Abstract: The current hydraulic seismic design code has clear provisions for the amplitude and frequency spectrum of strong earthquakes, but no provision for the impact of their duration on the seismic response of high-performance hydraulic structures. At present, a variety of definitions for the duration characteristics of strong earthquakes are available, but most of them only consider unidirectional ground motions, underestimating the duration impact in multi-directional cases. This paper constructs a dam-reservoir-foundation dynamic coupling analysis system through a case study of a high asphalt-concrete-core sandy gravel dam. We adopt an integrated duration index for multi-directional strong earthquakes, and use an incremental dynamic analysis (IDA) method to evaluate the influence of short-duration and long-duration ground motions on the seismic performance of high asphaltic concrete core rockfill dams, taking the relative settlement ratio of dam crest as an evaluation index of structural performance. Thus, this analysis system can give the damage level of a high asphaltic-concrete-core rockfill dam and its seismic fragility curves considering the integrated duration effect. Results show that the integrated duration characteristics of ground motions have a significant impact on dam failure probability at different performance levels. For fixed seismic intensity, dam failure probability at longer ground motion duration is greater than that at shorter duration.

Key words: high asphaltic concrete core rockfill dam, integrated duration, relative settlement ratio, fragility, failure probability