Bridge strain monitoring device and monitoring method

Abstract

The application discloses a bridge strain monitoring device, which comprises a grating displacement meter, an outer protective tube, an extension rod and a temperature sensor, the extension rod and the grating displacement meter are coaxially arranged in the outer protective tube, the measuring head at the end of the measuring rod of the grating displacement meter is located in the positioning groove of the extension rod, and the length of the outer protective tube is 3m-5m; the temperature sensor is arranged in the outer protective tube; one end of the outer protective tube is sealingly provided with a first end cover, and the other end of the outer protective tube is sealingly provided with a second end cover; the second end cover is provided with a through hole, and the cable of the temperature sensor and the grating displacement meter is led out of the through hole and sealingly connected with the through hole. The application increases the effective strain measurement length by arranging the extension connecting rod, realizes long gauge length strain monitoring, significantly reduces the number of strain gauges, and further reduces the bridge strain cost; in addition, the dynamic acquisition frequency of the application can reach 50 Hz, and more reliable data is provided for the bridge safety evaluation; furthermore, the application uses temperature compensation strain to ensure the accurate monitoring of the bridge strain.

Description

Technical Field

[0001] This invention relates to the field of bridge strain monitoring technology, and in particular to a bridge strain monitoring device and monitoring method. Background Technology

[0002] In recent years, with the general increase in the service life of bridges, more and more bridges have developed latent damage or structural defects such as strain accumulation. Therefore, during the service life of bridges, bridge strain monitoring is one of the key indicators in bridge performance monitoring projects, and its accuracy directly affects the assessment of the bridge's health status. Existing bridge strain monitoring mainly uses vibrating wire and fiber optic grating strain gauges, but the detection range of these two types of strain gauges is usually within 250 mm, which is easily affected by local stress concentration or small deformations, making it difficult to capture the global strain distribution characteristics of the bridge, unable to correlate with the overall deformation of the bridge, and resulting in large measurement errors. In addition, existing monitoring methods are greatly affected by temperature, resulting in significant errors. Summary of the Invention

[0003] In view of this, the first objective of the present invention is to provide a bridge strain monitoring device, and the second objective of the present invention is to provide a bridge strain monitoring method.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: The bridge strain monitoring device of the present invention includes a grating displacement meter, an outer protective tube, an extension rod, and a temperature sensor. The extension rod and the grating displacement meter are coaxially arranged inside the outer protective tube. The probe at the end of the grating displacement meter is located in the positioning groove of the extension rod. The length of the outer protective tube is 3m-5m. The temperature sensor is installed inside the outer protective tube; a first end cap is sealed at one end of the outer protective tube, and a second end cap is sealed at the other end. The second end cap has a through hole, through which the cables of the temperature sensor and the grating displacement meter pass and are sealed to the through hole.

[0005] Preferably, the outer protective tube is provided with multiple support and positioning rings at intervals, and the extension rod passes through the multiple support and positioning rings. In this invention, the support and positioning rings provide support and positioning for the extension rod, ensuring the coaxiality between the extension rod and the measuring rod of the grating displacement gauge, thereby ensuring monitoring accuracy.

[0006] Preferably, the inner sealing head of the first end cap has a first positioning hole, and one end of the extension rod is inserted into the first positioning hole. The positioning hole at the end of the first end cap can position and fix the extension rod.

[0007] Preferably, the inner sealing head of the second end cap has a second positioning hole, and the end of the grating displacement meter is located in the second positioning hole. The second end cap can position the grating displacement meter.

[0008] Preferably, the outer protective tube is a stainless steel tube, and the extension rod is a lightweight carbon fiber rod.

