JP7082462B2 - Anchor reinforcement structure, anchor reinforcement method and anchor reinforcement member - Google Patents

Description

The present invention relates to, for example, an anchor reinforcing structure, an anchor reinforcing method, and an anchor reinforcing member for an anchor bolt that fixes a base plate or the like of a column base.

In order to prevent the structure from collapsing due to an earthquake, the structure such as columns is required to have a seismic strength of a predetermined value or higher. However, old structures may not meet the current seismic standards, as structures constructed before the current seismic standards were not required to have the strict seismic strengths of today. However, it takes time and cost to newly reconstruct all the structures such as columns.

As a method of reinforcing such a structure, for example, there is a method of placing concrete around the column base portion of an existing column to construct a reinforced concrete root winding portion. However, since concrete is constructed around the columns, a lot of construction work such as reinforcing bars and formwork is required, and the size of the columns is increased by the amount of concrete, which hinders the convenience of the building.

On the other hand, structures such as column bases are usually fixed to foundations and ground by anchor bolts (for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2006-104780

If the strength and deformation capacity of the anchor bolts are not sufficient, the structure may tip over due to the anchor bolts breaking at an early stage. Therefore, it may be necessary to reinforce the anchor bolts in order to reinforce the structure. In particular, many anchor bolts used for exposed steel-framed column bases of the old age cause the threaded part to break before the shaft part of the anchor bolt is sufficiently plastically deformed, and the deformation ability of the column base is high. Many are scarce.

The present invention has been made in view of such problems, and an object of the present invention is to provide an anchor reinforcing structure, an anchor reinforcing method, and an anchor reinforcing member capable of efficiently reinforcing anchor bolts.

In order to achieve the above-mentioned object, the first invention is an anchor reinforcing structure, in which an existing anchor bolt for fixing the base plate of the exposed column base and a reinforcing member joined to the upper part of the anchor bolt are provided. The reinforcing member includes a shaft member and a fixing member capable of accommodating the shaft member inside, and the shaft is provided with a gap between the shaft member and the fixing surface of the fixing member. One end of the member is joined to the anchor bolt, the fixing member has a hole at one end through which the shaft member can be inserted , and is fixed only to the upper surface of the base plate and is fixed to the shaft member. With the fixing member covered, the shaft member protruding from the upper part of the fixing member is fixed at the upper part of the fixing member, and the lower end portion of the shaft member is attached to the shaft portion of the intermediate portion of the shaft member. An enlarged diameter portion thicker than the thickness is formed, a male screw portion is formed at the upper end portion of the shaft member, and the diameter of the shaft portion is smaller than the diameter of the valley portion of the male screw portion and the diameter of the enlarged diameter portion. A groove is formed on the lower surface side of the enlarged diameter portion, the shaft member and the anchor bolt are welded at the groove, and the shaft member breaks the joint portion between the shaft member and the anchor bolt. It is an anchor reinforcement structure characterized in that plastic deformation is started with a load smaller than the load to be applied.

The load at which the shaft member starts plastic deformation may be larger than the load at which the threaded portion of the anchor bolt starts plastic deformation and smaller than the load at which the threaded portion of the anchor bolt breaks.

The load at which the shaft member starts plastic deformation may be smaller than the load at which the threaded portion of the anchor bolt starts plastic deformation.

According to the first invention, a reinforcing member is attached to the upper part of the anchor bolt, and the shaft member starts plastic deformation with a load smaller than the load at which the joint with the anchor bolt breaks. Therefore, in the event of an earthquake or the like. , A sufficient amount of deformation can be secured before the joint with the anchor bolt breaks.

Such a reinforcing member is particularly effective for reinforcing anchor bolts that fix the base plate of the column base.

Further, by forming a diameter-expanded portion thicker than the thickness of the shaft portion in the middle portion of the shaft member at the lower end portion of the shaft member and forming a groove on the lower surface side of the diameter-expanded portion, the anchor bolt and the shaft member can be formed. Can be easily welded. At this time, since the welded area of the joint can be made larger than the cross-sectional area of the intermediate portion of the shaft member, the shaft member can be plastically deformed with a load smaller than the load at which the joint with the anchor bolt breaks. can.

If the load at which the shaft member starts plastic deformation is larger than the load at which the threaded portion of the anchor bolt starts plastic deformation and smaller than the load at which the threaded portion breaks, high strength and the effect of preventing the anchor from breaking are obtained. It can be compatible.

