JP6636275B2 - Anchor bolt and method of construction of anchor bolt - Google Patents

Description

  The present invention relates to an anchor bolt and a method for installing an anchor bolt.

  In order to reinforce or expand an existing concrete structure, a rod-shaped anchor bolt may be buried in an anchor hole formed in the existing concrete structure. For example, Patent Literature 1 discloses a method for installing an anchor bolt in which an anchor bolt is fixed in an anchor hole by inserting the anchor bolt into the anchor hole and pushing in and expanding a metal fitting of the anchor bolt with a jig. I have.

JP-A-2004-162295

  By the way, it is desired that the anchor bolt buried in the anchor hole be improved in tensile strength and shear strength and the reliability of the anchor bolt.

  Therefore, an object of the present invention is to provide an anchor bolt and a method for installing the anchor bolt, which can improve the strength of the anchor bolt embedded in the anchor hole against the tensile force and the shear force and the reliability of the anchor bolt.

  The present invention relates to a rod-shaped anchor bolt buried in an anchor hole formed in an existing concrete structure, wherein the rod-shaped anchor bolt has a pair of ends which are outside the anchor hole when buried in the anchor hole. A base end which is an end on the side where the anchor is located, and a tip which is an end on the side which is located inside the anchor hole when the anchor bolt is buried in the anchor hole among a pair of ends of the rod-shaped anchor bolt; A main body portion extending halfway from the end portion to the distal end portion, a reduced diameter portion extending halfway from the main body portion to the distal end portion, and having a thickness smaller than the thickness of the main body portion; A diameter-expanding portion extending toward the portion and having a thickness larger than the diameter of the diameter-reducing portion, between the main body portion and the diameter-reducing portion, the diameter-reducing portion, and the diameter-reducing portion and the diameter-enlarging portion And the enlarged diameter part are anchor bolts formed seamlessly and integrally.

  According to this configuration, the anchor bolt extends halfway from the main body portion on the base end side to the distal end portion, and has a reduced diameter portion having a thickness smaller than the thickness of the main body portion, and from the reduced diameter portion to the distal end portion. And a diameter-expanding portion that extends toward the center and has a thickness larger than the diameter of the diameter-reducing portion. In addition, since the portion between the main body and the reduced diameter portion, between the reduced diameter portion, between the reduced diameter portion and the enlarged diameter portion, and the enlarged diameter portion are formed seamlessly and integrally, the conventional embedded The anchor bolt embedded in the anchor hole can be improved in resistance to tensile and shear forces and the reliability of the anchor bolt, as compared with an anchor bolt in which an enlarged diameter portion is formed by a jig later.

  Further, in this case, it is preferable to further include an enlarged taper portion between the reduced diameter portion and the enlarged diameter portion, the diameter gradually increasing from the reduced diameter portion to the enlarged diameter portion.

  According to this configuration, the diameter between the reduced diameter portion and the enlarged diameter portion gradually increases from the reduced diameter portion to the enlarged diameter portion. When a force is applied, a force acts in a direction in which the anchor hole is expanded from the enlarged diameter tapered portion via a filler such as grout, so that it is possible to further improve the strength of the anchor bolt against the tensile force.

  In addition, it is preferable that a tapered portion having a diameter gradually reduced from the main body to the reduced diameter portion is further provided between the main body and the reduced diameter portion.

  According to this configuration, the diameter of the filler gradually decreases from the main body to the diameter-reduced portion. It is possible to make it easier to wrap around from the diameter part to the main body part, and to make it easier to embed the anchor bolt by the anchor hole.

  Further, a flat portion may be provided on the outer periphery of the enlarged diameter portion.

  According to this configuration, the filler is inserted into the anchor hole into which the filler such as grout has been injected beforehand by the gap generated between the flat portion on the outer periphery of the enlarged diameter portion and the wall surface of the anchor hole. From the diameter to the reduced diameter portion, and a gap between the reduced diameter portion and the filler can be prevented.

