Fatigue Life Assessment of Key Fatigue Details of the Corroded Weathering-Steel Anchor Boxes of a Cable-Stayed Bridge

Abstract

In order to study the influence of corrosion on the fatigue life of weathering steel bridges, firstly the nominal stress method is employed to identify the key fatigue details of a typical weathering-steel anchor box of a cable-stayed bridge and then, a multi-scale refined finite-element model for the weathering-steel anchor box is established. The established fatigue-life assessment method for corroded weathering steel is extended to the multi-scale model, the remaining fatigue life for the fatigue details under corrosion are predicted, and the influence of the initial pit size on the fatigue life of weathering steel structures is analyzed. The research results show that corrosion pits can be equated to the introduction of initial cracks in the structure, and the remaining fatigue life for key fatigue details is calculated when the initial crack size is 1 mm, 2 mm, and 3 mm of the fatigue life when the initial crack size is 0 mm, with results of 20.3%, 12.7%, and 11.5%, respectively. Therefore, the research results show that the corrosion pits are equivalent to the introduction of initial cracks in the structure and, even if the initial crack size is small, the fatigue life of the structure is greatly reduced. The fatigue-life assessment method for corroded weathering-steel structures established in this paper is based on the finite element method and fracture mechanics, which offer universal applicability and generalizability and make up for the lack of a fatigue-life assessment method for corroded weathering-steel bridges in service.

Keywords

• weathering steel
• corrosion
• fatigue detail
• fatigue life
• assessment method