Truss tower node fatigue loading experiment device and method

Abstract

The present application relates to the technical field of wind power and discloses a truss tower node fatigue loading experiment device and method, the truss tower node fatigue loading experiment device includes base, column assembly, flange assembly, crossbeam and actuator, column assembly includes first column and second column that are arranged at intervals on base, flange assembly includes first flange connected with first column and second flange connected with second column, first flange and second flange are used to connect the two ends of the main pipe of test piece respectively, crossbeam is arranged between first column and second column, the height of crossbeam is adjustable, the number of actuator is same with the number of branch pipe of test piece and one-to-one correspondence, one end of actuator is connected with crossbeam, the other end of actuator is used to connect the free end of branch pipe of test piece, and actuator can be telescopic along the direction coinciding with the axis of branch pipe.The truss tower node fatigue loading experiment device of the embodiment of the present application can be adapted to different shapes of node, is convenient and fast to connect and is stable in connection.

Description

Technical Field

[0001] This invention belongs to the field of wind power technology, specifically relating to a fatigue loading test device and method for truss tower nodes. Background Technology

[0002] Currently, most fatigue loading test apparatuses for truss tower joints are designed for specific joint types (such as T-type and K-type). While these specialized apparatuses are relatively simple in structure, they lack versatility and are difficult to apply to other joint types. In contrast, more versatile test apparatuses often have complex structures, require more components, and are cumbersome to assemble and debug. To date, a fatigue loading test apparatus that guarantees both good versatility and a simple, easy-to-operate structure is still lacking. Furthermore, the connection between the joint and the loading device in existing apparatuses often lacks sufficient strength, making them prone to slippage or deformation under repeated loading, affecting the accuracy and reliability of experimental data. Summary of the Invention

[0003] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of this invention provide a fatigue loading test apparatus for truss tower nodes, which is adaptable to nodes of different shapes, facilitating rapid and stable connection.

[0004] This invention also proposes a fatigue loading test method for truss tower nodes, which can accurately perform load fatigue tests on various types of nodes and ensure the accuracy of experimental data.

[0005] The fatigue loading test device for truss tower nodes according to an embodiment of the present invention includes a base, a column assembly, a flange assembly, a crossbeam, and actuators. The column assembly includes a first column and a second column disposed on the base. The first column and the second column are parallel and spaced apart, and the distance between them is adjustable. The flange assembly includes a first flange connected to the first column and a second flange connected to the second column. The first flange and the second flange are used to connect the two ends of the main pipe of the test specimen, respectively. The crossbeam is disposed between the first column and the second column, and the height of the crossbeam is adjustable. The number of actuators is the same as the number of branch pipes of the test specimen and corresponds one-to-one. One end of the actuator is connected to the crossbeam, and the other end of the actuator is used to connect to the free end of the branch pipe of the test specimen. The actuator can extend and retract in a direction coinciding with the axis of the branch pipe.

[0006] The truss tower node fatigue loading test device of this invention, through adjustable spacing double columns, adjustable height crossbeams, and actuators that correspond one-to-one with the branch pipes and are arranged coaxially, can be adapted to node specimens of different specifications and different numbers of branch pipes. It does not require replacement of the main structure, simplifies the device architecture, ensures accurate load transfer, and improves the versatility and stability of the test.

[0007] In some embodiments, the two ends of the main pipe are respectively equipped with docking flanges, and both the first flange and the second flange are connected to the corresponding docking flanges by multiple anchor bolts.

[0008] In some embodiments, the bottom of the first column and the second column are respectively provided with connecting plates. The connecting plates can be slidably adjusted along the base in the direction of the main pipe axis. The connecting plates are provided with first connecting holes. The base is provided with multiple sets of second connecting holes arranged along the direction of the main pipe axis. The first connecting holes and the corresponding second connecting holes are fastened together by bolts.

