This study presents the detailed model test results for the flow-induced vibrations of shell-type long-span gates, in which the upstream gate face consists of vertical and inclined skin plates (also referred to as weir plates). Shell-type gates possess two degrees-of-freedom, one each in the streamwise (horizontal) and vertical directions, due to the gate bending flexibility in those two directions. The streamwise and vertical vibrations can become closely coupled with each other through hydrodynamic forces acting on the weir plates, thus resulting in severe self-excited vibrations. A two-dimensional model study of a shell-type long-span gate under small gate openings but without overflow was performed to measure the vibration frequency, the excitation ratio (negative damping ratio) and the trajectories of gate motion, thus showing the effects of the inclined weir plate angle upon the dynamic instability of shell-type gates. It was conclusively described that the shell-type gates are most unstable when the inclined weir plate angle takes on a value of about 60° relative to the horizontal line.
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