A method for testing the traction force of the puller and the strand force during the erection of the main cable strands of a suspension bridge.

Abstract

This invention relates to the field of suspension bridge main cable erection technology, specifically to a method for testing the traction force of the main cable strands and the cable force of the traction cables before and after the puller of a suspension bridge. The testing method includes the following steps: First, the tension of the cable strands is tested. Two cable strand tension rod sensors are set up, and a full-bridge measurement circuit is used for cable strand tension rod measurement. Strain gauges are arranged along the axis of the rod on the circular cross-section of the tension rod, and two compensation plates made of the same material as the tension rod but not bearing external loads are set up, with resistance strain gauges attached to them respectively. Then, the traction force of the front and rear traction cables of the puller is tested. Two wedge joint sensors are set up, and the measurement method at the two measuring points is the same, using a half-bridge measurement circuit. Strain gauges are arranged along the traction direction of the traction cable on the upper surface of the wedge joint, and compensation plates made of the same material as the wedge joint but not bearing external loads are set up, with resistance strain gauges attached to them. Finally, the cable strands and the front and rear traction cables of the puller are calibrated using a testing machine, and calibration equations for the input values ​​and sensor test values ​​are established. Based on the calibration equations, the monitoring data of the tension rod sensors and wedge joint sensors during the working process are output, and finally, the accurate cable strand traction force and the cable force of the front and rear traction cables of the puller are obtained.

Description

[Technical Field]

[0001] This invention relates to the field of tension testing of traction cables, and particularly to a method and apparatus for testing the tension of the traction cable and strands of a traction device during the erection of the main cable strands of a suspension bridge. [Background Technology]

[0002] This invention relates to the field of suspension bridge main cable erection technology, specifically to a method for testing the traction force of the main cable strands and the cable force of the traction cables before and after the puller of a suspension bridge.

[0003] Primarily based on the construction of main cable strands for extra-long span suspension bridges, this study aims to detect the tension in the traction cables before and after the puller, as well as the tension in the strands, to monitor the load-bearing status of the strands and the puller's traction cables in real time. This ensures construction safety and improves construction quality and efficiency. However, due to factors such as the complexity of the traction mechanism, limited space for sensor placement, and construction cost control, testing the tension in the strands and the traction cables before and after the puller during the main cable erection of suspension bridges is quite difficult.

[0004] Currently, commonly used cable force testing methods include wire rope tension testing, pressure testing, pressure sensor testing, magnetic flux testing, and frequency testing. Wire rope tension testing requires a large setup space, the rope cannot move continuously relative to the force measuring device of the pulley system, and it cannot pass through the pulley system of the suspension bridge main cable erection system. Pressure testing and pressure sensor testing are only applicable to jack tensioning systems. Magnetic flux testing measures cable force by measuring changes in the magnetic flux of the traction cable using an electromagnetic sensor, but the magnetic flux is significantly affected by ambient temperature. Frequency testing measures cable force by measuring the cable's vibration frequency, but the continuous changes in the suspension length of the main cable strands and the position of the pulley system during the erection of the main cable of a suspension bridge result in a large range of variations in the cable vibration frequency. In summary, existing methods cannot meet the requirements for testing the traction force of the cable strands and the cable force of the traction cables before and after the pulley system during the erection of the main cable of a suspension bridge. [Summary of the Invention]

[0005] The purpose of this invention is to provide a method for testing the traction force of the main cable strands of a suspension bridge and the cable force of the traction cables before and after the puller, so as to solve the above-mentioned problems.

[0006] This invention employs the following technology: a device for testing the tension of a traction cable and its strands, comprising a tension rod sensor, a wedge-shaped joint sensor, a calibration fixture for the tension rod sensor, a calibration fixture for the wedge-shaped joint sensor, and several resistance strain gauges. Using a mechanical testing machine, calibration tests are conducted at the measuring points through the traction cable and its strands testing fixture to accurately obtain the calibration coefficients between the strain and load at the measuring points.

