Device and method for carrying out hysteresis test by adopting prestress loading instead of vertical load

Abstract

The invention provides a device and method for carrying out a hysteresis test by adopting prestress loading instead of vertical load, the device comprises a vertical loading assembly, a horizontal loading assembly, a supporting and fixing assembly and a test object, and the test object is a hollow structural member; the vertical loading assembly is arranged in the vertical direction, a core component of the vertical loading assembly is a high-strength bolt rod, the high-strength bolt rod is connected with a rigid base plate V at the bottom of the hollow structural member in a fastened mode, and it is ensured that vertical prestress is evenly transmitted to the hollow structural member. The horizontal loading assembly comprises a reaction wall and an MTS servo actuator, one end of the MTS servo actuator is fixed to the reaction wall through an actuator connecting bolt, and the other end of the MTS servo actuator is connected with the side portion of the hollow structural member through a clamping device. The sensor is arranged on the prestress self-loading device, the axial force can be monitored in real time, real-time adjustment can be carried out according to data on the sensor in the test process, the axial force can meet the test requirement all the time, and it is guaranteed that the test result is reliable.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vertical load loading device, in particular to a device and method for carrying out hysteresis test by using prestress loading instead of vertical load. BACKGROUND

[0002] Hollow members have the advantages of low weight and high strength, and are widely used in fabricated systems. Low-cycle reciprocating loading test loading is the core means to study the seismic performance of such members, and constant vertical axial force needs to be applied during the test process, and then horizontal reciprocating load is applied to simulate the action of earthquake. During the hysteresis test process, the member needs to be subjected to vertical load and axial load at the same time.

[0003] In the traditional axial pressure application method, a vertical hydraulic servo actuator is directly loaded, and this method has certain technical defects: during the test process, the member will appear bending deformation phenomenon. The bending deformation of the member causes the vertical hydraulic servo actuator to be unable to accurately provide the vertical axial force of the member, and the member is no longer in the state of axial compression. This phenomenon will affect the accuracy and stability of the test data to some extent, and may even cause the test to fail.

[0004] Based on the shortcomings of the above-mentioned traditional loading method, it is necessary to design a test device which can ensure that the test piece is always in the state of axial compression, and ensure the smooth development of the test and the reliability of the results SUMMARY

[0005] The purpose of the present application is to provide a device and method for carrying out hysteresis test by using prestress loading instead of vertical load, to solve the problems raised in the background art.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0007] A device for carrying out hysteresis test by using prestress loading instead of vertical load, comprising:

[0008] A vertical loading assembly, a horizontal loading assembly, a support fixing assembly and a test object, the test object being a hollow structural member;

[0009] The vertical loading assembly is arranged along the vertical direction, and the core component thereof is a high-strength bolt rod. The high-strength bolt rod is inserted into the inside of the hollow structural member, and the high-strength bolt rod passes through, from top to bottom, a flange with a washer nut I, an extended nut I, a rigid pad I, a through-hole load sensor, a rigid pad II, a through-hole jack, a rigid pad III, a flange with a washer nut II, an extended nut II, and a rigid pad IV, and is fastened and connected with a rigid pad V at the bottom of the hollow structural member through an extended nut III and a flange with a washer nut III, so as to ensure that the vertical prestress is uniformly transmitted to the hollow structural member.

[0010] The support fixing assembly comprises a component support and a ground anchor bolt, the component support is fixed to the test foundation through the ground anchor bolt, and the bottom of the hollow structural component is connected to the component support;

[0011] The horizontal loading assembly comprises a counter-force wall, an MTS servo actuator and a clamping device, one end of the MTS servo actuator is fixed to the counter-force wall through an actuator connecting bolt, and the other end is connected to the side of the hollow structural component through the clamping device; a through-type load sensor is used for real-time monitoring of the vertical prestress, a through-type jack is used for applying a vertical prestress to replace a traditional vertical load, and the MTS servo actuator is used for applying a horizontal reciprocating load to realize a hysteretic test.

