slab type-P.T or conventional?

[1sa]

Under what circumstances is it appropriate/efficient to use post-tensioning versus conventional reinforced concrete slab? Specifically, I am designing a building with column spacing of either 15'-27'-15' in one direction and 29'-0" spans in the other direction. We can not have beams due headroom clearance issue. Should this be designed as one way? Thanks.

 

[dik]

The spans are good for PT; the shorter exterior spans are a bit of a issue. You should be able to reduce the slab thickness a bit and if multi-storey, it can add up... Matter of checking with local costing... for a conventional slab, you might be looking at an 8" or 9" slab with maybe 9" or 10" drop panels... or something of that ilk...

 

[dcarr82775]

Recently did a few buildings with a similar layout (exterior spans were 19ft). I used PT and it worked just fine. Less drape on teh exterior spans of course, but nothing out of the ordinary

 

[rapt]

1sa,

It is a two slab supported on discrete columns from your description! That makes it two way!

 

[asixth]

Mainly driven by costs. PT will give a thinner slab with less concrete quantites and reo quantities. But it does require and additional trade on the construction site and can slow the floor-to-floor cycle.

It generally goes to the project manager and quantity surveyor to establish the cheaper ($$) floor system.

 

[TomDupuis15]

Post Tension is the only way we can keep a house foundation together in some parts of Snyder. The conventional slabs crack due to the soil being to unstable around here. I have aconvention slab for our new house but we are on a calechie hill (rock). Have that engineering study done, you won't regret it.

decorative concrete kansas city

 

[hokie66]

It is a two way system, especially if the depth is constant. Either PT or conventional can work. PT is probably more economical, but only if PT is routinely used in your area.