A high-precision control method for the main cable strand shape of a suspension bridge

Abstract

The present invention discloses a method for high-precision control of the linear shape of the main cable strand of a suspension bridge, comprising: collecting temperature data of multiple cross sections within the full length of the main cable strand after the main cable strand is pulled into place, respectively calculating the main cable strand sag f1 without considering the temperature change factor and the main beam cable strand sag f2 considering the temperature change factor, taking the difference between f1 and f2 as the main cable strand elevation, adjustment value, and quickly adjusting the linear shape of the main cable strand; the main cable strand comprises a plurality of digital steel wires, a plurality of array-type temperature fiber grating sensors are buried in the digital steel wires throughout the length, and the array-type temperature fiber grating sensors are used to measure the temperature data of each cross section in the main cable strand. The present invention can accurately calculate the elevation adjustment value of the main cable strand and realize accurate correction of the linear shape of the main cable strand.

Description

Technical Field

[0001] The present invention relates to the technical field of main cable installation for suspension bridges, and more specifically, to a method for high-precision control of the strand shape of the main cable of a suspension bridge. Background Art

[0002] As the main force-bearing and permanent non-replaceable component of the suspension bridge, the line shape and erection quality of the main cable strand are crucial to the force of the suspension bridge. In order to ensure its construction quality, the current specification has made provisions for the temperature and wind speed, two environmental factors that have a greater impact on the cable strand elevation when the cable strand line shape is adjusted. In particular, the specification stipulates that the longitudinal temperature difference of the cable strand during the cable strand line shape adjustment should not be greater than 2°C, and the cross-sectional temperature should not be greater than 1°C, which puts very high requirements on the measurement technology.

[0003] Since a single cable strand has a small cross section, only the longitudinal temperature difference is considered in the installation of suspension bridge strands. The change in temperature difference will cause the actual length of the strand to change, which will be converted into the sag difference between the strand to be adjusted and the reference strand in the actual operation process. The temperature measurement during the linear adjustment of the strand of a traditional suspension bridge is mainly determined by taking the characteristic position, such as measuring the mid-span point of the side span, the mid-span point of the main span and the quarter point, and then setting up the temperature distribution of the strand along its longitudinal direction as a linear stage function. The temperature difference of the characteristic point is used to obtain the temperature change slope of the segment, and finally the integration is performed along the length direction of the strand to obtain the change of the strand caused by the temperature difference; the more corresponding characteristic points, the higher the solution accuracy. This method is applicable to suspension bridges with a mild climate and a small span at the bridge site. Considering that the span of suspension bridges is constantly increasing and the bridge site environment is becoming more and more complex, the characteristic position method is not accurate enough to judge the cable adjustment temperature. In addition, the measurement equipment for measuring the longitudinal temperature difference of cable strands by the traditional characteristic position point method needs to be wired and powered on the catwalk, which is not only cumbersome but also easily damaged by workers during the cable pulling operation. Therefore, in order to meet the large-scale construction needs of suspension bridges and improve the accuracy and speed of adjusting the linear shape of the main cable strands, it is urgent to develop a main cable strand for high-precision adjustment of the linear shape of the main cable strands of suspension bridges, which can quickly measure as much temperature data as possible along the longitudinal direction of the cable strand in a short time. Summary of the invention

[0004] An object of the present invention is to solve at least the above problems and to provide at least the advantages which will be described hereinafter.

[0005] In order to achieve these purposes and other advantages according to the present invention, a high-precision control method for the linear shape of a main cable strand of a suspension bridge is provided, comprising: collecting temperature data of multiple cross sections within the entire length of the main cable strand after the main cable strand is pulled into place, calculating the sag f1 of the main cable strand without considering the temperature change factor and the sag f2 of the main beam cable strand considering the temperature change factor, taking the difference between f1 and f2 as the elevation adjustment value of the main cable strand, and quickly adjusting the linear shape of the main cable strand; the main cable strand comprises a plurality of digital steel wires, a plurality of array-type temperature fiber grating sensors are buried in the digital steel wires throughout the entire length, and the array-type temperature fiber grating sensors are used to measure the temperature data of each cross section in the main cable strand.

[0006] Preferably, f1 and f2 are calculated according to the horizontal force H1 on the main cable strand when the temperature change factor is not considered and the horizontal force H2 on the main cable strand when the temperature change factor is considered, respectively:

[0007]

[0008]

[0009] Where, q is the weight of the main cable strand per linear meter.

