ACI 318-11 D.5.2.9 Effective rebars tensile resisting distance

[LYO]

thread507-314031
Hello, appreciate with all the information shared within this thread.
From "Design of Anchor Reinforcement in Concrete Pedestal", to be considered effective resisting anchor tension, distance from anchor head to the reinforcement shall not be more than hef/3. From civilbay reference, this distance shall not be more than 8" (200mm). However, from ACI318-11, the figure shown for Clause D5.2.9, the figure was stating this distance shall not more than hef/2. The code does not explain any further.
Please, if anyone can guide me through which of these limitation should be valid and where they were referred from? Many thanks

 

[TXStructural]

To apply 5.2.9, the reinforcement must be developed on both sides of the notional crack. This means that you would determine the extents of the breakout cone, and develop bar or wire across the breakout cone surface. Section RD5.2.9 seems explanatory. Also refer to ACI 318-11 12.5 and 12.14 (in particular 12.14.2.3 for non-contact laps splice requirements - the maximum is 6")

The 318 Appendix D approach is to have one hairpin located adjacent to each stud or set of studs.

 

[LYO]

from RD5.2.9, "...The anchor reinforcement should consist of stirrups, ties, or hairpins placed as close as practicable to the anchor. Only reinforcement spaced less than 0.5hef from the anchor centerline should be included as anchor reinforcement."
If hef = 1000mm, so all rebars within 500mm (hef/2) radius can be taken into account as anchor reinforcement. But these rebars will be at a distance < 6" (150mm) as per 12.14.2.3 ...hence we shall provide hairpins as a medium in between anchor and rebars in order to make anchor reinforcement to effective?

 

[LYO]

sorry, correction, rebars are NOT at a distance < 6" as required in12.14.2.3.