Strain gauge adjusting device and box dynamic strain test point arrangement method

Abstract

The invention relates to the technical field of box type roadbed construction, and particularly discloses a strain gauge adjusting device and a box dynamic strain test point arrangement method. The device comprises a device main body, the device main body comprises a frame body, a substrate is arranged in the frame body, a plurality of strain gauges are arranged on one end face of the substrate, and the substrate and the plurality of strain gauges jointly form a three-way strain rosette; a first connecting block is arranged on the side wall of the base plate, and a second connecting block rotationally connected with the first connecting block is arranged on the inner side wall of the frame body; an adjusting mechanism is arranged on the side wall of the frame body and used for pushing the base plate to rotate along the rotating connecting position. The subsequent measurement data can be prevented from being influenced by the inclination of the three-direction strain rosette on the substrate; the method comprises the following steps: arranging strain gauges at the center of the bottom surface of a top plate of a box body and haunched positions on two sides respectively, and arranging a strain gauge at the center of the top surface of a bottom plate of the box body; strain gauges are arranged on the inner side, the outer side, the upper haunching position and the lower haunching position of the box web. And monitoring personnel can conveniently prevent the box body from being damaged.

Description

Technical Field

[0001] This invention relates to the field of box-type roadbed construction technology, specifically to a strain gauge adjustment device and a method for arranging dynamic strain test points in the box. Background Technology

[0002] Box-type roadbeds, such as precast concrete box structures in railway construction, are subjected to dynamic loads such as vehicle vibration, temperature changes, and foundation settlement during long-term service. Their stress distribution directly affects the safety, durability, and stability of the structure. Therefore, long-term monitoring of the roadbed is necessary. Currently, stress monitoring of box-type roadbeds usually uses fixed-angle triaxial strain gauges (such as 0°-45°-90° or 0°-60°-120°) and strain gauges fixed on the roadbed. Due to the uneven surface of the box, construction workers usually fix the triaxial strain gauges and strain gauges to the box by gluing or manually fixing them with bolts. After the construction workers have fixed them, some triaxial strain gauges are prone to tilting at the angle. At this time, they need to be removed and reinstalled, which is time-consuming and labor-intensive for the construction workers and affects the construction progress. Summary of the Invention

[0003] This invention provides a strain gauge adjustment device and a method for arranging dynamic strain test points in a test chamber, which can overcome some or all of the defects of the prior art.

[0004] According to a strain gauge adjustment device of the present invention, the device includes: a device body, the device body including a frame, a base plate being provided inside the frame, a plurality of strain gauges being provided at one end face of the base plate, the base plate and the plurality of strain gauges together forming a triaxial strain rosette; a first connecting block being provided at the side wall of the base plate, and a second connecting block being provided at the inner side wall of the frame and rotatably connected to the first connecting block; an adjustment mechanism being provided at the side wall of the frame, the adjustment mechanism being used to push the base plate to rotate along the rotatable connection.

[0005] With this invention, when using the strain gauge adjustment device, the construction personnel first fix the frame to the box body by passing screws through the bolt holes at the four corners of the frame. After the frame is fixed, the construction personnel rotate the bolt located at the bottom of the frame so that the bolt enters the threaded blind hole on the mounting block. During the process of the bolt entering the threaded blind hole, the bolt will push the sliding member to move along the strip-shaped through hole. At this time, the cylinder on the sliding member will press the inclined surface at the lower end of the substrate, so that the substrate will rotate along the rotating connection of the first connecting block and the second connecting block, thereby adjusting the position of the substrate and preventing the triaxial strain rose on the substrate from tilting and affecting the subsequent measurement data. The adjustment device includes a substrate, and the triaxial strain rose is first firmly pasted on this substrate. This structure can provide better rigid support, so that the strain is transmitted from the concrete structure surface to the strain gauge more completely and without loss through the device base, reducing the signal attenuation caused by the thickness or unevenness of the adhesive layer.

[0006] After the sliding component located below the frame is adjusted by the construction personnel, the construction personnel then rotate the bolt located on the side wall of the frame. As the bolt enters the mounting block, it pushes the sliding component, causing the cylinder on the sliding component to press against the inclined surface on the side wall of the substrate. This, in conjunction with the sliding component below the frame, clamps and fixes the substrate, preventing it from moving.