[0012] Preferably, the rigid pads I, II, III, IV and V are made of high-strength alloy materials, and the areas of the pads are not less than the areas of the corresponding contact end faces of the through-type jacks or the hollow structural component, so as to disperse the load and avoid local stress concentration.

[0013] Preferably, the two ends of the through-type load sensor are tightly attached to the rigid pads I and II respectively, so as to ensure the accuracy of load monitoring.

[0014] Preferably, the clamping device comprises upper and lower symmetrically arranged clamping plates and fastening bolts, the inner sides of the clamping plates are provided with anti-skid pads, the spacing between the clamping plates is adjusted through the fastening bolts to adapt to hollow structural components with different cross-sectional sizes, the clamping plates are connected to the output end of the MTS servo actuator through a spherical hinge, and the coaxiality of horizontal load transmission is ensured.

[0015] Preferably, the component support comprises a base and limiting plates, the base is fixed to the test foundation through ground anchor bolts, the limiting plates are vertically arranged on both sides of the top of the base, the bottom of the hollow structural component is embedded between the two limiting plates, the contact surfaces between the limiting plates and the hollow structural component are provided with buffer pads, and the horizontal displacement of the hollow structural component is limited while local damage is avoided.

[0016] A method for carrying out a hysteretic test by using a prestress load to replace a vertical load, characterized in that the method comprises the following steps:

[0017] S1 device installation: the component support is fixed to the test foundation through the ground anchor bolt, the bottom of the hollow structural component is installed to the component support, the rigid pad V, the lengthened nut III and the flange pad nut III are sequentially assembled, the high-strength bolt rod is penetrated through each component from top to bottom and fastened to ensure that each rigid pad is tightly attached, the MTS servo actuator is fixed to the counter-force wall through the actuator connecting bolt, and the MTS servo actuator is connected to the hollow structural component through the clamping device;

[0018] S2 prestress application: start the through jack, apply vertical prestress to the hollow structural member, monitor the load value in real time through the through load sensor, and lock and fix after reaching the preset prestress value through the flange pad nut I, the long nut I, the flange pad nut II and the long nut II to keep the prestress stable;

[0019] S3 hysteresis loading test: start the MTS servo actuator, apply horizontal reciprocating load to the hollow structural member according to the preset loading system, and record the monitoring data of the through load sensor and the displacement response of the hollow structural member synchronously, and complete the hysteresis test;

[0020] S4 test end: after the test is completed, unload the horizontal load of the MTS servo actuator, then unload the vertical prestress through the through jack, and finally remove each connecting part and device.

[0021] Preferably, in step S2, the vertical prestress is applied in a step loading mode, each step loading value is 20% of the preset value, and each step loading is stabilized for 3-5 minutes to ensure that the hollow structural member is stressed stably.

[0022] Preferably, in step S3, the preset loading system is displacement control loading, the loading amplitude is set in an equal amplitude or increasing amplitude mode, each displacement amplitude is cyclically loaded for 3-5 times, and the cycle gap is stabilized for 1-2 minutes to ensure the reliability of the test data.

[0023] Compared with the prior art, the beneficial effects of the present application are:

[0024] The present application is equipped with a sensor on the prestressed self-loading device, which can monitor the axial force in real time. During the test, the data on the sensor can be adjusted in real time to ensure that the axial force always meets the test requirements and ensures the reliability of the test results.

[0025] The present application realizes uniform transmission of vertical prestress by penetrating the hollow structural member from the inside through the high-strength bolt rod, and disperses the load by double fastening of multiple nuts and multiple rigid pads, effectively avoiding local uneven stress and stress concentration, and ensuring the stability of the member during the test process.

[0026] The present application realizes real-time and accurate capture of dynamic changes of vertical prestress through the design of the through load sensor and the rigid pad, and synchronously collects load and displacement data through the high-precision control of the MTS servo actuator, which significantly improves the accuracy and reliability of the hysteresis test data. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is a prestressed tensioning schematic diagram of the present application;

[0028] Figure 2 It is a prestressed tensioning completion schematic diagram of the present application;

[0029] Figure 3 This is a front view of the experimental apparatus of the present invention;

[0030] Figure 4 This is a three-dimensional view of the experimental apparatus of the present invention;

[0031] Figure 5 For the present invention Figure 3 Cross-sectional view of experimental setup 1-1;

[0032] Figure 6 For the present invention Figure 3 Cross-sectional view of the hollow structural component in the pilot test (2-2);

[0033] Figure 7 For the present invention Figure 3 Cross-sectional view of the experimental setup 3-3.

