Strand anchor

Abstract

To prevent a breakage or a crack at an end of a wedge member.SOLUTION: An anchorage body of a strand 1 has a holding member 2 including a first open hole 21 with a first opening 22 and a second opening 23 at both ends, wherein the first opening 22 is larger than the second opening 23, and a wedge member 3 inserted from the first opening 22 into a first open hole 21. The wedge member 3 has a second open hole 34 fixing a strand S and is divided into a plurality of small pieces in a peripheral direction around the second open hole 34. The wedge member 3 has a first part 31 and a second part 32 connected at a first connection part 33 between the first opening 22 and the second opening 23. The first part 31 is situated at the first opening 22 side and is separated from an inner surface of the first open hole 21. The second part 32 is situated at the second opening 23 side and is in contact with the inner surface of the first open hole 21.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an anchor for strands. [Background technology]

[0002] Tendons are used to apply compressive force to concrete structures to produce prestressed concrete. The tendons are inserted into the concrete structure, tensioned by jacks and other tools, and fixed to anchors that are fixed to the concrete structure to maintain the tension.

[0003] Patent Document 1 discloses an example of a fixing body for a strand. The fixing body has a holding member also called a female cone and a wedge member also called a male cone. The wedge member is inserted into a through hole of the holding member. The through hole has an outer diameter that gradually decreases from an insertion opening into which the wedge member is inserted toward the back, and the wedge member also has a shape complementary to the through hole. When the wedge member is pushed into the holding member with a strand inserted into a through hole provided in the center of the wedge member, the wedge member engages with the inner surface of the through hole, and the wedge member is firmly fixed to the holding member. As a result, the strand is firmly fixed by the wedge member. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-113154 A Summary of the Invention [Problem to be solved by the invention]

[0005] After the wedge member is pressed into the holding member to complete the fixing body, cracks may occur near the rear end of the wedge member in the insertion direction. One reason for this is thought to be that the force (support pressure and friction force) that the wedge member receives from the holding member is greater at the rear end. The occurrence of cracks not only reduces the value of the product, but depending on the type of cracks, may also have a negative effect on the performance of the fixing body. This problem is particularly likely to become apparent when the wedge member is made of resin, which is prone to cracks.

[0006] An object of the present invention is to provide an anchor for a strand that is less susceptible to breakage or cracking at the end of the wedge member. [Means for solving the problem]

[0007] The anchor for the strand of the present invention comprises a holding member having a first through hole with a first opening and a second opening at both ends, the first opening being larger than the second opening; It is made of resin, and a wedge member inserted into the first through hole from the first opening. The wedge member has a second through hole for fixing the strand and is divided into a plurality of small pieces in a circumferential direction around the second through hole. The wedge member has a first portion and a second portion connected at a first connection portion between the first opening and the second opening. The first portion is located on the side of the first opening and is spaced apart from the inner surface of the first through hole. The second portion is located on the side of the second opening and is in contact with the inner surface of the first through hole. The first through hole has a first hole portion and a second hole portion connected by a second connection portion between the first opening and the second opening, the first hole portion extends from the first opening to the second connection portion and the second hole portion extends from the second connection portion to the second opening, the inner diameter of the second hole portion decreases at a constant ratio from the second connection portion to the second opening, the inner diameter of the first opening is smaller than the inner diameter of a virtual opening obtained by extending the inner surface of the second hole portion to the position of the first opening at a constant ratio, and the inner diameter of the first hole portion decreases from the first opening to the second connection portion at a constant ratio that is smaller than the constant ratio. In one embodiment, the outer diameter of the first portion decreases away from the first connection portion, and in a cross section passing through the center line of the wedge member, the first portion has an arc-shaped surface connecting the first connection portion and the end face on the first opening side, and when the multiple small pieces are brought into circumferential contact with each other, the diameter of the end face on the first opening side of the wedge member is D, and the radius of the arc is in the range of 0.1D or more and 0.3D or less. In another embodiment, the first through hole and the wedge member have a common centerline, and an angle that a side surface of the second portion makes with the centerline is greater than an angle that an inner surface of the second hole makes with the centerline. Effect of the Invention

