: SF Tower settlement Part II

Is this forum going to wind up becoming the laughing stock of eng-tips with never ending non serious ideas. Could we try and keep it relevant here.

RE: SF Tower settlement Part II

In the first week of June 2007, Webcor Builders reported to Treadwell & Rollo that the tower appeared to be moving to the east. This was while the east face of the tower's foundation was tied to tower/podium shoring wall and the tower was around 20 floors up.

The production pile reinforcing was given in SG&H's 2017 Seismic Safety Report. SG&H butchered their description of the tops of the piles on page 5 of the report. There are so many mistakes, in their description of the piles that it borders on suspicious. Since it was one of the key aspects that the Peer Review asked to be examined, it is amazing that no one bothered to compare what SG&H wrote, with the figures at the end of the report.

LB Karp already suspects that there are failed piles under the tower.

One news report stated there is a SF Gov. hearing scheduled for next month.

RE: SF Tower settlement Part II

Not only Larry Karp but also the LERA team. I don't know if that's where Larry and Josh learned of their concern about the tops of the piles or if they developed that independently. But the LERA team believed that one of the advantages of their "internal" fix is that the micropiles would be driven (actually pushed, not driven)through stout casings inserted through the mat and that these casings would restore some of the moment capacity that has been lost. I am not sure how critical this really is since the structures is embedded 25-35 feet, but even a small amount of dishing and tilting must have caused some damage to the tops of the piles.

RE: SF Tower settlement Part II

Not me. I am just a simple dirt engineer.

RE: SF Tower settlement Part II

I think that the situation is so serious that Hamburgers group must be exposed for saying that the building is completely safe and nothing has failed. We have 950 prestressed piles that have an imposed rotation applied of approximately 0.003 in/in in bending which is the definition of the strain limit for ultimate strength of concrete. However the axial load in these piles due to prestress is 967 psi or 0.97 KSI which for an E = 4.8 x 10^3 KSI (7000 psi concrete) results in an initial axial strain of = 0.97/(4.8x10^3)= 0.0002 i/in The permanent vertical load per pile including is 229700 K /950 = 241 k/pile = 241/(194.9+(1.22x6)) = 1.19 KSI which gives a total strain in compression of 0.0002 + .0003 in/in = 0.0005 in axial and plus 0.003 in/in bending = 0.0035 in/in total strain. These figures are based on each pile carrying equal load and an equal fall east to west of 0.30% ie 22.5 in or 1.875 ft in about 640 ft = 0.00293 in/in.

Without any wind or earthquake the concrete piles at the slab are already strained well beyond the traditional 0.003 to 0.0035 strain limit for concrete in ultimate strength design and it should be incorrect to argue that nothing is overstressed. I agree 100% with Karp and the LERA team that probably a number of piles have failed.

Hopefully someone could verify my calculations and hopefully find some error or the building is not in a great situation. Walnuts & dik it might be time for you step up and prove me wrong. Since I deleted and revised this post Walnuts has already indicated he is not interested. Can someone else check.

RE: SF Tower settlement Part II

If the piles are disconnecting from the slab, as I think apper.42 is suggesting, then what is happening? The piles are still there to take the compressive load, so the slab shouldn't suddenly "smoosh into the mud" (a technical term).

The piles will still have an IMPERFECT connection to the slab.

So it would seem unlikely to have a catastrophic smoosh. More likely a drastically increasing tilt (sound familiar?).

But I'm just an irrelevant gadfly; what do I know?


spsalso

RE: SF Tower settlement Part II

Quote (spsalso)

If the piles are disconnecting from the slab, as I think paper.42 is suggesting,....

The fact that the concrete has technically failed in compression does not "disconnect" the piles from the 10' thick slab, reinforcing steel and friction in the concrete should maintain the connection but bending resistance is reduced or nullified and shear resistance is quite possibly reduced. Shear resistance is essential to transfer lateral loads from wind or earthquake to the piles. The tops of at least some of the piles have probably been physically damaged. It is very simple to check the slope on the base slab at any point across the 10' thick pad to assess the induced rotation of various piles in the group and the resulting strain. No catastrophic smoosh but, in my opinion, not good either. A slope of 0.3 feet across the 105' of 10' thick slab gives a slope of 0.003 ft/ft or .003 in/in which is the accepted limit for the strain in the concrete piles at ultimate capacity. Shoot a laser across and measure anywhere, simple.



