JP2017203357A - Pretension tendon, manufacturing method of pretension tendon, construction method using pretension tendon, and method for introducing pretension into concrete - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pretension tendon capable of easily ensuring a pretension with a shortest fixing length required for the pretension tendon when any anchorage device is not used by using a pretension tendon of a high strength reinforcing bar (SD: 390 or more).SOLUTION: Disclosed pretension tendon S has at least one protruding bump 11 which is formed with the same material as the base material 10. The size of the tendon is 1.5 times or more in diameter of the base material 10 on the base material 10, at both end area of bar of a base material 10 (high strength reinforcing bar) to be tensioned.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pretension tension material, a method for producing the pretension tension material, a method using the pretension tension material, and a method for introducing pretension into concrete.

  Tensile materials (PC steel bars, steel wires, etc.) used for the pretension structure are high strength steel materials whose tensile strength is 3 to 5 times that of the reinforcing bars (also called ordinary reinforcing bars) used for general RC structures. Since PC steel introduces pretension into concrete, the higher the strength, the more effective, and the steel is made stronger by high-frequency induction heat treatment.

  That is, generally, high-frequency heating quenching is performed on steel in order to increase the strength, and the wear resistance and fatigue strength of metal parts are improved by surface quenching. It is known that the strength is increased from the surface layer to the center of the steel by adjusting the high frequency appropriate for the reinforcing bar and the filling time using this method.

And this high-strength steel material has been used as a PC structure by using it as a tension material of a pretension structure.
On the other hand, steel materials that have been heat-quenched are vulnerable to heat, and when tempered or heated at high temperatures, the tempering action of the metal acts and causes a decrease in yield strength, so that the tension necessary for pretension cannot be obtained.
For this reason, PC steel as a tension material that needs to maintain high strength is prohibited from being welded or subjected to high temperatures.

In recent years, the strength of ordinary reinforcing bars (SD490 for conventional building RC structures) has been increasing, and high strength reinforcing bars with a tensile strength of 785 N / mm ² have been produced. In the case where a large tension is not required, it is possible to use this reinforcing bar as a tension material.
For example, in the case of using PC steel wires (including stranded wires) when used only for floor slabs, the current PC is used by cutting concrete and steel wires at the same time after the strength of the concrete has developed. It is floor slab technology.

  In the case of such a technique, the adhesion performance does not work near the cut end (the steel wire and the concrete are not integrated due to insufficient adhesion), and a zone where the pretension force does not work appears at the end. Although it was a PC floor slab, there was a problem that it had an RC structure.

In order to be integrated with concrete in a reinforcing bar used as an RC structure, the reinforcing bar and the concrete do not slip at the boundary, that is, adhesion performance is necessary at the boundary between the reinforcing bar and the concrete.
On the other hand, since the steel material strength is high in the steel material for pretension (PC steel wire or PC steel stranded wire) that constitutes the pretension tension material (including precast concrete members), the adhesion performance with concrete is insufficient. A dedicated fixing device is used until the concrete and the steel material as the pretension tension material adhere to each other.

Originally, pre-tensioned concrete structures mainly consist of members for beams and columns, but when pre-tensioning is introduced into floor slabs and small beams by the pre-tensioning method, PC steel wires as pre-tension tension members are tensioned. Concrete is then cast, and after the required concrete strength has been developed, the steel wire and concrete are cut to the required length as a floor slab and carried to the construction site for use.
In this case, since there is no fixing device on the cut surface, the pretension force is insufficient for a certain length from the cut surface.
In other words, in the vicinity of the cut end of the pretensioned concrete structure, the adhesion performance does not work between the concrete and the steel wire (adhesion is insufficient), and the zone where the pretension force does not work appears at the end. It will be.

Recently, high-strength reinforcing bars (tensile strength: 785 N / mm ² , SD295 is 295 N / mm ² ) with tensile strength more than twice that of the reinforcing bars used for floor slabs (SD295) have been manufactured. As part of this, it is conceivable to use steel bars for tension as pretension tension materials.
Here, in order to ensure the necessary fixing strength (or adhesion strength), the fixing length (adhesion length) also increases in accordance with the strength of the steel material.

In the pre-tension method, when a fixing tool is not used at the end, the tension of the PC steel as the pre-tension tension material is fixed by the adhesion between the steel and concrete. Therefore, in order to transmit the tension force completely to the concrete, as shown in FIG. 13, a certain section (a certain length) is required. This length is called the fixing length (transmission length).
When only high-strength reinforcing bars are used as the pretension tendon, it is necessary to rely only on the adhesive strength of the steel bars. As with the prior art, only the adhesion force on the peripheral surface of the steel bar requires a longer fixing length as the steel used for tension becomes stronger.
In the case as described above, the pretension effect is not generated in the area where the pretension concrete structure is not sufficiently fixed.

  In addition, in the case of PCa floor slabs and small beams (full PCa, half PCa) with ordinary reinforcing bars as pretension tension members, cracks occur before the floor slabs and small beams reach their allowable strength. This crack is not aesthetically pleasing.

Conventionally, fixing performance due to lack of fixing length with concrete on the end side of pre-tensioning tension material of pre-cast members (PCa floor slab etc.) that introduce pre-tension has been constructed without much consideration. Yes.
However, in the precast member into which pretension is introduced, it is preferable to improve the structural performance by shortening the necessary fixing length on the end side of the pretension tension material and the concrete as much as possible.
Therefore, in terms of structural performance, it is desirable that the pretension tension material and the region on the end side of the concrete where pretension does not work be shorter (required fixing length is short).
In particular, on the end side of the pretension tension member that does not use the fixing device, it is desired to reduce the necessary fixing length as much as possible, and improvement toward it is a theme that is always required.

The object of the present invention is to use a high-strength reinforcing bar (SD390 or higher) as a pretension tension material, and to easily ensure the minimum fixing length of the pretension tension material when the fixing device is not used. It is to provide a pretensioning tension material that can be used.
Another object of the present invention is to provide a method for producing the pretension tendon, a method using the pretension tendon, and a method for introducing pretension into concrete.

According to the pre-tension tension material of the present invention, the problem is that the same material as the base material around the base material is 1.5 times larger than the diameter of the base material on the end side of the bar-shaped base material to be tensioned. This can be solved by forming at least one large protrusion-shaped bump.
In this specification, the term “knot” refers to a protrusion or the like having a shape 1.5 times larger than the diameter of the tension material, and when concrete is placed, the concrete and the tension material are fixed. This is what you can do.