[0008] According to the present invention, it is possible to provide a strand anchor in which breakage or cracks are less likely to occur at the end of the wedge member. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a conceptual diagram of a fixing body for a strand according to the first embodiment. [Diagram 2] 2A-2A, 2B-2B, and 2C-2C are schematic cross-sectional views of the fixing member taken along lines 2A-2A, 2B-2B, and 2C-2C in FIG. [Diagram 3] 1A and 1B are a conceptual diagram and a diagram showing an example of a breakage mode of a conventional fixing body. [Figure 4] FIG. 11 is a conceptual diagram of a fixing body for a strand according to a second embodiment. [Diagram 5] FIG. 11 is a conceptual diagram of a fixing body for a strand according to a third embodiment. [Figure 6] FIG. 13 is a conceptual diagram of a fixing body for a strand according to a fourth embodiment. [Figure 7] 4 is a schematic diagram showing a method of attaching an anchor to a strand. FIG. [Figure 8] FIG. 1 is a diagram showing a test device and test results of the strand of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, several embodiments of the present invention will be described with reference to the drawings. In the following description, the axial direction X means the longitudinal direction of the first through hole 21 and the wedge member 3 of the retaining member 2. The center line of the first through hole 21, the center line of the second through hole 34, the center line of the wedge member 3, and the center line of the strand S all overlap, and are collectively referred to as the center line C. In the drawings, the direction in which the wedge member 3 is inserted is indicated as the +X direction, and the opposite direction is indicated as the -X direction.

[0011] FIG. 1(a) is a cross-sectional view of a strand anchor (hereinafter, referred to as anchor 1) according to a first embodiment of the present invention, and FIG. 1(b) is an enlarged view of part A in FIG. 1(a). For convenience, FIG. 1(b) shows the holding member 2 and the wedge member 3 separated in the vertical direction, but they are in contact in section B. FIGS. 2(a) to 2(c) are schematic cross-sectional views of the anchor 1 taken along lines 2A-2A, 2B-2B, and 2C-2C in FIG. 1(a), respectively. The anchor 1 has a holding member 2 and a wedge member 3 as main members. The holding member 2 is a member that holds the wedge member 3, and has a first through hole 21 with a first opening 22 and a second opening 23 at both ends. The holding member 2 is embedded in a structure 4 such as reinforced concrete, that is, an object to which a compressive force is applied by the strand S. The sheath 11 into which the strand S is inserted is embedded in the structure 4, and after the strand S is tensioned, the inside of the sheath 11 is filled with grout 12. The first through hole 21 has a circular cross-sectional shape perpendicular to the axial direction X at all positions in the axial direction X, and the center of the cross-section is on a straight line, that is, on the center line C of the first through hole 21. The first opening 22 is larger than the second opening 23. In this embodiment, the inner diameter of the first through hole 21 is maximum at the first opening 22, gradually decreases toward the second opening 23, and is minimum at the second opening 23. The holding member 2 has a generally cylindrical shape, and the outer diameter is constant in the axial direction X. The holding member 2 is made of resin such as glass fiber reinforced plastic (GFRP) and carbon fiber reinforced plastic (CFRP), and is therefore lightweight and has excellent strength. The holding member 2 can also be made of steel.

[0012] The wedge member 3 is a member for fixing the strand S. The wedge member 3 is inserted into the first through hole 21 from the first opening 22 toward the second opening 23. The wedge member 3 is housed inside the first through hole 21 over its entire length. The wedge member 3 has a second through hole 34 for fixing the strand S, and is divided into a plurality of small pieces 35 in the circumferential direction around the second through hole 34. In this embodiment, the wedge member 3 is divided into two at 180° intervals, but the number of divisions is not limited, and the wedge member 3 may be divided into three at 120° intervals, for example. Since the strand S is generally made by twisting a plurality of steel or resin wires, the more the number of divisions, the easier it is to ensure adhesion with each wire, but the fewer the number of divisions, the easier it is to uniformly press the small pieces 35 into the holding member 2. The wedge members 3 are separated from each other in the circumferential direction when they are inserted into the holding member 2 with the strand S fixed thereto. Therefore, to be precise, the second through hole 34 is a cavity with a circular cross section formed inside the recessed portion 36 provided on the inner surface of the two wedge members 3. The second through hole 34 has a circular cross section perpendicular to the axial direction X at all positions in the axial direction X, and the center of the cross section is on a straight line, i.e., on the center line C of the second through hole 34. The wedge members 3 are made of resin such as GFRP or CFRP, and are therefore lightweight and have excellent strength.

