CN115493925A - Coupling Test Device and Test Method for Tension-Torsion Corrosion Fatigue of Bridge Suspenders - Google Patents

Abstract

The invention provides a bridge sling tension-torsion corrosion fatigue coupling test device and a test method. The tension-compression conversion subsystem converts vertical pressure into vertical tension through the tension-compression conversion device; meanwhile, the torsion subsystem extrudes the wedge block of the lower pressure bearing platform through the wedge block on the upper pressure bearing platform, so that the thrust bearing drives the lower pressure bearing platform to rotate, further the bridge sling anchored on the lower pressure bearing platform is driven to rotate, the effect of synchronous action of pulling and torsion is realized, and the conversion of compression load to fatigue load of pulling and torsion is realized. The invention can simulate the chlorine salt erosion, the pulling fatigue and the twisting fatigue synchronous loading of the sling steel wire and the steel strand of the cable bearing bridge, can also simulate the pulling fatigue and the twisting fatigue independent loading, and can effectively simulate the real working state of the sling steel wire and the steel strand of the cable bearing bridge; the invention can simulate the durability test of the material under the coupling action of harmful ion erosion and complex tensile and torsional stress.

Description

Coupling test device and test method for tension-torsion corrosion fatigue of bridge suspenders

technical field

The invention belongs to the field of bridge structure durability, and in particular relates to a coupling test device and test method for tension-torsion corrosion fatigue of bridge suspension cables.

Background technique

The suspenders and slings of cable-bearing bridges in coastal cities have been in service environments with corrosive media for a long time. Under the coupling action of chloride salt erosion and external loads, the steel wires and steel strands in the suspenders are corroded, and their mechanics The performance and fatigue performance deteriorate, and the service life is greatly reduced, which seriously affects the service safety and reliability of the bridge structure. The study of fatigue performance of sling wires and steel strands under the coupled action of complex stress and environmental corrosion is the basic premise to correctly evaluate and prolong the service life of cable bridge structures.

For bridges with cable bearing systems, the service environment has the characteristics of high humidity, high salinity, and high temperature, and the steel wires and steel strands in this service environment are corroded, and corrosion pits are gradually formed on the surface. It is worth noting that, during the service process, due to the installation error of the anchorage, the influence of the vehicle load and the wind load, the high speed, heavy load and acceleration characteristics of the sling steel wire and steel strand material will cause the horizontal, vertical and Coupled vibrations, which in turn cause dynamic tensile and torsional loads on steel wires and strands. However, under the coupled action of torsional load and axial tensile load, the stress state of the section at the pit is more complex. Studies have shown that under the same axial tensile load, compared with the pure tensile state, the torsional effect The addition of will cause the material durability to lose nearly 60%.

Aiming at the fatigue performance of bridge suspender steel wire and steel strand under the coupling effect of corrosion and fatigue in the cable load-bearing system, due to the lack of understanding of the real stress state of the steel wire and steel strand during service and the constraints of the test equipment, the existing Most studies have neglected the effect of torsion on the fatigue properties of materials.

The Chinese invention patent application with the publication number CN110044740A discloses a method, application, device and fixture for the determination of the corrosion fatigue damage law of cable steel wire. And fatigue testing machine, which provides test equipment for studying the coupling effect of tensile fatigue and corrosion, but the equipment uses MTS fatigue testing machine, which is expensive and complicated to maintain, especially the torsional load cannot be applied synchronously, so that it cannot be truly simulated Stress state of steel wire and steel strand.

Contents of the invention

The purpose of the present invention is to provide a bridge suspension cable pull-torsion corrosion fatigue coupling test device and test method to solve the technical problem that the existing test device cannot truly simulate the stress state of the bridge suspension cable.

