Corrosion fatigue analysis of stay cables under combined loads of random traffic and wind

摘要

After the failure of their protection system, stay cables may subject to environmental corrosion and fatigue loading simultaneously. To study the cable safety during the bridge service life, a general framework was proposed in this paper to estimate the corrosion fatigue life of stay cables under the combined action of random traffic and wind. A simplified approach integrated with the wind-vehicle-bridge system was first introduced to calculate the stress time histories of the stay cables. Based on the traffic data and wind records at the bridge site, the procedure to predict the stress ranges of bridges in service was applied to the North Channel Bridge (NCB) of Hangzhou Bay Bridge as an example and the most critical stay cable was determined. The time-variant corrosion fatigue model of the stay cable was then established considering the deterioration of the steel wires and the corrosion distribution inside the cable. Three levels of corrosion rates (low, medium, and high) were also defined in the model for different environmental conditions, and the corrosion fatigue analysis of the stay cable was finally conducted. The results show that the coupled effects of corrosion and fatigue greatly reduce the lifetime of the wire, and the fatigue resistance of the stay cable in the bridge service life is insufficient under certain corrosion rates.