CN115855400A - Sensor for monitoring bridge deflection - Google Patents
Sensor for monitoring bridge deflection Download PDFInfo
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- CN115855400A CN115855400A CN202211613234.4A CN202211613234A CN115855400A CN 115855400 A CN115855400 A CN 115855400A CN 202211613234 A CN202211613234 A CN 202211613234A CN 115855400 A CN115855400 A CN 115855400A
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Abstract
The invention discloses a sensor for monitoring bridge deflection. The sensor comprises an elastic rod body, a strain fiber grating and a temperature fiber grating; the elastic rod body is linear and flexible, a plurality of annular monitoring sections are uniformly arranged along the axial direction of the elastic rod body, and a temperature fiber bragg grating is arranged on the surface of the elastic rod body at a preset distance from each monitoring section; a strain fiber grating is arranged in each notch on the surface of each monitoring section; the four strain fiber gratings of the monitoring section and the corresponding temperature fiber gratings form a monitoring link. The sensor adopts the linear sensor of optical fiber sensing, can effectively solve the problems of data lag, external interference, stability and maintainability in bridge deflection monitoring, and can effectively obtain the dynamic and static deflection deformation of the bridge, thereby more effectively providing data support for the safety evaluation of the bridge structure.
Description
Technical Field
The invention relates to the technical field of bridge deflection monitoring, in particular to a sensor for monitoring bridge deflection.
Background
The linearity of the bridge can directly reflect the structural safety of the bridge. On the one hand, if the beam is deformed too much, the more intense the impact and vibration action which may be generated, and the greater the influence on the driving safety. On the other hand, excessive deformation of the beam may cause damage to the structure of the bridge, and threatens the safety of the whole structure of the bridge. Therefore, the method has great significance for linear monitoring of the bridge. In general, the linear monitoring of the bridge is mainly realized by monitoring the deflection change of the bridge, including the dynamic and static deflection measurement of the bridge. At present, the types of sensors mainly adopted for monitoring the bridge deflection comprise communicating pipe principle type sensors, reflection type photoelectric type sensors, inclination angle type sensors, CCD (charge coupled device) and the like, and the sensors are widely applied to long-term monitoring of the bridge deflection change, so that a certain effect is achieved. However, these types of sensors still have some problems in monitoring changes in bridge deflection. If the sensor of the communicating pipe type is easily influenced by the conditions of liquid expansion, evaporation, liquid leakage and the like in the communicating pipe in the process of monitoring the deflection change, the monitoring precision is reduced; when the reflective photoelectric sensor is adopted, the sensor is very easily interfered by external passing vehicles; the inclination angle sensor is only suitable for the deflection monitoring of the simply supported beam bridge, and the applicable monitoring range is narrow; CCD type monitoring coverage is low, and is easily influenced by external natural environment factors.
In summary, for monitoring of bridge deflection, the existing sensors have the problems of long-term stability, difficulty in maintenance, weak anti-interference capability, lag in monitoring data and the like, and are difficult to accurately acquire bridge deflection changes due to the influence of the factors.
Disclosure of Invention
The present invention is directed to solve the above problems of the background art, and to provide a sensor for monitoring bridge deflection.
The purpose of the invention can be realized by the following technical scheme:
the embodiment of the invention provides a sensor for monitoring bridge deflection, which comprises an elastic rod body, a strain fiber grating and a temperature fiber grating, wherein the strain fiber grating is arranged on the elastic rod body;
the elastic rod body is used as a core rod piece and is flexible in a linear shape, a plurality of annular monitoring sections are uniformly arranged along the axial direction of the elastic rod body, and a temperature fiber grating is arranged on the surface of the elastic rod body at a preset distance from each monitoring section;
four notches are formed in the surface of each monitoring section, the distance between every two adjacent notches on the monitoring section is one fourth of the perimeter of the monitoring section, and each notch is internally provided with a strain fiber grating;
the four strain fiber gratings of the monitoring section and the corresponding temperature fiber gratings form a monitoring link.
The embodiment of the invention also provides a bridge deflection measuring method based on the sensor for monitoring bridge deflection, wherein the sensor for monitoring bridge deflection is arranged along the bridge direction of a target bridge, and the method comprises the following steps:
acquiring monitoring data of each monitoring link; the monitoring data comprises strain measurement data of all strain fiber gratings of the monitoring link, temperature measurement data of temperature fiber gratings and position numbering of the monitoring link;
correcting the strain measurement data according to the temperature measurement data to obtain strain correction data;
calculating the measured deflection value of the position of the monitoring link according to the strain correction data;
and determining the deployment position of the monitoring link in the target bridge according to the position numbering, and corresponding the measured deflection values of all the monitoring links to the deployment position to obtain deflection change data of the target bridge.
