Adjustable loading device for anti-seismic test of large test piece

Abstract

The utility model relates to the technical field of civil engineering tests, and discloses an adjustable loading device for an anti-seismic test of a large test piece, which comprises a counter-force system, a rotatable force transfer system and a loading system, the counter-force system comprises a base and a cross beam, and the cross beam is located above the base; the rotatable force transmission system comprises a rigid pull rod and connecting pieces, the connecting pieces are arranged at the two ends of the rigid pull rod, and the connecting pieces at the two ends are rotationally connected with the base and the cross beam respectively; during working, a test piece is located between the base and the cross beam; the loading system comprises a jack and a horizontal actuator, the jack is arranged on the cross beam, the output end of the jack can be in contact with the test piece to apply a vertical load to the test piece, and the horizontal actuator is used for applying a horizontal load to the test piece. The device can solve the problems that a rigid member can prevent the top of the test piece from applying a horizontal low-cycle repeated load to influence the lateral stiffness of the test piece, and the axial load action line deviates from the central axis of the test piece after the top of the test piece generates certain displacement.

Description

Technical Field

[0001] The utility model belongs to the technical field of civil engineering structure test, and specifically relates to an adjustable loading device for large-scale test piece anti-seismic test, which can be suitable for quasi-static test (low-cycle repeated load test). Background Art

[0002] In civil engineering, the study of the seismic performance of components such as columns and nodes usually involves low-cycle repeated load tests. In low-cycle repeated load tests, the axial pressure on the specimen will greatly affect the lateral stiffness of the specimen. Therefore, studying the seismic performance of the specimen under different axial pressures is an important topic, which requires a set of test devices that can perform axial and horizontal loading at the same time. This test device should not only be able to apply axial and horizontal loads to the specimen at the same time, but also ensure that the loading devices in the two directions are independent of each other and do not affect each other.

[0003] Based on the above requirements, the existing methods of simultaneous axial and horizontal loading have certain limitations. First, the horizontal load will cause a large horizontal displacement at the top of the column, which will in turn cause the central axis of the column to deflect. At this time, the axial loading line of action is difficult to coincide with the axis, which affects the axial load. Secondly, when loading horizontally, the top of the column often drives the axial loading device to produce horizontal displacement together. If the axial loading device itself has a certain lateral stiffness, it will affect the lateral stiffness of the column and greatly affect the test results. Finally, the current method generally adopts the form of excavating the ground to embed the anchor and transmit the force through the steel beam on the ground through the steel cable to achieve self-balancing axial loading. This requires the test site to have a suitable anchor structure or to have the conditions for excavating the ground to cast concrete anchors, which places stringent requirements on the site.

[0004] Chinese utility model CN220399092U discloses a self-balancing reaction force loading device for mechanical testing of large specimens. The force transmission system of the device adopts the form of steel bars and anchors, and there is no rotation system and horizontal loading system. When the top of the specimen is displaced and rotates around the bottom, the vertical loading device cannot rotate with the specimen. The lateral stiffness of the vertical loading device will also affect the lateral stiffness of the specimen. Therefore, it is not suitable for quasi-static tests that require simultaneous loading of horizontal and vertical loads. In addition, the jack of the device lacks protection measures, which increases the unsafe factor. The bottom of the device lacks a design for fixing the specimen, and the specimen cannot be constrained at the fixed end. Utility Model Content

[0005] In order to solve at least one of the problems existing in the prior art, the utility model proposes an adjustable loading device for seismic testing of large specimens, which is a self-balancing loading device in which axial and horizontal loading do not affect each other, does not affect the lateral stiffness of the specimen, and is less dependent on the site, so as to improve test efficiency and save test costs.

[0006] In order to achieve the purpose of the utility model, the utility model provides an adjustable loading device for seismic test of large specimens, including a reaction force system, a rotatable force transmission system and a loading system;

[0007] The reaction force system includes a base and a crossbeam, wherein the crossbeam is located above the base;

[0008] The rotatable force transmission system includes a rigid pull rod and a connecting piece. The connecting pieces are provided at both ends of the rigid pull rod, and the connecting pieces at both ends are rotatably connected to the base and the cross beam respectively. The rigid pull rod plays the role of connecting and transmitting loads.