[0007] Preferably, the adjustment mechanism includes a pushing component disposed on an adjacent side wall of the frame. The pushing component includes a mounting block. A strip-shaped through hole is provided on the side wall of the frame along the length of the side wall. One end of the mounting block near the strip-shaped through hole is recessed inward to form a threaded blind hole. A sliding member is provided at the strip-shaped through hole. A bolt is provided at the threaded blind hole to extend into the threaded blind hole and to push the sliding member to move along the strip-shaped through hole.

[0008] With this invention, the construction worker rotates the bolt, causing the nut on the bolt to push the round block to move. The movement of the round block causes the connecting rod to move along the strip-shaped through hole. The cross-section of the strip-shaped through hole is rectangular, and the cross-section of the connecting rod is also rectangular, thereby preventing the connecting rod from shaking during movement and significantly improving the stability of the sliding component during movement.

[0009] Preferably, the sliding member includes a connecting rod passing through a strip-shaped through hole, a circular block at one end of the connecting rod near the bolt, and a limiting hole at the circular block for the bolt to pass through; a cylinder at one end of the connecting rod away from the circular block; and an inclined surface at one end of the substrate near the cylinder, which is provided along the length of the substrate sidewall.

[0010] With this invention, the thickness of the circular block is less than the width of the strip-shaped through hole. When installing the sliding component, the construction personnel pass the connecting rod and the circular block through the strip-shaped through hole on the frame, and then insert the bolt through the limiting hole on the circular block into the threaded blind hole on the mounting block; thus, it is convenient for the installer to install the sliding component onto the frame.

[0011] Preferably, the frame is rectangular in shape, and each of the four corners of the frame is provided with a connecting plate that connects to the frame, and the connecting plate is provided with bolt holes.

[0012] With this invention, when construction workers connect the frame and the box, they align the connecting plates at the four corners of the frame with the pre-embedded holes on the box, so that the bolt holes on the connecting plates are connected to the pre-embedded holes. Then, screws are inserted into the pre-embedded holes through the bolt holes to fix the frame to the frame.

[0013] Preferably, the second connecting block has two parallel mounting plates with mounting holes; the two mounting plates and the second connecting block together form a limiting range into which the first connecting block extends; the first connecting block has a rotating column that passes through the mounting holes.

[0014] With this invention, the second connecting block is welded to the two mounting plates. When assembling the substrate and the frame, the first connecting block on the substrate is first inserted into the limiting range, and then the rotating column is glued to the first connecting block through the mounting hole by means of adhesive. This makes it convenient for the installer to connect the substrate and the frame.

[0015] Preferably, the sliding parts are made of stainless steel, and the cylinders and blocks are welded to the connecting rods.

[0016] This invention provides a high-strength stainless steel structure that can extend the service life of sliding components.

[0017] This invention provides a method for arranging dynamic strain test points in a box-shaped structure. The steps are as follows: First, one strain gauge is arranged at the center of the bottom surface of the top plate of the box-shaped structure and at the armholes on both sides. Then, one strain gauge is arranged at the center of the top surface of the bottom plate of the box-shaped structure. Strain gauges are arranged on the inner and outer sides of the web plate of the box-shaped structure and at the upper and lower armholes. The inner side uses a strain gauge adjustment device. The construction personnel first fix the strain gauge adjustment device on the inner side of the web plate of the box-shaped structure. After the strain gauge adjustment device is fixed, the base plate is pushed to rotate along the rotation connection point of the first connecting block and the second connecting block through the adjustment mechanism to adjust the position of the three-dimensional strain gauge.