In order to solve the problems of the technologies described above, the specific technical solutions of the present invention are as follows:

A bridge suspension cable tension-torsion corrosion fatigue coupling test device, the device includes a corrosion test system and a fatigue test system, characterized in that the fatigue test system includes a tension-compression conversion subsystem and a torsion subsystem;

The tension-compression conversion subsystem includes a fatigue actuator, a support surface and a tension-compression conversion device, and the support surface is provided with a first through hole and a plurality of second through holes;

The tension-compression conversion device includes a top plate and a bottom plate. The fatigue actuator is located above the top plate to drive the tension-compression conversion device to move downward. The through hole connects the top plate and the bottom plate, and the bottom plate is provided with a third through hole;

The corrosion test system is arranged on the upper end surface of the support surface, and the corrosion test system is located inside the tension-compression conversion device. The upper and lower ends of the corrosion test system are provided with a fourth through hole, and the first The first through hole, the third through hole and the two fourth through holes are coaxially arranged;

The torsion sub-system is arranged between the corrosion test system and the top plate, and the torsion sub-system includes an upper pressure bearing platform arranged on the lower end surface of the top plate and a lower pressure bearing platform arranged on the upper end surface of the corrosion test system , the lower pressure platform is provided with a fifth through hole at the position corresponding to the fourth through hole, the lower pressure platform can rotate along the axis of the fifth through hole, the lower end surface of the upper pressure platform and The upper end surface of the lower pressure platform is provided with a plurality of wedge-shaped blocks that cooperate with each other in the circumferential direction; the upper anchor point of the bridge sling is arranged on the lower pressure platform, and the lower anchor point of the bridge sling is arranged on the bottom plate. The line connecting the upper anchor point and the lower anchor point coincides with the rotation center of the lower bearing platform.

Thus, after the fatigue actuator is started, and the cycle times, stress ratio, stress level, and loading frequency of the fatigue actuator are set, the pressure exerted by the fatigue actuator is transmitted to the bottom plate through the top plate, and the bottom plate moves downward, thereby exerting pressure on the bridge. The sling exerts axial tension to achieve the purpose of fatigue loading. At the same time, the wedge-shaped block on the upper pressure-bearing platform squeezes the wedge-shaped block of the lower pressure-bearing platform, so that the lower pressure-bearing platform rotates along the axis of the fifth through hole, and then drives the bridge sling anchored to the lower pressure-bearing platform to rotate, Realize the effect of synchronous effect of tension and torsion, and realize the transformation from compression load to tension and torsion fatigue load.

Further, the lower bearing platform is connected to the upper end surface of the corrosion test system through a thrust bearing, one end of the thrust bearing is arranged in the fifth through hole, and the other end of the thrust bearing is connected to the upper surface of the corrosion test system. End connection. The wedge-shaped block on the upper pressure-bearing table squeezes the wedge-shaped block of the lower pressure-bearing table, so that the thrust bearing drives the lower pressure-bearing table to rotate.

Further, the fatigue actuator is arranged on a beam, and both sides of the beam are supported by support beams.

Still further, a plurality of support columns are provided on the lower end surface of the support surface.

Furthermore, the corrosion test system includes a corrosion box arranged on the end surface of the support surface and a sprayer arranged on the upper part of the corrosion box, the upper end surface of the corrosion box is connected with the lower bearing platform, and the sprayer is arranged on the upper part of the corrosion box. The shower is connected to the barrel through a water pipe, and a water pump is arranged on the water pipe, and both the water pump and the fatigue actuator are electrically connected to the controller.

In addition, the upper part of the corrosion test system is also provided with a reset device for the lower bearing table, the reset device is a spring, one end of the spring is fixed on the upper end surface of the corrosion test system, and the other end of the spring is fixed On the outside of the lower bearing platform.

Based on the same inventive concept, the present invention also provides a method for carrying out experiments on bridge slings using the above-mentioned bridge sling tension-torsion corrosion fatigue coupling test device, comprising the following steps:

Step 1: Pass one end of the bridge sling through the fifth through hole and anchor it to the upper end of the lower bearing platform, pass the other end of the bridge sling through the third through hole and anchor it to the bottom of the bottom plate.

Step 2. According to the environmental characteristics of spring, summer, autumn and winter seasons, different concentrations of corrosion solutions are prepared and sprayed on the bridge slings through the corrosion test system.

