SF Tower settlement Part III 18

[dik]

thread815-412357
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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]

Would the plywood cushions be on top of the follower?

No, the plywood cushion was a biscuit in the middle of the ring of reinforcing exiting the top of the pile. Once the follower enters the ground, there is no changing out the cushion.

 

[SwinnyGG]

Do you think any highrise construction project occurs without collusion?

The construction industry is not the high-margin palm-greasing money factory it is in the movies

Isn't that the point of such construction is to secure government grants?

Uh... no.

I've been involved with lots of them... (not really high rise but less than about 30 stories) and no collusion. Maybe the threshold is 31?

"High Rise" is a non-ambiguous term.. it's very clearly defined. 30 stories is way, way beyond the threshold.

 

[3DDave]

The construction industry is not the high-margin palm-greasing money factory it is in the movies

I'm shocked, shocked I tell you.

This seems to be at the opposite end; so desperate for work they chose the most stupid of shortcuts, trying to float a building 5X heavier for the footprint than the neighbors onto a sea of muck because to do it right was far more expensive than what the seller was willing to pay. As usual, physics beats any plan or contract if allowed the chance.

 

[3DDave]

There is news that the raft support is working to remove the lean, but isn't causing the high side to sink. Instead the raft center is sinking at about 1/10th inch per year.

 

[dik]

Sorry swinny... I didn't know there was a height... I've always considered highrises at 50 storeys or something of that ilk... I've never considered 20 or 30 stories as a highrise. I've considered buildings were lateral frames and design become problematic... shorter buildings are just lateral restraints provided by shearwalls, elevators and stairshafts... nothing out of the way.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[epoxybot]

Thursday, February 02, 2017
SF Board of Supervisors - Government Audit and Oversight Committee

160975 Hearing - Building Standards in Seismic Safety Zones

Video:

https://sanfrancisco.granicus.com/player/clip/27042?view_id=10&meta_id=538192&redirect=true

Jack Moehle 44:00 mark

The Mat foundation was designed to sufficiently pick up that force (Outrigger Loading), as well as to have enough strength to develope the moment strength of the core itself. And this is to my recollection the first building that I was a peer reviewer for where I cajoled the structural engineer to put shear reinforcement into the foundation mat.

I'm pretty sure it is in this building. And the way most of these towers had been designed up until that time, is that the foundation mat was made thick enough that shear reinforcing isn't required. But one of the things that we were learning, in research, about that time, was that very thick structural elements, have a unit shear strength that is less than the shear strength of thinner elements.

So if I have a foundation mat that is 1 foot thick, if I make it 10 feet thick, it's not 10 time as strong, maybe.... 2 or 3 times as strong. And by putting shear reinforcement in the mat, it enhances the performance of the system, so that you can get the full strength back out. And I think that shear reinforcement is serving a very good purpose
for us today. And in the future will as well.