Assembled axis and eccentricity reciprocating tension-compression test device suitable for structural member
By designing an assembled axial and eccentric reciprocating tension-compression testing device, the problem that existing devices cannot perform reciprocating tension-compression tests on metal tubes or metal tube-concrete composite components is solved. This achieves reliable load transfer and test accuracy, is applicable to the application of arbitrary eccentric loads, and improves the operability of the test and the utilization rate of materials.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-14
- Publication Date
- 2026-03-31
AI Technical Summary
Existing testing equipment cannot perform reciprocating tension-compression tests on metal tubes or metal tube-concrete composite components, and has problems such as brittle failure of end connections, poor load transfer, and difficulty in adjusting eccentric loads, resulting in distorted test results.
An assembled axial and eccentric reciprocating tension-compression test device was designed, including a loading device connection part and a test component connection part. It adopts components such as a clamp, clamp plate, connecting plate, eccentricity adjustment shaft, and tension-compression rotating shaft. The assembly method realizes reliable load transmission and eccentricity adjustment, avoiding virtual displacement at the end.
It enables the application of reciprocating tension-compression loads on metal tubes or metal tube-concrete composite components, ensuring the reliability of load transfer and the accuracy of testing. It is applicable to the application of arbitrary eccentric loads, improving the operability of the test and the utilization rate of materials.
Smart Images
Figure CN224066544U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of building structure technology, and specifically relates to an assembled axial and eccentric reciprocating tension-compression test device suitable for structural components. Background Technology
[0002] Metal tube components and metal tube-concrete composite components are two widely used types of building structural components. Metal tubes mainly consist of weldable metal materials such as common structural steel pipes and stainless steel pipes. The internal concrete filling of metal tube-concrete composite structural components includes ordinary concrete, high-strength concrete, recycled concrete, and ultra-high-performance concrete. These structural components are widely used in industrial plants, stadiums, high-rise buildings, long-span bridges, and power transmission towers. When subjected to seismic or wind loads, metal tube or metal tube-concrete composite components are often under cyclic tension-compression stress. Cyclic tension-compression damage in structural components is a key reason for performance degradation and even failure, and it forms the basis for analyzing their failure mechanisms under coupled cyclic loading.
[0003] However, existing testing devices can often only perform monotonic compression or monotonic tension tests on metal tubes or metal tube-concrete composite members. In some existing tension-compression testing devices, the failure zone often appears at the end joint of the specimen during tension-compression tests, and the heat-affected zone of the end weld often fails before the specimen. When the specimen is a metal tube-concrete composite member, existing devices cannot fully ensure that the tension-compression load is effectively transferred to the core concrete, resulting in the metal tube being directly stressed and failing to form a combined effect with the core concrete. Furthermore, existing devices rely solely on bolt tension, which easily leads to stress concentration. The end plate is prone to bending deformation during tension-compression transition, resulting in excessive virtual displacement of the specimen and distorted test results. Therefore, it is impossible to study the reciprocating tension-compression mechanical properties of metal tube members and metal tube-concrete composite members.
[0004] Furthermore, when the specimen is subjected to eccentric loading, the eccentricity of the existing loading device is difficult to adjust or the adjustment accuracy is insufficient. Moreover, the welded area and bolted connection area at the end of the metal pipe are more prone to brittle failure under reciprocating tension-bending coupled loads. The hinged boundary conditions at the end of the specimen cannot guarantee that the specimen will rotate freely under bending moment, resulting in the test results not reflecting the true stress condition of the specimen. Utility Model Content
[0005] In view of this, this utility model aims to solve the problem that existing test devices can only achieve monotonous compression or monotonous tension conditions and cannot perform reciprocating tension-compression tests; and that existing tension-compression test devices often suffer brittle failure at the end connection, and the tension of the end clamps and bolts is difficult to ensure the effective transmission and smooth conversion of tension-compression loads in metal tube-concrete composite structures; when there is an eccentric load, existing loading devices cannot apply arbitrary eccentric loads, and the rotation capacity of the ends cannot be fully guaranteed, resulting in virtual displacement during loading, which leads to insufficient reliability of the reciprocating tension-compression test results of metal tubes or metal tube-concrete composite components.
