Damping for every mode

[crescenzo]

Hello
I am a civil student and I want to assign for my thesis the experimental damping for every modal shape. How can I do?
Futhermore, can more inputs be given by assigning the damping obtained by the experiment for each input without losing the history of previous displacements and accelerations? How can I do?
Thank you

[selimgunay]

How many modes does your structure have?

[crescenzo]

My specimen presents 9 mode. I would assign for only first 3 modes because experimentation has returned me only three modes. The other modes through the dinamic identification tecnicque are not identified.
Thank you for your availability

[selimgunay]

In Rayleigh damping, you can assign the damping for two modes and check the damping curve to make sure that the error is minimum for the third mode.