Device and method for testing torsion resistance or shear resistance of recycled concrete beam test piece

Abstract

The invention discloses a device and a method for testing torsion resistance or shear resistance of a recycled concrete beam test piece. The device comprises a first jack, and a force transmission gear is arranged on a piston rod of the first jack; the hoop is used for clamping a concrete test piece; a hoop gear is arranged on one side of the hoop, and the force transmission gear is meshed with the hoop gear, so that the hoop is driven to rotate through the lifting of the first jack, and the torsion damage of the concrete test piece is caused; the heating mechanism is used for heating the concrete test piece, and the second jack is used for applying pressure to the shaft end of the concrete test piece, so that the concrete test piece is in an axial pressure state; the third jack is used for applying pressure to the side, not provided with the hoop gear, of the hoop; the device can be used for testing the torsional strength and the shear strength of the concrete beam under the coupling action of high temperature and axial compression. The device is used for testing the torsional strength and the shear strength of the structure under the coupling action of high temperature and axial compression.

Description

Technical Field

[0001] The invention relates to a testing device, in particular to a testing device and method for the torsional performance or shearing performance of a recycled concrete beam specimen. Background Art

[0002] The torsional strength and shear strength of concrete beams are important mechanical parameters in engineering construction. The shear strength test of concrete beams mainly focuses on evaluating the bearing capacity and failure mode of the beam when subjected to shear force. There are currently two mainstream methods for measuring shear strength. One is three-point bending, where the beam is placed on two fulcrums and the load is applied through a press. The other is a direct shear test, where a shear force is directly applied to a certain section of the beam, which is achieved by clamping the two ends of the beam and applying force in opposite directions. The torsional strength test of concrete beams is mainly used to evaluate the performance and torsional resistance of the beam under torsional loads. The currently commonly used torsional strength test is a pure torsion test. Torque is applied in opposite directions at both ends of the beam, usually using a special fixture or torque application device. This test can directly measure the torsional strength and torsional stiffness of the concrete beam.

[0003] At present, some researchers have made many improvements and innovations to directly obtain the shear and torsional properties of concrete beams.

[0004] Di Shengjie invented a shear mechanism for multiple shear surfaces of original loess. The shear unit in the device is connected to the rotation unit and is set in the test hole. Its unfolded end is connected to the surface of the annular soil body in the unfolded state, which is used to apply vertical shear force to the annular soil body that is subjected to horizontal normal force. This scheme can obtain the shear performance of different positions of deep annular soil in the loess area.

[0005] The torsional strength and shear strength of concrete beams are important mechanical parameters in engineering construction. The shear strength test of concrete beams mainly focuses on evaluating the bearing capacity and failure mode of the beam when subjected to shear force. There are currently two mainstream methods for measuring shear strength. One is three-point bending, where the beam is placed on two fulcrums and the load is applied through a press. The other is a direct shear test, where a shear force is directly applied to a certain section of the beam, which is achieved by clamping the two ends of the beam and applying force in opposite directions. The torsional strength test of concrete beams is mainly used to evaluate the performance and torsional resistance of the beam under torsional loads. The currently commonly used torsional strength test is a pure torsion test. Torque is applied in opposite directions at both ends of the beam, usually using a special fixture or torque application device. This test can directly measure the torsional strength and torsional stiffness of the concrete beam.

[0006] At present, some researchers have made many improvements and innovations to directly obtain the shear and torsional properties of concrete beams.

[0007] Di Shengjie invented a shearing mechanism for multiple shearing surfaces of original loess. The shearing unit in the device is connected to the rotating unit and is arranged in the test hole. Its unfolded end is connected to the surface of the annular soil body in the unfolded state, and is used to apply vertical shear force to the annular soil body that is subjected to horizontal normal force. The present invention can obtain the shearing performance of different positions of deep annular soil bodies in loess areas.

