A low cycle fatigue test device for building steel structure

Abstract

The utility model belongs to building steel structure detection equipment technical field, specifically provides a kind of building steel structure low-cycle fatigue test device including workbench, support frame and mounting plate being set on the support frame top, workbench is located the both sides of support frame sliding direction respectively fixed with counterforce frame, each counterforce frame is respectively fixed with first telescopic cylinder, the output of each first telescopic cylinder is fixedly connected with support frame, the top surface of support frame is fixed with multiple second telescopic cylinders, the output of multiple second telescopic cylinders is fixedly connected with the bottom surface of mounting plate, and mounting plate is equipped with multiple bolt holes. The utility model drives mounting plate and scale-down building steel structure to do up-down reciprocating motion by first telescopic cylinder and second telescopic cylinder, realizes the simulation of multidimensional composite load, carries out bolt connection by bolt hole on mounting plate and scale-down building steel structure, simulates the mode of foundation bolt connection, can more truly reflect low-cycle fatigue performance.

Description

Technical Field

[0001] This application belongs to the technical field of building steel structure testing equipment, and more specifically, it relates to a low-cycle fatigue testing device for building steel structures. Background Technology

[0002] Steel structures are widely used due to their superior seismic performance, environmental friendliness and energy efficiency, high compressive strength, and high-quality, lightweight industrialized materials. However, with the rapid development of steel structure construction, during long-term service, the joints and connections of steel structures are prone to damage accumulation due to low-cycle fatigue, ultimately leading to structural performance degradation or even failure. Low-cycle fatigue refers to the fatigue failure phenomenon that occurs in materials under conditions of large strain amplitude and low cycle count. Its research is crucial for evaluating the durability and safety of steel structures under extreme loads.

[0003] Research on the low-cycle fatigue performance of steel structures in buildings primarily relies on experimental simulation techniques. Traditional testing devices often employ hydraulic servo systems or mechanical loading devices to conduct fatigue tests on steel structure specimens by simulating cyclic loading under actual working conditions. However, most devices can only achieve reciprocating loading in a single direction, making it difficult to simulate the multi-dimensional coupled load conditions under complex seismic loading, leading to discrepancies between experimental results and the stress state in actual engineering. Furthermore, welded fixed connections are often used in experiments to replace anchor bolt connections in actual engineering, failing to accurately reflect the impact of details such as bolt loosening, preload loss, and contact surface friction on low-cycle fatigue performance, easily resulting in a disconnect between experimental data and actual engineering behavior. Utility Model Content

[0004] Based on the above-mentioned technical problems, this application provides a low-cycle fatigue testing device for building steel structures to solve the technical problems that existing low-cycle fatigue testing devices are difficult to simulate multi-dimensional coupled load conditions under complex seismic action, resulting in deviations between test results and stress states in actual engineering, and that welding fixed connections are often used in the test instead of anchor bolt connections in actual engineering, which easily leads to a disconnect between test data and actual engineering behavior.

[0005] To achieve the above objectives, the technical solution adopted in this application is as follows: a low-cycle fatigue testing device for building steel structures is provided, comprising: a workbench, a support frame slidably disposed on the workbench, and a mounting plate disposed above the support frame. Reaction frames are fixedly disposed on both sides of the workbench in the sliding direction of the support frame. A first telescopic cylinder is fixedly disposed horizontally on each reaction frame. The output end of each first telescopic cylinder is fixedly connected to the support frame. Multiple second telescopic cylinders are vertically fixedly disposed on the top surface of the support frame. The output ends of the multiple second telescopic cylinders are fixedly connected to the bottom surface of the mounting plate. The mounting plate is provided with multiple bolt holes for bolt connection with a scaled-down building steel structure.

[0006] Furthermore, there are four reaction frames, which are arranged in pairs facing each other, and each reaction frame is fixed with a first telescopic cylinder.

[0007] Furthermore, there are six second telescopic cylinders, which are evenly distributed on the top surface of the support frame.

[0008] Furthermore, both the first telescopic cylinder and the second telescopic cylinder are servo electric cylinders.

[0009] Furthermore, the top surface of the workbench is fixedly provided with two slide rails at intervals, the two slide rails are parallel in axis, and the bottom surface of the support frame is fixedly provided with two sliders, the two sliders being slidably connected to the two slide rails respectively.

[0010] Furthermore, the support frame is a rectangular frame assembled from multiple square steel bars.

