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SF Tower settlement Part III
18

SF Tower settlement Part III

RE: SF Tower settlement Part III

(OP)
From that article:

"Seven days after that memo, fix designer Ron Hamburger notified city officials – in a Nov. 30 letter – that “settlement monitoring indicates that no additional settlement or tilting occurred as a result of this 24-inch pilot installation.” He notified the city that the Dan Brown firm would no longer be present during upcoming testing. Although acknowledging that amounted to an exception to the agreed-to provisions of the testing program, Hamburger said the city’s own appointed design review panel “does not believe this is necessary.”"

I don't know what was agreed to, but oversight for any remedy should be in place. SF politics at play?

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 III

The Expert Design Review Team suffers from the same coziness that Millennium Tower's Consultant, UBC Prof. Jack Moehle & Peer Reviewer Hardip Pannu afforded SFDBI.

RE: SF Tower settlement Part III

(OP)
I suspect that they will monitor the tilt, very closely... no more than 1/2", you say...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 III

Now I realize I'm only using arithmetic, instead of some higher math. So you guys should like maybe do some sort of analysis on the following:

How to put it?

52 / 18 = 2.8888...

We'll call that 2.9, to continue to avoid the higher math. That would appear to be the new supported weight per pile, compared to the old (52) quantity.

If the Old Piles could hold up 800,000 pounds each, then my calculations:

2.9 X 800,000 = 2.32 million pounds.

The amount the New Piles would have to hold up. Individually.

Correct me if I'm missing something, but isn't 2.32 (million) a whole lot bigger than the 1 (million) that is mentioned?


Perhaps they're going to lighten the building? Maybe restrict the number of pianos in each unit?

Or looked at another way: if the old piles were needed to hold up 52 X 800,000 pounds, then their total uppicity would be 41.6 million pounds. The new proposed piles can each hold up 1 million pounds. That's 18 million pounds.

41.6 - 18 = 23.6 million pounds to be held up with something yet to be described. Luck? Hot air? A hot air balloon?


spsalso


"The required construction is neither complex nor unusual." Ron Hamburger

RE: SF Tower settlement Part III

(OP)
I don't have a whole lot of confidence in what they are doing. It's far beyond me geotechnically, and I have no idea of how to address the seismic issues.

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 III

SF Business Times: "Less is more: Engineers behind Millennium Tower fix have a new strategy"

New calculations show piles can bear more weight than was previously known — an estimated 1 million pounds, per Hamburger’s letter, up from 800,000. Crews will be able to accomplish the objectives of the previously planned retrofit with the reduced number of piles, Hamburger wrote, though he noted that the building’s tilt would not be corrected as much as had been previously predicted.

There are new photos on http://lbkarp.com - The 3rd to last photo shows a center bar in the pile much larger in diameter than the #18 high strength threaded bar previously proposed.

The Dan Brown & Associates letter from 23 November 2021 is also at lbkarp.com.

SG&H was the waterproofing consultant for the Millennium Tower project and the cracking in the bottom levels of the parking garage, immediately adjacent to the tower/podium shoring wall, will likely remain a chronic problem for the Millennium HOA. I'm quite certain the main water leakage/cracking is in the north & west walls of the lower parking levels. The parking garage walls incorporated an integral waterproofing admixture.

The tower/podium shoring wall in this area has two sections where the CDSM shoring wall has soldier piles at 2.5 ft OC. This location was troublesome early in the project, with water seeping into the excavation while the tie-back work was going on.

Beginning in Nov-2006 Surveyor, Martin M. Ron Assoc. began monitoring the Trestle erected to facilitate excavation of the Podium/Mid-Rise. From Nov-2006 to Jun-2007(time letter was written) they recorded continuing uplift of the trestle of 1-7/8 to 2-1/4 inches across the trestle.

I'm not sure how much basal heave is acceptable but the construction scheme of tying the tower to the shoring wall certainly complicates things. Then there is the uplift of the Mid-Rise on the corner of Mission St. & Beale St., as shown in an NBC image from late 2016. The uplift of the Mid-Rise was just noticeable in Apr 2011 (Google StreetView) and continues slowly over time. It currently looks to be about where it was in 2016.



The tower and the shoring wall are just a large shovel.

RE: SF Tower settlement Part III

If, as it seems to be the case from that photograph, the building is pushing up other structures at one side, it is not so much settling due to accelerated compaction and dewatering of the OBC, as rotating by mobilising the OBC. To my non-local eye words like settlement paint an altogether passive picture of what is going on.

RE: SF Tower settlement Part III

(OP)
Is there any recent news about the amount of settlement or tilt? Curious mimes want to know.

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 III

(OP)
Neat skyhook...

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 III

23.6 million pound of uplift needed.

Uplift per balloon: .03 lbs

That ole arithmetic again:


23.6 million lbs (extra lift needed) / .03 lbs (upness per balloon) = 787 million balloons.


I LIKE it!!

This will make Hamburger not only the most famous structural/aeronautical engineer ever, but also establish him as a world class artist. And a very very cool guy.

It's almost too bad this building wasn't built in Buffalo: Billion Balloons over Buffalo


Wow!


spsalso

RE: SF Tower settlement Part III

(OP)
I'm not quite as impressed, yet.

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 III

Quote (expoybot)

There are new photos on http://lbkarp.com - The 3rd to last photo shows a center bar in the pile much larger in diameter than the #18 high strength threaded bar previously proposed.

It appears from the other pictures the bar is also being used as the tremie to place the concrete, indicating it is hollow. A few pics from the website show a concrete pump hose running up the bar that is only present when the bar is being placed. I wonder if it has an equivalent cross sectional area to a #18

RE: SF Tower settlement Part III

(OP)
Interesting, Karp refers to it as a debacle... wonder why? 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 III

This ENR article finally popped-up on Google/News "Engineer Proposes Slashing Scope of Millennium Tower Pile Upgrade"

It links to a letter to the HOA and also to SFDBI. The SFDBI letter confirms that the center bar is hollow and used for tremie placement of grout.

There is a layout of piles in various states of completion, as of August 21, 2021. I believe 3 more 24 inch piles have been done since. SG&H are suggesting 18 total piles but it could be 24 piles, depending on the EDRT.

The intial design of the piles called for a #18 center bar. Checking the EDRT Comment Log, the center bar was increased to 3 inches. No doubt hollow. The bar in the LB Karp photo, to my eye, looks larger than 3 inches.

RE: SF Tower settlement Part III

Yes, in the production piles the center bar is hollow and is used to tremie the grout in. I think in the "indicator piles" it was a solid bar and the grout was tremied in in a separate grout pipe. The hollow bar is described in the Structures Magazine article.

RE: SF Tower settlement Part III

(OP)

Quote (center bar is hollow and used for tremie placement of grout.)


Tremmie, or pressure grout?

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 III

Dik - the Structure Magazine article: says "with a single, central 103 mm hollow, high strength, coarse thread reinforcing bar, which also serves as a tremie", but I guess they pump the grout into it.

RE: SF Tower settlement Part III

It says that they had to modified their pile installation procedure. What did they modify?


RE: SF Tower settlement Part III

Not sure what you are referring to RFreund. In the recent test piles and casings, not much. Mostly just more careful monitoring of plug depth in the casings and water and air pressures for the piles. Back at the time of the indicator piles, the first 24-inch pile did not carry the casing down into the Franciscan when they drilled the socket, and the socket did not hold when they tried to do a pullout test. So, they did a second indicator pile carrying the casing down into the socket and then withdrawing it as they tremied the grout in. I assumed that they stopped withdrawing the casings around the top of the Franciscan but recently I read somewhere that they pulled them up to 20 feet above the top of the Franciscan - not sure about this. As discussed above, for the production piles the grout is pumped down a hollow central rod. In the two indicator piles the central bar was solid and had Osterberg-type load cells inserted in it and the grout was pumped down a separate tremie pipe.

RE: SF Tower settlement Part III

(OP)
thanks... still not sure.

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 III

(OP)
Thanks for the link epoxybot... looks like half a day's read for this weekend. I thought the info at the comment below was interesting and I thought the coclusion was a bit weak.

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 III

Dik, were you referring to Tim Redmond's conclusion being a bit weak? I assume so. I think that in his third last little paragraph he mixes up Dr. Pyke's position with Mr. Hamburger's. I don't believe that Pyke has opined on what tilt might be acceptable, although I don't know what he said to Redmond. And even Hamburger has said no problem in earthquakes up to a total tilt of 48 inches, not more tilt of 48 inches. And I think he acknowledges that other problems with elevators and plumbing might arise if the tilt exceeds 30 inches. I might add that I am not sure that anyone can calculate what tilt might be acceptable in a major earthquake with any accuracy.

RE: SF Tower settlement Part III

(OP)
To the article by Robert Pike.

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 III

(OP)
Not being up to snuff with geotechnical and seismic, as an outsider, it appears to be a bit of a 'dog and pony show'.

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 III

Dik, maybe, but I think Pyke's stuff was put together more for DBI and the EDRT rather than for the Supes.

RE: SF Tower settlement Part III

(OP)
dunno, but it does make a little sense.

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 III

Quote (Walnut)

Not sure what you are referring to RFreund. In the...

Sorry, I should have been more specific. As I understand they started to install the "repair piles" down to rock. However, this accelerated the settlement so they stopped. The articles that I was reading said they then "modified the installation method". I'm curious to know what about the original method caused the accelerated settlement or what they changed to avoid this in the piles they are currently installing.


RE: SF Tower settlement Part III

RFreund well that's a long and incomplete story! But the short answer is that I think the basic problem with installing the 24-inch piles is that they are using a rock bit. Fine for drilling into the Franciscan but not so good for drilling through soils. This really only came to light due to the monitoring report written by Ben Turner of Dan Brown & Associates, which I am guessing is why he was sent home! Some excerpts:

During drilling, air pressure varied from approximately 190 psi to 220 psi, water pressure varied from approximately 200 psi to 240 psi, and the water flow rate was approximately 20 gpm.

During each of these stops, the operator lifted the drill approximately 1 ft off the base of the excavation (i.e., by withdrawing the drill string up into the 24-in casing) and air continued to be circulated through the face of the tool and up the return line at approximately 200 psi. It is necessary to keep circulating air through the drill in order to continue flushing remaining spoils up and out of the return line; if the air pressure were to be abruptly stopped, the spoils would fall out of suspension and could cause clogging of the drill upon restarting. This is notable because of the potential for the drill to unintentionally “mine” soil during these intervals when air is circulating but downward drilling progress is not occurring. The greatest potential for unintentional mining would be in clean sand layers such as were encountered near the base of the Alameda Formation.

The pour log indicates that partway through pouring from the fourth grout truck, while the 24-in casing was being lifted such that the casing tip passed through the depth interval of approximately 260 ft to 256 ft below the top of guide wall, the grout level dropped from 19 ft to 37 ft below the top of guide wall. As grout pumping continued and the casing was withdrawn to the final tip depth of 243 ft, the grout level continued to drop to a low point of 67 ft below the top of guide wall before beginning to rise again. In total, the grout level dropped 48 ft over a period of about 30 minutes, corresponding to about 5 yd3 of grout loss plus the additional volume that was pumped during this time.

Note that the air and water pressures used to lift the cuttings are like 7 atmospheres! They did make a change to the device in the drill bit that cuts a slightly larger hole than the nominal diameter of the drill bit, but I doubt that made much difference. The biggest change was that Center Rock, the supplier of the drill bits and DBA were more carefully monitoring the pressures and so on. That didn't make much difference either.

During the actual installation of the piles there was a quite dramatic drop in the pore pressures in the Old Bay Clay. It is not very clear, at least to me, what this results from. Does the high-pressure reverse circulation have the effect of "sucking" water out of the clay, or is it just overmining creates a cavity into which water can flow? This drop in pore pressures and increase in effective stresses is then rather quickly reversed but some permanent settlement should result from that cycle of loading, in addition to settlement that results from overmining. For some unknown reason there has typically been a delay of several days before grouting, so that does not help. I believe that Jaxon van Derbeken is chasing down that story.

RE: SF Tower settlement Part III

Wow, I had no idea they were using a down the hole hammer for the entire depth of the pile. Even with casing that is unusual to me for such soft soils. I would have through a bit more consideration would have gone into the installation procedures because of the high profile and cost of the project. I would have proposed a continuous casing (temporary or permanent) with a standard soil auger to rock before using the DTH bit. It would be more costly, but not as expensive as repairing a repair.

RE: SF Tower settlement Part III

Milliontown, yes, I would also have thought that more thought would have gone into the perimeter pile installation before they started, especially since the building already had a settlement problem.

RE: SF Tower settlement Part III

@Walnut - thanks for the explanation. It seemed like most articles just say "there was more settlement during repairs, so they modified the installation procedure" and moved on, but never actually talked about why there was more settlement or what they did to correct this.


RE: SF Tower settlement Part III

(OP)
It surprised me that they could be dismissed, so easily.

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 III

(OP)
In the event the tower takes on a real serious tilt, who cleans up the mess and who pays for it? The condominium owners? As an added expense, should San Francisco have them put together a fund to 'clean up'?

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 III

(OP)
From the news?
"A ritzy San Francisco condo tower is now leaning 26 inches and is expected to tilt by a further three inches annually after work to stabilize it ended up worsening the issue.

Just months earlier, the Millennium Tower - a high-end condo tower that opened in the earthquake-prone city in 2009 and sold units for millions of dollars - was only leaning 22 inches.

However, the 58-story, 645-foot tall building is now leaning 26 inches after stabilization work to help stop the sinking was halted because the removal of earth to add stabilizing piles was worsening its slant."

https://www.dailymail.co.uk/news/article-10384831/...

At what point does this become serious? 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 III

Probably about 5 years ago, I think,

RE: SF Tower settlement Part III

(OP)
hokie... you missed the 'happyface'. 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 III

"...there is no cause for alarm..."

Emily Guglielmo, former President of the Structural Engineers Association of Northern California

Though, to be fair, she may have modified her views since making this statement on September 9 of last year.



spsalso

RE: SF Tower settlement Part III

NBC: Leaning San Francisco skyscraper is tilting 3 inches per year as engineers rush to implement fix

Excerpt: In a Thursday letter to the Millennium Tower Association, the San Francisco Department of Building Inspection said it had approved the new 18-pile plan, writing that it is "satisfied that the associated settlement and tilt remain within safe ranges and support [Hamburger's] proposal to continue the retrofit using the modified installation procedures."

SFDBI Permit Services - Deputy Director III, Neville Pereira, stated in the Govt Audit & Oversight Committee Hearing, that same day, that they were WEEKS from completing a review of the revised 18 pile solution. Starting at 3:17:00 in the Govt Audit & Oversight Committee Hearing video.

RE: SF Tower settlement Part III

That was by some national NBC correspondent, I think, rather than Jaxon van Derbeken of NBC Bay Area. I haven't seen the letter, but I am guessing that DBI has allowed them to continue under the existing permit to install more piles. That is what was said in the meeting. I understand that hamburger is speaking at a meeting of the Homeowners' Association this evening. I wonder whether they will throw eggs at him?

RE: SF Tower settlement Part III

(OP)
I just listened to the review meeting. Pike's comments were alarming, and he came across as a bit of an alarmist. This needs clarification. He may be correct and there should be a real concern and there is a real reason for being an alarmist. I cannot imagine a 600' building 'falling over'. If his concerns are real, the committee was pretty dismissive of his presentation and I would have thought that they would have delved into his comments, at least a little bit. Sounds like politics at play.

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 III

Leaning San Francisco skyscraper is tilting 3 inches per year as engineers rush to implement fix
IS NOT TRUE.

LINK TO AN OFFICAL PLOT TELLS A DIFFERENT STORY.
https://sfdbi.org/sites/default/files/20211027%20M...

FIGURE 026-05 SHOWS:

FIVE YEARS FROM 2006 TO 2010, ZERO TILT WAS RECORDED TOWARD THE WEST, AND FOUR INCH TILT WAS RECORDED TO THE NORTH. ELEVEN YEARS LATER, NOW THE TILT IS 24 INCHES TO THE WEST AND 9 INCHES TO THE NORTH. DOES THIS MAKE SENSE?

SEVEN YEARS FROM 2011 TO 2018, THE TILT WAS 14-INCH TO THE WEST. 2013 AND 2015 WERE THE ONLY TWO YEARS THAT THE TILT WAS APPROCIMATELY THREE INCHES.

