SF Tower settlement Part II 18

[1503-44]

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

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

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

 

[dik]

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

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

-Dik

 

[Student Forever]

Here is the Karp-Kardon report from 2019 predicting what's happening to the tower now:

http://www.lbkarp.com/mi/Millennium Report 7-10-19c.pdf

He and Kaplan wrote this report for the City of San Francisco in 2019.

He was interviewed recently here:

https://www.nbcbayarea.com/investig...wer-upgrade-would-make-tilting-worse/2642033/

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

His firm's site here:

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

has many important Geotech reports , photos, etc on the piling solution.

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

 

[Student Forever]

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

Do you know that this Berkeley Professor who is probably the most responsible person for this fiasco blames God for it. See the 2017 story here:

https://www.nbcbayarea.com/news/loc...-for-sinking-millennium-tower-says-god/36922/

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

 

[dik]

sad...

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

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

-Dik

 

[apper.42]

Actually the majority of the tilt is to the West

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

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

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

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

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

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

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

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

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

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

 

[dik]

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

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

-Dik

 

[dik]

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

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

-Dik

 

[spsalso]

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

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



spsalso

 

[apper.42]

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

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

Link to more info :

https://www.eng.uwo.ca/news/davenport.htm

 

[Student Forever]

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

 

[apper.42]

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

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

 

[Student Forever]

Here is a great article:

"The man who saved the Leaning Tower of Pisa, By Andy Pearson 14 September 2000" with this link:

https://www.building.co.uk/focus/the-man-who-saved-the-leaning-tower-of-pisa/1455.article

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

Part of the story quotes him as :

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

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

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

 

[dik]

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

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

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

-Dik

 

[Student Forever]

Anyone interested, here is a paper by Prof. Burland on stabilizing Pisa Tower. The photo below is from this paper.

https://scholarsmine.mst.edu/cgi/viewcontent.cgi?article=2604&context=icchge

Best

 

[dik]

Thanks...

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

-Dik

 

[Student Forever]

Apparently, for the Pisa Tower also, a sudden tilting has occurred due to disturbing the soil on the leaning side by the Architect causing the suden leaning. Please see the highlighted part below (from the same Burland Paper

https://www.building.co.uk/focus/the-man-who-saved-the-leaning-tower-of-pisa/1455.article.

 

[epoxybot]

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

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

 

[Enable]

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

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

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

 

[dik]

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

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

-Dik

 

[epoxybot]

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