Formwork for Podium over Existing Deck

[Boiler106]

I need to design a post tensioned 12" podium slab to go as close as possible to the top-most elevated floor/roof of an existing building. This distance can be 6 inches to the underside of the deck or it could be 5 feet; we are trying to minimize it. The concrete column spacing is 32'x32'. There is a concern that conventional formwork would be too difficult to remove.

However, i am limited by two things: the new floor system cannot load the existing floor system, and any requirements for height and removal the shoring system might have.

We have considered foam, but are concerned that our loads will transmit through the surface to the floor below. Although, admittedly, i have not looked at the deformation compatibility b/w the two floor structures.

We have also considered a steel framed floor with metal deck that can be left in place.

Can anyone think of anything else?

 

[dhengr]

Boiler106:
Use two prestressed “L” shaped conc. beams, spanning 32' btwn. two conc. columns, one beam on each column line. Then use precast conc. slabs to span btwn. the two beams. However deep you need to make the slab bearing shelf (the horiz. leg of the “L”) to carry its slab reaction load will determine how close the underside of the slabs can be to the existing roof slab. Cast a 2", or some such, haunch on the bot. of each end of the beams to keep them up off the existing roof slab, and camber the beams to take up part of their deflection.