A device and method for testing local corrosion of a steel strand of a concrete T-beam

Abstract

The application discloses a kind of local corrosion test device of concrete T-shaped beam steel strand, including test beam, the test beam is post-tensioned prestressed concrete T-shaped beam, the lower triangle of test beam is opened with corrosion zone, corrosion groove is equipped in corrosion zone, and corrosion groove is installed in corrosion zone by fixing frame;The bellows are equipped in the test beam, and the steel strand is worn in the bellows.The device and test method of the application can pre-set the corrosion site and corrosion degree of steel strand, and provide conditions for quantitative study of the influence of steel strand local corrosion on prestressed concrete beam.The application uses several fixing frames to support corrosion groove, and researchers can flexibly select the length of corrosion section, which widens the research scope of corrosion section.

Description

Technical Field

[0001] This invention relates to the field of corrosion testing technology, specifically to a device and method for testing localized corrosion of steel strands in concrete T-beams. Background Technology

[0002] Prestressed concrete bridges located in coastal environments are susceptible to chloride ion corrosion, leading to localized corrosion of prestressing tendons. This localized corrosion causes premature failure of the components, preventing the structure from meeting its normal service life and resulting in significant economic losses and social impact. Previously, the adverse effects of prestressing tendon corrosion in bridge structures were insufficiently understood, resulting in many bridges requiring major repairs or demolition and reconstruction after only a short period of use, placing an unbearable economic burden on them, and even causing some to collapse. For large-scale cross-river and sea bridges with substantial investments, even extending their service life by just one year would have significant static economic and social benefits. Therefore, it is necessary to study the corrosion patterns of prestressing tendons under chloride ion or other liquid erosion that affects the durability of bridge structures. Currently, research on the durability of prestressed concrete beams lacks the equipment and methods for conducting localized corrosion tests on prestressed steel strands, hindering research progress. Summary of the Invention

[0003] The purpose of this invention is to provide a device and method for testing the localized corrosion of steel strands in concrete T-beams, for conducting localized corrosion tests on prestressed steel strands in a chloride salt environment.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a steel strand corrosion test device under tensile stress, comprising a test beam, wherein the test beam is a post-tensioned prestressed concrete T-beam, a simulated corrosion zone is formed at the lower triangle of the test beam, and the embedded corrugated pipes of the simulated corrosion steel strand are symmetrically arranged in the horseshoes on both sides below the lower triangle, and a corrosion groove is provided in the simulated corrosion zone, and the corrosion groove is installed in the simulated corrosion zone by a fixing frame.

[0005] The test beam is equipped with a corrugated pipe, and steel strands are threaded through the corrugated pipe;

[0006] The corrosion tank includes a vertical plate, and a solution storage cavity is provided on one side of the vertical plate;

[0007] The other side of the vertical plate is provided with a test beam corrosion chamber, and a sponge is provided inside the test beam corrosion chamber, with the sponge placed on the outside of the concrete.

[0008] A copper wire is welded to the section of the steel strand intended for corrosion. The copper wire is led out from the notch of the circular washer between the tensioning anchor of the corrugated pipe and the beam end of the test beam. The copper wire is connected to the positive terminal of the DC power supply, and the negative terminal of the DC power supply is connected to the thin steel plate on the inner wall of the vertical plate.

[0009] Compared with the prior art, the beneficial effects of the present invention are:

[0010] 1) The device and test method of the present invention can be used to pre-determine the corrosion location and degree of the steel strand, providing conditions for quantitatively studying the impact of local corrosion of steel strand on prestressed concrete beams.

[0011] 2) This invention uses several fixed frames to support the corrosion tank, allowing researchers to flexibly select the length of the corrosion section and broaden the research scope of the corrosion section.

[0012] 3) The use of intelligent power strips for cyclic timing replenishment of corrosion fluid into the corrosion chamber makes the replenishment of corrosion fluid more timely and accurate, and saves labor. Attached Figure Description

[0013] Figure 1 This is a three-dimensional structural view of the test apparatus of the present invention.

