Arch bridge arch rib erection construction deflection monitoring method and system

Abstract

The invention discloses an arch bridge arch rib erection construction deflection monitoring method, which comprises the following steps that S1, an arch bridge arch rib is spliced, the arch bridge arch rib comprises two upper chords and two lower chords which are respectively distributed up and down, the upper chords and the lower chords are respectively provided with a plurality of distributed strain optical fibers, and two adjacent distributed strain optical fibers are connected to form a plurality of distributed strain optical fibers; connecting all the distributed strain optical fibers to form a path; s2, acquiring strain and temperature data of the distributed optical fiber online in real time; s3, temperature compensation axial strain and neutral axis axial strain are obtained through calculation according to the collected strain and temperature data, and the deflection of the arch rib is obtained through calculation. According to the method, the deflection of the arch rib in the erection construction stage can be monitored in real time, construction does not need to be interrupted, and the method can be applied to the whole construction process; multiple parameters such as deflection, strain and temperature can be measured at the same time; the system can run and cover full life cycle monitoring of the arch rib, and can be converted into structure health monitoring after construction is completed.

Description

Technical Field

[0001] The present invention relates to the field of monitoring the deflection of arch bridge arch rib construction, and more specifically, to a method for monitoring the deflection of arch bridge arch rib construction. Background Art

[0002] The arch rib is the skeleton of the main arch ring of the arch bridge. During the installation and construction process, it bears its own weight, lateral connecting components, arch waves and corresponding construction loads.

[0003] Arch rib deflection can directly reflect the working status and applicability of the bridge construction process. Excessive deformation of the arch rib will affect the normal construction and safety. Abnormal changes in deflection may lead to unfavorable structural stress and cause structural damage. By real-time online monitoring of arch rib deflection, the operation status of bridge construction can be understood to ensure smooth construction.

[0004] Currently, the methods suitable for monitoring the deflection of arch ribs include GPS, laser, image, and inclinometer. GPS deflection measurement is not affected by the environment, but it is expensive and has low accuracy. Both laser and image methods are non-contact measurement methods, but the laser method is limited by distance. If the distance is too far, the light beam will easily shake, thus affecting the measurement accuracy. The image method is affected by environmental visibility. On rainy days or in poor light, the image quality may be poor, affecting the measurement effect. The inclinometer method uses the inclination angle to infer the deformation of the structure, but it requires a large number of points and the equipment is easily damaged, resulting in high maintenance costs in the later stage. Summary of the invention

[0005] In order to achieve these purposes and other advantages according to the present invention, a preferred embodiment of the present invention provides a method for monitoring the deflection of an arch bridge arch rib erection, comprising the following steps:

[0006] S1. Distributed fiber optic sensor layout

[0007] The arch ribs of the arch bridge are spliced, wherein the arch ribs of the arch bridge include two upper chords and two lower chords respectively distributed up and down, and a plurality of distributed strain optical fibers are respectively installed on the upper chords and the lower chords, and all the distributed strain optical fibers are connected to form a passage by connecting two adjacent distributed strain optical fibers;

[0008] S2. Data Collection

[0009] Obtain distributed optical fiber strain and temperature data online in real time;

[0010] S3. Data Processing

[0011] The temperature compensated axial strain and neutral axis axial strain are calculated based on the collected strain and temperature data, and the deflection of the arch rib is also calculated.

[0012] Preferably, a distributed temperature optical fiber is installed next to each distributed strain optical fiber for temperature compensation to eliminate the interference of temperature changes on strain measurement.

[0013] Preferably, in S3, the temperature-compensated axial strain and the neutral axis axial strain are calculated according to the collected strain and temperature data, which specifically includes the following steps:

[0014] S31. Calculation of temperature compensated axial strain

[0015] First, perform temperature compensation calculation to eliminate the influence of temperature on strain monitoring, specifically:

[0016] ε ij =ε ijs -ε ijt Formula (1)

[0017] Among them, i = 0, m, 2m, 3m, ..., is the spatial coordinate of the arch rib position, the unit is meter, m is the spatial resolution of the demodulation equipment used; j = 1, 2, 3, 4, is the steel pipe number of the upper chord / lower chord; ε ij is the actual axial strain of the upper / lower chord numbered j after temperature compensation at the section at the ith meter; ε ijs is the axial strain of the upper / lower chord numbered j before temperature compensation at the section at the ith meter; ε ijt is the axial strain caused by temperature in the section of the steel pipe numbered j at the i-th meter;

[0018] S32. Calculate the axial strain of the neutral axis

[0019] According to the axial strain data of the two upper chords and the two lower chords obtained in step S31, the strain value at the neutral axis of the arch rib section at the position i meters is obtained, which is specifically:

[0020]

[0021] Among them, i = 0, m, 2m, 3m, ..., is the spatial coordinate of the arch rib position, the unit is meter, m is the spatial resolution of the demodulation equipment used; j = 1, 2, 3, 4, is the steel pipe number of the upper chord / lower chord; ε ij is the actual axial strain of the upper chord / lower chord numbered j at the i-th meter section after temperature compensation.

