Response statistics of structural systems subjected to fully non-stationary spectrum compatible excitation

The probabilistic analysis of structural systems subjected to seismic excitations requires the spectral characterization of both the input excitation and the structural response; in order to reproduce the typical characteristics of real earthquakes ground-motion time history, the seismic excitation should be modelled as a non-stationary stochastic process. Once the characterization of the ground motion acceleration is done, it is possible to analyze the safety of structural systems subjected to those excitations; in particular, the largest absolute value peak of stochastic response is a useful design information. In order to define the statistics of the maximum of the stochastic response of structures, it is necessary to evaluate the Non-Geometric Spectral Moments (NGSMs). In this paper the fully non-stationary spectrum compatible model has been adopted to define the ground motion acceleration process. Then the evaluation of the NGSMs is performed. The main steps of the proposed approach are: i) the study of a set of real earthquakes to catch their most important features; ii) the introduction of the fully non-stationary spectrum compatible process; iii) the definition of the NGSMs, in the time domain; iv) the evaluation of the mean frequency; v) the validation with the Monte Carlo Simulation