JP4311748B2 - Tension material fixing device and tension material fixing method - Google Patents

Description

  The present invention fixes a tension material for introducing prestress to a structure formed of concrete or the like, a tension material fixing tool for fixing the tension material to the structure in a state where a tensile force is introduced, and the tension material to the structure. Regarding the method.

The tension material fixing tool used when fixing the tension material for introducing pre-stress to the structure is fixed by screwing a nut to the tension material threaded at the end, and the tension material It is generally known that it is fixed by a wedge that is pressed against the surface. Among these, several proposals have been made for the tension member fixing device fixed by the nut as described in Patent Document 1 and Patent Document 2, for example, but the basic configuration is as shown in FIG. It has a nut 102 and a bearing plate 103. That is, a nut 102 that is screwed into a threaded portion 101 a provided on the end of the tension material 101 and a pressure plate 103 that has a through hole through which the tension material 101 is inserted are screwed into the tension material 101. The nut 102 is locked to the pressure bearing plate 103.
When the tension member 101 is fixed to the concrete structure 100 with such a fixing tool in a state where the tensile force is introduced, the tensile force of the tension member 101 acts on the bearing plate 103 via the nut 102, and this bearing plate. 103 is transmitted as a compressive force into the concrete structure 100.

The tension work and the fixing work when the fixing tool is used are performed as follows.
A tension rod 104 is connected to the tip of the tension material 101 as shown in FIG. 21, and a ram chair 105 and a center hole jack 106 are attached to the tension rod 104. Then, the tension rod 104 is locked to the rear end portion of the center hole jack 106. The structure in which the tension rod 104 is locked to the center hole jack 106 uses a nut 107 and a bearing plate 108 screwed to the rear end portion of the tension rod 104 to fix the tension material 101 to the concrete structure 100. The same structure can be adopted. Instead of the tension rod 104, an extension steel rod is connected to the tip of the tension member 101 via a coupler, and the rear end of the extension steel rod is locked to the rear portion of the center hole jack. Also good.

When the tension rod 104 connected to the tension material 101 is locked to the rear end portion of the center hole jack 106, the center hole jack 106 is driven and a reaction force is applied to the concrete structure 100 via the bearing plate 103. Thus, a tensile force is applied so as to pull out the tendon material 101 from the concrete structure. Then, as the tendon material 101 is pulled out from the concrete structure 100, the nut 102 is rotated and tightened from the side of the ram chair 105. When the nut 102 is tightened in this way, the driving of the center hole jack 106 is stopped, the pulling of the tension rod 104 is released, and the nut 102 is locked to the bearing plate 103. Thereby, the tension material 101 is fixed in a state where the tensile force is introduced, and the reaction force of the tension material 101 acts on the concrete structure 100 to introduce prestress (compression force) to the concrete structure.
JP-A-48-91830 Japanese Patent Laid-Open No. 3-208965

However, there are the following problems in the conventional tension material fixing device as described above.
As shown in FIG. 22, the fixing end portion of the tension member into which the tension force is introduced includes the thickness of the bearing plate 103, the thickness of the washer, the thickness of the nut 102, and the tip of the tension member 101 from the surface of the concrete structure 100. The part protrudes. At the end of the tensioning material 101, the end of the tensioning material 101 protrudes from the rear end of the nut by the length of the tensioning material due to the introduction of the connection surplus length for connecting the tensioning rod 104 and the tensile force. This protrusion length can be cut after fixing, leaving a surplus length necessary for securely locking the nut 102, but the protrusion length including the thickness of the bearing plate 103 and the thickness of the nut 102 is large. Become. For this reason, when it is going to cover and protect these with concrete for rust prevention, the layer thickness of protective concrete must be enlarged.

  In order to solve such problems, a notch called so-called boxing is provided, and the tension material is fixed in the notch, but many man-hours are required for processing the formwork and rebar. Is necessary and not economical. In addition, in the corners where the two-direction tension members must be fixed, the fixing members for the tension members interfere with each other, and the arrangement becomes difficult.

On the other hand, the conventional tendon fixing device has the following other problems.
The diameter of the tendon is smaller than the diameter of the sheath hole provided in the concrete structure 100, and before the tension, the tendon is biased from the position (planning center line) that should be placed in the design. Sometimes. In particular, when the tendon is arranged in a horizontal or nearly horizontal direction, the tendon is inscribed in the lower surface in the sheath by its own weight, and the amount of eccentricity is large. Therefore, when tension is required, it is necessary to adjust the center line of the tension material, etc., and this work drives the jack while manually supporting the tension material, the ram chair 105, the jack, etc. in a predetermined position, and introduces tensile force to the tension material. Will do. Such work is not only inefficient, but also dangerous. In addition, it is difficult to strictly adjust the center line of the tendon and the fixing tool, and in the case of a thin plate-like member, if the position of the tendon is not arranged at the predetermined planned center, the stress distribution introduced into the concrete structure May cause unevenness and cracks.

There are also the following problems.
After the tensile force is introduced into the tendon, in order to integrate the tendon and the concrete structure 100, grout is injected into the sheath through the injection hole 103a provided in the bearing plate as shown in FIG. However, as shown in FIG. 23, in the conventional tension material fixing tool, a gap is formed between the tension material 101 in the through hole of the pressure bearing plate 103, and air remains and fills the grout when the grout is injected. It becomes difficult to be done. In particular, when the tendon is arranged in the vertical direction or a direction close thereto, the grout is hardly filled in the fixing tool on the upper end side. For this reason, it may become a residual space without being filled with grout, causing moisture to permeate and deteriorating the tendon.

  The invention according to the present application has been made in view of the above-described problems, and the purpose thereof is to shorten the length of the fixing tool and the like protruding from the surface of the structure on which the tension material is fixed, In addition to facilitating the placement and covering of the fixing tool, it is possible to accurately set the center of the tendon and the fixing tool at predetermined positions.

