anchor bolt appendix D 3

[0444]

the get satisfactory of break-out in tension I need to increase the edge distance to at least 30 inches which there is no room to get more that 18 inches. base on appendix D we could design supplementals reinforcement instead of increasing the edge distance, but I don't know how to design this. can somebody answer my question?
Thanks.

 

[Ron]

Interrupt the shear plane with reinforcement.

 

[JedClampett]

Something sounds wrong here. How deep are your anchors embedded?

 

[0444]

The max. embedment is 25"=heff
question is about ACI D.4.2.1
Thanks.

 

[sdz]

For anchors in tension in a pedestal you will normally have to rely on the pedestal reinforcement to carry the load. The vert pedestal bars have to have anchorage both sides of the potential failure plane which could be a horizontal plane level with the bolt head or a 3/2 slope as shown in App D.

 

[0444]

sdz, Thank you so much for your advice. Could you please also let me know what would be the embedment hef design for? only for shear break out ? I was wondering what would be the Ld of anchor when we rely on the pedestal rebar..
I hold off the calcs to send out until to get the resolve..
Thanks a lot.

 

[WillisV]

The embedment of the anchors should be deep enough to allow pedestal rebar to be developed above where the concrete breakout plane crosses the rebar.

 

[0444]

Hi WiiisV,
Could you please see the attached file if I am understanding correctly?
I appreciate it

 

[WillisV]

That is the basic idea - I didn't look at any of your numbers but as long as both (L1+L2) and (L3) exceed the development requirements (it must be developed on both sides of the breakout plane) and the strength requirements are met you are OK.

Some general notes is that the hook (if used) is generally at the top to minimize development length so as to decrease required anchor embedment. Also a phi factor of 0.75 is generally used (see ACI 318-08 D.5.2.9) for reinforcing resisting tension loads in lieu of concreate breakout.

 

[Lion06]

I would try to get the reinforcing closer to the anchor rods. We specify 2" max in our typical detail. If the pier is significantly larger than the baseplate such that it won't be close to the anchor rods, we provide additional reinforcing.

Here is a paper that will help you with the design.