JP2013204364A - Joining structure for joining seismic isolation device to concrete structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a joining structure to join a seismic isolation device made of round laminated rubber to a reinforced concrete structure.SOLUTION: A plurality of embedded metal fittings 30 which have female screw portions and are vertically extended are embedded in an upper surface of a structure 20 in a predetermined planar arrangement. A peripheral portion of a lower flange plate 16 of a seismic isolation device 10 is provided with fixing bolt insertion holes. The lower flange plate 16 is fixedly connected to the structure 20 by screwing fixing bolts 34 inserted in the fixing bolts insertion holes and female screw portions of the embedded metal fittings 30. A plurality of main reinforcement bars 26 which are parallel with each other and horizontally extended are arranged in a horizontal direction at intervals in the vicinity of the upper surface of the structure 20. The planar arrangement of the embedded metal fittings 30 is a quadrilateral surrounding a laminated rubber 12 with 2 sides horizontally extended in parallel to a direction that the main reinforcement bars 26 are extended and other 2 sides horizontally extended orthogonal to the direction that the main reinforcement bars 26 are extended. The plurality of embedded metal fittings 30 are positioned on each side of the quadrilateral.

Description

  The present invention relates to a joining structure for joining a seismic isolation device to a reinforced concrete structure, and more specifically, a seismic isolation device made of a round laminated rubber having an upper flange plate at an upper end and a lower flange plate at a lower end. The present invention relates to a joining structure for joining to a reinforced concrete structure.

  The seismic isolation device made of laminated rubber has steel plate flange plates at both upper and lower ends, and the upper and lower flange plates are joined to the upper structure and the lower structure by fixing bolts, respectively. Equipment is installed. Conventionally, a circular flange plate has been used as a flange plate of a seismic isolation device made of a round laminated rubber. A plurality of fixing bolt insertion holes for inserting fixing bolts are formed at the peripheral edge of the circular flange plate, and the fixing bolt insertion holes are formed on a single circle concentric with the round laminated rubber. Are provided at equiangular intervals. When the structure that joins the flange plate of the seismic isolation device made of such a round laminated rubber is a reinforced concrete structure such as a footing or a beam, a fixing bolt is screwed into the structure. An embedded metal fitting such as an anchor bolt with an internal thread that has an internal thread and extends in the vertical direction is embedded. In that case, since the planar arrangement of the embedded metal fittings is an arrangement corresponding to the planar arrangement of the fixing bolt insertion holes of the flange plate, a plurality of embedded metal fittings are arranged at equal angular intervals on one circle. As a specific example of the joint structure of the seismic isolation device having such a configuration, for example, there is one disclosed in Patent Document 1 below.

JP2011-214259

  In order to join a seismic isolation device made of round laminated rubber to a reinforced concrete structure such as a footing or a beam using such a conventional joint structure, the buried hardware does not interfere with the reinforcing bars of the structure, and in particular with the main bars. It is necessary to consider so. In many cases, a large number of main bars are arranged in the vicinity of the surface of the reinforced concrete structure to which the flange plate of the seismic isolation device is joined, and these main bars are parallel to each other and horizontally (that is, footing, Although extending in the longitudinal direction of the beam and spaced in the horizontal direction (i.e. in the footing and beam width directions), the spacing is often quite narrow. However, as described above, when a plurality of buried fittings extending in the vertical direction are arranged at equal angular intervals on one circle, the buried fitting located near the side edge of the footing or beam Since the separation distance between the embedded brackets in the footing or beam width direction is small (refer to the distance L shown in FIG. 2B), in order to arrange the main bars away from the embedded brackets, The design and construction of the streaks becomes troublesome.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a joint structure for joining a seismic isolation device made of a round laminated rubber to a reinforced concrete structure while having sufficient strength. An object of the present invention is to provide a joint structure that can facilitate the design and construction of reinforcing bars for reinforced concrete structures such as footings and beams for joining seismic isolation devices.

