Extension of wake oscillator model for continuous system and application to the VIV-galloping instability of a bridge during launching phase

Abstract

For prism bodies or sectional models, Tamura’s nonlinear wake oscillator model has exhibited reasonable successes in modeling the interaction problem between vortex induced vibration and galloping, suggesting the potential to serve as an effective tool for practical use. Making a step further, this paper introduces an approach to apply the wake oscillator model to a continuous structural system with non-uniform mode shapes. This approach is based on coupling multiple discrete wake oscillators to the continuous structural system, which is described by the finite element method. A clear advantage is the high flexibility in considering the variation of structural and aerodynamic parameters along the axis of the continuous system. After validating this approach, a steel–concrete composite bridge during its critical launching phase was used as a case study for the interaction problem between vortex induced vibration and galloping. The effect of mode shape and the synchronicity between discrete wake oscillators and vibrating structural system were analyzed and discussed. Moreover, the capability of the presented approach in considering the participation of multiple structural modes in the fluid–structure interaction is shown. For the studied engineering case, the important role of the launching nose and its implication were highlighted, which might be very useful for the suppression of galloping instability in practical bridge launching.