[0018] Through this invention, the core principle of the triaxial strain gauge is to calculate the principal stress and shear stress by measuring the strain in three known directions. The construction personnel can use the adjustment mechanism to ensure that the substrate is rotated to the preset precise angle, thereby avoiding the error of visual judgment when manually pasting and ensuring the theoretical correctness of the three strain gauge directions. Strain gauges installed at the center of the top and bottom plates jointly monitor the overall bending deformation of the box. When the center of the top plate is under compression and the center of the bottom plate is under tension, the box bends downward, and the measured data is a positive bending moment. When the center of the top plate is under tension and the center of the bottom plate is under compression, the box bends upward, and the measured data is a negative bending moment. By comparing the positive and negative bending moments, construction personnel can accurately calculate the magnitude of the overall bending moment and axial force. The web is the primary shear-resistant component. By measuring the differential deformation of strain gauges on the inner and outer sides, the magnitude of the shear force borne by the web can be directly calculated, which construction personnel use to assess the shear resistance of the box girder structure. The haunches, due to their abrupt geometric changes, are areas with complex stresses and are prone to shear cracks or diagonal cracks. Placing strain gauges at these locations allows for the earliest detection of abnormalities and the prevention of failure.

[0019] In areas such as the inner side of the box girder web, the stress is not a simple tension or compression, but a complex state of combined compression, tension, and shear. Triaxial strain gauges can simultaneously measure strain in three directions, thus helping construction personnel to accurately calculate the magnitude and direction of the principal stress and the maximum shear stress at that point. This allows construction personnel to prevent damage to the box girder in advance. The data measured by strain gauges at various locations can facilitate monitoring personnel in preventing damage to the box girder.

[0020] Preferably, the strain gauge at the haunch on the bottom surface of the top plate is used to monitor the stress concentration effect, and the strain gauge at the center of the top surface of the bottom plate is used to monitor the overall bending deformation.

[0021] This invention enables monitoring at the top plate's armpits to prevent localized cracking, and monitoring at the bottom plate's center to ensure overall stability.

[0022] Preferably, the triaxial strain rosettes on the inner side of the web are arranged at angles of 0°, 45°, and 90° for calculating principal stresses and shear stresses.

[0023] Through this invention, principal stress and shear stress can be accurately analyzed to determine the complex stress state inside the web, providing core data support for structural safety.

[0024] Preferably, temperature compensation strain gauges are arranged in the stress-free areas of the box.

[0025] Through this invention, strain gauges used for temperature compensation can eliminate measurement errors caused by temperature changes, ensuring the authenticity and accuracy of strain data. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the main body of the device in Example 1.

[0027] Figure 2 This is a schematic diagram of the triaxial strain flower in Example 1.

[0028] Figure 3 This is a schematic diagram of the frame in Example 1.

[0029] Figure 4 This is a schematic diagram of the slider in Example 1.

[0030] Figure 5 This is a schematic diagram of the threaded blind hole in Example 1.

[0031] Figure 6 This is a schematic diagram of the installation position of the strain gauge adjustment device in Example 1. Detailed Implementation

[0032] To further understand the content of this invention, a detailed description of the invention is provided in conjunction with embodiments. It should be understood that the embodiments are merely illustrative and not limiting of the invention.

[0033] Example 1 like Figure 1-5 As shown, this embodiment provides a strain gauge adjustment device, including a device body 100. The device body 100 includes a frame 110, and a base plate 150 is provided inside the frame 110. A plurality of strain gauges 120 are provided at one end face of the base plate 150. The base plate 150 and the plurality of strain gauges 120 together form a triaxial strain flower. A first connecting block 230 is provided on the side wall of the base plate 150, and a second connecting block 350 rotatably connected to the first connecting block 230 is provided on the inner side wall of the frame 110. An adjustment mechanism is provided on the side wall of the frame 110, which is used to push the base plate 150 to rotate along the rotatable connection.

[0034] In this embodiment, when using the strain gauge adjustment device, the construction worker first fixes the frame 110 to the box by passing screws through the bolt holes 170 at the four corners of the frame 110. After the frame 110 is fixed, the construction worker rotates the bolt 130 located below the frame 110, so that the bolt 130 enters the threaded blind hole 510 on the mounting block 140. During the process of the bolt 130 entering the threaded blind hole 510, the bolt 130 will push the sliding member 380 to move along the strip-shaped through hole 320. At this time, the cylinder 410 on the sliding member 380 will press against the base plate 150. The inclined surface 210 at the end allows the substrate 150 to rotate along the rotational connection between the first connecting block 230 and the second connecting block 350, thereby fine-tuning the position of the substrate 150 and preventing the triaxial strain gauge on the substrate 150 from tilting and affecting subsequent measurement data. The adjustment device includes the substrate 150, on which the triaxial strain gauge is first firmly attached. This structure provides better rigid support, allowing the strain to be transferred more completely and losslessly from the concrete structure surface to the strain gauge through the device base, reducing signal attenuation caused by adhesive layer thickness or unevenness.