[0014] Figure 2 This is a schematic diagram of the corrosion tank mechanism of the present invention.

[0015] Figure 3 This is an exploded view of the corrosion tank of the present invention.

[0016] Figure 4 This is a schematic diagram of the tensioning end of the test device of the present invention.

[0017] Figure 5 This is a cross-sectional view of the top of the vertical plate of the present invention.

[0018] Figure 6 This is a front view of the test apparatus of the present invention.

[0019] Figure 7 This is a side cross-sectional view of the test apparatus of the present invention.

[0020] 1. Test beam; 2. Fixing frame; 2-1. Lead screw; 2-2. Steel plate; 2-3. Nut; 3. Corrosion tank; 4-1. Vertical plate; 4-2. Inclined plate; 4-3. Side plate; 4-4. Base plate; 4-5. Outer plate; 5. Sponge; 6. Water pump; 6-1. Conduit; 6-2. Smart power strip; 6-3. Check valve; 7. Solution storage tank; 8. DC power supply; 9. Stud; 10. Concrete; 11. Round washer; 12. Steel strand; 13. Copper wire; 14. Corrugated pipe; 15. Water injection hole. Detailed Implementation

[0021] 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.

[0022] Please see Figure 1-7 This invention provides a technical solution: a test device for localized corrosion of steel strands in a concrete T-beam, comprising a test beam 1, wherein the test beam 1 is a post-tensioned prestressed concrete T-beam, and its cross-sectional structure consists of flanges, a web, a lower triangle, and a horseshoe shape. A simulated corrosion zone is formed at the lower triangle of the test beam 1, and pre-embedded corrugated pipes for the simulated corrosion steel strands are symmetrically arranged within the horseshoe shapes on both sides below the lower triangle. A corrosion groove 3 is provided within the simulated corrosion zone, and the corrosion groove 3 is installed within the simulated corrosion zone via a fixing frame 2. The corrosion groove 3 is made of plexiglass.

[0023] The test beam 1 is equipped with a corrugated pipe 14, and steel strands 12 are threaded through the corrugated pipe 14.

[0024] The corrosion tank 3 includes a vertical plate 4-1, and a solution storage cavity is provided on one side of the vertical plate 4-1.

[0025] On the other side of the vertical plate 4-1, there is a test beam corrosion chamber, and a sponge 5 is placed inside the test beam corrosion chamber, with the sponge 5 positioned outside the concrete 10; the solution storage chamber is provided for continuously supplying liquid to the test beam corrosion chamber. Meanwhile, the top surface of the vertical plate 4-1 near the solution storage chamber is arc-shaped, and the top surface of the vertical plate 4-1 near the test beam corrosion chamber has a 45° inclination angle. Figure 5 As shown, this setup ensures that the solution in the solution storage chamber can flow more easily to the corrosion chamber of the test beam.

[0026] A copper wire 13 is welded to the section of the steel strand 12 that is to be corroded. The copper wire 13 is led out from the notch of the circular washer 11 set between the tensioning anchor of the corrugated pipe 14 and the beam end of the test beam 1. The copper wire 13 is connected to the positive terminal of the DC power supply 8 to avoid corrosion of the steel strand outside the section of the steel strand and the anchors at both ends of the beam when the guide wire is directly connected to the anode from the end of the steel strand 12. The negative terminal of the DC power supply 8 is connected to the thin steel plate on the inner wall of the vertical plate 4-1.

[0027] The fixing frame 2 includes a pair of steel plates 2-2 and a pair of studs 9 for fixing the upright plate 4-1. The pair of steel plates 2-2 are connected by a screw 2-1; and the pair of steel plates 2-2 are placed on both sides of the test beam 1.

[0028] The bottom surface of the stud 9 is smooth and flat, and its length should be greater than 1 / 2 of the difference between the flange width and the horseshoe width of the test beam 1. The stud 9 is used to hold the upright plate 4-1 to fix the corrosion tank.

