I have observed the following discrepancies in the anchor chair calculations between TANK and the AISI formulas. Hopefully there is a simple explanation.

Reviewing the Anchor Chair Calculation output, "Local stress at the top plate per AISI" uses the anchor bolt eccentricity (e); whereas the AISI formula uses the distance from the outside edge of the top plate to the edge of the bolt hole (f). The formula is otherwise the same. The (f) vs. (e) substitution is also true for "Stress in the Top Plate at given Thickness". Was this substitution intentional and if so, could someone explain why? The results are generally different whether e or f is used. Thanks.

I cannot check now what is there, however I think (f) vs. (e) substitution cannot be correct.

The reason is that AISI says "critical stress in top plates occurs between the hole and the free edge of the plate", and AISI presents a specific bending model applied to a "beam" of sectional dimensions as fxc.
That bending stress must be proportional with 1/fc^2 since fc^2 is coming up from section modulus. No "e" appears in this section of calculation.

When calculate bending stress transmitted to shell, the bending stress is proportional with the bending moment and that means is proportional with "P*e". Here "f" cannot be considered.

Best regards.