In my building vibration response analysis, I need to apply damping ratio of concrete = 2% which equals to 0.02 in material damping section.
However, im lack of understanding regarding on which type of damping option need to be defined (alpha, beta , composite and structural) .
Is it true to i need to apply Damping ratio=0.02 as Structural damping ?
Thank you.
Hi
And watch out for the classic confusion on the damping types structural damping loss factor, ETA, and % of critical damping, KSI, where ETA = 2*KSI.
Rayleigh damping will give you a damping value that varies with frequency. This model is mathematically convenient but, is poor in the sense that it does not rely on any physical mechanism, i.e. it is a purely mathematical construct.
/Claes
Dear Raimy Haidar
You can identify which option you should use, this can be done by calculating the natural frequency of the system, Thus, α for mass proportional damping so mass proportional damping dominates when the frequency is low, and β for stiffness proportional damping so stiffness proportional damping dominates when the frequency is high.
Nazim NARIMAN
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