The fixing length of the pretension tension material depends on the surface roughness of the surface of the steel material (such as deformed joints), and becomes shorter on the rough surface and longer on the smooth surface (round steel). When the steel bar is fixed as it is, there is a difference depending on the diameter, but generally it is said to be 400 mm to 450 mm in the case of a PC steel bar as a pretension tension material.
In the pre-tension structure, the conventional pre-tension tension material uses a mildly deformed node, but it has a protruding nodule that is 1.5 times larger than the diameter of the base material, and uses the adhesive force and supporting pressure. Is not used.

In the present invention, on the end side of a bar-shaped base material that is tensioned as a pre-tension tension material, a protrusion-shaped knob having the same material as the base material around the base material and 1.5 times larger than the diameter of the base material By forming at least one of these, the adhesion force and the supporting pressure act on the aneurysm, the fixing length is short, and the necessary tension can be exhibited.
That is, in the case of a pretensioned tension material having a projecting shape of an ankle formed integrally from the same material, when the tension is applied, the base material and the aneurysm at the time of applying the tension exhibit an elongation due to the tension. Under such circumstances, the bearing effect of concrete works from the position of the aneurysm, and it is possible to improve the performance by exerting the bearing effect on the adhesion effect in the zone where the adhesion performance did not work on the previous floor slab. .
In this way, one or a plurality of protrusion-shaped ridges are created on the pretension tension material, and in addition to being integrated with the concrete by adhesive force at the position of the protrusions, The effective working position of the tension can be brought closer to the end.

At this time, at least two lumps are formed at a predetermined interval, the groin on the endmost side is for tension, and the groin on the inner side from the endmost side is embedded in the concrete. Is preferred.
If comprised in this way, since the tension | tensile_strength for a tension | tensile_strength can be tensioned, it becomes unnecessary to process the edge part of a pretension tension material.
And according to the pretensioning tension material of the present invention, when pretension is effectively applied to concrete using a high strength reinforcing bar, the adhesion effect of the portion requiring adhesion (the end side of the high strength reinforcing bar) is improved. Can be made.

  Moreover, since the pretension can be introduced to the end side of the concrete floor slab by using the pretension tension material of the present invention, it is possible to control the occurrence of cracks and improve the proof stress. PCa floor slab, etc.) can be improved, making it possible to manufacture with shorter spans (members can be shortened).

  In this way, in consideration of the tensioning jig, a protrusion-shaped nodule is formed in a necessary part close to the end of the high-strength reinforcing bar. On the other hand, the tensile force is simultaneously applied to the pretension tendon and the aneurysm, and the effect of supporting the aneurysm is taken into account in addition to the adhesion stress, and the required adhesion length can be greatly shortened. For example, post-installed anchor bars can improve the adhesion performance (combination force of adhesion force and supporting pressure), thereby shortening (shallowing) the support length to be embedded.

Further, according to the method of manufacturing a pretension tension material of the present invention, the problem is that, on the end side of the tensioned rod-shaped base material, the same material as the base material is used around the base material, from the diameter of the base material. In manufacturing a pretension tension member formed by forming at least one protrusion-shaped aneurysm that is 1.5 times larger, a predetermined position on the end side of the base material is heated by a heating means, and the rod-shaped base material is This is solved by melting and forming a protrusion-shaped nodule around the base material, and the base material and the nose are integrally formed of the same material.
By comprising in this way, the pre-tension tension material which concerns on this invention can be manufactured easily.

At this time, it is preferable that the rod-shaped base material is made of a reinforcing bar manufactured by an electric furnace.
Reinforcing bars manufactured in an electric furnace achieve high strength (785N / mm ² ) by adjusting the chemical composition, so the yield strength does not decrease even when welding. On the other hand, in the case of blast furnace rebars with the same strength, it has been found that the yield strength decreases when welded. Therefore, if it is the same strength, an electric furnace rebar is preferable, but it is not intended to exclude a blast furnace rebar from the present invention.

Further, it is preferable that the knob has an outer shape that does not depend on a cross-sectional shape of the rod-shaped base material.
This nodule is formed around the rod shape of the pretension tension material, but includes an eccentric circle as well as a rod-shaped concentric circle, and has an outer shape that does not depend on the cross-sectional shape of the rod-shaped base material, and is suitable for applications. Select a shape and give it. The pretension tendon is heated and melted to create a plurality of lumps, and it is possible to perform tightening without using a fixing device.

  In addition, by making it from a single steel bar as a bar-shaped base material, the shape of the knob depends on the use and location of the steel material of this pre-tension tension material, and the size and shape (in plan view from the axis) From concentric circles to eccentric circles) can be selected and created.

Further, the heating means is preferably a fiber laser heat ray.
When building materials (rebars and steel frames) are joined by welding in the construction sector, it is necessary to ensure the strength of the base metal, and in general carbon dioxide welding (site work) and electrofusion joining (for factory-fabricated secondary processed products) Is the mainstream. Fiber laser heat rays are not used in the construction field, but rebars that are not cut with fiber laser heat rays can be partially melted.

As described above, when a fiber laser hot wire is used as the heating means, it is possible to shorten the time required for forming the bumps as compared with the conventional carbon dioxide gas welding (melting).
Melting time such as high-temperature electric power such as fusion welding is not required because fiber laser heat rays can be used without reducing the strength of high-strength reinforcing bars as pretension tension materials (in the case of electric furnace reinforcing bars) Even short fiber laser heat rays are best used.

  For the production of the knob, the rod-shaped base material is inserted into the mold having a space that can be inserted through the rod-shaped base material and matched to the shape of the knob, and is heated, and the base material positioned in the space Is heated in the space, and the rod-shaped base material is pushed into the space of the mold from the outside of the mold, and the base material in the mold is melted to form a protrusion-shaped knob. Is preferred.

  In this way, it is not necessary to join separate materials in order to form the knob, and it is possible to make the knob with the base material.

  In order to melt and soften the steel material, the formation of the knob depends on the space shape of the mold, and a concentric mold, an eccentric mold, an elliptical mold, and a polygon mold are applied to form a shape.

  According to the method for producing a pretension tension material of the present invention, the object is to form guide means along the frame in the longitudinal direction of the table-like frame and to form a knob at a predetermined position on the frame. , The heating means for creating the aneurysm is moved by being guided by the guiding means, and the insertion mold is formed so that the mold for producing the aneurysm can hold the base material constituting the pretension tension material, A space for forming the knob is formed in the mold, communicated with the insertion hole, a communication passage capable of introducing heat by the heating means is formed in the space, and the rod-shaped base material is positioned in the mold. The base material located in the mold space is heated through the communication path, and the rod-shaped base material is moved toward the mold space in accordance with the melting of the base material in the space. Pushed from the outside, the rod-shaped base material melts and the base material Protruding-shaped lumps are formed around the base material and the lumps are integrally formed of the same material to form one lumps. In order to create the following, the guide means of the gantry is guided and moved to form the next knob as described above.

