SF Tower settlement Part III 18

[dik]

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

-Dik

 

[epoxybot]

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.

 

[dik]

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...

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

-Dik

 

[Keith_1]

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.

 

[dik]

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

 

[epoxybot]

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.

 

[Keith_1]

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.

 

[spsalso]

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

 

[Mark R]

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.

 

[spsalso]

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

 

[Walnuts]

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?

 

[epoxybot]

LB Karp recently updated his Millennium Debacle web page with documents from the previous LERA proposal, along with site photos of the current work.

 

[Walnuts]

I like his title: "Start excavating along Fremont Street to relieve lateral support to base of building to assist inducing catastrophic failure".

 

[dik]

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

 

[Ingenuity]

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.

 

[spsalso]

Yup.

And meanwhile, it's been two weeks since the last posting on the tilt-o-meter.

Sure hope it ain't broke.


spsalso

 

[Walnuts]

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!

 

[spsalso]

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

 

[dik]

...or maybe start a pool for when it 'goes'? I got into trouble on the other site for suggesting a pool for Covid deaths.

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]

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?

 

[Mark R]

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.