Multiple simultaneous automatic tensioning system and multiple simultaneous automatic tensioning method

Abstract

To provide an automatic simultaneous multi tensioning system and automatic simultaneous multi tensioning method capable of reducing the stress load applied to concrete when tensioning a plurality of PC cables.SOLUTION: A tensioning system includes: a plurality of tensioners 1a to 1d that tension-drive a plurality of PC cables C1, C2 respectively with hydraulic pumps 4a to 4d and tension jacks 3a to 3d, and that acquire the elongation amount of each of the PC cables C1, C2 and the tension pressure of each of the hydraulic pumps 4a to 4d; and a control device 10 connected to each of the tensioners 1a to 1d for communication and that performs tension-control of the PC cables C1, C2 with each of the tensioners 1a to 1d while monitoring the elongation amount and the tension pressure of each of the tensioners 1a to 1d. The control device 10 performs simultaneous tension control with the tensioners 1a to 1d, and drive-controls the tensioners 1a to 1d so that the pressure difference among the tensioners 1a to 1d is less than a prescribed value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a multiple simultaneous automatic tensioning system and multiple simultaneous automatic tensioning method that can reduce the stress load on concrete when tensioning multiple PC cables. [Background technology]

[0002] In prestressed concrete bridges (PC bridges), tensioning of the prestressing steel (PC cable) is one of the important construction processes that significantly affects the load-bearing capacity and durability of the structure. Traditionally, tension management of PC cables has relied heavily on manual procedures, such as operating tensioning jacks, measuring tension pressure and PC cable elongation, and creating tension management tables. In recent years, however, tension management systems have been developed that automate everything from measuring hydraulic pump pressure and PC cable elongation to pump operation. This reduces the labor required for tension management and also improves and stabilizes the accuracy of measurement management. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-117215 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-125232 Summary of the Invention [Problem to be solved by the invention]

[0004] However, conventional automatic tension management systems only managed the tension of each PC cable individually, not multiple PC cables at the same time. This resulted in unbalanced tension in each PC cable, which caused problems in wide or curved bridges, with stress being distributed only partially to the concrete.

[0005] The present invention has been made in consideration of the above, and aims to provide a multiple simultaneous automatic tensioning system and multiple simultaneous automatic tensioning method that can reduce the stress burden on concrete when tensioning multiple PC cables. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the present invention provides a system comprising a plurality of tensioning machines that tension each of a plurality of PC cables using a hydraulic pump and a tensioning jack, and acquires the amount of elongation of each PC cable and the tensioning pressure of each hydraulic pump, and a control device that is communicatively connected to each tensioning machine and controls the tension of the PC cables using each tensioning machine while monitoring the amount of elongation and the tensioning pressure of each tensioning machine, wherein the control device simultaneously controls the tensioning of each tensioning machine and drives and controls each tensioning machine so that the pressure difference between each tensioning machine is less than a predetermined value.

[0007] In addition, in the above invention, the present invention is characterized in that when the tensioning device reaches a final pre-tensioning pressure, which is the final tensioning pressure reached by applying a predetermined pressure, the control device temporarily stops the tensioning pressure, and when all tensioning devices have reached the final pre-tensioning pressure, the control device simultaneously re-tensions each tensioning device.

[0008] In addition, in the above invention, the present invention is characterized in that the control device stops tensioning of all tensioning machines and outputs an alarm if the tensioning pressure exceeds the set range or the absolute upper limit value while at least one of the tensioning machines is under tension control.

[0009] In addition, the present invention is characterized in that a control device is communicatively connected to a plurality of tensioning machines that tension each of a plurality of PC cables using a hydraulic pump and a tensioning jack, and acquires the amount of elongation of each PC cable and the tensioning pressure of each hydraulic pump, and simultaneously controls the tension of the PC cables using each tensioning machine while monitoring the amount of elongation and the tensioning pressure of each tensioning machine, and drives and controls each tensioning machine so that the pressure difference between each tensioning machine is less than a predetermined value.

[0010] In addition, in the above invention, the present invention is characterized in that when the tensioning device reaches a final pre-tensioning pressure, which is the final tensioning pressure reached by applying a predetermined pressure, the control device temporarily stops the tensioning pressure, and when all tensioning devices have reached the final pre-tensioning pressure, the control device simultaneously re-tensions each tensioning device.

