A double knife hinge support suitable for the compression test of I-shaped section test pieces

Abstract

The application is suitable for the technical field of building engineering test, and provides a double-knife hinge support suitable for the compression test of I-shaped section test pieces, which comprises a lower bottom plate, an intermediate bottom plate and an upper bottom plate arranged in sequence and stacked; the upper bottom plate is provided with bolt holes for fixing the head of a testing machine; the lower side surface of the upper bottom plate and the lower side surface of the intermediate bottom plate are provided with mutually orthogonal knife hinges; the upper side surface of the intermediate bottom plate and the upper side surface of the lower bottom plate are respectively provided with grooves matched with the knife hinges; the lower bottom plate is uniformly provided with four lower connecting steel sheets on the lower side surface, the intermediate of the lower connecting steel sheets is provided with a sliding groove, and the sliding groove is provided with a clamp. The position of the clamp in the sliding groove can be adjusted to adapt to test pieces with different section sizes and realize quantitative control of eccentricity; the orthogonal knife hinge structure ensures flexible rotation; the connecting ear part is hung with a steel rope to prevent the connecting plate from falling off. The application solves the problems of the existing support, such as difficult centering, difficult quantitative control of eccentricity, easy falling off of the connecting plate, etc., and has high precision, good controllability and wide application range.

Description

Technical Field

[0001] This invention belongs to the field of building engineering testing technology, and in particular relates to a double-knife hinge support suitable for compression testing of I-shaped cross-section specimens. Background Technology

[0002] Compression columns in building engineering have a wide variety of cross-sectional shapes, such as rectangular, circular, and irregular sections. These components are widely used in various projects, including high-rise buildings, stadiums, and bridges. During service, compression columns primarily experience two typical load modes: axial compression and eccentric compression. Axial compression and eccentric compression tests conducted on these two load modes are crucial techniques for studying their mechanical properties. Boundary support conditions are one of the key factors affecting the test results of the compression performance of components; therefore, the rational design of supports is of great significance for ensuring the accuracy of the tests.

[0003] Currently, commonly used support types in axial compression tests of columns include welded plate supports, ball joint supports, knife joint supports, and point joint supports. Traditional knife joint supports typically consist of upper and lower connecting plates and mating knife edges and grooves, forming a hinge mechanism through line contact between the knife edges and grooves to simulate ideal hinged boundary conditions. Ball joint supports, on the other hand, are formed by a precisely fitted arc-shaped groove on the top surface of the lower connecting plate and a spherical protrusion on the bottom surface of the upper connecting plate, creating a hinge mechanism that allows for omnidirectional rotation.

[0004] However, existing supports still have the following technical problems in practical applications: the relative position of the component and the support cannot be adjusted, and it is difficult to quantitatively control the eccentricity in the eccentric compression test, which makes it difficult to control the test accuracy; at the same time, due to the structural characteristics of the contact plates being separated from each other, there is a safety hazard of the connecting plate falling off during the test, which affects the reliability and safety of the test operation. Summary of the Invention

[0005] The purpose of this invention is to provide a double-knife hinge support suitable for compression tests on I-shaped cross-section specimens, aiming to solve the problems existing in the background art.

[0006] This invention is implemented as follows: a double-knife-hinge support suitable for compression testing of I-shaped cross-section specimens includes a lower base plate, an intermediate base plate, and an upper base plate stacked sequentially. The upper base plate has upper base plate fixing bolt holes for positioning the testing head. The lower sides of both the upper and intermediate base plates are provided with orthogonal knife-hinge joints. The upper and lower sides of the intermediate and lower base plates respectively have grooves that mate with the knife-hinge joints on the upper and lower base plates. Four lower connecting steel plates perpendicular to the lower base plate are evenly installed on the lower side of the lower base plate. A sliding groove is formed in the middle of each lower connecting steel plate, and a clamp is installed in the middle of the sliding groove.

[0007] Furthermore, upper connecting steel plates and middle connecting steel plates perpendicular to the upper base plate and the middle base plate are alternately arranged on the two side edges of the surface of the upper base plate and the middle base plate, and bolt holes are opened on both the upper connecting steel plates and the middle connecting steel plates.

[0008] Furthermore, the upper connecting steel plate and the middle connecting steel plate have two bolt holes at their upper ends and one bolt hole at their lower ends.

[0009] Furthermore, a pair of connecting ears are provided on both sides of the intersection of the upper base plate and the middle base plate, which are hung by steel ropes passing through the holes.

[0010] Furthermore, bolt holes are provided on the outer surfaces of the upper base plate, the middle base plate, and the lower base plate along both ends of the blade. The bolt holes between the upper base plate and the middle base plate, and between the middle base plate and the lower base plate, are flexibly connected by steel sheets.

