3-DIMENSIONAL VIBRATIONS OF INFLATABLE DAMS

Inflatable dams are used for various purposes, such as controlling flood-waters, diverting water for irrigation, impounding water for recreation, raising the height of existing spillways, and preventing beach erosion. They are flexible, cylindrical structures attached to a rigid, horizontal base. The vibrations of such dams are investigated in this paper. The dam is modelled as an elastic shell inflated with air and anchored along two of its generators. Both infinitely-long darns and dams of finite length are considered. Previous analyses have only considered two-dimensional vibrations and have assumed that the dam is an inextensible membrane. The finite element method is applied, first to determine the equilibrium shape of the dam and then to analyze small vibrations about that configuration. For the numerical examples, the lowest six vibration frequencies and corresponding mode shapes ave obtained. The results are compared to those when no external water is present.