[0009] When working, the test piece is located between the base and the beam;

[0010] The loading system includes a jack and a horizontal actuator. The jack is arranged on a crossbeam and the output end can contact the specimen to apply a vertical load to the specimen. The crossbeam can provide a reaction force to the jack to load the specimen. The horizontal actuator is used to apply a horizontal load to the specimen.

[0011] As a further improvement to the utility model, a limiting plate is provided on the base to limit the specimen and fix the horizontal displacement of the specimen base.

[0012] The base is provided with bolt holes, and the test piece is fixed on the base through the bolt holes and fasteners.

[0013] As a further improvement to the utility model, the base is located at the very bottom of the device, and the crossbeam is located at the very top of the device.

[0014] As a further improvement to the utility model, a specimen base is provided at the bottom of the specimen, and during operation, the specimen base is fixedly located in the limiting plate.

[0015] As a further improvement to the utility model, a base ear plate is provided on the base, a crossbeam ear plate is provided on the crossbeam, and the connecting pieces at both ends of the rigid pull rod are rotatably connected to the base ear plate and the crossbeam ear plate respectively.

[0016] Preferably, base ear plates are provided at both ends of the top surface of the base, and two crossbeam ear plates are correspondingly provided on the crossbeam, and rigid pull rods are provided between the oppositely arranged base ear plates and crossbeam ear plates.

[0017] The other two ends of the base are constrained by reaction walls, and the reaction walls are provided by the actual test site.

[0018] In a further improvement of the utility model, the connectors arranged at both ends of the rigid pull rod are rotatably connected to the base ear plate and the beam ear plate through bearings or pins. The connectors can realize free rotation in the ear plate plane through the pins / bearings.

[0019] Preferably, the base ear plate and the beam ear plate are provided with pin holes, and the connectors provided at both ends of the rigid pull rod are rotatably connected with the base ear plate and the beam ear plate through the pins. The pins can realize free rotation in the plane.

[0020] As a further improvement to the utility model, the end of the rigid pull rod is connected to the connecting piece through a nut.

[0021] As a further improvement to the utility model, when in operation, the horizontal actuator is located between the reaction wall and the test piece.

[0022] As a further improvement to the present invention, the loading system further comprises a pressure sensor, and the pressure sensor is arranged on the jack.

[0023] As a further improvement to the utility model, a limit box is further provided on the crossbeam, the jack is located in the limit box, and the output end of the jack extends out of the limit box.

[0024] Preferably, the limit box is fixed by welding at the mid-span of the crossbeam.

[0025] Preferably, the limit box is a cubic box with side openings, the top surface of the limit box is welded to the cross beam, and a hole is opened on the bottom surface to allow the top plate of the jack to extend out.

[0026] As a further improvement to the utility model, the side opening of the limit box is provided with a slot-type baffle movably disposed at the opening. After the jack is loaded into the limit box, the slot-type baffle can be closed to play a protective role.

[0027] As a further improvement to the utility model, the rigid pull rod is made of high-strength pull rod material, both ends of which are connected to connecting pieces and can rotate synchronously with the central axis of the specimen.

[0028] Compared with the prior art, the present invention can at least achieve the following beneficial effects:

[0029] (1) The utility model realizes the effect of loading horizontal load and vertical load simultaneously without affecting each other, thus ensuring the accuracy of low-cycle repeated tests;

[0030] (2) The device of the utility model can achieve self-balancing effect by itself, and does not require the site to have a ground anchor structure, so the test site is more flexible;

[0031] (3) The structure of the device of the utility model is detachable and the pull rod can be made of high-strength steel material. It has a small deadweight and can achieve large tonnage loading. It is lighter than a large frame loading system and is easy to store and transport;