  In order to solve the above-mentioned problem, the invention according to claim 1 is attached to the end of the tendon, and fixes the tendon so that the reaction force of the tensile force introduced into the tendon is transmitted to the structure. A tension member fixing tool that has a through-hole through which the tension member is inserted and is disposed in contact with the structure, and a screw portion formed at an end portion of the tension member on the inner side. A long nut having a thread formed on the outer peripheral surface thereof, and is screwed to the outer peripheral surface of the long nut and is locked to the bearing plate to transmit the tensile force of the tension material to the bearing plate. A fixing nut, and an inner peripheral surface of a through hole provided in the bearing plate so that a cross-section is reduced in a direction in which the tension material extends from an end side where the tension material is fixed. The fixing nut is inclined with respect to the axis of the tension material, and the fixing nut has an outer peripheral surface inclined to an inner peripheral surface of the through hole. Inclined to respond, providing tendon fixing device is intended to be locked to the wedge in the through hole.

In such a fixing tool, the end portion of the tension material is screwed and connected to the inside of the long nut, and the fixing nut is screwed onto the outer peripheral surface of the long nut. Then, this fixing nut is fitted into a through hole provided in the bearing plate, and the outer peripheral surface of the fixing nut is in close contact with the inner peripheral surface of the through hole inclined and locked like a wedge. Accordingly, the tensile force of the tendon acts on the bearing plate via the long nut and the fixing nut, and is transmitted from the back surface (bearing surface) of the bearing plate to the structure.
With the tension material fixed in this manner, the fixing nut is fitted in a wedge shape in a through-hole provided in the bearing plate so that the amount of the fixing nut protruding from the surface of the bearing plate is kept small. Can do. Further, since the tendon is screwed into the long nut and the long nut is screwed into the fixing nut, the long nut and the tendon can be fixed without protruding from the fixing nut. Therefore, the amount of protrusion of the fixing tool and the end of the tendon material from the surface of the structure can be greatly reduced as compared with the conventional fixing tool that fixes the nut having a flat end surface in contact with the surface of the flat bearing plate. It becomes possible.

  In addition, the tension member, the long nut and the fixing nut are screwed together, and the fixing nut is fitted into the through hole of the bearing plate in a wedge shape. If it is arranged at the position, the tendon member and the fixing tool are fixed in a state of being exactly aligned with the center of the through hole of the bearing plate.

  On the other hand, when a tensile force is introduced into the tension member by a jack, an extension steel material is screwed into the long nut from the end surface opposite to the end surface into which the tension material is screwed, and a jack is attached to the extension steel material. A tensile force can be introduced into the tendon via That is, a long nut can be used as a connection tool between a tension material and an extended steel material. As the tension material stretches and the tension material is pulled out from the end face of the structure, the fixing nut is screwed into the through-hole of the bearing plate, and the fixing nut is installed in the state where the predetermined tensile force is introduced. Can be locked to. After the predetermined tension is introduced, the jack can be removed and the extended steel can be extracted from the long nut, so that the tension does not protrude from the long nut.

  In addition, the tension material for introducing pre-stress to the structure to be added later can be screwed and connected to the long nut after fixing the tension material to the concrete structure and extracting the extended steel material. . A tension force can be similarly introduced into the tension material at the other end.

  The invention according to claim 2 is the tension material fixing tool according to claim 1, wherein the fixing nut is formed with a tool engaging portion for rotating around an axis line on an outer peripheral portion on an end side of the tension material. When the fixing nut is mounted in the through hole of the bearing plate, the tool engaging portion protrudes from the surface of the bearing plate toward the end of the tendon material, and the wedge-shaped portion whose outer peripheral surface is inclined is The bearing surface and the tip of the bearing plate that are in contact with the structure are positioned substantially on the same plane, or the tip protrudes or retracts slightly from the bearing surface.

By forming the tool engaging portion, the fixing nut can be easily rotated in a state where a tensile force is introduced to the tension member via the extended steel material and the long nut. And since the tool engaging part protrudes from the surface of the bearing plate, the fixing nut can be pushed into the through hole of the bearing plate strongly. Thereafter, when the tensile force acting on the tension material is released from the extended steel material, the fixing nut is locked to the bearing plate without causing any looseness in the tension material, and the reaction force of the tensile force acts on the structure.
In addition, since the tip of the wedge-shaped portion is substantially the same as the back surface of the bearing plate, the peripheral surface of the wedge-shaped portion can be brought into contact with a wide range of the inner peripheral surface of the through hole. In addition, the diameter of the outer peripheral surface of the fixing nut and the diameter of the through hole of the bearing plate can be reduced, and sufficient strength of the bearing plate can be ensured and the structure can be brought into contact with a large area.
In the above invention, the state where the tip of the wedge-shaped portion slightly protrudes from the back surface of the bearing plate means that it is difficult to fill the grout between the fixing nut and the sheath because the tip projects from the back surface of the bearing plate. The amount of protrusion is suppressed to such an extent that it does not become. Further, the state in which the tip of the wedge-shaped portion is slightly retracted from the back surface of the bearing plate is such that the grout filling in the concave portion formed in the through hole does not become difficult.

  The invention according to claim 3 is the tension material fixing device according to claim 1 or 2, wherein a protection bolt is screwed into the long nut from a side opposite to the side where the tension material is screwed. It is assumed that the rear end surface of the bolt is the same as the end surface of the long nut or is screwed into the back from the end surface of the long nut.

