Joining structure

Abstract

To provide a junction structure capable of restricting a displacement between steel members by utilizing a shear capacity of a bolt, and the bolt to be used for this junction structure.SOLUTION: A junction structure 1 connects overlapped members by a bolt 5. An open hole 21 inserted through a shaft part 52 of the bolt 5 and capable of locking a head part 51 of the bolt 5 is formed at one member. A female screw part 43 to be screwed to the shaft part 52 of the bolt 5 is formed at other member. A taper reduced in diameter toward the shaft part 52 is formed on an outer surface of the head part 51 and a male screw part 54 to be screwed to the female screw part 43 and a shear deformation part 55 formed between the head part 51 and the male screw part 54 are formed at the shaft part 52. A same taper as the taper of the head part of the bolt 5 is formed on an inner surface of the open hole 21. An inner diameter of a part corresponding to the shear deformation part 55 of the female screw part 43 is larger than the outer diameter of the shear deformation part 55.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a joining structure for joining steel materials to each other. manufacture

Background Art

[0002] Conventionally, when joining steel materials to each other, it has been common to use rivets. The joining structure using rivets joins members so that rattling does not occur by filling holes formed in the steel materials with heated rivets. The rivets inserted into the holes without gaps join the members by shear force.

[0003] However, since heated rivets need to be handled carefully, work at heights or in unstable locations is time-consuming for construction. In addition, it is necessary to arrange a device for heating the rivets at the site, which also incurs costs. Therefore, the joining structure using rivets has been an obstacle to early construction and cost reduction of the project.

[0004] On the other hand, currently, as a joining structure for steel materials, friction joining using high-strength bolts is generally adopted (see, for example, Patent Document 1). In friction joining, in a state where the steel materials are overlapped, both steel materials are tightened with high-strength bolts, and the displacement at the joint is suppressed by the frictional force on the contact surface between the steel materials. Therefore, even if the bolt diameter is smaller than the bolt hole diameter and there is a clearance, there is no problem in performance, so construction is carried out with a larger clearance considering construction errors, and there is no problem in construction either. However, in friction joining, in order to ensure the necessary frictional force, it is necessary to appropriately manage the friction surface and the tightening force, so the construction requires skill and time.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In shear joining with bolts, joining of steel materials requires the use of a plurality of bolts. However, due to manufacturing errors, construction errors, etc., misalignment may occur in the positions of bolt holes. If there is misalignment in the bolt holes, the bolts cannot be inserted. Therefore, it is common to secure a clearance that can absorb errors, such as enlarging the bolt holes. However, if a clearance is secured in the bolt holes, there is a risk of misalignment by the amount of the clearance when a load acts on the joint. When misalignment occurs in the joint, deformation occurs in the structure.

[0007] An object of the present invention is to propose a joint structure that can suppress misalignment between steel materials in shear joining with bolts. manufacture

Means for Solving the Problems

[0008] The joint structure of the present invention for solving such problems joins, in a stacked state, one member in which a through-hole is formed through which the shaft portion of a bolt can be inserted and the head of the bolt can be locked, and the other member in which a female screw portion that can be screwed with the shaft portion is formed. An inclined surface that reduces in diameter as it approaches the shaft portion is formed on the outer surface of the head of the bolt. Further, on the shaft portion of the bolt, a male screw portion that is screwed with the female screw portion and a shear deformation portion formed between the head and the male screw portion are formed. Further, an inclined surface equivalent to the inclined surface of the head is formed on the inner surface of the through-hole. Furthermore, the minimum inner diameter of at least the portion of the female screw portion corresponding to the shear deformation portion is larger than the maximum outer diameter of the shear deformation portion. so that the minimum inner diameter of the through hole is 2 mm to 3 mm larger than the maximum outer diameter of the shaft portion of the bolt

