JP3042765B2 - Method and apparatus for fixing metal member to concrete, and shear bearing ring - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for fixing a metal member to concrete, a fixing device therefor, and an anchor bolt used for fixing the same.

[0002]

2. Description of the Related Art FIG. 14 is an explanatory view of a conventional method of fixing a base plate of a steel frame building.
Is a concrete foundation, and 102 is an anchor bolt mounted on the concrete foundation 101 by projecting a screw portion at the end to the outside, and the anchor bolt 102 is made of ordinary steel (S
S400). Reference numeral 103 denotes a base plate made of a steel frame as a steel material, reference numeral 104 denotes a hole through which the anchor bolt 102 provided in the base plate 103 is inserted, and reference numeral 105 denotes a double nut screwed into a screw portion 102a of the anchor bolt 102.

[0003] The anchor bolt 102 is installed on the concrete foundation 101 accurately before the concrete is cast. However, anchor bolt 1
No. 02 receives a pressing force from the concrete during concrete placement, causes a bending displacement shown by a dotted line in FIG. 11 and causes the anchor bolt 10 to be inserted into the hole 104 of the base plate 103 attached to the surface on which the concrete foundation 1 is formed.
2 is difficult or impossible to insert.

Therefore, conventionally, in order to eliminate the difficulty in assembling due to the displacement of the anchor bolt, the following method has been used. Anchor bolt 10 provided on base plate 103
The hole diameter of the second insertion hole 104 is made larger than the diameter of the anchor bolt 102 so that it can be inserted even if the anchor bolt 102 is slightly bent, and a clearance of, for example, 17 to 29 mm is provided.

[0005] As shown in FIG. 15, the concrete 101a around the anchor bolt 102 is cut off, the anchor bolt 102 is blown with a gas flame to correct the dotted line bent position to the solid line state, and then the missing concrete 101a is filled. Put it back and fix it.

[0006] As shown in FIG. 16, an anchor frame 106 is formed by using an anchor bolt 102, and a tip screw portion 102 a of the anchor bolt 102 projects from a steel material 106 a on an end surface of the anchor frame. The wound of iron wire 107 this anchor frame over arm 106 around the net, and performs concreting is positioned, anchor frame 106 in the concrete under construction, i.e. the anchor bolt 102 causing the position deviation There is no.

[0007]

BRIEF Problems to be Solved fixing method to the concrete of a conventional metal member, which is configured as described above, a gap is produced between greater both than the diameter of the hole diameter anchor bolt in said means Therefore, the anchor bolt cannot directly receive the lateral displacement of the base plate (column base) of the steel frame, and the initial displacement is large with respect to the shearing force, the displacement rigidity is small, and the deformation is large even with a small load. Since the maximum shear force is determined by the concrete breaking, it is lower than the maximum shear force of the anchor bolt. Therefore, when the shearing force (lateral displacement) of the base plate acts on the anchor bolt during an earthquake, the shearing force acting on the anchor bolt is applied to the concrete and breaks the concrete.

[0008] According to the above-mentioned means, the strength of the anchor bolt is reduced, and the anchor bolt is inclined, and the resistance to shearing force (lateral displacement) is reduced.

In the above-mentioned means, the anchor bolt which directly applies a shearing force to the anchor bolt is of a bearing type (a type which is eccentric from the center of the hole of the base plate and directly hits the peripheral wall portion of the hole) to be a bearing type. When a high-stress bolt (bolt fixed by a strong frictional force due to surface contact) made of a high-strength material (equivalent to F10T or F8T) is used, it cannot be said that the method of use takes advantage of its features.

[0010] The means for filling the adhesive or mortar into the gap between the hole 104 and the anchor bolt 102 of the base plate 103, the degree of aging of the adhesive or mortar, shrinkage ratio of different materials, the injection degree can check such have like There were challenges.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and it is possible to suppress displacement of an anchor bolt with respect to a metal member when the anchor bolt is installed, and to easily fix a metal member such as a steel member of a steel frame building. A fixing method, a fixing device, an anchor bolt and a shear bearing ring used for fixing the metal member, which can be easily and accurately performed, and which can enhance the fixing strength of the metal member by enhancing the shearing force of the anchor bolt. The purpose is to:

[0012]

According to a method of fixing a metal member to concrete according to the present invention, an anchor bolt to which a shearing force reinforcing member is assembled is provided such that one end surface of the shearing force reinforcing member is substantially flush with the concrete surface. As described above, a step of attaching a metal member to the concrete surface through the anchor bolt through a hole provided in the metal member, and screwing a nut to a screw portion of the anchor bolt passing through the hole of the metal member. And clamping and fixing the metal member between the nut and the shearing force reinforcing member.