[0006] To solve the above problems, the present invention adopts the following technical solution: an assembled axial and eccentric reciprocating tension-compression test device and test method suitable for structural components, including a loading device connection part, a test component connection part, and a test component, wherein the loading device connection part and the test component connection part are connected, and the test component connection part is connected to the test component;
[0007] The loading device connection part includes a chuck end, a chuck plate and a chuck cover plate. The chuck end is located below the chuck plate, and the chuck cover plate fixes the chuck end and the chuck plate together.
[0008] The connecting part of the test component includes a connecting plate, an eccentricity adjustment shaft, a tension-compression rotating shaft, and a connecting base plate. The connecting plate is vertically mounted on the connecting base plate. The connecting plate is provided with a axial loading fixing hole II. The connecting plate is provided with a sliding groove. The tension-compression rotating shaft is installed in the sliding groove. The eccentricity adjustment shaft passes through the sliding groove and also passes through the tension-compression rotating shaft. The tension-compression rotating shaft is a cubic steel block with round steel columns welded to both ends, and a hole drilled in the middle for wire feeding. The wire feeding parameters are consistent with those of the eccentricity adjustment shaft.
[0009] Furthermore, the chuck end is provided with an axial loading fixing hole I, and the connecting plate of the test component connection part is provided with an axial loading fixing hole II. When axial loading is required, pins can be inserted into the axial loading fixing holes I and II to fix the load and ensure that the load is applied axially.
[0010] Furthermore, the tensile-compressive load is applied by the MTS testing machine, which is equipped with clamps. The clamp end 1-1 is inserted into the clamp and clamped, and the load is applied by the friction between the clamp and the clamp end.
[0011] Furthermore, the connection parts of the loading equipment and the connection parts of the test components need to be assembled before the test. During assembly, the tension-compression shaft is placed into the corresponding groove position of the connecting plate, and then the eccentricity adjustment shaft is inserted. After adjusting and determining the required eccentricity, the nut on the outside of the eccentricity adjustment shaft is tightened, and the position of the tension-compression shaft is fixed.
[0012] Furthermore, the connecting part of the test component also includes a central bolt. The connecting base plate is connected to the test component through the central bolt. The central bolt includes a straight thread, a nut, and several shear keys. A nut is installed at one end of the central bolt, and several shear keys are welded to the outer periphery of the central bolt.
[0013] Furthermore, the test component includes two end plates, an outer metal tube, and a core concrete. The upper and lower ends of the outer metal tube are connected to the end plates, and a hole is drilled in the center of the end plate for wire routing. The outer metal tube is filled with core concrete.
[0014] Furthermore, the end plate has an arc-shaped groove with a beveled edge. The corresponding position of the end of the outer metal tube is cut into an arc shape, and the outer metal tube is plug-welded after being inserted into the end plate.
[0015] Furthermore, the test component needs to be processed and assembled before the experiment. The central bolt can be screwed out from the side of the component to the outside. The upper part of the straight screw passes through the center hole of the end plate and is screwed out to the corresponding length according to the design. Then, one end plate is plug-welded to the outer metal tube. When there is core concrete inside the tube, the concrete is poured. Before the concrete solidifies, the other end plate is installed. Similarly, the straight screw needs to be screwed in in advance. After the core concrete is cured, plug welding is performed. When the component is only a metal tube, the shear key does not need to be welded to the lower part of the straight screw. The two end plates and the outer metal tube can be plug-welded at the same time. After the two end plates and the outer metal tube are plug-welded, the metal tube stiffening ribs can be welded. The welding position is on the part of the outer metal tube that is not plug-welded.