[0009] In some embodiments, the column assembly further includes a cross brace, the first flange being connected to the first column via the cross brace, and the second flange being connected to the second column via the cross brace.

[0010] In some embodiments, the crossbeam is located above the flange assembly, the crossbeam is parallel to the upper end face of the base, and both ends of the crossbeam are connected to the first column and the second column of the column assembly respectively through a first connector.

[0011] In some embodiments, both the first column and the second column are provided with a plurality of bolt holes spaced apart along the height direction, and the first connector is engaged with the corresponding bolt holes by bolts to adjust the height of the crossbeam.

[0012] In some embodiments, both the first column and the second column are provided with slide rails along the height direction, and the first connector cooperates with the first column and the second column through the slide rails to adjust the height of the crossbeam.

[0013] In some embodiments, a second connector is installed on the crossbeam, the number of the second connectors being the same as the number of actuators and corresponding one-to-one. The installation position of the second connector can be adjusted along the length direction of the crossbeam. One end of the actuator is connected to the second connector, and the other end of the actuator is connected to the free end of the branch pipe through a flange.

[0014] In some embodiments, when the specimen is a T-shaped node, there is one actuator, and the extension and retraction direction of the actuator is perpendicular to the main tube.

[0015] In some embodiments, when the specimen is a K-type node, there are two actuators, one end of which is hinged to the second connector.

[0016] The truss tower node fatigue loading test device of this invention achieves rapid and stable assembly of various nodes through a flexibly adjustable main structure, standardized flange connection and precise preload control, taking into account both versatility and structural simplicity, ensuring that the test energy is accurately applied to the node area, and significantly improving the reliability and economy of the test.

[0017] The fatigue loading test method for truss tower nodes according to this invention is implemented by the fatigue loading test apparatus for truss tower nodes described in any of the above embodiments, and includes the following steps:

[0018] S1. Select anchor bolts with preset yield loads, and determine the preload of a single anchor bolt and the number of anchor bolts to be used; S2. Install the test specimen, adjust the distance between the first column and the second column, and fasten the butt flange at one end of the main pipe of the test specimen to the first flange with the number of anchors used and the pre-tightening force. Fasten the butt flange at the other end of the main pipe to the second flange with the number of anchors used and the pre-tightening force. Adjust the height of the crossbeam, connect one end of the actuator to the crossbeam, and connect the free end of the branch pipe to the other end of the actuator. S3. Activate the actuator and use the extension and retraction of the actuator to conduct a fatigue loading test on the specimen until the test is completed.

[0019] The fatigue loading test method for truss tower nodes in this invention addresses the pain points of large load loss and insufficient data authenticity in existing test connection parts. Relying on a highly adaptable device, through precise design of anchor bolt parameters and preload, and standardized installation and loading procedures, it ensures that the flange connection does not slip and that all test energy is applied to the core area of ​​the node, thus significantly improving the reliability of fatigue test data and implementation efficiency. Attached Figure Description

[0020] Figure 1 This is an overall schematic diagram of the fatigue loading test device (T-shaped node) for truss tower nodes according to an embodiment of the present invention.

[0021] Figure 2 This is a structural schematic diagram of the fatigue loading test device (K-type node) for truss tower nodes according to an embodiment of the present invention.

[0022] Figure 3 yes Figure 1 The right view.

[0023] Figure 4 This is an enlarged view of the flange assembly.

[0024] Figure 5 This is a flowchart of the calculation process for anchor bolt selection.

