JPWO2011049170A1 - Steel pipe connection structure - Google Patents

Abstract

A steel pipe connection structure in which one steel pipe and the other steel pipe are connected in the longitudinal direction by meshing a shear protrusion or a load transmission key between the steel pipes, and the other steel pipe is connected to the one steel pipe side. A protrusion extending to the side, and a recess into which the protrusion is inserted is formed on the other steel pipe side; the one steel pipe and the other steel pipe of a connecting portion where the side surface and the bottom surface of the recess are connected Stress relaxation consisting of one of a curved surface, a surface intersecting an adjacent surface at an obtuse angle, or a combination thereof in a portion where bending force is generated due to out-of-plane deformation of the protrusion when a tensile load is applied between A shape portion is provided.

Description

The present invention relates to a steel pipe connection structure for connecting steel pipes in the longitudinal direction.
This application claims priority on October 21, 2009 based on Japanese Patent Application No. 2009-242267 for which it applied to Japan, and uses the content for it here.

Conventionally, steel pipes are widely used for piles, columns, etc. in civil engineering or building structures.
When these steel pipes are used for civil engineering or building structures, for the convenience of production and transportation, steel pipes of a regular size are often carried to the site and connected to the site to form a predetermined length. Welding is often used for this joining, but mechanical joints that do not use local welding are often used to save labor and shorten construction time.

  Steel pipes connected using mechanical joints are subjected to a force during construction or service, and when a tensile load or a bending load is applied to the connection parts, the connection parts may be deformed out of plane with each other and come out.

  Regarding the connection of such steel pipes, for example, in Patent Document 1, a protrusion provided on a joint material joined to one steel pipe is inserted into a concave part of the joint material joined to the other steel pipe, and the above-described protrusion is formed into a concave part. The technique which keeps a joint material mutually does not slip out by hold | maintaining with an outer peripheral wall part is disclosed.

  As shown in FIG. 8, the connecting structure of the steel pipes using the joint material is, for example, a factory in which a female box joint material 102 is welded and attached to the lower end of the upper steel pipe 101 at the welding portion 103. A male pin joint material 105 is welded and attached to the upper end of the welding portion 106.

  Then, as shown in FIG. 9, the protrusion 112 of the pin joint 105 is inserted into the recess 122 of the box joint material 2, and a plurality of arc-shaped load transmission keys 107 are attached in the circumferential direction of the box joint material 102. By fitting the load transmission key 107 into the key groove 111 on the outer periphery of the pin joint material 105, the upper and lower steel pipes 101 and 102 are connected.

  On the other hand, Patent Document 2 discloses a technique for reducing the radial clearances of the protrusions and the recesses to such an extent that they can be fitted to each other and improving the resistance to bending force in addition to preventing the joint members from coming out. .

Japanese Unexamined Patent Publication No. 2004-346660 Japanese Unexamined Patent Publication No. 2006-291543

  However, when a tensile load acts between the connected steel pipes, a bending force M in a direction away from each other as shown in FIG. 9 is generated in the upper and lower joint members 102 and 105. As a result, as shown in FIG. Such out-of-plane deformation occurs in the protrusion 112.

When such out-of-plane deformation occurs in the protrusion 112, stress concentrates on the connecting portion 122a between the side surface and the bottom surface opposite to the out-of-plane deformation of the recess 122, and a crack starting from the periphery of the recess 122 may occur. There is. When the yield strength of the steel pipe connection structure is improved, the possibility of cracks starting from the periphery of the recess 122 increases.
Accordingly, there is a strong demand for a technique for preventing cracks around the concave portion 122 caused by bending force generated by out-of-plane deformation of the protrusion in accordance with improvement in yield strength against tensile load and the like.
The same applies to the recess 113 of the pin joint material 105 into which the protrusion 123 at the lower end of the box joint material 2 is fitted.

