JPH0625457B2 - Fixing tool for prestressed concrete and fixing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fixing tool for prestressed concrete and a fixing method, and is particularly suitable for fixing a tension wire made of a stranded wire with a fiber-reinforced plastic fixing tool. And a fixing method for prestressed concrete.

[Prior Art] As is well known, prestressed concrete is a concrete product that is under a compressive load.

As a method for applying this compressive load, a tension wire rod such as steel is inserted into the through hole of a concrete body provided with a through hole in the longitudinal direction, and after the wire rod is tensioned, both ends of the wire rod are connected to both ends of the concrete body. There is a method of fixing using a fixing tool. There are many types of fixing devices.

FIG. 3 is a plan view showing an example of a fixing device, and FIG. 4 is a view shown in FIG.
It is sectional drawing which follows the -V line. Reference numeral 1 denotes an outer cone, which has a tapered inner hole 1a. Reference numeral 2 is a frustoconical inner cone that fits into the inner hole 1a,
It has a central hole of equal diameter. The inner cone 2 is divided into three to form wedges 2a, 2b, 2c. Wire 3
Is inserted into the center hole of the inner cone 2, and its removal is prevented by the tightening force of the wedges 2a, 2b, 2c,
As a result, the wire is fixed.

Besides, Hochtief, Bilfinger, Held u. Franke,
Various fixing devices such as Moraudi and Bauwens are known.

As described above, a great number of kinds of structures or configurations of the fixing device are known, but steel is widely used as a material because it requires high strength. However, the steel fixing device has considerable durability under the normal use environment, but it generates rust in a highly corrosive environment and causes its own strength decrease. Deterioration of surrounding concrete progresses due to the generation of rust. (For example, since volume expansion accompanies the occurrence of rust,
This can cause small cracks in the concrete. Therefore, when the conventional prestressed concrete is used for, for example, an offshore structure or a structure near the coast, the prestress is likely to be lowered relatively early.

As a solution to such a problem, there has been proposed a fiber reinforced plastic fixing tool which is formed by using a thermosetting synthetic resin as a binder and using glass fiber and carbon fiber as reinforcing fibers in combination (Japanese Patent Laid-Open No. 2000-242242). 62-63746).

On the other hand, a wire made of carbon fiber is also used, and it is highly evaluated because it is lighter and has higher corrosion resistance than a steel wire. As this carbon fiber wire rod, there is a case where a cable-shaped wire rod 4 made of a twisted wire obtained by twisting the unit wire rods 4a shown in FIG. 5 is used.

When the wire rod 4 made of such a stranded wire is fixed by sandwiching it with the conventional wedge-shaped fixing tools 5a and 5b, if the wire rod 4 is made of fiber-digested plastic, the pressure resistance is lower than that of the steel wire rod. The unit wire rod 4a forming the wire is the fixing tool 5a, 5b.
It may be deformed due to strong pressure on the surface and crack.

Therefore, in order to solve such a problem and more securely fix the wire, a wire 6 such as a copper wire is wound around the wire 4 as shown in FIG.

[Problems to be Solved by the Invention] When the number wire 6 is wound around the wire 4 as shown in FIG.
Fixing tools made of steel can perform fixing in a relatively stable and reliable manner, but when using fixing tools made of fiber reinforced plastic, the bending strength of fiber reinforced plastic is inferior to that of steel. There is a problem that the fixing tool is cracked by pressing with 6.

Further, when a tension wire made of such a stranded wire is pressure-bonded and fixed by a conventional fixing tool, a slight gap is generated between the wire and the fixing tool, and moisture is generated from this gap. There are also problems such as salt intrusion, freezing damage due to freezing, and salt damage due to salting out, resulting in deterioration of wire rods and cracking of concrete.

[Means for Solving Problems] A fixing tool for prestressed concrete of the present invention is a fixing tool for fixing a tension wire made of a stranded wire, and is made of fiber reinforced plastic, and the wire contact The surface is formed with life-like irregularities following the shape of the outer peripheral surface of the wire.

Further, the method of fixing the wire rod in the prestressed concrete of the present invention, the tension wire rod made of a stranded wire is inserted through the through hole provided in the concrete body, and after the wire rod is tensioned, both ends of the wire rod are made into the concrete body. In fixing, the fixing tool for prestressed concrete according to the present invention is characterized in that a resin adhesive is interposed between the wire and the fixing tool.