In the state in which the tendon is fixed, the inner hollow portion is open on the end surface of the long nut opposite to the side on which the tendon is screwed. This portion can be used to screw the extended steel material when the tensile force is introduced, but it becomes difficult to reuse the foreign material or the like after the extended steel material is removed.
However, since the protective bolt is screwed in, it is possible to prevent foreign matter from entering the inside of the long nut and damage to the screw thread. In particular, after introducing a tensile force to the tendon and covering the tendon fixator with concrete or the like to complete the structure, when further extending the tendon by extending the structure, etc., pull out the protective bolt, Other tendons can be connected inside the long nut. Then, it is possible to introduce press stress to the structure that has been extended by introducing a tensile force at the other end.

  The invention according to claim 4 is the tension material fixing device according to claim 1, 2 or 3, and penetrates from the surface to the back side which becomes the bearing surface in the peripheral portion of the through hole of the bearing plate. It has a grouting hole, and the opening on the back side is provided inside the sheath that is joined to the bearing plate and through which the tension material is inserted.

  The grout hole as described above can be formed in the bearing plate by simple processing. And the length of a grout hole can be shortened and grout can be inject | poured smoothly. Further, by providing a plurality of grout holes around the through-holes, it is possible to secure an air discharge port at the time of grout injection regardless of the direction in which the bearing plate is arranged.

  The invention according to claim 5 is a method of fixing the tension material to the structure body such that a reaction force of the tensile force introduced into the tension material is transmitted to the structure body via the bearing plate. A step of disposing the tension member and the bearing plate at a predetermined position of the structure; and an inner side of a long nut in which a thread is formed on both the inner peripheral surface and the outer peripheral surface; A step of screwing the formed screw portion; and an extension steel material is inserted into a through-hole provided in the bearing plate, and the screw portion formed at an end portion of the extension steel material is inserted from the side opposite to the tension material to the length. A step of connecting the tension member and the extension steel member by screwing into the inside of the nut; and a fixing nut having an outer peripheral surface inclined in a wedge shape and fitted in the through hole of the bearing plate. A step of screwing with a screw thread on the outer peripheral portion, and attaching a center hole jack to the extended steel material, A step of pulling the extension steel material by applying a reaction force to the pressure plate to introduce tension to the tension material; a predetermined tensile force is introduced to the tension material; and the fixing nut is rotated to penetrate the pressure bearing plate Tightening in the hole, bringing the inclined outer peripheral surface of the fixing nut into contact with the inner peripheral surface of the corresponding through hole, and releasing the traction force by the center hole jack; And a tension material fixing method including a step of removing the extended steel material.

In this method, even if the tension material is cut in consideration of the amount of elongation when a predetermined tensile force is introduced and the end surface is placed in the structure side from the fixing surface of the structure, it is joined with a long nut. Tensile force can be introduced using the extended steel material. When the tension material is elongated due to the introduction of the tensile force, a fixing nut screwed into the long nut is used, and the tension material is not protruded from the fixing nut to the tension end side. Can be fixed. Further, since the fixing nut is fitted in the through hole of the bearing plate and is locked in a wedge shape, the amount of the nut protruding from the bearing plate can be reduced.
In addition, in the state where the tension material is fixed, the centers of the tension material, the long nut, the fixing nut and the through hole of the bearing plate coincide with each other. Therefore, by placing the bearing plate accurately at a predetermined position of the structure, The material can be placed accurately without being eccentric in the sheath.

  The invention according to claim 6 is the tension material fixing method according to claim 5, wherein the step of screwing the fixing nut into the long nut includes a guide nut to which the fixing nut can be screwed on the outside, and the extension. Screwed into the threaded part of the steel material, screwed into the fixing nut to the thread formed on the outer peripheral surface of the guide nut, and rotated through the fixing nut or guide nut to penetrate the support pressure plate. The fixing nut is fitted into the hole, and then the fixing nut is screwed onto the long nut in a state where a tensile force is introduced into the tension material.

  When a jack is attached to the extended steel material and a reaction force is applied to the structure to introduce a tensile force to the tension material, the jack is strongly pressed against the structure and the position of the tension material and the center position of the tension material cannot be moved. However, before the tensile force is introduced to the tension member as described above, the fixing nut is screwed to the outside of the guide nut screwed to the tension member, and this fixing nut is fitted into the through hole of the bearing plate. By setting it as the state, the center of the through-hole provided in the tension material, the long nut, the fixing nut, and the bearing plate matches. Therefore, by operating the jack in this state and introducing the tension force, the tension material is introduced and fixed at the correct position.

The invention according to claim 7 is a tension material fixing device that is attached to an end portion of the tension material and fixes the tension material so that a reaction force of a tensile force introduced into the tension material is transmitted to the structure. A pressure bearing plate that is provided in contact with the structure and has a through hole through which the tension material is inserted; and a screw portion that is formed at an end of the tension material; A nut that is locked and transmits the tensile force of the tension member to the bearing plate, and the inner peripheral surface of the through hole provided in the bearing plate extends from the end side of the tension member. The nut is inclined with respect to the axis of the tendon so that the cross-section is reduced in the direction of the direction, the outer peripheral surface of the nut is inclined corresponding to the inner peripheral surface of the through-hole, is intended to be engaged in Dekusabi shape, on the end side of the tension member, a tool engagement portion for rotating about the axis are formed The nut when mounted on the through hole of the bearing capacity plate, the tool engagement portion is to provide a tendon fixing device is intended to protrude from the surface of the Bearing plate.

In this tendon fixing device, a nut screwed to the tendon is fitted into a through hole provided in the bearing plate and is locked in a wedge shape. Therefore, the amount of the nut protruding from the surface of the bearing surface when a predetermined tensile force is introduced and fixed to the tendon can be kept small.
Further, by fitting the nut screwed to the tension member into the through hole of the bearing plate, the center of the tension member and the center of the through hole provided in the bearing plate can be accurately matched. Therefore, if the bearing plate is correctly placed at a predetermined position, before the tensile force is introduced to the tendon, the tendon is placed at the correct position, and the tensile force is introduced and fixed in this state. Can do.

