JP2011190616A - Device and method for releasing tensioning force of tendon - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily release a tensioning force, introduced into a tensioning material, by a simple device. <P>SOLUTION: In a section in which a steel strand 6 serving as the tendon is disposed outside a concrete member, the steel strand 6 is preinserted through the through-holes of two steel blocks 21 and 31 disposed while facing each other and ring-shaped members 26 and 36 of an anchoring implement. The tensioning force is introduced into the steel strand; and both ends of the steel strand are anchored to a bridge girder. Before the release of the tensioning force of the steel strand, wedges 27 and 37 are inserted between the ring-shaped members and the steel strand; after that, a center hole jack 50 for a prestressing steel bar makes the tensioning force introduced into the prestressing steel bar 40 for coupling two steel blocks together; and the tensioning force of the tendon between the steel blocks is released. The steel strand is cut off between the steel blocks. After the steel strand is cut off, an anchoring nut 41a screwed to the prestressing steel bar is rotated to be loosened, and the center hole jack is slowly decompressed to release the tensioning force of the divided tendon. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a tension release device and a tension release method that release tension from a tension member in a state where the tension is introduced.

  A prestressed concrete structure arranges a tendon in or along a concrete member. And, prestress is introduced into the concrete by introducing a tension force to the tendon and fixing the end to the concrete member. Some such tension materials introduce tension during construction of a concrete structure and release the tension when the structure is completed. For example, in the overhang construction method in which a prestressed concrete bridge with a ramen structure (hereinafter referred to as a “PC bridge”) is built from the upper part of the bridge pier to the both sides in order for each construction block, it is tensioned when completed as a temporary cable on the upper part of the bridge girder near the pier. A tendon that releases force may be placed. In other words, because the structural system at the time of completion is different from the structural system at the time of erection, the bending moment acting on the bridge girder near the pier is greatly different between completion and erection, and excessive prestress is applied at the time of completion. It is done to release. In addition, when a prestressed concrete bridge girder is installed by an extrusion method, a temporary cable that releases tension is often used because the position of supporting the bridge girder varies with the progress of the extrusion process.

As a method for releasing the tension after the tension is introduced into the tension member and once fixed on the structural member, the following methods are known.
In the method shown in FIG. 12, when the bridge girder 101 is constructed, a notch 104 is provided in the rear portion of the position where the tension member 102 is fixed, that is, the portion where the tension jack 103 at the end of the tension member is attached. And when releasing tension | tensile_strength, the jack for tension | tensile_strength 103 is mounted | worn with a tension | tensile_strength material in this notch, the tension | tensile_strength material 102 is pulled, and the load of a fixing tool is released. In this state, the wedge of the fixing tool is removed or the nut is loosened to release the tension of the tension member 102.
In the method shown in FIG. 13, a fixing protrusion 111 for fixing a tension material is formed on a floor slab, and the tension material 112 is fixed by the fixing protrusion 111. After the bridge girder is completed, a tensioning jack 113 is attached to the fixing projection, and the tension is released in the same manner. After releasing the tension, the concrete fixing protrusions are removed.

  Moreover, the method of patent document 1 arrange | positions the edge part of the tension material arrange | positioned in the bridge axis direction within the upper floor slab outside the concrete member, that is, above the upper floor slab. And the ends of other tendons arranged so as to extend on the opposite side of the tendons are similarly pulled out of the concrete member, and the ends of these tendons are combined into one integrated fixing tool. To settle. That is, the reaction force of the two tendons stretched in opposite directions is applied to the integrated fixing tool to cancel each other. As a result, the two tension members are connected to each other via the integrated fixing tool, and tension force is introduced to both tension members. When releasing the tension force, a tensioning jack is attached to the integrated fixing tool on the upper floor slab, and the load of the fixing tool is released by pulling the tension material. Thereby, the tension of the tendon can be released.

  On the other hand, in addition to the case where the prestress is inserted into the concrete member as described above, the tension material may be stretched between the structural members and used to support the structure by the tension force. For example, there are a slanting material for hanging and supporting from a bridge girder in an oblique direction, a hanger for hanging and supporting a girder from a main cable of a suspension bridge, a hanger for hanging and supporting a girder of a lower arch bridge from an arch rib, and the like. These tendons may need to be replaced in order to repair or reinforce the deterioration over time, and it is necessary to release the tension when removing these tendons.

JP 2004-68332 A

However, there are the following problems in releasing the tension of the tendon as described above.
In the method shown in FIG. 12, it is necessary to form a large notch in order to attach the tensioning jack to the tension material, and the cross section of the bridge girder is reduced at this portion. For this reason, there exists a problem that the yield strength of this part falls. Moreover, when constructing a bridge girder in which reinforcing bars and PC steel materials are densely arranged, it is difficult to secure a space for arranging a tensioning jack by interfering with the reinforcing bars and the tensioning material.
As shown in FIG. 13, when the fixing protrusion is formed on the upper floor slab, it is necessary to construct or remove the fixing protrusion, which increases the construction process. And the problem that the cost accompanying this increases arises.

