Anchoring device, and installation method of outer cable

Abstract

To provide an installation method of an outer cable capable of improving workability when reinforcing a lower structure of a bridge through a reinforcement method by an outer cable method even when spaces around the bridge have constraint.SOLUTION: An anchoring device of an outer cable introducing pre-stress in a lower structure of a bridge is provided with: a frame arranged so as to surround an end of the lower substrate in a pre-stress introducing direction; and a pair of cable anchoring parts arranged on both ends of the frame. The cable anchoring part includes an anchoring plate on which the outer cable is anchored and a work space to apply tension to the outer cable continued in the frame from the anchoring plate, and the anchoring plate is placed within an area of a side surface along the pre-stress introducing direction of the lower structure.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an external cable anchoring device used to introduce prestress into the substructure of a bridge, and to an external cable installation method using the anchoring device. [Background technology]

[0002] External cable bridge reinforcement methods have been known for some time, in which external cables are used to introduce prestress into concrete bridge girders and piers. For example, in Patent Document 1, a pair of steel brackets (anchoring devices) with cable support parts are installed at a distance below the existing bridge girder, and then both ends of the external cable are anchored to each of the cable support parts (anchoring parts), reinforcing the existing bridge girder.

[0003] Specifically, a pair of roughly U-shaped steel brackets are prepared and placed at a distance from each other at the longitudinal center of the lower part of the existing bridge girder. The steel brackets are then fastened to the existing bridge girder using fasteners inserted through through-holes in the existing bridge girder, with the lower part of the existing bridge girder fitted in place. The outer cable is then tensioned and both ends are secured to the cable support parts installed at the bottom of the steel brackets.

[0004] The steel brackets in Patent Document 1 can be used to reinforce not only bridge girders but also structures such as the beams of bridge piers, but require a process of drilling through holes in the structure to be reinforced in order to install the steel brackets. The process of drilling such through holes is complicated, as it is necessary to take into consideration the interference of reinforcing bars, and this creates issues with workability.

[0005] Furthermore, since the pair of steel brackets are installed in the longitudinal middle of the structure to be reinforced, prestress is introduced by the tension of the outer cable in the section of the existing structure to be reinforced that is sandwiched between the pair of steel brackets. However, since tensile forces are generated on both sides of the prestressed section, in some cases it may be necessary to install a separate structure to reinforce both sides.

[0006] For this reason, for example, Patent Document 2 discloses a configuration in which an external cable is used to reinforce a newly constructed beam section by integrating the beam section with both ends of an existing pier, and a fixing section for fixing the end of the external cable is provided at the end of the newly constructed beam section. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2023-141428 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-234687 Summary of the Invention [Problem to be solved by the invention]

[0008] When an anchoring point for an external cable is provided at the end of the beam of a bridge pier, work space is required for tensioning the external cable and space is required to install the anchoring device that secures the tensioned external cable to the anchoring point. However, this space is provided at a position that extends significantly beyond the end of the beam, that is, at a position that extends outside the road bridge.

[0009] For this reason, if there are restrictions such as the proximity of surrounding structures or the construction gauge to the road bridge, it will be impossible to secure the above-mentioned space. Even if such space can be secured, the anchoring part that secures the end of the outer cable will be placed in an exposed position that protrudes outside the road bridge and is easily exposed to rain and snow, which will pose a durability issue.

[0010] The present invention was developed in consideration of such problems, and its main purpose is to improve the workability of the work of tensioning the external cable to introduce prestress into the bridge substructure, even when there are space restrictions around the bridge, and the durability of the fixing device that secures the tensioned external cable. [Means for solving the problem]

[0011] In order to achieve this purpose, the anchoring device of the present invention is an anchoring device for an external cable that introduces prestress into the substructure of a bridge, and is characterized in that it comprises a frame that is arranged to surround one end of the substructure in the prestress introduction direction, and a pair of cable anchoring portions provided at both ends of the frame, the cable anchoring portion including an anchoring plate to which the external cable is anchored, and the anchoring plate is arranged within the range of the side of the substructure that is along the prestress introduction direction.

[0012] The fixing device of the present invention is characterized in that the frame is formed so as to be separable into a plurality of parts.

