Seismic Impact in the Free Field (Response Spectra and Accelerograms)

There are several ways of setting seismic impact on bedrock for calculating the impact on the free field. In the paper, two ways of setting the initial seismic impact on bedrock are analyzed: artificial and synthetic accelerograms. For assessing the effect of the soil profile in transferring seismic signals from bedrock to the free field, four seismogeological models were used. Linear and nonlinear (equivalent-linear approximation) behavior of soil profiles were studied. Summing all results of calculations, we conclude that there are no significant differences in expected seismic impact on the free-surface depending on how the input is set at bedrock. Systematically larger values when synthetic method is used is not more than 10%, which is not evaluated as being significant.