[0022] Preferably, in S3, the arch rib deflection is calculated according to the collected strain and temperature data, which specifically includes the following steps:

[0023] S33. After the arch rib is installed, it can be approximately regarded as a cantilever beam. The conjugate beam method corresponds to a virtual beam model. The installed arch rib satisfies the physical relationship between the curvature k and the bending moment M.

[0024]

[0025] Where, EI is the cross-sectional bending stiffness;

[0026] S34. At any position x on the arch rib, the real beam and the virtual beam have the following numerical relationship:

[0027]

[0028] Where EI is the cross-sectional bending stiffness; y(x) is the deflection distribution of the real beam; is the bending moment distribution of the virtual beam; k(x) is the curvature of the real beam at the x-coordinate; M(x) is the bending moment distribution of the real beam; ε(x) is the strain of the arch rib at the x-coordinate measured by the distributed optical fiber; is the load distribution of the virtual beam;

[0029] Assuming that the horizontal length of the arch rib is L, its cross-sectional bending stiffness is EI, and the beam is divided into n units along the length direction, the unit length is l = L / n. For any load, M(x) / EI can be equivalent to a virtual beam The uniformly distributed load is:

[0030]

[0031] In the formula, k(x n ) is the curvature of the nth section of the real beam at the x coordinate; EI is the bending stiffness of the section; M(x n ) The bending moment distribution of the nth section of the real beam; is the load distribution of the nth segment of the virtual beam;

[0032] According to the load distribution of the virtual beam, the bending moment at any point on the virtual beam can be calculated, specifically:

[0033]

[0034] Wherein, i=1…n;

[0035] According to the corresponding relationship between the real beam and the conjugate beam, the longitudinal deflection of the arch rib is equal to the bending moment of the virtual beam:

[0036]

[0037] Substituting formula (5) into formula (10), we have

[0038]

[0039] A preferred embodiment of the present invention provides a system for monitoring the construction deflection of an arch bridge rib structure, wherein the arch bridge rib comprises two upper chords and two lower chords respectively distributed up and down, and the upper chords and the lower chords are respectively installed with a plurality of distributed strain optical fibers, and by connecting two adjacent distributed strain optical fibers, all the distributed strain optical fibers are connected to form a path; a distributed temperature optical fiber is arranged and installed next to each distributed strain optical fiber, and two adjacent distributed strain optical fibers are connected to form a path, and the distributed optical fibers collect strain and temperature data in real time.

[0040] The present invention includes at least the following beneficial effects: the present invention can monitor the deflection of the arch rib during the construction phase in real time without interrupting the construction, and can be applied to the entire construction process; and can simultaneously perform multi-parameter measurements of deflection, strain, and temperature; the system of the present invention can operate to cover the entire life cycle monitoring of the arch rib, and can be converted to structural health monitoring after the construction is completed.

[0041] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic diagram of the deflection monitoring structure of the arch rib erection construction of an arch bridge in one implementation of the present invention.

[0043] Figure 2 Schematic diagram of the cross section of the upper chord / lower chord in one embodiment of the present invention.

[0044] Figure 3 It is a schematic diagram of assembling the arch ribs in one embodiment of the present invention.

[0045] Figure 4 It is a schematic diagram of the projected length of the arch rib in one embodiment of the present invention.

[0046] Figure 5 It is a schematic diagram of the projected length of the arch rib in one embodiment of the present invention. DETAILED DESCRIPTION

[0047] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0048] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art can think of other obvious variations. The basic principles of the present invention defined in the following description can be applied to other embodiments, variations, improvements, equivalents, and other technical solutions that do not deviate from the spirit and scope of the present invention.

[0049] Those skilled in the art should understand that, in the disclosure of the present invention, the orientation or position relationship indicated by the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are based on the orientation or position relationship shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0050] It is to be understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element may be one, while in another embodiment, the number of the element may be multiple, and the term "one" should not be understood as a limitation on the quantity.

[0051] like Figure 1-5 As shown, a preferred embodiment of the present invention provides a method for monitoring the deflection of an arch bridge arch rib erection, comprising the following steps:

[0052] S1. Distributed fiber optic sensor layout

[0053] The arch ribs of the arch bridge are spliced, wherein the arch ribs of the arch bridge include two upper chords and two lower chords respectively distributed up and down, namely, upper chord A1, upper chord B2, lower chord A3, and lower chord B4. The upper chords and lower chords are respectively installed with multiple distributed strain optical fibers 5. By connecting two adjacent distributed strain optical fibers, all distributed strain optical fibers are connected to form a path; a distributed temperature optical fiber 6 is arranged and installed next to each distributed strain optical fiber for temperature compensation to eliminate the interference of temperature changes on strain measurement.