[0029] The number of the proposed corrosion zone and the corrugated pipe 14 are both two, and the proposed corrosion zone and the corrugated pipe 14 are arranged symmetrically.

[0030] The solution storage chamber also includes a pair of side plates 4-3, a bottom plate 4-4, and an outer plate 4-5. The pair of side plates 4-3 are connected to the upright plate 4-1, the bottom plate 4-4, and the outer plate 4-5 by tenon and mortise.

[0031] The corrosion chamber of the test beam also includes an inclined plate 4-2, which is connected to the upright plate 4-1 by tenon and mortise and tenon joints, and the inclined plate 4-2 is in contact with the inner wall of the area to be corroded.

[0032] The outer plate 4-5 has a water injection hole 15, and the water injection hole 15 is connected to a water pump 6 through a conduit, and the water pump 6 is connected to a solution storage tank 7; a check valve 6-3 is provided on the conduit.

[0033] This invention also provides a test method for a test apparatus for localized corrosion of steel strands in concrete T-beams, including...

[0034] Step 1: Fabrication of Test Beam 1;

[0035] S01: Calculate the cutting length of a single steel strand 12 and corrugated pipe 14 based on the reinforcement curve of the steel strand 12 and the reserved lengths at the tensioning end and anchoring end; the tensioning end and anchoring end are respectively located at... Figure 1 The left and right ends of the test beam. Corrugated pipe 14 is a non-metallic flexible hose made of PE material.

[0036] S02: Starting from the anchoring end, calculate the length range of the steel strand 12 corresponding to the specified corrosion zone in the test beam 1, and mark it. Completely remove the passivation film of the steel strand 12 within this marked section using sandpaper. Apply a layer of epoxy resin to each end of the marked section, 200mm from each side. After the epoxy resin dries, spot weld a cross-sectional area of ​​approximately 1mm² onto the steel strand 12 after removing the passivation film. 2 The copper conductor 13 has a length not less than the cutting length of a single steel strand 12. The copper conductor 13 and the steel strand 12 are tied and fixed at a distance of 20mm from the welding point, and then fixed with plastic binding wire every 500mm along the tensioning end direction.

[0037] S03: Tie the reinforcing cage, fix the corrugated pipe 14 with the material cut on the control point of the curved reinforcement, then pass the steel strand 12 through the corrugated pipe 14 from the anchoring end, and control the reserved length of the steel strand 12 at the anchoring end. Lead the copper conductor 13 out from the corrugated pipe 14 at the tensioning end.

[0038] S04: Place the reinforcing cage into the test mold, and reserve a groove-shaped post-cast opening at the simulated corrosion zone of the lower triangle of test beam 1, so that the interface between the corrugated pipe 14 and the original lower triangle is directly exposed to the air without concrete coverage. Pour and cure the concrete, and then remove the formwork. After 28 days of curing, prepare to prestress test beam 1. Before tensioning, recheck the reserved length of the steel strand 12 at the anchorage end, and add the pre-slip length of the steel strand 12 at the anchorage end. Then install the fixed end anchorage. After the fixed-end anchor is installed, a notched circular washer 11 and the tensioning-end anchor are installed sequentially at the tensioning end. The notched circular washer 11 is about 10mm thick, its diameter is not less than the diameter of the tensioning-end anchor, and its elastic modulus should be greater than that of the tensioning-end anchor. The cross-sectional area at the notch is about 3 to 6 times the cross-sectional area of ​​the copper conductor. When installing the circular washer, the copper conductor 13 is led out from this notch. Then, the test beam 1 is prestressed. After the tensioning is completed, high-pressure grouting and curing are carried out.

[0039] S05: After curing, first roughen the surface of the concrete around the groove, then clean the surface with water and a blower. Next, remove the exposed corrugated pipe 14 at the groove post-pouring opening to expose the mortar inside the pipe. Then backfill with concrete 10 of a lower grade. After curing for 28 days, begin the corrosion test.