[0013] The fixing device of the present invention is characterized in that a working space for tensioning the external cable is provided in an area continuing from the fixing plate into the frame.

[0014] The fixing device of the present invention is characterized in that a plurality of combinations of the frame and the pair of cable fixing portions are provided consecutively in the height direction of the lower structure.

[0015] The method for installing an external cable of the present invention is a method for installing an external cable using the anchoring device of the present invention, and is characterized by including the steps of: arranging the anchoring device so that the frame surrounds one end of the lower structure in the prestress introduction direction; arranging a pair of the external cables along a pair of side surfaces parallel to the prestress introduction direction of the lower structure; and tensioning the external cable by utilizing a working space provided in an area continuous from the anchoring plate into the frame, and anchoring one end of the external cable to the anchoring plate.

[0016] The method for installing an external cable of the present invention is characterized in that the anchoring devices are arranged in pairs at both ends of the substructure in the prestress introduction direction, and both ends of each of the pair of external cables are anchored to the anchoring plates provided on each of the pair of anchoring devices.

[0017] The method for erecting an external cable of the present invention is characterized in that the substructure is a beam portion of a bridge pier.

[0018] According to the anchoring device and external cable installation method of the present invention, the frame is arranged to surround one end of the substructure in the prestress direction, so that the cable anchoring parts provided on both ends of the frame are positioned inward from the end of the substructure, facing the side surface along the prestress direction. As a result, the anchoring plates included in the cable anchoring parts are also positioned within the range of the side surface along the prestress direction.

[0019] This means that, for example, when prestressing the beam portion of a pier as a substructure, if the anchoring plate, which is placed within the range of the side along the direction of prestress introduction, is positioned closer to the column portion of the pier, a large working space for tensioning the external cable can be secured in the area extending from the anchoring plate into the frame.

[0020] Therefore, even if there are constraints such as the proximity of surrounding structures or construction limits to road bridges, as long as the environment allows for the placement of an anchoring device, it is possible to efficiently carry out tensioning work on the external cable by utilizing the work space that continues from the anchoring plate inside the frame.

[0021] In addition, the work space can be used as a storage space for the fixing tool that secures the tensioned outer cable after the tensioning work of the outer cable is completed. This protects the fixing tool from damage due to external contact. Furthermore, even if the fixing device is in an outdoor environment where it is directly exposed to wind and rain, the fixing tool stored in the work space can be minimized in exposure to wind and rain, preventing the intrusion of rainwater, which could cause deterioration, and improving durability.

[0022] Furthermore, the external cable fixing device stored in the work space can prevent snow from accumulating on the fixing device in snowy areas, etc. This reduces the risk of snowfall accidents, which had to be addressed when the fixing device is in an environment where third parties can enter below it. [Effects of the Invention]

[0023] According to the present invention, cable anchoring sections equipped with anchoring plates are provided at both ends of a frame that is arranged to surround one end of the substructure in the prestress introduction direction.Therefore, even if there are space restrictions around the bridge, it is possible to utilize the work space secured in the area that continues from the anchoring plates within the frame, thereby improving the workability of the work of tensioning the external cable to introduce prestress into the substructure of the bridge, and the durability of the anchoring device that secures the tensioned external cable. [Brief explanation of the drawings]

[0024] [Figure 1] 10 is a diagram showing how a bridge pier is reinforced using an external cable method using the anchoring device of this embodiment. FIG. [Figure 2] 3A and 3B are diagrams illustrating a cable fixing portion of the fixing device according to the present embodiment. [Figure 3] 2 is a perspective view showing the details of the fixing device according to the present embodiment. FIG. [Figure 4] 2 is a detailed (planar) view of the fixing device according to the present embodiment; FIG. [Figure 5] 10A to 10C are diagrams illustrating a method for installing an external cable using the fixing device according to the present embodiment. [Figure 6] 10A and 10B are diagrams illustrating how an outer cable is tensioned in the present embodiment. [Figure 7] FIG. 10 is a diagram showing another example of the fixing device according to the present embodiment (part 1). [Figure 8] FIG. 10 is a diagram showing another example of the fixing device according to the present embodiment (part 2). [Figure 9] FIG. 10 is a diagram showing another example of the fixing device according to the present embodiment (part 3). DETAILED DESCRIPTION OF THE INVENTION

[0025] This invention is a device suitable for reinforcement construction using an external cable system, which uses external cables to introduce prestress into the substructure of a bridge to restore or improve the bearing capacity of the substructure. Below, we will explain the anchoring device and the external cable installation method using an example of reinforcing the beam part of a bridge pier, with reference to Figures 1 to 9.

