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]

That SEAONC has not commented on her statement is tacit approval... which is even worse.

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

-Dik

 

[spsalso]

Some may view it as "extremely reckless and inappropriate" to have built a building that is falling over, and not being able to fix it.



spsalso

 

[dik]

...and perhaps a little unprofessional?

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]

The "Hamburger solution" results in asymmetrical support to bedrock on two sides of the building which means that lateral shaking in any direction due to earthquake is going to lead to the c of g of the building moving eccentrically to the hard support from the piles to bedrock. The resulting torque on the building would probably be well above any design torque because of the sudden change in foundation conditions. The natural frequency of the building due to torsion will probably be totally different than due to lateral loadings and any damping built into the building probably is not designed for high twisting of the building. From almost any source, uneven foundation support is a no-no in high earthquake zones due to unpredictable torsional effects. The diagram in the link is my attempt to show the uneven support and tendency to cause excess torsion in the structure. This could cause irreparable damage to the building if not specifically checked for this. Not sure my link is working correctly.

 

[Student Forever]

Here is from SEAONC website:

"[SEAONC] Mission: To advance the practice of structural engineering, to build community among our members, and to educate the public regarding the structural engineering profession.

Vision: A world in which structural engineers are valued by the public for their contributions to building a safer and stronger community."

It looks like for the Millennium Tower, SEAONC has failed in every aspect of the "Mission" statement, and for the "vision", by not making any statement on Millennium Tower's sickness, The current SEAONC President Moore has gone blind and does not see, and the past SEONC President Guglielmo, has gotten blurred vision. Know a good eye doctor to recommend to them? If you know, send the name to SEAONC Directors too.

By the way, it is not just SEAONC in northern California, that has failed so far in its Mission and lost its Vision at least in this case. Has anyone heard anything factual from the other three local structural engineers associations in Califonia (SEAOSC, SEAOCC, SEAOSD)? SEAOC (the umbrella organization) has also settled (no pun intended) in deadly silence on MT settlement.

In its SEAOC Strategic Framework posted here: P

https://cdn.ymaws.com/

http://www.seaoc.org/resource/resmgr/files/SEAOC_Strategic_Framework_20.pdf

, it has the following under [SEAOC] Values:

"Values:
• Practice:
o Technical development and advancement of knowledge
o Structural engineering excellence
o Professional ethics and integrity
o Sustainability and resilience

None of the above is practiced in Millennium tower by those who caused this failure, all are SEAOC members, some even leaders, and senior members. They are saying to junior members: "Do as I say, not as I do". The quote first appeared in print in 1654: “Preachers say, do as I say, not as I do” (John Selden, Table-Talk: Preaching ). Parents have been saying it to children ever since.(from:

https://idioms.thefreedictionary.com/do+as+I+say,+not+as+I+do)

 

[Student Forever]

Warnings About San Francisco Millennium Tower Repair Plans Raised Before Work Began

https://sanfrancisco.cbslocal.com/2...millennium-tower-warnings-repair-leaning-fix/

 

[epoxybot]

Happy Valley 1851 - Yerba Buena Cove Shoreline

 

[Ingenuity]

Warnings About San Francisco Millennium Tower Repair Plans Raised Before Work Began

Guglielmo quote from the sound bite:

“… the engineering techniques are very consistent. We do these on houses in San Francisco all the time. Underpinning, moving loads and foundations is very traditional.”

Okay, so this is simply a very tall house. Nothing to see here. All good

 

[dik]

Ya... really tall...

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]

Ya... really tall

Yes the building is tall 605 ft without the mast but it has a minimum base width of 105 ft so the slenderness ratio is about 5.8 which is well below the 7 that we were taught was about the practical limit (for straight sided buildings). I believe that 605 was the planned height before the 16" settlement. The original World Trade Centre building without the mast was 1368 feet and the base was somewhat more that 200' on each side giving a slenderness ratio of 6.8, close to the maximum that I was taught many moons ago. These newer tapered buildings can obviously overcome this old ratio of 7.

So yes it is tall and fairly slender but Not overly slender. It is however heavy, heavier than any other building in SF with a non bedrock foundation (they are predominately steel). Other buildings with similar foundations exert less than about 3 kip/ft2 on the foundation but Millennium Tower exerts 14.2 k/Ft2 plus approx. 0.7 K/ft2 from the overturning moment due to the lean resulting in almost 15 k/ft2. The pressure from Millennium tower is much higher than the consolidation pressure that was applied the the old bay clay so of course it will consolidate further.

 

[Student Forever]

Where is the Mayor of San Francisco London Breed in all of this? Now we know:

"San Francisco Mayor London Breed seen partying at a nightclub without a mask, report says" Los Angeles Times here:

https://news.yahoo.com/san-francisco-mayor-london-breed-193728496.html?fr=sycsrp_catchall

Why Supervisor Peskin is trying so hard, while Mayor is not settling down from her maskless dance and partying?

