820 3D Model Tests for Coupled-Mode Self-Exited Vibration of Full-Scale Tainter-Gates : Week Vibration Synchronized with Whole Gate Vibration around Trunnion Pin

Abstract

This paper presents the test results of coupled-mode self-excited vibration of Folsom dam Tainter-gate by the large-scaled 3-dimension model gate. The Folsom gate was represented by a 1/31-scaled model, where the whole gate vibrates around the trunnion pin and the skinplate vibrates in the streamwise direction. Both the vibration modes will couple through hydrodynamic and inertial forces. This type of coupled-mode vibration is accompanied by the flow-rate variation under the gate, thus inducing a violent self-excited vibration in certain conditions. In the present model tests, the frequency ratio of the skinplate streamwise in-water natural vibration to the whole gate rotational vibration around the trunnion pin was varied from 0.8 to 1.5. As a result, the vibration synchronized with the whole gate vibration around the trunnion pin was revealed, in addition to the vibration synchronized with the skinplate streamwise vibration.