[0025] Figure label: 1. Base; 2. Column assembly; 21. First column; 22. Second column; 23. Cross brace; 3. Flange assembly; 31. First flange; 32. Second flange; 4. Crossbeam; 5. Actuator; 6. Connecting flange; 7. Anchor bolt; 8. Connecting plate; 9. First connecting piece; 10. Second connecting piece. Detailed Implementation

[0026] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0027] like Figures 1-5 As shown, the fatigue loading test device for truss tower nodes according to an embodiment of the present invention includes a base 1, a column assembly 2, a flange assembly 3, a crossbeam 4, and actuators 5. The column assembly 2 includes a first column 21 and a second column 22 disposed on the base 1. The first column 21 and the second column 22 are parallel and spaced apart, and the spacing between them is adjustable. The flange assembly 3 includes a first flange 31 connected to the first column 21 and a second flange 32 connected to the second column 22. The first flange 31 and the second flange 32 are used to connect the two ends of the main pipe of the test specimen, respectively. The crossbeam 4 is disposed between the first column 21 and the second column 22. The height of the crossbeam 4 is adjustable. The number of actuators 5 is the same as the number of branch pipes of the test specimen and corresponds one-to-one. One end of the actuator 5 is connected to the crossbeam 4, and the other end of the actuator 5 is used to connect to the free end of the branch pipe of the test specimen. The actuator 5 can extend and retract in a direction coinciding with the axis of the branch pipe.

[0028] The truss tower node fatigue loading test device provided in this embodiment effectively solves the problems of poor versatility and complicated structure of existing truss tower node fatigue loading devices. It can be adapted to truss tower node specimens with different main pipe lengths, different number and types of branch pipes, and can complete fatigue loading tests of multiple types of nodes without changing the main structure of the device. At the same time, it can ensure that the loading direction is completely coincident with the branch pipe axis.

[0029] The fatigue loading test device for truss tower nodes is equipped with a base 1, which serves as the load-bearing foundation for the entire device. It can be fixedly installed on the rigid ground or reaction ground of the test site, providing stable installation support and test reaction foundation for the other components.

[0030] The column assembly 2 includes a first column 21 and a second column 22. Both the first column 21 and the second column 22 are mounted on the base 1. They are arranged in parallel intervals. The interval between them can be flexibly adjusted according to the main pipe length of the test specimen. It can adapt to truss tower node specimens of different specifications and sizes without disassembling or replacing the main frame of the device.

[0031] The flange assembly 3 includes a first flange 31 and a second flange 32. The first flange 31 is connected to the first column 21, and the second flange 32 is connected to the second column 22. The first flange 31 and the second flange 32 are respectively used to connect to the two ends of the main body of the test specimen, so as to realize the rigid fixation of the main body of the test specimen on the device, provide stable end constraints for the nodal fatigue test, and avoid the unexpected slippage of the main body during the test.

[0032] The crossbeam 4 is installed between the first column 21 and the second column 22. The installation height of the crossbeam 4 can be flexibly adjusted according to the setting height and inclination angle of the test specimen support pipe, providing a suitable installation position and a stable reaction support structure for the subsequent installation of the actuator 5.

[0033] The number of actuators 5 is the same as the number of branches of the specimen, and each actuator 5 is arranged in a one-to-one correspondence with each branch. One end of the actuator 5 is connected to the crossbeam 4, and the other end of the actuator 5 is used to connect to the free end of the branch of the specimen. The actuator 5 can perform telescopic movement in a direction that is completely coincident with the axis of the corresponding branch.

[0034] When conducting fatigue loading tests, first adjust the interval between the first column 21 and the second column 22 according to the length of the main pipe of the specimen. Then, fix both ends of the main pipe of the specimen to the first column 21 and the second column 22 respectively through the flange assembly 3. Next, adjust the installation height of the crossbeam 4 according to the parameters of the branch pipe of the specimen. Then, connect each actuator 5 to the crossbeam 4 and the free end of the corresponding branch pipe respectively. After starting the actuator 5, the actuator 5 outputs cyclic fatigue load along the axis of the branch pipe to complete the fatigue loading test of the truss tower node.

[0035] In some embodiments, the two ends of the main pipe are respectively equipped with docking flanges 6, and the first flange 31 and the second flange 32 are both connected to the corresponding docking flanges 6 by a plurality of anchor bolts 7.

