Structural Analysis And Construction Technology Of Cable Replacement Of Earth-anchored Concrete Cable-stayed Bridge

Cable corrosion will inevitably occur due to several reasons,such as the imperfect protection technology,the poor construction quality,and the improper maintenance of stay cable.After several years of operation,the cable-stayed bridges have to change cables to ensure the safety and their continuing operation.The key of cable replacement process is to synchronously control the parameters such as the cable force,deflection and stress.And there are relatively few researches on cable replacement in recent studies.Therefore,based on the cable replacement and maintenance project in an earth-anchored concrete cable-stayed bridge,Yunxian Hanjiang Bridge,this paper mainly locates the researches on the analysis of the cable replacement structure and the construction technology,which provides reference for the cable replacement of similar bridges in the future.The specific works are as follows:(1)The existing optimization theory of cable-replacement is analyzed.Combined the theory with the characteristics of the earth-anchored cable-stayed bridge,a method of improving the alignment of the bridge deck and main tower and the internal force of the main beam through cable-replacement technology are put forward by applying the minimum complementary energy.(2)Considering the nonlinear factors of cable-stayed bridge,the analysis model of earth-anchored cable-stayed bridge is established by using finite element software MIDAS/CIVIL,and in order to make bridge deck alignment and cable force of the model close to the actual structure,some technical means are applied to adjust the model,such as the adjustment of cable force,the imposition of load,etc.The different cable replacement conditions are simulated considering of the construction environment and the influence of temperature that a reasonable order of cable replacement is obtained by analyzing the safety of structure under different cases with respect to the redistribution of cable force and the alignment and stress change of main girder during the process of cable replacement.(3)None-axial-force hinge as a new technology used in the earth-anchored cable-stayed bridge that it is stressed in a complicated situation.A none-axial-force hinge solid model is proposed by finite element software ABAQUS.The characteristics and safety of the none-axial-force hinge are analyzed during the process of cable replacement based on the bridge model of MIDAS/CIVIL and considering the actual conditions of the cable replacement.(4)Based on the cable replacement construction,the construction monitoring data and the numerical results as Yunxian Hanjiang Bridge a case study,the construction technology of the cable replacement project of the earth-anchored cable stayed bridge is summarized and discussed.The results show that the short cables should be replaced following the long ones during the cable replacement of Yunxian Hanjiang Bridge.A construction order is adopted that two cables are replaced symmetrically in the single tower and successively and anti-symmetrically in the twin towers in a time during the unload of long cables.Another construction order is adopted that four cables are replaced symmetrically in the single tower and anti-symmetrically in the twin towers in a time during the unload of the other cables.None-axial-force hinge is safe during the whole process of cable replacement,however the effect of temperature on the force of it can not be neglected.The structural stress state of the bridge after cable replacement is improved and satisfy the safety need of the bridge.