[0016] Furthermore, after the test component is processed and assembled, the upper part of the straight screw extending from the end plate passes through the center hole of the connecting base plate and is connected and fastened to the connecting base plate with the corresponding nut. Then, a U-shaped pad is inserted and a limit bolt is screwed in to prevent the U-shaped pad from slipping out during loading. The corner bolts pass through the corner bolt holes of the connecting base plate and the component end plate respectively and are tightened to complete the assembly of the overall device.
[0017] Compared with the prior art, the beneficial effects of the assembled axial and eccentric reciprocating tension-compression testing device and method for structural components described in this utility model are:
[0018] 1. This utility model enables the application of tensile-compressive cyclic loads to structural components with reliable end connections, while reducing the generation of virtual displacements during load application, further improving the operability and accuracy of the test. The designed test component connection connects the loading device and the test component, effectively transferring the tensile-compressive load applied by the loading device to achieve tensile-compressive cyclic loading of the structural component; the outer metal tube, after being cut according to the design, extends into the arc-shaped groove bevel of the end plate and is plug-welded, while stiffening ribs are used to ensure reliable connection between the specimen and the end plate, avoiding the problem of brittle failure that easily occurs in the heat-affected zone of traditional fillet welds; the lower part of the central bolt is threaded to the end plate of the test component, and the upper part of the central bolt is bolted to the connecting base plate, effectively preventing the problem of the connecting base plate and the center of the test component end plate becoming detached when tensile-compressive loads are applied.
[0019] 2. This utility model achieves effective transfer of tensile and compressive loads in a metal tube-concrete composite structural member. The central bolt and the four corner bolts work together to ensure a tight fit between the connecting base plate and the end plate of the test member. Under compressive loads, the end plate of the test member transmits uniformly distributed pressure, at which point the outer metal tube and the core concrete share the load. Under tensile loads, the end plate of the test member directly transfers the tensile force to the outer metal tube. The central bolt, pre-embedded in the core concrete, has a shear key welded to its lower part, transferring the tensile force to the core concrete. This allows the outer metal tube and the core concrete to share the tensile force, ensuring effective transfer of tensile and compressive loads. (A brief description of the tension-compression conversion effect follows.)
[0020] 3. This utility model can ensure the rotational capacity of the test component end, realizing the application of arbitrary eccentric loads. By adjusting the position of the tension-compression shaft through the eccentricity adjustment shaft, tension-compression loads with arbitrary eccentricity can be applied to the test component. In addition, the connection part between the loading device and the test component can be locally designed according to research needs and the size of the test component to meet special eccentricity requirements.
[0021] 4. This utility model adopts a modular mechanical connection, making the assembly and operation of the test device convenient and enabling rapid installation of test components. If any component is damaged, it can be quickly replaced, improving the utilization rate of structural materials and reducing additional workload during the test. Furthermore, this utility model has a wide range of applications and can be used to study the reciprocating tensile-compression mechanical properties of metal pipe components and metal pipe-concrete composite components. Attached Figure Description
[0022] The accompanying drawings, which form part of this utility model, are used to provide a further understanding of the utility model. The illustrative embodiments of the utility model and their descriptions are used to explain the utility model and do not constitute an undue limitation of the utility model. In the drawings:
[0023] Figure 1This is a schematic diagram of an assembled axial and eccentric reciprocating tension-compression test device suitable for structural components in an embodiment of this utility model;
[0024] Figure 2 This is a schematic diagram of the loading device connection portion in an embodiment of this utility model;
[0025] Figure 3 This is a schematic diagram of the connection portion of the test component in an embodiment of this utility model;
[0026] Figure 4 This is a schematic diagram of the eccentricity adjustment part in an embodiment of this utility model;
[0027] Figure 5 This is a schematic diagram of the U-shaped pad in an embodiment of the present utility model;
[0028] Figure 6 This is a schematic diagram of the connection between the metal pipe and concrete composite components in an embodiment of this utility model;
[0029] Figure 7 This is a schematic diagram of the connection of the metal pipe components in an embodiment of this utility model;
[0030] Figure 8 This is a schematic diagram of the central bolt in an embodiment of this utility model;
[0031] Explanation of reference numerals in the attached figures:
[0032] Loading device connection part 1, chuck end 1-1, chuck plate 1-2, chuck cover plate 1-3, chuck bolt 1-4, shaft loading fixing hole I 1-5;
[0033] Test component connection part 2, connecting plate 2-1, eccentricity adjustment shaft 2-2, tension-compression rotating shaft 2-3, shaft loading fixing hole II 2-4, stiffening rib 2-5, connecting base plate 2-6, center bolt 2-7, corner bolt 2-8, straight screw 2-71, nut 2-72, shear key 2-73, U-shaped pad 2-9, limit bolt 2-91;
[0034] Test component 3, end plate 3-1, outer metal tube 3-2, core concrete 3-3, metal tube stiffening rib 3-4. Detailed Implementation
[0035] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present utility model can be combined with each other, and the described embodiments are only some embodiments of the present utility model, not all embodiments.
