Scale Factor

03-Unexpected behaviour/errors
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huffte
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Joined: 22 Jul 2011, 10:19
Location: Cookeville, Tennessee, USA
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Scale Factor

Post by huffte »

The program appears to ignore the specified scale factor in Step 3. Regardless of the specified scale factor, the matching appears to be performed to the specified target spectrum, not the specified target multiplied by the scale factor.

The scale factors specified in the Settings appears to be ignored as well, regardless of which algorithm is selected.

Great program!!!
Tim Huff
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seismosoft
Posts: 1047
Joined: 06 Jul 2007, 04:55

Re: Scale Factor

Post by seismosoft »

Indeed Tim, you are right.
We will fix this in the new release.
Many thanks for the continuous support.
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ppaudel
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Joined: 27 Aug 2021, 19:26

Re: Scale Factor

Post by ppaudel »

Also, do the the seed eqs we obtain from the website the software directs need to be scaled before using them for spectral matching? or is it already scaled and ready to use. If not, how do we scale them? Appreciate your answer.
huffte
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Joined: 22 Jul 2011, 10:19
Location: Cookeville, Tennessee, USA
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Re: Scale Factor

Post by huffte »

Most web sites for ground motion data provide unscaled accelerograms (certainly, PEER is explicit in stating that downloaded records are unscaled). There are several methods in the literature used for ground motion scaling. The online PEER database provides a means of computing appropriate scale factors given a period range of interest, as does one of the companion programs to SeismoMatch, SeismoSelect.
Tim Huff
Kirkaguel
Posts: 51
Joined: 31 Dec 2018, 10:04

Re: Scale Factor

Post by Kirkaguel »

The scale factor is still not working even with the latest version?

The concept of spectral matching is that the program will automatically do the scaling at the period range of interest modifiying the frequency content to closely fit the target design spectrum. This process wll use variable scale factors as multiplier to the acceleration ordinates at the period range of interest. The scale factor in STEP 3 has a special function which I believe is supposed to accomodate specific requirements in the code i.e. ASCE 7 requires that the mean of the SRSS spectra of the selected ground motions should not be less than 110% than the target spectrum at the period range of interest. So, this is supposed to be the function of step 3 scale factor but still not working.
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seismosoft
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Joined: 06 Jul 2007, 04:55

Re: Scale Factor

Post by seismosoft »

The scaling factor in Step 3 is simply a direct scaling factor of the spectrum introduced in Step 2. We confirm that the scaling factors works correctly in v2022.
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Kirkaguel
Posts: 51
Joined: 31 Dec 2018, 10:04

Re: Scale Factor

Post by Kirkaguel »

seismosoft wrote: 05 May 2022, 20:19 The scaling factor in Step 3 is simply a direct scaling factor of the spectrum introduced in Step 2. We confirm that the scaling factors works correctly in v2022.
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Thanks for the clarification technical support, now I get it. I was expecting that the response spectra of the selected ground motions are the one that will be scaled up and will plot like they are floating above the target design spectrum. I was only looking at the scaled response spectra plot and they are all closely fit with the target design spectrum.

Again thank you this is now clarified.
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