Clamping device for strain measurement of high-toughness concrete

Abstract

The invention relates to the technical field of high-toughness concrete measurement, and discloses a clamping device for high-toughness concrete strain measurement. Comprising four extension arms symmetrically and uniformly distributed on the left side and the right side of a concrete test piece, attaching assemblies connected to the ends of the extension arms and an elastic traction assembly for tensioning the two attaching pieces with the same height, and the two extension arms on one side of the concrete test piece are close to the two size gradual change positions of the concrete test piece correspondingly; the attaching assembly comprises bearing plates, clamping blocks and damping pads, the bearing plates are fixedly connected with the ends of the extension arms, the clamping blocks are fixedly connected to the side walls of the sides, close to the concrete test piece, of the bearing plates, when the clamping blocks on the two bearing plates at the same height horizontally and continuously move in the close direction, the contact faces of the clamping blocks abut against the concrete test piece, and the damping pads abut against the concrete test piece. And the damping pad is made of a soft material. According to the invention, the concrete test piece can be firmly clamped, the extension arm is prevented from retracting due to vibration force in the tensile test process, and the accuracy of test data is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of high-toughness concrete measurement, and in particular to a clamping device for high-toughness concrete strain measurement. Background Art

[0002] High-toughness concrete is a new type of building material. It is composed of cement, mineral admixtures, admixtures and chopped fibers. The uniform distribution of fibers effectively prevents crack expansion and greatly improves the toughness and tensile strength of concrete. It has a dense microstructure, low porosity, and strong resistance to impermeability, frost and chemical corrosion. High-toughness concrete can withstand greater deformation without damage and is suitable for bridge engineering. It can enhance the safety of bridge decks and bridge structures. In the construction field, it is used in key parts of high-rise buildings and underground projects to improve earthquake resistance and durability. It can also be used in water conservancy, roads, tunnels and other projects. In the research and application of high-toughness concrete, it is very important to accurately measure its deformation in tensile tests in order to achieve accurate calculation and evaluation of the ultimate tensile strain of high-toughness concrete.

[0003] Existing strain measurement is mainly achieved by using two extensometers. The extensometer includes a detection body and two extension arms connected to the detection body. The two extension arms can rotate toward or away from each other. When in use, the two extensometers are respectively set on both sides of the specimen, and the spacing width of the two extension arms of the extensometer is adjusted to the initial predetermined standard spacing value. The two extension arms of the extensometer extend toward one side of the specimen. For the special shape of dumbbell-shaped high-toughness concrete, the extension arm is usually clamped to the concrete specimen in a special way. The existing special clamping device includes a flange portion connected to the end of the extension arm away from the detection body. The two flanges at the same height are wrapped and tied by an annular rubber band. The rubber band is also connected to the extension arm by a preload. The preload makes the extension arms of the same height of the two extensometers clamp the high-toughness concrete. The measured value of the specimen strain is determined by comparing the change in the spacing between the two extension arms on the same side of the extensometer during the test with the initial spacing between the extension arms.

[0004] However, when using existing extensometers to clamp high-toughness concrete dumbbell-shaped specimens, there will be instability problems. The main problem is that cracks will appear in the specimen during the stretching process. The appearance of cracks will also cause high-frequency vibration of the specimen. The vibration force will weaken the clamping force of the clamping device and cause the two extension arms of the extensometer to retract, causing the clamping position to change. This unstable clamping and susceptibility to vibration seriously affect the accuracy of the tensile strain measurement results of high-toughness concrete. Summary of the invention

[0005] The present invention provides a clamping device for high-toughness concrete strain measurement, which can firmly clamp the concrete test piece, avoids the extension arm from retracting due to vibration force during the tensile test, and ensures the accuracy of the test data.

[0006] The present invention provides a clamping device for measuring strain of high-toughness concrete, comprising four extension arms symmetrically and evenly distributed on the left and right sides of a concrete specimen, a fitting assembly connected to the end of each extension arm, and an elastic pulling assembly for tightening two fittings at the same height. The two extension arms on one side of the concrete specimen are respectively close to two size gradients of the concrete specimen. The fitting assembly comprises: a bearing plate, a clamping block, and a damping pad. The bearing plate is fixedly connected to the ends of each extension arm. The clamping block is fixedly connected to a side wall of the bearing plate close to the concrete specimen. When the clamping blocks on the two bearing plates at the same height move horizontally and continuously in a similar direction, the contact surface of the clamping blocks presses against the concrete specimen. The damping pad is made of soft material, fixedly connected to the bearing plate and on the same side as the clamping block. The length of the damping pad extending toward one side of the concrete specimen is longer than the length of the clamping block extending toward one side of the bearing plate.

