3-DIMENSIONAL VIBRATIONS OF INFLATABLE DAMS

Inflatable dams are used for various purposes, such as controlling flo od-waters, diverting water for irrigation, impounding water for recrea tion, raising the height of existing spillways, and preventing beach e rosion. 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 d ams of finite length are considered. Previous analyses have only consi dered two-dimensional vibrations and have assumed that the dam is an i nextensible membrane. The finite element method is applied, first to d etermine the equilibrium shape of the dam and then to analyze small vi brations about that configuration. For the numerical examples, the low est six vibration frequencies and corresponding mode shapes ave obtain ed. The results are compared to those when no external water is presen t.