[0008] Patent document CN114235579A discloses a triaxial testing device for the compression and shear strength of natural gas hydrate cores. The device is provided with a compression cylinder, in which the core is placed; the compression cylinder has a closed pipeline connected to the external tank; a confining pressure and temperature control unit is connected to the pipeline of the triaxial testing machine; a data acquisition unit is provided at the upper end of the compression cylinder and fixedly connected to the triaxial testing machine, which is used to record the change of the acoustic wave velocity before and after the core is crushed, and to record the time difference between the transverse and longitudinal wave velocities. It can test the compressive strength and shear strength of the core in the stable state of natural gas hydrate, obtain the macroscopic mechanical property test data of the core, and analyze the deformation mechanism of the sedimentary layer.

[0009] Patent document CN116840074A discloses a shear strength test device for concrete cube specimens. The device adopts the method of horizontal pressure and vertical shearing. A rectangular horizontal pressure frame is first set on the outside of the concrete specimen, and a normal pressure mechanism and a roller row are set between the concrete specimen and the rectangular horizontal pressure frame. The normal pressure mechanism and the rectangular horizontal pressure frame can be used to apply pressure to the right and left normal pressure parts on the side of the concrete specimen to complete the shear strength test of high-strength and high-performance concrete. The device has the advantages of simple structure, easy operation and wide application range.

[0010] Patent document CN219512012U discloses a cable torsional stiffness test device. The device fixes a test piece, which is arranged corresponding to the torsion assembly and is used to clamp the other end of the cable to be tested; a torsion torque sensor is connected to the torsion assembly to test the torsion torque borne by the cable to be tested; an angle sensor is connected to the cable to be tested to test the torsion angle of the cable to be tested; the test method includes the following steps: preparing a sample; installing the sample into the test device; providing a test torsion force, and collecting the torsion torque and torsion angle; analyzing the relationship between the torsion angle and torsion torque; and calculating the torsional stiffness.

[0011] Patent document CN112067463A discloses a test device for the torsion resistance of an insulator, which is arranged on a frame, one end of a test sample is rotatably mounted on the frame through a brake, and the rotation axis of the test sample is arranged vertically; an eccentric rotor is arranged on the frame so as to slide horizontally, and the other end of the test sample is plugged in with the eccentric rotor, and the center line of the test sample is coaxial with the rotation axis of the eccentric rotor; a rotary drive mechanism, the output shaft of the rotary drive mechanism is plugged in with the eccentric rotor, and the output shaft of the rotary drive mechanism is coaxial with the axis of the eccentric rotor; a linear drive mechanism, the linear drive mechanism is used to drive the rotary drive mechanism to rise and fall, so that the output shaft of the rotary drive mechanism can be plugged in or separated from the eccentric rotor. This solution can automatically test the torsion resistance function of the insulator, with high test efficiency and accurate results.

[0012] However, most of the above devices only focus on solving a single mechanical parameter under a single condition of shear or torsion. Most of the devices cannot perform shear or torsion tests on the experimental components under the coupling of high temperature and axial pressure to obtain their corresponding mechanical properties. Most shear and torsion tests require precise alignment of the components with the experimental fixture to ensure that the load acts at the center of the specimen. The processing accuracy of the components is relatively high. Summary of the invention

[0013] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and to provide a device and method for testing the torsional performance or shear performance of a recycled concrete beam specimen, so as to simultaneously realize the torsional performance or shear performance test of the concrete beam specimen under the coupling of high temperature and axial compression.

[0014] To achieve the above object, the technical solution of the present invention is:

[0015] In a first aspect, the present invention provides a device for testing the torsional performance or shear performance of a recycled concrete beam specimen, comprising:

[0016] A first jack, wherein a power transmission gear is arranged on a piston rod of the first jack;

[0017] A hoop, the hoop is used to clamp the concrete specimen; a hoop gear is provided on one side of the hoop, the force transmission gear and the hoop gear are meshed, so that the hoop is driven to rotate by the lifting and lowering of the first jack, causing torsional damage to the concrete specimen;

[0018] A first force sensor, used for detecting and recording the force state of the first jack;

[0019] The heating mechanism is used to heat the concrete specimen.

