A loading device for composite torsion test of beam members and a shear-torsion test method thereof

Abstract

The application provides a beam member composite torsion test loading device and a shear-torsion test method thereof. The loading device can be used for pure torsion loading, bending-torsion loading, shear-torsion loading or bending-shear-torsion loading of a beam member. The loading device comprises two composite torsion supports for supporting and fixing the beam body; three counterforce frames for providing counterforce to electro-hydraulic servo actuators; three electro-hydraulic servo actuators for respectively applying loads to two outer arms and the beam body; three spherical hinge supports respectively arranged between the three electro-hydraulic servo actuators and the beam member; and a control system for controlling the three electro-hydraulic servo actuators to output loads in proportion and constant. The device can realize pure torsion and composite loading conditions of bending-torsion, shear-torsion and bending-shear-torsion. The test method of applying torsion to both ends of the beam member is adopted, so that the boundary conditions of the test piece are more composite and actual stress conditions. The shear-torsion ratio and the bending-torsion ratio can be kept constant during the loading process. A shear-torsion test method based on the loading device is also provided.

Description

Technical Field

[0001] This invention relates to the field of structural engineering testing technology, specifically to a composite torsion test loading device for beam members and its shear-torsion test method. Background Technology

[0002] In practical structural engineering, beam-type components such as edge beams, canopy beams, and crane beams in frame structures are often under combined torsion under their own weight and external loads. Therefore, in order to further study the failure modes and stress mechanisms of beam-type components under different combined torsion states, it is necessary to conduct combined torsion test studies on beam-type components.

[0003] Traditional loading devices have the following shortcomings: ① The test loading device can only complete one loading condition and cannot realize multiple composite loading conditions; ② The test uses multiple actuators to load independently, and there is no linkage control between the actuators. During the loading process, the load between each actuator cannot be proportionally output at all times, which makes it impossible for the test to keep the torsion-shear ratio and torsion-bending ratio constant at all times; ③ The beam member test uses the column member loading method (torque is applied to one end of the specimen and the other end is fixed). As the load increases, cracks appear at the fixed end, the stiffness decreases, and the fixed end fails first. This is different from the constraint type and failure location of the composite torsion beam member in reality; ④ The composite torsion device cannot guarantee that the specimen will torsion around the torsion center of the section during all specimens under torsion loading; ⑤ During the loading process, sliding friction is used between the arc-shaped components of the upper and lower torsion supports. Compared with rolling friction, the frictional resistance is larger; ⑥ The shear-torsion test loading method ignores the influence of the bending moment caused by the applied shear force on the shear-torsion test. Summary of the Invention

[0004] This invention is made to solve the above-mentioned problems, and its purpose is to provide a composite torsion test loading device for beam members and a shear-torsion test method thereof.

[0005] This invention provides a composite torsion test loading device for beam-type components, used to subject beam-type components to pure torsion loading, bending-torsion loading, shear-torsion loading, or bending-shear-torsion loading. The beam-type component includes a beam body and two outriggers perpendicularly connected to both ends of the beam body and in opposite directions. It features two composite torsion supports, respectively supported at the middle of the beam body near one end and at the other end. Each composite torsion support includes a clamping assembly, a torsion assembly, and a bending assembly connected sequentially from top to bottom. The clamping assembly supports and fixes the beam body, the torsion assembly provides torsional freedom for the beam-type component at the support, and the bending assembly provides bending freedom for the beam-type component at the support; three reaction frames. The system includes two reaction frames positioned at the locations of the two outriggers, and another reaction frame positioned at the midpoint of the beam body between two composite torsion supports. Three electro-hydraulic servo actuators are vertically mounted on the three reaction frames; two of these actuators apply loads to the two outriggers, and the other applies loads to the beam body. Three ball joint supports are positioned between the three electro-hydraulic servo actuators and corresponding portions of the beam member, transferring loads to the beam member and reducing the constraint effect of vertical loads on the torsion of the beam member. A control system connects to and controls the three electro-hydraulic servo actuators to output loads proportionally and constantly.

