EP1757819A1

EP1757819A1 - Uniformly disposing tool for anchor wedge

Info

Publication number: EP1757819A1
Application number: EP04726284A
Authority: EP
Inventors: Tsutomu Kadotani; Takashi Takagaki; Masato Yamada; Yoshiyuki Matsubara; Motonobu Nishino
Original assignee: Sumitomo SEI Steel Wire Corp
Current assignee: Sumitomo SEI Steel Wire Corp
Priority date: 2004-04-07
Filing date: 2004-04-07
Publication date: 2007-02-28
Also published as: CN1926339A; EP1757819A4; WO2005100800A1; CN100489320C

Abstract

A tool simple in structure is provided for uniformly disposing an anchor wedge. The tool can dispose the segments of the wedge without staggering them circumferentially or axially relative to each other to grip a PC steel member, and can prevent nonuniform application of additional stress on the PC steel member.

The tool comprises a tubular part 10 and protruding parts 20, which are formed on one end of the part 10. The tubular part 10 surrounds a PC steel member (PC steel strand 100). Each protruding part 20 is inserted into the space between two adjacent wedge segments, which grip the PC steel member, to dispose the segments circumferentially at regular intervals. By inserting each protruding part 20 into the space between two adjacent wedge segments, it is possible to dispose the segments circumferentially at regular intervals.

Description

Technical Field

The present invention relates to a tool for uniformly disposing the segments of a wedge for anchoring one end of a PC steel member to a PC structure.

Background Art

Anchors with wedges are known as structures for anchoring PC steel strands or other PC steel members to PC structures. As shown in Fig. 3, each of the anchors consists of one or more wedges 200 and an anchor disk 120 or a female cone 130. The anchor disk 120 and female cone 130 have tapered holes 121 and 131, respectively.
Each wedge 200 can take the form of a truncated cone, one end of which is larger in diameter than the other end, by arranging generally two or three segments. With its segments thus arranged, each wedge 200 has a cylindrical hole formed on and extending along its axis. Each wedge 200 grips a PC steel strand 100 in its cylindrical hole. Each of the segments has an annular groove formed on its outside surface near its thicker end. With the segments arranged in the form of a truncated cone, an O-ring (not shown) engages with their grooves to bind the segments together.
It is possible to anchor a PC steel strand 100 by gripping its one end with a wedge 200, engaging the wedge 200 with a tapered hole of an anchor disk 120 or a female cone 130 and exerting a predetermined tension to the strand 100 with a jack. The anchor disk 120 or female cone 130 may be disposed on an anchor plate 110, which is disposed on a concrete structure for example. The anchor plate may be replaced by a rib cast anchor or a socket.
Such a wedge has the problem that its segments may be disposed nonuniformly along a PC steel strand and, in some cases, around the strand. As stated already, a conventional wedge is kept in the form of a truncated cone, only with its segments bound by an O-ring. As a result, when a PC steel strand is anchored by a conventional wedge, as shown in Fig. 4, the O-ring 140 may easily expand, so that the wedge segments may stagger axially and/or circumferentially relative to each other. For example, if the PC steel strand curves near the anchor (the PC steel strand is not in straight-line layout), it is difficult to dispose the segments axially in the same position. In this case, the additional stress on the PC steel strand may act nonuniformly. In particular, there are high-level demands for uniformal disposion of the segments of the wedges for the diagonal and/or outer cables of cable-stayed bridges, which need to have high fatigue characteristics. This makes it more necessary to prevent the segments from staggering relative to each other.
Japanese Patent Publication (before examination) No. H7-279912 discloses a wedge driver as a conventional technology for preventing wedge segments from staggering relative to each other as stated above. The wedge driver consists of an outer cylinder and a hollow push cylinder, which is housed slidably in the outer cylinder. The outer cylinder is fitted with plate springs and stoppers on its front end. The plate springs can hold wedge segments together temporarily. Each of the stoppers can be inserted into the space between two adjacent wedge segments to keep them from moving circumferentially.

Disclosure of Invention

The technology disclosed in Patent Document 1 has the following problems:

(1) The wedge driver is complex in structure.

The wedge driver needs to be fitted with stoppers and plate springs for keeping the segments of a wedge in the form of a truncated cone. Accordingly, the wedge driver has many parts and is complex in structure.