In order to achieve the above object, a joining structure according to the present invention for joining a seismic isolation device comprising a round laminated rubber having an upper flange plate at the upper end and a lower flange plate at the lower end to a reinforced concrete structure, On the upper surface of the reinforced concrete structure, a plurality of embedded metal fittings having an internal thread portion at least at the upper end portion and extending in the vertical direction are in a given plane arrangement, and the opening of the internal thread portion is the reinforced concrete structure A plurality of fixing bolt insertion holes are embedded in the peripheral portion of the lower flange plate of the seismic isolation device in the same plane arrangement as the plane arrangement of the embedded bracket. Is formed, and the fixing bolt inserted through the fixing bolt insertion hole of the lower flange plate is screwed into the female thread portion of the embedded metal fitting, The lower flange plate is fixedly joined to the reinforced concrete structure, and a plurality of main bars extending in parallel and horizontally extend in the vicinity of the upper surface of the reinforced concrete structure. The planar arrangement of the embedded metal fittings is arranged with an interval between two sides extending in a horizontal direction parallel to the extending direction of the plurality of main bars and the extending direction of the plurality of main bars. And a plurality of the embedded metal fittings are arranged on each side of the quadrilateral that has two sides extending in the horizontal direction perpendicular to each other and surrounds the laminated rubber. .
The joining structure according to the present invention for joining a seismic isolation device comprising a round laminated rubber having an upper flange plate at the upper end and a lower flange plate at the lower end to the reinforced concrete structure is the reinforced concrete structure. A plurality of embedded metal fittings having a female screw portion at least at the lower end portion and extending in the vertical direction are provided in a given plane arrangement, and the opening of the female screw portion is exposed on the lower surface of the reinforced concrete structure. Embedded in the peripheral flange of the upper flange plate of the seismic isolation device, a plurality of fixing bolt insertion holes are formed in the same plane arrangement as the plane arrangement of the embedded bracket, When the fixing bolt inserted into the fixing bolt insertion hole of the upper flange plate is screwed into the female thread portion of the embedded bracket, the upper flange plate A plurality of main bars extending in parallel with each other in the horizontal direction are spaced apart in the vicinity of the lower surface of the reinforced concrete structure. The planar arrangement of the embedded metal fittings is orthogonal to two sides extending in a horizontal direction parallel to the extending direction of the plurality of main bars and the extending direction of the plurality of main bars. It is an arrangement in which a plurality of the embedded metal fittings are positioned on each side of a quadrilateral having two sides extending in the horizontal direction and surrounding the laminated rubber.

  According to the present invention, it is composed of a round laminated rubber that can facilitate the design and construction of reinforcing bars for reinforced concrete structures such as footings and beams that join seismic isolation devices while having sufficient strength. A joint structure for joining the seismic isolation device to the reinforced concrete structure is obtained.

A and B are a plan view and a side view of a joint structure according to a first embodiment of the present invention for joining a seismic isolation device made of round laminated rubber to a reinforced concrete structure. A and B are a plan view and a side view of a joining structure according to a conventional example for joining a seismic isolation device made of round laminated rubber to a reinforced concrete structure. A and B are a plan view and a side view of a joint structure according to a second embodiment of the present invention for joining a seismic isolation device made of round laminated rubber to a reinforced concrete structure. A and B are a plan view and a side view of a joint structure according to a third embodiment of the present invention for joining a seismic isolation device made of round laminated rubber to a reinforced concrete structure. FIGS. 8A and 8B are a plan view and a vertical sectional view of a joint structure according to a fourth embodiment of the present invention for joining a seismic isolation device made of round laminated rubber to a reinforced concrete structure. FIGS. A and B are a plan view and a side view of a joint structure according to a fifth embodiment of the present invention for joining a seismic isolation device made of round laminated rubber to a reinforced concrete structure. A and B are a plan view and a vertical sectional view of a joint structure according to a sixth embodiment of the present invention for joining a seismic isolation device made of round laminated rubber to a reinforced concrete structure.

  1A and 1B are a plan view and a side view of a joint structure according to a first embodiment of the present invention for joining a seismic isolation device made of round laminated rubber to a reinforced concrete structure. In the figure, a seismic isolation device 10 made of a round laminated rubber 12 is shown. The round laminated rubber 12 includes an upper flange plate 14 made of a steel plate at its upper end, and a lower flange plate made of a steel plate at its lower end. 16 is provided. The round laminated rubber 12 is configured by alternately laminating a plurality of rubber layers and a plurality of steel plate layers. The planar shape of the rubber layer and the steel plate layer is circular, and therefore the shape of the round laminated rubber 12 is cylindrical.