[0011] Furthermore, the upper base plate, the middle base plate, and the lower base plate are all square.

[0012] The present invention provides a double-knife hinge support suitable for compression tests of I-shaped cross-section specimens, which has the following beneficial effects:

[0013] The double-knife hinge support provided by this invention features a sliding groove on the underside of the lower base plate for mounting clamps. This allows for flexible adjustment of the clamp position according to different cross-sectional specimens, enabling precise quantitative control of axial alignment or eccentricity. This effectively solves the problems of difficulty in aligning columns during axial compression tests and difficulty in quantitatively controlling eccentricity during eccentric compression tests. Simultaneously, the orthogonally arranged upper and lower knife hinge structure ensures flexible rotation of the support, avoiding the problem of high frictional resistance leading to rotational failure under high loads, a common issue with traditional ball hinge supports. Furthermore, the use of connecting lugs and perforated steel ropes for slinging prevents the connecting plate from detaching during testing, improving the safety and reliability of the test operation. This support has a wide range of applications, is easy to disassemble, and highly adjustable, overcoming the shortcomings of traditional welding or plaster casting fixing methods, such as low installation efficiency and difficult cleaning. Attached Figure Description

[0014] Figure 1 This is a three-dimensional structural view of an embodiment of the present invention;

[0015] Figure 2 This is a schematic diagram of the upper base plate structure in an embodiment of the present invention;

[0016] Figure 3 This is a schematic diagram of the intermediate base plate structure in an embodiment of the present invention;

[0017] Figure 4 This is a schematic diagram of the lower base plate structure in an embodiment of the present invention;

[0018] Figure 5This is a top view of a clamp applicable to cylindrical cross-section members.

[0019] In the attached diagram: 1. Connecting ear; 2. Upper connecting steel plate; 3. Middle connecting steel plate; 4. Component; 5. Upper base plate fixing bolt hole; 6. Upper base plate; 7. Knife hinge; 8. Middle base plate; 9. Groove; 10. Lower base plate; 11. Lower connecting steel plate; 12. Slide groove; 13. Clamp. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0021] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0022] like Figures 1 to 5 As shown, this embodiment provides a double-knife hinge support suitable for compression testing of I-shaped cross-section specimens, including a lower base plate 10, an intermediate base plate 8, and an upper base plate 6 stacked in sequence. The upper base plate 6, intermediate base plate 8, and lower base plate 10 are all square. The upper base plate 6 has upper base plate fixing bolt holes 5 for positioning the testing machine head; in use, the testing machine head is fixedly connected to the upper base plate 6 through these bolt holes.

[0023] Both the lower side of the upper base plate 6 and the lower side of the middle base plate 8 are provided with orthogonal blade hinges 7. Specifically, the blade hinges on the lower side of the upper base plate 6 and the blade hinges on the lower side of the middle base plate 8 are spatially perpendicular to each other. The upper side of the middle base plate 8 has a groove 9 that mates with the blade hinges on the lower side of the upper base plate 6, and the upper side of the lower base plate 10 has a groove 9 that mates with the blade hinges on the lower side of the middle base plate 8. The blade hinges 7 and the grooves 9 form a line contact hinge pair, allowing free rotation in a certain direction, and the two orthogonal blade hinge structures together achieve the function of omnidirectional rotation.

[0024] On the two side edges of the upper base plate 6 and the intermediate base plate 8, upper connecting steel plates 2 and intermediate connecting steel plates 3 are alternately arranged, perpendicular to the upper base plate 6 and the intermediate base plate 8, respectively. The upper connecting steel plate 2 connects the upper base plate 6 and the intermediate base plate 8, and the intermediate connecting steel plate 3 connects the intermediate base plate 8 and the lower base plate 10. Bolt holes are provided on both the upper connecting steel plate 2 and the intermediate connecting steel plate 3. Specifically, two bolt holes are provided at the upper end of the upper connecting steel plate 2 and the intermediate connecting steel plate 3, and one bolt hole is provided at the lower end.

[0025] During assembly, first tighten the two upper bolt holes, leaving some space in the lower bolt hole to allow for adjusting the base plates to be parallel. Once the upper base plate 6, middle base plate 8, and lower base plate 10 are parallel, tighten the lower bolt hole, then arrange the components to ensure overall stability. After the entire device is installed, slightly loosen the lower bolt hole to ensure the base plate can move freely during the test pressurization process, thus achieving the purpose of hinged connection at the upper end for the axial compression test.

[0026] Furthermore, bolt holes are provided on the outer surfaces of the upper base plate 6, the middle base plate 8, and the lower base plate 10 along both ends of the blade. Flexible connections are achieved between the bolt holes of the upper base plate 6 and the middle base plate 8, and between the bolt holes of the middle base plate 8 and the lower base plate 10, through steel sheets, thereby ensuring the safety and stability of the device.

