JPH01121451A - Fixture for prestressed concrete and fixing method - Google Patents

Abstract

PURPOSE: To ensure anchoring by forming an anchor of fiber reinforced plastic, and forming rifle-like unevenness following the outer peripheral surface shape of wire material, at an abutting face to tension wire material formed of stranded wire. CONSTITUTION: This anchor for prestressed concrete 10 is formed of fiber reinforced plastic and composed of an outer cone 11 with a tapered inner hole 11a, and an inner cone 12 of frustum shape fitted into the inner hole 11a and having a center hole. The cone 12 is composed of three wedges 12a, 12b, 12c, and rifle-like unevenness following the outer peripheral surface of tension wire material 13 formed of stranded wire is formed at the internal walls of the wedges 12a, 12b, 12c. The rifle-like unevenness is fitted to spiral recessed grooves 13a and protrusions 13b of the wire material 13 to bring the internal wall of the cone 12 into close contact with the outer peripheral surface of the wire material 13. The wire material 13 can therefore be anchored positively and stably.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fixing tool and a fixing method for prestressed concrete, and is particularly suitable for fixing a tensioning wire made of stranded wire with a fixing tool made of fiber-reinforced plastic. The present invention relates to a fixing tool and a fixing method for prestressed concrete.

[Prior Art] As is well known, prestressed concrete is a concrete product that is subjected to compressive loads.

As a method of applying this compressive load, a tensioning wire such as steel is inserted into the through-hole of a concrete body provided with a through-hole in the longitudinal direction, and after tensioning this wire, both ends of the wire 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.

Figure 3 is a plan view showing an example of the fixing device, Figure 4 is Figure 3V
- It is a sectional view along the V line. Reference numeral 1 indicates an outer cone, which has a tapered inner hole fa. Reference numeral 2 denotes a truncated cone-shaped inner cone that fits into the inner hole 1a and has a central hole of equal diameter. This inner cone 2 is divided into three wedges 2a, 2b, and 2c. The wire 3 is inserted into the center hole of the inner cone 2, and its extraction is as follows:
Tightening of the wedges 2a, 2b, 2c is prevented by force, thereby fixing the wire rod.

In addition, Hochtief% Bilfinger,
He1d u.

Various fixing devices are known, such as Franke% MoraudiSBauwens.

As described above, a large number of types of fixing devices are known, but steel is widely used as a material because it requires high strength. However, although steel fixtures have considerable durability under normal use environments, they rust in highly corrosive environments, reducing their own strength and weakening them. , The deterioration of the surrounding concrete progresses due to the occurrence of rust. (For example, when rust occurs, it undergoes volumetric expansion, which causes fine troughs in the concrete.) Therefore, when conventional prestressed concrete is used, for example, in offshore structures or structures near the coast, it is difficult to compare The negative effect of prestress reduction at an early stage was likely to occur.

As a solution to these problems, a fiber-reinforced plastic fixing device has been proposed, which is made by molding a thermosetting synthetic resin as a binder and a combination of glass fiber and carbon fiber as reinforcing fibers (Unexamined Japanese Patent Publication No. (Sho 62-63746)
.

On the other hand, wire rods made of carbon fiber are also used, and are highly evaluated because they are lighter and have higher corrosion resistance than steel wire rods. As this carbon*@ wire rod, a cable-shaped wire rod 4 made of a stranded wire obtained by twisting together unit wire rods 4a shown in FIG. 5 may be used.

The wire rod 4 made of such a stranded wire is attached to a conventional wedge-shaped fixing device 5a, 5. When fixing by sandwiching the stranded wire between the wire rods 5a and 5b, if the wire rod 4 is made of fiber-reinforced plastics, the pressure resistance is lower than that of steel wire rods, so the unit wire rods 4a constituting the stranded wire are fixed by the fixing tools 5a, 5.
(b) may be strongly compressed and deformed, causing it to crack.

Therefore, in order to solve this problem and fix the film more reliably, as shown in FIG. 6, a wire 6 such as a copper wire is wound around the wire 4, and a fixing tool is crimped onto the wire 6.

