Geotechnical aspects affecting the selection of input motion for seismic site response analysis

A procedure recently proposed by the authors was applied to select suitable sets of acceleration time-histories to be used in 1D seismic response analyses for a strategic site in the Messina (Italy) strait area. Starting from a probabilistic seismic hazard analysis of the area,proper ranges of earthquake magnitude and source-to-site distance have been detected and used for a preliminary selection of input ground motions. Then, a proper interval of vibration periods, relevant for the seismic response of the site of interest, was defined accounting for the soil non-linear behaviour and for the possibly occurring frequency coupling. With reference to the Life Limit State and to different reference lives, ranging from 100 to 200 years, real acceleration records were selected fitting, in the selected interval of vibration periods, a target (code-prescribed) ground motion defined in terms of elastic response spectra. As a result, the relevant effect of the geotechnical properties of the soil deposit on the results of the accelerogram selection procedure is highlighted and discussed in the paper.