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  #1921  
Old Posted Jan 15, 2017, 9:46 PM
Skyguy_7 Skyguy_7 is offline
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^I've always wondered this! Anyone? Bueller?
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  #1922  
Old Posted Jan 16, 2017, 12:22 AM
City Wide City Wide is offline
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Quote:
Originally Posted by vexxed82 View Post
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.
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  #1923  
Old Posted Jan 16, 2017, 1:55 PM
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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.


Quote:
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
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  #1924  
Old Posted Jan 16, 2017, 4:19 PM
LouisVanDerWright LouisVanDerWright is offline
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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.

Last edited by LouisVanDerWright; Jan 17, 2017 at 5:07 AM.
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  #1925  
Old Posted Jan 17, 2017, 4:52 AM
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scalziand scalziand is offline
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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.
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  #1926  
Old Posted Jan 17, 2017, 3:40 PM
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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).
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  #1927  
Old Posted Jan 17, 2017, 8:22 PM
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Tom In Chicago Tom In Chicago is offline
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Quote:
Originally Posted by orulz View Post
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???

. . .
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  #1928  
Old Posted Jan 18, 2017, 7:32 PM
chief56 chief56 is offline
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Quote:
Originally Posted by harryc View Post
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.
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  #1929  
Old Posted Jan 19, 2017, 3:39 PM
nergie nergie is offline
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Boom for second crane installed this morning

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.
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  #1930  
Old Posted Jan 19, 2017, 3:50 PM
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Quote:
Originally Posted by nergie View Post
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.
this has been working well:

https://postimage.io/
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  #1931  
Old Posted Jan 19, 2017, 5:54 PM
orulz orulz is offline
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Quote:
Originally Posted by Tom In Chicago View Post
I wasn't aware that this was ever part of the design plan for either Chandler or Regatta. . . where did you hear this???

. . .
The developer didn't want to do it. However, the Planning Commission evidently made them reserve a 66 foot right-of-way between these buildings for this possible future connection. Reference here.
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  #1932  
Old Posted Jan 19, 2017, 8:23 PM
nergie nergie is offline
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Quote:
Originally Posted by maru2501 View Post
this has been working well:

https://postimage.io/
Thanks I'll try to setup an account at this site.
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  #1933  
Old Posted Jan 19, 2017, 8:31 PM
nergie nergie is offline
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Vista Images-

http://imgur.com/lqvdvUU
http://imgur.com/lQsc1z3
http://imgur.com/sQmVRu6
http://imgur.com/RQKhHXY
http://imgur.com/zNIf13Y
http://imgur.com/ZgSMpyc
http://imgur.com/zQIkSDq
http://imgur.com/2SILTj4



All images taken by me on my iPhone and iPad. My apologies for the quality. How do I get the pictures not just the links to show up in my post?

Last edited by nergie; Jan 19, 2017 at 8:51 PM.
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  #1934  
Old Posted Jan 19, 2017, 8:46 PM
nergie nergie is offline
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Pls Delete -duplicate post
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  #1935  
Old Posted Jan 19, 2017, 8:52 PM
rlw777 rlw777 is offline
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This should work

If you can't find the place to copy the direct link you can just add "i." to the beginning of the url and "h.jpg" to the end
so "http://imgur.com/2SILTj4" becomes "http://i.imgur.com/2SILTj4h.jpg"

Quote:
Originally Posted by nergie View Post











All images taken by me on my iPhone and iPad. My apologies for the quality.

Last edited by rlw777; Jan 19, 2017 at 9:03 PM.
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  #1936  
Old Posted Jan 19, 2017, 9:21 PM
Notyrview Notyrview is offline
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  #1937  
Old Posted Jan 19, 2017, 10:13 PM
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Quote:
Originally Posted by orulz View Post
The developer didn't want to do it. However, the Planning Commission evidently made them reserve a 66 foot right-of-way between these buildings for this possible future connection. Reference here.
Design wise it's straightforward, but I don't think the city would ever foot the bill to get it done, it would really only be for the added benefit of a few highrises.

Not saying I don't want it done, but I think it would come off too unnecessary to actually complete.
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  #1938  
Old Posted Jan 20, 2017, 4:13 PM
nergie nergie is offline
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Thank you, for all the help
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  #1939  
Old Posted Jan 20, 2017, 4:20 PM
orulz orulz is offline
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Quote:
Originally Posted by MayorOfChicago View Post
Design wise it's straightforward, but I don't think the city would ever foot the bill to get it done, it would really only be for the added benefit of a few highrises.

Not saying I don't want it done, but I think it would come off too unnecessary to actually complete.
I agree the city isn't going to just decide to shell out money to make these high rises more desirable. The only possibilities I see for building it are (1) when the rest of LSE Block C is built out, and (2) whenever Wacker is rebuilt.
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  #1940  
Old Posted Jan 20, 2017, 4:33 PM
LouisVanDerWright LouisVanDerWright is offline
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Tired ono shots of this core from the ground:



[IMG]www.imgur.com/NWBilc0[/IMG]

[IMG]www.imgur.com/QYvBdWz[/IMG]

Measuring from his little perch:

[IMG]www.imgur.com/mdpmzgM[/IMG]

[IMG]www.imgur.com/bbAVv4Q[/IMG]

Another building born too late to know the Cubs as the lovable losers, still flying the "W":

[IMG]www.imgur.com/1oWrU1s[/IMG]

No idea why these aren't working right now...

Last edited by LouisVanDerWright; Jan 20, 2017 at 4:58 PM.
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