Further, according to the method of fixing a metal member to concrete according to the present invention, an anchor bolt having a shearing force reinforcing member attached thereto is provided such that one end surface of the shearing force reinforcing member is substantially flush with the concrete surface. Installing on a concrete, attaching a metal member to the concrete surface by passing the anchor bolt through a hole provided in the metal member, and laterally shifting into a gap between the anchor bolt penetrating the hole of the metal member and the hole. A step of press-fitting the prevention member, and a step of screwing a nut to a screw portion of the anchor bolt penetrating the hole of the metal member, and clamping and fixing the metal member between the nut and the shearing force reinforcing member. It is characterized by consisting of.

[0014] The apparatus for fixing a metal member to concrete according to the present invention comprises: an anchor bolt mounted on concrete such that one end surface of the assembled shear force reinforcing member is flush with the concrete surface; A steel material attached to the concrete surface through a hole formed in the steel material, and the steel material is sandwiched between the steel member and the shearing force reinforcing member by being screwed into a screw portion of an anchor bolt penetrating the steel material hole. And a nut to be fixed.

Further, according to the present invention, there is provided an apparatus for fixing a metal member to concrete, comprising: an anchor bolt mounted on a concrete foundation such that one end surface of the assembled shear force reinforcing member is substantially flush with the concrete surface; A metal member attached to the concrete surface by passing an anchor bolt through the hole; a lateral displacement prevention member that press-fits into a gap between the anchor bolt and the hole that has penetrated the metal member; and a hole that penetrates the metal member screwed into the screw portion of the anchor bolt, characterized in that it consists of a nut and fixed to sandwich the metal member between the shear reinforcement member.

The lateral slip prevention member in each of the fixing methods and the fixing devices described above has an outer peripheral shape which is inclined from one end side to the other end side and is reduced in diameter. And on its outer peripheral surface,
A cutting blade that penetrates while shaving the hole wall surface of the metal member is provided. Further, it is characterized in that it is provided with a tooth-shaped or rib-shaped projection having a groove portion into which a cutting piece cut by the cutting blade enters. Further, the lateral displacement prevention member may be one or two having different diameters.
It is characterized by two eccentric rings. The metal member is a steel frame base plate or a steel plate.

The anchor bolt of the present invention used for fixing a metal member such as a steel material of the steel-frame building is characterized in that a deformed reinforcing bar as an anchor portion and a high stress bolt as a screw portion are integrated. .

In the shear bearing ring of the present invention used for fixing the metal member, a part of the cylinder is cut in parallel with the axis to form a C-shaped cross section, and the thickness of both sides of the C-shaped opening is formed. It is characterized by being formed sequentially thinner toward the end.

[0019]

Embodiments of the present invention will be described below.

Embodiment 1 FIG. 1 is an explanatory view of a method of fixing steel materials of a steel-framed building showing Embodiment 1 of the present invention. In FIG. 1, reference numeral 1 denotes a concrete foundation, and 2 denotes an end screw portion 2a. Are projected to the outside and installed on the concrete foundation 1, 3 is a nut as a shearing force reinforcing member previously attached to the anchor bolt, 4 is a base plate of a steel frame as a steel material, and 5 is provided on the base plate 4. A hole 6 through which the anchor bolt 2 is inserted, a fastening nut 6 which is screwed into the screw portion 2a of the anchor bolt 2 to fasten and fix the base plate 4 to the concrete foundation, and 10 and 11 are fitted to the anchor bolt 2 so as to clamp the base plate 4. Washer.

Next, the operation will be described. When the anchor bolt 2 is installed on the concrete foundation 1, first, a nut 3 is attached to the anchor bolt 2 in advance, and the anchor bolt 2 is accurately positioned so that the end face of the nut 3 is substantially flush with the concrete surface. Perform concrete casting. In this case, a large-diameter nut 3 is assembled near the concrete surface on which the maximum shearing force of the anchor bolt 2 acts, and the nut 3 increases the contact area with concrete, thereby increasing the shear rigidity and the shear strength. As a result, the displacement of the anchor bolts 2 during concrete casting can be minimized.

