Period identification of multi degree of freedom structure-shallow foundation-ground system: Dynamic centrifuge test

This study aims to accurately identify periods of ground and lengthened period of multi-degree-of-freedom structures installed on shallow foundations in dynamic centrifuge model tests using the frequency domain decomposition (FDD) method. A series of dynamic centrifuge model tests were conducted with single- and multi-degree-of-freedom structures installed on shallow foundations and sandy ground. The frequency domain decomposition method was utilized to identify the ground period and the lengthened structure period. The results obtained from the FDD method for the soil–structure system, including periods and mode shapes, are compared with those calculated using conventional methods such as response spectrum (RS), ratio of response spectrum (RRS), fast Fourier transforms (FFT), and ratio of fast Fourier transforms (RFFT). The comparison demonstrates that FDD is effective in terms of both simplicity and accuracy for the modal analysis of complex soil–structure systems based on centrifuge test data.