×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Bottom rebar in slab over steel deck - clear cover?

Bottom rebar in slab over steel deck - clear cover?

Bottom rebar in slab over steel deck - clear cover?

(OP)
I have a 6" total thickness slab over steel deck (4.5" concrete over 1.5" B deck) that has been designed for forklift loading. Following SDI's (Steel Deck Institute) guidelines, the deck is form-only and reinforcing has been provided to support the forklift loading.

The bottom rebar is intended to be in a low flute, with a little over 1" clear from deck to bar. The "d" depth of the bar is 4-1/2" from the top of the slab. Obviously this is my primary design concern - I want to maintain this effective depth.

At some locations, headed studs and spliced bottom bars result in the bars being pushed up against the side of the flutes (still maintaining the correct "d" depth and cover below), which means some of these bars no longer meet ACI clear cover of 3/4".

A couple of questions:


Is anybody aware of any guidance on bottom of deck clear cover for a slab on steel deck? ACI does not specifically address slabs on steel deck and SDI seemingly references ACI clear cover requirements, but they are clearly aimed at the clear cover to the top of the slab.


Are these bars still effective if they are up against (or very nearly up against) the side of a flute?



I'd appreciate any experience or code/standard references. I've reached out to SDI and am awaiting a response, but I thought I would ask here as well!

Thanks!

RE: Bottom rebar in slab over steel deck - clear cover?

I've typically worked in corrosive environments, ergo I treat the deck like it's not even there. (Other than providing a form.) Perhaps in non-corrosive environments this isn't so much a consideration.

Quote:

Are these bars still effective if they are up against (or very nearly up against) the side of a flute?

I would think only partially.....because they cannot develop on one side. You would also not be observing minimum cover requirements (as per the "corrosive environment" approach).

RE: Bottom rebar in slab over steel deck - clear cover?

Most deck manufacturers do not recommend their decking be used for moving loads... unless the deck is used as a concrete form. For non corrosive environments, I've used a bar placement to suit the 'flutes' with the support bars bearing directly on the deck.

Dik

RE: Bottom rebar in slab over steel deck - clear cover?

(OP)
I got a response back from SDI:

Quote (SDI)

Reinforced concrete slabs using permanent steel deck for forms must be designed in accordance with ACI-318. There is no exception for that in any of our Standards

So proper ACI concrete cover is required period. Bars laying directly on/against flutes would NOT be OK.

I'll be approaching this by getting the bars shimmed off of the sides of the flutes while eating into the allowable 3/8" tolerance on effective depth and clear cover.

RE: Bottom rebar in slab over steel deck - clear cover?

Jittles... by placing the bars in the flutes, I've achieved concrete cover as required... I'm happy, others may not be...

Dik

RE: Bottom rebar in slab over steel deck - clear cover?

Have you considered a 2" deck? They typically have much wider flutes that will allow more room for the studs and the bars to be lapped.

RE: Bottom rebar in slab over steel deck - clear cover?

Interesting dilemma. I'd not considered this before. You could also not carry the bars over the beams if the beam spacing is large enough for that to be somewhat sensible.

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.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources