Energy budget analysis and engineering modeling of post-flutter limit cycle oscillation of a bridge deck

Abstract

Abstract The post-flutter limit cycle oscillation (LCO) of a two-degree-of-freedom bridge deck involving aerodynamic nonlinearities is studied using computational fluid dynamics (CFD) simulations. To investigate the aerodynamic mechanism for the post-flutter LCO, a comprehensive energy budget analysis is conducted based on the simulated responses, in which the energy input properties of the 1st-order and higher-order force components are considered separately. Results show that only the 1st-order force components contribute significantly in the energy input, while the contributions of the higher-order force components are insignificant. The sensitivities of aerodynamic derivatives to vibration amplitudes and phase difference between vibration modes are investigated using forced vibration CFD simulations. For the concerned bridge deck, some aerodynamic derivatives are highly sensitive to vibration amplitude, while the influences of modal coupling effects are insignificant. A simplified multi-input multi-output nonlinear self-excited force model with amplitude-dependent aerodynamic derivatives is developed according to the sensitivity analysis. An example of bridge post-flutter LCO with two degrees of freedom is utilized to demonstrate the accuracy of the amplitude-dependent aerodynamic derivative-based model. The model also applies to single-degree-of-freedom LCOs, e.g., galloping and vortex-induced vibration, and hence it may serve as a unified analysis framework for nonlinear bridge aeroelasticity.