[0013] The wedge member 3 has a first portion 31 and a second portion 32. The first portion 31 and the second portion 32 are connected to each other at a first connection portion 33 between the first opening 22 and the second opening 23. The first portion 31 is located on the side of the first opening 22, and the second portion 32 is located on the side of the second opening 23. The first portion 31 is spaced apart from the inner surface of the first through hole 21, and the second portion 32 is in contact with the inner surface of the first through hole 21. The outer diameter of the first portion 31 is constant and is the same as the outer diameter of the first connection portion 33. The outer diameter of the second portion 32 decreases at a constant rate from the first connection portion 33 to the front end in the insertion direction. The outer diameter is defined here when the wedge member 3 is pressed into the first through hole 21 and the fixing body 1 is completed.

[0014] The second portion 32 of the wedge member 3 before being inserted into the first through hole 21 has a side surface that is slightly larger than the inner surface of the second hole portion 25 (described later) of the first through hole 21. In other words, the angle θ3 between the side surface of the second portion 32 and the center line C is slightly larger than the angle θ2 between the inner surface of the second hole portion 25 and the center line C. Therefore, the support pressure that the second portion 32 receives from the holding member 2 and the frictional force generated between the second portion 32 and the holding member 2 become larger toward the rear in the insertion direction and are maximized at the first connection portion 33. The second portion 32 of the wedge member 3 receives a larger support pressure toward the rear in the insertion direction and is strongly compressed, and as a result, the strand S can be gripped with a larger force. This allows a stable tension to be applied to the strand S, and makes it less likely that the wedge member 3 will bite through the strand S.

[0015] FIG. 3(a) shows a conventional fixing body 101. The first through hole 121 of the holding member 102 and the wedge member 103 have a generally complementary shape, and the entire side surface of the wedge member 103 is in contact with the inner surface of the first through hole 121. In such a fixing body 101, as shown in part A of FIG. 3(a) and FIG. 3(b), the wedge member 103 is likely to break or crack at the rear end in the insertion direction. This is considered to be because, as described above, the support pressure that the wedge member 103 receives from the holding member 102 and the frictional force generated between the wedge member 103 and the holding member 102 are maximum at the rear end. FIG. 3(b) shows a failure mode in which the rear end surface of the wedge member 103 peels off, but cracks may also occur in the axial direction.

[0016] In this embodiment, the first portion 31 is provided at the rear of the wedge member 3 in the insertion direction, away from the first through hole 21, so that the occurrence of splits or cracks at the rear end of the wedge member 3 can be suppressed. The second portion 32 receives a support pressure from the holding member 2, and is compressed and deformed to grip the strand S. The second portion 32 generates a hoop stress (circumferential compressive stress) due to the support pressure from the holding member 2. The hoop stress is transmitted to the first portion 31 by the rigidity of the wedge member 3. As a result, the first portion 31 of the wedge member 3 is compressed radially inward, gripping the strand S. In other words, the compressive deformation generated in the second portion 32 also generates a compressive deformation in the first portion 31, and a force for gripping the strand S is generated. In this way, in the fixing body 1 of this embodiment, splits or cracks are less likely to occur, while the performance of gripping the strand S is maintained. In this embodiment, it is considered that the position where the wedge member 3 receives the maximum support pressure moves to the first connection portion 33, but since the support pressure at this position is smaller than the support pressure at the rear end of the wedge member 103 of the conventional fixing body 101, the possibility of breakage or cracks occurring at the first connection portion 33 is small.

[0017] The length of the first portion 31 is preferably in the range of 0.1D or more and 1.0D or less. Here, D is the diameter of the end face 27 on the first opening 22 side of the wedge member 3 when the multiple small pieces 35 are closely contacted with each other in the circumferential direction. It is believed that by setting the length of the first portion 31 in this range, the compressive deformation occurring in the second portion 32 can be effectively transmitted to the first portion 31, and the gripping force for the strand S can be maintained.