[0007] Preferably, the distance between two extension arms on the same side is smaller than the distance between two correspondingly connected supporting plates.

[0008] Preferably, each supporting plate is connected to a hanging ear at the front and rear ends, and the hanging ear is provided with a hanging hole in the vertical direction. The elastic pulling assembly includes: a sleeve, a sliding rod, a tension spring, and two hooks. The sleeve is horizontally arranged between two hanging ears at the same height, the sliding rod is slidably inserted in the sleeve, and the tension spring is placed in the sleeve, one end of which is fixedly connected to the inner wall of the sleeve, and the other end is fixedly connected to the end of the sliding rod. The two hooks are respectively fixedly connected to the ends of the sleeve and the sliding rod that are far away from each other, and the two hooks are respectively hooked in the hanging holes of the two hanging ears at the same height.

[0009] Preferably, the side of the supporting plate away from the connecting extension arm is fixedly connected to two box bodies, the box body is provided with a concave cavity, a vertical abutment plate is slidably connected in the concave cavity, a sliding rod is fixedly connected to the middle part of one end surface of the abutment plate close to the adjacent hanging ear, the sliding rod sleeve is provided with a compression spring, the sliding rod is slidably connected to the box body, and the hanging ear is fixedly connected to the end of the sliding rod passing through the box body.

[0010] Preferably, the clamping block is made of metal steel, and the side of the clamping block in contact with the concrete specimen is sharpened, and the damping pad and the concrete specimen are squeezed and deformed to fill in the missing inclined surface of the clamping block.

[0011] Preferably, the damping pad is in strip shape and has a length extending horizontally in the front-to-back direction that is greater than the thickness of the concrete specimen.

[0012] Preferably, the tension spring is made of chromium-molybdenum alloy steel.

[0013] Preferably, the damping pad is made of silicone rubber.

[0014] Preferably, each extension arm has a plurality of through holes along its thickness direction near the corresponding supporting plate, a mounting hole is provided on the side of the supporting plate that fits the extension arm and corresponds to the through holes, and the extension arm is connected to the supporting plate by bolts.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: the provided load-bearing plate can realize the connection between the clamping block and the damping pad and the extension arm, and a high-strength clamping effect is achieved on the load-bearing plates on both sides through a plurality of elastic pulling components, thereby ensuring the stability of the clamping; at the same time, the provided damping pad can utilize its reliable elastic deformation and reset ability to increase the pressing prestress on the concrete specimen; at the same time, the provision of the damping pad can enhance the friction damping force between the clamping block and the concrete specimen; when the clamping block and the concrete specimen are pressed tightly, even if vibration occurs, the extension arm is not easy to deviate and slide sideways under the action of the damping pad, and the damping pad is limited compared to the same side. The corresponding clamping block is more prominent, and the damping pad has deformation force. After being squeezed, the surface in contact with the concrete specimen will swell, thereby increasing the fitting area with the concrete specimen, and further improving the friction damping force after the two are in contact and pressed tightly. When close to the concrete specimen, the direct contact of the damping pad can be used to buffer and consume the vibration force, which greatly weakens the vibration intensity of the specimen acting on the extension arm. Under the action of larger friction force, the possibility of extension arm displacement is further reduced, and the retraction of the two extension arms during the tensile strain measurement of high-toughness concrete is reduced as much as possible, or even avoided, thereby ensuring the accuracy of the strain measurement results.

[0016] The device adopts a specially designed clamping structure to achieve a firm multi-dimensional clamping and pre-tightening effect on the concrete specimen, and can prevent the extension arms from loosening and sliding back during the tensile test. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic structural diagram of a clamping device for measuring strain of high-toughness concrete provided by an embodiment of the present invention;

[0018] Figure 2 A partial structural schematic diagram of a clamping device for measuring strain of high-toughness concrete provided by an embodiment of the present invention;

[0019] Figure 3 A schematic diagram of the internal cross-sectional structure of an elastic pulling component of a clamping device for high-toughness concrete strain measurement provided by an embodiment of the present invention;

[0020] Figure 4 for Figure 1 A partial enlarged view of part A;

[0021] Figure 5A schematic structural diagram of a measuring rod in a clamping device for measuring strain of high-toughness concrete provided in an embodiment of the present invention.