Step 3: Start the fatigue actuator, the pressure exerted by the fatigue actuator is transmitted to the bottom plate through the top plate, and the bottom plate moves downward, thereby exerting axial tension on the bridge sling; at the same time, the wedge-shaped The block squeezes the wedge-shaped block of the lower bearing platform, so that the lower bearing platform rotates along the axis of the fifth through hole, and then drives the bridge sling anchored in the lower bearing platform to rotate.

Step 4. Remove the pressure exerted by the fatigue actuator on the top plate. At this time, the bridge sling in the elastic stage recovers and deforms, driving the tension-compression conversion device to move upward, and the lower pressure-bearing platform rotates and resets under the action of the reset device .

Step 5, repeat step 2 and step 4, and record the test data, and end when the cycle reaches the set number of tests.

The bridge suspension cable pull-torsion corrosion fatigue coupling test device and test method of the present invention have the following advantages:

1. The structure of the present invention is simple, easy to disassemble and assemble, and the setting of the load conversion device realizes the transformation from compression fatigue load to tension and torsional fatigue load.

2. The present invention can not only simulate the chloride salt erosion of the steel wire and steel strand of the cable load-bearing bridge, and the simultaneous loading of the tension and torsion fatigue, but also simulate the separate loading of the tension and torsion fatigue, and can effectively simulate the steel wire and steel wire of the cable load-bearing bridge. The real working state of the stranded wire; the invention can simulate the durability test of the material under the coupling action of harmful ion erosion and tension and torsion complex stress.

3. According to the environmental characteristics of spring, summer, autumn and winter, it can simulate the real service environment of boom steel wire and steel strand, and can be widely used in the durability research of bridge structures and materials. In addition, each control operation of the present invention is carried out on the control system, which has the advantages of high degree of intelligent control and simple operation.

Description of drawings

Fig. 1 is a structural representation of the present invention;

Fig. 2 is the top view of the present invention;

Fig. 3 is the structure diagram of torsion subsystem of the present invention;

Fig. 4 is the structural representation of corrosion system of the present invention;

Figure 5 is a schematic diagram of the anchorage of the bridge sling and the lower bearing platform;

Figure 6 is a schematic diagram of the anchorage between the bridge sling and the bottom plate.

Explanation of marks in the figure: 1. Fatigue actuator; 2. Upper pressure platform; 22. Tension-compression conversion device; 3. Guide column; 4. Wedge block; 5. Lower pressure platform; 51. Fifth through hole; 6. Reset device; 7. Corrosion box; 71. Fourth through hole; 8. Bridge sling; 9. Support surface; 91. First through hole; 92. Second through hole; 10. Bottom plate; 101. Third Through hole; 11, support column; 12, sprinkler; 13, water pump; 14, barrel; 15, controller; 16, beam; 17, support beam; 18, top plate.

detailed description

In order to better understand the purpose, structure and function of the present invention, the present invention will be described in further detail below in conjunction with the accompanying drawings.

As shown in Fig. 1, a kind of bridge suspender tension-twist corrosion fatigue coupling test device of the present embodiment includes a corrosion test system and a fatigue test system, and the fatigue test system includes a tension-compression conversion subsystem and a torsion subsystem; The compression conversion subsystem includes a fatigue actuator 1 , a support surface 9 and a tension-compression conversion device 22 . The fatigue actuator 1 is arranged on a beam 16 , and both sides of the beam 16 are supported by support beams 17 .

As shown in FIG. 1 and FIG. 2 , a first through hole 91 and a plurality of second through holes 92 are provided on the support surface 9 . A plurality of support columns 11 are provided on the lower end surface of the support surface 9 . The tension-compression conversion device 22 includes a top plate 18 and a bottom plate 10, the fatigue actuator 1 is located above the top plate 18 for driving the tension-compression conversion device 22 to move downward, and the bottom plate 10 is arranged below the support surface 9, mostly The first guide post 3 passes through the second through hole 92 to connect the top board 18 and the bottom board 10 . Preferably, in order to make the tensile stress on the bridge suspension cables 8 more uniform, there are four guide columns 3 , and the bottom ends of the four guide columns 3 are uniformly arranged around the bottom plate 10 . The bottom plate 10 is provided with a third through hole 101 , and the third through hole 101 is an anchor point at the lower end of the bridge suspension cable 8 . Both the top plate 18 and the bottom plate 10 are steel plates to ensure that the top plate 18 and the bottom plate 10 will not be deformed during the test.