[0034] In the diagram: 1. High-strength bolt rod; 2. Flange with washer nut I; 3. Extended nut I; 4. Rigid pad I; 5. Through-hole load sensor; 6. Rigid pad II; 7. Through-hole jack; 8. Rigid pad III; 9. Flange with washer nut II; 10. Extended nut II; 11. Rigid pad IV; 12. Hollow structural component; 13. Rigid pad V; 14. Extended nut III; 15. Flange with washer nut III; 16. Component support; 17. Ground anchor bolt; 18. Actuator connecting bolt; 19. Reaction wall; 20. MTS servo actuator; 21. Clamping device. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Example:

[0037] Please see Figures 1 to 7 The present invention provides a technical solution:

[0038] A device for conducting hysteresis tests by replacing vertical load with prestressed loading is based on the fact that the traditional vertical load application method is replaced by vertical prestressed loading to achieve accurate testing of the hysteresis performance of hollow structural component 12. The device consists of a vertical loading component, a horizontal loading component, a support and fixing component and the test object (hollow structural component 12). The components work together to ensure the stability of the test and the reliability of the data.

[0039] The vertical loading assembly, arranged vertically, is the core unit for achieving prestressed loading. Its design revolves around the uniform application, real-time monitoring, and stable maintenance of the load. The core load-bearing component is a high-strength bolt rod 1, which is adapted to the internal cavity size of the hollow structural member 12 and runs through the member to form a vertical load-bearing skeleton. From top to bottom, the high-strength bolt rod 1 passes through the flange with washer nut I2, the extended nut I3, the rigid pad I4, the through-hole load sensor 5, the rigid pad II6, the through-hole jack 7, the rigid pad III8, the flange with washer nut II9, the extended nut II10, and the rigid pad IV11. Finally, it forms a double fastening connection with the rigid pad V13 at the bottom of the hollow structural member 12 through the extended nut III14 and the flange with washer nut III15. Through the locking fit of the multi-stage nuts, the uniform transfer of vertical prestress from the loading end to the member is ensured, avoiding test errors caused by uneven local stress.

[0040] Among them, rigid pads I4, II6, III8, IV11, and V13 are all made of high-strength alloy materials, possessing excellent compressive strength and stiffness. The area of ​​each pad is strictly controlled to be no less than the area of ​​the corresponding contact end face of the through-hole jack 7 or hollow structural component 12, effectively dispersing concentrated loads and preventing component damage or deformation of the loading equipment due to localized stress concentration during loading. The through-hole load sensor 5, as the core component for force monitoring, is tightly fitted at both ends to rigid pads I4 and II6 respectively, eliminating monitoring errors caused by gaps in the contact surfaces and ensuring real-time capture of dynamic changes in vertical prestress, thus guaranteeing the accuracy of the test data.

[0041] The horizontal loading assembly, used to apply horizontal reciprocating loads to achieve hysteresis testing, mainly consists of a reaction wall 19, an MTS servo actuator 20, and a clamping device 21. The reaction wall 19 serves as the supporting foundation for the horizontal load and is fixed to one end of the MTS servo actuator 20 via actuator connecting bolts 18, ensuring the actuator's stability during loading. The MTS servo actuator 20 possesses high-precision load and displacement control capabilities, and its output end is connected to the side of the hollow structural member 12 via the clamping device 21, enabling precise transmission of the horizontal reciprocating load.

