Flow-Induced Vibration of Long-Span Gates due to Shed Vortices (Vibration Criteria, Level of Fluid Excitation and Added Mass).

Submerged long-span gates which dam wide rivers can undergo violent streamwise vibrations caused by vortex shedding beneath the gate. This study presents flow-induced vibration characteristics which were obtained in a model gate test. From the measured vibration frequencies and damping ratios in air and water, the level of fluid excitation and the added mass for small-amplitude gate vibrations are calculated and reduced to a dimensionless form. Thus, the vibration criteria are obtained. In addition, the average values of the maximum amplitudes of gate vibration were measured. The results of these experiments, taken as a whole, suggest that the flow-induced vibration characteristics of the long-span gates are well predicted by dimensionless parameters, such as the reduced gate opening and the reduced velocity.