Stirrups in One Way Slabs
Stirrups in One Way Slabs
(OP)
Hello,
I could swear I saw a reference in ACI-318 about shear stirrups allowed to project into the minimum required reinforcement cover. In other words the 3/4" cover would be only applicable to primary bars exempting #3 bars which would have less than 3/4"...
Can anyone help... I have spent so much time looking through 318 and I just can't find it...
Thank you!
I could swear I saw a reference in ACI-318 about shear stirrups allowed to project into the minimum required reinforcement cover. In other words the 3/4" cover would be only applicable to primary bars exempting #3 bars which would have less than 3/4"...
Can anyone help... I have spent so much time looking through 318 and I just can't find it...
Thank you!






RE: Stirrups in One Way Slabs
BA
RE: Stirrups in One Way Slabs
(13" total concrete depth)
RE: Stirrups in One Way Slabs
Generally the concrete joist systems I've seen have had a form of single legged stirrups.
In regards to the infringing on clear cover, I'd still be inclined to maintain at least 3/4" to any steel (main steel or stirrups).
RE: Stirrups in One Way Slabs
Yeah - single leg S or Z shape...ACI allows one single bar to be bent into squared snake form along the joist where the horizontal legs (at top and bottom) simply develop into concrete - not having to tie into bottom or top bars of the T beam - kind of neat... Though logically Id like my stirrups to be anchored around primary steel.
RE: Stirrups in One Way Slabs
RE: Stirrups in One Way Slabs
Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries
www.americanconcrete.com
RE: Stirrups in One Way Slabs
In spite of the thread title, the OP is talking about pan joists.
RE: Stirrups in One Way Slabs
Still, I would modify my point to agree with what you said hokie; widening the ribs or otherwise providing more concrete shear strength would appear to be cheaper unless you needed to save weight or depth.
Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries
www.americanconcrete.com
RE: Stirrups in One Way Slabs
Appreciate everyone's input - all good solid advice!
RE: Stirrups in One Way Slabs
Well then, can you shorten them? I.e., make the beams wider?
RE: Stirrups in One Way Slabs
RE: Stirrups in One Way Slabs
Depth can vary but i am already using the deepest form that creates 10" depth.
I notice using higher strength mix reduces shear but ever so little.
I wish I could find that place in 318 where it allows shear steel to protrude past primary rebar into 3/4" cover...
RE: Stirrups in One Way Slabs
RE: Stirrups in One Way Slabs
Your rib width, depth and spacing complies with ACI 318-11 §8.13.2 on joist construction, so you are permitted under §8.13.8 to increase your Vc by 10%, if you have not done so already.
RE: Stirrups in One Way Slabs
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.
RE: Stirrups in One Way Slabs
Perhaps you could consider using sections of deformed welded wire mesh (WWM) as shear reinforcement at the ends of each joist. They would be fairly simple to install and fabrication costs should be relatively low. You should not encroach into the 3/4" cover, however.
BA
RE: Stirrups in One Way Slabs