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SF Tower settlement Part III
7

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

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

3
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.

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