  The present invention also provides an anchor hole forming step of forming an anchor hole in an existing concrete structure, a filler injecting step of injecting a filler into the anchor hole formed by the anchor hole forming step, and a filling step by a filler injecting step. And an anchor inserting step of inserting the anchor bolt of the present invention into an anchor hole into which a material has been injected.

  In this case, in the anchor hole forming step, the width of the anchor hole on the inner side of the existing concrete structure may be larger than the width of the anchor hole on the outer side of the existing concrete structure.

  ADVANTAGE OF THE INVENTION According to the anchor bolt of this invention, the durability with respect to the tensile force of the anchor bolt embedded in the anchor hole and the mechanical strength of an anchor bolt can be improved.

(A) is a side view of the anchor bolt according to the first embodiment, (B) is a cross-sectional view taken along line BB of (A), and (C) is a cross-section taken along line CC of (A). It is sight. It is a perspective view which shows the frame member attached to the concrete wall of the existing concrete structure by the anchor bolt of FIG. 1 (A)-(C) embedded in the anchor hole formed in the existing concrete structure. (A), (B), (C), (D), and (E) are diagrams showing a method for installing an anchor bolt according to the first embodiment. It is a figure which shows the force which acts on a filler and an anchor hole from a diameter expansion taper part, when a tensile force acts on the anchor bolt embedded in the anchor hole in 1st Embodiment. (A), (B) and (C) are diagrams showing a method of installing an anchor bolt according to a second embodiment. It is a figure which shows the force which acts on a filler and an anchor hole from a diameter expansion taper part, when a tensile force acts on the anchor bolt embedded in the anchor hole in 2nd Embodiment. (A) is a side view of the anchor bolt according to the third embodiment, (B) is a cross-sectional view taken along line BB of (A), and (C) is a cross-sectional view taken along line CC of (A). It is sight.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The anchor bolt 1a according to the first embodiment shown in FIGS. 1 (A) to 1 (C) has a rod-like shape and is formed on an existing concrete structure in order to reinforce or add to the existing concrete structure. It is buried in the anchor hole. As shown in FIGS. 1A to 1C, the anchor bolt 1a has a columnar shape as a whole, more specifically. The anchor bolt 1a has a base end 3 which is an end located outside the anchor hole when embedded in the anchor hole, and a base end 3 between the pair of ends of the rod-shaped anchor bolt 1a when embedded in the anchor hole. And a tip 2 which is an end located on the side located inside the anchor hole.

  The anchor bolt 1a has a main body 6 extending halfway from the base end portion 3 to the distal end portion 2, and extends halfway from the main body portion 6 to the distal end portion 2, and has a thickness smaller than the thickness of the main body portion 6. And a large diameter portion 9 extending from the reduced diameter portion 8 toward the distal end portion 2 and having a thickness larger than the thickness of the reduced diameter portion 8. The anchor bolt 1a includes a tapered diameter portion 10 between the main body portion 6 and the reduced diameter portion 8, the diameter of which gradually decreases from the main body portion 6 to the reduced diameter portion 8. The anchor bolt 1 a has a tapered portion 11 between the reduced diameter portion 8 and the enlarged diameter portion 9, the diameter of which gradually increases from the reduced diameter portion 8 to the enlarged diameter portion 9. In addition, in this embodiment, since the anchor bolt 1a has a columnar shape, the thickness means the diameter. However, in the case where the anchor bolt 1a has an elliptical shape or a polygonal shape in a cross-sectional view of the anchor bolt 1a, the thickness means an arbitrary width in the cross-sectional view of the anchor bolt 1a.

  A tapered portion 10 between the main body 6 and the reduced diameter portion 8, a tapered portion 11 between the reduced diameter portion 8, a tapered portion 11 between the reduced diameter portion 8 and the enlarged diameter portion 9, and a tapered portion 9. Are seamlessly and integrally formed. The main body portion 6, the reduced diameter taper portion 10, the reduced diameter portion 8, the increased diameter taper portion 11, and the increased diameter portion 9 can be manufactured by, for example, lathe processing of a round steel material formed into a cylindrical shape. Further, the main body 6, the reduced diameter tapered portion 10, the reduced diameter portion 8, the increased diameter tapered portion 11, and the increased diameter portion 9 can also be manufactured by casting a steel material.

