SF Millenium Tower Again

Imagine adding 200 foot pilings under an already built and occupied building. How would they do that? Drill holes and fill with rerod and concrete? Tie it to... something... on the top end?

The thing is so ugly, they should dynamite it and make a park.

I wonder how tall that basement is.

the elevators jam? Looks like the original design group didn't get bogged d own in too much math.

They're drilling from inside the existing cellar. They can bore the pile ho le with an instrumented auger, load it with a steel reinforcing cage and th en fill with concrete slurry. Then all these piles should be evenly distrib uted around the existing concrete frame they have for a foundation.

Drilling 200 foot holes should be fun. That area is mud fill, rotted sailing ship hulls, and earthquake rubble, a stone's throw from the Bay.

We have a series of streets named 1st, Battery, Front, and now Embarcadero, iterations of the filled bay shoreline. Even Bayshore Blvd is a mile from the water.

The building structure is concrete, not steel. It's several times heavier than similar buildings.

And several times uglier.

ch the elevators jam? Looks like the original design group didn't get bogge d down in too much math.

hole with an instrumented auger, load it with a steel reinforcing cage and then fill with concrete slurry. Then all these piles should be evenly dist ributed around the existing concrete frame they have for a foundation.

You may not have to look at it much longer if this pile fix does not work. From what I've seen, 70 meters is at the limits of what the auger technolog y can do. At two inches of new lean development every six months, and this rate of lean is picking up, they don't have much time left. Lean begets mor e lean because the structure naturally bears down on the lean side with mor e weight. Look at the equilibrium of moments at the base, that astronomical mass acting through that astronomical moment arm, the force imbalances are huge. Then the internal forces on fasteners and beams are probably inestim able. Generally rigid structures can only take minuscule deflections before stuff starts to break, and breaking begets more breaking.

Ohh, that is also several times more brittle than a mostly steel structure. Hmmm, not great to have to start jacking it up on one side. The first few new pilings will apply huge forces at one point. And, they can't add 100 new pilings at the same time. Drilling 100 holes at one time would make it topple for sure. Seems like they probably need some kind of adjustable support system, so the force applied to the new pilings can be adjusted as more are completed. (Sounds like some REALLY BIG nuts and bolts!)

I'm assuming this thing is mostly post-stress concrete, then, for at least the horizontal elements?

Jon

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I was wondering if they place the piles to catch the sinking building event ually leveling it, because it's sinking so fast. They need to do a worst ca se estimate of pile installation completion time, and give themselves maybe a 6 month leeway until the building hits the first piles on the lean side, then that limits maximum lean, and they simply wait for the other side to settle on its piles, leveling the whole structure.

Makes me happy to not be a civil engineer.

I've known very few civil engineers. On the other hand some mechanical engineers are remarkably lifelike.

Cheers

Phil Hobbs

And typically can't fix a broken toaster.

much the elevators jam? Looks like the original design group didn't get bo gged down in too much math.

nd

ile hole with an instrumented auger, load it with a steel reinforcing cage and then fill with concrete slurry. Then all these piles should be evenly d istributed around the existing concrete frame they have for a foundation.

k. From what I've seen, 70 meters is at the limits of what the auger techno logy can do. At two inches of new lean development every six months, and th is rate of lean is picking up, they don't have much time left. Lean begets more lean because the structure naturally bears down on the lean side with more weight. Look at the equilibrium of moments at the base, that astronomi cal mass acting through that astronomical moment arm, the force imbalances are huge. Then the internal forces on fasteners and beams are probably ines timable. Generally rigid structures can only take minuscule deflections bef ore stuff starts to break, and breaking begets more breaking.

Reminds me of the tale I heard about Chicago. They raised the whole thing so they could put in a sewer system.

George H.

so much the elevators jam? Looks like the original design group didn't get bogged down in too much math.

ed

and

pile hole with an instrumented auger, load it with a steel reinforcing cag e and then fill with concrete slurry. Then all these piles should be evenly distributed around the existing concrete frame they have for a foundation.

ork. From what I've seen, 70 meters is at the limits of what the auger tech nology can do. At two inches of new lean development every six months, and this rate of lean is picking up, they don't have much time left. Lean beget s more lean because the structure naturally bears down on the lean side wit h more weight. Look at the equilibrium of moments at the base, that astrono mical mass acting through that astronomical moment arm, the force imbalance s are huge. Then the internal forces on fasteners and beams are probably in estimable. Generally rigid structures can only take minuscule deflections b efore stuff starts to break, and breaking begets more breaking.

or

Well, if you gave them the .stp file, it would be different.....

Cheers

Phil Hobbs

MAN, anybody who was engaged in the structural engineering, soil studies, subsurface work, etc. has GOT to be very nervous right now as to whether their insurance is going to cover them. Whew, not a good place to be, this is REAL liability!

Jon

On Monday, July 24, 2017 at 10:09:53 AM UTC-7, Phil Hobbs wrote: ...

"What is the difference between Mechanical Engineers and Civil Engineers?"

Mechanical Engineers build weapons. Civil Engineers build targets.

kevin

If it moves it's mechanical

Of it's powered it's electrical

If it isn't supposed to move it's civil

If it's an assembly line it's industrial.

Some serious fraction of the MT tenants are lawyers. And when they file, they will name everyone involved, down to the coffee cup suppliers.