[0054] S2. Data Collection

[0055] Obtain distributed optical fiber strain and temperature data online in real time;

[0056] S3. Data Processing

[0057] The temperature compensated axial strain and neutral axis axial strain are calculated based on the collected strain and temperature data, and the deflection of the arch rib is also calculated.

[0058] Preferably, in S3, the temperature-compensated axial strain and the neutral axis axial strain are calculated according to the collected strain and temperature data, which specifically includes the following steps:

[0059] S31. Calculation of temperature compensated axial strain

[0060] First, perform temperature compensation calculation to eliminate the influence of temperature on strain monitoring, specifically:

[0061] εij =ε ijs -ε ijt Formula (1)

[0062] Among them, i = 0, m, 2m, 3m, ..., is the spatial coordinate of the arch rib position, the unit is meter, m is the spatial resolution of the demodulation equipment used; j = 1, 2, 3, 4, is the steel pipe number of the upper chord / lower chord; ε ij is the actual axial strain of the upper / lower chord numbered j after temperature compensation at the section at the ith meter; ε ijs is the axial strain of the upper / lower chord numbered j before temperature compensation at the section at the ith meter; ε ijt is the axial strain caused by temperature in the section of the steel pipe numbered j at the i-th meter;

[0063] S32. Calculate the axial strain of the neutral axis

[0064] According to the axial strain data of the two upper chords and the two lower chords obtained in step S31, the strain value at the neutral axis of the arch rib section at the position i meters is obtained, which is specifically:

[0065]

[0066] Among them, i = 0, m, 2m, 3m, ..., is the spatial coordinate of the arch rib position, the unit is meter, m is the spatial resolution of the demodulation equipment used; j = 1, 2, 3, 4, is the steel pipe number of the upper chord / lower chord; ε ij is the actual axial strain of the upper chord / lower chord numbered j at the i-th meter section after temperature compensation.

[0067] Preferably, in S3, the arch rib deflection is calculated according to the collected strain and temperature data, which specifically includes the following steps:

[0068] S33. After the arch rib is installed, it can be approximately regarded as a cantilever beam. The conjugate beam method corresponds to a virtual beam model. The installed arch rib satisfies the physical relationship between the curvature k and the bending moment M.

[0069]

[0070] Where, EI is the cross-sectional bending stiffness;

[0071] S34. At any position x on the arch rib, the real beam and the virtual beam have the following numerical relationship:

[0072]

[0073] Where EI is the cross-sectional bending stiffness; y(x) is the deflection distribution of the real beam; is the bending moment distribution of the virtual beam; k(x) is the curvature of the real beam at the x-coordinate; M(x) is the bending moment distribution of the real beam; ε(x) is the strain of the arch rib at the x-coordinate measured by the distributed optical fiber; is the load distribution of the virtual beam;

[0074] Assuming that the horizontal length of the arch rib is L, its cross-sectional bending stiffness is EI, and the beam is divided into n units along the length direction, the unit length is l = L / n. For any load, M(x) / EI can be equivalent to a virtual beam The uniformly distributed load is:

[0075]

[0076] In the formula, k(x n ) is the curvature of the nth section of the real beam at the x coordinate; EI is the bending stiffness of the section; M(x n ) The bending moment distribution of the nth section of the real beam; is the load distribution of the nth segment of the virtual beam;

[0077] According to the load distribution of the virtual beam, the bending moment at any point on the virtual beam can be calculated, specifically:

[0078]

[0079] Wherein, i=1…n;

[0080] According to the corresponding relationship between the real beam and the conjugate beam, the longitudinal deflection of the arch rib is equal to the bending moment of the virtual beam:

[0081]

[0082] Substituting formula (5) into formula (10), we have

[0083]

[0084] In this way, the deformation calculation of the arch rib can be transformed into the problem of calculating the virtual beam bending moment corresponding to the arch rib. In formula (10), ε(x i ) is the neutral axis axial strain ε measured by the distributed optical fiber in step 3(2) i .

[0085] A preferred embodiment of the present invention provides a system for monitoring the construction deflection of an arch bridge rib structure, wherein the arch bridge rib comprises two upper chords and two lower chords respectively distributed up and down, and the upper chords and the lower chords are respectively installed with a plurality of distributed strain optical fibers, and by connecting two adjacent distributed strain optical fibers, all the distributed strain optical fibers are connected to form a path; a distributed temperature optical fiber is arranged and installed next to each distributed strain optical fiber, and two adjacent distributed strain optical fibers are connected to form a path, and the distributed optical fibers collect strain and temperature data in real time.

