JPH0663305B2 - Method and apparatus for fixing PC steel strands - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is used by embedding a fixing tool in a bridge girder of a road bridge, a girder, a lock anchor or a beam of a building, a prestressed concrete structure such as a precast material. The present invention relates to a fixing method for PC steel strands and a fixing device suitable for carrying out the method.

(Prior Art) In a prestressed concrete structure such as a bridge girder of a road bridge, a girder, a lock anchor or a beam of a building, and a precast material, when prestressing the structure, a fixing device is arranged at both ends of the structure. However, a method in which a tension member is arranged and a tension force is applied to the tension member from one end or both ends is generally adopted.

Then, PC steel wire or PC steel rod or other PC steel material is used as a tension material, and the end of the PC steel wire is subjected to head forming by cold working to form a groove with a diameter almost equal to or larger than the PC steel wire diameter. A device for attaching the metal anchor to the connector, screwing the metal anchor to the connector, tensioning the tensioning member with a tensioning device, and then fixing the anchor to the structure with a fixing nut is disclosed in JP-B-45. -7494.

That is, in the fixing device described in the above publication, as shown in the front view of FIG. 11, the head shape of the PC steel wire is flattened by pressing the end portion (Pa) of the PC steel wire (P), and gradually. An inclined surface (Pb) in the expanding direction is integrally formed with the PC steel wire (P), and the flat end portion is formed.
The width b of (Pa) is made larger than the diameter d of the PC steel wire (P), and the thickness of the flat end (Pa) is formed to be equal to the diameter d of the tension member (P). Bundled PC steel wire bundles, and FIGS. 12A to 12D
As shown in, pull it out of the pressure plate (1), insert the connector (2) through the PC steel wire bundle, and insert the PC steel wire bundle into the grout hole.
Attach (3) to each opening groove (4) of the anchor (5) (see FIG. 13) that has a plurality of opening grooves (4) formed on the outer periphery and is formed on the outer periphery (see FIG. 12A), and then , The anchor (5) is screwed into the connector (2) and set (see Fig. 12B), and in this state, the PC steel wire bundle is pulled back to the other side, and this is repeated to complete the assembly of the fixing device. (See FIG. 12B).

After that, attach the tension rod (7) of the tensioning device (6) to the connector (2), and when the predetermined tension is reached, tighten the tightening nut (8) around the connector (2) around the PC steel wire bundle. Is fixed to the structure.

After fixing, PC grout is injected from the grout hole (3) of the anchor (5), and post-filling concrete is applied to complete the work.

As described above, according to the conventional fixing means, a PC steel material such as a PC steel wire or a PC steel rod is used as a tension material, and the heading of the PC steel material is cold-worked by a press or the like to form one anchor. I was trying to fix it.

(Problems to be Solved by the Invention) As described above, in the conventional fixing device for the tension material of the concrete structure, the PC steel material is used as the tension material.
Cold heading of steel material to the above-mentioned shape with a press etc., attach it to one anchor, set this to the connector (2), and after completing the tensioning work of PC steel material, grouting In this conventional example, a PC steel material is used as a tension material, and its end portion is cold-worked so that it can be buried and used. The head was made as a part,
High strength is required for the structural parts to which this kind of tension material is applied, and in order to satisfy this requirement, PC steel materials (wires, steel bars)
It is necessary to increase the diameter and increase the strength, but there is a limit for this type of PC steel material.

For this reason, when applying PC steel wire as a tension material, we are trying to increase strength by using many steel wires with a diameter of 5 to 7 mm, but when attaching PC steel wire to the anchor. If the steel wire has a tendency to be twisted or bent, it requires a lot of labor and time to install it.

Further, if the capacity of the PC steel material as a tension material increases, the outer diameter of the anchor for mounting them must also be increased, which leads to an increase in the size of the fixing device as a whole and an increase in its manufacturing cost, which is not preferable. .

Further, even in the heading process of the above PC steel material, because of the cold working means such as pressing, the processing pressure is high, the damage of the processing jig and the heading process shape become asymmetrical, etc. There were many cases where it became defective.