  The inventors of the present invention, as a result of earnest research on the stress concentration in the connecting structure of the steel pipes, as a result of suppressing the stress applied to the connecting portion of the side surface and the bottom surface of the recess to 1 / 1.5 or less in the case of no measures. In addition, the inventors have found that stress concentration due to out-of-plane deformation of the protrusions is alleviated and cracking around the recess is suppressed.

  The object of the present invention is to relieve the stress concentration on the recesses and thus generate cracks around the recesses with respect to the steel pipe connection structure in which the protrusions provided on one steel pipe side are inserted into the recesses formed on the other steel pipe side. An object of the present invention is to provide a steel pipe connection structure that can be suppressed.

In order to solve the above problems, the present invention proposes the following means.
A first aspect of the present invention is a steel pipe connection structure in which one steel pipe and the other steel pipe are connected in the longitudinal direction of these steel pipes by meshing shear protrusions or load transmission keys between the steel pipes. A protrusion extending to the other steel pipe side is provided on the one steel pipe side, and a recess is formed on the other steel pipe side, and a side surface and a bottom surface of the recess are connected to each other. When the tensile load is applied between the one steel pipe and the other steel pipe of the connecting portion, the portion where the bending force is generated by the out-of-plane deformation of the projection intersects the curved surface and the adjacent surface at an obtuse angle. The stress relaxation shape part which consists of any one of these, or these combination is provided.
According to the connection structure of the steel pipe, since the stress relaxation shape portion is provided in a portion where the bending force is generated due to the out-of-plane deformation of the protrusion in the connecting portion, the stress of the connecting portion is applied even if the bending force is applied. Concentration is relaxed, and as a result, generation of cracks starting from the periphery of the recess can be suppressed.

According to a second aspect of the present invention, there is provided the steel pipe connection structure according to the first aspect, wherein the length of each of the steel pipes in the radial direction of the stress relaxation shape portion is the one steel pipe and the other steel pipe. It is 1/11 or more of the total thickness of the connection part which connected the steel pipe.
According to the connection structure of the steel pipe, the stress applied to the connecting portion between the side surface and the bottom surface of the recess can be suppressed to 1 / 1.5 or less, and the crack generation starting from the periphery of the recess due to the stress concentration can be suppressed. . The radial length of the stress relaxation shape portion is selected within the range of the width of the concave portion (the length in the radial direction).

According to a third aspect of the present invention, there is provided the steel pipe connection structure according to the first aspect, wherein the protrusion and the bottom surface of the recess are formed by the longitudinal action of the protrusion generated by the load action of the connected steel pipe. A contact prevention shape portion for preventing contact due to a change in direction is further provided.
According to the connection structure of the steel pipe, since the contact prevention shape portion is provided and the contact between the top surface of the protrusion and the bottom surface of the recess is prevented, impact load such as impact is directly transmitted from the protrusion to the bottom surface of the recess. There is nothing to do.
As a result, stress concentration due to load action such as impact load does not occur, and as a result, the generation of cracks starting from the periphery of the recess can be suppressed.

According to a fourth aspect of the present invention, there is provided the steel pipe connection structure according to the first aspect, wherein the side surface of the protrusion and the concave portion is more than the connecting portion on the side where the bending stress is generated due to the out-of-plane deformation. A gap is formed between the projection and the side surface of the recess when the projection contacts the side of the opening and the side where the out-of-plane deformation occurs is generated.
According to the above steel pipe connection structure, when an out-of-plane deformation of the protrusion occurs, a gap is formed between the protrusion and the side surface of the recess on the side where the out-of-plane deformation occurs. Is suppressed. As a result, stress concentration due to out-of-plane deformation of the protrusion is suppressed, and as a result, generation of cracks starting from the periphery of the recess can be suppressed.

  According to the present invention, it is possible to alleviate the stress concentration acting on the steel pipe connection structure and to suppress the occurrence of cracks around the recess.

