Cable protection

Abstract

To provide a cable protector which can prevent bridge fall prevention cables from breaking at cross girders or diaphragm through holes when large force is applied to the bridge girders in a direction different from an axial direction of the bridge fall prevention cables, and can also be used on bridge-fall prevention cables with higher yield loading than before.SOLUTION: In order to prevent bridge girders from falling from a supporting framework that supports them, a cable protector 1 that prevents breakage of bridge falling prevention cables (PC cables) 102 that connect adjacent bridge girders, or bridge girders and bridge abutments or bridge piers consists of deflectors 2 made of engineering plastic (MC nylon) attached to an outer periphery of the bridge fall prevention cables 102, fixing plates 3 interposed between an inner peripheral surface of a through hole 106 and the deflectors 2 and made of metal (steel) having higher strength than the deflectors 2, and at least one pair of positioning members 5 that are fixed to the fixing plates 3 and can be locked to peripheral edges on both sides of the through hole 106.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a cable protector for preventing breakage of a falling bridge prevention cable (PC cable) used in a PC cable type falling bridge prevention device installed to prevent a bridge girder from falling from a bridge abutment or pier during a disaster such as an earthquake.

Background Art

[0002] During a disaster such as an earthquake, when a large shaking or impact acts on a bridge, there is a risk that the bridge girder installed on the pier or bridge abutment may fall. For this reason, falling bridge prevention devices that connect adjacent bridge girders Allies or connect a bridge girder to a bridge abutment or pier are provided (see, for example, Patent Documents 1 and 2).

[0003] FIGS. 11 and 12 show an example, in which bridge girders 100 Allies placed adjacent to each other on a pier (not shown) are connected by a falling bridge prevention device 101 using a falling bridge prevention cable (PC cable) 102. A steel fixing tool 103 is fixed to the side wall of the bridge girder 100, and a flat fixing portion 103a provided on the fixing tool 103 and a buffer 104a disposed on the surface of this fixing portion are inserted through a mansion portion 102a fixed to the end of the PC cable 102. A washer 104b and a nut 104c that constitute a stopper are attached to the end of the mansion portion 102a that has passed through these fixing portion 103a and buffer 104a. Then, a coiled spring 104d that surrounds the mansion portion 102a is disposed between the washer 104b and the buffer 104a, and the nut 104c is tightened to fix the PC cable 102 to the fixing tool 103 in a non-loose state.

[0004] In this example, two fixing tools 103 are arranged side by side on the inner surfaces of both side walls of the bridge girder 100 with different distances in the bridge axis direction from the end of the bridge girder 100. On each side wall, the fixing tool closer to the end of the bridge girder 100 AlliesThese are connected by a PC cable 102-1 inserted through a through hole 106 formed near the side wall of the transverse girder 100a located at the end of the bridge girder 100, and also by a fixing device far from the end of the bridge girder 100. Allies These are connected by a PC cable 102-2 inserted through a through hole 106 formed near the center of the transverse beam 100a. Furthermore, to reinforce the periphery of the through-hole 106 through which the PC cable 102 is inserted, an annular doubling plate 107 is joined to at least one side of the crossbeam 100a by welding or the like. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2014-114549 [Patent Document 2] Japanese Patent Application Publication No. 9-53205 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, in the event of an earthquake or other event, if a large force acts in a direction different from the axial direction of the PC cable 102, the PC cable 102 of the bridge collapse prevention device will be strongly pressed against the inner surface of the through-hole 106 in the transverse girder 100a (see Figure 13). Ideally, this PC cable 102 would minimize the horizontal movement of the bridge girder 100 and prevent the bridge girder 100 from falling off the bridge piers or abutments. However, the through-hole 106 formed in the transverse girder 100a is only about 18 mm thick (the thickness of the transverse girder 110a (approximately 9 mm) plus the thickness of the doubling plate 107 provided on one side of the transverse girder (approximately 9 mm)). Therefore, when the PC cable 102 is pressed against the inner surface of the through-hole 106, a large localized shear stress acts on the PC cable 102, raising concerns that the PC cable 102 may break.