[0040] Step 2: Fabrication, installation, and commissioning of the corrosion apparatus;

[0041] A01: Construct corrosion tank 3;

[0042] Among them, the inclined plate 4-2, the pair of side plates 4-3 and the outer plate 4-5 are all provided with tenons, and the upright plate 4-1, the bottom plate 4-4 and the outer plate 4-5 are all provided with mortises to cooperate with the tenons; the top surface of the upright plate 4-1 is arc-shaped on the side near the solution storage cavity, and the top surface of the upright plate 4-1 is inclined at a 45° angle on the side near the corrosion cavity of the test beam.

[0043] A02: The inner diameter design of the inner guide tube and check valve in water injection hole 15, and water injection hole 15 is located at the bottom of outer plate 4-5;

[0044] From the formula Calculations show that In the formula, V is the flow rate; μ is the flow velocity, which can be determined according to the water pump 6; A is the cross-sectional area of ​​the pipe, and d is the inner diameter of the pipe;

[0045] A03: Assemble the groove body; connect the five pieces of acrylic glass that have been made above with mortise and tenon joints, then inject UV glue into the mortise and tenon joints and let it dry;

[0046] A04: Processing and manufacturing 2 fixing frames;

[0047] A05: Install the mounting bracket 2 and corrosion tank 3; The steel plate 2-2 has screw holes for threaded rods 2-1 and studs 9. Assemble each set of four pre-machined rods 2-1 and two steel plates 2-2 into a rectangle, and place it on the designated part of the test beam 1. Then tighten the nuts 2-3 at both ends of the rods 2-1, so that the two steel plates 2-2 are tightly against the two sides of the beam flange, and the four rods 2-1 are tightly against the top and bottom surfaces of the test beam 1. Apply silicone sealant to the inner surface of the lower part of the assembled vertical plate 4-1, and then align the lower tip of the inclined plate 4-2 with the lower triangle and horseshoe surface of the test beam 1 in the section to be corroded. At the boundary, the lower part of the vertical plate 4-1 is attached to the horseshoe surface of the section to be corroded in the test beam 1; after attachment, the vertical plate 4-1 is slightly adjusted up and down so that the inclined side of the inclined plate 4-2 is tightly attached to the lower triangular surface of the test beam 1; the length of the stud 9 is installed and adjusted, and the stud 9 is used to hold the vertical plate 4-1 to fix the corrosion tank 3. Finally, the gaps at the interfaces between each piece of plexiglass and concrete in the tank are filled tightly along the inner wall with glass glue to prevent water leakage from the tank body; then a thin steel plate is taken, cut to the size of the test beam corrosion cavity of the vertical plate 4-1, one side is covered with glass glue, and then it is attached to the test beam corrosion cavity of the vertical plate 4-1 to serve as the cathode;

[0048] A06: After the glass glue dries, fill the corrosion chamber of the test beam with a 3.5% NaCl solution and let it stand for 24 hours. Then, remove the solution. Next, fill the corrosion chamber of the test beam with PVA medical sponge 5. Before laying the sponge 5, it should be pre-soaked in a 3.5% NaCl solution until saturated.

[0049] A07: The solution storage tank 7 is filled with a 3.5% NaCl solution. One end of the water pump 6 is connected to the solution storage tank 7 via a conduit 6-1, and the other end is connected to the solution storage chamber via a conduit 6-1. The power supply of the water pump 6 is connected to the smart power strip 6-2. The corrosive solution is immersed into the sponge 5 through the arc surface and tilt angle on the vertical plate 4-1. Before the power supply of the water pump 6 is connected to the smart power strip 6-2, the evaporation rate of the corrosive solution must be calculated according to the Penman formula. Then, the flow rate of the corrosive solution that the water pump 6 needs to supply must be calculated based on the evaporation rate. Then, the time required to reach the required amount of water must be calculated based on the required flow rate and the pumping speed of the water pump 6. The time required to fill the solution storage chamber and the time required for the sponge to become saturated again must be calculated. Based on the calculated time, the smart power strip with a timer switch function is used for cyclic timing so that the water pump periodically replenishes the corrosive solution in the solution storage chamber to ensure that the sponge is always moist.

