CHICAGO | St. Regis Chicago (Vista) | 1,191 FT | 101 FLOORS

[KWILLSKYLINE]

Solar, thanks for those pictures. Aparently I was blind or just not paying attention. Can we expect two cranes for One Grant Park as well?

[SolarWind]

January 5, 2017

[KWILLSKYLINE]

God I miss the city. ^^^ keep the pictures posting whenever you have the chance and thanks to all of you toughing out the cold to get these amazing shots.
When I used to work at NBC I would have had a pretty decent view on top of the roof, once it poked up above upper Wacker of course.

[harryc]

resurfacing upper upper Wacker

[KWILLSKYLINE]

^^^^^Whats the third hole for? Third crane possibly?
Or one of the cores?

[BVictor1]

Originally Posted by KWILLSKYLINE

^^^^^Whats the third hole for? Third crane possibly?
Or one of the cores?

Core pit for the main tower. There will be no third tower crane.

01/09/16

[Rocket49]

^^^^
Love your nighttime photo!

Was it taken during the evening, or later in the night?

[BVictor1]

Originally Posted by Rocket49

^^^^
Love your nighttime photo!

Was it taken during the evening, or later in the night?

Between 4:30 and 5pm.

[KWILLSKYLINE]

Night time photos are always Gems. get it. I would love for that project to start up the same time as Vista.

[maru2501]

inclement weather no issue Second crane going up now










west elevator area

[vexxed82]

Originally Posted by maru2501

inclement weather no issue Second crane going up now

Sort of a general construction question: Aside from the physical forces of gravity, and re-bar, is there a chemical reaction that fuses different 'pours' of concrete together?

Specifically in regards to the foundation columns that have been recently dug out. Clearly the caissons are cured (mostly), and although new rebar will be tied to the existing rebar, will there always be a joint, however minuscule, between the top of the old column pour, and bottom of the new column pour?

[Skyguy_7]

^I've always wondered this! Anyone? Bueller?

[City Wide]

Originally Posted by vexxed82

Sort of a general construction question: Aside from the physical forces of gravity, and re-bar, is there a chemical reaction that fuses different 'pours' of concrete together?

Specifically in regards to the foundation columns that have been recently dug out. Clearly, the caissons are cured (mostly), and although new rebar will be tied to the existing rebar, will there always be a joint, however minuscule, between the top of the old column pour, and bottom of the new column pour?

I've got no idea if its used on projects of this scale, but there are bonding agents, a liquid, that claim to be able to join new concrete to old.

[harryc]

Jan 10
from across the river


Jan 14
Second crane going up - note the micro piles being installed - an afterthought ?




Split level foundation pad ?


It appears that the big - coupled - rebar is being used for the horizontal as well as the vertical - note the staggered endings (earthquake code ?).


extending upper upper Wacker



The attention to ascetic detail is impressive, use a crane with rounded weights when the backdrop is a curvy building.

Sort of a general construction question: Aside from the physical forces of gravity, and re-bar, is there a chemical reaction that fuses different 'pours' of concrete together?

Specifically in regards to the foundation columns that have been recently dug out. Clearly the caissons are cured (mostly), and although new rebar will be tied to the existing rebar, will there always be a joint, however minuscule, between the top of the old column pour, and bottom of the new column pour?

An excellent question

[LouisVanDerWright]

I'm not an engineer, but my understanding of that question is as follows:

Yes there is always a permanent "fault line" of sorts where two pours come together, but that the concrete actually does seal together fairly tightly. Remember that concrete is basically just aggregate (i.e. sand and gravel) with portland cement holding it together. So what is the difference between gluing together a bunch of little pieces of rock (i.e. the aggregate) and gluing a bunch of little pieces of rock (i.e. the aggregate in the fresh pour) to one big piece of rock (i.e. the hardened previous pour)? Not much, other than the fact that there is likely to be more air pockets along that line. So of course there is some degree of a fault there permanently, though it is bonded fairly well.