[0035] After the sliding member 380 located below the frame 110 is adjusted by the construction personnel, the construction personnel then rotate the bolt 130 located on the side wall of the frame 110. As the bolt 130 enters the mounting block 140, it pushes the sliding member 380, causing the cylinder 410 on the sliding member 380 to press against the inclined surface 210 on the side wall of the substrate 150. This, in conjunction with the sliding member 380 below the frame 110, clamps and fixes the substrate 150, preventing the substrate 150 from moving.

[0036] In this embodiment, the adjustment mechanism includes a pushing component disposed on the adjacent side wall of the frame 110. The pushing component includes a mounting block 140. A strip-shaped through hole 320 is provided on the side wall of the frame 110 along the length direction of the side wall of the frame 110. One end of the mounting block 140 near the strip-shaped through hole 320 is recessed inward to form a threaded blind hole 510. A sliding member 380 is provided at the strip-shaped through hole 320 and passes through the strip-shaped through hole 320. A bolt 130 is provided at the threaded blind hole 510 and is used to push the sliding member 380 to move along the strip-shaped through hole 320.

[0037] In this embodiment, the construction worker rotates the bolt 130, causing the nut on the bolt 130 to push the round block 430 to move. The movement of the round block 430 causes the connecting rod 420 to move along the strip-shaped through hole 320. The cross-section of the strip-shaped through hole 320 is rectangular, and the cross-section of the connecting rod 420 is also rectangular, thereby preventing the connecting rod 420 from shaking when moving and improving the stability of the sliding member 380 when moving.

[0038] In this embodiment, the sliding member 380 includes a connecting rod 420 passing through the strip-shaped through hole 320. The end of the connecting rod 420 near the bolt 130 is provided with a round block 430, and the round block 430 is provided with a limiting hole 440 for the bolt 130 to pass through. The end of the connecting rod 420 away from the round block 430 is provided with a cylinder 410. The end of the substrate 150 near the cylinder 410 is provided with an inclined surface 210 arranged along the length direction of the side wall of the substrate 150.

[0039] In this embodiment, the thickness of the round block 430 is less than the width of the strip-shaped through hole 320. When installing the sliding component 380, the construction personnel pass the connecting rod 420 and the round block 430 through the strip-shaped through hole 320 on the frame 110, and then insert the bolt 130 through the limiting hole 440 on the round block 430 into the threaded blind hole 510 on the mounting block 140; thus, it is convenient for the installer to install the sliding component 380 onto the frame 110.

[0040] In this embodiment, the frame 110 is rectangular in shape, and each of the four corners of the frame 110 is provided with a connecting plate 160 connected to the frame 110, and the connecting plate 160 is provided with bolt holes 170.

[0041] In this embodiment, when the construction personnel connect the frame 110 to the box, they align the connecting plates 160 at the four corners of the frame 110 with the pre-embedded holes on the box, so that the bolt holes 170 on the connecting plates 160 are connected to the pre-embedded holes. Then, the screws are inserted into the pre-embedded holes through the bolt holes 170 to fix the frame 110 to the box.

[0042] In this embodiment, the second connecting block 350 is provided with two parallel mounting plates 340, and the mounting plate 360 ​​is provided with mounting holes 360; the two mounting plates 340 and the second connecting block together form a limiting interval 370 for the first connecting block 230 to extend into; the first connecting block 230 is provided with a rotating column 240 that passes through the mounting hole 360.

