Quote (OP)

As I read the code, the rails are supposed to perpendicular to the face of the column.

Where exactly did you read that? My understanding is that radial stud rail layouts have been shown to be somewhat superior to orthogonal layouts and are sometimes details that way outside of north America.

Quote (OP)

If I orient the stud rails to the face of the column, the placement of the tendons and top steel will be difficult to thread through the stud rails.

I agree with your concern regarding constructability issues. Any chance you could just have a capital or drop panel at this location to deal with punching shear? Obviously, that screws up the usual desire to have simple, flat plate formwork.

Unless things are very congested, I suspect that your tendons could often be woven through the studs successfully. I probably wouldn't bother with the rails that you show oriented vertically as I suspect that they won't be very effective.

Interesting case. Definitely agree with KootK that dropping the vertical rails shouldn't impact your punching perimeter much, if at all, since you are at the slab edge.