JP2000110353A - Strand tightening device and strand tightening method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a strand straightening device and a strand tightening method using the device for not only facilitating mounting for a strand but also facilitating handling by suppressing the device size of a tightening direction to use in the tightening direction of the strand even when a space is narrow as compared with the conventional type device having equivalent tightening force giving performance and separating a fixing part and a tightening part to be attached and detached. SOLUTION: This strand tightening device A comprises a fixing jack 1 incorporating a fixing center hole jack 5 capable of suppressing the male cone of a fixing grip and inserting a strand in a center hole 7 and provided with a plurality of pressure receiving parts 6, 6 on the side part and a. tightening jack 2 having a recess groove part 8 opening one side face on the center part, provided with wedge-like tightening pawls 9, 9 sandwiching the strand in the recess groove part 8, and incorporating a plurality of cylinder jacks 10, 10 on the side part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strand tensioning device and a strand tensioning method, and more particularly to a PC steel material for a concrete structure and a PC for a suspension bridge, a cable-stayed bridge, and the like.
The present invention relates to a strand tensioning device and a strand tensioning method used in a work for applying tension to a strand used for a cable and maintaining the state with a fixing grip.

[0002]

2. Description of the Related Art Conventionally, a strand tensioning method for applying tension to a strand such as a PC steel material of a concrete structure or a PC cable of a suspension bridge, a cable-stayed bridge or the like by a tensioning device and maintaining the tensioned state by a fixing grip has been known. It is known. In other words, after the base end of the strand is fixed to the structure, the distal end of the strand is led out from the reaction pressure receiving surface of the structure, and after the anchor plate and the fixing grip are attached, the strand is tensioned by the tensioning device. The tension is maintained by clamping the strand with the fixing grip.

The above-mentioned conventional tensioning device has a basic structure in which a tensioning center hole jack and a fixing center hole jack are built in the device body at linear intervals, so that the dimension of the device in the tensioning direction is reduced. It was big. In the tensioning method, a space for installing a tensioning device and driving it is necessary, and in order to secure sufficient space, design of the tensioning method and eventually the main structure of concrete structures, suspension bridges, cable-stayed bridges, etc. Requires special consideration for construction.

FIG. 8 shows a strand tensioning method using a conventional tensioning device on the premise that the aforementioned space is sufficiently secured. First, an anchor plate 102 and a fixing grip 1 are attached to a strand 101 whose tip is led out from a reaction force receiving surface 100 such as a concrete structure.
After the mounting, the distal end of the strand 101 is inserted into the fixing center hole jack 105 of the tensioning device 104 and the center hole of the tensioning center hole jack 106 in order and mounted (see FIG. 8A). Next, when the tension center hole jack 106 is driven backward, the wedge-shaped grip 107 provided therein automatically clamps the strand 101 and applies tension to the strand 101 (FIG. 8).
(b)). Then, the fixing center hole jack 105 is driven forward to press the male cone 103A of the fixing grip 103 into the female cone 103B to fix the strand 101 and maintain the applied tension (see FIG. 8 (c)). . Then, when the tension center hole jack 106 is driven forward, the clamping of the strand 101 by the wedge-shaped grip 107 is automatically released and returns to the initial state. When the tension is insufficient, the above operation is repeated, and the predetermined operation is repeated. After the tension is obtained, the tension device 104 is removed from the strand 101, and the strand 101 is cut into a predetermined length (see FIG. 8D).