[0036] This embodiment optimizes the docking structure between the specimen and the device, effectively solving the problems of load loss and slippage deformation that easily occur at the connection points between nodes and devices in existing test devices. It can achieve a high-precision rigid connection between the main pipe and the flange assembly 3, ensuring stable transmission of the test load path.

[0037] Both ends of the main body of the test specimen are fixedly fitted with mating flanges 6, which are welded to the ends of the main body to ensure coaxiality between them. A first flange 31 is fitted to the mating flange 6 at one end of the main body, and a second flange 32 is fitted to the mating flange 6 at the other end of the main body. Both the first flange 31 and the second flange 32 are fastened to their respective mating flanges 6 using multiple anchor bolts 7. High-strength anchor bolts 7 can be used. By applying a calibrated preload, the mating flange surfaces can be ensured to be in tight contact, using inter-surface friction to transfer loads, reducing the shear force borne by the anchor bolts 7 themselves, and preventing unexpected slippage or deformation at the connection point during the test.

[0038] In some specific embodiments, multiple sets of standardized anchoring holes are arranged on the discs of the first flange 31 and the second flange 32 according to the main pipe connection parameters of commonly used truss tower nodes in engineering. The diameter and position distribution of each set of anchoring holes match the installation dimensions of the main pipe connecting flanges 6 of different specifications. Without replacing the flange body, it is possible to quickly adapt to main pipe specimens with different pipe diameters and different bolt hole arrangements, so as to achieve a stable connection between the main pipe and the device.

[0039] In some embodiments, the bottom of the first column 21 and the second column 22 are respectively provided with connecting plates 8. The connecting plates 8 can be slidably adjusted along the base 1 in the direction of the main pipe axis. The connecting plates 8 are provided with first connecting holes. The base 1 is provided with multiple sets of second connecting holes arranged along the direction of the main pipe axis. The first connecting holes and the corresponding second connecting holes are fastened together by bolts.

[0040] In some embodiments, the column assembly 2 further includes a cross brace 23, the first flange 31 is connected to the first column 21 via the cross brace 23, and the second flange 32 is connected to the second column 22 via the cross brace 23.

[0041] This embodiment achieves flexible adjustment and reliable locking of column spacing, can quickly adapt to main pipe specimens of different lengths, greatly improves the universal adaptability of the device, and also enhances the load transfer path between the specimen and column assembly 2. The overall structure is simple, and the disassembly and adjustment operation is convenient. There is no need to add complex auxiliary components, which takes into account both the universality and structural stability of the device.

[0042] Connecting plates 8 are respectively installed at the bottom of the first column 21 and the second column 22. The connecting plates 8 are fixed to the bottom of the corresponding columns as a whole to ensure connection strength and structural integrity. The connecting plates 8 can slide and adjust along the axis of the main pipe along the base 1, thereby changing the interval between the first column 21 and the second column 22 to accommodate main pipe specimens of different lengths. A first connecting hole is opened on the connecting plate 8, and multiple sets of second connecting holes are opened on the base 1 along the axis of the main pipe. When the column slides to the target spacing position matching the length of the main pipe, the first connecting hole is precisely aligned with the corresponding second connecting hole, and bolts are inserted into the aligned connecting holes and tightened to achieve rigid fixation of the column on the base 1. This ensures that the column will not slip during the entire test and provides a stable reaction force support foundation for the fatigue loading test. To facilitate accurate sliding of the connecting plate 8, a slide rail can also be installed between the connecting plate 8 and the base 1.

[0043] The column assembly 2 is also equipped with a cross brace 23, which is made of rigid load-bearing profile. The first flange 31 is fixedly connected to the first column 21 through the cross brace 23, and the second flange 32 is fixedly connected to the second column 22 through the cross brace 23. One end of the cross brace 23 is fixedly connected to the side wall of the corresponding column, and the other end is fixedly connected to the back of the corresponding flange, which can evenly and stably transfer the test load borne by the flange to the column body.