[0007] Such inconveniences can also occur when the PC cable 102 is installed by inserting it through a through hole formed in a diaphragm (not shown) to avoid interference with the diaphragm. Therefore, the applicant has previously proposed various cable protection devices to prevent breakage of PC cables (Japanese Patent Publication No. 2019-49136). By using the proposed cable protection devices, it is expected that in the event of an earthquake or other seismic activity, the PC cables will not break, the horizontal movement of the bridge girders will be minimized, and the bridge girders will not detach from the bridge piers or abutments.

[0008] However, in order to increase the applicability of cable protection devices to approximately 80% of existing PC cables, there is a need to develop cable protection devices that can also suppress the breakage of PC cables with higher yield strength (for example, PC cables with a yield strength approximately 1.32 times that of F100: F130).

[0009] This invention has been made in view of the above circumstances, and its main objective is to provide a cable protection device that can prevent the risk of PC cables rupturing at the through-holes of the transverse girders and diaphragms when a large force acts on the bridge girder in a direction different from the axial direction of the PC cable during an earthquake or the like, and that can also handle PC cables with higher yield loads than conventional devices. [Means for solving the problem]

[0010] To achieve the above objectives, the cable protection device according to the present invention prevents the bridge girder from falling from the support structure that supports the bridge girder, and the adjacent bridge girder Allies Alternatively, the bridge girder and the abutment or pier are connected via a bridge collapse prevention cable, and this bridge collapse prevention cable is inserted through a through hole provided in at least one of the cross girders and diaphragms of the bridge girder, and then the adjacent bridge girder Allies A cable protection device used in a bridge collapse prevention device that is stretched between the bridge girder and the bridge abutment or bridge pier, A deflection device made of engineering plastic is attached to the outer circumference of the aforementioned bridge collapse prevention cable, A fixing plate is interposed between the inner circumferential surface of the through hole and the deflection device, fixed to the deflection device, and made of a metal with higher strength than the deflection device. A positioning member fixed to the fixing plate and capable of engaging with the peripheral edges on both sides of the through hole, It is characterized by being composed of [this]. Here, "lockable to both sides of the through-hole" includes the case where, if a doubling plate is placed around the periphery of the through-hole, it is lockable to the inner periphery of the doubling plate. Furthermore, the deflection device may be made of, for example, MC nylon, and the fixing plate and positioning member may be made of, for example, steel.

[0011] Therefore, in the through-holes of the bridge girder's transverse girders and diaphragms through which the bridge collapse prevention cable passes, a deflection device is provided on the outer circumference of the bridge collapse prevention cable, and a fixing plate made of a metal stronger than the deflection device is interposed between the inner surface of the through-hole and the deflection device. At least one pair of positioning members that can be locked to the periphery on both sides of the through-hole are fixed to the fixing plate. As a result, even if a large force acts in a direction different from the axial direction of the bridge collapse prevention cable, the displacement of the cable protector from the through-hole is restricted by the positioning members, ensuring that the cable protector is securely positioned between the bridge collapse prevention cable and the inner surface of the through-hole. Consequently, when a large force acts in a direction different from the axial direction of the bridge collapse prevention cable, the bridge collapse prevention cable is not directly pressed against the inner surface of the through-hole in the transverse girders or diaphragms, but is first pressed against the deflection device, and then pressed against the inner surface of the through-hole via the deflection device and the fixing plate made of a metal stronger than the deflection device. Therefore, the load received from the inner surface of the through-hole is first received by the fixing plate, which is made of a metal with higher strength than the deflection device. This allows the plate to withstand the load received from the inner surface of the through-hole, and prevents the deflection device from breaking due to a large localized force from the inner surface of the through-hole. Thus, damage to the cable protector is suppressed, eliminating or reducing the shear stress acting locally on the PC cable, and preventing the PC cable from breaking.

[0012] A more specific example of the cable protection device configuration is as follows: the deflection device is composed of three divided deflection device members arranged around the bridge collapse prevention cable in the circumferential direction; the fixing plate is composed of three divided fixing plate members arranged between the inner circumferential surface of the through hole and the deflection device in the circumferential direction; and the fixing plate is fixed to the deflection device (for example, by bolting) with the divided portions of adjacent deflection device divided members and adjacent fixing plate divided members offset in the circumferential direction. This configuration makes it easy to install cable protection devices, and also prevents the strength of the assembled cable protection devices from being partially weakened.