[0005] Such a strand tensioning method is disclosed in PC
It is used for horizontal tightening work using PC steel wires in bridges.
PC bridges are constructed by constructing a large number of factory-produced girders at predetermined intervals on piers, fixing the girder with concrete, and tightening laterally with PC steel wires that penetrate and cross all the girders. . Therefore, when three or more PC bridges are to be constructed close to each other, the bridges are usually constructed in order from the bridge located at the end in order to secure a space for laterally tightening the PC steel wires. However, if it becomes necessary to newly install the PC bridge 202 between the existing bridges 200 and 201 for some reason as shown in FIG. 9, a special construction method must be adopted. That is, a temporary receiving sanddle (not shown) is placed on the upper surface of the pier 203, and the bridge girder 204 is placed thereon by a conventional method.
And the bridge girder 204 is connected to the existing bridge 200, 2
01, and at least one of the existing bridges 200 is dismantled and the side walls of the bridge girder 204 are dismantled to secure a space for mounting the tensioning device 206. The side is tightened by applying tension to the side. Thereafter, in order to lift the bridge girder 204 to a predetermined position, a number of vents 208 are temporarily provided below the bridge girder 204, a temporary receiving beam 209 is erected thereon, and a plurality of sandals 210 are further mounted on the temporary receiving beam 209. And hydraulic jack 2
11 is installed to support the bridge girder 204. Then, the temporary receiving sandals are changed and lifted by one stroke with a hydraulic jack. After supporting the bridge girder 204 with the temporary receiving sandles, the jacking sandles 210 are changed and the hydraulic girder 211 is used to change the bridge girder 204 with the hydraulic jack 211. To support. By repeating this operation, the temporary receiving sandals are finally removed, and the bridge girder 204 is directly placed on the bearing of the pier 203. Thereafter, the vent 208 and its foundation are removed, and the erection work is completed. However, the lifting of PC bridges requires careful adjustment of the lifting amount of each jack, especially in the case of a large number of bridge girders, since cracks may enter the concrete. This is a large-scale construction, and the construction cost is very high.

The above-mentioned tensioning device is also used for introducing tension of the PC cable 301 of the cable-stayed bridge 300 as shown in FIG. The cable-stayed bridge 300 is a bridge tower 30 erected in the center.
The bridge girder 303 is supported by a large number of PC cables 301 that are inclined and passed from 2.
As shown in FIG.
Is attached to the bridge girder 303 under tension. To apply tension to the PC cable 301, the PC cable 3 pulled out from the reaction pressure receiving surface 304 as described above is used.
An anchor plate 305 and a fixing grip 306 are attached to the distal end of the device 01, and a tension device 308 composed of a center hole jack is attached via a ram chair 307. Since this tensioning work is all performed in a narrow space inside the bridge girder 303, it is extremely dangerous work to find difficulties in transporting and setting the heavy and long tensioning device 308 and operating the hydraulic machine.

[0007]

SUMMARY OF THE INVENTION In view of the above situation, the present invention seeks to solve the problem by reducing the size of the device in the tensioning direction as compared with a conventional type device having the same tension applying performance. Suppress and allow use in places where the space in the tension direction of the strand is narrow,
In addition, by separating the fixing part and the tension part so that they can be detached and attached, not only is it easy to attach to the strand, but also the strand tensioning device that is easy to handle, and the strand tensioning method using the device The point is to provide.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a tensioning device for tensioning a strand which maintains tension by a fixing grip comprising a female cone and a male cone while applying tension to the strand. A fixing jack having a fixing center hole jack that presses a male cone of a fixing grip and allows a strand to be inserted into a center hole at a central portion, and a plurality of pressure receiving portions on a side portion, and a central portion. A tensioning jack having a wedge-shaped tensioning claw for holding the strand in the grooved groove, and a plurality of cylinder jacks built in at the side portions. The strand is inserted through the hole, the strand is received in the groove of the tension jack, and the piston lock of each cylinder jack is received. Tip was constructed tension device of the strand formed by suppressing the tensioning direction of the apparatus dimension in the state of being linked to the pressure receiving portion of each fixing jacks.

Further, the strand tensioning device of the present invention comprises:
A connection projection is provided at the tip of each piston rod of the tension jack, and a connection groove that is open to one side and the tension jack side and that can receive the connection projection is formed in each pressure receiving portion of the fixing jack, The connecting projection of each piston rod can be simultaneously engaged with the connecting groove of the fixing jack from a direction orthogonal to the tension direction of the strand. As a result, the fixing jack and the tension jack can be separately carried and carried, and can be combined integrally at the time of use.