[0009] ​According to such a joining structure, a taper (inclined surface) capable of locking the head of a bolt to the inner surface of the through hole is formed, and since this through hole has an inner diameter larger than the thread diameter of the male screw portion, even if there is a deviation in the position between the central axis of the through hole and the central axis of the female screw portion, it is easy to screw the male screw portion into the female screw portion. Since the bolt has a taper (inclined surface) on its head, when it is screwed into the female screw portion, the head closely adheres to the inner surface of the through hole. At this time, the deviation in the position (central axis) between the female screw portion and the through hole is absorbed by the shear deformation portion being shear-deformed by the required shear force. Therefore, even if an external force smaller than the required shear force acts on the joint portion, there will be no deviation between the members.

[0010] bolt The bolt is formed with a head having a taper that reduces in diameter as it approaches the shaft portion on the outer surface, a male screw portion having a thread formed on the outer surface, and a shear deformation portion having an outer diameter smaller than the root diameter of the thread crest of the male screw portion between the male screw portion and the head. therefore If the outer diameter of the shear deformation portion is smaller than the root diameter of the thread crest of the male screw portion, it can be shear-deformed at the shear deformation portion without damaging the male screw portion.

[0011] The joining structure may join a first steel pipe (one member) and a second steel pipe having a joining steel plate (the other member) fixed to its end. At this time, a part of the joining steel plate protrudes from the tip of the second steel pipe and is fixed to the inner surface of the second steel pipe, and the joining steel plate overlapped on the inner surface of the first steel pipe is joined to the first steel pipe by butting the end faces of the first steel pipe and the second steel pipe against each other. By doing so, it is possible to join the steel pipes so that rattling does not occur. two steels By doing so, it is possible to join the steel pipes so that rattling does not occur.

Advantages of the Invention

[0014] The joining structure of the present invention manufacture makes it possible to reduce the labor during construction and suppress the occurrence of deviation between steel materials by utilizing the shear strength of the bolt.

Brief Description of the Drawings

[0015]

Figure 1

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Modes for Carrying Out the Invention

[0016] <First Embodiment> In the first embodiment, the joining structure 1 between steel pipes constituting a steel pipe column will be described. As shown in FIGS. 1(a) and 1(b), the joining structure 1 of this embodiment joins square steel pipes (first steel pipe 2 and second steel pipe 3) with the same cross-section arranged vertically, with their end faces butted against each other. The first steel pipe 2 and the second steel pipe 3 are integrally joined by the joining structure 1. The joining structure 1 of this embodiment joins the first steel pipe 2 (one member) and a joining steel plate 4 (the other member) fixed to the end of the second steel pipe 3 with bolts 5.

[0017] As shown in FIG. 2(a), through holes 21 are formed in six locations in three vertical rows and two horizontal rows (a total of six locations) on each face at the lower end of the first steel pipe 2 (the end on the side of the second steel pipe 3). As shown in FIGS. 2(b), 3(a), and 4(a), the through holes 21 have a shape that allows the shaft portion 52 of the bolt 5 to be inserted and the head portion 51 of the bolt 5 to be housed and locked. That is, the minimum inner diameter of the through hole 21 is made about 2 mm (hole clearance with a track record in high-strength bolt joining, 3 mm when the bolt outer diameter is 27 mm or more) larger than the outer diameter of the male screw portion 54, which is the maximum outer diameter of the shaft portion 52 of the bolt 5. As shown in FIG. 4(a), an inclined surface (taper) is formed on the inner surface of the through hole 21. The taper of the through hole 21 in this embodiment has a vertical-to-horizontal ratio of the gradient of 5:1 (11.3° with respect to the central axis of the through hole 21), but the gradient of the through hole 21 is not limited as long as it is 45° or less, preferably 10° or more and 30° or less, with respect to the central axis of the through hole 21.

