Dear Hrushi,
Just to add some something, the ASME Sec. Div. 1 allowable for bolts are conservative. In the structural field the anchor bolts have tensile allowable and shear allowable. With shear allowable being less.
But, ASME Sec. VIII Div. 1 provides one allowable for the bolts and that seems to be smaller than shear allowable used in the structural engineering. I think I compared SA-307.
So, look at the allowables that you are using too. You may be getting some inherent conservatism using ASME allowables.
I agree with Ray that friction is considerable, this is also mentioned in many engineering handbooks dealing with anchor bolt design.
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Best Regards,
Mandeep Singh
CADWorx & Analysis Solutions
Hexagon PPM