The covariance response of linear systems to locally stationary random excitation

A simple method is given for calculating the covariance response of linear, time-invariant systems to random excitation processes which are locally stationary, or approximately so. As an illustration, the method is used to estimate the response of an idealized model of a ten-storey building to non-stationary ground acceleration; the accuracy of the estimated response is assessed by a comparison with the results of a less approximate, but lengthier, general calculation method, previously published.