Bridge deflection and strain monitoring device and method

Abstract

This invention discloses a bridge deflection and strain monitoring device and method. The device includes a control terminal, a millimeter-wave radar device, and multiple measuring points evenly spaced at the bottom of the bridge. Each millimeter-wave radar device can transmit a millimeter-wave radar signal to the measuring point and receive the echo signal, which is then transmitted to the control terminal for signal data processing. This invention achieves monitoring through the control terminal, millimeter-wave radar device, and measuring points, eliminating the need for complex wiring; it employs non-contact measurement, is unaffected by temperature and humidity, and enables continuous monitoring around the clock; the positions of the millimeter-wave radar device and control terminal can be flexibly adjusted, making it suitable for different types of bridges. In practice, the ranging accuracy of this invention can be controlled within ±0.5mm, keeping the deflection error within 1mm and the strain error within 5 με, thus improving monitoring accuracy.

Description

Technical Field

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

[0002] As a core component of transportation infrastructure, the structural stability of bridges directly impacts traffic safety. During their long service life, bridges are continuously subjected to multiple factors, including vehicle loads, environmental effects, and material aging, making them prone to hidden damage such as deflection and strain accumulation. Failure to monitor these deformations and strain accumulations in a timely manner can lead to serious safety accidents and pose significant safety hazards. Therefore, it is essential to monitor the deflection and strain of bridges during their service life to ensure timely reinforcement and improve safety.

[0003] Currently, bridge deflection and strain monitoring mainly relies on contact sensors such as strain gauges and displacement meters. These contact monitoring methods have the following significant shortcomings: First, the monitoring length of existing strain gauges or displacement meters is often short, while bridges are often long. In actual monitoring, a large number of sensors need to be deployed, resulting in high monitoring costs, complex wiring, and easy sensor damage. In addition, existing strain gauge and displacement meter monitoring is easily affected by vibration interference, making it difficult to achieve continuous measurement across the entire cross section. Furthermore, they have poor adaptability and are prone to monitoring interruptions in harsh environments. Summary of the Invention

[0004] In view of this, the first objective of the present invention is to provide a bridge deflection and strain monitoring device, and the second objective is to provide a bridge deflection and strain monitoring method.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: The bridge deflection and strain monitoring device of the present invention It includes a control terminal, two millimeter-wave radar devices installed on the piers on both sides of the bridge, and multiple measuring points evenly spaced at the bottom of the bridge. Each of the millimeter-wave radar devices transmits millimeter-wave radar signals to the measuring point, receives echo signals, and then transmits the echo signals to the control terminal.

[0006] More preferably, the spacing between the measuring points is 1 / 20 to 1 / 15 of the bridge span; the vertical distance between the millimeter-wave radar device and the bottom of the bridge is 1 / 4 to 3 / 4 of the bridge span, and the height difference between the millimeter-wave radar device and the ground or water surface is greater than 3 m. The measuring points are evenly spaced and fixed to the bottom surface of the bridge to ensure that they deform synchronously with the main beam of the bridge; the millimeter-wave radar device is located at a height of more than 3 m above the ground or water surface to reduce interference from ground debris, vehicles, or water surface fluctuations on the millimeter-wave radar device.

[0007] This invention proposes a method for monitoring bridge deflection and strain. The monitoring device used in the method includes a control terminal, two millimeter-wave radar devices installed on the piers on both sides of the bridge, and multiple measuring points evenly spaced at the bottom of the bridge. Each millimeter-wave radar device transmits a millimeter-wave radar signal to the measuring point and receives the echo signal, and then transmits the echo signal to the control terminal. The monitoring method includes the following: The first step is to determine the location of the first millimeter-wave radar device, with its coordinates at the origin, denoted as (0,0); and then determine the location of the second millimeter-wave radar device, with its coordinates as (…). X 1 , Y 1 ), to obtain the distance between two millimeter-wave radar devices, denoted as L 0 ;in, X The direction is in the direction of the bridge. Y The direction is the direction of gravity on the bridge; The second step is to obtain the distance from each millimeter-wave radar device to any measurement point, and then obtain the coordinates of each measurement point based on the distance measurements. For example, taking any measurement point A: the distances between the two millimeter-wave radar devices and measurement point A are denoted as follows: L 1 and L 2 Then the coordinates of measuring point A are ( X A , Y A The following formula is satisfied: X A 2 + Y A 2 = L 1 2 (1); ( X 1 - X A ) 2 +( Y 1 - Y A ) 2 =L 2 2 (2); Based on formulas (1) and (2), the coordinates of measuring point A are determined, and the specific formulas are as follows: (3); (4); In formula (3) above, a = 4 L 0 2 b=-4 Y 1 ( L 0 2 + L 1 2 -L 2 2 );c =( L 0 2 +L 1 2 -L 2 2 )- 4 L 1 2 X 0 2 ; The third step involves fitting the bridge's alignment based on the coordinates of each measuring point from the second step. The fitted bridge alignment is then compared to the initial alignment to obtain the bridge's deflection curve. Y = f ( x ); The fourth step is to take the second derivative of the deflection curve to obtain the curvature of the bridge. ρ The curvature formula is as follows: 1 / ρ = f "( x ); The fifth step is to determine the distance from different locations at the bottom of the bridge to the bridge's neutral axis based on the cross-sectional characteristics at various points on the bridge. h = h ( x The strain ε at the bottom of the bridge beam is calculated, and the formula for the strain at the bottom of the beam is as follows: ε( x )=- f″ ( x )× h ( x ).

