Research Of Optimization Of Cable Force Of Concrete Cable-stayed Bridge Based On Influence Matrix Method And Intelligent Algorithm

When the structural system and component size of the bridge are determined,the cable force is an important factor to determine the stress of cable-stayed bridge.Therefore,determination of reasonable completed cable force and reasonable constructing cable force are critical issues during design and construction control of prestressed concrete cable-stayed bridge.On the basis of summarizing the existing theory and method of cable force optimization,in order to solve the shortcomings of the research status,key issues of reasonable completed cable force and reasonable constructing cable force for prestressed concrete cable-stayed bridge are explored and resolved through the combination of influence matrix method and group intelligent optimization algorithm with the prestressed concrete cable-stayed bridge as engineering background in this thesis.The main contents were as follows:(1)Firstly,the application,development and structural characteristics of concrete cable-stayed bridge were briefly reviewed;the research status,basic theory and applicability of optimization method about completed and constructing cable force were introduced in detail;the advantages of the combination of the influence matrix method and group intelligent optimization algorithm in optimization of cable force were elaborated,and the shortcomings of the current research were pointed out.(2)Secondly,an improved single-objective salp swarm algorithm based on the principle of harmony search was proposed to overcome defect of standard salp swarm algorithm,several unconstrained test functions and truss optimization problems with frequency constraints verified that the improved algorithm has the characteristics of faster convergence speed and higher accuracy compared with other salp swarm algorithm and classic single-objective algorithm;meanwhile,on the basis of this,combined with the characteristics of multi-objective problem,an improved multiobjective salp swarm algorithm based on population dynamic grouping strategy based on diversity feedback and elite retention strategy based on harmony search was proposed,through the simulation analysis of multi-objective series test functions,it was confirmed that this multi-objective algorithm had better convergence and diversity than the basic multi-objective salp swarm algorithm and other classic multi-objective algorithms.(3)Thirdly,Midas/Civil finite element model which takes a cable-stayed bridge as an engineering background was established and the rationality of it was confirmed by model comparison,which ensured the accuracy of subsequent studies;Taking the bending moment of the girder for example,the deviation of traditional method was analyzed,and reasonable initial cable force and its increment were reckoned,then the influence matrix method with small deviation was proposed,which obviously reduced the calculation deviation.(4)Fourthly,the traditional unconstrained cable force optimization method was used to optimize reasonable completed cable forces,which proved the defects and shortcomings of them;The combination of the influence matrix method with small deviation and HS-SSA,DGHS-MOSSA were proposed respectively to establish the optimization model of reasonable cable force and optimize reasonable completed cable force;In single objective optimization of cable force,the influence that made by strain energy of tension and compression on results was analyzed,and then,the changes of stress and deformation state of structure were compared respectively,the method could avoid the arbitrariness of artificial adjustment of cable forces when the constraints were reasonable;In multi-objective optimization,the problems of single-objective optimization with a single result and difficult to determine the range of constraints were solved successfully,in which strain energy and vertical displacements of girder was taken as objective function,and the differences of the worst stress and deformation under different displacements of pylon were compared,meanwhile,the difference of results between the multi-objective and single-objective were analyzed.This method could avoid the process of repeated trial calculation in completed optimization of cable force and get multiple solutions at one time for further selection.(5)finally,the construction influence matrix with small deviation was derived.Considering the effect of shrinkage and creep in the construction stage,reasonable cable force of completed bridge was revised and the effect on the optimization result was analyzed.Then,with the reasonable cable force of completed state as goal,the optimal cable force of construction was optimized by HS-SSA.This method realized the coupling optimization of cable force of completed state and construction state based on shrinkage and creep.