RE: SF Tower settlement Part II

I came across this news item from 2016 yesterday.
Global Construction Review: "Residents’ alarm as heavy luxury tower in San Francisco sinks and tilts"
In describing the Millennium Tower project on its website, DeSimone says that by using performance-based design as well as code-based design, it was able to "optimize the design of the perimeter frames and reduced their sizes more than what would typically be allowed by code".

DeSimone, as like Webcor, no longer lists Millennium Tower San Francisco on their project page.


RE: SF Tower settlement Part II

"Performance-based design" is fine when it performs, but when it doesn't...

The building is too heavy for the site. When the decision was made not to found it on rock, it was doomed.

RE: SF Tower settlement Part II

I suspect you're correct... and in an seismic area, to boot.

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

-Dik

RE: SF Tower settlement Part II

When they take it down, they should sell 4" cubes of it as memorabilia. Perhaps giving them free to the various people involved in the project.

I'd pay five bucks! Maybe $7 if it's got rebar.

No, this is not meant as a joke.



spsalso

RE: SF Tower settlement Part II

It would cost more than that to 'cube' it... ponder As condo owners, are they responsible for the cost of demolition? ponder

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

-Dik

RE: SF Tower settlement Part II

Not sure if you guys have "iron rings" in the US but here in Canada the iron ring which used to be steel and are now stainless steel were supposedly made from the casting that broke when part of the second Quebec Bridge fell into the St. Lawrence River. The first one collapsed during construction because buckling was not well understood in those days and the latticing on the compression chords was not correctly designed. The idea of course is to remind all graduate engineers of their grave responsibility to the public and to themselves.

Rebar from the Millennium Tower could serve the same purpose for graduates in the US and there would undoubtedly would be a huge supply if the tower either collapses or is demolished. Unfortunately either way these rings would probably be the most expensive in history.

RE: SF Tower settlement Part II

Sad... and I hope it doesn't come about. For other reasons, I don't wear the iron ring... to me and for reasons other than the bridge, it an symbol of engineering gone wrong.

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

-Dik

RE: SF Tower settlement Part II

People make mistakes.

Hubris is thinking it's always OTHER people.


spsalso

RE: SF Tower settlement Part II

In my mind the Millennium Tower is similar to the miami pedestrian bridge in that it was a really bad idea right from the start. Think about building a structure more that 5x heavier per sq. ft. than steel structures around it and building it on clay fill. Call it a mistake but in my mind it is a stupid lapse of judgement; if that is hubris so be it.

RE: SF Tower settlement Part II

I think it goes a bit beyond hubris...

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

-Dik

RE: SF Tower settlement Part II

A certain Jurassic Park quote comes to mind.

RE: SF Tower settlement Part II

Quote (SwinnyGG)

"God help us, we're in the hands of engineers."

Is the first that comes to mind for me. Or possibly "Yeah, yeah, but your scientists were so preoccupied with whether or not they could that they didn't stop to think if they should."



RE: SF Tower settlement Part II

apper.42, it is not "built on a clay fill". There is fill at the site but the embedded part of the building goes through the fill and the forest of concrete piles goes down to a sand layer of variable composition and thickness at a depth of something like 80-100 feet. The problem is that the Old Bay Clay, which starts at about 100 feet is overloaded (technically was pushed back on to the virgin compression curve). Worst case is that there is an incipient bearing capacity failure in the Old Bay Clay - in laymen's term the Old Bay Clay is trying to squish out under Mission and Fremont Streets and under the podium building. (It can't squish under the Transbay Terminal because of the Arup/Koutsoftas "buttress".) It is hard to say what the Perimeter Pile Upgrade will do to this situation but one knowledgeable friend has suggested that the PPU "perforates" the sand layer, like the perforations in a roll of toilet paper, so that the sand layer distributed less of the weight of the building and more of the weight of the building is applied to the Old Bay Clay. Pretty hard to calculate with any accuracy but could be true. But regardless of that, the Old Bay Clay is susceptible to "secondary consolidation" due to re-orientation of clay minerals, which is one reason why the Tower has been settling an average of something like 1/2 inch per year for the last ten years (with a little fluctuation due to changes in the groundwater elevation). Slate seems to think that this is going to magically stop in about six years time (when with the north and west sides underpinned, the building might have leveled up), but I think that is unlikely. Also, a strong gust of wind from the west, let alone an earthquake, might be enough to squish more Old Bay Clay under the podium building. Old Bay Clay is a little stronger than young Bay Mud but has the same composition. It is just older and tends to be a little more "over-consolidated". But when pushed back on to its "virgin curve", it is a pretty soft clay. All this should have been known to the geotechnical engineers on the original design team. When Professor Jack Moehle tried to explain it away as an "act of God", he must have been out to lunch.

