The collaboration between the two national committees, JCOLD and CFBR, has been a unique opportunity to launch new simplified dynamic analyses. This paper presents a new simplified dynamic analysis for embankment dam. The main assumptions of this analysis are based on observations of the seismic performances of large dams under strong motion earthquakes and their interpretations. The qualification of this analysis is based on the comparison between observed and predicted seismic performances of dams. By this way, the new method is an attempt to capture the main observed phenomena leading to failure, which are not always taken into account by the current simplified methods.