Reproducing Earthquake Records Using Shaking Tables with Limited Displacements

摘要

Shaking tables are effective and powerful for testing of structures, models or structural details subjected to earthquakes or other dynamic loadings. The control system of the table is generally developed using real seismic records. The algorithm used to calculate the control signal should consider the restrains in the platform displacements. In order to overcome this limitation the ground acceleration record is usually changed, and it subsequently yields undesired affect on the tested specimens. This paper deals with an originally developed method allowing minimizing the undesired effects. The proposed method is based on signals perturbation theory used for control algorithms of complicated dynamic systems. It includes piecewise linear continuous approximation of integrated earthquake ground acceleration. The effectiveness of the proposed method is demonstrated by comparing the total earthquake energy and response spectrums of real and simulated earthquakes. Additionally responses of a multistory structural model to real and simulated seismic records were compared. It is shown that it is possible to obtain good simulation of real earthquakes using shaking tables with limited platform displacements.