Test loading device for testing bonding performance of reinforcing steel bar and concrete

Abstract

The utility model discloses a test loading device for testing the bonding performance of reinforcing steel bars and concrete, and belongs to the technical field of performance testing of concrete structure test pieces. Comprising an external complex stress applying device, a horizontal counter-force structure, a horizontal fixing structure and an anchoring and drawing structure, the external complex stress applying device, the horizontal fixing structure and the anchoring and drawing structure are all located above the horizontal counter-force structure, and the external complex stress applying device is used for applying complex stress to a reinforced concrete test piece in the circumferential direction; before testing, the steel bar is placed in a corrosion pool to be corroded, the steel bar in the reinforced concrete test piece penetrates through the horizontal counter-force structure, and anchoring and drawing structures are installed at the free end and the drawing end of the steel bar. The device is small in size and weight, simple in testing method, easy to operate, good in flexibility and easy to carry. And the accuracy of a test result is improved. And the test of the bonding performance of the reinforced concrete test piece under the coupling action of external complex stress and steel bar corrosion is realized.

Description

Technical Field

[0001] The utility model relates to the technical field of concrete structure specimen performance testing, in particular to a testing loading device for testing the bonding performance of steel bars and concrete. Background Art

[0002] Reinforced concrete structures have been widely used due to their excellent mechanical properties and easy access to raw materials. Since some reinforced concrete structures are located in coastal areas and saline soil areas in the west, they will be corroded by chloride ions, resulting in steel corrosion and concrete carbonization. The bonding performance between steel and concrete will gradually deteriorate due to the corrosion of steel. In actual structures, most reinforced concrete structures work under external loads, such as the lower structure of bridge piers and the beam-column joints in building construction. The reaction force generated at the support node of the column will produce lateral pressure on the upper and lower main bars in the beam. Therefore, it is very important for actual engineering to study the test loading device for the bonding performance of steel and concrete under the coupling of steel corrosion and external complex stress.

[0003] At present, most of the testing methods and equipment for the bond performance between steel bars and concrete at home and abroad use large electro-hydraulic servo universal testing machines (MTS) for pull-out tests. The MTS equipment itself has a large weight, high cost and cost, and is difficult to carry and disassemble, and is not flexible in application. For pull-out tests under complex stress, due to the large weight of the load-bearing equipment itself, it is difficult to install and disassemble the MTS equipment when pulling, and the stability is not good during the pulling process, resulting in large errors in measurement accuracy. Therefore, the development of a test loading device for the bond performance of steel bars and concrete under complex stress is very important for in-depth research on the bond performance of steel bars and concrete under complex stress and research on the bond performance under the coupling conditions of steel bar corrosion and external complex stress. Utility Model Content

[0004] The purpose of the utility model is to develop a test loading device for testing the bonding performance of steel bars and concrete under the coupling effect of external complex stress and steel bar corrosion. Complex stress (bidirectional compression-compression combination, bidirectional tension-tension combination, bidirectional tension-compression combination) is applied to the concrete specimen through the external complex stress application device, and then the test of the bonding performance of steel bars and concrete under complex stress state is carried out in conjunction with the anchoring and pulling structure and the corresponding reaction force device.

[0005] To achieve the above-mentioned purpose, the utility model provides a testing loading device for the bonding performance of steel bars and concrete, comprising an external complex stress applying device, a horizontal reaction force structure, a horizontal fixing structure and an anchoring and pulling structure. The external complex stress applying device, the horizontal fixing structure and the anchoring and pulling structure are all located above the horizontal reaction force structure. The external complex stress applying device is used to apply complex stress to the circumference of the reinforced concrete specimen, which is placed in a rust pool for corrosion before the test. The steel bars in the reinforced concrete specimen pass through the horizontal reaction force structure, and the free end and the pulling end of the steel bars are both installed with anchoring and pulling structures.

[0006] Preferably, the horizontal reaction structure includes a base plate, a reaction plate is vertically arranged at the center of the base plate, a triangular reinforcement plate is connected to one side of the reaction plate, a channel steel is connected below the center of the other side of the reaction plate, and a front baffle is arranged at the end of the channel steel.