[0013] Furthermore, it is preferable that the inner surface of the deflection device be formed as a curved surface in which the radius of curvature gradually decreases toward the axial center. With such a configuration, when a large force acts in a direction different from the axial direction of the bridge collapse prevention cable, it is possible to increase the contact area between the bridge collapse prevention cable and the deflection device, making it easier to disperse the force acting on the bridge collapse prevention cable.

[0014] Here, at least one pair of positioning members fixed to the fixing plate may be integrally formed on the outer circumferential surface of the fixing plate (the dividing member for the fixing plate). In this configuration, the mounting position of the positioning member is predetermined, and the fixed state cannot be finely adjusted, making it suitable for a type where the bridge collapse prevention cable passes through perpendicularly to the through-hole.

[0015] Furthermore, at least one pair of positioning members are used to fix the fixing plate to the deflection device. to The fixing plate (divided member for fixing plate) may be fixed to the outer surface of the fixing plate using fasteners (for example, bolts). In this configuration, positioning members can be added later, allowing for fine adjustments to the size and orientation of the positioning members, making it suitable for locations where bridge collapse prevention cables pass through holes at an angle.

[0016] In addition, deflectorThe axial length of the (said deflection tool's dividing member) may be made larger than the axial length of the fixing plate (fixing plate's dividing member). With such a configuration, it becomes possible to stably attach the fixing plate to the deflection tool, and also possible to increase the contact area between the deflection tool and the bridge-fall prevention cable.

[0017] In the most preferred embodiment, the said deflection tool is composed of three deflection tool dividing members formed in an arc shape within a range of a central angle of about 120 degrees, the said fixing plate is composed of three fixing plate dividing members formed in an arc shape within a range of a central angle of about 120 degrees, and the said deflection tool dividing member and the said fixing plate dividing member may be fixed with a phase shift of about 60 degrees in the circumferential direction.

Advantages of the Invention

[0018] As described above, the cable protector of the bridge-fall prevention device according to the present invention includes a deflection tool made of engineering plastic attached to the outer periphery of the bridge-fall prevention cable, a fixing plate made of a metal having higher strength than the deflection tool and interposed between the inner peripheral surface of the through-hole and the deflection tool, and at least one pair of positioning members fixed to the fixing plate and capable of being locked to the peripheral edges on both sides of the through-hole. Therefore, even if a large force acts on the bridge girder in a direction different from the axial direction of the PC cable, the cable protector will not come off from the through-hole, and also, the PC cable is not directly pressed against the inner peripheral surface of the through-hole, but is pressed against the inner peripheral surface of the through-hole via the deflection tool and the fixing plate. Therefore, the force acting from the inner peripheral surface of the through-hole is first received by the fixing plate with high strength, so it can withstand the load received from the inner peripheral surface of the through-hole. Further, since the load is applied to the deflection tool through the entire fixing plate, it is possible to avoid a large force acting locally on the deflection tool, and it becomes possible to suppress the breakage of the deflection tool. Also, since the bridge-fall prevention cable receives the load from the inner peripheral surface of the through-hole via the fixing plate and the deflection tool made of engineering plastic, the pressing force from the deflection tool is applied to the PC cable in a dispersed or reduced state. Even when a load corresponding to the yield load of the PC cable is applied from the inner peripheral surface of the through-hole, shear stress does not act locally on the PC cable, and it becomes possible to prevent the breakage of the PC cable 102.