RE: SF Tower settlement Part II

Walnut, I agree, and I think you hit the bore with the proverbial hammer. I love the use of the technical term "squish", because it is the most descriptive word to describe the conditions.

CHeers

RE: SF Tower settlement Part II

Agree 100% also. As the guy described when they were tunnelling, it is a bit like elephant sh*t. Yes I exaggerated about the "clay fill" but in terms of geological time it really is just over consolidated fill which unfortunately is prone to more consolidation under the high load imposed by the building.

RE: SF Tower settlement Part II

I think what Hamburger is trying to say in regards to the mat being "hung up", is that the compression capacity is greater on the side in which the soil is basically captured, than the other side in which it is not, which is in my personal view is valid.

There is a train box, which DOT standards are pretty strict in terms of the amount of deflection allowed, and given the boring results implies that it is anchored in shale, with well points. . The only thing I can conceptualize to fix it would be to drive some caissons under the slab into bedrock and then bellow out the bottoms. I really don't understand why friction was even considered given the conditions of the soil.

When you build in a city, it is negligent to assume that nothing will ever be constructed near you, because everything is basically infill, and to claim "its there fault" for a faulty design is even worst.

What I don't understand is why hamburger didn't sink some 2" spoonbills into the side that he claims is hung up, in order to gain an understanding of what the condition actually is; strikes per foot, soil characterization, and moisture content can tell you a whole lot about what is happening -- and in my experience the more you know the closer you are to a solution.

RE: SF Tower settlement Part II

Quote (Keith_1)

I think what Hamburger is trying to say in regards to the mat being "hung up", is that the compression capacity is greater on the side in which the soil is basically captured, than the other side in which it is not, which is in my personal view is valid.

Undoubtedly the Tower/Podium shoring wall, the 105 ft deep TJPA shoring wall and the bedrock socketed buttress wall, result in higher modulus of subgrade at the S/E corner but the condition of the 3 ft mat being "hung up", existed BEFORE the TJPA had installed their shoring wall and later their buttress wall. Arup installed the 103 crack gauges in the basement of the tower in 2009, nearly 3 years before any ground work took place on the Transbay Transit Center property.

Transworld, the subcontractor to Balfour Beatty Infrastructure, responsible for moving the 301 Mission Screen Wall, 5 feet towards the tower, discovered cracks in the existing foundation/basement wall. The cracks are where the tower's basement/foundation adjoin the Parking Garage E/W Podium wall. It is recorded in Field Condition Report FCR-043 and reference in Webcor/Obayashi's W/O RFI T-0130

I came across this yesterday. It suggests that Hamburger's 2014 report, expressing concerns about the outriggers, during lower intensity earthquakes; might be the result of work by USGS' Mehmet Celebi.
"Responses of a 58-Story RC Dual Core Shear Wall and Outrigger Frame Building Inferred from Two Earthquakes"

Here's an interesting tidbit. The original EOR for the 301 Mission St. project, Dr. Niaz A. Nazir, joined DeSimone in July 2001 and immediately went to work on the Millennium Tower. This was when it had 3 and later 4 basement levels beneath the tower.

Previously, he had worked at EQE International, Oakland, CA. He joined EQE in 1999. In September 2001, Ron Hamburger was a Principal at EQE and head of Structural in Oakland. Hamburger was sent to work on the World Trade Center Disaster and in December 2001, Niaz Nazir was made EQE's Structural Group Manager.

Niaz Nazir passed away, unexpectedly, in May of 2004. Two days after his death, Treadwell & Rollo returned to the 301 Mission property to perform Bores B-6 & B-7, to sample the Old Bay Clay. It is the first physical indication, the tower was going to be heavier because of Webcor's scheme to move three of the tower's four basements to the podium/mid-rise.