[0010] Further, the opposing surface of the concave groove portion of the tension jack is a tapered surface whose interval becomes narrower as approaching the fixing jack, and a pair of the tension claws are formed in the concave groove portion with the inclined surface formed into a tapered surface. The pressing portions are disposed so as to be in sliding contact with each other, and the pressing portions projecting from the thick ends of the tension claws in the direction in which the strands are tensioned project from the main body of the tension jack. As a result, the strand can be securely held in the initial stage of the tension, and there is no play in the tension direction, and the stroke of the tension jack can be used to the maximum.

[0011] The end face of each pressure receiving portion of the fixing jack, which is on the side facing the fixing jack and the tension jack, is formed by retreating from the end face of the center portion having the built-in center hole jack. The protrusions
The tension jack can be received in a recess formed in the center end face. This makes it possible to significantly reduce the size of the device in the tension direction.

[0012] Further, a preparatory step for fixing the anchor plate and the fixing grip to the strand whose base end is fixed to the structure and the front end of which is led out from the reaction force receiving surface of the structure as usual, A fixing jack having a built-in center hole jack and having a plurality of pressure-receiving parts on the sides was inserted by inserting the strand from the end into the center hole of the center hole jack, and then one side was opened to the center. A tension jack having a concave groove portion and having a wedge-shaped tensioning claw for holding the strand in the concave groove portion, and a tension jack having a plurality of cylinder jacks built in a side portion is inserted into the groove portion from the side of the strand. A setting step of receiving and mounting a piston rod tip of each cylinder jack in association with a pressure receiving section of the fixing jack; and After inserting and holding the strand, the tension jack is driven, the piston rods of both cylinder jacks press the pressure receiving portion of the fixing jack to apply tension to the strand, and then the center hole jack of the fixing jack is driven. After the male cone of the fixing grip is pushed into the female cone to fix the strand, the piston rod of the tension jack is pulled in, the tension claws are loosened to approach the fixing jack, and the tension claws are pushed again to clamp the strand. The present invention provides a tensioning method for a strand, which comprises releasing the pressing of a center hole jack to return to an initial state and repeating these operations a predetermined number of times, and a strand tensioning method.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the accompanying drawings. 1 to 6 show a strand tensioning device A of the present invention. In the drawings, reference numeral 1 denotes a fixing jack, and 2 denotes a tensioning jack. The tensioning device A of the present invention
Is used in a tensioning method in which a tension is applied to a strand 3 used for a PC steel material of a concrete structure or a PC cable such as a suspension bridge or a cable-stayed bridge, and the state is maintained by a fixing grip 4. Is not particularly limited.

The tensioning device A of the present invention is composed of a fixing jack 1 and a tensioning jack 2 so that they can be transported and handled separately and can be used in combination. The tension state is maintained by the fixing grip 4 composed of the male cone 4B and the male cone 4B. The fixing jack 1 has a fixing center hole jack 5 built in the center and pressure receiving portions 6 and 6 on both sides, and the strand 3 is inserted into a center hole 7 of the center hole jack 5. ,
The center hole jack 5 is driven forward to press the male cone 4B of the fixing grip 4 into the female cone 4A, and the strand 3 is held by the fixing grip 4. The tension jack 2 has a concave groove 8 with one side open at the center, and wedge-shaped tension claws 9 for holding the strand 3 in the concave groove 8, and a pair of tension claws 9 on both sides. The cylinder jacks 10, 10 are built in. Then, the strand 3 is inserted into the center hole 7 of the fixing jack 1, and the groove 8 of the tension jack 2 is formed.
In this case, the strands 3 are received, and the distal ends of the piston rods 11, 11 of the two cylinder jacks 10, 10 are used in connection with the pressure receiving parts 6, 6 of the fixing jack 1, respectively.

More specifically, connecting projections 12 and 12 having a substantially T-shaped cross section are provided at the distal ends of both piston rods 11 and 11 of the tensioning jack 2, respectively, and both pressure receiving portions 6 and 6 of the fixing jack 1 are provided. Center hole jack 5
Are formed on one side perpendicular to the center axis of the shaft and on the side of the tension jack 2 to form the connecting grooves 13 having a substantially T-shaped cross section and capable of receiving the connecting protrusion 12, and are perpendicular to the direction of tension of the strand 3. The connecting projections 12, 12 of both piston rods 11, 11 can be simultaneously engaged with the connecting grooves 13, 13 of the fixing jack 1 from the direction, so that the fixing jack 1 and the tension jack 2 can be connected at the time of use. .