[0010] Preferably, the invention is characterized in that the stressed cable length S1 when the temperature change factor is not considered and the elongation ΔS caused by the stress generated by the deadweight when the cable strand is freely suspended are used. G1 Use the known main cable span value L and the main cable strand weight per meter q to express, and substitute S0=S1-ΔS G1 The horizontal force H1 on the main cable strands is calculated without considering the temperature change factor;

[0011]

[0012]

[0013]

[0014]

[0015] Among them, C is the height difference of the catenary; S0 is the length of the stress-free cable; E C ——Elastic modulus of cable strand wire; A C ——is the area of ​​the cable strand wire.

[0016] Preferably, the stress cable length S2 when the temperature change factor is taken into account and the elongation ΔS caused by the stress generated by the deadweight when the cable strand is freely suspended are used. G2 Use the known main cable span value L and the main cable strand weight per meter q to express, and substitute S0=S2-ΔSG2 -ΔS T The horizontal force H2 on the main cable strands is calculated considering the temperature change factor;

[0017]

[0018]

[0019] ΔS T =∑∫α(T i (S i )-t i )ds

[0020] Among them, ΔS T ——The change of the stress-free cable length considering the temperature change factor; T i (S i )——fitting function of temperature distribution along the length direction of the main cable strand.

[0021] Preferably, T i (S i ) is the temperature data of each cross section of the main cable strand in the length direction measured by the array temperature fiber Bragg grating sensor, which is fitted to obtain T i (S i ).

[0022] Preferably, a plurality of the digital steel wires are arranged at the center of the main cable strand and are evenly distributed on the periphery of the main cable strand.

[0023] Preferably, the outer periphery of the digital steel wire is provided with at least one slot extending along the length direction of the skeleton steel wire, a plurality of the array-type temperature grating optical fiber sensors are passed through the slot, and the outer periphery of the digital steel wire is covered with a protective layer.

[0024] Preferably, the arrayed temperature fiber Bragg grating sensor comprises a measuring optical fiber on which a plurality of fiber Bragg gratings are engraved at intervals along its length; the number of cross sections to be measured in the main cable strand is the same as the number of the fiber Bragg gratings.

[0025] The present invention has at least the following beneficial effects:

[0026] The high-precision control method for the linear shape of the main cable strand of a suspension bridge provided by the present invention uses an array-type temperature fiber grating sensor built into the digital steel wire to quickly and accurately measure the temperature of multiple cross sections of the main cable strand throughout its length, and accurately calculates the elevation adjustment value of the main cable strand based on the measured temperature data, thereby realizing accurate correction of the linear shape of the main cable strand. The array-type temperature fiber grating sensor is built into the digital steel wire, which does not affect the manufacturing and on-site installation of the main cable strand, and solves the problems of cumbersome external measurement wiring and power supply of traditional cable strands, a small number of measurement points, and high measurement intensity;

[0027] 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

[0028] Figure 1 It is a temperature distribution curve diagram of the main cable strand along the length direction in one embodiment of the present invention;

[0029] Figure 2 is a schematic diagram of the cross-sectional structure of the main cable strand of the present invention;

[0030] Figure 3 It is a schematic diagram of the longitudinal section structure of the main cable strand of the present invention; DETAILED DESCRIPTION

[0031] 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.

[0032] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials are commercially available unless otherwise specified; in the description of the present invention, the terms "lateral", "longitudinal", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and 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 operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0033] like Figure 1As shown, a high-precision control method for the linear shape of a main cable strand of a suspension bridge comprises: collecting temperature data of multiple cross sections within the full length of the main cable strand after the main cable strand is pulled into place, respectively calculating the main cable strand sag f1 without considering the temperature change factor and the main beam cable strand sag f2 considering the temperature change factor, taking the difference between f1 and f2 as the main cable strand elevation adjustment value, and quickly adjusting the linear shape of the main cable strand; the main cable strand comprises a plurality of digital steel wires, a plurality of arrayed temperature fiber grating sensors are buried in the digital steel wires throughout the length, and the arrayed temperature fiber grating sensors are used to measure the temperature data of each cross section in the main cable strand.