Brief Description of the Drawings

[0019] [Figure 1] FIG. 1 is a conceptual diagram showing a state where a cable protector according to the present invention is provided in a through hole in a configuration in which a PC cable is inserted through a through hole provided in a cross girder and tensioned to connect adjacent bridge girders. [Figure 2] FIG. 2 is a diagram showing a first configuration example of the cable protector according to the present invention, and is a perspective view showing a state where the cable protector is provided in the through hole. [Figure 3] FIG. 3 is a diagram for explaining the mounting state of the cable protector shown in FIG. 2, (a) is a cross-sectional view taken along line A-A of (b), and (b) is a cross-sectional view taken along line B-B of (a). [Figure 4] FIG. 4 is a diagram showing a split member for a deflector constituting the deflector, (a) is a cross-sectional view taken along line C-C of (b), (b) is a cross-sectional view taken along line D-D of (a), and (c) is a view of (a) seen from above. [Figure 5] FIG. 5 is a diagram showing a split member for a fixing plate constituting the fixing plate, (a) is a cross-sectional view taken along line E-E of (b), and (b) is a view of (a) seen from the right. [Figure 6] FIG. 6 is a diagram showing a second configuration example of the cable protector according to the present invention, and is a perspective view showing a state where the cable protector is provided in the through hole. [Figure 7] FIG. 7 is a diagram for explaining the mounting state of the cable protector shown in FIG. 6, (a) is a cross-sectional view taken along line A-A of (b), and (b) is a cross-sectional view taken along line B-B of (a). [Figure 8] FIG. 8 is a diagram showing a split member for a deflector constituting the deflector, (a) is a cross-sectional view taken along line C-C of (b) and viewed axially, (b) is a cross-sectional view taken along line D-D of (a), and (c) is a view of (a) seen from above. [Figure 9] FIG. 9 is a diagram showing a split member for a fixing plate constituting the fixing plate, (a) is a cross-sectional view taken along line E-E of (b), and (b) is a view of (a) seen from the right. [Figure 10] Figure 10 is a perspective view showing the positioning member to be attached to the fixing plate in Figure 9. [Figure 11] Figure 11 shows a conventional bridge girder collapse prevention device, where (a) is a view of the bridge girder collapse prevention device installed on the bridge girder from the bridge axis direction, and (b) is an enlarged perspective view showing the part where the end of the PC cable is fixed to the anchoring device of the bridge collapse prevention device. [Figure 12] Figure 12(a) is a conceptual diagram showing a conventional example in which a PC cable connecting adjacent bridge girders is stretched by inserting it through holes provided in the transverse girders, and Figure 12(b) is an enlarged side view showing the part in which the end of the PC cable is fixed to the anchoring device of the bridge collapse prevention device in Figure 12(a). [Figure 13] Figure 13 illustrates the state in which the bridge girder is displaced due to a force acting on it in a direction different from the axial direction of the PC cable, starting from the state shown in Figure 12(a). [Modes for carrying out the invention]

[0020] The cable breakage prevention structure for the bridge collapse prevention device according to the present invention will be described below with reference to the attached drawings. In Figure 1, adjacent bridge girders Allies An example of a bridge collapse prevention device 101 is shown in which a PC cable 102 connecting the bridge girders is passed through a through hole 106 provided in the transverse girder 100a of the bridge girder 100 and then stretched between the bridge girders. This bridge collapse prevention device 101 itself has the same configuration as conventional devices, so its explanation will be omitted, but in addition to this existing bridge collapse prevention device 101, a cable protector 1, which will be described later, is attached between the PC cable 102 and the inner surface of the through hole 106 in each through hole 106.

[0021] In this example, as before, two anchoring devices 103 are installed side by side on the inner surface of each side wall of the bridge girder 100, at different distances from the end in the bridge axis direction of the bridge girder 100, and on each side wall, the anchoring device closer to the end of the bridge girder 100 AlliesThese are connected by a PC cable 102-1 inserted through a through hole 106 formed near the side wall of the transverse girder 100a, which is provided at the end of the bridge girder 100, and also by a fixing device far from the end of the bridge girder 100. Allies These are connected by a PC cable 102-2 inserted through a through hole 106 formed near the center of the transverse beam 100a.

[0022] Furthermore, to reinforce the periphery of the through-hole 106 through which the PC cable 102 is inserted, an annular doubling plate 107 may be joined to one side of the transverse beam 100a by welding or other means. In this case, the through-hole 106 of the transverse beam 100a shall be considered to include the through-hole 107 of the doubling plate 107. Therefore, in cases where a doubling plate is provided, the thickness of the through-hole (the width of the inner surface of the through-hole) is the sum of the thickness of the crossbeam and the thickness of the doubling plate. [Examples]

[0023] Figures 2 and 3 show a first example configuration of the cable protection device 1. This cable protection device 1 comprises a deflection device 2 attached to the outer circumference of the PC cable 102, a fixing plate 3 interposed between the entire inner circumference of the through hole 2 and the deflection device 2, and a positioning member 5 fixed to the fixing plate.