[0018] As shown in Fig. 2(b), a joining steel plate 4 is fixed to the inner surface of the upper end portion (the end portion on the first steel pipe 2 side) of the second steel pipe 3. The joining steel plate 4 has a base portion 41 fixed to the inner surface of the second steel pipe 3, and the other portion (the protruding portion 42) protrudes from the tip of the second steel pipe 3. Further, two slits 31, 31 are formed on each surface of the upper end portion of the second steel pipe 3. The slit 31 is a groove for welding the joining steel plate 4 to the inner surface of the second steel pipe 3, as shown in Figs. 2 and 3(b). The length of the slit 31 (the length along the axial direction of the second steel pipe 3) in the present embodiment is set to be equal to or less than the length of the base portion 41 of the joining steel plate 4. Note that the width and length of the slit 31 are not limited, and the dimensions are such that a shape capable of integrally fixing the joining steel plate 4 can be ensured.

[0019] As shown in Fig. 2(b), the joining steel plate 4 is disposed across both steel pipes in a state of being overlapped on the inner surfaces of the first steel pipe 2 and the second steel pipe 3. As shown in Figs. 3(a) and (b), in the present embodiment, the joining steel plate 4 is fixed to each surface of the second steel pipe 3. The base portion 41 of the joining steel plate 4 is welded to the inner surface of the second steel pipe 3 using the slit 31. That is, in a state where the joining steel plate 4 is in contact with the inner surface of the second steel pipe 3, the portion exposed to the outside by the slit 31 is welded from the outside of the second steel pipe to the corner portion with the slit 31, as shown in Fig. 3(b). Further, the four joining steel plates 4, 4,... are welded at the contact portions of the edges (the corners formed by the side surfaces) and exhibit a cylindrical shape. Note that in order to accommodate the accuracy of the steel pipe, the base portion 41 of the joining steel plate 4 and the inner surface of the second steel pipe 3 may be welded with a gap (about 1 mm). Also, the joining steel plates 4 do not necessarily need to be welded to each other.

[0020] As shown in FIGS. 1(b) and 2(b), female screw portions 43, 43,... are formed in six locations in two horizontal rows in three vertical stages on the protruding portion 42 of the joining steel plate 4. The female screw portions 43 correspond to the positions of the through holes 21 of the first steel pipe 2. When the end faces of the first steel pipe 2 and the second steel pipe 3 are butted against each other, the female screw portions 43 of the joining steel plate 4 and the through holes 21 of the first steel pipe 2 communicate with each other. As shown in FIG. 4(a), female screws into which the male screw portions 54 of the bolts 5 can be screwed are formed over the entire length (the length in the thickness direction of the joining steel plate) on the inner surfaces of the female screw portions 43.

[0021] As shown in FIG. 4(a), the bolt 5 includes a head portion 51 locked to the through hole 21 and a shaft portion 52 screwed into the female screw portion 43. On the outer surface of the head portion 51, an inclined surface (taper) that reduces in diameter as it approaches the shaft portion 52 is formed. The gradient of the taper formed on the outer surface of the head portion 51 is made equal to the gradient of the taper (inner wall surface) of the through hole 21 (the aspect ratio is 5:1). Also, the length of the taper of the head portion 51 is made equal to the length of the taper of the through hole 21. That is, the head portion 51 of the bolt 5 has a shape such that substantially the whole of it fits into the through hole 21 when inserted into the through hole 21. As shown in FIG. 4(b), a recess (hexagonal hole) 53 having a hexagonal shape in plan view that opens on the upper surface is formed in the head portion 51. The bolt 5 can be tightened by a tool such as a hexagonal bar wrench using the recess 53.

