JP2005344295A - Method and structure for anchoring structural cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an anchoring method and an anchoring structure, which have the advantage of a pressure bonding grip method, and which enable anchorage to be performed by an outer peripheral surface of a pressure bonding grip. <P>SOLUTION: In this anchoring method for a structural cable, the pressure bonding grip is fixed to a terminal end of a prestressing steel strand, and engaged with an anchoring plate inside the anchor socket. The cone-shaped or trumpet-shaped pressure bonding grip is attached at the terminal end of the prestressing steel strand in a nonstress state; the outer peripheral surface of the pressure bonding grip is engaged with a cone-shaped or trumpet-shaped pressure bonding grip engaging hole which is provided in the the anchoring plate in an opened state; and a tensile force of the cable is borne by a tapered peripheral wall of the pressure bonding grip engaging hole of the anchoring plate; and stress is transferred by a wedge effect. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fixing method and a fixing structure for a structural cable such as a cable for supporting a bridge girder of a cable-stayed bridge and a cable for supporting a suspended structure, and more particularly, an end of a PC steel stranded wire constituting the structural cable. The present invention relates to an improvement in a fixing method and a fixing structure using a pressure-grip grip that is fixed to a portion and is fixed by engaging the pressure-grip grip with a fixing plate of an anchor socket.

Conventionally, as a fixing method for a cable (structural cable composed of PC steel wire or PC steel wire) for supporting a bridge girder in a cable stayed bridge as shown in FIG. 1, (a) metal casting fixing, (b) Button head fixing, (c) Wedge fixing (see, for example, Patent Document 1) (see FIGS. 7A, 7B, and 7C), (d) Cylindrical crimp grip fixing (FIG. 6A) (See, for example, Patent Document 2).
In the above-described fixing method, (c) wedge fixing method and (d) metal cast fixing transfer cable tension to the fixing portion by the outer peripheral surface in the radial direction. On the other hand, (b) button head fixing and FIG. 6 (d) cylindrical crimp grip fixing methods are carried out by hooking the fixing plate with the support pressure of the end face of the button head or the axial end face of the crimp grip.

  In the fixing method, each of the methods (a), (b), and (d) attaches the cable in a stress-free state, while (c) the wedge method uses a conical through hole disposed on the fixing plate. The cable is held by a wedge that is divided into two or three parts, and is attached by a reaction force while applying tension to the cable.

JP-A-8-74937 Japanese Patent Laid-Open No. 11-21813

  By the way, (d) Cylindrical crimp grip fixing in the fixing method is excellent in fatigue characteristics and workability in that the cable is attached in a stress-free state. However, the crimp grip is fixed to the fixing portion in the axial direction. It is necessary to fix the end face by hooking it to the fixing plate with a supporting pressure. Therefore, the through hole formed in the fixing plate is a step consisting of a cable insertion hole and a crimp grip engagement hole having a diameter larger than the diameter of the cable insertion hole. With a perforated hole, there are problems in terms of economy that the number of processing steps for the hole is large and the manufacturing cost is high.

  In addition, the wedge method is easy to manufacture because the insertion hole formed in the fixing plate is a single tapered hole, and due to the wedge effect due to the close engagement between the radially outer peripheral surface of the wedge and the inner peripheral surface of the tapered hole. Fixing is possible, but because the cable is attached while applying tension, it has problems in fatigue characteristics and workability as compared with the cylindrical crimp grip system.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a fixing method that has the advantages of the crimping grip method and can be fixed by the outer peripheral surface of the crimping grip. It is to provide a fixing structure.

  In order to achieve the above object, the technical means taken by the present invention is to fix the crimping grip to the terminal end of the PC steel strand and fix the crimping grip to the fixing plate inside the anchor socket. In this method, a cone-type or trumpet-type crimp grip is attached to the terminal end of the PC steel strand in a stress-free state, and the outer peripheral surface of the crimp-grip grip is a cone-type or trumpet-type opened on the fixing plate. The cable is engaged with the crimping grip engaging hole, the cable tension is supported by the tapered peripheral wall of the crimping grip engaging hole of the fixing plate, and the stress is transmitted by the wedge effect.