  Moreover, in the technique described in Patent Document 1, it is necessary to use a jack that can be attached to a tension material drawn to the upper side of the upper floor slab in order to release tension. When using a material in which a plurality of steel strands are bundled as a tension material, a large tension jack capable of introducing a large tension force is used. It is necessary to prepare such a large tension jack even when releasing the tension force, which reduces the efficiency of the work.

  On the other hand, in many cases, the tension member that supports the structural member is not assumed to release the tension force in advance. Under such conditions, it is required to release the tension of the tendon that supports the structural member while maintaining the structure in a safe state, and to remove the tendon.

  This invention is made | formed in view of such a situation, The objective is providing the tension | tensile_strength release apparatus and tension | tensile_strength release method which can release easily the tension | tensile_strength introduced into the tension | tensile_strength with a simple apparatus. That is.

  In order to solve the above-mentioned problem, the invention according to claim 1 is characterized in that the tension force of the tension member in which both ends are fixed to the structural member in a state where the tension force is introduced and part or all of the tension member is stretched outside the structural member. Two intermediate fixing blocks that are attached to the tension member to which a tension force is introduced and are arranged to face each other at an interval in the axial direction of the tension material; A fixing means for fixing both of the blocks to the tendon so as to restrain movement of the blocks in a direction approaching each other; and a connecting means for connecting the intermediate fixing blocks facing each other to each other. The means exerts a force in a direction to bring the two intermediate fixing blocks closer to each other, and the tension of the tension member is released or reduced between the two intermediate fixing blocks. It is possible to maintain a distance between each other and to allow the two intermediate fixing blocks to move away from each other after the tendon is cut between the two intermediate fixing blocks. Provided is a tension release device for a tension material.

  In this tension releasing device, when a force is applied in the direction in which the two intermediate fixing blocks are brought close to each other by the connecting means, the tension of the tension material between the two intermediate fixing blocks is applied to the connecting means, The tension between the intermediate fixing blocks is released or reduced. Then, when the tension force is released or reduced, the tension material can be cut between the two intermediate fixing blocks. Thereafter, the tension of the tendon is released by moving the two intermediate fixing blocks away from each other.

  The invention according to claim 2 is the tension release device of the tension member according to claim 1, wherein the tension member is a bundle of a plurality of steel wires or steel strands, and the intermediate fixing block includes: A through hole through which each of the steel wire or the steel strand is inserted is provided separately, and the steel wire or the steel strand is inserted into the through hole before a tension force is introduced.

  In this tension release device, it is possible to securely fix the steel wire or the steel strand as the tension material to the intermediate fixing block. Moreover, each steel wire or a strand than steel can be fixed with a small member, and work efficiency becomes favorable.

  The invention according to claim 3 is the tension force releasing device of the tension material according to claim 1 or 2, wherein the fixing means includes a ring-shaped member through which the tension material is inserted, the ring-shaped member, and the And a wedge that is pushed in between the tendon.

  In this tension releasing device, the steel wire or the steel strand into which the tension is already introduced can be fixed to the intermediate fixing block reliably and efficiently with a simple structure.

  According to a fourth aspect of the present invention, there is provided the tension member releasing device according to the first, second, or third aspect, wherein the connecting means is provided in a connecting hole provided in each of the intermediate fixing blocks. It includes a steel bar to be inserted and a nut screwed into a threaded portion of the steel bar, and a plurality of the steel bars are arranged around the tension material.

  In this device, by attaching a jack to a plurality of steel bars arranged around the tension member and tensioning the two intermediate fixing blocks, a force in a direction approaching each other can be applied in a stable state. Further, the tension force of the tendon is shared and applied to a plurality of steel bars, and the tension of the tendon can be released or reduced between the intermediate fixing blocks using a small jack.

  The invention according to claim 5 is the tension release device for the tension member according to claim 1, wherein the fixing means is arranged so that a plurality of members surround the tension member, and are connected so as to be integrated. A wedge receiving member and a wedge to be pushed between the wedge receiving member and the tension member, and the intermediate fixing block is mounted around an axis of the tension member to which a tension force has already been introduced. In this case, the fixing means is brought into contact.

 In this device, even when tension is already introduced into the tension member, the intermediate fixing block is fixed to the tension member after that, and the tension force between the two intermediate fixing blocks is released, and the tension in this portion is released. The material can be cut and the tension of the entire tendon can be released.