[0044] In some embodiments, the crossbeam 4 is located above the flange assembly 3, the crossbeam 4 is parallel to the upper end face of the base 1, and both ends of the crossbeam 4 are connected to the first column 21 and the second column 22 of the column assembly 2 respectively through the first connector 9.

[0045] In some embodiments, the first column 21 and the second column 22 are provided with a plurality of bolt holes spaced apart along the height direction. The first connector 9 is engaged with the corresponding bolt holes by bolts to adjust the height of the crossbeam 4.

[0046] In some embodiments, both the first column 21 and the second column 22 are provided with slide rails along the height direction, and the first connector 9 cooperates with the first column 21 and the second column 22 through the slide rails to adjust the height of the crossbeam 4.

[0047] In some embodiments, a second connector 10 is installed on the crossbeam 4. The number of second connectors 10 is the same as the number of actuators 5 and they correspond one-to-one. The installation position of the second connector 10 can be adjusted along the length direction of the crossbeam 4. One end of the actuator 5 is connected to the second connector 10, and the other end of the actuator 5 is connected to the free end of the branch pipe through a flange.

[0048] This embodiment realizes the installation and height adjustment of the crossbeam 4, effectively solving the problems of poor adaptability of the crossbeam 4 in existing test devices and the inability to flexibly match different branch pipe parameters. It can realize multi-level precise adjustment of the installation height of the crossbeam 4, and at the same time, it can flexibly adjust the installation position of the actuator 5 along the length of the crossbeam 4, adapting to various truss tower node specimens such as T-type and K-type with different branch pipe heights, inclination angles, and lateral spacings. There is no need to replace the main body of the crossbeam 4 or to process additional installation holes, which greatly improves the universal adaptability of the device.

[0049] The crossbeam 4 is positioned above the flange assembly 3. The extension direction of the crossbeam 4 is parallel to the upper end face of the base 1. The two ends of the crossbeam 4 are respectively connected to the first column 21 and the second column 22 through the first connector 9 to form a stable portal frame, providing rigid reaction support for the actuator 5, ensuring that the crossbeam 4 will not bend or displace during fatigue loading, and ensuring the stability of the load output.

[0050] Multiple bolt holes are spaced along the height of both the first column 21 and the second column 22. The bolt holes on the same column have the same diameter and uniform spacing, forming standardized height adjustment positions. When adjusting the height of the crossbeam 4, align the first connecting piece 9 with the corresponding bolt hole on the column, insert bolts into the first connecting piece 9 and the corresponding bolt hole, and tighten them to lock the crossbeam 4 at the target installation height. This can be flexibly adjusted according to the setting height and inclination angle of the test specimen support pipe, ensuring that the installation space and axis angle of the actuator 5 perfectly match the design parameters of the support pipe. The first connecting piece 9 can be fitted with clamps, connecting plates 8, etc., as needed.

[0051] Alternatively, both the first column 21 and the second column 22 are equipped with slide rails along the height direction. The first connecting member 9 is a slider that cooperates with the slide rail or another slide rail. The height of the crossbeam 4 can be adjusted by moving the first connecting member 10 along the slide rail. At the same time, a locking structure, such as a clamping bolt, is also provided on the first connecting member 9 to lock the relative position of the first connecting member 9 and the slide rail, thereby locking the height of the crossbeam.

[0052] A second connector 10 is installed on the crossbeam 4. The number of second connectors 10 is the same as the number of actuators 5, and each second connector 10 corresponds to each actuator 5. The installation position of the second connector 10 can be adjusted along the length of the crossbeam 4 to adapt to the lateral spacing and axial position of different branch pipes. After adjustment, it can be rigidly locked with the crossbeam 4. One end of the actuator 5 is connected to the second connector 10, and the other end of the actuator 5 is connected to the free end of the branch pipe through a flange, ensuring that the extension axis of the actuator 5 is completely coincident with the axis of the branch pipe, ensuring that the cyclic fatigue load can be accurately and losslessly transferred to the core test area of ​​the node. The second connector 10 can be a sleeve and bolt fit, or a slider and bolt fit, etc.

