Steel strand residual stress detection device

Abstract

The utility model discloses a device for detecting residual stress of a steel strand in the technical field of bridge detection, which aims to solve the problem that the loss condition of prestress of the steel strand is difficult to accurately evaluate in the prior art and comprises a clamping unit, a steel frame main body and a signal acquisition system, the clamping unit is arranged at the top end of the steel frame main body and is used for clamping a steel strand; the steel frame main body comprises a tension bar; the tension bar is a detachable screw, the reaction frame comprises a bottom plate and two symmetrical supporting arms, and the two symmetrical side plates are connected with the upper portion of the bottom plate at the same time. A ball bearing and a propelling nut below the counter-force frame are sequentially sleeved on the tension bar through threads; the signal acquisition system comprises tension sensors, and the tension sensors are arranged in the two side plates of the reaction frame and connected with the tension bar through threaded holes in the two ends. The device is simple in structure principle, low in cost and convenient to maintain, can be suitable for detecting the residual stress of the typical steel strand in a highway bridge, and has a wide application prospect.

Description

Technical Field

[0001] The utility model relates to a steel strand residual stress detection device, belonging to the technical field of bridge detection. Background Art

[0002] The main stress measurement methods for prestressed steel strands include strain gauge bonding, anchor pressure sensor detection, strand sensor detection, magnetic flux detection, fiber Bragg grating detection, and ultrasonic guided wave detection. However, for prestressed steel strands in existing bridges, which are embedded in concrete, most do not have stress sensors installed during construction, requiring external measurement methods to measure residual stress. Furthermore, methods such as magnetic flux detection and ultrasonic guided wave detection, which are suitable for measuring cable stress, are difficult to implement due to limitations in space and interfaces. Considering that the residual stress of prestressed steel strands is crucial to the safety of bridge structures, developing a suitable residual stress detection method for prestressed steel strands is crucial for bridge engineering.

[0003] Based on the basic principle that there is a linear relationship between the axial stress and the lateral stiffness of a steel strand, the utility model proposes a steel strand residual stress detection device with a simple structural principle, low cost, and easy maintenance. It is suitable for residual stress detection of typical steel strands in highway bridges and has broad application prospects. Utility Model Content

[0004] The technical problem to be solved by the utility model is that the existing residual prestress detection environment for detecting bridge steel strands is complex and it is impossible to accurately use sensors to collect the prestress data of the steel strands.

[0005] In order to solve the above technical problems, the utility model proposes a steel strand residual stress detection device, which is characterized by comprising a clamping unit, a steel frame body and a signal acquisition system;

[0006] The clamping unit is provided at the top of the steel frame body and is used to clamp the steel strand;

[0007] The steel frame body includes a tension rod; the tension rod is a screw rod; the reaction frame includes a base plate, two symmetrical support arms and two symmetrical side plates are simultaneously connected to the upper part of the base plate, and the tension rod passes through a threaded hole on the base plate; below the reaction frame, a ball bearing and a push nut are sequentially threadedly sleeved on the tension rod;

[0008] The signal acquisition system includes a tension sensor, which is placed inside the two side plates of the reaction frame and is connected to the tension rod through threaded holes at both ends.

[0009] Furthermore, the clamping unit includes a wire grabber, which is connected to the tension rod and hooks the steel strand.

[0010] Furthermore, the signal acquisition system also includes a laser displacement sensor arranged on the outside of a side plate, a sleeve is provided on the tension rod, a laser baffle is fixedly provided horizontally on the outside of the sleeve, and the sleeve is located between the wire catcher and the tension sensor.

[0011] Furthermore, the top ends of the two support arms of the reaction frame are respectively provided with steel strand limiters, and the steel strand limiters are in contact with the steel strands.

[0012] Furthermore, it also includes a data acquisition and analysis instrument. The laser displacement sensor is connected to the laser baffle. The data measured by the tension sensor and the laser displacement sensor are stored in the data acquisition and analysis instrument. The data acquisition and analysis instrument and the laser displacement sensor are fixed to the two side panels respectively by screws.

[0013] Furthermore, the width and thickness of the thread grabber are set to 1 cm.

[0014] Furthermore, the height of the steel strand limiter should be greater than the height of the concrete protective layer, and a U-shaped groove is provided at the end of the limiter with a groove depth of 2 cm.

[0015] Furthermore, the tension sensor is a resistive force sensor, which is used to monitor the changes in the tension of the steel strand in real time.

[0016] Furthermore, the laser baffle covers the laser reflecting surface of the laser displacement sensor.

[0017] Furthermore, the laser displacement sensor has an accuracy of micrometer or nanometer level.

