Accurate description of non-stationary random seismic excitation

Seismic random processes are characterized by high non-stationarity and, in most cases, by a marked variability of frequency contents. The widely used hypothesis modelling seismic signal as a simple product of stationary signal and a deterministic modulation function, consequently, is hardly always applicable. Such assumption leads to an incorrect estimation of the frequency contents, which can significantly influence the assessment of structural response to such a seismic event. As a solution, the multicomponent decomposition of the non-stationary seismic record is presented. The wavelet multi resolution analysis is used as a tool. An example of the seismic response of a simplified structure is given. (author)