Wind Tunnel and CFD Study on Identification of Flutter Derivatives of a Long‐Span Self‐Anchored Suspension Bridge

Abstract

Abstract:  The Sanchaji Bridge with a main span of 328 m, located in Changsha City across Xiangjiang River, is one of the longest self‐anchored suspension bridges completed in China. This article presents the results from a combined wind tunnel and CFD (computational fluid dynamics) study on identification of flutter derivatives of the bridge deck. Based on the Covariance Block Hankel Matrix (CBHM) algorithm in time domain, sectional model wind tunnel tests are conducted in smooth flow to recover modal parameters and to further identify flutter derivatives from free‐decay vibration records. On the other hand, based on the ALE (Arbitrary Lagrangian Eulerian) description and a second‐order projection algorithm, the CFD study uses the FVM (Finite Volume Method) on staggered grids and a forced vibration manner of the bridge deck to evaluate the flow field around the bridge deck. With the obtained aerodynamic forces acting on the bridge deck, flutter derivatives can be evaluated based on system identification. Finally, both of the suggested methods are applied to identification of flutter derivatives of the bridge deck of the Sanchaji Bridge. The results of the present methods have the same trends with Theodorsen analytical solutions, while the results from the CFD study compare well with those from the wind tunnel test. The agreement on the present results suggests that the aeroelastic phenomenon of bridge decks with sharp edges does not appear sensitive to the Re number and turbulence modeling.