The end faces of the pressure receiving portions 6 and 6 of the fixing jack 1 on the side opposite to the fixing jack 1 and the tension jack 2 are set back from the end face of the central portion in which the center hole jack 5 is built. The central projection 14 formed by this is received in a recess 15 formed in the end face of the central portion of the tension jack 2 so that the size of the device in the tension direction of the strand is greatly suppressed.
Although the device size becomes shorter as the receiving depth of the projecting portion 14 into the recess 15 becomes smaller, the bending strength and rigidity of the pressure receiving portions 6 and 6 on both sides with respect to the center portion of the fixing jack 1 are secured. A minimum wall thickness is required.

The structure of the fixing jack 1 on the side of the fixing grip 4 is substantially the same as that of the conventional device, except that an engaging ring 16 for receiving and joining a part of the fixing grip 4 is fixed at the center thereof. The mating ring 16 has an annular recessed portion 17 for engaging the end of the female cone 4A and a circular opening 19 in which the male cone 4B is received and the press contact portion 18 of the center hole jack 5 can move. . still,
The structure of the center hole jack 5 is not different from the conventional one.

The opposite surface of the tension groove 2 of the tension jack 2 is a tapered surface 20, 20 whose interval decreases as approaching the fixing jack 1, and a pair of tension claws 9, 9 in the groove 8. 9 are arranged opposite to each other so that their inclined surfaces 21 and 21 are in sliding contact with the tapered surfaces 20 and 20, and a pressing portion 22 projecting from the thick end of each tensioning claw 9 in the tensioning direction of the strand 3 is attached to the tensioning jack. 2 from the main body. Then, the tension claws 9, 9 are
It is held so as not to fall off by 3 and 23 and can be moved along a guide hole 24 parallel to the tapered surface 20. Further, semi-circular holding grooves 25 are formed on the opposing surfaces of the tension claws 9, 9, and female screw-like irregularities are formed in the holding grooves 25 to prevent slipping on the strand 3. . The interval between the presser plates 23 is set to be wide enough for the strand 3 to pass through.
When the tension claws 9, 9 are pulled out from the main body most and the interval is widened, the width for inserting the strand 3 therebetween is ensured. Further, after the strand 3 is arranged between the holding grooves 25, 25 of the tension claws 9, 9, the tension claws 9, 9 are elastically urged by a coil spring or the like in a direction opposite to the tension direction of the strand. It is also preferable to hold them. The tension jack 2 has a handle 26 on the side opposite to the concave groove 8 for easy handling.
It is also preferable to fix or to be able to tilt or detach.

As shown in FIGS. 3 to 6, after the anchor plate 29 and the fixing grip 4 are inserted through the strand 3 led out from the reaction force receiving surface 28 of the concrete structure 27 or the like, the fixing jack 1 When the distal end of the strand 3 is inserted into the center hole 7 and mounted, before the tension is applied to the strand 3, the position of the fixing grip 4 becomes unstable with respect to the fixing jack 1. An annular band 31 of the holder 30 is fixed to the holding portion 30, and tips of a pair of bending arms 32, 32 extending from the annular band 31 are formed on opposite sides of the pressure receiving portions 6, 6 of the fixing jack 1. The engaging holes 33 are engaged with the fixing holes 33 so that the fixing grip 4 is maintained at an accurate position with respect to the fixing jack 1. The fixing grip 4 has a known structure in which a plurality of male cones 4B each having a tapered outer surface are inserted into a cylindrical female cone 4A having a tapered inner hole.

Next, a tensioning method for actually applying a tension to the strand 3 will be described mainly with reference to FIG. The tensioning method roughly includes a pre-preparation step, a setting step of attaching the tensioning device A to a predetermined position to connect the fixing jack 1 and the tensioning jack 2, and applying a tension to the strand 3 using the tensioning device A. Tensioning process and removal process.

