The current RM bridge ultimate capacity calculations allow for material reduction factors only, which are not used by AASHTO for reinforced and prestressed concrete. AASHTO concrete reduction factors for flexure and P-M capacities are based on the tensile strain of reinforcing (or prestressing) at ultimate capacity, where the resistance factor is lower when the section is compression controlled and higher where it is tension controlled. See Figure C5.5.4.2-1 of AASHTO 9th edition for more information. In order to create an accurate factored ultimate resistance for plots and RMSets, I would propose an update to calculate the AASHTO resistance factor for ultimate concrete capacities and create a factored ultimate resistance .sup file with that factor.