RE: SF Tower settlement Part II

Quote (apper.42)

Is the first that comes to mind for me. Or possibly "Yeah, yeah, but your scientists were so preoccupied with whether or not they could that they didn't stop to think if they should."

This is the quote I meant, but your selection is equally applicable.

Life lessons as taught by Michael Crichton and Steven Spielberg.

RE: SF Tower settlement Part II

NBC: Original Cost to Build to Bedrock for Tower Like Millennium Put at Just $4 Million

After watching this video, I went looking for the Deposition of the TJPA's Executive Director from 2002 to 2015, Maria Ayerda. I had the right case number but was unable to find her deposition. What I did find was a lot more interesting, Exhibit materials! SF Superior Court case# CGC-16-553758 – Appendix of Exhibits in Support of TJPA’s Opposition to Langan Engineering’s Motion for Summary Judgment Volume 1 of 9. 2019-03-15

If you care to download the pdf file (free) it is 126mb. Go to the SF Superior Court website to query the case# and scroll down to 2019-03-15 Volume 1.

Beginning on page 50, are email exchanges, regarding settlement & the tower moving to the east, beginning in March of 2007. Webcor didn't notify Treadwell & Rollo until June 8, 2007. Ramin Golesorkhi of Treadwell & Rollo, under a sworn oath, told the SF Govt. Audit & Oversight Committee's Hearing on May 16, 2018 that there was only one settlement survey marker to monitor the tower. That wasn't the truth, the whole truth & nothing but the truth.

Page 62 shows that the podium wall was cracked and leaking before October 2008.

Starting on page 65, are settlement calculations based on the equivalent footing approach. The calculations are dated 10/28/2008 but the correspondence is from 2005. The deadload data was produced 6/16/2006 and doesn't quite match up to the 4 volume foundation calculations, dated May 24, 2005. There were two subsequent addendum to the foundation; with the last dated March 6, 2006. The deadload of the tower in 2005 was 208,622 and in March 2006 it is 221,180. At some point between May 2005 & March 2006, the mat slab increased from 9 ft to 10 ft and then they had to do some beefing up of the 2nd & 3rd floor due to the sloping SMRF at the south end of the tower.

On page 132 to 225, Treadwell & Rollo provide recommendations regarding the piling. This includes the full set of Indicator Pile driving records, the letter/s from InSituTech & CapWap results. InSituTech's letter date Nov. 17, 2005 comes with an expired engineering stamp. Granted, it is only 7-1/2 months out of date.

What is noteworthy about Treadwell & Rollo's - Ramin Golesorkhi's calculations, is that it doesn't account for the interference to the calculation by the tower/podium shoring wall. This is in October 2008, when the tower was already topped-out. Dare I quote Ron Hamburger and his statements regarding the south end of the foundation & the TJPA's Buttress Wall resulting in higher modulus of sub-grade?

Maria Ayerda was blowing smoke in her deposition. The TJPA was completely clueless to what Millennium was doing with the tower foundation. Why would the TJPA update their FEIR to proceed with a "Top-Down" design for 4 to 6 months and then immediately change course when they signed the Easement Agreement with Millennium Partners?

It turns out, the Perimeter Pile Upgrade is holding up Ron Hamburger's retirement as managing principal. He will still be Chairman of SG&H.

SFDBI has given Shimmick/Legacy permission to install 8 ea. 36 inch casings on Mission St. based on the "Success" of the 36 in. casing. By my count, that is 41 of 42 total; so it could be the final 8, to finish the 36 inch casings. Shimmick/Legacy apparently needs a part for the 24 inch casing rig. Haven't they had at least a month?

Ron Hamburger claimed the 36 inch casing test was a success, yet the settlement result over the remaining week's time, resulted in the maximum settlement and they haven't even drilled the 24 inch casing for the so-called test pile.

RE: SF Tower settlement Part II

So, using my simple minded approach 1/4" per pile (which I understood was their limit for the test) with a total of 8 piles gives another 2" of total settlement which could be likely, doesn't sound very hopeful to me. Sounds more as if this disaster is going to worsen soon if they don't stop what they are doing. Oh and we would still have 8 20" piles left to finish.

Stop, stop!!

RE: SF Tower settlement Part II

The SF Govt. Audit & Oversight Committee will hold a hearing on the status of the Millennium Tower Perimeter Pile Upgrade this Thursday, along with other business. The committee's meeting time is 10 AM Pacific.