[0034] In this technical solution, refer to Figure 2 , the main cable strand is made by braiding the digital steel, 3 and the general steel wire 4. After the main cable strand is pulled in place, the temperature data of each cross section measured by the array temperature fiber grating sensor is measured and acquired in the anchor chamber of the anchor fixed to the main cable strand anchor head. The length of the strand is S=S0+ΔS G +ΔS T , S0 is the stress-free cable length, which will not change after the cable leaves the factory and is a known value; ΔS G ΔS is the elongation caused by the stress generated by the cable strands due to their own weight when the cable strands are freely suspended; T The change in cable length is caused by temperature difference. Therefore, the accuracy of the final cable sag adjustment depends directly on the temperature data, and the change in stress-free cable length caused by temperature can be expressed as ΔS T =∑∫α(T i (S i )-t i )ds, where T i (S i ) is the temperature distribution fitting function of the main cable strand along the length direction, and it is fitted based on the temperature data of each cross section measured by the array temperature fiber grating sensor. Compared with the traditional characteristic position method, the main cable strand temperature distribution curve (refer to Figure 1 The dotted line in the figure) is used to fit the temperature data of each cross section measured by the array temperature fiber Bragg grating sensor to obtain a curve (refer to Figure 1 The solid line part in the figure can more accurately reflect the temperature change of the main cable strand along the length direction, and then according to ΔS T The calculation formula can accurately calculate the change in stress-free cable length due to temperature changes, thereby achieving precise control of the linearity of the main cable strands.

[0035] Specifically, the main cable strands are catenary after being pulled into place. After S0 is determined, when the temperature is equal to the factory temperature, its linear sag, the cable force generated by its own weight, etc. can be determined; after considering the temperature, when its own weight remains unchanged, the change in its sag is in principle due to the change in cable force caused by the temperature internal force. The change in horizontal force causes the sag to change, so it is only necessary to obtain the horizontal force under each temperature condition to obtain the corresponding sag. Therefore, the sag f1 of the main cable strand without considering the temperature change factor and the sag f2 of the main beam cable strand with considering the temperature change factor are calculated according to the horizontal force H1 when the main cable strand does not consider the temperature change factor and the horizontal force H2 when the temperature change factor is considered:

[0036]

[0037]

[0038] Where, q is the weight of the main cable strand per linear meter.

[0039] The stressed cable length S1 without considering the temperature change factor and the elongation ΔS caused by the stress generated by the deadweight when the cable strand is freely suspended G1 Use the known main cable span value L and the main cable strand weight per meter q to express, and substitute S0=S1-ΔS G1 The horizontal force H1 on the main cable strands is calculated without considering the temperature change factor;

[0040]

[0041]

[0042]

[0043]

[0044] Among them, C is the height difference of the catenary; S0 is the length of the stress-free cable; E C ——Elastic modulus of cable strand wire; A C ——is the area of ​​the cable strand wire.

[0045] The stress cable length S2 when considering the temperature change factor and the elongation ΔS caused by the stress generated by the deadweight when the cable strand is freely suspended G2 Use the known main cable span value L and the main cable strand weight per meter q to express, and substitute S0=S2-ΔS G2 -ΔS T The horizontal force H2 on the main cable strands is calculated considering the temperature change factor;

[0046]

[0047]

[0048] ΔS T =∑∫α(T i (S i )-t i )ds (9)

[0049] Among them, ΔS T ——The change of the stress-free cable length considering the temperature change factor; T i (S i )——fitting function of temperature distribution along the length direction of the main cable strand.

[0050] Substituting H1 and H2 into equation (5) and equation (6), we can obtain α1, α2, β1, and β2 respectively. Substituting them into equation (3), equation (4), equation (7), and equation (8), we can obtain S1, S2, and S2 represented by L, q, H1, and H2 respectively. G1 , S G2 , and then through S0 = S1-ΔS G1 S0 = S2 - ΔS G2 -ΔS T The values ​​of H1 and H2 are obtained respectively, and then the values ​​of f1 and f2 are calculated by substituting them into equations (1) and (2) respectively. Finally, the cable line shape is quickly adjusted according to the cable sag difference Δf=f1-f2 when considering the temperature change.