[0009] This invention proposes a bridge strain monitoring method. The bridge strain monitoring device includes a grating displacement gauge, an outer protective tube, an extension rod, and a temperature sensor. The extension rod and the grating displacement gauge are coaxially arranged inside the outer protective tube. The probe of the grating displacement gauge is located in the positioning groove of the extension rod at the end of the probe rod. The length of the outer protective tube is 3m-5m. The temperature sensor is set on the inner wall of the outer protective tube and close to the grating displacement gauge. A first end cap is sealed at one end of the outer protective tube, and a second end cap is sealed at the other end. The second end cap has a through hole, through which the cables of the temperature sensor and the grating displacement gauge pass and are sealed to the through hole. The method includes the following specific steps: multiple bridge strain monitoring devices are arranged and installed at the bottom of the bridge; the cable of each bridge strain monitoring device is connected to a controller; the displacement and temperature of each bridge strain monitoring device are acquired; and the bridge strain of each bridge strain monitoring device is calculated. e The formula is as follows: ε=(Δx+αΔT) / L ; In the formula, Δx The displacement change value of the bridge strain monitoring device. ΔT The temperature change value of the bridge strain monitoring device. α The difference in the coefficient of linear expansion between the bridge and the bridge strain monitoring device. L The gauge length is 3m to 5m for the bridge strain gauge.

[0010] Compared with the prior art, the advantages of the present invention are as follows: This invention increases the effective strain measurement length by using an extended connecting rod, enabling long gauge length strain monitoring (3-5 m), significantly reducing the number of strain gauges and thus lowering bridge strain monitoring costs. Furthermore, the dynamic acquisition frequency of this invention can reach 50 Hz, providing more reliable data for bridge safety assessment. Moreover, this invention integrates a temperature sensor within the outer protective casing, using temperature to compensate for strain during monitoring, ensuring accurate bridge strain monitoring and improving monitoring precision. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the structure of the present invention.

[0012] Figure 2 This is a partially enlarged view of the present invention.

[0013] Figure 3 This is a circuit block diagram of the present invention.

[0014] Figure 4 This is a schematic diagram illustrating the application of the present invention on a bridge. Detailed Implementation

[0015] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. These embodiments are implemented based on the technical solution of the present invention, and detailed implementation methods and specific operation processes are given. However, the scope of protection of the present invention is not limited to the following embodiments.

[0016] It should be noted that, in the description of this invention, relational terms such as “first” and “second” are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0017] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0018] like Figure 1-3 As shown, this invention proposes a bridge strain monitoring device, including a grating displacement gauge 3, an outer protective tube 1, an extension rod 2, and a temperature sensor 8. The extension rod 2 and the grating displacement gauge 3 are coaxially arranged inside the outer protective tube 1. The probe at the end of the measuring rod of the grating displacement gauge 3 is located in the positioning groove 7 of the extension rod 2. The length of the outer protective tube 1 is 3m-5m. The temperature sensor 8 is arranged inside the outer protective tube 1. The temperature sensor 8 is preferably a grating temperature sensor and is integrated with the grating displacement gauge 3. A first end cap 4a is sealed at one end of the outer protective tube 1, and a second end cap 5a is sealed at the other end. The second end cap 5a has a perforation through which the cables of the temperature sensor 8 and the grating displacement gauge 3 pass through the perforation. The cables of the temperature sensor 8 and the grating displacement gauge 3 are sealed to the perforation to ensure the airtightness of the outer protective tube 1, thereby protecting the grating displacement gauge 3.

[0019] In actual installation, both the first end cap 4a and the second end cap 5a are T-shaped structures. The inner sealing head of the first end cap 4a has a first positioning hole 4b, and the right end of the extension rod 2 is inserted into the first positioning hole 4b. The inner sealing head of the second end cap 5a has a second positioning hole 5b, and the end of the grating displacement meter 3 is located in the second positioning hole 5b. The first positioning hole 4b and the second positioning hole 5b are arranged coaxially to ensure the coaxiality of the grating displacement meter 3 and the extension rod 2.

[0020] During actual installation, multiple support and positioning rings 6 are spaced apart inside the outer protective tube 1, through which the extension rod 2 passes. The support and positioning rings 6 provide support and positioning for the extension rod 2, further ensuring the coaxiality between the extension rod 2 and the measuring rod of the grating displacement gauge 3, thereby ensuring monitoring accuracy.

[0021] In actual processing, the outer protective tube 1 is preferably a stainless steel tube with a thickness of 2 mm to 3 mm, and the support positioning ring 6 is a stainless steel ring, which is fixed on the inner wall of the outer protective tube 1; the extension rod 2 is a lightweight carbon fiber rod to reduce weight, and the extension rod 2 significantly increases the gauge length of the bridge strain monitoring device, so that the gauge length of the present invention can reach 5 m.

