How are tower cranes attached to buildings?

KevinFromTexas · #1 Posted **Oct 10, 2007, 4:54 AM**

This was a question posed by another forumer, and I've sort of wondered myself. How are tower cranes attached to buildings? They appear to have some kind of bracket that reaches out from the shaft of the tower crane and latches onto the skeleton of the building. Anyone know exactly how they are attached and where exactly? Floorplates or columns.

Austin55 · #2 Posted **Oct 11, 2007, 2:50 AM**

Quote:

Originally Posted by KevinFromTexas

This was a question posed by another forumer, and I've sort of wondered myself. How are tower cranes attached to buildings? They appear to have some kind of bracket that reaches out from the shaft of the tower crane and latches onto the skeleton of the building. Anyone know exactly how they are attached and where exactly? Floorplates or columns.

Arent they attached to the floorplates And the columns? but how does that move up?

KevinFromTexas · #3 Posted **Oct 11, 2007, 3:58 AM**

The tower crane's shaft doesn't move up. Only the top of the crane moves up when it's time to raise the crane. A jack raises the top of the crane and a new piece of tower shaft is slid in and bolted into place. The jack raises up another level (up to the new piece of shaft) and the process continues until the desired height is achieved. But I'm wondering how exactly they attach to the concrete without damaging it. That was the original question posed by another forumer, how are the brackets attached without chewing up the concrete.

dallasbrink · #4 Posted **Oct 11, 2007, 5:22 AM**

how do they move up the cranes on the super talls that rise with the building inside the building and how do they remove the cranes from the top of them?

The Jabroni · #5 Posted **Oct 11, 2007, 4:12 PM**

This has been a question that's been boggling my mind for a long time. I also want to know that once they're done construction, how do they take down the crane, especially at very tall heights?

cbotnyse · #6 Posted **Oct 11, 2007, 6:14 PM**

Quote:

Originally Posted by The Jabroni

This has been a question that's been boggling my mind for a long time. I also want to know that once they're done construction, how do they take down the crane, especially at very tall heights?

This is what I am wondering. In Chicago, I've seen other cranes come in to take down cranes, but that was on a mid-rise. How do you get down the Trump crain once its topped off? or the Spire crane????

MayDay · #7 Posted **Oct 11, 2007, 6:50 PM**

From wikipedia:

A tower crane is usually assembled by a telescopic crane of smaller lifting capacity but greater height and in the case of tower cranes that have risen while constructing very tall skyscrapers, a smaller crane (or derrick) will sometimes be lifted to the roof of the completed tower to dismantle the tower crane afterwards.

From what I understand, some cranes (likely the smaller/derrick) can be dismantled into pieces/parts that are small enough to fit in a freight elevator. That's likely what they used to remove the crane seen here (Key Tower under construction):

theWatusi · #8 Posted **Oct 11, 2007, 11:22 PM**

Quote:

Originally Posted by dallasbrink

how do they move up the cranes on the super talls that rise with the building inside the building and how do they remove the cranes from the top of them?

Only the top of the crane moves in this case also. The shaft of the crane is inside of the core (the base is at the bottom) See pictures of the FT to illustrate this

KevinFromTexas · #9 Posted **Oct 13, 2007, 2:10 AM**

I posted a very comprehensive thread in the Texas section with photos and video of how they raise and lower tower cranes. Amanita, our resident forum crane goddess, also helped out with the info. See the link below.
http://forum.skyscraperpage.com/showthread.php?t=135432

harryc · #10 Posted **Oct 13, 2007, 2:14 AM**

KevinFromTexas · #11 Posted **Oct 13, 2007, 2:17 AM**

Ha, well, here's a little photo info about how tower cranes are attached.
I took this picture back in July of the construction of San Antonio's Grand Hyatt hotel.
I took this picture from the Tower of the Americas of the hotel's top during construction.
If you pan over to the right you can see the braces I'm talking about which anchor the crane to the building's skeleton.
I'm still wondering how these are attached though without damaging the concrete.

harryc · #12 Posted **Oct 13, 2007, 2:18 AM**

Quote:

Originally Posted by KevinFromTexas

I posted a very comprehensive thread in the Texas section with photos and video of how they raise and lower tower cranes. Amanita, our resident forum crane goddess, also helped out with the info. See the link below.
http://forum.skyscraperpage.com/showthread.php?t=135432

Impressive.

harryc · #13 Posted **Oct 13, 2007, 2:24 AM**

Pieces on the ground.

Installed.

This allows the crane to put in - or take out - sections of tower, raising or lowering itself.

harryc · #14 Posted **Oct 13, 2007, 2:25 AM**

KevinFromTexas · #15 Posted **Oct 13, 2007, 3:12 AM**

Cool, thanks for the pictures. I'm guessing they're just bolted into the concrete?

Kelvin · #16 Posted **Oct 13, 2007, 4:37 PM**

Generally speaking a crane derives it's lateral support by, as noted previously, by use of horizontal ties to the building frame. The engineer who designs the building does not account or provide these measures -- rather that task is given to the general contractor or crane designer.

They in turn offer a means of support, including drawings and calculations, to the engineer who reviews it for compliance with their design.

All this is done before the crane goes up and so when formwork is put together, the contractor will then place special embedments behind the forms that get cast into the concrete (one could also detail special attachments in a steel frame too) and then are available to the crane when it gets to that point.

The point of attachment is usually at the slab (rather than the column) for a couple of reasons - 1. the column face is often further back than the edge of the slab making it the easiest place to connect to, and 2. placing lateral load (from the crane tower) is generally not well received by the engineer (it could make his column push out and deform, crack, or buckle - esp. with "green" concrete). Slabs on the other hand are especially well suited to picking up and distributing lateral loads from external elements.

When the crane is disassembled and the ties removed, the anchors can be grouted over.

harryc · #17 Posted **Oct 13, 2007, 5:13 PM**

Quote:

Originally Posted by Kelvin

Generally speaking ........ the anchors can be grouted over.

Thank your Kelvin !

Anchor on concrete ( 300 N LaSalle - Chicago )

dallasbrink · #18 Posted **Oct 15, 2007, 6:05 PM**

ok, on these super tall building where the crane climbs with the floors and is attached to the floors i guess, how do they get those cranes down. Like on the Trump Tower in Chicago, how will they get those down?

MayDay · #19 Posted **Oct 15, 2007, 6:32 PM**

Slow down, switch to de-caf, and re-read:

A tower crane is usually assembled by a telescopic crane of smaller lifting capacity but greater height and in the case of tower cranes that have risen while constructing very tall skyscrapers, a smaller crane (or derrick) will sometimes be lifted to the roof of the completed tower to dismantle the tower crane afterwards.
...........

From what I understand, some cranes (likely the smaller/derrick cranes) can be dismantled into pieces/parts that are small enough to fit in a freight elevator. That's likely what they used to remove the crane seen here (Key Tower under construction):

..........

MayDay · #20 Posted **Oct 15, 2007, 6:40 PM**

This is a pretty good "Cranes 101" from ALL - a company based in Cleveland:

http://allcraneloadcharts.com/pdfs/A...quip_Guide.pdf