[0043] In this embodiment, the second connecting block 350 is welded to the two mounting plates 340. When assembling the substrate 150 and the frame 110, the first connecting block 230 on the substrate 150 is first inserted into the limiting interval 370, and then the rotating column 240 is glued to the first connecting block 230 through the mounting hole 360. This makes it convenient for the installer to connect the substrate 150 and the frame 110.

[0044] In this embodiment, the sliding member 380 is made of stainless steel, and the cylinder 410 and the block 430 are welded to the connecting rod 420.

[0045] Through this embodiment, the stainless steel structure has high strength, which can extend the service life of the sliding component 380.

[0046] like Figure 6 As shown, this embodiment provides a method for arranging dynamic strain test points in a box. The steps are as follows: First, one strain gauge 120 is arranged at the center of the bottom surface of the top plate of the box and at the armholes on both sides. Then, one strain gauge 120 is arranged at the center of the top surface of the bottom plate of the box. Strain gauges 120 are arranged on the inner and outer sides of the box web and at the upper and lower armholes. The inner side uses a strain gauge 120 adjustment device. The construction personnel first fix the strain gauge 120 adjustment device on the inner side of the box web. After the strain gauge 120 adjustment device is fixed, the base plate 150 is pushed to rotate along the first connecting block 230 and the second connecting block 350 through the adjustment mechanism to adjust the position of the three-dimensional strain gauge.

[0047] In this embodiment, the core principle of the triaxial strain gauge is to calculate the principal stress and shear stress by measuring the strain in three known directions. The construction personnel use the adjustment mechanism to ensure that the substrate is rotated to the preset precise angle, thereby avoiding the error of visual judgment when manually pasting and ensuring the theoretical correctness of the three strain gauges in the 120° direction. Strain gauges 120, installed at the center of the top slab and the center of the bottom slab, jointly monitor the overall bending deformation of the box. When the center of the top slab is under compression and the center of the bottom slab is under tension, the box bends downward, and the measured data is a positive bending moment. When the center of the top slab is under tension and the center of the bottom slab is under compression, the box bends upward, and the measured data is a negative bending moment. By comparing the positive and negative bending moments, construction personnel can accurately calculate the magnitude of the overall bending moment and axial force. The web is the main shear-resistant component. By measuring the differential deformation, the inner and outer strain gauges 120 can directly calculate the magnitude of the shear force borne by the web, which construction personnel use to assess the shear resistance of the box girder structure. The haunches, due to their abrupt geometric changes, are areas with more complex stresses and are prone to shear cracks or diagonal cracks. Placing strain gauges 120 at these locations allows for the earliest detection of abnormalities and the prevention of failure.

[0048] In areas such as the inner side of the box girder web, the stress is not simple tension and compression, but a complex state of combined compression, tension, and shear. A triaxial strain gauge can simultaneously measure strain in three directions, helping construction personnel to accurately calculate the magnitude and direction of the principal stresses and the maximum shear stress at that point. This allows construction personnel to prevent damage to the box girder in advance. Data measured by strain gauges at various locations (120mm) facilitates monitoring and preventative measures against box girder damage.

[0049] In this embodiment, the strain gauge 120 at the underside of the top plate is used to monitor the stress concentration effect, and the strain gauge 120 at the center of the top surface of the bottom plate is used to monitor the overall bending deformation.

[0050] In this embodiment, monitoring at the top plate's haunch prevents localized cracking, while monitoring at the bottom plate's center ensures overall stability.

[0051] In this embodiment, the triaxial strain rosettes on the inner side of the web are arranged at angles of 0°, 45°, and 90°, which are used to calculate the principal stress and shear stress.

[0052] Through this embodiment, principal stress and shear stress can be accurately analyzed to determine the complex stress state inside the web, providing core data support for structural safety.

[0053] In this embodiment, temperature compensation strain gauges 120 are arranged in the stress-free area of ​​the box.

[0054] Through this embodiment, the strain gauge 120 used for temperature compensation can eliminate measurement errors caused by temperature changes, ensuring the authenticity and accuracy of strain data.

[0055] It is readily understood that those skilled in the art can combine, split, or reorganize the embodiments provided in this application to obtain other embodiments, all of which do not exceed the protection scope of this application.

