Bundling reinforcing vs. minimum spacing
Bundling reinforcing vs. minimum spacing
(OP)
Is there a penalty in strength for using bundled bars to reinforce concrete beams as opposed to bars spaced out correctly? Other than longer minimum lap length for tension development, I can't seem to find anything.
The basis for my question comes from site visits. Occasionally, in an 8" joist, the two bars in the bottom will be essentially touching. It seems like it would be ok, as this is no different than bundling bars, even though the mininum is 3/4" spacing.
I'd like to hear everyone's thoughts and opinions on this.
The basis for my question comes from site visits. Occasionally, in an 8" joist, the two bars in the bottom will be essentially touching. It seems like it would be ok, as this is no different than bundling bars, even though the mininum is 3/4" spacing.
I'd like to hear everyone's thoughts and opinions on this.






RE: Bundling reinforcing vs. minimum spacing
φMn of the beam. However, ACI does have requirements for developing this longitudinal reinforcing and this is affected by the bundling (as you mention above). A few aspects I can think of:
1. Developing positive moment past supports (ACI 318 - 12.11.3)
2. Cutoff locations for negative reinforcing (12.12)
3. Hook development lengths
4. Class A laps required for structural integrity in 7.13.
5. Distribution of steel per 10.6 would force you into spreading out the bars anyway.
RE: Bundling reinforcing vs. minimum spacing
RE: Bundling reinforcing vs. minimum spacing
Hg
Eng-Tips policies: FAQ731-376
RE: Bundling reinforcing vs. minimum spacing
RE: Bundling reinforcing vs. minimum spacing
RE: Bundling reinforcing vs. minimum spacing
1. the clear distance between bars in a layer shall be the larger of db, 1 inch or 1.33 x MSA ..ACI 318 Sec 7.6.1, or
2. if bars are in same vertical plane, then clear distance shall be 1 inch...ACI 318 Sec 7.6.2
The reason for this is to prevent inter-alia, honeycombing as pointed out by UcfSE...ACI 318 R7.6
Is the bar size No.6..what is the MSA of the concrete mix?
RE: Bundling reinforcing vs. minimum spacing
what you don't want is air beside the bars.
Unless you've got a very runny mix and a very small aggregate size the bars should not be too close together without touching.
If you end up with air beside the bars you will later end up with water beside the bars and that's BAD.
RE: Bundling reinforcing vs. minimum spacing
RE: Bundling reinforcing vs. minimum spacing