[0006] The composite torsion test loading device for beam components provided by this invention may also have the following features: the clamping assembly includes an upper clamping plate, a lower clamping plate, a height pad, and multiple screws. The upper clamping plate is set on the top surface of the beam body, the lower clamping plate is set below the beam body, and the height pad is set between the beam body and the lower clamping plate to adjust the placement position of the beam component, ensuring that the beam body can torsion around its own cross-sectional torsion center. The upper and lower ends of the multiple screws are respectively connected to the upper clamping plate and the lower clamping plate, and are locked by nuts to clamp the upper clamping plate and the lower clamping plate, thereby fixing the beam body.

[0007] The composite torsion test loading device for beam components provided by the present invention may also have the following features: the torsion assembly includes an upper arc-shaped support, a lower arc-shaped support, multiple sliding rollers, and two roller supports. The top surface of the upper arc-shaped support is connected to the bottom of the clamping assembly. The bottom surface of the upper arc-shaped support is a convex arc surface, and its arc center coincides with the torsion center of the beam section. The top surface of the lower arc-shaped support is a concave arc surface. The multiple sliding rollers are rotatably arranged between the convex arc surface of the upper arc-shaped support and the concave arc surface of the lower arc-shaped support. The two ends of each sliding roller are rotatably mounted on the two roller supports to prevent them from falling off.

[0008] Furthermore, the torsion assembly also includes two baffles, which are respectively installed on the two sides of the corresponding sliding rollers at both ends of the upper arc-shaped support and respectively limit the two sides of the corresponding sliding rollers at both ends of the lower arc-shaped support to prevent the upper arc-shaped support from falling off the lower arc-shaped support due to axial tension during the torsion process of the beam.

[0009] Furthermore, lubricant is sprayed onto the surface of the sliding roller, the convex arc surface of the upper arc support, and the concave arc surface of the lower arc support.

[0010] The composite torsion test loading device for beam components provided by the present invention may also have the following features: the bending assembly includes an upper pad, a lower pad, a roller, and a plurality of anti-slip screws. The top surface of the upper pad is connected to the bottom of the torsion assembly. The bottom surface of the upper pad and the top surface of the lower pad are respectively provided with keyways extending along the axial direction of the beam. The roller is rotatably disposed between the upper pad and the lower pad along the axial direction of the beam. The roller is provided with an annular protrusion that matches the keyway. A plurality of anti-slip screws are installed on the bottom surface of the upper pad and the top surface of the lower pad. The anti-slip screws on each pad are arranged on both sides of the roller to prevent the roller from falling off between the upper pad and the lower pad.

[0011] The composite torsion test loading device for beam components provided by the present invention may also have the following features: each ball joint support includes an upper ball joint support pad and a lower ball joint support pad, the bottom surface of the upper ball joint support pad is provided with a convex spherical surface in the middle, and the top surface of the lower ball joint support pad is provided with a matching concave spherical surface in the middle.

[0012] This invention also provides a shear-torsion test method for beam members, characterized by the following steps: using the above-mentioned composite torsion test loading device for beam members, including: (1) determining the dimensions of the beam member, the load output ratio of the three electro-hydraulic servo actuators, and the position of the action point of the electro-hydraulic servo actuators acting on the beam body, ensuring that the test failure occurs near the inflection point of the beam body; (2) assembling the various parts of the composite torsion test loading device for beam members and installing it with the beam member; (3) arranging the measuring device at the observation position on the surface of the beam body and connecting the strain gauges measuring the internal reinforcement of the beam body to the measuring channel; (4) loading the beam member, wherein, during pre-loading, debugging whether each part is installed normally and whether the data of each measuring channel is abnormal, and during formal loading, controlling the three electro-hydraulic servo actuators to synchronously apply vertical downward load according to the designed load output ratio through the control system, loading in stages until the beam body fails.

[0013] The shear-torsion test method provided by the present invention may also have the following features: step (2) includes: placing the beam horizontally on the clamping assembly of the two composite torsion supports and clamping the beam; fixing the three reaction frames at the positions corresponding to the two cantilever arms and the beam; installing the three electro-hydraulic servo actuators on the three reaction frames and making them act vertically downward on the designed positions of the two cantilever arms and the beam; placing ball joint supports between the corresponding parts of each electro-hydraulic servo actuator and the beam component; and connecting the three electro-hydraulic servo actuators to the control system.