Further, if the load at which the shaft member starts plastic deformation is smaller than the load at which the threaded portion of the anchor bolt starts plastic deformation, the strength design of the shaft member is easy.

The second invention is an existing method for reinforcing an existing anchor, wherein the base plate of the exposed column base is fixed by using an anchor reinforcing member including a shaft member and a fixing member capable of accommodating the shaft member inside. The step of removing the nut of the anchor bolt, the step of welding one end of the shaft member to the anchor bolt, and the step of covering the shaft member with the fixing member to cover the other end of the shaft member. It comprises a step of projecting onto the fixing member and fixing the shaft member and the fixing member on the upper portion of the fixing member, and the fixing member is fixed only to the upper surface of the base plate and the shaft member is fixed. A diameter-expanded portion thicker than the thickness of the shaft portion in the middle portion of the shaft member is formed at the lower end portion of the shaft member, and a male screw portion is formed at the upper end portion of the shaft member. A groove is formed on the lower surface side of the enlarged diameter portion, which is smaller than the diameter of the valley portion of the male threaded portion and the diameter of the enlarged diameter portion, and the shaft member and the anchor bolt are welded at the groove to form the shaft. There is a gap between the member and the fixed surface of the fixing member, and the shaft member starts plastic deformation with a load smaller than the load at which the threaded portion of the anchor bolt breaks. It is a reinforcement method.

According to the second invention, the existing anchor bolt can be easily reinforced.

The third invention is a reinforcing member of an existing anchor for fixing the base plate of the exposed column base, and the shaft member and the shaft member can be accommodated inside and fixed only to the upper surface of the base plate. A member and a diameter-expanded portion thicker than the thickness of the shaft portion in the middle portion of the shaft member are formed at the lower end portion of the shaft member, and a male screw portion is formed at the upper end portion of the shaft member. The diameter of the shaft portion is smaller than the diameter of the valley portion of the male screw portion and the diameter of the enlarged diameter portion, a groove is formed on the lower surface side of the enlarged diameter portion, and the fixing member has one end. It is an anchor reinforcing member characterized by having a hole through which the shaft member can be inserted in the portion.

According to the third invention, it is possible to obtain a reinforcing member capable of easily reinforcing the anchor bolt.

According to the present invention, it is possible to provide an anchor reinforcing structure, an anchor reinforcing method, and an anchor reinforcing member capable of efficiently reinforcing an anchor bolt.

The side view which shows the anchor reinforcement structure 1. An enlarged cross-sectional view of the anchor reinforcing structure 1. Exploded view of the reinforcing member 11. The figure which shows the existing column base 3. The figure which shows the state which the nut 27 was removed. The figure which shows the state which attached the shaft member 13. The figure which shows the state which arranges the fixing member 15 and attaches a nut 17. An enlarged cross-sectional view of the anchor reinforcing structure 1a. The figure which shows the state which the column base 3 is displaced. FIG. 9 is an enlarged cross-sectional view of the F portion of FIG. The figure which shows the relationship between a load and a deformation amount.

Hereinafter, the anchor reinforcing structure 1 according to the embodiment of the present invention will be described. FIG. 1 is a side view showing the anchor reinforcing structure 1. In the following description, the anchor reinforcing structure 1 shows a reinforcing structure for the anchor bolt 9 that fixes the base plate 7 of the column base 3, but the present invention is not limited to this, as long as it is a structure fixed by an anchor. Applicable.

The column base 3 is constructed on the floor 5 (for example, the foundation). A base plate 7 is fixed on the floor 5 with anchor bolts 9. A reinforcing member 11 is fixed to the upper part of the anchor bolt 9.

FIG. 2 is an enlarged cross-sectional view of part A of FIG. 1, and FIG. 3 is an exploded cross-sectional view of the reinforcing member 11. The reinforcing member 11 includes a shaft member 13 and a fixing member 15. As shown in FIG. 3, the shaft member 13 is provided with a male screw portion 21 at one end (upper end) and a diameter expansion portion 22 at the other end (lower end). The intermediate portion between the enlarged diameter portion 22 and the male screw portion 21 is the shaft portion 23. The diameter-expanded portion 22 is thicker than the shaft portion 23. Further, the diameter of the shaft portion 23 is smaller than the diameter of the valley portion of the male screw portion 21 and the diameter of the enlarged diameter portion 22.

