Damping in Dynamic Analysis

[Oleg Dzampaev]

Dear Colleagues,

I am currently performing a Nonlinear dynamic analysis of a four-story reinforced concrete building with a soft story and masonry infill walls.
I have developed several models of the same building using different damping types and parameters, as specified in the SeismoSoft documentation.

Please find below a figure illustrating the first-story displacement results for the different models:

Accordingly, I would like to inquire about the standard methodology for determining the appropriate damping types and parameters.
For instance, the damping settings vary between the "4-Storey Italian Building with roof" model [Damping Type: Stiffness-Proportional Damping (Tangent Stiffness), Period: 0.7209 sec, Damping Ratio: 1%] and the "2-Storey School Building in Greece" model [Damping Type: Stiffness-Proportional Damping (Initial Stiffness), Period: 0.2250 sec, Damping Ratio: 2%]. Both models were obtained from the SeismoSoft sample models repository.

Could you please clarify the criteria used to adopt specific damping parameters for such analyses? Furthermore, how can one determine when it is necessary to include viscous damping in addition to the explicitly modeled hysteretic damping?

Best regards,
Oleg Dzampaev

[seismosoft]

The criteria for the definition of the damping parameters depend on the expected damping of the original structure. There are no specific rules that are globally acknowledged as standard rules for the selection of the parameters. Therefore, we cannot propose specific criteria or rules; maybe this is something that you should discuss with your supervisor, or you should carry out sensitivity studies.
In general, with increasing nonlinear response in the structure the effect of viscous damping becomes gradually less important.
Seismosoft Support