ACI D.6.2.7 - Supplemental Reinforcement for Anchors

[humanengr]

Per ACI 318-11, D.6.2.7, the cracked concrete modification factor = 1.2 may be used if
"a No. 4 bar or greater (is) between the anchor and the edge.."

There is no commentary and no specifics are given.

Just wondering if anyone has more info. on where the #4 (or greater) bar must be placed. Any requirements regarding position with respect to failure surface / assumed failure surface?
Any requirements for bar length / to what point the bar must extend? Any requirements to develop the bar / provide hooks at end of bar?

A sketch is provided for reference.

 

[TehMightyEngineer]

I agree, it's quite vague. The PCA notes offers no additional help.

The intent is clearly to stop cracking at the free edge of the concrete in the direction of load. I would imagine you would need something developed fully on either end of the centerline of the anchor bolt group and positioned similar to the "edge reinforcement" as shown on fig. RD.6.2.9(b) of the 2011 spec.

Professional and Structural Engineer (ME, NH)
American Concrete Industries

http://www.americanconcrete.com