5.1.2 H1 Minimum Flexural Reinforcement:
g_{1} = 1.56, which can be reduced to 1.2 for precast segmental structures. g_{2} = 1.1 g_{3} = the ratio of yield stress to ultimate stress of the reinforcement. For prestressed concrete structures, use 1.0.
Appropriate values for M_{dnc} and S_{nc} shall be used for any intermediate composite sections. Where the beams are designed for the monolithic or noncomposite section to resist all loads, substitute S_{nc} for S_{c} in the above equation for the calculation of M_{crmod} .
This memorandum incorporates the recommendations for the NCHRP Report 149, LRFD Minimum Flexural Reinforcement Requirements. It revises 1.2M_{cr} to be some coefficients multiplied by M_{cr} . These coefficients are a function of component type’s affect on modulus of rupture, the effective prestress, and the ratio of yield to ultimate stress in the prestressing steel.
cc: Mohammad Sheikhizadeh, Bridge Construction  47354
