Simulation of Vortex-Induced Vibration of Long-Span Bridges: A Nonlinear Normal Mode Approach

Due to the lack of analytic technique for simulating the vortex-induced vibration (VIV) of long-span bridges, a combination of the VIV semi-empirical model with the structural equation of motion is widely employed to calculate the responses of bridge structures. However, the applicability of this method has seldom been investigated before. In this study, the theoretical defects of the conventional combination strategy (i.e. the finite element procedure or the linear normal mode procedure, LNM) are first discussed, a more theoretically reliable approach (the nonlinear norm mode approach, NNM) is then proposed, and the closed-form expression for the NNM of the VIV system is derived. The accuracy of the proposed method is further illustrated by two case studies. This new approach offers a theoretically reliable tool for analyzing the VIV of long-span bridges. It can also be applied to the process of VIV fatigue analysis or control strategy optimization.