Optionally, the strain measurement data is corrected according to the temperature measurement data, and obtaining strain correction data specifically includes:
wherein alpha is f Is the thermal expansion coefficient of each fiber grating, and xi is the thermo-optic coefficient of each fiber grating, P e And for the photoelastic constant of each fiber grating, delta T is the real-time monitoring value of the temperature grating, and delta epsilon is the strain correction data.
Optionally, calculating the measured flexibility value of the position of the monitoring link according to the strain correction data includes:
calculating a target angle of the monitoring link according to the strain correction data;
calculating the deformation radius of the position of the monitoring link according to the target angle; the deformation radius is the radius of a virtual circle with a monitoring section as an arc;
and calculating the measured flexibility value of the position of the monitoring link according to the deformation radius.
Optionally, calculating the target angle of the monitoring link according to the strain correction data specifically includes:
wherein α is the target angle, ε 1 、ε 2 、ε 3 And ε 4 Is the strain correction data.
Optionally, calculating the deformation radius of the position where the monitoring link is located according to the target angle specifically includes:
wherein R is the deformation radius, and R is the section radius of the elastic rod body.
Optionally, calculating the measured flexibility value of the position of the monitoring link according to the deformation radius specifically includes:
where ω (x) is the measured deflection value.
The invention has the beneficial effects that:
the embodiment of the invention provides a sensor for monitoring bridge deflection, which comprises an elastic rod body, a strain fiber grating and a temperature fiber grating, wherein the strain fiber grating is arranged on the elastic rod body; the elastic rod body is used as a core rod piece and is flexible in a linear shape, a plurality of annular monitoring sections are uniformly arranged along the axial direction of the elastic rod body, and a temperature fiber grating is arranged on the surface of the elastic rod body at a preset distance from each monitoring section; four notches are formed in the surface of each monitoring section, the distance between every two adjacent notches on the monitoring section is one fourth of the perimeter of the monitoring section, and each notch is internally provided with a strain fiber grating; the four strain fiber gratings of the monitoring section and the corresponding temperature fiber gratings form a monitoring link. The sensor adopts the linear sensor of optical fiber sensing, can effectively solve the problems of data lag, external interference, stability and maintainability in bridge deflection monitoring, and can effectively obtain the dynamic and static deflection deformation of the bridge, thereby more effectively providing data support for the safety evaluation of the bridge structure.
Drawings
The invention will be further described with reference to the accompanying drawings.
FIG. 1 is a three-dimensional view of a sensor for monitoring bridge deflection according to an embodiment of the present invention;
FIG. 2 is a front view of a sensor for monitoring bridge deflection according to an embodiment of the present invention;
FIG. 3 is a flow chart of a bridge deflection measuring method according to an embodiment of the present invention;
in the figure: 1. an elastic rod body; 2. strain fiber grating; 3. temperature fiber grating; 4. grooving; 5. and monitoring the section.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The embodiment of the invention provides a sensor for monitoring bridge deflection. Referring to fig. 1 and 2, fig. 1 is a three-dimensional view of a sensor for monitoring bridge deflection according to an embodiment of the present invention, and fig. 2 is a front view of the sensor for monitoring bridge deflection according to an embodiment of the present invention. The device comprises an elastic rod body 1, a strain fiber grating 2 and a temperature fiber grating 3;
the flexible rod body 1 is used as a core rod piece and is linear and flexible, a plurality of annular monitoring sections 5 are uniformly arranged along the axial direction of the flexible rod body 1, and a temperature fiber grating 3 is arranged on the surface of the flexible rod body 1 at a preset distance from each monitoring section 5;
four notches 4 are formed in the surface of each monitoring section 5, the distance between every two adjacent notches 4 on the monitoring section 5 is one fourth of the perimeter of the monitoring section 5, and each notch 4 is internally provided with a strain fiber grating 2;
the four strain fiber gratings 2 of the monitoring section 5 and the corresponding temperature fiber gratings 3 form a monitoring link.
The embodiment of the invention provides a sensor for monitoring bridge deflection, which adopts a linear sensor for optical fiber sensing, can effectively solve the problems of data lag, external interference, stability and maintainability in bridge deflection monitoring, and can effectively obtain the dynamic and static deflection deformation of a bridge, thereby more effectively providing data support for the safety evaluation of a bridge structure.
In one implementation, the elastic rod body 1 is a core rod body, is linear and flexible, and can be a PC rod coated with high elastic thick acrylic acid, or can be other resin rods, plastic rods, rubber rods, and the like. The elastic rod body 1 is used as a carrier for mainly sensing the deflection change of the bridge and is arranged along the bridge direction, when the deflection of the bridge changes, the elastic rod body is driven to change, the elastic rod body is influenced, different bending moments and axial stretching can be generated on each monitoring section 5, the strain fiber bragg grating 2 in the notch groove 4 is driven to generate axial deformation at the moment, the temperature influence of the strain fiber bragg grating 2 is compensated through the temperature fiber bragg grating 3, the actual strain measured value of the strain fiber bragg grating 2 is obtained, and the deflection deformation of the elastic rod body on the monitoring section 5 can be calculated.
