Wind-induced excitation upon a bridge needs to be treated very carefully. Long, lightweight bridges are susceptible to wind action, and show a certain interaction between the motion of the deck and the ambient flow. This aeroelastic force acts as an additional dynamic load, inducing a self-exciting oscillation mechanism into the structure, which could lead to failure of the dynamic system. The evaluation of structural behavior requires analysis of the dynamic properties, as well as the analysis of the aeroelastic forces acting upon it. In the present work, the deep stall flutter aeroelastic instability has been investigated. Stall flutter, is a two degree of freedom instability, and takes place under the coupled motion between the vertical and torsional movement of the bridge deck. The response prediction of the structure is determined by aeroelastic flutter derivatives. The identification of the parameters is done by the means of computational fluid dynamics techniques. The thesis focuses assessing the applicability of recent methodologies analyzing the flutter response of long-span bridges. Mainly, the single harmonic and the multi-frequency based forced vibration analysis. Both methods identify the flutter derivatives related to an imposed motion (heave or pitch) for a specific reduced frequency. The main advantage of the multi-harmonic forced vibration approach is that it allows to determine the aeroelastic flutter derivatives for different reduced frequencies at once. Thus, reducing the computational power demands of the numerical simulations, by performing only one simulation for multiple reduced frequencies. In the present work, a rectangular section with an aspect ratio of 5:1 and a bridge-like section are evaluated under smooth flow. The experimental set up and the system parameters extraction method are described, and their influence on the flutter derivatives are discussed in detail. For both cross sections, the flutter derivatives are identified by the two proposed methods, and a comparison is carried out, which includes literature studies (numerical and experimental wind tunnel tests) and aeroelastic method (direct identification in time domain), in order to validate the obtained parameters.     «

Wind-induced excitation upon a bridge needs to be treated very carefully. Long, lightweight bridges are susceptible to wind action, and show a certain interaction between the motion of the deck and the ambient flow. This aeroelastic force acts as an additional dynamic load, inducing a self-exciting oscillation mechanism into the structure, which could lead to failure of the dynamic system. The evaluation of structural behavior requires analysis of the dynamic properties, as well as the analysis...     »