It is a perspective view which shows an example of the connection structure of the steel pipe which concerns on this invention, and is a figure which shows the state before connection. It is a perspective view of the connection structure of the steel pipe, and is a figure showing the connected state. It is a fragmentary sectional view which shows the connection procedure of the connection structure of the steel pipe, and is a figure which shows the state before connecting. It is a fragmentary sectional view which shows the connection procedure of the connection structure of the steel pipe, and is a figure which shows the state combined. It is a fragmentary sectional view which shows the connection procedure of the connection structure of the steel pipe, and is a figure which shows the connected state. It is a fragmentary sectional view of the connection structure of the steel pipe which concerns on the 1st Embodiment of this invention, and is a figure which shows the detail of the A1 part of FIG. 2C. It is a fragmentary sectional view of the connection structure of the steel pipe which concerns on the 2nd Embodiment of this invention, and is a figure which shows the detail of the A1 part of FIG. 2C. It is a fragmentary sectional view of the connection structure of the steel pipe which concerns on the 3rd Embodiment of this invention, and is a figure which shows the detail of the A1 part of FIG. 2C. It is a fragmentary sectional view of the connection structure of the steel pipe which concerns on the 4th Embodiment of this invention, and is a figure which shows the detail of the A1 part of FIG. 2C. It is a fragmentary sectional view of the connection structure of the steel pipe which concerns on the 5th Embodiment of this invention, and is a figure which shows the detail of the A1 part of FIG. 2C. It is a fragmentary sectional view of the connection structure of the steel pipe which concerns on the 6th Embodiment of this invention, and is a figure which shows the detail of A1 part of FIG. 2C. It is a figure which shows the dimension of the connection structure of the steel pipe which analyzed the distortion. It is a graph which shows ratio of the R dimension of the recessed part of the connection structure of the steel pipe which concerns on 1st Embodiment, and main distortion. It is a longitudinal cross-sectional view which shows another embodiment of the connection structure of the steel pipe which concerns on this invention. It is a perspective view which shows an example of the connection structure of the conventional steel pipe. It is a longitudinal cross-sectional view which shows the connection structure of the steel pipe shown in FIG. It is an enlarged view explaining the stress concentration part in A2 part of FIG.

Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1A to 3A.
As shown in FIGS. 1A and 1B, the steel pipe connection structure according to the first embodiment has a male box joint material 2 attached to the upper steel pipe 1 and a male shape attached to the lower steel pipe 4. A pin joint material 5 is inserted.

  Further, the box joint material 2 is attached with an arc-shaped load transmission key 7 that is appropriately divided over the entire circumference, and by fitting the load transmission key 7 into the key groove 11 on the outer periphery of the pin joint material 5, The steel pipes 1 and 2 are mechanically connected so that a tensile load can be transmitted between them.

  The box joint material 2 is attached to the lower end of the upper steel pipe 1 by welding at the weld portion 3, and the pin joint material 5 is attached to the upper end of the lower steel pipe 4 by welding at the weld portion 106. These welded portion 3 and welded portion 6 are welded at a factory, for example.

2A, 2B, and 2C are diagrams showing a procedure for connecting the box joint material 2 and the pin joint material 5. FIG.
First, as shown in FIG. 2A, a screw 8 and a load transmission key 7 are attached to the box joint material 2. For example, a hexagon socket head screw is used as the screw 8, and the screw 8 is fixed to the screw hole 21 of the box joint material 2.

Next, as shown in FIG. 2B, a protrusion 12 formed at the upper end of the pin joint material 5 and protruding upward, a recess 22 of the box joint material 2, and a protrusion 23 formed at the lower end of the box joint material 2 and protruding downward. The concave portions 13 of the pin joint material 5 are fitted together.
When the protrusion 23 and the recess 13 are fitted together, the box joint material 2 and the pin joint material 5 are positioned in the vertical direction, and the tip of the load transmission key 7 is disposed at the entrance of the key groove 11 of the pin joint material 5.

