elevated concrete slab on piles

[taikos186]

I've got this project to work on and I'm having hard time coming up with concept of presterssed pilings and cast in place concrete floor slab connection.

May be you have came across with something similar. In a beginning I was thinking to do simply like we would do for pile foundation with reinforced concrete slab, with pile caps and edge beams. Only the difference is that reinforced slab is elevated 8 feet above ground. Would you do 30" sqr. pile caps and edge beams for this type of elevated foundation/floor? The problem is that I have not seen it before, may be it should be done in a different way?

I would greatly appreciate your opinion

 

[JAE]

I would install the piling up to the ground level. Then use a series of cast-in-place concrete grade beams to tie them together just at or below ground. Then extent reinforced concrete columns up from each pile/pier to support the elevated concrete floor.

If necessary, use shear walls for lateral forces - or design the grade-beam / column / floor structure as a moment frame.

 

[hokie66]

JAE's way is one way, but it is feasible to extend the piles above grade as columns, in which case there would be no pile caps. Using them in this way may require larger piles. This is done frequently in bridge construction, but not so often in buildings.

 

[JAE]

I guess I was thinking of prestressed piling installed with 8 feet sticking out of the ground - just didn't sound right to me. There would just be too much variability in the position of driven piling like that.

I'd feel better about a grid of grade beams at the base as they would cover over any variation in position and plumbness.

 

[Zambo]

I think JAE's recommendation is the way to go for the structure proposed by the threadstarter. But it is not unusual to have a structure where the same members are piles below ground and designed as columns above ground (for example a jetty structure) As hokie66 states it is likely that the piles would have to be larger to satify the design as columns above ground.