Answer:
Yes, it is.
Open Window "1.2 Materials" and the material library for reinforcing steel. See Image 01.
In this material library, you can create a new "user-defined" material and edit the standard preset for the yield strength, for example. See Image 02.
Afterwards, you can select this user-defined material for design in Window 1.2 in RF‑CONCRETE Members and RF‑CONCRETE Columns.
It is the same for the RSTAB add-on modules CONCRETE and CONCRETE Columns.
In the settings for National Annex, there are the limits defined for the maximum value of the yield strength. See Image 03. To change this limit, you need to create a new user-defined national annex. See Image 04.