[0020] The second jack is used to apply pressure to the axial end of the concrete specimen so that the concrete specimen is in an axial compression state;

[0021] a third jack, for applying pressure to the side of the hoop that is not provided with the hoop gear;

[0022] The third force sensor is used to detect and record the force state of the third jack.

[0023] Optionally, the heating mechanism includes two mullite bricks, a mullite brick with a U-shaped groove is arranged between the two mullite bricks, a U-shaped thermal conductive carbon rod is arranged in the mullite brick with the U-shaped groove, and the connection end of the U-shaped thermal conductive carbon rod passes through the first mullite brick or the second mullite brick to connect to a three-phase high current transformer to achieve temperature control.

[0024] Optionally, after the hoop clamps the concrete specimen, the hoop is placed on the mullite brick with the U-shaped groove, and both ends of the concrete specimen are placed on two mullite bricks of the heating mechanism.

[0025] Optionally, the torsional performance or shear performance testing device for the recycled concrete beam specimen also includes a pedestal, which is provided with a cross-shaped groove; the lateral groove of the cross-shaped groove is used to place the heating mechanism and the second jack, and the middle intersection position of the cross-shaped groove is the placement position of the hoop; one side of the vertical groove of the cross-shaped groove is used to place the third front jack, and the other side and upper part of the vertical groove are used to install a frame, and the frame is used to install the first jack.

[0026] Optionally, a loading plate is provided between the second jack and the shaft end of the concrete specimen; the second jack, the loading plate and the second force sensor constitute an axial pressure mechanism.

[0027] Optionally, the first force sensor is arranged on the top of the first jack; the second force sensor is arranged on the top of the second jack; and the third force sensor is arranged on the top of the third front jack.

[0028] Optionally, the third jack is placed on a mullite brick; the third jack, the mullite brick and the third force sensor constitute a shear mechanism.

[0029] Optionally, the first jack, the second jack and the third jack are all hydraulic jacks.

[0030] Optionally, a second force sensor is used to detect and record the force state of the second jack.

[0031] In a second aspect, the present invention provides a method for testing the torsional performance or shearing performance of a recycled concrete beam specimen, based on the above-mentioned testing device, comprising:

[0032] Step 1: Make a steel pedestal with a cross groove;

[0033] Step 2: Make a hoop with a hoop gear and a first jack with a power transmission gear, and assemble the two;

[0034] Step 3: Make the heating mechanism;

[0035] Step 4: Assemble the components of step 2 and step 3 together, and install the axial compression mechanism of the concrete specimen;

[0036] A frame with a first jack and a first force sensor is welded on a pedestal with a cross groove, and a hoop with a concrete specimen and a heating mechanism are placed in the groove of the pedestal. The U-shaped heat-conducting carbon rod terminal passes through a mullite brick and is connected to a three-phase high-current transformer to control the temperature. An axial pressure mechanism, namely a steel loading plate, a second force sensor and a second jack, is placed on the top of the concrete specimen to put the concrete specimen in an axial pressure state.

[0037] Step 5: Make a shearing mechanism, which consists of mullite bricks, a third force sensor and a third jack; the third force sensor is placed on the top of the third jack to record the stress state of the third jack.

[0038] Step 6: Place the shear mechanism in step 5 into the grooved stand in step 4;

[0039] First, before conducting the shear test, retract the piston rod of the first jack;

[0040] Then, the prestressed tensioning oil pump controls the lifting and lowering of the third jack, and the piston rod of the third jack presses against the steel structure hoop. After continued pressurization, shear failure occurs at the steel structure hoop of the concrete specimen.