[0022] As shown in FIG. 4(a), on the shaft portion 52, a male screw portion 54 having a screw (male screw) formed on the outer surface and a shear deformation portion 55 formed between the male screw portion 54 and the head portion 51 are formed. The outer surface of the shear deformation portion 55 does not have a male thread, and the outer diameter of the shear deformation portion 55 is made smaller than the root diameter of the male thread portion 54. Therefore, the outer diameter of the shear deformation portion 55 is smaller than the inner diameter of the female thread portion 43. That is, when the bolt 5 is screwed into the female thread portion 43 with the axis of the shaft portion 52 and the axis of the female thread portion 43 being aligned, a gap having a dimension in which the outer diameter of the shear deformation portion 55 is smaller than the root diameter of the male thread portion 54 is formed between the outer surface of the shear deformation portion 55 and the female thread portion 43. It is desirable that the size of the gap between the shear deformation portion 55 and the female thread portion 43 be about half of the difference between the hole-to-hole dimension P2 between adjacent female thread portions 43 and the hole-to-hole dimension P1 between adjacent through holes 21 (see Fig. 5).

[0023] For the joining structure 1, first, the base portion 41 of the joining steel plate 4 is welded to the end portion of the second steel pipe 3. The joining steel plate 4 may be welded to the upper end of the second steel pipe 3 built in at a predetermined position at the construction site, or may be welded to the end portion of the second steel pipe 3 in advance and then the second steel pipe 3 may be built in at a predetermined position. Next, the first steel pipe 2 is joined from above the second steel pipe 3. The end face of the second steel pipe 3 is abutted against the end face of the first steel pipe 2, and the protruding portion 42 of the joining steel plate 4 fixed to the second steel pipe 3 is inserted into the inner cavity of the first steel pipe 2. By inserting the protruding portion 42 into the inside of the first steel pipe 2, the protruding portion 42 is brought into a state of being in contact with the inner surface of the second steel pipe 3. Subsequently, the first steel pipe 2 and the second steel pipe 3 (joining steel plate 4) are fixed by fastening the shaft portion 52 of the bolt 5 that has passed through the through hole 21 to the female thread portion 43.

[0024] As shown in Fig. 5, even if there is a difference between the hole-to-hole dimension P1 between adjacent through holes 21 and the hole-to-hole dimension P2 between adjacent female screw portions 43, the bolt 5 deforms at the shear deformation portion 55, so that the head 51 of the bolt 5 is in close contact with the inner surface of the through hole 21, and the first steel pipe 2 and the joining steel plate 4 (second steel pipe 3) can be joined. That is, by deforming at the shear deformation portion 55 which is smaller than the female screw portion 43 and has a gap with the inner diameter of the female screw portion 43, the dimensional difference between the through hole 21 and the female screw portion 43 can be absorbed. At this time, at the shear deformation portion 55, displacement by an adjustment dimension ΔT (= (P1 - P2) / 2) which is half of the difference between the hole-to-hole dimension P1 between adjacent through holes 21 and the hole-to-hole dimension P2 between adjacent female screw portions 43 occurs, thereby absorbing the deviation.

[0025] According to the joining structure 1 of the present embodiment, since a taper having the same shape as the taper of the head 51 of the bolt 5 is formed on the inner surface of the through hole 21, the head 51 of the bolt 5 is locked to the through hole 21, and force transmission between the bolt 5 and the first steel pipe 2 is ensured. On the other hand, by fastening the shaft portion 52 of the bolt 5 to the female screw portion 43, force transmission between the bolt 5 and the joining steel plate 4 becomes possible. As a result, the first steel pipe 2 and the joining steel plate 4 are joined so that force transmission is possible via the bolt 5. Further, since the joining steel plate 4 is welded to the second steel pipe 3, the first steel pipe 2 and the second steel pipe 3 are joined via the joining steel plate 4. The first steel pipe 2 and the joining steel plate 4 (second steel pipe 3) are not joined by the frictional force between the members, but are joined by the shear strength of the bolt 5. Therefore, unlike high-strength bolt friction joining, they are not joined by the frictional force between the members due to the tightening force, but can be joined relatively simply by the shear force of the bolt 5.

