Hi,
I wish to apply the recorded time-history as a loading to the structure in a commercial software as a part of the exercises in a structural engineering class. We currently have in possession and installed two seismographs RS4D Turnkey (AM.R0B07 and AM.R8280). Is there a possibility to take the vibration recordings and save them to *.txt or *.xlsx file type that is suitable for the structural engineering software? Is there a possibility to extract such data from other RS stations closer to earthquake events?
Thank you!
Regards,
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I think you need to be a bit more explicit in what you are looking for. What exactly would you want these files to contain?
The RS device (by default) keeps a week of data, and you can copy those files out. They are in miniSEED format, which is somewhat complex (maybe overly complex for the world today), but there are tools that will extract the data (I have been using mseed2ascii). The raw data is “counts”, a unitless value from the analog to digital converter reading the ground measurement transducer.
The recorded numbers (one sample every 1/100th of a second) look like this:
TIMESERIES AM_R309F_00_EHZ_D, 6490377 samples, 100 sps, 2022-04-19T00:00:04.192999, TSPAIR, INTEGER, Counts
2022-04-19T00:00:04.192999 16548
2022-04-19T00:00:04.202999 16518
2022-04-19T00:00:04.212999 16483
2022-04-19T00:00:04.222999 16442
2022-04-19T00:00:04.232999 16476
2022-04-19T00:00:04.242999 16507
2022-04-19T00:00:04.252999 16474
2022-04-19T00:00:04.262999 16452
2022-04-19T00:00:04.272999 16519
2022-04-19T00:00:04.282999 16508
2022-04-19T00:00:04.292999 16494
2022-04-19T00:00:04.302999 16572
2022-04-19T00:00:04.312999 16543
2022-04-19T00:00:04.322999 16517
2022-04-19T00:00:04.332999 16563
You can also output the data without the date/time stamp on each line for a smaller file, and keep track of the time relative to the timestamp in the header yourself.
It should be fairly clear that you probably need to re-center the values around zero (calculate an average and subtract it from each value).
If you want to convert the counts to m/s you can do so, with some programming by obtaining the calibration data for your device and using that in the conversion.
For other devices data, I did a quick search but didn’t find any advertised way to do it from the RaspberryShake servers, but the manual does mention this:
https://manual.raspberryshake.org/fdsn.html#fdsnwebservices
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An RS4D does not give you the data in V1 format (COSMOS, IRIS, etc) but with Obpsy you can obtain the data in Txt and then with some commercial program obtain the file V1.
In this forum it is published how to obtain a Txt (in g) with Obpsy
Regarding measuring vibrations with an RS4D, it depends on the flexibility of the structure and the excitation that generates it. If you intend to measure ambient vibrations (for SHM), field tests show that the accelerometer cannot but you can use the geophone (EHZ) data to get at least some periods.
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Hi,
thank you for your reply.
There is a description of using an earthquake record as an action to the structure in a commercial software SAP2000 on this link: Time history sap2000 - YouTube
Is it possible to use MATLAB to prepare the eq record for the structural analysis as in the case described by the video in the link?
Thank you and regards,
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Hello dpenava,
Given the extensive capabilities of MATLAB, it should be possible to create a code that does what you need. Unfortunately, we don’t have such code readily available, so if anyone of our users can help you, please feel free to come forward!
In case you decide for a substitute software, then as also Philip has shown, you can possibly create a code in Python for Obspy to do the job for you.
Hi
Here you will find a routine for matlab that converts RS4D miniSEED into Txt with Matlab or Octave.
It is not easy to use but it works. Its output is in counts that matlab can convert to g with the factors indicated in the RS4D user guide.
Then with must you can generate the SAP2000 input format for time history.
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