Next, when the screw 8 is turned in a predetermined direction from the outside of the screw hole 21 using a hexagon wrench or the like, the load transmission key 7 moves forward along the axis of the screw 8 as shown in FIG. Enter.
As shown in FIGS. 2A to 2C, the load transmission key 7 is disposed across both the box joint material 2 and the pin joint material 5 by making the thickness of the load transmission key 7 larger than the depth of the key groove 11. Is done.

  Thus, the box joint material 2 and the pin joint material 5 are connected. After the screw 8 is screwed in, the embedding depth of the screw 8 is measured from the outside of the box joint material 2 with a depth gauge or the like, and it is confirmed that the load transmission key 7 is securely fitted in the key groove 11. To do.

Further, at the joint when the box joint material 2 and the pin joint material 5 are connected to each other, the upper and lower steel pipes 1 and 4 are prevented from relatively rotating around the axis at one place or at a plurality of places at appropriate circumferential intervals. A rotation suppression key 10 is attached.
For example, as shown in FIG. 2A, the rotation inhibition key 10 is fixed in advance to the lower end portion of the pin joint material 5 by screwing or the like, and a nut is attached to the tip of the rotation inhibition key screw 9. It is attached by screwing the member provided with.

  In this embodiment, the protrusion 12 is formed so that the tip is thinned by chamfering, for example, so that it can be smoothly inserted into the recess 22 when the joint material 2 and the joint material 5 are connected.

Next, with reference to FIG. 3A, the detail of the connection structure 30 of the steel pipe which concerns on 1st Embodiment is demonstrated.
FIG. 3A is a partial cross-sectional view including the center line of the steel pipe 1 of the steel pipe connection structure 30 and shows details of the A1 part of FIG. 2C.
As shown in FIG. 3A, the steel pipe connection structure 30 is in contact with, for example, a side surface 22 </ b> S and a bottom surface 22 </ b> B at a connecting portion 22 a located on the inner peripheral side of the steel pipe 1 of the recess 22 (hereinafter referred to as an inner peripheral side connecting portion). The stress relaxation shape part 31 which consists of the surplus formed in the curved surface of the curvature radius R is provided.
Further, the radius of curvature R is set to a dimension of 1/11 or more of the total thickness T (see FIG. 2C) of the connecting portions when both the joint materials 2 and 5 are connected. The radius of curvature R of the stress relaxation shape portion is selected within the range of the width of the recess (the length in the radial direction).
That is,
The total thickness T of the connected parts is preferably set to 1/11 ≦ R ≦ width of recess.

  When the tensile force is applied to the connection structure 30 of the steel pipes 1 and 4 connected via the joint members 2 and 5, for example, the projection 12 is deformed out of the plane on the outer peripheral side. A bending force is generated in the peripheral side connecting portion 22a.

  In this embodiment, the protrusion 23 of the joint material 2 and the recess 13 of the joint material 5 may have the same configuration as the protrusion 12 and the recess 22. Moreover, you may provide a stress relaxation shape part in the connection part (henceforth an outer peripheral side connection part) of the outer peripheral side in the steel pipe 1 of the recessed part 22. FIG.

  According to the connection structure 30 of the steel pipe, even if the protrusion 12 is deformed out of the plane by the tensile load between the steel pipe 1 and the steel pipe 4, the stress concentration on the inner peripheral side connecting portion 22a of the concave portion 22 is concentrated. Can be relaxed.

  Further, when the curvature radius R of the stress relaxation shape portion 31 is set to 1/11 or more of the total thickness T of the connecting portions when both the joint materials 2 and 5 are connected, the inner peripheral side connecting portion 22a The stress is reduced to 1 / 1.5 or less, and cracks starting from the periphery of the recess 22 (particularly in the vicinity of the inner peripheral connecting portion 22a) due to the stress concentration can be prevented.