[0026] Before describing the fixing device and the method for installing the external cable, the reinforcement method using the external cable will be outlined.

[0027] <<External cable reinforcement method>> 1(a) and 1(b), a pair of anchoring devices 10 are arranged at both ends of a beam 611 of a pier 61 of a road bridge 60 in the direction perpendicular to the bridge axis. A pair of outer cables 70 are also arranged on each of the two side surfaces of the beam 611 that are parallel to the direction perpendicular to the bridge axis. The outer cables 70 are tension members made by bundling multiple PC steel strands and covering them with a covering material, and are provided with anchoring devices 80 at both ends.

[0028] 2, the fixing device 80 includes an apartment 81 into which the end of the outer cable 70 is inserted, an anchor plate 82 through which the apartment 81 passes, and a nut 83 that screws onto the apartment 81. The fixing device 80 further includes the nut 83 and a protective cap 84 that protects the apartment 81 protruding from the nut 83.

[0029] The fixing devices 80 provided at both ends of this external cable 70 are each fixed to a pair of fixing devices 10, as shown in Figure 1(a). This is the same for each pair of external cables 70 arranged along both sides of the beam section 611, as shown in Figure 1(b). Since these external cables 70 are in a tensed state, the beam section 611 is tightened by the pair of fixing devices 10, and prestress is introduced in the direction perpendicular to the bridge axis. The fixing devices 10 used as described above in the external cable reinforcement method are configured as follows:

[0030] <<Fusing device>> As shown in Figures 1(b) and 3(b), the fixing device 10 includes a pair of cable fixing portions 20, a frame 30 connecting the cable fixing portions 20, an upper covering material 40, and a lower covering material 50.

[0031] ≪Top coating material and bottom coating material≫ 3(a) and 3(b), the upper covering material 40 is arranged so as to cover the upper part of the frame 30 (described later) and the upper part of the working space 23 of the cable fixing part 20, and is formed in a substantially U-shape in plan view. The lower covering material 50 has the same shape as the upper covering material 40, and is arranged so as to cover the lower part of the frame 30 and the lower part of the working space 23 of the cable fixing part 20.

[0032] <Frame> As shown in Figures 3(a) and 4, when viewed in a plane while covered with the upper covering material 40, the frame 30 is formed in an approximately U-shape that can surround the end of the beam portion 611, and is composed of an end wall 31 that follows the end of the beam portion 611, a pair of inner walls 32 that follow the side of the beam portion 611, and a frame reinforcing wall 33.

[0033] Each of the pair of inner walls 32 has a longitudinal portion of its surface facing the side of the beam 611, and the other longitudinal portion extending out from the beam 611 in a direction perpendicular to the bridge axis. An end wall 31 is connected to the longitudinal middle of each of these inner walls 32.

[0034] The surface of the end wall 31 faces the end of the beam 611, and a frame reinforcing wall 33 is connected to the middle of the back surface so as to be perpendicular to the end wall 31. The frame reinforcing wall 33 is arranged in parallel with other longitudinal portions of each of the pair of inner walls 32 that protrude from the beam 611. As shown in Figures 3(b) and 4, a cable anchoring part 20 is provided on the back surface of the inner wall 32 whose surface faces the side surface of the beam 611.

[0035] <Cable fixing part> As shown in Figure 3(b), the cable fixing section 20 comprises a fixing plate 21 connected perpendicularly to the back surface of the inner wall 32, a reinforcing section 22 that reinforces the fixing plate 21, and a working space 23 that also serves as a storage space for the fixing device 80 for the outer cable 70.