[0041] Step 7: Calculate torsional stress;

[0042] According to the torsional stress calculation formula τ=T / A; where T is the torque, T=F×r1, F is the force value, obtained by the first force sensor on the first jack, r1 is the force arm; A is the cross-sectional area of ​​the concrete specimen;

[0043] Step 8: Calculate shear stress;

[0044] According to the shear stress formula τ=F / A, F is the force value, and the third force sensor on the third jack obtains that A is the cross-sectional area of ​​the concrete specimen

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] The present invention can be used to test the torsion and shear strength of concrete beams under the coupling of high temperature and axial compression. Traditional structures often only focus on torsion (torque) or shear (shear force) testing, but in actual applications, the structure may be affected by these two forces and the environment at the same time. The device tests the torsion and shear strength of the structure under the coupling of high temperature and axial compression. The device integrates the functions of structural torsion and shear, rather than a single function, which makes the device more suitable for testing multiple mechanical properties of the structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 A schematic diagram of the overall structure of a device for testing the torsional performance or shear performance of a recycled concrete beam specimen provided in an embodiment of the present application;

[0048] Figure 2 It is a structural diagram of the pedestal;

[0049] Figure 3 is a schematic diagram of the assembly of the first jack and the hoop;

[0050] Figure 4 The figure is a schematic diagram of the installation of the first jack in the frame;

[0051] Figure 5 It is a structural schematic diagram of the heating mechanism;

[0052] Figure 6 It is a structural schematic diagram of the torsional performance test device of concrete beam specimens under the coupling of high temperature and axial compression;

[0053] Figure 7 It is a schematic diagram of the shearing mechanism;

[0054] Figure 8 It is a structural schematic diagram of the shear performance test device of concrete beam specimens under the coupling of high temperature and axial compression;

[0055] Fig. 9 To solve the torsional stress diagram;

[0056] Fig.10 Schematic diagram for solving shear stress

[0057] In the figure: 1, pedestal; 2, second jack; 3, first jack; 4, first force sensor; 5, frame; 6, mullite brick; 7, thermal conductive carbon rod; 8, concrete specimen; 9, oil pipe; 10, ferrule; 11, loading plate; 12, mullite brick with U-shaped groove; 13, third jack; 14, second force sensor; 15, third force sensor. DETAILED DESCRIPTION

[0058] Example:

[0059] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0060] In the description of the present application, it should be understood that if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0061] In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, if the term "plurality" appears, "plurality" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0062] In this application, unless otherwise clearly specified and limited, if the terms "install", "connect", "connect", "fix" and the like appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the above terms can be understood in their specific meanings in this application according to the specific circumstances.

[0063] In this application, unless otherwise clearly specified and limited, if there is a description such as "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, "above", "above" and "above" a first feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. "Below", "below" and "below" a first feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0064] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. If any, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are for illustrative purposes only and do not represent the only implementation method.

[0065] See also Figure 1 As shown, a torsional performance or shear performance testing device for a recycled concrete beam specimen provided in this embodiment mainly includes a first jack 2, a hoop 10, a first force sensor 4, a heating mechanism, a second jack 2, a second force sensor 14, a third jack 13 and a third force sensor 15.

[0066] Among them, Figure 2 As shown, a force transmission gear is arranged on the piston rod of the first jack 2; the hoop 2 is used to clamp the concrete specimen 8, and a hoop gear is arranged on one side of the hoop 8. The force transmission gear and the hoop gear are meshed with each other, so as to drive the rotation of the hoop 8 through the lifting and lowering of the first jack 2, thereby causing torsional damage to the concrete specimen 8; the first force sensor 4 is used to detect and record the stress state of the first jack 2, so as to obtain the force value required for the rotation. Specifically, the first force sensor 4 is arranged at the top of the first jack 2 to record the stress state of the jack. The data of the first force sensor 4 is collected by the Donghua acquisition system. The lifting and lowering of the first jack 2 is realized by connecting the prestressed tensioning oil pump with the first jack through the oil pipe 9.

[0067] The heating mechanism is used to heat the concrete specimen, and the heating temperature is adjustable.

