Intelligent cable force measuring method for short sling of suspension bridge

Abstract

The invention discloses an intelligent cable force measurement method for a short suspension cable of a suspension bridge, and belongs to the technical field of intelligent measurement of bridge cable force, and the method comprises the following steps: carrying out the preliminary structural design of the short suspension cable of the suspension bridge; establishing a three-dimensional finite element model of the short suspension cable of the suspension bridge, and carrying out stress analysis on the short suspension cable; parameters of the sleeve are optimized, and parameters of the pull rod are optimized; screening a pull rod stress uniformity area and taking the area as an optimal measurement area, and then determining the length of the measurement rod; establishing an intelligent sensing suspension bridge short sling; carrying out a force measurement calibration test on the short sling of the intelligent sensing suspension bridge, and determining a corresponding relation between the cable force of the short sling and the displacement sensed by the displacement sensor; based on real-time displacement data collected by a displacement sensor, an accurate cable force measurement result of the short sling is obtained by utilizing a corresponding relation. According to the invention, factors such as short sling boundary conditions, great fundamental frequency identification difficulty and great flexural rigidity influence can be overcome, and the cable force can be accurately identified.

Description

Technical Field

[0001] The invention relates to an intelligent cable force measurement method for a short suspension cable of a suspension bridge, belonging to the technical field of intelligent cable force measurement of bridges. Background Art

[0002] Suspension bridges are one of the most powerful types of bridges. The slings are important force transmission components connecting the main beam and the main cable, transferring the load borne by the main beam to the main cable. The change of the sling cable force has a huge impact on the internal force and linear changes of the suspension bridge structure. It is one of the key indicators for the status assessment of long-span suspension bridges and an important basis for analyzing the current stress state of the structure and assessing the health of the bridge structure. Accurate identification of the sling cable force is of great significance to the service status assessment of the suspension bridge.

[0003] Relevant application technologies show that the cable tension of long cables can be accurately identified by the frequency method. The accuracy of the frequency method mainly depends on the accuracy of the vibration pickup technology and the accuracy of the cable tension calculation formula (including the identification of parameters at all levels). The first two fundamental frequencies of short cables can be accurately identified by hammer excitation, but the interference of forced vibration of short cables less than 5m is very large, especially for bridges in operation, it will be more difficult to pick up their natural frequencies, the fundamental frequency resolution is not high and the accuracy is poor. Due to factors such as boundary conditions, difficulty in identifying fundamental frequencies and large influence of bending stiffness, it is difficult to accurately identify the cable tension of short cables by conventional cable tension detection methods. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide an intelligent measurement method for the cable force of the short cables of a suspension bridge, which can overcome factors such as the boundary conditions of the short cables, the difficulty in identifying the fundamental frequency and the great influence of the bending stiffness, and accurately identify the cable force.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] The present invention provides a method for intelligently measuring the cable force of a short sling of a suspension bridge, comprising the following steps:

[0007] The short suspension cable of the suspension bridge is preliminarily designed. The short suspension cable of the suspension bridge includes the suspension cable and an upper anchor cup and a lower anchor cup connected at both ends thereof. The lower anchor cup is connected to the pull rod through a sleeve. A measuring rod for measuring its deformation is arranged in the pull rod. The measuring rod is implanted in the displacement sensor.

[0008] Establish a three-dimensional finite element model of the short cable of the suspension bridge, conduct a stress analysis on the short cable, and obtain mechanical calculation results;

[0009] According to the mechanical calculation results and based on the strength theory, the sleeve parameters are optimized to generate sleeve optimization parameters so that the sleeve tensile performance is better than the tie rod and the lower end anchor cup, and the tie rod parameters are optimized to generate tie rod optimization parameters so that the tie rod meets the safety requirements;

[0010] Based on the preliminary structural design, a region with uniform stress on the tie rod is selected and used as the best measurement region, and then the length of the measuring rod is determined to generate a length parameter of the measuring rod;

[0011] According to the preliminary design structure of the short suspension cable of the suspension bridge, as well as the sleeve optimization parameters, the pull rod optimization parameters and the length parameters of the measuring rod, the intelligent sensing short suspension cable of the suspension bridge is established;

[0012] A force measurement calibration test was conducted on the short cables of the intelligent sensing suspension bridge to determine the corresponding relationship between the cable force of the short cables and the displacement sensed by the displacement sensor.

[0013] Based on the real-time displacement data collected by the displacement sensor, the measurement result of the short sling force is obtained by utilizing the corresponding relationship between the short sling force and the displacement sensed by the displacement sensor.

[0014] In the preliminary structural design of the short suspension cable of the suspension bridge: a coaxial center hole is opened on the pull rod, and the two ends of the measuring rod are locked with the center hole.