  The invention according to claim 6 is a method of releasing tension force of a tension material in which both ends are fixed to a structural member in a state where tension force is introduced, and a part or all of the tension material is stretched outside the structural member, Arranging the two intermediate fixing blocks to face each other at an interval in the axial direction of the tendon; and after the tension is introduced to the tendon, both of the intermediate fixing blocks are brought close to each other A step of fixing to the tendon so as to restrain the movement in a moving direction, connecting the intermediate fixing blocks facing each other, and applying a force in a direction to bring these intermediate fixing blocks closer to each other. The tensioning force of the tensioning material is released or reduced between the two intermediate fixing blocks, and the distance between the intermediate fixing blocks is maintained in this state; and the two intermediate fixing blocks There is provided a tension material releasing method characterized by comprising a step of cutting a tension material in between, and a step of moving the two intermediate fixing blocks in a state of being connected to each other in a direction away from each other.

In this tension material tension release method, the tension force can be released or reduced between the two intermediate fixing blocks of the tension material to which the tension force is introduced, and the tension material can be cut at this portion. In addition, after the tendon is cut, the two intermediate fixing blocks to which the cut tendon is fixed are moved away from each other to release the tension of each of the two tendons divided. Can do.
In this way, the tension of the tendon can be released by a simple method, the work process can be simplified and the cost can be reduced.

  The invention according to claim 7 is the tension material releasing method according to claim 6, wherein the step of fixing the intermediate fixing block to the tension material is mounted in advance between the two intermediate fixing blocks. The two ring-shaped members are brought into contact with the mutually opposing surfaces of the intermediate fixing block, and wedges are provided between the respective ring-shaped members and the tension member from the side opposite to the contact portion with the intermediate fixing block. Shall be inserted.

  In this tension release method, the ring-shaped member is fixed to the tension member by the wedge, and the intermediate fixing block is abutted against the ring-shaped member and fixed to the tension member. Therefore, it is possible to securely fix the tension material to which the tension force is introduced to the two intermediate fixing blocks with a simple structure.

  The invention according to claim 8 is the tension material releasing method according to claim 6, wherein the step of fixing the intermediate fixing block has already applied tension to the divided portion of the wedge receiving member divided into a plurality of parts. After arranging the tension material being introduced so as to surround it and connecting them together, the wedge receiving member is fixed to the tension material by pushing a wedge between the tension material and the wedge receiving member, The intermediate fixing block is locked to the wedge receiving member.

  In this tension release method, the wedge receiving member is fixed to the tension member that was not scheduled to release the tension. Therefore, the tendon can be firmly fixed to the two intermediate fixing blocks with a simple structure.

  As described above, according to the tension force releasing device and the tension force releasing method of the present invention, the tension force introduced into the tension material can be easily released with a simple device.

It is a schematic side view showing a prestressed concrete bridge during cantilever construction, and a tension member that is used at the time of construction of the bridge, and later releases tension force using a tension force release device according to an embodiment of the present invention. . It is the schematic front view and schematic side view which show the tension | tensile_strength release apparatus with which the tension material shown in FIG. 1 was mounted | worn. FIG. 3 is a schematic cross-sectional view showing a fixing jig for fixing a tension member of the tension releasing device shown in FIG. 2 to an intermediate fixing block. It is a schematic perspective view which shows the guide member which guides the tension material arrange | positioned in the PC bridge shown in FIG. 1 to the tension material release apparatus. It is a figure which shows the process of releasing the tension | tensile_strength of a tension material using the tension | tensile_strength release apparatus shown in FIG. It is a figure which shows the process of releasing the tension | tensile_strength of a tension material using the tension | tensile_strength release apparatus shown in FIG. It is a figure which shows the process of releasing the tension | tensile_strength of a tension material using the tension | tensile_strength release apparatus shown in FIG. It is a schematic side view of the downhill type arch bridge which can release the tension | tensile_strength of a suspension material using the tension | tensile_strength release apparatus which is one Embodiment of this invention. It is a schematic front view of the tension | tensile_strength release apparatus which can release | release the tension | tensile_strength of the suspension material of a lower arch bridge shown in FIG. FIG. 10 is a schematic plan view and a schematic front view of an intermediate fixing block used in the tension releasing device shown in FIG. 9. It is the schematic plan view and AA arrow directional view of the wedge receiving member used with the tension | tensile_strength release apparatus shown in FIG. It is a schematic side view which shows the tension | tensile_strength release method of the conventional tension material. It is a schematic side view which shows the tension | tensile_strength release method of the conventional tension material.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a prestressed concrete bridge (PC bridge) that is cantilevered, and a tension that is used at the time of erection of the bridge, and that later releases a tension force using a tension force release device according to an embodiment of the present invention. It is a schematic side view which shows material.
This PC bridge is formed such that concrete bridge girder 1 is sequentially projected from the upper part of bridge pier 2 to each side of each construction block 3 having a predetermined length while being balanced. And this bridge girder 1 is connected with the bridge girder (not shown) overhanging so that it may oppose on the other bridge pier, and becomes a ramen structure. And the tension material 5 is arrange | positioned in order to respond | correspond to the bending moment which acts on the bridge girder 1 during overhang | projection construction, this tension material 5 is tensioned, and it fixes to the concrete of a bridge girder. As a result, prestress is introduced into the concrete and excessive tensile stress is prevented from occurring in the concrete.