[0018] The beneficial effects achieved by the utility model are as follows: the utility model proposes a steel strand residual stress detection device, which has a simple structural principle. The tension sensor is placed inside the two side plates of the reaction frame and is connected to the tension rod through a threaded hole. It can accurately collect data, and has low cost and easy maintenance. It is suitable for typical steel strand residual stress detection in highway bridges and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the front main structure of a steel strand residual stress detection device provided according to an embodiment of the present utility model;

[0020] Figure 2 This is a schematic diagram of the rear main structure of a steel strand residual stress detection device provided according to an embodiment of the utility model;

[0021] Figure 3 This is a side view of the device of Example 1 of the present utility model;

[0022] Figure 4 This is a schematic diagram of the positions of the tension sensor and the reaction frame of Example 1 of the present utility model.

[0023] Figure 5 This is a schematic diagram of a thread catcher according to Example 2 of the present utility model;

[0024] Figure 6 Schematic diagram of the vertical portion of the reaction frame end and the steel strand limiter of Example 2 of the present utility model;

[0025] Figure 7 This is a schematic diagram of a steel strand residual stress detection device according to embodiment 2 of the present utility model applied to a prestressed steel strand;

[0026] Figure numerals: 1. reaction frame; 2. tension rod; 3. wire grabber; 4. laser baffle; 5. propulsion nut; 6. ball bearing; 7. steel strand limiter; 8. tension sensor; 9. laser displacement sensor; 10. data acquisition and analysis instrument; 11. steel strand. DETAILED DESCRIPTION

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0028] Example 1

[0029] like Figure 1 As shown, this embodiment provides a steel strand residual stress detection device, comprising a clamping unit, a steel frame body, and a signal acquisition system; the clamping unit is provided at the top of the steel frame body for clamping the steel strand; the steel frame body comprises a tension rod 2; the tension rod 2 is a detachable screw rod; the reaction frame 1 comprises a bottom plate, two symmetrical support arms, and two symmetrical side plates connected to the upper portion of the bottom plate; below the reaction frame 1, a ball bearing 6 and a push nut 5 are sequentially threadedly sleeved on the tension rod 2;

[0030] The signal acquisition system includes a laser displacement sensor 9 arranged on the outside of a side panel, a sleeve is arranged on the tension rod 2, between the wire catcher 3 and the tension sensor 8, and a laser baffle 4 is arranged horizontally on the outside of the sleeve. Figure 4As shown, the tension sensor 8 is placed inside the two side plates of the reaction frame 1 and connected to the tension rod 2 through threaded holes at each end. The wire grabber 3 is connected to the tension sensor 8 via a screw and a threaded sleeve. A laser baffle 4 is located between the sleeve and the wire grabber 3. The wire grabber 3 grasps the steel strand 11, ensuring that the tension is effectively applied to the strand 11. The tension sensor 8 is connected to the signal acquisition system via a data cable or wireless transmission to transmit the tension signal. During use, tension is applied to the tension rod 2 via a hydraulic jack or other loading device. This tension is transmitted through the tension sensor 8 to the wire grabber 3, ultimately acting on the steel strand 11. The tension sensor 8 measures the tension in real time and transmits the data to the signal acquisition system. Simultaneously, the laser displacement sensor 9 measures the displacement of the steel strand 11, collecting displacement data of the steel strand 11 under tension. The signal acquisition system records the changes in tension, displacement, and other data over time. After unloading, the strain or stress recovery of the steel strand 11 is observed. Due to the elastic recovery properties of the material, part of the stress will be recovered, and the remaining part is the residual stress.

[0031] like Figure 2 and Figure 3 As shown, the laser displacement sensor 9 and the data acquisition and analysis instrument 10 are fixed to the two side panels respectively by screws, and all the data measured by the sensors are stored in the data acquisition and analysis instrument 10. The signal acquisition system connects the tension sensor 8 and the laser displacement sensor 9 through a data cable or wireless transmission to collect force and displacement data. During the detection, the tension sensor 8 measures the magnitude of the tension applied to the steel strand 11 in real time and transmits the tension data to the data acquisition and analysis instrument 10. At the same time, the laser displacement sensor 9 accurately measures the displacement change of the steel strand 11 under the action of tension, and also transmits the displacement data to the data acquisition and analysis instrument 10. The data acquisition and analysis instrument 10 receives and synchronously processes these two sets of data, and analyzes the residual stress of the steel strand 11 through data fitting. By continuously changing the magnitude of the tension and repeating the above measurement and calculation process, the mechanical performance parameters of the steel strand 11 under different tension levels can be obtained, thereby more comprehensively understanding the residual stress distribution of the steel strand 11.

