Research Of Partial Cable Replacement Of Cable-stayed Bridge In Complex Traffic Conditions

Cable-stayed bridge is applicated worldwidely since 1970 s, it has become one of the most common bridges becauce of its rapid construction in recent 40 years. However, cable-stayed bridge would face more and more problems after several years of operation, and the worst is cable’s corrosion and damage. Cable is the main component of cable-stayed bridge to bear load. If the corroded cables can’t be replaced in time, the structure may be in danger. Traffic is always closed when replacing cables, thus can ensure safety of the bridge. However, it has caused more and more troubles to people’s travelling and traffic fluent with develop of transportation, and the puzzle is more critical especially for those bridges that located at pivotal sites. When replacing cables how to guarantee the safety of structure and maintain smooth traffic turn into an issue of social concern. Based on Sha Ximiao Jialing River Bridge cable replacement project, this paper researches how to replace partial cables of cable-stayed bridge in complex traffic conditions. The main contents are as follows:Firstly, considering that shock effect caused by vehicle would bring about bridge vibrating when traffic is open, this paper summarizes common construction monitoring methods of cable replacement and characteristics of cable replacement in complex traffic conditions, to analyze applicability of all the methods for the bridge’s cable replacement in complicated traffic conditions.Secondly, control conditions of force structure and the proposed amount in the process of cable replacement is put forward in this paper. It had better enhanc cable’s safety factors in linking with its damage on the basis of specification. Beam deformation must meet specification requirements, at the same time it should be less than the theoretical calculation of the deformation under the design live load. It is good to control beam stress within envelope of stress value in serviceability limit state.Thirdly, this paper establishes finite element model by supposing that the bridge is in closed condition, to research the influence of different cable replacement plans on bridge structure and plans’ feasibility by calculating and analyzing cable force, beam stress and beam deformation in different replacement order and number.Fourthly, vehicle load is simulated based on traffic organization plan acted on the bridge. The result shows that cables’ force of Hechuan shore upstream side and Chongqing shore downstream side have nothing to do with cable replacement on downstream side of Hechuan shore. Feasibility of cable replacement program and traffic organization plan are checked by analyzing cable force, beam stress and deformation in the load state that traffic organization plan allows.Finally, cable replacement construction is monitored effectively by measuring cable force, deck linear, beam stress and tower deviation exactly. All the results indicate that structure force and deck linear after cable replacement meet the design requirements. It can provide a reference for similar projects that construction monitoring support and guide cable replacement effectively in open traffic conditions.