I'm stunned! I have been suspicious and hard on Millennium Partners in my postings to this thread yet today I find that the TJPA was made aware of Millennium's design changes from 4 basement levels to just one in 2005.

In 2004 the TJPA's Executive Director enlisted the help of Arup, who was working on behalf of URS for the Caltrain component of the Transbay Transit Center, to evaluate a project that was in conflict with the footprint of the future rail approach to planned transit center. That project was 80 Natoma, a 52 story concrete high-rise that would have been the tallest, heaviest residential tower, west of the Mississippi.

In 2004 Demetrious C Koutsoftas, associate principal at Arup's San Francisco office, won the Ralph B Peck award for his paper 'Post-preload settlements of a soft bay mud site.'

Demetrious Koutsoftas assembled a Blue-Ribbon panel of Geotechnical Experts to look at 80 Natoma.
Dr. Jonathan Bray, Dr. Thomas D. O'Rourke, Professor Youssef Hashash, Dr. Andrew J. Whittle & Professor Emeritus Charles C. Ladd (Deceased). Not only did these eminent geotechs have concerns regard subsidence of 80 Natoma and also express their reservations as to the prospect of the TJPA's subsequent train tunnel build under the tower; two of the geotechs hinted that ground failure was a possibility, were the tower and the train tunnel to be built. A buttress wall of the tower was one scenario examined.

80 Natoma was a Tubex/Fundex piled project on similar strata but inshore and uphill of the 1852 Yerba Buena cove. 301 Mission was in the tidal zone of the cove, where tidal influence persists.

It turns out, according to court records, that the TJPA's Executive Director, Maria Ayerda, the TJPA's Chief Engineer, Elizabeth Wiezcha & Arup's Demetrious C Koutsoftas, were apprised of Millennium Partners new tower design & foundation in 2005. So they could have taken steps to insist that the foundation go to bedrock but instead chose to ignore it. The Aug. 23/24, 2005 email stream between TJPA's Chief Engineer, Elizabeth Wiezcha & Arup's Demetrious C Koutsoftas begins immediately prior to the Peer Review panels acceptance of the foundation design and demolition of existing structures remaining at the site.

Oddly, it was Demetrious Koutsoftas, in emails that expressed concern regarding disclosure of the revised 301 Mission tower foundation at a TJPA workshop, advising that there were people attending the workshop who could spread this information and how it would effect the TJPA's relationship with Millennium Partners!

Demetrious Koutsoftas had worked on the downtown Caltrain Extension for URS & then Arup, since 1997. He left Arup in 2006 ~retiring~. Later he filed article of incorporation with the Calif. Secretary of State in 2006.

After Pelli, Clark, Pelli contracted with Arup to provide subsurface engineering design for the transit center, Arup requsted that the TJPA permit the wording of their contract be changed to include the word 'negligent' ahead of the wording errors & omissions. It seems the negligence had already occurred.

Maybe Demetrious Koutsoftas' 'retirement' was a swift kick out the door.

RE: SF Tower settlement Part II

It seems to get more interesting... as I noted earlier, my experience with Arup is limited and based on that they are 'top drawer'. I'm surprised that this wasn't dealt with in greater depth.

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

-Dik

RE: SF Tower settlement Part II

epoxybot, I believe that Demetrious left Arup because of internal company politics.

But here is something really shocking. I finally got around to reading Treadwell & Rollo's 2005 revised geotechnical report (available on Larry Karp's web site.) Here is the piece on the foundation recommendation:

8.1 Foundations
8.1.1 Tower

We considered deep (piles) and shallow (mat) foundations for the support of the proposed tower structure. The sandy fill encountered in the upper 12 to 23 feet of the borings will be removed in its entirety during excavation for the proposed basement. However, Marine Deposits will be exposed at the base of the planned excavation and are unsuitable for support of a mat foundation. In addition, medium dense sandy layers encountered are expected to liquefy in the event of a major earthquake, as discussed in Section 7.2.1. Therefore, we judge a mat foundation would not be appropriate for the proposed 60-story tower.

