I intend to conduct a modal testing on a clamped-clamped steel beam in ABAQUS.
-The input is random signal with normal distribution, zero mean, and maximum amplitude of 5 (N).
-Duration of loading is 30 seconds.
-The length of the beam is 2 meters which is monitored by 5 sensors attached on top surface of the I-shape beam.
-Sampling rate is 100 so the cut-off frequency is 50 (Hz).
-The beam's natural frequencies are in range of 4 to 35 (Hz).
Have I set the right parameter to perform modal analysis?
I am recording the acceleration data of the sensors for a structural system identification method, unfortunately the identified frequencies from the Stochastic System Identification (SSI) method are not satisfying and do not match with real frequencies, I believe the above parameters should change to achieve my desired results.
I would be appreciated if anyone help me out with the right numbers for duration of the analysis, sampling rate, number of sensors, and the type of excitation applied to the beam.
Thank you.
Article Modal strain identification using sub-microstrain FBG data f...
It seems that there is a bug in SAP2000. I would recommend to use Opensees to do these calculations.
Dear Fabian Dwenger
Actually I am working on system identification methods so I need acceleration data of a structure I already know what the frequencies are (obtained from frequency analysis of ABAQUS) so I can verify my methods. Now my question is how to run the test with proper settings?
Modal testing: The location of the excitation is important to excite the structure, Generally the exciter should be placed at the anti nodal position.
For clamped- clamped condition first mode extraction, you need to put your exciter at the middle, second mode you need shift right are left where antinode is exist.
Generally, you can keep the exciter not at the middle which will excite 2 modes.
1. See the force transducer input, whether it is sensing same as your controller input.
2. See the accelerometer response.
Dear Mohammad Maldar: I recommend you to check the two following papers. Regards.
Article Seismic Behavior of Glass Fiber-Reinforced Polymer Wall Panels
The application of ABAQUS in seismic analysis of
connected structures http://www.simulia.com/download/scc-papers/Architecture/application-abaqus-seismic-analysis-connect-struc-2010-F.pdf
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