In one implementation, in fig. 1, FBG0a01, FBG0a02, FBG0a03, FBG0a04, FBG0B01, FBG0B02, FBG0B03, FBG0B04 are name numbers of the strain fiber grating 2, and FBG-T is a name number of the temperature fiber grating 3, and in actual deployment, the name numbers may be associated with the deployed positions of the fiber gratings as position numbers.
In one implementation, as shown in fig. 2, the distance between two adjacent notches 4 on the monitoring section 5 is one fourth of the circumference of the monitoring section 5, that is, the two notches 4 are 90 ° from the center of the monitoring section 5. The depth and the length of the grooves 4 on the surface of the elastic rod body are consistent with the diameter and the length of the strain fiber grating 2, the grooves 4 are arranged by adopting cross sections, each cross section comprises four grooves, the cross sections are uniformly distributed along the axis direction of the elastic rod body, the grooves 4 on each cross section are distributed at positions which are 90-degree azimuth angles around the surface of the elastic rod body, and the longer the elastic rod body is, the more the cross sections containing the grooves 4 are. The strain fiber bragg grating 2 is used as a main sensing element and is tightly embedded and installed in the grooves, each section has four grooves corresponding to the four embedded strain fiber bragg gratings 2, the temperature fiber bragg gratings 3 are arranged between the monitoring sections 5 by adopting a surface pasting method, and the four strain fiber bragg gratings 2 on each monitoring section 5 are connected with one temperature fiber bragg grating 3 in series to form a monitoring link.
Based on the sensor for monitoring the bridge deflection, the embodiment of the invention provides a bridge deflection measuring method, and referring to fig. 3, fig. 3 is a flowchart of the bridge deflection measuring method provided by the embodiment of the invention. The sensor for monitoring the bridge deflection is arranged along the bridge direction of the target bridge, and the method comprises the following steps:
s301, acquiring the monitoring data of each monitoring link.
S302, strain measurement data are corrected according to the temperature measurement data, and strain correction data are obtained.
And S303, calculating the measurement flexibility value of the position of the monitoring link according to the strain correction data.
S304, determining the deployment position of the monitoring link in the target bridge according to the position numbering, and corresponding the measured deflection value of the monitoring link with the deployment position to obtain deflection change data of the target bridge.
The monitoring data comprises strain measurement data of all the strain fiber gratings of the monitoring link, temperature measurement data of the temperature fiber gratings and position numbering of the monitoring link.
The embodiment of the invention provides a bridge deflection measuring method, which adopts a linear sensor of optical fiber sensing, can effectively solve the problems of data lag, external interference (expansion coefficient influence and temperature influence) and stability and maintainability in bridge deflection monitoring, and can effectively obtain the dynamic deflection deformation and the static deflection deformation of a bridge, thereby more effectively providing data support for the safety evaluation of a bridge structure.
In one implementation mode, the elastic rod body is used as a carrier for mainly sensing the deflection change of the bridge and is arranged along the bridge direction, when the deflection of the bridge changes, the elastic rod body is driven to change, the elastic rod body is influenced, different bending moments and axial stretching can be generated on each section of the notch groove, and at the moment, the strain fiber bragg grating in the notch groove is driven to generate axial deformation. The variation of the bridge deflection can be calculated through the measurement of the strain fiber grating.
In one implementation mode, strain measurement data are corrected according to the temperature measurement data, the deformation influence of temperature on the strain fiber bragg grating can be compensated, the strain correction data are closer to the deformation quantity of a target bridge, and the bridge deflection measurement accuracy is improved.
In one implementation, the fiber grating real-time data is acquired by a high-speed acquisition instrument, so that the dynamic deflection change of the bridge can be acquired without data hysteresis.
In one embodiment, step S302 specifically includes:
wherein alpha is f Is the thermal expansion coefficient of the strain fiber grating, xi is the thermo-optic coefficient of the strain fiber grating, P e The optical elastic constant of the strain fiber grating is shown, delta T is a real-time monitoring value of the temperature grating, and delta epsilon is strain correction data of the strain fiber grating.
In one embodiment, step S303 includes:
step one, calculating a target angle of the monitoring link according to strain correction data;
step two, calculating the deformation radius of the position of the monitoring link according to the target angle; the deformation radius is the radius of a virtual circle with a monitoring section as an arc;
and step three, calculating the measured flexibility value of the position of the monitoring link according to the deformation radius.
