Cable force testing method based on support stiffness of unknown damper under complicated boundary condition

Abstract

The invention discloses a cable force testing method based on the support stiffness of an unknown damper under a complicated boundary condition. A technical problem that the cable force-frequency relationships of the inhaul cables change greatly because of installation of various dampers at end portions of inhaul cables of the modern bridges and thus the precision of cable force measurement by theconventional frequency method is affected can be solved. According to the invention, a finite-element cable force testing method for damper identification is provided for the inhaul cable with a damper. An inhaul cable is established and the position of a rubber ring of the damper is replaced by a spring device equivalently; a cable force frequency relationship under support stiffness of different dampers is obtained; the support stiffness of the inhaul cable is identified by using multi-order practically measured frequency and the cable force-frequency relationship is corrected; and then onthe basis of an interpolation principle, a practically measured cable force is determined by the practically measured frequency. When the cable force testing method is applied to a certain arch bridge, the finite-element-method-based cable force-frequency relationships before and after installation of the dampers at the end portions of the cable are close to the field practically measured results,so that the certain engineering value is verified.

Description

technical field [0001] The invention relates to the technical field of cable force testing, in particular to a cable force test method based on unknown shock absorber support stiffness under complex boundary conditions, and to a cable force measurement method using a frequency method for a cable or suspender with a shock absorber at the end. Especially for the built-in rubber shock absorbers of both ends of the casing. Background technique [0002] The cables under external loads and natural conditions will inevitably vibrate, and the vibrations will cause repeated flexures at the roots of the cables, accelerate the fatigue of the steel wires, and cause people to panic about the safety of the bridge structure. For this reason domestic and foreign cable companies or manufacturers have produced multiple shock absorbers to suppress the large-scale vibration of the cable. The analysis method for cables with shock absorbers is too complicated and has low practical applicability....

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Problems solved by technology

[0003] In the prior art, the research on cables with damping devices mainly includes the following aspects: Among them, Chen Qingzhi proposed to identify the bending stiffness and the support stiffness of the damping device based on the PSO optimization algorithm. The identification method relies on the measured multi-order frequency, but the frequency above the third order of the actual short cable is not easy to measure, and the proposed cable force formula is based on the energy method, while the cable-vibration-absorbing device system is a non-conservative system due to the existence of damping force, and the system energy is not conserved. Use the energy method to solve; Li Tingbo proposed to solve the equivalent stiffness of the shock absorber without considering the bending stiffness, but the actual bending stiffness of the short cable is relatively large, and ignoring the bending stiffness will also lead to a certain deviation

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