[0050] A08: Connect the copper wire 13 to the positive terminal of the power supply and the thin steel plate to the negative terminal of the power supply. Then, apply power to the designated area of ​​the steel strand 12 to rust. The current density and time are calculated according to Faraday's law.

[0051] A09: After powering on, turn off DC power supply 8. The local corrosion test is now complete.

Claims

1. A device for testing the local corrosion of steel strands of a concrete T-beam, characterized in that: The utility model relates to a test beam (1) for the corrosion test of prestressed concrete T beam, which comprises a test beam (1) for the corrosion test of prestressed concrete T beam, a corrosion groove (3) is arranged in the lower triangle of the test beam (1), and the corrosion groove (3) is installed in the corrosion test area through a fixing frame (2). The test beam (1) is provided with a bellows (14), and a steel strand (12) is arranged in the bellows (14). The corrosion groove (3) comprises a vertical plate (4-1), and one side of the vertical plate (4-1) is provided with a solution storage cavity. The solution storage cavity further comprises a pair of side plates (4-3), a bottom plate (4-4) and an outer plate (4-5), and the pair of side plates (4-3) are connected to the vertical plate (4-1), the bottom plate (4-4) and the outer plate (4-5) through mortise and tenon joints. The outer plate (4-5) is provided with a water injection hole (15), the water injection hole (15) is connected to a water pump (6) through a conduit, the water pump (6) is connected to a solution storage tank (7), a check valve (6-3) is arranged on the conduit, one end of the conduit (6-1) of the water pump (6) is connected to the solution storage tank (7), the other end of the conduit (6-1) is connected to the solution storage cavity, the power supply of the water pump (6) is connected to an intelligent socket (6-2), the corrosion liquid is immersed into a sponge (5) through the arc surface and the inclined angle of the vertical plate (4-1), before the power supply of the water pump (6) is connected to the intelligent socket (6-2), the evaporation amount of the corrosion liquid is calculated according to the Pengman formula, the flow of the corrosion liquid required by the water pump (6) is calculated according to the evaporation amount, the time required to reach the required water amount is calculated according to the required flow and the water pumping speed of the water pump (6), the time required to fill the solution storage cavity and the time required for the sponge to be saturated again are calculated, and the intelligent socket with the timing switch function is cyclically timed according to the calculated time, so that the water pump can periodically supplement the corrosion liquid into the solution storage cavity; the top surface of the vertical plate (4-1) is arc-shaped near the side of the solution storage cavity, and the top surface of the vertical plate (4-1) is inclined at an angle of 45° near the side of the test beam corrosion cavity. The other side of the vertical plate (4-1) is provided with a test beam corrosion cavity, and the test beam corrosion cavity is provided with a sponge (5), and the sponge (5) is arranged outside the concrete (10). A copper wire (13) is welded to the corrosion test area of the steel strand (12), the copper wire (13) is led out from the gap of a round gasket (11) arranged between the tensioning anchor of the bellows (14) and the beam end of the test beam (1), the copper wire (13) is connected to the positive electrode of a direct current power supply (8), and the negative electrode of the direct current power supply (8) is connected to the inner wall of the vertical plate (4-1).

2. The apparatus for testing the local corrosion of the steel strand of the concrete T-beam according to claim 1, characterized in that: The fixing frame (2) comprises a pair of steel plates (2-2), and the pair of steel plates (2-2) are connected through a lead screw (2-1); and the pair of steel plates (2-2) are arranged on both sides of the test beam (1).

3. The apparatus for testing the local corrosion of steel strands of concrete T-beams according to claim 1, characterized in that: The number of the corrosion test areas and the bellows (14) is both two, and the corrosion test areas and the bellows (14) are symmetrically arranged.