[0011] In addition, in the above invention, the present invention is characterized in that the control device stops tensioning of all tensioning machines and outputs an alarm if the tensioning pressure exceeds the set range or the absolute upper limit value while at least one of the tensioning machines is under tension control. [Effects of the Invention]

[0012] According to the present invention, the stress load on concrete when tensioning multiple PC cables can be reduced. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a block diagram showing the configuration of a multiple simultaneous automatic tensioning system according to this embodiment. [Figure 2] Figure 2 shows a cross section of a box girder bridge. [Figure 3] FIG. 3 is a diagram showing an example of a tension management input / output screen displayed on the input / output unit. [Figure 4] FIG. 4 is a flowchart showing the procedure of the tension control process performed by the control unit. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0015] <Device configuration> FIG. 1 is a block diagram showing the configuration of a multiple simultaneous automatic tensioning system 1 according to the present embodiment. This embodiment illustrates an example in which two PC cables C1 and C2, which are prestressing steel members for a box girder bridge 100, are tensioned in the bridge axis direction. However, this is not limiting. FIG. 2 is a cross-sectional view of the box girder bridge 100, in which the two PC cables C1 and C2 are tensioned in the bridge axis direction at two locations, left and right, perpendicular to the bridge axis direction. This embodiment is applied to a cast-in-place post-tensioning method in which the two PC cables C1 and C2 are tensioned with tensioning jacks to introduce prestress into the box girder bridge after the concrete strength is developed. Because the box girder bridge 100 is a box girder bridge, the PC cables C1 and C2 pass through the internal space within the box girder bridge 100. While FIG. 2 illustrates an internal cable tensioning method, this embodiment can also be applied to an external cable tensioning method in which the PC cables C1 and C2 are placed outside the web concrete member (inside the cross beam and deflection section).

[0016] 1, the multiple simultaneous automatic tensioning system 1 includes multiple tensioning machines 1a to 1d and a control device 10. The multiple tensioning machines 1a to 1d and the control device 10 are wirelessly connected by Wi-Fi (registered trademark) or the like, but may also be connected by wire.

[0017] The tensioning machines 1a and 1b are devices that tension the PC cable C1 from both ends of the PC cable C1. The tensioning machines 1c and 1d are devices that tension the PC cable C2 from both ends of the PC cable C2. Each tensioning machine 1a to 1d has a hydraulic control device 2a to 2d and a tensioning jack 3a to 3d, respectively. The tensioning jacks 3a to 3d, hydraulic pumps 4a to 4d, and displacement sensors 13a to 13d arranged on each tensioning jack 3a to 3d are connected to the hydraulic control devices 2a to 2d, respectively. The tensioning jacks 3a to 3d tension the PC cables C1 and C2 using hydraulic pressure supplied from the hydraulic pumps 4a to 4d. The displacement sensors 13a to 13d detect the amount of elongation of the PC cables C1 and C2 at each tensioning jack 3a to 3d.

[0018] The hydraulic control devices 2a to 2d each have a drive control unit 5a to 5d, a pressure sensor 6a to 6d, and a communication unit 7a to 7d. The drive control units 5a to 5d drive and control the tensioning jacks 3a to 3d and the hydraulic pumps 4a to 4d, respectively, under the control of the control device 10, and output the extension amounts detected by the displacement sensors 13a to 13d and the tension pressures of the hydraulic pumps 4a to 4d detected by the pressure sensors 6a to 6d to the control device 10. The communication units 7a to 7d are each a communication interface that performs communication processing with the control device 10.

[0019] The control device 10 is a control device that controls simultaneous tensioning of the PC cables C1 and C2 via the tensioners 1a to 1d, and is, for example, a personal computer. It has an input / output unit 11, a communication unit 12, a memory unit 13, and a control unit 14. The input / output unit 11 is an input / output device such as a touch panel display, and inputs and outputs various information. The input / output unit 11 may be configured as a separate input device and output device. The communication unit 12 is a communication interface that performs communication processing with the tensioners 1a to 1d. The memory unit 13 is a storage device such as a non-volatile memory or a hard disk drive, and stores setting information D1 and a management table D2. The setting information D1 is design data for tension management of the PC cables C1 and C2, and is stored in advance in the memory unit 13. The management table D2 is data indicating the current tension status and results of the tension of each PC cable C1 and C2.

