Optimization Of Hanger Tension And Analysis Of Construction Control For Single Tower Self-anchored Suspension Bridge

The self-anchored suspension bridge has the characteristics of graceful structure,strong adaptability to terrain and superior economic performance,which is increasingly favored by the engineering community,especially in the medium and small span bridges in the city with strong competitiveness.The unique structural system of the self-anchored suspension bridge makes the structural stress and construction method very different from the land-anchored suspension bridge.The construction control of self-anchored suspension bridge becomes particularly complicated because of the construction method of constructing girder before erecting cable.Based on the Jiahe Bridge in Yantai City,Shandong Province as the engineering background,this paper uses the analytical method to carry out in-depth calculation and analysis of the main cable geometric shape of the self-anchored suspension bridge and through the finite element software to draft the hanger tension schemes of the bridge,the optimal tension scheme is selected by comparison analysis.The research content of this paper mainly includes the following aspects:(1)Based on the theory of segmental catenary,the calculating program of the completed cable line shape of Jiahe Bridge was compiled by using Matlab software,and the line shape,the unstressed length and the internal force of the main cable of Jiahe Bridge were calculated.Based on the catenary theory and the principle of unstressed cable length invariance,the unloaded cable line shape was programmed and calculated,the analytical equation of it was determined,then the coordinates of the suspension points of the unload cable were calculated based on the principle that the unstressed length of the main cables of each segment remains constant in the completed bridge state and the free cable state.(2)Through the finite element analysis software Midas/Civil,the primary completed bridge model of the whole bridge was established to solve the unstressed length and internal force of the main cable and the hanger internal forces under the state of the completed bridge,and the calculation results were in good agreement with the theoretical value,which verified the correctness of the primary completed bridge model.The unloaded cable model was obtained by the inverted disassembly of the completed bridge model,and the analysis of the unloaded cable shape obtained in the model was compared with the analytical solution of the unloaded cable line shape,the calculation results of the two are in good agreement,which show the accuracy of the unloaded cable model and provides a more accurate model basis for formal analysis.(3)The analytical program was used to quantitatively analyze the influence of unstressed cable length,span variation and compression of the completed bridge on the shape of the unloaded cable,which is helpful to better analyze the causes of errors in the process of cable wire strand erection,and to quickly and accurately correct the shape of the main cable.In the erection stage of the datum cable,the line shape of the reference strand was controlled by controlling the elevation of the mid-span control point.After the adjustment of the datum cable was completed,it's continuously stable for 3 days to ensure the accuracy of the erection.(4)Five kinds of hanger tension schemes were worked out through forward analysis in the finite element model.The optimal tension scheme was compared and selected in terms of the tension batch,the number of connecting rods and jacks,the maximum tension force and the smoothness of the main cable,and the optimal suspension cable tension scheme was selected as the system transformation scheme of Jiahe Bridge,which served as a system conversion scheme for the Jiahe Bridge.(5)The construction control method in the process of hanger tensioning of Jiahe Bridge was elaborated in detail,that's the first round of tension was mainly controlled by marking line method and the second round of tension is controlled by the exposed amount of anchor cup and the tension force of hanger.The bridge construction was monitored strictly during the process of hanger tension,and the construction was guided and analyzed by the measured data,which could also ensure the safety of the bridge in the system transformation process.