[0022] Description of reference numerals:

[0023] 1. Loading plate; 2. Detection body; 3. Extension arm; 4. Elastic pulling assembly; 41. Sleeve; 42. Sliding rod; 43. Tension spring; 44. Hook; 5. Clamping block; 6. Damping pad; 7. Hanging ear; 71. Hanging hole; 8. Box body; 81. Concave cavity; 9. Abutment plate; 10. Sliding rod; 11. Compression spring; 12. Measuring rod; 121. Rod; 122. Telescopic rod. DETAILED DESCRIPTION

[0024] A specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific implementation.

[0025] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the technical solutions of the present invention and simplifying the description, and do 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 invention.

[0026] refer to Figure 1 and Figure 2 The present invention provides a clamping device for measuring strain of high-toughness concrete, comprising four extension arms 3 symmetrically and evenly distributed on the left and right sides of a concrete specimen, a fitting assembly connected to the end of each extension arm 3, and an elastic pulling assembly 4 for tightening two fittings at the same height. The two extension arms 3 on one side of the concrete specimen are respectively close to two size gradients of the concrete specimen. The fitting assembly comprises: a bearing plate 1, a clamping block 5, and a damping pad 6. The bearing plate 1 is fixedly connected to the end of each extension arm 3. The clamping block 5 is fixedly connected to a side wall of the bearing plate 1 close to the concrete specimen. When the clamping blocks 5 on the two bearing plates 1 at the same height move horizontally and continuously in a similar direction, the contact surface of the clamping blocks 5 presses against the concrete specimen. The damping pad 6 is made of soft material, fixedly connected to the bearing plate 1 and on the same side as the clamping block 5. The length of the damping pad 6 extending toward one side of the concrete specimen is longer than the length of the clamping block 5 extending toward one side of the bearing plate.

[0027] In the above embodiments, the supporting plate 1 is capable of realizing the connection between the clamping block 5 and the damping pad 6 and the extension arm 3, and a plurality of elastic pulling components 4 are used to realize high-strength clamping of the supporting plates 1 on both sides, thereby ensuring the stability of the clamping. At the same time, the damping pad 6 is capable of utilizing its reliable elastic deformation and reset ability to increase the prestressing force on the concrete specimen. At the same time, the setting of the damping pad 6 can enhance the friction damping force between the clamping block 5 and the concrete specimen. When the clamping block 5 is pressed against the concrete specimen, even if vibration occurs, the extension arm 3 is not easy to deviate and slide sideways under the action of the damping pad 6. By limiting the damping pad 6 to be more prominent than the corresponding clamping block 5 on the same side, the damping pad 6 has a deformation force, and after being squeezed, it is in contact with the concrete specimen. The contacting surface will swell, thereby increasing the contact area with the concrete specimen, further improving the friction damping force after the two are in contact and pressed tightly. When close to the concrete specimen, the direct contact of the damping pad 6 can also buffer and consume the vibration force, greatly weakening the vibration intensity of the specimen acting on the extension arm 3. Under the action of the larger friction force, the possibility of displacement of the extension arm 3 is further reduced, and the retraction of the two extension arms 3 during the tensile strain measurement of high-toughness concrete is reduced as much as possible or even avoided, thereby ensuring the accuracy of the strain measurement results. The device adopts a specially designed clamping structure to achieve a firm multi-dimensional clamping and pre-tightening effect on the concrete specimen, which can prevent each extension arm 3 from loosening and sliding and retracting during the tensile test.

[0028] Further, refer to Figure 1 , the distance between the two extension arms 3 on the same side is smaller than the distance between the two correspondingly connected supporting plates.

[0029] Further, refer to Figure 1 and Figure 4 , each bearing plate 1 is connected to a hanging ear 7 at the front and rear ends, and the hanging ear 7 is provided with a hanging hole 71 in the vertical direction. The elastic pulling component 4 includes: a sleeve 41, a slide bar 42, a tension spring 43, and two hooks 44. The sleeve 41 is horizontally arranged between the two hanging ears 7 at the same height, the slide bar 42 is slidably inserted in the sleeve 41, and the tension spring 43 is placed in the sleeve 41, one end of which is fixedly connected to the inner wall of the sleeve 41, and the other end is fixedly connected to the end of the slide bar 42, and the two hooks 44 are respectively fixedly connected to the ends of the sleeve 41 and the slide bar 42 that are far away from each other, and the two hooks 44 are respectively hooked in the hanging holes 71 of the two hanging ears 7 at the same height.

[0030] In the above embodiment, the hook 44 provided therein can pass through the hook ear 7. When there is no stretching action, the stretch spring 43 is in a retracted state. The tensioning force of the stretch spring 43 can be used to achieve the relative sliding of the sleeve 41 and the slide rod 42, thereby achieving the effect of pre-tightening and clamping the concrete specimen.