  Next, with reference to FIG. 3B, the connection structure 40 of the steel pipe which concerns on the 2nd Embodiment of this invention is demonstrated.

  The steel pipe connection structure 40 according to the present embodiment is different from the steel pipe connection structure 30 in that a cross section including the center of the steel pipe 1 is used instead of the stress relaxation shape portion 31 formed of a curved surface, as shown in FIG. 3B. The stress relaxation shape portion 41 is formed of a surplus wall having an inclined surface with a length C on each side that intersects the side surface 22S and the bottom surface 22B at an inner angle of 135 °. Since others are the same as those in the first embodiment, the same reference numerals are given and description thereof is omitted.

According to the steel pipe connection structure 40, even if the protrusion 12 is deformed out of plane on the outer peripheral side of the steel pipe 1, the concentration of stress on the inner peripheral connecting portion 22a can be reduced.
Further, by setting the dimension C of one side of the stress relaxation shape portion 41 to 1/11 or more of the total thickness T of the connecting portions when both the joint materials 2 and 5 are connected, the periphery of the recess 22 is set as the starting point. Crack generation can be suppressed. The radial length of the stress relaxation shape portion is selected within the range of the width of the concave portion (the length in the radial direction).
That is,
It is preferable to set 1/11 ≦ C ≦ width of the concave portion of the total thickness T of the connected portions.

  Next, with reference to FIG. 3C, the connection structure 50 of the steel pipe which concerns on the 3rd Embodiment of this invention is demonstrated.

The steel pipe connection structure 50 according to this embodiment is different from the steel pipe connection structure 30 in that a stress relaxation shape portion 51 is provided instead of the stress relaxation shape portion 31 formed of a curved surface. As shown in FIG. 3C, the stress relaxation shape portion 51 has a cross section including the center of the steel pipe 1 intersecting the side surface 22S at an obtuse angle, and the bottom surface 22B side of the recess 22 is from the side of the length C1 and the side surface 22S side is the side of the length C2. And a surplus surface that combines a curved surface having a radius of curvature R1 in contact with the bottom surface 22B.
Since others are the same as those in the first embodiment, the same reference numerals are given and description thereof is omitted.

  According to the steel pipe connection structure 50, the stress relaxation shape portion 51 can be efficiently processed by setting C1 and C2 constituting the inclined surface to dimensions suitable for processing. Moreover, the crack direction around the recessed part 22 is suppressed by making the radial direction dimension of the stress relaxation shape part 51 into 1/11 or more of the total thickness T of the connection part when the joint materials 2 and 5 are connected. Can do.

  In the first to third embodiments, whether or not the radial dimension of the stress relaxation shape portions 31, 41, 51 is 1/11 or more of the total thickness T of the connected portions is arbitrarily set. be able to.

  Next, with reference to FIG. 4A, the connection structure 60 of the steel pipe which concerns on the 4th Embodiment of this invention is demonstrated.

  The steel pipe connection structure 60 according to the present embodiment is different from the steel pipe connection structure 30 in that, as shown in FIG. 4A, in addition to the stress relaxation shape portion 61 formed of a curved surface having a radius of curvature R2, The contact prevention shape part (for example, clearance gap) 62 for ensuring the space | interval of the dimension L1 is provided between the top | upper surface 12A of the processus | protrusion 12, and the bottom face 22B of the recessed part 22 which considered the amplitude of the direction. Since others are the same as those in the first embodiment, the same reference numerals are given and description thereof is omitted.

  Next, with reference to FIG. 4B, the connection structure 70 of the steel pipe which concerns on the 5th Embodiment of this invention is demonstrated.