[0020] The control unit 14 is a control unit that controls the entire multiple simultaneous automatic tension system 1, and has a tension control unit 15 and a management table generation unit 16. The control unit 14 stores programs corresponding to these functional units in a storage device such as a non-volatile memory, and executes the corresponding processes by loading these programs into memory and running them on the CPU.

[0021] The tension control unit 15 simultaneously controls the tension of the PC cables C1 and C2 using each tensioning unit 1a-1d while monitoring the elongation and tensioning pressure detected by each tensioning unit 1a-1d, and drives and controls each tensioning unit 1a-1d so that the pressure difference between each tensioning unit 1a-1d is less than a predetermined value. When each tensioning unit 1a-1d reaches a final pre-tensioning pressure, which is reached by applying a predetermined pressure, the tension control unit 15 temporarily stops the tensioning pressure. When all tensioning units have reached the final pre-tensioning pressure, the tensioning unit 15 simultaneously re-tensions each tensioning unit 1a-1d. Furthermore, when the tensioning pressure of at least one of the tensioning units 1a-1d exceeds the set range or the absolute upper limit during tensioning control, the tension control unit 15 stops the tensioning of all tensioning units 1a-1d and outputs an alarm.

[0022] The control table generating unit 16 generates and displays a control table D2 showing the relationship between the amount of elongation and the tensioning pressure in real time during tension control, and also generates and outputs various related control charts.

[0023] <Tension management input / output screen> Fig. 3 is a diagram showing an example of a tension management input / output screen displayed on the input / output unit 11. As shown in Fig. 3, the tension management input / output screen has, for example, a tension data display area E1, a tension management data area E2, and an operation area E3.

[0024] The tension data display area E1 displays, for example, the tension pressure and pressure difference of the PC cables C1 and C2 at the time of design, as well as data showing the current tension pressure and pressure difference of the PC cables C1 and C2 during tension control in real time.

[0025] The tension management data area E2 displays, for example, management tables D21 and D22 showing the relationship between the tension pressure P and the elongation ΔL for each PC cable C1 and C2. The management tables D21 and D22 display an upper limit line Lu and a lower limit line Ld indicating the setting range. The setting range for tension pressure application is the area surrounded by the upper limit line Lu and the lower limit line Ld. A retention line Ls is also displayed. The retention line Ls is a line indicating the tension pressure and elongation amount at which tension ends, and tension ends when the tension correction line L intersects with the retention line Ls. The retention line Ls may also be a retention line using a friction coefficient.

[0026] The sequentially measured elongation ΔL and tension pressure P are plotted as actual measurement points PD on management tables D21 and D22. On the other hand, the tension correction line L is a line obtained by correcting the preliminary tension pressure applied when the elongation ΔL is 0 to 0. Specifically, it is a line obtained by shifting the absolute value of the negative elongation when the actual lateral line tension pressure P estimated from the sequence of actual measurement points PD is 0 to the positive side of the actual measurement line. The tension control unit 15 controls each tensioning device 1a-1d so that this tension correction line L falls within a set range, and also controls the pressure difference between each tensioning device 1a-1d, i.e., the pressure difference between the PC cables C1 and C2, to be less than a predetermined value. During actual tension control, actual measurement points PD are sequentially added, and the tension correction line L is sequentially extended and updated.

[0027] The final tension pressure line Lb indicates the final tension pressure at the point where the tension correction line L and the restraint line Ls intersect. The pre-final tension pressure line La indicates a pressure that is a predetermined pressure lower than the final tension pressure, specifically a pressure that is approximately 0.5 to 5.0 MPa lower than the final tension pressure. The tension control unit 15 controls and stops the tension pressures of all tensioners 1a to 1d until they reach the pre-final tension pressure. Once the tension pressures of all tensioners 1a to 1d reach the pre-final tension pressure, all tensioners 1a to 1d are simultaneously re-tensioned to reach the final tension pressure. The absolute upper limit line Lx indicates the upper limit of the tension pressure. Therefore, if the tension pressure of at least one of the tensioners 1a to 1d exceeds the set range defined by the upper limit line Lu and the lower limit line Ld, or exceeds the absolute upper limit value indicated by the absolute upper limit line Lx, the tension control unit 15 stops the tension of all tensioners 1a to 1d and outputs an alarm. The upper limit line Lu and the lower limit line Ld are set because even for PC cables of the same shape, the relationship between tension pressure and elongation varies depending on error factors, and the upper limit line Lu and the lower limit line Ld are values ​​statistically processed based on standard error, etc.

