Minimum Steel Reinforcement in Retaining Wall
Minimum Steel Reinforcement in Retaining Wall
(OP)
I'm looking for some clarification regarding the exemption for minimum reinforcement given in ACI 318 10.5.3 (allowed where As provided is at least 1/3 greater than required) versus requirements for a minimum spacing of reinforcement steel of 18" in sections 7.6.5 and 14.3.5. This came up in a cast-in-place retaining wall design (relatively small, 10' high). Specifically, I was wondering if you can use the exemption of 10.5.3 to allow for cutting off alternating bars or are you stuck with the 18" max spacing?






RE: Minimum Steel Reinforcement in Retaining Wall
RE: Minimum Steel Reinforcement in Retaining Wall
RE: Minimum Steel Reinforcement in Retaining Wall
Dinosaur - there are requirements for development that necessarily extend the rebar beyond the point where they're needed, but it's relatively small (6" for #4) so if you truly exceed the 18" limitation, there is some economy in cutting of alternating bars.
Still, I would think the 18" max is there to ensure the reinforcement behaves properly in the system. Otherwise it might be that you have to look at the wall as a structural plain concrete design?
Thanks for your input.
RE: Minimum Steel Reinforcement in Retaining Wall
To me, the 18" requirement is a "good practice", rather than mandatory, to prevent wide cracks. Actually, for certain cases, you may need more bars in a closer spacing to achieve that purpose (crack control).
RE: Minimum Steel Reinforcement in Retaining Wall
RE: Minimum Steel Reinforcement in Retaining Wall
I would never have less primary reinforcement in a slab or wall than was required for shrinkage and temperature. No matter what the minimum area of steel is, you can't exceed a bar spacing of 18" or 3 times the thickness.
I believe that the intent of 10.5.2 and 10.5.3 is for beams, where you could have a concrete section much bigger than needed. A grade beam could be an example of this.
RE: Minimum Steel Reinforcement in Retaining Wall
RE: Minimum Steel Reinforcement in Retaining Wall
thanks alot
regards
RE: Minimum Steel Reinforcement in Retaining Wall