Modal parameter identification of model structure in shaking table test

The objective of the paper is to present a method for modal parameter identification of model structure in shaking table test by using the seismic response records. The method includes two key steps. Firstly, the adaptive on-line system identification method is adopted to investigate whether the time-varying response occurs during the process of vibration, and the acceleration response record is divided into segments if the response is time-varying. Secondly, only the response time-history in time-invariant stage and segment is adopted to identify modal parameters by using off-line system identification method. To show the availability and accuracy, the method is applied to the shaking table test data of a 12-story RC-frame model structure (scale 1:10) to identify its modal frequencies, damping ratios and mode shapes, and the results are compared with the traditional modal analysis results under the excitation of low amplitude white noise. It is shown that the dynamic properties after every strong motion input can be determined from the seismic response data in shaking table test by the method. The parameters identified from the seismic response data can be as the useful supplement of the traditional modal analysis.