First, in the preparatory step, the base end is fixed to the structure by a fixing grip or the like, and the strand 3 whose leading end is led out from the reaction force receiving surface 28 of the structure is cut leaving a predetermined margin length. This is a step of mounting the anchor plate 29 and the fixing grip 4 from the tip as usual.

Next, in the setting step, the fixing jack 1
The strand 3 is inserted from the end into the center hole 7 of the center hole jack 5 built in the center portion of the fixing hole 4, and the male cone 4B of the fixing grip 4 is received in the opening 19 of the engagement ring 16 and the female cone 4A is engaged with the engagement ring. After engaging with the annular concave portions 17 of the holder 16 and simultaneously attaching the bent arms 32, 32 of the holder 30 to the engagement holes 33, 33 (see FIG. 7A), the central portion of the tension jack 2 At the same time as receiving the strand 3 from the side into the groove 8 formed at the end of the fixing jack 1, the connecting projections 12, 12 provided at the distal ends of the piston rods 11, 11 of the cylinder jacks 10, 10 are connected. 13, the piston rods 11, 11 are linked to the pressure receiving portions 6, 6, and the strand 3 is positioned between the holding grooves 25, 25 of the pair of tensioning claws 9, 9. (See FIG. 7 (b)).

In the tensioning step, the tensioning claws 9, 9 are pushed in to clamp the strand 3, then the tensioning jack 2 is driven, and the fixing jack 1 is fixed by the piston rods 11, 11 of both cylinder jacks 10, 10. Pressure receiving part 6, 6
Is applied to apply tension to the strand 3 (see FIG. 7 (c)), and then the center hole jack 5 of the fixing jack 1 is driven to push the male cone 4B of the fixing grip 4 into the female cone 4A at the pressure contact portion 18. (See FIG. 7 (d)), and the tension jack 2
Then, the tensioning claws 9, 9 are loosened by pulling the piston rods 11, 11 so as to approach the fixing jack 1 (see FIG. 7 (e)).
After pressing the center hole jack (see FIG. 7 (f)), the pressing of the center hole jack 5 is released to return to the initial state, and these operations are repeated a predetermined number of times.

Finally, the removing step includes the fixing grip 4
With the strand 3 completely fixed, the tension jack 2 is removed to the side of the strand 3, the fixing jack 1 is pulled out in the tension direction, and the strand 3 protruding from the fixing grip 4 is cut short. is there.

In the tensioning device A according to the present embodiment, the tensioning jack 2 has a tension of 35 tonf, a stroke of 50 mm,
The fixing force of the fixing jack 1 is 3.5 tonf, the stroke is 15 mm, the device size in the tension direction is 239 mm, the weight of the tension jack 2 is about 26 kg, and the weight of the fixing jack 1 is about 15 kg. A conventional tensioning device having the same tension performance has a device size of about 500 mm and a weight of about 50 k.
g, whereas the tensioning device A of the present invention has a device size of less than half and the weight of the handling unit (about 26 kg for the heaviest tensioning jack 2) is about half, achieving compactness and light weight. I was able to do it. In addition, the conventional tensioning device requires extra space for the minimum device dimension from the end of the strand in order to attach it to the strand, and further adds a stroke for tensioning, so a space of at least about 1 m is required. is necessary. On the other hand, in the tensioning device A of the present invention, the fixing jack 1 and the tensioning jack 2 are separated, and only the fixing jack 1 is inserted from the tension direction of the strand, and the tensioning jack 2 is mounted from the side of the strand 3. The space required for the work may be very narrow, and the work can be performed in half the space of the conventional case even if the stroke of the tension jack 2 for the tension work is taken into consideration. By shortening the protruding length, the cutting length of the strand 3 after applying the tension is inevitably shortened, thereby saving resources. The tensioning device A of the present invention
In the PC bridge shown in FIG. 9 by using
Tension work can be performed even if there is little space on the side, so after installing the bridge girder directly on the pier, it is possible to tighten the PC steel wire and perform the horizontal tightening work, achieving a significant cost reduction . In addition, the work of pulling in the PC cable inside the bridge girder of the cable-stayed bridge shown in FIGS.
The burden on the worker can be greatly reduced.

