Study On The Optimal Control Of The Line Shape Of The Arch Rib And The Force Inside The Arch By Adjusting The Buckle

At present,most of the concrete-filled steel tube arch bridges are constructed by the cable-stayed buckle-hang-cantilever construction method.Among them,the calculation of the buckle cable force,the concrete pouring in the steel tube and the calculation and construction of the suspender are all difficult points.The purpose of this paper is to obtain a cable force calculation method that can satisfy the target line shape and construction cable force of arch rib of long-span concrete-filled steel tube,then the method can optimize the construction process and adjust the construction line shape and stress of arch rib,and adapt to some current and even later intelligent tensile means.The feasibility of this method is verified by calculation,what’s more,it is found that the load adjustment of arch rib can be carried out scientifically,and the safety of the construction process can be guaranteed.Based on the engineering background of the Ping Nan Third Bridge,a concrete-filled steel tube arch bridge with a main span of 575 m,this paper completed the calculation and optimization of the cable tension of the cable-stayed buckle construction of the bridge:(1)Explain the development situation of concrete-filled steel tube in my country.Then,sort out the research on cable force calculation and optimization by domestic and foreign scholars,and summarize the current research status in cable force calculation and optimization;(2)Introduced the common line shapes such as the manufacturing line,construction line and target line of concrete-filled steel tube arch bridge.Then introduced the current commonly used cable force calculation methods for concrete-filled steel tube,and made a brief evaluation of the advantages and disadvantages of different cable force calculation methods.At the same time,the construction overview of Ping Nan Third Bridge will be introduced in detail,and the bridge model will be established and calculated using the finite element software Midas Civil.(3)A detailed introduction to the cable force calculation and optimization methods used in this article.First,using the simplified moment balance method to calculate the initial iterative tension force,and at the same time,obtaining the preraised height of initial segment.Then using the fixed-length cable method to iterative calculate the cable force with the iterative forward algorithm idea of arch rib hoisting prediction to obtain the cable force that meets the linear requirements.finally,an optimization model is established on the basis of the traditional optimization model.The optimization model increase constraint of the maximum cable force difference between adjacent segments.Iterate repeatedly until the allowable error condition is met based on the new optimization model.After analyzing the finally obtained cable force,displacement and stress results,then the results show that as the maximum cable force difference between adjacent segments decreases,the cable force and line shape in the construction stage are improved.(4)Analyze the factors that affect the cable force and arch rib line shape.The calculation and analysis show that the increase in the angle of the buckle can significantly reduce the amount of the buckle,and the construction line shape is better.But with the increase in the height of the tower,it is necessary to balance the angle of the buckle and the height of the tower.The timing of the hinge has less impact on your buckle during the construction process,and has a greater impact on the displacement of the arch rib and the stress at the arch foot.Through the analysis of the new cable force calculation optimization method,it can be well adapted to the construction of large-span concrete-filled steel tube arch bridges.The one-time tension method avoids more repeated cable adjustments,and it has strong applicability and can be used for construction cables.What’s more,this method can realize the double control of linear and cable force,and provides a certain reference for the construction of large-span steel tube concrete arch bridges.