[0014] The role and effect of invention

[0015] The composite torsion test loading device and shear-torsion test method for beam members according to the present invention have the following beneficial effects:

[0016] (1) The composite torsion test loading device can realize pure torsion loading conditions as well as composite loading conditions of bending torsion, shear torsion, and bending shear torsion.

[0017] (2) The three electro-hydraulic servo actuators are linked and controlled by a unified control system. During the loading process, each electro-hydraulic servo actuator can output according to a fixed ratio, thereby ensuring that the torsion-shear ratio and torsion-bending ratio remain constant throughout the test.

[0018] (3) The test method of applying torque to both ends of the beam member is closer to the boundary constraint conditions of the beam member than the existing method of fixing one end and applying torque to the other end. It can avoid the problem of decreased stiffness, weakened constraint and premature failure of the fixed end of the specimen due to increased load and concrete cracking. In addition, the test method of loading at both ends can divide the ultimate torsional angle of the specimen equally at both ends of the specimen, which can reduce the error caused by the tilt of the electro-hydraulic servo actuator.

[0019] (4) For the torsion assembly of the composite torsion support, a sliding roller is designed between the upper arc support and the lower arc support, so that the upper arc support and the lower arc support are rolling friction during the loading process, which can greatly reduce the frictional resistance.

[0020] (5) For the clamping assembly of the composite torsion support, the specimen is fixed by a connection structure of upper clamping plate, lower clamping plate and screw. A height pad is provided between the specimen and the lower clamping plate to ensure that the specimen can be torsion around the torsion center of the cross section during all specimen loading processes.

[0021] (6) During the shear-torsion test, considering the influence of the bending moment caused by the applied shear force on the shear-torsion test, the dimensions of the beam member, the load output ratio of the three electro-hydraulic servo actuators, and the position of the electro-hydraulic servo actuators acting on the beam body are selected and determined in the design stage in conjunction with the test study parameters, so as to ensure that the test failure location occurs near the inflection point of the beam body.

[0022] (7) The composite torsion test loading device adopts an assembly structure, and the components can be quickly disassembled and replaced. The composite design of the composite torsion support is conducive to carrying out composite torsion tests on specimens with different cross-sectional shapes, and has strong versatility. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a composite torsion test loading device for beam-type components in an embodiment of the present invention;

[0024] Figure 2 This is another structural schematic diagram of the composite torsion test loading device for beam-type components in an embodiment of the present invention;

[0025] Figure 3 This is an exploded view of the ball joint support in an embodiment of the present invention;

[0026] Figure 4 This is a schematic diagram of the composite torsion support in an embodiment of the present invention;

[0027] Figure 5 This is an exploded schematic diagram of the composite torsion support in an embodiment of the present invention;

[0028] Figure 6 This is a front view of the composite torsion support in an embodiment of the present invention;

[0029] Figure 7 This is a side view of the composite torsion support in an embodiment of the present invention;

[0030] Figure 8 This is a cross-sectional view of the composite torsion support in an embodiment of the present invention.

[0031] Explanation of reference numerals in the attached figures:

[0032] 1. Beam-type component; 10a. Composite torsion support; 10b. Composite torsion support; 11. Clamping assembly; 111. Upper clamping plate; 112. Lower clamping plate; 113. Height pad; 114. Screw; 12. Torsion assembly; 121. Upper arc-shaped support; 122. Lower arc-shaped support; 123. Sliding roller; 124. Roller bracket; 125. Baffle; 13. Bending assembly; 131. Upper pad; 132. Lower pad; 13 3 rollers; 1331 annular protrusion; 134 anti-slip screw; 20a reaction frame; 20b reaction frame; 20c reaction frame; 30a electro-hydraulic servo actuator; 30b electro-hydraulic servo actuator; 30c electro-hydraulic servo actuator; 40a ball joint support; 40b ball joint support; 40c ball joint support; 41 upper pad of ball joint support; 411 convex spherical surface; 42 lower pad of ball joint support; 421 concave spherical surface. Detailed Implementation

[0033] To make the technical means, creative features, objectives and effects of this invention easier to understand, the following embodiments are described in detail with reference to the accompanying drawings.

