Seismic Response of Concrete Gravity Dam

Kaushik Das, Pankaj Kumar Das, Lipika Halder
NIT Agartala, INDIA


A concrete gravity dam is a submerged complicated structure which is designed in such a way that its own weight resists the external forces and hence its behavior under seismic actions due to earthquakes has become a matter of immense interest by the researchers. This type of structure is most durable and solid, and hence requires less maintenance. Concrete gravity dams can be constructed with ease on any dam site, where there exists a natural foundation strong enough to bear the enormous weight of the dam. These dams are mainly constructed to utilize the potential energy of rivers for the generation of hydropower and for the purpose of irrigation as they are expected to retain the water impounded in the reservoir and to resist the earthquakes with acceptable damages in the seismic prone areas. Thus failure of such dams may lead to catastrophic events with sudden release of reservoir and devastation of surrounding habitation. Therefore, the issues of safety of dams are looked with increased attention in various parts of the world in recent years. To prevent the failure of dams in seismic regions, it is important to assess its behavior at any age during its lifetime, so that remedial measures can be taken to strengthen or decommission of the dam at the right time.

Hence for the design and safety evaluation of an earthquake resistant dam, it is important to use a rational dynamic analysis procedure. The dynamic analysis of a linearly elastic dam is done through standard techniques for an empty reservoir, but problem becomes complicated when the interaction effects of unbounded reservoir and the elastic foundation has to be suitably accounted for as the analysis procedure employed should be capable of evaluating the dynamic deformations and stresses in a dam subjected to a given ground motion.

In the present work a simple dam model is modeled and analysed with the help of ALTAIR HYPERWORKS 10 software and the seismic response is evaluated for a KOYNA EARTHQUAKE ground acceleration data and the seismic response are computed for hydrodynamic pressure force for the duration of earthquake. The effect of concrete degradation on the seismic response is also considered in the present study which would help in safety evaluation of the concrete gravity dam under consideration at any specific age.

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