The Research On Construction Control Of Ring Type Extradosed Cable-stayed Bridge

Many novel bridge types have appeared with bridge technology rapidly developing. Extradosed cable-stayed bridge as a new combined structure has great development potential all over the world in recent years. The stiffness of the new bridge type is between rigid continuous beam bridge and flexible cable-stayed bridge. Extradosed cable-stayed bridge is characterized by low tower, firm girder and cable centralized. This new bridge type has the advantages of novel structure, long span ability, simple construction and economy compared to continuous beam bridge, and the advantages of convenient construction, saving material and high stiffness of main beam compared to cable-stayed bridge.Based on an extradosed cable-stayed bridge under construction, this paper studies the theory and methods of construction control of it. Numerical models of MIDAS/CIVL and ANSYS are built to conduct structure and parametrical analysis and cable force optimization. Based on the analysis results, some reference for later construction control of the extradosed cable-stayed bridge is provided in this paper.Firstly, according to the structural characteristics of extradosed cable-stayed bridge, the main content and methods of construction control are briefly introduced and the way of modeling the bridge components in finite element analysis is in detail described. Based on the Balihu bridge, a numerical model of MIDAS/CIVL considering all construction stages is built to investigate the changes of structure displacements, inner forces and cable force in the construction process. Then the performance of the bridge under service stage is analyzed. Considering the load combination effect of dead load, live load, temperature load and etc under finished stage, checking calculations are made on the bending, shearing and crack resistance for the bridge in ultimate limit state and serviceability limit state.Secondly, the dynamic performance and stability of the bridge under finished stage are analyzed through eigenvalue and buckling analysis. By changing the parameters of boundary conditions and stiffness of main tower, the influence of these parameters on the displacement of girder, inner forces and cable force is investigated. The mechanical characteristics of "ring type" main tower are discussed based on the software ANSYS and the concrete stresses in sensitive regions are analyzed locally under the most unfavorable load. Finally, considering the characteristics of Balihu bridge, the contents and methods of the bridge construction control is in detail introduced. Some conclusions are obtained after the contrast between the field test data and calculation data.