Regarding anchor bolt design for pier foundation.
Regarding anchor bolt design for pier foundation.
(OP)
Hi all,
I have a question regarding anchor bolt design for pier foundation.
Structure has 4 square piers sitting on 11' square mat foundation. I am checking the existing anchor bolts of 1'-6" typical square pier foundation for tensile load of 70 kips and shear force of 4 kips in both directions on typical pier. Pier has, 8 #5 vertical bars and #4 stirrups. It has two 1" dia A615 Gr 60 anchor rods placed diagonally and embedded 3'-2" into the pier foundation. The clear spacing between anchor rods on either side is 6" and clear distance to the edge from typical anchor rod is 6" on either side. I checked the anchor bolts for steel tensile strength, pull out resistance of anchor in tension, side face blowout resistance, interaction equation, and embedment depth analysis per ACI 318 Appendix D. Anchor bolts passed for all the above checks except for side face blowout resistance.
I thought of three alternatives,
1: Add two additional hilti anchor bolts embedded 10" into the existing pier as general engineering judgement.
2: Add extra concrete (increase the pier size to 2'6" from 1'6") to increase the side face blowout resistance.
3: Do nothing and check the existing anchor bolts for only anchor strength and embedment depth assuming the pull out resistance and side face blowout resistance is taken by pier reinforcement. Since Appendix D calculations are only for plain concrete.
Can anyone suggest me which one is the best solution?
Any help will be greatly appreciated.
Thanks and Regards,
Sagans.
I have a question regarding anchor bolt design for pier foundation.
Structure has 4 square piers sitting on 11' square mat foundation. I am checking the existing anchor bolts of 1'-6" typical square pier foundation for tensile load of 70 kips and shear force of 4 kips in both directions on typical pier. Pier has, 8 #5 vertical bars and #4 stirrups. It has two 1" dia A615 Gr 60 anchor rods placed diagonally and embedded 3'-2" into the pier foundation. The clear spacing between anchor rods on either side is 6" and clear distance to the edge from typical anchor rod is 6" on either side. I checked the anchor bolts for steel tensile strength, pull out resistance of anchor in tension, side face blowout resistance, interaction equation, and embedment depth analysis per ACI 318 Appendix D. Anchor bolts passed for all the above checks except for side face blowout resistance.
I thought of three alternatives,
1: Add two additional hilti anchor bolts embedded 10" into the existing pier as general engineering judgement.
2: Add extra concrete (increase the pier size to 2'6" from 1'6") to increase the side face blowout resistance.
3: Do nothing and check the existing anchor bolts for only anchor strength and embedment depth assuming the pull out resistance and side face blowout resistance is taken by pier reinforcement. Since Appendix D calculations are only for plain concrete.
Can anyone suggest me which one is the best solution?
Any help will be greatly appreciated.
Thanks and Regards,
Sagans.






RE: Regarding anchor bolt design for pier foundation.
RE: Regarding anchor bolt design for pier foundation.
RE: Regarding anchor bolt design for pier foundation.
sideface blowout is not an issue if you meet minimum edge distance per anchor bolt design for piers.
attach is a good reference for that
RE: Regarding anchor bolt design for pier foundation.
@delagina, thanks for the reference, i went through the reference and it seems like if provided edge distance is > 6do then side-face blowout can be prevented. In my case, the edge distance is exactly equal to 6in (6X1" dia), is it safe to assume side face blowout resistance is ok or should i check per ACI 318 D4.2.1?.
Thanks and Regards,
RE: Regarding anchor bolt design for pier foundation.
if your bolt fail in side face blowout per ACI even if you meet you edge distance then that guide is wrong.
but i doubt it, there is probably an error in your calcs.
RE: Regarding anchor bolt design for pier foundation.
Please find the attached calculation i performed following the reference.
At your convenience, can you please comment on my calcs, that will be of very great help.
Thanks a lot again.
RE: Regarding anchor bolt design for pier foundation.
and you have grade 60 Abolt?
seems like yours doesnt match the "usual" 4-bolt, grade 36 Abolt that reference used.
sorry i dont have time check your calcs line by line
RE: Regarding anchor bolt design for pier foundation.
delagina, anchor ties can be designed to take side blowout, not pier ties. Pull out rebar does not help as far as I know.
RE: Regarding anchor bolt design for pier foundation.
RE: Regarding anchor bolt design for pier foundation.
These examples are based on ACI 318-08 Appendix D, with Anchor Reinforcement design using above mentioned reference
RE: Regarding anchor bolt design for pier foundation.
The A615 has little control on carbon content, IIRC and is difficult to weld.
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