[0053] In some embodiments, when the specimen is a T-shaped node, there is one actuator 5, and the extension and retraction direction of the actuator 5 is set perpendicular to the main pipe.

[0054] In some embodiments, when the specimen is a K-type node, there are two actuators 5, one end of which is hinged to the second connector 10.

[0055] This embodiment optimizes the configuration and connection method of actuator 5 for the T-type and K-type truss tower nodes most widely used in engineering, solving the problem that the existing device can only adapt to a single node type. It can accurately match the stress characteristics and loading requirements of the two types of nodes, and can complete the fatigue performance test of the two mainstream nodes without changing the main structure of the device.

[0056] When the specimen is a T-shaped node, only one branch pipe is set on the specimen, and the axis of the branch pipe intersects the axis of the main pipe perpendicularly. A corresponding actuator 5 is configured. The extension and retraction direction of the actuator 5 is set perpendicular to the main pipe and completely coincides with the axis of the branch pipe. It can output cyclic fatigue load along the axis of the branch pipe, accurately simulating the reciprocating force condition perpendicular to the main pipe that the T-shaped node is subjected to in actual engineering.

[0057] When the specimen is a K-type node, two branch pipes arranged at a preset inclination angle are installed on the specimen, and two actuators 5 are configured accordingly. One end of each actuator 5 is hinged to the second connecting piece 10 at the corresponding position. The hinged structure can adapt to the installation inclination angle of the branch pipe and flexibly adjust the loading angle of the actuator 5 to ensure that the extension axis of the actuator 5 is always completely coincident with the axis of the corresponding branch pipe. The preset cyclic fatigue load can be applied to the two branch pipes simultaneously, accurately reproducing the bidirectional oblique stress condition of the K-type node in the truss tower structure, avoiding the additional stress caused by the inclination angle constraint, and ensuring that the fatigue load is accurately applied to the core test area of ​​the node.

[0058] Throughout the experiment, structural design and parameter control ensured that the load was transmitted along an ideal path. The ideal load transmission path was sequentially transmitted through actuator 5, branch pipe, node core area, main pipe, flange assembly 3, column assembly 2, and base 1, ensuring that the node core area was the only controllable fatigue weak point in the entire load transmission path. During the experiment, all plastic deformation, crack initiation, and propagation occurred in the node core area. Unexpected deformation or fatigue damage did not occur in the main body of the device, flange connections, or non-node areas of the main pipe. This fundamentally ensured that all the energy input to the experiment was used for the fatigue performance testing of the nodes, completely eliminating the interference of energy loss in non-node areas on the test results.

[0059] The following describes a fatigue loading test method for a truss tower node according to an embodiment of the present invention, implemented using the fatigue loading test apparatus for a truss tower node as described in any of the above embodiments, and includes the following steps: S1. Select anchor bolts 7 with preset yield loads, and determine the preload of a single anchor bolt 7 and the number of anchor bolts 7 to be used; S2. Install the test specimen, adjust the distance between the first column 21 and the second column 22, and fasten the butt flange 6 at one end of the main pipe of the test specimen to the first flange 31 with a number of anchor bolts 7 with a pre-tightening force. Fasten the butt flange 6 at the other end of the main pipe to the second flange 32 with a number of anchor bolts 7 with a pre-tightening force. Adjust the height of the crossbeam 4, connect one end of the actuator 5 to the crossbeam 4, and connect the free end of the branch pipe to the other end of the actuator 5. S3. Start actuator 5 and use the extension and retraction of actuator 5 to conduct fatigue loading test on the specimen until the test ends.

