Research On Structural Form Of Transition Section Of Cable-stayed-continuous Cooperative System Bridge

The cable-stayed-continuous cooperative bridge type has certain advantages over the pure cable-stayed bridge,however,this bridge type also has the problem of how to make a reasonable transition between the diagonally-span main beam and the continuous-span main beam.This is mainly because the π-beam is usually the best option for the construction of the diagonally-span across the main beam and the continuous beam is the most suitable one for the large box girder,thus it is difficult to make effective transitions in the section.If the diagonally-span main beam also adopts a large box girder that is completely consistent with the continuous beam,then the difficulty of diagonally pulling the cantilever construction will be increased.Because of this,this bridge type has encountered certain obstacles in comprehensive promotion and application.Although more than ten bridges of this type have been built in China,this problem still enjoys research significance.In this paper,a typical cable-stay-continuous cooperative system bridge,Fengcheng Jianyu Bridge,is used as the engineering background,and the structural form of the transitional sections of the cable-stayed-continuous system bridge is analyzed.The paper firstly compares and analyzes the typical forms of the main beam transition section of a typical cable-stayed-continuous cooperative system bridge.Then,the full-bridge finite element model is established by Midas/Civil finite element software,and the full bridge and local transition sections are checked and analyzed.Next,the Ansys three-dimensional finite element software is used to establish the solid element calculation model of local transition sections of the original structure.Finally,the Ansys finite element model is respectively established by adjusting the height of the diaphragm,the thickness of the diaphragm,the spacing of the diaphragm and the non-gradient transition sections in the original design structure,and the local displacement and stress conditions of the transition sections are compared and analyzed,which provides reasonable reference for the rational design of the transition segment structure of the continuous collaboration system.The main conclusions of this paper are as follows:(1)With the assistance of Midas/Civil,the structural check of the full bridge of Fengcheng Jianyan Bridge is carried out.It shows that the maximum displacement of the structure is 13.9cm,which meets the requirements of the specification.The cable-to-cable limit of the cable is less than 0.4,which meets the design.The allowable compression stress is16.4 MPa,which satisfies the calculation of structural normal stress.(2)When the transverse baffle is 10 cm away from the bottom of the beam,the influence of the displacement on the original structure is obvious,and the effect of the normal stress onthe cross-section of the cross-section is also the largest.However,the change of the height of the transverse baffle has no significant effect on the normal stress of the side of the box girder.When the thickness of the diaphragm reaches 50 cm,the vertical torsional displacement and vertical displacement of the original structure are more obvious,and the normal stress on the cable-stayed roof is also the largest.When the spacing of the diagonally-spaced diaphragms is encrypted,the influence on the displacement of the original structure is obvious and that of the transverse diaphragm on the corresponding beam side is relatively obvious.(3)By adopting the non-gradient transition form,the displacements of the original structure are significantly reduced.However,the structure is not smooth enough in the stress transition,and stress concentration is likely to occur.