[0024] The deflection device 2 is formed in a cylindrical shape with a cable insertion hole 2a formed in the center. It is composed of multiple (three in this example) deflection device division members 21, 22, and 23 arranged sequentially adjacent to each other in the circumferential direction, divided around the PC cable 102 so as to enclose the PC cable 102. Each of the deflection device division members 21, 22, and 23 is formed to be substantially the same shape, curves along the outer surface of the PC cable 102, and forms a circular arc with a central angle of approximately 120 degrees, as shown in Figure 4. Such a deflection device 2 (deflection device division members 21, 22, and 23) is formed from engineering plastics such as MC nylon or FRP, which have higher mechanical strength than general-purpose plastics, and it is particularly preferable that they be formed from MC nylon.

[0025] Furthermore, the inner surfaces of the deflection device 2 (divided members 21, 22, 23 for the deflection device) are formed as curved surfaces in which the radius of curvature gradually decreases toward the axial center. Therefore, the thickness of the peripheral wall of the deflection device is thickest in the center and gradually thins toward both ends. Therefore, when the three deflection device division members 21, 22, and 23 are combined in a ring shape, the cable insertion hole 2a is formed such that its inner diameter is smallest in the middle section and gradually increases towards both ends. The inner diameter of the middle section of this deflection device 2 is formed to be approximately equal to or slightly larger than the outer diameter of the PC cable 102. Furthermore, the outer surface of the deflection device 2 is formed to have the same diameter (outer diameter) from one end to the other in the axial direction without being curved in the axial direction.

[0026] Therefore, when the PC cable 102 is curved along the inner surface of the cable insertion hole 2a of the deflection device 2, the contact area between the PC cable 102 and the deflection device 2 increases, preventing loads acting from the side on the PC cable from acting locally. Furthermore, each of the deflection device segment members 21, 22, and 23 has a screw hole 25 that penetrates from the outer circumferential surface to the inner circumferential surface, located at approximately 30 degrees from each circumferential edge, and a total of four such holes are formed between each axial end and the intermediate portion. Therefore, between the axial intermediate portion and each end of the deflection device segment members 21, 22, and 23, two screw holes 25 are formed at approximately 60-degree intervals.

[0027] In contrast, the fixing plate 3 is formed in a cylindrical shape with a deflection device insertion hole 3a formed in the center. It is constructed by sequentially arranging multiple (three in this example) fixing plate dividing members 31, 32, 33 adjacent to each other in the circumferential direction, with the deflection device 2 enclosed between the periphery of the deflection device 2 and the inner circumferential surface of the through hole 106. Each fixing plate dividing member 31, 32, 33 is formed in substantially the same shape, curves along the outer circumferential surface of the deflection device 2, and forms a circular arc with a central angle of approximately 120 degrees, as shown in Figure 5. The entire fixing plate 3 (fixing plate dividing members 31, 32, 33) is made of steel (for example, SS400). The outer diameter of the fixing plate 3 is formed to be approximately equal to or slightly smaller than the inner diameter of the through hole 106, and the inner diameter of the fixing plate 3 is formed to be approximately equal to or slightly larger than the outer diameter of the deflection device 2.

[0028] Furthermore, each of the fixing plate dividing members 31, 32, and 33 has a bolt insertion hole 35 that penetrates from the outer circumferential surface to the inner circumferential surface, located at approximately 30 degrees from each circumferential edge, and a total of four such holes are formed between each axial end and the intermediate portion. Therefore, between the axial intermediate portion and each end of the fixing plate dividing members 31, 32, and 33, two bolt insertion holes 35 are formed at approximately 60-degree intervals.

[0029] Furthermore, at least one pair of positioning members 5 are integrally formed on the outer circumferential surface of the axial central portion of each fixing plate dividing member 31, 32, 33. These positioning members are positioned opposite each other at a distance greater than the thickness of the transverse beam (or the thickness including the doubling plate if one is present) in which the through-hole 106 is formed, and the transverse beam (or the doubling plate if one is present) is placed between them to engage with the inner circumferential edges on both sides of the through-hole 106.

[0030] The size and shape of the positioning member 5 are not limited as long as they have the function of preventing the fixing plate 3, which is attached to the inside of the through hole 106, from shifting significantly in the axial direction. Furthermore, multiple pairs of positioning members 5 may be provided at equal intervals in the circumferential direction of the fixing plate 3 (in this example, one pair is provided for each fixing plate dividing member 31, 32, and 33 (a total of three pairs)). The spacing between the pair of positioning members 5 may be approximately equal to the thickness of the crossbeam (and the thickness including the doubling plate if one is present), as described above, or a predetermined gap may be provided between the periphery of the through-hole 106 and the positioning member 5. Furthermore, the thickness of the positioning member 5 may be the same as the thickness of the fixing plate 3 (fixing plate dividing members 31, 32, 33), or it may be thinner than the fixing plate 3 (fixing plate dividing members 31, 32, 33).