As the above-described tensioning device A, two cylinder jacks 10, 1 in the tensioning jack 2 are used.
0, and two pressure receiving parts 6, 6 are provided in the fixing jack 1 correspondingly. However, in principle, three cylinder jacks 10,... Are built in the tension jack 2 at equal intervals. Then, the groove 8 is formed between the pair of cylinder jacks 10 and 10 as described above, and the fixing jack 1 is formed.
Also, by providing the three pressure receiving portions 6,..., The tension capacity can be increased by about 1.5 times while the device size in the tension direction is suppressed.

[0027]

According to the strand tensioning apparatus and the strand tensioning method of the present invention as described above, the following remarkable effects can be obtained.

According to the strand tensioning device of the first aspect, a center hole jack for fixing that presses the male cone of the fixing grip and allows the strand to be inserted into the center hole is built in the central portion, and a plurality of pressure receiving jacks are provided on the side portion. And a wedge-shaped tensioning claw for holding the strand in the groove and having a plurality of cylinder jacks built into the side. A state in which the strand is inserted into the center hole of the fixing jack, the strand is received in the concave groove of the tension jack, and the tip of the piston rod of each cylinder jack is linked to the pressure receiving section of the fixing jack. The size of the device in the direction of tension at the tension can be reduced, so that it can be attached to the strand in a narrow space and tightened. Working together is facilitated, since the fixing jack and tensioning jack can be handled in a state of being separated, respectively, it is possible to greatly reduce the burden on the operator.

According to the second aspect, in addition to the above-described effect that the fixing jack and the tension jack can be carried separately, the fixing jack and the tension jack can be integrally combined at the time of use.

According to the third aspect, the strand is reliably held at the initial stage of tension, play in the tension direction is eliminated, and the stroke of the tension jack can be used to the maximum, and the stroke of the tension jack is small. In other words, even if the device size in the tensioning direction is reduced, efficient tensioning work can be performed.

According to the fourth aspect, the size of the device in the tension direction can be greatly reduced.

Further, according to the strand tensioning method of the fifth aspect, mounting and tensioning work on the strand in a narrow space, which is difficult with the conventional tensioning device, is facilitated, and the fixing jack and the tensioning jack are used. Can be handled separately from each other, so that the burden on the operator can be greatly reduced. Further, when the strand tensioning method of the present invention is applied to a work for applying tension to a strand used for a PC steel material of a concrete structure such as a PC bridge or a PC cable such as a suspension bridge or a cable-stayed bridge, a concrete structure or a bridge may be used. And the like, so that the structure of the main body and the incidental works can be changed, and thus the possibility of significantly reducing the cost of building the main body is hidden.

[Brief description of the drawings]

FIG. 1 is a partial sectional view of a strand tensioning device of the present invention.

FIG. 2 is a side view similarly viewed from a tension direction.

FIG. 3 is a perspective view showing a state where a fixing jack and a tension jack are separated from each other.

FIG. 4 is a perspective view showing a state in which a fixing jack and a tension jack are combined and attached to a strand.

FIG. 5 is a perspective view showing a state where tension is applied to the strand.

FIG. 6 is an enlarged partial sectional view showing a relationship between a fixing grip and a fixing jack.

FIG. 7 is a simplified explanatory view for explaining the strand tensioning method of the present invention, wherein (a) shows a state in which a fixing jack is mounted on the strand, and (b) shows a state in which the fixing jack and the tension jack are combined and mounted on the strand. (C) is a state in which tension is applied by driving the tension jack, (d) is a state in which the fixing jack is driven and the strand is held by the fixing grip, and (e) is a state in which the tension jack is returned to the initial state. State,
(f) shows a state in which the strand is clamped by the tension claws of the tension jack.

FIG. 8 is an explanatory view showing a tensioning method using a conventional tensioning device, wherein (a) shows an initial state, (b) shows a tensioned state, (c) shows a fixed state, and (d) shows a removed state, respectively. .

FIG. 9 is an explanatory diagram showing a conventional construction method when a PC bridge is newly constructed by approaching between existing bridges on both sides.

FIG. 10 is a simplified explanatory view of a cable stayed bridge.