THREE YEARS FROM 2018 TO 2020, THE TILT TO THE WEST HAS BEEN REDUCED TO APPROXIMATELY TWO INCHES. IS THIS THE REASON MR. HAMBURGER CONCLUDED STRUCTURAL UPGRADE OF THE BUILDING IS NOT NEEDED?

DURING THE FIX FROM 11/2020 TO 8/2021, THE TILT TOWARD THE WEST INCREASED BY SIX INCHES.

RE: SF Tower settlement Part III

It looks like NBC has updated their story to clarify that the 18 Pile ~Solution~ is scheduled for completion of SFDBI/EDRT review by February 28th.

One thing I think noteworthy of last Thursday's Govt. Audit & Oversight Committee meeting was how Stanford Prof. Gregory Deierlein danced around the 'Cracked Foundation" question. It looked to me like he checked himself, during his response. The notion that the EDRT doesn't want to bring into discussion the hinged 3 foot cantilever slab, at the south end of the tower, to members of the SF Board of Supervisors is troubling.

While he is right about cracks in the bottom of the mat being in an anaerobic environment and thus slow to develop corrosion, the current monitoring regime does not include elevation changes to the 3 foot cantilever slab. Prof. Deierlein suggesting everything looked fine back in mid-2017 doesn't really inspire confidence. The crack could literally be a hairline at the base of the southern SMRFs. Ron Hamburger danced around the cracked foundation as well. You don't find cracks by coring, not without field input.

RE: SF Tower settlement Part III

epoxybot, the bottom of the mat is now likely below the groundwater but when the test micropile perforations were drilled through it, I am told that it was dry because, even though the alleged dewatering by neighbors was minor, there was some and at that point it had not recovered. Corrosion products will not be swept away like they can be from steel pilings under a bridge with a fast current flowing under it, but I wouldn't completely discount the possibility of corrosion.

RE: SF Tower settlement Part III

"Bring dynamite and a crane
Blow it up, start all over again."
Nashville Teens, 1964

RE: SF Tower settlement Part III

(OP)

Quote (Stanford Prof. Gregory Deierlein danced around the 'Cracked Foundation" question.)


I thought he was going to step into something... but, he evaded it quite nicely. No one wants to talk about the cracks on the bottom; you cannot see them anyway. Some of the photos show, what I would consider, as significant cracking.

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 III

This pile fix seems to assume that the new parameter piles will take up their "share" of the load. I wounder if anyone has attempted to figure out how the loads will actually transfer?
Important considerations
  • Spring rate of each pile.
  • Flexibility of the foundation mat.
  • Load transfer (sideways) in the building support system.
Considering the loads tend to transfer to the stiffer supports, what keeps the loads in the new perimeter piles below their design load limit?
Is there anything from preventing this load transfer from accelerating the cracking of the foundation mat?

The Leaning Tower of Soma is a mess—but everyone’s ducking responsibility

Is the cure worse than the disease? Will the building keep tilting and sinking? Can it survive an earthquake? Answers do not inspire confidence

By Tim Redmond; January 6, 2022


RE: SF Tower settlement Part III

(OP)
If the building 'falls over' are the tenants (ie, condo owners) responsible for the costs of repair for damage, in addition to the loss of value for the condo units. Are the condo units a multi-million dollar liability?

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 III

I suppose the answer to that would inform current remedial actions as well as future maintenance. Right now someone is footing the bill out of fear of certain liabilities.

(That's the easiest answer I can come up with:)

RE: SF Tower settlement Part III

A recent Building Integrity video discussed who owned what in a condo. Individuals own inside their condo. The condo association owns the structure. So it would seem the condo association would be responsible if the building fell over. So it's up to them to make those damaged whole. Of course, they may well say it was actually someone else's fault the building fell. Now we get into multiple lawsuit/defendant land.

But, pretty much, if it's your "thing" and it causes damage, you get to pay:

Your house catches fire, and burns down the neighbor's house, it's YOU (or your insurance).
The brakes fail on your parked car, and it crashes into a bus, it's YOU.
An electric space heater you own or have control over destroys much of a building and perhaps kills some people, it's YOU. Again, YOU can try to transfer the blame to someone else, but first it's on YOU.

I'll just mention "act of god" here, but since the building's been tilting for years, that ain't gonna fly.


spsalso

RE: SF Tower settlement Part III

Walnuts: I agree that the anaerobic conditions would not suffocate the corrosion process, just slow it down. How much is debatable. Since the TJPA characterized groundwater in the area as brackish, an electrolyte solution is present to feed the reaction.

Dik: The legal settlement pretty much puts the Homeowners at future risk, if the tower were to collapse. It would definitely damage Salesforce Tower across Fremont St. I hate to think what it would do to 350 Mission Street, with its 50 foot tall lobby.

After the 36 inch casings were drilled, were they backfilled or are they just sitting in the ground open? It looks like the drilling of the 36 inch casings was done from the surface down through the tower shoring wall. I can't help but wonder how that might contribute to the current settlement issues.

Perhaps the reason the large PG&E vault at the south end of the foundation is not part of any Environmental Impact Report is because San Francisco excludes an "Existing/Replacement" utility from CEQA. This is only suppose to apply when there aren't any Special Conditions. I would think the Seismic Security of the PG&E vault would predicate it being part of any CEQA for Millennium Tower New Build or Remedial work. This is SF Planning doing their usual dirty work.

When in 2005, Mission Street Development submitted their plans for review by the TJPA, a PG&E vault was mentioned as a concern, relative to future Train Box excavation. I fail to see how a Hinged 3 Ft. Cantilever Slab supporting the "Replacement" utility vault, escapes Environmental Review or a separate seismic safety review by the City, the Developer, the HOA, etc.

RE: SF Tower settlement Part III

epoxybot, I believe the 36-inch casings have been left more or less open, filled only by the final plug and then whatever sediment has fallen out of the column of water inside the casing. That might be quite considerable. For one of the 24-inch pile installations that Ben Turner of DBA reported on, there was quite a large depth of sediment on top of the plug. I wanna say 16 feet but I would have to dig to confirm that number. I don't know what shoring might have been left in place, but I assume they are outside of that. But all the casings were inserted through holes that had been left in what I think they call the "guide beam", a new concrete box that runs all the way along both Fremont and Mission Streets that has the locations of all the planned casings pre-marked in it. I read somewhere that that was done partly to make sure that the casings went in at exactly the right locations and also to minimize downdrag on the existing basement walls. I don't know what happens to the guide beam when they dig down to construct the mat extension (should they ever get to that point).

RE: SF Tower settlement Part III

(OP)
I was thinking that... and that the current owners may have a multi-million dollar liability on their hands, beyond the cost of ownership of their units.

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 III

I am not an expert.

In my opinion tilt is worse than sinking. Tilt will not only increase the pressure on one side of the footing but also increases secondary moments on structural members due to P-Delta effects.

What if they just balance the tilt by increasing pressure on the opposite side or something along this line.

This may increase the sinking. They may loose a story or two in this process, but sinking will probably stop,
Once the soil beneath gets compacted enough.

RE: SF Tower settlement Part III

To the Geotech's.

I have reviewed the drilling logs, and it seems that there is not a consistent nor stable strata that is capable of transferring a 2,000kip load via friction, and that most of the load will be a point load at a rather weak shale base. Can the shale (1) actually support a 4.4 kip sq in static load and (2) support the "live" load that occurs in the jacking processes?

This is way beyond any field condition that I have ever encountered, perhaps I'am just overwhelmed by the concept of the transfer of a 2,ooo kip load to a 24" pile.

In my experience a good Geotech/Civil Engineer is the vital key to building any large building.

RE: SF Tower settlement Part III

Keith 1, which boring logs did you review? I think the best and possibly the only reliable log is of boring PB-1 drilled by Slate near the two indicator pile locations on Fremont Street. It shows Franciscan Melange from 256 feet down to 323 feet. The melange is described by Slate as "generally consists of pervasively sheared shale matrix supporting blocks of siltstone, sandstone, chert, serpentinite, and volcanics; blocks vary from 1/2 to 3 inches; local serpentinite and quartz veins." There is no indication of even a rather weak shale base. The melange is known to be a tricky material that can vary quite widely over short distances. Not what I would want to support a 600-foot tall, concrete-framed building. Ron Hamburger, a structural engineer, keeps on referring to piles drilled into rock, but this is not what most geotechnical engineering would regard as rock for this purpose. It is instructive to see what Slate wrote about the first indicator pile, which they abandoned because they could not keep the hole open: "leaving the uncased rock socket hole open for any significant amount of time, as well as repeated extraction and re-insertion of the drilling tooling and flushing with water, seems to be detrimental to the stability of the hole [which should not have been a surprise!]. The Franciscan Complex bedrock materials are quite variable ..."

Thank you for your support of good geotechnical / civil engineering!

But also, the one and only "pile load test” was done on the second indicator pile which had three Osterberg load cells embedded in the rock socket plus other devices to measure deformation. They do some tricky stuff to come up with “unit side shear resistances”. That is all they report, but I added up the shear forces around a 2-foot diameter pile and got 663 kips in the Lower Alameda formation and 2060 kips in the Franciscan. These are not capacities of any kind – just what was developed when the load cells reached their limit of 800+ kips. So, if you believe this, you could safely apply 1000 kips as a permanent load. But I think there is something funny about these numbers. The loads cells, when tested one at a time maxed out pushing a bit over 800 kips in both directions, up and down, 1600 kips total. I am not sure how they then get interpreted resistances that add up to 2723 kips (not my expertise and I don't have time to read all the relevant literature). Also, the capacity for a downwards load might be different because of a different pattern of deformation and the long-term capacity of the Franciscan Melange might be different from the short-term capacity. Basically a lot of unknowns. To rely on just one pile load test and some input from adjacent sites (which John Egan mentioned in his remarks to the Board of Supes hearing) seems like more than a bit of a gamble for a high-profile fix and building.

RE: SF Tower settlement Part III

Thanks Walnut, that was a very informative post, and I greatly appreciate it.

I apologize for the use of the term "weak shale" as I lack the vocabulary or knowledge to properly characterize the substrate as you have correctly done so.

The logs that I saw were posted on this thread and consisted of site specific and local surveys that contained hammer #'s and soil characterizations, and to be honest the use a rotary drill left me with nothing more than a best guess, because I have only ever dealt with test results from bore holes taken with a spoon bill.

My observation was that the strata varied dramatically every 10' or so, and I did not see anything that offered much soil sheer strength to carry anything close to the applied loads via friction, and that the terminal strata was nothing like a granite or a 6,500 psi consolidated clay layer to carry the point loads at the socket.

The only thing that makes possible sense to me, and that would give them a fighting chance would be to bell the bottom out above the socket to distribute the load, but again I have never seen a pile that was loaded anything near what they are attempting.

Foundations, dewatering, sewer/water and storm water management are vital to construction, and in my opinion a good Geotech/Civil is the best investment you could ever make.

RE: SF Tower settlement Part III

With all the legal beagles looking at this, why would any engineer take on this project?

RE: SF Tower settlement Part III

Arrogance.

or

Money.

or

Got in early, and it's too late to get out.

or a combination of the above.



spsalso

RE: SF Tower settlement Part III

(OP)

Quote (With all the legal beagles looking at this, why would any engineer take on this project?)


I like challenges... but, this one is a little more than that. I still don't have a warm fuzzy feeling about any of the proposed solutions. You would think they would be getting the best, world wide, geotekkies 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 III

Quote (dik)

I like challenges... but, this one is a little more than that. I still don't have a warm fuzzy feeling about any of the proposed solutions. You would think they would be getting the best, world wide, geotekkies involved.
I agree, I don't really get any warm fuzzies about what they are doing. On the other hand, I'm not sure what else could be done short of tearing the building down. They really don't have a lot of room to work in while doing remediation and they've already shown that additional excavation just causes more problems.

RE: SF Tower settlement Part III

(OP)
That's why they have to quickly sit down and talk to all the experts... they may have time now, but maybe not in a couple of years... an old expression one of my colleagues that was a pilot used to say, "There's nothing more useless than runway behind you."

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 III

(OP)
One of the main tenets of professional associations (engineering ones, at least) is looking after the safety of the public. SEAOC is strangely quiet about this structure (with the exception of a past member). A seismic event, with the precarious foundatons, could kill or injure many. I don't know what it would take for the association to 'really' be interested in public safety? Maybe it a 'catch all' that all associations use to make themselves feel important.

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 III

If they're overloading the capacity of that clay and sand to support the building then the only safe options are to reduce the load (i.e. remove some of the building) or get the piles down to bedrock. And then because that's so far down, you have to worry about bending of the piles too. So yeah they look to be in some serious trouble to me.

RE: SF Tower settlement Part III

Maybe, instead of driving piles on the shady side of the building, they should be pumping water out from under the other side.

Let the building sink, but keep it vertical. Then there'll be some new basement apartments that will rent out at a substantial discount. Or maybe just an extra parking floor or two. But most of the owners will just have a slightly less wonderful view.

Otherwise, the buildings got to come down. One way or another.



spsalso

RE: SF Tower settlement Part III

Another great video released by Josh Porter, just two days ago:

Link


And I am REALLY looking forward to the next one!



spsalso

RE: SF Tower settlement Part III

epoxybot - Were you ever able to come across any foundation and basement plan sheets for the Millennium Tower you could share? Some of the older links in the original thread are dead.

RE: SF Tower settlement Part III

In Part II I asked:

Quote (hpaircraft)

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.

I wonder if the situation is grave enough for this yet?

One of the responses to my original query is that such contingency planning might be seen as an admission of failure. I think what it would be, an act of concern for public safety, is more important than what it would look like.

RE: SF Tower settlement Part III

(OP)
If the video by Josh Porter is correct, it's something they should be looking at predicated on the repair efforts to date. SEAOC is strangely silent.

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 III

(OP)
Is this the type of reduction for a group of piles (the reduction is approx 40%):

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 III

Dik - From the "Structural Evaluation of the Millennium Tower, 301 Mission Street, San Francisco, CA; Revised Supplemental Report" July 26, 2017

BEGIN Page 12: We used an in-house computer program to calculate a group factor for the piles based on the empirical method outlined in Reese6 et al. We obtained a group factor of 0.6 and assigned it to LPile as a modifier. END
6) Reese, LC., Isenhower, W.M., and Wang, S-T, Analysis and Design of Shallow and Deep Foundations,
Dec 2007

ti89t - The items that are now broken links can now mostly be found on LBKarp's Millennium Debacle page.
In addition there are the SF Gov. Audit & Oversight Committee "Communication Packets" that comprise everything SF Supervisor Aaron Peskin has requested be made public. File Destinations: 160975 & 210954
Apart from a plan view of the piling and an elevation view of the tower podium shoring wall, there aren't any structuaral drawings of the mat foundation or basement. There is a original floor plan of the basement in some of the documents linked above.

RE: SF Tower settlement Part III

(OP)

Quote (We obtained a group factor of 0.6)


It as a WAG, with fictitious numbers, just to get an inkling of the reduction... I've never done this type of calc before, but the 0.61 calculated is close to the 0.6. I wouldn't do this sort of design myself; I'd rely on a geotekkie. I just didn't realise that there could be that much of a difference... I was thinking maybe 80% or something of that ilk. It's just nice to know the sort of methodology that goes into this type of calc. Thanks, epoxy...


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 III

I recently talked with a local Geotech, he tells me the leaning tower on SF has been good for his business. It brings a real life example with real consequences to the construction industry,

RE: SF Tower settlement Part III

How many inches before the building becomes unstable?

RE: SF Tower settlement Part III

Strictly speaking, it is ALREADY unstable. And has been for years.

Perhaps:

Uninhabitable? Drains can't drain, elevators can't work, golf balls won't roll properly when putted......

Likely to fall over? Hmmmm...........



spsalso

RE: SF Tower settlement Part III

(OP)

Quote (golf balls won't roll properly when putted......)


Just adds a challenge. 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 III

So then a definite no for a billard club.

A black swan to a turkey is a white swan to the butcher.

RE: SF Tower settlement Part III

(OP)
another challenge?

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 III

How much of a lean can the building sustain before the lean compromises the structure?

Obviously it's designed to be upright, and perhaps a lean isn't calculated into the design. At what point does the structure have to be demolished and these patch fixes abandoned as pointless?

RE: SF Tower settlement Part III

I think it partly depends on the chance of the building continuing to lean more after it gets to this "magic moment".