[0034] Example

[0035] Figure 1 and Figure 2 These are schematic diagrams of the composite torsion test loading device for beam-type components from different perspectives.

[0036] like Figure 1 and Figure 2 As shown, this embodiment provides a composite torsion test loading device for a beam-type component, including a composite torsion support, a reaction frame, an electro-hydraulic servo actuator, a ball joint support, and a control system. The beam-type component 1 includes a beam body integrally connected to the beam body and two outriggers. The two outriggers are vertically connected to both ends of the beam body and arranged in opposite directions. The entire beam-type component 1 is placed horizontally during the test.

[0037] The composite torsion support is used to support the beam body of beam member 1. There are two composite torsion supports: composite torsion support 10a and composite torsion support 10b. Composite torsion support 10a is located near one end of the beam body in the middle, and composite torsion support 10b is located at the other end of the beam body, allowing the overhang arm at that end to extend laterally. The structure of the composite torsion support will be explained in detail later with reference to the relevant accompanying drawings.

[0038] The reaction frame comprises two columns and a crossbeam spanning the two columns. There are three reaction frames: reaction frame 20a, reaction frame 20b, and reaction frame 20c. Reaction frames 20a and 20b are positioned at the cantilever arms at both ends of the beam member 1, with their crossbeams parallel and directly above the corresponding cantilever arms. Reaction frame 20c is positioned at the middle of the beam member 1, between the composite torsion support 10a and composite torsion support 10b. The crossbeam of reaction frame 20c is positioned above the beam body and perpendicular to it. The span of the reaction frame, i.e., the length of the crossbeam, should be greater than the length of the cantilever arm to ensure that the cantilever arm can move within the plane of the reaction frame. The crossbeam of the reaction frame can be fixed to the columns with screws, and the height of the crossbeam can be adjusted on the columns.

[0039] Electro-hydraulic servo actuators are used to apply loads to beam member 1. There are three electro-hydraulic servo actuators: 30a, 30b, and 30c. One end of each actuator has a universal joint mounted on the crossbeam of one of the three reaction frames, and the piston at the other end acts on beam member 1 via a ball joint support. Electro-hydraulic servo actuators 30a and 30b, located at either end of beam member 1, apply loads to their respective overhanging arms, thereby applying torque to the beam. Electro-hydraulic servo actuator 30c, located in the middle of beam member 1, applies loads to the beam. These three electro-hydraulic servo actuators are linked and controlled by a control system, ensuring a constant proportional load output throughout the loading process, thus guaranteeing that the torsional-shear ratio and torsional-bending ratio remain constant throughout the test.

[0040] The ball joint supports are used to transfer the load output by the electro-hydraulic servo actuator to the beam member 1. There are three ball joint supports: ball joint support 40a, ball joint support 40b, and ball joint support 40c, which are respectively installed between the electro-hydraulic servo actuators 30a, 30b, and 30c and corresponding parts of the beam member 1. Figure 3 As shown in the exploded schematic diagram of the ball joint support, each ball joint support includes an upper ball joint support plate 41 and a lower ball joint support plate 42. The top surface of the upper ball joint support plate 41 is in contact with the electro-hydraulic servo actuator. A convex spherical surface 411 is provided in the middle of the bottom surface of the upper ball joint support plate 41. A matching concave spherical surface 421 is provided in the middle of the top surface of the lower ball joint support plate 42. The bottom surface of the lower ball joint support plate 42 is in contact with the beam member 1. The ball joint support enables the load output by the electro-hydraulic servo actuator to be transmitted to the beam member 1 in a manner closest to the actual load, and reduces the constraint effect of the vertical load on the torsion of the beam member 1.

[0041] The composite torsion support will be explained in detail below.

[0042] Figures 4 to 8 These are the structural schematic diagram, exploded view, front view, side view, and sectional view of the composite torsion support.

[0043] like Figures 4 to 8 As shown, each composite torsion support includes a clamping assembly 11, a torsion assembly 12, and a bending assembly 13 connected sequentially from top to bottom.

