Radiant heat in concrete on composite deck 1

[bouk715]

Does anyone know of design guidance for composite slab and composite beam design to incorporate radiant heat tubing? I'm having some trouble finding any design examples/tech notes online.

We are designing a floor system with concrete slab on composite metal deck supported by steel beams. The beams will also utilize shear studs to engage composite action with the slab. The architect/MEP is considering adding radiant heat tubing to the slab and I'm trying to figure out how to take it into account in the design.

Could we just determine the compression block depth "a" in the slab and make sure the tubing isn't within that depth? Or are there additional considerations that need to be made? Adding a concrete topping to set the tubing in could be an option, but would add considerable concrete and beam weight.

Any guidance is greatly appreciated.

 

[jike]

Is this an interior structure? If so, no topping is normally required unless drainage is necessary. If an exterior slab, then you will need a membrane plus a topping.

It is unlikely that radiant heat tubing will affect the compression block but you could do a calculation to reassure yourself.

 

[bouk715]

Thanks for the quick response! Yes, this is an interior slab. 2" deck with 3" of concrete over the top of the deck (5" total thickness).

 

[jayrod12]

I'm pretty sure that a couple of the manufacturer's have released information on this, specifically for the beam composite action.

I vaguely remember a previous thread on this somewhat recently. I'll see what I can dig up. Depending on the size and number of lines required there are reductions that need to be taken into account.

 

[bouk715]

Thanks jayrod12...I wasn't able to find anything online or in a thread search, but let me know if you know of something.

 

[KootK]

I remember that thread. There was an article attached to it too. I can't find it unfortunately. ASCE 3-91 says:

- max conduit size = min (25 mm, 1/3 cover)
- no crossovers. have fun enforcing that.
- 18" min spacing.
- min 25 mm cover.

My fuzzy recollection of that other thread is that the article specified a min spacing from studs. Six inches maybe? In specifications, I've seen prohibitions against both tying conduit to studs and placing conduit in the deck flutes.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[bouk715]

KootK - good info. My recollection is that ASCE 3 is for any type of conduit, so it seems that radiant heat would probably be captured under that. The 18" minimum spacing could be tough too...I'll have to talk with the MEP as I recall that the heating loops usually have a tighter spacing than that (12" or so).

 

[jayrod12]

The one paper I read mentioned the no crossovers. However if you in general oriented the tubes parallel to the beams I would think the odd cross over for tie in would be trivial.

However that was for the beams only, I'm not sure how it would work for the deck composite action, I guess if you kept it out of the flutes then I can't see a huge issue.

 

[bouk715]

http://www.eng-tips.com/viewthread.cfm?qid=252077

Is this the thread you are recalling?

 

[KootK]

No. I'd say it was within the last six months. And it had me as a responder. And there was an attached article.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[bouk715]

Ok...haven're been able to find that recent. I'll look a bit more. Do you recall if it was about radiant heat or just conduit in general?

 

[jayrod12]

might've just been conduit in general.

 

[jayrod12]

found it

http://www.eng-tips.com/viewthread.cfm?qid=378722

 

[bouk715]

Just wanted to post a last follow-up for anyone looking at this post in the future. After quite a bit of searching, I did find an article that provided some recommendations and considerations for radiant heat in composite slab/beam design.

http://www.newsteelconstruction.com...composite-floors-effects-on-slab-beam-design/

Thanks again for all the helpful responses.