Vortex-induced vibration (VIV) is a major concern for long-span bridge decks, which may happen especially for closed-box girders under certain environmental wind conditions. Traditionally, sustained VIV is observed as long as the wind speed falls within the lock-in region in wind tunnel tests. However, structural vibration monitoring of long-span bridges has indicated that frequency of VIV events may exhibit a probabilistic pattern. This paper proposes an analytical framework to evaluate the probability of VIV occurrence. First, a nonlinear aeroelastic model with multi-stability limit cycles is used to simulate the bridge deck VIV response within the VIV-triggering wind conditions. The first structural dynamic equilibrium point is usually unstable; the bridge deck instantaneous oscillation amplitude, which is excited by external environmental loads, must exceed this fixed point to trigger the VIV event. The external environmental excitation applied on bridge can be identified from the deck vibration without VIV occurring, then the VIV occurrence probability can be evaluated by Fokker–Planck–Kolmogorov equation. This study utilizes the field measurement data from the Humen Bridge, on which VIV event occurred the first time after 23-year servicing period, because water-filled barriers were placed along the two edges of bridge deck. Afterwards, VIV occurred frequently for over one month. The bridge deck VIV occurrence probability is evaluated by combining environmental wind information, stochastic deck excitation magnitude and a nonlinear aeroelastic VIV model. The results suggest that the proposed methods can approximate the VIV occurrence probability in comparison with empirical estimations using field measurements.

涡激振动（VIV）是大跨桥面的一个主要问题，尤其是在某些环境风条件下的闭箱梁上可能会发生这种情况。传统上，只要风速落在风洞测试中的锁定区域内，就会观察到持续的 VIV。然而，大跨度桥梁的结构振动监测表明，VIV 事件的频率可能呈现出概率模式。本文提出了一个评估 VIV 发生概率的分析框架。首先，使用具有多稳定性极限循环的非线性气动弹性模型来模拟触发 VIV 的风条件下的桥面 VIV 响应。第一结构动态平衡点通常是不稳定的；由外部环境荷载激发的桥面瞬时振荡幅度必须超过该固定点才能触发 VIV 事件。施加在桥梁上的外部环境激励可以从不发生VIV的桥面振动中识别出来，然后可以通过Fokker-Planck-Kolmogorov方程评估VIV发生的概率。本研究利用了虎门大桥的现场测量数据，该大桥在使用23年后首次发生VIV事件，因为桥面两侧设置了充水屏障。此后，VIV频繁发生，持续1个多月。通过结合环境风信息、随机桥面激励强度和非线性气动弹性 VIV 模型来评估桥面 VIV 发生概率。结果表明，与使用现场测量的经验估计相比，所提出的方法可以近似 VIV 发生概率。通过结合环境风信息、随机桥面激励强度和非线性气动弹性 VIV 模型来评估桥面 VIV 发生概率。结果表明，与使用现场测量的经验估计相比，所提出的方法可以近似 VIV 发生概率。通过结合环境风信息、随机桥面激励强度和非线性气动弹性 VIV 模型来评估桥面 VIV 发生概率。结果表明，与使用现场测量的经验估计相比，所提出的方法可以近似 VIV 发生概率。