It's one thing to KNOW the leaning has stopped, and you can count on it. It's another if the building goes right on by, like an RPO picking up a mail bag.

That said, there's been talk about the need to keep a minimum of 1/8" per foot slope for the plumbing drain piping, and something about the elevators.

spsalso

RE: SF Tower settlement Part III

I saw this video on the Structural Engineering subreddit and found it to be very interesting.

https://www.youtube.com/watch?v=R22WWyFpjS0

It is a building in Santos, Brazil that had a correction for a 0.5 degree tilt. The video is in Portuguese, but does a good job of capturing the majority of the engineering concepts utilized.

RE: SF Tower settlement Part III

I presume the Santos building had stopped leaning when they did the repair. If not, then it would have made more sense to leave the jacks in place.

Millennium has not stopped leaning.

The video is VERY interesting, and it does look like they pulled it off, though sometimes the placement of the jacks and/or shims looked a bit haphazard. To me.


spsalso

RE: SF Tower settlement Part III

The more it leans though the more pressure is being applied more to the footings on one side of the building though? Won't there be a point of no return in terms of the leaning will increase at this point and it won't be possible to stop?

RE: SF Tower settlement Part III

Well, we can start with the rock bottom (if only!!!!) theoretical base: the center of gravity of the building moves outside its footprint. Simplifying practically everything, when the sideways movement of the roof reaches 100 feet, over she goes. The building is at two feet now. It would undoubtedly do the tippy-dance sooner, though.

The point of "differential pressure" as it tips is certainly interesting. And I wonder how much that differential pressure will cause "stuff" to ooze out from the higher pressure side. Geo-guys and gals might likely have something to say about this sideways oozing of mud. Or whatever water filled stuff is holding this building up. Or not.

One plus about this building actually falling over is that it will take out what I consider an ugly blight on a skyline that I gaze upon regularly: The Salesforce Cucumber.

The current rate of lean increase westward is 3" per year. So we've got about 400 years before it tips over, if the rate stays the same, and if the "rock bottom" case holds. So it would thus appear that Ms. Guglielmo was correct in stating that there is "...no cause for alarm..." at this time. Perhaps later.

spsalso

RE: SF Tower settlement Part III

100 feet? No issue sooner?

RE: SF Tower settlement Part III

While the theoretical point of no return is 100 feet a bigger question is at what point are people not going to feel comfortable living in the building? I'm sure it's well before the 100 foot lean. I'm sure even the amount it's leaning right now would be disturbing to some people.

Also, the farther it tilts I would expect the rate of tilting to increase based on the heavier load of the footings on that side of the building. This obviously is based on simple physics.

RE: SF Tower settlement Part III

Aren't they already having issues with the lean affecting drains? I can't imagine that situation at a 100 ft lean.

RE: SF Tower settlement Part III

I "yelped" this building, and found some very interesting reviews.


spsalso

RE: SF Tower settlement Part III

(OP)
I trust the piles are moving with this and not shearing off...

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 III

If the piles have not sheared off, then the piles and the dirt around them (and under the slab) have also moved an inch. So where did the dirt go that was in that inch?


spsalso

RE: SF Tower settlement Part III

I feel validated about my observations about the the snapping curb on Fremont St. and the so-called aging sewer line. Seemingly all tower related. Even the SFDPW stated the sewer line lateral-to-sewer main, servicing Millennium Tower was at the correct elevation. Hence the City paid for a sewer replacement (Elevation Change) as a favor to the Tower.

RE: SF Tower settlement Part III

Can someone say how much the tilt in this building compare with how much the columns can be out of plum per the code allowance. From bot to top of building?

RE: SF Tower settlement Part III

I think the safe lean angle limit might be when the CG passes the KERN distance.

Quote (https://www.sciencedirect.com/science/article/abs/...)

The region within which axial loads may be applied to a compression member without inducing tension anywhere in the cross-section, commonly called the ‘kern’.
I think having the pilings on the high side of the building undergo tension would be very undesirable, but the building plumbing is sure to stop working before that point.

RE: SF Tower settlement Part III

Quote (Kevinsnn)

Can someone say how much the tilt in this building compare with how much the columns can be out of plum per the code allowance. From bot to top of building?
I don't believe I've ever seen anything in the codes about how much tilt allowable and obviously if there is something it would be stipulated in degrees of angle instead of distance because of the varying heights of buildings.

RE: SF Tower settlement Part III

(OP)
I think the kern is not a good guess... I suspect there will be many more problems with services before the kern is approached. I think the biggest issue, currently, is how the building will perform in a seismic event. Is it already compromised. This is most important and it seems that no one is addressing it. Could it be like climate change and no one is concerned about it; it's not going to happen.

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 III

A full seismic dynamic analysis to prove or disprove safety sounds like someones PHD Thesis. Hopefully failure of the building services will make the seismic issues moot before a "criteria event" occurs.
This leaning tower engineering stands in contrast to the following event.
William LeMessurier-The Fifty-Nine-Story Crisis: A Lesson in Professional Behavior

Quote (https://www.youtube.com/watch?v=um-7IlAdAtg)

National Academy of Engineering
William LeMessurier, one of the nation's most distinguished structural engineers, served as design and construction consultant on the innovative Citicorp headquarters tower, which was completed in 1977 in New York. The next year, after a college student studying the tower design had called him to point out a possible deficiency, LeMessurier discovered that the building was indeed structurally deficient. LeMessurier faced a complex and difficult problem of professional responsibility in which he had to alert a broad group of people to the structural deficiency and enlist their cooperation in repairing the deficiency before a hurricane brought the building down.
His story was recounted in detail in "The Fifty-Nine-Story Crisis," which appeared in the May 29, 1995 issue of The New Yorker, and on November 17, 1995, LeMessurier himself came to MIT, from which he received his doctorate, to speak to prospective engineers about the decisions he had to make and the actions he took.

RE: SF Tower settlement Part III

Mark R (Mechanical), i was asking how much columns are allowed to be built out of plumb per the building code
and how this compares with the tilt here.

RE: SF Tower settlement Part III

Quote (kevinsnn)

Mark R (Mechanical), i was asking how much columns are allowed to be built out of plumb per the building code and how this compares with the tilt here.
You are the structural engineer, is that in your ballpark? I'm only a lowly mechanical engineer and have to worry about pipe and steel etc. On a more serious note, I remember ever seeing a talent for how plumb a column have to be in any of the structural codes. Saying that, I don't deal with them that often so it probably there someplace.

RE: SF Tower settlement Part III

Why would it be required that columns be plumb? I can envision a structure with all columns 10 degrees out of plumb, but still can stand and support a load.


spsalso

RE: SF Tower settlement Part III

Quote (spsalso)

Why would it be required that columns be plumb? I can envision a structure with all columns 10 degrees out of plumb, but still can stand and support a load.

'cause it induces eccentricity, which magnifies the column moments due to the added displacement. For steel steel columns, for example, plumbness tolerance of 1/500 (0.12o) is typical, with some limitations.

Your 10o example is 1 in 5.7 !!!

RE: SF Tower settlement Part III

We have a slab. 20 feet up, we want another flat slab, to be a dance floor for performance, with a bar on one side serving the best martinis (gin only). The assignment is to hold that floor up securely, using columns tilted at 10 degrees. The secret code is that they're not all tilted in the same direction. But they ARE 10 degrees from vertical.

If columns were required to be vertical, this structure could not be built. And you and I could not quaff martinis while ogling the dancers.


spsalso

RE: SF Tower settlement Part III

You can design for most known and planned-for actions, but even your 10o tilting columns have a tolerance on the as-built construction. Ya' can't necessarily make them 15o and expect satisfactory performance.

Oh, and I don't drink...and are not 18 "ogling the dancers".

RE: SF Tower settlement Part III

(OP)
That's why you include the tolerance in some designs, in particular if they greater than intended. Whenever I'm dealing with HSS sections and ASTM A500C sections are spec'd, I immediately base the section properties based on the minimum values for size and wall thickness. My SMath programs do that if A500 is used.

As Ingenuity noted, you can have wild and wonderful support conditions, as long as you design for them.

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 III

(OP)

Quote (Oh, and I don't drink...and are not 18 "ogling the dancers)


Poor sod... that's how I got my job with RJC... I accidentaly met the Winnipeg manager at one of the local strip clubs... It's called networking. 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 III

ACI 117-10 Specification for Tolerances for Concrete Construction and Materials.
Deals with the allowable tolerances during construction.

BTW How can I change my discipline from CIVL/Environmental to Structural.

Thank you

RE: SF Tower settlement Part III

Engineering Failures & Disasters at Eng-Tips, the ultimate in doomscrolling.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

RE: SF Tower settlement Part III

So with a 1 in 500 out of plumb, this 650'building would be 16" off center
compared to 26" the building is tilted I believe. Do Bridges so out of plumb for buildings not used.

RE: SF Tower settlement Part III

ACI 117-10: "The maximum tolerance is 6 in. at heights more than 500 ft above the top of foundation of the structure."

Well. THAT SHIP HAS SAILED!

Of interest might be: was that dimension exceeded before the building department awarded a certificate of occupancy?

If you've been following the "tip-o-meter", which is the weekly report from the building department about building movement (linked quite a ways above), you'll notice that the rate of change is constant, with maybe a hint of increase.

These days, it's good to have something you can count on.

spsalso

"...no cause for alarm..." Emily Guglielmo, PE

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

RE: SF Tower settlement Part III

(OP)

Quote ("...no cause for alarm..." Emily Guglielmo, PE)


You don't need more than 640K...pipe

"When we set the upper limit of PC-DOS at 640K, we thought nobody would ever need that much memory. — William Gates, chairman of Microsoft" 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 III

Quote (EZBuilding)

I saw this video on the Structural Engineering subreddit and found it to be very interesting...

Here's an article that describes what's in the video. The video shows the straightening of Building B; the article describes the straightening of Building A, then Building B:

https://link.springer.com/article/10.1007/s41062-0...

RE: SF Tower settlement Part III

(OP)
spsalso: Can you post a link to the "tip-o-meter"; I couldn't find it. 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 III

(OP)

Quote (Here's an article that describes what's in the video.)


Millennium tower is 4x the height. Are those buildings in a seismic zone, by any chance?

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 III

@ hpaircraft

Thank you for sharing that - very informative and interesting

@dik

No seismic and low wind speeds throughout most of Brazil. I did not mean to imply that this process would be applicable for the Millenium Tower, but found it to be a really cool video with some relevance to the thread.

RE: SF Tower settlement Part III

link to the tip-o-meter:


Link



spsalso

RE: SF Tower settlement Part III

(OP)
Thanks spsalso...

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 III

With the latest results from the tip-o-meter, the slope seems to be curving downwards, and so I will have to change my prediction of absolute tip to 300 years, from 400 years.



spsalso


"...there is no cause for alarm..."

RE: SF Tower settlement Part III

The City of San Francisco has a Document Request Portal that has the latest SGH/Slate 18-Pile submittal. There are two versions, a 316 page "engineering" submittal and a 1374 page version prepared for Supervisor Aaron Peskin. It includes the engineering submittal, data regarding the installation of piles subsequent to the August halt in piling operations, due to settlement (see page 1067/1374). The document also contains, at the front, a mountain of emails between SFDBI, SGH, the EDRT and Dr. Pyke. You can go snow blind scrolling through the emails, which are provided repeatedly, 3 to 4 times! I think they do this on purpose.

316 Page Document

1374 Page Document

RE: SF Tower settlement Part III

(OP)
I just thought of a neat April Fools joke... get a bunch of demolition contractor to meet on the QT at the site to discuss upcoming demolition plans for the site... 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 III

Quote (spsalso)

With the latest results from the tip-o-meter, the slope seems to be curving downwards, and so I will have to change my prediction of absolute tip to 300 years, from 400 years.

That's good news, still well beyond the acceptance criterion of latest retirement date of implicated persons.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

RE: SF Tower settlement Part III

"Absolute tip", of course, is the "worst" case. It seems likely the building will actually tip earlier. I dearly hope I'm still alive to see it take out the Sales Force Tower--I'd hate to miss THAT!

It can be noted that the Most Implicated persons involved in Champlain Towers have all long retired. In perhaps ALL senses of the word. Lucky lads. Sorta.


This morning, I drove by the building going west on the freeway coming off of the Bay Bridge. I tried to see if I could visually detect it leaning. I thought I did, but I had to also pay attention to driving, and so was distracted a bit from this important task.


spsalso

RE: SF Tower settlement Part III

I was looking at some photos of an SGH inspection of the tower & podium last week and came across this gem. It is the southeast sloping SMRF. The main crack seems odd because it is open in the middle and closed on both ends. Is it a torsion crack? The image is taken looking to the south. This SMRF is about 4 feet from the edge of the hinged 3 ft. cantilever mat.







RE: SF Tower settlement Part III

That's certainly an interesting crack pattern and something it seems that the structural people would be very concerned about. Not sure what the cause of being but it sounds like your idea of being torsion is quite logical. It will begin to see if this is brought up again and is a subject of any further study.

RE: SF Tower settlement Part III

The crack(s) seem to be in a surface application of "somethin'", about a half inch thick, smeared over the concrete. Look towards the bottom of the beam, in the lower of the two photos. That SURELY isn't what's left after the forms are removed.

So maybe it's a shrinkage crack in the "somethin'". Or maybe there's an even bigger crack in the actual concrete hidden underneath.

Or there's nothing to see here--move along, please.



spsalso

RE: SF Tower settlement Part III

Quote (spsalso)

The crack(s) seem to be in a surface application of "somethin'", about a half inch thick, smeared over the concrete. Look towards the bottom of the beam, in the lower of the two photos. That SURELY isn't what's left after the forms are removed.

No, that is off-form concrete finish. The 'dags' you see at the bottom are where concrete slurry leaked behind the chamfer strip and was not removed after the forms were taken off.

RE: SF Tower settlement Part III

(OP)
I would have thought the SMRFs would be located on the same plane, not slightly offset. Is there a reason for that? ductility?

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 III

"...off-form concrete finish."

Why would they smear this stuff? It can't be structural, can it? And, if not, what's the point?


spsalso

RE: SF Tower settlement Part III

Quote (spsalso)

Why would they smear this stuff? It can't be structural, can it? And, if not, what's the point?

Is it NOT a coating or a 'smearing' of cementitious layer.



A 1" x 1" (or 3/4" x 3/4") wood chamfer strip is added to the corner of the beam/column forms, and when concrete is been placed and consolidated the chamfer strip often moves slightly (if the chamfer is not nailed securely) and concrete slurry then gets between the chamfer and the face of the formply and then the concrete and slurry sets. Upon stripping the forms the 'dags' remain. Hence, an off-form finsh, no coating.

RE: SF Tower settlement Part III

(OP)
Could it be a flexural crack from moment caused by vertical translation?

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 III

Crack inclination signals a Shear crack. Flexural cracking would be more vertical at Top & Bottom extremes.

RE: SF Tower settlement Part III

Got it about the leakage behind the chamfer strip. Thanks.




spsalso

RE: SF Tower settlement Part III

(OP)
Sorry Ahmed, the cracks are nearly vertical, and there are 2 or 3 of them, similar to a flexural crack in a high moment area... it was just a thought.

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 III

Can any of you structural guys explain to me how the Baugrid connects at a joint like this? I checked their website and it looks cute in a beam or a column, but what do they do at connections?

RE: SF Tower settlement Part III

Quote (dik)

I would have thought the SMRFs would be located on the same plane, not slightly offset.
The slope of the most southeast & most southwest SMRF are the result of needing 'driving' space for vehicle in the porte-cochère.

During peer review it was an element to which Hardip Pannu of Middlebrooke-Louie, noted a concern for the large elements behaving like shear walls. There isn't any information as to how his concern was resolved.

EOR, Derrick Roorda at that time with DeSimone Consulting Engineers, wrote in his paper for the SEAONC 2007 conference proceedings; "Design of Tallest Reinforced Concrete Structure in California – 58 Story Residential Tower in San Francisco" as so:

RE: SF Tower settlement Part III

Quote (Walnut)

Can any of you structural guys explain to me how the Baugrid connects at a joint like this?

While most of the 'link-beams' do use Baugrid, it was after all the joint they tested for this project; this photo somewhat suggests the link-beams for the sloping SMRFs were field built. The edges of the rebar, in the beam, appear to be rounded compared the squared sharp edges of the Baugrid columns.