[0015] The two ends of the measuring rod are clamped with the center hole by springs. The two springs are fixed on the measuring rod. The side wall of the center hole is provided with a clamping groove for accommodating the springs.

[0016] A protective sleeve, a gasket, a washer and a nut are sequentially sleeved on the pull rod in a direction away from the lower anchor cup; the upper anchor cup is connected with an upper ear plate, the upper ear plate is fork-shaped, and a sling pin is installed on the upper ear plate.

[0017] The three-dimensional finite element model of the short suspension cable of the suspension bridge is established, and the stress analysis of the short suspension cable is performed to obtain the mechanical calculation results including:

[0018] The component models are assembled into a three-dimensional finite model, and the contact relationship and boundary conditions between the component models are set to perform stress condition analysis. The dead load and live load are converted into concentrated force, the cable tensioning is achieved through the temperature method, and the axial stress analysis of the cable is performed.

[0019] The optimization contents of the sleeve parameters include the diameter, thickness and thread length of the sleeve.

[0020] The optimization contents of the pull rod parameters include the length, diameter and thread length of the pull rod.

[0021] The length of the measuring rod is determined and adjusted according to actual engineering needs and finite element calculation results.

[0022] The force measurement calibration test of the short suspension cable of the intelligent sensing suspension bridge to determine the corresponding relationship between the short suspension cable force and the displacement sensed by the displacement sensor includes:

[0023] Carry out force measurement calibration, perform initial tensioning of the sling at 10% of the force, and release the tensioning force to eliminate the inelastic deformation between the connecting parts of the sling;

[0024] Tension the bottom end of the sling at 20%, 40%, 60%, 80% and 100% of the sling design force respectively, and record the displacement deformation of the measuring rod at the corresponding tensioning force;

[0025] Linear fitting is performed on the tension force and the deformation of the measuring rod to determine the measurement parameters of the position sensor.

[0026] Beneficial effects of the present invention: The present invention provides an intelligent measurement method for the cable force of the short cable of a suspension bridge, establishes an intelligent sensing short cable of a suspension bridge, performs force measurement calibration test on the short cable of the intelligent sensing suspension bridge, determines the corresponding relationship between the cable force of the short cable and the displacement sensed by the displacement sensor, and obtains accurate cable force measurement results of the short cable based on the real-time displacement data collected by the displacement sensor and the corresponding relationship between the cable force of the short cable and the displacement sensed by the displacement sensor. This method can overcome factors such as the boundary conditions of the short cable, the difficulty in identifying the fundamental frequency, and the great influence of the bending stiffness, and solves the problem of the difficulty in accurately measuring the cable force of the short suspension rod in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic flow chart of a method for intelligently measuring the cable force of a short sling of a suspension bridge according to the present invention;

[0028] Figure 2 It is a structural diagram of the short sling of the intelligent sensing suspension bridge designed by the present invention;

[0029] The reference numerals in the figure are as follows: 1-upper ear plate; 2-sling pin; 3-upper anchor cup; 4-sling; 5-steel strand; 6-sleeve; 7-pull rod; 8-washer; 9-nut; 10-measuring rod; 11-displacement sensor; 12-protective cover; 13-gasket. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the protection scope of the present invention.

[0031] Example 1

[0032] like Figure 1 As shown, the present invention discloses an intelligent method for measuring the cable force of a short sling of a suspension bridge, comprising the following steps:

[0033] Step one is to conduct preliminary structural design of the short cable of the suspension bridge, wherein the short cable of the suspension bridge includes a short cable and an upper anchor cup and a lower anchor cup connected at both ends thereof, the lower anchor cup is connected to the pull rod through a sleeve, a measuring rod for measuring its deformation is arranged in the pull rod, and the measuring rod is implanted in the displacement sensor.

[0034] Step 2: Establish a three-dimensional finite element model of the short cable of the suspension bridge, perform a stress analysis on the short cable, and obtain mechanical calculation results.

[0035] Step three, according to the mechanical calculation results and based on strength theory, the sleeve parameters are optimized so that the sleeve tensile performance is better than the tie rod and the lower end anchor cup, and the tie rod parameters are optimized so that the tie rod meets the safety requirements.

[0036] Step 4: Screen the area with uniform stress on the tie rod and use it as the best measurement area, then determine the length of the measuring rod.

[0037] Step five, based on the preliminary design structure of the short suspension cable of the suspension bridge, as well as the sleeve optimization parameters, the pull rod optimization parameters and the length parameters of the measuring rod, an intelligent sensing short suspension bridge is established.

[0038] Step six, conduct a force measurement calibration test on the short cables of the intelligent sensing suspension bridge to determine the corresponding relationship between the short cable force and the displacement sensed by the displacement sensor.