  In the drawing, a reinforced concrete structure 20 is further shown. The reinforced concrete structure 20 in the illustrated example includes a footing 22 and an underground beam 24 connected to the footing 22. The main bar 26 of the underground beam 24 extends through the footing 22, and the lower flange plate 16 of the seismic isolation device 10 is joined to the upper surface of the footing 22. On the other hand, the upper flange plate 14 of the seismic isolation device 10 is joined to the lower surface of a reinforced concrete building frame (not shown), and the joining structure is between the lower flange plate 16 and the footing 22 described in detail below. The upper and lower sides of the joint structure are inverted.

  A plurality of main bars 26 of the underground beam 24 are arranged from a region near the upper surface of the underground beam 24 to a region near the upper surface of the footing 22, and these main bars 26 are parallel to each other and horizontally ( It extends in the longitudinal direction of the footing 22 and the underground beam 24, and is arranged in the horizontal direction (in the width direction of the footing 22 and the underground beam 24) at intervals. In the figure, 28 is a reinforcing bar.

  On the upper surface of the footing 22, a plurality of embedded metal fittings 30 having an internal thread portion at least at the upper end portion and extending in the vertical direction are embedded, and the embedded metal fittings 30 have a given planar arrangement, and The opening of the female screw portion is embedded so as to be exposed on the upper surface of the footing 22. The buried metal fitting 30 in the illustrated example is composed of a long nut that constitutes the upper end portion thereof, and an anchor bolt that is joined to the lower end of the long nut and extends downward. However, it is also possible to use a buried bracket different from the illustrated example. For example, if the long nut is sufficiently long and the long nut itself functions as an anchor bolt, the anchor It is also possible to omit the bolt. In addition, a cap nut may be used instead of the long nut. In that case, an anchor bolt may be joined to the cap nut, and the cap nut is sufficiently long. You may make it fulfill | perform the function of an anchor bolt itself.

  In order to accurately place the plurality of embedded metal fittings 30 in a given plane arrangement, in the illustrated example, the embedded metal fittings 30 are welded and joined to a base plate 32 made of a steel plate to constitute a base plate assembly. By placing the footing 22 and the underground beam 24 and laying the formwork, placing the base plate assembly at the target position and placing concrete, the plurality of buried fittings 30 are arranged in a given plane arrangement. The reinforced concrete structure 20 embedded in is constructed.

  The upper flange plate 14 and the lower flange plate 16 have the same configuration except that they are vertically inverted. The flange plates 14 and 16 have a circular shape, and a plurality of fixing bolt insertion holes are formed on the peripheral edge portions of the flange plates 14 and 16 in the same plane arrangement as that of the embedded metal fitting 30. . The fixing bolts 34 inserted through the fixing bolt insertion holes are screwed into the respective female thread portions of the long nuts of the plurality of buried fittings 30, whereby the lower flange plate 16 is fixedly joined to the footing 22. Further, the upper flange plate 14 is fixedly coupled to a building frame not shown.

  Hereinafter, the planar arrangement of the embedded metal fitting 30 (accordingly, the planar arrangement of the fixing bolt insertion holes) in the present invention will be described. As a comparative example, FIGS. 2A and 2B show a plan view and a side view of a joining structure according to a conventional example for joining a seismic isolation device made of round laminated rubber to a reinforced concrete structure. In FIG. 1A and FIG. 2A, a circle with reference number “14 (16)” represents the outer peripheral shape of the upper flange plate 14 and the lower flange plate 16, and reference number “30 (34). A plurality of small circles marked with “)” represent the position of the embedded metal fitting 30 (therefore, the position of the fixing bolt insertion hole through which the fixing bolt 34 is inserted). In the conventional joining structure shown in FIG. 2, a plurality of embedded metal fittings 30 are arranged at equal angular intervals on one circle, whereas in the present invention, a plurality of embedded metal fittings 30 are arranged as shown in FIG. The embedded metal fittings 30 are arranged on the sides of the quadrilateral, that is, two sides extending in a horizontal direction parallel to the extending direction of the main reinforcing bars 26 and a horizontal direction orthogonal to the extending direction of the main reinforcing bars 26. The planar arrangement is such that a plurality of embedded metal fittings 30 are positioned on each side of the quadrilateral surrounding the laminated rubber 10. In the embodiment shown in FIG. 1, three embedded metal fittings 30 are located on each side of the quadrilateral, and the number of embedded metal fittings 30 located on each side of the quadrilateral is three. The above is preferable.