[0032] (4) The utility model adopts a rigid tie rod and a nut instead of steel bars and anchors, so that the deformation of the connecting rod is smaller, the test is safer and more reliable, and the disadvantage that the lateral stiffness of the rigid tie rod affects the test results is avoided;

[0033] (5) The utility model ensures that when the specimen produces a large inter-story displacement angle, the vertical load action line remains consistent with the central axis of the specimen;

[0034] (6) The beam limit box of the utility model protects the jack and the pressure sensor, preventing the pressure sensor from slipping, falling or even popping out due to huge pressure, making the test safer and more reliable;

[0035] (7) The device of the utility model can select rigid pull rods of different lengths according to different sizes of the test pieces to achieve a height adjustable effect;

[0036] (8) In addition to being used for quasi-static tests, the device of the utility model can also be used for static tests that require a certain lateral displacement or static tests that do not require lateral displacement.

[0037] (9) The device of the utility model can be used for testing specimens such as independent columns and special-shaped columns, and multiple sets of the device can also be used in combination for testing structures such as frames and shear walls. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic structural diagram of an adjustable loading device for seismic testing of large specimens provided in an embodiment of the utility model.

[0039] Figure 2 It is a structural schematic diagram of the base in the embodiment of the utility model.

[0040] Figure 3 It is a top view of the base in the embodiment of the utility model.

[0041] Figure 4 It is a schematic diagram of the structure of the crossbeam in the embodiment of the utility model.

[0042] Figure 5 Schematic diagram of the test piece tested in the embodiment of the present utility model.

[0043] Figure 6 This is a schematic diagram of the device used for an independent column specimen in an embodiment of the utility model.

[0044] Figure 7 This is a schematic diagram of a combination of multiple devices used for a portal frame test piece in an embodiment of the utility model.

[0045] Description of reference numerals:

[0046] 1—crossbeam; 2—hydraulic jack; 3—horizontal actuator; 4—rigid pull rod; 5—test piece; 6—first connecting piece; 7—base; 8—nut; 9—base ear plate; 10—first pin shaft; 11—limit plate; 12—test piece base; 13—crossbeam ear plate; 14—slot baffle; 15—limit box; 16—bolt hole; 17—second pin shaft; 18—second connecting piece. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0048] Figure 1 The schematic diagram of the structure of the adjustable loading device for seismic test of large specimens according to the utility model is shown. Figure 2 , Figure 4 , Figure 5 The base part, beam part and specimen part of the device are shown respectively.

[0049] Please see Figure 1 The utility model provides an adjustable loading device for seismic test of large specimens, including a reaction force system, a rotatable force transmission system and a loading system. The reaction force system includes a crossbeam 1 and a base 7, and the rotatable force transmission system includes a rigid pull rod 4 and a connecting piece. The loading system includes a jack, a pressure sensor and a horizontal actuator 3.

[0050] Please see Figure 2 The base 7 is at the bottom of the device, and plays the role of bearing the test piece and the device, and fixing the test piece; two base ear plates 9 are set at both ends of the top surface of the base 7, and the other two ends are constrained by the reaction wall. The reaction wall is provided by the actual test site. The two base ear plates 9 are connected to the two first connecting members 6 through the first pin shaft 10, and the first connecting member 6 can rotate freely around the first pin shaft 10. The top surface of the base 7 is also provided with a limit plate 11 and a bolt hole 16 (see Figure 3 ), used to fix the specimen 5. Figure 5 The bottom of the specimen 5 is provided with a specimen base 12, and the specimen base 12 is matched with the limiting plate 11. When the specimen base 12 is placed in the limiting plate 11 and connected to the bolt hole 16 by bolts, the bottom of the specimen 5 is regarded as a fixed end.

[0051] In some embodiments of the present invention, the base 7 is a steel member with a certain bending rigidity; the first connecting member 6 is welded by an ear plate and a bending-resistant short beam with a hole (a hole through which the rigid pull rod 4 can pass); and the limit plate 11 is a steel plate.