[0027] Four lower connecting steel plates 11, perpendicular to the lower base plate 10, are evenly installed on the lower side of the lower base plate 10. The thickness and height of the four lower connecting steel plates 11 are all the same. A groove 12 is opened in the middle of each lower connecting steel plate 11. The groove 12 is an elongated through hole or groove. A clamp 13 is installed in the middle of the groove 12. One end of the clamp 13 extends into the groove 12, and the other end is set inward to support the side of the specimen.

[0028] The end of the clamp 13 is connected to the slide groove 12, and the clamp 13 is tightened and fixed by fixing bolts. By adjusting the installation position of the clamp 13 in the slide groove 12, the contact position between the inner end of the clamp 13 and the side of the specimen can be changed, thereby realizing quantitative control of the axial position or eccentricity of the specimen. The double-knife hinge support of this embodiment can use different fixing clamps according to the different cross-sections of the components (such as I-shaped cross-sections, circular cross-sections, rectangular cross-sections and other irregular cross-sections). The clamp replacement method is simple and easy to disassemble and assemble, making this support applicable to components of different sizes and cross-section types.

[0029] A pair of connecting lugs 1 are provided on both sides of the intersection of the upper base plate 6 and the middle base plate 8. During assembly, a steel rope is passed through the connecting lugs 1 and secured to prevent the base plate from accidentally falling due to insecure fixing during installation and testing, thereby improving the safety of the test operation.

[0030] Brief description of the operation process

[0031] In this embodiment, when using the double-knife hinge support, firstly, the upper base plate 6 is fixed to the head of the testing machine through the upper base plate fixing bolt holes 5; then, following the operating steps of the above flexible connection structure, the parallelism of each base plate is adjusted through the upper connecting steel plate 2, the middle connecting steel plate 3 and the corresponding bolt holes; then, the specimen is placed above the lower base plate 10, and the specimen is positioned at the axial center or a predetermined eccentricity by adjusting the extension length of the sliding groove 12 on the lower connecting steel plate 11 and the clamp 13; finally, the clamp 13 is locked, and the lower bolt holes are slightly loosened before the compression test can be performed.

[0032] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A double-knife hinge support suitable for compression tests on I-shaped cross-section specimens, characterized in that, The double-knife hinge support applicable to compression tests of I-shaped cross-section specimens includes: The lower base plate (10), the middle base plate (8) and the upper base plate (6) are stacked in sequence. The upper base plate (6) is provided with upper base plate fixing bolt holes (5) for positioning the test head. The lower side of the upper base plate (6) and the lower side of the middle base plate (8) are provided with orthogonal blade hinges (7), and the upper side of the middle base plate (8) and the upper side of the lower base plate (10) are respectively provided with grooves (9) that cooperate with the blade hinges on the upper and lower base plates. Four lower connecting steel plates (11) perpendicular to the lower base plate (10) are evenly installed on the lower side of the lower base plate (10). A sliding groove (12) is opened in the middle of the lower connecting steel plate (11), and a clamp (13) is installed in the middle of the sliding groove (12).

2. The double-knife hinge support for compression testing of I-shaped cross-section specimens according to claim 1, characterized in that, The upper base plate (6) and the middle base plate (8) are alternately provided with upper connecting steel plates (2) and middle connecting steel plates (3) perpendicular to the upper base plate and the middle base plate, respectively. Bolt holes are provided on both the upper connecting steel plates (2) and the middle connecting steel plates (3).

3. The double-knife hinge support for compression testing of I-shaped cross-section specimens according to claim 2, characterized in that, The upper connecting steel plate (2) and the middle connecting steel plate (3) have two bolt holes at their upper ends and one bolt hole at their lower ends.

4. The double-knife hinge support for compression testing of I-shaped cross-section specimens according to claim 1, characterized in that, A pair of connecting ears (1) are provided on both sides of the upper base plate (6) and the middle base plate (8) that are intersected, and are hung by steel rope through the holes.

5. The double-knife hinge support for compression testing of I-shaped cross-section specimens according to claim 1, characterized in that, Bolt holes are provided on the outer surfaces of the upper base plate (6), the middle base plate (8), and the lower base plate (10) along the two ends of the blade. The bolt holes of the upper base plate (6) and the middle base plate (8), and the bolt holes of the middle base plate (8) and the lower base plate (10) are flexibly connected by steel sheets.

6. The double-knife hinge support for compression testing of I-shaped cross-section specimens according to claim 1, characterized in that, The upper base plate (6), the middle base plate (8), and the lower base plate (10) are all square.

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