As a result, the base plate 4 as a steel material
Can be mounted on a concrete foundation by inserting the anchor bolt 2 into the hole 5 without correcting the displacement, and the screw portion 2a of the anchor bolt 2 inserted through the hole 5
The base plate 4 can be easily and quickly fixed to the concrete foundation 1 by screwing the fastening nut 6 to the base. In addition, since the contact area between the anchor bolt 2 and the concrete is increased by the screwed nut 3, even if a shear force is generated between the anchor bolt 2 and the base plate 4, the concrete is hardly broken.

Second Embodiment FIG. 2 is an explanatory view of a method of fixing steel materials of a steel frame building according to a second embodiment of the present invention. In FIG. 2, reference numeral 7 denotes a washer 10 and a base plate in the first embodiment. 4 is a shear bearing washer as a shearing force reinforcing member fitted to the anchor bolt 2 and has a tapered outer peripheral shape with a slope from one end to the other end. Reference numeral 8 denotes the washer 11 and the base plate 4 in the first embodiment.
And a shear bearing washer fitted to the anchor bolt 2 and having the same shape as the shear bearing washer 7 and the other configuration is the same as that of the first embodiment. And duplicate explanations are omitted.

According to the second embodiment, since the outer surface area of the shear bearing washer 7 is larger than that of the nut 3, the contact area with the concrete increases and the contact area with the base plate 4 as a steel material also increases. Large shear rigidity and shear strength can be obtained. As a result, the displacement of the anchor bolt 2 at the time of placing the concrete can be suppressed, and the breakage of the concrete due to the shearing force acting between the anchor bolt 2 and the base plate can be further reduced.

In this case, stress is transmitted by friction between the shear bearing washer 7, 8 and the base plate 4 by sandwiching the base plate 4 between the shear bearing washer 7, 8 and this stress F is expressed as F = μ × A × W. Here, μ: friction coefficient A: friction area of shear bearing washer 7 W: axial force of anchor bolt 2

Third Embodiment FIG. 3 is an explanatory view of a method for fixing steel materials of a steel frame building according to a third embodiment of the present invention. In FIG. 3, reference numeral 9 denotes an anchor bolt formed on a base plate 4 as a steel material. 2
The bearing is a shear bearing ring as a lateral displacement prevention member that is press-fitted into a gap between the hole 5 through which the bolt 5 passes and the anchor bolt 2 that passes through the hole 5, and the other configuration is the same as that of the second embodiment. And a duplicate description is omitted.

As shown in FIG. 4, the shear bearing ring 9 has an outer peripheral surface inclined from one end to the other end to reduce the diameter, thereby facilitating press-fitting. Further, if a cutting blade 9a that penetrates while cutting the hole wall surface of the steel material is provided on the outer peripheral surface, it can be firmly attached.

In this case, as shown in FIGS. 5 and 6, if a tooth-shaped or rib-like projection having a groove portion into which a cutting piece generated when entering while shaving is provided is provided, it is easy to enter while shaving. Can be. This tooth profile is easier to cut if it is angled, and the tooth profile is horizontal in each row (Fig. 5).
Alternatively, by shifting the shear bearing ring 9 in the vertical direction (FIG. 6) by a minute amount t, the penetration of the shear bearing ring 9 becomes easy. Several types of shear bearing rings 9 are prepared in advance, and when the steel material hole 5 and the anchor bolt 2 are misaligned as shown in FIGS. 7A and 7B, a size close to the extent of the misalignment is selected. To use.

FIG. 8 shows a modification of FIG. 7. In this case, as a method of filling the gap between the bolt hole 5 and the bolt 2, it is achieved by combining two large and small rings having different eccentric diameters. That is, when the bolt 2 is eccentric to the left side with respect to the bolt hole 5 as shown in FIG.
The large-diameter ring 9b eccentric to the left side of FIG.
By combining with the eccentric small-diameter ring of (c), a gap can be eliminated at any bolt 2 position.

