PHILADELPHIA | FMC Tower @ Cira Centre South | 736 FT | 49 FLOORS - Page 75

Flyers2001 · #**1481** Posted **Jul 21, 2014, 7:51 PM**

Quote:

Originally Posted by ichigo

I'm not that knowledgeable when it comes to actual construction, so can someone explain to me how this is going to work? Is caisson going to get filled in with concrete and act as a foundation? Or are they still going to dig the crater for the foundation and if so, why not do that first and then do the caisson?

From what I was reading caisson is usually used when there is water involved, for construction of bridges for example. I was under impression that for a building this size you would dig a giant crater, put support for the walls and fill it in with concrete for the foundation.

Thanks in advance for the explanation

I don't believe they are digging any deeper. The Caisson installation would indicate under/construction on this forum.

summersm343 · #**1482** Posted **Jul 21, 2014, 7:54 PM**

Quote:

Originally Posted by simms3_redux

^^^See 181 Fremont thread in UC forum for explanations, history, etc. caissons are to reach bedrock. Not familiar with Philly bedrock, but a similar sized building UC in SF has bedrock 260 ft below where the foundation will be poured. They drilled the caissons first and are now commencing excavation, an explanation for this order of events is also provided, though my understanding of FMC is that heavy excavation is not necessary as parking is in an existing above-ground structure.

Will be interesting watching this one rise! It will probably take 3-6 months to drill the caissons and fill them with concrete. It took about 6-8 months for both 181 Fremont and Salesforce Tower caissons in SF, but there are other complications here (super space constraints at 181, depth of shafts at both sites, seismic considerations, size of Salesforce Tower, etc).

I was told bedrock on this site was only 58 feet down. I do not know how accurate that is.

summersm343 · #**1483** Posted **Jul 21, 2014, 10:11 PM**

Decided to take a detour on my after-work-run and visit the site again.

Caught them lowering a rebar cage into the drilled hole! There is also a cement truck on site now

Another picture of the first drilled hole with rebar already in. Cement is probably being poured in now:

Philly Fan · #**1484** Posted **Jul 21, 2014, 11:15 PM**

Quote:

Originally Posted by summersm343

Decided to take a detour on my after-work-run and visit the site again.

Caught them lowering a rebar cage into the drilled hole! There is also a cement truck on site now

Hmmmm . . . . . somebody predicted that earlier today:

Quote:

Originally Posted by Philly Fan

Can concrete trucks be far behind?

Incidentally, just to get technical for a moment: those trucks actually contain concrete, which is a mixture of cement, water, and aggregate. If they used just cement in construction, these buildings wouldn't be standing for very long.

apetrella802 · #**1485** Posted **Jul 21, 2014, 11:30 PM**

Quote:

Originally Posted by summersm343

I was told bedrock on this site was only 58 feet down. I do not know how accurate that is.

I know that bedrock for the first Comcast tower was said to be 60' below grade so the 58' is probable correct since there are just one block apart.

summersm343 · #**1486** Posted **Jul 21, 2014, 11:39 PM**

Quote:

Originally Posted by Philly Fan

Incidentally, just to get technical for a moment: those trucks actually contain concrete, which is a mixture of cement, water, and aggregate. If they used just cement in construction, these buildings wouldn't be standing for very long.

Thanks for the correction!

And yes you did predict it hahaha.

summersm343 · #**1487** Posted **Jul 21, 2014, 11:41 PM**

Quote:

Originally Posted by apetrella802

I know that bedrock for the first Comcast tower was said to be 60' below grade so the 58' is probable correct since there are just one block apart.

FMC is actually about 18 blocks away from CITC

JustSomeGuyWho · #**1488** Posted **Jul 22, 2014, 5:40 AM**

Quote:

Originally Posted by apetrella802

I know that bedrock for the first Comcast tower was said to be 60' below grade so the 58' is probable correct since there are just one block apart.

R U mistakenly talking about the new Comcast building and not FMC?

ichigo · #**1489** Posted **Jul 22, 2014, 2:27 PM**

Quote:

Originally Posted by summersm343

I work on more of the business side of real estate so I'm not completely versed in highrise construction, but I think I know enough to explain. Anyone feel free to correct me where I am wrong.