  Examples of the material of the anchor bolt 1a include an SS material which is a rolled steel material for general structures, an SN material which is a rolled steel material for building structures, and a rolled steel material for welded structures specified in JIS (Japanese Industrial Standards). Can be applied.

  The main body 6 includes a threaded portion 4 having a threaded portion for attaching a nut to the outer peripheral surface on the base end portion 3 side, and an unthreaded cylindrical portion 5 on the distal end portion 2 side. Have. In the anchor bolt 1a of the present embodiment, since the strength and reliability against the tensile force and the shear force are excellent, the number of constructions can be reduced as compared with the related art. Therefore, the diameter of the main body 6 is larger than before. The diameter of the main body 6 can be, for example, 20 to 100 mm, and is 60 mm in the present embodiment.

  As shown in FIGS. 1A and 1B, near the boundary between the cylindrical portion 5 and the tapered portion 10, a spacer 7, which is a small cylindrical protrusion protruding from the outer peripheral surface of the cylindrical portion 5. Are provided, for example. The three spacers 7 near the boundary between the cylindrical portion 5 and the reduced diameter tapered portion 10 are located at a position where the distance along the central axis of the anchor bolt 1a is equidistant from the boundary between the cylindrical portion 5 and the reduced diameter tapered portion 10. Are located. As shown in FIG. 1B, in a cross-sectional view of the anchor bolt 1 a, each of the three spacers 7 near the boundary between the columnar portion 5 and the tapered portion 10 has a spacer 7 that is adjacent to each other. Lines connecting the center of the cylindrical portion 5 are arranged at substantially equal intervals, for example, at approximately 120 °.

  The length of each of the three spacers 7 protruding from the outer peripheral surface of the cylindrical portion 5 is substantially the same, and the length of each of the three spacers 7 in contact with the anchor hole wall surface of the anchor hole or a few mm shorter than that. Length. For example, when the diameter of the main body 6 is 60 mm and the diameter of the anchor hole is 70 mm, the length of each of the three spacers 7 protruding from the outer peripheral surface of the cylindrical portion 5 can be 5 mm. Three spacers 7 similar to the three spacers 7 near the boundary between the cylindrical portion 5 and the tapered portion 10 are provided near the boundary between the cylindrical portion 5 and the thread portion 4.

  The spacer 7 is formed, for example, by turning a round steel material formed into a cylindrical shape to form the main body 6, the reduced diameter tapered portion 10, the reduced diameter portion 8, the increased diameter tapered portion 11, and the increased diameter portion 9. The spacer 7 can be formed by embedding a spacer 7, which is a cylindrical round steel material having a smaller diameter than the main body 6, in the outer peripheral surface of the column 5. The spacer 7 can be formed together with the main body 6, the reduced diameter tapered portion 10, the reduced diameter portion 8, the increased diameter tapered portion 11, and the increased diameter portion 9 by casting a steel material. it can.

  The diameter of the reduced diameter tapered portion 10 decreases substantially uniformly from the cylindrical portion 5 to the reduced diameter portion 8. The angle formed between the outer peripheral surface of the tapered portion 10 and the central axis of the anchor bolt 1a can be, for example, 3 ° to 50 °, more preferably 10 ° to 30 °. 2 °. By setting the angle between the outer peripheral surface of the reduced diameter tapered portion 10 and the central axis of the anchor bolt 1a within the above range, the diameter of the reduced diameter tapered portion 10 can be reduced when the anchor bolt 1a is buried in the anchor hole in which the filler is injected in advance. Is sufficiently small, the filler easily flows from the reduced diameter portion 8 to the main body 6, and the force can be smoothly transmitted. The boundary between the reduced diameter portion 8 and the reduced diameter tapered portion 10 is rounded.