  With this construction, the mold is fixed as compared to creating the lobes locally at the ends, but the heating means (eg plasma radiator) can be moved to the position of this mold, so production Will be improved.

Moreover, according to the construction method using the pretensioning tension material of the present invention, the problem is that the pre-tensioned tension material according to claim 1 or 2 is embedded, exposing a slight distance from the end portion, to the coupler. After holding the exposed portion and tensioning the coupler with a necessary tension, the tension is maintained, and the end portion is further supported by the bearing pressure by the knob of the pretension tension material and the adhesion to the concrete at the end. Introduce pretension to concrete up to the point.
More specifically, the coupler is composed of opposing nuts having wedges on at least the pretension tension material side, and a connecting body having a reverse threading on each nut and disposed between the opposing nuts, Tension the coupler by tensioning the coupler tension member with a jack, tensioning the coupler with the necessary tension force, maintaining the tension force, pulling the nut by rotation of the connecting body, pulling away by rotating to the other, The problem is solved by introducing pretension to the concrete to a position closer to the end by supporting pressure due to the bump of the pretension tension material and adhesion to the concrete at the end.
In this way, the jack-side tension steel bar is in principle coupled with a wedge by a wedge to be tensioned. However, the opposite ends of the tension steel bar may be threaded and tightened.

  If comprised in this way, a pretension can be easily given and tension | tensile_strength adjustment is attained. In other words, the end of the pretension tension material is threaded or not, so the coupler nut screw is a reverse thread, so the coupler nut (or connecting body) is rotated in one direction, It can be introduced by adjusting the pretension to the concrete by pulling and pulling them apart by rotating to the other, and pulling or pulling away the reinforcing bars in the floor slab and the auxiliary reinforcing bars.

With this configuration, the rebar moves (extends and contracts) by one screw thread by one rotation, so it is possible to introduce tension (depending on the size) without a jack. In situations where jacks cannot be brought in, tension can be suitably introduced.
Therefore, it becomes possible to introduce a tension force by rotating the coupler nut (or connecting body) when the predetermined strength of the concrete is developed, or to separate the steel bar and the nut by reverse rotation.

According to a construction method using a pretensioning tension material of the present invention, the subject is fixed by a wedge arranged in a coupler with a free end of the pretensioning tension material according to claim 1 or 2 embedded in concrete. After tensioning the tension tension member with a jack and tensioning with the necessary tension force, the tip of the jack receives a reaction force with a cone via a wedge to maintain the tension force, and the tension of the pre-tension tension member is supported by the ankle. This is solved by introducing pre-tension into the concrete to a point closer to the end by adhesion of the pressure and the concrete at the end.
When the wedge is used in this way, it is not necessary to thread the pre-tension tension material, and the work becomes easy.

  According to the method of introducing pretension to concrete using the pretension tendon of the present invention, the pretension tendon embedded in concrete is left as a fixing tendon leaving a free end side knot. Position in the concrete, position the free end-side knob as a tension knob outside the formwork, connect the pre-tension tension rod and the jack side with the knob connecting coupler, and strain the knob connecting coupler. This is solved by tensioning the anchoring knob with a tension knob and introducing pretension into the concrete to a location closer to the end. If comprised in this way, a knob will be located in the both sides of a formwork between the free end side knob and the knob in a formwork, and will tension a pretension tension material using a coupler and a knob. Is easily possible.

At this time, a mold is formed so that the tension knob is filled with concrete, and after the pre-tension tension material is fixed, the jack of the tension knob is unloaded, the coupler is removed, and the tension It is preferable that the concrete is placed in the mold around the nodule.
With such a configuration, the tension knob is embedded in the concrete as it is without cutting, so that a cutting operation becomes unnecessary.

According to the present invention, the adhesion force and the support pressure act on the aneurysm, the fixing length is short, and the necessary tension can be exhibited. The fixing length is short and the necessary tension can be demonstrated. In other words, in addition to being integrated with the concrete by adhesion force, it is possible to bring the effective working position of the pretension closer to the end portion by the support pressure of the knob-like projections.
Pre-tension can be introduced up to the end of the slab, cracking can be controlled and the proof stress is improved, so the performance of the slab can be improved, so the shorter span (members can be shortened) ) Is also possible.

  Moreover, when it is a tension material having an ankle formed integrally from the same material and is in tension, the base material and the aneurysm at the time of applying the tension show an elongation at the same time. Under such circumstances, the bearing effect of concrete works from the position of the aneurysm, and it is possible to improve the performance by exerting the bearing effect on the adhesion effect in the zone where the adhesion performance did not work on the previous floor slab. .

  This nodule is formed around a rod shape, but includes not only a rod-shaped concentric circle but also an eccentric circle, and an external shape that does not depend on the cross-sectional shape of the rod-shaped base material, and selects a shape suitable for the application. Give. A tension material is heated and melted to create a plurality of ridges and can be fastened without using a fixing device.

  According to the present invention, heating and melting can be performed by a fiber laser hot wire, and the time required for forming the bumps can be shortened as compared with conventional carbon dioxide gas welding (melting).

  Moreover, although the type | mold is being fixed compared with making a lump locally at each edge part, since a plasma radiator can be moved to the position of this type | mold, productivity will improve.

  By using a coupler as in the present invention, the rebar moves (extends and contracts) by one thread of the coupler screw, so that it is possible to introduce tension (depending on the size) without a jack. In situations where jacks cannot be brought in, tension can be suitably introduced.

When the wedge is used as in the present invention, it is not necessary to thread the pretension tension material, and the work becomes easy.
Furthermore, between the free end side and the inside of the form, the form will be located on both sides of the form, making it easy to tension the pretension tension material using the coupler and the form. It becomes.
Further, if the tension knob is embedded in the concrete, the tension knob is embedded in the concrete as it is without cutting, so that a cutting operation becomes unnecessary.
In addition, although drawing etc. are expressed centering on the floor slab, the thing of the small beam-like member (member height is higher than member width) similarly controlled by a long-term load can also be made into object.

