| With the increasing investment in transportation infrastructure in China,more and more cable-stayed bridges are built and applied because of their superior mechanical performance.As the main stressed component of cable-stayed bridge,the damage of cable will cause adverse changes to the overall structure of the bridge.However,due to the influence of corrosion,alternating load and other factors in the service period of cable-stayed bridge,the cable is easy to break in varying degrees.Steel strand cables are widely used in stay cables due to their simple tensioning and convenient transportation.However,due to the complex structure of steel strand cable and the mutual influence of each steel strand,the internal force of steel strand is not clear,and it is difficult to accurately evaluate its safety after damage.In order to reveal the stress mechanism of steel strand after broken wire,this paper tries to find out the hierarchical relationship :silk-wire strand-cable in steel strand cable,and find out the safety evaluation method of cable after broken wire damage.Relying on a Yellow River Highway Bridge as the actual engineering background and the special fund project(300102219705)of basic scientific research business expenses of Central University,the following studies are carried out:In this paper,in order to reveal the stress mechanism and safety of the broken steel strand cable,through establishing the hierarchical relationship: silk-wire strand-cable in steel strand cable,and find out the safety evaluation method of cable after broken wire damage.Relying on the science and technology project of Shaanxi Provincial Department of Communications(17-15k)and the special fund project of basic scientific research business expenses of Central University(300102219705),the following research is carried out:1.A 1 × 7 solid model of 1860 grade steel strand is established in Solid Works.Hyper Mesh is used for mesh generation and ANSYS Workbench is used for analysis.The correctness of the finite element model is verified by comparing the calculated results with the existing literature through different boundary conditions and side wire breakage and middle wire breakage effects.The calculation results show that the middle wire fracture has little effect on the stress of steel strand,and the stress growth and stress distribution are the same as those before the wire fracture.After the side wire fracture,the stress redistributes to the adjacent wires,which leads to the stress increase of the adjacent wires,and enters the plastic development stage earlier than other wires,which leads to the decrease of the bearing capacity.2.In Solid Works,the cable model with 7-hole anchorage is established,and the influence of the change of the axial force of one tendon on the axial force of other tendons is analyzed by ANSYS Workbench;then the cable with 7-hole anchorage and 250-37 type cable are established,and the influence of the failure of one tendon on the whole cable force and the tension of other tendons is analyzed.3.The Midas civil model of a Yellow River Highway Bridge is established to analyze the influence of cable damage at different positions on the main beam and main tower of the bridge.The sensitivity of the main tower and main beam to cable damage is obtained,and the influence effect of cables at different positions on the main beam and main tower is obtained.4.After the influence effects of wire,strand and cable are obtained,the matter-element extension evaluation method is used to establish a cable safety evaluation model with wire strand cable hierarchical relationship.According to the analysis results of this paper,the weights of different hierarchical relationships are obtained.Taking the broken wire damage of a cable of a highway bridge on the Yellow River as an example,the matter-element extension evaluation method is used to evaluate its safety. |
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