Analysis of Behavior of Earth Dam Using Strong‐Motion Earthquake Records

The seismic records of the Long Valley Earth Dam are utilized in order to shed some light on the salient features of the dam nonlinear behavior. The dam is well instrumented with 22 accelerographs tied with a common triggering. It was shaken in the 1980s by a series of earthquakes that varied in intensity and maximum induced accelerations. The analysis is based on ideas of system‐identification techniques. A preliminary pattern recognition, based on a spectral analysis, shows evidence of three‐dimensionality and nonlinearity in the dam behavior and of seismic wave propagation at its boundaries. The investigation shows that, although constitutive hysteretic models provide reasonable approximations, they are insufficient to fully account for all the vibrational dissipation mechanisms. It also reveals that the model response in the upstream‐downstream direction has a better quality of fitness to the recorded response than do the responses in the longitudinal and vertical directions. Furthermore, the analysis shows an insufficiency of the instrumentation at the structures boundaries. Finally, this case study shows that seismic records can be utilized to produce a wealth of information not available by other means.