[0031] The deflection device 2 and the fixing plate 3 are fixed to each other by aligning the positions of the screw holes 25 of the deflection device 2 (deflection device split members 21, 22, 23) and the bolt insertion holes 35 of the fixing plate 3 (fixing plate split members 31, 32, 33) by shifting the division portions of adjacent deflection device split members 21, 22, 23 and adjacent fixing plate split members 31, 32, 33 by approximately 60 degrees in the circumferential direction, and then passing the fixing bolts 4 through the bolt insertion holes 35 from the radially outward direction and screwing them into the screw holes 25.

[0032] In the above configuration, to attach the cable protector 1 between the inner surface of the through-hole 106 and the PC cable 102, the fixing plate dividing members 31, 32, and 33 are sequentially inserted into the gap between the inner surface of the through-hole 106 and the existing PC cable 102 inserted through the through-hole 106, the pair of positioning members 5 are aligned with the position of the through-hole 106, and in that state, the fixing plate dividing members 31, 32, and 33 are moved radially outward to position the inner edge of the through-hole 106 between the pair of positioning members 5 (the inner edge of the through-hole 106 is sandwiched between the pair of positioning members 5), and in that state Maintaining the position, insert the deflection device division members 21, 22, and 23 into the gap between the inner circumferential surface of the fixing plate 3 and the PC cable 102. Align the centers of the deflection device division members 21, 22, and 23 with the axial center of the fixing plate 3 and move them in the circumferential direction to align the bolt insertion holes 35 of the fixing plate division members 31, 32, and 33 with the screw holes 25 of the deflection device division members 21, 22, and 23. In this state, insert the fixing bolts 4 from the outside into the bolt insertion holes 35 of the fixing plate 3 (fixing plate division members 31, 32, and 33) and screw them into the screw holes 5 of the deflection device 2 (deflection device division members 21, 22, and 23). As a result, the cable protector 1 is positioned between the entire inner circumference of the through-hole 106 and the PC cable 102, and the positioning member 5 is locked to the inner edge of the through-hole 106, ensuring that it is installed without shifting away from the through-hole 106.

[0033] Therefore, when such a cable protector 1 is attached to the through-hole 106, the curved surface of the deflection device 2, which is made of engineering plastic, is curved so that the inner diameter of the middle part in the axial direction is smallest, and contacts the outer surface of the PC cable 102. In addition, a metal fixing plate 3, which is stronger than the deflection device 2, is fixed between the deflection device 2 and the inner surface of the through-hole 106. As a result, even if a large force acts on the bridge girder 100 in a direction different from the axial direction of the PC cable 102 (for example, in the horizontal direction perpendicular to the bridge axis), the PC cable 102 is not pressed directly against the inner surface of the through-hole 106 of the transverse girder 100a, but flexes along the inner surface of the deflection device 2. This increases the contact area with the deflection device 2, and the cable is pressed against the inner surface of the through-hole 106 via the deflection device 2 and the fixing plate 3.

[0034] Therefore, the force acting from the inner surface of the through-hole 106 of the transverse beam is first received by the strong fixing plate 3, which can withstand the load received from the inner surface of the through-hole. As the load is applied to the deflection device 2 through the entire inner surface of the fixing plate 3, the deflection device is prevented from receiving a large localized force from the inner surface of the through-hole, and thus the fracture of the deflection device can be suppressed. In addition, the contact area between the inner surface of the deflection device 2 and the PC cable is increased, so the pressing force from the deflection device is applied to the PC cable in a distributed state, preventing localized concentration of shear stress on the PC cable 102, and thus preventing the PC cable 102 from fracturing. [Examples]

[0035] The above configuration was an example of a cable protection device suitable for a right-angle penetration type where the PC cable 102 passes perpendicularly through the through-hole 106. However, the PC cable 102 often passes diagonally through the through-hole 106, and in such cases, the above-described protection device may not be usable as is. Figures 6 and 7 show examples of cable protection devices 1 suitable for diagonal penetration types.