[0052] See also Figure 4 The cross beam 1 is located above the base 8 and at the top of the device, and plays a role in providing support for the loading system. A limit box 15 and two cross beam lugs 13 are welded to the bottom of the cross beam 1. A slot-type baffle 14 is movably provided on the limit box 15. During the test, the jack 2 and the pressure sensor are placed in the limit box 15, and the pressure sensor is placed on the jack 2, and is restricted from moving or popping out by the slot-type baffle 14. The two cross beam lugs 13 are located on both sides of the limit box 15, and the two cross beam lugs 13 are respectively connected to the second connecting member 18 through the second pin shaft 17, and the second connecting member 18 can rotate freely around the second pin shaft 17.

[0053] The second connecting member 18 is formed by welding an ear plate and a bending-resistant short beam with a hole (a hole through which the rigid tie rod 4 can pass).

[0054] In some embodiments of the present invention, the cross beam 1 is a steel beam.

[0055] In some embodiments of the present invention, a limit box 15 is welded and fixed at the mid-span of the crossbeam 1 .

[0056] In some embodiments of the present invention, the beam ear plate 13 and the base ear plate 9 are both steel plates with pin holes.

[0057] In some embodiments of the utility model, the limit box 15 is a cubic box with a side opening, the top surface is welded to the crossbeam 1, and the bottom surface is provided with a square hole. The top plate of the jack extends out from the hole on the bottom surface of the limit box to contact the test piece 5, and a slot-type baffle 14 is movably provided at the side opening.

[0058] In some embodiments of the present invention, the first pin shaft 10 and the second pin shaft 17 can be connected by connection methods including but not limited to ordinary pin shafts, rolling bearings, etc. that can achieve free rotation in the plane.

[0059] In some embodiments of the present invention, the jack is a top plate with a ball joint type hydraulic jack that can adapt to the rotation of the loading surface.

[0060] Please see Figure 1, the specimen 5 is placed on the base 7, the beam 1 and the jack 2 are placed above the specimen 5, one end of the horizontal actuator 3 is connected to the reaction wall, and the other end is connected to the specimen 5, and the output end of the jack 2 can contact the specimen 5, and at the same time, the total of 4 connecting parts of the beam 1 and the base 7, the first connecting part 6 and the second connecting part 18 on the same side are connected by a rigid tie rod 4, and are fixed with nuts 8 respectively, so that the device can achieve self-balancing vertically. The specimen 5 is applied with a horizontal load through the horizontal actuator 3, and the horizontal actuator 3 and the base 7 of the device constrain the horizontal displacement through the specific test site and test conditions.

[0061] Compared with the combination of steel bars and anchors, the combination of rigid tie rods and nuts has the advantages of high rigidity, small deformation, small elastic potential energy, and nut slippage, which makes it safer to use in mechanical tests. However, excessive lateral stiffness will also affect the lateral stiffness of the specimens in low-cycle repeated tests. In order to avoid its shortcomings, connectors are introduced. The connectors are tension members with ear plates, which are connected to the rotatable reaction force system through a pin to achieve the rotation function, which can eliminate the influence of the lateral stiffness of the rigid tie rods.

[0062] At the beginning of the test, the predetermined vertical load is applied by the jack 2, and the reaction force is transmitted to the base 7 through the crossbeam 1 and the rigid tie rod 4. The vertical load is kept constant, and the low-cycle repeated load is gradually applied through the horizontal actuator 3. Because of the existence of the rotatable force transmission system, the rigid tie rod 4 will not affect the lateral stiffness of the specimen 5. When the low-cycle repeated load is applied, the vertical load can also maintain a stable value, and the test effect is good.

[0063] See also Figure 6 and Figure 7 In addition to specimen 5, it can also be used for independent column specimens and multiple sets of devices can be combined for portal frame and other specimens. In addition to being used for quasi-static tests, this device can also be used for static tests.

[0064] In the adjustable loading device provided by the aforementioned embodiment of the utility model, the jack 2 applies pressure to the specimen 5, and the crossbeam 1 provides a reaction force for the jack 2. The rigid pull rod 4 and the connecting member transmit the reaction force to the base 7 in the form of tension. The base 7 bears the pressure of the specimen 5 and the tension of the rigid pull rod 4, and the device itself achieves a self-balancing effect.

