I have the acceleration time history and from seismosignal I am getting velocity ,displacement time histories by integration of acceleration time history and the ground motion parameters and structural response at different damping based on that . But based on one of my reference paper , I need to get Peak ground velocity and displacement values based on the velocity and displacement time histories after conventional processing but this conventional processing should not affect acceleration time history and also need to get the structural response based on acceleration ,processed velocity and processed displacement time histories but now Iam getting response based on only acceleration time history.
Is there any provision for applying correction to velocity and displacement time histories only without affecting acceleration time history and to get stuctural response based on that.
Response spectum and ground motion parameters
Re: Response spectum and ground motion parameters
Hi anbazhagan. I wonder if you could clarify your question a bit and perhaps cite the paper you reference?
Generally speaking, I believe you are generating response spectra (elastic) at various damping values in SeismoSignal. And you are also interested in ground motion parameters such as PGD and PGV.
I assume by 'processing', you mean baseline correction and/or filtering.
It is correct to say that the PGV and PGD should usually be taken from processed records. Raw records can often have residual drift at the end of the record for both velocity and displacement indicating incorrect values for these parameters.
It is easy enough to examine the effect of the processing on the generated response spectra. Run the spectra on an unprocessed accelerogram and run it a second time on the processed version of the same accelerogram. Plot the two together and you will generally find that processing has little effect on the acceleration response spectrum over the range of periods of structural interest (up to 10-20 seconds or more), though I cannot say this will be the case every time. And, for inelastic spectra, the effects of processing upon spectra may be more pronounced. These comments are based on material I have read in:
'On Baseline Corrections and Uncertainty in Response Spectra for Baseline Variations Commonly Encountered in Digital Accelerograph Records', Akkar and Boore, Bulletin of the Seismological Society of America, Vol. 99, No. 3, pp. 1671–1690, June 2009.
So, in summary, yes - take ground motion parameters from the processed records only.
For additional insights, see:
'Final Report Effects of Strong-Motion Processing Procedures on Time Histories, Elastic, and Inelastic Spectra', COSMOS Report CP-2005/02, Savage, Stepp, and Johnson.
Best of luck, anbazhagan.
Generally speaking, I believe you are generating response spectra (elastic) at various damping values in SeismoSignal. And you are also interested in ground motion parameters such as PGD and PGV.
I assume by 'processing', you mean baseline correction and/or filtering.
It is correct to say that the PGV and PGD should usually be taken from processed records. Raw records can often have residual drift at the end of the record for both velocity and displacement indicating incorrect values for these parameters.
It is easy enough to examine the effect of the processing on the generated response spectra. Run the spectra on an unprocessed accelerogram and run it a second time on the processed version of the same accelerogram. Plot the two together and you will generally find that processing has little effect on the acceleration response spectrum over the range of periods of structural interest (up to 10-20 seconds or more), though I cannot say this will be the case every time. And, for inelastic spectra, the effects of processing upon spectra may be more pronounced. These comments are based on material I have read in:
'On Baseline Corrections and Uncertainty in Response Spectra for Baseline Variations Commonly Encountered in Digital Accelerograph Records', Akkar and Boore, Bulletin of the Seismological Society of America, Vol. 99, No. 3, pp. 1671–1690, June 2009.
So, in summary, yes - take ground motion parameters from the processed records only.
For additional insights, see:
'Final Report Effects of Strong-Motion Processing Procedures on Time Histories, Elastic, and Inelastic Spectra', COSMOS Report CP-2005/02, Savage, Stepp, and Johnson.
Best of luck, anbazhagan.
Tim Huff
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anbazhagan
- Posts: 6
- Joined: 12 Apr 2014, 14:35
Re: Response spectum and ground motion parameters
Hi,
Thank you for the answer.
This question was with reference to the papers:
1.) Response spectrum of incompatible acceleration, velocity and
displacement histories , Praveen K. Malhotra ,EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS ,Earthquake Engng Struct. Dyn. 2001; 30:279{286
2.)Smooth Spectra of Horizontal and Vertical Ground Motions
by Praveen K. Malhotra,Bulletin of the Seismological Society of America, Vol. 96, No. 2, pp. 506–518, April 2006, doi: 10.1785/0120050
The question was related to any provision in seismosignal to get the ground motion parameters and response spectrum according to the second reference paper. I have only the acceleration time history of for my data set but not the velocity and displacement time histories.
So wanted to know about baseline correction and filtering option in detail or any other option in seismosignal so as to get similar ground motion parameters and response spectrum with the data that Iam having .