RE: SF Tower settlement Part III

(OP)
Thanks epoxy... there are just so many things about this that I'm a little concerned about, but don't have the seismic or geotech, or real high rise (limited to about 35 stories) experience to be really frightened... 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 III

Epoxybot, that is a really scary photo Trying to pour that with everything tied is close to physically impossible even with a great plasticizer mix, that is alot of steel to get the aggregate through. That crack is getting close to the bars and that is not a good thing, because that beam should be not be under enough tension that the diagonal crack suggest.

The reason the concrete looks that way is because there is a ton of water added and it is all "cream" and no "rock". I have poured some pretty big beams with triple #13 top and bottom and the only way that I know to do it is to tie them as you pour.


There was a question about plumbness in columns, it is more about transferring loads, and yes it would be really bad if the cross section of the steel is offset by 10 degrees. Yes you can have angled columns, but the design of the underlying beam would be different, and would function more as an joist or a truss, which would distribute the compressive load to a transfer beam and would then load a foundation.

RE: SF Tower settlement Part III

(OP)
I've designed sloping columns and beams similar to what was shown... never an issue as long as your design is correct. I've never had an opportunity to place so much reinforcing in any structure I've done. I'd have probably done the frame in steel.

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 III

A little follow-up on the crack in the link beam adjacent to the southeast SMRF. Beams cast to support the driveway tie into the SMRF/Link beam/s. It would seem the driveway support beams are pushing on the SMRF/Link-Beams. This took place before the tower was given a Cert. of Final Completion.



RE: SF Tower settlement Part III

In the photo that epoxybot posted there appears to be at least 3/4" of conduit running thru deck / beam connection. Does anyone know what deck system they used? I'am starting to think that this building has incurable problems that would not matter if were constructed on s correct foundation.

I just read an article of the google, that suggested that they are going to just start excavating in preperation for the mat extentsion without approval for the reduction from 56 piles to 18. I have never seen the bottom of a mat foundation exposed, and the thought scares the poop out of me, that is one major rain event to a nightmare.



RE: SF Tower settlement Part III

I'm having trouble seeing any hint of conduit running thru deck / beam connection.

The latest report from the tilt-o-meter is strangely late. Wonder what's up.


spsalso

RE: SF Tower settlement Part III

Quote (spsalso)

I'm having trouble seeing any hint of conduit running thru deck / beam connection.
I didn't see any either, I thought I had just missed it, glad you didn't see it either! I was also wondering about the tilt report, hopefully it's nothing unusual but being late you certainly have to wonder.

RE: SF Tower settlement Part III

Josh Porter (Building Integrity) has a new to me video on this building:


Link


This one is only the first (or third, depending on how you look at it) in a series--looking forward to more.


spsalso


RE: SF Tower settlement Part III

Keith 1 - they are not actually going to excavate under the bottom of the mat. Just down to it. And then jackhammer a hole in the mat, which I think knocks off the tops of the first row of the existing concrete pile, in which they then pour a key. This is shown in Step 7 of their drawings.

What the drawing does not show is that they are now down in the young Bay Mud, which would heave at the bottom of a 25-foot excavation even if there were not a 600-feet-tall building right next to it. Who knows what will happen in this case?

RE: SF Tower settlement Part III

LB Karp recently updated his Millennium Debacle web page with documents from the previous LERA proposal, along with site photos of the current work.

RE: SF Tower settlement Part III

I like his title: "Start excavating along Fremont Street to relieve lateral support to base of building to assist inducing catastrophic failure".

RE: SF Tower settlement Part III

(OP)
Should Karp not be including a copy of his correspondence to SEAOC? They are the ones truly invested in looking after the welfare of the citizens and protecting them.

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

-Dik

RE: SF Tower settlement Part III

Within Karp's correspondence Link to City and County of San Francisco Board of Supervisors dated April 4, 2022 he states the following:



From this Link Deierlein (as chair of the EDRB) is signing off as a P.E.



If you do a check for Deierlein here Link it indicates that he is not licensed in California. The other three (3) co-signers are licensed in California.

I am not familar with BPELSG rules and regulations, but Deierlein - regardless of his qualifications and experience - probably should not have signed off as a P.E.



RE: SF Tower settlement Part III

Yup.

And meanwhile, it's been two weeks since the last posting on the tilt-o-meter.

Sure hope it ain't broke.


spsalso

RE: SF Tower settlement Part III

spsalso, maybe jackhammering out the old shoring wall has broken the tilt-o-meter?

ingenuity, I believe that Deierlein has a New York P.E. I don't know what the local rules are either, but I would think that, at a minimum, he should put (NY) after the P.E. What is more telling is that he is not an S.E. Insufficient practical experience!

RE: SF Tower settlement Part III

I am pleased to report that the tilt-o-meter is still in working order, though it's running a bit behind. The April 6 report was just posted.

I am also pleased to report that the rate of tilt change is roughly the same as it's been, and the Salesforce Tower continues to be in peril.

I wonder if it's too early to have a design competition for the replacement buildings.



spsalso

RE: SF Tower settlement Part III

(OP)
...or maybe start a pool for when it 'goes'? ponder I got into trouble on the other site for suggesting a pool for Covid deaths. pipe

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

-Dik

RE: SF Tower settlement Part III

I think the tilt-o-meter has been drinking. Very weird results. The next week's must be even worse since they are late again?

RE: SF Tower settlement Part III

If I'm not mistaken no work has been going on recently but yet a couple of the test points went up? Certainly makes me question the validity of the measurements.

RE: SF Tower settlement Part III

Or things are breaking.

RE: SF Tower settlement Part III

More from the tilt-o-meter:





Compare the last report, 048, with 046. Look at the 1.2 inch contour in particular.

RE: SF Tower settlement Part III

(OP)
Interesting localised 'dip'. ponder

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

-Dik

RE: SF Tower settlement Part III

Sure haven't heard much from Aaron Peskin (San Francisco Supervisor) or Jaxon Van Derbeken (reporter) on this matter for awhile.

Wonder why.

Are things going so well and so blandly that there ain't much to say?




spsalso

RE: SF Tower settlement Part III

(OP)
Peskin's earlier involvement may be a bit of a problem.

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

-Dik

RE: SF Tower settlement Part III

It hasn't kept him from asking embarrassing questions until recently.

I wonder why he would change his approach now.


spsalso

RE: SF Tower settlement Part III

(OP)
He may have learned his earlier actions may make him and/or the city culpable.

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

-Dik

RE: SF Tower settlement Part III

(OP)
I'm still a bit concerned about the actions of the SEAOC. If the tower fails and there are some fatalities, the question will be asked, "Why didn't they do something?" With most professional organisations their 'mission statement' is to protect the public.

We have a similar situation in Winnipeg where we had a large city building, with possible massive building envelope issues. The occupants were relocated to another building and there is a fairly intensive 'fraud' investigation.

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

-Dik

RE: SF Tower settlement Part III

SGH Field Report #7 - Oct. 11, 2021 - (Supplement No. 69) is a collection of photos of the Podium/Mid-Rise & Tower basement levels. Starting on page 4 of the report are photos attributed to the "West Podium Basement Wall at level B1". That's not possible.

The photos clearly show water intrusion through cracks in the shotcrete basement wall but the opposite side of a Podium/Mid-Rise B1 basement wall would be the B1 basement of the tower. The as-built elevation difference between the tower B1 basement and the B1 level of the podium.mid-rise is about 1 inch. The shoring wall tops put below the tower mat at 25.75ft BGS.



Roughly, the historical ground water level for this area of the old Yerba Buena Cove has been about -7ft to -11 SF Datum. At the southwest corner of the site this translates to about 11ft to 15 ft BGS. The only source of water above this level would be the landscape water system, which failed spectacularly on Mission St. & Fremont St. The elevation at the B1 basement tower mat is 15.75ft BGS.

My interest is the result of an ongoing lawsuit between two maybe 3 insurance companies that are arguing over Webcor, possibly having not provided a bond-breaker between the podium/mid-rise shoring wall and the podium-mid-rise basement structure. Results from LERA's investigation of the clearance between the base of the tower mat & the top of the tower/podium shoring wall show a mixed bag of Stayform and plywood. The investigation was conducted at the top of the level B3 podium/mid-rise basement wall to gauge the distance between the top of the shoring wall & the bottom of the tower mat.

So surely the SGH photos attributed to level B1 must be at level B2. To verify, I first looked at construction photos to see if any showed a wall being built at the B1 level separating the tower & the garage but no luck. But I did see the ground, mechanical and 3rd floors of the tower had decks cantilevering over the podium mid-rise.



I couldn't find any drawings that suggest the tower's cantilevered decks connect to the podium. The result, are offset seismic joints between the B2 level & the ground floor.



Here, (Google Maps) you can see the 3rd floor (pool deck) is supported by steel beams connected to a separate structure from the tower's cantilevered deck. An elevator shaft can just be seen in the shadows. Photo 11 (page 6) of the SGH Field Report #7 appears to identify this as a shear-wall. But what level, B1 or B2?



Still trying to rule out any B1 podium level concrete wall I looked at SGH Supplement No. 20 - June 7, 2019. It is a response to the EDRT regarding the prospect of the tower coming to rest on the tower/podium shoring wall. On page 9 of the document is a cross section of the tower:podium interface. Assuming this is the case over the entire length of the B1 podium/mid-rise basement adjacent to the B1 tower basement. There isn't any B1 West Basement wall built of shotcrete that is cracked and leaking.



None the less SGH sure seems to think one exists.





Thank goodness for the Eagle-Eyed EDRT.



RE: SF Tower settlement Part III

The purpose of this structure is to be an aspirational, high life-style, high profile, high capital growth flagship asset that (almost incidentally) people can live in. I have boundless faith that enough money and enough engineering applied in enough time could make safe the physical structure, but will it now ever be what it was built to be? It's going down 2" a year on one side. I wouldn't buy there even if I could do it with pocket change. I realize this is a social and human matter not an engineering one, but this building is not like a bridge, whose purpose emerges from its existence at a particular location, and has 100% restored function once some emergent problem gets properly fixed. This object is a "brand" sprayed onto a bunch of building materials that at this point would be better off somewhere else, it seems to me.

RE: SF Tower settlement Part III

I reached out to Dr. Robert Pyke who had asked about the impact of the garage shoring wall on the design team's estimates of future settlements in one of a series of letters From Dr. Pyke to Neville Pereira of DBI. I guess he was concerned that when the EDRT asked about the shoring wall in 2019, they got the usual runaround from Hamburger and Co. This is what Pereira wrote back to him: As you noted in your letter, the EDRT has previously raised a comment with the design team regarding the existing CDSM shoring wall beneath the east side of the mat foundation. As part of our ongoing review, we are confirming with the design team that the possible effects of the shoring wall are being addressed in the analyses to evaluate building settlement and the mat integrity for the proposed revisions to foundation retrofit. This suggests that the DBI and the EDRT had been asleep at the wheel since 2019. Dr. Pyke has not yet received any further response from Mr. Pereira.

RE: SF Tower settlement Part III

(OP)

Quote (I have boundless faith that enough money and enough engineering applied in enough time could make safe the physical structure)


I hope you are correct... I don't have the same 'warm fuzzy feeling', and it may just be an overcautious approach due to my unfamiliarity with really tall buildings and seismic activity. To me, there are too many irregularities in the foundation for a high seismic area, and already signs of distress. In addition the foundations only go down a fraction of the height of the structure in soil that may liquify. pipe

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

-Dik

RE: SF Tower settlement Part III

Photo of Fremont St sidewalk as of yesterday. Serious digging has not yet started.

RE: SF Tower settlement Part III

@epoxybot

I'm working on my geotech masters and exploring the MT case history. Could you help clarify some questions I have?

  • Does the old/new PGE vaults referenced in your diagrams run the entire length of the cantilever slab?
  • Was the old PGE vault removed or just abandoned in place?
  • Is the old PGE vault pile supported?
  • Do you have any plans/dimensions available?
  • Do you have any construction sequencing documents for the MT?
Thanks in advance

RE: SF Tower settlement Part III

Quote (dik)

in soil that may liquify.
In the real world of limited budgets and competing interests that is my concern too. When compaction becomes lateral displacement, if that hasn't started already, I think in practical terms it's game over. Many startling things can be achieved by clever folks with a bottomless budget but a budget that could fix this probably exceeds the reputationally-diminished worth of the building.

RE: SF Tower settlement Part III

I believe I read earlier on this page that lateral displacement HAS occurred.


spsalso

The latest tilt-o-meter numbers are in, and the building tilt is progressing nicely.

RE: SF Tower settlement Part III

@Cool_Controls linked a local TV news report in which, in one shot, they pointed out the same weekly report as @Walnuts did here on April 16th, the one with the squiggly 1.2 inch contour line. They seem to be basing their claim of the tower dropping 0.1 inch in a week on that. However, that seems to have been a bad data point, and the tower seemed to return to a steadier rate of sinking and tilting in the next two reports.

RE: SF Tower settlement Part III

(OP)

Quote (the tower seemed to return to a steadier rate of sinking and tilting in the next two reports.)


That's reassuring. ponder

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

-Dik

RE: SF Tower settlement Part III

Still more Building Integrity (part 4):


Link



spsalso

RE: SF Tower settlement Part III

(OP)
I think Hamburger's credibility is seriously challenged. I've never been involved with this type of response. Seems like the Keystone Engineers... ponder

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

-Dik

RE: SF Tower settlement Part III

@pellucidar: It is tough to draw any conclusions from a week or two of data. The 1/10 inch drop in one week of the north-west corner was followed by a rebound the next week, then a very small drop, and then another big drop, so that the average rate of settlement of that corner remains about the same it has been since August. And they are just mucking around at the surface. They have not even begun construction of the new shoring walls (secant piles using CLSM with soldier piles every 5 feet) or the excavation down to 25 feet into the young Bay Mud layer! But the kink in the 1.2 inch settlement contour has straightened out. Maybe that was a survey error or a zombie trying to get out from under that mat? I dunno.

RE: SF Tower settlement Part III

Slow and steady wins the race.

RE: SF Tower settlement Part III

Do it right the first time.


spsalso

RE: SF Tower settlement Part III

Quote (Cool_controls)

Slow and steady wins the race.
Or possibly in this case slow and steady loses the building!

RE: SF Tower settlement Part III

2

Quote (ti89t)

Does the old/new PGE vaults referenced in your diagrams run the entire length of the cantilever slab?

Based on photos of the excavation, exposing the older utility vault, the older utility vault runs nearly the entire length of the 103ft width of the 3ft cantilever slab. The tower's vault is approximately 90ft long and 15ft wide. The soldier piles of the shoring wall, at 5ft o.c. seem to confirm the 15ft width of the old utility vault.

Unlike the north, west & east tower basement walls, which are shotcrete, the new PG&E vault is poured in place concrete. There is a small niche at on the exterior of the east end of the new PG&E vault that is a part of the Condo owners storage area. Neither PG&E or Mission Street Development appear to have traded any additional square feet and called it a day.

Quote (ti89t)

Was the old PGE vault removed or just abandoned in place?

It remains to be revealed if the old PG&E vault was demolished or left in place. The last photo of the old PG&E utility vault, available on the Interweb, has a date of June 7, 2006. The pour for the mat was June 17, 2006. Neither the SF Dept. of Public Works (SFDPW) or the SF Public Utilities Commission (SFPUC), list permits for disconnecting PG&E Electrical, leading up to the tower's foundation pour.

I have made two separate PG&E Land Office requests regarding the current state of the old PG&E vault. With the first request, I received a phone call from Brad Harris of the PG&E Land Office. He wanted to more clearly understand my request. When I directed him to the Wikipedia page that showed the older utility vault, ...for some reason he dropped his phone and we lost contact...surprise. We reestablished contact and I was told he would dig into the matter. He was, he explained working from home but insisted, everything was at his fingertips (Covid Restrictions). 2 weeks later I left Brad a message following up. He promptly returned my call and said he couldn't find any record for a PG&E vault, buried under 129 Fremont St. I told Brad I has reviewed the Deed for 129 Fremont & the ALTA Survey and that I was unable to find any notation for the utility vault. He suggested that since the vault was on private property and not necessarily connected to 129 Fremont that there wasn't any need to file an Easement. Strange as it may seem, this could be true; as PG&E owned 129 Fremont at that time. The only useful information I was given was that PG&E sold 129 Fremont, May 2, 1972. Subsequent phone calls with Brad Harris, devolved into spin that the vault might belong to other utilities.

