Flutter Characteristics of Thin Plate Sections for Aerodynamic Bridges

Abstract

A fundamental understanding of the flutter stabilization of streamlined box girders is of critical importance for ensuring the structural safety of superlong span bridges. This study systematically investigated the flutter characteristics of thin plate sections by performing theoretical analysis in conjunction with wind tunnel tests with the aim of evaluating the flutter mechanism of superlong-span bridges with streamlined box girders. From the results of a two-dimensional, two-degree-of-freedom (2D-2DOF) flutter analysis, it can be seen that with increases in ftorsion/fheaving, the aerodynamic damping part D of the torsion motion becomes more important and the level of participation level of heaving motion gradually decreases. Thus, the relationship between the structural torsional–heaving frequency ratios (ftorsion/fheaving) and the critical velocities of flutter can change with changes in the structural frequency ratio in different ways. Furthermore, the method of flutter energy analysis was used to investigate the components of energy input and energy dissipation, and the results show that the components associated with flutter derivatives A1* and A2* produce the maximum positive and negative energy inputs, respectively. The maximum energy dissipation has a strong correlation with the mechanical damping force. In addition, the measurements of flow field using particle image velocimetry (PIV) demonstrate that the scale of vortex streets becomes larger with increases in wind velocity, while the bobbing movements of the vortex streets could lead to the flutter instability of thin plates.