  When the bridge girder 1 having such a ramen structure is extended and installed, a large negative bending moment acts on the pier 2 immediately before the bridge girder 1 extended from both sides is connected at the center portion of the span. On the other hand, in the structure system after the central part of the span is connected, the positive bending moment can be resisted at the central part of the span, and the negative bending moment on the pier 2 can be reduced. Therefore, in the PC bridge, the tension force is released after the central part of the span is connected to a part of the tension member 5 arranged near the upper edge of the bridge girder 1 during the overhanging construction.

  As the above-described tension member 5 from which tension is released in the present embodiment, a bundle of six strands 6 of steel having an outer diameter of 15.2 mm is used. The tendon 5 is inserted into a tubular sheath embedded in an upper part 7 of a bridge girder that is extended from the upper part of the pier 2 to both sides. In the vicinity of the upper part of the pier 2, it is bent upward and drawn out of the concrete member above the upper surface of the bridge girder and is arranged along the upper surface. Tensile force is introduced into both ends of the tension member 5 at the end of the construction block 3 d and fixed to the concrete of the construction block 3 d using the fixing tool 8.

After tension force is introduced into the tension member 5 and both ends thereof are fixed using the fixing tool 8 in the vicinity of the end of the construction block 3d, the next construction block 3e is further connected to the tip of the construction block 3d. And it is overhanging construction sequentially.
The construction block 3e arranged to face the fixing tool 8 is provided with a notch 4 facing the fixing tool 8. This notch 4 is provided in order to release the grip of the tension material by the fixing tool 8 when the tension force of the tension material 5 is released. For example, in the case of fixing the tension material with a wedge, The size is such that the wedge can be removed and the fixation of the tendon can be released. Therefore, the cutout 4 may be smaller than the cutout for mounting a tension jack or the like.

  In this way, the construction blocks are sequentially formed, and the tip of the bridge girder 1 that is cantilevered is connected to the bridge girder protruding from the opposite side to form a series of bridge girder. It is released using the tension release device 20 which is an embodiment of the present invention.

The tension release device 20 is provided in a portion where the tension material near the pier is disposed outside the concrete member. As shown in FIG. 2, the first steel block 21 and the second steel block which are intermediate fixing blocks are provided. 31 and fixing steels 25 and 35, which are arranged between these two steel blocks and restrain the movement of these steel blocks in a direction close to each other, and PC steel connecting the steel blocks The main part is composed of a connecting means comprising a rod 40 and a fixing nut 41 for locking the PC steel bar 40 to the steel blocks 21 and 31. In FIG. For the sake of convenience, a part of the steel strand 6 is omitted.

The first steel block 21 and the second steel block 31 are thick plate-like members formed of steel, and these are members having the same shape and the same dimensions. Six through-holes 23 and 33 through which six steel wires 6 are individually inserted are formed independently at the center of the plate-like surfaces of the steel blocks 21 and 31. And the steel strand 6 before tension | tensile_strength is introduce | transduced is penetrated by the said through-holes 23 and 33, and the two steel blocks 21 and 31 are arrange | positioned so that it may oppose at intervals. Further, around the through holes 23 and 33, three connection holes 24 and 34 for inserting the PC steel rod 40 are formed, and six steel strands inserted into the steel blocks 21 and 31 are formed. Three PC steel bars 40 can be arranged so as to surround 6.
The shape of the outer peripheral edges of the steel blocks 21 and 31 is a shape obtained by rounding off the apex portion of the equilateral triangle, and the connecting holes 24 and 34 are provided in the rounded protruding portions.

