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Method for identifying variable boundary cable force of medium or long cable

An identification method, a technology for medium-length cables, is applied in the field of variable-boundary cable-force identification for medium-length cables, and can solve the problems that it is difficult to remove specific influence values, the frequency is not easy to test, and only simple boundaries can be considered.

Inactive Publication Date: 2010-12-01
SOUTH CHINA UNIV OF TECH
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Problems solved by technology

The identification of the frequency adopts the refined FFT technology, and the frequency resolution of the cable is increased to above 0.001HZ after the refinement. It can be said that the test accuracy of the natural frequency fully meets the engineering requirements. This method is widely used and has great application value. However, the current frequency The method has the following deficiencies: 1) only simple boundaries can be considered; 2) due to the influence of other structural frequencies, it is not easy to test the frequency of some ultra-low frequency or ultra-high frequency cables, that is, it is not easy to separate the tested frequencies; 3 ) is difficult to remove the specific influence value of each influencing factor (other structural vibration, environment, own parameters) in the cable
However, if the relationship between frequency and boundary conditions is taken into account: if the relationship equation between cable force and frequency changes, the frequency must change under the condition of constant cable force. It can be known from field tests on long cables that when the cable force is in the middle When constraints are applied, the frequency of the cable increases

Method used

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  • Method for identifying variable boundary cable force of medium or long cable
  • Method for identifying variable boundary cable force of medium or long cable
  • Method for identifying variable boundary cable force of medium or long cable

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Embodiment

[0056] The cable force test was carried out on the tie bars of a tied arch bridge. The cable is a 260m steel strand. There are two splitter plates in the middle of the steel strand to divide the steel strand into 3 sections, with a length of 49.7m+160.6m+49.7 m, the wire splitter plate has a strong constraint on the steel strand, which is equivalent to the "anchor" of the steel strand at the wire splitter board. Every 10-12 steel strands form a bundle of tie rods. The distance between the steel strands in a bundle of tie rods is very small. In the middle area of ​​the steel strands, there is a phenomenon that the steel strands are closely attached to each other. In addition, butter and other substances are filled between the steel strands of the tie rods, and the tie rods are set at the axis of the two arch ribs (inside the groove plate of the bridge deck) to resist the horizontal thrust of the main arch. The tie rods below the axis of each arch rib are composed of 25 (5×5) bu...

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Abstract

The invention discloses a method for identifying a variable boundary cable force of a medium or long cable. The method comprises the following steps of: performing unit discreteness on the cable, dividing the cable into n units (n is in a range of 40 to 400), and calculating a unit rigidity matrix [K]e and a mass matrix [M]e of each unit according to formulas (1) to (2); then arranging rubber cushion blocks on the cable to form external restraint, wherein the number of the rubber cushion blocks is 2 to 6 and the mounting number of the rubber cushion blocks is determined according to the length of the tested cable; and after the total rigidity matrix [K] and the total mass matrix [M] are determined, solving a characteristic value equation l[K]-omega2[M]l=0 of natural vibration frequency of a cable structure by adopting an iteration method to obtain the cable force T. Under the condition that the cable force is not changed, if the boundary condition of the cable is changed, the frequency of the cable is changed, and the equation of the frequency of the cable and the cable force is changed along with the change of the boundary condition of the cable, so the condition that the frequency of the cable cannot be tested under complex environments is solved, and meanwhile the frequency of the cable is in an interval capable of being tested by the conventional instrument by regulating the boundary condition.

Description

technical field [0001] The invention relates to a cable force identification method of a stressed medium-length cable, more specifically, a cable force identification method for cable-stayed cables of cable-stayed bridges, arch bridge suspenders, arch bridge tie rods, and main cables of suspension bridges in engineering applications. force recognition method. technical background [0002] With the vigorous and rapid development of engineering construction, cables are widely used in engineering construction due to their simple structure, beautiful appearance, and economic advantages, especially in bridge construction, such as cable-stayed bridge cable, arch bridge crane, etc. Cable rods, arch bridge tie rods, and suspension bridge anchors are all cable rods. The cable force of the cable is related to the safety of the structure. In the application of the cable, the cable force is generally very large. For example, in a cable-stayed bridge, the cable can even withstand hundre...

Claims

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Application Information

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IPC IPC(8): G01L5/04G06F19/00
Inventor 王荣辉李平杰
Owner SOUTH CHINA UNIV OF TECH
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