  As apparent from a comparison between FIG. 1 and FIG. 2, if the structure and dimensions of the round laminated rubber 12 used in the joining structure according to the present invention and the joining structure of the conventional example are the same, When the shapes of the upper and lower flange plates 14 and 16 are circular, the flange plate in the joining structure according to the present invention has a larger diameter than the flange plate in the joining structure of the conventional example.

  In particular, in the joint structure of the conventional example of FIG. 2, the embedded metal fittings 30 positioned near the side edges of the footing 22 and the underground beam 24 are connected to each other in the width direction of the footing 22 and the underground beam 24. The separation distance L between 30 becomes small. Since the main reinforcing bars 26 are arranged in the vicinity of the upper surfaces of the footing 22 and the underground beam 24, the embedded metal fitting 30 extending in the vertical direction is connected to the main reinforcement 26 when viewed from the side of the footing 22 and the underground beam 24. It is in a positional relationship that intersects. For this reason, in arranging the main reinforcement 26, it is necessary to arrange the arrangement of the embedded furniture 30, and the design and construction of the arrangement of the reinforcement is troublesome. On the other hand, in the joint structure according to the present invention in FIG. 1, it is possible to make the size of the separation distance L between the embedded metal fitting 30 in the width direction of the footing 22 and the underground beam 24 uniform. Since the separation distance L can be set to a sufficiently large size, the design and construction related to the bar arrangement of the main reinforcement 26 are greatly facilitated.

  Below, the junction structure which concerns on the 2nd Embodiment-7th Embodiment of this invention is demonstrated. All of the joint structures have the same configuration as the joint structure of FIG. 1 described above, and corresponding components are denoted by the same reference numerals, and the joint structure of FIG. Only the differences will be described in detail.

  3A and 3B are a plan view and a side view showing a joint structure according to a second embodiment of the present invention for joining a seismic isolation device made of round laminated rubber to a reinforced concrete structure. It is. In the joining structure of FIG. 3, the planar shape of the upper and lower flange plates 14 and 16 is a regular octagon, and in order to increase the bending rigidity of the flange plates 14 and 16, a steel plate reinforcing plate 36 is added to the peripheral portion. In other respects, the structure is the same as that of the joint structure of FIG. Four reinforcing plates 36 are added to each of the upper and lower flange plates 14, 16 and are fastened together with the flange plates 14, 16 by fixing bolts 34.

  4A and 4B are a plan view and a side view, respectively, showing a joint structure according to a third embodiment of the present invention for joining a seismic isolation device made of round laminated rubber to a reinforced concrete structure. It is. The joining structure in FIG. 4 is almost the same as the joining structure in FIG. 3, and the only difference is that the reinforcing plate 36 is fastened with fixing bolts 34 in order to increase the bending rigidity of the upper and lower flange plates 14, 16. Instead, a steel reinforcing member 38 joined to the peripheral edge of the flange plates 14 and 16 by welding is used.

  A plan view and a vertical sectional view in FIGS. 5A and 5B show a joint according to a fourth embodiment of the present invention for joining a seismic isolation device made of round laminated rubber to a reinforced concrete structure. Structure. In the joining structure of FIG. 5 as well, the planar shape of the upper and lower flange plates 14 and 16 is a regular octagon as in the joining structures of FIGS. 3 and 4, but in order to increase the bending rigidity of the flange plates 14 and 16. Further, a thick portion 40 is formed at the peripheral portion. Furthermore, in the joining structure of FIG. 5, a so-called connected steel plate type laminated rubber is used as the round laminated rubber 12. That is, the round laminated rubber in the joining structure of FIGS. 1, 3 and 4 is formed by alternately stacking the steel plate layers and the rubber layers to form an integrated laminated body. Whereas the flange plate 16 is integrated with the laminated body, the upper and lower flange plates 14 and 16 are different from the laminated body in the round laminated rubber 12 of FIG. It is manufactured as a body steel plate member and is connected to the laminate by bolts 48. Therefore, as shown in the vertical cross-sectional view of FIG. 5B, the laminated body in which the steel plate layers and the rubber layers are alternately laminated is integrated with the uppermost steel plate layer 44 and the lowermost steel plate layer 46. It is made thicker than the other steel plate layers so that the upper and lower flange plates 14 and 16 can be connected to the steel plate layers 44 and 46 by bolts 48, respectively. As described above, in the laminated laminated rubber 12 of the connected steel plate type in which the uppermost layer and the lowermost steel plate layers 44 and 46 of the laminated body are thickened and the upper and lower flange plates 14 and 16 are connected to the steel plate layers 44 and 46. When the round laminated rubber 12 is actuated due to an earthquake, the horizontal shear deformation amount of the upper end portion and the lower end portion of the laminated body is horizontal (because the steel plate layers 44 and 46 are present). It can be kept smaller than the directional shear deformation. Therefore, even if the thick portion 40 or the fixing bolt 34 is located quite close to the peripheral wall of the upper end portion and the lower end portion of the laminated body of the round laminated rubber 12, the thick portion 40 or the fixing bolt 34 is not There is an advantage that there is no fear of being damaged by coming into contact with the peripheral wall of the laminate.

