Anchor reinforcement as per appendix-D ACI318-08

[h-badawy]

Dear experts

i have a casted/existed concrete pedestal with anchor bolts in the site now and due to some of problems the superstructure redesign and moment applied to the pedestal increased and lead to increase the total tension force on the group of anchor bolts and the concrete strength fail in the breakout according i need to put extra reinforcement in the pedestal, however the current/ existing reinforcement is sufficient for both breakout and design of pedestal, the thing is ,that As per ACI318-08 appendix-D ,the Only reinforcement spaced less than 0.5hef from the anchor centerline should be included as anchor reinforcement while not all the anchor bolts near the above distance (g= hef/2) from the reinforcement, my question is ,the anchor reinforcement should be placed near to all anchor bolts with (g)distance or the outer anchor can only cover the reinforcement especially the anchor working as a group.
( please see the snap bellow).

Thank you

 

[HTURKAK]

If you draw the potential failure surface for tension failure mode, you will see the reason for the detailing of tension reinf.

The following excerpt from ACI 318 -14

 

[h-badawy]

I don’t have any doubt in this sketch, my concern regarding to the highlighted yellow anchors in the middle which are not in the range of g=hef/2 from the reinforcement anchors, if reinforcements near to the edge of outer anchor bolts are sufficient for the extra breakout tension force , so no need to be near to the internet anchors which are located in a distance more than g ????

Thank you

 

[HTURKAK]

If the distance ( g ) satisfies the requirement to be less than hef for green anchor ( and apparently g ≤ hef as per the sketch ), yes.. If you draw the failure surface for tension failure, you will see. What is the reason for 16 anchors for one side ?

 

[h-badawy]

The reason of using 16 anchors in one side is the moment transferred from the steel column is vr high.
Do you mean if the two yellow anchors in the middle are not satisfied the distance (g) , i remove these two anchors from the calculation and check again the need reinforcement anchor ????


Thank you