The Role of Modulation Function in Nonstationary Stochastic Earthquake Model

In structural engineering earthquakes are often represented as random phenomena. Frequently, filtered white noise stochastic processes are adopted to properly model their frequency content. In order to model the time variation of earthquake intensity, these processes are assumed nonstationary, and time modulation functions (MFs) are used. For these, different shapes and formulas have been proposed in literature till now, but only few works have dealt with their comparison in terms of structural response. This paper focuses on this topic: at this aim, a simple linear single degree of freedom (SDoF) system, which represents a structure vibrating in its fundamental mode, is considered subject to a time modulated filtered stochastic process. Different shapes of the MF are considered and the influence on two structural response indices, i.e. the maximum displacement standard deviation and the failure probability, is investigated. A sensitivity analysis is finally performed by varying peak ground acceleration (PGA), Arias intensity and structural period.

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