Wedge Structure

Abstract

To provide a wedge structure having excellent fixing performance, in which the biting depth of engaging teeth is made uniform and repeated attachment and detachment work is possible. [Solution] A wedge structure used in an intermediate fixing device for tension rods, comprising a pair of wedge members having a truncated cone-shaped outer shape and split along the central axis direction, the pair of wedge members forming a hollow section along the central axis, the inner surfaces forming the hollow section having engaging teeth that can engage with the tension rod being inserted, the pair of wedge members having opposing surfaces that face each other at the split position, and an inclined edge portion having an inclined surface that is inclined relative to the opposing surfaces at the intersection of the opposing surfaces and the inner surfaces.

Description

[Technical Field]

[0001] The present invention relates to a wedge structure for use in an intermediate anchorage for tendons. [Background technology]

[0002] Conventionally, wedges have been widely used to secure tendons in prestressed concrete structures. The wedge has a truncated cone shape and a hollow section through which the tendon passes. The wedge has engaging teeth on its inner surface that bite into the tendon to maintain a predetermined tension.

[0003] To secure tendons, wedges with a split structure are used from the viewpoint of ease of construction and reliability. In particular, when used in on-site construction, wedges with a two-split structure (see Patent Document 1: Figure 7) that are easy to work with are often used. Furthermore, wedges with a three-split structure are generally used for securing factory-fabricated pretensioned tendons to abutments or for applications that require repeated connection and disconnection, such as connecting couplers in the middle.

[0004] On the other hand, in repair and renewal work on infrastructure structures, it may be necessary to replace part of an existing tendon. In such work, in order to maintain the functionality of the structure as a whole, it is necessary to safely and reliably remove the tendon to be replaced and its connecting components (such as turnbuckles) while maintaining the tension applied to the tendon.

[0005] Figure 5 is an explanatory diagram of a method for replacing an existing tendon using a replacement tool. In this replacement method, first, a replacement device is attached to the part of the existing tendon to be replaced (Fig. 5(a)), and the tendons on both sides of the part to be replaced are fixed using intermediate fixing devices attached to both ends of the replacement device. By tensioning the temporary tendons on the replacement device, the tension of the tendons is transferred to the temporary tendons, the part to be replaced is removed (Fig. 5(b)), and new tendons can be installed (Fig. 5(c)). After the replacement is complete, the replacement device, including the intermediate fixing devices, is removed (Fig. 5(d)).

[0006] The intermediate anchor has a built-in wedge for engaging with the tendon. In field work, a two-piece wedge is often used because it is simple in structure and easy to install. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-186814 Summary of the Invention [Problem to be solved by the invention]

[0008] In conventional two-piece wedges, the small diameter of the engaging teeth (the diameter at the tip of the engaging teeth) is smaller than the diameter of the tendon (Fig. 6). For this reason, when the tendon and wedge are engaged, the engaging teeth at both ends of the wedge tend to bite into the tendon first. In particular, when the tendon is a steel bar, if the engaging teeth at both ends of the wedge bite first, the bite depth of the entire engaging teeth becomes uneven, and the engaging teeth at both ends bite deeply, making it difficult to remove the wedge after it has been set in place. As a result, this structure is not suitable for repeated attachment and detachment work, which reduces workability and reliability, especially during component replacement work.

[0009] SUMMARY OF THE INVENTION An object of the present invention is to provide a wedge structure that has a uniform bite depth of engaging teeth, allows repeated attachment and detachment, and has excellent fixing performance. [Means for solving the problem]

[0010] The present invention, made to achieve the above-mentioned object, is a wedge structure used in an intermediate fixing device for a tension member, which is composed of a pair of wedge members having a truncated conical outer shape and divided into two along a central axis direction, the pair of wedge members forming a hollow portion along the central axis, and the inner surfaces forming the hollow portion having engaging teeth that can engage with the tension member inserted therethrough, the pair of wedge members having opposing surfaces that face each other at the split position, and an inclined edge portion at the intersection of the opposing surfaces and the inner surfaces having an inclined surface that is inclined relative to the opposing surfaces. The inclined edge portion may be composed of an inclined surface extending from the opposing surface to the inner circumferential surface, and may be composed of a first removal surface which is the inclined surface continuing with the inner circumferential surface, and a second removal surface which is continuing with the first removal surface and the opposing surface. The angle formed by the straight line connecting the end of the inclined edge portion on the inner surface side to the central axis and the straight line connecting the end of the inclined edge portion on the opposing surface side to the central axis may be greater than or equal to 15 degrees and less than or equal to 17 degrees. The inclined surface may be parallel to the opposing surface and inclined at an angle of 50 degrees or more and 80 degrees or less with respect to a plane including the central axis. [Effects of the Invention]