[0007] Preferably, the anchoring and pulling structure includes an anchoring puller, an anchor, a pressure sensor and a high-precision displacement sensor. The pressure sensor is installed at the pulling end of the steel bar, the rear end of the pressure sensor is close to the reaction plate, and the front end is close to the anchoring puller. The anchor is installed at the front end of the anchoring puller and is close to it. The high-precision displacement sensor is located between the free end of the steel bar and the pulling end of the steel bar inside the channel steel.

[0008] Preferably, the horizontal fixing structure includes a long threaded screw, a short threaded screw, a long horizontal baffle, a short horizontal baffle and a high-strength nut. The threaded screw and the long horizontal baffle are connected by a high-strength nut and are used to fix the external complex stress applying device. The short threaded screw and the short horizontal baffle are connected by a high-strength nut and are used to fix the anchor puller.

[0009] Preferably, the upper and lower parts of the long-threaded screw rod and the short-threaded screw rod are both provided with threads, and the diameters of the long-threaded screw rod and the short-threaded screw rod are between 14-18 mm.

[0010] Preferably, the reaction plate, triangular reinforcement plate, front baffle and bottom plate are all made of 10-40mm Q460 high-strength steel plate.

[0011] Preferably, the bottom plate, reaction plate, front baffle, channel steel, triangular reinforcement plate, long threaded screw rod, short threaded screw rod and high-strength nut are all made of corrosion-resistant steel and coated with anti-rust paint.

[0012] Preferably, the connection between the reaction plate, the triangular reinforcement plate, the channel steel, the front baffle and the bottom plate is welded by gas shielded welding.

[0013] Preferably, two high-precision displacement sensors are provided, which are fixed in sequence to the free end of the steel bar and the steel bar drawing end inside the channel steel by means of magnetic clamps.

[0014] Preferably, a simple clamp is installed at the high-precision displacement sensors at the free end and the drawn end of the steel bar, and the metal round head at the front end of the high-precision displacement sensor rests on the simple clamp.

[0015] Preferably, the pressure sensor and the high-precision displacement sensor are connected to the DH3816 static strain collector and connected to an external computer to measure and collect relevant test data.

[0016] A method for testing a loading device for testing the bonding performance of steel bars and concrete, comprising the following steps:

[0017] S1. Place the reinforced concrete test block in an external complex stress application device, then put the reinforced concrete test block under the complex stress state into the corrosion pool, connect the steel bars to the power supply, and realize the steel bar corrosion of the reinforced concrete test piece under the complex stress state.

[0018] S2. Take out the external complex stress applying device from the rust pool and move it to the corresponding position of the bottom plate. The steel bars are passed through the reserved holes of the reaction plate and the front baffle in turn. The long threaded screw rod is connected to the bottom plate through the reserved threaded holes. The long horizontal baffle plate is installed at the upper edge of the outer side of the external complex stress applying device through the long threaded screw rod to fix its position.

[0019] S3. Slightly adjust the position of the reinforced concrete test block so that its surface fits the front baffle at the front of the channel steel.

[0020] S4. Connect the short threaded screw to the base plate through the reserved threaded hole, and install the nut and the short horizontal baffle at the corresponding position on the upper end of the short threaded screw to provide vertical support for the anchoring and pulling equipment.

[0021] S5. Install the pressure sensor at the pulling end of the steel bar, with the rear end of the pressure sensor close to the reaction plate and the front end close to the anchor puller, and the anchor is installed at the front end of the anchor puller.

[0022] S6. Apply pressure to the hydraulic jack, perform a pull-out test on the reinforced concrete test block, collect displacement data and load data through the DH3816 static strain acquisition instrument, and analyze the test data. The principle is as follows:

[0023]

[0024]

[0025] τ and s are the bonding stress and relative slip value, respectively; P is the pull-out force of the anchor puller; l d is the length of the bonding section, D is the diameter of the steel bar, s l and f are the slip amounts of the drawing end and the free end, Es is the elastic modulus of the steel bar, l 0 It is the distance between the top of the bonding end and the fixed position of the high-precision displacement sensor.

