Analytical Modeling, System Identification, and Tracking Performance of Uniaxial Seismic Simulators

This technical note presents a simplified approach to reproducing historical earthquake records using uniaxial seismic simulators. Although complex, real-time feedback control systems may be utilized to control such simulators, it is shown herein that the application of a simple, off-line correction procedure is adequate for producing reasonable reproductions of historical earthquakes. An analytical model which describes the dynamic properties of a uniaxial seismic simulator is formulated in the frequency domain and calibration of the analytical model is performed via experimental system identification testing. It is shown that the model and identified properties are valid over a practical range of frequencies of motion. The analytical model is subsequently utilized in the implementation of an off-line correction procedure to improve the dynamic tracking performance of the seismic simulator. The effectiveness of the procedure is demonstrated by comparing motion of the simulator using both uncorrected and corrected command signals that correspond to historical earthquake records. The results show that the analytical model developed is adequate for describing the dynamic behavior of the seismic simulator and that the application of a simple, off-line correction procedure improves the dynamic tracking performance of the simulator.