[0051] In another embodiment, referring to Figure 2 and Figure 3, multiple digital steel wires 3 are arranged at the center of the main cable strand and evenly distributed on the periphery of the main cable strand. The periphery of the digital steel wire 3 is provided with at least one through-length slot 6 along its length direction, and at least one array-type temperature grating optical fiber sensor 2 is inserted into the slot 6, and the periphery of the digital steel wire 3 is covered with a protective layer 5. The protective layer 5 prevents the array-type temperature fiber grating sensor 2 from falling from the digital steel wire 3, and the protective layer 5 can be made of conventional protective materials such as metal sheaths. The array-type temperature fiber grating sensor 2 includes a measuring optical fiber, and a plurality of fiber gratings are engraved on the measuring optical fiber at intervals along its length direction; the number of cross-sections to be measured in the main cable strand is the same as the number of the fiber gratings. Within the full length range of the main cable strand, the number of cross-sections to be measured is determined by the number of the fiber gratings, so the number and spacing of the cross-sections to be measured can be adjusted according to actual conditions. Preferably, the spacing between two adjacent fiber Bragg gratings can be set to 1m to ensure that the array temperature fiber Bragg grating sensor 2 is not squeezed and damaged by the surrounding general steel wire 4. The arithmetic mean of the temperature data measured by multiple fiber Bragg gratings in the same cross section of the main cable strand is taken as the temperature value of the cross section, and the curve formed by the temperature values ​​of multiple cross sections within the full length of the main cable strand is fitted to obtain the temperature distribution fitting function T of the main cable strand along the length direction. i (S i ).

[0052] 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 high-precision control method for the main cable strand shape of a suspension bridge, characterized in that: include: After the main cable strand is pulled into place, the temperature data of multiple cross sections within the full length of the main cable strand are collected, and the main cable strand sag f1 without considering the temperature change factor and the main beam cable strand sag f2 considering the temperature change factor are calculated respectively. The difference between f1 and f2 is used as the main cable strand elevation adjustment value, and the main cable strand linear shape is quickly adjusted; the main cable strand includes a plurality of digital steel wires, and a plurality of array-type temperature fiber grating sensors are buried in the digital steel wires throughout the length, and the array-type temperature fiber grating sensors are used to measure the temperature data of each cross section in the main cable strand; f1 and f2 are calculated according to the horizontal force H1 of the main cable strand when the temperature change factor is not considered and the horizontal force H2 of the main cable strand when the temperature change factor is considered: Substitute H1 and H2 into the following formula to obtain α1 and α2 respectively: Among them, q is the weight of the main cable strand per meter, L is the span of the main cable, and C is the height difference of the catenary.

2. The high-precision control method for the strand shape of the main cable of a suspension bridge according to claim 1, characterized in that: The stress cable length S1 without considering the temperature change factor and the elongation ΔS caused by the stress generated by the deadweight when the cable strand is freely suspended are used. G1 Use the known main cable span value L and the main cable strand weight per meter q to represent, and substitute The horizontal force H1 on the main cable strands is calculated without considering the temperature change factor; Among them, S0 is the stress-free cable length; Ec is the elastic modulus of the cable strand; Ac is the area of ​​the cable strand.

3. The high-precision control method for the strand shape of the main cable of a suspension bridge according to claim 1, characterized in that: The stress cable length S2 when considering the temperature change factor and the elongation ΔS caused by the stress generated by the deadweight when the cable strand is freely suspended are used. G2 Use the known main cable span value L and the main cable strand weight per meter q to represent, and substitute The horizontal force H2 on the main cable strands is calculated considering the temperature change factor; in, ——The change in the length of the stress-free cable taking into account the temperature change factor; ——Fitting function of temperature distribution along the length direction of the main cable strand.

4. The high-precision control method for the strand shape of the main cable of a suspension bridge according to claim 3, characterized in that: It is obtained by fitting the temperature data of each cross section of the main cable strand in the length direction measured by the array-type temperature fiber Bragg grating sensor.

5. The high-precision control method for the strand shape of the main cable of a suspension bridge according to claim 1, characterized in that: A plurality of digital steel wires are arranged at the center of the main cable strand and are evenly distributed around the periphery of the main cable strand.

6. The high-precision control method for the strand shape of the main cable of a suspension bridge according to claim 1, characterized in that: The outer circumference of the digital steel wire is provided with at least one slot extending along the length direction of the digital steel wire, a plurality of array-type temperature grating optical fiber sensors are passed through the slot, and the outer circumference of the digital steel wire is covered with a protective layer.

7. The high-precision control method for the strand shape of the main cable of a suspension bridge according to claim 1, characterized in that: The array-type temperature fiber grating sensor comprises a measuring optical fiber, on which a plurality of fiber gratings are engraved at intervals along its length direction; the number of cross sections to be measured in the main cable strand is the same as the number of the fiber gratings.

Images