[0007] First, the tension of the cable strands was tested. Two cable strand tension rod sensors were set up, namely measuring point 1 and measuring point 2. The measurement method was the same for both measuring points. Taking measuring point 1 as an example, a full-bridge measurement circuit was used for the cable strand tension rod measurement. Strain gauges R1 and R3 were arranged along the axis of the rod on the vertical axis of the rod's circular cross-section at measuring point 1. Two compensation plates a and b, made of the same material as the tension rod and not subjected to external loads, were also set up. Resistance strain gauges R2 and R4 were attached to them respectively. R1, R2, R3, and R4 formed a full-bridge measurement circuit, with R1 and R3 arranged in relative positions within the measurement circuit. This measurement circuit achieved temperature self-compensation and measured the axial force of the lower left tension rod. Similarly, the axial force of the upper right tension rod could be obtained through measuring point 2. Therefore, the sum of the axial forces at measuring points 1 and 2 is the cable strand tension force. Next, the tension force of the cable before and after the puller was tested. Two wedge-shaped joint sensors were set up, namely measuring point 3 and measuring point 4. The measurement method was the same for both measuring points. Taking measuring point 3 as an example, the measurement of the front traction wedge joint uses a half-bridge measurement circuit. Strain gauge R1' is arranged at measuring point 3 on the upper surface of the wedge joint along the traction direction of the traction cable. A compensation gauge made of the same material as the wedge joint and not subjected to external load is also installed. A resistance strain gauge R2' is attached to this compensation gauge, forming a half-bridge measurement circuit with two fixed resistors R3' and R4'. R1' and R2' are positioned adjacent to each other in the measurement circuit. This circuit enables temperature self-compensation and front traction cable force testing. Similarly, the rear traction cable tension can be measured at measuring point 4.

[0008] [The improvements and beneficial effects of this invention compared to existing technologies]

[0009] This method for testing the cable force of a traction device is unprecedented. This invention has the following advantages: It provides a method for testing the traction force of the main cable strands of a suspension bridge and the cable force of the front and rear traction cables of the traction device. Based on the working principle and structural characteristics of the traction device, it does not require modification of the original structure. Only resistance strain gauges are arranged and a reasonable measurement circuit is formed. The traction force of the cable strands and the cable force of the front and rear traction cables of the traction device are tested through experimental calibration technology. This invention is simple to operate, has high testing accuracy, and low cost.

Detailed Implementation Methods

[0010] The invention will be further described below with reference to the accompanying drawings.

[0011] See Figures 1-6 This invention is a device for testing the tension of traction cables and strands of a traction device, comprising a tie rod sensor, a wedge joint sensor, a tie rod sensor calibration fixture, a wedge joint sensor calibration fixture, and several resistance strain gauges.

[0012] Please see Figure 1As shown in the figure, the tie rod sensor and the wedge joint sensor are connected to the anchor head front rod (9) and rear rod (8) via the anchor connecting plate (3) and lug (2). Strain gauges R1 and R3 are arranged along the rod axis at measuring point 1 on the circular section of the cable strand tie rod (4). Figure 1 In the CC cross-section, R1 and R3 are located in the middle of the tie rod along the axial direction, respectively, and are attached at the 0-degree and 180-degree positions of the tie rod cross-section. Two compensating plates, a and b, made of the same material as the cable tie rod and not bearing external loads, are installed, and resistance strain gauges R2 and R4 are attached to them respectively. R1, R2, R3, and R4 together form... Figure 2 In the full-bridge measurement circuit, the output signal of the bridge is proportional to the axial force F on the cable strand (4). X1 .

[0013] Measuring the axial force F of tie rod 5 X2 The principle is the same as the axial force principle of the tie rod. The total tension F on the cable strands X =F X1 +F X2 .

