Study On Key Structure And Mechanical Behavior Of Asymmetric Single Tower Cable-stayed Bridge On Process Of Rotation Construction

After several decades of development,the rotation construction has become a typical construction method of bridge,which has been widely used in bridges on mountain valleys,torrents,busy navigation,busy city highway,railway cross line etc..It is a highly technical bridge construction method,but there are great risks in the construction process.In the process of turning,the cable-stayed bridge is subjected to various factors,which makes the cable stayed bridge under different structural system.Relying on the asymmetrical single tower cable-stayed bridge at Xiangyang East and West axis railway,this paper tries to study on key structure and mechanical behavior of asymmetric single tower cable-stayed bridge on process of rotation construction from the following aspects:Firstly,Combined with the rotation construction methods and structural system characteristics of asymmetrical single tower cable-stayed bridge,this paper optimizes the dead load cable tension of the bridge at Xiangyang according to the unknown load factor method based on influence matrix method,which is provided by the software Midas Civil,to obtain Reasonable cable force and initial tension of the bridge.Then,the stress analysis of the project is carried out under different working conditions.The results show that the stress state of each stage of the project is in accordance with the requirements of the code.Secondly,After analyzing the key structure-the portal pier,this paper proposed two types of structural scheme for the bridge at Xiangyang.Combining the force analysis of the two types of structural scheme,this paper concluded that internal force and deformation of the structure is more reasonable to use circular arc chamfering at the junction between the pier and capping beam.Thirdly,Using finite element Software-Ansys to analyze the influence of distortion effect from filled spandrel diaphragm plate and truss type diaphragm plate on steel box girder of cable-stayed bridge,the results showed that the distortion of the steel box girder is reduced by 26.94%,and the distortion displacement is reduced by 59.40%,Compared with truss type diaphragm;Compared with the truss diaphragm,the distortion ratio of the solid abdominal diaphragm is reduced by 91.36%?Therefore,the filled spandrel diaphragm plates have more advantages than the truss type diaphragm plates in suppressing the distortion effects of the steel box girders.Finally,When a temporary consolidation is changed into the permanent consolidation,the prestressing force is released from the steel beam in portal pier,which can make the stress on the capping beam more well-distributed and reasonable,to achieve the aim of the optimization of prestressed steel beam in the process of conversion of gantry type pier system.When the bridge used permanent consolidation,analyzing the stress state and 3 kinds of prestress released by steel beam scheme of portal pier,this paper found that loading the force of jacking lift hierarchically while releasing of prestressed steel beam tension structure could reduce the range of stress and displacement and ensure the construction safety.