Condition Assessment of Grouped Cable Forces of Cable-Stayed Bridge Using Deflection Data

The stress state of the cable group in a cable-stayed bridge directly affects the overall performance. A novel method for assessing grouped cable forces using deflection data is proposed in this article. Firstly, a simplified equation between the variation in cable forces and the girder deflection was built according to the geometric relationship of the deformation. Secondly, the threshold value of cable force change rate for a single cable can be determined by the proposed theoretical equation and the deflection limit in the specification. On this basis, the evaluation standard of single cable force of piecewise linear mode was established. Thirdly, considering the uniform and non-uniform changes in the cable forces, the condition assessment method of grouped cable forces was established based on the variable weight synthesis method and the gray correlation degree theory. Finally, a case study of a real bridge was undertaken. The results show that the case data validate the correctness of the proposed theoretical equation. The threshold of change rate for long cable is 30%. Six-year assessment scores of grouped cables are generally decreasing, which also reflects the development of other component defects from the side.