hysteretic material and degradation

[Horr]

Great day to all,

I have classic moment frames with elastic beam and column element and concentated plasticity at both element ends represented by rotational spring. I want to set the moment-rotation relationship in such a way to be proper for the strength and stiffness degradation (or pinching) of RC frames.

It seems the hysteretic material is the best. Am I right?
Questions:
1. what is the Reference (theoritical or experimental model) for the presented hysteretic model?
2. can it simulate only the strength degradation without stiffness degradation (It seems peak-oriented)?
3. How can I set the parameters as the Reference below:
http://dx.doi.org/10.1080/13632460902859144

Thanks,
Horr