  Further, since the tool engaging portion is formed on the nut and protrudes from the surface of the bearing plate, the nut can be rotated and can be firmly fitted into the through hole of the bearing plate. Therefore, it is possible to fix the tension material in a state where a predetermined tensile force is introduced without causing the tension material to loosen at the time of fixing.

  As described above, in the tension material fixing tool of the present invention, the length of the fixing tool and the like protruding from the bearing surface of the structure can be shortened, and the arrangement of the tension material fixing tool is facilitated, and the fixing tool The thickness of the protective layer covering the film can be reduced. In addition, the center of the tension member and the center of the through hole provided in the bearing plate can be accurately aligned and fixed, and by placing the bearing plate at a predetermined position, the tension member can be accurately fixed. It can be fixed at any position.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view showing a tendon fixing device that is an embodiment of the invention according to the present application.
This tension material fixing tool introduces prestress to the concrete structure 10 using the tension material 11, and includes a long nut 12 having threads formed on the inner peripheral surface and the outer peripheral surface, and a screw on the inner peripheral surface. A crest is formed, and the outer peripheral surface is provided with a fixing nut 13 whose cross section is reduced in the axial direction to form a conical wedge, and a through hole 14a is provided in the center, and the inner peripheral surface of the through hole is the outer peripheral surface of the fixing nut 13. Correspondingly inclined bearing plate 14 is provided. Then, the thread portion 11a at the end of the tendon is screwed into the long nut 12, and the thread 12a provided on the outer peripheral surface of the long nut 12 is screwed into the fixing nut 13. The outer peripheral surface of the fixing nut 13 is supported by the support nut. It is inserted into a through hole provided in the pressure plate 14 and is locked in a wedge shape. The tensile force of the tension member 11 is transmitted to the bearing plate 14 via the long nut 12 and the fixing nut 13, and further acts on the concrete structure 10 from the contact surface between the concrete structure 10 and the bearing plate 14, thereby prestressing. Is to be introduced.

As the tension member 11, a PC steel rod is generally used, and a threaded portion 11a is formed at an end portion thereof, so that it can be screwed into the inside of the long nut 12 up to about half the length of the long nut 12. It has become. The tendon 11 is inserted and disposed in a sheath 15 embedded in the concrete structure 10, and the cross section of the sheath 15 is expanded near the surface of the concrete structure 10.
The tension material 11 can be a PC steel wire, a PC steel wire, a rod in which an aramid fiber or the like is hardened with a resin rod in addition to a PC steel rod, but can be threaded at the end. A cylindrical member made of steel is connected by crimping or a wedge, or the cylindrical member is fixed to a tendon with an adhesive, mortar, molten metal, or the like.

  As shown in FIG. 2, the long nut 12 is a metallic cylindrical member in which threads are precisely formed on the inner peripheral surface and the outer peripheral surface. And the thread part 11a of the edge part of the tension | tensile_strength material 11 is screwed in from one edge part of the long nut 12, and the extension steel material 16 (shown in FIG. 5) for tension | tensile_strength introduction is screwed in from the other side. Yes. At this time, the long nut is assumed to have a sufficient length in the axial direction so that the tensile force is transmitted from the extended steel material 16 to the tension material 11. The thread 12a provided on the outer peripheral surface of the long nut 12 is screwed with the fixing nut 13, and is provided in a range sufficient to transmit the tensile force introduced into the tension member 11. ing.

  A small through hole is provided in the central portion in the axial direction of the long nut 12 in a direction perpendicular to the axial line, and a pin 12b is inserted and fixed. By screwing the tension member 11 and the extension steel member 16 screwed from both ends until the respective ends of the tension member 11 abut against the pin 12b, the tensile force is reliably transmitted from the extension steel member 16 to the long nut 12 and further to the tension member 11. A sufficient screwing length is secured.

As shown in FIG. 3, the fixing nut 13 is a metallic cylindrical member, and has a thread formed on the inner peripheral surface. Then, it is screwed with a thread 12 a provided on the outer peripheral surface of the long nut 12.
The outer periphery of the fixing nut is composed of a wedge-shaped portion 13a and a tool engaging portion 13b. The cross-sectional shape of the outer peripheral surface of the wedge-shaped portion 13a is circular, but the cross-section is reduced in the direction of the tip side, that is, the direction in which the tendon material extends into the structure. Thereby, it fits in the through-hole of the bearing plate 14, and is locked in a wedge shape. The length of the wedge-shaped portion 13a in the axial direction is set to be substantially the same as the thickness of the pressure bearing plate 14 described below. That is, when fitted into the through hole of the pressure bearing plate 14, it is pressed against the entire inner peripheral surface of the through hole 14a and is locked without causing stress concentration. The diameter of the outer peripheral surface is set as small as possible within a range having sufficient strength and rigidity, and is set so that the inner diameter of the through hole 14a does not become excessive.

  On the other hand, the tool engaging portion 13b is provided continuously behind the wedge-shaped portion 13a, and is flattened, for example, by cutting a polygonal part or a circular part so that a tool for rotating the fixing nut 13 can be engaged. The cross-sectional shape is as described above, and has a length necessary for engagement in the axial direction. The tool engaging portion 13b is formed inside the extended surface of the conical curved surface forming the wedge-shaped portion 13a so as not to engage with the flat surface of the bearing plate 14.

