Design And Analysis Of Semi-closeed Composite Steel Box Girder Cable-stayed Bridge

Semi-closed steel box composite girder cable-stayed bridge is a new kind of structural forms of bridge, based on the traditional closed steel box composite girder cable-stayed bridge, which is used for the first time on the project of Jiaojiang2nd Bridge.This paper takes the main bridge of Jiaojiang2nd Bridge as the project background, reviews briefly the research status of cable-stayed bridge at home and abroad, and summarizes the characteristics of this cable-stayed bridge and its design gist. This paper discusses the bridge site selection and the concept of bridge type scheme, based on the analysis and study of the background information of many factors including local climate, hydrology, engineering geology, ship transportation. The paper puts forward four possible bridge types, containing twin towers cable-stayed bridge,3towers partial cable-stayed bridge, single span suspension bridge, medium bearing arch bridge for technical and economic comparison, considering of the safety of ship collision, force structure, difficulty of construction, wind resistance, the impact on the channel, the duration, the landscape and the cost. Finally, the bridge type scheme of the main bridge was confirmed as twin towers cable-stayed bridge, which was5spans continuous floating system with semi-closed steel box composite girder (70+140+480+140+70) m, and further research on this scheme was carried out. By using static analysis and aerodynamic parameters analysis, this paper compares the schemes of different combinations of beam column and the construction details including the tower, girder and stay cable. Besides, based on the research on the modeling of the whole bridge, the paper puts forward the main load cases of its construction and operation and analysis of the factors including the combinations of displacement, internal force. The results show that semi-closed steel box composite girder cable-stayed bridge has many advantages, containing good wind stability, low cost, convenient construction and easy conservation.