[0060] The fatigue loading test method for truss tower nodes provided in this embodiment effectively solves the problems of poor versatility, large load transfer loss, and insufficient accuracy of test data in existing node fatigue test methods. It can be adapted to the fatigue test requirements of mainstream truss tower nodes such as T-type and K-type with different main pipe lengths and branch pipe types. By precisely applying the preload of anchor bolts 7, it ensures that there is no slippage or plastic deformation at the flange connection throughout the test, and all the input test energy is precisely applied to the core test area of ​​the node, fundamentally guaranteeing the authenticity and reliability of fatigue test data. At the same time, it greatly simplifies the test switching process for nodes of different specifications and reduces the time and economic cost of test implementation.

[0061] First step, see appendix Figure 4 First, the parameters of anchor bolt 7 were designed and determined. Based on the maximum test load of the fatigue test design for the target specimen, combined with the flange surface friction coefficient and the preset safety factor, the number of anchor bolts 7 to be used was calculated and determined. High-strength anchor bolts 7 with corresponding preset yield loads were selected, and the target value of the preload of a single anchor bolt 7 was calculated. The bearing capacity of the anchor bolt 7 was then checked to ensure that the anchor bolt 7 remained in an elastic working state under the maximum test load, avoiding plastic deformation or connection failure of the anchor bolt 7 during the test. The detailed calculation method is as follows.

[0062]

[0063]

[0064] In the formula: —Number of anchor bolts used; —Flange surface friction coefficient; —Preload of a single anchor bolt; —Maximum test load; —Safety factor; —Safety factor; — Yield load of a single anchor bolt.

[0065] After the formula calculation is satisfied, a torque wrench is used to apply the preload. The number of anchor bolts can be calculated and tested sequentially from small to large until the formula requirement is met. Through the above design selection, when the force is transmitted to the anchor bolts, the anchor bolts will not loosen, and stable contact will be maintained between the butt flange and the first flange, as well as between the butt flange and the second flange.

[0066] The second step is to complete the installation and debugging of the specimen and experimental apparatus. First, adjust the distance between the first column 21 and the second column 22 according to the length of the main pipe of the specimen. After the distance is appropriate, the columns are rigidly fixed on the base 1. Then, align the butt flange 6 at one end of the main pipe of the specimen with the first flange 31. Use the number of anchor bolts 7 determined in the first step and the calculated preload to complete the fastening connection. Simultaneously, fasten the butt flange 6 at the other end of the main pipe with the second flange 32 using anchor bolts 7 of the same specification and the same preload, ensuring that the flange surfaces on both sides are fully and tightly fitted, so that the load is transferred through inter-surface friction and the shear force borne by the anchor bolts 7 is reduced. Then, adjust the installation height of the crossbeam 4 according to the setting height and inclination angle of the branch pipe of the specimen and lock it. Connect one end of the actuator 5 corresponding to the number of branch pipes to the crossbeam 4, and connect the free end of the branch pipe to the other end of the actuator 5. Adjust the installation posture of the actuator 5 to ensure that the extension and retraction direction of the actuator 5 is completely coincident with the axis of the corresponding branch pipe, so as to eliminate the interference of additional bending moment on the test results.

[0067] The third step is to conduct fatigue loading tests. After all installation, commissioning, and pre-inspection are completed, actuator 5 is started. According to the preset fatigue loading regime, cyclic fatigue loads are applied to the specimen branch pipe through the axial extension and retraction of actuator 5. The deformation, stress distribution, and crack initiation and propagation in the core area of ​​the node are continuously monitored until the preset number of cycles is reached, or the node shows fatigue failure and the test termination condition is met. At this point, loading is stopped, and the fatigue loading test of the entire truss tower node is completed.

[0068] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to 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 invention.

[0069] 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 at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0070] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0071] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0072] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0073] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.

