Numerical investigation on the nonlinear flutter behaviors of a π-shaped sectional bridge deck

Abstract

Nonlinear flutter behaviors of a π-shaped sectional bridge deck are investigated numerically, focusing on the effects on the post-flutter limit cycle oscillation (LCO) amplitudes caused by various nonlinearities, including aeroelastic, structural damping, and geometric nonlinearity. The Multi-stage indicial functions (IFs) are adapted to describe the nonlinear aeroelastic effects in time-domain, which necessitate amplitude-dependent aeroelastic model parameters. The motion amplitude-dependent parameters are mainly extracted numerically with computational fluid dynamics (CFD) method and partially examined by experimentally extracted results. The CFD-based parameters turn out to be satisfactory compared with experimental results. Finally, the flutter thresholds and post-flutter limit cycle oscillations are simulated using the present time-domain multi-stage indicial functions model. The numerical results show that introduction of any one kind of nonlinearity (aeroelastic, structural damping, or geometric) in the numerical procedure can lead to LCO. These three kinds of nonlinearity are compared in detail in terms of the effects they have on the post-flutter LCO amplitude. It turns out that the damping nonlinearity, for the case concerned in this work, is the most important factor that determines the post-flutter LCO amplitude and the flutter onset wind speed as well. The time-domain multi-stage indicial functions procedure adopted in this work can serve as an efficient solving strategy to obtain nonlinear post-flutter performances of long-span bridges.