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Converting 5% damped response spectrum to 2% & 0.5% damping

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numericaleng

Structural
Dec 5, 2021
8
I am designing a water storage tank and I need to convert my elastic response spectrum's damping ratio 5% to 2% & 0.5%. Could you please help me how can i convert it?
If I have a time history data, I can derive it to other thinks (PSA, PSV, PSD, SA, Displacement charts etc.) . But I did not think before how can be converted the damping ratio in a elastic response spectrum.
Damping_ratio_spec_xymskp.png
 
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Are you saying to have available time history data or not? Off the top of my head I don't know any other means other than time history derivation of response spectra. I'm sure there is something in Chopra about this.
 

-AWWA and API use damping scaling factor K = 1.5 to convert spectrum from 5 percent damping to 0.5 percent damping..

-Another code suggests the use damping scaling factor K = 1.3 to convert spectrum from 5 percent damping to 2.0 percent damping

Suggest you to look to the following doc.







Tim was so learned that he could name a
horse in nine languages: so ignorant that he bought a cow to ride on.
(BENJAMIN FRANKLIN )

 
 https://files.engineering.com/getfile.aspx?folder=06dd40d9-7e99-4b79-8d2f-a8ef2dcc81dd&file=damping-ngaw2-nov-15-2012.pdf
Thank you for you comments. I found something from Chopra. I m just not sure which one is more relaible or suitable; Media or One Sigma
chopra_damping_scale_gqtgu8.png
 
I have the Newmark document and, in it, he clearly intends for the 84.1 / one sigma version to be the elastic design spectrum. That's going back to 1982 however. I'm not sure if things may have changed since then.

c01_zktney.png
 
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