[0031] Further, references 1 and Figure 4 Considering that the dumbbell-shaped concrete specimen may need to be subjected to thickness increase strain measurement during the test, two box bodies 8 are fixedly connected to the side of the load-bearing plate 1 away from the connecting extension arm 3. The box body 8 is provided with a concave cavity 81, and a vertical abutment plate 9 is slidably connected in the concave cavity 81. A sliding rod 10 is fixedly connected to the middle part of one end surface of the abutment plate 9 close to the adjacent hanging ear 7. The sliding rod 10 is sleeved with a compression spring 11. The sliding rod 10 is slidably connected to the box body 8, and the hanging ear 7 is fixedly connected to the end of the sliding rod 10 passing through the box body 8.

[0032] In the above embodiment, the distance between the two hanging ears 7 can be adaptively stretched and extended relatively, so as to be suitable for thicker test pieces.

[0033] Further, refer to Figure 4 The material of the clamping block 5 is metal steel, and the side of the clamping block 5 in contact with the concrete specimen is sharpened. The damping pad 6 is filled in the missing inclined surface of the clamping block 5 after being squeezed and deformed by the concrete specimen.

[0034] In the above embodiments, the clamping block 5 is sharpened to increase the pressure exerted by the edge of the clamping block 5 on the surface of the concrete specimen, and the clamping stability of the concrete specimen is improved based on the full contact between the damping pad 6 and the concrete specimen.

[0035] Further, refer to Figure 2 The damping pad 6 is in strip shape and its length extending horizontally in the front-to-back direction is greater than the thickness of the concrete specimen.

[0036] In the above embodiments, the bonding area between the side wall of the concrete specimen can be guaranteed.

[0037] Further, refer to Figure 1 The material of the tension spring 43 is chromium-molybdenum alloy steel.

[0038] In the above embodiments, the material of the tension spring 43 is limited to chromium-molybdenum alloy steel, which has the characteristics of high strength, high hardness, high toughness, high fatigue limit, good wear resistance, etc. At the same time, it has good long-lasting elasticity and will not undergo plastic deformation during use. When in a tensioned state, the tensioning stability of the two bearing plates 1 is stronger, which can greatly reduce the stability effect caused by the vibration of the concrete specimen, so as to ensure that the clamping force of each bearing plate 1, the clamping block 5 and the damping pad 6 on the concrete specimen is always stable.

[0039] Further, refer to Figure 4 The material of the damping pad 6 is silicone rubber.

[0040] In the above embodiments, the material of the damping pad 6 is limited to silicone rubber because the material has strong and reliable elastic deformation and reset ability, and can be deformed after being extruded to increase the prestress on the concrete specimen. At the same time, the silicone rubber material has strong friction resistance and can be pressed against the concrete specimen. After the specimen vibrates, the damping pad 6 is not easy to deviate and slide sideways. At the same time, the direct contact of the damping pad 6 can also buffer and consume the vibration force, which greatly weakens the vibration intensity of the specimen acting on the extension arm 3. Under the action of the larger friction force, the possibility of displacement of the extension arm 3 is further reduced, and the retraction of the two extension arms 3 during the tensile strain measurement of high-toughness concrete is reduced as much as possible or even avoided, thereby ensuring the accuracy of the strain measurement results.

[0041] Further, refer to Figure 2 Each extension arm 3 is provided with a plurality of through holes along the thickness direction near the corresponding supporting plate 1, and a mounting hole is provided on the side of the supporting plate 1 that is in contact with the extension arm 3 and at the position corresponding to the through hole, and the extension arm 3 is connected to the supporting plate 1 by bolts.

[0042] In the above embodiments, the connection is performed by bolts, which can facilitate disassembly and assembly before and after the test, and also facilitate the replacement and maintenance of various parts.

[0043] Further, refer to Figure 2 and Figure 5 , each extension arm 3 is provided with a through hole on one side adjacent to the bearing plate 1 along the thickness extension direction thereof, that is, vertically, and the through holes of the two extension arms 3 on the left and the two extension arms 3 on the right are respectively penetrated with a vertically extending measuring rod 12, the measuring rod 12 comprises upper and lower rods 121 and a telescopic rod 122 in the middle, the diameter of the rod 121 is smaller than the size of the through hole, the cylinder and the rod size of the telescopic rod 122 are larger than the size of the through hole, the telescopic length of the telescopic rod 122 can be adjusted and locked, and the cylinder part is provided with a scale line, which is convenient for accurately controlling the telescopic length, and the measuring rod 12 provided in this embodiment can complete direct adjustment when determining the initial spacing between the two extension arms 3, specifically, when the initial spacing between the two extension arms 3 of the extensometer needs to be 10 cm, the initial spacing value of the extension arms 3 can be set efficiently and accurately by rotating and adjusting the length of the telescopic rod 122 to 10 cm, avoiding the traditional frequent use of a vernier caliper or a steel ruler for measurement and determination when setting the clamping range, reducing the measurement error, and ensuring the accuracy of the test results.