As shown in FIG. 4, the support plate 14 is a circular or polygonal metal plate and has a through hole 14 a at the center. The inner peripheral surface of the through-hole 14a is inclined with respect to the axis of the tension material so that the cross-section is reduced in the direction in which the tension material 11 extends. It corresponds to the outer peripheral surface of 13a. Therefore, the fixing nut 13 can be locked in a wedge shape with the outer peripheral surface and the inner peripheral surface of the through hole 14a being in close contact with each other in a state of being fitted into the through hole 14a.
A plurality of grout injection holes 14 b are provided in the periphery of the through hole of the bearing plate 14. The grout injection hole 14b penetrates from the surface of the bearing plate 14 to the back surface of the bearing plate 14, that is, the bearing surface contacting the concrete structure 10, and opens to the enlarged diameter portion 15b of the sheath 15 on the bearing surface side.

  In the concrete structure 10, a sheath 15 in which the tension material 11 is arranged is embedded. The inner end of the sheath 15 is enlarged so that the long nut 2 can be accommodated. The length of the sheath expanded diameter portion 15a is determined by the amount by which the long nut 12 threadedly engaged with the end portion of the tension member 11 is pulled out by the introduction of the tensile force, that is, the extension amount of the tension member. That is, the long nut 12 is disposed in a deep position in the sheath enlarged diameter portion 15a in advance, and extends to a position where the long nut 12 is locked to the bearing plate 14 via the fixing nut 13 when a predetermined tensile force is introduced. The tendon 11 and the long nut 12 are arranged so that the above occurs.

Next, a method for fixing the tension material 11 by introducing a tensile force using the tension material fixing tool will be described.
First, as shown in FIG. 5, the tendon material 11 and the bearing plate 14 are installed at predetermined positions of the concrete structure 10. The bearing plate 14 may be embedded in the concrete structure 10 in advance, or may be in contact with and supported by the surface of the concrete structure 10. The bearing plate 14 is arranged so that the center of the through hole 14a exactly coincides with the center line where the tendon material 11 is to be arranged. The tendon 11 is cut to a length that takes into account the amount of elongation when a predetermined tensile force is introduced, and the end face is located in the sheath 15 on the structure side of the bearing plate 14. A long nut 12 is screwed into a threaded portion 11 a provided at the end of the tension member 11, and the tension member 11 is screwed to about half the length of the long nut 12 in the axial direction. And the extension steel material 16 is screwed in the other side of the long nut 12, and the tension material 11 and the extension steel material 16 are connected. At this time, a guide nut 18 is screwed into the extended steel material 16 in advance, and a fixing nut 13 is screwed into the outside of the guide nut 18 in advance. The guide nut 18 has the same inner diameter and outer diameter as the long nut 12 and is threaded on both the inner peripheral surface and the outer peripheral surface in the same manner as the long nut 12.

  The guide nut 18 or the fixing nut 13 screwed to the tension member 11 is rotated as described above, and the fixing nut 13 and the guide nut 18 are screwed together while maintaining the state where the fixing nut 13 and the guide nut 18 are screwed as shown in FIG. 13 is fitted into the through hole 14a of the bearing plate 14. As a result, the center line of the tendon 11 exactly matches the center of the through hole 14 a provided in the bearing plate 14.

  Next, as shown in FIG. 6, a center hole jack 17 is attached to the extension steel material 16, and the extension steel material 16 is locked to the rear part of the center hole jack 17. The extension steel material 16 can be locked to the center hole jack 17 by, for example, screwing a nut 19 into a threaded portion formed at the rear end portion of the extension steel material 16. A ram chair 20 is inserted between the center hole jack 17 and the concrete structure 10, and the ram chair 20 is brought into contact with the pressure plate 14.

Thereafter, the center hole jack 17 is hydraulically operated to push the extended steel material 16 backward. As a result, a tensile force is introduced into the tendon 11 via the long nut 12, and the reaction force acts on the concrete structure 10 from the center hole jack 17 via the ram chair 20. By the reaction force acting, the positions of the ram chair 20 and the center hole jack 17 are fixed, and the center position of the tension member 11 is also fixed.
When a tensile force is introduced into the tension member 11, the tension member 11 is stretched as shown in FIG. 7, and the long nut 12 is gradually pulled out into the through hole 14 a of the bearing plate 14. In this state, the fixing nut 13 is rotated and screwed with the thread 12 a on the outer peripheral surface of the long nut 12. At this time, since the guide nut 18 rotates only the fixing nut 13 while being screwed to the extended steel material 16, the screwing between the guide nut 18 and the fixing nut 13 is released.
Since the fixing nut 13 and the long nut 12 have the same center line, they can be easily screwed together.

  If the guide nut 18 is not used, the positions of the tension member 11 and the extended steel member 16 are not fixed as shown in FIG. 11, and the position is fixed in an eccentric state when a tensile force is introduced by operating the jack. May be. If the positions of the tension member and the extension steel member are fixed in such an eccentric state, the long nut 12 and the bearing plate 14 interfere with each other, and it becomes impossible to introduce a tensile force to the tension member 11, or the fixing nut 13 and the long nut. The screwing with 12 becomes difficult. However, when the length of the tension member 11 is short and the amount of elongation is small, a part of the long nut 12 may be disposed in a state of being inserted into the through hole of the bearing plate 14. The fixing nut 13 can be screwed onto the long nut 12 before the tensile force is introduced into the material 11. Thereby, since the center position of the tendon 11 coincides with the center of the through hole 14a, it is not necessary to use the guide nut 18.

  After the tensioning material 11 is started to be tensioned and the position of the tensioning material 11 is fixed, the fixing nut 13 is rotated while further increasing the tensile force by operating the center hole jack 17 so that the fixing nut 13 is moved to the long nut 12. Screw it deeply into. The fixing nut 12 can be rotated by engaging a tool with the tool engaging portion 13 b of the fixing nut 13 from the side of the ram chair 20. When a predetermined tensile force is introduced into the tension member 11, the fixing nut 13 is fitted into the through hole 14 a of the bearing plate as shown in FIG. 8, and the wedge-shaped portion 13 a formed on the outer peripheral surface of the fixing nut 13 passes therethrough. The fixing nut 13 is strongly tightened until it is strongly pressed against the inner peripheral surface of the hole 14a.

