Flow-induced dynamic instability closely related to Folsom Dam Tainter-Gate failure in California

This study presents calculated results for a flow-induced coupled-mode vibration instability which would have caused a serious failure of a huge 87-ton Tainter gate at Folsom Dam in California. The Folsom Tainter-gate originally possesses two significant vibration modes of a whole gate vibration around the trunnion pin and a streamwise bending vibration of the skinplate, which are coupled well to each other through the hydrodynamic force caused by flow-rate variations under the gate and the skinplate inertia torque due to the vibrations, to induce a violent self-excited vibration under certain conditions. The equations of motion for such a dangerous kind of coupled-mode vibrations are approximately solved for the Folsom Tainter-gate to reveal its strong flow-induced dynamic instability, where the closed energy cycle for the self-excited vibrations is definitely addressed.