Numerical investigation of fluid-structure interaction for long-span bridge decks

IIn this work a simulation model of aeroelastic phenomena for long-span bridges is presented. By the proposed model the aerodynamic field and the structural motion are simulated simultaneously and in a coupled manner. The structure is represented as a bidimensional rigid body with two degrees of freedom, having mass per unit length and mass moment of inertia per unit length equal to those of the deck. The aerodynamic fields are simulated by numerically integrating the Arbitrary Lagrangian-Eulerian (ALE) formulated Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations with a finite volume scheme on moving grids which adapt themselves to the structural motion. The 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. The URANS equations are completed by the turbulent closure relations which are expressed as a function of the turbulent kinetic energy and the turbulent frequency according to the k-omega SST approach. The model validation is performed by the comparison between numerical and experimental results. The proposed model is utilised in order to identify the flutter critical wind velocity of the Forth Road Bridge deck, and the numerical results are compared with those of an experimental campaign.