[0028] The operation area E3 is provided with GUIs such as a start button B1, a tension button B2, a fix button B3, a pressure release button B4, a control chart button B5, and an emergency stop button B6. The start button B1 is a button that applies a preliminary tensioning pressure, for example, 0.5 MPa. The tension button B2 is a button that starts tensioning each of the tensioners 1a to 1d simultaneously. The fix button B3 is a button that instructs the simultaneous release of tensioning pressure on the PC cables C1 and C2 in order to fix the wedge in the anchor head. The pressure release button B4 is a button that instructs the release of pressure to remove the tensioning jacks 3a to 3d. The control chart button B5 is a button that generates and outputs various control charts, including the currently displayed control tables D21 and D22. The emergency stop button B6 is an emergency button that the operator can use to instruct the operator to temporarily suspend and maintain tensioning by all the tensioners 1a to 1d. The control chart may be, for example, a group control chart that graphs the state of the final tension pressure of each of the PC cables C1 and C2.

[0029] <Tension control procedure> Fig. 4 is a flowchart showing the procedure of the tension control process performed by the control unit 14. As shown in Fig. 4, the control unit 14 first detects pressing of the start button B1 and simultaneously applies a preliminary tension pressure to the tension jacks 3a to 3d (step S110). When this preliminary tension pressure is applied, the amount of elongation of the PC cables C1 and C2 is set to 0.

[0030] Thereafter, by pressing the tension button B2, tensioning is started simultaneously for each of the tensioning devices 1a-1d (step S120). The control unit 14 determines whether or not the set range has been exceeded during this tension control (step S130). If the set range has not been exceeded (step S130: No), it then determines whether or not the tension pressure P has exceeded the absolute upper limit line Lx (step S140). If the set range has been exceeded (step S130: Yes) or if the tension pressure P has exceeded the absolute upper limit line Lx (step S140: Yes), tension is stopped and an alarm is output (step S160), and this process ends.

[0031] If the tensioning pressure P does not exceed the absolute upper limit line Lx (Step S140: No), the system further determines whether the pressure difference between the tensioning pressures of the tensioning units 1a-1d, i.e., the pressure difference between the PC cables C1 and C2, is equal to or greater than a predetermined value (Step S150). If the pressure difference between the tensioning pressures of the tensioning units 1a-1d is equal to or greater than the predetermined value (Step S150: Yes), the system stops tensioning the PC cable with the higher tensioning pressure (Step S170) and determines whether the pressure difference has become less than the predetermined value (Step S180). If the pressure difference does not become less than the predetermined value (Step S180: No), the system proceeds to Step S170, and continues to stop tensioning the PC cable with the higher tensioning pressure. If the pressure difference becomes less than the predetermined value (Step S180: Yes), the system proceeds to Step S190. This prevents the tensioning pressure between the PC cables C1 and C2 from increasing, thereby reducing the stress load on the concrete.

[0032] Next, in step S190, it is determined whether any PC cable has reached the final pre-tensioning pressure (final tensioning pressure - (0.5 to 5.0) MPa). If no PC cable has reached the final pre-tensioning pressure (step S190: No), this determination process is repeated. If any PC cable has reached the final pre-tensioning pressure (step S190: Yes), tensioning of this PC cable is stopped (step S200). Next, it is determined whether all PC cables have reached the final pre-tensioning pressure (step S210). If all PC cables have not reached the final pre-tensioning pressure (step S210: No), the process proceeds to step S190. If all PC cables have reached the final pre-tensioning pressure (step S210: Yes), tensioning of all PC cables is resumed simultaneously (step S220). Note that tensioning may be resumed by pressing the tension button B2. A display indicating which PC cables have reached the final pre-tensioning pressure may also be displayed in the tension data display area E1.

[0033] Then, it is determined whether all the PC cables have reached the final tension pressure (step S230). If all the PC cables have not reached the final tension pressure (step S230: No), this determination process is repeated. If all the PC cables have reached the final tension pressure (step S230: Yes), the tension on all the PC cables is stopped (step S240). This ends the tension on all the PC cables.

