JP2003286759A - Pc anchorage device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an anchorage body which does not cause an excessive load on a wedge anchorage section of PC steel wires or PC stranded wires and which is excellent in fatigue characteristic when a repeated stress acts on a PC cable and an increasing tension is applied. <P>SOLUTION: A PC anchorage device is provided with a casting block 3 buried in concrete, a bonding block 31 supported by the casting block 3, and an anchor head 6 in which PC steel wires or PC stranded wires 5 are anchored. The bonding block 31 internally forms an integrated conical body 33 formed of a filler excellent in adherence and integrated conical bodies 33 of PC steel wires or PC stranded wires to bear an excessive tension. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a PC fixing device and a PC fixing method. More specifically, a PC with excellent fatigue properties for PC cable materials such as post tension type, out cable type PC steel materials and diagonal materials.
The present invention relates to a fixing device and method.

[0002]

2. Description of the Related Art PC made of PC steel wire or PC steel wire
The most common PC fixing system for fixing cables is
It consists of a casting block embedded in concrete and an anchor head. After tensioning, the PC steel wire or the PC steel wire is fixed to the anchor head by a wedge, respectively, and the casting block and the sheath are filled with grout through the grout holes provided in the casting block to complete the fixing. Grouting is performed for the purpose of protecting a PC steel wire or a PC cable made of a PC steel wire from corrosion. When the structure is in use, the increased tension acting on the entire PC cable directly acts on the wedge portion of the anchor head.
Due to its fixing mechanism, wedge fixing causes some damage to the surface of PC steel wire or PC steel wire during fixing, and if tension is repeatedly applied to such a part, PC
Fatigue strength of steel wire or PC stranded wire may be a problem. In particular, when a PC steel wire or a PC stranded wire is used as an out cable or a PC cable having a hanging structure, the increased tension directly acts on the wedge fixing portion. Therefore, for the purpose of improving the fatigue strength of the fixing portion,
Various measures have been taken such as making various improvements to the anchor head and wedges and improving the quality. A technique for improving such fatigue characteristics is commercially available as an out-cable specification fixing member or a cable-stayed bridge specification fixing member, depending on its degree. However, all of them are expensive and have a drawback in economic efficiency.

In particular, PC cables for cable-stayed bridges are required to have excellent fatigue characteristics because the repeated variable tension due to the live load is large when a vehicle or train passes. In order to avoid damage to the PC cable due to wedge fixing, a button head process is applied to each of the multiple single wires that make up the PC cable to fix it in the socket, and then a special resin or steel ball is filled inside it. There are many specially crafted products on the market.

In such a PC fixing system, a prefabricated cable manufactured in a dedicated factory is carried into the site, temporarily placed, and then installed, tensioned and fixed. Since the prefabricated cable cannot absorb the length error for each single wire, in the PC cable manufacturing, the temperature is corrected while applying a constant tension so that the tension does not vary among the single wires, and then cut. It is extremely expensive because it requires extremely strict quality control such as button head processing and inspection. At the erection point, the deflection of the bridge girder, which changes moment by moment due to the progress of construction such as the weight of the structure, construction machinery and the outside air temperature, is calculated in advance from the number of months of prefabricated cable erection, and various error factors are thoroughly examined. After that, the production length of the PC cable has to be determined, and such a prediction requires a great deal of labor. In addition, if there is a large difference between the planned and actual construction, such as changes in the weight of the erection machine or the work load, there is a limit to the adjustment of the fixing length of the prefabricated cable. Will be very large. In addition, large-scale PC cables can weigh dozens of tons, and many large machines are required for a series of operations such as hoisting, PC cable deployment, and erection at the site.
Cable work occupies a large part of bridge construction process, construction cost, etc., and it is desired to develop a rational PC cable system.

The present inventors have previously proposed the PC fixing device shown in FIGS. 3 and 4 as a technique for solving such a problem. In this apparatus, a tensioned PC steel wire or PC steel stranded wire is wedge-fixed to an anchor head, and then a special grout material is filled in a casting block to form a high-strength cone.

