SF tower settlement 25

[IRstuff]

Those cracks probably were hairline cracks when the strain gages were installed, based on the dates written on them.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[MotorCity]

So if this issue was settled out of court, would it be a settlement on the settlement?

 

[MacGyverS2000]

This discussion is unsettling, MC, but I've occasionally cracked up while reading it...


Dan - Owner

http://www.Hi-TecDesigns.com

 

[JAE]

I'm starting to catch the general drift of this thread.

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[IRstuff]

Seems to me the discussion has suddenly gotten a bit skewed off foundation.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[dik]

I was thinking, micropiles to rock and secured in the slab foundation. Would the poor soil offer enough restraint to preclude buckling. Lets try to think of some remediation.

Dik

 

[MacGyverS2000]

IR, perhaps we should come at this from a different angle rather than straight on? I'm leaning towards a simple solution.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[JAE]

I sure dig your slant on this.

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[darthsoilsguy2]

curious. has anyone heard who the geotech firm was on this? i know DeSimone was structural but haven't seen any reference to the geotech. FYI... they have a new geotech in now who was not related with the original construction.

 

[Sparweb]

That settles it.
I will only read this thread for shear amusement from now on.

STF

 

[Ingenuity]

curious. has anyone heard who the geotech firm was on this?

Treadwell & Rollo, now part of Langan Engineering. ENR link re aquisition and Langan Engineering website.

i know DeSimone was structural...

Sadly, Vincent DeSimone (founder of DeSimone Consulting Engineers) passed away in November, 2016. Memoriam

 

[JedClampett]

This one only settled 14 inches before it was "dealt with."

 

[JedClampett]

A structural engineer did a review of the building design, but only the building, not the foundation.
I kind of sympathize with the guy, no one welcomes you reviewing scope beyond your contract.

 

[JAE]

Just curious here - it says that the tower has sunk 16" - that is "significant".
But the lean is 2".

For a 645 ft. (196.6m) tall building the ACI 117 tolerances (for construction) would be on the order of 3" to 6" depending on the direction of the measurement.

So a 2" "lean" here doesn't sound too bad.

For typical wind load deflections, a tall building like this might lean L/500 = 15 inches.

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[Ingenuity]

A structural engineer did a review of the building design, but only the building, not the foundation.
I kind of sympathize with the guy, no one welcomes you reviewing scope beyond your contract.

And non-other than Prof Jack Moehle of UC Berkeley:

“The interest was to do an internal review to ensure that the structural system selected was suitable,” Moehle told city lawmakers at Thursday’s hearing. “[So] that if there was a formal peer review for the city later that most questions would be dealt with already.”

 

[Ingenuity]

And this from 2004 about 80 Natoma SF proposed 50-story tower that was NOT constructed Link:

A 50-story building is heavy. If constructed, the 80 Natoma Building would impose 13,000 pounds per square foot on the soil below it. Moreover, if the developer went ahead with his plan to use short (70-foot) piles to support the building, the bottom of his piles would lie just above a 90-foot layer of compressible clay. Geotechnical experts concluded that imposing such loads through the piles to the clay would cause the clay to deform and the building to settle several inches. Unless the developer were to extend his piles another 100 feet or so to bedrock, there is no getting around this.

 

[Ingenuity]

Link to C & C of SF video testimony of Prof Jack Moehle dated 2/2/17 - all 2.5 hours! Link

 

[itsmoked]

I'm betting we see this in the future with that building.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[hokie66]

I had the same thought, Keith. But I'm not betting.

 

[dik]

From Curbed, "Moehle says he inspected the high-rise’s design from top to bottom—but no lower than the bottom. A geotechnical review—i.e., an assessment of the condition of the soil under the building site—wasn’t part of the process, because no one ever hired a geotechnical engineer."

Even as a rookie, if I had been asked to provide an engineering report for a building with substantial subsidence, I would have raised a bit of a flag about having a geotechnical report included with the overall report (and that is not hindsight being 20/20). Because subsidence was a key issue, this would be a significant part of the engineering report.

Dik