[0042] The clamping device 21 adopts an adjustable structural design, including clamping plates and fastening bolts arranged symmetrically on the upper and lower sides. The inner side of the clamping plates is provided with an anti-slip pad, which enhances the friction with the surface of the hollow structural member 12, preventing relative slippage during loading, and also avoids damage to the member surface caused by excessive clamping force. The clamping plate spacing can be flexibly adjusted by the fastening bolts to accommodate hollow structural members 12 with different cross-sectional dimensions, improving the device's versatility. Simultaneously, the clamping plates are connected to the output end of the MTS servo actuator 20 via a ball joint, which can automatically compensate for minor angular deviations of the member during loading, ensuring the coaxiality of horizontal load transmission and ensuring that the load direction is consistent with the experimental design.

[0043] The supporting and fixing components undertake the positioning and stabilization functions of the overall device, including component supports 16 and ground anchor bolts 17. Component supports 16 are firmly connected to the test foundation via ground anchor bolts 17. The embedment depth and tightening torque of the ground anchor bolts 17 are rigorously designed to ensure they can resist the overturning force and horizontal thrust generated by the horizontal reciprocating load during the test, preventing support displacement from affecting the test results. Component supports 16 specifically consist of a base and limiting plates. The base is welded from heavy-duty steel plates and stiffening ribs to enhance overall rigidity. The limiting plates are vertically positioned on both sides of the top of the base, forming symmetrical limiting spaces. The bottom of the hollow structural component 12 is embedded between the two limiting plates. A buffer pad is provided on the contact surface between the limiting plates and the hollow structural component 12. This effectively buffers the local impact force during the transmission of horizontal loads, while limiting the horizontal displacement of the hollow structural component 12 and ensuring the axial stability of the component during loading, thus preventing damage to the bottom of the component.

[0044] A method for conducting hysteresis tests using prestressed loading instead of vertical loads includes the following steps:

[0045] S1 device installation: Fix component support 16 to the test foundation with ground anchor bolts 17, install the bottom of hollow structural component 12 to component support 16, and assemble rigid pad V 13, extended nut III 14, and flange with washer nut III 15 in sequence; tighten the high-strength bolt rod 1 through each component from top to bottom to ensure that each rigid pad fits tightly; fix MTS servo actuator 20 to reaction wall 19 with actuator connecting bolts 18, and connect MTS servo actuator 20 to hollow structural component 12 using clamping device 21;

[0046] S2 Prestressing Application: Start the through-hole jack 7 to apply vertical prestress to the hollow structural member 12. The load value is monitored in real time by the through-hole load sensor 5. After the preset prestress value is reached, it is locked and fixed by flange with gasket nut I2, extended nut I3, flange with gasket nut II9, and extended nut II10 to maintain the stability of the prestress.

[0047] S3 Hysteresis Loading Test: Start the MTS servo actuator 20 and apply a horizontal reciprocating load to the hollow structural member 12 according to the preset loading regime. Simultaneously record the monitoring data of the through-hole load sensor 5 and the displacement response of the hollow structural member 12 to complete the hysteresis test.

[0048] S4 Test Completion: After the test, first unload the horizontal load of the MTS servo actuator 20, then unload the vertical prestress through the through-hole jack 7, and finally dismantle all connecting parts and devices.

[0049] In step S1, the support and fixing components are first installed. The component support 16 is firmly fixed to the test foundation using ground anchor bolts 17, ensuring that the support base is horizontal and tightly fitted to the foundation without any looseness. Then, the hollow structural component 12 is hoisted between the limiting plates of the component support 16, and the verticality of the component is adjusted so that the component's axis coincides with the force centerline of the vertical loading component. A rigid pad V13 is installed at the bottom of the hollow structural component 12, and the extended nut III14 and the flange-mounted washer nut III15 are installed and initially tightened, laying the foundation for subsequent prestress transfer.

[0050] From top to bottom, the high-strength bolt rod 1 is passed through the flange with washer nut I2, the extended nut I3, the rigid pad I4, the through-hole load sensor 5, the rigid pad II6, the through-hole jack 7, the rigid pad III8, the flange with washer nut II9, the extended nut II10, and the rigid pad IV11, until it connects to the rigid pad V13 at the bottom of the hollow structural member 12. Each component is tightened one by one to ensure that each rigid pad fits tightly with the adjacent component without gaps. Finally, the horizontal loading assembly is installed. The MTS servo actuator 20 is fixed to the reaction wall 19 by the actuator connecting bolt 18. The height of the actuator is adjusted, and the clamping device 21 is used to clamp the side of the hollow structural member 12, ensuring that the clamping is firm and that the output end of the actuator is aligned with the force point of the member.