She, the elected official charged with the safety of San Franciscans, including those living in the tilting Millennium Tower, also thinks "there is no cause for alarm".

 

[dik]

SF... you just couldn't contain yourself, I guess...

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

-Dik

 

[spsalso]

“The Engineering Design Review Team (EDRT) did receive and review the letters from Karp & Kardon and Dr. Pyke as part of the EDRT’s review of the permit request for the foundation retrofit designed by SGH (Simpson, Gumpertz and Heger). At that time, the EDRT asked SGH to respond to the points raised by the letters about SGH’s retrofit design and the EDRT was satisfied with SGH’s responses to those points.”


Since it's not a matter of national security (Or IS it???), it would sure be swell to see SGH's "response to the points" (mentioned above) and how EDRT expressed their satisfaction.

"Sure. Great charts, nice colors! Let's DO this thing."

Might want to ask if they're STILL satisfied, and if not, what caused their change of mind.



spsalso

PS: My mom would have recommended writing thank-you notes to K&K and Pyke.

 

[dik]

News...

https://www.cnn.com/2021/09/17/us/southern-california-quake/index.html

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

-Dik

 

[hamjohn]

New boring 9/17

https://www.nbcbayarea.com/investigations/millennium-tower-fix-testing-begins/2659964/

 

[epoxybot]

Here is a link to all the bore logs taken so far. They begin on page 52 of the PDF. Treadwell & Rollo's B-4 & Cotton Shires SD-2 are the closest to the current boring operation. SD-2 looks interesting at the junction of the Colma/Marine sands to the Old Bay Clay.
Courtesy of LB Karl's 'Millennium Debacle' webpage.

 

[Walnuts]

In response to spsalso, here are the Hamburger (non-)responses to Pyke's 2019 comments (I am a newbie and not sure how to attach it so I have included it - why it was copied to Naomi Kelley, I have no idea - Pyke says that not only did they not contact him but that he had not seen this until a couple of weeks ago):


25 July 2019

Dr. Gregory Deierlein
318 Parkside Drive
Palo Alto, CA 94306

Project 147041.10 – Millennium Tower, Perimeter Pile Upgrade
Comments from Dr. Robert Pyke

Dear Dr. Deierlein:

This letter responds to comments raised by Dr. Robert Pyke in an e-mail, and attached memo, forwarded by the City Attorney’s office to Mr. Peter Meier on 23 July. I prepared these responses in consultation with Mr. John Egan, who serves as my principal geotechnical consultant for our work on this project.

The e-mail raises three primary points associated with Mr. Egan’s characterization of the site and
recommendation of MCER ground motion spectra. Specifically, these are:

1. Characterization of the site as Site Class D rather than E.

This point was extensively reviewed by the EDRT and is addressed in the comment log under comment 34.

2. Use of 80% of the default spectrum specified by the building code, rather than relying on site specific study, noting that ASCE 7-16, which will be adopted by the City of San Francisco in January 2020 will require site specific study.

In the course of their geotechnical study, Mr. Egan and his support team did indeed perform site-specific response analysis to develop a response spectrum appropriate to the foundation level of the Tower. ASCE 7 requires that when site-specific response analysis is performed, the resulting spectrum cannot be taken as less than the 80% of the default spectrum. Mr. Egan’s site-specific response analysis resulted in a spectrum with spectral ordinates generally less than 80% of the default spectrum, but with longer- period (i.e., 2 sec ≤ T ≤ 4 sec) energy content exceeding 80% of the default spectrum; thus, the greater of the 80% limit or the site-specific response study was adopted as the recommended spectrum, as required by the building code. This was reviewed by the EDRT and is logged as comment 3 in the log.

3. Dr. Pyke’s personal belief that characterization of ground shaking at the site using the Vs-30 parameter will underestimate the likely energy content of shaking in the period range 1 to 1.5 seconds. Dr. Pyke notes that Engeo’s proposed design spectrum did have increased energy content in this period.

We note that the building’s fundamental period of response is approximately 5 seconds
and more than 60% of the building’s mass is mobilized in modes that have periods in




excess of 3 seconds. Only 20% of the building’s mass participates in the period range between 1 and 1.5 seconds. Regardless, in the course of our design, we evaluated the building for Engeo’s ground motions as well as those recommended by Mr. Egan. The building performed adequately for both sets of ground motions.

Dr. Pyke’s memorandum dated 17 July raises the following technical points:

1. An allegation that our team purports that a disproportionate fraction of the building’s weight is carried by the perimeter columns, and this fails to take into account the sequence of construction.

