Abstract
The nonstationary ground motions are assumed to be expressed as the product of an envelope function representing the temporal amplitude modulation and another function representing the frequency content of a stationay random process. In the previous investigation due to the present author, the envelope functions of nonstationary ground motions were fixed and the critical frequency contents were found. In contrast to the previous studies, the critical envelope functions are investigated here with the frequency contents fixed to the critical one found in the previous study. It is shown that the order interchange of the double maximization procedure with respect to time and to the envelope function can be a powerful solution algorithm for finding the critical envelope function.