[0036] See Figure 1-8This embodiment describes an assembled axial and eccentric reciprocating tension-compression testing device suitable for structural components, comprising a loading device connection part 1, a test component connection part 2, and a test component 3, wherein the loading device connection part 1, the test component connection part 2, and the test component 3 are connected sequentially.
[0037] Combination Figure 2 As shown, the loading device connection part 1 includes a chuck end 1-1, a chuck plate 1-2, a chuck cover plate 1-3, chuck bolts 1-4, and a central loading fixing hole I 1-5. These components can be fabricated by cutting and welding steel plates. The chuck end 1-1 includes a cubic portion and a U-shaped portion. A hole is drilled in the central loading fixing hole I 1-5 on the chuck end 1-1, and four holes are drilled at corresponding positions for threading on the four chuck bolts 1-4. Threading is also done on the four chuck bolts 1-4 on the chuck plate 1-2, and holes are drilled at corresponding positions for the four chuck bolts 1-4 on the chuck cover plate 1-3. Tensile and compressive loads are applied by an MTS (electro-hydraulic servo loading test system) testing machine. The MTS testing machine is equipped with clamps. The upper cubic portion of the chuck end 1-1 is inserted into the clamps and clamped, and the load is applied using the friction between the clamps and the chuck end.
[0038] Combination Figures 3 to 5 As shown, the connecting part 2 of the test component includes a connecting plate 2-1, an eccentricity adjustment shaft 2-2, a tension-compression rotating shaft 2-3, a axial loading fixing hole II 2-4, a stiffening rib 2-5, a connecting base plate 2-6, a center bolt 2-7, a corner bolt 2-8, a U-shaped pad 2-9, and a limiting bolt 2-91. The connecting plate 2-1, the stiffening rib 2-5, and the connecting base plate 2-6 can be fabricated by cutting and welding steel plates, with holes drilled at corresponding positions. The eccentricity adjustment shaft 2-2 is a long bolt, and the tension-compression rotating shaft 2-3 is a cubic steel block with round steel columns welded to both ends, with a central hole for threading. The threading parameters are the same as those of the eccentricity adjustment shaft 2-2, and the eccentricity adjustment shaft 2-2 can be screwed into and pass through the tension-compression rotating shaft 2-3. U-shaped pad 2-9 is machined from a cubic steel block. Its height is the same as the rectangular space reserved at the bottom of the connecting plate 2-1, and its width is slightly narrower. Holes are drilled and threaded at the corresponding positions on the side, and limit bolts 2-91 can be screwed in.
[0039] The connecting base plate 2-6 is connected to the test component 3 by a central bolt 2-7 and corner bolts 2-8. The central bolt 2-7 includes a straight threaded rod 2-71, a nut 2-72 and several shear keys 2-73. A nut 2-72 is installed at one end of the central bolt 2-7, and several shear keys 2-73 are welded to the outer periphery of the central bolt 2-7.