(2) If the segments of a wedge are bound by an O-ring, it is impossible to use the wedge driver for the wedge.

The O-ring binding the wedge segments would be expanded by the stoppers on the front end of the outer cylinder of the wedge driver and could not bind the segments. If the push cylinder of the wedge driver pushed the wedge, the plate springs of the driver would interfere with the O-ring. This prevents the wedge from being pushed smoothly, disengages the O-ring from the wedge and/or causes another problem.
Accordingly, the main object of the present invention is to provide a tool simple in structure for uniformly disposing an anchor wedge that can dispose the segments of the wedge without staggering them circumferentially or axially relative to each other to grip a PC steel member, and can prevent nonuniform application of additional stress on the PC steel member.
The other object of the present invention is to provide a tool for uniformly disposing an anchor wedge that can be used without difficulty even if the segments of the wedge are bound by an O-ring, and that can prevent the segments from staggering circumferentially or axially relative to each other.
The present invention achieves its objects by using a tool that disposes the segments of a wedge uniformly when the wedge is inserted into a tapered hole.
A tool according to the present invention comprises a tubular part and protruding parts, which are formed on one end of the tubular part. The tubular part surrounds a PC steel member. Each of the protruding parts is inserted into the space between two adjacent segments of a wedge, which grips the PC steel member, to dispose the segments of the wedge circumferentially at regular intervals.
When the tool is used, which has protruding parts arranged uniformly on the front end of a tubular part, the insertion of each of the protruding parts into the space between two adjacent segments of a wedge results automatically in the wedge segments being disposed circumferentially at regular intervals. This prevents a PC steel member from being gripped by the wedge segments staggered relative to each other.
The tool according to the present invention comprises a tubular part and protruding parts. The tubular part has an inner diameter that allows a PC steel member to be inserted into the part. When each of the protruding parts is inserted into the space between two adjacent segments of a wedge, the end of the tubular part on which no protruding part is formed may be struck. Therefore, the tubular part is formed of a material of mechanical strength high enough to withstand the striking shocks.
It is preferable that the end face of the tubular part on which the protruding parts are formed be perpendicular to the axial direction of the tubular part so that the segments of a wedge can be disposed axially in the same position. When the tool is driven toward the wedge, with the protruding parts each interposed between two adjacent wedge segments, the end face of the tubular part comes into contact with the end larger in diameter of the wedge so that the segments can be disposed without being staggered axially.
The protruding parts protrude from one end of the tubular part and are arranged at regular intervals circumferentially of the tubular part. In general, the protruding parts and the tubular part are formed of the same material, and the protruding parts are integral with the tubular part. The protruding parts are equal in number to the spaces between the wedge segments. For example, if the wedge consists of three segments, the spaces and the protruding parts are three in number.
It is preferable that the protruding parts be tapered toward their front ends. Each of the tapered protruding parts is easy to insert into and pull out of the space between two adjacent wedge segments.
The method for using the tool may include the steps of inserting each of the protruding parts into the space between two adjacent segments of a wedge, and striking the end of the tubular part that is opposite the protruding parts. By inserting each of the protruding parts into the space between two adjacent wedge segments, it is possible to dispose the segments of the wedge circumferentially at regular intervals. The end face of the tubular part on which the protruding parts are formed comes into contact with the segments so that the segments can be disposed without being staggered axially.
After inserting each of the protruding parts into the space between two adjacent segments of a wedge in advance, the segments of the wedge may be inserted into the tapered hole of a female cone or the like. Alternatively, after the segments of a wedge are inserted into the tapered hole of a female cone or the like, each of the protruding parts may be inserted into the space between two adjacent segments of the wedge.
As explained above, the tool according to the present invention has the following effects.

(1) When the tool is used, which has protruding parts arranged uniformly on the front end of a tubular part, the insertion of each of the protruding parts into the space between two adjacent segments of a wedge results automatically in the wedge segments being disposed circumferentially at regular intervals. This prevents a PC steel member from being gripped by the wedge segments staggered relative to each other.
(2) The formation of the protruding parts on one end of the tubular part makes the tool very simple in structure. The simple method of using the tool by inserting each of the protruding parts into the space between two adjacent segments of a wedge inhibits the wedge segments from staggering. In particular, even if the wedge segments are bound by an O-ring, it is possible to use the tool without any difficulty.
(3) The protruding parts tapered toward their front ends make each of the protruding parts easy to insert into and pull out of the space between two adjacent segments of a wedge.
(4) The end face of the tubular part on which the protruding parts are formed is perpendicular to the axial direction of the tubular part. As a result, it is possible to dispose the segments of a wedge axially in the same position.