  The diameter of the reduced diameter portion 8 can be, for example, 40 to 60% of the diameter of the main body portion 6, and is 50% in the present embodiment. By setting the diameter of the reduced-diameter portion 8 within the above range, the diameter of the reduced-diameter portion 8 is sufficiently large. Can be secured. The length of the reduced diameter portion 8 along the central axis of the anchor bolt 1a is, for example, 0.5 to 1.5 times the diameter of the reduced diameter portion 8, and more preferably 1.8 to 1.2 times. In the present embodiment, it is 1.0 times. By setting the length of the reduced diameter portion 8 within the above range, it is possible to prevent the filler from becoming difficult to wrap around the reduced diameter portion 8 when the anchor bolt 1a is buried in the anchor hole into which the filler is previously injected. Further, the presence of the reduced diameter portion 8 causes the anchor bolt 1a to exhibit a ductile behavior when a tensile force or a shearing force acts on the structure in which the anchor bolt 1a is embedded, so that the entire structure is brittle. Can be suppressed and safety is improved.

  The diameter of the enlarged diameter tapered portion 11 gradually increases from the reduced diameter portion 8 to the enlarged diameter portion 9. The angle between the outer peripheral surface of the enlarged diameter tapered portion 11 and the central axis of the anchor bolt 1a can be, for example, 3 ° to 50 °, more preferably 10 ° to 30 °, and in the present embodiment, 20.6 °. °. By setting the angle between the outer peripheral surface of the enlarged diameter tapered portion 11 and the central axis of the anchor bolt 1a within the above range, the diameter of the enlarged diameter tapered portion 11 can be reduced when the anchor bolt 1a is buried in the anchor hole in which the filler is injected in advance. Is small enough to allow the filler to easily flow from the reduced diameter portion 8 to the main body 6, and when the angle of the enlarged diameter tapered portion 11 is sufficiently large, a tensile force acts on the anchor bolt 1a. The force for expanding the anchor hole is generated, and the proof stress is improved. The boundary between the reduced diameter portion 8 and the increased diameter tapered portion 11 is rounded.

  The diameter of the enlarged diameter portion 9 can be, for example, 80 to 120% of the diameter of the main body 6, and can be the same as the diameter of the main body 6 in the present embodiment. By making the diameter of the enlarged diameter portion 9 and the diameter of the main body portion 6 the same, lathe processing of a round steel material formed into a columnar shape makes it easy to manufacture the anchor bolt 1a. The length of the enlarged diameter portion 9 along the central axis of the anchor bolt 1a is, for example, 10 to 65% of the diameter of the enlarged diameter portion 9, and is 25% in the present embodiment. By setting the length of the enlarged diameter portion 9 along the central axis of the anchor bolt 1a within the above range, the diameter of the enlarged diameter portion 9 is sufficiently short, so that the filler does not easily flow from the enlarged diameter portion 9 to the reduced diameter portion 8. And the length of the enlarged diameter portion 9 is sufficiently long, so that a decrease in mechanical strength can be prevented. The end portion 2 side of the enlarged diameter portion 9 has a planar shape orthogonal to the central axis of the anchor bolt 1a.

  Hereinafter, a method of installing the anchor bolt 1a in the first embodiment will be described. As shown in FIG. 2, the anchor bolt 1 a according to the present embodiment is used to attach the frame member 100 to the existing concrete structure 200 in order to reinforce or add to the existing concrete structure 200. It is buried in an anchor hole formed in the object 200. The frame member 100 has a roughly H-steel shape. The frame member 100 includes a wall flange 101 and a facing flange 102 facing the wall flange 101.

  A bolt hole, which is a through hole (not shown), is provided in the wall surface flange 101. After the anchor bolt 1a embedded in the existing concrete structure 200 is passed through the bolt hole of the wall surface flange 101, the anchor bolt 1a and the wall surface flange 101 are fastened by the nut 20, so that the frame member 100 is connected to the existing concrete structure. It is attached to the object 200. In this embodiment, the width of the opposing flange 102 is smaller than the width of the wall flange 101 for the convenience of attaching the nut 20 to the anchor bolt 1a. Further, a rib plate 103 is attached between the wall surface flange 101 and the opposed flange 102 for reinforcement.