According to the third embodiment, since the shear bearing ring 9 is press-fitted into the gap between the anchor bolt 2 passed through the bolt hole 5 of the base plate 4 and the hole wall, lateral displacement between the two can be eliminated. And, together with the increase in the contact area between the base plate 4 and the concrete,
Greater shear stiffness and shear strength are obtained. As a result,
It is possible to suppress the displacement of the anchor bolt 2 at the time of placing the concrete and to reduce the possibility of breaking the concrete by the shearing force acting between the anchor bolt 2 and the base plate.

Embodiment 4 FIG. 9 is a front view showing the structure of the anchor bolt 2 used in the method and apparatus for fixing a steel material of a steel building according to the present invention. In the first embodiment, the conventional ordinary steel anchor bolt may be used. However, when the shear bearing washer 7 is used as in the second and third embodiments, the thread portion of the anchor bolt 2 is Must be high stress bolts. On the other hand, the shaft portion of the anchor bolt installed in the concrete foundation is desirably a deformed reinforcing bar in order to enhance the adhesive force of the concrete.

In this case, threading the deformed reinforcing bar has ribs and joints, the core is not aligned, and threading is difficult. Also, the use of high-stress bolts threaded over the entire length increases costs. Therefore, the end face of the deformed reinforcing bar 2b as an anchor portion and the high stress bolt 2c as a screw portion are brought into contact, and the contact portion 2d is made to have a strength equivalent to the strength of the deformed reinforcing bar 2a by means such as welding or bonding. Unite,
This constitutes an anchor bolt 2.

By using the anchor bolt 2, the effect of the deformed reinforcing bar 2b is obtained for contact with concrete, and the shearing force applied to the base plate is transmitted to the washer from the friction between the base plate and the washer. Through to the foundation concrete. Therefore, the function of the bolt will be satisfied if the tightening force against the steel material is increased, and the effect of the high stress bolt 2c can be applied to the tightening and fixing of the base plate 4, and this kind of metal member can be applied to concrete. It is extremely effective when used in a fixing method and a fixing device.

FIG. 10 shows the experimental results of the steel material fixing method of the first to third embodiments and the conventional steel material fixing method. Curve A shows the experimental result of the first embodiment, and the load 17 (t) ) Breaks the concrete, and curve B is the experimental result of the second embodiment. The base plate 4 slides sideways at a load of 20.5 (t), and a further load starts to be applied to the concrete, and the load is 34.5 (t). , The concrete was destroyed, and the curve C is the experimental result of the third embodiment.
At (t), the concrete is broken, and the curve D is an experimental result of the conventional steel material fixing method. The concrete is broken at a load of 11.2 (t) lower than each embodiment of the present invention. As is clear from the experimental results, in each embodiment of the present invention, since the shearing force reinforcing member is attached to the anchor bolt 2 to increase the contact area with concrete, a large shearing rigidity and shearing strength can be obtained. , Concrete is less likely to break.

In each of the above embodiments, the drawings show only the case of a base plate of a steel-framed building in which anchor bolts are installed in the vertical direction. Needless to say, it includes the case of a steel plate installed in the direction. Further, in each of the above-described embodiments, the steel material such as the base plate of the steel-framed building has been described. However, what is fixed to the concrete is not limited to the steel material, but may be any metal member containing aluminum. .

Fifth Embodiment FIG. 11 shows a specific embodiment of the shear bearing ring shown in FIG. 7B for press-fitting into the gap between the hole of the base plate 4 and the anchor bolt 2 to prevent lateral displacement. This shear bearing ring 10 is formed by cutting off a part of a cylinder 10a in parallel with the axis to form a C-shaped cross section, and forming the C-shaped both sides 10b, 10c to be gradually thinner toward the opening end. It is. The shear bearing ring 10 is formed by mechanical working such as plastic working, cutting, or the like, or by pressing metal powder into a predetermined shape in a mold. The thickness of the opening end parallel to the axis is an appropriate thickness. Good, very easy to create.

FIG. 12 shows the shear bearing ring 9 shown in FIG. 8 and the shear bearing ring 10 of this embodiment.
FIG. 7 is a comparison diagram of the use state of FIG. When the shear bearing ring 9 is used for the eccentric anchor bolt 2, the anchor bolt insertion hole of the base plate 4 needs a hole diameter D as shown in FIG. FIG. 12 (b)
As shown in the figure, the hole diameter of the anchor bolt insertion hole of the base plate 4 is sufficient. Therefore, the diameter of the hole provided in the base plate 4 can be smaller by D−d = α when the shear bearing ring 10 of the present embodiment is used, and a decrease in the strength of the base plate 4 can be prevented accordingly.

