A prestressed steel wire corrosion test device under tensile stress state and an operating method thereof

Abstract

This invention discloses a corrosion testing device and operating method for prestressed steel wire under tensile stress. The device includes a pair of partially grooved box girders, fixed by a support device. A pair of fixed box girders and a sliding box girder are installed between the two box girders. A corrosion testing device is provided between the fixed box girders, and a stress-relieving device is provided between the sliding box girders and one side of the fixed box girders. The prestressed steel wire passes through the sliding box girders, the pair of fixed box girders, and the stress-relieving device, and is fixed by anchors. This invention reduces prestress loss after tensioning, ensuring the prestressed steel wire maintains its stress state. Furthermore, it allows for easier unloading of the prestressed steel wire after the corrosion test, and the stress-relieving device can be recycled.

Description

Technical Field

[0001] This invention relates to the field of corrosion testing technology, specifically to a corrosion testing device and operating method for prestressed steel wire under tensile stress. Background Technology

[0002] Prestressed steel wires are the main load-bearing components in prestressed concrete structures, and their health directly affects the durability and safety of the structure. However, during service, prestressed steel wires are highly susceptible to corrosion from water, air, and corrosive media, leading to a rapid degradation of their mechanical properties and ultimately, breakage. This can prevent the structure from meeting its normal service life and even cause major safety accidents. Therefore, it is necessary to study the degradation law of the mechanical properties of prestressed steel wires after corrosion. However, current experimental equipment lacks the facilities and methods for conducting corrosion tests on prestressed steel wires under tensile stress, which hinders such research. Summary of the Invention

[0003] The purpose of this invention is to provide a corrosion testing device and operating method for prestressed steel wire under tensile stress, used for conducting corrosion tests on prestressed steel wire under tensile stress. On the one hand, it can reduce the prestress loss of the prestressed steel wire after tensioning, ensuring its stress state; on the other hand, it allows for easier unloading of the prestressed steel wire after the corrosion test, and the unloading device can be recycled.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a prestressed steel wire corrosion testing device under tensile stress, comprising a pair of partially grooved box girders, the pair of partially grooved box girders being fixed by a support device, a pair of fixed box girders and a sliding box girder being installed between the pair of partially grooved box girders, a corrosion device being provided between the pair of fixed box girders, a stress-relieving device being provided between the sliding box girders and one side of the fixed box girders, and the prestressed steel wire passing through the sliding box girders, the pair of fixed box girders and the stress-relieving device, and being fixed by an anchor.

[0005] Compared with the prior art, the beneficial effects of the present invention are:

[0006] 1. The device and test method of this invention can be used to conduct corrosion tests on prestressed steel wires under tensile stress, providing conditions for quantitatively studying the mechanical properties of prestressed steel wires after corrosion.

[0007] 2. By setting up a stress-relieving device, the prestressed steel wire can be unloaded after the corrosion test is completed, which is more convenient, and the stress-relieving device can be recycled.

[0008] 3. The unloading device in this invention also has the function of holding the load, which can reduce the prestress loss of the prestressed steel wire after tensioning and ensure its stress state. Attached Figure Description

[0009] Figure 1 This is a three-dimensional structural view of the test apparatus of the present invention.

[0010] Figure 2 This is a schematic diagram of the sliding box girder of the present invention.

[0011] Figure 3 This is a schematic diagram of the force-relieving device of the present invention.

[0012] Figure 4 This is an exploded view of the force-relieving device of the present invention.

[0013] Figure 5 This is a schematic diagram of the cage mechanism of the present invention.

[0014] Figure 6 This is a schematic diagram of the corrosion device of the present invention.

[0015] 1. Support device; 1-1. Support box girder; 1-2. Flange jack; 2. Box girder with partial grooving; 3. Sliding box girder; 3-1. Sliding steel plate; 4. Fixed box girder; 5. Prestressed steel wire; 6. Anchorage; 7. Unloading device; 7-1. Cage mechanism; 7-1-1. First longitudinal cage; 7-1-2. Steel plate with bolt holes; 7-1-3. Spring clip groove; 7-2. Hollow steel pipe; 7-2-1. Second longitudinal cage; 7-2-2. Transverse round steel pipe; 7-3. Rotating retainer; 7-4. Ball bearing; 7-5. Spring clip; 8. Template; 9. Corrosion device; 9-1. Corrosion tank; 9-2. Cathode plate; 9-3. DC power supply; 9-4. Corrosion solution. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Please see Figure 1-6This invention provides a technical solution: a prestressed steel wire corrosion testing device under tensile stress, comprising a pair of partially grooved box beams 2, the pair of partially grooved box beams 2 being fixed by a support device 1, and a pair of fixed box beams 4 and sliding box beams 3 being installed between the pair of partially grooved box beams 2. The fixed box beams 4 are fixed to the partially grooved box beams 2 by bolts. The sliding box beams 3 are slidably connected to the inner side of the pair of partially grooved box beams 2 by sliding steel plates 3-1.