  Hereinafter, a procedure for embedding the anchor bolt 1a in the existing concrete structure 200 in the first embodiment will be described. First, the arrangement position of the reinforcing bars of the existing concrete structure 200 is confirmed. As shown in FIG. 3A, in the anchor hole forming step, the anchor hole 201 having the anchor hole wall surface 202 in the existing concrete structure 200 is formed by the drill bit 81 while avoiding the confirmed arrangement position of the reinforcing bar. It is formed. The anchor hole 201 is formed substantially horizontally without penetrating the concrete wall of the existing concrete structure 200. In the anchor hole forming step, the anchor hole 201 is formed so that the drill bit 81 does not contact the reinforcing bar on the opposite side of the concrete wall of the existing concrete structure 200. In the present embodiment, for example, when the diameter of the main body 6 of the anchor bolt 1a is 60 mm, the anchor hole 201 having a diameter of 70 mm can be formed. The drilling residue remaining in the anchor hole 201 is removed from the anchor hole 201 by being blown off by a blower.

  As shown in FIG. 3 (B), there is a roughing process in which a roughing cutting bit 82 is inserted into the anchor hole 201 formed in the anchor hole forming process, and roughening of the anchor hole wall surface 202 is performed. Is also good. After the inside of the anchor hole 201 is cleaned, as shown in FIG. 3 (C), grout or the like is injected into the anchor hole 201 formed in the anchor hole forming step by a grout injection hose 83 as a filler injection step. Filler 250 is injected. The filler 250 has such a viscosity that the filler 250 does not flow out of the anchor hole 201 when injected into the substantially horizontal anchor hole 201. The filler 250 can be, for example, an inorganic (cement) filler.

  As shown in FIG. 3D, as an anchor insertion step, the anchor bolt 1a is inserted into the anchor hole 201 into which the filler 250 has been injected in the filler injection step. In the present embodiment, although the viscosity of the filler 250 is high, as the anchor bolt 1a is inserted into the anchor hole 201, the filler 250 is formed by the enlarged diameter portion 9, the enlarged diameter tapered portion 11, and the reduced diameter tapered portion 10. It becomes easy to turn from the tip portion 2 to the column portion 5, and a gap is hardly generated between the outer peripheral surface of the anchor bolt 1a and the filler 250. When the anchor bolt 1 a is inserted into the anchor hole 201, the anchor bolt 1 a is positioned substantially at the center of the anchor hole 201 because the spacer 7 contacts the anchor hole wall surface 202. The anchor bolt 1a is inserted into the anchor hole 201 to a position where the distal end portion 2 contacts the bottom of the anchor hole 201.

  After the anchor insertion step, the excess filler 250 overflowing from the anchor hole 201 is discharged, and the space between the anchor hole 201 and the anchor bolt 1a is sealed. As shown in FIG. 3 (E), after the thread portion 4 of the anchor bolt 1a is passed through the bolt hole 104 of the wall flange 101 of the frame member 100, the nut 20 is fastened to the thread portion 4. Thus, the frame member 100 is attached to the existing concrete structure 200. Thereafter, for example, a frame is further connected to the frame member 100, and a frame having a lower end supported by the existing concrete structure 200 can be provided.

  In the present embodiment, a reduced diameter portion 8 that extends from the main body portion 6 on the base end portion 3 side of the anchor bolt 1a to the distal end portion 2 and has a thickness smaller than the thickness of the main body portion 6 is provided. A diameter-enlarging portion 9 extending from the diameter portion 8 toward the distal end portion 2 and having a thickness larger than the diameter of the diameter-reducing portion 8. Need not be formed. Further, the portion between the main body 6 and the reduced diameter portion 8, the portion between the reduced diameter portion 8, the reduced diameter portion 8 and the enlarged diameter portion 9, and the enlarged diameter portion 9 are integrally formed without a joint. For this reason, the anchor bolt 1a buried in the anchor hole 201 has improved resistance to tensile and shear forces and reliability of the anchor bolt 1a, as compared with a conventional anchor bolt having a diameter-enlarged portion formed by a jig after being buried. be able to. Further, the anchor bolt 1a according to the present embodiment is excellent in strength and reliability against tensile force and shear force, so that the number of constructions can be reduced as compared with the related art.