The relationship between the pretension tension material and the adhesion force of concrete according to the present invention will be described with an example of a bump, (a) is a conceptual diagram explaining the tension force of concrete and pretension tension material, (b) is It is a conceptual diagram explaining the relationship between residual introduction force and fixing length. The relationship between the pretension tension material according to the present invention and the adhesion force of concrete will be described with three examples. (A) is a conceptual diagram illustrating the tension force between concrete and high-strength reinforcing bars, and (b) is the remaining figure. It is a conceptual diagram explaining the relationship between introduction force and fixing length. It is a schematic explanatory drawing which shows an example of the variation of the size and shape of a knob. It is explanatory drawing which shows the process of forming a knob. It is explanatory drawing which shows the example of a type | mold. It is explanatory drawing when hold | maintaining a pretension tension material on the opposite side to a tension jack. It is a schematic explanatory drawing which shows the Example using a coupler. It is explanatory drawing which shows the example which embeds one in concrete and utilizes the other for tension using two knobs. It is explanatory drawing which shows the example which does not cut | disconnect the knob used for tension. It is explanatory drawing made to tense with a wedge. It is a schematic plan view explaining the production line which shows another example. It is a schematic side view of FIG. It is another example which shows the relationship between a pretension tension material and concrete, (a) is the figure seen from the plane, (b) is the figure seen from the side, (c) is the figure seen from the side. It explains the relationship between the steel and concrete adhesion in the conventional pretension system, (a) is a conceptual diagram explaining the tension of concrete and high-strength reinforcing bars, (b) is the residual introduction force and anchorage length It is a conceptual diagram explaining the relationship.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The members, arrangements, and the like described below are not intended to limit the present invention and can be variously modified within the scope of the gist of the present invention.
FIG. 1 to FIG. 13 show an embodiment of the present invention. FIG. 1 explains the relationship between the pretension tension material and the adhesion force of concrete with an example of a bump, and FIG. FIG. 2B is a conceptual diagram illustrating the relationship between the residual introduction force and the fixing length, and FIG. 2 illustrates the relationship between the pre-tension tension material and the adhesion force of the concrete. For example, (a) is a conceptual diagram illustrating the tension between concrete and a pretension tension material, (b) is a conceptual diagram illustrating the relationship between the residual introduction force and the fixing length, and (a) in FIG. ) To (f) are schematic explanatory views showing examples of variations in the size and shape of the knobs, (a) to (c) in FIG. 4 are explanatory diagrams showing the process of forming the knobs, and (a) to (f) in FIG. c) is an explanatory view showing an example of a mold, and FIG. FIG. 7 is a schematic explanatory view showing an embodiment using a coupler, and FIG. 7A is a schematic explanatory view showing an embodiment using a coupler. (B) is an example of a coupler that is reversely threaded on the inside of the coupler and a connector with a reverse thread is placed. Fig. 8 shows two joints, one is embedded in concrete and the other is tensioned. FIG. 9 is an explanatory diagram showing an example of not cutting a knob used for tension, FIG. 10 is an explanatory diagram for tensioning with a wedge, and FIG. 11 is a schematic diagram for explaining a production line showing another example. FIG. 12 is a schematic side view of FIG. 11, and FIG. 13 is another example showing the relationship between the pretension tendon and concrete. (A) is the figure seen from the plane, (b) is the figure seen from the side, (c) is the figure seen from the side.

  The pretension tension material S according to the present invention is a rod-shaped base material 10 made of high-strength reinforcing bar or the like, and the same material as the base material 10 around the base material 10 and 1.5 times the diameter of the base material 10. The main component is that the protrusion 11 having a large protruding shape and at least one protrusion 11 are formed.

  As shown in FIG. 1, the relationship between the base material 10 made of a rod-shaped steel material as the pretension tension material S and the adhesion force of the concrete 20, as shown in FIG. The concrete 20 is placed so that the member 10 made of a high-strength reinforcing bar having the projecting ridge 11 is embedded therein, and the pretension tension material S and the concrete 20 are integrally formed. Here, the “knurl” is a protrusion having a shape 1.5 times or more larger than the diameter of the tendon, and when concrete is placed, the concrete and the pretension tendon are fixed. What you can do.

The bar-shaped base material 10 can use a reinforcing bar manufactured by an electric furnace. Reinforcing bars manufactured in an electric furnace achieve high strength (785N / mm ² ) by adjusting the chemical composition, so the yield strength does not decrease even when welding. On the other hand, in the case of blast furnace rebars with the same strength, it has been found that the yield strength decreases when welded. However, even a blast furnace rebar rather than an electric furnace rebar can be adequately dealt with by using one having a strength higher than that of the electric furnace rebar.
When the tension is applied by the pretension tension material S having the protrusion-shaped aneurysm 11 formed integrally with the same material, the base material 10 and the aneurysm 11 at the time of applying the tension exhibit the elongation under the tension. Under such circumstances, the bearing effect of the concrete 20 works from the position of the bump 11, and the bearing effect is exerted on the adhesion effect by the bump 11 in the zone where the adhesion performance did not work with the conventional floor slab, and the performance Improvements can be made.
The fixing length of the pretension tension material S depends on the surface roughness of the surface of the steel material that is the base material 10 (such as deformed nodes), and becomes shorter on the rough surface and longer on the smooth surface (round steel). When the pretension tension material S is made of a steel bar and is fixed as it is, there is a difference depending on the diameter, but it is generally a PC steel bar and is said to be 400 mm to 450 mm.

In the pre-tension structure, the conventional pre-tension tension member uses a mildly deformed node, but as in the present invention, a protruding nose 11 larger than the diameter of the base material 10 is provided, No technique is used to apply adhesion and support pressure.
On the end side of the bar-shaped base material 10 that is tensioned as the pre-tension tension material S, a protruding nodule 11 that is the same material as the base material 10 around the base material 10 and is 1.5 times larger than the diameter of the base material 10. By forming at least one of these, the adhesion force and the supporting pressure act on the knob 11, the fixing length is short, and the necessary tension can be exhibited.
As described above, when the high-strength reinforcing bar as the pre-tension tension material S is used and the pre-tension is effectively operated, the adhesion effect of the portion that needs to be adhered (the end side of the high-strength reinforcing bar) can be improved. .

In the example of FIG. 1, an example in which one knob 11 is formed is shown. After tensioning the pre-tension tension material S with a jack or the like (not shown), unloading the tension force due to the jack is shown in FIG. As described above, the tension force P is transmitted to the embedded pretension tension material S, and the adhesion force is increased by the knob 11, so that the fixing length can be made close to the position of the knob 11. That is, it is possible to sufficiently achieve the introduction pretension force and shorten the fixing length until the remaining introduction force becomes sufficient.
As described above, the conventional fixing length as shown in FIG. 14 can be shortened, the remaining pretension can be shortened, and the support pressure and adhesion stress in the pretension tension material S can be increased from the end side. Can take.