[0018] The support device 1 includes a pair of support box beams 1-1 and flange-type jacks 1-2. The pair of partially grooved box beams 2 are mounted on the pair of support box beams 1-1, and both support box beams 1-1 are fixed to the ground by the flange-type jacks 1-2. The flange-type jacks 1-2 are installed at the four corners to facilitate overall adjustment of the height of the partially grooved box beams 2.

[0019] A corrosion device 9 is installed between the pair of fixed box girders 4, and the corrosion device 9 is also installed on the ground via flange-type jacks 1-2. A stress-relieving device 7 is installed between the sliding box girder 3 and one side of the fixed box girder 4. The prestressed steel wire 5 passes through the sliding box girder 3, the pair of fixed box girders 4, and the stress-relieving device 7, and is fixed by an anchor 6. Because the prestressed steel wire 5 is too thin, ordinary anchors cannot hold it, so the anchor 6 uses the same structure as in patent CN104453100B.

[0020] The corrosion device 9 includes an corrosion tank 9-1 and a DC power supply 9-3. The prestressed steel wire 5 is arranged above the corrosion tank 9-1, and the corrosion tank 9-1 is filled with a corrosion liquid 9-4. A cathode plate 9-2 is provided in the corrosion tank 9-1. The positive terminal of the DC power supply 9-3 is connected to a copper wire drawn from the prestressed steel wire 5, and the negative terminal of the DC power supply 9-3 is connected to the cathode plate 9-2.

[0021] The stress-relieving device 7 includes a retainer mechanism 7-1 and a hollow steel tube 7-2, both machined from Q235A round steel. The retainer mechanism 7-1 and the hollow steel tube 7-2 are rotatably connected by a rotating retainer ring 7-3 to ensure that the hollow steel tube 7-2 can rotate freely when the retainer mechanism 7-1 is fixed on the sliding box girder 3. The rotating retainer ring 7-3 is provided with a ball bearing groove, and the balls 7-4 are installed in the ball bearing groove.

[0022] The retainer mechanism 7-1 is mounted on the sliding box girder 3; the hollow steel pipe 7-2 is provided with external threads, and the fixed box girder 4 is provided with threaded holes, with the external threads screwed into the threaded holes. The outer side wall of the transverse circular steel pipe 7-2-2 is provided with an outer prism.

[0023] The retainer mechanism 7-1 includes a first longitudinal retainer 7-1-1 and a steel plate 7-1-2 with bolt holes. The steel plate 7-1-2 with bolt holes is installed on the sliding box beam 3, and the first longitudinal retainer 7-1-1 and the steel plate 7-1-2 with bolt holes are integrally formed.

[0024] The hollow steel tube 7-2 includes a second longitudinal retainer 7-2-1 and a transverse round steel tube 7-2-2. The external thread is formed on the transverse round steel tube 7-2-2, and the second longitudinal retainer 7-2-1 and the transverse round steel tube 7-2-2 are integrally formed. The contact surfaces of the first longitudinal retainer 7-1-1 and the second longitudinal retainer 7-2-1 with the rotating retainer 7-3 are provided with rotating retainer grooves. The rotating retainer 7-3, equipped with balls 7-4, is movably engaged in the rotating retainer groove. Simultaneously, the inner diameter of the transverse round steel tube 7-2-2 should not be less than 20mm to allow the PVC conduit fitted onto the uncorroded section of the prestressed steel wire 5 to pass through. Furthermore, the length of the external thread on the transverse round steel tube 7-2-2 must be no less than 2 / 3 of the length of the transverse round steel tube 7-2-2, and must be significantly greater than the tension of the prestressed steel wire 5.

[0025] The first longitudinal retainer 7-1-1 has a spring clip slot 7-1-3, one side of which is engaged with a spring clip 7-5. The other side of the spring clip 7-5 is engaged with the outer wall of the second longitudinal retainer 7-2-1. The specific installation method is as follows... Figure 3 and 4 As shown, the rotating retainer 7-3 with ball bearings 7-4 is used to prevent it from falling off.

