08-10-2014, 04:17 PM
Consideration of spatial variability in seismic ground motion in the analysis of extended structures has been proven to be essential. For simple structures this can be conveniently incorporated in terms of cross power spectral density function during stochastic analysis. But for complex or non-linear structures, where time-history analysis is to be performed, a set of properly correlated earthquake accelerograms is required. In view of this, a new simulation approach for the generation of spatially variable seismic ground motions is presented. The simulated motions have realistic temporal variation in amplitude and frequency content and those are consistent with the design spectrum in the mean sense. Wavelet transform has been used for the time-frequency analysis and a new complex harmonic wavelet basis function has been proposed specially to deal with earthquake signals. Though a stationary coherency model has been chosen, but it can easily be extended for any other non-stationary model also, when they are made available. The proposed approach has been illustrated by tw