## response spectra

### response spectra

Dear Seismosoft, based on mean response spectra if its possible to compute spectra with account standart deviation by use SeismoSpect or another tool(s)? Thank you very much.

### Re: response spectra

Hi parz. I wonder if you could clarify your question a bit please? I'll try to answer based my interpretation of your question.

If you are looking for the standard deviation fro a given set of ground motions, then certainly SeismoSpect handles this. Simply select the "Show Mean Spectrum = StDev" box on the Elastic/Inelastic Spectra worksheet. Graphically or in tabular form, you can see how the Standard Deviation varies with period for the selected set of records.

Note that it is common practice in the field to assume that spectral aceleration is logarithmically distributedand to thus compute mean and standard deviation parameters of the natural log of spectral acceleration rather than spectral acceleration itself. And if you are looking for a means to estimate standard deviation for a given mean spectrum irrespective of a particular set of ground motions, then modern ground motion predictin models (GMPM's) are good at providing estimates of both mean and standard deviation as long as the variables reasonably match your tectonic environment. I would suggest a look at the following link where spreadhseets for several GMPM's are available.

http://peer.berkeley.edu/ngawest/nga_models.html

This is a place to start anyway. A google search on "ground motion prediction" would likely open up other doors if needed.

Best of luck parz.

If you are looking for the standard deviation fro a given set of ground motions, then certainly SeismoSpect handles this. Simply select the "Show Mean Spectrum = StDev" box on the Elastic/Inelastic Spectra worksheet. Graphically or in tabular form, you can see how the Standard Deviation varies with period for the selected set of records.

Note that it is common practice in the field to assume that spectral aceleration is logarithmically distributedand to thus compute mean and standard deviation parameters of the natural log of spectral acceleration rather than spectral acceleration itself. And if you are looking for a means to estimate standard deviation for a given mean spectrum irrespective of a particular set of ground motions, then modern ground motion predictin models (GMPM's) are good at providing estimates of both mean and standard deviation as long as the variables reasonably match your tectonic environment. I would suggest a look at the following link where spreadhseets for several GMPM's are available.

http://peer.berkeley.edu/ngawest/nga_models.html

This is a place to start anyway. A google search on "ground motion prediction" would likely open up other doors if needed.

Best of luck parz.

Tim Huff

### Re: response spectra

Thanks huffte for the link!

actually there is no any acceleration TH and only standart RS available as a starting point, probably it should generated NGA model, let see. My best regards, huffte.

actually there is no any acceleration TH and only standart RS available as a starting point, probably it should generated NGA model, let see. My best regards, huffte.

### Re: response spectra

Dear Seismosoft,

Please, how it can available a tabular data of the spectrum with Standard Deviation? It is visible in graph only, when "Values" is on the only Mean spectrum data are presented without Standard Deviation.

Thanks!

Please, how it can available a tabular data of the spectrum with Standard Deviation? It is visible in graph only, when "Values" is on the only Mean spectrum data are presented without Standard Deviation.

Thanks!

- seismosoft
**Posts:**961**Joined:**06 Jul 2007, 04:55

### Re: response spectra

Dear parz,

You are correct, currently only the mean spectrum is provided in tabular format. We will consider adding also the data of 'Mean+StDev' and 'Mean+2StDev' in a future version of the software.

Thank you for the suggestion.

Seismosoft Support

You are correct, currently only the mean spectrum is provided in tabular format. We will consider adding also the data of 'Mean+StDev' and 'Mean+2StDev' in a future version of the software.

Thank you for the suggestion.

Seismosoft Support