4. The apparatus for testing local corrosion of steel strands of concrete T-beams according to claim 1, characterized in that: The test beam corrosion cavity further comprises a slope plate (4-2), the slope plate (4-2) is connected to the vertical plate (4-1) through a mortise and tenon joint, and the slope plate (4-2) is attached to the inner wall of the corrosion test area.

5. A test method for the test apparatus for local corrosion of a steel strand of a concrete T-beam according to claim 1, characterized by: The utility model relates to a test beam (1) for the corrosion test of prestressed concrete T beam, which comprises a test beam (1) for the corrosion test of prestressed concrete T beam, a corrosion groove (3) is arranged in the lower triangle of the test beam (1), and the corrosion groove (3) is installed in the corrosion test area through a fixing frame (2). Step one, the production of test beam (1); Step two, the production, installation and debugging of corrosion device; Step two includes A01: the production of corrosion tank (3); Wherein, the inclined plate (4-2), a pair of side plates (4-3) and the outer plate (4-5) are provided with tenons, the vertical plate (4-1), the bottom plate (4-4) and the outer plate (4-5) are provided with mortises matched with the tenons; the top surface of the vertical plate (4-1) is arc-shaped near the solution storage cavity, and the top surface of the vertical plate (4-1) is inclined at an angle of 45° near the test beam corrosion cavity; A02: the inner diameter of the water injection hole (15) and the check valve is designed, and the water injection hole (15) is arranged at the bottom of the outer plate (4-5); From the formula Calculations show that In the formula, V represents the flow rate; The flow velocity is determined according to the water pump (6); A is the cross-sectional area of ​​the pipe, and d is the inner diameter of the pipe; A03: assembling the tank body; the five parts of the vertical plate (4-1), the inclined plate (4-2), the pair of side plates (4-3), the bottom plate (4-4) and the outer plate (4-5) are connected by mortise and tenon, and then UV glue is injected at the mortise and tenon joint and dried; A04: processing and producing the fixing frame (2); A05: installing the fixing frame (2) and the corrosion tank (3); the steel plate (2-2) is provided with screw holes for passing through the lead screw (2-1) and the stud (9), four lead screws (2-1) and two steel plates (2-2) are simply assembled into a rectangle, and then the lead screw (2-1) is screwed into the designated part of the test beam (1), and then the nut (2-3) is tightened at both ends of the lead screw (2-1), so that the two steel plates (2-2) are tightly attached to the two sides of the beam flange, and the four lead screws (2-1) are tightly attached to the top and bottom surfaces of the test beam (1); the inner surface of the lower part of the assembled vertical plate (4-1) is coated with glass glue, and then the inclined edge of the inclined plate (4-2) is aligned with the test beam (1) at the junction of the lower triangular surface and the horseshoe surface in the corrosion section, and the lower part of the vertical plate (4-1) is attached to the horseshoe surface of the test beam (1) in the corrosion section; after sticking, the vertical plate (4-1) is adjusted up and down, so that the inclined edge of the inclined plate (4-2) is tightly attached to the lower triangular surface of the test beam (1); the length of the stud (9) is adjusted so that the stud (9) abuts against the vertical plate (4-1) to fix the corrosion tank (3), and finally the gaps between the organic glass and the concrete interface in the tank are filled with glass glue along the inner wall to prevent water leakage; then take a sheet of thin steel plate, cut it to the size of the test beam corrosion cavity of the vertical plate (4-1), coat it with glass glue on one side, and then paste it on the test beam corrosion cavity of the vertical plate (4-1) as a cathode; A06: after the glass glue is dried, fill the test beam corrosion cavity with NaCl solution with a concentration of 3.5%, and stand for 24 hours, then pump out the solution; then cover the test beam corrosion cavity with PVA medical sponge (5), and the sponge (5) is immersed in NaCl solution with a mass concentration of 3.5% until saturated before laying; A07: The solution storage tank (7) is filled with a 3.5% NaCl solution, the water pump (6) is connected to the solution storage tank (7) through the conduit (6-1) at one end, and the other end of the conduit (6-1) is connected to the solution storage cavity, the water pump (6) is connected to the intelligent power strip (6-2), and the corrosive liquid is immersed in the sponge (5) through the arc surface and the inclination on the vertical plate (4-1); Before the water pump (6) is connected to the intelligent power strip (6-2), the evaporation amount of the corrosive liquid is calculated according to the Pengman formula, then the flow rate of the corrosive liquid required by the water pump (6) is calculated according to the evaporation amount, then the time required to reach the required water amount is calculated according to the required flow rate and the pumping speed of the water pump (6), then the time required to fill the solution storage tank and the time required for the sponge to be saturated again are calculated, and the intelligent power strip with a timing switch function is set to cycle and time according to the calculated time, so that the water pump can periodically supplement the corrosive liquid in the solution storage tank, so that the sponge is always wet; A08: Connect the positive electrode of the power supply with the copper wire (13) and the negative electrode of the power supply with the thin steel plate, then apply power to the steel strand (12) in the specified area, and calculate the current density and time according to Faraday's law; A09: After the power is turned off, the direct current power supply (8) is turned off, and the localized corrosion test is completed.