[0026] Further, since the through hole 21 has an inner diameter larger than or equal to the clearance of a high-strength bolt with construction results with respect to the shaft portion 52 of the bolt 5, even if there is a deviation in the position between the central axis of the through hole 21 and the central axis of the female screw portion 43, the bolt 5 can be easily screwed into the female screw portion 43. Further, the deviation in the position (central axis) between the female screw portion 43 and the through hole 21 is absorbed by the shear deformation of the shear deformation portion 55. Therefore, even when an error occurs during construction or during member manufacturing, the bolt can be fastened.

[0027] In the case of high-strength bolt friction joints, when an excessive force exceeding the frictional force is applied due to a major earthquake or the like, slippage of the hole clearance occurs and deformation and impact are applied to the structure. Therefore, a safety factor calculation is required and an increase is necessary. On the other hand, in the joining structure 1 of the present embodiment, since there is no hole clearance, even when a force exceeding the allowable shear strength of the bolt steel material is applied, the toughness of the steel material (the property of stretching while holding the force) maintains the safety factor, so it is more stable than a friction joint with a slippage phenomenon.

[0028] Since the first steel pipe 2 and the joining steel plate 4 are joined via the bolt 5 so that stress can be transmitted, it is not always necessary for the first steel pipe 2 and the joining steel plate 4 to be in close contact like a friction joint. Therefore, even when a slight gap is formed between the first steel pipe 2 and the joining steel plate 4 due to the relationship between the shape of the steel pipe (the first steel pipe 2 or the second steel pipe 3) and the shape of the joining steel plate 4, the joinability can be ensured.

[0029] Since the outer diameter of the shear deformation part 55 is smaller than the root diameter of the male screw part 54, it becomes easier to shear-deform at the shear deformation part 55. Even when there is a deviation between the through hole 21 and the female screw part 43, when the shear deformation part 55 is sheared and deformed (elastic deformation to plastic deformation) first, assuming that the maximum shear strength is reached, other parts of the bolt 5, the through hole 21 or the female screw part 43 are designed not to be damaged. Also, it is advisable to design with the shear force within the elastic range of the shear deformation part 55 against the force causing deviation between the first steel pipe 2 and the joining steel plate 4.

[0030] Since the head 51 of the bolt 5 fits almost entirely within the through hole 21, the bolt 5 hardly protrudes from the outer surface of the first steel pipe 2. Also, since the outer surface of the head 51 of the bolt 5 is in close contact with the inner surface of the through hole 6, it is difficult to loosen. The taper of the through hole 21 functions as a guide when inserting the bolt 5.

[0031] Also, by setting the taper gradient such that the aspect ratio is 5:1 (45° or less with respect to the central axis of the through-hole 21, preferably 10° or more and 30° or less), while tightening the bolt 5, the shear deformation part 55 can be shear-deformed following the taper. Note that if the taper angle is too large, the horizontal force becomes small with respect to the tightening force of the bolt 5, making it difficult to shear-deform the shear deformation part 55.

[0032] <Second Embodiment> In the second embodiment, as shown in FIG. 6, a joining structure 10 for joining overlapping members (the first member 20 and the second member 40) with a bolt 50 will be described. As shown in FIG. 7, a through-hole 21 through which the shaft portion 52 of the bolt 50 can be inserted is formed in the first member 20. As shown in FIG. 8, the through-hole 21 secures a predetermined clearance (0.4 mm in this embodiment: mutual deviation ±0.2 mm) with respect to the shaft portion 52 (base portion 57).

[0033] Also, as shown in FIG. 7, a screw hole having a female screw portion 43 that can be screwed with the male screw portion 54 of the bolt 50 is formed in the second member 40. An inclined surface is formed on the inner surface of the upper end portion (the end portion on the first member side) of the screw hole (female screw portion 43). Note that the second member 40 of this embodiment has a larger member thickness than the first member 20, but the relative magnitudes of the member thicknesses of the first member 20 and the second member 40 are not limited, and for example, they may have the same thickness.