FIG. 3 is a longitudinal sectional view showing the out cable fixed by the PC fixing device 1. The casting block 3 is embedded in the concrete 2, and the PC steel wire or the PC steel wire 5 inserted in the sheath 4 is fixed to the anchor head 6 by using the wedge 7. PC steel wire or PC steel stranded wire 5
A protective coating 22 is applied to the outer periphery of the. The anchor head 6 is pressure-bonded to the end surface of the casting block 3. A backup material 9 is applied to the joint portion between the casting block 3 and the sheath 4, and a pressure-resistant cone 12 is formed in the casting block 3. This cone 12 covers the anchor head 7 with a cover 8 and
Is formed by press-fitting from the injection hole, and is integrated with the PC steel wire or the PC stranded wire 5 to form a wedge for collectively fixing the PC cables. In this device, when the PC cable receives a tension equal to or higher than the tension of the PC steel wire or the PC steel wire, the adhesion effect between the cone and the PC steel wire or the PC steel wire and the cone formed of the filler are Due to the wedge effect,
Reduces the effect of increased tension directly on the wedge of the anchor head. As a result, it exhibits excellent fatigue properties.

FIG. 4 is a longitudinal sectional view of the fixing device in which the fixing device 1 of FIG. 3 is re-tensioned and fixed. The anchor head 6 and the cone 12 are pulled, the shim plate 13 is inserted between the anchor head 6 and the end surface of the casting block 3, and then the gap 15 generated between the inner surface of the casting block 3 and the cone 12 is formed. Further, the curable pressure-resistant filling material 14 is press-fitted on the back surface of the cone 12 to be re-tensioned and fixed. Such a PC fixing device is suitable for fixing an out cable and can be re-tensioned, but a slight gap 15 shown in FIG.
It has not always been easy to fill the above with a pressure resistant filling material.

[0008]

SUMMARY OF THE INVENTION The present invention is a further improvement of the above-mentioned technique. The problem to be solved by the present invention is that of PC steel materials such as post tension type and out cable type and PC such as diagonal members. For cable materials,
It is to supply a fixing member having excellent fatigue characteristics at low cost.
INDUSTRIAL APPLICABILITY The present invention has particularly excellent performance when repeated stress is applied to a PC cable to cause an increased tension.
It is an object of the present invention to provide a high-performance PC fixing device having a simple structure that does not apply an excessive load to the wedge fixing portion of a steel wire or a PC stranded wire.

[0009]

The present invention has been made to solve the above problems, and its technical means is a casting block embedded in concrete in a PC steel wire or PC steel stranded wire fixing device. And a bonding block having an inner cone that is supported by the casting block and that fixes the PC steel wire or the PC steel wire bundle.
A PC fixing device, comprising: an anchor head for fixing a PC steel wire or a PC steel wire.

In the above PC fixing device, the bonding block is connected to the casting block by a PC.
If it is formed so as to be movable in the longitudinal direction of the steel wire or the PC steel stranded wire, the PC cable that has experienced tension relaxation can be re-tensioned and re-established, and the relaxation can be easily recovered under such conditions. It is suitable as a fixing device used in.

As another invention of the present invention, there is provided a PC fixing device comprising a casing pipe embedded in concrete and a washer installed at its mouth instead of the casting block. According to the present invention, increased tension can be applied to the PC cable without applying a severe load to the fixing portion of the PC steel wire or the PC stranded wire, and the tension of the PC cable can be completely removed. You can also

In the method of the present invention, using the above PC fixing device, the PC steel wire or the PC steel wire is initially tensioned and fixed to the anchor head, and then the filler is injected into the bonding block to resist the variable tension. In the fixing method for a PC, an integral cone of the filling material and the PC steel material is formed in the fixing portion and the bonding block. In this case, as the filler, it is preferable to use a cement-based or resin-based filler having self-hardening property and good adhesiveness and having good fluidity. Such a filler is used to fill a narrow gap between the PC steel wires or the PC steel wires and to form a cone that is integral with the PC steel wires or the bundle of PC steel wires in the bonding block. It is suitable.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is a system comprising a casting block, a bonding block and an anchor head. Bonding block has P inside
It has an integral cone formed by filling the entire C steel wire or PC steel wire with a filler.

Embodiments of the present invention will be described below with reference to the drawings.