  FIG. 2 shows an example in which three aneurysms 11 are made slightly smaller than those in FIG. 1, and the introduction pretension force gradually increases at the position of the aneurysms 11 to support and apply pressure. An example in which the wearing force increases in stages is shown. Other functions and effects are the same as those shown in FIG.

  FIG. 3 illustrates a variation of the knob 11. For example, FIG. 3A shows a rod-shaped pretension tension material S, and the outer shape is an ellipse, but is concentric with respect to the sectional shape of the diameter. (B) is also an eccentric circle, (c) is also a concentric ellipse, (d) is an eccentric ellipse, and (e) is also concentric. Similarly, the shape (f) shows an eccentric square shape. That is, the knob 11 forms an outer shape that does not depend on the cross-sectional shape of the rod-shaped base material 10.

The shape of the knob 11 can be selected according to the application and use of the steel for tension, and the size and shape (from a concentric circle to an eccentric circle when viewed from the axial center). It can be created. The pretension tension material S is heated and melted to create a plurality of bumps 11 and can be fastened without using a fixing device.
In this way, various shapes can be used. In short, when tension is applied to the concrete 20 side by the knob 11 of the pretension tension material S, the pretension tension material S is preliminarily placed between the concrete 20 and the pretension tension material S. The shape and the like are not particularly limited as long as the aneurysm 11 has a large residual tension.

  Pretension tension material S is a high-strength reinforcing bar, in addition to reinforcing bars for PCa floor slabs, concrete structures such as PCa column beams, large precast box culverts, precast side grooves, L-type retaining walls and PC sheet piles. It can also be used for the main bars and post-installed anchor bars. In post-installed anchor bars, the support performance to be embedded can be shortened (shallow) by improving the adhesion performance (combination force of adhesion force and support pressure).

  The pretension tension material S can be manufactured in a process of forming the bumps 11 as shown in FIG. FIG. 4 shows a method of manufacturing the concentric circle-shaped knob 11, and (a) is an explanatory view showing a state in which the rod-like pretension tension material S is arranged on the die 30. It is formed so as to penetrate the insertion hole 31 in which the tension tension material S can be disposed, and a space 32 that matches the shape of the knob 11 is formed in the center of the mold 30. A passage 33 through which heat can be introduced from the outside is formed toward the space 32.

  And as shown in (b), the base material 10 which is the rod-shaped pretension tension material S is inserted into the mold 30, and the base material 10 located in the space 32 of the mold 30 is passed from the passage 33 by the heating means 104. Heat is introduced and heated. At this time, the base material 10 that is the pretension tension material S that has started to melt in the space 32 of the mold 30 is pushed from both sides of the mold 30 of the rod-shaped pretension tension material S, as shown in (c), The base material 10 in the mold 30 is melted, and the shape of the knob 11 is formed by the shape of the space 32 of the mold 30.

The formation of the knob 11 depends on the shape of the space 32 of the mold 30 in order to melt and soften the steel material which is the base material 10, and forms a shape by assigning a concentric, eccentric, elliptical, or polygonal mold 30. To do.
As in this embodiment, it is not necessary to join separate materials to form the knob 11, and the knob 11 can be made with the base material 10.

As the heating means 104, a fiber laser heat ray may be used. When building materials (rebars and steel frames) are joined by welding in the construction sector, it is necessary to ensure the strength of the base metal, and in general carbon dioxide welding (site work) and electrofusion joining (for factory-fabricated secondary processed products) Is the mainstream. Fiber laser heat rays are not used in the field of construction, but are used to partially melt rebar that has not been cut with fiber laser heat rays.
Thus, when the heating means 104 is a fiber laser heat ray, it is possible to shorten the time required for forming the bump 11 as compared with the conventional carbon dioxide gas welding (melting).
The fiber laser heating wire can be used without reducing the strength of the high-strength reinforcing rod (in the case of an electric furnace reinforcing rod). Use is optimal. By doing in this way, the base material 10 and the knob 11 can be integrally formed with the same material.

In addition, although the said type | mold 30 used the integral type which formed the penetration hole 31 which can arrange | position the rod-shaped pretension tension material S, and the channel | path 33 for heating, the type | mold using a split type may be used. . FIG. 5 shows an example using a split mold 40. (a) is a space 32 for forming a square (rectangular) knob 11 and (b) is a concentric circle and is 2.5 times larger. The space 32 for forming the lumps 11 of the size of (2), (c) shows the state in which the spaces 32 for forming the lumps 11 of 1.5 times are formed, and the shape of each of the lumps 11 is manufactured. It is a figure, These figures have shown variations, such as a space shape in a type | mold.
5 shows an example in which the split mold 40 is divided at the center of the mold. However, if the split mold 40 is formed so that the pretension tension material S can be arranged, the split mold 40 is split at the center of the mold. Without dividing, the division mold 40 may be divided at a biased position so that it can be easily manufactured.

  FIG. 6 is an explanatory diagram of an example using the reaction force receiving means 80 when holding the pretension tension material on the side opposite to the tension jack. The dish-shaped head 81 is contacted and fixed to the reaction force receiving means 80 at the end of the pretension tension material S opposite to the jack. Using this position as the reaction force point position, the tension of the jack causes the pretension tension material S to generate pretension (prestress).

Next, a method for introducing pretension into the concrete 20 using the pretension tendon S of the present invention will be described.
The example shown in FIG. 7 is two types of coupler systems (a) and (b). First, FIG. 7A will be described. This is an example of a coupler in which a reverse threading 60c is provided on the outer side of nuts 60a and 60b constituting the coupler 60 and a connection body 66 is disposed on the outer periphery.
First, the distance from the end portion of the pretension tension material S to the knob 11 is left with a slight length X (about 200 mm from the end portion), and the protruding portion 13 is protruded (the protruding portion is also referred to as the tension material 13). On the other hand, it connects with the jack side tension | tensile_strength bar steel 65 not shown and the coupler 60.
The coupler 60 and the wedges 61 and 62 mesh with each other, and the tension member 13 and the connecting portion 65 can be tightly connected by the opposing wedges 61 and 62.
On the other hand, a cover ring 66 is installed outside the coupler 60. The cover ring 66 has a coupler 60 at a predetermined position near the center of the outer surface of the coupler 60 and an inner surface of the cover ring as the connecting body 66, respectively. Left and right reverse screws 60c and 66c are formed with the central portion of the left and right sides as a boundary. Reference numeral 50 denotes a formwork.