[0034] As shown in FIGS. 6 and 7, the bolt 50 includes a head portion 51 locked to the first member 20 and a shaft portion 52 screwed with the female screw portion 43. The head portion 51 has a width larger than the outer diameter of the through-hole 21. The bolt 50 of this embodiment is a so-called hexagonal bolt having a head portion 51 that is hexagonal in plan view, but the shape of the head portion 51 is not limited, and for example, a so-called bolt with a hexagonal hole in which a hexagonal recess (hexagonal hole) 53 that opens on the upper surface is formed in plan view may be used.

[0035] As shown in FIGS. 6 and 7, the shaft portion 52 includes a base portion 57 provided on the head portion 51 side, a male screw portion 54 having an outer diameter smaller than that of the base portion 57 with a screw formed on the outer surface, a shear deformation portion 55 formed between the male screw portion 54 and the head portion 51 and having an outer diameter smaller than that of the male screw portion 54, and a tapered portion 58 formed between the base portion 57 and the shear deformation portion 55 and having an inclined surface that tapers as it approaches the shear deformation portion 55.

[0036] The shear deformation portion 55 of the present embodiment is formed at the end of the male screw portion 54 on the base portion 57 side. The shear deformation portion 55 is formed at a position where it is inserted into the screw hole (female screw portion 43). The outer surface of the shear deformation portion 55 does not have a male screw, and the outer diameter of the shear deformation portion 55 is made smaller than the root diameter of the male screw portion 54. Therefore, the outer diameter of the shear deformation portion 55 is smaller than the inner diameter of the female screw portion 43. That is, when the bolt 5 is screwed into the female screw portion 43 with the axis of the shaft portion 52 and the axis of the female screw portion 43 aligned, a gap having a dimension such that the outer diameter of the shear deformation portion 55 is smaller than the root diameter of the male screw portion 54 is formed between the outer surface of the shear deformation portion 55 and the female screw portion 43.

[0037] The tapered portion 58 is composed of an inclined surface equivalent to the inclined surface formed on the inner surface of the screw hole (female screw portion 43). In this embodiment, a disc spring washer 8 is provided between the head portion 51 of the bolt 50 and the first member 20. The disc spring washer 8 can pass through the base portion 57 of the bolt 50.

[0038] For the joining structure 1, first, the first member 20 and the second member 40 are overlapped. At this time, the centers of the through holes 21 of the first member 20 and the center of the screw hole (female screw portion 43) of the second member 40 may be misaligned. Subsequently, as shown in FIGS. 9(a) and (b), the male screw portion 54 of the bolt 50 passing through the through hole 21 is fastened to the female screw portion 43 to fix the first member 20 and the second member 40.

[0039] When the male screw portion 54 having an outer diameter smaller than that of the through hole 21 is screwed into the female screw portion 43, as shown in FIG. 9(a), the tapered portion 58 abuts against the edge of the through hole 21. By adjusting the position of the central axis of the through hole 21 and the central axis of the female screw portion 43 by the horizontal correction force due to the tightening force of the bolt 50, the base portion 57 is inserted into the through hole 21 with a small clearance (0.4 mm).

[0040] In this way, even when there is a deviation between the central axis of the through hole 21 of the first member 20 and the central axis of the screw hole of the second member 40, the bolt 5 deforms at the shear deformation portion 55 while the tapered portion 58 abuts against the edge of the through hole 21, so that the base portion 57 is guided into the through hole 21, and the first member 20 and the second member 40 can be joined in a state where the base portion 57 is in close contact with the inner surface of the through hole 21. That is, by deforming at the shear deformation portion 55 which is smaller than the female screw portion 43 and has a gap with the inner diameter of the female screw portion 43, the deviation is absorbed.