FIG. 11 is an explanatory diagram showing a state in which a PC cable is being pulled inside the bridge girder of the cable stayed bridge.

[Explanation of symbols]

A Tensioning device 1 Fixing jack 2 Tension jack 3 Strand 4 Fixing grip 4A Female cone 4B Male cone 5 Center hole jack 6 Pressure receiving part 7 Center hole 8 Depressed groove 9 Tension claw 10 Cylinder jack 11 Piston rod 12 Connecting protrusion 13 Connection groove 14 Projection 15 Concave part 16 Engagement ring 17 Annular concave part 18 Press-contact part 19 Opening part 20 Taper surface 21 Inclined surface 22 Pressing part 23 Holding plate 24 Guide hole 25 Holding groove 26 Handle 27 Concrete structure 28 Reaction force receiving surface 29 Anchor plate 30 Holding Tool 31 Ring zone 32 Bending arm 33 Engagement hole

Claims (5)

[Claims] 1. A tensioning device for tensioning a strand, wherein the tensioning force is applied to a strand by applying tension to the strand and maintaining a tensioned state with a fixing grip composed of a female cone and a male cone. A fixing center hole jack through which a strand can be inserted is built in the center, and a fixing jack having a plurality of pressure receiving sections on the side and a concave groove with one side open in the center and a concave groove are provided in the central groove. The fixing jack comprises a tension jack having a wedge-shaped tensioning claw for holding the strand, and a plurality of cylinder jacks on its side.The strand is inserted through the center hole of the fixing jack, and the strand is inserted into the groove of the tension jack. And the tip of the piston rod of each cylinder jack is linked to the pressure receiving section of the fixing jack. A strand tensioning device characterized in that the device dimension in the tensioning direction in the state is suppressed. 2. A connecting projection is provided at a tip end of each piston rod of the tensioning jack, and is connected to each pressure receiving portion of the fixing jack so as to be open to one side and the tensioning jack side to receive the connecting projection. 2. The strand tensioning device according to claim 1, wherein a groove is formed, and the connecting projection of each piston rod can be simultaneously engaged with the connecting groove of the fixing jack from a direction orthogonal to the direction of tension of the strand. 3. The opposing surface of the concave groove portion of the tension jack,
A tapered surface having a narrower interval as approaching the fixing jack, and a pair of tensioning claws are disposed in the concave groove portion so as to face each other so that the inclined surfaces thereof are in sliding contact with the tapered surface. 3. The strand tensioning device according to claim 1, wherein a pressing portion protruding from the portion in the tension direction of the strand is projected from the main body of the tension jack. 4. A central portion formed by retreating an end surface of each pressure receiving portion of the fixing jack from an end surface of a central portion having a built-in center hole jack on a side facing the fixing jack and the tension jack. 4. The strand tensioning device according to claim 1, wherein the projecting portion is receivable in a recess formed in an end face of a central portion of the tension jack. 5. A preparatory step for fixing an anchor plate and a fixing grip to a strand whose base end is fixed to a structure and whose distal end is led out from a reaction pressure receiving surface of the structure, in a usual manner; A fixing jack having a built-in center hole jack and having a plurality of pressure-receiving parts on the sides was inserted by inserting the strand from the end into the center hole of the center hole jack, and then one side was opened to the center. A tension jack having a concave groove portion and having a wedge-shaped tensioning claw for holding the strand in the concave groove portion, and a tension jack having a plurality of cylinder jacks built in a side portion is inserted into the groove portion from the side of the strand. A setting step of receiving and mounting the piston rod tips of both cylinder jacks in association with the pressure receiving sections of the fixing jack, and pressing the tension claw. After holding the strand, the tension jack is driven, the piston rod of each cylinder jack presses the pressure receiving part of the fixing jack to apply tension to the strand, and then the center hole jack of the fixing jack is driven to fix the grip. After the male cone is pushed into the female cone to fix the strand, the piston rods of the tension jack are pulled in, the tension claws are loosened to approach the fixing jack, and the tension claws are pushed again to clamp the strand. A tensioning step of releasing the pressing of the hole jack to return to an initial state and repeating these operations a predetermined number of times.