a question in modeling isolated bridge

[bsimoel]

hi all,
I am modeling an RC bridge which is isolated using HDR (high damping ratio)
I have modeled isolators with bilinear zerolength elements, which hysteresis loops cause an effective damping ratio of 10% (as mentioned in the product catalogue)
my main questions are as below:
1- should I include -dorayleigh 1 in definition of zerolength elements?
2- is it reasonable to call rayleigh command to assign constant damping ratio to all of the elements of the bridge?
3- what damping ratio is common to use for isolated RC bridge? (2%? 5%?)
4- how about assumptions of alpha and beta (rayleigh coefficients)

I have searched many literature and provisions till now, but there is no CLEAR assumption for nonlinear timehistory analysis of isolated bridges, I really appreciate your attention and help.

[bsimoel]

no help?

[satis]

I am not sure about the bridges but in case of isolated buildings people have been using stiffness proportional damping and has been quoted in many literature. For the best ideas you can have a look at "Appropriate viscous damping for nonlinear time‐history analysis of base‐isolated reinforced concrete buildings"