A concrete axial tension self-balancing test device and test method

Abstract

The present invention relates to a concrete axial tension self-balancing test device in the field of concrete testing technology, including a vertical tension test mechanism and a horizontal tension test mechanism; the vertical tension test mechanism includes a reinforcement plate 1, a reinforcement plate 2, a reinforcement plate 3 and a reinforcement plate 4, and the pressure is converted into tension through a jack 1, and the horizontal tension test mechanism includes reinforcement plates 5, 6, 7, 8 and 9, and the pressure is converted into tension through a jack 2. During the test, the concrete specimen is respectively bonded to the reinforcement plate 2, the reinforcement plate 1, the reinforcement plate 6 and the reinforcement plate 7 through epoxy resin glue. By applying force in two directions at the same time, the tensile strength of the concrete component when it is simultaneously subjected to force in two directions can be more accurately tested. The concrete specimen can be self-balanced when subjected to tension, is not prone to overload, and the test result is more accurate.

Description

Technical Field

[0001] The invention belongs to the technical field of civil engineering concrete testing, and in particular relates to a self-balancing testing device for concrete axial tension. Background Art

[0002] The axial tensile strength of concrete is an important mechanical index. In the past, when determining the axial tensile strength of concrete, the main test methods can be divided into two categories: one is the direct test method, that is, the direct axial tensile test method; the other is the indirect test method, including the splitting test method and the bending tensile test method. The splitting test is commonly used at home and abroad to test the axial tensile strength of concrete, but a large number of tests have shown that the splitting test method cannot truly reflect the axial tensile strength of concrete, and the splitting tensile strength is slightly greater than the direct tensile strength. In order to meet the test requirements and obtain more accurate tensile strength, it is very necessary to conduct a direct tensile test on the concrete specimen.

[0003] In direct tensile tests, it is particularly important to use a simple and easy method to ensure that the specimen is axially tensile and the stress is evenly distributed. The concrete direct tensile specimens currently used can be divided into external clamping, internal embedding and bonding types. The external clamping type is generally prone to stress concentration at the clamping point. For inorganic brittle materials such as concrete, fracture is easy to occur at the clamping point, and it is difficult to ensure that the fracture occurs at the uniform stress. The internal embedding type is difficult to ensure that the specimen is axially tensile, and the stress distribution in the specimen is also relatively complex. The bonding type is relatively easy to ensure that the axial tension is applied, and the stress distribution in the specimen is more uniform than the first two methods. The probability of fracture occurring in the uniform stress section is higher, but there is also the phenomenon of uneven stress distribution. It can be seen that the above methods all have their own defects and cannot meet the requirements of direct tensile tests well. The root cause of the above problems is that there will be different degrees of eccentricity during the direct tensile test of concrete materials, which will lead to inaccurate tensile test data. Summary of the invention

[0004] The purpose of the present invention is to provide a concrete axial tension self-balancing test device, which can accurately and effectively carry out concrete axial tension tests, avoid eccentric force on the concrete axis, is simple and convenient to operate, and can meet the test requirements of stiffness and accuracy.

[0005] In order to achieve the above-mentioned object, the present invention proposes the following technical scheme: a concrete axial tension self-balancing test device, comprising a vertical tension test mechanism and a horizontal tension test mechanism;

[0006] Vertical tensile testing mechanism: comprising reinforcing plate 1, reinforcing plate 2, reinforcing plate 3 and reinforcing plate 4 which are parallel to each other and whose centers are located on the same longitudinal axis, wherein reinforcing plate 1, reinforcing plate 2, reinforcing plate 3 and reinforcing plate 4 are arranged in sequence from bottom to top; reinforcing plate 1 and reinforcing plate 3 are respectively fixedly connected at four corners by four first screws arranged in parallel; reinforcing plate 2 and reinforcing plate 4 are respectively fixedly connected at four corners by four second screws arranged in parallel; the first screw passes through reinforcing plate 2 with a gap, and the second screw passes through reinforcing plate 3 with a gap; a jack 1 is arranged between reinforcing plate 3 and reinforcing plate 4, the bottom support of the jack 1 is at the center of reinforcing plate 3, and a pressure sensor 1 is arranged between the top of the jack 1 and the center of reinforcing plate 4;

