ABSTRACT
In order to prevent the uncontrolled rapid release of water from the reservoir of a storage dam during a strong earthquake, the dam must be able to withstand the strong ground shaking from even an extreme earthquake, which is referred to as the Safety Evaluation Earthquake or the Maximum Credible Earthquake. Large storage dams are generally considered safe if they can survive an event with a return period of 10,000 years, that is, having a one percent chance of being exceeded in 100 years. There is a basic difference between the load bearing behaviour of buildings and bridges on the one side, and dams. Under normal conditions buildings and bridges have to carry mainly vertical loads due to the dead load of the structures and some secondary live loads. Moreover, most of the existing buildings and bridges have not been designed against earthquakes using modern concepts, whereas dams have been designed to resist against earthquakes since the 1930s.