The corrosion test system is arranged on the upper end surface of the support surface 9, and the corrosion test system is located inside the tension-compression conversion device 22, and the upper and lower ends of the corrosion test system are provided with a fourth through hole 71, The first through hole 91 , the third through hole 101 and the two fourth through holes 71 are coaxially arranged. Specifically, the corrosion test system includes a corrosion box 7 arranged on the upper end surface of the support surface 9 and a sprinkler 12 arranged on the upper part of the corrosion box 7. The corrosion box 7 is a sealed space, and two of the first The four through holes 71 are respectively arranged at the upper and lower ends of the corrosion box 7, and the two fourth through holes 71 are provided with seals to ensure that the corrosion box 7 is still in a sealed environment after the bridge sling 8 is installed. The sealing member includes a slidable steel ring, elastic rubber tightly connected to the inside and outside of the steel ring, and a spring connected to the elastic rubber. The upper end surface of the corrosion box 7 is connected to the lower bearing platform 5, the sprinkler 12 is connected to the bucket 14 through a water pipe, and a water pump 13 is arranged on the water pipe, and the water pump 13 and the fatigue actuator 1 All are electrically connected with the controller 15, and the controller 15 may be a timing device.

As shown in Fig. 1, Fig. 3 and Fig. 4, the torsion sub-system is arranged between the corrosion test system and the top plate 18, and the torsion sub-system includes an upper bearing platform 2 arranged on the lower end surface of the top plate 18 And the lower bearing platform 5 arranged on the upper end surface of the corrosion test system, the lower bearing platform 5 is provided with a fifth through hole 51 at a position corresponding to the fourth through hole 71, and the fifth through hole 51 It is the upper anchorage point of the bridge hanger 8. The lower bearing platform 5 can rotate along the axis of the fifth through hole 51 . Preferably, the lower pressure bearing platform 5 is connected to the upper end surface of the corrosion test system through a thrust bearing, one end of the thrust bearing is arranged in the fifth through hole 51, and the other end of the thrust bearing is connected to the corrosion test system. The upper end surface of the system is connected, the thrust bearing is coaxially arranged with the fourth through hole 71, and the lower end surface of the upper pressure bearing platform 2 and the upper end surface of the lower pressure bearing platform 5 are circumferentially provided with a plurality of wedge blocks 4 that cooperate with each other . The wedge-shaped block 4 is a steel component, and its slopes are all polished. The slope angle of the wedge-shaped block 4 can be determined according to the torque requirement, and the slope angle ranges from 30° to 60°. Specifically, the fatigue actuator 1 compresses the upper pressure platform 2 downward, and the upper pressure platform 2 moves downward, and transmits the pressure to the bottom plate 10 through the guide column 3, and the bottom plate 10 converts the downward pressure into The downward pulling force of the bridge hanger 8. Simultaneously, the upper and lower matched wedge blocks 4 are in contact, and when the upper pressure platform 2 moves downward, the lower pressure platform 5 is driven to rotate, thereby driving the bridge sling 8 to twist, thereby realizing the simulation of pulling, torsion, Corrosion coupling.

In order to more realistically simulate the real scene, the lower pressure platform 5 needs to be reset after the upper pressure platform 2 leaves. Therefore, the upper part of the corrosion test system is also provided with a reset device 6 of the lower bearing table 5, the reset device 6 is a spring, one end of the spring is fixed on the upper end surface of the corrosion test system, and the spring's The other end is fixed on the outside of the lower bearing platform 5 . When the upper pressure platform 2 moves downward, the spring stretches, and the lower pressure platform 5 rotates. When the upper pressure platform 2 moves upward, the spring shrinks, and the lower pressure platform 5 resets. The reset device 6 can also be a hydraulic cylinder, the cylinder body of which is installed on the upper end surface of the corrosion test system, and the protruding end of the hydraulic cylinder is installed outside the lower bearing platform 5 . When the upper pressure platform 2 moves downward, one end of the hydraulic cylinder stretches out, and the lower pressure platform 5 rotates. When the upper pressure platform 2 moves upward, the extended end of the hydraulic cylinder is recovered, so that the lower pressure platform 5 reset.