[0026] The prestressed steel wire 5 is provided with a template 8, which is placed inside the corrosion tank 9-1. The template 8 is used to pour concrete for subsequent corrosion testing. The distance from the lower edge of the circular hole in the template 8 to the lower edge of the template 8 must be between 40mm and 50mm. After demolding, the concrete in the template 8 should be submerged in the corrosive liquid to a height of not less than 20mm.

[0027] This invention also provides an operating method for a prestressed steel wire corrosion testing device under tensile stress:

[0028] S01: The cutting length of the prestressed steel wire 5 is calculated based on the reserved length of the prestressed steel wire 5 at the tensioning end and the anchoring end; the end closest to the sliding box girder 3 is the tensioning end, and the other end is the anchoring end;

[0029] S02: Starting from the anchor end, mark the length of the corrosion zone of the prestressed steel wire 5. Then, completely remove the passivation film from this marked section with sandpaper. Finally, spot weld a wire with a cross-sectional area of ​​approximately 1 mm² onto the prestressed steel wire 5 after removing the passivation film. 2The copper conductors are not less than the spacing between a pair of fixed box girders 4. The copper conductors and prestressed steel wires 5 are tied and fixed at a distance of 20mm from the weld point, and then fixed with plastic binding wire every 200mm along the tensioning end direction. PVC conduits are installed outside the corrosion zone.

[0030] S03: Install the stress relief device 7, insert the prestressed steel wire 5, install the anchor 6 at the same time, and then tension the prestressed steel wire 5; the tensioning method is existing technology and has been described in patent CN104453100B, so it will not be repeated here.

[0031] S04: After the prestressed steel wire 5 is tensioned, concrete is poured inside the formwork 8. When the concrete strength is sufficient to ensure that its surface and edges will not be damaged due to demolding, the formwork 8 is removed and water is sprinkled for curing.

[0032] S05: Place a cathode plate 9-2 at the bottom of the corrosion tank 9-1, and inject a 3-5% NaCl solution into the corrosion tank 9-1. Lift the corrosion tank 9-1 using a flange-type jack 1-2, ensuring there is a gap between the edge of the corrosion tank 9-1 and the prestressed steel wire 5, so that the corrosion tank 9-1 does not contact the prestressed steel wire 5, preventing the corrosion tank 9-1 from sharing the charge upon contact. The concrete should be submerged in the corrosion solution to a height of not less than 20mm.

[0033] S06: After the corrosion test is completed, the prestressed steel wire 5 is released. First, according to the thread direction of the hollow steel pipe 7-2 and the fixed box girder 4, the outer prism on the transverse round steel pipe 7-2-2 is rotated with a wrench, which in turn drives the sliding box girder 3 to slide towards the anchor end. After the prestressed steel wire 5 is completely relaxed, the anchor 6 is removed, and then the concrete in the corrosion area of ​​the prestressed steel wire 5 is broken to remove the prestressed steel wire 5 after corrosion.

Claims

1. A corrosion testing device for prestressed steel wire under tensile stress, characterized in that: It includes a pair of partially grooved box girders (2), which are fixed by a support device (1). A pair of fixed box girders (4) and a sliding box girder (3) are installed between the pair of partially grooved box girders (2). A corrosion device (9) is provided between the pair of fixed box girders (4). A stress relief device (7) is provided between the sliding box girder (3) and one side of the fixed box girder (4). Anchors (6) are installed on the sliding box girder (3). The prestressed steel wire (5) passes through the sliding box girder (3), the pair of fixed box girders (4) and the stress relief device (7), and is fixed by the anchors (6). The unloading device (7) includes a retainer mechanism (7-1) and a hollow steel pipe (7-2). The retainer mechanism (7-1) and the hollow steel pipe (7-2) are rotatably connected by a rotating retainer (7-3). The retainer mechanism (7-1) is installed on the sliding box beam (3). The hollow steel pipe (7-2) is provided with external threads, and the fixed box beam (4) is provided with threaded holes, and the external threads are screwed into the threaded holes. The retainer mechanism (7-1) includes a first longitudinal retainer (7-1-1) and a steel plate with bolt holes (7-1-2). The steel plate with bolt holes (7-1-2) is installed on the sliding box beam (3), and the first longitudinal retainer (7-1-1) and the steel plate with bolt holes (7-1-2) are integrally formed. The hollow steel tube (7-2) includes a second longitudinal retainer (7-2-1) and a transverse round steel tube (7-2-2). The external thread is formed on the transverse round steel tube (7-2-2), and the second longitudinal retainer (7-2-1) and the transverse round steel tube (7-2-2) are integrally formed. The first longitudinal retainer (7-1-1) has a spring clip slot (7-1-3), one side of which is engaged with a spring clip (7-5), and the other side of the spring clip (7-5) is engaged with the outer wall of the second longitudinal retainer (7-2-1).

