In the present paper, the impact of input ground motion characteristics on the seismic response of a typical concrete arch dam has been investigated by relying on the foundation numerical model.

For this purpose six ground motions, including near-fault and far-field recordings, with various characteristics in the acceleration response spectrum, have been used to analyze the coupled system. Three different options have been introduced for the dam-foundation interaction: 1) foundation rock is assumed to be rigid; 2) foundation rock is modelled as a massless medium; and 3) a massed foundation is assumed with the inclusion of infinite elements at the far-end boundaries. The reservoir medium is assumed to be compressible, and has been modelled according to the Eulerian approach. It has also been observed that modelling the foundation as a massed element decreases stresses relative to the massless model, while use of a rigid foundation model leads to stress concentration at the dam-foundation interface. In all these foundation types, near-fault ground motions have led to higher responses than far-field motions, especially for the upper parts of the dam body, with less scattering of results in far-field ground motion.

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