Dear all
How can I extract the frequencies and mode-shapes of a 3D bridge from the acceleration record of multiple accelero-meters installed on the bridge?
Thank you.
Well depending on where you've placed your accelerometers you can find certain natural frequencies and mode shapes. Are the acceleration records synchronized? Because if not, your records may not be useful. There are different ways you can do this. Was the bridge excited with a prescribed force or through ambient vibration? You could most likely try the ERA approach. This video talks about ERA:
https://www.youtube.com/watch?v=5TM_JrW5qDo&t=15s
Hi
You typically use Operational Modal Analysis to do this.
Here is a link to a low cost commercial software that does the job. I believe the. Company has also a Japanese sales representative.
http://absignal.com/literature/Bridge.php
This software can control NI hardware to make also measurements. If you use other hardware, it can import time data using the Universal File Format 58, or its ascii interface.
sincerely
Claes
Dear Amirali Najafi (Ph.D.), Claes Richard Fredö (Ph.D.), and Ahad Javanmardi (Ph.D.) Thank you very much. I greatly appreciate it.
Amirali Najafi (Ph.D.), regarding the ERA approach, is there a possibility of using this method in identifying the dynamic properties in real-time operation where there is a continuous excitation force like load from a vehicle crossing the bridge. Or is it restricted to acceleration data recorded after the impulse excitation?
Abdurehman Bali , you may use ERA for vehicular loads as well. There is a method called NExT-ERA - which is pretty much identical to ERA.
Dear Amirali Najafi (Ph.D.), Thank you for your recommendation. I really appreciate it.
Hi Abdurehman Bali
There's an open-source platform that links with MATLAB, named EasyMod. Here follows the link:
https://hosting.umons.ac.be/html/mecara/EasyMod/index.html
It's very useful and accurate. I used it in a recent publication, you can read it at my Researchgate profile.
Cheers,
Victor
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