Determination of stochastic characteristics of seismic non-stationary random excitation processes

Non-stationary random excitation process can be decomposed into the deterministic part (modulation function) and the stationary stochastic part. This pa,per, first, gives an overview of these modulation functions used, which are currently used. Secondly it proposes a new function, which consists of the B-splines. Remarks on applicability and examples of their use are included. The stationarity, spectral density approximation and Gaussian character of the stationary stochastic part of the excitation process is tested.