[0039] Step seven, based on the real-time displacement data collected by the displacement sensor, using the corresponding relationship between the short sling force and the displacement of the displacement sensor, an accurate measurement result of the short sling force is obtained.

[0040] The present invention utilizes the correspondence between the cable force of the short sling and the displacement sensed by the displacement sensor to obtain an accurate measurement result of the cable force of the short sling, which can overcome factors such as the boundary conditions of the short sling, the difficulty in identifying the fundamental frequency and the great influence of the bending stiffness, and solves the problem of the difficulty in accurately measuring the cable force of the short sling in the prior art.

[0041] Example 2

[0042] like Figure 1 As shown, the present invention discloses an intelligent method for measuring the cable force of a short sling of a suspension bridge, comprising the following steps:

[0043] Step 1: Conduct preliminary structural design of the short cables of the suspension bridge. Figure 2As shown, the short sling of the suspension bridge includes a sling 4 and an upper anchor cup 3 and a lower anchor cup 5 connected at both ends thereof, the lower anchor cup 5 is connected to the pull rod 7 through a sleeve 6, and a measuring rod 10 for measuring its deformation is arranged in the pull rod 7, and the measuring rod 10 is implanted in a displacement sensor 11. The displacement sensor 11 is replaceable and can be wired to transmit data. In the preliminary structural design of the short sling of the suspension bridge: a coaxial center hole is opened on the pull rod 7, the aperture of the center hole is 3.5mm, and the two ends of the measuring rod 10 are locked with the center hole. The measuring rod 10 coincides with the center line of the pull rod 7, the center line of the sling 4 coincides with the center line of the pull rod 7, the cable force of the sling 4 is the same as the axial force of the pull rod 7, and the deformation is consistent with that of the pull rod 7. The cable force of the sling is obtained by measuring the axial force of the pull rod 7. The measuring rod 10 is locked with the pull rod 7, forcing the measuring rod 10 and the pull rod 7 to maintain the same deformation. The measuring rod 10 obtains the displacement change of the pull rod 7 (the change in the distance between the two locking points) through the displacement sensor 11, and calculates the axial force of the pull rod 7. Since the axial force of the pull rod 7 is the same as the cable force of the sling, the cable force of the short sling can be accurately measured. Specifically, the two ends of the measuring rod 10 are locked with the center hole by springs, and the two springs are fixed on the measuring rod 10. A slot for accommodating the spring is provided on the side wall of the center hole. In addition, a protective sleeve 12, a gasket 13, a washer 8 and a nut 9 are sequentially sleeved on the pull rod 7 in the direction away from the lower end anchor cup 5; the upper end anchor cup 3 is connected to the upper end ear plate 1, the upper end ear plate 1 is fork-shaped, and the sling pin 2 is installed on the upper end ear plate 1.

[0044] Step 2: Establish a three-dimensional finite element model of the short cable of the suspension bridge, perform a force analysis on the short cable, and obtain mechanical calculation results. Assemble the component models into a three-dimensional finite model, set the contact relationship and boundary conditions between the component models, perform a force condition analysis, convert the dead load and live load into concentrated force, realize cable tensioning through the temperature method, and perform a cable axial force analysis.

[0045] Step three, according to the mechanical calculation results and based on strength theory, the sleeve parameters are optimized, including the sleeve diameter, thickness and thread length, so that the sleeve tensile performance is better than the tie rod and the lower end anchor cup, and the tie rod parameters are optimized, including the tie rod length, diameter and thread length, so that the tie rod meets the safety requirements.

[0046] Step 4: Screen the area with uniform stress on the tie rod and use it as the best measurement area, and then determine the length of the measuring rod 10. The length of the measuring rod 10 is adjusted according to actual engineering needs and finite element calculation results.

[0047] Step five, based on the preliminary design structure of the short suspension cable of the suspension bridge, as well as the sleeve optimization parameters, the pull rod optimization parameters and the length parameters of the measuring rod, an intelligent sensing short suspension bridge is established.

[0048] Step 6: Conduct a force measurement calibration test on the short cable of the intelligent sensing suspension bridge to determine the corresponding relationship between the cable force of the short cable and the displacement sensed by the displacement sensor. During the force measurement calibration, perform an initial tensioning of the cable force at 10%, release the tensioning force to eliminate the inelastic deformation between the connecting parts of the cable; tension the bottom end of the cable at 20%, 40%, 60%, 80%, and 100% of the cable design force, and record the deformation of the measuring rod at the corresponding tensioning force; perform linear fitting on the tensioning force and the deformation of the measuring rod to determine the measurement parameters of the position sensor.