As a result, it is sufficient that the base plate 4 has an appropriate thickness. If the hole diameter of the base plate 4 is small, a small and thin shear bearing washer is sufficient. For this reason, the concrete foundation does not need to be large, and the entire structure can be made compact.

FIG . 13 shows a shear bear having two different diameters.
Explanatory drawing showing the state of using a ring ring in combination
It is. As is clear from the figure, the concrete of the metal member
Ring 101 and small ring 102 used for fixing to
Shear bearing ring consisting of a combination with
Each of these large ring 101 and small ring 102
Part of the cylinder is cut off parallel to the axis to form a C-shaped cross section.
Then, the pressure on both sides of the C-shape is gradually reduced toward the opening end.
And small rings are anchored in both sides of the C-shape.
-Has an inner diameter and an opening surrounding the bolt 2, and the large ring
The inner diameter and the opening that surround the small ring in both sides of the C-shape
Having. That is, when the shear bearing ring is inserted into the gap between the anchor bolt 2 and the hole of the base plate 4, it is possible to use two shear bearing rings 101 and 102 having different diameters in a cylindrical shape. Good thing.

[0040]

As described above, according to the present invention, since the shearing force reinforcing member is attached to the anchor bolt and installed on the concrete, a large shearing rigidity and a high shearing strength can be obtained. Even if the displacement of the bolt occurs, the bolt hole of the metal member such as the base plate can be made larger, and it is not necessary to correct the position of the anchor bolt after placing the concrete. Therefore, it is not necessary to use an expensive anchor frame, and it is possible to easily and quickly fix a metal member to concrete at low cost. In addition, there is an effect that a fixing method and a fixing device in which a shear force is generated between the metal member and the anchor bolt after the metal member is fixed and a load is applied to the anchor bolt, which does not lead to concrete breakage are obtained.

Further, since the lateral displacement prevention member is press-fitted into the gap between the hole of the metal member and the anchor bolt passing through the hole, the lateral displacement of the metal member can be prevented, and in addition to the shear force reinforcing member. Thus, there is an effect that a fixing method and a fixing device that can further improve the shear rigidity and the shear strength can be obtained.

Further, since the anchor bolt is formed by integrating a deformed reinforcing bar as an anchor portion and a high-stress bolt as a screw portion to have the same strength as that of the deformed reinforcing bar, the fixing method and the fixing device of the present invention are provided. There is an effect that a suitable anchor bolt can be obtained at low cost.

Further, a shear bearing ring for preventing lateral displacement of the metal member is formed by cutting a part of the cylinder in parallel with the axis so as to have a C-shaped cross section. Since the metal members are sequentially made thinner, the bolt holes of the metal member can be made to have an appropriate size, and a reduction in the strength of the metal member can be prevented. Further, it is possible to prevent a reduction in the strength of the metal member, and it is possible to obtain the metal member easily and at low cost.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a method for fixing steel materials of a steel-framed building showing Embodiment 1 of the present invention.

FIG. 2 is an explanatory diagram of a method of fixing steel materials of a steel-framed building showing Embodiment 2 of the present invention.

FIG. 3 is an explanatory view of a method for fixing steel materials of a steel-framed building showing Embodiment 3 of the present invention.

FIG. 4 is an explanatory diagram of a press-fitting process of a shear bearing ring.

FIG. 5 is a front view of a shear bearing ring.

FIG. 6 is a front view of a shear bearing ring.

FIG. 7 is an explanatory diagram showing a press-fit state of a shear bearing ring.

FIG. 8 is an explanatory diagram of a case where two eccentric rings having different diameters are combined and pressed into a gap between a bolt hole and a bolt.

FIG. 9 is a front view showing a configuration of an anchor bolt.

FIG. 10 is a graph showing experimental results obtained by a steel material fixing method according to each embodiment of the present invention and a conventional steel material fixing method.

FIG. 11 is a perspective view showing another embodiment of the shear bearing ring.