[0014] like Figure 1 and Figure 4 As shown, the front traction wedge joint (6) and the rear traction wedge joint (7) are connected by a connecting beam (1). Measuring points 3 and 4 are respectively pasted on the upper surfaces of the front traction wedge joint (6) and the rear traction cable wedge joint (7) in the figure. The measurement of the front traction wedge joint (6) adopts a half-bridge measuring circuit. Strain gauge R1' is arranged at measuring point 3, and a compensation plate of the same material as the wedge joint and not bearing external load is set. Resistance strain gauge R2' is pasted on it, and it forms a half-bridge measuring circuit with two fixed resistors R3' and R4'. The output signal of the bridge is proportional to the tension F of the left front traction cable. x3 Similarly, the tension F in the rear traction cable on the right side... X4 The measurement principle is the same as that of the front traction cable tension measurement principle.

[0015] To obtain more accurate measurement results, a calibration fixture for the pull rod sensor is set up as follows: Figure 3 As shown, it includes an upper pull head and a lower pull head with the same structure. Taking the upper pull head as an example, the upper pull head mainly includes an upper pull head pin (13), a vertical plate (12), a stiffening plate (11), a connecting plate (10), and a testing machine pull rod (14). The vertical plate (12), the stiffening plate (11), and the connecting plate (10) are connected to each other by welding. The upper pull head is connected to the testing machine pull rod (14) through the upper pull head pin (13). The upper end of the cable pull rod (4) passes through the connecting plate (10) and is tightened to the upper pull head through a nut (15), a spring washer (16), and a flat washer (17). Similarly, Figure 3The lower pull head is connected to the test machine pull head (19) on the test machine base via the pull head pin (18). The cable tie rod (4) passes through the pull head connecting plate and is connected to the pull head. During operation, the test machine applies a tensile load to the upper pull head of the cable tie rod sensor to complete the calibration test.

[0016] Similarly, to obtain more accurate measurement results, a wedge-shaped connector sensor calibration fixture is set up, such as... Figure 6 As shown, it includes a wedge-shaped connector upper pull head and a wedge-shaped connector lower pull head with the same structure. Taking the wedge-shaped connector upper pull head as an example, the wedge-shaped connector sensor upper pull head mainly includes a connecting pin 1 (24), a connecting pin 2 (25), an upper vertical plate (21), an upper connecting plate (22), and a lower vertical plate (23). The upper connecting plate (22) is connected to the upper vertical plate (21) and the lower vertical plate (23) by welding. The upper vertical plate (21) is connected to the upper pull rod (24) of the testing machine by the connecting pin 1 (25). 0) Connected to the lower plate (23), the lower plate (23) is connected to the wedge joint 1 (27) through the connecting pin 2 (25), the wedge joint 1 (27) is connected to the wedge joint 2 (6) where the measuring point 3 is located through the wire rope (29), similarly, the wedge joint pull head is connected to the test machine pull rod (30) on the test machine base through the lower connecting pin 3 (26), and the test machine applies tensile load to the test machine pull rod (20) of the wedge joint sensor during the working process to complete the calibration test.