[0022] This invention proposes a method for monitoring bridge strain, which includes the following: Multiple bridge strain monitoring devices were arranged according to Figure 4 The strain monitoring devices are arranged and fixed on the bottom surface of the bridge, so that each strain monitoring device deforms synchronously with the deformation of the bridge. The cables of each strain monitoring device are connected to the controller. When the bridge undergoes slight deformation, the readings of the grating displacement gauges 3 of the strain monitoring devices change. The controller processes the signals from the grating displacement gauges 3 and the temperature signals within the strain monitoring devices to calculate the strain of each device. e The formula is as follows: ε=(Δx+αΔT) / L ; In the formula, Δx The displacement change value of the bridge strain monitoring device. ΔT The temperature change value of the bridge strain monitoring device. α The difference in the coefficient of linear expansion between the bridge and the bridge strain monitoring device. L The gauge length is 3m to 5m for the bridge strain gauge.

[0023] It should be noted that the controller in this invention has a built-in data acquisition module, data processing module, and display module, and programmable logic controllers (PLCs) and industrial control computers are preferred. Of course, the controller of this invention can also be equipped with a wireless communication module to connect with a remote terminal, receive control commands from the remote terminal, and provide feedback on relevant parameters of the real-time working status, enabling bridge pipeline departments to understand the bridge's condition in a timely manner.

[0024] This invention increases the effective strain measurement length by setting an extended connecting rod, realizing long gauge length strain monitoring (gauge length up to 3 m-5 m), significantly reducing the number of strain gauges required (taking a bridge with a span of 30 m as an example, only five sets of the bridge strain monitoring device of this invention are needed, see...). Figure 4This reduces bridge strain costs. Furthermore, the dynamic acquisition frequency of this invention can reach 50 Hz, providing more reliable data for bridge safety assessment. Moreover, this invention integrates a temperature sensor 8 within the outer protective tube 1, using temperature to compensate for strain during strain monitoring, ensuring accurate monitoring of bridge strain and improving monitoring precision.

[0025] Finally, it should be emphasized that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still make modifications to the technical solutions described in the foregoing embodiments without creative effort, or make equivalent substitutions for some of the technical features. Therefore, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A bridge strain monitoring device, comprising a grating displacement meter, characterized in that: It also includes an outer protective tube, an extension rod, and a temperature sensor. The extension rod and the grating displacement meter are coaxially arranged inside the outer protective tube. The probe at the end of the grating displacement meter is located in the positioning groove of the extension rod. The length of the outer protective tube is 3m-5m. The temperature sensor is installed inside the outer protective tube; a first end cap is sealed at one end of the outer protective tube, and a second end cap is sealed at the other end. The second end cap has a through hole, through which the cables of the temperature sensor and the grating displacement meter pass and are sealed to the through hole.

2. The bridge strain monitoring device according to claim 1, characterized in that: The outer protective tube is provided with multiple support and positioning rings at intervals, and the extension rod passes through multiple support and positioning rings.

3. The bridge strain monitoring device according to claim 1, characterized in that: The inner sealing head of the first end cap has a first positioning hole, and one end of the extension rod is inserted into the first positioning hole.

4. The bridge strain monitoring device according to claim 1, characterized in that: The inner sealing head of the second end cap has a second positioning hole, and the end of the grating displacement meter is located in the second positioning hole.

5. The bridge strain monitoring device according to claim 1, characterized in that: The outer protective tube is made of stainless steel, and the extension rod is made of lightweight carbon fiber.

6. A method for monitoring bridge strain, characterized in that: The bridge strain monitoring device according to any one of claims 1-5 specifically includes the following steps: arranging and installing multiple bridge strain monitoring devices at the bottom of the bridge; connecting the cable of each bridge strain monitoring device to a controller; acquiring the displacement and temperature of each bridge strain monitoring device; and calculating the bridge strain of each bridge strain monitoring device. ε The formula is as follows: ε = (Δx + αΔT) / L ； In the formula, Δx The displacement change value of the bridge strain monitoring device. ΔT The temperature change value of the bridge strain monitoring device. α The difference in the coefficient of linear expansion between the bridge and the bridge strain monitoring device. L The gauge length is 3 m to 5 m for the bridge strain gauge.

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