  6A and 6B are a plan view and a side view, which show a joint structure according to a fifth embodiment of the present invention for joining a seismic isolation device made of round laminated rubber to a reinforced concrete structure. It is. In the joining structure of FIG. 7, in order to make the upper and lower flange plates 14, 16 compact, the planar shape thereof is a square. The planar arrangement of the embedded metal fitting 30 (therefore, the planar arrangement of the fixing bolt insertion holes) has two sides extending in the horizontal direction parallel to the extending direction of the main reinforcing bars 26 and a horizontal direction perpendicular to the extending direction of the main reinforcing bars 26. Each of the four sides of the quadrilateral surrounding the laminated rubber 10, and four embedded fittings 30 are positioned on each side of the quadrilateral. The planar arrangement is such that three embedded metal fittings 30 are located at each corner. Of the plurality of embedded metal fittings 30, the four embedded metal fittings 30 positioned at the four apex angles of the quadrilateral have a large separation distance from the round laminated rubber 12. In order to increase the bending rigidity of the plates 14 and 16, the thickness of the flange plates 14 and 16 is increased.

  7A and 7B are a plan view and a side view showing a joint structure according to a fifth embodiment of the present invention for joining a seismic isolation device made of a round laminated rubber to a reinforced concrete structure. It is. The joining structure in FIG. 7 is obtained by further reducing the size of the upper and lower flange plates 14 and 16 in the joining structure in FIG. 6, and the fixing bolt 34 is closer to the laminated body of the round laminated rubber 12. Similar to the joining structure of FIG. 5, the connecting steel plate type round laminated rubber 12 is used, thereby eliminating the possibility of the fixing bolt 34 coming into contact with the peripheral wall of the laminated body of the round laminated rubber 12 and damaging it. Yes. In the joint structure of FIG. 7, the upper and lower flange plates 14 and 16 are extremely small, so that they are strong against bending, and therefore means for increasing the bending rigidity is unnecessary.

  The above description is about the structure of the portion where the lower flange plate 16 of the round laminated rubber 12 is joined to the upper surface of the footing 22, but the upper flange plate 14 of the round laminated rubber 12 is made of reinforced concrete. The structure of the part to be joined to the lower surface of the building frame of the building may be a structure in which the above-described structure is turned upside down. In such a structure, at least the lower end part of the reinforced concrete structure has a female screw part. A plurality of embedded metal fittings extending in the vertical direction are embedded in a given plane arrangement so that the opening of the female screw portion is exposed on the lower surface of the reinforced concrete structure. . Further, a plurality of fixing bolt insertion holes are formed in the peripheral portion of the upper flange plate 14 of the seismic isolation device 10 in the same plane arrangement as those of the embedded metal fittings, and are inserted into the fixing bolt insertion holes. The upper fixing flange plate 14 is fixedly joined to the reinforced concrete structure by screwing the fixing bolts to the female thread portion of the embedded metal fitting. Further, in the vicinity of the lower surface of the reinforced concrete structure, a plurality of main bars extending in parallel with each other in the horizontal direction are arranged at intervals in the horizontal direction. The planar arrangement of the embedded metal fittings extends in the horizontal direction perpendicular to the extending direction of the plurality of main bars, and two sides extending in the horizontal direction parallel to the extending direction of the plurality of main bars. The planar arrangement may be such that a plurality of embedded fittings are located on each side of the quadrilateral that has two sides and surrounds the laminated rubber 12.

