Stochastic seismic analysis by using an analytica lmodel of PSD consistent with Response Spectra

Most of the seismic codes define seismic actions by means of pseudo-acceleration Response Spectra (RS) and strongly encourage the use of the modal superposition analysis method. The effectiveness of this design procedure is bounded by the limitations inherent to those analytical tools, such as the linearity of the system and the reliability of the modal correlation coefficients used to superimpose the modal responses. Conversely, for linear systems the use of the stochastic analysis tools could straightforwardly allow the direct evaluation of all the quantities of interest in a more adequate statistical framework, once a stochastic characterization of the seismic action is provided. This paper aims at defining a parametric analytical definition for Power Spectral Density functions (PSD) coherent with a wide range of Response Spectra defined by several international seismic codes with different shapes. The reliability of such a powerful tool is then assessed through an extensive numerical campaign by comparing stochastic analysis and Monte-Carlo simulations.