Efficient estimation of the peak factor for the stochastic characterization of structural response to non-stationary ground motions

Abstract

[EN] The determination of the peak factor is quite cumbersome in the case of a non-stationary process, due to the necessity of calculating the non-geometric spectral moments of the process and obtaining the threshold level of the first-passage problem corresponding to a certain non-exceedance probability value. In this paper, an efficient approximate new method is presented for practical applications in Earthquake Engineering. The so-called Equivalent Oscillator and Response method consists of transforming the original oscillator excited by a uniformly modulated non-stationary colored noise into an equivalent oscillator excited by a uniformly modulated non-stationary white noise, in such a way that the responses of both oscillators have similar values for the spectral parameters that affect the calculation of the peak factor. A new dimensionless spectral peakedness factor is introduced in order to ensure the matching of the spectral bandwidth of both oscillators. A numerical application of the new method, based on a nonstationary seismological model for the ground accelerations process, is carried out, showing the reliability and robustness of the new method for efficiently and accurately estimating the peak factor of the nonstationary structural response.