ABSTRACT:

As one of three key factors in ground motion, the effect of seismic duration on the dynamic response of gravity dam most focus on theoretical analysis, and few concrete dam model tests are carried out to discuss about it. In order to research the influence of duration on the seismic behavior of high concrete gravity dam, in this study, a 185 m gravity dam model experiment based on similarity theory is carried out on a shaking table which type is Dys-600-5-05. The inputting seismic peak ground acceleration is kept as 5.32 g, and the earthquake periods are 0.48 s, 1.44 s, 3.20 s, 6.4 s, 9.6 s, respectively. Test results show that: when the seismic duration is less than 1.44 s, the dam body has no obvious crack, and there is no change in the whole frequency. After the time of 3.2 s, crack appears at the bending position above the dam toe of downstream face, and the crack extends to the bottom of the dam and eventually develops to be a penetrating crack at the time of 9.6 s. This study suggests that the dam will not be damaged when suffered a short duration of strong earthquake even if the peak acceleration is very large. With the duration increasing of strong earthquake, the cumulative damage of gravity dam is intensified, and the frequency of dam will significantly decreased.

1. INTRODUCTION
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