[0026] Therefore, the utility model adopts a steel bar and concrete bonding performance test loading device with the above structure, which has the following beneficial effects:

[0027] (1) The test device of the utility model has a small size and weight, and the test method is simple and easy to operate. It can be assembled and used with different external complex stress applying devices. Compared with large electro-hydraulic servo universal testing machines, it has better flexibility and is easier to carry.

[0028] (2) The test device of the utility model, wherein the reaction plate, triangular reinforcement plate, front baffle plate and bottom plate are made of Q460 high-strength steel plates, and the welding method adopts gas shielded welding. The high-strength nuts used are all fine threaded nuts. The strength of the materials used can meet the strength requirements of the current reinforced concrete bonding performance test, and can bear a maximum stress of 200MPa.

[0029] (3) The test device of the utility model can realize real-time measurement of the pulling force and the slippage of the loading end and the pulling end of the steel bar by connecting the force sensor and the high-precision displacement sensor to the DH3816 static strain collector, thereby improving the accuracy of the test results.

[0030] (4) The loading device of the utility model can apply complex stresses (bidirectional compression-compression combination, bidirectional tension-tension combination, bidirectional tension-compression combination) to the concrete test block, thereby realizing the test of the bonding performance of reinforced concrete specimens under the coupling effect of external complex stress and steel corrosion.

[0031] The technical solution of the utility model is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a structural schematic diagram of a test loading device for testing the bonding performance of steel bars and concrete.

[0033] Figure 2 It is a schematic diagram of the oil pump pressure application and data acquisition structure of an embodiment of a test loading device for testing the bonding performance of steel bars and concrete in the utility model;

[0034] Reference numerals

[0035] 1. Triangular reinforcement plate; 2. Reaction plate; 3. Bottom plate; 4. Anchor; 5. Anchor puller; 6. Pressure sensor; 7. Short threaded screw; 8. Short horizontal baffle; 9. Front baffle; 10. Channel steel; 11. External complex stress application device; 12. Long threaded screw; 13. Long horizontal baffle; 14. High-precision displacement sensor; 15. Simple clamp; 16. Magnetic clamp; 17 Steel bars; 18. High-strength nuts. DETAILED DESCRIPTION

[0036] The technical solution of the utility model is further described below through the accompanying drawings and embodiments.

[0037] Unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the usual meanings understood by persons with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" and the like mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" and the like are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0038] Example

[0039] like Figure 1As shown, the utility model provides a test loading device for testing the bonding performance of steel bars and concrete, including an external complex stress applying structure, a horizontal reaction force structure, an anchoring and pulling structure, and a horizontal fixing structure. The horizontal fixing structure includes a long threaded screw 12, a long horizontal baffle 13, a short threaded screw 7, a short horizontal baffle 8, and a high-strength nut 18. The horizontal reaction force structure includes a bottom plate 3, a reaction plate 2, a triangular reinforcement plate 1, a channel steel 10, and a front baffle 9. The external complex stress applying structure includes an external complex stress applying device 11. The pulling end of the steel bar is sleeved with an anchor 4, the front surface of the reaction frame 2 is fitted with the rear surface of the pressure sensor 6, the front surface of the pressure sensor 6 is fitted with the rear surface of the anchor puller 5, the front surface of the anchor puller 5 is fitted with the anchor, the right-angled side of the triangular reinforcement plate 1 is connected to the reaction plate 2, the channel steel 10 is connected to the reaction plate 2, the front baffle plate 9 is connected to the channel steel 10, the long threaded screw 12 is connected through the threaded hole reserved on the bottom plate 3, and the long horizontal baffle 13 is fixed in the corresponding position by a high-strength nut 18 to fix its external complex stress application device. The short horizontal baffle 8 is fixed in the corresponding position by a high-strength nut 18. The loading end and free end of the steel bar 17 are installed with a simple clamp 15, the metal round head at the front end of the high-precision displacement sensor 14 is against the simple clamp 15, and the magnetic clamps 16 at the loading end and the free end are adsorbed and fixed on the reaction plate 2 and the bottom plate 3 respectively.

