Minimum Stirrup Spacing
Minimum Stirrup Spacing
(OP)
Hi all,
In ACI 3018 11.5.5.1, there's a minimum spacing stipulation of d/2 for perpendicular stirrups. This usually has not been a problem for me, but on my current project, I have a little cantilevered sidewalk on h=12" t-beams, making my d value only about 9". Stirrups spaced at 4.5" seems a bit excessive to me. Any advice on this would be appreciated. Thanks!
In ACI 3018 11.5.5.1, there's a minimum spacing stipulation of d/2 for perpendicular stirrups. This usually has not been a problem for me, but on my current project, I have a little cantilevered sidewalk on h=12" t-beams, making my d value only about 9". Stirrups spaced at 4.5" seems a bit excessive to me. Any advice on this would be appreciated. Thanks!






RE: Minimum Stirrup Spacing
If the beam is very stout like a slab you can get away from it. Also, if Vu<Vc/2, they aren't require (I think).
If you had to do stirrups, maybe consider using draped mesh instead. 4.5" stirrup spacing is silly.
When I am working on a problem, I never think about beauty but when I have finished, if the solution is not beautiful, I know it is wrong.
-R. Buckminster Fuller
RE: Minimum Stirrup Spacing
RE: Minimum Stirrup Spacing
Otherwise 4.5" oc doesn't seem that unreasonable to me. It is what it is.
RE: Minimum Stirrup Spacing
I have one more question regarding this though. On 11.5.5.3 it says "where Vs exceeds 4*sqrt(f'c)*bw*d, maximum spacings given in 11.5.5.1 and 11.5.5.2 shall be reduced by one half". This is another stipulation that has never given me trouble till now, but as Vs is proportional to Av, using more stirrups (which i would generally consider safer) can reduce your minimum spacing by half. As you might imagine, using #3's at 4.5" in my beam as mentioned makes Vs rather large, causing 11.5.5.3 to call for 2.25". What is up with this? Can you reduce the Vs to the Vsreq? That would make sense to me, but I'm just making it up.
RE: Minimum Stirrup Spacing
Or bump up the f'c to get more shear capacity.
When I am working on a problem, I never think about beauty but when I have finished, if the solution is not beautiful, I know it is wrong.
-R. Buckminster Fuller
RE: Minimum Stirrup Spacing
RE: Minimum Stirrup Spacing
Re. your 2.25' thing. Is that clause dependent on the Av you actually need, as opposed to what you've actually put in simply to satisfy spacing?
RE: Minimum Stirrup Spacing
RE: Minimum Stirrup Spacing
In your case if you reduce the spacing by half and recalculate Vs, it probably exceeds 11.5.7.9 Vs max of 8*sqrt(f'c)*bw*d. There's a logical bust there...
RE: Minimum Stirrup Spacing
RE: Minimum Stirrup Spacing
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RE: Minimum Stirrup Spacing