[0040] Combination Figures 1 to 5As shown, the loading device connection part 1 and the test component connection part 2 need to be assembled before the test. During assembly, the tension-compression shaft 2-3 is inserted into the corresponding groove position of the connecting plate 2-1, and then the eccentricity adjustment shaft 2-2 is inserted. After adjusting and determining the required eccentricity, the nut on the other side of the eccentricity adjustment shaft 2-2 is tightened, and the position of the tension-compression shaft 2-3 is fixed. The U-shaped part of the chuck end 1-1 is inserted into the connecting plate 2-1. The semi-circular groove of the U-shaped part of the chuck end 1-1 and the semi-circular groove of the chuck plate 1-2 surround the two cylindrical parts of the tension-compression shaft 2-3. The chuck end 1-1 and the chuck plate 1-2 are connected by the chuck cover plate 1-3 and the chuck bolts 1-4.
[0041] Combination Figures 6 to 8 As shown, the test component 3 includes an end plate 3-1, an outer metal tube 3-2, and a core concrete 3-3. The upper and lower ends of the outer metal tube 3-2 are connected to the end plate 3-1, respectively. A hole is drilled in the center of the end plate 3-1 for threading, and the outer metal tube 3-2 is filled with the core concrete 3-3. An arc-shaped groove is cut into the end plate 3-1, and the edges of the groove are beveled. An arc-shaped section is cut at the corresponding position at the end of the outer metal tube 3-2. The outer metal tube 3-2 is inserted into the connecting end plate 3-1 and connected by plug welding.
[0042] Combination Figure 6 , Figure 7 As shown, component 3 of the test assembly needs to be processed and assembled before the experiment. The central bolt 2-7 can be screwed out from the side of the component to the outside. The upper part of the straight screw 2-71 passes through the central hole of the end plate 3-1 and is screwed out to the corresponding length according to the design. Then, one end plate 3-1 is plug-welded to the outer metal tube 3-2. When there is core concrete 3-3 inside the tube, the concrete is poured. Before the concrete solidifies, the other end plate 3-1 is installed. Similarly, the straight screw 2-71 needs to be screwed in in advance. After the core concrete 3-3 has cured, plug welding is performed. When the component is only a metal tube, the shear key 2-73 does not need to be welded to the lower part of the straight screw 2-71, and the length of the straight screw 2-71 can be reduced accordingly. The two end plates 3-1 and the outer metal tube 3-2 can be plug-welded at the same time. After the two end plates 3-1 and the outer metal tube 3-2 are plug-welded, the metal tube stiffening rib 3-4 can be welded. The welding position is on the part of the outer metal tube 3-2 that has not been plug-welded.
[0043] Combination Figures 1 to 8 As shown, after the test component 3 is processed and assembled, the upper part of the straight screw 2-71 extending from the end plate 3-1 passes through the center hole of the connecting base plate 2-6 and is then connected and tightened to the connecting base plate 2-6 using the corresponding nut 2-73. Subsequently, the U-shaped pad 2-9 is inserted and the limiting bolt 2-91 is screwed in to prevent the U-shaped pad from slipping out during loading. The corner bolts 2-8 are then passed through the corner bolt holes of the connecting base plate 2-6 and the component end plate 3-1 and tightened, completing the assembly of the overall device.
[0044] Furthermore, all components in the test device are cut and welded from steel plates. It is recommended that the loading device connection part 1 and the test component connection part 2 be made of metal materials with higher strength and stiffness than the test component part 3.
[0045] Furthermore, the cubic part of the chuck end 1-1 can use different cross-sectional shapes such as circular, square, or rhomboid, depending on the loading device fixture.
[0046] Furthermore, the dimensions of the connection part 2 of the test component can be designed according to the test requirements, thereby achieving large eccentricity loading.