[0011] The present invention can achieve at least one of the following effects by solving the above-mentioned problems. (1) By providing an inclined edge at the intersection of the opposing surface and the inner peripheral surface, it is possible to prevent the engaging teeth at both ends of the inner peripheral surface of the wedge member from first biting into the tendon. This allows the entire engaging teeth to bite into the tendon to a uniform depth, making it easier to remove the wedge member after installation. (2) The wedge structure is divided into two parts and can be easily removed, making it reusable and suitable for repeated installation and dismantling. This improves the efficiency and reliability of work when replacing tendons and their connecting members while maintaining tension. (3) By setting the removal angle at the inclined edge, i.e., the angle between the straight lines connecting the ends on the inner surface side and the opposing surface side with the central axis, within an appropriate range depending on the diameter of the inner surface of the tension member and the wedge member, the distribution angle of the remaining engaging teeth approaches a three-part structure, making it easier to remove the wedge member and significantly improving the workability of installation and dismantling. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is an explanatory diagram of a state in which the wedge structure according to the present invention is used; [Figure 2] FIG. [Figure 3] 10A and 10B are explanatory diagrams showing examples of the configuration of an inclined edge portion of a wedge member. [Figure 4] FIG. 10 is an explanatory diagram of the state in which the tendon is fixed by the wedge structure. [Figure 5] FIG. 10 is an explanatory diagram of a method for replacing an existing tendon. [Figure 6] FIG. 10 is an explanatory diagram of a conventional wedge and tendon engagement state. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0014] <1> Wedge structure configuration The wedge structure 1 of the present invention is a component used to grip the outer periphery of the tendon 3 in a tendon anchoring device that is primarily used when intermediately anchoring the tendon 3. Note that the wedge structure 1 of the present invention is not limited to such intermediate anchoring, but can also be applied to anchoring devices in newly constructed structures and other tendon anchoring applications. Furthermore, as mentioned above, the tendon 3 is not limited to steel bars, in which the engaging teeth at both ends of a conventional wedge significantly engage first, but can also be applied to conventionally used steel wires, steel strands, etc. The tendon anchor has a jacket 4 with a through hole 41 at the center, and the wedge structure 1 is inserted into the through hole 41 of the jacket 4 when in use (Fig. 1). The wedge structure 1 has a truncated cone-shaped outer shape and is composed of a pair of wedge members 2 split in two along the central axis (Fig. 2). The wedge members 2 have opposing surfaces 21 that face each other at the split position, and an inner peripheral surface 22 that forms a hollow portion through which the tendon 3 is inserted. The wedge structure 1 has a split structure, which makes it easy to install on site.

[0015] <2> Engaging teeth A plurality of engagement teeth 221 are formed on the inner peripheral surface 22 of the wedge member 2 . When the wedge structure 1 is pushed into the insertion hole 41 of the jacket 4, the engaging teeth 221 bite into the outer periphery of the tendon 3, thereby gripping the tendon 3.

[0016] <3> Beveled Edge The wedge member 2 has an inclined edge 23 at the intersection between the opposing surface 21 and the inner peripheral surface 22 . The inclined edge portion 23 may be composed of an inclined surface 231 inclined relative to the opposing surface 21 (Figure 3(a)), or may be composed of a first removal surface 231 which is an inclined surface continuing with the inner surface 22, and a second removal surface 232 which is continuing with the first removal surface 231 and the opposing surface 21 and is formed along the engaging tooth 221 (Figure 3(b)). The inclined edge portion 23 is formed by removing the portions of the engaging teeth 221 formed on the inner circumferential surface 22 that are located at both ends of the inner circumferential surface 22 by inclined surfaces 231 . The inclined edges 23 prevent the engagement teeth 221 from first engaging at both ends of the inner circumferential surface 22, allowing the entire engagement teeth 221 to engage evenly with the tendon 3, making it easy to remove the wedge member 2 after it has been set in place. This ease of attachment and detachment makes it possible to reuse the wedge structure 1, making it suitable for repeated setting and dismantling. As a result, it is possible to improve the efficiency and reliability of work when replacing tendons and their connecting members while maintaining tension.