[0044] The clamping assembly 11 is used to support and fix the beam body of the beam-type component 1, and mainly includes two upper clamping plates 111, one lower clamping plate 112, a height pad 113, and four screws 114. The two upper clamping plates 111 are disposed on the top surface of the beam body and distributed along the axial direction of the beam body. Each upper clamping plate 111 extends along the width direction of the beam body and has threaded holes at both ends. The lower clamping plate 112 is disposed below the beam body corresponding to the two upper clamping plates 111, and each of the four corners of the lower clamping plate 112 has threaded holes. The height pad 113 is disposed between the beam body and the lower clamping plate 112, as shown in the figure. Figure 1 and Figure 2 The thickness of the height pad 113 is t = R - 0.5h, where h is the height of the beam section and R is the radius of the upper arc support 121 of the torsion assembly 12. The height pad 113 is used to ensure that the arc center of the upper arc support 121 coincides with the torsion center of the beam section. In this way, when torque is applied to the beam member 1, the beam can torsion around its own torsion center. In addition, the cross-sectional dimension of the height pad 113 should not be greater than the dimension of the lower clamping plate 112, and the width of the height pad 113 should not be less than the width of the beam section. The upper ends of the four screws 114 are connected to the two ends of the two upper clamping plates 111 respectively, and the lower ends are connected to the four corners of the lower clamping plate 112 respectively. The two upper clamping plates 111 and the lower clamping plate 112 are clamped together by locking with nuts to fix the beam. The spacing between adjacent screws 114 should be sufficient for the beam or the overhang arm to pass through.

[0045] The torsion assembly 12 provides torsional freedom for the beam member 1 at the support, and mainly includes an upper arc-shaped support 121, a lower arc-shaped support 122, multiple sliding rollers 123, two roller supports 124, and two baffles 125. The upper arc-shaped support 121 is connected to the bottom surface of the lower clamping plate 112 of the clamping assembly 11 by screws. The bottom surface of the upper arc-shaped support 121 is a convex arc surface, and its arc center coincides with the torsional center of the beam section. The top surface of the lower arc-shaped support 122 is a concave arc surface, and the width of the lower arc-shaped support 122 (in the beam width direction) is greater than the width of the upper arc-shaped support 121. Multiple sliding rollers 123 are rotatably disposed between the convex arc surface of the upper arc-shaped support 121 and the concave arc surface of the lower arc-shaped support 122. Lubricant is sprayed onto the surfaces of the sliding rollers 123, the convex arc surface of the upper arc-shaped support 121, and the concave arc surface of the lower arc-shaped support 122. Each sliding roller 123 is rotatably mounted at both ends on two arc-shaped roller supports 124, which prevent the sliding rollers 123 from falling off. Two baffles 125 are respectively installed on the two sides of the corresponding sliding rollers 123 at both ends of the upper arc-shaped support 121, and respectively engage with the two sides of the corresponding sliding rollers 123 at both ends of the lower arc-shaped support 122 to limit their movement, preventing the upper arc-shaped support 121 from falling off the lower arc-shaped support 122 due to axial tension during beam torsion.

[0046] The bending assembly 13 provides the beam member 1 with bending freedom at the support, and mainly includes an upper pad 131, a lower pad 132, a roller 133, and multiple anti-slip screws 134. The upper pad 131 is connected to the bottom surface of the lower arc-shaped support 122 of the torsion assembly 12 by screws. Two keyways are correspondingly formed on the bottom surface of the upper pad 131 and the top surface of the lower pad 132. The two keyways on each pad are distributed along the width direction of the beam and extend in the axial direction. The roller 133 is rotatably disposed between the upper pad 131 and the lower pad 132 in the axial direction of the beam. The roller 133 has two annular protrusions 1331 that match the two keyways on the upper pad 131 and the lower pad 132, ensuring that the roller 133 can roll between the upper pad 131 and the lower pad 132 in the axial direction of the beam. Two rows of anti-slip screws 134 are also provided on the bottom surface of the upper pad 131 and the top surface of the lower pad 132. The two rows of anti-slip screws on each pad are arranged on both sides of the roller 133 to prevent the roller 133 from falling off between the upper pad 131 and the lower pad 132.

