Phase Spectrum Modeling to Simulate Design Earthquake Motion

概要

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Modeling the phase of earthquake ground motion is required in order to synthesize design ground motion that is compatible with the given response spectrum. A simple method is presented for modeling the phase characterstics of earthquake motion using the concept of group delay time and wavelet analysis. Using existing data sets of observed earthquake motions, we calculated the group delay time of each earthquake motion on each compact support of the mother wavelet. Because of the fluctuating nature of the group delay time on each support, the mean of the group delay times and standard deviation were calculated. Attenuation relations of the mean delay time and standard deviation on each support were obtained by regression analysis as functions of the earthquake's magnitude and epicentral distance. On the assumption that the group delay time has a normal distribution, a sample group delay time can be generated on each support, and by integrating it with respect to frequency the phase spectrum is derived. Simulated sample phase spectra were used to simulate earthquake motions compatible with a design response spectrum. Their characteristics were investigated using ductility demand spectra.
日本自然災害学会の論文