We are not sure what Dr. Pyke is referring to. We have never made statements suggesting that a disproportionate amount of the building’s weight is carried by the columns. We independently computed the amount of building weight carried by the individual columns and the central core and compared these with similar computations made by DeSimone Consulting Engineers in their original structural design. Our calculations suggest that roughly 45% of the building’s weight is carried by the central core and 55% by the perimeter columns. This is consistent with distributions of load we have observed in other tall buildings.

2. The suggestion that transfer of 20 percent of the load form the existing piles to the new piles would result in immediate rebound of about 1 inch.

Geotechnical analysis conducted by Mr. Egan and his team confirm that approximately an inch of rebound will occur when the load is removed from the building. We concur that this will not occur immediately, but rather may take approximately 1 to 2 years to occur, consistent with the time-dependent rebound behavior of clay soil when overburden confining stress is reduced. The expression of immediate recovery of settlement alluded to was made in the context of the 40-year period over which our team has evaluated the building’s future settlement behavior.

3. Arresting the settlement of the north and west sides of the building while the center and the south-east corner of the building continue to settle can only increase the stresses in the mat that underlies the building and the outriggers when the mat is already dished and cracked, and the condition of the outriggers is uncertain.

In the course of our design, we conducted extensive analyses of the post-retrofit settlement of the building, and the effect of this settlement on the mat foundation and structure. These analyses suggest that post-upgrade settlement will counter the settlement that occurred to-date and in the process of doing so, tend to relieve, rather than increase, stresses which have accumulated to-date. We have demonstrated through our extensive analyses, reviewed by the EDRT, that the mat is capable of resisting stresses associated with the addition of the new piles, as well as the building’s response to MCER shaking, as specified by the building code.


4. The proposed fix cleverly provides for backing off the underpinning of the north and west sides of the building, should settlement of the south-east corner catch up with and overtake the settlement of the north west corner.

While it is true that the design would accommodate reduction in the amount of jacking applied along the north and west sides, this was never the intent of the pile head detail. Rather, the intent of this detail was to allow jacking of additional force onto the piles if rebound resulted in reduction of the effective jacking force. We note, however, that since the settlement experienced to-date is due to consolidation of the underlying soils, as the building settles, the consolidating soils will ultimately become normally consolidated and the rate of settlement will naturally diminish significantly with time. In fact, this behavior is evident in review of settlement data collected over the past 18 months.

5. The proposed fix creates an asymmetrical foundation which is bad enough under static loads but will create unpredictable and likely adverse response under seismic loads.

The perimeter pile upgrade adds vertical and lateral stiffness and strength to the foundation along the north and west sides of the building foundation. We have extensively and rigorously studied both effects in our analyses of the design. The upgraded building does not qualify as an “irregular” building under the definition of the building code. Further, the building’s response to earthquake motion is superior with the perimeter pile upgrade in place, compared with that of the un-retrofitted building.

6. The proposed fix requires complex and difficult construction on City property which houses many existing utilities and ties backs and will require new dewatering.

The required construction is neither complex nor unusual. It requires installation of drilled piles around the perimeter of the building. Piles of this type are routinely employed in building construction. The tie-backs, which will be cut, were installed to permit the original excavation for the building’s construction. They serve no purpose at this time and were intended to be sacrificial when installed. No dewatering will be required to enable the construction. Ground water will be controlled by soil grouting as has been successfully done in the construction of other nearby projects.

Sincerely yours,

Ronald O. Hamburger, SE Senior Principal
CA License No. 2951
I:\SF\Projects\2014\147041.10-301S\WP\027ROHamburger-L-147041.10.jdi_Response to Comments.docx

cc: Shah Vahdani Craig Shields Marko Schotanus Tom Hui – SF DBI
Naomi Kelley – City Attorney

 

[spsalso]

Walnuts,

Thank you.


spsalso

 

[epoxybot]

The EDRT Comment Log and all comments there to, no longer matter, since the foundation has changed from 52 Piles to 42 piles. Dr. Pykes first comment seem to increase in validity.

The shenanigans at SFDBI clearly continue. SFDBI pumped out the revised building permits, just before news broke of the tower settling another..., 1 or was it 2 inches. Who knows?

Slate is a new company. They were formed from a few recent graduates, led by Debra Murphy; they all jumped ship from Sage. Sage Engineers was later purchased by Gannett-Fleming. Perhaps the decision makers at Sage decided, once the 2017 Seismic Safety Report. commissioned by the City of SF, was done that the liability of where SG&H were headed; wasn't a selling point. I chuckled when I looked up John Egan's LinkedIn page. He was given senior status as Sage, until they parted ways. Now he is an independent consultant but he lists himself as Senior Principal. I guess his shadow is a Junior Principal. 301 Mission is their meal ticket.

 

[spsalso]

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

So, then, the job was a piece of cake; and if it failed, the designer was a total incompetent and shouldn't be trusted to tie his/her own shoes. Or so it seems implied.




spsalso