The steel pipe connection structure 70 according to this embodiment is different from the steel pipe connection structure 30 in that a stress relaxation shape portion 71 and a contact prevention shape portion 72 are provided instead of the stress relaxation shape portion 31 formed of a curved surface. It is a point.
As shown in FIG. 4B, the stress relaxation shape portion 71 has a cross section including the center of the steel pipe 1 intersecting the side surface 22S at an obtuse angle, and the bottom surface 22B side of the recess 22 is from the side of the length C3 and the side surface 22S side is from the side of the length C4. And the surplus surface that combines the inclined surface, the bottom surface 22B, and the curved surface with the curvature radius R3 in contact with the outer peripheral side surface 22T.
Moreover, the contact prevention shape part 62 is comprised by the clearance gap which can ensure the space | interval of the dimension L2 between the top | upper surface 12A of the processus | protrusion 12 and the bottom face 22B of the recessed part 22 which considered the amplitude of the up-down direction at the time of construction, for example. Yes.
Since others are the same as those in the first embodiment, the same reference numerals are given and description thereof is omitted.

According to the steel pipe connection structures 60 and 70, the stress relaxation shape portions 61 and 71 alleviate the concentration of stress in the inner peripheral connection portion 22a. Furthermore, since the contact preventing shape portions 62 and 72 are provided, the contact between the top surface 12A of the protrusion 12 and the bottom surface 22B of the concave portion 22 is prevented.
As a result, since the impact load due to the impact applied when constructing the connected steel pipes 1 and 4 is not directly transmitted from the protrusion 12 to the bottom surface 22B of the recess 22, the stress of the inner peripheral connecting portion 22a is reduced. Concentration is suppressed, and as a result, generation of cracks starting from the periphery of the recess 22 can be suppressed.

  Next, with reference to FIG. 4C, the connection structure 80 of the steel pipe which concerns on 6th Embodiment of this invention is demonstrated.

  The steel pipe connection structure 80 according to the present embodiment is different from the steel pipe connection structure 30 in that a bending force relaxation shape portion is provided in addition to the stress relaxation shape portion 81 as shown in FIG. 4C. It is.

The stress relaxation shape part 81 is provided in the inner peripheral side connection part 22a, and the cross section including the center line of the steel pipe 1 is configured by an extra wall having a curved surface.
Further, the bending force relaxation shape portion prevents a direct load from the protrusion 12 to the inner peripheral side connection portion 22a, and the inner peripheral side connection portion 22a generated by an out-of-plane deformation of the protrusion 12 acting on the outer side surface 22T. The bending stress is reduced.

Specifically, the side surface 22S on the inner peripheral side is formed as a tapered portion 82 whose opening side is inclined toward the inner peripheral side, and as a result, the inner periphery of the protrusion 12 and the concave portion 22 in which bending stress is generated due to the out-of-plane deformation of the protrusion 12. The side surface 22S on the side contacts with the opening side of the recess 22 from the inner peripheral side connecting portion 22a.
Further, for example, on the side surface on the outer peripheral side of the protrusion 12, when the protrusion 12 is deformed out of plane (shown by a two-dot chain line in FIG. 4C), the protrusion 12 does not contact with the side surface 22T. A shape portion 83 is formed in consideration of the above displacement.

  Since others are the same as those in the first embodiment, the same reference numerals are given and description thereof is omitted.

According to the steel pipe connection structure 80, on the inner peripheral side where bending stress is generated due to out-of-plane deformation, the tapered portion 82 causes the inner peripheral side surface 22S of the protrusion 12 and the concave portion 22 to be recessed from the inner peripheral connecting portion 22a. Therefore, the load is not transmitted from the protrusion 12 to the bottom surface 22B of the recess 22.
In addition, since the shape portion 83 corresponding to the out-of-plane deformation is formed on the protrusion 12, a gap is secured between the protrusion 12 and the side surface 22 </ b> T on the outer peripheral side of the recess 22 even if the protrusion 12 is deformed out of the surface. The generation of bending force on the inner peripheral side connecting portion 22a due to the out-of-plane deformation of the protrusion 12 is reduced. As a result, the concentration of stress on the concave portion 22 due to the out-of-plane deformation of the protrusion 12 is reduced, and as a result, the generation of cracks around the concave portion 22 is suppressed.