As shown in FIG. 3, the fixing jigs 25 and 35 include steel ring-shaped members 26 and 36, and wedges 27 and 37 that are pushed between the ring-shaped members 26 and 36 and the steel strand 6. , Is composed of. When the tension member 6 is stretched along the bridge girder being installed, only the ring-shaped members 26 and 36 are inserted through the steel strand 6 in advance, and the first steel block 21 and the second steel block 31 are connected to each other. Between, it arrange | positions in the inner surface vicinity of each steel block.
The wedges 27 and 37 are divided into four parts, which are arranged in the circumferential direction and can be inserted between the ring-shaped members 26 and 36 and the steel strand 6 with a gap between them. ing. Then, when the two steel blocks 21 and 31 move together with the ring-shaped member so as to reduce the distance between them, they are pushed between the ring-shaped members 26 and 36 and the tension member 6, and the ring-shaped member is attached to the tension member 5. Fix it. Thereby, the two steel blocks 21 and 31 are abutted against the ring-shaped member, and the position with respect to the tension material is fixed, so that the movement of the two steel blocks 21 and 31 toward each other is restricted. .
The wedge need not be limited to one divided into four parts, and may be any shape that is divided into a plurality of parts and that can be inserted between the ring-shaped member and the steel strand by providing a gap therebetween. Also, other known jigs can be adopted as the fixing jig.

The PC steel bar 40 may be a full thread steel bar that is threaded over its entire length. And when releasing the tension | tensile_strength of the tension | tensile_strength material 5, it inserts in the connection holes 24 and 34 of each steel block 21 and 31 so that the 1st steel block 21 and the 2nd steel block 31 may be connected. Is.
The fixing nut 41 is screwed onto the PC steel rod 40 so that the PC steel rod 40 is engaged with the steel blocks 21 and 31 outside the first steel block 21 and the second steel block 31 facing each other. Combined.
The PC steel bar 40 is not limited to a fully threaded steel bar, and it is sufficient that a screw is provided at least at a portion where the fixing nut 41 is screwed.

  A first cable lead-out port 7a and a second cable lead-out port 7b are provided in a portion where the tension material 5 embedded in the upper deck 7 is drawn upward from the concrete of the bridge girder near the pier. The tension members 5 are bent up from these cable outlets and arranged on the upper side of the bridge girder. And the guide member 9 shown in FIG. 4 was each provided in the part where the wire 6 was pulled out from these cable outlets 7a and 7b, and was bent up from the cable outlets 7a and 7b above the bridge girder. Each steel strand 6 is led to the through holes 23 and 33 of the steel blocks 21 and 31 arranged on the bridge girder.

  Moreover, in the part arrange | positioned in the concrete before a tension | tensile_strength is pulled out from the said cable outlet 7a, 7b, when tension | tensile_strength is introduce | transduced into the tension | tensile_strength 5 bent up upwards, it is on the upper surface in a sheath. A force pushing up acts. For this reason, it is desirable to arrange reinforcing bars that resist upward forces acting from the tension members 5 embedded in the concrete around the sheath where the steel strands are arranged.

Next, a method for releasing the tension of the tendon using the tension release device 20 will be described.
5 to 7 are schematic side views showing a process of releasing the tension force of the tension material.
In addition, also in these figures, among the six steel strands, the middle two strands are not shown for convenience.
The steel blocks 21 and 31 and the ring-shaped members 26 and 36 of the tension release device 20 are arranged on the bridge girder 1 when the steel strand 6 as the tension material is arranged as shown in FIG. Then, the steel wire 6 is inserted into the through holes 23 and 33 and the ring-shaped members 26 and 36 of the steel blocks 21 and 31. Then, tension is introduced into the steel strand 6 and prestress is introduced into the bridge girder 1.

When the construction of the bridge girder 1 progresses and the tension force of the tension member 5 is released, as shown in FIG. 5 (b), the PC steel rod 40 is connected to the connection holes 24, formed in the two steel blocks 21, 31. The fixing nut 41 is screwed so that the PC steel rod 40 does not come out of the connecting holes 24 and 34 outside the two steel blocks 21 and 31 facing each other. Further, wedges 27 and 37 are inserted between the ring-shaped members 26 and 36 and the steel strand 6.
In the present embodiment, the fixing nut 41 is screwed to both ends of the PC steel rod 40 inserted through the connection holes of the steel blocks 21 and 31, but the diameter of the fixing portion 41 is increased at one end of the PC steel rod. The formed head may be integrally formed, and the head may be locked to one steel block.

  When the tension release device 20 is mounted in this manner, as shown in FIG. 6A, a PC steel bar center hole jack 50 is mounted on one end of the PC steel bar 40 for each of the PC steel bars. Tension is introduced into the PC steel bar 40. Thereby, the 2nd steel block 31 bears the reaction force of the center hole jack 50, and force acts on the two steel blocks 21 and 31 in the directions of arrows A and B shown in FIG. . Then, the two steel blocks 21 and 31 move together with the ring-shaped members 26 and 36 in a direction approaching each other, and the wedges 27 and 37 are strongly pushed between the ring-shaped members 26 and 36 and the steel strand 6. Thereby, the ring-shaped members 26 and 36 are firmly fixed to the strand 6 of steel, and the two steel blocks 21 and 31 are also restrained from moving relative to the strand of steel.

