Method for precisely testing external prestressing tendon tensioning force
A technology of external prestressing and testing methods, which is applied in the direction of tension measurement, etc., and can solve problems such as difficult to accurately measure the tensile force of external prestressed tendons, the test accuracy cannot meet engineering requirements, and the distance between steering blocks is small.
Active Publication Date: 2014-02-05
GUANGXI TRANSPORTATION SCI & TECH GRP CO LTD
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Problems solved by technology
However, since the external prestressed tendons are usually in contact with the bridge girder through many turning blocks, the distance between the turning blocks is usually small (often within 500 times the diameter of the external prestressed tendons), resulting in the calculation of the external prestressed tendons The length is small, the contact stiffness between the steering block and the prestressed tendon, the anchorage stiffness of the prestressed tendon, the shock absorber of the prestressed tendon and other factors will have a great influence on the test frequency of the prestressed tendon, and these effects are unknown
Therefore, it is difficult to accurately measure the tensile force of external prestressed tendons by using the conventional frequency method, and its test accuracy cannot meet the engineering requirements
Method used
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Embodiment 1
[0044] as attached figure 1 , install a vibration pickup on the external prestressed tendon between the two steering gears with a distance of L, connect the vibration pickup to the vibration tester, and measure the first-order vibration angular frequency ω of the external prestressed tendon 1 ; as attached figure 2 , at the middle position L / 2 of the external prestressed tendon, install an additional mass block (magnetic iron block), the installation method is as follows Figure 5 , use the vibration tester to test the first-order vibration angular frequency ω of the external prestressed tendon after adding the mass block 1 ′; combined with the stiffness EI of the external prestressed tendons provided by the design drawings, the material density ρ and the cross-sectional area A, and the measured weight M of the mass block, the tension value T of the external prestressed tendons is calculated using formula (8) 0 .
[0045] T 0 ...
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The invention discloses a method for precisely testing external prestressing tendon tensioning force. A related test model is designed by the inventor, the boundary condition of an external prestressing tendon is simplified into a damper and a spring support, the prestressing tendon is further simplified into a simply supported stretching rope with an equivalent calculating length L0, a mass block is added to the middle of the prestressing tendon, the vibration balance equations of the stretching rope generated before and after the mass block is added to the middle of the prestressing tendon are optimized and built, the recognition algorithm of the equivalent calculating length L0 of the prestressing tendon is formed at last, and therefore the testing method is built. The testing of the method is convenient, testing cost is low, and only two vibration frequency tests need to be carried out on the prestressing tendon before and after the mass block is added. Testing precision is high, and the problem of the precise testing on the external prestressing tendon tensioning force can be solved well. The method is applied to the field of external prestressing strengthened bridge testing and can achieve the convenient and high-precision testing on the external prestressing tendon tensioning force, and therefore reliable essential data are provided for the detection and monitoring of the bridges of the kind.
Description
technical field [0001] The invention belongs to the technical field of bridge detection and monitoring, and in particular relates to an accurate test method for the tensile force of external prestressed tendons. Background technique [0002] External prestressing technique is a commonly used reinforcement method for girder bridges. The tensile force of external prestressed tendons is an important indicator of the effect of external prestressed reinforcement of this type of bridge. In the reinforcement acceptance, inspection and evaluation of this type of bridge, it is necessary to test the tensile force of external prestressed tendons. However, in the existing technical means, unless a pressure sensor is installed during construction, it is difficult to accurately measure the tensile force of the external prestressed tendons by other methods. The frequency method uses the deterministic relationship between the tension force and the vibration frequency of the tension cable t...
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IPC IPC(8): G01L5/04
Inventor 郝天之吴昌霞邱波罗月静梁茜雪李淑芬王伟芳陈文
Owner GUANGXI TRANSPORTATION SCI & TECH GRP CO LTD