Probabilistic Response Analyses to Earthquakes

A single degree-of-freedom system is analyzed probabilistically for earthquake-like excitations. A Gaussian nonstationary random process model developed previously has been used for the ground acceleration. After finding the variance of the response, the distribution of the highest peak is determined approximately. The average of this is closely related to the conventional average response spectra. Numerical results are presented for four earthquake-like excitations which differ widely in their properties such as duration, maximum acceleration, rate of zero crossings, etc. The four excitations are supposed to simulate the Port Hueneme (NS, March 18, 1957); Vernon, CA (S82E, October 2, 1933); Taft, CA (S69E, July 21, 1952); and Tower Latino Americana, Mexico (N09E, May 11, 1962) earthquakes. The present approximate analysis indicates that long duration earthquakes may have more than one peak in their undamped average velocity spectra.