[Problems to be solved by the invention] When the wire 6 is wound around the wire 4 as shown in FIG.
If the fixing device is made of steel, it can be fixed relatively stably and reliably, but when using a fixing device made of fiber-reinforced plastic, the bending strength of fiber-reinforced plastic is inferior to that of steel, so There is a problem that the fixing tool breaks due to pressure bonding with No. 6.

In addition, when a tensioning wire made of such stranded wires is crimped and fixed using a conventional fixing tool, a small gap will be created between the wire and the fixing device, and moisture and water will escape from this gap. There were also problems such as the intrusion of salt and other substances, resulting in frost damage due to freezing and salt damage due to salting out, resulting in deterioration of wire rods and cracks in concrete.

[Means for Solving the Problems] The fixing tool for prestressed concrete of the present invention is a fixing tool for fixing tensioning wires made of stranded wires, and is made of fiber-reinforced plastic, and is made of fiber-reinforced plastic. It is characterized in that the surface is formed with rifle-shaped unevenness that follows the shape of the outer peripheral surface of the wire.

In addition, the method for fixing wire rods in prestressed concrete of the present invention involves inserting a tensioning wire rod made of stranded wire into a through hole provided in a concrete body, tensioning the wire rod, and then attaching both ends of the wire rod to the concrete body. When fixing, the above-mentioned fixing tool for stressed concrete of the present invention is characterized in that a resin adhesive is interposed between the wire and the fixing tool.

The present invention will be described in detail below with reference to FIGS. 1 and 2.

FIG. 1 is a perspective view showing a divided wedge of an inner cone of a fixing device for prestressed concrete according to an embodiment of the present invention, and FIG. 2 is a perspective view showing a wedge in which the inner cone is formed by the wedge shown in FIG. 1. FIG. 1 is a perspective view showing the overall configuration of a fixing device of the present invention.

The prestressed concrete fixing device 10 of this embodiment is made of fiber-reinforced plastic and has a tapered inner hole 1.
It is composed of an outer cone 11 having a diameter 1a, and an inner cone 12 having a truncated cone shape and having a center hole that fits into the inner hole 11a. This inner cone 12 has three wedges 12a.
, t2b.

12c. .

In the present invention, the wedges 12a, 1 of this inner cone 12
Rifle-shaped unevenness 14 is formed on the inner wall surface forming the center hole of each of 2b and 12c, which follows the shape of the outer peripheral surface of the tensioning wire 13 made of a stranded wire to be fixed.

That is, the rifle-shaped unevenness 14 is provided so that the protrusions 14a and grooves 14b can fit into the spiral grooves 13a and 13b of the twisted wire rod 13, respectively.

For this reason, such wedges 12a, 12b.

The inner wall of the center hole of the inner cone 12 formed by the inner cone 12c is in close contact with the outer peripheral surface of the wire 13, and the wire 13 can be reliably fixed in a good crimped state.

The fixing device of the present invention is made of fiber-reinforced plastic (FRP), and is preferably made of thermosetting synthetic resin as a binder and carbon fiber as reinforcing fiber. By using such a material, the corrosion resistance of the fixing tool is dramatically improved.

In this case, the thermosetting synthetic resin to be used is preferably one that is less deformed by external stress and has excellent weather resistance and chemical resistance. Specifically, epoxy acrylate resin,
Examples include phenol resin, amino resin, polyester resin, and the like.

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

Carbon fibers with a diameter smaller than the above range are expensive, and those with a diameter larger than the above range have poor flexibility. Furthermore, if the length is longer than the above range, they may become entangled during manufacturing, making it difficult to mix uniformly, and if the length is short, the reinforcing effect will be reduced.

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

In the present invention, pigments and powder fillers may be mixed into the thermosetting synthetic resin as long as the strength is not impaired.

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

The fixing device of the present invention includes, in addition to the fixing device having the structure shown in FIGS. 1 and 2, the fixing device having an inner cone divided into two or four or more parts, and the above-mentioned Hochtief.

It can be applied to various types of fixing devices, such as fixing devices such as Bilfinger.

Such a fixing tool of the present invention is particularly effective for fixing tensioning wires made of twisted wires of fiber-reinforced plastics.