[0068] The second jack 2 is used to apply pressure to the axial end of the concrete specimen 8, so that the concrete specimen is in an axial compression state, and the second force sensor 14 is used to detect and record the stress state of the second jack.

[0069] The third jack 13 is used to apply pressure to the side of the hoop 10 where the hoop gear is not provided; the third force sensor 15 is used to detect and record the force state of the third jack 13 .

[0070] It can be seen that the torsional performance or shear performance test device for the recycled concrete beam specimen provided in this embodiment can simultaneously realize the torsional performance or shear performance test of the concrete beam specimen under the coupling of high temperature and axial pressure under the coordinated action of the first jack, the second jack, the third jack and the heating mechanism.

[0071] In a specific embodiment, if Figure 5 As shown, the heating mechanism includes two mullite bricks 6, between which a mullite brick with a U-shaped groove 12 is arranged, in which a U-shaped heat-conducting carbon rod 7 is arranged, and the terminal of the U-shaped heat-conducting carbon rod passes through the mullite brick 6 to connect to a three-phase high-current transformer to control the temperature. When the hoop 10 is clamped with the concrete specimen 8, since the hoop 10 protrudes from the surface of the concrete specimen 8, the hoop 10 is placed on the mullite brick with a U-shaped groove 12 to heat the concrete specimen 8, and the two ends of the concrete specimen 8 are placed on the two mullite bricks 6 of the heating mechanism.

[0072] Most of the existing shear and torsion tests require precise alignment of the component with the test fixture to ensure that the load acts on the center of the specimen, and the component processing accuracy is high. For this reason, in a preferred embodiment, the torsion or shear performance test device of the recycled concrete beam specimen also includes a pedestal 1, such as Figure 2 As shown, the base is provided with a cross-shaped groove; Figure 7 As shown, the transverse groove of the cross-shaped groove is used to place the heating mechanism and the second jack 2, the middle intersection position of the cross-shaped groove is the placement position of the hoop 10, one end of the concrete specimen 8 is against the inner wall of one end of the transverse groove, and the other end of the concrete specimen 8 is placed with the second jack 2; one side of the vertical groove of the cross-shaped groove is used to place the third front jack, as shown in FIG. Figure 1 and 4 As shown, the upper part of the other side of the vertical groove is used to install the frame 5, and the frame 5 is used to install the first jack 3. In this way, the first jack 3, the second jack 2, the third jack 13 and the heating mechanism and other components are placed on the pedestal, and there is no need to align them with the experimental fixture. The processing accuracy of the entire device is low, which is more convenient for testing.

[0073] In a specific embodiment, in order to prevent the second jack 2 from damaging the shaft end of the concrete specimen 8 , a loading plate 11 is provided between the second jack 2 and the shaft end of the concrete specimen 8 .

[0074] In a specific embodiment, the second force sensor 14 is arranged on the top of the second jack 2; the third force sensor 15 is arranged on the top of the third front jack 13. The third jack 13 is placed on the mullite brick 6. The first jack 3, the second jack 2 and the third jack 13 are all hydraulic jacks. The pedestal 1 is a steel pedestal, the frame is a high-temperature alloy steel frame, the hoop is a steel structure hoop, and the loading plate is a steel loading plate.

[0075] Accordingly, this embodiment also provides a method for manufacturing a device for testing the torsional performance or shear performance of a recycled concrete beam specimen, which specifically includes the following steps:

[0076] Step 1: Make a steel base with a cross groove, and use laser cutting and welding steel plate technology to achieve this configuration, such as Figure 2 shown.

[0077] Step 2: Make a steel structure hoop with a partial hoop gear and a first jack with a force transmission gear. The gears of the two components mesh with each other, so that the lifting of the jack drives the steel structure hoop to rotate, thereby causing torsional damage to the concrete specimen. In order to obtain the force value required for torsion, the first jack with the force transmission gear and the first force sensor are placed on a high-temperature alloy steel frame for fixation. The first force sensor is placed on the top of the first jack to record the force state of the jack, and the data of the force sensor is collected by the Donghua acquisition system. The lifting of the first jack is achieved by connecting the prestressed tensioning oil pump to the first jack through an oil pipe, such as Figure 3-4 shown.

