In this part (part-5), we will see the concrete anchor bolt design calculation example for calculating anchor material (steel) strength in shear according to the ACI 318 appendix D codes. But before that, please go through the problem statement and part-1, part-2, part-3 and part-4 of this series.
The formula for determining the steel strength in shear given in the American Concrete Institute code is:
Steel strength in shear, φNsa = φnAse,Nfuta……………………..D-19
Φ – Strength reduction factor and its value for ductile anchor bolt in shear; the value of it is 0.65
Nsa – Nominal shear strength of the group of anchor in lb
n – Total anchor number in the group, in our case the value is 4
Ase,N – Effective cross sectional area of a single anchor, the value of it for the 0.75 inch anchor bolt is 0.334 square inch.
futa – Specified tensile strength for a single anchor (to be obtained from manufacturer’s catalog) in psi, in our case the value is 75000 psi.
Now, by putting the values in the equation D-19 explained above, we can obtain the value of the steel strength for the group of anchor is:
Φ Nsa = 0.65*4*0.334*75000 = 65130 lb
You might have already observed that only difference between calculating the cast in place anchor bolt material strength in shear and in tension is the strength reduction factor. For shear it is 0.65 and for tension 0.75. Also, please remember that in both the cases we used Specified tensile strength.
In the next part (Part-5) we will see the calculation methodology for Breakout Strength of Anchor in Shear.