Study Of Combinatorial Optimization Of Determining Reasonable Cable Forces Of Completion State Of Bridge Of Double-Tower Prestressed Concrete Cable Stay Bridge

Due to large spanning capacity and good economic benefit,prestressed concrete cable-stayed bridge get fast development in recent years,and the form of a cable-stayed bridge is increasingly diversified.Although cable area on both sides of the main tower still symmetric arrangement in partially cable-stayed bridge,but there are many differences between two sides sometimes.Such as side span of double-towers three large span cable-stayed bridge have a no cable area,cable force near the no cable area is significantly greater than the cable forces at the same time near the mainspan side,thus causing cable force obviously unreasonable that near no cable area,and the main tower bottom generate large bending moment.Based on the double-towers three span prestressed concrete cable-stayed bridge that side span have a larger no cable area as the background engineering,Respectively by rigid support continuous beam method,minimum bending energy method,using a reasonable method of minimum that three common bridge calculation method for its solution,explore the existing problems and the corresponding optimization scheme of the results.Three aspects are explored as follow.First,the principle of three methods are explained.The problems in rigid support continuous beam method in theory are analyzed theoretically and the point of optimization solution according with force equation is analyzed.On the basis of the minimum bending energy method's formula when it was selected minimal value,its significance and the relationship between the minimum bending energy method and the continuous rigid-support beam method are studied.Based on the method of stress balance,the design limit of concrete bar bending moment in different loading cases are explored.A calculation formula of bending moment design limit are given which provide theoretical reference for setting the tower beam bending moment constraints of the minimum cable method.Second,MATLAB are used to solve the force of built bridge of the background engineering with three programming methods.The regular of each methods are summarized,the cause of the problem in the result are analyzed.In view of the problems,optimization solutions are put forward theoretically.Finally,combining with the actual of the background engineering,three optimization solutions: cable force adjustment method,adding cantilever beam method,the method of adding upper and lower limits of cable force are came up with to tackle the existent problem in the rigid support continuous beam method,the minimum bending energy method and the minimum cable method.After the optimization which apply three kinds of optimization method,the existence of problems in solving were effectively solved.The problem of induction and the optimal solution which have been explored in three method can provide reference for similar cable-stayed bridge case in this article.On the other hand,the formula of cross section bending moment's design limit can provide theoretical reference for concrete bar bending moment of correlation analysis.