The method for carrying out the experiment on the bridge sling by adopting the bridge sling tensile torsion corrosion fatigue coupling test device of the above-mentioned embodiment comprises the following steps:

Step 1, as shown in Figure 5, one end of the bridge sling 8 is passed through the thrust bearing and anchored to the upper end of the lower bearing platform 5; as shown in Figure 1, Figure 3, Figure 4 and Figure 6, the bridge The other end of the sling 8 passes through the fourth through hole 71 , the first through hole 91 , and the third through hole 101 in turn, and is anchored to the bottom of the bottom plate 10 .

Step 2, fixing the seal at the fourth through hole 71 .

Step 2, according to the environmental characteristics of spring, summer, autumn and winter, different concentrations of corrosion solution are prepared, and the controller 15 controls the water pump 13 to spray the corrosion solution on the bridge sling 8 . According to the environmental characteristics of spring, summer, autumn and winter, the corrosion simulations of pure water spray, pure water environment, low concentration chloride salt solution environment and high concentration chloride salt environment are respectively carried out.

Step 3: Start the fatigue actuator 1 after setting the number of cycles, stress ratio, stress level, and loading frequency of the fatigue test system. The pressure applied by the fatigue actuator 1 is transmitted to the bottom plate 10 through the top plate 18, and the bottom plate 10 moves downward. Further, an axial tension is applied to the bridge sling 8 . At the same time, the wedge-shaped block of the upper pressure-bearing platform 2 squeezes the wedge-shaped block of the lower pressure-bearing platform 5, so that the lower pressure-bearing platform rotates along the axis of the fifth through hole 51, and then drives the bridge crane anchored on the lower pressure-bearing platform. Cable 8 rotates.

Step 4: Remove the pressure exerted by the fatigue actuator 1 on the top plate 18. At this time, the bridge sling 8 in the elastic stage resumes deformation, driving the tension-compression conversion device 22 to move upward. And in cooperation with the reset device 6, the lower bridge sling 8 drives the lower bearing platform 5 to rotate and reset.

Step 5. Repeat step 2 and step 3, and record the test data, and end when the cycle reaches the set number of tests.

The tension-torsion corrosion fatigue coupling test device of the bridge suspender of the present invention can not only simulate the tension and torsion single stress fatigue loading of the material, but also can simultaneously simulate the tension and torsion composite stress fatigue loading test of the material.

It can be understood that the present invention is described through some embodiments, and those skilled in the art know that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, the features and examples may be modified to adapt a particular situation and material to the teachings of the invention without departing from the spirit and scope of the invention. Therefore, the present invention is not limited by the specific embodiments disclosed here, and all embodiments falling within the scope of the claims of the present application belong to the protection scope of the present invention.

Claims (7)