However, none of this matters when you understand how we use concrete. Concrete is all about compression, as was mentioned earlier. This is why they pour all of these floors in one big go. The rebar exists solely to makeup for the shortcoming of concrete which is that it is brittle. Each pour bonds so tightly together that the sheer forces would have to be immense to sever the rebar embedded through the fault between the pours. This wouldn't work so well if you had faults aligned with the pull of gravity (i.e. if you poured half of one floor one day and the other half after the first half dries, the vertical fault would be significantly weaker).

So short summary: concrete actually binds to itself fairly well, but we never use it in situations where how well it binds to itself would be a factor. Rebar is used in concrete to account for the same shortcomings that would make leaving a vertical joint in concrete a problem. You can think of it almost like legos, the block is concrete, the pegs are rebar. If you put compressive forces on a lego wall, it's extremely strong, but if you held the same wall horizontally and applied force, it would quickly crumble. The bricks are bound together quite tightly, but the pegs really carry any sheer force.

[chief56]

Originally Posted by harryc

Jan 10
from across the river


Jan 14
Second crane going up - note the micro piles being installed - an afterthought ?




Split level foundation pad ?


It appears that the big - coupled - rebar is being used for the horizontal as well as the vertical - note the staggered endings (earthquake code ?).


extending upper upper Wacker



The attention to ascetic detail is impressive, use a crane with rounded weights when the backdrop is a curvy building.



An excellent question

Rebar size #14 and #18 have to be coupled. As a rule, its good to stagger laps/couplers so you dont have them all in a row. The bottom mat bars could be staggered due to the size and quantity of bars. You need to have room to manuever the couplers and to tighten them down. I believe this is all #18 bar and the couplers look like position couplers to make securing them easier.

As far as concrete pours, they typically butt up to each other, like LVDW mentioned, the shear loads of floors on columns compress the concrete together, the reinforcing ties everything together thru the joints.

Concrete - better in compression
Rebar - better in tension
The perfect marriage.

[nergie]

I watched and took a short film of the boom being lifted and fitted into place for the East (2nd) tower crane this morning whilst gnoshing on my breakfast. I would love to share the photos and video but having no luck. I can directly look down on the Vista site from my living room, and have compiled an album of photos and videos that I would love to share. Please help, thank you. I had some success with Imgur but then no more luck.

[scalziand]

Well put LVDW. Just making sure that the existing concrete is wet will help the fresh concrete stick to it properly. If it's too dry, the joint won't be wetted properly, and the older concrete can even suck out water from the fresh concrete, preventing the concrete at the joint from curing properly.

[orulz]

Does the street connection from Upper Wacker to Waterside Drive through Vista mean they have forever foreclosed on the idea of extending Upper Wackeru further east?Chandler and Regatta were desgned with their "ground floors" at the level of Upper Wacker, and with an eventual extension of Harbor Drive between them to Wacker in mind. Even if the actual issue of street connectivity is being addressed by Vista, it would still be nice to have an actual street in front of these buildings. (Can't they tell that this lack of completeness offends my OCD?!)

My preference would be for this to be addressed whenever the area east of Chandler is developed.

Alternatively, maybe an Upper Wacker extension could be added whenever Wacker Drive is rebuilt through there. Considering this section of Wacker opened in 1987, and the segment just to the west was opened in 1975, and that the original stretches of Wacker lasted from 1926-2001 (75 years) and 1954-2010 (56 years) we can predict that this stretch of Wacker will need to be rebuilt sometime between 2031 (1975 + 56) and 2062 (1987 + 75).

[Tom In Chicago]

Originally Posted by orulz

Does the street connection from Upper Wacker to Waterside Drive through Vista mean they have forever foreclosed on the idea of extending Upper Wackeru further east?Chandler and Regatta were desgned with their "ground floors" at the level of Upper Wacker, and with an eventual extension of Harbor Drive between them to Wacker in mind.

I wasn't aware that this was ever part of the design plan for either Chandler or Regatta. . . where did you hear this???

. . .