  Thereafter, when the tensile force of the extension steel member 16 by the center hole jack 17 is released, the tensile force of the tension member 11 acts on the bearing plate 14 from the long nut 12 through the fixing nut 13. It is pressed against the bearing surface. Thereby, a compressive force acts on the concrete structure 10 and prestress is introduced.

After fixing the tension material, the center hole jack 17, the ram chair 20, the guide nut 18 and the extension steel material 16 are removed, and as shown in FIG. 9, the extension steel material 16 of the long nut 12 is screwed into the hollow portion. Screw in the protective bolt 21. Further, grout is press-fitted from the injection tube 22 connected to the grout injection hole 14b, and the space in the sheath 15 is filled. At that time, the fixing nut 13 is locked in close contact with the through hole 14b of the bearing plate, and since the tip is substantially flush with the back surface of the bearing plate, there is no space where the grout is difficult to enter, and the grout is completely Injected.
Then, as shown in FIG. 10, protective concrete 23 is placed so as to cover the bearing plate 14 and the tension material fixing tool.

  When the tension member 11 is fixed as described above, the length of the tension member 11 or the tension member fixing tool projecting from the bearing surface of the concrete structure 10 is only the tool engaging portion 13b of the fixing nut 13, which is conventionally known. The projecting length can be shortened compared to. Therefore, the tension member 11 and its fixing tool can be easily arranged, and the thickness of the protective concrete 23 covering the fixing tool can be reduced.

  Moreover, in the concrete structure 10 using this tension material fixing tool, once the construction of the concrete structure is completed, when it is necessary to add the concrete structure, the protective concrete 23 shown in FIG. 10 is removed. After that, the tension material extending into the long nut 12 can be screwed by removing the protective bolt 21. Therefore, it is not necessary to newly arrange a tensioning material fixing tool arranged in the additional portion, and it is possible to introduce prestress so that the compressive force acts on the boundary portion with the existing concrete structure 10 as well. It becomes.

FIG. 12: is a schematic sectional drawing which shows the tension material fixing tool which is other embodiment of the invention which concerns on this application.
This tension material fixing tool is provided with a wedge-shaped nut 32 having an outer peripheral surface of a conical curved surface, and a through hole provided in the center, and an inner peripheral surface thereof inclined corresponding to the outer peripheral surface of the nut 32. And a pressure plate 33. The threaded portion 31 a at the end of the tendon 31 is screwed into the nut 32, and the outer peripheral surface of the nut 32 is locked in a wedge shape within the through hole of the pressure bearing plate 33. The tensile force of the tension member 31 is transmitted to the bearing plate 33 via the nut 32 and further transmitted to the bearing surface of the concrete structure 10 to introduce prestress.

  As the tensioning material 31 fixed by the tensioning material fixing tool, a PC steel rod is generally used as in the fixing tools shown in FIGS. 1 to 4, but a threaded portion is formed at the end, and a nut is used. Any tensioning material that can be locked can be used.

  As shown in FIG. 13, the nut 32 is made of metal, and has a thread formed precisely on the inner peripheral surface thereof to be screwed with the tension material 31. The outer peripheral portion includes a wedge-shaped portion 32a having an outer peripheral surface inclined like a wedge, and a tool engaging portion 32b for rotating the nut around the axis.

  The wedge-shaped portion 32a has a circular cross-sectional shape on the outer peripheral surface, and the cross-section is reduced in the direction in which the tension material extends into the structure from the distal end side of the tension material to be fixed. Thereby, it fits in the through-hole of the bearing plate 33, and is locked in a wedge shape. The length of the wedge-shaped portion 32a in the axial direction is larger than the thickness of the following pressure-bearing plate 33. When the wedge-shaped portion 32a is fitted into the through-hole of the pressure-bearing plate 33, the rear end of the wedge-shaped portion 32a, that is, the end face side of the tension material It almost coincides with the surface of the pressure plate 33, and the front end protrudes toward the structure side from the back surface of the pressure support plate 33, that is, the pressure support surface in contact with the structure.

  On the other hand, the tool engaging portion 32b is provided continuously behind the wedge-shaped portion 32a, and is flattened by cutting a part of a polygon or a circle, for example, so that a tool for rotating the nut 32 can be engaged. The cross-sectional shape has a length necessary for engagement in the axial direction. The tool engaging portion 32b is formed inside the extended surface of the conical curved surface that forms the wedge-shaped portion 32a, and does not engage with the flat surface of the bearing plate 33.

As shown in FIG. 14, the bearing plate 33 is a circular or polygonal metal plate and has a through hole 33a in the center. The inner peripheral surface of the through-hole 33 a is reduced in cross section in the direction in which the tendon 31 extends, and is inclined with respect to the axis of the tendon 31. This inclination angle corresponds to the inclination angle of the outer peripheral surface of the wedge-shaped portion 32a of the nut 32. When the nut 32 is fitted into the through-hole 33a, the outer peripheral surface of the wedge-shaped portion 32a is the inner periphery of the through-hole 33a. It is in close contact with the surface and is locked in a wedge shape.
The bearing plate 33 is provided with a plurality of grout injection holes 33b. The grout injection hole 33 b penetrates from the periphery of the through hole 33 a on the surface of the bearing plate 33 to the periphery of the through hole on the back side of the bearing plate 33 and communicates with the inside of the sheath 34.

