PSD Functions

02-Analytical capabilities
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SarahClegg
Posts: 3
Joined: 13 Aug 2013, 13:12

PSD Functions

Post by SarahClegg »

Hi all,

I was wondering if it is possible to output the Power Spectral Density Functions (PSDF) of: (i)the artificial time histories generated in SeismoArtif, and (2) the target PSDF compatible with the target response spectum?

From what I can gather, the 'Artificial Accelerogram Generation' calculation method uses the PSDF to genertae the time histories, so I'm hopeful that a user might be able to access these?

The basis of this question is a requirement in ASCE4-98, which requires the PSDFs of generated time histories to be compared with that of the target spectrum, to ensure there is sufficient power at all frequencies of interest.

Hope you can help!
Many thanks,
Sarah
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seismosoft
Posts: 1056
Joined: 06 Jul 2007, 04:55

Re: PSD Functions

Post by seismosoft »

Sarah, hi.

Would it be possible to use SeismoSignal's Power Spectrum computation facility, in order to meet the requirements you outlined?

Seismosoft Support

SarahClegg
Posts: 3
Joined: 13 Aug 2013, 13:12

Re: PSD Functions

Post by SarahClegg »

Hello again, and thanks for your reply.

In response, can I explain a little better my request. Seismosignal requires an acceleration time history as input, and thus will output a PSD specific to that single time history.

However, I need a 'design' PSD generated for the design response spectrum that is used as an input to Seismoartif. This could then be used for comparison with the time history specific PSDs created in Seismosignal in ASCE4-98, to ensure there is sufficient power at all frequencies of interest.

Thank you

huffte
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Joined: 22 Jul 2011, 10:19
Location: Cookeville, Tennessee, USA
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Re: PSD Functions

Post by huffte »

I think I see your dilemma SarahClegg. You can get the PSDF of the accelerogram easy enough using SeismoSignal, as recommended by SeismoSoft in their response. The problem is that you cannot access the PSDF which SeismoArtif internally computes from the target response spectrum, and this is the data you wish to have access to for comparative purposes.

It would seem that the information is, in fact, invisible to the user. Perhaps a Command Button to display the PSDF of the target spectrum would be simple enough to incorporate in some future release of SeismoArtif?

In the meantime, if in a pinch, the following article presents one method of converting a response spectrum to a PSDF:

http://www.iitk.ac.in/nicee/wcee/articl ... 2-0024.PDF

The below excerpt form the SeismoArtif Help System inclines me to believe that the information is already computed internally and just needs to be made available to the user:

"This method defines each artificial ground motion modifying the starting random process through the use of a selected envelope shape and a Power Spectral Density Function (PSDF). The PSDF is calculated from the velocity target spectrum (Sv) which is selected before the execution."

Tim Huff
SarahClegg
Posts: 3
Joined: 13 Aug 2013, 13:12

Re: PSD Functions

Post by SarahClegg »

Huffte, hi. Thank you, yes this is exactly my dilemma. Thank you for the links. It would be great if SeismoArtif could make the information available to the user as you have mentioned.

Sarah
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seismosoft
Posts: 1056
Joined: 06 Jul 2007, 04:55

Re: PSD Functions

Post by seismosoft »

Hi Sarah,

We will consider your request in a future release of SeismoArtif.

Seismosoft Support
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