Hereinafter, the present invention will be described in detail with reference to FIGS. 1 and 2.

1 is a perspective view showing a divided wedge of an inner cone of a fixing tool for prestressed concrete according to an embodiment of the present invention, and FIG. 2 is a wedge shown in FIG. 1 in which the inner cone is formed. It is a perspective view showing the whole composition of the fixing tool of the present invention.

Fixing tool 10 for prestressed concrete of the present embodiment
Is made of fiber reinforced plastic and is composed of an outer cone 11 having a tapered inner hole 11a and a frustoconical inner cone 12 having a central hole fitted into the inner hole 11a. This inner cone 12 has three wedges 12
It is composed of a, 12b and 12c. .

In the present invention, the wedges 12a, 1 of the inner cone 12 are
Rifle-shaped concavities and convexities 14 are formed on the inner wall surfaces of the central holes 2b and 12c, each of which has a shape similar to the outer peripheral surface of the tension wire 13 made of a fixed stranded wire.

That is, in this rifle-shaped concavo-convex portion 14, the convex strip 14a and the concave groove 14b are provided so that they can be fitted into the spiral spiral concave groove 13a and the convex strip 13b of the wire member 13, respectively.

For this reason, the inner wall of the central hole of the inner cone 12 constituted by such wedges 12a, 12b, 12c is brought into close contact with the outer peripheral surface of the wire rod 13, and the wire rod 13 can be reliably fixed in a good pressure-bonded state.

The fixing tool of the present invention is made of fiber reinforced plastic (FRP), and it is particularly preferable that the fixing tool is formed by molding a carbon fiber as a reinforcing fiber with a thermosetting synthetic resin as a binder. By being made of such a material, the corrosion resistance of the fixing device is dramatically improved.

In this case, as the thermosetting synthetic resin to be used, those having small deformation with respect to external stress and excellent weather resistance and chemical resistance are preferable, and specifically, epoxy acrylate resin,
Examples thereof include phenol resin, amino resin, polyester resin and the like.

Carbon fibers having a diameter of about 5 to 10 μm are suitable, and both short fibers and long fibers can be used.

If the diameter of the carbon fiber is smaller than the above range, the cost is high, and if it is thick, the flexibility is poor. In addition, if the length is longer than the above range, uniform blending becomes difficult due to entanglement during production, and if the length is shorter, the reinforcing effect becomes smaller.

The weight ratio of the carbon fiber to the thermosetting synthetic resin is preferably about 85 to 15 to 60:40. With such a blending ratio, it is possible to obtain a fiber-reinforced plastic having extremely high strength.

In the present invention, a pigment or a powder filler may be mixed with the thermosetting synthetic resin as long as the strength is not impaired.

The method for manufacturing the fixing tool of the present invention made of such a fiber reinforced plastic may be a conventional method, and can be easily manufactured by, for example, a filament winding method. Alternatively, a cloth of carbon fibers may be laminated and impregnated with a thermosetting synthetic resin to be molded. When molding is carried out, compression molding can be carried out to obtain a molded product having extremely high strength.

The fixing device according to the present invention includes the fixing device having the configuration shown in FIGS. 1 and 2, the inner cone having a division number of 2 or 4 or more, and the fixing devices such as Hochtief and Bilfinger described above.
It can be applied to various fixing tools.

Such a fixing tool of the present invention is particularly effective for fixing a tension wire made of a stranded wire made of fiber reinforced plastic.

In the fixing method using such a prestressed concrete fixing device of the present invention, a tension wire made of a stranded wire is inserted into a through hole of a concrete body, and after the wire is tensioned, both ends of the wire are made into a concrete body. When fixing, it is preferable to interpose a resin adhesive between the tension wire and the fixing tool.

Specifically, it is preferable to apply a resin adhesive to the outer peripheral surface of the fixing member crimping portion of the wire and the wire contact surface of the fixing tool, and then cover the wire with the fixing tool to perform fixing.

In this case, it is preferable to use, as the resin adhesive, one having a working time, that is, a time required for exhibiting the adhesive strength, of about 30 minutes. Specifically, an adhesive such as a room temperature curing type epoxy adhesive is used. Can be used.

