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

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

(OP)
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.

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

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.

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

-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 )

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

(OP)
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

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

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.

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