[0018] The first through hole 21 has a first hole portion 24 and a second hole portion 25. The first hole portion 24 and the second hole portion 25 are connected to each other at a second connection portion 26 between the first opening 22 and the second opening 23. The first hole portion 24 extends from the first opening 22 to the second connection portion 26, and the second hole portion 25 extends from the second connection portion 26 to the second opening 23. The inner diameter of the second hole portion 25 decreases at a constant ratio (second ratio) from the second connection portion 26 to the second opening 23. In contrast, the inner diameter of the first hole portion 24 decreases from the first opening 22 to the second connection portion 26 at a constant ratio (first ratio) smaller than the second ratio. In other words, the angle θ1 that the inner surface of the first hole 24 makes with the center line C is constant over its entire length, and the angle θ2 that the inner surface of the second hole 25 makes with the center line C is constant over its entire length, and θ1<θ2. As a result, the inner diameter of the first opening 22 becomes smaller than the inner diameter of the imaginary opening 27 obtained on the plane H including the first opening 22 by extending the inner surface of the second hole 25 to the position of the first opening 22 at the second ratio. Since the outer diameter of the holding member 2 is determined by the inner diameter of the first opening 22 and the required thickness of the holding member 2, when the inner diameter of the first opening 22 is reduced from D2 to D1, the outer diameter D3 of the holding member 2 also becomes smaller accordingly. The fixing bodies 1 may be installed in a staggered pattern in large numbers, and when the holding member 2 becomes smaller, the range required for fixing is also reduced, leading to the rationalization of structures and construction. In addition, it becomes possible to install more strands S in a certain area.

[0019] The shapes of the first through hole 21 and the first hole portion 24 are not limited as long as the first portion 31 is separated from the first through hole 21. For example, in one embodiment, the inner diameter of the first hole portion 24 may be constant from the first opening 22 to the second connecting portion 26. In this case, the inner diameter of the first opening 22 is minimum, and the outer diameter of the holding member 2 is also minimum. In this case, it is preferable that the outer diameter of the first portion 31 is also constant. In another embodiment, the outer diameter of the first portion 31 may gradually increase from the first connecting portion 33 toward the rear end in the insertion direction. In this case, it is preferable that the rate of change of the outer diameter of the first portion 31 is equal to or smaller than the rate of change of the inner diameter of the first hole portion 24.

[0020] An example of the effect of reducing the outer diameter D3 of the holding member 2 will be described in more detail. When an aramid rod is used as the strand S, the axial length of the resin wedge member 3 is considered to be about 200 mm. Assuming that the outer diameter of the strand S is 15.2 mm and the thickness of the part with the narrowest diameter at the front end of the wedge member 3 in the insertion direction is 5 mm, the outer diameter of the front end is 25.2 mm (15.2 + 2 × 5 mm). If the inclination angle of the side of the wedge member 3 is 6°, the outer diameter at the rear end 200 mm away is 67.2 mm (25.2 + 2 × 200 mm × tan (6 °)). If the inclination angle in the range of 1.0D (= 67.2 mm) from the rear end is 0°, the diameter of the rear end is 53.1 mm (25.2 + 2 × 132.8 mm × tan (6 °)), which can be suppressed to about 80% of the outer diameter. This effect becomes larger when many strands S are arranged. If the wedge member 3 is long, this effect becomes even greater.

[0021] The second connection portion 26 is preferably located between the first connection portion 33 and the first opening 22. The wedge member 3 is gradually compressed while being inserted into the first through hole 21, but if the second connection portion 26 were at the same position as the first connection portion 33 or further forward in the insertion direction than the first connection portion 33, the first connection portion 33 of the wedge member 3 would get caught on the inner surface of the first hole portion 24, which may prevent smooth insertion. By providing the first connection portion 33 further rearward in the insertion direction than the second connection portion 26, the first connection portion 33 comes into contact with the second hole portion 25, allowing the wedge member 3 to be inserted smoothly.

[0022] FIG. 4(a) is a cross-sectional view of the fixing body 1 according to the second embodiment, and FIG. 4(b) is an enlarged view of part D in FIG. 4(a), showing the rear part of the wedge member 3 in the insertion direction. In this embodiment, the outer diameter of the first part 31 decreases with increasing distance from the first connecting part 33. More specifically, the rear end of the wedge member 3 in the insertion direction is rounded (R chamfered). As a result, in a cross section passing through the center line C of the wedge member 3, the first part 31 has a circular arc surface connecting the first connecting part 33 and the end face 27 on the first opening 22 side. Instead of R chamfering, chamfering such as C chamfering may be performed so that the chamfered part becomes flat. In either case, the rear end of the wedge member 3 does not contact the first through hole 21, so that the same effect as in the first embodiment can be obtained. It is preferable that the radius of the arc of the R chamfer is in the range of 0.1D or more and 0.3D or less. Also in this embodiment, the inner surface of the first through hole 21 facing the first portion 31 can be parallel to the axial direction C, so that the effect of reducing the inner diameter of the first opening 22 can be obtained.

