Structural Analysis Of All The Cables Replacement Of Long-span Cable-stayed-suspension Pipeline Bridge

With the rapid development of pipeline transportation in China,the cable-stayedsuspension cooperation system has been gradually applied to large-span pipeline transportation projects.As the cable-bearing bridge,due to the early improper maintenance and the harsh environment,serious cable corrosion problems will inevitably occur after years of operation.The replacement of the cable is imperative to ensure the safe operation of the bridge.Although some scholars have carried out relevant research on the cable-replacement engineering of the cable-stayed bridge,so far,there have been few systematic studies on the replacement of the suspension cable.Moreover,the structural performance of the pipe bridge is different from that of the highway bridge.Combined with the cable replacement engineering of the Wei Jing pipeline bridge spanning Han River,this paper has studied the cable replacement structural analysis of the long-span high flexibility cable-stayed-suspension pipeline bridge.The main contents and conclusions are as follows:(1)Discuss the cooperation pattern,structural form and characteristics of the cable-stayed-suspension system bridge.The replacement examples of cable-stayed bridges and suspension bridges and the research status of cable-replacement engineering are summarized,the purpose and significance of this paper are clarified.Combining with the engineering background,summarize the structural characteristics of the cable-stayed-suspension pipeline bridge.(2)According to the structural characteristics and disease conditions of the pipeline bridge,the spatial finite element model is established to accurately simulate the actual stress state of the bridge before the cable replacement.The mechanical properties of cable-stayed-suspension bridge is studied,then initial state analysis is carried out.The results show that the stay cable dominates and the suspension system plays an auxiliary role in the cable-stayed suspension cooperation system,the beam of the pipeline bridge is mainly bearing axial loads.The overall distribution of the whole bridge cable is uneven,and some of the cable tensions are too large,which deviates greatly from the reasonable bridge state.(3)Combined with the characteristics of the pipeline bridge,the construction process of replacing all the cables of the pipe bridge is studied and discussed under the premise of not interrupting the oil transfer.The replacement of the suspension system is proposed by first installing a new suspension system and then removing the old main cable and sling.The replacement of the stay cable adopts a temporary cable to carry out the transition of the old and the new stay cable.(4)Based on the initial state model,the suspension system replacement process of the pipeline bridge is simulated to analyze the Stress and deformation of the structure.The installation stage the new main cable is the most dangerous,The internal force of the cable stayed adjacent to tower root increased significantly.And the proportion of load assumed by the new suspension system in the cooperative system increases.Stress and displacement of the pipeline are concentrated in the suspension section because of the smaller rigid.There is a problem of discontinuity in the deformation of the main beam of the cable-stayed cable transition section.The internal forces,deformations and stresses of the pipe bridge at this stage meet the construction safety requirements.(5)The simulation analysis of the cable-stayed cable replacement process is carried out to study the stress state of the structure at this stage.The results show that due to the auxiliary action of the temporary cable,the internal force of the whole bridge changes little,and the deformation and stress of the pipeline bridge meet the requirements.It shows that the temporary cable has played the role of replacing the S1 cable,and it is feasible to use the temporary cable to carry out the replacement of the old and new cable stays.But the stress of the main beam at this stage is dangerous,so control is required during construction.