As for the adhesive force of the PC steel strand, the PC steel strand 53 is attached to the concrete 52 in the state where no tension force is applied, and as shown in FIG. 5, a tensile force P is applied to the PC steel strand 53. In addition, when an adhesion test is performed, it is known that the value becomes significantly smaller than that of the deformed bar. This is a PC
The twisting back of the steel stranded wire 53 and the PC as shown in FIG.
This is because the cross-sectional profile 54 of the steel stranded wire 53 becomes the cross-sectional profile 55 due to the reduction of the cross-sectional area.

In the present invention, the filler is press-fitted into the bonding block with a tension of about 40 to 60% of the breaking load being applied to fill the space between the PC steel wire or the PC steel wire in the bonding block. Form an integral cone. The fluctuating load applied thereafter is at most about 10% of the PC steel wire or the wire breaking load of PC steel. Therefore, there is almost no return or reduction in cross-sectional area as described above, and the adhesive effect between the PC steel wire or the PC steel wire and the filler is further increased due to the wedge effect in the bonding block, so that extremely high fatigue properties are expected. be able to.

FIG. 1 is a longitudinal sectional view of a PC fixing device 1 according to the first invention of the present invention. The casting block 3 is embedded in the concrete 2, and a bonding block 31 having a tail end portion fitted therein is provided in the mouth of the casting block 3, and the anchor head 6 is fixed to the bonding block 31. In the embodiment, the anchor head 6 is of the type in which the PC steel wire or the PC steel wire is fixed by the wedge 7, but the present invention is not limited to this, and other fixing means such as screw fixing may be used.

The PC steel wire or the PC steel wire 5 passes through the casting block 3 and the bonding block 31 and is wedge-fixed to the anchor head 6. In the bonding block 31, the PC steel wire or the PC steel stranded wire 5 forms a bundle and the gap is filled with the filling material 32 and hardens to be integrated, so that the integrated cone 3 can bear the tension force.
3 is formed.

Further, for example, after being applied to a structure using an out cable, corrosion of the PC steel wire or the PC steel wire occurs, and then the safety of the system deteriorates for some reason, and the PC steel wire or the PC steel wire Even when the wire is replaced, it is possible to cut the damaged PC steel wire or PC steel stranded wire, and then easily remove the bonding block 31 and the anchor head 6 of the main fixing body, which is embedded in concrete. The casting block 3 can be reused.

The construction method of the PC fixing device 1 is as follows. Initial tension and steady fixing of the PC steel wire or the PC stranded wire 5 are performed by the wedge 7 of the anchor head. After fixing this wedge, cut the excess length of PC steel wire or PC steel wire 5,
A ceramic-added epoxy resin, for example, is press-fitted into the bonding block 31 as the filler 32 to form the filler 32.
Cone 33 in which the PC wire and the PC steel wire 5 are integrated
Are formed in the bonding block 31. The PC fixing device 1 is expected to have an effect that the fixing force is shared by the bonding block 31 and the cone 33 against future load fluctuation, and has high yield strength and high fatigue strength.

Also in the re-tensioning (a method of gradually increasing the tension force in accordance with the construction stage of the structure) which is often used in the construction of the PC structure, the present invention is provided with the bonding block 31 and is shown in FIG. Thus, the tail end is housed in the casting block 3, the support end face 34 is formed so as to abut the mouth of the casting block, the bonding block 31 is axially movable with the casting block 3, and the support end face 34 is shimmed. Since it is possible to pinch, it is easy to re-tension.

FIG. 2 shows an embodiment according to the second invention of the present invention. Instead of the casting block 3 of FIG. 1, a casing pipe 41 embedded in concrete 2 and a washer 42 installed at its mouth are provided. Is installed. The washer 42 is interposed between the casing pipe 41 and the bonding block 31, and is connected to the bonding block 3
Supports 1. This structure also produces the same operation and effect as the structure shown in FIG.

In the present invention, when the tension is lowered for some reason, the bonding block 31 and the anchor head 6 are pulled, and in the apparatus of FIG. 1, a shim is inserted between the bonding block and the casting block,
In the device of, by changing the thickness of the washer 42,
The desired tension can be restored, and the tension material can obtain the same performance as that at the time of installation. Also, washers 4
When 2 is removed, the cable fixing device is the casing pipe 4
It is possible to move inside 1 to completely unload the tension of the PC cable, and it is also possible to replace the cable.