By tensioning the tension member 65 that continues from the tip of the jack (not shown), the coupler 60 and the wedges 61 and 62 are engaged with each other, and the tension member 13 and the connection portion 65 are tightly coupled. Then, by rotating the connecting body (cover ring) 66, it is possible to apply the tension to the pretension tension material S while adjusting the tension.
If the connecting body (cover ring) 66 of the coupler 60 is rotated to one side, the two tension members 13 and the connecting portion 65 are pulled together, and separated by rotating to the other side. A pretension can be introduced into the concrete 20 by pulling or pulling away the tension material 65 that is a part and an auxiliary reinforcing bar.
Therefore, a predetermined strength of the concrete 20 is developed, and it becomes possible to introduce a tension force by rotating the connecting body (cover ring) 66, or to separate the steel bar and the wedge by reverse rotation.

  Next, FIG. 7B will be described. In this example, a coupler 60 and a core rod 63 as a connection body 66 are used, and a coupler is provided in which a connection body that is reversely threaded inside the coupler 60 and has a reverse thread is disposed. The same members as those in FIG. 7A are denoted by the same reference numerals, and the description thereof is omitted.

  The coupler 60 can connect the tension member 13 and the connecting portion 65 by the wedges 61 and 62 facing the core rod 63 as a connecting body. As shown in FIG. 7B, inner surface left and right reverse threading 60d and 60e are formed at predetermined positions on the inner periphery of the coupler 60. In the coupler 60 divided into two, a core rod 63 as a connecting member for drawing which is reverse threaded 63a, 63b matched to the inner surface left and right reverse threaded 60d, 60e of the coupler 60 is combined and integrated with the coupler 60. Is configured.

By tensioning the tensioning material 65 that continues from the tip of the jack (not shown), the coupler 60 and the wedges 61 and 62 are engaged with each other, and the tensioning material 13 and the connecting portion 65 are tightly coupled.
By rotating the core rod 63 as a cover ring (connector) 66 in the coupler 60, as in FIG. 7 (a), the two tension members 13 and the connection portion 65 are drawn together and rotated apart to the other, Pretension can be introduced into the concrete 20 by pulling the end portion of the pretension tension material S, which is the reinforcing bar in the slab, and the tension material 65, which is the auxiliary reinforcement, or pulling them apart. Accordingly, tension can be applied while adjusting the pretension tension material S.

  That is, one end of the pretension tension material S is set, tension is applied, tension force by a jack (not shown) is maintained via the coupler 60 fixed by a wedge, and the preload by the ankle 11 of the pretension tension material S is supported. Then, it is allowed to adhere to the concrete 20 at the end, and the pretension can be introduced to the concrete 20 to a place closer to the end.

  If comprised in this way, a pretension can be easily given and tension | tensile_strength adjustment is attained. Then, by rotating the core rod 63 as a cover ring (connector) 66 once, the reinforcing bar moves (extends and contracts) by one screw thread, so that tension (depending on the size) is introduced even without a jack. It is possible. In situations where jacks cannot be brought in, tension can be suitably introduced.

FIG. 8 shows another tension method using a knob without using a coupler. FIG. 8A is a plan view, and FIG. 8B is a cross-sectional view showing a case where two tensions on the end side are used to introduce pretension into the concrete 20. It is.
The tension end 11a (11) on the free end side of the pretension tension material S is left, and is positioned (embedded) in the concrete 20 as a fixing end 11b (11), and the tension end 11 (11a) on the free end side As shown in FIG.
The tension knob 11 (11a) is connected to the knob connecting coupler 70, and a connecting portion 73 that can be connected to a jack (not shown) is connected to the knob connecting coupler 70 and is tensioned by the jack. The coupler 70 for connecting an ankle according to the present embodiment includes a main body 71 formed of a strong frame, a groove 72 through which the base material 10 passes, and a groove 72 through which the connection portion 73 passes. In this example, the groove 72 of the knob 70 for connecting the knob is configured so that both the base material 10 and the connecting portion 73 can be handled.

Then, the coupler 70 for connecting the knobs is tensioned, the knobs 11 (11b) for fixing are tensioned with the knobs 11 (11a) for tension, and the pretension is introduced into the concrete 20 to a position closer to the end.
If comprised in this way, between the free end side knob 11 (11a) and the knob 11 (11b) in a mold, the knob 11 (11a, 11b) will be located in the both sides of a mold, It is possible to easily tension the tension tension material S using the knob connecting coupler 70 and the knob 11.

At this time, as shown in FIG. 9A, a mold 50 is formed such that the tension knob 11 is filled with the concrete 20. The mold 50 is formed with a wall so as to expand toward the aneurysm-connecting coupler 70, and is formed so that the peripheral (outer periphery) portion of the tension barb 11 of the pretension tension material S becomes the recess 51. Yes.
After the pretension tension material S has settled, in order to release the tension of the tension knob 11, the jack 90 that has been tensioned by the knob connection coupler 70 is removed, the tension force is released, and the load is unloaded. In this state, the periphery of the tension knob 11 is a recess 51 that is recessed from the mold 50.
The jack 90 is supported by a support frame 91 and abuts on the mold 50 to absorb the reaction force of the jack 90.

Next, the coupler 70 for connecting the aneurysm is removed, the concrete 22 is placed on the mold 52 around the tension aneurysm 11, and the periphery of the tension aneurysm 11 is filled with concrete so as to be flush with the mold 50. It is configured to be.
With such a configuration, the tension aneurysm 11 is embedded in the concrete 20 as it is without cutting, so that a cutting operation is not necessary.

  Instead of threading as shown in FIG. 7, a wedge and cone as shown in FIG. 10 can be used and a dedicated coupler 60 can be used. That is, FIG. 10 shows a method of introducing pre-tension into the concrete 20 using the pre-tension tension material S without threading the end portion from the end 11 on the end side of the pre-tension tension material S. .

  In the method of this example, an apparatus as shown in FIG. That is, a wedge 93, a cone 94 that accommodates the wedge 93, a stopper 95 that prevents the wedge 93 from moving, and a jack 96 that is connected to the stopper 95 are provided. The stopper 95 is formed with a concave portion 95 a that allows the movement of the wedge 93, and the wedge is configured to be movable in the space between the cone 94 and the concave portion 95 a of the stopper 95.