[0051] In step S2, the through-hole jack 7 is activated to apply vertical prestress to the hollow structural member 12. To avoid damage to the member due to excessive instantaneous load, a graded loading method is adopted, with each loading value being 20% ​​of the preset prestress value. After each loading is completed, the pressure is stabilized for 3-5 minutes to allow the hollow structural member 12 to fully adapt to the load and achieve uniform stress distribution. During the loading process, the vertical prestress magnitude is monitored in real time by the through-hole load sensor 5. When the monitored value reaches the preset value and stabilizes, the flange gasket nut I2, the extended nut I3, the flange gasket nut II9, and the extended nut II10 are tightened in sequence to form a double locking fixation, ensuring that the vertical prestress remains stable and does not loosen during subsequent horizontal loading.

[0052] In step S3, after the vertical prestress stabilizes, the MTS servo actuator 20 is activated to apply a horizontal reciprocating load to the hollow structural member 12 according to the preset loading regime. The loading regime adopts a displacement control mode, and the loading amplitude can be set according to the test requirements in a constant amplitude or incremental manner. Each displacement amplitude level is cyclically loaded 3-5 times, with a 1-2 minute stabilization interval between cycles to ensure that the member can return to a stable state after each loading cycle, guaranteeing the repeatability and reliability of the test data. During the loading process, real-time monitoring data from the through-hole load sensor 5, horizontal load data from the MTS servo actuator 20, and displacement response data from the hollow structural member 12 are simultaneously collected to form a complete hysteresis performance dataset. The test is stopped when the member exhibits significant plastic deformation, the load drops to 85% of the peak load, or the structure fails.

[0053] In step S4, after the hysteresis loading test is completed, the unloading is carried out in the order of "horizontal first, then vertical": First, the MTS servo actuator 20 is controlled to gradually unload the horizontal load until the load is zero; then, the vertical prestress is slowly unloaded through the through-hole jack 7 to avoid stress impact caused by instantaneous unloading and damage to the components or devices; finally, the clamping device 21, the MTS servo actuator 20, the various nuts, washers, sensors and jacks matched with the high-strength bolt rod 1 are removed in sequence, the hollow structure component 12 is taken out, the test device is cleaned and maintained, and the entire test process is completed.

[0054] All other parts of this invention not described herein are the same as existing technologies, or are known technologies, or can be implemented using existing technologies, and will not be described in detail here.

[0055] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A device for conducting hysteresis tests using prestressed loading instead of vertical load, characterized in that, include: Vertical loading component, horizontal loading component, support and fixing component and test object, the test object is a hollow structural component (12). The vertical loading assembly is arranged in the vertical direction. Its core component is a high-strength bolt rod (1). The high-strength bolt rod (1) is inserted into the hollow structure component (12). The high-strength bolt rod (1) passes through the flange with washer nut I (2), the extended nut I (3), the rigid pad I (4), the through-hole load sensor (5), the rigid pad II (6), the through-hole jack (7), the rigid pad III (8), the flange with washer nut II (9), the extended nut II (10), and the rigid pad IV (11) from top to bottom. Then, it is fastened to the rigid pad V (13) at the bottom of the hollow structure component (12) through the extended nut III (14) and the flange with washer nut III (15) to ensure that the vertical prestress is uniformly transmitted to the hollow structure component (12). The support and fixing assembly includes a component support (16) and a ground anchor bolt (17). The component support (16) is fixed to the test foundation by the ground anchor bolt (17). The bottom of the hollow structure component (12) is connected to the component support (16). The horizontal loading assembly includes a reaction wall (19), an MTS servo actuator (20), and a clamping device (21). One end of the MTS servo actuator (20) is fixed to the reaction wall (19) via an actuator connecting bolt (18), and the other end is connected to the side of the hollow structure component (12) via the clamping device (21). The through-hole load sensor (5) is used to monitor the magnitude of vertical prestress in real time, the through-hole jack (7) is used to apply vertical prestress to replace the traditional vertical load, and the MTS servo actuator (20) is used to apply horizontal reciprocating load to achieve hysteresis test.