[0036] The anchoring plate 21 is a plate material to which the external cable 70 is fixed via the fixing tool 80, and as shown in Fig. 1(a), it is installed closer to the column part 612 side than the end of the beam part 611. As shown in Fig. 4, this anchoring plate 21 has a through hole 21a formed therein through which the condominium 81 of the fixing tool 80 provided on the external cable 70 passes, and an anchor plate 82 of the fixing tool 80 is installed on the surface. Therefore, a working space 23 for the fixing tool 80 is formed on the surface side of the anchoring plate 21, and a reinforcing part 22 is arranged on the back side.

[0037] The reinforcing portion 22 is a member that suppresses deformation of the fixing plate 21 that may occur when the tensioned outer cable 70 is fixed to the fixing plate 21 via the fixing device 80. Any structure may be used, but in this embodiment, as shown in Fig. 3(b), a case is taken as an example in which the fixing plate 21 includes a support wall 221, a pair of rib plates 222, and a blocking wall 223.

[0038] As shown in Figures 3(b) and 4, the support wall 221 is provided parallel to the inner wall 32 with the outer cable 70 sandwiched therebetween, and one end is connected to the back surface of the anchoring plate 21. As shown in Figures 2 and 3(b), the rib plates 222 are provided in pairs above and below between the inner wall 32 and the support wall 221 with the outer cable 70 sandwiched therebetween, and one end is connected to the back surface of the support wall 221 and the other end is connected to the blocking wall 223.

[0039] The blocking wall 223 is disposed parallel to the fixing plate 21 at a distance, and its four sides are connected to the pair of rib plates 222, the inner wall 32, and the support wall 221 so as to block the space surrounded by these. Similar to the fixing plate 21, the blocking wall 223 is formed with a through hole 223a through which the condominium 81 of the fixing device 80 provided on the outer cable 70 passes.

[0040] 2 and 3(b), the work space 23 is a space formed by the above-mentioned anchor plate 21, the inner wall 32, the upper covering material 40, and the lower covering material 50, and utilizes the range continuing from the anchor plate 21 into the frame 30. Therefore, when connecting the anchor plate 21 perpendicularly to the rear surface of the inner wall 32, if the position is adjusted so that it is installed closer to the column part 612 side than the end of the beam part 611, the work space 23 can be secured widely in the tension direction of the outer cable 70 (the direction in which prestress is introduced).

[0041] Such a working space 23 functions as a working space when tensioning the outer cable 70 and as a space for storing the fixing device 80 for the outer cable 70. A method for using the working space 23 will be explained in the method for installing the outer cable 70, which will be described later.

[0042] <<External cable installation method>> An example of a procedure for installing the external cable 70 using the fixing device 10 will be described below with reference to FIG.

[0043] ≪Preparation process≫ For example, as shown in Figures 3(b) and 4, the fixing device 10 is provided with a hanging metal fitting 101 at an appropriate position. Also, in order to temporarily fix the fixing device 10 to the beam portion 611 of the pier 61, a temporary fixing member 102 such as an angle member is provided.

[0044] <<Process for arranging the fixing device and external cable>> As shown in Figures 5(a) and (b), a pair of fixing devices 10 are hung down using hanging fittings 101, and placed at a predetermined height so as to surround the end of the beam portion 611 of the pier 61.

[0045] 2 and 5(b), the fixing device 10 and the end of the beam 611 are temporarily fixed by bolting using the temporary fixing member 102. After that, as shown in FIG. 5(c), the external cable 70 is arranged along the side surface of the beam 611 and is bridged over the paired fixing device 10 with the beam 611 in between.

[0046] 5(c) and 6, a fixing device 80 is attached to the end of the outer cable 70, and this fixing device 80 is positioned in the work space 23 of the cable fixing portion 20. Also, a traction device 90 is prepared in the work space 23. If necessary, a filler material 103 such as non-shrink mortar is filled between the frame 30 of the fixing device 10 and the beam portion 611 of the pier 61.

[0047] ≪Tension process≫ Thereafter, the outer cable 70 is tensioned using the traction device 90, and the tensioned outer cable 70 is fixed to the fixing plate 21 via the fixing tool 80.