Next, a method for introducing and fixing a tensile force to the tendon 1 using the tendon fixer will be described.
First, the tendon 31 and the bearing plate 33 are arranged at predetermined positions of the concrete structure 10. The bearing plate 33 may be in contact with the surface of the concrete structure 10 or may be embedded in the concrete structure 10 as shown in FIG. The bearing plate 33 is arranged accurately with the center of the through-hole 33a aligned with the center line on which the tendon 31 is to be arranged.
The tendon 31 is inserted into the sheath 34 embedded in the concrete structure 10, the end 31a to be fixed is inserted from the inside of the concrete structure 10 into the through hole of the bearing plate 33, and the end 31a is the concrete structure. The length is set so as to protrude from. The end 31a protruding from the through hole 33a of the bearing plate 33 is provided with a screw portion, and the nut 32 is screwed into the screw portion. The nut 32 is screwed to a position where the nut 32 is fitted in the through hole of the bearing plate 33 to fix the position of the tension member 31. Thereby, the nut 32 is locked at a predetermined position along the inner peripheral surface of the through hole 33a, and the center line of the nut 32, that is, the center line of the tension member 31 coincides with the center of the through hole 33a. It is located on a predetermined planned center line.

  Further, a tension rod 35 having a female screw portion formed at one end is screwed into and connected to the end portion of the tension member 31, and a ram chair 36 and a center hole jack 37 are attached to the tension rod 35. Then, the tension rod 35 is locked to the rear portion of the center hole jack 8 by the nut 38.

  Thereafter, as shown in FIG. 16, the center hole jack 37 is hydraulically operated to push the tension rod 35 backward. As a result, a tensile force is introduced into the tendon 31, the tendon 31 is stretched, and the nut 32 is gradually pulled out to the jack side. The nut 32 is rotated and screwed to the bearing plate 33 side, and when a predetermined tension force is introduced into the tension member 31, the tool is engaged with the tool engaging portion 32b of the nut 32 from the side of the ram chair 36. Then, the nut 32 is rotated and firmly tightened into the through hole 33 a of the bearing plate 33.

  After that, when the tension force of the tension rod 35 by the center hole jack 37 is released, the tension force of the tension material 31 acts on the bearing plate 33 from the nut 32, and the bearing plate 33 is pressed against the bearing surface of the concrete structure 10 to become concrete. Prestress is introduced into the structure 10.

  After fixing the tendon 31, as shown in FIG. 17, the center hole jack 37, the ram chair 36 and the tension rod 35 are removed, and the tendon 31 is cut leaving a cutting excess length. Further, as shown in FIG. 18, grout is press-fitted from the injection tube 39 connected to the grout injection hole 33b, and the space in the sheath 34 is filled as shown in FIG. At that time, the nut 32 is in close contact within the through hole 33b of the bearing plate 33, and further protrudes into the sheath 34 from the bearing plate 33, so that there is no space that is difficult to fill with grout, and the grout is filled. No residual space is likely to occur.

  When the tension member 31 is fixed as described above, the length of the fixing portion of the tension member 31 protruding from the bearing surface 10a of the concrete structure 10 is the cutting of the tool engaging portion 32b of the nut 32 and the tension member 31. Only the total length of the extra length. Therefore, the projecting length can be shortened as compared with the conventional tension material fixing tool, and the layer thickness of the protective concrete 40 can be reduced.

It is a schematic sectional drawing which shows the tension material fixing tool which is one Embodiment of this invention. It is the top view, side view, and sectional drawing of a long nut used with the tension material fixing tool shown in FIG. It is a top view, a side view, a cross-sectional view, and a bottom view of a fixing nut used in the tension material fixing tool shown in FIG. It is the top view and sectional drawing of a bearing plate used with the tension material fixing tool shown in FIG. It is the schematic which shows the procedure which performs tension | tensile_strength work and fixing work using the tension material fixing tool shown in FIG. It is a schematic sectional drawing which shows the procedure which performs tension | tensile_strength work and fixing work using the tension material fixing tool shown in FIG. It is a schematic sectional drawing which shows the procedure which performs tension | tensile_strength work and fixing work using the tension material fixing tool shown in FIG. It is a schematic sectional drawing which shows the procedure which performs tension | tensile_strength work and fixing work using the tension material fixing tool shown in FIG. It is a schematic sectional drawing which shows the procedure which performs tension | tensile_strength work and fixing work using the tension material fixing tool shown in FIG. It is a schematic cross section which shows the procedure which performs tension | tensile_strength work and fixing work using the tension material fixing tool shown in FIG. It is reference sectional drawing for demonstrating the function of the guide nut in the tension material fixing tool shown in FIG. It is a schematic sectional drawing which shows the tension material fixing tool which is other embodiment of this invention. FIG. 13 is a plan view, a side view, a cross-sectional view, and a bottom view of a nut used in the tendon fixing device shown in FIG. 12. It is the top view and sectional drawing of a bearing plate used with the tension material fixing tool shown in FIG. It is a schematic sectional drawing which shows the procedure which performs tension | tensile_strength work and fixing work using the tension material fixing tool shown in FIG. It is a schematic sectional drawing which shows the procedure which performs tension | tensile_strength work and fixing work using the tension material fixing tool shown in FIG. It is a schematic sectional drawing which shows the procedure which performs tension | tensile_strength work and fixing work using the tension material fixing tool shown in FIG. It is a schematic sectional drawing which shows the procedure which performs tension | tensile_strength work and fixing work using the tension material fixing tool shown in FIG. It is a schematic sectional drawing which shows the procedure which performs tension | tensile_strength work and fixing work using the tension material fixing tool shown in FIG. It is a schematic sectional drawing which shows the conventional tension material fixing tool. It is a schematic sectional drawing which shows the state which performs tension | tensile_strength work and fixing work using the tension material fixing tool shown in FIG. It is the schematic which shows the process after performing the tension | tensile_strength work and fixing work using the tension material fixing tool shown in FIG. It is a schematic sectional drawing which shows one of the problems in the conventional tension material fixing tool.

