Study On The Damage Classification And The Fatigue Life Of Cable Wire

As China's modern infrastructure construction is gradually improved, bridge facilities which are still in operation step into a operational and maintenanable stage. Bridge as a hub engineering across the the Cliff and valley, steel members appeared different degrees of corrosion damage with the growth of operational service life. As for cable-stayed bridge, lasso is the most critical component and its Cable corrosion and fatigue damage threaten the whole bridge's operation safety seriously. Therefore, there is an important engineering practical significance to study the classification of corrosion damage according to the cable of cable-stayed bridge in the operation and evaluate cable wire's remaining fatigue life in different corrosion degree and state of force.The main research work of this paper is as follows:Firstly, introducing the evaluation method of corrosion damage of steel wire in the current situation at home and abroad and the related theory of evaluating the cable's fatigue life, and determining to use Paris formula in the damage tolerance design method to anti launch the theoretical remaining fatigue life of the tested cable wire fracture.Secondly, Based on the Xiangjiang Yinpen cable-stayed bridge's old wire,measuring and doing statistical analysis to wire macro parameters and geometric geometric parameters of different corrosion levels,the galvanized steel wire corrosion level is divided into six, and put forward a new evaluation standard of the stay-cables' wire corrosion classification which Contains the wire's diameter parameters and pit parameters.Thirdly, using electric hydraulic pulse fatigue machine to study the fatigue life of the test cable,which are arranged and combined by different steels' corrosion grades.and then obtain the cable wire's remaining fatigue life and cable wire's breaking rules under different loads.To compare the effects of cable wire fracture crack source, initial crack depth A0 width, the length of crack on the remaining fatigue life by using low magnification electron microscope to measure steel wire's fatigue fracture type.Fourthly, using ABAQUS finite element calculation software to establish steel wire's finite element model which Contains the typical corrosion, and analyse the distribution of the stress field of the pits, result in the curve and the fitting formula that erosion crater where the maximum stress concentration coefficient changes with corrosion pit parameters.Through analyzing various types of typical corrosion pit graph compares, the result shows a rule that different morphology of corrosion pit have influence on corrosion pit depth of stress concentration factor.Finally, using damage tolerance design method of fracture mechanics to make pit equivalents to half elliptical initial crack.Moreover, using quantitative Paris formula to anti launch the theoretical remaining fatigue life of the tested cable wire fracture.compare the fatigue life test value and the calculated value,the match degree is good,which can satisfy the engineering demand.