[0023] Although the holding member 2 in the above-described embodiment is provided for each strand S, it may be one that fixes a large number of strands S together. FIG. 5(a) is a cross-sectional view of the holding member 2 of the third embodiment, and FIG. 5(b) is a side view taken along line AA in FIG. 5(a). The holding member 2 is provided with a total of 12 first through holes 21 on two concentric circles, and the wedge members 3 and strands S are passed through each of the first through holes 21. The shapes of the first through holes 21 and the wedge members 3 are the same as those in the first and second embodiments. In particular, by adopting the wedge member 3 of the first embodiment, the inner diameter of the first opening 22 of the first through hole 21 is reduced, and therefore it is possible to reduce the outer diameter of the holding member 2.

[0024] The retaining member 2 can also be provided on the outside of the structure 4. FIG. 6 shows a cross-sectional view of the retaining member 2 of the fourth embodiment. A hollow cylindrical outer tube 5 is provided on the outside of the retaining member 2, one end of the outer tube 5 is opened, and a flange 6 that protrudes inward is provided at the other end. The retaining member 2 is attached to the outer tube 5, and the wedge member 3 with the strand S passed through it is pushed into the first through hole 21 of the retaining member 2. At this time, the flange 6 restricts the movement of the retaining member 2 in the +X direction. As a result, the retaining member 2 is held in a predetermined position relative to the surface of the structure 4, and the wedge member 3 is fixed to the retaining member 2.

[0025] In the embodiment described above, the rear end of the wedge member 3 in the insertion direction is contained within the first through hole 21, but it may protrude from the first through hole 21. In this case as well, by providing a part of the first portion 31 inside the first through hole 21, it is possible to achieve the same effect as in the above embodiment.

[0026] Here, referring to FIG. 7, a method of mounting the fixing body 1 will be briefly described. First, as shown in FIG. 7(a), the holding member 2 is attached to the structure 4 through which the strand S is inserted by an appropriate means such as an anchor. The strand S is inserted through the wedge member 3, but the wedge member 3 is not fixed to the holding member 2. Next, as shown in FIG. 7(b), the jack 7 is set on the fixing body 1. The strand S is inserted through the tensioning wedge member 8 provided on the jack 7, and the strand S is fixed by the tensioning wedge member 8. Next, as shown in FIG. 7(c), the jack 7 is operated to tension the strand S. Since the strand S is fixed by the tensioning wedge member 8 but not by the fixing body 1, the tensioned and stretched strand S moves inside the second through hole 34 of the wedge member 3 of the fixing body 1 relative to the wedge member 3. Next, as shown in FIG. 7(d), the wedge member 3 of the fixing body 1 is pushed into the first through hole 21 of the holding member 2 by the pushing jig 9 provided on the jack 7 to fix the strand S. At this time, the strand S is fixed to the tensioning wedge member 8. Next, as shown in FIG. 7(e), the strand S is released from the tensioning wedge member 8 and cut at a predetermined position P outside the fixing body 1. In the tensioning process of the strand S shown in FIG. 7(c), if sufficient tension (elongation) cannot be obtained due to the stroke of the jack 7, the wedge member 3 of the fixing body 1 is lightly pushed into the first through hole 21 of the holding member 2 to temporarily fix the strand S. Thereafter, the tensioning wedge member 8 is released from the strand S, the jack 7 is returned to its original position, the strand S is fixed by the tensioning wedge member 8, and the jack 7 is operated again. The wedge member 3 comes out of the first through hole 21, so that the strand S can be further tensioned. The above steps are repeated until a predetermined tension is applied to the strand S, and then the step shown in Fig. 7(e) is carried out.