[0011] Furthermore, sleeves are fixed at the four corners of the top surface of the support frame, and a sliding rod is fixed on the bottom surface of the mounting plate corresponding to each sleeve, with each sliding rod slidingly passing through the corresponding sleeve.

[0012] Compared with the prior art, the beneficial effects of the low-cycle fatigue testing device for building steel structures provided in this application are: 1. By using the first telescopic cylinders located on both sides of the workbench to drive the support frame to make horizontal reciprocating motion, and multiple second telescopic cylinders to drive the mounting plate and scaled-down building steel structure to make up-down reciprocating motion, the simulation of multi-dimensional composite loads is realized, which is closer to the stress condition of steel structure under complex load conditions in actual engineering. The bolt connection between the mounting plate and the scaled-down building steel structure is made through bolt holes, which highly simulates the anchor bolt connection method of building steel structure in actual engineering, and can more realistically reflect the stress behavior and low-cycle fatigue performance of steel structure under actual connection conditions. 2. The first telescopic cylinders on the two opposing reaction frames work together to apply a horizontal force to the support frame, which enhances the stability and uniformity of the horizontal loading, makes the support frame more balanced in force during horizontal movement, reduces test errors caused by uneven force, and improves the accuracy and reliability of the test. 3. The six evenly distributed second telescopic cylinders can apply vertical force more uniformly, keeping the mounting plate stable during its up-and-down movement. This prevents the mounting plate from tilting or deforming due to excessive or insufficient localized force, thus ensuring the uniformity of vertical force on the scaled-down steel structure and improving the accuracy of test results. Furthermore, the cooperation between the sliding rod and the sleeve restricts the horizontal displacement of the mounting plate, providing guidance for its up-and-down movement and further improving the accuracy of vertical loading. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a perspective view of a low-cycle fatigue testing device for building steel structures according to the present invention; Figure 2 This is a side view of a low-cycle fatigue testing device for building steel structures according to the present invention.

[0015] Explanation of reference numerals in the attached figures: 1. Workbench; 11. Slide rail; 2. Support frame; 21. Slider; 3. Reaction frame; 4. Mounting plate; 41. Bolt hole; 5. First telescopic cylinder; 6. Second telescopic cylinder; 7. Sleeve; 8. Slide rod. Detailed Implementation

[0016] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0017] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0018] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0019] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" or "several" means two or more, unless otherwise explicitly specified.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0021] Please refer to the following: Figures 1 to 2 As shown, the following describes a low-cycle fatigue testing device for building steel structures provided in an embodiment of this application. This utility model's low-cycle fatigue testing device for building steel structures includes a workbench 1, a support frame 2, a reaction frame 3, a mounting plate 4, a first telescopic cylinder 5, and a second telescopic cylinder 6. The support frame 2 is slidably mounted on the workbench 1. Specifically, two slide rails 11 are fixedly mounted at intervals on the top surface of the workbench 1, and the two slide rails 11 are parallel in axis. Two sliders 21 are fixedly mounted on the bottom surface of the support frame 2, and the two sliders 21 are slidably connected to the two slide rails 11 respectively. Thus, the sliding connection between the support frame 2 and the workbench 1 is achieved through the cooperation of the sliders 21 and the slide rails 11, providing stable guidance for the horizontal movement of the support frame 2.

[0022] Preferably, the support frame 2 is a rectangular frame assembled from multiple square steel bars. It should be noted that the rectangular frame structure assembled from multiple square steel bars has high strength and rigidity, can withstand large loads, and is simple in structure, easy to manufacture and install. This structural form ensures the stability of the device while reducing manufacturing costs and improving the cost-effectiveness of the device.

[0023] At least two reaction frames 3 are fixedly mounted on both sides of the workbench 1 in the sliding direction of the support frame 2. Each reaction frame 3 is fixedly equipped with a horizontally positioned first telescopic cylinder 5, and the output end of each first telescopic cylinder 5 is fixedly connected to the support frame 2. The first telescopic cylinders 5 located on both sides of the workbench 1 work together to drive the support frame 2 to perform horizontal reciprocating motion on the workbench 1 in the sliding direction, simulating a horizontal load.

[0024] In this embodiment, there are four reaction frames 3, which are arranged in pairs facing each other. Each reaction frame 3 is fixed with a first telescopic cylinder 5. During the test, the first telescopic cylinders 5 on the two opposing reaction frames 3 work together to apply a horizontal force to the support frame 2, so that the support frame 2 is more balanced in force during horizontal movement, reducing test errors caused by uneven force and improving the accuracy and reliability of the test.