Claims

1. A fatigue loading test apparatus for truss tower nodes, characterized in that, include: Base; The column assembly includes a first column and a second column disposed on the base, wherein the first column and the second column are parallel and spaced apart, and the interval between them is adjustable; A flange assembly, comprising a first flange connected to the first column and a second flange connected to the second column, wherein the first flange and the second flange are used to connect the two ends of the main pipe of the specimen, respectively. A crossbeam is provided between the first column and the second column, and the height of the crossbeam is adjustable; The actuators are numbered the same as the number of branches of the specimen and correspond one-to-one. One end of the actuator is connected to the crossbeam, and the other end of the actuator is used to connect to the free end of the branch of the specimen. The actuators can extend and retract in a direction that coincides with the axis of the branch.

2. The fatigue loading test apparatus for truss tower nodes according to claim 1, characterized in that, Both ends of the main pipe are equipped with docking flanges, and both the first flange and the second flange are connected to the corresponding docking flanges by multiple anchor bolts.

3. The fatigue loading test apparatus for truss tower nodes according to claim 1, characterized in that, The bottom of the first column and the second column are respectively provided with connecting plates. The connecting plates can slide and adjust along the base in the direction of the main pipe axis. The connecting plates are provided with first connecting holes. The base is provided with multiple sets of second connecting holes arranged along the direction of the main pipe axis. The first connecting holes and the corresponding second connecting holes are fastened together by bolts.

4. The fatigue loading test apparatus for truss tower nodes according to claim 1, characterized in that, The column assembly also includes a cross brace, the first flange is connected to the first column via the cross brace, and the second flange is connected to the second column via the cross brace.

5. The fatigue loading test apparatus for truss tower nodes according to claim 1, characterized in that, The crossbeam is located above the flange assembly and is parallel to the upper surface of the base. Both ends of the crossbeam are connected to the first column and the second column of the column assembly respectively through the first connector.

6. The fatigue loading test apparatus for truss tower nodes according to claim 5, characterized in that, Both the first and second columns have multiple bolt holes spaced apart along their height. The first connector adjusts the height of the crossbeam by engaging bolts with the corresponding bolt holes; or... Both the first column and the second column are provided with slide rails along the height direction. The first connector cooperates with the first column and the second column through the slide rails to adjust the height of the crossbeam.

7. The fatigue loading test apparatus for truss tower nodes according to claim 1, characterized in that, A second connector is installed on the crossbeam. The number of the second connectors is the same as the number of the actuators and they correspond one-to-one. The installation position of the second connector can be adjusted along the length of the crossbeam. One end of the actuator is connected to the second connector, and the other end of the actuator is connected to the free end of the branch pipe through a flange.

8. The fatigue loading test apparatus for truss tower nodes according to claim 7, characterized in that, When the specimen is a T-shaped node, there is one actuator, and the extension and retraction direction of the actuator is set perpendicular to the main pipe.

9. The fatigue loading test apparatus for truss tower nodes according to claim 7, characterized in that, When the specimen is a K-type node, there are two actuators, and one end of the actuator is hinged to the second connecting member.

10. A fatigue loading test method for truss tower joints, characterized in that, The fatigue loading test apparatus for truss tower nodes as described in any one of claims 2-9 is used to achieve the fatigue loading test method for truss tower nodes, which includes the following steps: S1. Select anchor bolts with preset yield loads, and determine the preload of a single anchor bolt and the number of anchor bolts to be used; S2. Install the test piece, adjust the distance between the first column and the second column, and fasten the butt flange at one end of the main pipe of the test piece to the first flange with the number of anchors used and the pre-tightening force. The butt flange at the other end of the main pipe of the test piece is fastened to the second flange with the number of anchors used and the pre-tightening force. Adjust the height of the crossbeam, connect one end of the actuator to the crossbeam, and connect the free end of the branch pipe to the other end of the actuator; S3. Activate the actuator and use the extension and retraction of the actuator to conduct a fatigue loading test on the specimen until the test is completed.

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