[0007] Horizontal tensile testing mechanism: comprising reinforcing plates 5, 6, 7, 8 and 9 which are parallel to each other and whose centers are located on the same axis; the four corners of reinforcing plates 5 and 8 are respectively fixedly connected by four third screws arranged in parallel; the four corners of reinforcing plates 7 and 9 are respectively fixedly connected by four fourth screws arranged in parallel; the fourth screw passes through reinforcing plate 8 with a gap, and the four corners of reinforcing plates 5 and 6 are fixedly connected by four fifth screws; a jack 2 is arranged between reinforcing plates 8 and 9, one end of the jack 2 is supported at the center of reinforcing plate 8, and a pressure sensor 2 is arranged between the other end of the jack 2 and the center of reinforcing plate 9;

[0008] The reinforcing plate six and the reinforcing plate seven are located between the reinforcing plate one and the reinforcing plate two; the reinforcing plate one, the reinforcing plate two, the reinforcing plate six and the reinforcing plate seven enclose a space for placing the concrete specimen; during the test, the upper, lower, left and right sides of the concrete specimen are respectively bonded to the reinforcing plate two, the reinforcing plate one, the reinforcing plate six and the reinforcing plate seven by epoxy resin glue.

[0009] As a further improvement of the present invention, the reinforcing plate six and the reinforcing plate seven can be movably placed on the upper surface of the reinforcing plate one, a pad is welded on the side of the jack two, and the bottom of the pad is on the same horizontal plane as the bottom surface of the reinforcing plate one, so that the axis of the jack two coincides with the axis of the reinforcing plates five, six, seven, eight and nine.

[0010] Furthermore, the jack 1 and the jack 2 may be separate hydraulic jacks; the sensor 1 and the sensor 2 may be spoke-type tension and compression sensors.

[0011] The present invention also provides a test method for a concrete axial tension self-balancing test device, comprising the following steps:

[0012] 1) Prepare a concrete specimen with a rectangular horizontal cross section;

[0013] 2) Release the pressure and take out Jack 1, Jack 2, Sensor 1 and Sensor 2, so that the reinforcing plates 1 and 2 can move relative to each other, and at the same time, the reinforcing plates 6 and 7 can move relative to each other;

[0014] 3) Place the concrete specimen in the space enclosed by reinforcing plate 1, reinforcing plate 2, reinforcing plate 6 and reinforcing plate 7, so that the concrete specimen is in contact with reinforcing plate 1, reinforcing plate 2, reinforcing plate 6 and reinforcing plate 7;

[0015] 4) Apply epoxy resin glue on the contact surface between the concrete specimen and the reinforcing plate 1, reinforcing plate 2, reinforcing plate 6 and reinforcing plate 7, and wait for the epoxy resin glue to fully cure;

[0016] 5) Install Jack 1, Jack 2, Sensor 1 and Sensor 2, and use Jack 1 and Jack 2 to apply pressure in the vertical and horizontal directions simultaneously. The pressure from Jack 1 forms a vertical tensile force between reinforcing plates 1 and 2, and the pressure from Jack 2 forms a horizontal tensile force between reinforcing plates 6 and 7, until the concrete specimen is stretched and broken; continuously record the readings of Sensor 1 and Sensor 2 during the stretching process.

[0017] Due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0018] (1) The test device is composed of steel plates and screws. It has a small structural mass, is easy to transport and install, and can be directly manufactured in the factory.

[0019] (2) The test device can quickly, effectively and accurately carry out the concrete axial tension test. It can convert the pressure of the jack into tension. The jack and the concrete specimen are set coaxially to ensure that the concrete specimen is subjected to axial tension and avoid eccentric force.

[0020] (3) In the vertical direction, reinforcing plates 1 and 3 form a whole, and reinforcing plates 2 and 4 form a whole. During the test, the forces from the concrete specimen and jack 1 make the above two wholes self-balanced, thereby ensuring that the force is in the longitudinal direction and the concrete specimen is not subjected to the eccentric load. Similarly, the same is true in the horizontal direction. The difference is that in the horizontal direction, reinforcing plates 5, 6 and 8 form a whole. The purpose of setting reinforcing plate 6 is to facilitate the installation of smaller concrete specimens. Before jacks 1 and 2 work, the entire device will not be skewed during the entire installation process.

