The dynamic characteristics of pressurized cylindrical membranes used as dams are
considered here. Single-anchored air-inflated membranes are predominantly studied. Load combinations
are considered without any water, with impounding water, and with water overflow.
The two major experimental variables are the dam's internal pressure and the stream's flow rate
or the impounded water height. The existence of upstream water is shown to completely change
the dynamic characteristics of the membrane-dam, now a structure-fluid system. Two aspect ratios
are considered with the same height, at two separate open-channel facilities. The material used is
modeled as an inextensible weightless membrane without any bending stiffness. It is shown that
the ratio between the internal pressure head and the upstream water head, identified as the
"pressure ratio", is the major controlling parameter. During overflow conditions, the pressure ratio
is shown to have a critical value where the energy of vibration maximizes. In addition, the ratio
of the upstream water head to the dam's height, identified as the "load ratio", is non-linearly
proportional to the vibration's energy level. Both the pressure ratio and the load ratio are shown
to be dependent on the model's aspect ratio. The pressure ratio is slightly non-linearly proportional
to the natural frequencies of the system, while the load ratio is inversely proportional. Up-scaling
of the results follows the Froude law. The source of vibrations either in the form of a driving
force or a perturbation force is identified to be at the downstream base of the dam.
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