The Reasonable Condition In Two Stages And The Analysis Of Broken Cable Risk For Single Tower Cable-stayed Bridge

With its own advantages the single tower composite girder cable-stayed bridge has become a kind of bridge who started relatively late,but its development is rapid.Its structure and loading is complex,but the structure of the space effect is remarkable.After the loading is known clearly,how to determine the reasonable bridge state and the reasonable construction state is one of the challenges with which single tower composite beam cable-stayed bridge design and construction faced.Lasso as important bearing and power transmission components,its cable force is the premise and key to determine the cable-stayed bridge in reasonable state.In addition,cable component is relatively weak parts in cable-stayed bridge structure.It will cause enormous losses when the line is broken on whatever phase which occurs in its life cycle,therefore the finite element simulation is used to study how do the broken line affect the structure and it’s necessary that the structure’s dependence of different position is obtained.The fourth Aojiang bridge under construction is a composite beam cable-stayed bridge which has a single tower and double cable plane,two asymmetric arrangements.This paper set the bridge as engineering background,using ANSYS simulation analysis,systematic researched the method of definite during the service and construction stages of cable-stayed bridge,and then analyzing the influence of cable failure to the structure after the cable-stayed bridge finished building.The main research content is as follows:(1)This paper comprehensively analyzes the current method at home and abroad which is used to determine reasonable cable force at bridge stage and construction stage,giving various methods a certain objective evaluation,introducing the principle of the first-order analysis and steps in detail and lying a theoretical foundation for its further research.(2)The paper introduces briefly the survey of fourth Aojiang bridge engineering,using ANSYS parametric design language(APDL)to establish the finite element model of the bridge,choosing bending strain energy of structure as objective function,basing on the idea of first order analysis to write optimization analysis file,which is used to determine the optimal cable force of the completed bridge,and making brief analysis of the internal force and linear at a bridge component state.(3)This paper formulates appropriate construction process for the fourth Aojiang bridge,re-establishing optimization analysis file,choosing the weighted sum of linear of main girder and the bending strain energy of structure at a reasonable bridge state as objective function and using the method of first-order optimization analysis to obtain secondary lasso tension in the construction process,and thus get the reasonable construction state,which offer reference opinions for engineering construction.(4)In order to qualitatively analyze the dependence of cable-stayed bridge structure on of every lasso,the paper choose the service stage of fourth Aojiang bridge as the basic state,according to two cases of single fault line and broken line in a variety of operating mode,to simulate broken line and making the finite element simulation analysis,which will analyze the influence of broken cable to cable tower,girder and cable one by one,and examine the degree of change of broken line on the structural dynamic characteristics,in order to provide some references for the design,construction and daily maintenance of the similar bridge.