[0086] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A method for monitoring the deflection of an arch bridge arch rib during construction, characterized in that: The following steps are involved: S1. Distributed fiber optic sensor layout The arch ribs of the arch bridge are spliced, wherein the arch ribs of the arch bridge include two upper chords and two lower chords respectively distributed up and down, and a plurality of distributed strain optical fibers are respectively installed on the upper chords and the lower chords, and all the distributed strain optical fibers are connected to form a passage by connecting two adjacent distributed strain optical fibers; S2. Data Collection Real-time online acquisition of strain and temperature data of distributed optical fibers; S3. Data Processing The temperature compensated axial strain and neutral axis axial strain are calculated based on the collected strain and temperature data, and the deflection of the arch rib is also calculated.

2. The method for monitoring the deflection of the arch rib erection construction of an arch bridge according to claim 1, characterized in that: A distributed temperature optical fiber is installed next to each distributed strain optical fiber for temperature compensation to eliminate the interference of temperature changes on strain measurement.

3. The method for monitoring the deflection of the arch rib erection construction of an arch bridge according to claim 1, characterized in that: In S3, the temperature-compensated axial strain and the neutral axis axial strain are calculated based on the collected strain and temperature data, which specifically includes the following steps: S31. Calculation of temperature compensated axial strain First, perform temperature compensation calculation to eliminate the influence of temperature on strain monitoring, specifically: e ij =e ijs -e ijt official(1) Where i = 0, m, 2m, 3m, ..., is the spatial coordinate of the arch rib position, in meters, and m is the spatial resolution of the demodulation equipment used; j = 1, 2, 3, 4, is the steel pipe number of the upper chord / lower chord; ε ij is the actual axial strain of the upper / lower chord numbered j after temperature compensation at the section at the ith meter; ε ijs is the axial strain of the upper / lower chord numbered j before temperature compensation at the section at the ith meter; ε ijt is the axial strain caused by temperature in the section of the steel pipe numbered j at the i-th meter; S32. Calculate the axial strain of the neutral axis According to the axial strain data of the two upper chords and the two lower chords obtained in step S31, the strain value at the neutral axis of the arch rib section at the position i meters is obtained, which is specifically: Where i = 0, m, 2m, 3m, ..., is the spatial coordinate of the arch rib position, in meters, and m is the spatial resolution of the demodulation equipment used; j = 1, 2, 3, 4, is the steel pipe number of the upper chord / lower chord; ε ij is the actual axial strain of the upper chord / lower chord numbered j at the i-th meter section after temperature compensation.

4. The method for monitoring the deflection of the arch rib erection construction of an arch bridge according to claim 1, characterized in that: In S3, the arch rib deflection is calculated according to the collected strain and temperature data, which specifically includes the following steps: S33. After the arch rib is installed, it can be approximately regarded as a cantilever beam. The conjugate beam method corresponds to a virtual beam model. The installed arch rib satisfies the physical relationship between the curvature k and the bending moment M. Where, EI is the cross-sectional bending stiffness; S34. At any position x on the arch rib, the real beam and the virtual beam have the following numerical relationship: Where EI is the cross-sectional bending stiffness; y(x) is the deflection distribution of the real beam; is the bending moment distribution of the virtual beam; k(x) is the curvature of the real beam at the x-coordinate; M(x) is the bending moment distribution of the real beam; ε(x) is the strain of the arch rib at the x-coordinate measured by the distributed optical fiber; is the load distribution of the virtual beam; Assuming that the horizontal length projection of the arch rib is L, and its cross-sectional bending stiffness is EI, the beam is divided into n units along the length direction, then the unit length is l = L / n. For any load, M(x) / EI can be equivalent to a virtual beam. The uniformly distributed load is: …… In the formula, k(x n ) is the curvature of the nth section of the real beam at the x coordinate; EI is the bending stiffness of the section; M(x n ) The bending moment distribution of the nth section of the real beam; is the load distribution of the nth segment of the virtual beam; According to the load distribution of the virtual beam, the bending moment at any point on the virtual beam can be calculated, specifically: Wherein, i=1…n; According to the corresponding relationship between the real beam and the conjugate beam, the longitudinal deflection of the arch rib is equal to the bending moment of the virtual beam: Substituting formula (5) into formula (10), we have 5. A system for monitoring the deflection of the arch rib erection construction of an arch bridge according to any one of claims 1 to 4, characterized in that: The arch rib of the arch bridge includes two upper chords and two lower chords which are respectively distributed up and down. A plurality of distributed strain optical fibers are respectively installed on the upper chords and the lower chords. By connecting two adjacent distributed strain optical fibers, all the distributed strain optical fibers are connected to form a passage. A distributed temperature optical fiber is arranged and installed next to each distributed strain optical fiber. Two adjacent distributed strain optical fibers are connected to form a passage. The distributed optical fibers collect strain and temperature data in real time.

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