[0041] According to the joining structure 1 of the present embodiment, since the base portion 57 of the bolt 50 is in close contact with the inner surface of the through hole 21, the force transmission between the bolt 50 and the first member 20 is ensured. On the other hand, by fastening the shaft portion 52 (male screw portion 54) of the bolt 50 to the female screw portion 43, the force transmission between the bolt 50 and the second member 40 becomes possible. As a result, the first member 20 and the second member 40 are joined so that the force can be transmitted through the bolt 50. The first member 20 and the second member 40 are not joined by the frictional force between the members, but are joined by the shear strength of the bolt 50. Therefore, unlike the high-strength bolt friction joining, they are not joined by the frictional force between the members due to the tightening force, but can be joined relatively simply by the shear force of the bolt 50.

[0042] In addition, the deviation in the position (central axis) between the female screw portion 43 and the through hole 21 is absorbed by the shear deformation of the shear deformation portion 55. Therefore, even when an error occurs during construction or during member manufacturing, the bolt can be fastened. Further, since the shear deformation portion 55 undergoes shear plastic deformation, damage to the through hole 21, the female screw portion 43, etc. is prevented. By making the shear strength of the shear deformation portion 55 smaller than the allowable bearing strength of the through hole 21 and the allowable shear strength of the female screw portion 43 and setting it within the range of uniform elongation (within the maximum strength), the shear deformation portion 55 can be restored without being damaged and the required allowable shear force can be maintained.

[0043] In high-strength bolt friction joints, when excessive force exceeding the frictional force is applied due to a major earthquake or the like, slippage occurs in the hole clearance, causing deformation and impact on the structure. Therefore, a safety factor calculation is required and an increase is necessary. On the other hand, in the joining structure 10 of the present embodiment, since there is no hole clearance, even when a force exceeding the allowable shear strength of the bolt steel is applied, the toughness of the steel (the property of stretching while holding the force) maintains the safety factor, so it is more stable than a friction joint with a slippage phenomenon.

[0044] Since the first member 20 and the second member 40 are joined via the bolt 50 so that stress can be transmitted, it is not always necessary for the first member 20 and the second member 40 to be in close contact like a friction joint. Therefore, even when a slight gap is formed between the first member 20 and the second member 40, the joinability can be ensured.

[0045] Since the outer diameter of the shear deformation portion 55 is smaller than the root diameter of the male screw portion 54, it is easier to cause shear deformation in the shear deformation portion 55. Even when there is a deviation between the through hole 21 and the female screw portion 43, when the shear deformation portion 55 undergoes shear deformation (elastic deformation to plastic deformation) first, assuming that the maximum shear strength is reached, other parts of the bolt 50, the through hole 21, or the female screw portion 43 are designed not to be damaged. Also, it is advisable to design with the shear force within the elastic range of the shear deformation portion 55 against the force causing deviation between the first member 20 and the second member 40.

[0046] The embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and each of the above-described components can be appropriately changed without departing from the spirit of the present invention. For example, in the above embodiment, the case of connecting square steel pipes has been described, but the members joined to the joining structure 1 are not limited. For example, as shown in FIG. 10, the joining structure 1 of the present invention may be adopted for connecting steel pipes with a circular cross section. At this time, the joining steel plate 4 has an arc shape according to the cross-sectional shape of the steel pipes (the first steel pipe 2 and the second steel pipe 3).

[0047] Further, the joining structure 1 is not limited to the joining of steel pipes (steel pipe columns). For example, it may be adopted for the joining of other steel materials (H-shaped steel, I-shaped steel, channel steel, steel plates, etc.). Also, in the above embodiment, the case where female threads are formed in the female thread portion 43 has been described. However, a nut in which female threads are formed may be embedded. For example, as shown in FIGS. 11(a) and 11(b), the nut 44 may be configured to be insertable into the female thread portion 43. At this time, the nut 44 is preferably formed with an inclined surface (taper) at an angle of 45° or less, preferably 10° or more and 30° or less, with respect to the central axis of the female thread portion 43 (for example, the aspect ratio is 5:1). It is also desirable that an inclined surface (taper) with an equivalent gradient is formed on the inner surface of the female thread portion 43. By doing so, when the bolt 5 is tightened, the nut 44 adheres closely to the female thread portion 43, and a joining structure 1 capable of transmitting stress via the bolt 5 can be configured.

