Material damping ratio

[MTII]

Hi,

I've managed to create a new material in Material Definition window but I would like to know what's the purpose of the Damping ratio defined for the material. The help file says:

Damping ratio - specifies the damping ratio for the user-defined material. This ratio is used for the dynamic analysis of structures.

At least for Modal and Time History Analysis types I don't see any difference in results whether the material damping ratio is 0,05 or 0,5. 

So for what analysis types the material damping ratio is used and how does it affect the results?

I know that it's possible to define damping value for Time History Analysis in Parameters window. However, I would like to have different damping values for different parts of my structure and I was hoping that the Material damping would make it possible to do that.

Thanks in advance!

[Pawel.Pulak · Accepted solution]

This material specific damping ratio can be used in some seismic codes (French ones and French NA of EC8) to average spectra considering different materials composing different parts of the structure. Such averaging for these seismic codes is activated using this setting in advanced parameters of modal analysis:

This parameter is not used in modal analysis and in time history.

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[nsb2312]

where can I find these modal analysis parameters?

[Pawel.Pulak]

After defining modal analysis load case in Analysis Type window and opening parameters for it:

Regards,