[0049] Step seven, based on the real-time displacement data collected by the displacement sensor, using the corresponding relationship between the short sling force and the displacement sensed by the displacement sensor, an accurate measurement result of the short sling force is obtained.

[0050] The above are only preferred embodiments of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An intelligent method for measuring the cable force of a short suspension cable of a suspension bridge, characterized in that: The following steps are involved: The short suspension cable of the suspension bridge is preliminarily designed. The short suspension cable of the suspension bridge includes the suspension cable and an upper anchor cup and a lower anchor cup connected at both ends thereof. The lower anchor cup is connected to the pull rod through a sleeve. A measuring rod for measuring its deformation is arranged in the pull rod. The measuring rod is implanted in the displacement sensor. Establish a three-dimensional finite element model of the short cable of the suspension bridge, conduct a stress analysis on the short cable, and obtain mechanical calculation results; According to the mechanical calculation results and based on the strength theory, the sleeve parameters are optimized to generate sleeve optimization parameters so that the sleeve tensile performance is better than the tie rod and the lower end anchor cup, and the tie rod parameters are optimized to generate tie rod optimization parameters so that the tie rod meets the safety requirements; Based on the preliminary structural design, a region with uniform stress on the tie rod is selected and used as the best measurement region, and then the length of the measuring rod is determined to generate a length parameter of the measuring rod; According to the preliminary design structure of the short suspension cable of the suspension bridge, as well as the sleeve optimization parameters, the pull rod optimization parameters and the length parameters of the measuring rod, the intelligent sensing short suspension cable of the suspension bridge is established; A force measurement calibration test was conducted on the short cables of the intelligent sensing suspension bridge to determine the corresponding relationship between the cable force of the short cables and the displacement sensed by the displacement sensor. Based on the real-time displacement data collected by the displacement sensor, the measurement result of the short sling force is obtained by utilizing the corresponding relationship between the short sling force and the displacement sensed by the displacement sensor.

2. The intelligent cable force measurement method of the short suspension cable of a suspension bridge according to claim 1 is characterized in that: In the preliminary structural design of the short suspension cable of the suspension bridge: a coaxial center hole is opened on the pull rod, and the two ends of the measuring rod are locked with the center hole.

3. The intelligent cable force measurement method of the short suspension cable of a suspension bridge according to claim 2 is characterized in that: The two ends of the measuring rod are clamped with the center hole by springs. The two springs are fixed on the measuring rod. The side wall of the center hole is provided with a clamping groove for accommodating the springs.

4. The intelligent cable force measurement method of the short suspension cable of a suspension bridge according to claim 2 is characterized in that: A protective sleeve, a gasket, a washer and a nut are sequentially sleeved on the pull rod in a direction away from the lower anchor cup; the upper anchor cup is connected with an upper ear plate, the upper ear plate is fork-shaped, and a sling pin is installed on the upper ear plate.

5. The intelligent cable force measurement method of a short suspension cable of a suspension bridge according to claim 1 is characterized in that: The three-dimensional finite element model of the short suspension cable of the suspension bridge is established, and the stress analysis of the short suspension cable is performed to obtain the mechanical calculation results including: The component models are assembled into a three-dimensional finite model, and the contact relationship and boundary conditions between the component models are set to perform stress condition analysis. The dead load and live load are converted into concentrated force, the cable tensioning is achieved through the temperature method, and the axial stress analysis of the cable is performed.

6. The intelligent cable force measurement method of a short suspension cable of a suspension bridge according to claim 1 is characterized in that: The optimization contents of the sleeve parameters include the diameter, thickness and thread length of the sleeve.

7. The intelligent cable force measurement method of a suspension bridge short cable according to claim 1 is characterized in that: The optimization contents of the pull rod parameters include the length, diameter and thread length of the pull rod.

8. The intelligent cable force measurement method of a short suspension cable of a suspension bridge according to claim 1 is characterized in that: The length of the measuring rod is determined and adjusted according to actual engineering needs and finite element calculation results.

9. The intelligent cable force measurement method of a suspension bridge short cable according to claim 1 is characterized in that: The force measurement calibration test of the short suspension cable of the intelligent sensing suspension bridge to determine the corresponding relationship between the short suspension cable force and the displacement sensed by the displacement sensor includes: Carry out force measurement calibration, perform initial tensioning of the sling at 10% of the force, and release the tensioning force to eliminate the inelastic deformation between the connecting parts of the sling; Tension the bottom end of the sling at 20%, 40%, 60%, 80% and 100% of the sling design force respectively, and record the deformation of the measuring rod at the corresponding tensioning force; Linear fitting is performed on the tension force and the deformation of the measuring rod to determine the measurement parameters of the displacement sensor.

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