Cross-sectional distributions versus integrated coefficients of flutter derivatives and aerodynamic admittances identified with surface pressure measurement

Global coefficients for unsteady aerodynamic forces are a powerful tool for the assessment of the aeroelastic response of bridges in turbulent winds. However, global coefficients do not provide any information about the phenomenology of the fluid–structure interaction. This paper introduces a distributed representation of global coefficients that, exploiting the knowledge of the unsteady pressure field along the contour of the deck, allows to understand more in detail the aerodynamics of the phenomenon. We use the distributed representation to analyze the unsteady forces acting on a simple closed-box single girder deck, and we focus the study on two aspects. First, we analyze the unsteady aerodynamic forces near the stall of the moment coefficient, highlighting that a specific area of the deck governs the phenomenon; then we focus the attention on the comparison between the phenomenology of self-excited and wind induced unsteady forces. Results show the effectiveness of the distributed representation in highlighting similarities and discrepancies between different wind–bridge interactions. The distributed representation results to be an interesting tool to perform the optimization of the aeroelastic performances of decks and to improve nonlinear models for the dynamic response of bridges in turbulent wind.