Strong motion duration effects on base isolated systems

In this paper the non-stationary response covariance of a base isolated building subjected to a seismic excitation modelled through a zero mean Gaussian non-stationary stochastic process, uniformly modulated in the time with a boxcar-shape temporal function, is determined. The results are utilised to give an estimation of the strong motion duration effects on the temporal peak of the root mean square value of the response of the system and on system failure probability for first threshold crossing.