[0036] This cable protection device 1 also comprises a deflection device 2 attached to the outer circumference of the PC cable 102, a fixing plate 3 interposed between the entire inner circumference of the through hole 2 and the deflection device 2, and a positioning member 5 fixed to the fixing plate 3. The deflection device 2, which is attached to the outer surface of the cable, has a thickness and length that is adjusted according to the diameter of the through hole 106, but its basic shape is the same as that of the deflection device 2 of the orthogonal type cable protector, and is composed of three divided members 21, 22, and 23 for the deflection device shown in Figure 8, so the same connections are used in the same places and the explanation is omitted.

[0037] The fixing plate 3, which is attached to the outer circumferential surface of the deflection device 2 and positioned between it and the inner circumferential surface of the through hole 106, is formed in a cylindrical shape with a deflection device insertion hole 3a formed in the center. It is constructed by sequentially arranging multiple (three in this example) fixing plate dividing members 31, 32, and 33 adjacent to each other in the circumferential direction, with the fixing plate divided between the periphery of the deflection device and the inner circumferential edge of the through hole so as to enclose the deflection device 2. Each of the fixing plate division members 31, 32, and 33 is substantially the same shape and, as shown in Figure 9, curves along the outer surface of the deflection device 2, forming a circular arc with a central angle of approximately 120 degrees. The entire fixing plate 3 (fixing plate division members 31, 32, and 33) is made of steel (for example, SS400).

[0038] Furthermore, the fixing plate 3 does not have a positioning member integrally formed with it. Instead, a positioning member 5, which is made of a separate component, is fixed to the outer surface of the fixing plate 3 by fixing bolts 4 used when fixing the fixing plate 3 (fixing plate division members 31, 32, 33) to the deflection device 2 (deflection device division members 21, 22, 23). The positioning member 5 used here is formed from an L-shaped steel material, as shown in Figure 10. A bolt insertion hole 6 is formed in the fixing piece 5a that is attached to the outer surface of the fixing plate 3 (fixing plate dividing members 31, 32, 33). The upright piece 5b that is attached to the outer surface of the fixing plate 3 (fixing plate dividing members 31, 32, 33) is oriented toward the crossbeam and is approximately parallel to the crossbeam. The fixing bolt 4 is inserted through the bolt insertion hole 6 of the fixing piece 5a and the bolt insertion hole 35 of the fixing plate 3 (fixing plate dividing members 31, 32, 33), and then screwed into the screw hole 25 of the deflection device 2 (deflection device dividing members 21, 22, 23) to fix it to the outer surface of the fixing plate 3 (fixing plate dividing members 31, 32, 33).

[0039] These positioning members 5 are provided in correspondence with each screw hole 25 of the deflection device 2, and two pairs are provided for each fixing plate segment member 31, 32, 33 (a total of six pairs for the entire fixing plate). Therefore, in the oblique through-type, the positioning members 5 are fixed using the fixing bolts 4 that fix the fixing plate 3 to the deflection device 2, so the distance between the positioning members 5 facing each other in the axial direction is large. However, the upright pieces 5b of the pair of positioning members 5 provided on both sides of the through-hole 106 can be locked to the periphery of the through-hole 106 of the cross beam 100a, so that the cable protector 1 does not come out of the through-hole 106.

[0040] Therefore, since the cable protector 1 is fixed without coming off the through-hole 106, even in this configuration, the curved surface of the deflection device 2, which is made of engineering plastic, is curved so that the inner diameter of the middle part in the axial direction is smallest, and contacts the outer surface of the PC cable 102. In addition, a metal fixing plate 3, which is stronger than the deflection device 2, is fixed between the deflection device 2 and the inner surface of the through-hole 106. As a result, even if a large force acts on the bridge girder 100 in a direction different from the axial direction of the PC cable 102 (for example, the horizontal direction perpendicular to the bridge axis), the PC cable 102 is not pressed directly against the inner surface of the through-hole 106 of the transverse girder 100a, but flexes along the inner surface of the deflection device 2. This increases the contact area with the deflection device 2, and the cable is pressed against the inner surface of the through-hole 106 via the deflection device 2 and the fixing plate 3. Therefore, the force acting from the inner surface of the through-hole 106 of the transverse beam is first received by the strong fixing plate 3, which can withstand the load received from the inner surface of the through-hole. As the load is applied to the deflection device 2 through the entire inner surface of the fixing plate 3, the deflection device is prevented from receiving a large localized force from the inner surface of the through-hole, and thus the fracture of the deflection device can be suppressed. In addition, the contact area between the inner surface of the deflection device 2 and the PC cable is increased, so the pressing force from the deflection device is applied to the PC cable in a distributed state, preventing localized concentration of shear stress on the PC cable 102, and thus preventing the PC cable 102 from fracturing.

