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Old Posted Oct 22, 2010, 6:41 AM
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Preecha Preecha is offline
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Lift slab construction

Hello, everybody

i am searching for information regarding 'lift slab' construction in low- and medium-rise buildings, does anyone know where to find such information? i would appreciate for the help.

thank you very much in advance

Preecha
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  #2  
Old Posted Oct 24, 2010, 2:50 AM
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scalziand scalziand is offline
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After the collapse of L'Ambiance Plaza during construction, Lift slab construction kind of fell out of favor, at least in Connecticut.

When the floors were being jacked up, the temporary wedges holding them in place against the columns slipped, causing the floors to pancake together.

Possibly useful link: http://www.jackingsystems.com/climbfloor/builders.php

Also, try looking up 'jack slab' construction, as it is sometime called that too.
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Old Posted Oct 24, 2010, 6:58 PM
Rizzo Rizzo is offline
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Quote:
Originally Posted by scalziand View Post
After the collapse of L'Ambiance Plaza during construction, Lift slab construction kind of fell out of favor, at least in Connecticut.

When the floors were being jacked up, the temporary wedges holding them in place against the columns slipped, causing the floors to pancake together.

Possibly useful link: http://www.jackingsystems.com/climbfloor/builders.php

Also, try looking up 'jack slab' construction, as it is sometime called that too.
That project is generally agreed to be the end of this construction technique almost everywhere.


Huron Towers in Ann Arbor was built using lift-slab.

http://en.wikipedia.org/wiki/Huron_Towers
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  #4  
Old Posted Oct 24, 2010, 7:29 PM
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My condo (one of 4 towers) was built using this method. I believe it was the only time this construction technique was used in Canada, and it was built in the mid 1950s so I don't know where there would be any info available.
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Old Posted Oct 26, 2010, 3:33 AM
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This type of construction appears to have only existed for economic reasons. Constructing reinforced concrete slabs is expensive and labor intensive if you build it from scratch on-site (that is, directly at the height you want to build the floor at). The labor involves tying the reinforcement, inspecting that the reinforcement spacing and ties are correct, placing the forms securely, and then pouring the concrete (which also requires inspection and curing afterwards). All this is difficult, not to mention potentially dangerous, to do above ground. Simply moving this whole operation onto ground level gets rid of a lot of the expense and potential dangers.

As others have implied, the task of actually raising the finished slab into place also has its own dangers, so much so that this technique is hardly used nowadays (if even used at all).

In fact, true properly-engineered reinforced concrete floor slabs (with rebar placed in the correct locations to resist moment and shear forces) are rarely built at all nowadays because of the expense and intensive labor (that is, for floor slabs above ground). Concrete floors built nowadays are mostly of the form-deck variety. This simply involves pouring the desired thickness of concrete onto corrugated sheet steel with concrete forms around it. This method is far less labor and cost-intensive than any of the above methods. Although the steel sheet deck doesn't quite provide the 'properly engineered' resistances against moment and shear, it still provides enough resistance against the various forces at above the minimum factors of safety to be considered adequate.
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  #6  
Old Posted Oct 26, 2010, 6:19 AM
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thank you very much, all. i apprecciate your replies.
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  #7  
Old Posted Apr 23, 2015, 2:01 AM
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The evening news just had a reminder tonight that tomorrow is the 28th anniversary of the L'Ambiance Plaza collapse.

Edit:
And in the paper today:

L'Ambiance still echoes
Published 7:53 pm, Wednesday, April 22, 2015

As they have every year since the day it happened, April 23, 1987, organized labor in Connecticut has kept alive not only the memory of the L'Ambiance Plaza construction disaster and the 28 men who died there, but also the importance of the ongoing fight for safety in the workplace.

On that day, a twin-towered apartment building going up at the corner of Washington Avenue and Coleman Street in Bridgeport collapsed, the floors that had been erected in a now abandoned practice called lift-slab, pancaking down on the tradesmen working below.

Death, it was determined later, came with merciful swiftness.

Lift-slab is a method of construction in which concrete floors are poured at ground level and jacked upward into position.

http://www.ctpost.com/opinion/articl...es-6217736.php

Last edited by scalziand; Apr 23, 2015 at 5:24 PM.
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  #8  
Old Posted Apr 24, 2015, 10:16 PM
Jasonhouse Jasonhouse is offline
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Most everyone looking to build quickly and/or save on labor in a high cost area uses some form of precast or tilt-up (or mix) these days instead.
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