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A spiral strain test device and method for extruded fiber-reinforced fabric tendons

A technology of fiber reinforcement and extrusion molding, applied in the field of embedded and implanted spiral resistance strain test devices, can solve the problems of test accuracy, mechanical damage of strain elements, and impact on strain measurement accuracy, so as to improve test stability, The effect of overcoming deformation asynchrony and improving test accuracy

Active Publication Date: 2021-02-02
XI'AN UNIVERSITY OF ARCHITECTURE AND TECHNOLOGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the most mature and widely used steel string strain gages in the monitoring of traditional reinforced concrete and prestressed concrete structures rely on a large number of welded connections in the layout method, which is helpless for typical inorganic non-metallic materials such as fiber-reinforced fabric FRP bars. Another type of surface-attached strain testing technology can be selected for strain testing of FRP tendons
[0003] As a result, a series of "bottleneck" problems that restrict the test accuracy of surface-attached strain testing technology are derived, which are mainly reflected in the following aspects: (1) Attached strain elements (strain gauges, strain gauges) are laid on the surface of FRP ribs, and the After the concrete is vibrated, it will cause mechanical damage to the strain element, and in the follow-up long-term monitoring period, the working environment such as temperature and humidity will have a greater impact on the test accuracy; (2), the core of the traditional resistive strain element Part of it is a sensitive grid, and the resistance wire is coiled back and forth on the sensitive grid. There are many straight line segments and semi-circular arc segments. It will affect the accuracy of strain measurement; (3), in engineering practice, it is found that for beams and column members deformed under the combined stress state of compression bending or tension bending, the traditional test method even for the same measurement area, on the FRP tendon, The strain test elements arranged on the lower edge show large differences in values. The reason is that the radial effect (stress and deformation) has a significant impact on the axial strain, and for FRP tendons with larger diameters, this The more significant the effect

Method used

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  • A spiral strain test device and method for extruded fiber-reinforced fabric tendons
  • A spiral strain test device and method for extruded fiber-reinforced fabric tendons
  • A spiral strain test device and method for extruded fiber-reinforced fabric tendons

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0064] Such as Figure 5 As shown, the lead-out test terminal 5 is connected to the Wheatstone bridge through a wire, and is integrated in the strain tester 2 for 1 / 4 bridge test.

[0065] Let the bridge R1 be a resistance wire resistor, and the other three are precision resistors. After the FRP tendon arranged on the lower edge of the beam body is stretched and deformed, the change of the corresponding electrical signal is reflected in the voltage drop as follows:

[0066]

[0067] Based on formula (13), the corresponding strain ε can be output and recorded by the terminal 3 of the data acquisition system through signal conversion 1 , which is the real-time axial strain value of the FRP tendon.

Embodiment 2

[0069] Such as Figure 6 As shown, the lead-out test terminal 5 is connected to the Wheatstone bridge through a wire, and is integrated in the strain tester 2 for the half-bridge mode-I test.

[0070] Keep the length of the two spiral resistance strain wires arranged on the measuring area the same, make the bridge R1 the resistance wire resistance one, the bridge R3 the resistance wire resistance two, and the other two precision resistances. After the FRP tendon arranged on the lower edge of the beam body is stretched and deformed, the change of the corresponding electrical signal is reflected in the voltage drop as follows:

[0071]

[0072] Based on formula (14), the corresponding strain ε can be output and recorded by the terminal 3 of the data acquisition system through signal conversion 1 , under the half-bridge mode-Ⅰ test, the voltage is increased to 2 times that of the 1 / 4 bridge test, and the actual axial strain of the FRP tendon is 0.5 times the output strain.

Embodiment 3

[0074] Such as Figure 6 As shown, the lead-out test terminal 5 is connected to the Wheatstone bridge through wires, and integrated in the strain tester 2 for half-bridge mode-II testing.

[0075] Keep the length of the two spiral resistance strain wires arranged on the measurement area the same, make the bridge R1 the resistance wire resistance one, the bridge R2 the resistance wire resistance two, and the other two precision resistances. If the strain of the resistance wire resistance 2 changes ε t is caused only by temperature, that is, ε 2 =ε t , the change of the corresponding electrical signal is reflected in the voltage drop as:

[0076]

[0077] Input the obtained voltage drop into the resistance strain gauge to measure the strain ε 1 . Under the test of this method, the corresponding strain ε can be output and recorded by the terminal 3 of the data acquisition system through signal conversion based on formula (15) 1 , this half-bridge mode-Ⅱ test can effectiv...

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PUM

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Abstract

The invention discloses a spiral resistance strain testing device and method for extruding fiber reinforced fabric (FRP) bars, belonging to the field of experimental mechanics measurement of architecture and civil engineering. The test device includes a spiral resistance strain wire, a resistance strain tester, and a data acquisition system. In the present invention, the helical resistance strain wire that matches the geometric topology of the surface of the FRP reinforcement is embedded, and the longitudinal direction of the pre-embedded FRP reinforcement in the beam and column structures under typical composite stress states such as compression bending or tension bending is implemented. The strain test can effectively eliminate the interference of the bending radial effect (deformation and stress) on the longitudinal strain target test results, and can continuously monitor the strain of the extruded FRP bars with higher precision, so as to know the effective prestress of the FRP bars in real time. Working conditions, provide basic data for accurate assessment of structural prestress loss. Compared with the traditional testing device, the present invention has the advantages of simple structure, convenient operation, strong environmental adaptability, and not easy to be damaged during on-site installation.

Description

technical field [0001] The invention belongs to the technical field of mechanical measurement of bridge engineering experiments, is suitable for strain testing of extruded fiber reinforced fabric (FRP) tendons, and relates to an embedded and implanted spiral resistance strain testing device and method. Background technique [0002] At present, concrete structures using extruded fiber-reinforced fabric (FRP) tendons are more and more widely used in civil engineering and construction engineering. Strain (stress) monitoring and identification is a key link related to the overall structural safety and objective evaluation of performance, especially in the practice of health monitoring and operation and maintenance of long-span bridge engineering. However, the most mature and widely used steel string strain gages in the monitoring of traditional reinforced concrete and prestressed concrete structures rely on a large number of welded connections in the layout method, which is help...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01B7/16
CPCG01B7/18
Inventor 郭琦冯磊张恒健吴梦
Owner XI'AN UNIVERSITY OF ARCHITECTURE AND TECHNOLOGY