Later I contacted the PG&E Land Office regarding 345 Mission St. (SE corner lot of Mission & Fremont), to which PG&E began occupancy circa 1958. In this instance, I received an Email response, requesting further details. I was asking for the date of sale for 345 Mission, so I could request the deed from the SF Assessor. When I gave them a run down of my previous communications regarding 129 Fremont & Millennium Tower, I was told to go dig in the SF Assessors' archives. Finito mad

Twice now the PG&E vaults have escaped Environmental Impact Review (EIR). First in the original EIR for the tower's planning approval & secondly for the so-called Retrofit. The California PUC and the City & County of San Francisco afford Public Utilities relief from undergoing EIR under certain circumstances but in the instance of Millennium Tower, PG&E had zero NEED to relocate or refurbish the utility vault. The only reason for moving PG&E's utility vault was to accommodate a private developer and allow that developer to build on land that was under PG&E's control. The reason being that one cannot build on or over a PG&E Easement.

The problem with the newer PG&E vault built into the tower's basement, is that it is integral to the tower's basement, occupies a completely different portion of land (Vertically), cannot be located in the HOA covenants even though they share a common wall, while supporting the driveway and there are 3 transformers exiting the utility vault, into the basement of the HOA property. And finally for the Retrofit EIR, the utility vault has a multitude of cracks due to the tower's settlement, its robust construction results in additional stiffness to the cantilever slab and can thus be considered a factor contributing to the hinging of the cantilever mat and yielding of the rebar connecting the 3ft slab to the 10ft mat and perhaps the crack in the SE sloping SMRF. Just throwing gas on the fire, the newer PG&E vault sits about 25 feet from the Fire Emergency Water Reservoir located just south of the tower core. Granted, the reservoir is located in a particularly robust position of the mat.

Even if we were informed that the vault was demolished, the question lingers as to what extent it was demolished. Was the top of the vault demolished and the rubble placed in the bottom half?

Quote (ti89t)

Is the old PGE vault pile supported?

I don't know. The top 11 to 17 feet bgs is liquefying sand fill. The Young Bay Mud in which it is embedded is marginally liquefiable. If the top of the old utility vault is -20ft sf datum and the overall height of the utility vault is 15ft, then the vault could be sitting on a layer of sand or more YBM. During ground clearing excavation, in advance of installing the CDSM shoring wall for the Transbay Transit Center, the subcontractor for Balfour Beatty Infrastructure, filed an RFI related to encountering piling that was supposed to have been cleared by the Demolition Contractor. The piles proximity to the tower was of a concern, since by the time the excavation work commenced the TJPA were paranoid about settlement on the Millennium Tower property. The response to the RFI noted a concern for the "utility vault" at -20 to -30 feet. These depths coincide with the older utility vault but there is enough ambiguity to the RFI, to not definitively know if the piles extracted were adjacent to, or below the utility vault. Somewhere at the TJPA and/or ARUP, there are photos.

Quote (ti89t)

Do you have any plans/dimensions available?
I have attached a drawing giving the dimensions of the tower basement from which the size of the current PG&E vault can be extracted. The drawing is from one of LERA's submittals to SFDBI and can be found on LB Karp's "Millennium Debacle" webpage. I have been unable to access LB Karp's webpage recently. If you can't access the page, I can post the entire document..., once I find it in the maze of files I have accumulated.

Quote (ti89t)

Do you have any construction sequencing documents for the MT?

No. I have a very long timeline that I have documented and cross-reference with what is available on line, gleaned from testimony and supplemented with observer accounts from the SkyscraperPage.com Millennium Tower Forum Thread. The forum thread include Webcor's Project Progress Press Releases.

RE: SF Tower settlement Part III

@epoxybot

You are an amazing individual and I cannot thank you enough for your work documenting this debacle.

I spoke with Larry this week about the website and he said his server is down but should be up in a few days. I’ve been using the waybackmachine to get archive copies of things until it’s back up.

I have some responses/follow up questions that I’ll send your way this week.

Thanks again!

RE: SF Tower settlement Part III

2
Falsus in uno, falsus in omnibus

I was going through LERA's "301 Mission St. Stabilization - Structural Basis for Design" - Sep. 20, 2018, compliments of Larry Karp's Millennium Debacle page and came across a disturbing bit of information. Beginning on page 106, LERA gives the "As Built" description of the existing piles.

The piles Do Not conform to the Shop Drawings and description provided by Simpson, Gumptertz & Heger's, "Supplemental Report for Foundation Settlement Investigation"

How does this even pass the muster of the 301 Mission St. Dearly Departed Mayor Edwin Lee's Structural Safety Review Team? It seems that the entire report to the City of San Francisco was based on DeSimone Consulting Engineer's Design Drawings and NOT on what was actually built. San Francisco paid $150,000 for the report and seems to have been hoodwinked. Where was Craig Shields, the Geotechnical member of the Structural Safety Review Team?

Surely, if anyone had access to the As-Built drawings and RFI log, one would think it would be the Developer and their post-construction engineering team. There doesn't seem to be any comparison between the superiority of LERA's "Initial Work" and what SGH has served up. The HOA has made some very poor decisions.

Further into LERA's section on the existing piling, they produce a graphic that shows the locations of the short driven piles; not too different from the one I produced from the shop drawings. It would be interesting to know how Engeo Geotechnical Engineers described the ground and it's effect on the piles.

While I don't know when in 2018 LERA developed their 'short-driven' pile map. I'm going to gloat a little for having posted mine to Eng-Tips in early April of 2018, while their report is from Sep. 2018.

RE: SF Tower settlement Part III

Mayor Lee had been dead 9 months by then. I don't think the review team was "his" anymore. Maybe throw in a "former" or something.

I get that there was a lot of sloppiness (at best) in the construction of this building. And the review of the construction of this building. And the design of the repair of the construction of this building. And the execution of the repair of the construction of this building. And the review of ALL of this.

THAT was fun to write. I was tempted to go on, but....

What are the implications of this particular form of sloppiness to the project?


spsalso




RE: SF Tower settlement Part III

The implication of the sloppiness of the design, construction and review of the perimeter pile upgrade is that the real estate values will never be "restored", which, according to Hamburger in his university lectures, is the purpose of doing this "fix". Grade is F.

RE: SF Tower settlement Part III

Oh, and I have heard one or more structural engineers complain that it has made geotechnical engineers in the Bay Area "more conservative". That might be true, but hopefully it has made them more careful rather than more conservative.

RE: SF Tower settlement Part III

Quote (Walnuts)

Oh, and I have heard one or more structural engineers complain that it has made geotechnical engineers in the Bay Area "more conservative". That might be true, but hopefully it has made them more careful rather than more conservative.
In reality it probably needs to be some of both. They obviously need to be more careful and make sure that their calculations are correct but they also need to be much more conservative and farther estimates go and they definitely need to err on the side of excessive safety. I'm sure the contractors and designers put a lot of pressure on them to reduce the costs but this is a perfect example of how the reduced costs come back to bite you in the long run!

RE: SF Tower settlement Part III

"...the reduced costs come back to bite you in the long run!"

Exactly. The reduced costs will bite ME every time I cross the Bay Bridge:

Epoxybot, on this topic (Dec 4, 2020):

"...$1 dollar from every vehicle that crosses the SF-Oak Bay Bridge..."


Yes. Who reduced the costs? Who benefited from the reduced costs? And who are the "you"s that got bitten?


spsalso

RE: SF Tower settlement Part III

I believe that the problem was driven by Millennium Partners desire to not increase costs but more than anything-else was driven by their desire to keep to a tight schedule, aided and abetted by Webcor. And aided and abetted by Treadwell & Rollo who relied on the "this is what everyone does" school of engineering when it was not applicable. The reason that you bear the cost is that the Transbay Joint Powers Authority was run by amateurs. Probably still is, although I have not followed that closely. But I believe they only put in $30 million to a $400 million settlement, so mostly it is the stockholders of a number of insurance companies that were taken for a ride by the lawyers and the legal process. "If you don't put up now, it will cost you even more if you go to trial." Maybe epoxybot can translate that to Latin for us?

RE: SF Tower settlement Part III

ti89t - LERA's "301 Mission St. Stabilization - Structural Basis for Design" - Sep. 20, 2018, compliments of Larry Karp's Millennium Debacle page contains a couple of DeSimone drawings, namely the elevator pit, that makes this download of interest to your pursuit.

I'm going to throw SGH the mealy end of a dog bone over Ron Hamburger's Dec 2020 SEAONC Convention video and his remarks about the TJPA shoring wall restricting the settlement of the 3ft cantilever mat.



Reviewing this slide generated by Pelli-Clark-Pelli, shortly after the TJPA gained access to the Millennium Tower's drawings, one can see some pretty silly shoring ideas that would have put the TJPA directly in the bullseye. Presumably, they did not actually underpin the south end of the B1 basement with a 110ft deep shoring wall. Likewise. they did not sink the TJPA's excavation shoring walls to bedrock. The TJPA was required to provide Mission St. Development (MSD) with 'preliminary' and 'approved for construction' plans for work in the 5ft easement that MSD donated to the TJPA. So, SGH should know what is actually in the ground next to the B1 basement.

The turn around from when the TJPA was provided plans for Millennium Tower to when Pelli-Clark-Pelli gave the TJPA BOD a presentation was about 1 week, so the slide is somewhat back-of-the-napkin.

RE: SF Tower settlement Part III

So the Transbay Joint Powers Authority can pass along their $30 million contribution because they can.

We will raise the bridge fare because cars are bad, and people who drive them are bad, and we will make them pay the extra dollar and no one will object. We certainly will not pay that $30 million out of our own pockets, because we have no pockets.

And the San Francisco Building Department. What are they kicking in? Are they raising permit fees to cover the expense?


spsalso

RE: SF Tower settlement Part III

(OP)
This whole thing just seems to get better and better.

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

-Dik

RE: SF Tower settlement Part III

A recent report by NBC Bay Area’s Jaxon Vanderbeken has been getting some traction in the press. NBC’s report brings to the fore, the tower/podium shoring wall and the fact that the tower will most likely come to rest on the CDSM wall.

SF Gate later ran the story with commentary from SGH’s Ron Hamburger. Hamburger seeks to give assurances regarding the shoring wall, stating they have been aware of the shoring wall since 2014. No doubt this is true but more so, in relation to the leaking in the 5-level parking structure. It was, after all, LERA/Enego who felt it necessary to investigate the relationship between the tower and the shoring wall.

Compared to LERA’s permit submittal of just two locations of investigation, the actual scope of work was far more comprehensive. Still, it appears LERA missed the portion of the shoring wall that would have revealed just how much distance remains between the Tower/Podium shoring wall and the bottom of the 10ft mat foundation.

In SGH’s original 52 pile retrofit scheme, the Expert Design Review Team’s 2019 Final Comment Log, Comment 20, indicated the separation between the bottom of the mat foundation and the top of the shoring wall, noted by LERA/Enego, was approximately 2 inches. Considering the locations where LERA/Enego/ Nicholson Construction/Cotton-Shires Assoc., cored through the parking garage wall, to inspect the shoring wall/tower separation, there is no clear knowledge that the northern end of the shoring wall, at Mission Street, isn’t already in contact between the mat and the shoring wall.

While not a perfect analogy, SGH seems to be taking the ‘coaster under the table leg’ view of their repair scheme. What seems more likely is that the tower will settle to the east and come to rest on the northern stretch of the shoring wall before any settlement to the south can make any meaningful difference.

Since the tower’s foundation was mechanically connected to the shoring wall during the tower’s construction and it didn’t show any signs of settlement; SGH seems very optimistic that the shoring wall will indeed settle.

From the 13th floor to the 42nd floor, 56% of the building weight was incrementally added to the tower, at approximately 3 million pounds per floor, per week. When the tower was released from the shoring wall, tower settlement accelerated dramatically until the topping off ceremony.

The top of the shoring wall deserves some characterization. The wall has 34 each W24 soldier piles, in total, mostly spaced at 5ft on center. The final 30 feet of shoring wall at the north end has 6 soldier piles, spaced at 2.5ft on center. These soldier piles were subsequently cut down just above the Cement/Soil mixed wall. The tops of these soldier piles will be the first points of contact with the bottom of the foundation. This northern end of the shoring wall, is an area in the adjacent parking, subject to cracked walls and slabs with persistent water ingress. Since the tower won’t be coming to rest uniformly across the entire shoring wall, there is concern the soldier piles will chisel into the bottom of the tower's mat at a subterranean level; known to be well below historical ground water levels. According to ARUP’s Transbay Transit Center geotechnical investigation, the ground water of the former Yerba Buena Cove is brackish.

The following image shows the extent of LERA’s shoring wall investigation. The image requires some explanation. The base image provided the breadth of the site, with the shoring wall in yellow and the tower’s ground floor cantilever in blue. LERA’s investigation (Light Blue Overlay) is scaled to the base image shoring wall to highlight the extent of the shoring wall investigated. The lower overlay shows the 10ft mat and the original permit inspection points.



Page 45 of LERA's "301 Mission St. Stabilization - Structural Basis for Design" - Sep. 20, 2018 shows LERA’s Analytical Mat Deflected Shape, as of Sep 2018.



Scaling LERA’s Mat Deflection Map to the Tower/Podium shoring wall, it appears that LERA may have missed the portion of the shoring wall that represents the least separation between the tower’s mat and the tower/podium shoring wall.



In my April 18 2022 Eng-Tips post, I showed cracks in the Podium’s Elevator Shaft (Level B1) that is integral to the 5-Level Parking Garage’s Shearwall. This is directly in relation to the area missed by LERA’s shoring wall inspection. While pure speculation, what appears to have happened, is the Podium/Garage has suffered Shadow-Effect Down-Drag, resulting in the cracks seen in the elevator shaft.

With the tower in its current state of tilt, the tower’s cantilever decks that projects into the podium, should be moving away (West), from the podium’s elevator door opening.



Remember that the Podium is buoyant and the 6ft thick portion of the podium/mid-rise mat, between the tower and the mid-rise is secured to ground with tie-downs.





Perhaps this explains why there appears to be uplift of the Mid-rise at the northeast corner of the Mid-rise at Mission & Beale. So, not so much basal heave as thrusting of the 6ft Mid-rise/Podium Mat.



I don’t recall if the EDRT has concerned themselves with the seismic gap between the cantilever decks and the podium. Or, how much the gap will close as the tower settles to the east.

RE: SF Tower settlement Part III

(OP)
How will the existing piles interfere with the new proposed ones? Will they be able to jack against the new ones as proposed? Has there been any thought of getting a 'bunch' of geotekkies together to come up with a plausible solution?

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

-Dik

RE: SF Tower settlement Part III

Many thanks to epoxybot for all the detail and especially this: Since the tower’s foundation was mechanically connected to the shoring wall during the tower’s construction and it didn’t show any signs of settlement; SGH seems very optimistic that the shoring wall will indeed settle. From the 13th floor to the 42nd floor, 56% of the building weight was incrementally added to the tower, at approximately 3 million pounds per floor, per week. When the tower was released from the shoring wall, tower settlement accelerated dramatically until the topping off ceremony. There are complications, like the western garage shoring wall being tied in some way to the other shoring walls by the stout diagonal bracing as the garage excavation was being made, and now being stuck in some way to the garage wall because a bond-breaker was never installed, and the fact that the Old Bay Clay would not have been pushed back on to its virgin curve until the Tower got up somewhere approaching its full height, but Hamburger's 2019 assertion that the mat would just push the shoring wall down when they came in contact was very cavalier, and the fact that the ERDT signed off on this suggests that they were asleep at the wheel. Oh, wait a moment, they did recommend in their letter signing of on the Perimeter Pile Upgrade that they be retained for 10 years to monitor it. Maybe they were wide awake?

RE: SF Tower settlement Part III

"...as the tower settles to the east."

That is quite unsettling to read! But at least I know which part of downtown SF to avoid.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

RE: SF Tower settlement Part III

From NBC news, January 7, 2022:

"The 58-story, 645-foot tall tower — opened to residents in 2009 — is now tilting 26 inches north and west at Fremont and Mission Streets in the heart of San Francisco’s financial district..."

https://www.nbcnews.com/news/us-news/leaning-san-f...