As described above, the existing PC cable having excellent fatigue characteristics is a prefabricated cable using a socket in the fixing portion, but it has many problems and risks. The present invention has the following features that cannot be solved by the conventional techniques. Can be made in-situ PC cable No need for prefabricated cable, single wire or bundled P
Carry the C steel material to the site and assemble a PC cable formed of a large number of PC steel wires or PC steel strands. The weight to be handled can be adjusted by making it on-site.
Costs such as C cable transportation costs, manufacturing costs, installation costs, and equipment costs thereof can be significantly reduced. Semi-prefabricated cables are also possible. PC cable systems such as fixing system, PC cable and its protective material are prefabricated to some extent, and prefabricated by freely combining the necessary materials and equipment according to the conditions such as lifting equipment and process at the installation point. It is possible and has a high degree of freedom. Easy management of PC cable length Since the initial tension is fixed by the wedge, there is no need for strict length management as with prefabricated cables, and it is possible to easily deal with structural systems that change intricately.

As described above, the present invention is a PC fixing method which is excellent in workability and low in cost.

[0026]

According to the present invention, even when a repeated stress is applied to the PC cable to cause an increased tension, the P
It has become possible to inexpensively supply a high-performance PC fixing device having excellent fatigue characteristics without placing an excessive load on the wedge fixing portion of the C steel wire or the PC steel wire. Further, it is easy to introduce re-tensioning stress to fix the tension.

Further, since it is possible to use a cable manufactured in the field, it is possible to significantly reduce the cost of cable transportation, manufacturing cost, installation cost and equipment cost thereof. Furthermore, it is possible to freely combine the necessary materials and equipment according to the conditions such as the lifting equipment and the process at the erection point to form a prefab, and the degree of freedom is high. Also, strict length control such as prefabricated cables is not required.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a PC fixing device according to an embodiment.

FIG. 2 is a vertical sectional view of a PC fixing device according to another embodiment.

FIG. 3 is a vertical cross-sectional view of a conventional PC fixing device.

FIG. 4 is a vertical sectional view of a conventional PC fixing device.

FIG. 5 is an explanatory diagram of an adhesion test.

FIG. 6 is an explanatory diagram of reduction in cross-sectional area.

[Explanation of symbols]

1 PC fixing device 2 concrete 3 casting blocks 4 sheath 5 PC steel wire or PC steel stranded wire 6 anchor head 7 wedge 8 covers 9 backup materials 11 Injection material 12 cones 13 Shim Plate 14 Filling material 15 Gap 22 Protective coating 31 bonding block 32 Filling material 33 cones 34 Support end face 41 casing pipe 42 washer 51 PC steel wire 52 concrete 53 PC steel stranded wire 54 cross-section profile 55 cross-section profile

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Souji Kanai             Marunouchi 3-4-1 shares, Chiyoda-ku, Tokyo             Ceremony Company PS (72) Inventor Yoshiaki Suzuki             Marunouchi 3-4-1 shares, Chiyoda-ku, Tokyo             Ceremony Company PS (72) Inventor Dr. Sakai             Marunouchi 3-4-1 shares, Chiyoda-ku, Tokyo             Ceremony Company PS (72) Inventor Junichi Todo             10-1 Nakahama-cho, Amagasaki-shi Shinko Steel Wire Industrial Co., Ltd.             In the company F term (reference) 2D059 AA41 BB06 BB08 CC25 DD27                       DD28 GG02                 2E164 DA01 DA24

Claims (4)

[Claims] 1. A fixing device for a PC steel wire or a PC steel strand, comprising a casting block embedded in concrete and an inner cone supported by the casting block for fixing a PC steel wire or a PC steel wire bundle. And a PC steel wire or an anchor head for fixing the PC steel wire.
Fixing device. 2. The bonding block is formed so as to be movable in a longitudinal direction of a PC steel wire or a PC steel wire with respect to a casting block.
The described PC fixing device. 3. The PC fixing device according to claim 1, further comprising a casing pipe embedded in concrete and a washer installed at a mouth of the casing pipe, instead of the casting block. 4. The PC fixing device according to claim 1, wherein a PC steel wire or a PC steel wire is initially tensioned and fixed to the anchor head, and then a filler is injected into the bonding block. And PC that resists variable tension
A PC fixing method characterized in that an integral cone with a steel material is formed in a fixing portion and a bonding block.