SF Tower settlement Part III 18

[dik]

thread815-412357
thread815-470048

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

-Dik

 

[Sym P. le]

Or things are breaking.

 

[Walnuts]

More from the tilt-o-meter:

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

 

[dik]

Interesting localised 'dip'.

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

 

[spsalso]

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

 

[dik]

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

 

[spsalso]

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

I wonder why he would change his approach now.


spsalso

 

[dik]

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

 

[dik]

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

 

[epoxybot]

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 towerodium 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.

 

[AusG]

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.

 

[Walnuts]

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.

 

[dik]

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.

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

 

[Walnuts]

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

 

[hamjohn]

Following is a link to a report mentioned epoxybot on pages 52 to 57.

https://drive.google.com/file/d/1S1MX5Rf8b8bLw48IWLyBJv26ZajEB2WT/view?usp=sharing

 

[ti89t]

@epoxybot

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

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

Thanks in advance

 

[AusG]

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.

 

[Cool_Controls]

Link

 

[spsalso]

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.

 

[pellucidar]

@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.

 

[dik]

That's reassuring.

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