  Further, when a tension force is introduced into the PC steel bar 40, the tension force of the stranded wire 6 between the steel blocks 21, 31 is reduced by the force in the direction in which the two steel blocks 21, 31 are brought close to each other. . That is, the tension force introduced into the steel strand 6 is borne by the PC steel rod 40 and is replaced with the tension force of the PC steel rod 40. Thereby, the tension force introduced into the steel strand 6 on both sides of the tension release device 20 is transmitted to the PC steel rod 40 via the steel blocks 21 and 31, and the steel strand 6 is moved between the two steel blocks. The tension is reduced or released.

  Thus, when the tension | tensile_strength of the wire 6 between the steel blocks 21 and 31 is released, the steel strand 6 can be cut | disconnected between steel blocks, as shown in FIG.6 (b). That is, even if the steel wire 6 is cut, the impact that the tension force is suddenly applied to other members does not occur. And the cut | disconnected steel strand 6 will be in the state by which both ends were fixed to the steel blocks 21 and 31 and the concrete of a bridge girder, respectively.

  Next, the fixing nut screwed on the tension side of the PC steel bar is rotated so as to be loosened, and the center hole jack 50 for the PC steel bar is slowly decompressed. Thereby, as shown in FIG. 7, the two steel blocks 21 and 31 move in a direction away from each other, and the tension of each of the wires 6 is gradually released from the steel divided into two. When the tension is released, the fixing tool 8 that has fixed the steel strand as the tension material 5 to the concrete of the bridge girder 1 can be removed in the notch 4 to remove the tension material.

Thus, in this Embodiment, the tension | tensile_strength of the tension | tensile_strength material 5 which bundled several steel strand 6 was released with the center hole jack 50 for PC steel bars, without using a large sized tension jack. It becomes possible. Thereby, work efficiency improves and it becomes possible to shorten a work schedule and cost.
Further, when the tension member 5 is tensioned again, the tension force is again applied to each of the tension members divided between the two steel blocks 21 and 31 by tensioning the PC steel rod 40 using the center hole jack 50. Can be introduced.

In addition, in this Embodiment, although what bundled six steel strands was used as a tension material, what bundled steel wires can also be used, and the number of steel strands or steel wires bundled can be used. Even when the diameters are different, it can be dealt with by appropriately designing the shape dimensions of the steel block, ring-shaped member and wedge.
Further, the material and shape of the steel block, the arrangement of through holes and connecting holes formed in the steel block, and the like can be changed as appropriate.

  On the other hand, in the above embodiment, in order to fix the intermediate fixing block to the tension member, a ring-shaped member is used as a member for attaching a wedge, and the intermediate fixing block is pushed into the ring-shaped member fixed to the tension member. However, the inner diameter of the through hole provided in the intermediate fixing block is changed, and the wedge is pushed between the inner peripheral surface of the through hole formed in the intermediate fixing block and the tension material. May be.

Next, a second embodiment of the present invention will be described.
FIG. 8 is a schematic side view showing a bridge that can use the tension releasing device according to the second embodiment of the present invention.
This bridge is a concrete arch bridge made of concrete, and arch ribs 61 and girders 62 are integrally joined at both ends. The girder 62 is suspended and supported from the arch rib 61 by a suspension member 63. A steel rod is used for the suspending material 63, and it is necessary to replace the suspending material 63 to repair or reinforce the deterioration over time. The tension material introduced into the suspending material 63 is once released to suspend the material. 63 is exchanged. In order to release the tension force of the suspension member 63, the tension force release device according to the embodiment of the present invention can be used, and the configuration thereof is as follows.

  As shown in FIG. 9, the tension release device 70 includes two intermediate fixing blocks 71 and 81 that are attached to an intermediate portion of a suspension member 63 that is a tension member fixed at both ends to an arch rib 61 and a girder 62. Wedges 72 and 82 and wedge receiving members 73 and 83 that function as fixing means for the two intermediate fixing blocks 71 and 81, a connecting steel rod 74 that connects the two intermediate fixing blocks 71 and 81 to each other, and a connecting steel rod The main part is composed of a nut 75 which is engaged with the intermediate fixing block.

The intermediate fixing blocks 71 and 81 are made of steel. As shown in FIG. 10, U-shaped notches are formed on thick plates 71a and 81a (for example, 50 mm thick) supported at right angles to the suspension member 63. 71b and 81b are provided, and the suspension member 63 is fitted into the notch. Then, the connection plates 71d and 81d to which the small blocks 71c and 81c to be inserted into the U-shaped cutouts are attached are joined by bolts 71e and 81e along the edge where the thick plate cutouts are provided. The position of the suspension material is regulated within the U-shaped notch. Further, on both sides of the U-shaped cutouts 71b and 81b, connecting holes 71f and 81f are provided in the thickness direction of the thick plate, and the connecting steel rod 74 is inserted into the connecting holes. The nut 75 screwed to the connecting steel rod 74 is engaged with the thick plates 71a and 81a.
The thick plates 71a and 81a are provided with U-shaped cutouts so that a cross-sectional defect occurs. Reinforcing ribs 71g and 81g are provided to reinforce the thick plates on both sides of the position where the cross-section is narrowed. ing.

