Holy crap. Look at the rebar in that beam in the northeast corner!

Is anyone here a structural engineer? What on Earth would be the advantage to forming a reinforced concrete beam like that instead of just running a deep-web beam from the exterior column to the interior column? Or using post-tensioned concrete? That thing looks like it's like 75% steel in there!
 
Maybe it's a design revision to add structural strength? The revision having been done after the manufacture of the super columns, required a bit of creative thinking?
 
whatever said:
Holy crap. Look at the rebar in that beam in the northeast corner!

Is anyone here a structural engineer? What on Earth would be the advantage to forming a reinforced concrete beam like that instead of just running a deep-web beam from the exterior column to the interior column? Or using post-tensioned concrete? That thing looks like it's like 75% steel in there!
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I believe this floor, like the floor below, vertical members are acting as a transfer slab for the elevator core. If you have the space thick concrete with lots of rebar works very well for lateral shear force transfer and although labour intensive material wise is economic. Also attaching pre fab steel or steel cable tensioned concrete beams to concrete columns works well for bridges but not so straight forward mid point for vertical concrete columns, thinking localized loading on column concrete. Not sure why they didn't go with just one thick transfer slab. - my two cents.
 
The Preservationist said:
I believe this floor, like the floor below, vertical members are acting as a transfer slab for the elevator core. If you have the space thick concrete with lots of rebar works very well for lateral shear force transfer and although labour intensive material wise is economic. Also attaching pre fab steel or steel cable tensioned concrete beams to concrete columns works well for bridges but not so straight forward mid point for vertical concrete columns, thinking localized loading on column concrete. Not sure why they didn't go with just one thick transfer slab. - my two cents.
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Because they need a doorway.

It is not for the elevator core, it is to be able to pour regular repeating typical walls above.
 
Based on my projections, I think they should be at the 23rd floor by this time next year.

Here is my projection:
7th level pour will happen sometime in early January (First Repeating Floor)
8th level pour will be 3rd week of Jan
9th level pour will be 2nd week of Feb
10th level pour will be 1st week of March
11th pour will be end of March
12th pour will be mid-April
13th pour will be first week of May
14th pour will be end of May
15th pour will be mid-Jun
16th pour will be end of June
17th pour will be end of July (Mechanical Floor)
18th pour will be 3rd week of August (Mechanical Floor)
19th pour will be mid-Sept
20th pour will be first week of Oct
21st pour will be end of Oct
22nd pour will be mid-Nov
23rd pour will be first week of Dec
 
jibsta said:
Because they need a doorway.

It is not for the elevator core, it is to be able to pour regular repeating typical walls above.
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Ok, that makes sense for why there's a bonkers beam spanning the columns, if it's carrying like 80 storeys of repeating walls above it. I'm just surprised that the answer is a buttload of heavy rebar versus like, a box girder.

Or why not throw a light beam from the outer columns to the inner columns on every floor, to support those repeating walls? Cheaper to do the one heavy beam here than many lighter beams the whole way up?

I don't doubt the civil engineer that came up with that knows way more than I do, I'm just intrigued by the design choice and am curious to understand it
 
The Preservationist said:
I believe this floor, like the floor below, vertical members are acting as a transfer slab for the elevator core. If you have the space thick concrete with lots of rebar works very well for lateral shear force transfer and although labour intensive material wise is economic. Also attaching pre fab steel or steel cable tensioned concrete beams to concrete columns works well for bridges but not so straight forward mid point for vertical concrete columns, thinking localized loading on column concrete. Not sure why they didn't go with just one thick transfer slab. - my two cents.
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Likely because the floor base has no central columns? Thus all the weight above ground goes to the 8 super columns around the perimeter of the tower...or least how I understand that. As there is also a thick transfer slab to said understanding as well.
 
I thought someone said the above tower portion would not have structurally supporting interior walls, only an elevator shaft? Have I got this wrong? thanks
 
The Preservationist said:
I thought someone said the above tower portion would not have structurally supporting interior walls, only an elevator shaft? Have I got this wrong? thanks
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As I said, to my understanding of it. In that I could be all wrong too. >.<
 
There's definitely interior structural shear walls all the way up - this is L56 for example.
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ChesterCopperpot said:
There's definitely interior structural shear walls all the way up - this is L56 for example.
View attachment 366737
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That's a lot of structure and weight if solid walls and true proportions. Thanks Chester for digging up the engineering drawings, it provides some explanation of the massive reinforcement we're seeing in the podium.

Edit: I'm interested to see if they pour all the vertical elements at once as per the last floor. That might suggest other things at play such and structural rigidity and lateral load transfer. Never seen anything go up like this.
 
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