[0047] This composite torsion test loading device for beam members is used to apply shear-torsion loading to beam member 1, where the structure is as follows: Figure 1 and Figure 2 As shown, the shear-torsion test process is as follows:

[0048] (1) Experimental design stage: Select and determine the dimensions of beam component 1, the load output ratio of electro-hydraulic servo actuators 30a, 30b, and 30c, and the position of the action point of electro-hydraulic servo actuator 30b on the beam according to the experimental research parameters, so as to ensure that the test failure location occurs near the inflection point of the beam; make height pads 113 according to the height of the beam section and the radius of the upper arc support 121.

[0049] (2) Assemble the composite torsion test loading device for the beam component and install it with the beam component 1: First, place the beam body horizontally on the clamping assembly 11 of the composite torsion support 10a and composite torsion support 10b, and make the clamping assembly 11 clamp the beam body. Specifically, the operation of the clamping assembly 11 is as follows: first, place the height pad 113 in the middle position of the lower clamping plate 112, then place the beam body on the height pad 113, and then pass four screws 114 through the lower clamping plate 112 and the two upper clamping plates 111 placed on the top surface of the beam body, and tighten the nuts respectively to clamp the lower clamping plate 112 and the two upper clamping plates 111.

[0050] Next, reaction frames 20a and 20b are respectively positioned at the cantilever arms at both ends of beam member 1, and reaction frame 20c is positioned at the middle of beam member 1. Electro-hydraulic servo actuators 30a, 30b, and 30c are respectively installed on reaction frames 20a, 20b, and 20c, with electro-hydraulic servo actuators 30a and 30b acting vertically downwards on the two cantilever arms, and electro-hydraulic servo actuator 30c acting vertically downwards at the designed position on the beam body. Ball joint supports 40a and 40b are placed between electro-hydraulic servo actuator 30a and its corresponding cantilever arm, and between electro-hydraulic servo actuator 30b and its corresponding cantilever arm, respectively. A ball joint support 40c is placed between electro-hydraulic servo actuator 30c and the beam body. Connect electro-hydraulic servo actuators 30a, 30b, and 30c to the control system.

[0051] It can be further adjusted to ensure that beam component 1 is in a horizontal state and the three electro-hydraulic servo actuators are in a vertically downward state.

[0052] (3) Install measuring devices: Arrange measuring devices at the observation positions on the surface of the beam. The measuring devices include displacement gauges, inclinometers, and strain gauges; connect the strain gauges for measuring the internal reinforcement of the beam to the measuring channel.

[0053] (4) Loading stage: During preloading, check whether each part of the load device for composite torsion test of beam component is installed normally and whether the data of each measurement channel of the measuring device is abnormal; during formal loading, control the electro-hydraulic servo actuators 30a, 30b and 30c to apply vertical downward load synchronously according to the designed load output ratio through the control system, and load in stages until the beam body is damaged.

[0054] The final shear-torsion test data of beam member 1 were obtained for further analysis and research.

[0055] When this composite torsion test loading device for beam member 1 is used to apply pure torsion loading, the structure needs to be appropriately adjusted. Specifically, the adjustment is as follows: Figure 1 and Figure 2 Based on the structure shown, the reaction frame 20c, electro-hydraulic servo actuator 30c, and ball joint support 40c are removed. The composite torsion support 10a is adjusted to be below the reaction frame 20a, and the overhang arm at one end of the beam member 1 protrudes from the composite torsion support 10a. In this state, the device can achieve pure torsional loading on the beam member 1. The process of pure torsion test can be adapted by referring to the process of shear torsion test, and will not be described in detail here.

[0056] When this composite torsion test loading device for beam member 1 is used to apply bending and torsion loading, the structure needs to be appropriately adjusted. Specifically, the adjustment is as follows: Figure 1 and Figure 2 Based on the structure shown, the reaction frame 20c, electro-hydraulic servo actuator 30c, and ball joint support 40c are removed, and the composite torsion support 10b is adjusted to a certain point on the beam. In this state, the device can achieve bending and torsional loading on the beam member 1. The bending and torsional test process can be adapted by referring to the shear and torsional test process, which will not be described in detail here.

