Accurate fatigue life prediction facilitates the fatigue maintenance of steel bridges. Since Digital Twin can simulate the lifecycle for physical objects at various scales, this study aims to provide a Digital Twin-driven framework for non-deterministic fatigue life prediction of steel bridges. A probabilistic multiscale model was developed to depict the fatigue evolution throughout the bridge lifecycle. The small crack initiation period was well described by the modified Fine and Bhat model considering microstructure uncertainties. After obtaining the critical model parameter via crystal plastic finite element simulation, the modified model was further calibrated using the assumed historical fatigue data in Digital Twin database. Based on the initiated half-penny-shaped small crack, the small crack initiation period was connected to the macrocrack extension period. Given the uncertainties of macrocrack propagation, the Paris’ law with random growth parameters was adopted. The Bayesian inference of the growth parameters realized the real-time calibration of the macrocrack growth model using Markov chain Monte Carlo simulation. The feasibility of the proposed framework was demonstrated through fatigue tests on a segmental steel deck specimen with mixed-mode deformed U-rib to diaphragm welded joints. The results show that the predicted fatigue initiation life and residual fatigue life are in good agreement with the experimentally observed life results. In summary, the proposed framework enhances our understanding of the fatigue evolution mechanism throughout the bridge lifecycle and provides an entirely new approach to accurately predict the fatigue life of steel bridges under various sources of uncertainties.

准确的疲劳寿命预测有助于钢桥的疲劳维护。由于Digital Twin可以模拟各种规模的物理对象的生命周期，因此本研究旨在提供Digital Twin驱动的框架，用于非确定性的钢桥疲劳寿命预测。建立了概率多尺度模型来描述整个桥梁生命周期中的疲劳演化。考虑到微观结构的不确定性，改进的Fine和Bhat模型很好地描述了小裂纹的萌生期。通过结晶塑性有限元模拟获得临界模型参数后，使用数字孪生数据库中假定的历史疲劳数据对修正后的模型进行进一步校准。基于引发的半便士形小裂纹，小裂纹萌生期与大裂纹扩展期有关。考虑到大裂纹扩展的不确定性，采用了具有随机增长参数的巴黎定律。增长参数的贝叶斯推断使用马尔可夫链蒙特卡洛模拟实现了宏观裂纹增长模型的实时校准。通过对分段式U形肋到膜片式焊接缝进行混合模式变形的分段钢甲板试件进行疲劳测试，证明了所提出框架的可行性。结果表明，预测的疲劳起始寿命和残余疲劳寿命与实验观察到的寿命结果吻合良好。总之，