Near fault and far fault seismic analysis of concrete gravity dam

Ground motions records of the past higher magnitude (Mw>5) earthquakes have indicated that ground motions recorded at the closest distance of the near-fault are very different from those recorded from a higher distance from the site of the far-fault. Forward directivity and fling effect are the essential characteristics of the near-fault earthquakes; these can cause potentially high damage during earthquakes. Hence, to understand the effect of the far-fault and near-fault on the performance of the structure is vital to reduce the damage and perform an efficient response. In this paper, an attempt is made to evaluate the effects of far-fault and near-fault ground motions on the seismic performance of the concrete gravity dam incorporating the dam-reservoir-foundation interaction. An arbitrary gravity dam is considered as numerical example. In this, eight different earthquake records are considered for time history analyses. The seismic performance of the dam is evaluated using the cumulative-overstress-duration (COD) and demand-capacity ratio (CDR). The results obtained show the importance of the near-fault ground motion effect on the seismic performance of the concrete gravity dam.