[0057] When this composite torsion test loading device for beam member 1 is used to apply bending, shear, and torsion loading, the structure needs to be appropriately adjusted. Specifically, the adjustment is as follows: Figure 1 and Figure 2 Based on the structure shown, the composite torsion support 10a is adjusted to be below the reaction frame 20a, and the overhang arm at one end of the beam member 1 protrudes from the composite torsion support 10a. In this state, the device can perform bending, shear, and torsion loading on the beam member 1. The bending, shear, and torsion test process can be adapted by referring to the shear and torsion test process, and will not be described in detail here.

[0058] The role and effect of the embodiments

[0059] The composite torsion test loading device for beam-type components involved in this embodiment has the following beneficial effects:

[0060] (1) The composite torsion test loading device can realize pure torsion loading conditions as well as composite loading conditions of bending torsion, shear torsion, and bending shear torsion.

[0061] (2) The three electro-hydraulic servo actuators are linked and controlled by a unified control system. During the loading process, each electro-hydraulic servo actuator can output according to a fixed ratio, thereby ensuring that the torsion-shear ratio and torsion-bending ratio remain constant throughout the test.

[0062] (3) The test method of applying torque to both ends of the beam member is closer to the boundary constraint conditions of the beam member than the existing method of fixing one end and applying torque to the other end. It can avoid the problem of decreased stiffness, weakened constraint and premature failure of the fixed end of the specimen due to increased load and concrete cracking. In addition, the test method of loading at both ends can divide the ultimate torsional angle of the specimen equally at both ends of the specimen, which can reduce the error caused by the tilt of the electro-hydraulic servo actuator.

[0063] (4) For the torsion assembly of the composite torsion support, a sliding roller is designed between the upper arc support and the lower arc support, so that the upper arc support and the lower arc support are rolling friction during the loading process, which can greatly reduce the frictional resistance.

[0064] (5) For the clamping assembly of the composite torsion support, the specimen is fixed by a connection structure of upper clamping plate, lower clamping plate and screw. A height pad is provided between the specimen and the lower clamping plate to ensure that the specimen can be torsion around the torsion center of the cross section during all specimen loading processes.

[0065] (6) During the shear-torsion test, considering the influence of the bending moment caused by the applied shear force on the shear-torsion test, the dimensions of the beam member, the load output ratio of the three electro-hydraulic servo actuators, and the position of the electro-hydraulic servo actuators acting on the beam body are selected and determined in the design stage in conjunction with the test study parameters, so as to ensure that the test failure location occurs near the inflection point of the beam body.

[0066] (7) The composite torsion test loading device adopts an assembly structure, and the components can be quickly disassembled and replaced. The composite design of the composite torsion support is conducive to carrying out composite torsion tests on specimens with different cross-sectional shapes, and has strong versatility.

[0067] The above embodiments are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention.

Claims

1. A composite torsion test loading device for a beam member, for pure torsion loading, bending-torsion loading, shearing-torsion loading or bending-shearing-torsion loading of a beam member, the beam member comprising a beam body and two outer arms each perpendicularly connected to the beam body at opposite ends of the beam body and in opposite directions, characterized in that, The utility model relates to a kind of composite beam torsion support and control system, including: Two composite torsion supports are supported respectively in the middle of the beam body near one end and the other end of the beam body, each composite torsion support includes sequentially connected from top to bottom embracing component, torsion component and bending component, The embracing component is used to support and fix the beam body, The torsion component is used to provide the torsion freedom of the beam member at the support, The bending component is used to provide the bending freedom of the beam member at the support; Three reaction frames, wherein two reaction frames are respectively arranged at two outer arm positions, and the other reaction frame is arranged at the middle of the beam body and located between two composite torsion supports; Three electro-hydraulic servo actuators are vertically installed on three reaction frames, wherein two electro-hydraulic servo actuators are used to apply load to two outer arms, and the other electro-hydraulic servo actuator is used to apply load to the beam body; Three spherical hinge supports are respectively arranged between three electro-hydraulic servo actuators and corresponding parts of the beam member, used to transfer load to the beam member and reduce the constraint effect of vertical load on the torsion of the beam member;And Control system, connected and control three electro-hydraulic servo actuators proportional constant output load, Wherein, the embracing component includes upper clamp plate, lower clamp plate, height pad and multiple screw rods, The upper clamp plate is arranged on the top surface of the beam body, The lower clamp plate is arranged below the beam body, The height pad is arranged between the beam body and the lower clamp plate, used to adjust the placement position of the beam member, to ensure that the beam body can be twisted around the torsion center of its cross section, The upper end and the lower end of multiple screw rods are connected with the upper clamp plate and the lower clamp plate respectively, and the upper clamp plate and the lower clamp plate are clamped between the upper clamp plate and the lower clamp plate by nut locking, to realize the fixation of the beam body, The torsion component includes upper arc support, lower arc support, multiple sliding rollers and two roller supports, The top surface of the upper arc support is connected to the bottom of the embracing component, and the bottom surface of the upper arc support is convex arc surface, and the arc center coincides with the torsion center of the beam body cross section, The top surface of the lower arc support is concave arc surface, Multiple sliding rollers are rollably arranged between the convex arc surface of the upper arc support and the concave arc surface of the lower arc support, and the two ends of each sliding roller are rotatably installed on two roller supports to prevent falling off, The bending component includes upper pad, lower pad, roller and multiple anti-skid screws, The top surface of the upper pad is connected to the bottom of the torsion component, and the bottom surface of the upper pad and the top surface of the lower pad are correspondingly provided with key grooves extending in the axial direction of the beam body, The roller is rollably arranged between the upper pad and the lower pad in the axial direction of the beam body, and the roller is provided with annular protrusion matched with the key groove. A plurality of said anti-skid screws are installed on the bottom surface of said upper pad plate and the top surface of said lower pad plate, and said anti-skid screws on each pad plate are arranged on both sides of said roller, for preventing said roller from falling off between said upper pad plate and said lower pad plate.

