Stirrup Spacing for Grade Beams
Stirrup Spacing for Grade Beams
(OP)
Looking for the maximum spacing requirements for stirrups in 24" deep grade beams. The stirrups would be used to hold the rebar in place, essentially as ties for the reinforcement as they would not be required for shear. I'm thinking 48" O.C. would be sufficient, but are there any other codes pertaining to maximum stirrup spacing?
ACI 318 Section 11.5.4 provides stirrup spacing requirements for shear; however, minimal shear is occuring.
IBC 2006 refers to ACI 318.
WRI: Design of Slab-on-Ground Foundations states "FOR BEAMS 36" TO 54" DEEP USE #3 STIRRUPS AT MAXIMUM 24" O.C."
ACI 318 Section 11.5.4 provides stirrup spacing requirements for shear; however, minimal shear is occuring.
IBC 2006 refers to ACI 318.
WRI: Design of Slab-on-Ground Foundations states "FOR BEAMS 36" TO 54" DEEP USE #3 STIRRUPS AT MAXIMUM 24" O.C."





RE: Stirrup Spacing for Grade Beams
Technically, to get extra shear, 21" would be the max considering cover for the depth.
A little extra shear capacity never hurt anyone.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Stirrup Spacing for Grade Beams
With typically low shear, and in our area, fairly deep grade beams (3'-6" below grade) the shear is way below φVc/2 so stirrups aren't required by code.
RE: Stirrup Spacing for Grade Beams
RE: Stirrup Spacing for Grade Beams
RE: Stirrup Spacing for Grade Beams
For example, #4 closed stirrups for a 100' x 200' building with a uniform 2' x 2' grade beam, spaced at 21" o.c., should cost about $1800. The cost at 48" o.c. will be about $800. (Based on a rough approximation of installed cost at $1/pound. Wholesale cost of rebar was about $750/ton last month.)
RE: Stirrup Spacing for Grade Beams