[0021] (4) It realizes the simultaneous tensile testing of concrete specimens in both vertical and horizontal directions, which can more accurately test the tensile strength of concrete components when they are subjected to forces in two directions at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the structure of the present invention.

[0023] Figure 2 This is a three-dimensional structural diagram of the present invention after the reinforcement plate four and the reinforcement plate nine are removed.

[0024] Figure 3 For Figure 2 A three-dimensional structural diagram of the present invention after jack one, reinforcing plate two and reinforcing plate three are further removed on the basis of the present invention.

[0025] In the figure, 1 is reinforcement plate one, 2 is reinforcement plate two, 3 is reinforcement plate three, 4 is reinforcement plate four, 5 is reinforcement plate five, 6 is reinforcement plate six, 7 is reinforcement plate seven, 8 is reinforcement plate eight, 9 is reinforcement plate nine, 10 is fifth screw, 11 is first screw, 12 is second screw, 13 is third screw, 14 is fourth screw, 15 is sensor one, 16 is jack one, 17 is sensor two, 18 is jack two, 19 is pad, and 20 is concrete specimen. DETAILED DESCRIPTION

[0026] like Figure 1-3 As shown, a concrete axial tension self-balancing test device is composed of a vertical tension test mechanism and a horizontal tension test mechanism.

[0027] Vertical tensile testing mechanism: comprising reinforcing plate 1, reinforcing plate 2, reinforcing plate 3, and reinforcing plate 4, which are parallel to each other and whose centers are located on the same longitudinal axis, and reinforcing plate 1, reinforcing plate 2, reinforcing plate 3, and reinforcing plate 4 are arranged in sequence from bottom to top; the four corners of reinforcing plate 1 and reinforcing plate 3 are respectively fixedly connected by four parallel first screws 11; the four corners of reinforcing plate 2 and reinforcing plate 4 are respectively fixedly connected by four parallel second screws 12; the first screw 11 passes through reinforcing plate 2 with a gap, and the second screw 12 passes through reinforcing plate 3 with a gap; a jack 16 is arranged between reinforcing plate 3 and reinforcing plate 4, the bottom support of jack 16 is at the center of reinforcing plate 3, and a pressure sensor 15 is arranged between the top of jack 16 and the center of reinforcing plate 4; the reinforcing plate is made of square metal plate.

[0028] Horizontal tensile testing mechanism: comprising reinforcing plate five 5, reinforcing plate six 6, reinforcing plate seven 7, reinforcing plate eight 8 and reinforcing plate nine 9 which are parallel to each other and whose centers are located on the same axis; the four corners of reinforcing plate five 5 and reinforcing plate eight 8 are fixedly connected by four third screws 13 arranged in parallel; the four corners of reinforcing plate seven 7 and reinforcing plate nine 9 are fixedly connected by four fourth screws 14 arranged in parallel; the fourth screw 14 passes through reinforcing plate eight 8 with a gap, and the four corners of reinforcing plate five 5 and reinforcing plate six 6 are fixedly connected by four fifth screws 10; a jack two 18 is arranged between reinforcing plate eight 8 and reinforcing plate nine 9, one end of the jack two 18 is supported on the center of reinforcing plate eight 8, and a pressure sensor two 17 is arranged between the other end of the jack two 18 and the center of reinforcing plate nine 9.

[0029] Reinforcing plate six 6 and reinforcing plate seven 7 are located between reinforcing plate one 1 and reinforcing plate two 2; reinforcing plate one 1, reinforcing plate two 2, reinforcing plate six 6 and reinforcing plate seven 7 enclose a space for placing the concrete specimen 20; during the test, the upper, lower, left and right sides of the concrete specimen 20 are respectively bonded to reinforcing plate two 2, reinforcing plate one 1, reinforcing plate six 6 and reinforcing plate seven 7 by epoxy resin glue.

