Tension test method for stay cable steel strand of partially cable-stayed bridge

A cable-stayed bridge cable steel and testing method technology, applied in the direction of tension measurement, etc., can solve the problems of short cable, low tension accuracy of cable steel strands, and difficult to accurately identify the bending stiffness of cable steel strands, etc. To achieve the effect of convenient testing process

Inactive Publication Date: 2011-07-13
ZHEJIANG UNIV
5 Cites 12 Cited by

AI-Extracted Technical Summary

Problems solved by technology

However, the epoxy steel strands of some cable-stayed bridge cables are bound together by cable clamps at both ends, and the length of the cables is relatively short. The influence of bending stiffness and boundary constraints on the natural frequency cannot be ig...
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Abstract

The invention provides a tension test method for a stay cable steel strand of a partially cable-stayed bridge. A steel strand of a certain length is fixed in the stay cable steel strand of the partially cable-stayed bridge, and the fundamental frequency and bending stiffness of the steel strand are tested, so that the tension of the stay cable steel strand can be calculated based on the cable free vibration computation theory considering the influence of bending stiffness according to the fundamental frequency, bending stiffness, length and quality parameters of the steel strand. By utilizing the test method, the high-precision tension test result of the steel strand can be obtained; and moreover, the test process is convenient, and the test method meets the requirement of tension test in the construction process and operation period of the stay cable steel strand of the partially cable-stayed bridge.

Application Domain

Technology Topic

Flexural rigidityEngineering +4

Image

  • Tension test method for stay cable steel strand of partially cable-stayed bridge
  • Tension test method for stay cable steel strand of partially cable-stayed bridge
  • Tension test method for stay cable steel strand of partially cable-stayed bridge

Examples

  • Experimental program(1)