FIG. 12 is an explanatory view showing a usage state of two types of shear bearing rings.

FIG. 13 is an explanatory view showing a combined use state of two shear bearing rings having different diameters.

FIG. 14 is an explanatory view of a conventional steel material fixing method for a steel frame building.

FIG. 15 is an explanatory diagram of rework.

FIG. 16 is a perspective view of an anchor frame for placing concrete.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Concrete foundation 2 Anchor bolt 2a Screw part 2b Deformed bar 2c High stress bolt 3 Nut (shearing reinforcing member) 4 Base plate (metal member) 5 Hole 6 Tightening nut 7 Shear bearing washer (shearing reinforcing member) 9 Shear bearing ring ( Side slip prevention members) 10, 11 Washers

Continued on the front page (72) Inventor Motoomi Ogata 1413-2 Kamiyaki, Matsudo-shi, Chiba (72) Inventor Eiji Suzuki 129, 129 Komagaki, Nagareyama-shi, Chiba (72) Inventor Shoichi Takahashi Major in Chiyoda-ku, Tokyo 2-6-2, Kotobuki Kogyo Kogyo Co., Ltd. (72) Inventor Masayuki Kato 1-33-13 Takadanobaba, Shinjuku-ku, Tokyo Inside Masato Kato Building Research Institute (56) References JP-A-2-13642 (JP, A) JP-A-6-67544 (JP, U) JP-A 2-36613 (JP, U) Registered utility model 3002207 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB) Name) E02D 27/00 E04B 1/24 E04B 1/41 502

Claims (7)

(57) [Claims] 1. A step of installing an anchor bolt on which a shear reinforcing member is assembled on concrete so that one end surface of the shear reinforcing member is substantially flush with a concrete surface.
And attaching the metal member to the surface of the concrete through the anchor bolt into a hole provided in the metal member,
An anchor bolt penetrating the hole of the metal member and the hole
Press-fitting a lateral displacement prevention member into a gap between the screws, and screwing a nut to a screw portion of an anchor bolt penetrating the hole of the metal member, and clamping the metal member between the nut and the shear force reinforcing member. in Rukin genus fixing method members to concrete such and a step of fixing Te, the lateral displacement preventing member
The outer peripheral shape is tapered from one end to the other end
A method for fixing a metal member to concrete. 2. The method for fixing a metal member to concrete according to claim 1, wherein said lateral displacement prevention member includes a cutting blade which penetrates while shaving a hole wall surface of said metal member. 3. The concrete member according to claim 2, wherein said lateral displacement preventing member has a tooth-shaped or rib-shaped projection having a groove for receiving a cutting piece cut by said cutting blade. Fixing method. An anchor bolt having one end face of 4. assembled shear force reinforcement member is anchored in the concrete so as to be substantially flush with the concrete surface, it is attached to the surface of the concrete through the anchor bolt into the hole A metal member, an anchor bolt passing through the hole of the metal member, and a lateral displacement prevention member press-fitting into a gap between the hole, and a shearing member which is screwed into a screw portion of the anchor bolt passing through the hole of the metal member. In a fixing device for fixing a metal member to concrete, comprising a nut for sandwiching and fixing the metal member between the reinforcing member and the force reinforcing member, an outer peripheral shape of the lateral displacement prevention member is inclined from one end to the other end. An apparatus for fixing a metal member to concrete, the diameter of which is reduced. Wherein said lateral displacement preventing member, the fixing device to the concrete of the metal member according to claim 4, characterized in that it comprises a cutting blade to penetrate while cutting a hole wall surface of the base plate. The outer peripheral surface of wherein said lateral displacement preventing member, a metal member according to claim 5, characterized in that a tooth or rib-like projections having a groove cutting pieces cut by the cutting blade enters Fixing device to concrete. 7. A shear bearing ring comprising a combination of a large ring and a small ring, wherein each of the large ring and the small ring has a C-shaped cross section by cutting a part of a cylinder in parallel with an axis. The thickness of the C-shaped sides is gradually reduced toward the opening end, the small ring has an inner diameter and an opening surrounding the anchor bolt in the C-shaped sides, and the large ring has A shear bearing ring used for fixing a metal member to concrete, having an inner diameter and an opening surrounding the small ring in both sides of the C-shape.