Cable Force Measurement With String-like Vibration Method And Safety Evaluation Of Cable-stayed Bridge Based On Cable Force

The cable is a commonly used component in engineering,especially in the cablesupported bridge system,the cable force affects the entire structural system at all times,so it is a key indicator in both the construction stage and the operation stage.Among the various common cable force identification methods at present,the vibration method is widely used because of its easy operation and high cost performance.However,the commonly used calculation formula is based on the theory of the articulated string model.For short cables,the boundary conditions affect the weight more,and the boundary conditions tend to be fixed.The cable-stayed bridge is a typical cable-supported bridge.The actual state of the cable-stayed bridge during the operation phase will change due to the effects of concrete creep,the stress relaxation effect of the cable itself,the external environment and other factors,therefore,it is necessary to conduct a safety evaluation of the cable-stayed bridge during the operation phase.The main research contents of this article are as follows:(1)In this paper,the relationship between the vibration frequency and cable force of the cable under fixed boundary conditions is deduced,but because it is beyond the equation,the analytical solution cannot be obtained,so two dimensionless parameters are introduced: "Relative stiffness" and "Ratio of relative frequency coefficient",the stringlike vibrating method is also named.A short cable with a length of only 5.33 m was subjected to graded tensile test.Based on the collected data,the calculated bending stiffness of the cable section was identified.A three-parameter dimensionless model was proposed.The measured frequency was substituted into the model calculation and the measured cable Comparing the force,the error is small,which proves the feasibility.(2)The action principle of the cable-beam structure is analyzed,and the analytical solution of the target force and target shape is derived by the force method.Several methods of accurately applying cable force are compared,the influence matrix method is used,the flow chart is designed,the secondary development is carried out based on ANSYS,and the single and double cable beam model examples are used to make specific explanations and confirm the feasibility.(3)Installed a cable force monitoring system on a cable-stayed bridge in operation stage,established a finite element model of the real bridge,and analyzed the three nonlinear problems and solutions of the cable-stayed bridge,The calculation process of the influence matrix is specified,and the influence matrix between the cables and the initial tensile force corresponding to the equilibrium final cable force are obtained,according to the accumulated measured cable force data,the actual state of the bridge is analyzed,and the cable stay is evaluated for safety.Cable-stayed bridges meet the design requirements in terms of internal force distribution,line shape,and vertical deflection of the main beam.