The tension procedure is as follows.
First, the free end portion of the pretension tension material S is fixed by the wedge 93 disposed in the coupler, and then the pretension tension material S is tensioned with a jack and tensioned with a necessary tension, and then the tip of the jack 96 Is subjected to a reaction force by the cone 94 through the wedge 93 to maintain the tension, and is closer to the end due to the support pressure by the knob 11 of the pretension tension material S and the adhesion of the concrete 20 at the end. Pretension can be introduced into the concrete 20 up to a point.

When the tension of the jack 96 is released, the wedge 93 can move in the space between the cone 94 and the recess 95a of the stopper 95 as shown in FIG. However, the tension is maintained by the action of the wedge in a pre-tensioned state.
Further, as shown in FIG. 10C, the free end portion of the protruding pretension tension material S is cut.
If comprised in this way, it will become unnecessary to thread the pretension tension material S.

11 and 12 show other embodiments showing a method of manufacturing the pretension tension material S. In these embodiments, the same members as those in the above embodiments are denoted by the same reference numerals and the description thereof is omitted. To do.
The manufacturing apparatus 100 for the pretension tendon S in this example includes a table-like gantry 101, a mold 102 for creating an aneurysm, guide means 103, and heating means 104 as main components. In this example, for example, an example is shown in which the bumps 11 are formed on both ends of a reinforcing bar (diameter 16 mm) having a length of about 8 to 11 m.

  The gantry 101 of the present embodiment is a table-like gantry 101 on which a reinforcing bar (diameter 16 mm) of about 8 to 11 m can be placed, and a higher placement table portion 101a on which a pretension tension material S having a height difference is placed. And a lower aneurysm forming table portion 101b for producing the aneurysm 11 and an inclined table portion 101c for rolling these height differences. The higher placement table portion 101a has a support portion having a long foot, and the lower aneurysm formation table portion 101b is supported by a support portion having a shorter foot than the support portion having a long foot.

  And the member 10 of the pretension tension material S in which the knob 11 is not formed is placed on the placing table portion 101a, and moved to the knob forming table portion 101b using the inclined table portion 101c. In addition, a split mold 40 for creating a knob is fixed in advance at a predetermined position where the knob 11 is formed in the knob forming table portion 101b. At this time, the inclined table portion 101c is formed at the position of the split mold 40 for forming the bump so that the base material 10 can be easily placed in the mold so that the slope is loose and fits the upper surface of the lower mold of the split mold 40. Has been.

  The split mold 40 for creating a lump in this example is a mold for creating a lump fixed on the lump forming table portion 101b of the gantry 101. The split mold 40 is an upper and lower split mold 40 and includes three pretension tension members S. After the arrangement, the upper die and the lower die can be clamped via the hinge 45. The operation of the split mold 40 is the same as in FIGS. 4 and 5, but the position of the passage, the split mold 40 can be opened and clamped via the hinge 45, and the formation of the knob 11 is pretensioned tension material. Although the number of S, which can be performed simultaneously, is different, the number of the pre-tension tension members S can be appropriately adopted, so that the division type forming the bump 11 can be configured to be other than three. Of course.

The guide means 103 is configured such that a moving rail is laid along the length direction of the pretension tension material S along the table-like gantry 101. However, it is not particularly limited as long as it is a means capable of moving in the length direction of the pretension tension material S along the table-like gantry 101, such as an air caster, without being limited to the moving rail.
Guided by the guide means 103, the heating means 104 is configured to be movable. In this example, a heating means 104 configured by placing a plasma radiator on a support base (cart) is guided by the guide means 103 and is movable.

Further, when the plasma radiator as the heating means 104 reaches the position of the split mold 40 which is a predetermined position by the guide means 103, it moves from the position to the split mold 40 of the knob forming table portion 101b and is formed in the split mold 40. Each of the spaces formed in the mold is heated via each of the passages.
In this example, the rod-shaped base material 10 is pushed into the casing forming the heating means 104 on both sides of the split mold 40 inward of the split mold 40, although not shown in the drawings, The space formed in the split mold 40 is driven by a device connected to the hydraulic cylinder device, grips the base material 10 with the gripping portion, and pushes the base material 10 heated and melted into the mold with the hydraulic cylinder. The bar-shaped base material 10 is pushed in from the outside of the split mold 40 to melt the bar-shaped base material 10 to form a protrusion-shaped nodule 11 around the base material 10. A single knob 11 is formed by integrally forming the same material. A reference numeral 110 in FIG. 11 indicates a work range of the heating unit 104.

Once the one knob 11 is formed, if necessary, in order to create the next knob 11, it is guided by the guiding means 103 of the mount 101 and fixed in advance (the mount 101 of FIG. 11). The next knob 11 is formed by moving to the knob forming table portion 101b.
In the examples of FIGS. 11 and 12, the split mold is an example of the pretension tension material S. However, in order to form two or more knobs, a plurality of split molds are arranged in advance in the work area. Thus, the heating means can be moved sequentially to form a plurality of knobs.

  As described above, the knob 11 on one side is created, and the carriage is moved to the other end by the guide means 103 to form the knob 11 in the same manner. If comprised in this way, since the base material 10 will move the heating means 104 without moving, productivity will improve.

Note that, instead of the split mold 40 as described above, it is also possible to configure. That is, an insertion hole through which the rod-shaped base material constituting the pretension tension material can be inserted, a space in which the base material melts to form an aneurysm inside the mold, and heat from the plasma radiator is introduced into the space. Fix the mold with possible communication path.
A rod-shaped base material is inserted into the mold, and the base material located in the mold space is heated through the communication path.
Then, in accordance with the melting of the base material, the rod-shaped base material is pushed into the mold space from the outside of the mold, and the rod-shaped base material is melted to form a knob around the base material.
In this way, the base material and the knob are integrally formed of the same material. When the formation of one knob is completed, the next knob is formed by being guided and moved by the guide means of the gantry to create the next knob.

  FIG. 13 is an example for a PCa floor slab as another example showing the relationship between the pretension tendon S and the concrete 20, (a) is a view seen from the plane, (b) is a view seen from the side, (c) Is a side view. As shown in the figure, in the present embodiment, the thickness of the PCa floor slab is changed, the portion in which the pretension tension material S is embedded is increased in thickness than the portion of the other concrete 20, and the pretension tension material S A concrete portion 21 having a larger thickness than other concrete thicknesses is formed around the periphery.

