Study On Rational Construction State And Optimization Of Bridge-completing Cable Tensions For Cable-stayed Bridges

Cable-stayed bridge is a kind of highly redundant and complicated structure, which is composed of the tower, girder and cable, the cable only stands the pulling force, the tower and the girder is pressure-curved component that primarily take on pressure, and the cable tensions have greatly tremendous influence on the distribution of internal stress in the structure system and they have become the key to control the internal forces of the whole bridge.How to determine and optimize the cable tensions in order to make the cable-stayed bridge in good condition, and how to determine the rational construction state——thereby the construction to achieve the target of rational finished dead load state in design, have become one of the key problems about design and construction technology of cable-stayed bridge,At present, many scholars at home and abroad have brought forward a lot of methods to determine rational cable tensions of cable-stayed bridge, but these methods have their focus and limitations.On the basis of previous studies, this paper put forward a comprehensive method which combined use of the Minimum Bending Energy Method, the Stress-Balance Method, the Influence Matrix Method and two Planning Theory to determine and optimize the cable tensions, then, took the actual project as an example,established a cable tension optimizing model for the cable-stayed bridge, introduced the optimization step of comprehensive method on PC cable-stayed bridge, and the stress performance had been improved through the optimization of the rational cable tensions, which showed that this method had a certain application value.Then, the forward analysis model of the cable-stayed bridge according to the sequence of construction was established. With the optimal cable tensions as the goal, rational construction state of the cable-stayed bridge was determined by the Forward Iteration Method, and initial tensions was obtained. The stress and deformation of the structure through construction process were analyzed, we found that the structural was in high safety during the process of construction, then pointed out the site and stage which need to be focused on monitoring during the construction.Finally, the static and dynamic behavior at operation stage was analyzed, we clarified the stress and deformation of the structure, obtained the vibration characteristics of the bridge, validated some common features of cable-stayed bridge about structure vibration characteristics. The parametric sensitivity analysis of the cable-stayed bridge was carried out and some useful conclusions were obtained.