Brief Description of Drawings

Fig. 1 (A) is an end view of a tool embodying the present invention.
Fig. 1(B) is a front view of the tool.
Fig. 2 is an explanatory drawing showing how the tool engages with wedge segments.
Fig. 3(A) is an explanatory drawing of an anchoring structure with an anchor disk.
Fig. 3(B) is an explanatory drawing of an anchoring structure with a female cone.
Fig. 4 is an explanatory drawing showing staggered wedge segments.

Best Mode for carrying out the Invention

An embodiment of the present invention will be described below.

Figs. 1(A) and 1(B) are an end view and a front view, respectively, of a tool embodying the present invention.
The tool includes a tubular part 10 and protruding parts 20, which protrude from one end of the part 10. The tubular part 10 is a cylindrical member having an inner diameter that allows a PC steel strand to be inserted into the part 10, and an outer diameter that is a little smaller than that of a wedge. In this embodiment, the tubular part 10 is formed of a steel pipe of carbon steel for machine construction (STKM13A), which has an outer diameter of 25.4 mm and an inner diameter of 19.4 mm.
The protruding parts 20 are formed at one end of the tubular part 10. In this embodiment, three protruding parts 20 are arranged at circumferentially regular intervals of 120 degrees. The protruding parts 20 and tubular part 10 are formed of the same material. The protruding parts 20 are integral with the tubular part 10.
The protruding parts 20 are tapered in width toward their front ends. The protruding part 20 are 10 mm in length, 4 mm in width at their rear ends, and 3 mm in width at their front ends.
The areas between the protruding parts 20 on the front end of the tubular part 10, at which the protruding parts 20 are formed, are faces perpendicular to the axial direction of the tubular part 10.

The procedure for using the tool is as follows.
It is assumed that a wedge 200 as shown in Figs. 3 and 4 is provided. One end of the wedge 200 is larger in diameter than the other end. The wedge 200 can substantially take the form of a truncated cone by arranging three segments. The segments are arranged in the form of a truncated cone. An O-ring surrounds and engages with the arranged segments to bind them together.
As shown in Fig. 2, each protruding part 20 of the tool is inserted into the space between adjacent arranged segments of the wedge 200. Each protruding part 20 can be inserted easily into the space between adjacent segments because the protruding parts 20 are tapered toward their front ends. The insertion results in the segments being disposed circumferentially at regular intervals because the protruding parts 20 are arranged at regular intervals circumferentially of the tubular part 10.
Each protruding part 20 is further inserted into the space between adjacent segments until the end faces between the protruding parts 20 of the tubular part come into contact with the thicker ends of the segments. The contact results in the segments being disposed without staggering axially relative to each other.
The wedge 200 thus engaging with the tool is then inserted into a female cone 130. As shown in Figs. 2 and 3 (B), the female cone 130 has a tapered hole 131, from which a PC steel strand 100 protrudes.
Because the wedge 200 engaging with the tool is inserted into the tapered hole 131, without the segments staggering circumferentially and axially relative to each other, they are prevented from staggering relative to each other when the wedge 200 engages with the female cone 130.
Subsequently, the other end of the tubular part 10, where no protruding part is formed, is struck with a hammer or the like so that the wedge can be forced into the tapered hole 131. Thereafter, the tool is removed from the wedge 200.

Industrial Applicability

In particular, the present invention relates to a tool that can dispose the segments of a wedge without staggering them relative to each other around and along a PC steel member.

Claims

A tool for uniformly disposing an anchor wedge, the tool comprising:
a tubular part for surrounding a PC steel member and

protruding parts formed on one end of the tubular part, each for being inserted into the space between two adjacent wedge segments, which grip the PC steel member, to dispose the segments circumferentially at regular intervals.
The tool claimed in claim 1 wherein the protruding parts are tapered toward the front ends thereof.
The tool claimed in claim 1 or 2 wherein the end face of the tubular part on which the protruding parts are perpendicular to the axial direction of the tubular part so that the segments can be disposed axially in the same position.