[0017] <4> removal angle The inclined edge portion 23 is defined by the angle (hereinafter referred to as the removal angle α) formed by the line connecting the end portion on the inner circumferential surface 22 side and the central axis O of the wedge member 2 and the line connecting the end portion on the opposing surface 21 side and the central axis O (Figure 4). The removal angle α is preferably in the range of 15 degrees to 17 degrees. If the removal angle α is less than 15 degrees, the engagement teeth 221 at both ends of the inner circumferential surface 22 cannot be sufficiently prevented from first engaging, which may result in uneven engagement depth. On the other hand, if the removal angle α is more than 17 degrees, the remaining range of the engagement teeth 221 becomes excessively narrow, which may affect fixing performance. By setting the removal angle α in the range of 15 degrees or more and 17 degrees or less depending on the diameter of the inner surface 22 of the tendon 3 and the wedge member 2, the distribution angle of the engaging teeth 221 remaining on the inner surface 22 approaches a three-split structure (approximately 120 degrees), making it easier to remove the wedge member 2 and significantly improving the workability of installation and dismantling.

[0018] <5> Inclined surface angle The inclined surface 231 constituting the inclined edge portion 23 is preferably inclined at an inclination angle β of 50 degrees or more and 80 degrees or less with respect to a plane that is parallel to the opposing surface 21 and includes the central axis O. If the inclination angle β of the inclined surface 231 exceeds 80 degrees, the range of the engaging teeth 221 removed by the inclined surface 231 becomes too narrow, making it difficult to prevent the ends of the engaging teeth 221 from being sufficiently removed and becoming prematurely bitten in. On the other hand, if the inclination angle β is less than 50 degrees, the engaging teeth 221 side of the inclined surface 231 may bite into the tendon 3 prematurely, which may result in a biased biting depth into the tendon 3. By appropriately setting the inclination angle β of the inclined surface 231, the entire engaging tooth 221 can be uniformly engaged with the tendon 3, making it easier to remove the wedge member 2 after it has been fixed. [Explanation of symbols]

[0019] 1. Wedge structure 2 Wedge members 21 Opposite surface 22 Inner surface 221 Engaging teeth 23 Sloped edge 231 Inclined surface (first removal surface) 232 Second removal surface 3 Tensors 4. Jacket 41 Insertion hole O center axis α removal angle β Tilt angle

Claims

1. 1. A wedge structure for use in an intermediate anchorage of a tendon, comprising: a pair of wedge members each having a truncated cone shape and split into two along a central axis, the pair of wedge members forming a hollow portion along the central axis; an inner circumferential surface forming the hollow portion has engaging teeth that can engage with the tension member that is inserted therethrough; the pair of wedge members have opposing surfaces that face each other at the dividing position, The present invention is characterized in that an inclined edge portion having an inclined surface inclined with respect to the opposing surface is provided at an intersection between the opposing surface and the inner peripheral surface. Wedge structure.

2. The inclined edge portion is formed by the inclined surface extending from the opposing surface to the inner circumferential surface. The wedge structure of claim 1 .

3. The inclined edge portion comprises a first removed surface which is the inclined surface continuing with the inner circumferential surface, and a second removed surface which is continuing with the first removed surface and the opposing surface. The wedge structure of claim 1 .

4. The angle formed by a line connecting the end of the inclined edge portion on the inner peripheral surface side to the central axis and a line connecting the end of the inclined edge portion on the opposing surface side to the central axis is 15 degrees or more and 17 degrees or less. The wedge structure of claim 1 .

5. The inclined surface is parallel to the opposing surface and is inclined at an angle of 50 degrees or more and 80 degrees or less with respect to a plane including the central axis. The wedge structure of claim 1 .

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