Long-span Cable-stayed Bridge With Double Box-shaped Girder Anchorage Study On Structural Characteristics Of Mechanical Behavior And Fatigue Properties

As the connecting structure that transfers cable force to main beam,cable-beam anchor structure often has various structure forms,dense welding seam of plate,complex force transmission mechanism and prominent local stress concentration.Therefore,it is very important to master its mechanical behavior and fatigue performance.Anchor box beam structure is one of the most common anchorage structure,traditional steel anchor box by the supporting plate and bearing plate through unilateral weld connected to the main girder,the paper studied the new double pick different anchor box beam structure is,through the bearing plate,top plate,sealing side of the end plate and web plate welding,thus structure form is more complicated.Based on the new type of cable beam anchor structure with double cantilever anchor box,the mechanical behavior and fatigue performance are studied in this paper.The main contents include:1.The finite element model of Midas full bridge is established.According to the loading calculation of the code,the most disadvantageous section of anchor box and the cable force amplitude are determined to be 2600 kN.Based on the design principle of the test model,the full scale model test loading scheme is designed,and the finite element software ANSYS is applied,through the stress equivalent comparison between the original segmental model and the test model,the results show that the error between the test model and the original segmental model is small.2.The static performance of the cable-girder Anchorage Structure With double-hanging anchor box is studied,and the rationality of the finite element analysis is verified by comparing the test results with the finite element calculation results.At the same time,the stress transfer law of the main welding seam of the structure is analyzed.The stress of the four longitudinal welding seam is basically the same,from the side of the end plate to the side of the top plate gradually changed from tensile stress to compressive stress.According to the calculation results of the original segmental model of the bridge,the force transfer mechanism of the cable-beam Anchorage Structure With double-cantilever anchor box is analyzed.The results show that the shear stress distribution of the four longitudinal welds is uniform,and the main force-transfer welds are the four Longitudinal welds,and the cable force ratio of the four longitudinal welds is 98%.3.The full-scale model fatigue test was carried out.During the fatigue verification stage and the fatigue failure stage,no cracks were found in the model by magnetic particle inspection.The test results show that the load stress curve of each fatigue detail varies linearly and keeps stable with the increase of fatigue load cycle times,and the structure has a certain fatigue strength reserve.4.Comparing the fatigue checking rules and the fatigue details in the relevant design codes of domestic steel structure,according to the test data,the fatigue strength of the structure is checked,and the results show that all fatigue details meet the requirements of the code.At the same time,the S-N curve of each specification is used to evaluate the fatigue life of steel anchor box and analyze the applicability and limitation of each specification.