The conical crimp grip referred to in the present invention means that the outer shape of the crimp grip fixed to the outer end of the PC steel strand is gripped from one axial end (cable end side) toward the other end. It has a tapered shape in which the outer diameter gradually changes to a small diameter.
The trumpet-type crimp grip is the outer shape of the crimp grip that is fixed to the outer end of the PC stranded wire, and is the middle in the length direction of the grip from one end in the axial direction (the end of the cable). The outer diameter of the grip is gradually changed to a small diameter until the position, and the other part has a cylindrical part having the same outer diameter, which is a combination of a so-called conical part and a cylindrical part.

  According to the above means, the conical crimp grip or the trumpet crimp grip fixed to the terminal end of the PC steel wire is fitted into the conical or trumpet crimp grip engagement hole formed through the fixing plate of the fixing portion. Thus, the tension of the cable is fixed by the wedge effect in which the outer peripheral surface of the crimping grip and the inner peripheral surface of the crimping grip engaging hole are in close contact with each other.

In addition, a specific structure for carrying out the fixing method is that a crimping grip of a cone type or a trumpet type is attached to the terminal end portion of the PC steel wire in a stress-free state, and on the other hand, to the fixing portion of the anchor socket, A cone-type or trumpet-type crimp grip engagement hole corresponding to the outer shape of the crimp grip is opened, and the tapered outer periphery of the crimp grip is in close contact with the tapered hole of the crimp grip engagement hole, and stress is applied to the outer periphery of the crimp grip. (Claim 2).
Note that the method of attaching a cone-type or trumpet-type crimp grip to the end of the PC steel strand is by using a crimping machine (crimp jack) with a built-in die that opens and closes in the radial direction. The outer shape is crimped to a conical or trumpet shape, and after crimping, the die is opened and the crimping grip is taken out.

Since the fixing method of the structural cable of the present invention can be fixed on the outer peripheral surface of the crimping grip attached in a stress-free state by the configuration of claim 1, it has excellent fatigue characteristics and workability compared to the cylindrical crimping grip method, Further, since the tension of the cable is supported by the side wall of the hole of the fixing plate, the structure of the fixing portion can be simplified and a fixing method excellent in economy can be provided.
In addition, according to the configuration of the second aspect, it is possible to provide a fixing structure that is excellent in fatigue characteristics and workability as compared with the cylindrical crimp grip system, and further excellent in economic efficiency.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a fixing structure for a structural cable according to the present invention will be described with reference to the drawings.
FIG. 2 shows a structure in which a fixing plate is integrated with the fixing portion of the anchor socket, and a conical crimp grip fixed to the end of the PC steel strand is fixed to the fixing plate. In the figure, 1 is an anchor socket. A fixing portion having two socket members 1a and 1b that are aligned with each other with a screw structure in the axial direction and having an outer diameter larger than the outer diameter of the socket member 1a at the tip of the socket member 1a. A cylindrical member 2 constituting 2 ′ is connected by a screw structure to form an outer shape in a stepped cylindrical shape. A taper hole 3 is formed on the inner side of the socket members 1a and 1b so as to extend over both members, and the taper hole is directed to about half of the thickness direction on the connection side of the tubular member 2 with the socket member 1a. 3 is formed with a large-diameter circular recess 4 communicating with the large-diameter side, and a cable 6 in which PC steel wires 5 are bundled in parallel is attached to the other half (corresponding to the fixing plate) 2a in the thickness direction. It is fixed.
The cable 6 is fixed to the other half 2a of the cylindrical member 2 by fixing a conical crimping grip 7 or a trumpet crimping grip 7 'on the outer end side of each PC steel strand 5 constituting the cable 6. The cone-type crimping grip 7 or the trumpet-type crimping grip 7 'is engaged and integrated with the other half of the cylindrical member and fixed.

