A probabilistic approach to define the reliability of gates at dams and weirs

The safety of a dam depends, among other things, on the functionality and the hydraulic ability of the gates. Therefore, a literature study was undertaken by observing national and international research to receive actual failure frequencies of gates and weirs. This information is necessary to extend the so called (n-1)-condition in the actual dimensioning process from a deterministic design concept towards a probabilistic approach. Because of the determined lack of data, a kind of semi-probabilistic approach was developed, to treat varying failure probability of different gate types. The basic principle is to generate an evaluation matrix to assess different gate structures relating to their failure patterns. The result should be a defined “basic-value” for each gate type, which reflects the overall susceptibility. Furthermore, there should be a possibility for design engineers and operators of dam structures to intervene the dimensioning process through an “individual value”.