[0047] Furthermore, the outer metal pipe 3-2 can be made of different materials such as steel pipe or stainless steel pipe, and the core concrete 3-3 can be made of different types of ordinary concrete, high-strength concrete, recycled concrete, self-compacting concrete, etc.
[0048] Furthermore, when axial loading is required, pins can be inserted into the axial loading fixing holes I1-5 and II2-4 to ensure that the load is applied axially.
[0049] Furthermore, it is recommended that bolts and screws be made of high-strength materials to ensure the connection strength of the loading device.
[0050] Furthermore, the U-shaped pad 2-9 is closely fitted with the connecting plate 2-1 and the center bolt 2-7 to ensure axial force transmission and improve the rigidity of the device.
[0051] Combination Figures 1 to 6 As shown, this utility model provides an assembled reciprocating tension-compression test method suitable for structural components, including the following steps:
[0052] S1. Assembly Process: Design corresponding components according to experimental requirements. Connect the end plate 3-1 of the test component to the connecting base plate 2-6 using center bolts 2-7 and corner bolts 2-8. Then, connect the loading device connecting part 1 to the test component connecting part 2. Insert the clamp end 1-1 into the MTS fixture and clamp it to complete the connection between the test device and the loading device. Install strain monitoring equipment and displacement monitoring equipment as needed for the experiment.
[0053] S2. During the testing process, the MTS load application device is used to apply axial or eccentric loads to the test component. The load can be any or a combination of monotonic tensile load, monotonic compressive load, cyclic tensile load, cyclic compressive load, or cyclic tensile-compressive load. The magnitude of the applied axial force and the deformation of the test component can be collected by the corresponding device.
[0054] The embodiments of this utility model disclosed above are merely illustrative of the present utility model. The embodiments do not exhaustively describe all details, nor do they limit the utility model to the specific implementation methods described. Many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of this utility model, thereby enabling those skilled in the art to better understand and utilize it.
Claims
1. A test method applied to an assembled axial and eccentric reciprocating tensile-compressive test device for structural members, characterized by: The loading device connecting part (1) and the test component connecting part (2) are connected, and the test component connecting part (2) is connected with a test component part (3); The loading device connecting part (1) includes a chuck end (1-1), a chuck plate (1-2) and a chuck cover plate (1-3), the chuck end (1-1) is below the chuck plate (1-2), and the chuck cover plate (1-3) is fixedly connected with the chuck end (1-1) and the chuck plate (1-2), The test component connecting part (2) includes a connecting plate (2-1), an eccentricity adjusting shaft (2-2), a tension-compression shaft (2-3) and a connecting bottom plate (2-6), the connecting bottom plate (2-6) is vertically provided with the connecting plate (2-1), the connecting plate (2-1) is provided with a shaft center loading fixing hole II (2-4), the connecting plate (2-1) is provided with a sliding groove, the sliding groove is provided with the tension-compression shaft (2-3), and the eccentricity adjusting shaft (2-2) penetrates through the sliding groove and the tension-compression shaft (2-3).
2. The assembled axial and eccentrically off-center reciprocating tensile-compressive test apparatus suitable for structural members according to claim 1, characterized in that: The chuck end (1-1) is provided with a shaft center loading fixing hole I (1-5), the connecting plate (2-1) of the test component connecting part (2) is provided with a shaft center loading fixing hole II (2-4), and when shaft center loading is required, a pin can be inserted into the shaft center loading fixing hole I (1-5) and the shaft center loading fixing hole II (2-4) for fixation, so that the load is applied in the axial direction.
3. The assembled axial and eccentrically off-center reciprocating tensile-compressive test apparatus suitable for structural members according to claim 1, characterized in that: The tension-compression load is applied by an MTS testing machine, the MTS testing machine is provided with a clamp, the chuck end (1-1) is clamped after being inserted into the clamp, and the load is applied by using the friction force between the clamp and the chuck end.