Next, with reference to FIG. 5 and FIG. 6, effects of the present invention using the steel pipe connection structure 30 according to the first embodiment as an example will be described.
Inner circumferential side where bending force is generated in the recess 22 when the box joint material 2 and the pin joint material 5 having the dimensions shown in FIG. 5 are connected and a tensile load of 4040 kN corresponding to the yield load of the steel pipe is applied in the direction of the arrow. The main strain generated in the connecting portion 22a was analyzed. The material of the joint materials 2 and 5 was SFCM880 (900 MPa class steel). The outer diameter φ of the steel pipe was 1600 mm and the thickness t = 23 mm. FIG. 6 shows the ratio of strain for each R dimension, assuming that the R surface or C surface is not formed on the inner peripheral side connecting portion 22a of the recess 22 (R = 0 mm).

As shown in FIG. 6, the strain was reduced as the R dimension was increased, and the stress concentration was alleviated by making the connecting portion an R surface. When R = 6 mm, the ratio of the main strain to when the R surface was not formed was approximately 1 / 1.5. Since the total thickness of the joint portion of the joint material is 68.1 mm as shown in FIG. 5, the ratio of the R dimension to the total thickness of the joint material when the strain value, that is, the stress becomes 1 / 1.5. Is 6 / 68.1 (= 1 / 11.35).
As described above, when the R surface is set to 1/11 or more of the total thickness of the joint portions of the joint material, stress concentration is alleviated.

  Therefore, when a protrusion is provided at the joint portion of the joint material and the yield strength is increased by a factor of 1.5, the inner peripheral side connection portion 22a of the concave portion 22 is 1/11 or more of the total thickness of the joint material. By providing a curved surface with a radius of curvature R, the stress acting on the inner peripheral side connecting portion 22a of the concave portion 22 becomes 1 / 1.5 or less, and breakage can be prevented without changing the material and thickness of the joint material. . It is considered that the same effect is ensured even when the stress relaxation shape portion in the inner peripheral side connecting portion 22a is other than a curved surface.

  The preferred first to sixth embodiments of the present invention have been described above, but the present invention is not limited to such examples. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the technical idea described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

  For example, the box joint material and the pin joint material may be upside down as shown in FIGS. 1A and 1B, and can be applied to configurations other than the box joint material and the pin joint material shown in FIGS. 1A and 1B. Not too long.

  Moreover, in the said embodiment, although the case where a connection structure was applied to the box joint material 2 and the pin joint material 5 was demonstrated, a connection part is directly connected to any one or both of the upper side steel pipe 1 and the lower side steel pipe 4. It can also be set as the structure formed.

  Moreover, in the said embodiment, although the case where the steel pipes 1 and 4 were cylindrical steel pipe piles was demonstrated, it cannot be overemphasized that it is applicable to building members other than a steel pipe pile, and a square cylinder is included. It may be applied to a polygonal steel pipe. The same applies to the joint material.

  Further, as shown in FIG. 7, for example, by using a spline formed in the longitudinal direction, one joint 91 and the other joint material 93 are inserted in the longitudinal direction, and then rotated with respect to each other. Instead of the key, the projection 92 provided in one joint 91 and the recess 94 provided in the other joint material 93 may be engaged and connected.

  In addition, in the steel pipe connection structures 30, 40, 50, 60, 70, 80 according to the above-described embodiment, a description will be given of a case where a tensile load acting at the time of construction causes a bending force to be generated in the inner peripheral connecting portion 22a. However, within the scope of the gist of the present invention, it may be applied to the bending force generated at the outer peripheral side connection portion due to the load during construction.

  In the above embodiment, the case where the stress relaxation shape portions 31, 41, 51, 61, 71, 81 are provided in the inner peripheral side connecting portion 22 a of the concave portion 22 has been described. You may provide a stress relaxation shape part. The same applies to the protrusion 23 and the recess 13.