There seems to be some confusion as to which direction the damn thing is going to fall. I'd recommend staying out of the Financial District altogether. And also the Embarcadero. City Hall and SF Building Department, on the other hand, are quite a distance away from the drop zone; so the folks there will be safe.


spsalso

RE: SF Tower settlement Part III

@epoxybot

One aspect I've been looking into was construction of the TTC buttress wall re-initiating settlement of the MT. Given the problems SGH has had with installation of the new piles accelerating settlement again, construction of the TTC buttress could be linked as well. The attached Desimone/T&R log scale shows end of primary consolidation may have been approached but resumed after buttress construction. This problem could have been exacerbated by the CDSM shoring wall NOT being complete due to the PGE vault relocation between Fremont/Mission as discussed in the attached ARUP/BF documents. BF/ARUP proceeded with dewatering and ARUP emails show piezometers levels were lowering the groundwater beyond those in the HSI dewatering analysis. I think the big takeaway is everyone who has touched the project underestimated the OBC, especially T&R pushing the OBC back into a normally consolidated state.

RE: SF Tower settlement Part III

(OP)
Slide #11 is telling... The Tower of Pisa was tilting as it was being constructed... there is some real intesting history there.

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

-Dik

RE: SF Tower settlement Part III

https://www.msn.com/en-us/weather/topstories/sf-s-...

(18) Each column will support 1 million pounds instead of (52) 800,000 pounds, although they are rated to take up to 2 million pounds, Hamburger said.

The outside panel of structural experts wrote in their recommendation that in the long term, by 2060, the 18-pile plan could recover about 4.3 inches of westward tilt and 0.3 inches of northward tilt. In contrast, the 52-pile plan was estimated to recover about 5.5 inches of westward tilt and 3.5 inches of northward tilt during the same time.

RE: SF Tower settlement Part III

(OP)
We'll have to wait and find out if it works... ponder

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

-Dik

RE: SF Tower settlement Part III

Well, we can visit the tilt-o-meter and see how things are going. I do note that the north-south tilt appears to be currently stable, while the east-west is increasing. This is good news, as it appears it would tend to correct the aim towards the Sales Force Tower.

spsalso

RE: SF Tower settlement Part III

S.F.’s leaning Millennium Tower one step closer to stabilizing its issues

A revised plan to arrest and rebalance the sinking and tilting of San Francisco’s Millennium Tower moved closer to getting the official sign-off after an outside panel of engineers recommended it to the Department of Building Inspection. If all goes as planned, the work could be implemented by the end of the year.

The plan uses 18 instead of 52 piles, or columns, to take some weight off the building’s foundation and stop it from settling further at the building’s northwest corner at Mission and Fremont Streets. Casings are sunk into the deep rock bed below and the piles are then drilled through them to embed 40 feet in the rock.

Project engineer Ron Hamburger of Simpson Gumpertz & Heger said in an email that “all 18 structural piles have been installed” as of March 9 under the originally permitted plan to install 52.
 

RE: SF Tower settlement Part III

Hah, hah, hah, hah! One step closer to not solving the problem. It is not clear to me that they will get much if any rebound when they transfer some of the load to the new perimeter piles, and even their predicted rebound is less than the additional settlement that they have caused so far, let alone any additional settlement that results from the excavation needed to construct the mat extensions.

Mealy-mouthed excerpts from the letter from the EDRT:

Based on our review, these analyses and design calculations conform to accepted engineering practice in accordance with the San Francisco Building Code. [IMHO the problem is complex and unique and is in no way covered by standard engineering practice.]

Based on our review of the drawings and analysis reports provided to us by the EOR and his team, in our professional opinion the revised 18-Pile PPU meets the requirements of section 403.9 of the
2016 San Francisco Existing Building Code. [If you read 403.9 you will see that it is about voluntary seismic retrofits - there is nothing in it that applies to this problem!]

Subject to continued monitoring of the building settlement and tilt, through construction and following completion of the 18-pile PPU, we see no technical reasons to withhold approval of the proposed revisions to the building permit for the voluntary foundation retrofit. [The EDRT previously recommended that they be retained for 10 years to observe the performance!] [Note that they now call it a voluntary foundation retrofit, so 403.9 is not applicable!]

The Tilt-O-Meter seems to be on the blink again!

RE: SF Tower settlement Part III

Quote (Walnuts)

[If you read 403.9 you will see that it is about voluntary seismic retrofits...]

You called their bluff and read the Building Code. Bet they didn't expect anyone to actually do that!

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

RE: SF Tower settlement Part III

Well, started and then kind of stopped. They have installed every second pile for the secant pile wall(s) along Fremont Street and then switched to Mission Street. It appears that no-one who is willing to speak knows why, but they were approaching the 3-inch limit on westward tilt for the year that the design team had themselves proposed.

RE: SF Tower settlement Part III

Note that the DBI inspection report starts at the bottom of the page and reads up!

RE: SF Tower settlement Part III

(OP)
Am I missing something here?



The date occurring before the date of the report?

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

Dik, I don't see a date on the report. It has a disposition (start) date and an expiration date, but the report itself is not dated.

RE: SF Tower settlement Part III

Ha! That is a puff piece that sounds like it was written by Hamburger!

RE: SF Tower settlement Part III

Note that Hamburger gets the photo credit!

RE: SF Tower settlement Part III

I'm betting that Las Vegas has odds on this working, I know which side I would be betting on! When you start reading about what they plan on doing it just looks like they are looking for a cheap way out. On the 18 piles when they originally proposed 52? If I was a resident of the building I wouldn't want to be staying in it when they start during the excavation inside of the new shear wall they are going to install. We will all have to wait and see but....

RE: SF Tower settlement Part III

Quote:

wait and see

Make sure you so it from at least 646 feet away.

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

RE: SF Tower settlement Part III

Quote (Mark R)

Las Vegas has odds on this working, ...
The definition of "working" depends on your point of view and time horizon.

RE: SF Tower settlement Part III

There's a new element in one of the charts on the tip-o-meter. I'm talking about the one on page 4, otherwise called the yellow-and-grey page. If you examine the upper left, you'll see a large area that does not show any contour lines. It's about 30 x 50, if I've got my scaling right.

Now, one way to interpret this is that they're run out of numbers, so they can't draw the next line, and the succeeding ones. In that case, there may be a shipment of numbers coming in soon, so that the continually increasing tilt can be properly kept up with. It's unpleasant to run out of numbers, I can tell you!

Alternately, and I think I like this one better, is that that section of the slab has stopped sinking, and is staying at a flat plane. What's intriguing about this is that it would then hint that it might SNAP off. Won't THAT be fun?

Of course, there's also the version where some Big Guy said that if the building tilts more than 2.10 inches/units, that Heads Will Roll. Thus inspiring this hesitation to add those lines. Curiously similar to how it must feel to have to tell Putin that a few more square miles are, uh, missing in our inventory.



spsalso

RE: SF Tower settlement Part III

spsalso,

While it would be entertaining if the north-west corner of the mat has already broken off, I think that it is more likely that they just ran out of the ink that they used to draw the contour lines. [Or that the routine that draws the contours is still set at 2.1 inches max. If anyone from Slate follows this site, you need to re-set that limit.] The preceding figure shows 2.4 inches settlement for LE-01, which is close to the NW corner, so the contours should fill in nicely over to the corner. But many thanks for your naming and continued interest in the Tilt-O-Meter.

While I am at it, I am not entirely sure what is going on at present, but I think they have been installing, or trying to install, the jet grout plug down below 25 feet along the future Mission Street excavation. According to the single best boring log that I have seen, PB-1, which is around the corner on Fremont Street, there is young Bay Mud from 25 to 35 feet. Jet grouting is not very effective in young Bay Mud - see the reports and paper on what happened on the Posey Tube seismic "retrofit". [I put retrofit in quotes because thar whole exercise was stupid!] The EDRT seems to have some awareness of this because they pushed the design team into agreeing that they will use chemical grouting as necessary to ensure that the bottom of the excavation is sealed, but that is also a bit dicey. Anyway, if anyone is planning to sneak into the excavation at night, wear your gumboots!

RE: SF Tower settlement Part III

Does anyone have any updated information about recent developments about this work? It's been over a month with no information posted.

RE: SF Tower settlement Part III

Thanks for the update! I have a feeling it's going to drag on a long time before any resolution is reached!

RE: SF Tower settlement Part III

I wonder if this will have any effect on the buildings tilt? It's the 1st earthquake I've seen information about in the bay area since the problem was noticed. 5.1 Quake in SF Bay Area

RE: SF Tower settlement Part III

I don't know that an M=5.1 earthquake would have had any effect, but if you check the legend in the figure in the link in my previous post you will see that the jet grouting on Mission St is said to have ended and that completion of the shoring wall on Fremont St has commenced! This is very peculiar as the HOA had said that they were going to connect at least some of the new perimeter piles along Mission St before they went back to Fremont, where the lateral roof tilt is already very close to what the design team had said would be their limit for the year. Maybe there was a problem with the jet grouting (as I predicted) and they have gone back to Fremont St to keep the contractor busy while they figure out what to do. This likely explains the sudden drop of the NW corner 2 weeks ago.

RE: SF Tower settlement Part III

(OP)

Quote (...while they figure out what to do.)


That sounds promising...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

NEW PERMIT APPLICATION 202210033614

EMERGENCY REPAIRS OF FAILED FACADE SYSTEM. STRUCTURAL ONLY

RE: SF Tower settlement Part III

By any chance do you know where we could find a copy of that permit, it would be interesting to see what it actually says.

RE: SF Tower settlement Part III

@Mark R - SFDBI Permit Tracking System
Scroll to: Permit (Application) or Complaint number (click)
Paste 202210033614 into the search box.

RE: SF Tower settlement Part III

Thanks!

RE: SF Tower settlement Part III

Just an anecdote: Four Seasons luxury condos in SoMa have few takers

It took Millennium Partners 10 years to get this project going. It includes The Mexican Museum of Art. Much of Mexican Museum’s pre-Hispanic collection insignificant or fake

Millennium Partners sold the unfinished project to Westbrook Partners. Westbrook Partners has done a number of very lucrative deals for Millennium properties. This time they got bitten, it appears.

Featured in today's DailyMail

RE: SF Tower settlement Part III

(OP)
Tried clicking on the permit number search and ended up with... maybe something else works...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

Odd. I got through. They want to put new bolts into the concrete to hold the cladding, or whatever it is. The permit appears to be for installing the bolts.


spsalso

RE: SF Tower settlement Part III

I confess I cannot figure out what Jaxon is trying to communicate.

When you "...scrap an elaborate strategy...", it's usually because it's not working. So, Jaxon. What's not working?

Rewrite!!!


spsalso

RE: SF Tower settlement Part III

spalso, I think Jaxon is just repeating what Hamburger, through the Homeowners Association, and the City are telling him. That's why it does not make any sense! I can think of four reasons why they might have resumed work on Fremont Street: (1) There is a problem with confirming that the jet grout plug is sound and they need more time to sort that out; (2) they realized that full transfer of load to some or all of the planned 6 perimeter piles along Mission Street, without simultaneously transfering load along Fremomt Street was nuts and would have done funny things to the mat, and maybe the moment frames and the facade as well; (3) they realized that installing the secondary secant piles on Fremont Street would not affect tilt and settlement nearly as much as installing the primary secant piles did (because the secondary piles have existing primary piles on both sides so there has to be less ground loss as the casing is advanced - and also because the primary piles provide some resistance to lateral movement of the soil adjacent to the building, at least until it is excavated out), and (4) they are running out of time and money. It is reported that they are now operating on the insurance coverage that Millennium Partners agreed to buy on the design team and the Fix contractor in order to seal the settlement deal, so it might actually be the insurers who are now calling the shots. Or some combination of the above? Who knows?!

RE: SF Tower settlement Part III

Thank you!


spsalso

RE: SF Tower settlement Part III

(OP)
I'm not into seismic design very much or 'real' highrise structures... but, I think the problem is a lot worse than everyone involved says. It may just be my ignorance of these issues. If the insurance companies are 'calling the shots', I would have thought that they would have called in experts to determine just how serious the issue is. The work done over the last few years has not been impressive, and does not instill a lot of confidence.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

(OP)
Interesting developments to the north... I wonder how Millenium Towers would fare?

https://www.cnn.com/2022/12/20/us/humboldt-county-...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

This new article by geotechnical engineer Robert Pyke might be of interest. I hope that it is not too long.

RE: SF Tower settlement Part III

(OP)
No... it's just about the right length. I'm surprised the City of San Francisco or the California Professional Engineers Association hasn't gotten involved.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

I agree with dik, the article seemed about the right length and with a great explanation of what is happening. I certainly understand why the original president of the HOA resigned, I wouldn't of been comfortable at all signing on to this proposal. The internal micro piles certainly seem like a much better solution for many reasons I'm really surprised it wasn't pursued more (even if it was value engineered). The fact that these new exterior piles are not solidly connected to the mat is of great concern to me and the fact that they are actually "fused" in their connection is even of more concern! I wonder what the press will be if some of these fuses break?

RE: SF Tower settlement Part III

Thank you dik and Mark R.

Someone-else noticed that the date is screwed up. I think he meant December 30 because that is the reference to the NYT article. I'll let him know. Guy has a Ph.D., so he likely does not know what day it is!

RE: SF Tower settlement Part III

Oh, and one more thing. The chosen fix was not as far as I know value engineered. Just reviewed by two academics in the context of a mediation proceeding. I have been involved in those and it is like making sausage!

RE: SF Tower settlement Part III

The Tip-o-meter keeps reporting its results.

It's still tipping.

Have you thought how convenient it would have been if the Tip-o-meter had never been established?

For some people.



spsalso

RE: SF Tower settlement Part III

(OP)
spsalso... do you have a new link to the tilt-o-meter? I cannot locate it at the old site.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

Some recent pics.

RE: SF Tower settlement Part III

RE: SF Tower settlement Part III

RE: SF Tower settlement Part III

And from the Tip-O-Meter:

RE: SF Tower settlement Part III

RE: SF Tower settlement Part III

(OP)
Thanks...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

If I recall correctly, the Millennium Tower's original EOR, DeSimone Consulting Engineers favored the LERA/ENGEO internal (symmetrical pile) 'upgrade'.

One might question whether the project's classification as a seismic 'voluntary upgrade', which allowed a host of other building code metrics to be avoided; still remains valid.

SGH was the waterproofing consultant during the tower's design and were involved with the choice of the waterproofing admixture for the 5-level, underground parking, in lieu of more traditional waterproofing schemes. Water leaks, unlike the sinking & tilting, were not something the Millennium Partners run HOA (up until 2014), could allow to go unaddressed. Thus SGH was active on 'issues' regarding the tower for some time before the tilting & sinking became public. Most of the water leak problems are of course at the tower/podium interface.

The symmetrical pile upgrade was largely an MP-free, HOA endeavor, which, had it proceeded; would have possibly removed Millennium Partners from having command & control of information related to the tower's construction. Any review of presentations & articles regarding the tower by SGH, shows they have religiously avoided revealing any data recorded during the tower's construction, other than what was advantageous to MP.

RE: SF Tower settlement Part III

(OP)

Quote (the project's classification as a voluntary upgrade)


I'd never consider the project as such a classification... It's a design error 'fix'.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

Dik - I just came back to CORRECT the post. It was classified as a 'Voluntary' 'Upgrade'.

RE: SF Tower settlement Part III

It's been awfully quiet over there for awhile. No Hamburger. No Peskin.

What are you kids DOING over there?



spsalso

RE: SF Tower settlement Part III

(OP)
epoxybot... fixed mine, too.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

epoxybot, dik, actually it is both. It is a voluntary seismic upgrade. That is specifically described in the San Francisco regulations. According to Hamburger it is not a seismic upgrade, but San Francisco does not have a category called (laughable) voluntary foundation upgrade. I have heard that Neville Pereira of DBI has said that when he first appeared on the scene he did not understand why it had been permitted as a voluntary seismic upgrade, but it is the only thing on the books that allows you to skirt the current code requirements.

RE: SF Tower settlement Part III

(OP)
I would think that by 'skirting' current code requirements, they could be opening themselves to a bunch of litigation.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

But if the "skirting" is acceptable to local authorities, that causes a problem with the lawsuits. The capitalists can say that the City accepted the proposal. You likely will have to sue them (the City), too. And so you will have to also confront the might of the Great State of San Francisco.

They accepted the reasoning, did they not, in granting approvals?



spsalso

PS: San Francisco likes "the City" to be capitalized (not sure about the "t"), because it's so very important.