6. The test method of claim 5, wherein: The preparation of the test beam (1) includes S01: Calculate the length of the single steel strand (12) and the corrugated pipe (14) according to the reinforcement curve of the steel strand (12) and the reserved length at the tension end and the anchoring end; S02: Take the anchoring end as the starting point, calculate the length range of the steel strand (12) corresponding to the specified corrosion section of the test beam (1), and mark it, polish off the passivation film of the steel strand (12) in the marked section with sandpaper, and brush a layer of epoxy resin on both ends of the marked section; After the epoxy resin is dried, a copper wire (13) with a cross-sectional area of 1 mm2 is spot welded on the steel strand (12) without a passivation film, the length of the copper wire (13) is not less than the length of the single steel strand (12), the copper wire (13) and the steel strand (12) are fixed at a distance of 20 mm from the welding point, and then fixed every 500 mm along the tension end direction with plastic binding wire; S03: Bind the reinforcement cage, fix the corrugated pipe (14) with the prepared material at the control point of the curved reinforcement, then pass the steel strand (12) from the anchoring end through the corrugated pipe (14), and control the reserved length of the steel strand (12) at the anchoring end, and lead the copper wire (13) out of the corrugated pipe (14) at the tension end; ​ ​ S04: Put the reinforcement cage into the test mold, and reserve a slot-shaped post-cast hole at the lower triangular section of the test beam (1) to be corroded, so that the corrugated pipe (14) is not covered with concrete and is directly exposed to the air at the interface with the original lower triangular section. Pour and cure the concrete and remove the mold; after 28 days of curing, prepare to prestress the test beam (1); before tensioning, recheck the reserved length of the steel strand (12) at the anchoring end and add the pre-slippage length of the steel strand (12) at the anchoring end, then install the fixed-end anchor, and after the installation of the fixed-end anchor is completed, install a circular grommet (11) with an opening and a tensioning-end anchor in turn at the tensioning end. The thickness of the circular grommet (11) with an opening is 10 mm, the diameter is not less than the diameter of the tensioning-end anchor, and the elastic modulus should be greater than that of the tensioning-end anchor. The cross-sectional area of the opening is 3-6 times the cross-sectional area of the copper wire, and the copper wire (13) is led out when the circular grommet is installed; then, prestress the test beam (1), and after tensioning is completed, perform high-pressure grouting and curing; S05: After curing is completed, first polish the surface of the concrete around the slot rough, then clean the surface with water and a hair dryer, next remove the exposed corrugated pipe (14) at the slot-shaped post-cast hole, expose the mortar inside the pipe, and then backfill with low-grade concrete (10), and after 28 days of curing, start the corrosion test. ​

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