[0032] Example 2

[0033] like Figure 5-Figure 7As shown, the clamping unit includes a wire grabber 3, a steel strand stopper 7, and a steel strand 11. The wire grabber 3 is connected to the tension rod 2 and hooks onto the steel strand 11. A sleeve is provided on the tension rod 2, between the wire grabber 3 and the tension sensor 8. A laser baffle 4 is horizontally positioned outside the sleeve. The baffle should be large enough to reflect the laser light from the laser displacement sensor 9, and its diameter is generally not less than 10 cm. The thickness of the wire grabber 3 should not be too large to accommodate practical applications: both the width and thickness are 1 cm. The main function of the wire grabber 3 is to firmly grasp the steel strand 11, ensuring effective force transmission between the steel strand 11 and the testing equipment during testing. When tension is applied, the wire grabber 3 evenly transfers the tension to the steel strand 11, subjecting the steel strand 11 to axial tension. The diagonal brace ends of the reaction frame 1 have a vertical height of 10 cm. The tops of the two support arms of the reaction frame 1 are each equipped with a steel strand stopper 7, and the groove depth is 2 cm. When the wire grabber 3 applies axial tension to the steel strand 11, the strand stopper 7 constrains the sides or periphery of the strand 11, limiting its tensile deformation to the axial direction. This ensures that measuring equipment, such as the laser displacement sensor 9, can accurately measure the axial displacement of the steel strand 11 and thus accurately calculate residual stress. The strand stopper 7 also helps protect the steel strand 11 from accidental collisions or damage during testing.

[0034] A laser baffle 4 is provided between the wire grabber 3 and the tension sensor 8 for reflecting the laser. The laser displacement sensor 9 is fixed to the reaction frame 1 by screws, and measures the displacement change of the steel strand 11 under tension by emitting and receiving laser beams, and works in conjunction with the laser baffle 4; the laser beam emitted by the laser displacement sensor 9 is irradiated on the laser baffle 4, and when the steel strand 11 is displaced under tension, the laser baffle 4 will also move accordingly. The laser displacement sensor 9 receives the reflected light and calculates the displacement of the steel strand 11 based on the position change of the reflected light. Since the laser displacement sensor 9 has high precision, it can accurately measure tiny displacement changes of the steel strand 11. During the entire loading process, the laser displacement sensor 9 continuously measures the displacement data, and synchronously records these data and the tension data transmitted by the tension sensor 8 in the signal acquisition system.

[0035] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent replacements for some of the technical features therein. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A steel strand residual stress detection device, characterized in that: It includes a clamping unit, a steel frame body and a signal acquisition system; The clamping unit is arranged at the top end of the steel frame body and is used to clamp the steel strand (11); The steel frame body includes a tension rod (2); the tension rod (2) is a screw rod, the reaction frame (1) includes a base plate, two symmetrical support arms and two symmetrical side plates are simultaneously connected to the upper part of the base plate, and the tension rod (2) passes through the threaded hole on the base plate; below the reaction frame (1), the ball bearing (6) and the push nut (5) are sequentially threadedly sleeved on the tension rod (2); The signal acquisition system comprises a tension sensor (8), which is placed inside the two side plates of the reaction frame (1) and connected to the tension rod (2) through threaded holes at both ends.

2. The steel strand residual stress detection device according to claim 1, characterized in that: The clamping unit comprises a wire grabber (3), which is connected to the tension rod (2) and hooks the steel strand (11).

3. The steel strand residual stress detection device according to claim 1, characterized in that: The signal acquisition system further comprises a laser displacement sensor (9) arranged on the outside of a side plate, a sleeve is provided on the tension rod (2), a laser baffle (4) is fixedly provided horizontally on the outside of the sleeve, and the sleeve is located between the wire catcher (3) and the tension sensor (8).

4. The steel strand residual stress detection device according to claim 1, characterized in that: The top ends of the two support arms of the reaction frame (1) are respectively provided with steel strand limiters (7), and the steel strand limiters (7) are in contact with the steel strands (11).

5. The steel strand residual stress detection device according to claim 3, characterized in that: It also includes a data acquisition analyzer (10), the laser displacement sensor (9) is connected to the laser baffle (4), the data measured by the tension sensor (8) and the laser displacement sensor (9) are stored in the data acquisition analyzer (10), and the data acquisition analyzer (10) and the laser displacement sensor (9) are respectively fixed to the two side plates by screws.

6. The steel strand residual stress detection device according to claim 3, characterized in that: The width and thickness of the thread catcher (3) are set to 1 cm.

7. The steel strand residual stress detection device according to claim 4, characterized in that: The height of the steel strand stopper (7) is greater than the height of the concrete protective layer, and a U-shaped groove is provided at the end of the steel strand stopper (7), and the groove depth is 2 cm.

8. The steel strand residual stress detection device according to claim 1, characterized in that: The tension sensor (8) is a resistive force sensor, used for monitoring the change of the tension of the steel strand in real time.

9. The steel strand residual stress detection device according to claim 3, characterized in that: The laser baffle (4) covers the laser reflection surface of the laser displacement sensor (9).

10. The steel strand residual stress detection device according to claim 5, characterized in that: The laser displacement sensor (9) has an accuracy of micrometer or nanometer level.

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