10: Concrete structure, 11: Tensile material, 12: Long nut, 12a: Thread provided on the outer peripheral surface of the long nut, 12b: Pin, 13: Fixing nut, 13a: Wedge-shaped part, 13b: Tool engaging part , 14: bearing plate, 14a: through hole, 14b: grout injection hole, 15: sheath, 15a: expanded diameter portion of sheath, 16: extension steel, 17: center hole jack, 18: guide nut, 19: nut, 20 : Lamb chair, 21: Protective nut, 22: Grout injection pipe, 23: Protective concrete,
31: tension material, 32: nut, 32a: wedge-shaped part, 32b: tool engagement part, 33: bearing plate, 33a: through hole, 33b: grout injection hole, 34: sheath, 35: tension rod, 36: ram chair 37: Center hole jack, 38: Nut, 39: Grout injection pipe, 40: Protective concrete,
100: Concrete structure, 101: Tensile material, 102: Nut, 103: Bearing plate, 104: Tension rod, 105: Ram chair, 106: Center hole jack, 107: Nut,

Claims (7)

A tension material fixing tool that is attached to an end of a tension material and fixes the tension material so that a reaction force of a tensile force introduced into the tension material is transmitted to the structure,
A bearing plate having a through-hole through which the tendon is inserted and disposed in contact with the structure;
A long nut in which a threaded portion formed at an end of the tendon is screwed inward and a thread is formed on the outer peripheral surface;
A fixing nut that is screwed onto the outer peripheral surface of the long nut and is locked to the support plate to transmit the tensile force of the tendon to the support plate;
The inner peripheral surface of the through-hole provided in the bearing plate is relative to the axis of the tendon so that the cross-section decreases from the end side where the tendon is fixed toward the direction in which the tendon extends. Is inclined,
The tensioning material fixing tool, wherein the fixing nut has an outer peripheral surface that is inclined corresponding to an inclination of an inner peripheral surface of the through hole, and is locked in a wedge shape in the through hole. The fixing nut is formed with a tool engaging portion for rotating around an axis on the outer peripheral portion on the end side of the tendon,
When the fixing nut is mounted in the through hole of the pressure plate, the tool engaging portion protrudes from the surface of the pressure plate to the end side of the tension material,
The wedge-shaped portion with the inclined outer peripheral surface is such that the support surface abutting against the structure of the support plate is substantially flush with the tip, or the tip protrudes or retracts slightly from the support surface. The tendon fixing device according to claim 1.   A protective bolt is screwed into the long nut from the side opposite to the side on which the tendon is screwed, and the protective bolt has a rear end surface that is the same as the end surface of the long nut or deeper than the end surface of the long nut. The tension material fixing tool according to claim 1 or 2, wherein the tension material fixing tool is provided. In the periphery of the through hole of the bearing plate, there is a grout hole that penetrates from the surface to the back side that becomes the bearing surface,
The tension material fixing according to claim 1, wherein the opening on the back side is provided inside a sheath that is joined to the bearing plate and into which the tension material is inserted. Ingredients. A method of fixing the tension material to the structure so that the reaction force of the tensile force introduced into the tension material is transmitted to the structure via the bearing plate,
Placing the tendon and the bearing plate at a predetermined position of the structure;
A step of screwing a screw portion formed at an end of the tendon material inside a long nut in which a thread is formed on both the inner peripheral surface and the outer peripheral surface;
An extension steel material is inserted into a through-hole provided in the bearing plate, and a thread portion formed at an end of the extension steel material is screwed into the long nut from the opposite side to the tension material, and the tension material And connecting the extended steel material,
A step in which an outer peripheral surface is inclined in a wedge shape, and a fixing nut fitted into a through hole of the bearing plate is screwed with a thread of an outer peripheral portion of the long nut;
Attaching a center hole jack to the extension steel material, pulling the extension steel material by acting a reaction force on the bearing plate and introducing tension to the tension material;
In addition to introducing a predetermined tensile force to the tendon, the fixing nut is rotated and tightened into the through hole of the bearing plate, and the inclined outer peripheral surface of the fixing nut is provided with a correspondingly inclined through hole. A step of contacting the inner peripheral surface;
A tension material fixing method comprising: releasing a traction force by the center hole jack, and removing the center hole jack and the extension steel material. The step of screwing the fixing nut into the long nut includes:
A guide nut to which the fixing nut can be screwed on the outside is screwed to a thread portion of the extension steel material, and the fixing nut is screwed to a screw thread formed on an outer peripheral surface of the guide nut,
Rotating the fixing nut or guide nut, and fitting the fixing nut into a through hole formed in the bearing plate,
6. The tension material fixing method according to claim 5, wherein the fixing nut is screwed onto the long nut in a state where a tensile force is introduced into the tension material. A tension material fixing tool that is attached to an end of a tension material and fixes the tension material so that a reaction force of a tensile force introduced into the tension material is transmitted to the structure,
A bearing plate having a through-hole through which the tendon is inserted and disposed in contact with the structure;
A nut that is screwed to a threaded portion formed at an end of the tendon, is locked to the support plate, and transmits a tensile force of the tendon to the support plate;
The inner peripheral surface of the through hole provided in the bearing plate is inclined with respect to the axis of the tendon so that the cross-section decreases from the end side of the tendon toward the direction in which the tendon extends. And
The nut has an outer peripheral surface that is inclined corresponding to the inner peripheral surface of the through hole, and is locked in a wedge shape in the through hole. The nut rotates around an axis on the end side of the tension material. A tool engaging part is formed,
The tension member fixing tool , wherein when the nut is mounted in the through hole of the bearing plate, the tool locking portion protrudes from the surface of the bearing plate .

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