[0030] Reinforcing plate six 6 and reinforcing plate seven 7 are movably placed on the upper surface of reinforcing plate one 1, and a pad 19 is welded to the side of jack two 18, and the bottom of pad 19 is on the same horizontal plane as the bottom surface of reinforcing plate one 1, so that the axis of jack two 18 coincides with the axis of reinforcing plate five 5, reinforcing plate six 6, reinforcing plate seven 7, reinforcing plate eight 8, and reinforcing plate nine 9.

[0031] Jack 1 16 and jack 2 18 are separate hydraulic jacks; sensor 1 15 and sensor 2 17 are spoke-type tension and compression sensors.

[0032] When conducting a concrete sample tensile test, proceed as follows:

[0033] 1) Prepare a concrete specimen 20 with a rectangular horizontal cross section.

[0034] 2) Release the pressure and remove the jack 16, jack 2 18, sensor 1 15 and sensor 2 17, so that the reinforcing plate 1 1 and reinforcing plate 2 2 can move relative to each other, and at the same time, the reinforcing plate 6 6 and reinforcing plate 7 7 can move relative to each other.

[0035] 3) Place the concrete specimen 20 into a space enclosed by the reinforcing plate 1 1 , the reinforcing plate 2 2 , the reinforcing plate 6 6 and the reinforcing plate 7 7 , so that the concrete specimen 20 is in contact with the reinforcing plate 1 1 , the reinforcing plate 2 2 , the reinforcing plate 6 6 and the reinforcing plate 7 7 .

[0036] 4) Apply epoxy resin glue on the contact surfaces between the concrete specimen 20 and the reinforcing plate 1 1 , the reinforcing plate 2 2 , the reinforcing plate 6 6 and the reinforcing plate 7 7 , and wait for the epoxy resin glue to fully cure.

[0037] 5) Install jack 16, jack 2 18, sensor 15 and sensor 2 17, and use jack 16 and jack 2 18 to apply pressure in the vertical and horizontal directions simultaneously. The pressure from jack 16 forms a tensile force in the vertical direction between reinforcing plate 1 and reinforcing plate 2, and the pressure from jack 2 18 forms a tensile force in the horizontal direction between reinforcing plate 6 6 and reinforcing plate 7 7, until the concrete specimen 20 is stretched and broken; the readings of sensor 15 and sensor 2 17 are continuously recorded during the stretching process.

[0038] Its beneficial effects are:

[0039] (1) The test device is composed of steel plates and screws. It has a small structural mass, is easy to transport and install, and can be directly manufactured in the factory.

[0040] (2) The test device can quickly, effectively and accurately carry out the concrete axial tension test, and can convert the pressure of the jack into tension. The jack and the concrete specimen 20 are arranged coaxially to ensure that the concrete specimen 20 is subjected to axial tension; eccentric force can be avoided.

[0041] (3) In the vertical direction, reinforcing plate 1 and reinforcing plate 3 3 form a whole, and reinforcing plate 2 2 and reinforcing plate 4 4 ​​form a whole. When the test is carried out, the force from the concrete specimen 20 and the jack 1 16 makes the above two wholes self-balanced, thereby ensuring that the force is in the longitudinal direction and the concrete specimen 20 is not subjected to the eccentric load. The same is true in the horizontal direction. The difference is that in the horizontal direction, reinforcing plate 5 5, reinforcing plate 6 6, and reinforcing plate 8 8 form a whole. The purpose of setting reinforcing plate 6 6 is to facilitate the installation of the smaller concrete specimen 20. Before jack 1 16 and jack 2 18 work, the whole device will not be skewed during the entire installation process.

[0042] (4) It realizes the simultaneous tensile test of the concrete specimen 20 in both vertical and horizontal directions, and can more accurately test the tensile strength of the concrete member when it is subjected to forces in two directions at the same time.

[0043] The present invention is not limited to the above-mentioned embodiments. On the basis of the technical solution disclosed in the present invention, technicians in this field can make some substitutions and deformations to some technical features therein according to the disclosed technical content without creative labor, and these substitutions and deformations are all within the protection scope of the present invention.

