Ultimate bond stress of Plan Anchor bars

[Zafery]

Sirs
Can anybody suggest any reference for bond stress as per ACI-318..

i want to calculate the bond strength of anchors is tension. Since I don't have any America code reference, I am using BS8110-1 Clause 3.12.8.4.
ultimate Bond stress, Fbu = β Sqrt(Fcu).
We are using 4000psi Concrete, cylindrical strength f'c= 4000psi = 27.57 Mpa
Since we are using formula from BS, The Fcu Value should be cubic. therefore I will convert my
cylindrical strength to cubic strength
Fcu = f'c / 0.8 = 27.57 /00.8 = 34.46 Mpa. (β = 0.28 for plain bars)

Fbu = 0.28 x Sqrt (34.46) = 1.64 Mpa.

In the procedure ok, kindly advise..

 

[WARose]

Except for adhesive anchors, concrete anchors in ACI do not transfer their load by "bond". The failure mode is different for headed (plain) anchors.

 

[Zafery]

Noted, however If we design anchor bolt as per ACI 318 appendix-D, the size of the pedestal/column is coming very huge, because of low concrete breakout strength and large edge distance and anchor to anchor distance requirements. As the Appendix-D procedure does not consider the effect of reinforcements. Even though as per D.4.2.1 we can take advantage of reinforcements in restraining concrete breakout. But how to use reinforcements to stop breakout, I did not found any reference in ACI.

because of this I was trying to use BS formula..

I saw same examples on net, some people provide additional reinformcents equal to anchor capacity around the anchor for all anchors, and they din not check concrete breakout strength as per D.5.2 (tension) and D 6.2 (Shear). however this procedure requires huge amount of reinforcements.

Therefore can we take advantage of the columns reinforcements itself and check, weather these reinforcements will be enough to prevent concrete breakout in tension and shear.
Kindly share your opinion..

 

[KootK]

Link

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[P205]

As per KootK's link, look at figure 3, you can effectively lap the anchors with the pier reinforcement which, to my understanding is an alternate method to using ACI 318.