when you say "so long as as your column plastic hinge takes proper account of any axial load in the column" you are referring to ACI-318-11 21.6.5.2 Transverse reinforcement: a) and b):
(a) The earthquake-induced shear force, calculated in accordance with 21.6.5.1, represents one-half or more...
In all of the examples I have seen regarding column shear reinforcement for a special moment frames, they use a column that is not at the top of the building, they all have a column framing above and below it (ACI 318-11 R21.5.4). So when the calculate Mpr for the beams tying into the column...