  The wedge receiving members 73 and 83 are provided for the two intermediate fixing blocks 71 and 81, respectively, and are attached to the suspension member 63 so as to contact the surfaces of the two intermediate fixing blocks facing each other. is there. The wedge receiving members 73 and 83 are formed by joining a pair of thick plate members 73a and 83a, and the bolts 73c and 83c are inserted into the bolt holes 73b and 83b provided in the respective thick plate members. These bolts are tightened to unite the pair of thick plate members 73a and 83a. These thick plate members are provided with recesses 73d and 83d at positions facing each other, and form through holes 73e and 83e through which the suspension member 63 is inserted when joined. The formed through holes 73e and 83e are extended from the side in contact with the intermediate fixing block to the opposite side, and the inner diameter is enlarged, and wedges 72 and 82 described later are pushed into the through holes 73e and 83e.

  The wedges 72 and 82 are divided into two parts and can be pushed between the attached wedge receiving members 73 and 83 and the suspension member 63. A large number of small convex portions that are continuous in the circumferential direction of the suspension material 63 are provided on the inner surfaces of the wedges 72 and 82 that are in contact with the suspension material 63, and are difficult to slide with respect to the suspension material 63. The wedges 72 and 82 can be pushed into the wedge receiving members 73 and 83 from the side opposite to the surface in contact with the intermediate fixing blocks 71 and 81, that is, the side where the inner diameters of the through holes 73e and 82e are enlarged. When the intermediate fixing blocks 71 and 81 and the wedge receiving members 73 and 83 are moved in a direction approaching the other intermediate fixing block, the wedges 72 and 82 are interposed between the wedge receiving members 73 and 83 and the suspension member 63. It is pushed in strongly. As a result, the wedge receiving members 73 and 83 are fixed to the suspension member 63 and restrain the intermediate fixing blocks 71 and 81 from moving in a direction approaching each other.

  The connecting steel rod 74 is inserted into connecting holes 71f and 81f formed in the pair of intermediate fixing blocks 71 and 81 so as to come into contact with the opposite surface of the two intermediate fixing blocks 71 and 81. A nut 75 is screwed onto the screw. These connecting steel rods 74 can introduce tension by a center hole jack 76. The connecting steel rod 74 is capable of applying a force in a direction in which the two intermediate fixing blocks 71 and 81 approach each other by introducing a tension force, and can maintain a state in which the tension force is introduced by tightening the nut 75. It has become.

  In such a tension releasing device 70, intermediate fixing blocks 71 and 81 and wedge receiving members 73 and 83 are attached to the suspension member 63 on which the tension is applied, and two intermediate fixing blocks are connected by a connecting steel rod 74. Can be connected to each other, and a force in a direction approaching each other can be applied to these intermediate fixing blocks 71 and 81. As a result, the tension of the suspension member 63 is released between the two intermediate fixing blocks, and even if the suspension member 63 is cut at this portion, a large impact force does not act on the structural member. After the suspension member 63 is cut, the tension of the suspension member 63 is released over the entire length by releasing the traction force of the center hole jack 76 while loosening the nut screwed to the connecting steel rod 74. The suspension member whose tension force has been released can be removed, and the suspension member 63 can be replaced by installing a new tension member and introducing the tension force.

  As shown in FIG. 8, when releasing the tension of the suspension member 63 that supports the beam 62 from the arch rib 61, a temporary support tension member is arranged in parallel to the suspension member 63, or It is preferable to support the girder 62 by providing a temporary support (not shown) that supports the ground. Further, it is desirable to reduce the tension of the suspension member 63 by introducing a tension force to the temporary support tension member or jacking up the girders 62 on the temporary column. Accordingly, it is possible to prevent an excessive tension force from acting on the suspension member 63 when the connecting steel rod 74 is tensioned after the two intermediate fixing blocks 71 and 81 are mounted.