[0048] The tensioning work of the outer cable 70 is carried out, for example, in the work space 23 as shown in Figure 6, by connecting a tension bar 91 to the apartment 81 of the outer cable 70 and passing this tension bar 91 through a center hole jack 93 fixed to a ram chair 92. After this, the tension bar 91 is pulled to tension the outer cable 70.

[0049] After tensioning the outer cable 70 by a predetermined amount, the nut 83 is tightened so that it abuts against the anchor plate 82 provided on the fixing plate 21. In this way, the outer cable 70 is fixed to the fixing plate 21 via the fixing device 80. As described above, the fixing plate 21 on which the anchor plate 82 is installed has the reinforcing portion 22 provided on its back surface, so that deformation does not occur.

[0050] As described above, the work of tensioning the outer cable 70 requires space to install the traction device 90, but the anchoring device 10 ensures a working space 23 that utilizes the continuous area from the anchoring plate 21 to the inside of the frame 30. Therefore, even if there are space constraints, such as the proximity of surrounding structures or construction limits, as long as the environment allows for the construction of the frame 30, the working space 23 can be ensured and tensioning work can be carried out efficiently.

[0051] <Protective cap attachment process> After the tensioning operation is completed, the traction device 90 is removed, and the protective cap 84 is attached as shown in FIG. 2, completing the operation.

[0052] As described above, by using the fixing device 10, the fixing tool 80 for the outer cable 70, including the protective cap 84, can be stored compactly in the work space 23 used for tensioning the outer cable 70, resulting in a structure that is considerate of the landscape.

[0053] Furthermore, even if the fixing device 10 is in an outdoor environment where it is directly exposed to wind and rain, the fixing device 80 stored in the working space 23 can be protected from the effects of wind and rain, and the intrusion of rainwater, which could cause deterioration, can be suppressed to a minimum, thereby improving durability.

[0054] Furthermore, the fixing device 80 for the outer cable 70 stored in the work space 23 can prevent snow from accumulating on the fixing device 80 in areas with heavy snowfall, etc. This reduces the risk of snowfall disasters, which had to be addressed when the fixing device 80 is located in an environment where third parties can enter below the fixing device 80.

[0055] The fixing device 10 and the method for installing the external cable 70 of the present invention are not limited to the above-described embodiment, and various modifications are possible within the scope of the present invention.

[0056] For example, in this embodiment, as shown in Fig. 3(b), the sides of the frame 30 and the work space 23 are open, but this is not limiting. As shown in Fig. 7, an outer plate 110 may be provided between the upper covering material 40 and the lower covering material 50 to cover the entire frame 30 and the work space 23. This allows the fixing device 80 to be protected more reliably.

[0057] Such an outer panel 110 may be installed in advance, and the portion covering the work space 23 may be made openable or closable, or the outer panel 110 may be manufactured as a separate member and installed on-site after the external cable 70 is installed. Also, the outer panel 110 may be configured to be installed so as to cover only either the frame 30 or the work space 23.

[0058] Furthermore, in this embodiment, as shown in Figures 3(b) and 4, the reinforcing portion 22 of the fixing plate 21 is formed in a substantially rectangular parallelepiped shape, but any shape may be used as long as it is able to reinforce the fixing plate 21. For example, as shown in Figure 8, the rib plate 222 may be formed in a trapezoid shape, and the reinforcing portion 22 may be formed in a box shape that is trapezoidal in plan view.

[0059] Furthermore, in this embodiment, the fixing device 10 is formed in a roughly U-shape in plan view, but this is not limited to this. Any shape in plan view is acceptable as long as it can be installed along and surrounding the end of the beam 611 in the direction perpendicular to the bridge axis. For example, in FIG. 9(a), the end of the beam 611 is semicircular in plan view. Therefore, the frame 30 of the fixing device 10 is formed in a roughly C-shape, and the cable fixing portions 20 are provided at both ends of the frame 30 so as to follow the side surfaces of the beam 611. Accordingly, the upper covering material 40 is also formed in a roughly C-shape in plan view. The same is true for the lower covering material 50.