In other words, the PCa floor slab is preferably as thin as possible in consideration of cost merit, but the plate thickness should be calculated to prevent cracking during transportation and temporary installation (construction), as well as the minimum cover thickness of the steel bar. To be determined.
Further, the crack strength varies depending on the strength of the concrete 20 when the pretension tension material S is tensioned. When the strength of the concrete 20 is low at the stage where the adhesion is transmitted to the concrete 20 after the jack that has tensioned the pretension tension material S is released, a split phenomenon occurs in the concrete 20 (therefore, the minimum necessary concrete thickness). Is required). For this reason, there is an example in which spring bars are arranged at the end of the pretension tension material S (the end of the floor slab). However, since only the concrete thickness around the pretension tension material S is necessary, The concrete 20 around the tension tension material S is thicker than the other parts by about 150 mm, and the other concrete is made of the same thickness as a normal PCa floor slab.
Thereby, it becomes possible to prevent the generation of cracks including cracks during transportation or temporary installation (construction) when the pretension tension material S is tensioned.

  Pre-tension tension materials are high-strength reinforcing bars, as well as reinforcing bars for PCa floor slabs, PCa column beams, large pre-cast box culverts, pre-cast side grooves, L-type retaining walls, and main bars of concrete structures in the civil engineering and building field such as PC sheet piles, It can also be used for post-construction anchor bars.

10 Base material 11 (11a, 11b) Lump 13 Protruding part (tension material)
20 Concrete 21 Thick concrete 30 Mold 31 Insertion hole 32 Space 33 Passage 40 Split mold 50, 52 Mold 51 Recess 60 Coupler 60c, 66c, 60d, 60e Reverse screw 61, 62, 93 Wedge 63 Core rod 63a, 63b Reverse threading 65, 73 Connection part 66 Covering (connection body)
70 Coupler 71 Main body 72 Groove 80 Reaction force receiving means 81 Dish head 90, 96 Jack 91 Support frame 94 Cone 95 Stopper 95a Recess 100 Manufacturing apparatus 101 Mounting base 101a Placement table portion 101b Knurl formation table portion 101c Inclined table portion 102 Mold 103 Guide means 104 Heating means S Pretension tension material

Claims (13)

  A pre-form formed by forming at least one protruding nodule of the same material as the base material at least 1.5 times larger than the diameter of the base material around the base material on the end side of the bar-shaped base material to be tensioned Tension tension material.   The said knob is formed at least two at predetermined intervals, the knob on the end side is used for tension, and the knob on the inner side from the end part is embedded in concrete. Pre-tension tension material.   A pre-tension tension material formed by forming at least one knob around the base material, which is the same material as the base material and 1.5 times larger than the diameter of the base material, on the end side of the bar-shaped base material to be tensioned In manufacturing the base material, a predetermined position on the end side of the base material is heated by a heating means, the rod-shaped base material is melted to form a protrusion-shaped nodule around the base material, and the base material and the nodule are formed. Are integrally formed of the same material. A method for producing a pretension tension material.   3. The method of manufacturing a pretension tension material according to claim 2, wherein the bar-shaped base material is made of a reinforcing bar manufactured by an electric furnace.   4. The method of manufacturing a pretension tension material according to claim 3, wherein the knob has an outer shape that does not depend on a cross-sectional shape of the rod-shaped base material.   4. The method of manufacturing a pretension tension material according to claim 3, wherein the heating means is a fiber laser heat ray.   The rod-shaped base material can be inserted into the mold that has a space that matches the shape of the knob and that can be heated, and the rod-shaped base material is inserted into the space to heat the base material located in the space. 4. The pretension according to claim 3, wherein the rod-shaped base material is pushed into the space of the mold from the outside of the mold, and the base material in the mold is melted to form a protrusion-shaped knob. A method for producing tendon. In the longitudinal direction of the table-shaped gantry, guide means are formed along the gantry, a mold for creating an aneurysm is fixed at a predetermined position on the gantry, and a heating means for creating an aneurysm is guided by the guiding means Make it movable,
The mold for creating the aneurysm is formed with an insertion hole so as to hold the base material constituting the pretension tension material,
Forming a space for communicating with the insertion hole to form the knob in the mold;
Forming a communication path capable of introducing heat by the heating means into the space;
The rod-shaped base material is positioned in the mold, the base material positioned in the mold space is heated through the communication path, and the mold space is adjusted in accordance with the melting of the base material in the space. The rod-shaped base material is pushed from the outside of the mold toward the base, and the rod-shaped base material melts to form a protrusion-shaped nodule around the base material. The base material and the nodule are the same material. To form a single knob,
After forming one knob, if necessary, in order to create the next knob, the guide means of the gantry is guided and moved to form the next knob as described above. Manufacturing method of pretension tendon. Embed the knob portion of the pretension tension material according to claim 1 or 2 to expose a slight distance from the end,
Let the coupler hold the exposed part,
After tensing the coupler with the necessary tension, the tension is maintained,
A construction method using a pre-tension tension material, wherein pre-tension is introduced into the concrete to a position closer to the end portion by supporting pressure due to the bump of the pre-tension tension material and adhesion to the concrete at the end portion. The coupler is composed of opposing nuts having wedges on at least the pretension tension material side, and a connecting body disposed between the opposing nuts, each of which has a reverse threading.
Tension the coupler tension member that tensions the coupler with a jack, tension the coupler with the necessary tension, and maintain the tension,
Pulling the nut by rotating the connecting body, pulling it away by rotating to the other,
The pretension tension according to claim 9, wherein pretension is introduced to the concrete to a position closer to the end by supporting pressure due to the bump of the pretension tension material and adhesion to the concrete at the end. Construction method using materials. The free end of the pretensioning tension material according to claim 1 or 2 embedded in concrete is fixed by a wedge disposed in a coupler,
After tensioning the pretension tension material with a jack and tensioning with the necessary tension,
The jack tip is subjected to a reaction force with a cone through a wedge to maintain tension,
A method of introducing pretension into concrete, wherein pretension is introduced into the concrete to a position closer to the end by supporting pressure due to the bump of the pretension tension material and adhesion of the concrete at the end. 3. A pre-tension tension material embedded in concrete, wherein the pre-tension tension material is positioned as a fixing scab in the concrete, leaving the free end side sway, and the free end side scab is positioned outside the mold as a tension stalk. Let
Connect the knob of the pretension tension material and the jack side with a coupler for connecting the knob, tension the knob for connecting the knob, tension the fixing knob with the knob for tension, and close to the end closer to the concrete. A method of introducing pretension into concrete, characterized by introducing pretension into the concrete.   Forming a mold that fills the tension knob with the concrete, unloads the tension knob after the pretension tension material has settled, removes the coupler, The method for introducing pretension into concrete according to claim 12, wherein the concrete is placed in a mold around the knob.

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