On the basis of the results of our analyses and evaluation, we conclude the proposed structure should be supported on piles. Piles would derive their capacity from a combination of skin friction in the medium dense to very dense sand and medium stiff to stiff clay, and end bearing in the dense to very dense sand. From our experience with similar projects, we conclude precast, prestressed concrete piles or an auger displacement pile system (details are described in Section 9.2) are the most appropriate pile types for the project. We understand on the order of about 1,000 piles will be required to support the tower. Although piles will transfer building loads to less compressible strata, some settlement of the pile foundations will still occur. The settlement of the large group of piles will be due to the consolidation settlement of the underlying overconsolidated Old Bay Clay. We estimate settlements on the order of four to six inches could occur under the tower.

That's it! For a high profile 60-story building! No mention of the stress that will be applied to the Old Bay Clay. No mention of whether the Old Bay Clay might be pushed on to the virgin consolidation curve. No mention of secondary consolidation. Total reliance on "our experience with similar projects" when they had never done a similar project!

RE: SF Tower settlement Part II

...and with the concrete mass, this is not likely similar to any other project done.

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

-Dik

RE: SF Tower settlement Part II

Yesterday, I was asking myself, 'Why didn't Millennium Partners just come right out and say, they shared their foundation plans with the Transbay Joint Powers Authority in Oct. 2005, after receiving SF Planning Commission approval in July of 2005?' The most Chris Jeffries ever said, was that 'they were never asked to extend piles to bedrock.'

Now, for some reason, in the last 24 hours, I have been reminded that 2016 was an election year. California Gov. Newsom was mayor of SF in 2005, and running for Governor. It would have brought the wrath of many, had it been disclosed that the TJPA, which is weighted 3/2 with SF TJPA board members, had dismissed concerns about 301 Mission; with the specter of 80 Natoma rising up in the press. Newsom, who is House Speaker Pelosi's nephew, would have been rag-dolled by the GOP nationwide.

I've been through all the TJPA Board of Director meetings from 2003 to 2006 and the TJPA Citizens Advisory Committee meetings and not a word was ever mentioned about 301 Mission until the Item appeared on the agenda, in 2009, to vote on authorization for the Executive Director the execute the Easement Agreement with Millennium.

The subsequent confidentiality agreement is looking a lot like Quid-Pro-Quo.

Maria Ayerda, the Executive Director of the TJPA, was hand picked by Willie Brown and given an office at the San Francisco Municipal Transit Authority, prior to the creation of the TJPA.

Silly me, it all makes sense now.

RE: SF Tower settlement Part II

Yes, but what will happen to the tops of the existing concrete piles if the building tilts that much. Oh, they are made of spaghetti?

RE: SF Tower settlement Part II

'could'? what happens if it can't? I have no idea of what secondary stresses develop in a brittle concrete structure with that sort of deformation... I hope the design is as robust as the foundation.

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

-Dik

RE: SF Tower settlement Part II

So, I watched the entire Board of Supervisors Committee meeting online yesterday out of morbid curiosity and interest...and, I was quite surprised by some of the very honest statements that Hamburger made, including alleging the original geotech made a mistake in their calculations when originally estimating the potential consolidation settlement of the Old Bay Clay (which anyone who has any geotechnical knowledge already well knew, but that was never admitted publicly...). He also clearly stated that dewatering of "adjacent sites" (plural) contributed to increased settlement as result of increasing effective stress with loss of buoyancy. Sites, not just the one prominent and publicly-funded project site that the Millenium HOA has pointed their fingers at all along...I have always wondered about the effects of dewatering for the buildings to the north and west of Millenium that was ongoing during time of increased rate of settlement, yet that never seems to be discussed in any of the news stories or any of the documents I can find online.

RE: SF Tower settlement Part II

Towards the end of the video, there's a drawing showing how the current attempt to right the building is supposed to work (at around 9:30). It includes adding an additional piece of concrete under the sidewalk, and keying that piece to the existing foundation, and then lifting both with hydraulic jacks.

My problem is with the design of the key. The "upper lifting surface", because it is angled, would appear to cam the new additional concrete away from the foundation. This would increasingly lessen engagement, and lower the effectiveness of the concept.

Or so it appears to me.


spsalso

RE: SF Tower settlement Part II

I noticed that too, but I assume that Grady's illustration is simplified and not based on any drawings.

RE: SF Tower settlement Part II

"simplified"?


