Effects of ground motion characteristics on seismic response of earth dams: some remarks on duration and vertical shaking

Acceleration records used as input motion for nonlinear dynamic analyses of earth dams can significantly affect the outcome of the analyses. The selection of an adequate set of records is therefore an essential step of the study. Customary approaches rely on matching the target spectrum and the average response spectrum of the selected records. Furthermore, vertical motion is often considered to have a modest influence on dam response. In this paper, FLAC was used to conduct dynamic analyses of an earth dam located in Central Italy. The response was assessed in terms of permanent crest settlements and correlation were attempted with several IMs. The analyses were conducted with and without vertical component of motions. It was found that Arias Intensity may be considered an additional parameter to guide selection of input motions. The inclusion of the vertical components lead to a general increase, on average 75%, of the crest settlement.