As described above, the wire material and the fixing tool are pressure-bonded to each other via the adhesive resin, whereby the adhesion between the wire material and the fixing tool is further enhanced, and a high-strength and solid fixing structure can be obtained.

[Operation] In the fixing tool for prestressed concrete of the present invention, since the rifle-shaped unevenness is formed on the wire abutting surface following the outer peripheral surface shape of the tension wire made of the twisted wire, it is extremely close to the tension wire. It is possible to perform pressure bonding in this state, and it is possible to fix the wire rod extremely reliably and stably without the need to wind a wire or the like around the wire rod made of stranded wire. Therefore, the problem of the fixing tool cracking is solved, and frost damage and salt damage are prevented.

Further, in the fixing method of the present invention, since the resin is interposed between the fixing tool of the present invention and the wire, the pressure-bonded state becomes more solid, and frost damage, salt damage, etc. are more reliably prevented. It is possible to obtain a prestressed concrete structure having extremely high strength and excellent durability.

[Examples] Examples will be described below.

Example 1 Using a fixing tool of the present invention as shown in FIGS. 1 and 2, a tension wire made of a stranded wire was fixed according to the fixing method of the present invention.

The materials of the outer cone and the inner cone of the fixing device and the wire rod are as follows.

Fixing tool outer cone Material: Carbon fiber reinforced epoxy acrylate resin.

Fixing tool Inner cone material: Same as outer cone.

Wire material: carbon fiber stranded wire (see FIG. 2) First, the wire was inserted through a through hole provided in the longitudinal direction of the concrete body, and this was tightened with a jig. Then, after applying a room temperature curing type epoxy adhesive to the surface of the wire, both ends of the wire covered with a fixing tool were fixed to both ends of the concrete body.

As a result, it was possible to fix the wire material and the fixing tool in a state where they were extremely closely attached. In this example, the breaking strength when the fixing device pulled the wire rod was a high strength exceeding 10 tons.

[Advantages of the Invention] As described in detail above, since the fixing tool for prestressed concrete of the present invention is made of fiber reinforced plastic, it has higher strength than a fixing tool made of steel and is excellent in durability, and the stranded wire Since the rifle-shaped unevenness following the outer peripheral surface shape of the strained wire rod is formed on the wire rod contact surface, the tension wire rod can be crimped in extremely close contact.
Therefore, the wire can be fixed very reliably and stably.

Further, according to the fixing method of the present invention using such a fixing tool, since the resin is interposed between the fixing tool and the wire, the crimped state becomes more solid, and frost damage, salt damage, etc. are more reliable. Therefore, it is possible to obtain a prestressed cleat structure having extremely high strength and excellent durability.

Therefore, the prestressed concrete according to the present invention,
It can be used stably for a long period of time even in a highly corrosive environment such as an offshore structure or a structure installed near the coast.

[Brief description of drawings]

1 is a perspective view showing a divided wedge of an inner cone of a fixing tool for prestressed concrete according to an embodiment of the present invention, and FIG. 2 is a perspective view showing an embodiment of the fixing tool according to the present invention,
3 and 4 are views showing a conventional fixing device, FIG. 3 is a plan view, and FIG. 4 is a sectional view taken along line IV-IV in FIG. 5 and 6 are perspective views showing a wire rod made of a stranded wire. 10 ... Fixing tool for prestressed concrete, 11 ... Outer cone, 12 ... Inner cone, 12a, 12b, 12c ... Wedge 13 ... Wire rod, 14 ... Rifle-like unevenness.

Claims (2)

[Claims] 1. A fixing tool for fixing a tension wire made of a stranded wire, which is made of fiber reinforced plastic,
Further, a fixing tool for prestressed concrete, characterized in that rifle-shaped unevenness following the shape of the outer peripheral surface of the wire is formed on the wire contacting surface. 2. A method of fixing a wire rod in prestressed concrete in which a tension wire rod made of a stranded wire is inserted into a through hole provided in a concrete body, the wire rod is tensioned, and both ends of the wire rod are fixed to the concrete body. In which a fixing tool made of fiber reinforced plastic and having a rifle-shaped unevenness formed on the contact surface of the wire rod in accordance with the outer peripheral surface shape of the wire rod is used, and a resin adhesive is provided between the wire rod and the fixing tool. A method for fixing a wire rod in prestressed concrete, characterized in that it is fixed by interposing.