The fixing member 15 can accommodate the shaft member 13 inside. At one end of the fixing member 15, a hole 25 through which the male screw portion 21 and the shaft portion 23 can be inserted is formed.

As shown in FIG. 2, the diameter-expanded portion 22 at the end of the shaft member 13 is joined to the threaded portion 9a of the anchor bolt 9. The shaft member 13 and the anchor bolt 9 are joined by, for example, welding or pin joining. In the illustrated example, the shaft member 13 and the anchor bolt 9 are joined at the welded portion 31. That is, the shaft member 13 and the anchor bolt 9 are joined by a structure other than the screw structure. In this case, the shaft member 13 and the anchor bolt 9 can be easily welded by providing the groove 29 on the lower surface of the enlarged diameter portion 22. The welding area of the welded portion 31 (the cross section perpendicular to the axial direction of the anchor bolt 9 and the cross-sectional area of the joint surface between the weld bead and the anchor bolt 9) is larger than the cross-sectional area of the shaft portion 23.

In this state, the fixing member 15 is arranged so as to cover the shaft member 13, and the male screw portion 21 projects upward from the hole 25 of the fixing member 15. Further, a nut 17 is provided on the male screw portion 21 and is fixed to the upper portion of the fixing member 15.

At this time, a gap is formed between the tip of the shaft member 13 (diameter-expanded portion 22) and the upper surface of the base plate 7 which is the fixing surface of the fixing member 15. That is, the shaft member 13 does not come into contact with the fixed surface of the fixing member 15.

The shaft member 13 and the fixing member 15 are made of, for example, steel. The shaft member 13 has a male screw portion 21 formed at the end of the rod-shaped material by tapping, and the shaft portion 23 may be reduced in diameter by cutting or the like with respect to the rod-shaped material, for example.

Next, a method of reinforcing the existing column base using the reinforcing member 11 will be described. FIG. 4 is a diagram showing the existing column base 3. As described above, the column base 3 is installed on the floor 5. The base plate 7 of the column base 3 is fixed to the floor 5 by anchor bolts 9 and nuts 27.

From this state, as shown in FIG. 5, the nut 27 is removed from the anchor bolt 9 (arrow C in the figure). Therefore, the threaded portion 9a of the anchor bolt 9 is in a state of protruding onto the base plate 7.

Next, as shown in FIG. 6, the shaft member 13 is joined to the anchor bolt 9 protruding from the base plate 7. For example, the threaded portion 9a of the anchor bolt 9 and the enlarged diameter portion 22 of the shaft member 13 are welded at the welded portion 31. At this time, as described above, a gap is formed between the lower end of the shaft member 13 (diameter expansion portion 22) and the upper surface of the base plate 7.

Next, as shown in FIG. 7, the shaft member 13 is covered with the fixing member 15. At this time, the male screw portion 21 of the shaft member 13 is inserted into the hole 25 of the fixing member 15 and protrudes upward of the fixing member 15. Further, the anchor reinforcing structure 1 is constructed by attaching and fixing the nut 17 to the male screw portion 21 from above the fixing member 15 (arrow D in the figure). As the nut 17, the nut 27 that has fixed the anchor bolt 9 may be used as it is.

When a plurality of anchor bolts 9 are adjacent to each other, after attaching the shaft member 13 to each anchor bolt 9, one fixing member 15 provided with a plurality of holes 25 is attached to the plurality of shaft members 13. Each shaft member 13 may be fixed with a nut 17 by collectively covering the shaft members 13.

Further, as in the anchor reinforcing structure 1a shown in FIG. 8, the shaft member 13 and the fixing member 15 may be joined at the welded portion 31a. In this case, the male screw portion 21 may not be provided at the upper end portion of the shaft member 13. As described above, as long as the shaft member 13 and the fixing member 15 can be joined, the joining method is not particularly limited.

Next, the function of the anchor reinforcing structure 1 will be described. FIG. 9 is a diagram showing a state in which the column base 3 is tilted (arrow E in the figure) during an earthquake, and FIG. 10 is an enlarged cross-sectional view of a portion F in FIG. When the base plate 7 is about to be lifted by an earthquake, tensile stress is applied to the shaft member 13 of the anchor bolt 9 and the reinforcing member 11.