[0044] The above disclosures are only several specific embodiments of the present invention. However, the embodiments of the present invention are not limited thereto. Any changes that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A clamping device for measuring strain of high-toughness concrete, characterized in that: The invention comprises four extension arms (3) symmetrically and evenly distributed on the left and right sides of a concrete specimen, a fitting assembly connected to the ends of each extension arm (3), and an elastic pulling assembly (4) for tightening two fittings at the same height. The two extension arms (3) on one side of the concrete specimen are respectively close to two size gradients of the concrete specimen. The fitting assembly comprises: A bearing plate (1) is fixedly connected to the end of each extension arm (3); A clamping block (5) is fixedly connected to a side wall of the bearing plate (1) close to the concrete specimen, and when the clamping blocks (5) on two bearing plates (1) at the same height move horizontally and continuously in similar directions, the contact surface of the clamping block (5) is pressed against the concrete specimen; The damping pad (6) is made of a soft material and is fixedly connected to the bearing plate (1) and on the same side as the clamping block (5). The length of the damping pad (6) extending toward the concrete specimen is longer than the length of the clamping block (5) extending toward the bearing plate.

2. A clamping device for high-toughness concrete strain measurement as claimed in claim 1, characterized in that: The distance between the two extension arms (3) on the same side is smaller than the distance between the two correspondingly connected supporting plates (1).

3. A clamping device for high-toughness concrete strain measurement as claimed in claim 1 or 2, characterized in that: Each of the supporting plates (1) is connected to a hanging ear (7) at the front and rear ends, and the hanging ear (7) is provided with a hanging hole (71) in the vertical direction. The left and right hanging ears (7) are connected by an elastic pulling assembly, and the elastic pulling assembly (4) comprises: A sleeve (41) is horizontally arranged between two hanging ears (7) at the same height; A sliding rod (42) is slidably inserted into the sleeve (41); A tension spring (43) is placed in the sleeve (41), one end of which is fixedly connected to the inner wall of the sleeve (41) and the other end of which is fixedly connected to the end of the slide rod (42). Two hooks (44) are respectively fixedly connected to the ends of the sleeve (41) and the slide rod (42) which are far away from each other. The two hooks (44) are respectively hooked in the hanging holes (71) of two hanging ears (7) at the same height.

4. A clamping device for high-toughness concrete strain measurement as claimed in claim 3, characterized in that: The side of the carrier plate (1) away from the connecting extension arm (3) is fixedly connected to two box bodies (8), the box body (8) is provided with a concave cavity (81), a vertical abutment plate (9) is slidably connected in the concave cavity (81), a sliding rod (10) is fixedly connected to the middle part of an end surface of the abutment plate (9) close to the adjacent hanging ear (7), the sliding rod (10) is sleeved with a compression spring (11), the sliding rod (10) is slidably connected to the box body (8), and the hanging ear (7) is fixedly connected to the end of the sliding rod (10) passing through the box body (8).

5. A clamping device for high-toughness concrete strain measurement as claimed in claim 2, characterized in that: The material of the clamping block (5) is metal steel, and the side of the clamping block (5) in contact with the concrete specimen is sharpened, and the damping pad (6) is filled in the missing inclined surface of the clamping block (5) after being squeezed and deformed with the concrete specimen.

6. A clamping device for high-toughness concrete strain measurement as claimed in claim 5, characterized in that: The damping pad (6) is in the shape of a strip and has a length extending horizontally in the front-to-back direction that is greater than the thickness of the concrete test piece.

7. A clamping device for high-toughness concrete strain measurement as claimed in claim 3, characterized in that: The material of the tension spring (43) is chromium-molybdenum alloy steel.

8. A clamping device for high-toughness concrete strain measurement as claimed in claim 1, characterized in that: The material of the damping pad (6) is silicone rubber.

9. A clamping device for high-toughness concrete strain measurement as claimed in claim 1, characterized in that: Each of the extension arms (3) is provided with a plurality of through holes along the thickness direction of the corresponding support plate (1) at a position close to the corresponding support plate (1); a mounting hole is provided on a side of the support plate (1) that is in contact with the extension arm (3) and at a position corresponding to the through hole; and the extension arm (3) is connected to the support plate (1) by bolts.

Images