2. The apparatus for conducting hysteresis tests using prestressed loading instead of vertical loads as described in claim 1, characterized in that: The rigid pad I (4), rigid pad II (6), rigid pad III (8), rigid pad IV (11) and rigid pad V (13) are all made of high-strength alloy material, and the area of ​​the pad is not less than the area of ​​the corresponding contact end face of the through-hole jack (7) or hollow structure component (12).

3. The apparatus for conducting hysteresis tests using prestressed loading instead of vertical loads as described in claim 1, characterized in that: The two ends of the through-hole load sensor (5) are tightly fitted to the rigid pad I (4) and the rigid pad II (6) respectively.

4. The apparatus for conducting hysteresis tests using prestressed loading instead of vertical loads as described in claim 1, characterized in that: The clamping device (21) includes clamping plates and fastening bolts arranged symmetrically on the upper and lower sides. The inner side of the clamping plate is provided with an anti-slip pad. The clamping plate spacing is adjusted by the fastening bolts to adapt to hollow structural components (12) with different cross-sectional dimensions. The clamping plate is connected to the output end of the MTS servo actuator (20) through a ball joint.

5. The apparatus for conducting hysteresis tests using prestressed loading instead of vertical loads as described in claim 1, characterized in that: The component support (16) includes a base and a limiting plate. The base is fixed to the test foundation by ground anchor bolts (17). The limiting plate is vertically set on both sides of the top of the base. The bottom of the hollow structure component (12) is embedded between the two limiting plates. The contact surface between the limiting plate and the hollow structure component (12) is provided with a buffer pad.

6. A method for conducting a hysteresis test using the apparatus described in any one of claims 1-5, characterized in that, Includes the following steps: S1 device installation: Fix the component support (16) to the test foundation with ground anchor bolts (17), install the bottom of the hollow structure component (12) to the component support (16), and assemble the rigid pad V (13), extended nut III (14), and flange with washer nut III (15) in sequence; tighten the high-strength bolt rod (1) through each component from top to bottom to ensure that each rigid pad fits tightly; fix the MTS servo actuator (20) and the reaction wall (19) with actuator connecting bolts (18), and connect the MTS servo actuator (20) and the hollow structure component (12) with clamping device (21); S2 Prestressing Application: Start the through-hole jack (7) to apply vertical prestress to the hollow structure component (12). Monitor the load value in real time through the through-hole load sensor (5). After reaching the preset prestress value, lock and fix it through flange with gasket nut I (2), extended nut I (3), flange with gasket nut II (9), and extended nut II (10) to keep the prestress stable. S3 Hysteresis Loading Test: Start the MTS servo actuator (20) and apply a horizontal reciprocating load to the hollow structural member (12) according to the preset loading regime. Simultaneously record the monitoring data of the through-hole load sensor (5) and the displacement response of the hollow structural member (12) to complete the hysteresis test. S4 Test Closure: After the test, first unload the horizontal load of the MTS servo actuator (20), then unload the vertical prestress through the through-hole jack (7), and finally dismantle all connecting parts and devices.

7. A method for conducting hysteresis tests using prestressed loading instead of vertical loads, as described in claim 6, characterized in that... In step S2, the vertical prestress is applied in a graded loading method, with each loading value being 20% ​​of the preset value. After each loading, the pressure is stabilized for 3-5 minutes to ensure the stability of the hollow structure component (12) under stress.

8. A method for conducting hysteresis tests using prestressed loading instead of vertical loads, as described in claim 6, characterized in that: In step S3, the preset loading regime is displacement control loading, and the loading amplitude is set in the form of constant amplitude or increasing amplitude. The loading is cyclically loaded 3-5 times under each displacement amplitude, and the pressure is stabilized for 1-2 minutes between cycles to ensure the reliability of the test data.

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