ACI 318-05, Equation D-17 and D-18 3

I would not use a hooked anchor rod for any kind of tensile load. AISC also recommends against it. It is prone to localized crushing of the concrete at the hooked followed by a straightening and pulling out of the anchor.

Thank you for your reply.

I am aware that hooked anchor bolts have low tensile capacity in concrete. I am also aware that AISC recommends against using hooked anchor bolts in tension. However, AISC is not the governing code when determining the capacity of a hooked anchor bolt in tension, at least for concrete failure mechanisms.

Given a choice, I would not use this type of anchor bolt, but my particular situation requires me to determine this capacity, so I need clarification of the ACI code.

ACI indicates in that section that it is for side face blowout of headed anchors. So the three options we could consider are:

1. Since that section is for headed anchors, does it simply not apply for hooked anchors?

2. Since that section is for headed anchors, does it mean that hooked anchors will always fail and be "no good"? If so, then any hooked anchor that has any tension will be unacceptable.

3. Since that section is for headed anchors, does it mean that ACI has no knowledge of side face blow out for hooked anchors and therefore is simply silent? Thus, the engineer must decide what to do on their own or by other research/knowlege.

Number 1 seems the most feasible but I'm not sure.

Having to choose, I would agree with your number 1, JAE. My reasoning is that the side face blowout is a failure from lateral pressures developed from the head bearing on the concrete. Since a hooked rod has a longer bearing length (and presumably away from the edge, not toward it), those lateral bursting pressures wouldn't be as great.

I like JAE's 1,2,3 summary. In my opening statement in this discussion thread, I alluded to JAE's #3 option, that is, ACI does not have the research background to formulate equations for this type of failure, and is therefore silent.

From a practical standpoint, I find it hard to believe that a headed anchor bolt can fail in this manner but a hooked bolt can not. A hooked bolt with a short hook can't be that different than a headed bolt with a large head.

Nonetheless, since ACI describes the section as being for HEADED, I have nothing else to go on but believe that JAE's #1 applies, and this failure mechanism does not need to be checked for HOOKED.

I wish someone from the ACI committee that produced this would provide some guidance. To submit a technical question to ACI requires membership, and that requires $...

Hi all;

The Canadian version CSA A23.3 Annex D commentary states:

"These equations are not applicable to J or L bolt anchors for which there are currently no side face blowout expression. L blots located in close proximity to a free edge with the hook orientated parallel to the free edge will exhibit a blowout type failure. With no expression provided for this L bolt failure, designers are encouraged to use headed anchors in close proximity to free edges"

...or orient the hook AWAY from the face.