[0040] The reaction plate 2 and the triangular reinforcement plate 1, the channel steel 10 and the front baffle 9, and the channel steel 10 and the reaction plate 2 are welded by gas shielded welding. After welding, the welds are polished by an angle grinder to make them smooth and flat without affecting subsequent tests.

[0041] The long threaded screw rod 12 and the short threaded screw rod 7 in the fixing device are both made of 8.8 grade high-strength screw rods, and the diameters of the long threaded screw rod 12 and the short threaded screw rod 7 are set between 14-18 mm. The nuts for fixing the long horizontal baffle 13 and the short horizontal baffle 8 are both made of high-strength nuts 18.

[0042] The reaction plate 2, the triangular reinforcement plate 1, the bottom plate 3, and the front baffle 9 are made of 8mm-40mm thick Q460 high-strength steel plates, and the steel plates are all painted with anti-rust paint.

[0043] By adjusting the position of the high-strength nut 18 in the short threaded screw 7 to fix the position of the short horizontal baffle 8 relative to the anchor puller 5, the anchor puller 5 is in a mutually perpendicular position relationship with respect to the reaction plate 2, and there is no gap between them to ensure the uniformity of the pulling force loading during the pulling process. The position of the anchor puller 5 relative to the reaction plate 2 is adjusted by adjusting the high-strength nut 18 to make it vertical.

[0044] The reaction plate 2 and the front baffle 9 are both provided with through holes that can pass through the steel bar 17. The diameter of the through hole is 30 mm, which is larger than the diameter of the steel bar. The drawing end and the loading end of the steel bar are both installed with a simple clamp 15. The metal round head at the front end of the high-precision displacement sensor 14 directly rests on the simple clamp 15. The magnetic clamp 16 is directly adsorbed on the reaction plate 2 and the bottom plate 3. Each part is small in size and easy to connect and disassemble.

[0045] In the specific implementation process:

[0046] S1. Place the reinforced concrete specimen in an external complex stress application device and apply pressure through an electric hydraulic pump. Then put the reinforced concrete specimen under complex stress into the corrosion pool, connect the steel bars to the power supply, and realize the corrosion of the steel bars under complex stress state.

[0047] S2. Take out the external complex stress applying device from the rust pool, fix it at the corresponding position of the bottom plate, and pass the steel bars through the holes on the front baffle and the reaction plate.

[0048] S3. Put the pressure sensor, anchor puller and anchor on the corresponding position of the steel bar pulling end. Adjust the position of the anchor puller relative to the reaction plate by adjusting the nut to make it vertical to ensure the uniformity of the tension.

[0049] S4. Connect the high-precision displacement sensor and force sensor to the DH3816 static strain collector by wire.

[0050] S5. Apply tension to the steel bar through the displacement control principle, and use the DH3816 static strain acquisition instrument to realize real-time collection of pull-out force and displacement. After the test is completed, the test data is processed and analyzed, and the bond-slip curve between the steel bar and concrete under the external load is drawn.

[0051] like Figure 2 As shown, firstly, the complex stress-applying structure is pressurized by an electric hydraulic pump, and the stability of its internal stress field is maintained by a voltage stabilizer. Then, a high-precision displacement sensor and a pressure sensor are connected to the DH3816 static strain acquisition instrument and an external computer. Finally, a manual hydraulic pump is used in conjunction with a pressure gauge to apply tension to the anchor puller, and a pulling test is performed. Relevant information such as displacement and force is collected in real time by a computer.

