構造振動系の非定常スペクトル応答解析法について

抄録

Hammond has analyzed the non-stationary response of both single and multimode systems subjected to non-stationary excitations by using Priestley's evolutionary spectral density. Unfortunately, his method has a fatal drawback, because a modulating function representing non-stationary state of excitation is restricted to real positive values. Furthermore, certain asymptotic forms of the response are intuitively assumed. After two years, Shinozuka showed that the input-output relationship derived by Hammond is also valid without such restriction even under the assumption of asymptotic form. However, this relationship could not have been concretely applied to the response analysis of dynamic systems because of a difficulty in estimating a modulating function included in it. In this paper, an effective method to evaluate a modulating function is developed by using complex demodulation analysis. Then, the present method is applied, as an example, to the response problem of a single-degree-of-freedom system subjected to earthquake ground motion to demonstrate its rationality and efficiency. The method can be also applied to actual multimode dynamic systems.