Seismic assessment of a dam-foundation-reservoir system using endurance time analysis

J W Salamon (US Bureau of Reclamation); M A Hariri-Ardebili (Univ. Colorado); H E Estekanchi, M R Masheykhi (Sharif Univ. of Technology)

Quantification of the progressive failure of concrete dams subjected to seismic excitation is a vital step in dam safety risk evaluation. The risk-inform approaches require a comprehensive structural analysis for several specific ground motions to identify the potential failure modes. Probabilistic seismic hazard analysis, ground motion selection, and scaling techniques are complex, time-consuming processes for any particular dam site. Very often, the structural and risk analyses are delayed while seismologists compile the investigation results.

The alternative technique is to use the Endurance Time Analysis (ETA). In ETA, a finite element (FE) model of the dam-foundation-reservoir system is excited using artificially generated signals called Endurance Time Excitation Functions (ETEF). These functions, which have a linearly intensifying nature and are compatible with the particular ground motion’s response spectrum, excite the model all the way from linear elastic range to nonlinear range and, finally, lead to failure. This paper proposes an original approach for the seismic assessment of concrete dams using ETA. ETEF is developed based on the selected ground motion, and the approach is illustrated by the FE analysis of a gravity dam. A comparison is made between the ETEF excitation and the scaled-up ground motions. A general discussion follows, and then conclusions and recommendations are provided.

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