Claims

1. A concrete axial tension self-balancing test device, characterized in that: It includes a vertical tensile test mechanism and a horizontal tensile test mechanism; Vertical tensile testing mechanism: comprising reinforcing plate 1, reinforcing plate 2, reinforcing plate 3 and reinforcing plate 4 which are parallel to each other and whose centers are located on the same longitudinal axis, wherein reinforcing plate 1, reinforcing plate 2, reinforcing plate 3 and reinforcing plate 4 are arranged in sequence from bottom to top; reinforcing plate 1 and reinforcing plate 3 are respectively fixedly connected at four corners by four first screws arranged in parallel; reinforcing plate 2 and reinforcing plate 4 are respectively fixedly connected at four corners by four second screws arranged in parallel; the first screw passes through reinforcing plate 2 with a gap, and the second screw passes through reinforcing plate 3 with a gap; a jack 1 is arranged between reinforcing plate 3 and reinforcing plate 4, the bottom support of the jack 1 is at the center of reinforcing plate 3, and a pressure sensor 1 is arranged between the top of the jack 1 and the center of reinforcing plate 4; Horizontal tensile testing mechanism: comprising reinforcing plates 5, 6, 7, 8 and 9 which are parallel to each other and whose centers are located on the same axis; the four corners of reinforcing plates 5 and 8 are respectively fixedly connected by four third screws arranged in parallel; the four corners of reinforcing plates 7 and 9 are respectively fixedly connected by four fourth screws arranged in parallel; the fourth screw passes through reinforcing plate 8 with a gap, and the four corners of reinforcing plates 5 and 6 are fixedly connected by four fifth screws; a jack 2 is arranged between reinforcing plates 8 and 9, one end of the jack 2 is supported at the center of reinforcing plate 8, and a pressure sensor 2 is arranged between the other end of the jack 2 and the center of reinforcing plate 9; The reinforcing plate six and the reinforcing plate seven are located between the reinforcing plate one and the reinforcing plate two; the reinforcing plate one, the reinforcing plate two, the reinforcing plate six and the reinforcing plate seven enclose a space for placing the concrete specimen; during the test, the upper, lower, left and right sides of the concrete specimen are respectively bonded to the reinforcing plate two, the reinforcing plate one, the reinforcing plate six and the reinforcing plate seven by epoxy resin glue; The reinforcing plates 6 and 7 can be movably placed on the upper surface of the reinforcing plate 1, and a pad is welded on the side of the jack 2, and the bottom of the pad is on the same horizontal plane as the bottom surface of the reinforcing plate 1, so that the axis of the jack 2 coincides with the axis of the reinforcing plates 5, 6, 7, 8 and 9.

2. A concrete axial tension self-balancing test device according to claim 1, characterized in that: The jack 1 and the jack 2 are separate hydraulic jacks.

3. A concrete axial tension self-balancing test device according to claim 1, characterized in that: The sensor 1 and the sensor 2 are spoke-type tension and compression sensors.

4. The test method of a concrete axial tension self-balancing test device according to claim 1 is characterized in that The steps include: 1) Prepare a concrete specimen with a rectangular horizontal cross section; 2) Release the pressure and take out Jack 1, Jack 2, Sensor 1 and Sensor 2, so that the reinforcing plates 1 and 2 can move relative to each other, and at the same time, the reinforcing plates 6 and 7 can move relative to each other; 3) Place the concrete specimen into the space enclosed by reinforcing plate 1, reinforcing plate 2, reinforcing plate 6 and reinforcing plate 7, so that the concrete specimen is in contact with reinforcing plate 1, reinforcing plate 2, reinforcing plate 6 and reinforcing plate 7; 4) Apply epoxy resin glue on the contact surface between the concrete specimen and the reinforcing plate 1, reinforcing plate 2, reinforcing plate 6 and reinforcing plate 7, and wait for the epoxy resin glue to fully cure; 5) Install Jack 1, Jack 2, Sensor 1 and Sensor 2, and use Jack 1 and Jack 2 to apply pressure in the vertical and horizontal directions simultaneously. The pressure from Jack 1 forms a vertical tensile force between reinforcing plates 1 and 2, and the pressure from Jack 2 forms a horizontal tensile force between reinforcing plates 6 and 7, until the concrete specimen is stretched and broken; continuously record the readings of Sensor 1 and Sensor 2 during the stretching process.

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