| Cable-stayed bridge is a kind of high-order statically indeterminate system structure.the pylon is the main load-bearing component,and it is also the key part of the control design and construction of the long-span cable-stayed bridge.The span of the cable-stayed bridge is getting larger and larger,and the requirements for the control accuracy and construction accuracy of the tower are also increasing.For the lower tower column where the shear deformation effect is obvious,how to calculate the shear effect relatively accurately becomes a key issue.the pylon is subjected to various external forces during the construction process,and the deformation and stress distribution are obviously spatial,so the stress of the tower structure is more complicated.This paper takes the Jiayu Yangtze River Highway Bridge as the engineering background,and conducts stress analysis and construction control research of the cable tower.(1)The theory and method of rational design state,geometrical nonlinearity and concrete shrinkage and creep in the calculation of cable-stayed bridges is introduced.The finite element software BDCMS is used to analyze the full bridge of Jiayu Bridge to get the full bridge force and displacement conditions.The cable force and the bearing reaction force under a reasonable bridge condition provide the basis for the structural analysis of the 2D plane program tower.(2)Based on the I-shaped model to calculate the shear heterogeneity,the influence of shear deformation is incorporated into the finite element program BDCMS.The accuracy of this method was verified and compared with the traditional finite element software midas/civil.Aiming at the problem that the external tensile stress of the lower column after the first prestressing is too large,the force of the tower under this method is analyzed by adopting the technology of reducing the first prestressed tension beam and adopting the lower crossbar at low temperature.(3)Considering the influence of shear deformation,the force analysis of the north tower of Jiayu Yangtze River Highway Bridge and its construction control are carried out.First of all,according to the construction program to determine the optimal supporting force of the active cross brace,the research on the temperature and weld shrinkage on the supporting force,the active crossbar installation for engineering control;according to the determined supporting force,the pylon construction process Forces analysis,according to the of the structure during construction to determine the pre-deflection and pre-deflection of the pylon structure;optimize the five active cross struts of the original construction program;in order to ensure the pylon construction in the summer linear shape,Jiayu Bridge pylon construction The use of tracking prism method to verify the effectiveness of this method.(4)The stress of the lower pillars in the process of tensioning is too large,three schemes are proposed from the design point of view,and the feasibility of these three schemes is verified,which will provide a reference for the design of similar pylons in the future. |
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