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"

 

[spsalso]

Loved the interview with Ms. Guglielmo.

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



spsalso

 

[epoxybot]

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

Here is a complication regardless of remedial scheme.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

 

[Student Forever]

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

https://sanfrancisco.cbslocal.com/v...san-francisco-sinking-skyscraper-put-on-hold/

 

[Student Forever]

https://youtu.be/H80mAhGagFw

 

[Student Forever]

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

 

[dik]

Thanks... no cause for alarm...

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]

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

 

[Student Forever]

MILLENNIUM TOWER
SF Official Seeks Hold on Troubled Millennium Tower Fix
By Jaxon Van Derbeken • Published September 10, 2021 • Updated on September 10, 2021 at 8:17 pm

https://www.nbcbayarea.com/investig...old-on-troubled-millennium-tower-fix/2653243/

 

[Student Forever]

It is interesting to go back and watch this CNN (

https://www.cnn.com/2021/07/05/us/san-francisco-millennium-tower-sinking/index.html)

in June which had a title of " Surfside catastrophe raises concerns about San Francisco's sinking Millennium Tower".

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

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

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

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

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

 

[apper.42]

Thanks... no cause for alarm

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

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

 

[AusG]

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

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

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

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

(C) AusG 2021, invoice in the mail.

 

[TugboatEng]

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

 

[dik]

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

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

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

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

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

-Dik

 

[dik]

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

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

-Dik

 

[TugboatEng]

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

 

[dik]

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

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

-Dik

 

[TugboatEng]

Buildings can be condemned before they collapse.

 

[dik]

Worked really well in Florida...

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

-Dik

 

[Student Forever]

Two questions:

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

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

 

[hpaircraft]

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

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

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

Edit Add: Or like this:

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