4. The assembled axial and eccentrically off-center reciprocating tensile-compressive test apparatus suitable for structural members according to claim 1, characterized in that: The loading device connecting part (1) and the test component connecting part (2) need to be assembled before testing, during the assembly, the tension-compression shaft (2-3) is placed into the corresponding sliding groove of the connecting plate (2-1), then the eccentricity adjusting shaft (2-2) is penetrated, after the required eccentricity is adjusted and determined, the nut outside the eccentricity adjusting shaft (2-2) is tightened, and the position of the tension-compression shaft (2-3) is fixed.
5. The assembled axial and eccentrically off-center reciprocating tensile-compressive test apparatus suitable for structural members according to claim 1, characterized in that: The test component connecting part (2) further includes a center bolt (2-7), the connecting bottom plate (2-6) is connected with the test component part (3) through the center bolt (2-7), the center bolt (2-7) includes a straight screw rod (2-71), a nut (2-72) and a plurality of shear keys (2-73), one end of the center bolt (2-7) is provided with the nut (2-72), and a plurality of shear keys (2-73) are welded on the outer periphery of the center bolt (2-7).
6. The assembled axial and eccentrically off-center reciprocating tensile-compressive test apparatus suitable for structural members according to claim 5, characterized in that: The test component part (3) includes two end plates (3-1), an outer metal pipe (3-2) and core concrete (3-3), the outer metal pipe (3-2) is connected with the end plates (3-1) at the upper and lower ends, respectively, the end plates (3-1) are drilled at the centers, and the outer metal pipe (3-2) is filled with the core concrete (3-3).
7. The assembled axial and eccentrically off-center reciprocating tensile-compressive test apparatus suitable for structural members according to claim 6, characterized in that: The end plate (3-1) is opened with an arc-shaped slot, and the edge part of the slot is processed with a bevel. The outer metal tube (3-2) is cut at the corresponding position of the end plate (3-1) to form an arc-shaped part. After the outer metal tube (3-2) is inserted into the end plate (3-1), the plug welding connection is adopted.
8. The assembled axial and eccentrically off-center reciprocating tensile-compressive test apparatus suitable for structural members according to claim 7, characterized in that: The test component part (3) needs to be machined and assembled before the experiment. The center bolt (2-7) can be rotated out from the side of the component to the outside. The upper part of the straight screw rod (2-71) passes through the center hole of the end plate (3-1). According to the design, the corresponding length is rotated out. Then, one side of the end plate (3-1) is plug welded with the outer metal tube (3-2). When the core concrete (3-3) exists in the tube, the concrete pouring is carried out. Before the concrete solidifies, the other side of the end plate (3-1) is installed. In the same way, the straight screw rod (2-71) needs to be rotated in advance. After the core concrete (3-3) is cured, the plug welding is carried out. When the component is only a metal tube, the lower part of the straight screw rod (2-71) can not be welded with the shear key (2-73). The two sides of the end plate (3-1) and the outer metal tube (3-2) can be plug welded at the same time. After the plug welding of the two sides of the end plate (3-1) and the outer metal tube (3-2) is completed, the metal tube stiffening rib 3-4 can be welded. The welding position is in the part of the outer metal tube (3-2) which is not plug welded.
9. The assembled axial and eccentrically off-center cyclic biaxial tensile-compressive test apparatus suitable for structural members according to claim 8, characterized in that: After the test component part (3) is machined and assembled, the upper part of the straight screw rod (2-71) of the end plate (3-1) passes through the center hole of the connecting bottom plate (2-6) and is connected and fastened with the corresponding nut (2-72) and the connecting bottom plate (2-6). Then, the U-shaped pad block (2-9) is embedded and the limiting bolt (2-91) is rotated in. The U-shaped pad block (2-9) is prevented from slipping out during loading. The corner bolt (2-8) passes through the corner bolt hole of the connecting bottom plate (2-6) and the component end plate (3-1) respectively and is tightened. The overall device assembly is completed.