[0025] It should be noted that the two first telescopic cylinders 5 are arranged coaxially opposite each other. During implementation, the first telescopic cylinder 5 on one side extends (to push the support frame 2), while the first telescopic cylinder 5 on the other side retracts (to pull the support frame 2). The driving forces of the two first telescopic cylinders 5 are equal in magnitude and opposite in direction. This effectively avoids uneven loading of the specimen. Through the coordinated driving of the first telescopic cylinders 5 on both sides, the equivalent loading stiffness is twice that of a single cylinder. During loading, the elastic deformation of the support frame 2 and the first telescopic cylinder 5 is significantly suppressed. Under high loads (such as stress amplitude close to the material yield strength), loading accuracy can still be maintained, avoiding the problem of "sufficient force but insufficient stress". In addition, by arranging the two first telescopic cylinders 5 coaxially opposite each other, when using position synchronization or force synchronization algorithms to control the extension and retraction of the first telescopic cylinders 5, it can be ensured that the extension and retraction displacement and output force of the two cylinders are perfectly matched.

[0026] Mounting plate 4 is positioned above support frame 2 to support the scaled-down building steel structure. Multiple second telescopic cylinders 6 (six in this embodiment) are evenly distributed on the top surface of support frame 2, with the output end of each cylinder fixedly connected to the bottom surface of mounting plate 4. During testing, the multiple cylinders 6 are activated synchronously to drive mounting plate 4 and the scaled-down building steel structure connected to it in a reciprocating up-and-down motion, simulating vertical loads. By using six evenly distributed cylinders 6, the vertical force can be applied more evenly, ensuring the mounting plate 4 remains stable during its up-and-down movement. This prevents tilting or deformation of mounting plate 4 due to excessive or insufficient localized force, thus guaranteeing the uniformity of vertical force on the scaled-down building steel structure and improving the accuracy of the test results.

[0027] In this embodiment, the mounting plate 4 is provided with multiple bolt holes 41 for bolt connection with the scaled-down building steel structure. During implementation, the scaled-down building steel structure specimen is placed at a suitable position on the mounting plate 4. Then, bolts are sequentially passed through the pre-set connection holes on the scaled-down building steel structure and the corresponding bolt holes 41 on the mounting plate 4. By tightening the nuts, the scaled-down building steel structure is firmly fixed to the mounting plate 4 to simulate an anchor connection. In subsequent tests, when the first telescopic cylinder 5 drives the support frame 2 to perform horizontal reciprocating motion, and the second telescopic cylinder 6 drives the mounting plate 4 to perform vertical reciprocating motion, the scaled-down building steel structure can move together with the mounting plate 4, thereby accepting the action of multi-dimensional composite loads, simulating the stress condition of steel structures under complex load conditions in actual engineering, and completing the low-cycle fatigue test.

[0028] It should be noted that in actual building structures, anchor bolt connections are a crucial link between the steel structure and the foundation, and their quality directly affects the stability and safety of the structure. Bolting the scaled-down steel structure through bolt holes 41 can highly simulate the anchor bolt connections in actual engineering projects. Therefore, it can more realistically reflect the stress behavior and low-cycle fatigue performance of the steel structure under actual connection conditions, making the test results more meaningful in practical engineering applications. Furthermore, by setting multiple bolt holes, it can accommodate scaled-down steel structures of different sizes to a certain extent.

[0029] In this embodiment, both the first telescopic cylinder 5 and the second telescopic cylinder 6 are servo electric cylinders. During the test, the controller drives the support frame 2 and the mounting plate 4 to perform corresponding reciprocating movements according to preset cycle number, vibration frequency, and amplitude parameters. By using servo electric cylinders, the number of loading cycles, vibration frequency, and amplitude can be controlled more precisely, meeting the requirements of high-precision fatigue testing and overcoming the shortcomings of traditional hydraulic systems, which are affected by factors such as oil temperature changes and leakage, as well as the inertial lag problem of mechanical devices.

