Flow-induced vibrations and galloping of gates

Gates are steel boxes used to control the flow in rivers and water channels. The water flow instigates gates vibrations. Vibrations are transmitting from the gate structure into the barrage or dam structures causing to them some problems with time. Recently, modifications are done on the geometry of the gates to reduce the flow-induced vibrations, while no attention has been paid on one of the most important problems in the dynamic analysis of gates by neglecting the fluid-structure coupling. It is very complicated process to carry out the modal tests for all types and sizes of the in-site gates in the case of fluid-structural coupling. The modelling process may offer the suitable solution. Modelling process of such structures are performed considering the fluid-structural coupling, which are neglected before despite their dominent effects in the analysis and on the dynamic characteristics of the system. Finite element (FE) analyses considering fluid-structural coupling were done on a small, physical model. Also, experimental modal analyses on the scale model have been done out of water and in the case of one surface of the physical model is fury interfaced with water. The modelling verification and validation were done. The updated finite element method is applied to an in-site gate. Both analytical and experimental results are in a good agreement. A method for eliminating galloping, which is self-excited vibration, may be at many dynamic systems with an inherent source of negative damping is given. The galloping phenomenon is self-excited vibrations of large amplitudes transverse oscillations, which is associated with a fluid dynamic instability. In the gate analysis the galloping is an exciting fluid force in phase with the gate structure vibrating velocity that amplifies initial gate structure oscillations. The galloping elimination can be obtained by avoiding the coincidence between the gate natural frequencies and the fluid force frequencies. Avoiding the gate opening that causes the critical flow velocity, which instigate that frequency can eliminate a fluid force frequency. The critical flow velocities that instigate vertical and horizontal gate vibrations are given and operational gate chart is obtained.