[0078] Step 3: Make a high temperature heating mechanism. Figure 5 As shown, it is composed of two mullite bricks, a mullite brick with a U-shaped groove and a U-shaped heat-conducting carbon rod. The U-shaped heat-conducting carbon rod is placed on the mullite brick with a U-shaped groove, and the terminal of the U-shaped heat-conducting carbon rod passes through the mullite brick and connects to a three-phase high-current transformer to control the temperature.

[0079] Step 4: Combine the components of the second and third steps, and install the axial compression mechanism of the concrete specimen. Weld the high-temperature alloy steel frame with the first jack and force sensor to the high-temperature alloy steel pedestal with grooves, and put the steel structure hoop with the concrete specimen and the high-temperature heating mechanism into the grooves of the high-temperature alloy steel pedestal. The U-shaped heat-conducting carbon rod terminal passes through the mullite brick and connects to the three-phase high-current transformer to control the temperature. Place the axial compression mechanism, namely the steel loading plate, the second force sensor and the second jack, on the top of the concrete specimen, so that the concrete specimen can be placed in an axial compression state. Figure 6 shown.

[0080] Step 5: Make the shearing mechanism. Figure 7As shown, it is composed of mullite bricks, a third force sensor and a third jack. The third force sensor is placed on the top of the third jack to record the stress state of the third jack.

[0081] Step 6: Place the shear mechanism in step 5 on the grooved high-temperature alloy steel pedestal in step 4. First, retract the piston rod of the first jack before the shear test. Then, the prestressed tensioning oil pump controls the lifting and lowering of the third jack, and the piston rod of the third jack presses against the steel structure hoop. After continued pressurization, shear failure occurs at the steel structure hoop of the concrete specimen, thereby achieving shear failure of the concrete component under the coupling of high temperature and axial pressure, such as Figure 8 Shown

[0082] Step 7: Calculate torsional stress. According to the torsional stress calculation formula τ = T / A. Where T is the torque, T = F × r1, F is the force value, which can be obtained by the first force sensor on the first jack, r1 is the force arm; A is the cross-sectional area of ​​the concrete specimen. Fig. 9 shown.

[0083] Step 8: Calculate shear stress. According to the shear stress formula τ = F / A, F is the force value, which can be obtained through the third force sensor on the third jack, and A is the cross-sectional area of ​​the concrete specimen. The shear stress can be deduced according to the calculation formula. Fig.10 shown.

[0084] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable ordinary technicians in the field to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made based on the essence of the content of the present invention should be included in the protection scope of the present invention.

Claims

1. A device for testing the torsional performance or shearing performance of a recycled concrete beam specimen, characterized in that: include: A first jack, wherein a force transmission gear is arranged on a piston rod of the first jack; A hoop, the hoop is used to clamp the concrete specimen; a hoop gear is provided on one side of the hoop, the force transmission gear and the hoop gear are meshed, so that the hoop is driven to rotate by the lifting and lowering of the first jack, causing torsional damage to the concrete specimen; A first force sensor, used for detecting and recording the force state of the first jack; The heating mechanism is used to heat the concrete specimen. The second jack is used to apply pressure to the axial end of the concrete specimen so that the concrete specimen is in an axial compression state; a third jack, for applying pressure to the side of the hoop that is not provided with the hoop gear; The third force sensor is used to detect and record the force state of the third jack.

2. The torsional performance or shearing performance testing device of the recycled concrete beam specimen according to claim 1, characterized in that: The heating mechanism includes two mullite bricks, a mullite brick with a U-shaped groove is arranged between the two mullite bricks, a U-shaped heat-conducting carbon rod is arranged in the mullite brick with the U-shaped groove, and the connection end of the U-shaped heat-conducting carbon rod passes through the first mullite brick or the second mullite brick to connect a three-phase high-current transformer to achieve temperature control.