The present invention has been made in view of the above-mentioned viewpoint, and a PC having a larger diameter and higher strength than the PC steel material as a tension material can be achieved.
We use steel strands to reduce the number of tendons used.
To provide a fixing method for a PC steel wire and a device therefor, which can simplify the work of attaching the tension material to the anchor, and can similarly reduce the outer diameter of the anchor and the fixing structure by downsizing. The purpose is.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention uses, as a method for fixing the PC stranded wire, a heading process for a plurality of tension material terminals made of PC steel stranded wire. After it is placed on the structure, it is pulled out to the outside of the bearing plate and penetrated through the connector consisting of a cylindrical body with internal and external threads, while a plurality of opening grooves for accommodating the tension material are provided on the outer periphery. And a plurality of anchors, each of which has a collar portion for preventing popping out, which extends in the extension direction of the outer peripheral surface, is provided at the end portion on the side where the sleeve is attached,
After shifting the phase of the opening groove and coaxially connecting and integrating them in the serial direction, the stranded wire end portion of the tension member is housed in each opening groove, and the connector is screwed around it, and then inside the structure. Located inside the metal sheath end of the connector, the tension rod of the tensioning device is screwed into the connector, and the tensioning device applies a predetermined tension force to the tensioning member through the tension rod to end the connector end. The tension member is fixed to the structure by removing the tension rod from the connector after locking the pressure plate to the outside of the portion with a tightening nut or the like.

Further, according to the present invention, as a fixing device for a PC steel wire, a plurality of tension members made of PC steel wires and having heads formed at the ends thereof and a center hole for grouting are provided. A cylindrical body having an outer peripheral surface on which a screw is engraved, and a plurality of opening grooves for accommodating the tension member are provided at a dividing position along the outer peripheral edge extending in the axial direction to prevent the sleeve from popping out. A plurality of anchors, each of which has a flange extending in the extension direction of the outer peripheral surface between the adjacent rims of the side ends of the opening groove where the twisted head is accommodated, and screws are engraved on the inner and outer surfaces. And a connector into which each of the anchors is screwed and inserted, the openings are shifted in phase by a plurality of anchors and are coaxially connected and integrated in a serial direction,
The twisted wire end portion of the tension member is housed in each opening groove, each anchor is screwed to the connector, and is fixed to the structure by a fastener such as a tightening nut.

(Operation) According to the method and apparatus for fixing PC stranded wire of the present invention, since the PC stranded wire is used as the tension material, it is possible to increase the diameter and strength of the PC steel wire. , 1/3 the number of tension materials used compared to PC steel wire used conventionally
The anchor diameter can be reduced to a small extent, and the outer diameter of the anchor can be reduced accordingly. Therefore, the connector for setting the anchor can also be reduced in diameter, so that the manufacturing cost of the fixing device can be reduced. Further, since the number of tension members used is reduced, the attachment work to the anchor does not require a special jig, and labor saving can be achieved.

Further, according to the present invention, by using a plurality of anchors having the same shape by coaxially connecting them in multiple stages, it is possible to reduce the size of the entire fixing device while maintaining high strength.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 6.

FIG. 1 is a schematic process diagram showing a process of heading processing of a PC steel strand P used as a tension material of the present invention, which is JIS G3536.
SWPR7B 12.7mmφ PC stranded wire P is attached to a press (10) consisting of a chucking and a die (Fig. A), and is energized to raise the temperature to 400 ° C or less (Fig. B). afterwards,
Press the head die (9) to perform warm working (Fig. C,
D), a heading shape as shown in FIG. 2 is formed.

As for the heading shape, if the diameter of the PC steel wire P is d (12,7mm), the heading width b is 1.5d (19.05mm) and 2b (25.4m).
m) steel sleeve (hereinafter simply referred to as sleeve)
(11) is loaded with a lubricant and fixed over a range of 2.9d (36.83 mm) from the head.