So I wanted to know about any option to modify the velocity and displacement time history according to the above mentioned paper to get the processed PGV and PGD values and the response spectra. In other words, can baseline correction and filtering be applied only to the velocity and displacement time histories obtained by integrating acceleration time history without affecting the acceleration time history and PGA value ?
Thanks and regards
Thank you for the answer.
This question was with reference to the papers:
1.) Response spectrum of incompatible acceleration, velocity and
displacement histories , Praveen K. Malhotra ,EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS ,Earthquake Engng Struct. Dyn. 2001; 30:279{286
2.)Smooth Spectra of Horizontal and Vertical Ground Motions
by Praveen K. Malhotra,Bulletin of the Seismological Society of America, Vol. 96, No. 2, pp. 506–518, April 2006, doi: 10.1785/0120050
The question was related to any provision in seismosignal to get the ground motion parameters and response spectrum according to the second reference paper. I have only the acceleration time history of for my data set but not the velocity and displacement time histories.
So wanted to know about baseline correction and filtering option in detail or any other option in seismosignal so as to get similar ground motion parameters and response spectrum with the data that Iam having .
So I wanted to know about any option to modify the velocity and displacement time history according to the above mentioned paper to get the processed PGV and PGD values and the response spectra. In other words, can baseline correction and filtering be applied only to the velocity and displacement time histories obtained by integrating acceleration time history without affecting the acceleration time history and PGA value ?
Thanks and regards
Re: Response spectum and ground motion parameters
Hi anbazhagan,
No, SeismoSignal does not feature the possibility of applying baseline/correction or filtering to velocity/displacement time-histories.
If you really want to post-process such time-histories, the only workaround I can think of is to load the velocity time-history into the program as if it was an accelerogram, and baseline/filter it.
Of course, by doing the above, the changes introduced in the velocity/displacement time-histories will not be reflected back into their acceleration counterpart, I appreciate that, but this will be as far as you will be able to go with the current version of SeismoSignal.
Best,
Rui
No, SeismoSignal does not feature the possibility of applying baseline/correction or filtering to velocity/displacement time-histories.
If you really want to post-process such time-histories, the only workaround I can think of is to load the velocity time-history into the program as if it was an accelerogram, and baseline/filter it.
Of course, by doing the above, the changes introduced in the velocity/displacement time-histories will not be reflected back into their acceleration counterpart, I appreciate that, but this will be as far as you will be able to go with the current version of SeismoSignal.
Best,
Rui
-
anbazhagan
- Posts: 6
- Joined: 12 Apr 2014, 14:35
Re: Response spectum and ground motion parameters
Thank you , I will try with the same.
Re: Response spectum and ground motion parameters
Hi
Can you tell me what does the "Response time-histories" under the "elastic/inelastic response spectra" tab mean? How is it calculated? How is it different from my input time-series?
My understanding is that it is the scaled time history obtained from normalised reponse spectrum? By normalised response spectrum, I mean the response spectrum of my original input time series is normalised by a scaling factor of 1/Sa(T) where T is the period of SDOF that can be given as an input in the "Response time-histories" tab. Please let me know if I am correct.
Can you tell me what does the "Response time-histories" under the "elastic/inelastic response spectra" tab mean? How is it calculated? How is it different from my input time-series?
My understanding is that it is the scaled time history obtained from normalised reponse spectrum? By normalised response spectrum, I mean the response spectrum of my original input time series is normalised by a scaling factor of 1/Sa(T) where T is the period of SDOF that can be given as an input in the "Response time-histories" tab. Please let me know if I am correct.
Re: Response spectum and ground motion parameters
"Response Time-Histories" performs a response history analysis for a single-degree-of-freedom oscillator subjected to the input ground motion. You may run linear or nonlinear (by specifying a desired displacement ductility) response history. So this gives the entire history of response at each time step, whereas the response spectrum only keeps the maximum value from the entire response history. This can tell you when the maximum occurred, how much residual displacement exists at the end of the analysis (for nonlinear analysis), and other valuable information not retained by the response spectrum results.
The analysis is performed via numerical integration of the equation of motion. Parameters used for this analysis may be changed in the "More Settings" button on the "Response Time-Histories" tab. Generally, the default values provide accurate results. The main parameter you may wish to change is probably the post-yield hardening ratio, which defaults to 0.00 (corresponding to elastic-perfectly-plastic hysteresis).
The analysis is performed via numerical integration of the equation of motion. Parameters used for this analysis may be changed in the "More Settings" button on the "Response Time-Histories" tab. Generally, the default values provide accurate results. The main parameter you may wish to change is probably the post-yield hardening ratio, which defaults to 0.00 (corresponding to elastic-perfectly-plastic hysteresis).
Tim Huff