Wind forces on bridge decks using state-of-the-art FSI methods
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Several bridges with span widths that challenge present technology are currently under planning in Norway, and wind effects are among the major concerns. Traditionally, wind-structure interactions are studied experimentally in the wind tunnel. However, with bridges that require careful and precise optimization of the aerodynamic properties, the sequence of wind tunnel tests quickly becomes a bottleneck and source of uncertainty. At the same time, the developments in computational power and technology makes numerical methods more relevant than ever in the study of wind effects. In this thesis, state-of-the-art methods of Computational Fluid Dynamics (CFD) and Fluid-Structure Interaction (FSI) are applied and further developed to simulate wind forces on bridge decks. The core technology is the Arbitrary Lagrangian-Eulerian Variational Multiscale (ALE-VMS) formulation of the Navier-Stokes equations of incompressible flows. In combination with coupling to structural dynamics, advanced mesh-moving techniques and multi-domain modeling, this highly developed formulation becomes a very powerful and versatile tool in the study of bridge aerodynamics. To prove this, all major topics of aerodynamic analysis of bridges are reviewed. Most of the effort is put into flutter and buffeting analysis, with in-depth studies on e.g., self-excited forces, aerodynamic derivatives and the aerodynamic admittance function. Other topics that are covered include e.g., stationary analyses, vortex-induced vibrations and scalability. Throughout the thesis, validation against wind tunnel experiments has been an essential task in order to prove the simulations credible. The present work proves numerical methods to be a valuable supplement to wind engineering, which, in combination with wind tunnel experiments, may provide the knowledge and insights required to design the next generation of long-span bridges in a safe and cost-effective way.