  Further, in the present embodiment, the diameter of the tapered portion 11 between the reduced diameter portion 8 and the enlarged diameter portion 9 gradually increases from the reduced diameter portion 8 to the enlarged diameter portion 9 so that the anchor hole 201 can be formed. When a tensile force acts on the buried anchor bolt 1a, a force acts in a direction in which the anchor hole 201 is expanded from the enlarged diameter tapered portion 11 through a filler 250 such as grout, so that the proof stress against the tensile force of the anchor bolt 1a. Can be further improved.

  That is, as shown in FIG. 4, when a force F1 that is a tensile force acts on the anchor bolt 1a embedded in the anchor hole 201, the outer peripheral surface of the enlarged diameter tapered portion 11 is inclined in the direction of the force F1. Therefore, a force F <b> 2 in the direction of expanding the anchor hole 201 is generated by pressing the anchor hole wall surface 202 from the outer peripheral surface of the enlarged diameter tapered portion 11 via the filler 250. Therefore, for example, even if the fixing force between the filler 250 and the anchor hole wall surface 202 is weakened, it is possible to prevent the anchor bolt 1a from being pulled out from the anchor hole.

  Further, in the present embodiment, the diameter is gradually reduced from the main body portion 6 to the diameter-reduced portion 8, so that the tapered portion 10 is inserted into the anchor hole 201 in which the filler 250 such as grout is previously injected. At times, the filler 250 can be more easily wrapped from the reduced diameter portion 8 to the main body portion 6, and the anchor bolt 1 a can be more easily buried by the anchor hole 201.

  Hereinafter, a second embodiment of the present invention will be described. In the present embodiment, when the anchor bolt 1a is buried in the existing concrete structure 200, in the anchor hole forming step, the width of the anchor hole 201 on the inner side of the existing concrete structure 200 is reduced. An anchor hole 201 wider than the width of the outer side of 200 is formed. As shown in FIG. 5A, similarly to the first embodiment, as the anchor hole forming step, an anchor hole 201 having an anchor hole wall surface 202 is formed in the existing concrete structure 200 by the drill bit 81. You.

  Next, as shown in FIG. 5 (B), in the anchor hole forming step, a diameter increasing bit 84 is inserted near the bottom of the anchor hole 201 formed by the drill bit 81, and the bottom of the anchor hole 201 is formed. Then, the anchor hole enlarged portion 203 having a diameter larger than the diameter of the anchor hole 201 on the outside of the existing concrete structure 200 is formed. The width of the anchor hole 201 on the inner side of the existing concrete structure 200 (the enlarged diameter portion 203 of the anchor hole) is, for example, 1.1 to 1.7 times the width of the anchor hole 201 on the outer side of the existing concrete structure 200. And more preferably 1.2 to 1.6 times, and in the present embodiment, 1.43 times.

  In addition, as shown in FIG. 5B, in the case where the diameter of the anchor hole enlarged portion 203 gradually increases toward the bottom of the anchor hole 201, the length of the anchor hole enlarged portion 203 is changed. (The length along the central axis of the anchor hole 201 and the length of the range in which the diameter of the anchor hole 201 is larger than the diameter of the outer side of the existing concrete structure 200) is, for example, the expansion of the anchor hole. The diameter can be 0.8 to 1.6 times the diameter of the bottom of the diameter portion 203, more preferably 1.0 to 1.4 times, and in the present embodiment, 1.2 times. is there.

  After that, similarly to the first embodiment, a roughening treatment as necessary, and then a filler injecting step are performed. Further, similarly to the first embodiment, an anchor insertion step of inserting the same anchor bolt 1a into the anchor hole 201 as in the first embodiment is performed, and as shown in FIG. After the part 4 is passed through the bolt hole 104 of the wall surface flange 101 of the frame member 100, the nut 20 is fastened to the thread part 4.

