Conditional Simulation of Spatially Correlated Earthquake Ground Motion

Methodology is presented for simulating properly correlated earthquake ground motions at an arbitrary set of closely spaced points, compatible with known or prescribed motions at other locations. The input consists of the spectral density function and frequency‐dependent spatial correlation function in several nonoverlapping ground‐motion segments. Linear‐prediction estimators are used to generate a set of statistically independent, frequency‐specific, spatial random processes, based on which ground motions are composed by means of a fast‐Fourier‐transform algorithm. The method's advantage over existing linear‐estimation techniques, known as kriging, is that it correctly reproduces the specified space‐time correlation structure of the ground motion. Examples are given to illustrate the features of the simulation methodology; in particular, response spectra and dynamic response ratios are compared for recorded and simulated motions at the site of the SMART 1 strong‐motion accelerograph array.