At this time, the cross-sectional area of the shaft portion 23 of the shaft member 13 is smaller than the cross-sectional area of the valley portion of the male screw portion 21 and the cross-sectional area of the joint portion (welded portion 31) between the shaft member 13 and the anchor bolt 9. The shaft portion 23 is plastically deformed (stretched and deformed) with a load smaller than that when the male screw portion 21 or the welded portion 31 starts plastic deformation (arrow H in FIG. 10).

Further, the shaft portion 23 starts plastic deformation with a load smaller than the load at which the threaded portion 9a of the anchor bolt 9 breaks. FIG. 11 is a diagram showing the relationship between the load of each part and the amount of deformation. In the figure, I is a diagram showing the behavior of the anchor bolt 9 (screw portion 9a). The threaded portion 9a starts plastic deformation with a predetermined load (L in the figure). However, since the strength and deformation capacity of the anchor bolt are not sufficient, the threaded portion breaks before the shaft portion of the anchor bolt is sufficiently plastically deformed (M in the figure).

On the other hand, the shaft portion 23 of the shaft member 13 exhibits the behavior as shown by K in the figure, for example. That is, the shaft portion 23 starts plastic deformation with a load smaller than the breaking load of the threaded portion 9a of the anchor bolt 9. Therefore, if the shaft portion 23 is within the range of deformation that can be plastically deformed, the thread portion 9a is not subjected to the load required for the thread portion 9a to break.

As described above, in the present embodiment, the shaft portion 23 is preferentially plastically deformed, so that the anchor bolt 9 can be prevented from breaking. Further, since the load at which the shaft portion 23 starts to undergo plastic deformation is only slightly smaller than the load at which the screw portion 9a breaks, it is possible to prevent the shaft portion 23 from being easily plastically deformed with a small load. Can be done. As described above, it is desirable that the load at which the shaft portion 23 starts plastic deformation is larger than the load at which the threaded portion 9a of the anchor bolt 9 starts plastic deformation and smaller than the load at which the threaded portion 9a breaks.

Here, the inclination allowed for the column base 3 is about 1/30 rad. Therefore, the required elongation amount is preset from the size of the base plate 7 and the inclination thereof. Further, at this time, by setting the gap between the shaft member 13 and the base plate 7 to a required elongation amount or more, the elongation of the shaft portion 23 can be surely allowed.

The shaft portion 23 of the shaft member 13 may behave as shown in J in the figure, for example. That is, the shaft portion 23 may start plastic deformation with a load smaller than the load at which the threaded portion 9a of the anchor bolt 9 starts plastic deformation. Even in this way, the load required for the threaded portion 9a to break is not applied to the threaded portion 9a within the range of the amount of deformation in which the shaft portion 23 can be plastically deformed. Further, it is easy to design the strength of the shaft portion 23 for starting the plastic deformation with a load smaller than the load at which the threaded portion 9a of the anchor bolt 9 starts the plastic deformation.

In this case, the shaft portion 23 starts plastic deformation with a smaller load as compared with the above-mentioned example, but the screw portion 9a of the anchor bolt 9 can be prevented from plastic deformation, so that an earthquake occurs. Later, the repair can be completed only by replacing the shaft member 13.

As described above, according to the present embodiment, the anchor reinforcing structure 1 can be obtained by a simple operation. Therefore, it is easy to reinforce the existing column base 3. Further, since the anchor reinforcing structure 1 can prevent the anchor bolt 9 for fixing the column base 3 from breaking, it is possible to prevent the column base 3 from tipping over.

In addition, after an earthquake, repairs can be easily performed by replacing the shaft member 13.

Further, since the cross-sectional area of the shaft portion 23 of the shaft member 13 is smaller than the cross-sectional area of the valley portion of the male screw portion 21 and the cross-sectional area of the welded portion 31, the shaft portion 23 of the shaft member 13 is preferentially plastically deformed. Can be done.

Further, if the plastic deformation starting load of the shaft portion 23 is larger than the load at which the threaded portion 9a of the anchor bolt 9 starts plastic deformation and smaller than the load at which the threaded portion 9a breaks, the anchor bolt 9 is prevented from breaking. , High strength can be achieved at the same time.

Further, if the plastic deformation starting load of the shaft portion 23 is smaller than the load at which the threaded portion 9a of the anchor bolt 9 starts plastic deformation, it is possible to prevent the threaded portion 9a of the anchor bolt 9 from being deformed after the earthquake. ..