Claims

1. A method for testing the traction force of the puller and the strand force during the erection of the main cable strands of a suspension bridge, characterized in that: This includes a pull rod sensor, a wedge joint sensor, a pull rod sensor calibration fixture, and a wedge joint sensor calibration fixture; The pull rod sensor includes a cable tie rod 1 (4) and a cable tie rod 2 (5). The cable tie rod 1 (4) and the cable tie rod 2 (5) of the puller are connected to the front connecting rod (9) and the rear connecting rod (8) of the anchor head through the anchor connecting plate (3) and the lug (2). The wedge-shaped joint sensor includes a front traction wedge joint (6) and a rear traction wedge joint (7), which are connected by a connecting beam (1). The calibration fixture for the pull rod sensor includes an upper pull head and a lower pull head with the same structure, as well as a cable pull rod 1 (4). The upper pull head includes an upper pull head pin (13), a vertical plate (12), a stiffener plate (11), a connecting plate (10), and a testing machine pull rod (14). The vertical plate (12), the stiffener plate (11), and the connecting plate (10) are connected to each other by welding. The upper pull head pin (13) is connected to the testing machine pull rod (14). The upper end of the cable pull rod 1 (4) passes through the connecting plate (10) and is tightened to the upper pull head through a nut (15), a spring washer (16), and a flat washer (17). The lower pull head is connected to the testing machine pull head (19) on the testing machine base through a lower pull head pin (18). The cable pull rod 1 (4) passes through the lower pull head connecting plate and is connected to the lower pull head. The cable pull rod 1 (4) can be replaced with a cable pull rod 2 (5) for calibration. The wedge-shaped connector sensor calibration fixture includes an upper wedge-shaped connector pull-up head and a lower wedge-shaped connector pull-down head with identical structures. The upper wedge-shaped connector sensor pull-down head mainly includes a connecting pin 1 (24), a connecting pin 2 (25), an upper vertical plate (21), an upper connecting plate (22), and a lower vertical plate (23). The upper connecting plate (22) is welded to the upper vertical plate (21) and the lower vertical plate (23) respectively. The upper vertical plate (21) is connected to the upper pull rod (20) of the testing machine through the connecting pin 1 (24). The lower vertical plate (23) is connected to the upper pull rod (20) of the testing machine through the connecting pin 1 (24). The wedge joint 1 (27) is connected to the connecting pin 2 (25). The wedge joint 1 (27) is connected to the wedge joint 2 (6) where the measuring point 3 is located via a steel wire rope 1 (29). The wedge joint pull head is connected to the testing machine pull rod (30) on the testing machine base via the lower connecting pin 3 (26). The wedge joint pull head is connected to the wedge joint 3 (28) via the connecting pin 4 (32). The wedge joint 3 (28) is connected to the wedge joint 4 (7) where the measuring point 4 is located via a steel wire rope 2 (31).

2. The method for testing the traction force of the puller and the strand force during the erection of the main cable strands of a suspension bridge according to claim 1, characterized in that... The tension rod sensor is provided with a cable-strand tension rod 1 (4) and a cable-strand tension rod 2 (5). The cable-strand tension rod 1 (4) has a measuring point 1 set at the middle position along the length of the rod, and the cable-strand tension rod 2 (5) has a measuring point 2 set at the middle position along the length of the rod. The measuring point 1 is composed of a Wheatstone full-bridge measurement circuit consisting of resistance strain gauges R1, R2, R3 and R4. R1 and R3 are respectively attached to the middle of the tension rod along the length of the rod. R1 and R3 are attached at the 0-degree and 180-degree positions of the cross-section of the tension rod. R2 and R4 are respectively attached to the surfaces of two compensation plates a and b made of the same material as the cable-strand tension rod and not bearing external loads. R1 and R3 are adjacent bridge arms of the Wheatstone full-bridge measurement circuit, and R2 and R4 are adjacent bridge arms of the Wheatstone full-bridge measurement circuit. The measurement method of the measuring point 2 is the same as that of the measuring point 1.

3. The method for testing the traction force of the puller and the strand force during the erection of the main cable strands of a suspension bridge according to claim 1, characterized in that: The front traction wedge joint (6) and the rear traction wedge joint (7) are connected by a connecting beam (1). Measuring points 3 and 4 are respectively pasted on the upper surfaces of the front traction wedge joint (6) and the rear traction cable wedge joint (7) in the figure. The front traction wedge joint (6) is measured using a half-bridge measuring circuit. Strain gauge R1' is arranged at measuring point 3, and a compensation plate of the same material as the wedge joint and not subjected to external load is set. Resistance strain gauge R2' is pasted on it, and it forms a half-bridge measuring circuit with two fixed resistors R3' and R4'. The strain gauges R1' and R2' are located on adjacent bridge arms. The measuring method of measuring point 4 is the same as that of measuring point 3.

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