ACI-318-99 section 7.2 contains min. bend diameters for rebar. Inside diameter for #3 - #8 bars is 6 x dia of bar.
What type of anchor rod is it? Chapter 6 of the AISC Manual of Steel Construction Volume II Connections has information on anchor bolts, but I don't see any info about bend diameters here. It is probably in the ASTM spec for the type of bolt being used.
ASTM F1554 provides guidance for the bend geometry for Grade 36, 55 and 105 anchor rods. I do not know where to find this information for stainless steel anchor rods. It is my experience that bends in anchor rods are much tighter than for similar size rebar. Also, hooked anchor rods do not develop as hooked rebar in concrete. I am recommending to our structural engineers that if you want to develop an anchor rod, it must have at least the same development length as a rebar of the same diameter.
In addition to the ASTM F1554, I think ACI-318-02 Appendix D addresses hook size for anchor bolts. In general the industry is getting away from hooked anchor rods as they are very limited in resisting tension loads.