3. The torsional performance or shearing performance testing device of the recycled concrete beam specimen according to claim 2, characterized in that: After the hoop clamps the concrete specimen, the hoop is placed on the mullite brick with the U-shaped groove, and the two ends of the concrete specimen are placed on the two mullite bricks of the heating mechanism.

4. The torsional performance or shearing performance testing device of the recycled concrete beam specimen according to claim 3, characterized in that: It also includes a base, which is provided with a cross-shaped groove; the lateral groove of the cross-shaped groove is used to place the heating mechanism and the second jack, and the middle intersection position of the cross-shaped groove is the placement position of the hoop; one side of the vertical groove of the cross-shaped groove is used to place the third front jack, and the other side and upper part of the vertical groove are used to install a frame, and the frame is used to install the first jack.

5. The torsional performance or shearing performance testing device of the recycled concrete beam specimen according to claim 1 or 4, characterized in that: A loading plate is arranged between the second jack and the shaft end of the concrete specimen; the second jack, the loading plate and the second force sensor constitute an axial pressure mechanism.

6. The torsional performance or shearing performance testing device of the recycled concrete beam specimen according to claim 1, characterized in that: The first force sensor is arranged on the top of the first jack; the second force sensor is arranged on the top of the second jack; and the third force sensor is arranged on the top of the third front jack.

7. The torsional performance or shearing performance testing device of a recycled concrete beam specimen according to claim 1 or 4, characterized in that: The third jack is placed on the mullite brick; the third jack, the mullite brick and the third force sensor constitute a shearing mechanism.

8. The torsional performance or shearing performance testing device of a recycled concrete beam specimen according to claim 1, characterized in that: The first jack, the second jack and the third jack are all hydraulic jacks.

9. The torsional performance or shearing performance testing device of a recycled concrete beam specimen according to claim 1, characterized in that: The second force sensor is used to detect and record the force state of the second jack.

10. A method for testing the torsional performance or shearing performance of a recycled concrete beam specimen, based on the testing device according to claim 1, characterized in that: include: Step 1: Make a steel pedestal with a cross groove; Step 2: Make a hoop with a hoop gear and a first jack with a power transmission gear, and assemble the two; Step 3: Make the heating mechanism; Step 4: Assemble the components of step 2 and step 3 together, and install the axial compression mechanism of the concrete specimen; A frame with a first jack and a first force sensor is welded on a pedestal with a cross groove, and a sleeve with a concrete specimen and a heating mechanism are placed in the groove of the pedestal. The U-shaped heat-conducting carbon rod terminal passes through a mullite brick and is connected to a three-phase high-current transformer to control the temperature. An axial pressure mechanism, namely a steel loading plate, a second force sensor and a second jack, is placed on the top of the concrete specimen to put the concrete specimen in an axial pressure state. Step 5: Make a shearing mechanism, which consists of mullite bricks, a third force sensor and a third jack; the third force sensor is placed on the top of the third jack to record the stress state of the third jack. Step 6: Place the shear mechanism in step 5 into the grooved stand in step 4; First, before conducting the shear test, retract the piston rod of the first jack; Then, the prestressed tensioning oil pump controls the lifting and lowering of the third jack, and the piston rod of the third jack presses against the steel structure hoop. After continued pressurization, shear failure occurs at the steel structure hoop of the concrete specimen. Step 7: Calculate torsional stress; According to the torsional stress calculation formula τ=T / A; where T is the torque, T=F×r1, F is the force value, obtained by the first force sensor on the first jack, r1 is the force arm; A is the cross-sectional area of ​​the concrete specimen; Step 8: Calculate shear stress; According to the shear stress formula τ=F / A, F is the force value, and the third force sensor on the third jack obtains that A is the cross-sectional area of ​​the concrete specimen.

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