It appears you have done a lot of research already.
As you know, Ansys does not have the "Mander's" Material model. The closest option might be the Capped Extended Drucker Prager. Please refer to the Section 4.4.5.1 of the MAPDL Material Reference Guide for more details.
Also, you might want to consider mesh independent reinforcement. See Section 14.1.3.1 of Structural Analysis Guide for more details.
You are navigating away from the AIS Discovery experience