Further, the stress relaxation shape portion related to the recess 13 may be configured differently from the stress relaxation shape portions 31, 41, 51, 61, 71, 81 related to the recess 22.
In addition, it is arbitrary whether the stress relaxation shape portions 31, 41, 51, 61, 71, 81 are either a curved surface or an inclined surface in a cross section including the center of the steel pipe 1 or a combination thereof. Can be set to

  Further, when the stress relaxation shape portion is a curved surface in sectional view, it can be arbitrarily set whether to connect the curved surface, the bottom surface, and the side surface so as to contact each other or to intersect at an obtuse angle. The same applies to the connection with the adjacent inclined surface or curved surface when a part of the stress relaxation portion is a curved surface.

  In the fifth and sixth embodiments, the case where the contact preventing shape portions 62 and 72 are constituted by a gap formed between the top surface 22A of the protrusion 12 and the bottom surface 22B of the recess 22 will be described. However, other shapes may be used.

  Further, in the sixth embodiment, the case where the bending force relaxation shape portion is configured by the tapered portion 82 of the side surface 22S and the shape portion 83 corresponding to the out-of-plane deformation formed on the protrusion 12 has been described. When the protrusion 12 and the inner peripheral side surface 22S are in contact with each other on the opening side from the inner peripheral connection portion 22a and the protrusion 12 is deformed out of the plane, the protrusion 12 and the outer peripheral side surface 22T of the recess 22 Another configuration in which a gap is secured between them may be employed.

  According to the present invention, stress concentration in the connection structure is alleviated and breakage is suppressed, so that it can be utilized industrially.

DESCRIPTION OF SYMBOLS 1 Upper steel pipe 2 Box joint material 3, 6 Welded part 4 Lower steel pipe 5 Pin joint material 7 Load transmission key 8 Screw 9 Rotation suppression key screw 10 Shear key 11 Key groove 12, 23 Protrusion 13, 22 Recess 21 Screw hole 22a Joint part (part where bending force is generated)
30, 40, 50, 60, 70, 80 Steel pipe connection structure 31, 41, 51, 61, 71, 81 Stress relaxation shape portion 62, 72 Contact prevention shape portion 82 Taper portion (contact prevention shape portion)
83 Shape part (Contact prevention shape part)

Claims (4)

A steel pipe connection structure in which one steel pipe and the other steel pipe are connected in the longitudinal direction of these steel pipes by meshing shear protrusions or load transmission keys between the steel pipes,
A protrusion extending toward the other steel pipe is provided on the one steel pipe side, and a recess into which the protrusion is inserted is formed on the other steel pipe side;
In the portion where the side surface and the bottom surface of the recess are connected, a portion where bending force is generated due to out-of-plane deformation of the protrusion when a tensile load is applied between the one steel pipe and the other steel pipe, A stress relieving shape portion formed of any one of a curved surface, a surface intersecting with an adjacent surface at an obtuse angle, or a combination thereof;
A steel pipe connection structure characterized by that.   The length in the radial direction of each of the steel pipes of the stress relaxation shape portion is 1/11 or more of the total thickness of the connected parts connecting the one steel pipe and the other steel pipe, The steel pipe connection structure according to claim 1.   A contact-preventing shape portion is further provided to prevent the projection and the bottom surface of the recess from contacting each other due to the variation in the longitudinal direction of the projection caused by the load action of the connected steel pipe. The steel pipe connection structure according to claim 1.   The projection and the side surface of the recess are in contact with each other at a position closer to the opening side than the connecting portion on the side where the bending stress due to the out-of-plane deformation occurs, and the side where the out-of-plane deformation occurs is the out-of-plane deformation of the projection. The steel pipe connection structure according to claim 1, wherein a gap is formed between the protrusion and the side surface of the recess when the protrusion occurs.

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