kamruzzaman Shohug

In ACI 21.5.2, it is mentioned that grade 40 & 60 shall be permitted for SMRF whereas fc' shall not be less than 3000 psi. To my understanding, they are trying to ensure proper yielding characteristics or ductile behavior or to avoid brittle failure. Upon what condition i can use higher steel grade (HRB 500/75 grade) in SMRF zone? Is there any issues such as ensuring higher concrete strength will allow me to used higher steel grade? Any code reference will be highly appreciated. Thanks