RE: SF Tower settlement Part III

Quote (Walnuts)

but it is the only thing on the books that allows you to skirt the current code requirements.

Classic example of engineering gone wrong - doing what is technically allowable by finding a loophole, rather than what is actually correct.

----------------------------------------------------------------------

Why yes, I do in fact have no idea what I'm talking about

RE: SF Tower settlement Part III

Wait for ab emergency declaration to be made so that no laws apply anymore.

RE: SF Tower settlement Part III

Our far does it have too go before it gets to that emergency point? Presume there is a cut out angle when it will have to start demolishing it.

RE: SF Tower settlement Part III

(OP)
With a seismic event and the type of soil, it may not be that gradual, I suspect.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

Millennium Tower Fix to Reverse About Half the Tilting Triggered During Project, Model Predicts

Two new reports from NBC Bay Area's Jaxon Van Derbeken.

RE: SF Tower settlement Part III

The Tilt-O-Meter says the building is still tipping. More. And more.

I assume this "rebound" will take effect after they finish the work. Apparently in the Spring. Which lasts until June 21.

The big thing here is that they say they won't right the building. I definitely saw drawings showing hydraulic jacks in there, somewhere. Seems to me you just keep putting shims in and readjusting the jack until the build is vertical again.



spsalso

RE: SF Tower settlement Part III

Ha ha ha! The load transfer to the new perimeter piles is applied through hydraulic jacks but that is to limit the loads applied to both the mat and the mat extensions (so they don't crack up) and the piles (so they don't buckle). But the building is far too heavy for the jacks to actually lift it! Likely what is going to happen is that in order to limit the load in the jacks they will have to back off the load frame and the build will continue to settle and tilt. No-one knows for sure - it is impossible to calculate accurately - but at least some pretty smart people think that there will be even less recovery of tilt than the design team is predicting and continued settlement. Part of the thinking is that everything this design team does goes wrong and that is not going to change!

RE: SF Tower settlement Part III

"But the building is far too heavy for the jacks to actually lift it!"


Hmmmm.

First, you only have to lift half of it: 686,000,000 lbs / 2 = 343,000,000 lbs

Then you assume a typical hydraulic pressure of 10,000 psi

343,000,000 / 10,000 = 34,300 square inches

If you use a jack with a 5" diameter piston, it is 20 square inches

So you need 1715 jacks

If we assume the jack base is 1 foot square, then you can get 100 in the length of the short wall of the tower (I believe it's about 100 feet long).

1715 / 100 = 17 rows of jacks, 100 in each row

Of course, you probably would also want so in part of one of the long walls. So put jacks under 100' of THAT wall, too.

Then you only need 9 rows.




spsalso

RE: SF Tower settlement Part III

Ha ha! But what do the jacks push against? !8 24-inch diameter pipe piles?

RE: SF Tower settlement Part III

I guess they'd have to. There would have to be "adapter plates" above and below the jacks.

It appears they did not design in any way to do something like this, even though it appears feasible.

A person could wonder why they didn't bother. Especially if they owned a unit in the building.


spsalso

RE: SF Tower settlement Part III

40kpsi jacks are standard fare in the power transmission sector. We use them for fastener tensioning and coupling mounting.

RE: SF Tower settlement Part III

(OP)
... so you only need 400 or 500 jacks. That's an improvement?

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

From a coat perspective, yes.

RE: SF Tower settlement Part III

Hydraulic Flat Jacks have capacities up to 1000 tons.

RE: SF Tower settlement Part III

From ENR California today looks like just coping Ronald O. Hamburger post

NEWSPROJECTSCALIFORNIACALIFORNIA CONSTRUCTION NEWSCONSTRUCTION METHODSBUILDINGS
Building Repairs
First Load Transfer a Success at Troubled Millennium Tower in San Francisco
By Nadine M. Post
If all continues as expected the saga of not just the fix, but the fix of the fix, for the troubled Millennium Tower in San Francisco may be over by the end of September. The team for the revised perimeter pile upgrade—intended to stem and recover some of the settlement and tilt of the 645-ft-tall tower—reached a milestone last week. Workers from AECOM’s Shimmick Construction successfully completed the initial stage of the transfer of loads from the residential condominium—which has been settling since its completion in 2009—to six new piles to bedrock installed along one side of the building.

“Our expectation was that this first small stage of load transfer would slow substantially, if not stop, the already recently reduced rates of settlement and tilting that has been occurring,” Ronald O. Hamburger, the consulting principal with Simpson Gumpertz & Heger (SGH) who is the engineer-of-record for the upgrade, wrote in a Jan. 29 progress report to the board of the Millennium Tower Association. “Preliminary data shows this has been successful and exceeded the engineering team’s projections.”

RE: SF Tower settlement Part III

NBC Bay Area's Jaxon Van Derbeken reports on the loading of piles on Mission St. with brief commentary by Harry Poulos, PE.

RE: SF Tower settlement Part III

NBC Bay Area's Jaxon Van Derbeken has a new report concerning the seismic review of the upgraded Millennium Tower. Questions remain...

RE: SF Tower settlement Part III

The Millennium Effect or The Leaning Tower of New York City

The Real Deal: Nearly all prospective buyers have backed away from a troubled development site near the South Street Seaport, where a still-unfinished condo tower leans slightly to the north.

I'm being speculative here, regarding 'The Millennium Effect' but if the foundation problems are the cause of buyers pulling out of unit reservations for Lower Manhattan's 161 Maiden Lane, it doesn't seem to bode well for current owners of units in the Millennium Tower, as to resale value and time spent on the market. Too much bad news.

Since there is very little that is known, as to the cause of the tilt, it is perhaps too early to give this an Engineering Failure & Disaster thread.

RE: SF Tower settlement Part III

I'm not seeing how the "boding" transfers from New York to SF.

"I was gonna buy this condo in Millennium Tower, but that one that's tipping in New York just makes me nervous."

You weren't nervous ALREADY?

spsalso

RE: SF Tower settlement Part III

Likely of interest:

Josh of the YouTube Building Integrity channel's recent video -- "Did I Uncover a $100,000,000 Mistake with the Millennium Tower "Fix"?" " https://www.youtube.com/watch?v=Xezg8PxVSYA.

Josh critiques the rather small plates at the bottom of the threaded rods in the jacking assembly atop the added piles. They look likely to be considerably too small to distribute the load, or even withstand the load. Josh could not find any calculations pertinent to them. And how does the rationale for the fusibility of the "fuses" make sense?

RE: SF Tower settlement Part III

I'm confused by his explanation. I understand why you don't want the pile to be tied into the rebar raft but I don't understand why you don't want the Bars to be connected to the rebar raft (floor of the vault) it seemed like everyone had to be the strongest connection and actually don't see a reason for them to not be connected all the way through their threads. Am I missing something? That would certainly help overcome the problem he discussed in the video.

RE: SF Tower settlement Part III

Mark,

I think perhaps it's because the threaded rod is designed to stretch. If the length that is in the concrete were bonded to it, that concrete connection would likely fail. So they work around that by NOT bonding the concrete to the rod. Only the steel plate is connected to the concrete.

Yeah, the plates look awfully small. But if you made each plate twice as big, would the added "outer edges" really be transferring much load? I dunno. But I do wonder.

As Josh was talking, I was waiting for the part where he or they thought that the steel plate embedment was so important that they actually built a REAL test piece and tried it out. In concrete. It appears it wasn't done. If it HAD been done, they could just point at it and say "Yeah, it works. Look over there and check it out." Didn't do it.

Meanwhile, over on the Tilt-O-Meter, things are sure interesting. Maybe confusing, too? Maybe it's working? Maybe it's not?

Tune in next week, kids.


spsalso

RE: SF Tower settlement Part III

(OP)
I'm not sure of his credentials, or the design connection capacity. For bolt tension capacity, the Canadian code capacity is determined by Ultimate Strength and not yield... I suspect the AISC is the same. I was not impressed with his discussion about fasteners being designed for yield. Maybe snakeoil.

I'm not sure how the plate was designed, but I suspect it is compact enough that it would be the bearing on the concrete that determines the load capacity based on the area of the plate, less the area of the rods, times the confined concrete compressive strength, which can double the bearing capacity. With the size of the nut underneath the plate, shear strength of the plate would not enter into it, I don't think.

I'm pretty sure that this was not overlooked. Because it's so critical, I would not design this tightly, but I would be confident of it's capacity if that approach was used. I would think that a high concrete f'c would be used, but I hope they didn't use 25MPa.

I should have added... I think the project has some serious problems... including this guy.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

I guess the sticky part of this threaded rod connection is: how can you limit the load to 1300 kips? The building weighs a whole lot more, at 686,000 kips. So those new piles kinda sorta maybe have to hold up half of that. 686,000 / 18 = 38,111. Which is a tad more than 1300.

So, potentially those supports will suck up that much and then fail if loaded more. I think I'll stand on the uphill side as that day approaches. Ron, on the other hand, had better be downwind!


spsalso

RE: SF Tower settlement Part III

(OP)
My biggest concern about their manner of remedy is that it non-symmetrical. I've done very little seismic stuff, and none recently, but I suspect strongly that cannot be good.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

(OP)

Quote (I guess the sticky part of this threaded rod connection is: how can you limit the load to 1300 kips?)


With hydraulic jacks, I think it's pretty easy to load, monitor and maintain a load of that magnitude to a reasonably accurate value. I don't think the loading is an issue...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

What happens to those jacks when/if the downward pressure of the building goes over the 1300 limit? In my experience, you can't hold something up with less force than it exerts downwards.


spsalso

RE: SF Tower settlement Part III

(OP)
It doesn't... with hydraulics it's easy to regulate the pressure.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

Thing is, if you raise the pressure in the jack to counteract the increased pressure of the building, that same increase also goes down into the piles.

If you decide to raise the pressure in the jack above the weight input of the building, it will rise and/or the pile will lower. If the pile is on bedrock, it has nowhere to go except sideways.

Anyway, it's an interesting show to watch.

What would be nice is to add the pressure readings on the jacks to the Tilt-O-Meter.


spsalso

RE: SF Tower settlement Part III

(OP)
I'm missing something here... you stablilse the load at 1300K. If it's less than the actual reaction, it will tend to lift the building until the 1300 load is reached. If the required reaction is greater than 1300K... you can maintain the 1300K and the building will continue to settle less quickly.

Quote (What would be nice is to add the pressure readings on the jacks to the Tilt-O-Meter.)


They can be set at a constant pressure and easily maintained at that pressure... kinda boring. What would be interesting would be to see the effects of the 1300K load... either up, down, or staying the same.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

But the whole point is to not overload the piles. I think. There's supposed to be a maximum load of 1300 kips.

If you have to raise the pressure to account for the increased downward force from the building, that downward force still HAS to be passed through to the piles. You can't lessen that.

A problem seems likely when/if the downward force of the building overpowers the support ability of the 18 piles.



If I jack up my car using a hydraulic jack (as my father DID do, a few times), I lift up a corner of the car, off of the ground. If the downward force from the car is 1000 pounds, then the base of the jack pushes downwards on the ground 1000 pounds. If I pump the jack, I raise the internal pressure in the jack. But the car still pushes down at 1000 pounds. And the jack still pushes down 1000 pounds.

Pumping the jack handle may well move the car, but it does not change the downward force of either the car of the base of the jack. Which must be equal.


spsalso

RE: SF Tower settlement Part III

(OP)
...but if the load applied to the pile by hydraulics is greater than the actual load from the building, it will have a tendency to raise the building at that point... for better or for worse, I don't know, but I suspect if something doesn't fail, it will be for the better. The problem with moving something that has moved over a period of time is that there can be unintended consequences... often find that happening with historic brickwork. If you put more force on the jack than the car does... the car accelerates upwards. In this case, the building will accelerate upwards, albeit slowly.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

I think one point of confusion about the jacks is that dik is saying on this kind of jack you can set a hydraulic pressure that should be maintained, which translates to a force that the jack applies. This differs from a commonplace car jack, where you pump the fluid in to raise the car, then close the valve, whereupon the jack becomes a solid object (more or less)... unless an excessive load blows a seal in the jack.

So in the Millenium Tower jacks, these become devices to apply a calibrated force to the building, while allowing the building to react by rising, staying stationary, or continuing to sink, albeit at perhaps reduced rate.

Do I have that right?

RE: SF Tower settlement Part III

That has been my understanding. The jack pressure can be varied to maintain the max 1300kip load.

Another thing being forgotten in this conversation is the built in fuse system. Loads over 1300 Kip would fail the fuse to limit the load on the piles and mat. See Pyke’s paper posted by Walnuts Jan 7.

RE: SF Tower settlement Part III

What I missed is that there are (staying with the easier for me to visualize car jack) TWO jacks involved. There's the old original one that has a bit of a leak in a seal (thanks gwideman). So it's slowly sinking. "We" figure if we take some load off the jack, the leak might stop. So we add another jack. It's only a small jack, and can't take the full load. However, we pump it up to slowly take just SOME of the pressure/weight pushing down on the other jack. And because we have a pressure gauge and an underpaid apprentice to watch it, that allows us to put in just the right amount of lift to take some load off of the other jack, while not blowing out.

The TOTAL downwards force of the car (building) remains the same (until you fill it with helium). But it's now distributed differently.

This fuse thing. Looking forward to learning more about that. Unlike a circuit breaker, a fuse is a one-time thing. So it seems that if the fuse "blows", the whole Fix is then disconnected and totally useless. But expensive.


spsalso

RE: SF Tower settlement Part III

(OP)
almost, except the small jack, has to be as large as the big jack... thanks for the explanation gwide... I hope it works, but don't know. The US does not need to rival Pisa with a Leaning Tower, albeit a tad bigger. Actually the Pisa Tower was leaning as it was constructed... maybe this one was too.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

Spalso: you said: "What would be nice is to add the pressure readings on the jacks to the Tilt-O-Meter." For some weeks they have been shown on page 24 of the Tilt-O-Meter. Separately, in a presentation developed by the SGH staffer who actually does all the work, developed I assume for the EDRT, it is explained that after increasing the load in the jacks in five increments to approximately 550 kips, the jacks were "locked off", likely just by closing a valve in the hydraulic system as someone has mentioned above, because the same presentation does not appear to show any mechanical lock off mechanism. Key photos from this presentation are included in Josh Porter's YouTube video. Interestingly, the loads measured by the load cell then dropped off over a couple of weeks to something less than 500 kips. At the request of Jaxon van Derbeken, Hamburger was asked about this by the DBI, and he basically said that this was all as expected, which was of course blowing smoke. A smart structural engineer friend of mine who has long experience with large diameter steel pile as used in offshore applications, has suggested that this fall off in the measured load likely results from some load redistribution down the pile below the bottom of the casings at about 100 feet. With the installation and load application sequences that they used, the piles likely had some resistance in skin friction in the 100 feet of so interval of Old Bay Clay when the loads were first applied, but this would "relax" over time (because the platy clay minerals relax) and more of the load is carried in the Lower Alameda formation, and maybe the "bedrock", although I doubt that much of the load actually gets to the bedrock. This would cause minor shortening of the piles since a greater load would be carried through to 100 feet of Old Bay Clay. Since, as noted above, the jacks are now more or less rigid, this slightly reduces the load. By itself this should not have a big effect on the Tilt-O-Meter because it appears that excavation of the trench along Fremont Street (now completed I think) and the water table going up and down, and, most importantly, some bending upwards of the edge of the mat, have more effect. Overall, it is a very complicated system and no matter how many Ph.D.'s you have doing calculations, it is all a bit unpredictable. We will have to wait a couple of months for the water table to stabilize to see what the more permanent effects are, but it seems more than likely that any recovery of tilt is going to be only a small fraction of the additional tilt that they have caused by careless construction practices.

RE: SF Tower settlement Part III

Ah, the "fuses". More research pretty much says the threaded rods are the "fuses". They're supposed to break if the pressure down towards the piles gets too high.

What's the plan for when/if the "fuses" break? It surely looks like the "fix" is over, since the "fuses" connect the piles to the foundation. No fuses--no connection.

Just wondering.


spsalso

RE: SF Tower settlement Part III

Spsalso: the threaded rods are supposed to be very stretchy, and they may not actually break even in a major earthquake. It is possible that the rods would pull out first, as suggested by Josh Porter. But the bigger problem is that no-one knows. As far as I know the design team has a fancy structural model, but they have never applied vertical excitation to it. I think the Hamburger just refers to the current minimum code requirement of applying a nominal static vertical load. It does make you wonder.

