Research On Reliability-based Optimization Of Buckle Cable Tension Of Steel Truss Arch Bridge At Construction Stages

Calculation of the forces of the buckle cable is difficult for the steel truss arch bridges using buckle cable at construction stages.In actual engineering,various uncertainties has great influence on both the internal force and displacement of the bridge.A reasonable stretching plan should satisfy all kinds of control criteria under the influence of various uncertainties.In order to solve these problems,a reliabilitybased buckle cable force optimization method based on Multi-objective optimization method is proposed.And the stretching plan is optimizated under the Conditions of reliability at construction stages.The main work is as follows:1.The basic method of reliability analysis and structural optimization based on reliability is introduced.Combining the characteristics of multi-objective optimization,a complete set of multi-objective structural optimization method based on reliability is established.2.Taking a reliability analysis of a plane truss model for Example,the advantages and disadvantages of three kinds of surface fitting method were compared,and the support vector regression was identified to be used.the design of the plane truss is optimizated based on reliability using the proposed method,and the feasibility of the method is proved.3.Taking a steel trussed arch bridge with a span of 70m+240m+70m for example.reliability of the stress of steel truss and the cable,stability of web membe and bearing at cable-stayed suspension construction stages is calculated,and the sensitivity of the uncertain factors is analysised.According to the general width limit method,the result reliability index at cable-stayed suspension construction stages is1.12 <β <1.15,and the construction scheme should be optimizated to decreased the hidden danger.4.The present method is applied to the steel trussed arch bridge,the random variables which affect the structural reliability are selected,the proposed method is used to optimize the design variables after screening.According to the analysis results,both the alignment and strain energy is optimizated,and the reliability of buckle cable is within an acceptable range by optimizing the buckle cable forces.The results showed that The optimized system reliability is 3.13 <β <3.22’,which is improved obviously.The absolute value of displacement error is reduced by 12%,the bending strain energy of the structure at the closure construction stage is reduced by2.6%.The proposed method Combined optimization based on reliability with multiobjective particle swarm optimization,the influence of various uncertainties is Considered,and optimization results is Pareto optimal set,which can be used by decision makers to choose the appropriate solution based on the specific situation.