Effects of aerodynamic appendices on the flutter characteristics of long-span bridge decks

This research deals with the effects produced by aerodynamic appendices on the aeroelastic stability of long-span bridge decks. A simulation model is presented by which the structural motion and the fluid flow are together and simultaneously simulated. The deck is schematised as a bidimensional two-degree-of-freedom rigid oscillator, whilst the aerodynamic fields are simulated by numerically solving the 2D Arbitrary Lagrangian-Eulerian (ALE) formulated Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations on moving meshes which adjust to the deck motion. The proposed finite volume method is based on high order Weighted Essentially Non-Oscillatory (WENO) reconstructions. The time discretisation is performed by a five stage fourth order accurate Strong Stability Preserving Runge-Kutta (SSPRK) method. It is shown that the proposed numerical method makes it possible to ensure both high accuracy in time and space. The simulation model is validated by comparing the numerical results with experimental data and is applied to the evaluation of the aeroelastic stability of the forth road suspension bridge deck. The effects of aerodynamic appendices on the flutter characteristics of the forth road bridge are investigated via the proposed simulation model. It is demonstrated that the presence of the cross-section details (barriers, railings, dividing strips) makes the aeroelastic stability of the deck worse and that the flutter sensitivity is mitigated by introducing a couple of sloping barriers at the edges of the deck.