  Also according to the present embodiment, the diameter between the diameter-reducing portion 8 and the diameter-enlarging portion 9 is gradually increased from the diameter-reducing portion 8 to the diameter-enlarging portion 9 so that the tapered portion 11 is buried in the anchor hole 201. When a tensile force acts on the anchor bolt 1a thus applied, a force acts in a direction in which the anchor hole 201 is expanded from the enlarged diameter tapered portion 11 through the filler 250 such as grout, so that the proof stress against the tensile force of the anchor bolt 1a is reduced. Can be improved.

  That is, as shown in FIG. 6, when a force F1 which is a tensile force acts on the anchor bolt 1a embedded in the anchor hole 201, the outer peripheral surface of the tapered portion 11 and the anchor hole of the anchor hole enlarged portion 203 are formed. Since the wall surface 202 is inclined in the direction of the force F 1, the anchor hole wall surface 202 is pressed from the outer peripheral surface of the enlarged diameter tapered portion 11 via the filler 250, and a force F 2 in the direction of expanding the anchor hole 201 is generated. Therefore, for example, even if the fixing force between the filler 250 and the anchor hole wall surface 202 is weakened, it is possible to prevent the anchor bolt 1a from being pulled out from the anchor hole.

  Hereinafter, a third embodiment of the present invention will be described. In the present embodiment, the shape of the anchor bolt is different from the above-described first and second embodiments. Hereinafter, points different from the first embodiment and the second embodiment will be described. As shown in FIGS. 7A to 7C, in the anchor bolt 1b according to the third embodiment, the angle formed between the outer peripheral surface of the tapered portion 10 and the central axis of the anchor bolt 1b is, for example, 3 °. The angle can be set to 50 °, more preferably 10 ° to 30 °, and in the present embodiment, 20.6 °. In the present embodiment, the length of the reduced diameter portion 8 along the central axis of the anchor bolt 1b is 2.33 times the diameter of the reduced diameter portion 8. The angle between the outer peripheral surface of the enlarged diameter tapered portion 11 and the central axis of the anchor bolt 1b is 20.6 ° in the present embodiment.

  As shown in FIGS. 7A and 7C, six flat portions 12 are provided on the outer periphery of the enlarged diameter portion 9 so that the enlarged diameter portion 9 forms a regular hexagonal prism. In the present embodiment, the diameter of the enlarged diameter portion 9 (the length between opposing apex angles of the enlarged diameter portion 9 forming a regular hexagonal prism in a cross-sectional view of the anchor bolt 1) is the same as the above-described first and second embodiments. The diameter of the main body 6 is the same as in the second embodiment. In the present embodiment, the length of the enlarged diameter portion 9 along the central axis of the anchor bolt 1 is 50% of the diameter of the enlarged diameter portion 9.

  A conical top 13 is provided on the side of the distal end portion 2 of the enlarged diameter portion 9 so that the enlarged diameter portion 9 forms a cone. The apex angle of the conical top 13 can be, for example, 90 ° to 170 °, more preferably 110 ° to 150 °, and in the present embodiment, 126.9 °. The other points are the same as the above-described first embodiment and second embodiment.

  In the present embodiment, when the filler 250 is inserted into the anchor hole 201 in which the filler 250 such as grout has been injected in advance, the filler is filled with a gap formed between the flat portion 12 on the outer periphery of the enlarged diameter portion 9 and the wall surface 202 of the anchor hole. 250 can be more easily wrapped from the enlarged diameter portion 9 to the reduced diameter portion 8, and a gap can be prevented from being formed between the reduced diameter portion 8 and the filler 250.

