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RE: WWF in slabs on form deck

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All concrete cracks (eventually).
What reinforcing does is reduce crack width. The more the reinforcing, the smaller the crack width. That's why I don't believe fiber reinforcement is effective in reducing cracking, other than the spider cracking when concrete cures too quickly.
Personally, I don't think WWF is very effective in reducing cracking mainly because I don't have much confidence that it will be placed in the upper third of the slab (after installers walk all over it).
I like the idea of placing a short length (2*l_sub_dh) bars centered over support beams placed in the top third of the concrete section.
Just my two cents.
T. William (Bill) Allen, S.E. (CA #2607)
V/F (949) 248-8588
San Juan Capistrano, CA
-----Original Message-----
From: Seth W. Cutler [mailto:seth(--nospam--at)]
Sent: Thursday, May 29, 2003 8:36 AM
To: seaint(--nospam--at)
Subject: Re: WWF in slabs on form deck

Here's a question for you:

Doesn't the concrete have to crack to activate the WWF?  Just wondering.  The only slab on metal form deck that we do is non-composite because we use open web bar joists and they're normally not more than 4'-0" o/c.  We have been using a  4" total thickness on a 1 1/2" pan-deck to provide a stiffer floor due to their use.


At 07:10 AM 5/29/2003, you wrote:
I was wondering how others feel about the amount of WWF required in
slabs on metal form deck?  Take for example a 3" slab on 9/16" form
deck-if you look at the ACI criteria, 6.0x6.0x1.4x1.4 does not provide
enough area for temperature and shrinkage, you would need to go to the
2.9.  In talking to the engineer I work under, he has never had a
problem in the 18 years he has practiced with the 1.4.  I also called
another engineer at a metal deck provider and he said he has seen the
1.4 for over 40 years.  I am just trying to gauge how others feel about
this.  Thanks to all in advance for any help.

Chris Bowers, EIT
A/E Building Systems - Structures
L. Robert Kimball and Associates
Ebensburg, PA
Phone:814-472-7700 xtn.350

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