Not the word that comes to my mind.


spsalso

RE: SF Tower settlement Part II

The direction of the keyway is incorrect in the sketch.

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

-Dik

RE: SF Tower settlement Part II

Grady has it consistent with SG&H:

PRACTICAL ENGINEERING schematic:



SG&H detail:

RE: SF Tower settlement Part II

I have no idea of what they want the keyway for, but if they are uplifting, the keyway is in the wrong direction. Maybe part of the problem is that they don't know what they are doing.

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

-Dik

RE: SF Tower settlement Part II

I think the upwards slope of the keyway allows for better filling without voids.

RE: SF Tower settlement Part II

With properly consolidated concrete this would not be an issue... even a slope of 5deg would suffice if they needed one. A slope of 45deg is way too much.

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

-Dik

RE: SF Tower settlement Part II

Drill/core on a sloped concrete surface will be difficult.

RE: SF Tower settlement Part II

Having the key cut at an angle like that increases the cross section area of the rod in the shear plane.

RE: SF Tower settlement Part II

The "keyway" is there to also expose the original bottom rebar mat and mechanically couple to new added rebar.

Whilst the moment component of the uplift reaction (a horizontal force at the keyway location) tends to 'open' up the joint, the key does provide reaction for the vertical component via bearing.

What alternative direction/location would you make the key, dik?

RE: SF Tower settlement Part II

I agree with Ingenuity, the keyway is not meant to transfer shear at all, it is there to allow them to tie into the existing reinforcement.

RE: SF Tower settlement Part II

You can still achieve that without the excessive slope without causing a significant 'wedging' action.

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

-Dik

RE: SF Tower settlement Part II

As the slope of the keyway allows the new section of concrete to pull away horizontally, that will then tension the new horizontal rebar.

Seems maybe clever. Sure hope the concept has been thoroughly tested before this building--not really a good time for an experiment.



spsalso

RE: SF Tower settlement Part II

OK, I'm maybe corrected. I still don't think there's any reason to pretension the steel, and it just adds to the connecting force caused the the cantilever jacking.

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

-Dik

RE: SF Tower settlement Part II

Just a dumb question from a mere mechanical: Those perimeter piles are very long and relatively thin going through a deep layer of clay, which has "give" to it. The piles will be loaded heavily in compression to lift then support the corner of the building.

Is not buckling a concern? Does the lower layer of clay give enough lateral support to prevent this?

Seems the whole problem is the clay "oozing out" laterally from underneath a very heavy load. So the stuff does move. Worry that the pile once loaded will deflect laterally mid span.

RE: SF Tower settlement Part II

Buckling of the new piles is definitely a design concern. According to the video posted above (here is the clip: https://youtu.be/ph9O9yJoeZY?t=544), the piles are actually being kept from contacting the clay at all, so I would think the design is assuming the full height of the pile is unbraced. That is, they are not counting on the old bay mud to brace the new piles.

RE: SF Tower settlement Part II

I'm pretty sure they would consider that. One advantage is that the passive continuous force required to maintain stability is really quite small.

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

-Dik

RE: SF Tower settlement Part II

No, dauwerda, they are in a 36-inch casing for about 100 feet, then in Old Bay Clay for another 100 feet, then sands and gravels of the Lower Alameda formation for about 50 feet, then a "rock socket" into Franciscan melange. So, initially like 200 feet unsupported but then the 24-inch pipe piles rest against the bottom of the 36-inch casing, having squashed the soft stuff they inject in between the 24's and the 36's. Seems a bit iffy to me, but I am just a dumb dirt engineer.

RE: SF Tower settlement Part II

I have not reviewed any technical documents, I just watched the video that I mentioned.
It (the video) states that the holes will be overdrilled so that no part of the new piles will come into contact with the old bay clay. I take this as the oversized casing (36"?) will be installed all the way down to bedrock. The pile itself will fit inside the casing (24"?) and be socketed into the bedrock. The video then states that the annular space will be filled with low strength material - after jacking. This is to ensure no weight is transferred to the clay incidentally through skin friction. If the jacking is happening prior to filling the annular space the pile must be designed for the unsupported length extending from the bedrock to the top of the pile. Are you saying this is not the case?

RE: SF Tower settlement Part II

Quote (I'm pretty sure they would consider that.)


The way this has gone, so far, maybe I'm not too confident of that statement...

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

-Dik

RE: SF Tower settlement Part II

My recollection from the EDRT comment log, is that they will be using an Anti-Friction coating on the lower 24 inch casings, passing through the OBC.

I still don't know how they intend to adjust the tilt with these piles threading through an annulus of about 1/2 inch. If you start at the southwest end of the tower and move to the northwest corner, with incrementally more lift to the northwest corner than to the southwest piles; then skew within the annulus between the pile and the foundation extension is inevitable.



PRACTICAL ENGINEERING used the erroneous 11+ ksf. It is actually 14.8 ksf.

The SFDBI monitoring reports don't look encouraging. The settlement after the 'test' pile looks very much like the settlement leading up to the decision that brought on the perimeter pile work stoppage.

They aren't monitoring the 3 foot cantilever mat, which has hinged from cracking at the re-entrant corner of the 3 foot to 10 foot mats at all. Nor are they monitoring the settlement markers just north of the 3 foot mat. That is just burying your head in the sand where real seismic structural damage is high. This is cracking traveling in the 10 foot mat.

Hamjohn - I've looked at that google maps image before. I don't know what they are doing but there are a number of building services at that location, including sewer, water, fire and possibly electrical.

RE: SF Tower settlement Part II

epoxybot PRACTICAL ENGINEERING did not get some of the details correct but his 11+ ksf turns out to be correct once you subtract the weight of the excavated soil (25 feet under the perimeter mat and 40 feet under the core) from the weight of the building. This is the correct way to get to 11+ kips, not Hamburger's assuming the pile supported mat and core are 100 x 200 feet, which they are not! I have a friend who asked him about that and, extraordinarily, he defended his calculation by including and perhaps exaggerating the length of the 3-foot cantilever slab. I conclude that he does not understand basic geotechnical engineering, which we have long suspected.

But you are correct about the anti-friction coating on the 24's. What that does to the lateral capacity I don't know for sure, but I guess it reduces what little lateral support is provided by the OBC!

dauwerda PRACTICAL ENGINEERING did a nice presentation for laypeople but it comes up short on some technical issues. The 36-inch casings definitely do not go to rock - they go only to the top of the OBC.

RE: SF Tower settlement Part II

epoxybot one more thing. I like your cross-section of the 24's going through the mat extension but, while the design team has sometimes talked about "lifting" the NW corner, there is no way that the jacks are going the actually lift the building. The jacks are just to transfer load rather than to cause any movements. If anything moves it will be the 24-inch piles compressing and buckling rather than the building lifting. They have talked about the load transfer relieving the pressure on the OBC which, over time, might cause some rebound, which would lift the sand layer, the existing forest of concrete piles, the mat and the mat extension, which would cause relative movement of the 24's and the mat extension, but I don't know if that will actually happen. What will happen is that the south and east sides of the building will continue to settle. At what point that locks the 24's into the mat extension I don't know. One other thing, someone I know who talks to Jaxon van Derbeken at NBC Bay Area told me that Jaxon would like to talk to you. Not I think on camera but just because you have a lot of good information. Up to you whether you contact him or not.

RE: SF Tower settlement Part II

RE: SF Tower settlement Part II

Well.

hamjohn has posted a screenshot that says that "...Downtown San Francisco [is]Sinking Slowly Around Millennium Tower".

Wow!

According to hamjohn, the ONLY thing not sinking is our very own Millennium Towers. Else, why would he/she post it?


It looks as though Millennium Tower only needs a slight directional correction to be the last building standing, as Downtown slowly slips into the mud.

Splook!

spsalso

RE: SF Tower settlement Part II

Downtown sinking slowly < Millennium Towers sinking fast.

RE: SF Tower settlement Part II

from NBC news:

https://www.nbcbayarea.com/investigations/sf-mille...

"Newly released monitoring data shows that San Francisco’s Millennium Tower tilted a quarter inch during the four days it took to install the first test pile to bedrock last month.

The monitoring data tracks settlement, tilting and water pressure levels underneath the sinking and leaning structure since work began on a fix for the troubled tower in May. Since work began to shore the sinking structure up on the north and west sides, the building has settled nearly 2 inches at the northwest corner and is now tilting more than two feet at that edge."

Maybe time to move on to 'Part III'...

thread815-490007: SF Tower settlement Part III

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

-Dik

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