統計的グリーン関数法による平均的応答スペクトルの直接評価

抄録

Considerable differences are sometimes observed among the response spectra of ground motions synthesized by fault model under the same fault parameters. The causes of variation of response spectra are classified into two factors. The one is the random nature of fault rupture process, and the other is problem issued from synthesis method itself. The variation caused by latter factor is undesirable in practical use. This paper presents the method for the direct evaluation of average response spectrum by stochastic Green's function method. In the proposed method, the element earthquake motion is not transformed into time domain using random phase, and the average response spectrum of target large fault is directly evaluated in frequency domain. The average response spectrum can be evaluated without variation because the present method does not include any random factor. The verification tests are carried out using homogeneous fault and the fault consisting of asperity and background region. The average response spectra evaluated by the proposed method agree well with the median of the response spectra of earthquake ground motions synthesized by the ordinal waveform synthesis method.