Accelerograms from Floor Response Spectra

02-Analytical capabilities
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pdc
Posts: 2
Joined: 25 Sep 2013, 09:54

Accelerograms from Floor Response Spectra

Post by pdc »

Hi everybody,
I am new here and just trying to understand if Artif can be useful to me and my organization. This is not actually a request for feature, it is a question:

I understand that ARTIF is made for generating accelerograms of ground motion, having ground motion spectra as input. I see a lot of parameters related to geology and the like.

What if I want to generate an artificial "floor motion" accelerogramm, having as input a floor response spectrum? I am not sure if (and how) the parameters (and the computations method) could be set, in that case, and first of all, if it makes sense to use the program this way. As you know, a Floor Response Spectra can have one or more peaks like a resonance in the middle frequency region, due to the characteristic of the building and of the floor where it was computed.

Does the whole algorithm make sense? would the results be meaningful? I will anyway now download the program and have a try, but the opinion of the forum and of the seismosoft technical team would be very appreciated.

Thanks a lot in advance.
huffte
Posts: 942
Joined: 22 Jul 2011, 10:19
Location: Cookeville, Tennessee, USA
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Re: Accelerograms from Floor Response Spectra

Post by huffte »

pdc,

I believe that SeismoMatch might be the better choice for generating spectrum-matched accelerograms for elevated floors in a building.

Certainly, SeismoArtif is a great tool. I see it's primary use as generating and adjusting artificial and synthetic accelerograms for a particular tectonic setting when a design spectrum is known and real records are unavailable.

While SeismoArtif does have the capability of adjusting real accelerograms in the frequency domain, I will copy here a quote from the SeismoArtif Help System:

"The artificial accelerogram is defined starting from a real one and adapting its frequency content to match the target spectrum using the Fourier Transformation Method as described in more detail here. This method may lead to reasonable results, however the more the target response spectrum differs from the real accelerogram's spectrum, the less realistic the artificial accelerogram will be. Indeed, users who wish to employ existing real accelerograms in the derivation of spectrum-compatible ground motions, something which is certainly recommended, are strongly suggested to use SeismoMatch instead, a more valid and appropriate tool for this purpose."

So, while the original intent of SeismoMatch is the spectrum-matching of ground accelerograms to a target spectrum, there is nothing inherently particular to a given tectonic setting implied in SeismoMatch.

If you know your floor spectrum, then I would offer that SeismoMatch is the better choice of the two.

Best of luck pdc.
Tim Huff
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seismosoft
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Joined: 06 Jul 2007, 04:55

Re: Accelerograms from Floor Response Spectra

Post by seismosoft »

Dear huffte,

Thanks for the customarily thorough and helpful response.

We would maybe add only that if one uses Methods 2 and 3 in SeismoArtif, which are based on "strictly artificial" accelerogram generation (without consideration of tectonic or geotechnical settings, nor of recorded ground motions), then perhaps this could constitute a valid approach for the use-case described by pdc?

Thanks again,

Seismosoft Support
huffte
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Joined: 22 Jul 2011, 10:19
Location: Cookeville, Tennessee, USA
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Re: Accelerograms from Floor Response Spectra

Post by huffte »

Dear Seismosoft.

Yes, agreed. Methods 2&3 in SeismoArtif could certainly be applied in the case of floor spectrum matching. And I see no reason that such a choice would not be defensible.

So as a note, I should be clear pdc. SeismoArtif will do the trick if you choose the right method.

Instead of saying that SeismoMatch is the "better" choice, I should have perhaps said that it is my personal choice for performing such operations.

And finally, pdc, aren't we fortunate and blessed to have such a fantastic choice to make. I know of no finer software available anywhere free of charge for academic purposes. Frankly, the costly ones are hard-pressed to win over SeismoSoft.
Tim Huff
pdc
Posts: 2
Joined: 25 Sep 2013, 09:54

Re: Accelerograms from Floor Response Spectra

Post by pdc »

A lot of thanks to boht "huffte" and Seismosoft Support, for the insight and the interesting considerations. I was not in office the last two workdays, I read only now. I am going to explore and understand what "SeismoMatch" can do for me :-). I was pointed to SeismoArtif by a colleague in another Department, for that reason I did not look "other" products.

Yes it is good to be able to choose :-)

Best regards froom Switzerland.
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