[0008] Compared with existing technologies, the advantages of this invention are as follows: This invention achieves monitoring through a control terminal, millimeter-wave radar device, and measuring points, eliminating the need for complex wiring; furthermore, it employs non-contact measurement during monitoring, unaffected by temperature and humidity, and can penetrate rain and fog, enabling continuous monitoring around the clock; moreover, the positions of the millimeter-wave radar device and control terminal can be flexibly adjusted, making it suitable for various types of bridges. In practice, this invention obtains the coordinates of each measuring point through distance measurement, calculates the bridge deflection based on the coordinates and the bridge's initial alignment, and calculates the bridge's curvature and strain based on the bridge deflection and cross-sectional characteristics. During monitoring, the distance measurement accuracy can be controlled within ±0.5mm, thereby keeping the deflection error within 1mm and the strain error within 5 με, improving monitoring accuracy and meeting the requirements for high-precision bridge health assessment. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the layout of measuring points in this invention.

[0010] Figure 2 This is a circuit block diagram of the present invention. Detailed Implementation

[0011] 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.

[0012] 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.

[0013] 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.

[0014] like Figure 1-2As shown, the present invention proposes a bridge deflection and strain monitoring device, including a control terminal, two millimeter-wave radar devices installed on the piers on both sides of the bridge 1 (i.e., installed on the piers on both sides below the bridge, with one millimeter-wave radar device installed on each pier), and multiple measuring points 2 evenly spaced at the bottom of the bridge 1. Each millimeter-wave radar device can transmit millimeter-wave radar signals to the measuring point 2 and receive echo signals, and then transmit the echo signals to the control terminal for data processing.

[0015] During actual installation, one millimeter-wave radar device (denoted as 3A) is installed on the pier with the smaller chainage, and its position is designated as the origin. The other millimeter-wave radar device (denoted as 3B) is installed on the pier with the larger chainage, and its position is determined accordingly. Each millimeter-wave radar device is installed at a height of at least 3 meters above the ground or water surface to minimize interference from ground debris, vehicles, or water fluctuations. The vertical distance between the millimeter-wave radar device and the bottom of bridge 1 is equal to the bridge span. L The span of the measuring point is 1 / 4 to 3 / 4; measuring points 2 are fixed at equal intervals at the bottom of bridge 1, so that when bridge 1 deforms, it deforms synchronously with the main body of bridge 1. The distance between two adjacent measuring points 2 is the bridge span. L 1 / 20 to 1 / 15 of.