1. A bridge sling tension-torsion corrosion fatigue coupling test device, comprising a corrosion test system and a fatigue test system, characterized in that, the fatigue test system includes a tension-compression conversion subsystem and a torsion subsystem; The tension-compression conversion subsystem includes a fatigue actuator (1), a support surface (9) and a tension-compression conversion device (22). The support surface (9) is provided with a first through hole (91) and multiple a second through hole (92); The tension-compression conversion device (22) includes a top plate (18) and a bottom plate (10), and the fatigue actuator (1) is located above the top plate (18) to drive the tension-compression conversion device (22) to move downward, so The bottom plate (10) is arranged below the support surface (9), and a plurality of guide columns (3) pass through the second through hole (92) to connect the top plate (18) and the bottom plate (10), and the bottom plate ( 10) There is a third through hole (101); The corrosion test system is arranged on the upper end surface of the support surface (9), and the corrosion test system is located inside the tension-compression conversion device (22), and a fourth Through holes (71), the first through hole (91), the third through hole (101) and the two fourth through holes (71) are coaxially arranged; The torsion sub-system is arranged between the corrosion test system and the top plate (18), and the torsion sub-system includes an upper bearing platform (2) set on the lower end surface of the top plate (18) and an upper bearing platform (2) set on the corrosion test system. The lower pressure bearing platform (5) on the upper end surface of the test system, the lower pressure bearing platform (5) is provided with a fifth through hole (51) at the position corresponding to the fourth through hole (71), and the lower pressure bearing platform (5) The platform (5) can rotate along the axis of the fifth through hole (51), and the lower end surface of the upper pressure bearing platform (2) and the upper end surface of the lower pressure bearing platform (5) are provided with a plurality of wedge-shaped blocks that cooperate with each other in the circumferential direction (4); the upper end anchorage point of the bridge sling (8) is provided on the lower bearing platform (5), the lower end anchorage point of the bridge sling (8) is provided on the bottom plate (10), and the upper end The line between the anchor point and the anchor point at the lower end coincides with the rotation center of the lower bearing platform (5). 2. The bridge sling tension-torsion corrosion fatigue coupling test device according to claim 1, characterized in that, the lower bearing platform (5) is connected to the upper end surface of the corrosion test system through a thrust bearing, and the thrust One end of the bearing is arranged in the fifth through hole (51), and the other end of the thrust bearing is connected with the upper end surface of the corrosion test system. 3. The bridge suspension cable pull-twist corrosion fatigue coupling test device according to claim 1, characterized in that, the fatigue actuator (1) is set on the beam (16), and the beam (16) passes through both sides Support beam (17) supports. 4. The bridge suspension cable tension-torsion corrosion fatigue coupling test device according to claim 1, characterized in that, the lower end surface of the support surface (9) is provided with a plurality of support columns (11). 5. The bridge suspension cable pull-twist corrosion fatigue coupling test device according to claim 1, characterized in that, the corrosion test system includes a corrosion box (7) arranged on the upper end surface of the support surface (9) and a The sprayer (12) on the upper part of the corrosion box (7), the upper end surface of the corrosion box (7) is connected to the lower pressure platform (5), and the sprayer (12) is connected to the bucket (14) through a water pipe ), the water pipe is provided with a water pump (13), and both the water pump (13) and the fatigue actuator (1) are electrically connected to the controller (15). 6. The bridge suspension cable pull-torsion corrosion fatigue coupling test device according to claim 1, characterized in that, the upper part of the corrosion test system is also provided with a reset device ( 6), the reset device (6) is a spring, one end of the spring is fixed on the upper end surface of the corrosion test system, and the other end of the spring is fixed on the outside of the lower bearing platform (5). 7. A method for carrying out experiments on bridge slings by adopting the bridge sling tensile torsion corrosion fatigue coupling test device as described in any one of claims 1 to 6, is characterized in that, comprises the steps: Step 1. Pass one end of the bridge sling (8) through the fifth through hole (51) and anchor it on the lower bearing platform (5), and pass the other end of the bridge sling (8) through the fifth through hole (51) in turn. Four through holes (71), the first through hole (91), the third through hole (101), and anchored on the bottom plate (10); Step 2. According to the environmental characteristics of the four seasons of spring, summer, autumn and winter, different concentrations of corrosion solutions are prepared and sprayed on the bridge sling (8) through the corrosion test system; Step 3: Start the fatigue actuator (1), the pressure exerted by the fatigue actuator (1) is transmitted to the bottom plate (10) through the top plate (18), and the bottom plate (10) moves downward, and then the bridge sling (8 ) to apply axial tension; at the same time, the wedge-shaped block on the upper pressure-bearing platform (2) squeezes the wedge-shaped block of the lower pressure-bearing platform (5), so that the lower pressure-bearing platform along the axis of the fifth through hole (51) Rotate, and then drive the bridge sling (8) anchored to the lower bearing platform to rotate; Step 4: Remove the pressure exerted by the fatigue actuator (1) on the top plate (18), at this time the bridge sling (8) in the elastic stage recovers to deform, driving the tension-compression conversion device (22) to move upward, and the The following pressure bearing platform (5) is rotated and reset under the action of the reset device (6); Step 5, repeat steps 2 to 4, and record the test data, and end when the cycle reaches the set number of tests.

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