Concrete Anchor Bolt Design Calculation
Concrete Anchor Bolt Design Calculation
Concrete Anchor Bolt Design Calculation
Calculation of A Nco
Before going to the calculation please refer the plan view of the anchor arrangement as below:
Now, by putting all the values in D-5 we get the Concrete breakout strength for the anchor group
N cbg =(A Nc /A Nco ) ec,N ed,N c,N cp,N N b
= 0.70*(676/900)*1*0.82*1*1*48000 = 20694.6131 lb
so, finally we got the concrete break out strength of the anchor group in tension as 20694.6131 lb.
Part-3: Determining Pullout Strength of Anchor in Tension
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.
Calculation
According to ACI codes, the pull out strength of the group of anchors is given by
N pn =8n c,P A brg f c ..D-14
Where, Strength reduction factor for pull out strength and its value for non-reinforcement in tension is
0.70 c,P Modification factor for pullout strength based on the presence of concrete cracks, for the
concrete with cracks at service load level c,P =1.
n Number of anchor bolts, in our case n=4.
Where,
d a = Diameter of the anchor bolt in inch., in our case it is 0.75 inch. Remember we have started with the
0.75 inch anchor in the part-1 of this calculation.
l e = Length of the anchor inserted inside the concrete in inch. In our case it is 10 inch.
= A factor related to the reduced mechanical properties of concrete, for normal weight concrete =1.
C a1 = we already know it from the Fig.1. Its value is 11 inch.
f c = Specified compressive strength of the concrete, in our case f c =4000 psi (refer problem statement of
part-1).
So, by putting all the values, the above equation (D-24) becomes