In one embodiment, calculating the target angle of the monitoring link according to the strain correction data specifically includes:
wherein alpha is the target angle, epsilon 1 、ε 2 、ε 3 And ε 4 Is strain correction data.
In one implementation, α is an angle between a line connecting a bending direction of the elastic rod body and a center of the curvature circle and a normal (perpendicular to the ground). Epsilon 1 、ε 2 、ε 3 And ε 4 And respectively obtaining strain correction data for each strain fiber grating in the same monitoring section according to the formula (1).
In one embodiment, calculating the deformation radius of the position of the monitoring link according to the target angle specifically includes:
wherein R is the deformation radius, and R is the section radius of the elastic rod body.
In one embodiment, the calculating the measured flexibility value of the position of the monitoring link according to the deformation radius specifically includes:
where ω (x) is the measured deflection value.
While one embodiment of the present invention has been described in detail, the description is only a preferred embodiment of the present invention and should not be taken as limiting the scope of the invention. All equivalent changes and modifications made within the scope of the present invention shall fall within the scope of the present invention.
Claims (7)
1. A sensor for monitoring bridge deflection is characterized by comprising an elastic rod body (1), a strain fiber grating (2) and a temperature fiber grating (3);
the flexible rod body (1) is used as a core rod piece and is linear and flexible, a plurality of annular monitoring sections (5) are uniformly arranged along the axial direction of the flexible rod body (1), and a temperature fiber grating (3) is arranged on the surface of the flexible rod body (1) at a preset distance from each monitoring section (5);
four notches (4) are formed in the surface of each monitoring section (5), the distance between every two adjacent notches (4) on the monitoring section (5) is one fourth of the perimeter of the monitoring section (5), and a strain fiber grating (2) is installed in each notch (4);
four strain fiber gratings (2) of the monitoring section (5) and corresponding temperature fiber gratings (3) form a monitoring link.
2. The bridge deflection measuring method for the sensor used for monitoring the bridge deflection is characterized in that the sensor used for monitoring the bridge deflection is arranged along the target bridge along the bridge direction, and the method comprises the following steps:
acquiring monitoring data of each monitoring link; the monitoring data comprises strain measurement data of all strain fiber gratings of the monitoring link, temperature measurement data of temperature fiber gratings and position numbering of the monitoring link;
correcting the strain measurement data according to the temperature measurement data to obtain strain correction data;
calculating the measured deflection value of the position of the monitoring link according to the strain correction data;
and determining the deployment position of the monitoring link in the target bridge according to the position numbering, and corresponding the measured deflection values of all the monitoring links to the deployment position to obtain deflection change data of the target bridge.
3. The bridge deflection measuring method according to claim 2, wherein the strain measurement data is corrected according to the temperature measurement data, and the obtained strain correction data is specifically:
wherein alpha is f Is the thermal expansion coefficient of the strain fiber grating, xi is the thermo-optic coefficient of the strain fiber grating, P e And the delta T is the photoelastic constant of the strain fiber grating, the delta T is the monitoring real-time value of the temperature grating, and the delta epsilon is strain correction data of the strain fiber grating.
4. The bridge deflection measurement method according to claim 2, wherein calculating the measured deflection value of the position of the monitoring link according to the strain correction data comprises:
calculating a target angle of the monitoring link according to the strain correction data;
calculating the deformation radius of the position of the monitoring link according to the target angle; the deformation radius is the radius of a virtual circle with a monitoring section as an arc;
and calculating the measured flexibility value of the position of the monitoring link according to the deformation radius.
5. The bridge deflection measurement method according to claim 4, wherein calculating the target angle of the monitoring link according to the strain correction data specifically comprises:
wherein alpha is an included angle (namely a torsion angle) formed by a connecting line of the bending direction of the elastic rod body and the center of the curvature circle and a normal (vertical to the ground), and epsilon 1 、ε 2 、ε 3 And ε 4 Is the strain correction data.
6. The bridge deflection measurement method according to claim 5, wherein the step of calculating the radius of curvature circle deformation at the position of the monitoring link according to the target angle specifically comprises the following steps:
wherein R is the deformation radius, and R is the section radius of the elastic rod body.
7. The bridge deflection measurement method according to claim 6, wherein the step of calculating the measured deflection value of the position of the monitoring link according to the deformation radius specifically comprises the following steps:
where ω (x) is the measured deflection value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211613234.4A CN115855400A (en) | 2022-12-15 | 2022-12-15 | Sensor for monitoring bridge deflection |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211613234.4A CN115855400A (en) | 2022-12-15 | 2022-12-15 | Sensor for monitoring bridge deflection |
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| CN115855400A true CN115855400A (en) | 2023-03-28 |
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| CN202211613234.4A Pending CN115855400A (en) | 2022-12-15 | 2022-12-15 | Sensor for monitoring bridge deflection |
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