[0027] Next, as an example, the strand S was tensioned using the anchor 1 of this embodiment. Figure 8(a) shows a test device. Both ends of the strand S of a carbon fiber composite cable (CFCC) were fixed by the anchors 1 and 13, and the reaction frame 10 and the jack 11 were set between the anchors 1 and 13. Iron plates 12 were attached to both ends of the reaction frame 10, and one of the anchors 13 and the jack 11 were fixed. The anchor 1 on the reaction frame 10 side used the wedge member 3 with R-chamfered ends shown in the second embodiment. The jack 11 was operated to tension the strand S. As shown in Figure 8(b), the strand S was gradually tensioned and held for 10 minutes, after which the strand S broke inside the anchor 1. No breaks or cracks occurred in the wedge member 3. [Explanation of symbols]

[0028] 1 Strand anchor 2 Retaining member 21 First through hole 22 First opening 23 Second Opening 24 First hole 25 Second hole 26 Second Connection 3 Wedge 31 First Part 32 Second Part 33 First Connection 34 Second through hole S Strand

Claims

1. a holding member including a first through hole having a first opening and a second opening at both ends, the first opening being larger than the second opening; a wedge member made of resin and inserted into the first through hole from the first opening, The wedge member has a second through hole for fixing the strand, and is divided into a plurality of small pieces in a circumferential direction around the second through hole; the wedge member has a first portion and a second portion connected at a first connection portion between the first opening and the second opening, the first portion being located on the side of the first opening and spaced apart from an inner surface of the first through hole, and the second portion being located on the side of the second opening and in contact with the inner surface of the first through hole; the first through hole has a first hole portion and a second hole portion connected by a second connection portion between the first opening and the second opening, the first hole portion extending from the first opening to the second connection portion, and the second hole portion extending from the second connection portion to the second opening; an inner diameter of the second hole portion decreases at a constant rate from the second connection portion to the second opening, and an inner diameter of the first opening is smaller than an inner diameter of a virtual opening obtained by extending an inner surface of the second hole portion to the position of the first opening at the constant rate; an inner diameter of the first hole portion decreases from the first opening to the second connection portion at a constant rate smaller than the constant rate; an outer diameter of the first portion decreases with increasing distance from the first connecting portion; a strand anchoring body, in a cross section passing through the center line of the wedge member, the first portion has an arc surface connecting the first connection portion and the end face on the first opening side, and when the plurality of small pieces are brought into close contact with each other in the circumferential direction, the diameter of the end face on the first opening side of the wedge member is D, and the radius of the arc is in the range of 0.1D to 0.3D.

2. A strand fixation body as described in claim 1, wherein the length of the first portion is in the range of 0.1D or more and 1.0D or less.

3. A retaining member having a first through hole with a first opening and a second opening at both ends, the first opening being larger than the second opening; a wedge member made of resin and inserted into the first through hole from the first opening, The wedge member has a second through hole for fixing the strand, and is divided into a plurality of small pieces in a circumferential direction around the second through hole; the wedge member has a first portion and a second portion connected at a first connection portion between the first opening and the second opening, the first portion being located on the side of the first opening and spaced apart from an inner surface of the first through hole, and the second portion being located on the side of the second opening and in contact with the inner surface of the first through hole; the first through hole has a first hole portion and a second hole portion connected by a second connection portion between the first opening and the second opening, the first hole portion extending from the first opening to the second connection portion, and the second hole portion extending from the second connection portion to the second opening; an inner diameter of the second hole portion decreases at a constant rate from the second connection portion to the second opening, and an inner diameter of the first opening is smaller than an inner diameter of a virtual opening obtained by extending an inner surface of the second hole portion to the position of the first opening at the constant rate; an inner diameter of the first hole portion decreases from the first opening to the second connection portion at a constant rate smaller than the constant rate; A strand anchor, wherein the first through hole and the wedge member have a common center line, and the angle that the side surface of the second portion makes with the center line is greater than the angle that the inner surface of the second hole portion makes with the center line.

4. 4. The strand anchor according to claim 3, wherein when the plurality of small pieces are brought into close contact with each other in the circumferential direction, the length of the first portion is in the range of 0.1D or more and 1.0D or less, where D is the diameter of the end face of the first opening side of the wedge member.

5. The anchor for strands according to claim 1 , wherein the second connection portion is between the first connection portion and the first opening.

6. The anchor for the strands according to claim 1 , wherein the holding member is made of a resin.

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