Example Embodiment

[0015] The test method provided by the present invention uses a section of the steel strand in a part of the cable-stayed bridge cable steel strand as the test section of the steel strand to test the fundamental frequency and bending rigidity of the section of the steel strand. Fundamental frequency, bending stiffness, length, quality parameters, according to the calculation theory of free vibration of cable considering the influence of bending stiffness, calculate the tension of some cable-stayed bridge cables; the test process of the fundamental frequency includes the following steps:
[0016] (1) Select any length of the steel strand in the cable-stayed bridge cable as the test section steel strand, and fix the two ends of the test section steel strand by connecting rigid bodies between the two ends;
[0017] (2) Use an acceleration sensor and a matching acquisition instrument to measure the fundamental frequency of the steel strand in the test section.
[0018] The bending stiffness test process includes the following steps:
[0019] (1) Select a section of steel strand without tension action, and fix its two ends with artificial boundaries, and its length, cross-sectional area and material are the same as the test section steel strand;
[0020] (2) Measure the fundamental frequency of this section of steel strand by using an acceleration sensor and a matching acquisition instrument;
[0021] (3) According to the known tension conditions (such as zero tension), calculate the bending stiffness of the steel strand in the test section.
[0022] Reference figure 1 In this embodiment, the following device is used to fix the two ends 11 and 12 of the steel strand 1 of the test section.
[0023] The device includes a strip rigid body 2 and steel stranded wire connectors 31, 32. The steel stranded wire connectors 31, 32 are fixed on the strip rigid body 2 and respectively used to connect to the two ends of the steel strand of the test section. Fix both ends of the steel strand in the test section.
[0024] The strip rigid body 2 can be a steel beam, and the symbol 4 is a vibration sensor. It uses an acceleration sensor, such as the DH301 capacitive three-way sensor produced by Donghua Electronic Instrument Factory, and is collected by a DH5901 handheld dynamic signal test analyzer 5 And analysis. According to the calculated length l between the two constrained boundaries of the steel strand and the section parameters (mass per unit length m, section bending stiffness EI and cross-sectional area A), the tension T of the steel strand is calculated from the measured frequency f.
[0025] According to the calculated length l between the two constrained boundaries of the steel strand and the section parameters (mass per unit length m, section bending stiffness EI and cross-sectional area A), the tension T of the steel strand is calculated from the measured frequency f.
[0026] The following describes the calculation theory of estimating tension based on frequency.
[0027] The free vibration equation of steel strand considering the effect of bending stiffness is:
[0028] EI ∂ 4 w ∂ x 4 - T ∂ 2 w ∂ x 2 + m ∂ 2 w ∂ t 2 = 0 - - - ( 1 )
[0029] In the formula, w is the lateral vibration displacement of the steel strand, EI is the bending stiffness, that is, the product of the elastic modulus E and the section moment of inertia I, T is the tension, and m is the mass per unit length of the boom. Here, it is assumed that the vibration of the boom is a small deformation, and the change in tension during the vibration can be ignored.
[0030] The natural frequency of the steel strand can be obtained according to the non-zero solution condition of equation (1). The natural frequency of the i-th mode is:
[0031] f i 2 = π 2 EI 4 ml 4 ( i - φ π ) 4 + T 4 ml 2 ( i - φ π ) 2 - - - ( 2 )
[0032] Where
[0033] tan φ = - 2 ω T mEI - - - ( 3 )
[0034] Where ω is the circular frequency.
[0035] Fix a steel strand under the condition of zero tension, test the vibration frequency, obtain the bending stiffness EI by formula (2), and then substitute formula (2) to obtain the steel strand of the cable-stayed bridge under any force Line tension.
[0036] In order to verify the effectiveness of the method and device of the present invention, it was verified in the inspection of a certain part of the cable-stayed bridge in Hangzhou, and several cables were selected for measurement. For easy operation, select a section of steel strand on the side close to the main beam and use both ends figure 1 The device shown is fixed, and the length of the fixed section is measured. The fundamental frequency of the steel strand is measured by an acceleration sensor and a matching acquisition instrument. Then test the bending stiffness of the steel strand. According to the steel strand of the same material, cross-sectional area and length, the two ends of the steel strand are fixed in the same way, and the fundamental frequency of the steel strand under environmental vibration is measured under zero tension. The tension is zero and the inverse calculation obtains the bending stiffness of the steel strand. In this way, under the premise that the boundary conditions and bending stiffness of the steel strand are known, the vibration frequency method is used to obtain the tension from the fundamental frequency of the steel strand according to formula (2).
[0037] The cable force of a partially cable-stayed bridge is measured, and any steel strand of the cable is selected, its tension calibration value T=129.0kN, the measured vibration frequency f=228.44Hz, the tension calculated by the method of the present invention T * =130.2kN, the ratio δ to the calibration value * =1.01; the tension T calculated according to the string theory without considering the bending stiffness 0 =171.02kN, the ratio δ to the calibration value 0 = 1.33. It can be seen that the algorithm of the present invention is more accurate than the tension calculated by traditional string theory.
[0038] According to the same test method, the tensions of the other 6 steel strands were tested, which are listed in Table 1. It can be seen from the data in the table that using the test method of the present invention, there are three sets of tension test accuracy of about 100%, and the remaining accuracy also exceeds 90%, while the traditional string theory test results are about 30% larger than the calibration value on average. It can be seen that the tension results obtained by using the testing method and device of the present invention have high accuracy.
[0039] Table 1 Tension test accuracy of cable steel strand
[0040]
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to view more

PUM

no PUM

Description & Claims & Application Information

We can also present the details of the Description, Claims and Application information to help users get a comprehensive understanding of the technical details of the patent, such as background art, summary of invention, brief description of drawings, description of embodiments, and other original content. On the other hand, users can also determine the specific scope of protection of the technology through the list of claims; as well as understand the changes in the life cycle of the technology with the presentation of the patent timeline. Login to view more.
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to view more

Similar technology patents

Classification and recommendation of technical efficacy words

Who we serve
  • R&D Engineer
  • R&D Manager
  • IP Professional
Why Eureka
  • Industry Leading Data Capabilities
  • Powerful AI technology
  • Patent DNA Extraction
Social media
Try Eureka
PatSnap group products