  The other half 2a of the cylindrical member 2 constituting the fixing unit 2 ′ has a thickness larger than the length of the conical crimping grip 7 or the trumpet crimping grip 7 ′, and its thickness direction (axial direction). A cone-type crimping grip engagement hole 8 or a trumpet-type crimping grip engagement hole 8 ′ is radially arranged on a substantially concentric circle so as to communicate with the large-diameter circular recess 4.

  As shown in FIG. 3, the conical pressure-bonding grip engagement hole 8 is formed as a continuous tapered hole having a gradually decreasing diameter from the distal end side of the cylindrical member 2 toward the large-diameter circular recess 4.

  Further, as shown in FIG. 4, the trumpet-type crimp grip engagement hole 8 ′ is formed with a tapered hole 8a having a predetermined length from the distal end side of the cylindrical member 2 toward the large-diameter circular concave portion 4, and the tapered hole 8a has a small diameter. A straight hole 8b having the same diameter is continuously formed on the side. In the case of the trumpet type crimp grip engagement hole 8 ′, the ratio of the taper hole 8a to the straight hole 8b is not limited to the taper hole: straight hole ratio 1: 3 shown in FIG. It can be changed.

  The diameter of the crimp grip engagement holes 8 and 8 ′ in the cylindrical member 2 on the small diameter side is slightly larger than the outer diameter of the wire 5 than the PC steel constituting the cable 6.

  A conical crimping grip 7 or a trumpet crimping grip 7 ′ attached to the outer end side of the PC steel stranded wire 5 is formed with a screw 7a in a spiral shape on the inner surface of about 2/3 of the entire length of the grip, and the remaining about 1 / 3 is a smooth surface, and is configured to be able to cope with a high tension drop (tensile load) at the portion of the screw 7a. And within the design load range, it has strength in the smooth cylindrical part, suppresses the influence on the wire from PC steel by crimping as much as possible, reduces the influence on fatigue strength, and guarantees the strength in the smooth cylindrical part. It is possible to reduce the stress transmission to the cylindrical portion.

Next, an example of a method for attaching the conical crimp grip 7 will be described with reference to FIG.
First, a crimping machine 9 for crimping a crimping grip to the outside of a PC steel wire 5 has a built-in fixed die, whereas a conventional crimping machine for attaching a cylindrical crimping grip has a built-in opening / closing die. A crimping machine is used to crimp and attach the crimping grip to the PC steel strand 5, and then the open / close die is opened to remove the crimping grip from the die.
That is, the crimping machine 11 for attaching the cylindrical crimping grip 10 to the PC steel wire 5 'is fixed with the crimping jack 12 on one side of the main body as shown in FIG. The dies 13 are arranged and fixed facing each other, and a push rod 14 is fixed to the tip of the piston 12a of the crimping jack 12.
The crimping grip is attached by the caulking machine 11 by inserting the PC steel strand 5 'from the tip of the die 13 toward the crimping jack side, and the grip main body outside the tip of the PC steel wire 5' penetrating the die 13. Wear 10 '. Thereafter, the crimping jack 12 is actuated to push the push rod 14, the PC steel wire 5 'and the grip body 10' are pushed together into the die 13, and the grip body 10 'is crimped by passing through the die. A cylindrical crimp grip is fixed to the outside of the PC steel strand 5 '.
In the case of a cylindrical crimping grip, the grip body 10 ′ passes through the die 13 and is crimped to a fixed diameter, and is pushed out of the die to complete the crimping.

