A Theoretical Study on the Cables Fatigue Life Quantitative Analysis Method of Cable Bridges

Based on the theory of fatigue fracture of metals, quantitative analysis method was proposed for fatigue strength of cables of cable bridges and conclusions were reached through analysis of calculation formula: the analysis method of stress fatigue life was able to consider the section dimensions of the cables, plasticity of the material and stress ration caused by external loads and other factors which affect the fatigue life. This analysis theory was correct which took into consideration of relatively overall factors and was a better way to analyze the cable fatigue life. Meanwhile, the design of fatigue strength of bridge cables should adopt the theoretical fatigue limit represented by equivalent nominal stress amplitude as the design value of fatigue strength of cable. The theory represented by equivalent nominal stress amplitude considered the influence of stress ratio on fatigue life of cables caused by external loads. Compared with traditional method of fatigue strength estimate, with sufficient theory basis and overall consideration of factors, the results of this method were more reliable.