Effects of Spatial Variability of Earthquake Ground Motion

Abstract

The codes of practice state that for large in-plane structures it is necessary to account for the spatial variability of earthquake ground motion (SVEGM). There are essentially two effects that contribute for this variation: (i) wave passage effect, due to finite propagation velocity; and (ii) the local site amplification due to spatial variation in geological conditions. This paper discusses the procedures to be undertaken in the analysis of a cable-stayed bridge under SVEGM. One of the problems is the artificial generation of correlated displacements records that simulate the earthquake load. A comparison of the effects produced by seismic waves with different propagation speeds and different geological conditions is undertaken. The results in this study show that the differences between the analysis with and without spatial variability of earthquake ground motion are not important.