DESCRIPTION OF SYMBOLS 10 Seismic isolation device 12 Round laminated rubber 14 Upper flange plate 16 Lower flange plate 20 Reinforced concrete structure 22 Footing 24 Underground beam 26 Main reinforcement 28 Reinforcement 30 Embedded bracket 34 Fixing bolt 36 Reinforcement plate 38 Reinforcement material 40 Thick wall Part

Claims (8)

In a joining structure for joining a seismic isolation device made of round laminated rubber having an upper flange plate at the upper end and a lower flange plate at the lower end to a reinforced concrete structure,
On the upper surface of the reinforced concrete structure, a plurality of embedded metal fittings having an internal thread portion at least at the upper end portion and extending in the vertical direction are in a given plane arrangement, and the opening of the internal thread portion is the reinforced concrete structure It is buried so as to be exposed on the upper surface of the object,
In the periphery of the lower flange plate of the seismic isolation device, a plurality of fixing bolt insertion holes are formed in the same plane arrangement as the plane arrangement of the embedded metal fittings,
The lower flange plate is fixedly joined to the reinforced concrete structure by screwing the fixing bolt inserted into the fixing bolt insertion hole of the lower flange plate into the female thread portion of the embedded metal fitting. And
In the vicinity of the upper surface of the reinforced concrete structure, a plurality of main bars extending in parallel with each other in the horizontal direction are arranged at intervals in the horizontal direction,
The planar arrangement of the embedded metal fittings extends in a horizontal direction perpendicular to the two sides extending in the horizontal direction parallel to the extending direction of the plurality of main bars and the extending direction of the plurality of main bars. A plurality of the embedded metal fittings are arranged on each side of the quadrilateral that has two sides and surrounds the laminated rubber,
A junction structure characterized by that. In a joining structure for joining a seismic isolation device made of round laminated rubber having an upper flange plate at the upper end and a lower flange plate at the lower end to a reinforced concrete structure,
On the lower surface of the reinforced concrete structure, a plurality of embedded metal fittings having an internal thread portion at least at the lower end portion and extending in the vertical direction are in a given plane arrangement, and the opening of the internal thread portion is the reinforced concrete structure It is buried so as to be exposed on the lower surface of the object,
In the peripheral portion of the upper flange plate of the seismic isolation device, a plurality of fixing bolt insertion holes are formed in the same planar arrangement as the planar arrangement of the embedded metal fittings,
The fixing bolt inserted through the fixing bolt insertion hole of the upper flange plate is screwed into the female thread portion of the embedded metal fitting so that the upper flange plate is fixedly joined to the reinforced concrete structure. And
In the vicinity of the lower surface of the reinforced concrete structure, a plurality of main bars extending in parallel with each other in the horizontal direction are arranged at intervals in the horizontal direction,
The planar arrangement of the embedded metal fittings extends in a horizontal direction perpendicular to the two sides extending in the horizontal direction parallel to the extending direction of the plurality of main bars and the extending direction of the plurality of main bars. A plurality of the embedded metal fittings are arranged on each side of the quadrilateral that has two sides and surrounds the laminated rubber,
A junction structure characterized by that.   The joining structure according to claim 1, wherein the planar arrangement is an arrangement in which at least three of the embedded metal fittings are positioned on each side of the quadrilateral.   The joining structure according to any one of claims 1 to 3, wherein the embedded metal fitting is fixedly joined to a base plate made of steel plate with the planar arrangement.   The joining structure according to any one of claims 1 to 4, wherein the upper flange plate and the lower flange plate are formed with a thick portion at a peripheral edge portion for increasing bending rigidity.   The joining structure according to any one of claims 1 to 4, wherein the upper flange plate and the lower flange plate are provided with a reinforcing member at a peripheral edge portion for increasing bending rigidity.   The joining structure according to any one of claims 1 to 6, wherein the round laminated rubber is a connected steel plate laminated rubber.   The said embedded metal fitting consists of a long nut, a cap nut, a long nut to which an anchor bolt is coupled, or a cap nut to which an anchor bolt is coupled. The junction structure described in the item.

Images