1: bridge girder, 2: bridge pier, 3: construction block, 4: notch of construction block, 5: tension material, 6: steel strand, 7: part where tension material is drawn upward from the concrete of the bridge girder, 8: Fixing tool, 9: guide member,
20: tension release device, 21: first steel block, 23: first steel block through-hole, 24: first steel block connecting hole, 25: first steel block fixing jig 26: ring-shaped member of the fixing jig on the first steel block side, 27: wedge of the fixing jig on the first steel block side,
31: Second steel block, 33: Second steel block through-hole, 34: Second steel block connecting hole, 35: Second steel block fixing jig, 36: Second steel A ring-shaped member of the fixing jig on the block side, 37: a wedge of the fixing jig on the second steel block side,
40: PC steel bar, 41: Fixing nut,
50: Center hole jack for PC steel bar 61: Arch rib, 62: Girder, 63: Suspension material,
70: tension release device, 71, 81: intermediate fixing block, 71a, 81a: thick plate, 71b, 81b: U-shaped notch, 71c, 81c: small block, 71d, 81d: connection plate, 71e, 81e : Bolt, 71f, 81f: connecting hole, 71g, 81g: reinforcing rib,
72, 82: wedge,
73, 83: Wedge receiving member, 73a, 83a: Thick plate member, 73b, 83b: Bolt hole, 73c, 83c: Bolt, 73d, 83d: Recess, 73e, 83e: Through hole, 74: Connecting steel rod, 75: Nut, 76: Center hole jack

Claims (8)

A device for releasing the tension of a tension material in which both ends are fixed to the structural member in a state where the tension force is introduced and a part or all of the tension material is stretched outside the structural member,
Two intermediate fixing blocks that are attached to the tendon to which tension is introduced and are arranged to face each other with an interval in the axial direction of the tendon;
Fixing means for fixing both of the intermediate fixing blocks to the tendon so as to restrain movement of the intermediate fixing blocks toward each other;
Coupling means for coupling the intermediate fixing blocks facing each other;
The connecting means applies a force in a direction in which the two intermediate fixing blocks are brought close to each other, and the tension of the tension member is released or reduced between the two intermediate fixing blocks. It is possible to maintain an interval between the two intermediate fixing blocks and to allow the two intermediate fixing blocks to move away from each other after the tension material is cut between the two intermediate fixing blocks. Tension release device for tension material. The tendon is a bundle of a plurality of steel wires or steel strands,
The intermediate fixing block is separately provided with a through hole through which each of the steel wire or the steel strand is inserted,
2. The tension-strength releasing device for a tension member according to claim 1, wherein the steel wire or the steel strand is inserted into the through-hole before the tension is introduced. 3.   The said fixing | fixed means contains the ring-shaped member by which the said tension material was penetrated, and the wedge pushed in between this ring-shaped member and the said tension material, The Claim 1 or Claim 2 characterized by the above-mentioned. Tension release device for tension material. The connecting means includes a steel bar inserted into a connecting hole provided in each of the intermediate fixing blocks, and a nut screwed into a threaded portion of the steel bar,
The tension | tensile_strength tension | tensile_strength release apparatus of the tension | tensile_strength material of Claim 1, 2 or 3 characterized by the above-mentioned. The fixing means includes a wedge receiving member that is arranged so that a plurality of members surround the tendon and are connected together, and a wedge that is pushed in between the wedge receiving member and the tendon. Is,
2. The tension member according to claim 1, wherein the intermediate fixing block is mounted around an axis of the tension member to which a tension force has already been introduced and is in contact with the fixing unit. Tension release device. Both ends are fixed to the structural member in a state where the tension force is introduced, and a part or all of the tension member is stretched outside the structural member to release the tension force of the tension member,
Arranging the two intermediate fixing blocks facing each other at an interval in the axial direction of the tendon;
Fixing both of the intermediate fixing blocks to the tendon so as to restrain movement of the intermediate fixing blocks in a direction approaching each other after a tension force is introduced into the tendon;
The intermediate fixing blocks facing each other are connected to each other, and a force is applied in a direction to bring these intermediate fixing blocks closer to each other so that the tension of the tensioning material is released or reduced between the two intermediate fixing blocks. Maintaining the space between the intermediate fixing blocks in this state;
Cutting the tendon between the two intermediate fixing blocks;
And a step of moving the two intermediate fixing blocks in a state of being connected to each other in a direction away from each other.   The step of fixing the intermediate fixing block to the tendon includes contacting two ring-shaped members, which are mounted in advance between the two intermediate fixing blocks, with the mutually opposing surfaces of the intermediate fixing block, The tension material releasing method according to claim 6, wherein a wedge is pushed in between the ring-shaped member and the tension material from the side opposite to the contact portion with the intermediate fixing block. . In the step of fixing the intermediate fixing block, the divided portions of the wedge receiving member divided into a plurality are arranged so as to surround the tension material in which the tension force has already been introduced, and after these are connected together, The wedge fixing member is fixed to the tension member by pushing a wedge between the tension member and the wedge receiving member, and the intermediate fixing block is locked to the wedge receiving member. 6. A method for releasing tension of a tension material according to 6.

Images