[0030] Preferably, sleeves 7 are fixed at the four corners of the top surface of the support frame 2, and sliding rods 8 are fixed on the bottom surface of the mounting plate 4 corresponding to each sleeve 7. Each sliding rod 8 slides through the corresponding sleeve 7. When the second telescopic cylinder 6 drives the mounting plate 4 to move up and down reciprocatingly, the sliding rods 8 slide within the sleeves 7, restricting the horizontal displacement of the mounting plate 4 and ensuring that the mounting plate 4 can only make stable reciprocating motion in the vertical direction. This provides guidance for the up and down movement of the mounting plate 4, improves the accuracy of vertical loading, and ensures the accuracy and reliability of the test.

[0031] In a specific implementation of this utility model, the scaled-down building steel structure specimen is placed at a suitable position on the mounting plate 4, and bolts are used to firmly fix the scaled-down building steel structure on the mounting plate 4, thereby simulating the anchor connection in actual engineering.

[0032] Then, the first telescopic cylinder 5 is activated. The first telescopic cylinder 5 on one side extends to push the support frame 2, while the first telescopic cylinder 5 on the other side retracts to pull the support frame 2. The driving forces of the two first telescopic cylinders 5 are equal in magnitude and opposite in direction, so as to jointly drive the support frame 2 to make horizontal reciprocating motion along the sliding direction on the workbench 1, thereby causing the support frame 2 to drive the mounting plate 4 and the scaled-down building steel structure to make horizontal reciprocating motion, simulating the horizontal load.

[0033] According to the test requirements, six second telescopic cylinders 6 are activated, driving the mounting plate 4 and the scaled-down building steel structure connected to it to reciprocate up and down, simulating vertical load. At the same time, when the second telescopic cylinders 6 drive the mounting plate 4 to reciprocate up and down, the sliding rod 8 slides in the sleeve 7, restricting the horizontal displacement of the mounting plate 4, so that the mounting plate 4 can only make stable reciprocating motion in the vertical direction.

[0034] It should be noted that during the test, the servo electric cylinder was driven to perform corresponding reciprocating motions on the support frame and mounting plate by a controller (such as a PLC controller in the prior art) according to the preset number of cycles, vibration frequency and amplitude parameters. The scaled-down building steel structure moved together with the mounting plate and was subjected to multi-dimensional composite loads, simulating the stress situation of steel structures under complex load conditions in actual engineering, and completing the low-cycle fatigue test.

[0035] It is understood that the parts in the above embodiments can be freely combined or deleted to form different combined embodiments. The specific contents of each combined embodiment will not be repeated here. After this description, it can be considered that the present utility model specification has recorded each combined embodiment and can support different combined embodiments.

[0036] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A low-cycle fatigue testing device for building steel structures, characterized in that, include: The system includes a workbench, a support frame slidably mounted on the workbench, and a mounting plate mounted above the support frame. Reaction frames are fixed to both sides of the workbench on either side of the support frame in the sliding direction. Each reaction frame is fixedly equipped with a horizontally mounted first telescopic cylinder. The output end of each first telescopic cylinder is fixedly connected to the support frame. Multiple second telescopic cylinders are vertically fixed to the top surface of the support frame. The output ends of the multiple second telescopic cylinders are fixedly connected to the bottom surface of the mounting plate. The mounting plate has multiple bolt holes for bolt connection with a scaled-down building steel structure.

2. The low-cycle fatigue testing device for building steel structures according to claim 1, characterized in that, There are four reaction frames, which are arranged in pairs facing each other, and each reaction frame is fixed with a first telescopic cylinder.

3. The low-cycle fatigue testing device for building steel structures according to claim 1, characterized in that, There are six second telescopic cylinders, which are evenly distributed on the top surface of the support frame.

4. The low-cycle fatigue testing device for building steel structures according to claim 1, characterized in that, Both the first telescopic cylinder and the second telescopic cylinder are servo electric cylinders.

5. The low-cycle fatigue testing device for building steel structures according to claim 1, characterized in that, The top surface of the workbench is fixedly provided with two slide rails at intervals, and the two slide rails are parallel in axis. The bottom surface of the support frame is fixedly provided with two sliders, and the two sliders are slidably connected to the two slide rails respectively.

6. The low-cycle fatigue testing device for building steel structures according to claim 1, characterized in that, The support frame is a rectangular frame assembled from multiple square steel bars.

7. The low-cycle fatigue testing device for building steel structures according to claim 1, characterized in that, Sleeves are fixed at the four corners of the top surface of the support frame, and a sliding rod is fixed on the bottom surface of the mounting plate corresponding to each sleeve. Each sliding rod slides through the corresponding sleeve.

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