Three-Dimensional Flutter Analysis of Aeroelastic Models of Bridge Decks Based on Large-Eddy Simulations

In light of the limitations of traditional methods based on a sectional deck model in predicting full-bridge flutter responses, a fluid–structure-interaction simulation method for directly solving the three-dimensional flutter responses of a bridge deck aeroelastic model is proposed in this study. The influences of pylons, cables, and hangers are reflected in modal parameters of the flexible deck. The structural and fluid dynamics are solved based on the mode superposition method and large-eddy simulation technique, respectively. Verification and validation of the simulation technique was conducted based on a thin plate for which the theoretical critical wind speed of flutter is available. The potential difference in flutter responses between a finite-length rigid deck model and a full-length aeroelastic deck model is highlighted. Flutter responses of an aeroelastic deck model of a suspension bridge were simulated and investigated. It was found that higher-order modes may be excited during flutter and vibrate at the same frequency as the primary flutter mode. Those modes with the same symmetry characteristics as the primary flutter mode and that have a natural frequency close to the primary flutter mode exhibit larger vibration amplitudes. To study the multimode coupling and modal shape inconsistency effects on flutter responses, a bimodal model and a modal-shape-consistent model were designed. Both models had a slightly lower critical wind speed of flutter than the original model. The spanwise correlation coefficients of surface pressure and aerodynamic forces of the aeroelastic model were much lower than those of the rigid model, which was caused mainly by the nonuniform additional static wind angle of attack along the spanwise direction. The proposed simulation method could serve as a new effective approach for refined analysis of three-dimensional flutter responses of bridges, and the research findings in this study contribute to a better understanding of the multimode flutter characteristics of long-span bridges.