[0065] The adjustable loading device provided in the aforementioned embodiment of the utility model has rotatable connecting parts connected to the upper and lower ends of the rigid pull rod 4. This structure can only withstand tension but not pressure and shear force, and basically has no lateral stiffness. Therefore, it will not affect the lateral stiffness of the specimen in the quasi-static test, so the accuracy of the test results can be guaranteed.

[0066] The adjustable loading device provided by the aforementioned embodiment of the utility model, due to the existence of the rotatable force transmission system, the jack 2, the beam 1, the connecting piece, and the rigid pull rod 4 can rotate with the rotation of the test piece 5 around the base 7. Within a certain rotation angle, the load applied by the jack 2 remains basically constant, and the effect of applying a horizontal load without affecting the size of the vertical force can be achieved, that is, the horizontal load and the vertical load are loaded at the same time without affecting each other.

[0067] The jack 2, the cross beam 1, the connector, and the rigid tie rod 4 can rotate along with the specimen as it rotates around the base, and the tension borne by the rigid tie rod 4 is along the direction of the tie rod itself. Therefore, when the top of the specimen 5 is displaced and the central axis is deflected, the rigid tie rod 4 can deflect along with the specimen 5, and the line of action of the tension also remains coincident with the central axis of the specimen 5, so that the axial load of the specimen 5 is not affected.

[0068] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These purposes are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different options and changes. The scope of the present invention is intended to be defined by the claims and their equivalents.

Claims

1. An adjustable loading device for seismic testing of large specimens, characterized in that: It includes a reaction force system, a rotatable force transmission system and a loading system; The reaction force system includes a base and a crossbeam, wherein the crossbeam is located above the base; The rotatable force transmission system comprises a rigid pull rod and a connecting piece, both ends of the rigid pull rod are provided with the connecting piece, and the connecting pieces at both ends are rotatably connected to the base and the cross beam respectively; When working, the test piece is located between the base and the beam; The loading system comprises a jack and a horizontal actuator. The jack is arranged on a crossbeam and an output end of the jack can contact with the specimen to apply a vertical load to the specimen. The horizontal actuator is used to apply a horizontal load to the specimen.

2. The adjustable loading device for seismic test of large specimens according to claim 1, characterized in that: A limiting plate is arranged on the base to limit the test piece.

3. The adjustable loading device for seismic test of large specimens according to claim 2, characterized in that: A specimen base is arranged at the bottom of the specimen, and during operation, the specimen base is fixed in the limiting plate.

4. The adjustable loading device for seismic testing of large specimens according to claim 1, characterized in that: The base is provided with a base ear plate, the crossbeam is provided with a crossbeam ear plate, and the connecting pieces at both ends of the rigid pull rod are rotatably connected with the base ear plate and the crossbeam ear plate respectively.

5. The adjustable loading device for seismic test of large specimens according to claim 1, characterized in that: The connecting pieces arranged at both ends of the rigid pull rod are rotatably connected with the base ear plate and the crossbeam ear plate through bearings or pin shafts.

6. The adjustable loading device for seismic test of large specimens according to claim 1, characterized in that: The end of the rigid pull rod is connected to the connecting piece through a nut.

7. The adjustable loading device for large specimen seismic test according to claim 1, characterized in that: When working, the horizontal actuator is located between the reaction wall and the test piece.

8. The adjustable loading device for seismic test of large specimens according to claim 1, characterized in that: The loading system further comprises a pressure sensor, and the pressure sensor is arranged on the jack.

9. An adjustable loading device for seismic testing of large specimens according to any one of claims 1 to 8, characterized in that: A limit box is also arranged on the crossbeam, the jack is located in the limit box, and the output end of the jack extends out of the limit box.

10. The adjustable loading device for large specimen seismic test according to claim 9, characterized in that: The side of the limit box is opened, and a slot-type baffle is movably arranged at the opening.

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