Inelastic isolator

[civilengineering]

Hi everyone

I want to model base isolated structures as 2-DOF systems with zerolength elements with inelastic isolator. The material model of isolator is bilinear such that the first line (linear region) matches on stress axis until yield point (Q) and the second line (inelastic region) starts from Q point (Q= strength of the isolation system, namely force at zero displacement) and continues with kb stiffness. I used several material models including Hysteretic material, Bouc Wen, MultiLinear models to this purpose, but the seismic responses obtained from time history analyses are not reasonable.
I repeated analysis with Single Friction Pendulum Bearing Element, but I could not reach to desired response.
Is there anybody who can kindly help me on modeling above mentioned isolator behavior?

Thanks so much

[satis]

You can use the ElastomericBearingPlacticity element
http://opensees.berkeley.edu/wiki/index ... y)_Element

Just use the value of alpha2 = 0 and mu=1.