Nonlinear behaviors of the flutter occurrences for a twin-box girder bridge with passive countermeasures

摘要

The flutter control effectiveness of passive aerodynamic countermeasures for long-span bridges is much dependent on the configuration of these countermeasures. The present study investigated the nonlinear flutter behaviors of a twin-box girder bridge with application of four common types of countermeasures, i.e. upward vertical central stabilizers (UVCS), downward vertical central stabilizers (DVCS), external guide vanes (EGV) and internal guide vanes (IGV). Particularly, the displacement bifurcation, power spectrums, oscillation configurations and failure modes of the bridge with these four countermeasures were systematically studied using a nonlinear aerodynamic force model (NAFM). The model predications were validated using wind tunnel testing data. It shows that the oscillation configuration of the bridge without countermeasures is an anti-symmetrical bending-torsional coupled motion with a hard-flutter phenomenon. Furthermore, the installation of 0.4 h/H UVCS or DVCS could lead to a relatively higher critical flutter wind velocity through prolonging the limit cycle oscillation of soft flutter, especially for 0.4 h/H UVCS. In addition, the flutter performance of the bridge with EGV dominated by the torsional DOF in soft flutter was superior to that with IGV dominated by the vertical DOF in soft flutter. (C) 2019 Elsevier Ltd. All rights reserved.