Has anyone post tensioned Lite-Deck or other IFF? Or opinions on how it would work?

Have not post-tensioned myself, but the IFF lends itself nicely to it. The strands need to be in the beam pockets. I am sure you already know this institute but here it is for everybody else: http://www.post-tensioning.org/

I did not find anything at PTI. Because any Lite-Deck I do is combined with ICFs, and poured with at least part of the wall, we would have to tension on the outside of the wall.

Do concrete subs do the actual tensioning or is it usually iron-workers?

Guys,

Please educate on the need to post tension a slab. I understand the principle of using hydraulic/pneumatic jacks to pull the rebar and this would compress the slab once the jacks are released. Does this allow increased flexural strength to the slab? To allow a clear span for an overhead deck?

Thanks,

Leonard

What got me thinking was a great article in the latest Concrete Construction magazine, Post-Tensioned SLABS.

Tension is applied to cable, 4 times the strength of rebar, compressing the concrete. The cables run through sleeves that are nearer the tension surface of the concrete. The tension side is opposite the load (compression) side.

I hope I explained it well.

I inquired with one of the engineers I use a few years ago. His claim it was not possible to PT a Insuldeck/Lite Deck because of the lack of concrete substance.

You can get proper clearance in the 'flutes' top to bottom, but not on the side to side area.

Tensioning I have used is 33,000 lbs. That's a lot of pressure. And I have seen cables snap...and fly out the opposite end of the slab.

I personally don't due the tensioning, I sub it to a company who comes in and is witnessed and verified by an independant special inspector/engineer.

Chris, What do you post-tension? I have heard of 3" slabs being PT. I would think a 6" wide beam pocket would be enough.

I sent an email to Ulteig Engineering, as they do a lot of the ICF and Lite-Deck around here.

I do SOG, 12" thick, remember I'm in CA, earthquake country, we have quirky codes out here that don't necessarily meet what the rest of the country has and expansive soil like crazy remember no rain for 9-10 months of the year.

Here's one for you...I just finished a project in Sisikiou County (right at the Oregon Border) rebar pattern was nuts and earthquake zone is less than the Bay Area, my buddy shows up from Oregon and laughs, he doesn't do no where near what I had and he is about 1 hour north, same seismic zone, different state, different engineer.

A 3" slab doesn't fly here, 4" is the bare minimum with rebar only and only as a non-structural slab. Most slabs I get are 6" non-structural with a 15x18" footing at bearing points.

insuldeck has a guide for posttensioning available.
if you need any help please email me.
[email protected]

Is the guide available online? I do not have a current application, I was just thinking.

insuldeck, I too would be interested to have a copy of your guide, thanks.

First, the theory seems to have gotten lost.  Concrete is a compressive building material; the tensioning (either pre or post) complements that strength.  Look at span charts for non-tensioned and tensioned concrete.

Second, Lite-deck seems to differ from Chris' engineer -- if you noodle around their web page (liteform.com), in the lite deck section, you'll see photos of post-tensioning lite deck supported slabs. 

That said, listening for the experienced guys' comments.

If you fill out a form, you get almost immediate access to the insul-deck post tension.

Here's a video on post tension.....


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We post tensioned a lite deck slab for a safe room lid back in April. It was 6" lite deck with 8" top hats. It worked fine.

Virgil Schmidt

 

to all who want our technical cd please email your address to
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Insuldeck,

What kind of spans can you get with garage type live loads?

You can download the Post-Tensioning Guide for Quad-Deck / Insul-Deck - registration is required. The Guides are for ESTIMATING purposes only. A licensed engineer has to provide specifications for each structure and its shoring depending on your specific requirements.

Longer spans may be achieved by increasing the T-beam height profile with sheet foam added to the Quad-Deck. Other design features, like additional reinforcing steel, post tensioning, or camber can also increase spans or loading.

We can provide you with a list of engineers who use the latest calculation techniques for these structures so you may not even need to post-tension. Just contact us through our website.

Happy New Year!
Georg Kustermann

icfconstruction,
as george has posted above, spans and load capabilities are dependening on panel height/joist depth and structural engineering. panels are 12.5" high maximum from production, but can be increased by adding eps top caps. we can basically span as far as a poured in place one-way T-beam slab can span, when designed according to ACI 318. 40 feet or more are possible, but you have to consider overall floor thickness and cost, as shorter spans will be less expensive, when combined with flush or dropped down concrete/steel beams, which are formed/installed and poured at the same time as the floor, and can be supported by columns as needed.
as to what is possible, think of the 100' long pre-cast, pre-stressed concrete beams you see traveling down the highway for interstate and coastal bridge construction.
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