[0056] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the embodiments shown are only part of the embodiments of the present invention. The actual structure is not limited thereto. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A strain gauge adjustment device, characterized in that: The device includes a main body (100), which includes a frame (110). A base plate (150) is provided inside the frame (110). Multiple strain gauges (120) are provided at one end face of the base plate (150). The base plate (150) and the multiple strain gauges (120) together form a triaxial strain flower. A first connecting block (230) is provided on the side wall of the base plate (150). A second connecting block (350) is provided on the inner side wall of the frame (110) and is rotatably connected to the first connecting block (230). An adjustment mechanism is provided on the side wall of the frame (110). The adjustment mechanism is used to push the base plate (150) to rotate along the rotatable connection.

2. The strain gauge adjustment device according to claim 1, characterized in that: The adjustment mechanism includes a push assembly disposed on the adjacent side wall of the frame (110). The push assembly includes a mounting block (140). A strip-shaped through hole (320) is provided on the side wall of the frame (110) along the length direction of the side wall of the frame (110). The end of the mounting block (140) near the strip-shaped through hole (320) is recessed inward to form a threaded blind hole (510). A sliding member (380) is provided at the strip-shaped through hole (320) and a bolt (130) is provided at the threaded blind hole (510) to extend into the threaded blind hole (510) and to push the sliding member (380) to move along the strip-shaped through hole (320).

3. The strain gauge adjustment device according to claim 2, characterized in that: The sliding member (380) includes a connecting rod (420) passing through a strip-shaped through hole (320), a round block (430) is provided at one end of the connecting rod (420) near the bolt (130), and a limiting hole (440) is provided at the round block (430) for the bolt (130) to pass through; a cylinder (410) is provided at one end of the connecting rod (420) away from the round block (430); and an inclined surface (210) is provided at one end of the substrate (150) near the cylinder (410) along the length direction of the side wall of the substrate (150).

4. The strain gauge adjustment device according to claim 3, characterized in that: The frame (110) is rectangular in shape. Each of the four corners of the frame (110) is provided with a connecting plate (160) that is connected to the frame (110). The connecting plate (160) is provided with bolt holes (170).

5. The strain gauge adjustment device according to claim 4, characterized in that: The second connecting block (350) is provided with two parallel mounting plates (340), and the mounting plates (360) are provided with mounting holes (360); the two mounting plates (340) and the second connecting block together form a limiting range (370) into which the first connecting block (230) extends; the first connecting block (230) is provided with a rotating column (240) that passes through the mounting hole (360).

6. The strain gauge adjustment device according to claim 5, characterized in that: The sliding element (380) is made of stainless steel, and the cylinder (410) and the block (430) are welded to the connecting rod (420).

7. A method for arranging dynamic strain test points in a test chamber, implemented by a strain gauge adjustment device as described in any one of claims 1-6, comprising the following steps: First, one strain gauge (120) is placed at the center of the bottom surface of the top plate of the box and at the armholes on both sides. Then, one strain gauge (120) is placed at the center of the top surface of the bottom plate of the box. Strain gauges (120) are placed on the inner and outer sides of the web plate of the box and at the upper and lower armholes. Among them, the inner side uses a strain gauge (120) adjustment device. The construction personnel first fix the strain gauge (120) adjustment device on the inner side of the web plate of the box. After the strain gauge (120) adjustment device is fixed, the base plate (150) is pushed to rotate along the first connecting block (230) and the second connecting block (350) through the adjustment mechanism to adjust the position of the three-dimensional strain gauge.

8. The method for arranging dynamic strain test points in a box according to claim 7, characterized in that: The strain gauge (120) at the underside of the top plate is used to monitor stress concentration effect, and the strain gauge (120) at the center of the top surface of the bottom plate is used to monitor overall bending deformation.

9. The method for arranging dynamic strain test points in a box according to claim 8, characterized in that: The triaxial strain rosettes on the inner side of the web are arranged at angles of 0°, 45°, and 90°, and are used to calculate the principal stresses and shear stresses.

10. The method for arranging dynamic strain test points in a box according to claim 9, characterized in that: Temperature compensation strain gauges (120) are arranged in the stress-free area of ​​the box.

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