The main cables of suspension bridges show various cross-sectional shapes with the evolution of construction phases, and they may suffer from severe galloping at certain conditions. The aim of this work is to provide a convenient tool for predicting the critical condition and galloping amplitude of main cables, and to explore the in-depth driving mechanism of nonlinear galloping. Firstly, a numerical scheme of fluid–structure interaction (FSI) was developed to predict the galloping performance of main cables, and the numerical results of both critical conditions and vibration amplitude of galloping were compared to those of wind tunnel tests. The validated computational scheme was then used to investigate the driving mechanism of nonlinear galloping from the perspectives of nonlinear aerodynamic damping and work of aerodynamic lift. Moreover, the amplitude dependencies of unsteady and nonlinear aerodynamic lift were studied. It is found that the hysteresis of the flow with respect to the motion of the main cable is an important reason responsible for the nonnegligible unsteadiness in aerodynamic lift. Remarkable multiple-frequency components of aerodynamic lift emerged at large vibration amplitude, which were caused by the variation of instantaneous relative wind incidence angle for main cable in oscillation. Low-order harmonic components of aerodynamic lift at small vibration amplitude were the trigger of galloping, while the high-order components which contribute negative work at large vibration amplitude were responsible for the nonlinear aerodynamic damping and limited cycle oscillation. Unsteady characteristics of aerodynamic lift were the main cause for the variation of work proportions between different order harmonic components.

悬索桥的主要电缆随着施工阶段的发展而呈现出各种横截面形状，并且在某些条件下可能会遭受严重的疾驰。这项工作的目的是提供一个方便的工具来预测主电缆的临界条件和舞动幅度，并探讨非线性舞动的深入驱动机理。首先，建立了一种流固耦合数值模型来预测主缆的舞动性能，并将关键条件和舞动振动幅度的数值结果与风洞试验进行了比较。然后从非线性气动阻尼和气动升力功的角度出发，使用经过验证的计算方案来研究非线性奔腾的驱动机理。此外，研究了非定常和非线性气动升力的幅度依赖性。已经发现，相对于主缆线的运动的滞后现象是造成气动升力不可忽略的重要原因。气动升力的显着多频分量在大振幅下出现，这是由于主电缆在振荡中的瞬时相对风入射角的变化引起的。气动升程在低振幅时的低阶谐波分量是奔腾的触发，而在大振幅时对负功起负作用的高阶分量是非线性气动阻尼和有限周期振荡的原因。