RE: SF Tower settlement Part III

There is a simple reason the current design is probably O.K. The six piles that are completed on Mission Street have been tested to a certain load resulted in the reduction of Millennium Tower's tilt. See Figure No: 099-06A of the Millennium Tower weekly report.

RE: SF Tower settlement Part III

(OP)
The fact that it is settling so much is not a good sign. In addition, I don't know what effect the eccentric support will have during a major seismic event. In particular, the supporting soils have a high risk of liquifaction during a major seismic event. I'm not so confident myself... but I'm not really experienced in seismic events.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

Hmmm. It is true that the tilt to the north has been very slightly reduced, and the tilt to the west even less, but this appears to be largely because the north-west corner of the mat has been bent up a bit. But the original point of the Fix was to obtain a significant recovery of the tilt and any recovery to date is just a tiny fraction of the additional tilt that has been caused by inappropriate construction techniques. I don't think this is OK!

RE: SF Tower settlement Part III

Has any of the post-construction effort indicated an end-all-be-all tilt that absolutely cannot be hit? Obviously the current status is not what you want out of a building, but at what point does this transform from a major screw-up to an extreme safety hazard that could warrant teardown? I know that's not likely to happen, just want to gauge the scale of the tilt-o-meter graphs to see what the target final tilt is. (Just reading through the thread now, I haven't been following the story too closely).

RE: SF Tower settlement Part III

The Tilt-O-Meter is currently "flat lining", so your question may be moot.

But it IS a good question, one which I am curious if the San Francisco Building Department has ever considered. And what their conclusions might be.

In a reflection on the ka-wality of design and construction for this building, note that Millennium Tower is one of the buildings that had windows blown out in the windstorm of last month.


spsalso

RE: SF Tower settlement Part III

(OP)

Quote ("flat lining")


That's great, now to address any seismic issues.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

Not just the seismic issues. The tilt is now significantly worse as a result of inappropriate construction procedures and so far the "rebound" that the design team had predicted does not seem to be happening. So, you still can't practice your putting in your multi-million-dollar condo! And, while no-one knows for sure, there are some reasons to expect that long-term settlement and tilting will resume.

RE: SF Tower settlement Part III

Has it been considered that rather than stopping the settlement, they may be controlling the settlement?
If they new system provides enough support in addition to the original foundation piles that may be enough to stop settlement.
If the down hill side is pressured to the design maximum, but the up hill is held at quite a bit less pressure, they may be able to let settlement on the up hill side to right the building.
Once the building is vertical, the hydraulic pressures may be equalized.
If the building continues to settle, albeit much more slowly, the hydraulic pressures may be balanced to keep the building vertical.
If the intent is to slow and control further settlement, the system may work well.
But, what do I know.
Hoping for comments if my simplistic thoughts are too simplistic.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

RE: SF Tower settlement Part III

waross, your thoughts are not too simplistic, but the history of this fiasco is complex! Originally the design team said that after they propped up the north and west sides of the Tower, the south and east sides would continue settling and in something like 8 years the building would be level. Then they switched to saying that when some of the load was transferred to the perimeter piles, the south and east sides would "rebound" in the short term before overall long-term settlement resumed. But the only thing that can be said with certainty is that no-one knows!

RE: SF Tower settlement Part III

(OP)
Did they ever determine if the original foundation was OK to start with?

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

I think that determination has been well and truly made, by the performance of the building.

RE: SF Tower settlement Part III

(OP)
Sorry hokie... not quite what I meant... was the original design predicated on 'real engineering'? or was there an error? From the end result, it's obvious that something else happened... it's like the Transcona grain elevator issue... as my late thesis advisor said, "Russia knows that Winnipeg is slightly west of Transcona."

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

I did not know of Transcona, but righting that structure was impressive.

RE: SF Tower settlement Part III

(OP)
Yup... and it's still there... or one similar to it. I haven't done a search for it... but I suspect Transcona will give you more hits. There used to be a large photo of it on one of the walls in the old engineering building at U of M. I think it was the first recorded failure in the mode suggested by Terzahgi.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

A paper on Transcona grain elevator. That was a massive chunk of concrete to tilt. From page 804, clay depth of 52 to 55 feet generally except a ridge of boulders up to 12 feet high along the east edge. As the structure was filled with grain, the settlement became uneven and the clay started to flow.

RE: SF Tower settlement Part III

(OP)
As hokie noted, righting it was quite a feat... I didn't know there were boulders on the east edge.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

Dik, in answer to your question about the original design: clearly there was an error in it! The design likely may have worked for the original steel-framed structure with 4 or 5 basement levels, but then they switched to a concrete frame and moved the basement parking to the adjacent building. At that point it should have been obvious that the Old Bay Clay, which starts down at 100 feet, below the sand layer in which the piles are tipped, would be pushed back on to its "virgin consolidation curve". Only recently I saw the calculation made by the original geotechnical firm which way underestimated the potential load on the Old Bay Clay. I don't know whether that was just an honest mistake or whether it was done intentionally to justify not switching to piles to "bedrock" since time pressure was driving all these changes, but regardless, it was a bad mistake.

RE: SF Tower settlement Part III

(OP)
It was not an unusual experience, then. The Transcona grain elevator failure was a new thing, and not anticipated...thanks, Walnuts

I'm not big in seismic, but one of my biggest concerns would be the liquifaction of the founding clays/fill.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

Hi all,

Not structural but have been following this thread with a sort of macabre fascination.

I have a question: Assuming the building is righted, surely by reason of it's history it has already become unsellable?

Politicians like to panic, they need activity. It is their substitute for achievement.

RE: SF Tower settlement Part III

Units are sold, not the building. If you lower the price enough, they will sell.

Between this and the windows failing, the design and construction quality could certainly be brought into discussion, and well could get new purchasers wondering at other unfound failings. Not to mention the found ones required to be reported to the buyer by the seller. These could be bargaining points for someone considering purchase.

I believe there have been insurance payouts to assorted persons and entities. Note that it's possible that a payout to an existing condo owner could possibly mitigate or eliminate loss caused by a low selling price.


spsalso

RE: SF Tower settlement Part III

Spsalso, the homeowners who participated in the lawsuits each received approximately $1 million under the settlement agreements. That might have made them happy at the time, but they were also promised a Fix that would work, so I guess that they are now longer so happy. But the $1 million each is an important part of the story. That is why the board of the HOA signed off on the Fix, and likely is why the four engineers who now comprise the EDRT and the DBI also signed off on it, because they didn't want the deny the homeowners their million bucks. Because they signed off on it, they now do not want to admit that they made a mistake. But now there is another problem. Because of first Covid and now layoffs in the "high tech" segment of the economy, demand for expensive housing in downtown SF has fallen quite a bit. Both Google and Facebook had built up large staffs in SF. Even before that, sales were slow to non-existent because sellers could not get their asking prices.

RE: SF Tower settlement Part III

(OP)
Is there any sort of mechanism in place that prevents condo unit owners getting 'stuck' with the repair bill?

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

Dik, the settlement agreements provided $100 million for the Fix and certain other repairs and upgrades. Also, Millennium Partners, the original developer, took out bonding / insurance policies on the design team and the contractor. All that to protect the homeowners from future assessments to pay for the Fix. How that is working out I don't know, but as a minimum I can see future lawsuits from the insurers to recover the monies that they are reportedly paying out because of the incompetence of the design team and the contractor. And the homeowners are going to be left with a tilting building!

RE: SF Tower settlement Part III

The joy of buying units. When things go wrong, all suffer.

RE: SF Tower settlement Part III

Just FYI - last Friday the Wall Street Journal included in their Friday "Mansions" section a unit from this tower - top floor I think. The guy paid $13 million for this top floor penthouse and is now asking $14 million. Apparently he purchased the unit AFTER all the news came out about the leaning/sinking, suggesting in the article that he could make some money once the problems were solved.

I'm not sure a $1 million profit is anything to scoff at but if you read the mansion section you see all sorts of houses going for 20, 30, 100 percent more than paid for a few years ago. Going from 13 to 14 million doesn't seem like much of a profit considering the risk.

RE: SF Tower settlement Part III

@JAE Probably not much better than just breaking even after legal fees, condo fees, taxes, etc are deducted. With high interest rates, possibly even effectively a small loss.

RE: SF Tower settlement Part III

Is it just me or does 0.25" at the foundation seem like more than what the top moved because of the distances involved? It's still tilting more and no matter how you look at it!

RE: SF Tower settlement Part III

(OP)
Still no soft cushy feeling... the 1/4" could be thermal for a building of that height... I think foundation based settlement measurements would be more appropriate... Whatever method, if they are not done correctly have about equal parts validity. I like Pike's comments, but this is a bit out of my league...

If it has to be razed, are the condo owners on the hook? including the cost for demolition?

With buildings, it seems if they fall down and kill people, those responsible are never charged.


-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

Isn’t that a worry if the building’s still moving but the new footings aren’t?

RE: SF Tower settlement Part III

New Article in ENR. After 15 Years, Settlement Arrested at San Francisco's Millennium Tower

It sounds like the EDRT accepts the work and feels the fix is sufficient. An interesting thing I noted is that Ron Hamburger says that the condo homeowners are the ones who asked to scale back the 52 pile fix. Shifting the blame? I don't recall homeowner input in the reduction of piles but it's been a long road so I could have missed that.

Quote:

"The pile production problems, which were solved, nevertheless “burned a significant amount of schedule and money,” says Hamburger. “The homeowners asked us to scale down the upgrade” to get back on track, he adds."

Quote:

Looking back, Hamburger says the foundation upgrade team, which included the homeowners’ association, the contractor and the designers, was “always able to work together" to figure out the best path forward. “There was never any talk of lawsuits,” he adds. “It all worked well,” in the end.

RE: SF Tower settlement Part III

Like Millionton, I find it very doubtful that the homeowners would request a number of piles being reduced. Why in the world what they want to reduce them and cause potential problems in the future? Do they even have anybody on their board with the expertise to know what's being done? If they did say that I'd be looking very seriously for some kickbacks someplace.

RE: SF Tower settlement Part III

I was pursuing the ASCE Journal of Geotechnical and Geoenvironmental Engineering and saw a free paper published in March on the Case History of the Millennium Tower. It was first submitted two years ago (July 12 2021) so it doesn't capture the recent developments but does describe the foundation conditions and settlement pre-fix. It appears this data was developed during the litigation.

I have yet to really dig into the paper but the conclusion sums it up pretty well in my opinion:

Quote:

Engineering analysis of the case history with 1D and 3D methods demonstrates that the observed settlements were predictable in terms of cumulative amounts and their time variations.

I think they avoid pointing a finger at anything in particular, but this all could have been predicted.

Link

RE: SF Tower settlement Part III

And for the very Nerdy among us, I found a Ph.D. thesis published during earlier parts of the Millennium Tower debacle regarding the engineering properties of the Old Bay Clay.

This link should provide a download, but my work network provides me with a lot of access to journals so I don't know if it is publicly available (it should be). Engineering Properties and Geologic Setting of Old Bay Clay Deposits, Downtown San Francisco, California

RE: SF Tower settlement Part III

Milliontown, there may be some truth to the suggestion that it was the Homeowners who asked for the cut back to 18 piles. Not the Homeowners as a whole, but the board of the Millennium Tower Association, the HOA, who had signed off on the Fix and were running out of the money that they got out of the settlements of the earlier lawsuits. Like the EDRT and the DBI, all the parties that signed off on the Fix had egg on their faces and have just been clinging to it, in the case of the ERDT to line their pockets, in the case of the Board of the HOA, in the vain hope that it would somehow restore property values. Good luck with that! I have heard a rumor that the board members who have overseen this catastrophe are now all quitting or not standing for re-election.

As for ENR, they have always been sucking up to Hamburger because he is a big wheel on the ASCE and other code writing committees. Perhaps this is more proof that those who can do, and those that can't teach or write codes?

As for whether the tilt has been stopped or reversed - certainly it has been slowed down and in the short term reversed a little, but it is too early to tell what will happen in the long term. But it already seems clear that the short-term reversal has been only a fraction of the additional tilt caused by the Fix! If anyone-else implemented a fix to reverse the tilt of a building and ended up increasing the tilt, they would be sued to high heaven. But in this case the prior settlement agreements basically leave that up to the Board of the HOA, so it will be interesting to see how that all works out.

RE: SF Tower settlement Part III

And another video about this interesting example of engineering:

https://www.youtube.com/watch?v=PwgwTtpPB0o

Let's not forget that Ron Hamburger said: "The required construction is neither complex nor unusual."

And he oughta know!



spsalso

RE: SF Tower settlement Part III

(OP)

Quote (Let's not forget that Ron Hamburger said: "The required construction is neither complex nor unusual.")


They need a 'Sarky' font...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

Funny how Hamburger always defended their calculations and said that the Fix was neither complex nor unusual, but is now using complexity as the excuse for being so far off on their rebound calculation! Ha ha ha ha ha! And curious how the DBI and their supposedly expert panel have never admitted that the Fix has made things worse, rather than better!

RE: SF Tower settlement Part III

(OP)
A whole lot of information at:

http://www.lbkarp.com/mi.html

If this project turns south... this could be a valuable source of information.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

Thanks for posting that information. I wasn't aware of the exposed rebar in the garage area.Thanks for posting that information. I wasn't aware of the exposed rebar in the garage area.

RE: SF Tower settlement Part III

Who used the term "caused construction"? This whistleblower doesn't seem credible at first glance.

RE: SF Tower settlement Part III

(OP)
He might not even be an engineer; he doesn't have to be.

The way things are unfolding with that project, it's possible that there could have been a little collusion. There is something really broken here. In the event, and I don't know the likelihood, the tower has to be razed, I suspect the condo owners will be responsible for the costs. The developer gets away Scott free. To reiterate, there is something really broken here.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

Do you think any highrise construction project occurs without collusion? Isn't that the point of such construction is to secure government grants?

I don't understand, though. Collusion in that sense shouldn't impact the quality of the project. Nobody colluded to make the building lean.

RE: SF Tower settlement Part III

(OP)
I've been involved with lots of them... (not really high rise but less than about 30 stories) and no collusion. Maybe the threshold is 31?

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

No subsidies? No clearing of red tape? No preferred contractors? Nothing? That is good to hear.

RE: SF Tower settlement Part III

(OP)
Even where projects are pre-qualified. There is a set criteria established and everyone is compared on that basis with numeric values established. This is provided at tender time. I've never encountered a 'shifty' plan examiner... other than one instance for a project outside Ottawa. The project manager didn't believe I needed rock anchors. He was friends with the building inspector and the building inspector asked for my design notes... The rock anchors stayed. The only change was the the CBO wanted the top of the rock anchors 'sleeved'. They were not pretensioned so it made little/no difference if they were sleeved... I just sleeved them.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: SF Tower settlement Part III

Quote (Dik )

I wasn't aware of this whistleblower...

The self-described 'whistleblower' is wrong. Yes, plywood cushions were used but the rebar and strands exiting the top of the piles were protected by a 20 foot long follower. I'm sure it was a pain to work with in the muck. Probably why the pile driver went broke.

RE: SF Tower settlement Part III

Would the plywood cushions be on top of the follower?

RE: SF Tower settlement Part III

Quote (Cool Controls)

Would the plywood cushions be on top of the follower?

No, the plywood cushion was a biscuit in the middle of the ring of reinforcing exiting the top of the pile. Once the follower enters the ground, there is no changing out the cushion.

RE: SF Tower settlement Part III

Quote (TugboatEng)

Do you think any highrise construction project occurs without collusion?

The construction industry is not the high-margin palm-greasing money factory it is in the movies

Quote (TugboatEng)

Isn't that the point of such construction is to secure government grants?

Uh... no.

Quote (dik)

I've been involved with lots of them... (not really high rise but less than about 30 stories) and no collusion. Maybe the threshold is 31?

"High Rise" is a non-ambiguous term.. it's very clearly defined. 30 stories is way, way beyond the threshold.

RE: SF Tower settlement Part III

Quote:

The construction industry is not the high-margin palm-greasing money factory it is in the movies

I'm shocked, shocked I tell you.

This seems to be at the opposite end; so desperate for work they chose the most stupid of shortcuts, trying to float a building 5X heavier for the footprint than the neighbors onto a sea of muck because to do it right was far more expensive than what the seller was willing to pay. As usual, physics beats any plan or contract if allowed the chance.

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