[0048] Also, in the above embodiment, the case where no threads are formed on the shear deformation portion 55 of the bolt 5 has been described. However, as shown in FIG. 12, threads may be formed over the entire length of the shaft portion 52 of the bolt 5. At this time, in the female thread portion 43, a diameter-expanded portion 45 having an inner diameter larger than the maximum outer diameter (thread crest) of the shear deformation portion 55 is formed corresponding to the position of the shear deformation portion 55. By doing so, a gap is formed between the shear deformation portion 55 and the female thread portion 43, enabling deformation in the shear deformation portion 55 and absorbing the displacement between the through hole 21 and the female thread portion 43.

[0049] In the above embodiment, the concave portion (hexagonal socket) 53 into which a tool can be inserted is formed in the head portion 51 of the bolt 5. However, the shape of the bolt 5 is not limited. For example, as shown in FIGS. 13(a) and 13(b), a locking portion 56 having a polygonal shape in plan view (hexagonal shape in FIG. 13) into which a tightening tool such as a wrench or a spanner can be locked may project from the upper surface of the head portion 51. Further, as shown in FIGS. 14(a) and 14(b), the head 51 of the bolt 5 may form a locking portion 56 having a polygonal shape in plan view (hexagonal in FIG. 14) that can lock a tightening tool such as a wrench or a spanner. At this time, as shown in FIG. 14(a), an inclined surface (taper) that reduces the diameter as it approaches the shaft portion 52 is formed at the boundary portion between the head 51 and the shaft portion 52.

[0050] In the second embodiment, the case where an inclined surface corresponding to the tapered portion 58 of the bolt 50 is formed on the inner surface of the threaded hole has been described. However, a tapered portion may be formed on the inner surface of the through hole according to the shape of the bolt 50.

Explanation of reference numerals

[0051] 1, 10 Joint structure 2 First steel pipe (one member) 20 First member (one member) 21 Through hole 3 Second steel pipe 31 Slit 4 Joint steel plate (the other member) 40 Second member (the other member) 41 Base portion 42 Protrusion 43 Female screw portion (bolt hole) 44 Nut 5, 50 Bolt 51 Head 52 Shaft portion 53 Recess 54 Male screw portion 55 Shearing deformation portion 57 Base portion 58 Tapered portion

Claims

1. A joining structure for joining stacked members with bolts, in one of the members, a through-hole is formed through which the shaft portion of the bolt can be inserted and the head of the bolt can be locked, in the other member, a female screw portion capable of screwing with the shaft portion is formed, on the outer surface of the head, an inclined surface that tapers as it approaches the shaft portion is formed, on the shaft portion, a male screw portion that screws with the female screw portion and a shear deformation portion formed between the head and the male screw portion are formed, on the inner surface of the through-hole, an inclined surface equivalent to the inclined surface of the head is formed, and the minimum inner diameter of the through-hole is 2 mm to 3 mm larger than the maximum outer diameter of the shaft portion of the bolt, A joining structure, characterized in that the minimum inner diameter of at least a portion of the female screw portion corresponding to the shear deformation portion is larger than the maximum outer diameter of the shear deformation portion.

2. The joining structure according to claim 1, characterized in that the outer diameter of the shear deformation portion is smaller than the valley diameter of the thread of the male screw portion.

3. one of the members is a first steel pipe, the other member is a joining steel plate fixed to the end of a second steel pipe, a part of the joining steel plate is fixed to the inner surface of the second steel pipe in a state of protruding from the tip of the second steel pipe, The joining structure according to claim 1 or claim 2, characterized in that the joining steel plate overlapped on the inner surface of the first steel pipe is joined to the first steel pipe with the bolt by butting the end faces of the first steel pipe and the second steel pipe against each other.

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