2. The corrosion testing device for prestressed steel wire under tensile stress state according to claim 1, characterized in that: The support device (1) includes a pair of support box beams (1-1) and flange jacks (1-2). The pair of partially grooved box beams (2) are installed on the pair of support box beams (1-1), and the pair of support box beams (1-1) are fixed to the ground by flange jacks (1-2).

3. The corrosion testing apparatus for prestressed steel wire under tensile stress state according to claim 1, characterized in that: The sliding box girder (3) is slidably connected to the inner side of a pair of partially grooved box girders (2) via a sliding steel plate (3-1).

4. The corrosion testing apparatus for prestressed steel wire under tensile stress state according to claim 1, characterized in that: The corrosion device (9) includes a corrosion tank (9-1) and a DC power supply (9-3). The prestressed steel wire (5) is placed above the corrosion tank (9-1), and the corrosion tank (9-1) is filled with a corrosion liquid (9-4). A cathode plate (9-2) is provided in the corrosion tank (9-1). The positive terminal of the DC power supply (9-3) is connected to a copper wire drawn from the prestressed steel wire (5), and the negative terminal of the DC power supply (9-3) is connected to the cathode plate (9-2).

5. The corrosion testing apparatus for prestressed steel wire under tensile stress state according to claim 1, characterized in that: The rotating retaining ring (7-3) is equipped with ball bearings (7-4).

6. The corrosion testing apparatus for prestressed steel wire under tensile stress state according to claim 4, characterized in that: The prestressed steel wire (5) is provided with a template (8), and the template (8) is placed in the corrosion tank (9-1).

7. The corrosion testing apparatus for prestressed steel wire under tensile stress state according to claim 1, characterized in that: The outer wall of the transverse circular steel pipe (7-2-2) is provided with an outer prism.

8. An operating method for a prestressed steel wire corrosion testing device under tensile stress as described in claim 1, characterized in that: S01: Calculate the cutting length of the prestressed steel wire (5) based on the reserved length of the prestressed steel wire (5) at the tensioning end and the anchoring end; S02: Starting from the anchor end, mark the length of the corrosion zone of the prestressed steel wire (5), then completely remove the passivation film of this marked zone with sandpaper, and spot weld a wire with a cross-sectional area of ​​about 1 mm² onto the prestressed steel wire (5) after removing the passivation film. 2 The copper conductors are not less than the spacing between a pair of fixed box girders (4). The copper conductors and prestressed steel wires (5) are tied and fixed at a distance of 20mm from the weld point, and then fixed with plastic binding wire every 200mm along the tensioning end direction. PVC conduits are installed outside the corrosion zone. S03: Install the unloading device (7), insert the prestressed steel wire (5), install the anchor (6) at the same time, and then tension the prestressed steel wire (5); S04: After the prestressed steel wire (5) is tensioned, concrete is poured in the formwork (8). When the concrete strength is sufficient to ensure that its surface and edges are not damaged due to demolding, the formwork (8) is removed and water is sprinkled for curing. S05: Place a cathode plate (9-2) at the bottom of the corrosion tank (9-1), and inject 3~5% NaCl solution into the corrosion tank (9-1). Lift the corrosion tank (9-1) using a flange jack (1-2), and ensure that there is a gap between the edge of the corrosion tank (9-1) and the prestressed steel wire (5), and that the concrete is submerged in the corrosion solution to a height of not less than 20mm. S06: After the corrosion test is completed, the prestressed steel wire (5) is released. First, according to the thread direction of the hollow steel pipe (7-2) and the fixed box girder (4), the outer prism on the transverse round steel pipe (7-2-2) is rotated with a wrench, which then drives the sliding box girder (3) to slide towards the anchor end. After the prestressed steel wire (5) is completely relaxed, the anchor (6) is removed. Then, the concrete in the corrosion area of ​​the prestressed steel wire (5) is broken, and the prestressed steel wire (5) after corrosion is removed.

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