  As described above, the embodiments of the present invention have been described. However, the present invention is not limited to the above embodiments, but may be embodied in various forms. For example, the main body part 6, the reduced diameter taper part 10, the reduced diameter part 8, the increased diameter taper part 11, and the increased diameter part 9 have an elliptical shape or a polygonal shape in a cross-sectional view of the anchor bolts 1a, 1b. Is also good. In addition, the length along the central axis of each of the anchor bolts 1a and 1b of the thread portion 4, the cylindrical portion 5, the main body portion 6, the reduced diameter taper portion 10, the reduced diameter portion 8, the increased diameter tapered portion 11, and the increased diameter portion 9 is provided. The ratio of the height and the ratio of the diameters are not limited to the above embodiment, and can be changed as appropriate, and the spacers 7 can be arranged while arbitrarily setting the number and the intervals. Further, the anchor bolts 1a and 1b do not need to include a part or all of the tapered portion 10, the tapered portion 11, the flat portion 12, and the conical top portion 13. The flat portion 12 may be provided such that the enlarged diameter portion 9 forms a polygonal column other than a regular hexagonal column. Further, the width of the opposed flange 102 may be the same as the wall surface flange 101 or may be wider than the wall surface flange 101. Further, the anchor bolts 1a and 1b may be applied to the floor of the existing concrete structure 200, and may be embedded in an anchor hole 201 formed perpendicular to the floor.

  1a, 1b: anchor bolt, 2: distal end, 3: proximal end, 4: threaded portion, 5: cylindrical portion, 6: body portion, 7: spacer, 8: reduced diameter portion, 9: enlarged diameter portion, DESCRIPTION OF SYMBOLS 10 ... taper diameter reduction part, 11 ... diameter expansion taper part, 12 ... plane part, 13 ... cone top, 20 ... nut, 81 ... drill bit, 82 ... roughing processing cutting bit, 83 ... grout injection hose, Reference numeral 84 denotes a bit for expanding diameter, 100 denotes a frame member, 101 denotes a wall flange, 102 denotes an opposite flange, 103 denotes a rib plate, 104 denotes a bolt hole, 200 denotes an existing concrete structure, 201 denotes an anchor hole, and 202 denotes a wall surface of an anchor hole. 203: anchor hole enlarged portion, 250: filler, F1, F2: force.

Claims (6)

A rod-shaped anchor bolt embedded in an anchor hole formed in an existing concrete structure,
Among a pair of ends of the rod-shaped anchor bolt, a base end that is the end located on the outside of the anchor hole when embedded in the anchor hole,
Among a pair of end portions of the rod-shaped anchor bolt, a tip portion which is the end portion located inside the anchor hole when embedded in the anchor hole,
A main body extending from the base end to the middle of the distal end,
A reduced diameter portion extending halfway from the main body to the distal end, and having a thickness smaller than the thickness of the main body,
An enlarged diameter portion extending from the reduced diameter portion toward the distal end portion and having a thickness larger than the thickness of the reduced diameter portion,
With
Between the main body and the reduced diameter portion, between the reduced diameter portion, between the reduced diameter portion and the enlarged diameter portion, and the enlarged diameter portion is formed integrally without a seam,
The main body has a constant thickness from the base end to the reduced diameter portion, and has a flat outer peripheral surface,
The body portion includes a spacer is a plurality of projections projecting from the different positions in the circumferential direction of the outer peripheral surface of the main body portion, said spacer when embedded into the anchor hole abuts against the wall surface of the anchor hole The anchor bolt, wherein the anchor bolt is located at the center of the anchor hole.   2. The anchor according to claim 1, further comprising a tapered portion between the reduced diameter portion and the enlarged diameter portion, the diameter gradually increasing from the reduced diameter portion to the enlarged diameter portion. 3. bolt.   3. The anchor according to claim 1, further comprising a tapered portion between the main body portion and the reduced diameter portion, the tapered portion gradually decreasing in thickness from the main body portion to the reduced diameter portion. 4. bolt.   The anchor bolt according to any one of claims 1 to 3, wherein the anchor bolt has a flat portion on an outer periphery of the enlarged diameter portion. An anchor hole forming step of forming the anchor hole in the existing concrete structure,
A filler injecting step of injecting a filler into the anchor hole formed by the anchor hole forming step,
An anchor insertion step of inserting the anchor bolt according to any one of claims 1 to 4 into the anchor hole into which the filler has been injected by the filler injection step,
Construction method of anchor bolts equipped with   6. The anchor hole forming step, wherein the width of the anchor hole on the inner side of the existing concrete structure is larger than the width of the anchor hole on the outer side of the existing concrete structure. Construction method of anchor bolt described in 4.

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