Hysteretic and Multilinear Material

[melis]

Dear Vesna;
I modeled a cantilever column from PEER column database. My results showed good agreement with experimantal data. However, i want to change my steel with new material. this material is called hybrid material and we purpose to use this material in my thesis. This material has four critical points in its force-rotation graph. First part is defined as Ki:initial stiffness , second part is defined as Kp: post yielding stiffness. these two parts are ascending parts but third part is descendig. this unloading part is "coupled takeda and flag shaped hysteretic models", so it is defined by using a diffrent variable like beta, Mu,gamma, but may be, i can model this part with multilinear or hysteretic material. first, i tried hysteretic material, but this material information is limited. i have some important question about this two materials
1) hysteretic and multilinear materials definition says; you can define stress or force - strain or deformation. i don't want to use stress-strain relation, but i didn't decide force-deformation couple.
For example; Can i use force-rotation relation or moment-curvature? how can i decide my material input values unit? Once i modeled a 2d frame, and i used hyrsteretic material. i used moment-curvature values, and results were well, but if i used moment-rotation values, how would opensees be aware of differences between curvature and rotation?
In my main model,first, i tried hysteretic material, and i used force-displacement values, but result were very different from the experimental data (for example; experimental fy:35e6 N model fy: 50e8N), then i confused about input values unit and definition.
2)i used both hysteretic and multilinear material but two of them were shown same result.why?
3)what is the multilinear material conditions? For example; i used these values;
uniaxialMaterial MultiLinear $matTag $u1 $f1 $u2 $f2 $u3 $f3 $u4 $f4
u1:0.008 radian
f1:300kN
u2:0.015 radian
f2:335kN
u3:0.025 radian
f3:345kN
u4:0.02
f4:150kN
then i run opensees.exe and it unexpectedly closed suddenly.
I think, i will model my hybrid material with multilinear material, so i need more information about this material.

Thank you so much..