Dynamic Performance Evaluation of Gate Vibration

This paper demonstrates how the use of appropriately scaled model experiments can effectively be used to evaluate the dynamic performance of a new gate system. The physical scale models studied in this investigation are exact replicas of the innovative hydraulically actuated wickets to be placed at the Olmsted Locks and Dam for controlling water flow and maintaining a navigable pool on the lower Ohio River. Operating shapes of the flow-induced gate motion at critical configurations are compared with the wet characteristic modes of the wicket to determine the potential resonant vibration problem. These wet modes are extracted such that the effects of structural and hydraulic boundary conditions of the flow field are accounted for in the modal experiment. Experimental results indicate that random energy contents of an ambient excitation can readily be used to estimate the physical characteristic modes of a wet structure. The study also shows that operational deflected shapes for potentially alarming excitations can be compared with such wet natural modes to identify resonance problems. This evaluation procedure demonstrates the convenience in using ambient vibration for the detection of self-excitation problems during the service life of the system.