[0016] In actual measurements, steel plates are placed at each measuring point 2 to distinguish the echoes from those at surrounding locations, thereby determining the distance from each millimeter-wave radar device to that measuring point and facilitating the acquisition of the coordinates of that point. This invention also proposes a method for monitoring bridge deflection and strain, which employs the bridge deflection and strain monitoring device described in this embodiment, specifically including the following: The first step is to determine the location of the millimeter-wave radar device installed on the small pier, denoted as (0,0), and mark it as (0,0). X 1 , Y 1 ), and obtain the distance between the two millimeter-wave radar devices. L 0 ;in, X The direction is in the direction of the bridge. Y The direction is the direction of gravity of bridge 1. L 0 represents the distance between the two millimeter-wave radar devices along the direction of the bridge; The second step is to obtain the distance from each millimeter-wave radar device to any measurement point, based on the distances from two millimeter-wave radar devices to the same measurement point and the distance between the two millimeter-wave radar devices. L 0. Calculate and determine the coordinates of the measurement, taking any measurement point A as an example: The distance between the millimeter-wave radar device at the origin and the measuring point A is L 1 The distance from another millimeter-wave radar device to the measured A is L 2 Then the coordinates of measuring point A are ( X A , Y A The following formula is satisfied: X A 2 + Y A 2 = L 1 2 (1); ( X 1 - X A ) 2 +( Y 1 - Y A ) 2 =L 2 2 (2); Based on formulas (1) and (2), the coordinates of measuring point A are calculated using the coordinates of each millimeter-wave radar device and the spacing L0. Wherein, Y A Satisfying formula (3) and X A It satisfies formula (4), as follows: (3); In formula (3) above, a = 4 L 0 2 b = -4 Y 1 ( L 0 2 + L 1 2 -L 2 2 ); c = ( L 0 2 +L 1 2 -L 2 2 )- 4 L 12 X 0 2 (4); The third step involves fitting the bridge's alignment during monitoring based on the coordinates of each measuring point obtained in the second step. The fitted monitoring alignment is then compared with the bridge's initial alignment to obtain the bridge's deflection curve. Y = f ( x ); The fourth step is to take the second derivative of the deflection curve to obtain the curvature of the bridge. ρ The curvature formula is: 1 / ρ = f "( x ); The fifth step is to obtain the cross-sectional properties (including the elastic modulus) at various locations on the bridge (including the cross-sectional properties of the bridge at each measuring point). E and the moment of inertia of the bridge section about the central axis I Determine the distance from different locations at the bottom of the bridge to the bridge's neutral axis. h = h ( x ); Step 6: Based on the distance formulas from different locations to the bridge's central axis from Step 5 and the curvature formula from Step 4, calculate and determine the beam bottom strain ε. The beam bottom strain formula is as follows: ε( x )=- f″ ( x )× h ( x ) Compared with existing technologies, the advantages of this invention are as follows: This invention can achieve monitoring through a control terminal, two millimeter-wave radar devices, and several measuring points, eliminating the need for complex wiring; furthermore, it employs non-contact measurement during monitoring, unaffected by temperature and humidity, and can penetrate rain and fog, enabling continuous monitoring around the clock; moreover, the positions of the millimeter-wave radar devices and measuring points 2 can be flexibly adjusted, making it suitable for various types of bridges. In practice, this invention obtains the coordinates of each measuring point through distance measurement, calculates the bridge deflection based on the coordinates and the initial alignment of the bridge, and calculates the bridge curvature and strain based on the bridge deflection and cross-sectional characteristics. During monitoring, the distance measurement accuracy can be controlled within ±0.5 mm, thereby controlling the deflection error within 1 mm and the strain error within 5 με, improving monitoring accuracy and meeting the requirements for high-precision bridge health assessment.

[0017] 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 deflection and strain monitoring device, characterized in that: It includes a control terminal, two millimeter-wave radar devices installed on the piers on both sides of the bridge, and multiple measuring points evenly spaced at the bottom of the bridge. Each of the millimeter-wave radar devices transmits millimeter-wave radar signals to the measuring point, receives echo signals, and then transmits the echo signals to the control terminal.

2. The bridge deflection and strain monitoring device according to claim 1, characterized in that: The spacing between the measuring points is 1 / 20 to 1 / 15 of the bridge span; the vertical distance between the millimeter-wave radar device and the bottom of the bridge is 1 / 4 to 3 / 4 of the bridge span, and the height difference between the device and the ground or water surface is greater than 3 m.

3. A method for monitoring bridge deflection and strain, characterized in that: The monitoring method employs the bridge deflection and strain monitoring device as described in claims 1-2, and includes the following: The first step is to determine the location of the first millimeter-wave radar device, with its coordinates at the origin, denoted as (0,0); and then determine the location of the second millimeter-wave radar device, with its coordinates as (…). X 1 , Y 1 ), to obtain the distance between two millimeter-wave radar devices, denoted as L 0 ; in, X The direction is in the direction of the bridge. Y The direction is the direction of gravity on the bridge; The second step is to obtain the distance from each millimeter-wave radar device to any measurement point, and then obtain the coordinates of each measurement point based on the distance measurements. For example, taking any measurement point A: the distances between the two millimeter-wave radar devices and measurement point A are denoted as follows: L 1 and L 2 Then the coordinates of measuring point A are ( X A , Y A The following formula is satisfied: X A 2 + Y A 2 = L 1 2 （1）； ( X 1 - X A ) 2 +( Y 1 - Y A ) 2 =L 2 2 （2）； Based on formulas (1) and (2) and the coordinate information of the millimeter-wave radar device, the spacing between the millimeter-wave radar devices L 0 The coordinates of measuring point A are calculated using the following formula: （3）； （4）； In formula (3), a=4 L 0 2 b=-4 Y 1 ( L 0 2 +L 1 2 -L 2 2 );c =( L 0 2 +L 1 2 -L 2 2 )- 4 L 1 2 X 0 2 ; The third step involves fitting the bridge's alignment based on the coordinates of each measuring point from the second step. The fitted bridge alignment is then compared to the initial alignment to obtain the bridge's deflection curve. Y = f ( x ); The fourth step is to take the second derivative of the deflection curve to obtain the curvature of the bridge. ρ The curvature formula is as follows: 1 / ρ = f″ ( x )； The fifth step is to determine the distance from different locations at the bottom of the bridge to the bridge's neutral axis based on the cross-sectional characteristics at various points on the bridge. h = h ( x ), calculate the strain up to the bottom of the bridge beam. ε The formula for the strain at the bottom of the beam is as follows: e( x )=- f″ ( x )× h ( x )。

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