Research On Identification Method Of Cable Forces In Complex Boundary Conditions

With the development of China’s economy and the advancement of bridge technology,large-span cable support system bridges have been widely constructed.These bridges can not only alleviate the increasing traffic demand,but also have a beautiful structure,which is favored by designers;and the bridge cable structure as an important force member,its stress situation directly affects the overall safety of the bridge structure,but also We evaluate an important indicator of bridge health.Most existing cables that do not have a cable pressure sensor installed use the frequency method for cable force identification.The frequency method has the characteristics of quickness and simplicity,and has been widely used in the cable force identification.The traditional cable force calculation formula is derived based on simple boundary conditions,but the results of the cable frequency test will be affected by various factors;in order to more accurately identify the cable force at the complex boundary and consider the influencing factors,This paper studies these problems based on the finite element method.The main work contents are:(1)Analyze and summarize the current relevant theories and methods of frequency identification cable force at home and abroad.(2)According to the structural characteristics of the cable,combined with its linear theory and vibration theory,the calculation formula of the cable force under complex boundary conditions is deduced.The formula believes that the boundary correction coefficient can be determined according to the actual boundary conditions of the cable to accurately determine the cable force Identify;Analyze the influence of the relevant influencing factors during the frequency test of the cable,and give the calculation method of the cable section stiffness from the perspective of the principle of the cross-section structure.(3)Combined with the finite element theory,ANSYS finite element software was used to simulate the cable structure.By comparing the vibration frequency of the cable with hinged boundary conditions,the correctness of the cable force identification method was verified;based on the finite element analysis,the cable was considered The change of cable frequency after the cable bending stiffness and sag affects the degree of influence of these two factors on the cable frequency.(4)By deducing the calculation formula of complex boundary conditions,the relationship between the boundary correction coefficient and the relevant dimensionless parameters is established;combining the results of the finite element numerical calculation,the data fitting method is used to obtain the consolidated boundary conditions.Boundary correction coefficient;based on the simulation analysis of the elastic boundary,the calculation method of the cable force under the elastic boundary condition is proposed;the effect of the built-in damper of the cable on the vibration of the cable structure is studied,and the method of estimating the support stiffness based on the binary linear regression is proposed,And then the method of cable force identification.(5)Combining engineering examples,the frequency of the cable under the consolidation boundary and the shock absorber is identified by the frequency spectrum method to verify the accuracy of the relevant formulas and methods.