Vibration attenuation of air inflatable rubber dams with variable anchorage width

Abstract

The attenuation of mechanical vibrations is a key factor in the design of structures, even more when they are related with flexible membranes as inflatable dams, where the self-excited vibrations are assumed to result from hydraulic disturbances that include unsteady water flow. In this work, the strategy for the attenuation of structural vibrations in semi-cylindrical air inflatable rubber dams proposed by Choura (1997), namely by properly varying the internal pressure, is extended to a variable anchorage width geometry adapting the mode shapes parameterization. It is demonstrated that an adequate variation in the internal pressure can modify the dynamic parameters of the structure. This approach is used to actively control the structure, measuring the induced vibration and varying the internal pressure accordingly for attenuation. The methodology followed in this work may fall under the definition of active control once that the internal pressure is changed in "real time", as a function of the self-excited vibration.