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

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

In this case, it is preferable to use a resin adhesive that takes about 30 minutes to work, that is, to demonstrate adhesive strength. Specifically, adhesives such as epoxy adhesives that cure at room temperature are preferred. Can be used.

By press-bonding the wire rod and the fixing tool through the adhesive resin in this manner, the adhesion between the wire rod and the fixing tool is further improved, and a high-strength and solid fixing structure can be obtained.

[Function] The fixing tool for prestressed concrete of the present invention has rifle-shaped unevenness that follows the shape of the outer circumferential surface of the tensioning wire made of stranded wires, and is therefore formed on the wire abutting surface. The wire can be crimped in the same state, and there is no need to wrap a wire or the like around the wire made of stranded wire, making it possible to fix the wire extremely reliably and stably. Therefore, the problem of cracking of the fixing device is solved, and frost damage and salt damage are also prevented.

In addition, 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 crimped state is more tightly bonded, and frost damage, salt damage, etc. are more reliably prevented. , it is possible to obtain a prestressed concrete structure with extremely high strength and excellent durability.

[Example] Examples will be described below.

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

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

Fixture outer cone material: Carbon fiber reinforced epoxy acrylate resin.

Fixture inner cone material: Same as outer cone.

Wire material: carbon fiber strands (see Figure 2).

First, a wire was inserted into a through hole provided in the longitudinal direction of the concrete body, and the wire was tensioned using a jig. After applying a room temperature curing epoxy adhesive to the surface of the wire, it was covered with a fixing tool to fix both ends of the wire to both ends of the concrete body.

As a result, the wire rod and the fixing tool were able to be fixed in extremely close contact with each other. In this example, the breaking strength when the fixing tool pulls the wire is 10 tons.

It had a high strength exceeding that of the previous one.

[Effects of the Invention] As detailed above, the prestressed concrete fixing device of the present invention is made of fiber-reinforced plastic, so it has higher strength and durability than steel fixing devices. Since rifle-shaped unevenness that follows the shape of the outer circumferential surface of the tension wire made of stranded wire is formed on the wire contact surface, it is possible to crimp the tension wire in extremely close contact with the tension wire.

Therefore, the wire can be fixed extremely reliably and stably.

Furthermore, 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 tighter, and frost damage, salt damage, etc. are more reliably prevented. This makes it possible to obtain a prestressed concrete structure with extremely high strength and excellent durability.

Therefore, the prestressed consort according to the invention is
It can be used stably for long periods of time even in highly corrosive environments such as offshore structures and structures installed near the coast.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a divided wedge of the inner cone of a fixing device for prestressed concrete according to an embodiment of the present invention, and FIG. 2 is a perspective view showing an embodiment of the fixing device of the present invention.
3 and 4 are views showing a conventional fixing device, in which FIG. 3 is a plan view and FIG. 4 is a sectional view taken along the line TV-IV in FIG. 3. FIGS. 5 and 6 are perspective views showing wire rods made of twisted wires. 10... Fixing tool for prestressed concrete, 11
...Outer cone, 12...Inner cone, 12a, 1
2b, 12cm--Wedge 13...Wire rod, 14...Rifle-shaped unevenness. Agent: Patent Attorney Tsuyoshi Shigeno b

Claims (2)

[Claims] (1) A fixing device for fixing a tensioning wire made of stranded wire, which is made of fiber-reinforced plastic, and
A fixing tool for prestressed concrete, characterized in that a rifle-shaped unevenness that follows the shape of the outer peripheral surface of the wire is formed on the wire contact surface. (2) After inserting a tensioning wire made of stranded wire into a through hole provided in the concrete body and tensioning this wire,
In a method for fixing a wire rod in prestressed concrete in which both ends of the wire rod are fixed to a concrete body, the wire rod is made of fiber-reinforced plastic, and a rifle-shaped unevenness that follows the shape of the outer peripheral surface of the wire rod is formed on the wire contact surface. 1. A method for fixing a wire in prestressed concrete, which comprises using a fixing tool and fixing the wire with a resin adhesive interposed between the wire and the fixing tool.