Efficiency of ground motion intensity measures with earthquake-induced earth dam deformations

In a seismic hazard analysis (SHA), the earthquake loading level should be predicted for one or more ground motion intensity measures (IMs) that are expected to relate well with the engineering demand parameters (EDPs) of the site. In this particular study, the goal was to determine the IMs that best relate to embankment dam deformations based on non-linear deformation analysis (NDA) results of two embankment dams with a large suite of recorded ground motions. The measure utilized to determine the “best” IM was standard deviation in the engineering demand parameter (e.g., deformation) for a given IM—[sigma]lnEDP|lnIM, also termed “efficiency.” Results of the study demonstrated that for the NDA model used, Arias intensity (AI) was found to be the most efficient predictor of embankment dam deformations. In terms of spectral acceleration (SA)-based IMs, the SA at short periods and then in the general range of the natural period of the dams were seen to be the most efficient IM, but was in almost all cases not as efficient as AI. In terms of total standard deviation ([sigma]lnDYF|M,R,S) of EDP conditioned on earthquake source parameters, the poor predictability of AI relative to other IMs resulted in a higher total standard deviation given an earthquake. Within this context, CAV was deemed the best IM.