Please refer the problem statement and the part-1, part-2 of this cast in place concrete anchor bolt design calculation example so that you will be in phase with this part (part-3) of the calculation. Here we will calculate the pull out strength of the concrete anchor according to the ACI 318 Appendix D codes.
What is Anchor Pullout Strength?
As the name suggests, it is the force required to uproot a anchor out of the concrete.
According to ACI codes, the pull out strength of the group of anchors is given by
Φ – Strength reduction factor for pull out strength and its value for non-reinforcement in tension is 0.70
ψc,P - Modification factor for pullout strength based on the presence of concrete cracks, for the concrete with cracks at service load level ψc,P=1.
n – Number of anchor bolts, in our case n=4.
Abrg – Net bearing area of the head of anchor bolt in square inch, in our case Abrg=0.654 Square inch.
f’c – The concrete’s specified compressive strength in psi, in our case f’c=4000 psi.
So, by putting all the values in D-14, we get the pullout strength of the anchor group as
φNpn =0.7*8*4*1*0.654*4000 lb
= 58598.4 lb
In the next part (Part-4) of the foundation anchor bolt design calculation example, we will discuss about calculating the concrete blow out strength in tension.