[0060] Additionally, the fixing device 10 may have either an integral structure or a separable structure. For example, in FIG. 9( a), the fixing device 10 is formed so as to be split in half at the center of the frame 30. Also, the upper covering material 40 is illustrated as being formed by connecting a plurality of covering material bodies 41. If the fixing device 10 has such a separable structure, the fixing device 10 can be manufactured at a manufacturing factory, then loaded in a separated state onto a construction vehicle and transported to a construction site, where it can be assembled using any connection means, such as bolting or welding.

[0061] 9B, the fixing device 10 may be configured to have a large height so that it can fix two external cables 70 arranged in parallel in the height direction. Alternatively, the fixing device 10 itself may be stacked in two layers in the height direction so that it can fix two external cables 70 arranged in parallel in the height direction. The number of external cables arranged in parallel in the height direction may be two or more, and the fixing device 10 may be manufactured to a height that can accommodate that number, or the corresponding number of fixing devices 10 may be stacked.

[0062] Furthermore, the anchoring device 10 may be made of any material, such as steel or concrete. If it is made of concrete, after the external cable 70 is installed, the work space 23 may be filled with a filler material and the anchoring device 80 for the external cable 70 may be buried. This ensures that the anchoring device 80 is protected even in outdoor environments, thereby further improving durability.

[0063] 1(a), in this embodiment, a pair of fixing devices 10 are arranged on either side of the beam portion 611 of the pier 61, and both ends of the external cable 70 are fixed to the fixing devices 10. However, only one end of the external cable 70 may be fixed to the fixing device 10, and the other end may be fixed by another means.

[0064] 1(a), the outer cable 70 is installed so as to extend in one direction, but this is not limiting. A deflection device having a so-called deflector may be added to any position of the beam 611 to deflect the middle portion of the outer cable 70. [Explanation of symbols]

[0065] 10 Fixing device 101 Hanging hardware 102 Temporary fixing member 103 Filling material 110 Outer plate (covering member) 20 Cable fixing point 21 Fixing plate 21a Through hole 22 Reinforcement 221 Supporting wall 222 Rib Plate 223 Blocking Wall 223a Through hole 23 Work Space 30 frames 31 End wall 32 Inner wall 33 Frame reinforced wall 40 Top covering material 41 Covering material body 50 Undercoating material 60 Road Bridge 61 Pier (substructure) 611 Beam section 612 Column section 62 Floor slab 70 external cable 80 Fixture 81 Apartment 82 Anchor Plate 83 Nut 84 Protective Cap 90 Traction device 91 Tension bar 92 Ram Chair 93 Center hole jack

Claims

1. An anchorage device for an external cable that introduces prestress into a bridge substructure, a frame disposed to surround one end of the substructure in a prestress introduction direction; a pair of cable fixing portions provided at both ends of the frame; the cable fixing portion includes a fixing plate to which the outer cable is fixed, The fixing device is characterized in that the fixing plate is arranged within a range of a side surface of the lower structure along a prestress introduction direction.

2. 2. The fixing device according to claim 1, The fixing device is characterized in that the frame is formed so as to be separable into a plurality of parts.

3. 2. The fixing device according to claim 1, a fixing device, characterized in that a working space for tensioning the external cable is provided in an area continuing from the fixing plate into the frame;

4. 2. The fixing device according to claim 1, A fixing device characterized in that a plurality of combinations of the frame and the pair of cable fixing portions are provided consecutively in the height direction of the lower structure.

5. A method for installing an external cable using the fixing device according to claim 1, a step of arranging the fixing device so that the frame surrounds one end of the lower structure in a prestress introduction direction; a step of placing the pair of outer cables along a pair of side surfaces of the substructure that are parallel to a prestressing direction; a step of tensioning the outer cable by utilizing a working space provided in an area continuous from the fixing plate to the inside of the frame, and fixing one end of the outer cable to the fixing plate; An external cable installation method comprising:

6. The method for installing an external cable according to claim 5, The fixing devices are arranged in pairs at both ends of the lower structure in a prestress introduction direction, a pair of said external cables, each of said pair of external cables being fixed at both ends to said fixing plates provided in each of said pair of fixing devices;

7. The method for installing an external cable according to claim 5, A method for erecting an external cable, characterized in that the substructure is the beam portion of a bridge pier.

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