Although the embodiments of the present invention have been described above with reference to the attached drawings, the technical scope of the present invention does not depend on the above-described embodiments. It is clear that a person skilled in the art can come up with various modifications or modifications within the scope of the technical ideas described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

1, 1a ………… Anchor reinforcement structure 3 ………… Column base 5 ………… Floor 7 ………… Base plate 9 ………… Anchor bolt 9a ………… Screw portion 11 ………… Reinforcing member 13 ………… Shaft member 15 ………… Fixing member 17 ………… Nut 21 ………… Male screw part 22 ………… Diameter expansion part 23 ………… Shaft part 25 ………… Hole 27 ………… Nut 29 ………… Groove 31, 31a …… …welded part

Claims (5)

It is a reinforcement structure of the anchor,
The existing anchor bolts that fix the base plate of the exposed column base, and
Reinforcing members joined to the top of the anchor bolts,
Equipped with
The reinforcing member includes a shaft member and a fixing member capable of accommodating the shaft member inside.
One end of the shaft member is joined to the anchor bolt with a gap between the shaft member and the fixed surface of the fixing member.
The fixing member has a hole at one end through which the shaft member can be inserted , and is fixed only to the upper surface of the base plate.
With the fixing member covered on the shaft member, the shaft member protruding from the upper part of the fixing member is fixed on the upper part of the fixing member.
A diameter-expanded portion thicker than the thickness of the shaft portion in the middle portion of the shaft member is formed at the lower end portion of the shaft member, and a male screw portion is formed at the upper end portion of the shaft member, and the diameter of the shaft portion is formed. Is smaller than the diameter of the valley portion of the male screw portion and the diameter of the enlarged diameter portion.
A groove is formed on the lower surface side of the enlarged diameter portion, and the shaft member and the anchor bolt are welded at the groove.
The shaft member is an anchor reinforcing structure characterized in that plastic deformation is started with a load smaller than a breaking load of a joint portion between the shaft member and the anchor bolt. Claim 1 is characterized in that the load at which the shaft member starts plastic deformation is larger than the load at which the threaded portion of the anchor bolt starts plastic deformation and smaller than the load at which the threaded portion of the anchor bolt breaks. Anchor reinforcement structure described in. The anchor reinforcing structure according to claim 1, wherein the load at which the shaft member starts plastic deformation is smaller than the load at which the threaded portion of the anchor bolt starts plastic deformation. It is a method of reinforcing existing anchors.
An anchor reinforcing member including a shaft member and a fixing member capable of accommodating the shaft member inside is used.
The process of removing the nuts of the existing anchor bolts that fix the base plate of the exposed column base,
A step of welding one end of the shaft member to the anchor bolt,
A step of covering the shaft member with the shaft member, projecting the other end portion of the shaft member onto the fixing member, and fixing the shaft member and the fixing member on the upper portion of the fixing member.
Equipped with
The fixing member is fixed only to the upper surface of the base plate.
A diameter-expanded portion thicker than the thickness of the shaft portion in the middle portion of the shaft member is formed at the lower end portion of the shaft member, and a male screw portion is formed at the upper end portion of the shaft member, and the diameter of the shaft portion is formed. Is smaller than the diameter of the valley portion of the male screw portion and the diameter of the enlarged diameter portion.
A groove is formed on the lower surface side of the enlarged diameter portion, and the shaft member and the anchor bolt are welded at the groove.
There is a gap between the shaft member and the fixed surface of the fixing member, and the shaft member is characterized in that it starts plastic deformation with a load smaller than the load at which the threaded portion of the anchor bolt breaks. Anchor reinforcement method. It is a reinforcing member of the existing anchor that fixes the base plate of the exposed column base.
Shaft member and
A fixing member that can accommodate the shaft member inside and is fixed only to the upper surface of the base plate .
Equipped with
A diameter-expanded portion thicker than the thickness of the shaft portion in the middle portion of the shaft member is formed at the lower end portion of the shaft member, and a male screw portion is formed at the upper end portion of the shaft member, and the diameter of the shaft portion is formed. Is smaller than the diameter of the valley portion of the male screw portion and the diameter of the enlarged diameter portion.
A groove is formed on the lower surface side of the enlarged diameter portion, and a groove is formed.
The fixing member is an anchor reinforcing member having a hole at one end through which the shaft member can be inserted.

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