2. The composite torsion test loading device for beam members according to claim 1, characterized in that: wherein said torsion assembly further comprises two baffle plates, said two baffle plates are respectively installed on the two sides of the two ends of the corresponding sliding roller of said upper arc-shaped support, and are respectively limitedly matched with the two sides of the two ends of the corresponding sliding roller of said lower arc-shaped support, for preventing said upper arc-shaped support from falling off from said lower arc-shaped support due to axial stretching in the process of torsion of said beam body.

3. The composite torsion test loading device for beam members according to claim 1, characterized in that: wherein, the surface of said sliding roller, the convex arc surface of said upper arc-shaped support, and the concave arc surface of said lower arc-shaped support are all sprayed with lubricant.

4. The composite torsion test loading device for beam members according to claim 1, characterized in that: wherein each said spherical hinge support comprises a spherical hinge support upper pad plate and a spherical hinge support lower pad plate, the middle part of the bottom surface of said spherical hinge support upper pad plate is provided with a convex spherical surface, the middle part of the top surface of said spherical hinge support lower pad plate is provided with a matching concave spherical surface.

5. A method of shear-torsion testing of a beam member, characterized by The composite torsion test loading device for beam members according to any one of claims 1-4, comprising the following steps: (1) determining the size of the beam member, the load output ratio of the three electro-hydraulic servo actuators, and the position of the acting point of the electro-hydraulic servo actuators on the beam body, to ensure that the test failure position occurs near the inflection point of the beam body; (2) assembling each part of the composite torsion test loading device for beam members, and installing it with the beam member; (3) arranging the measuring device at the observation position on the surface of the beam body, and connecting the strain gauges for measuring the internal reinforcement of the beam body to the measuring channel; (4) loading the beam member, wherein, during preloading, whether each part is installed normally and whether the data of each measuring channel is abnormal is debugged, and during formal loading, the three electro-hydraulic servo actuators are controlled by the control system to synchronously apply vertical downward load according to the designed load output ratio, and the load is applied in stages until the beam body fails.

6. The shear- torsion test method of claim 5, characterized in that: wherein, step (2) comprises: placing the beam body horizontally on the clamping assembly of the two composite torsion supports, and making the clamping assembly clamp the beam body; fixing the three counterforce frames at the positions corresponding to the two outer arms and the beam body, respectively, installing the three electro-hydraulic servo actuators on the three counterforce frames, respectively, and making them act vertically downward on the designed positions of the two outer arms and the beam body, respectively, and placing the spherical hinge supports between the corresponding parts of each electro-hydraulic servo actuator and the beam member; connecting the three electro-hydraulic servo actuators to the control system.

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