The Hyogoken-Nambu Earthquake occured on January 17, 1995. The Richter Magnitude of the earthquake was estimated to be 7.2. Fortunately, no damage was caused by the earthquake to Hitokura Dam situated 47km northeast of the epicenter. However, on seismographs placed in the upper- and lower-level inspection galleries, accelerations as large as 483 Gal and 183 Gal, respectively, (both in the horizontal direction) were recorded. The paper describes a two-dimensional FEM dynamic analysis performed using seismograms recorded at Hitokura Dam to evaluate the damping constant of the model used and the effect of vertical waves. A comparative dynamic response analysis was also performed using seismograms recorded during previous earthquake incidences. Following findings were obtained from the analysis. Analytical values correspond most closely to measured values when 10% was used for the damping constant, indicating the propriety of use of the value. The effect of the vertical components of incident waves could be best simulated when both the vertical and horizontal components were considered. However, no marked variations were observed in stress response values, indicating that the effect of vertical waves on stresses is small. The results of a comparative response analysis, which was performed using four different waveforms, namely, Hitokura, Narugo, Susohana and Tarumizu, and assuming the maximum acceleration to be 200 Gal, show that the maximum dynamic stress was induced by Hitokura wave.
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