A form of aerodynamic admittance for use in bridge aeroelastic analysis

This paper returns to, and addresses, the question of identifying the natur e of aerodynamic admittance in relation to extended-span bridges in wind. T heoretical formulations for the sectional aerodynamic forces acting upon th e deck girder of a long-span bridge have conventionally been composed of th e sum of two kinds of terms: aeroelastic terms and buffeting terms. The for mer employ frequency-dependent coefficients ("flutter derivatives") associa ted with sinusoidal displacements of the structure, while the latter have t ypically been expressed in quasi-static terms with fixed lift, drag and mom ent coefficients. This inconsistency of formulation has required that at so me point the buffeting terms, functions of gust velocity, be adjusted to a more compatible form through the introduction of the so-called aerodynamic admittance factors that are frequency-dependent. The present paper identifi es a form of these several section-force factors as functions of the flutte r derivatives themselves. (C) 1999 Academic Press.