Post-tensioned Suspended Ground Floor Slab and Piled Foundation Detail?

[gmannix1000]

Hi All,

Wondering if anyone would have some advice on some PT/foundation detailing.

We have an insitu ground floor slab and the contractor wishes to go PT. The PT specialist is advising that the ground floor slab should be isolated around columns/walls and a slip membrane should be present between the slab soffit and pile caps/groundbeams. Our insitu ground floor slab option was tied to the pile caps and groundbeams to transfer the diaphragm forces into all the piles across the floorplate and not just beneath the cores as piles generally have a low horizontal force capacity.

Has anyone come across this before or know if it is possible to detail the PT slab to the pile caps and groundbeams to get that diaphragm action into all the piles across the floorplate?

Thanks in advance, much appreciated.

 

[hokie66]

I think your PT guy is trying to limit restraint cracking of the slab by as much isolation as possible. If you don't care about cracking, tie it all together.

 

[KootK]

As with slab to wall detailing, I suppose that you could use a slip membrane on your grade beams and pile caps combined with sleeved dowels that get grouted in after the PT shrinkage has substantially taken place. My gut feel is that that this is probably just not a great application for PT.

 

[rapt]

If is is a slab on ground, the only help PT is giving is axial compression. If it is tied into the columns/pile caps, you get little to no axial compression due to restraint. So you have wasted your money on PT that will do nothing and you end up with a very cracked basically unreinforced slab.

 

[HTURKAK]

gmannix1000 : You're not supplying a lot of information here..

Will you provide info regarding ( size , thck of raft , type and dia of piles etc..)?


Can the use of (UNconnected piled raft with cushion) be an option?








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