However, in the case of the caulking machine to which the conical crimping grip 7 or the trumpet crimping grip 7 'of the present invention is attached, the diameter of the crimping hole of the die changes from the inlet side to the outlet side as shown in FIG. The die forming the taper hole and forming the crimping hole is a split-type die 15 that can be opened and closed in the radial direction. The method for opening and closing the die may be any of hydraulic, pneumatic, or mechanical. In addition, since it is the same as that of the caulking machine 11 shown in FIG.6 (b) except the opening-and-closing type | mold die 15, the same member attaches | subjects the same code | symbol and abbreviate | omits description.
As in the case of the conventional cylindrical crimping grip, the grip is attached by the above caulking machine, as shown in FIG. 5 (a), the grip body is attached to the tip of the PC steel strand 5 penetrating the closed die 15. Fit and install. After that, as shown in FIG. 5 (b), the crimping jack is actuated to push the push rod, the PC steel strand 5 and the grip body are pushed together into the die, and the grip body is conical with a tapered hole. Crimp. After completion of the crimping, the die is opened as shown in FIG. 5C, and the PC steel wire with the conical crimping grip attached is pulled out of the die. Incidentally, the maximum outer diameter D of the grip after completion of the crimping and the minimum inner diameter D ′ of the opened die are set to D <D ′. Thereby, the grip after completion of crimping can be removed from the crimping machine.

The conical crimping grip 7 or the trumpet crimping grip 7 ′ fixed to the PC steel strand 5 by the above attachment method is attached to the PC steel 5 in a state of no stress.
The cone-type crimp grip 7 or the trumpet-type crimp grip 7 ′ is fitted into the cone-type crimp grip engagement hole 8 or the trumpet-type crimp grip engagement hole 8 ′ in the fixing portion 2 ′ of the anchor socket 1. The taper outer peripheral surface of the crimping grip is engaged with the taper hole of the engagement hole, and the tension of the cable is supported by the peripheral wall surface of the taper hole of the fixing portion 2 ′. Reference numeral 16 in FIG. 2 denotes an epoxy resin (APS compound) that fills the space in the anchor socket 1.

  In the above-described embodiment, the fixing plate on which the conical crimp grip 7 or the trumpet crimp grip 7 'attached to the terminal end of the stranded steel wire is integrally formed with the fixing portion, and the fixing portion is improved in fatigue. However, the anchor socket provided with the fixing portion and the fixing plate may be separated from each other.

The external view which shows the usage example (bridge) of the cable for structure. FIG. 3 is a longitudinal sectional view showing an example of a fixing structure according to the present invention. The expanded sectional view which shows the engagement structure of the cone-type crimping | compression-bonding grip in a fixing | fixed part. The expanded sectional view which shows the engaging structure of the trumpet type crimping grip in a fixing | fixed part. (A), (b), (c) is process explanatory drawing which shows the method of attaching a conical crimping | compression-bonding grip to PC steel strand. (A) is sectional drawing which shows the fixing system by the conventional cylindrical crimping | compression-bonding grip, (b) is explanatory drawing which shows the attachment method of a cylindrical crimping | compression-bonding grip. The conventional fixing method of a structural cable is shown, (a) is a metal casting fixing, (b) is a button head fixing, (c) is a sectional view of wedge fixing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Anchor socket 2 ... Cylindrical member 2 '... Fixing part 5 ... PC steel strand 6 ... Cable 7 ... Conical type crimp grip 7' ... Trumpet type crimp grip 8 ... Conical type crimp grip engagement hole 8 '... Trumpet type crimp Grip engagement hole

Claims (2)

A fixing method of a structural cable in which a crimping grip is fixed to a terminal end of a PC steel strand and the crimping grip is engaged with a fixing plate inside an anchor socket, wherein Attach a trumpet-type crimp grip without stress, and attach the outer periphery of the crimp grip to the conical or trumpet-type crimp grip engagement hole established in the fixing plate, and apply cable tension to the fixing plate. A fixing method for a structural cable, characterized in that the structure is supported by a tapered peripheral wall of a crimp grip engagement hole and transmits stress by a wedge effect. A fixing structure of a structural cable in which a crimping grip is fixed to a terminal end of a PC steel strand and the crimping grip is engaged with a fixing plate inside an anchor socket. Attach a trumpet-type crimp grip without stress, and open a conical or trumpet-type crimp grip engagement hole corresponding to the outer shape of the above-mentioned crimp grip in the anchor socket's fixing part, to apply stress to the wedge effect A structure for fixing a structural cable, characterized in that it is transmitted through a cable.

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