Closed-form solutions for the evolutionary frequency response function of linear systems subjected to separable or non-separable non-stationary stochastic excitations

摘要

In the seismic engineering, in order to reproduce the typical characteristics of real earthquakes ground-motion time history, the so-called uniformly modulated and the fully non-stationary random processes have been introduced. The first process is constructed as the product of a stationary zero-mean Gaussian random process by a deterministic function of time; for this reason it is also called separable non-stationary stochastic process. However, this process catches only the time-varying intensity of the accelerograms. To consider simultaneously both the amplitude and frequency changes, time-frequency varying deterministic functions have been introduced in the characterization of the input process. The latter process is referred as fully or non-separable non-stationary stochastic process.