After arranging the eight PC steel strands P that have been head-machined in this way in the structure as described later, they are drawn out of the pressure bearing plate, and the connector 2 is penetrated to the anchor shown in FIGS. 3 and 4. Attach to (5).

As shown in the figure, the anchor (5) is formed into a circular shape as a whole, and a screw portion (51) is formed on the outer periphery thereof, and opening grooves (4) opening toward the outer periphery are formed at equal intervals on the circumference. A sleeve (11) which is pierced individually and is attached to the head-making part at the side end of the outer peripheral screw part (51).
The collar portion (53) that is required to prevent popping out is provided.

Once the attachment of the PC steel strand P to the anchor (5) is completed,
The anchor (5) is screwed into the connector (2) to set it. Then, the connector (2) is positioned in the metal sheath (12) in the structure (15), and then the tension rod (7) of the tensioning device (6) is screwed into the connector (2). ,
Tension is applied to the PC steel strand P (see Fig. 5).

Although illustration is omitted, when attaching a bushing to the tip of the tension rod (7) and screwing this into the connector (2) to directly tighten the nut (13) to the tension rod (7), Can eliminate the need for a screw part on the outer periphery of the connector (2), further reduce the diameter of the connector (2), and also reduce the diameter of the bearing plate (1).

When the tension reaches a predetermined value, the tightening nut (13) is screwed onto the outer periphery of the connector (2) to fix the PC steel wire P to the structure (15) (see FIG. 6).

The configuration of the fixing device of the present invention and the basic aspect of the fixing method are as described above, but in this case, when the number of the PC steel strands P used as the tension material is many, FIG. 7 to FIG.
As shown in Fig. 0, connect and expand multiple anchors (5) (5) (1
4) Connect and integrate.

That is, as shown in FIG. 7, four PC steel wires P are attached with a 90-degree phase difference in the opening groove (4) of the anchor (5) of the same structure used in the above-mentioned embodiment, and then, Attach another anchor (5) with four open grooves (4) shown in Fig. 8 to the connecting bolt (14).
Then, they are fastened and integrated in series with each other (see FIG. 9), and then four PC steel strands P are attached to each of the four opening grooves (4) of another anchor (5) (see FIG. 10).

After that, the fixing work of the PC steel wire P is performed according to the above-mentioned process.

The embodiment of the present invention is as described above, but a comparative example between the conventional example and the present invention will be described below.

Comparative Example A comparative example was carried out on a concrete viaduct under the following conditions.

Conventional example Tension material: PC steel wire (7.0 mm x 28) JIS G3536 SWPR1 Tensile load: 167 t Anchor outer diameter: 98 mmφ Connector outer diameter: 130 mmφ Auxiliary jig: Special jig required tensile load: 178 t (base material part) Fracture) Heading process ... Cold working (1 defective shape occurred) The present invention Tension material ... PC steel stranded wire (12.7mm x 9) JIS G3536 SWPR7B Tensile load ... 168t Anchor outer diameter ... 82mmφ Connector outer diameter ... 106mmφ Auxiliary jig… No special jig required Tensile load… 180t (breaking of base material) Head manufacturing… Warm working (no defective shape) Comparison results Tensile material… PC steel wire number reduced to 1/3 Tensile load… equal Anchor outer diameter …… Reduced to 83% Connector outer diameter ・ ・ ・ Reduced to 82% Auxiliary jig… No special jig required Tensile load… No problem in tension material strength Heading process… Warm working (no defective shape) (Effect of the invention According to the method and apparatus for fixing PC stranded wire of the present invention, the PC stranded wire is used as a tension material. As a result, it is possible to make the diameter and strength higher than PC steel wire, and the use of the tension material is reduced to about 1/3 compared to the PC steel material that was conventionally used. The outer diameter of the anchor can be reduced.

Therefore, the diameter of the connector for setting the anchor can be reduced, so that the manufacturing cost of the fixing device can be reduced. Further, since the number of tension members used is reduced, the work of attaching to the anchor does not require a special jig and is simple, and labor saving can be achieved.

