Research On The Externally Prestressed Key Parameters Of PC Composite Box-Bride Continuous Rigid Frame Bridge With Corrugated Steel Webs

This paper,based on Huatianhe Bridge,to force analysis by finite element software.The layout of steering and anchoring positions,that is,the deployment of linear external prestressing tendons,exerts a certain effect on the stress,quadratic effect and external prestressing increment of the whole structure,as external prestressing tendons are positioned outside the structure and their tension force can be transferred onto the main girder only through anchor beams and deviators in contact with the main girder.This paper,based of previous studies,carries out the research content for the reasonable proportion of completed bridge tendons and optimizing the design of external prestressed tendons linear:(1)First of all,discussion of several configuration mode of steel strands,combining the project to determine the most reasonable configuration.(2)Adopting the Midas Civil to calculate the overall structure,conduct the tendon matching design for external prestressing in accordance with code requirements,and estimating the stress of the overall structure after initially determining the number of tendons to be configured.(3)As for the long-span rigid-frame bridge constructed with corrugated steel web the characteristic of prestressed tendons configuration:the top cantilever construction tendons is mainly responsible for the negative bending during construction period and operation period,the bridge tendons in bottom plate is used to bear the positive bending after completion of the bridge,the external bridge tendons is used to bear the variable load after completion of the bridge.According to his configuration characteristics,the research is conducted on the influence of changes in the proportion of internal(the bridge steel strands in bottom plate)and external prestressing on the stress performance of the structure with an aim to control the section(mid-span section)on the basis of meeting the requirement of the limit state and the ultimate limit state for normal use,Study out the curve equation of proportion K(the ratio of external prestressing and the bridge steel strands in bottom plate)and deflection,seeKing the most reasonable range of K.(4)Externally prestressed tendons taKe the shape of a fold line,as its anchoring position determines the effective eccentric distance and affects the stress performance of the structure to a different extent.In this paper,we research the influence of the anchoring position of side span and midspan on the stress of the structure to figure out the extent and law of the influence as the aforesaid project is deployed and tensioned by span.(5)In this paper,we maKe use of Midas FEA finite element software and build the finite element model to study the quadratic effect,and use truss elements for simulating externally prestressed tendons outside the structure and solid elements for tendons buried into concrete main girders.TaKing the interval and number of deviators as variants,we conduct the linear and non-linear calculation to figure out its iMPact on the quadratic effect and externally prestressed stress increment.(6)We adopt Midas FEA finite element software to study the influence of the ratio of space between side and middle spans on the stress performance of the overall structure and get the law of main girder deformation and stress variety with different ratios of space.