| As an important force transmission structure between the beam and the tower,the stay cable plays an important role in controlling the overall life of the cable-stayed bridge.However,due to manufacturing errors,service time and other reasons,corrosive media under certain circumstances will break the wire cable protection systems,thereby making it corrosion occurs,which will seriously threaten the safety of the bridge.Among the cable erosional diseases,the point erosional pit’s parameters are most directly related to the evaluation of the residual fatigue life.Generally,the point erosional pit is simplified into single crack,and the residual fatigue life is evaluated by the linear elastic fracture mechanics method.However,in practice,pitting corrosion often does not occur in a single way.When multiple pits appear in adjacent locations,the coupling between the stress fields of the pits will occur.The method of calculating the stress intensity factor according to the single pit crack is not accurate enough.Based on the study of single crack,the double pits are equivalent to the double cracks model,and the mutual influence between the double cracks is analyzed to simplify the double crack calculation method.The theoretical and experimental simulations of the residual fatigue life of double cracks are carried out,and the two are compared and analyzed.The test has a single crack control group,compare the residual fatigue life of single and double cracks,and analyze the influence of double cracks on the residual fatigue life.Details are as follows:(1)The parameters are selected according to the corrosion level,and the pit is equivalent to a plane semi-elliptieal crack.The erack size and related parameters were set according to the established scheme.The finite element software ABAQUS and Franc3D were combined to calculate the stress intensity factor.The calculation results are compared with single cracks,and the distribution law of influence factors is analyzed.According to the analysis results,the modified coefficient of the double crack stress intensity factor is fitted,the calculation method is simplified;(2)Based on the results of stress intensity factor analysis,the theoretical analysis of double crack propagation life is carried out.The calculation analysis group is set up,and the double-crack extension life is calculated by using the Franc3D software combined with the linear elastic fracture mechanics method.The calculation results are analyzed to provide theoretical support for the fatigue life test.(3)According to the theoretical calculation results,the test steel wires are grouped according to the actual situation,and the loading test is carried out by the electro-hydraulie pulsation fatigue machine.Counted and analysed the shape of fatigue fractures and data on the shape and size of double cracks.The experimental data were compared horizontally to study the effect of double cracks on the residual fatigue life.The vertical comparison between the experimental and the theoretical data.the deviation between the two is studied,and the feasibility of the calculation is determined. |
PDF Full Text Request