Critical Flutter Wind Velocity Analysis of Long-Span Arch Bridge Featuring Single Arch and Deck System Consisting of Double Semi-Separated Box Girders with Inclined Webs
Critical Flutter Wind Velocity Analysis of Long-Span Arch Bridge Featuring Single Arch and Deck System Consisting of Double Semi-Separated Box Girders with Inclined Webs
This study focuses on the flutter performance of the long-span bridge with low torsion-bending frequency ratio.Based on an existing long-span arch bridge featuring its single arch that spans 180 m,the deck system consisting of double semi-separated steel box girders with inclined webs and a low torsion-bending frequency ratio approximating 1.0,the critical flutter wind velocities were analyzed.The dynamic property of the bridge was simulated to calculate the flutter stability of the bridge.Three groups of formulae to predict the critical flutter wind velocities of ideal flat plates recommended in Wind-Resistant Design Specification for Highway Bridges(JTG/T 3360-01-2018)were compared.Based on the critical flutter wind velocities of ideal flat plates by the Scanlan semi-inverse solution,considering the geometry of the deck and the correction factor of wind attack angles,the ranges of the critical flutter wind velocities are determined.Furthermore,the forced vibrations were numerically simulated to identity flutter derivatives to obtain the accurate critical flutter wind velocities.Consequently,the geometry and coefficients of wind attack angles of the double semi-separated box girders were calculated.As per the analysis,the bridge exhibits low torsion-bending frequency ratios,and the flutter stability is lower than the long-span arch bridges with a main span of 500 m.For the formulae to predict the critical flutter wind velocities of the ideal flat plate recommended by the specification,the results reveal great disparity at the small torsion-bending frequency ratio.The geometry correction factor of the double semi-separated box girder is smaller than that of the double separated box girders,but greater than the PK section girder and the box girder with inclined webs,while the correction factors of the wind attack angles are bigger than the other three types of main girder.
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