Further, since the heading process of the tendons is performed by the warm working at 400 ° C. or less, the heading shape defect of the ends of the tendons, which is seen in the conventional cold working, does not occur at all.

Further, according to the present invention, since a plurality of anchors of the same shape are coaxially connected in multiple stages and used, and a collar portion for preventing the sleeve from protruding is provided so as to extend in the extension direction of the outer peripheral surface, a plurality of anchors are provided. It is possible to bundle and tension the tension members of the book so that they are in contact with each other, and the outer diameter of the fixing device may be a small diameter corresponding to the outer diameter of one anchor. The excellent effect that the device to be maintained can be provided at low cost is exhibited.

[Brief description of drawings]

FIG. 1 is a schematic process diagram showing a step of heading processing of a PC steel wire P used as a tension material of the present invention, and FIG. 2 is a heading shape of a PC steel wire P used as a tension material of the present invention. FIGS. 3 to 6 show an embodiment of the fixing device of the present invention. FIG. 3 is an end view showing a state in which a PC steel strand P is attached to an anchor, and FIG. Is a cross-sectional view of the anchor, FIGS. 5 and 6 are cross-sectional views of the fixing process in the fixing device of the present invention, and FIGS. 7 to 10 are other embodiments of the present invention when a plurality of anchors are used. Fixing process diagram showing the first
FIG. 1 is a front view showing a heading shape of a PC steel wire by a conventional fixing device, FIGS. 12A to 12D are schematic sectional views showing a fixing process by the conventional fixing device, and FIG. 13 is applied to a conventional fixing device. It is an end view of the anchor to do. The names of the symbols are as follows. (1) ... Pressure plate, (2) ... Connector, (3) ... Grout hole, (4)
... Opening groove, (5) ... Anchor, (6) ... Tensioning device, (7) ... Tensioning device tension rod, (8) (13) ... Tightening nut,
(9) ... head die, (10) ... press, (11) ... steel sleeve, (12) ... metal sheath, (14) ... connecting bolt, (15) ... structure.

Claims (2)

[Claims] 1. A cylindrical body in which a plurality of ends of a tension material made of PC steel wires are subjected to heading processing, placed on a structure, and then drawn out of a bearing plate, and screws are engraved on the inner and outer surfaces. While having a plurality of opening grooves for accommodating the tension material on the outer circumference, a flange part for preventing popping out extends in the extension direction of the outer peripheral surface while being penetrated through the connector consisting of A plurality of anchors provided by shifting the phase of the opening groove and coaxially connecting and integrating in a serial direction, and storing the twisted wire end portion of the tension member in each opening groove,
After screwing the connector around it, position it inside the end of the metallic sheath in the structure, screw the tension rod of the tensioning device into the connector, and use the tensioning device to insert the tension rod through the tension rod. The tension member is fixed to the structure by removing the tension rod from this connector after locking the tension member to the bearing plate with a tightening nut or the like on the outside of the end of the connector while applying a predetermined tension force to the tension member. A method for fixing wires of PC steel, which is characterized in that 2. A circle which is made of PC stranded wire and has a plurality of tension members having heads formed at its ends, a center hole for grouting, and a screw thread on the outer peripheral surface. A plurality of opening grooves, each of which is formed of a columnar body, for accommodating the tension member are provided extending in the axial direction at a dividing position along the outer peripheral edge portion, and a collar portion for preventing the sleeve from protruding is provided with a twisted line of the opening groove. A plurality of anchors provided extending in the extension direction of the outer peripheral surface across the adjacent rims of the side end portion where the head manufacturing part fits,
It consists of a cylindrical body with threads engraved on the inner and outer surfaces, and each anchor is provided with a connector into which a screw is inserted, and the phase of the opening groove is shifted by a plurality of anchors to be coaxially connected and integrated in series. The strand end of the tension material is stored in the opening groove, each anchor is screwed to the connector, and is fixed to the structure by a fastener such as a tightening nut. apparatus.