Fatigue Evaluation of Cable-stayed Bridge Steel Deck Based on Predicted Traffic Flow Growth

Statistical analysis of the measured traffic flow over the Nanjing No. 3 Yangtze River Bridge from 2006 to 2010 was conducted. The predictions of traffic flow growth model were established. Random traffic flow was simulated by Monte-Carlo method to study dynamic impact effects under vehicle load. Considering the dynamic impact effects and wheel mark transverse distribution, the nominal stress, hot spot stress, and notch stress in the steel bridge deck details was calculated. The results of three evaluation method were compared. Suggestions of analysis models and fatigue evaluation were proposed. The study showed that the maximum magnification coefficient of the dynamic impact effects was close to the suggestion of BS5400. The simplified model could be used to analysis local stress ignoring the superimposed effects of longitudinal multi-vehicles. The evaluated service life under hot spot stress was comparatively longer. In terms of bridge safety and convenience, notch stress for the roof weld and U rib-to-diaphragm weld and hot spot stress for diaphragm arc gap were more suitable for fatigue evaluation. And the roof weld was most likely to crack.