Holes for caissons are dug down to the bedrock. The caisson is lowered in the hole and attached to the bedrock and then filled with concrete. Not all highrises require a hole to be dug. This really only occurs if there are subterranean levels or underground parking. However, even highrises that dig a hole for foundations will install caissons. It's basically what holds the building sturdy to the earth since the dirt directly under the building is less secure.

For FMC, there will not be any digging foundations like for CITC which will have subterranean levels and some underground parking. The base of FMC will already be lower than Walnut street level so caissons will be installed directly into the ground without any prior excavation.

Thanks, that makes much more sense now

Plokoon11 · #**1490** Posted **Jul 22, 2014, 11:35 PM**

Any daily sightings today?

ichigo · #**1491** Posted **Jul 24, 2014, 4:14 PM**

Went by the FMC site yesterday at 6:30 pm and they were still working. Normally when I go by, they are already done for the day. Seems like the activity is starting to pick up.

It's great to see the "dead zone" of 30th street to become so alive. As more and more people start working and living here, hopefully lot's of restaurants and businesses will come into the area.

wondertwinalpha · #**1492** Posted **Jul 24, 2014, 5:10 PM**

Busy busy busy!

summersm343 · #**1493** Posted **Jul 24, 2014, 5:15 PM**

That is one massive rebar cage!!! Look at that baby. BTW 5 holes are now drilled and three of them have caissons in them. Looks like one of the bigger holes is about to get a caisson too.

Plokoon11 · #**1494** Posted **Jul 24, 2014, 5:17 PM**

If I were 8 I would play in that thing. How many cassions do they need to install? Just curious. Looks like there working hard! Thanks for the update!

Philly Fan · #**1495** Posted **Jul 24, 2014, 5:57 PM**

Quote:

Originally Posted by summersm343

That is one massive rebar cage!!! Look at that baby.

Especially when you compare it to the two men in the photo for perspective. If that baby is going to be completely submerged in a caisson, it'll definitely be sitting on bedrock. And with the amount of steel in that thing, I'd say that pier should hold up pretty well.

nateberry1 · #**1496** Posted **Jul 25, 2014, 12:13 AM**

Some photos from this evening. 7/24/14

hammersklavier · #**1497** Posted **Jul 25, 2014, 5:03 AM**

Quote:

Originally Posted by summersm343

I was told bedrock on this site was only 58 feet down. I do not know how accurate that is.

Didn't know that. I'd assumed that since the site lies in the floodplain it was ~100-150 ft down min.

nateberry1 · #**1498** Posted **Jul 25, 2014, 11:33 PM**

A couple from today, not a lot of change. 7/25/14

[IMG]http://i357.photobucket.com/albums/oo14/nberry5862/FMC%20Tower/20140725_174145.jpg[/IMG

Philly-Drew · #**1499** Posted **Jul 25, 2014, 11:38 PM**

Quote:

Originally Posted by summersm343

Current 10 Tallest

1. Comcast Center- 58 floors- 975 feet
2. One Liberty Place- 61 floors- 945 feet
3. Two Liberty Place- 58 floors- 848 feet
4. BNY Mellon Center- 54 floors- 792 feet
5. Three Logan Square- 55 floors- 739 feet
6. Independence Blue Cross Tower- 45 floors- 625 feet
7. One Commerce Square- 41 floors- 565 feet
8. Two Commerce Square- 41 floors- 565 feet
9. Philadelphia City Hall- 9 floors- 548 feet
10. The Residences at the Ritz-Carlton- 48 floors- 518 feet

So, at some point, it is very likely that FMC will become the 6th highest building in the city.
How long do you think it states that way?

When would you wager that it becomes the 7th?

summersm343 · #**1500** Posted **Jul 26, 2014, 2:07 PM**

Quote:

Originally Posted by Philly-Drew

So, at some point, it is very likely that FMC will become the 6th highest building in the city.
How long do you think it states that way?

When would you wager that it becomes the 7th?

It will probably only be the 6th for a few months until CITC is topped out which will bump it down to 7th.