[0041] In the above example, we described an example in which adjacent bridge girders 100 are connected by a bridge collapse prevention device 101. However, even when connecting bridge girders 100 to abutments or piers (not shown) with a bridge collapse prevention device, a similar configuration can be applied as long as the PC cable 102 is inserted through a through hole 106 formed in the transverse girder 100a of the bridge girder 100. Furthermore, a similar configuration can be adopted for bridge collapse prevention devices 101 with different connection structures for the PC cable 102.

[0042] Furthermore, although the above example shows a cable protection device 1 installed in a through-hole 106 provided in the crossbeam 100a, even in cases where the PC cable 102 is inserted through a through-hole provided in a diaphragm (not shown) to avoid interference with the diaphragm, a similar cable protection device 1 may be attached to the through-hole in the diaphragm to prevent the PC cable 102 from breaking. [Explanation of symbols]

[0043] 1. Cable protection equipment 2 Deflector 3 Fixed plate 5 Positioning member 21,22,23 Split member for deflector 31, 32, 33 Divided members for fixing plates 102 Bridge Collapse Prevention Cable (PC Cable) 106 Through hole

Claims

1. A cable protection device used in a bridge collapse prevention device, which is used to prevent a bridge girder from falling from the support structure that supports the bridge girder, by connecting adjacent bridge girders to each other, or to a bridge girder and a bridge abutment or pier via a bridge collapse prevention cable, and stretching this bridge collapse prevention cable between adjacent bridge girders, or between a bridge girder and a bridge abutment or pier after inserting it through a through hole provided in at least one of the cross girders and diaphragms of the bridge girder, A deflection device made of engineering plastic is attached to the outer circumference of the aforementioned bridge collapse prevention cable, A fixing plate is interposed between the inner circumferential surface of the through hole and the deflection device, fixed to the deflection device, and made of a metal with higher strength than the deflection device. A positioning member fixed to the fixing plate and capable of engaging with the peripheral edges on both sides of the through hole, A cable protection device characterized by having the following features.

2. The deflection device is composed of three divided members for the deflection device, which are arranged around the bridge collapse prevention cable in the circumferential direction. The fixing plate is composed of fixing plate segment members arranged in three circumferential sections between the inner circumferential surface of the through hole and the deflection device. The cable protection device according to claim 1, characterized in that the fixing plate and the deflection device are fixed with the dividing portions of adjacent deflection device dividing members and the dividing portions of adjacent fixing plate dividing members offset in the circumferential direction.

3. The cable protection device according to claim 1 or 2, characterized in that the inner surface of the deflection device is formed as a curved surface in which the radius of curvature gradually decreases toward the axial center.

4. The cable protection device according to any one of claims 1 to 3, characterized in that the pair of positioning members are integrally formed on the outer circumferential surface of the fixing plate.

5. The cable protection device according to any one of claims 1 to 3, characterized in that the pair of positioning members are fixed to the outer circumferential surface of the fixing plate by a fixing device used to fix the fixing plate to the deflection device.

6. The cable protection device according to any one of claims 1 to 5, characterized in that the axial length of the deflection device is greater than the axial length of the fixing plate.

7. The cable protection device according to any one of claims 1 to 6, characterized in that the deflection device is composed of three deflection device division members formed in an arc shape within a central angle range of approximately 120 degrees, the fixing plate is composed of three fixing plate division members formed in an arc shape within a central angle range of approximately 120 degrees, and the deflection device division members and the fixing plate division members are out of phase by approximately 60 degrees in the circumferential direction.

8. The cable protection device according to any one of claims 1 to 7, characterized in that the deflection device is made of MC nylon, and the fixing plate and the positioning member are made of steel.

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