[0034] Thereafter, the control unit 14 fixes the wedge to the anchor head (step S250). Furthermore, the control unit 14 unloads all of the tensioning jacks 3a to 3d (step S260) and removes all of the tensioning jacks 3a to 3d (step S270). Thereafter, the control unit 14 confirms that the tension management is appropriate based on the control chart including the control tables D21 and D22, and then cuts the PC cable (step S280), thereby terminating this process.

[0035] In this embodiment, tensioning control of the PC cables C1 and C2 is performed simultaneously by each tensioning machine 1a to 1d, and each tensioning machine 1a to 1d is driven and controlled so that the pressure difference between each tensioning machine 1a to 1d is less than a predetermined value, so that the stress burden on the concrete can be reduced while constructing a PC bridge.

[0036] In the above embodiment, the tension of PC cables in a box girder bridge has been described, but the present invention can also be applied to tension control in other bridges, such as bridges with hollow decks. Furthermore, the present invention can be applied to prestressing methods using post-tensioning methods, not limited to bridges. It can also be applied to prestressing methods using sheaths.

[0037] Note that the configurations illustrated in the above embodiments are merely functional schematics and are not necessarily physically configured as shown. In other words, the distribution and integration of each device and component is not limited to that illustrated, and all or part of them can be functionally or physically distributed and integrated in any unit depending on various usage situations, etc. [Explanation of symbols]

[0038] 1. Multiple simultaneous automatic tension system 1a~1d Tension machine 2a~2d Hydraulic control device 3a~3d Tension jack 4a~4d Hydraulic pump 5a to 5d Drive control unit 6a~6d Pressure sensors 7a~7d,12 Communication Department 10 Control device 11 Input / output section 13 Storage section 13a~13d Displacement sensors 14 Control Unit 15 Tension control section 16 Management table generator 100 Box girder bridge B1 Start button B2 Tension button B3 Fixing button B4 Pressure release button B5 Control Chart Button B6 Emergency stop button C1, C2 PC cable D1 Setting information D2,D21,D22 management table E1 Tension data display area E2 Tension management data area E3 operation area L tension correction line La Final pre-tension pressure line Lb Final tension pressure line Ld lower limit line Ls Retaining line Lu upper limit line Lx absolute upper limit P tension pressure PD measurement point ΔL Elongation

Claims

1. a plurality of tensioning machines that tension each of the plurality of PC cables using a hydraulic pump and a tensioning jack, and acquire the amount of elongation of each PC cable and the tensioning pressure of each hydraulic pump; a control device that is communicatively connected to each tensioning device and that controls the tension of the PC cable by each tensioning device while monitoring the elongation amount and the tensioning pressure of each tensioning device; Equipped with The control device simultaneously controls tensioning by each tensioning device and drives and controls each tensioning device so that the pressure difference between each tensioning device is less than a predetermined value.When a tensioning device reaches a final pre-tensioning pressure, which is reached by applying a predetermined pressure, the tensioning pressure is temporarily stopped, and when all tensioning devices have reached the final pre-tensioning pressure, the multiple simultaneous automatic tensioning system is characterized by the above.

2. The multiple simultaneous automatic tensioning system described in claim 1, characterized in that the control device stops tensioning of all tensioning machines and outputs an alarm if the tensioning pressure exceeds a set range or an absolute upper limit value during tensioning control of at least one of the tensioning machines.

3. A method for automatically tensioning a plurality of PC cables simultaneously, the method comprising: driving a hydraulic pump and a tensioning jack to tension each of the plurality of PC cables; and a control device communicatively connected to a plurality of tensioning machines that acquires the amount of elongation of each PC cable and the tensioning pressure of each hydraulic pump; monitoring the amount of elongation and the tensioning pressure of each tensioning machine; and simultaneously controlling the tension of the PC cables by each tensioning machine, and controlling the drive of each tensioning machine so that the pressure difference between the tensioning machines is less than a predetermined value, The control device temporarily stops tensioning pressure when the tensioning device reaches a final pre-tensioning pressure, which is the final tensioning pressure reached by applying a predetermined pressure, and when all tensioning devices have reached the final pre-tensioning pressure, simultaneously re-tensions each tensioning device.

4. The method for automatically tensioning multiple tensioners simultaneously as described in claim 3, characterized in that the control device stops tensioning of all tensioners and outputs an alarm if the tensioning pressure exceeds a set range or an absolute upper limit value during tensioning control of at least one of the tensioners.

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