[0052] Therefore, the utility model adopts the above-mentioned steel bar and concrete bonding performance test loading device, which has a small volume and weight, a simple and easy-to-operate test method, and can be assembled and used with different external complex stress applying devices. Compared with large electro-hydraulic servo universal testing machines, it has better flexibility and is easy to carry. It can achieve real-time measurement of the pull-out force and the slippage of the loading end and the pull-out end, and improve the accuracy of the test results. And it can realize the test of the bonding performance of reinforced concrete specimens under the coupling of external complex stress and steel corrosion.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model rather than to limit it. Although the utility model has been described in detail with reference to the preferred embodiments, ordinary technicians in this field should understand that they can still modify or replace the technical solution of the utility model with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the utility model.

Claims

1. A loading device for testing the bonding performance of steel bars and concrete, characterized in that: It includes an external complex stress applying device, a horizontal reaction force structure, a horizontal fixed structure and an anchoring and pulling structure. The external complex stress applying device, the horizontal fixed structure and the anchoring and pulling structure are all located above the horizontal reaction force structure. The external complex stress applying device is used to apply complex stress to the circumference of the reinforced concrete specimen. Before the test, the reinforced concrete specimen is placed in a rust pool for corrosion. The steel bars in the reinforced concrete specimen pass through the horizontal reaction force structure, and the free end and the pulling end of the steel bar are both installed with anchoring and pulling structures.

2. The loading device for testing the bonding performance of steel bars and concrete according to claim 1, characterized in that: The horizontal reaction structure includes a bottom plate, a reaction plate is vertically arranged at the center of the bottom plate, a triangular reinforcement plate is connected to one side of the reaction plate, a channel steel is connected below the center of the other side of the reaction plate, and a front baffle is arranged at the end of the channel steel.

3. The loading device for testing the bonding performance of steel bars and concrete according to claim 2, characterized in that: The anchoring and pulling structure includes an anchoring and pulling instrument, an anchor, a pressure sensor and a high-precision displacement sensor. The pressure sensor is installed at the pulling end of the steel bar. The rear end of the pressure sensor is close to the reaction plate, and the front end is close to the anchoring and pulling instrument. The anchor is installed at the front end of the anchoring and pulling instrument and is close to it. The high-precision displacement sensor is located between the free end of the steel bar and the pulling end of the steel bar inside the channel steel.

4. The loading device for testing the bonding performance of steel bars and concrete according to claim 3 is characterized in that: The horizontal fixing structure includes a long threaded screw, a short threaded screw, a long horizontal baffle, a short horizontal baffle and a high-strength nut. The threaded screw and the long horizontal baffle are connected by a high-strength nut and are used to fix an external complex stress applying device. The short threaded screw and the short horizontal baffle are connected by a high-strength nut and are used to fix an anchor puller.

5. The loading device for testing the bonding performance of steel bars and concrete according to claim 4, characterized in that: The upper and lower parts of the long-threaded screw rod and the short-threaded screw rod are both provided with threads, and the diameters of the long-threaded screw rod and the short-threaded screw rod are between 14 and 18 mm.

6. The loading device for testing the bonding performance between steel bars and concrete according to claim 5, characterized in that: The reaction plate, triangular reinforcement plate, front baffle and bottom plate are all made of 10-40mm Q460 high-strength steel plate.

7. The loading device for testing the bonding performance between steel bars and concrete according to claim 6, characterized in that: The bottom plate, reaction plate, front baffle, channel steel, triangular reinforcement plate, long threaded screw rod and short threaded screw rod are all made of corrosion-resistant steel and the surface is coated with anti-rust paint.

8. The loading device for testing the bonding performance between steel bars and concrete according to claim 7, characterized in that: The connection between the reaction plate, triangular reinforcement plate, channel steel, front baffle and bottom plate is welded by gas shielded welding.

9. The loading device for testing the bonding performance between steel bars and concrete according to claim 8, characterized in that: Two high-precision displacement sensors are provided, which are fixed in sequence to the free end of the steel bar and the steel bar drawing end inside the channel steel through magnetic clamps.

10. A loading device for testing the bonding performance of steel bars and concrete according to claim 9, characterized in that: Simple fixtures are installed at the high-precision displacement sensors at the free end and the drawing end of the steel bar, and the metal round head at the front end of the high-precision displacement sensor rests on the simple fixture.

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