Nonlinear flutter control of a long-span closed-box girder bridge with vertical stabilizers subjected to various turbulence flows

Abstract

This study investigated the influence of different heights of upward vertical central stabilizers (UVCS) in flutter performance of long-span suspension bridges through developing nonlinear three-dimensional Finite Element (FE) bridge model using large-deformation beam elements with 14 degrees of freedom (DOFs). Using Runyang Yangtze River Bridge as a case study, the developed FE model firstly incorporates a nonlinear aerodynamic force model of the 2D closed-box girder with various UVCS, and the model predicted critical flutter wind velocities of the bridges were validated using wind tunnel testing results. A series of parametric studies were then carried out to study the aerodynamic performance of the bridge under different vertical intensities of incoming turbulence flow (Iw) by developing multi-variable non-stationary stochastic wind fields. The numerical results show that the installation of UVCS could not only modify from first-order to second-order symmetrical vertical oscillation configuration, but also change the coupled oscillation from the stable condition to the unstable limit cycle of flutter divergence. Furthermore, UVCS mainly governs the vertical DOF partication in the coupled bending-torsional oscillation of the bridge, while the increase of the height of UVCS results in a higher critical flutter wind velocity but a lower torsional frequency, particularly for the 1.1 m UVCS when Iw is over 2.84%.