Study Of The Steel Box Girder Of Longjiang Bridge Welding Timing And Sequence During The Installation Process

A long-span suspension bridge's main component stiffness,include the main cable,suspender and stiffening girder,is large.Suspension bridge possess a significant change of geometry in the construction,we often encountered more problems that the difficult stiffening girder connection,the poor wind stability,the long construction period,and a lot of welding stress.It is necessary to correctly simulate the stiffening girder of temporary connection,and choose reasonable hoisting beam sections in order,meanwhile,we need to predict the implementation of the timing and sequence of welded steel box girder in the design and construction of long-span suspension bridges.In this paper,the Longjiang large suspension bridge,at Yunnan,as the engineering background,based on the structure type and the construction condition of the stiffening girder.We use the finite element analysis software MIDAS/CIVIL,about bridge structure,to establish the calculation model with two different stiffening girder erection scheme.The hoisting process of steel box girder is analyzed accurately,and the internal force of the structure and the shape of the steel box girder are calculated.Combined with the construction condition of hoisting and welding of stiffening girder,we need to further explore the stiffening girder hoisting after welding,and the rationalization proposals,Longjiang bridge steel box girder of girth welding timing and sequence,are put forward.In this paper,the main work as follows:(1)The common construction methods about long-span suspension bridge with steel stiffening girder are introduced,for example,the erection of deck crane,the erection of cable crane,the erection of rail cable girder,and the erection of bridge deck crane.According to the stiffening beam with different structure types and construction conditions,we determined the most suitable erection method of hoisting Longjiang bridge girder.(2)The different stiffening girder erection sequences would be developed,taken two erection sequence that from the cross direction on both sides to tower and from the tower began to the mid span.Considering the construction condition and hoisting method,we separately formulated the order of hoisting stiffening girder about longjiang bridge.According to the different designs of stiffening girder,we use the finite element analysis software MIDAS/CIVIL to establish the spatial finite element model ofLongjiang bridge.We would analyze,the opening range between the adjacent beam segment margin of hoisting steel box stiffening girder in each stage,the shape of main cable and internal forces changes,the change of axial internal forces between the stiffening girders,and the shape change of stiffening girder erection.(3)Focuses on the application of temporary hinge method in hoisting steel box stiffening girder,and they were used to analyze the line changes and the sling tension in the process of hoisting stiffening girder between the temporary hinge method and the rigid connection method.(4)The construction conditions of hoisting and welding stiffening girders would be analyzed.By comparing with the detailed numerical analysis of the linear change of lifting stiffening girder and the opening width change between the adjacent sections,we discussed that the issues of welding stiffening girder after hoisting,and put forward some reasonable suggestions of the welding time and the welding sequence about Longjiang bridge stiffening girder.