JP2022170225A - Steel pipe connection structure and connection method - Google Patents

Abstract

To transfer force stably and effectively in connecting steel pipes in which bending moment is generated.SOLUTION: A connection structure of steel pipes comprises a first steel pipe, a second steel pipe and a pair of cast iron hardware divided with a plane including an axis of the first steel pipe and an axis of the second steel pipe, and each of the pair of cast iron hardware comprises a first half-split pipe having an inner peripheral surface in contact with the outer peripheral surface of the first steel pipe at least partially, a second half-split pipe having the inner peripheral surface in contact with the outer peripheral surface of the second steel pipe at least partially, and a flange part formed in continuation with a lateral end of the first half-split pipe and the lateral end of the second half-split pipe respectively and capable of fastening the pair of cast iron hardware to each other. The distance between the bottoms of the inner peripheral surfaces of the first half-split pipe when the flange parts of the pair of cast iron hardware are brought into close contact each other is smaller than an outer diameter of the first steel pipe.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present invention relates to a steel pipe connection structure and a steel pipe connection method.

As a connection structure of steel pipes used in structures, it has been common to use flange joints formed at the ends of steel pipes, as in the example of the overhead wire pole described in Patent Document 1, for example. In this case, the flanges are formed along a plane orthogonal to the axis of the steel pipe, and the steel pipes are connected by bringing the flanges into close contact with each other and joining them with bolts.

Japanese Patent Application Laid-Open No. 2014-20096

In the case of the overhead wire column described in Patent Literature 1, the flange joint mainly transmits compressive force in the axial direction of the steel pipe. On the other hand, when steel pipes are subjected to a bending moment, such as when steel pipes are used for beams supported by overhead lines, flange joints transmit compressive and tensile forces in the axial direction of the steel pipes. Since the tensile force is transmitted between the flanges through the bolts, in such a case it was necessary to increase the number of bolts to join the flanges.

Further, as shown in FIGS. 13A and 13B, in a steel pipe beam column joint 90 of a conventional overhead wire column, ring structures 93 and 94 that transmit the load of a beam 91 to a column 92 are arranged parallel to flange joints 95 and 96. It is common to be divided in various aspects. Therefore, it is necessary to design so that all bending moments transmitted from the beam 91 to the ring structures 93 and 94 via the bolts of the flange joints 95 and 96 are borne by the bolts joining the split ring structures 93 and 94. It can be said that it is a structure with a lot of waste.

Accordingly, an object of the present invention is to provide a steel pipe connection structure and a steel pipe connection method capable of stably and efficiently transmitting force when connecting steel pipes in which a bending moment is generated.

[1] A first steel pipe, a second steel pipe, and a pair of cast iron hardware divided by a plane containing the axis of the first steel pipe and the axis of the second steel pipe, wherein the pair of cast iron hardware are a first half pipe whose inner peripheral surface is at least partially in contact with the outer peripheral surface of the first steel pipe, and an inner peripheral surface at least partially in contact with the outer peripheral surface of the second steel pipe. A second half-tube is continuously formed at the side ends of the first half-tube and the side end of the second half-tube, respectively, for clamping the pair of cast iron hardware together. The distance between the bottoms of the inner peripheral surface of the first half pipe when the flanges of the pair of cast iron hardware are brought into close contact with each other is the distance between the bottoms of the first steel pipe A connected structure of steel pipes smaller than the outer diameter.
[2] The steel pipe connection structure according to [1], wherein the axis of the first steel pipe is perpendicular to the axis of the second steel pipe.
[3] The first steel pipe and the second steel pipe have a common axis, the first half pipe and the second half pipe are formed continuously, and the pair of cast iron The steel pipe connection according to [1], wherein the distance between the bottoms of the inner peripheral surfaces of the second half pipe when the flanges of the hardware are brought into close contact with each other is smaller than the outer diameter of the second steel pipe. structure.
[4] The length along the axis of the first steel pipe of the section where the first half pipe and the first steel pipe are in contact is 1.0 times or more the outer diameter of the first steel pipe. The connecting structure of steel pipes according to any one of [1] to [3], wherein:
[5] Further comprising a shear key fitted to each of the recess formed in the inner peripheral surface of the first half pipe and the opening formed in the peripheral surface of the first steel pipe [1] The connecting structure of steel pipes according to any one of [4].
[6] The shear key has a tapered shape in which the cross-sectional dimension decreases from the recess toward the opening, and the inner peripheral surface of the first half pipe is connected to the first steel pipe through the shear key. The connecting structure of the steel pipes according to [5], which is in contact with.
[7] A first half-tube, a second half-tube, and a flange continuously formed on the side end of the first half-tube and the side end of the second half-tube. A steel pipe connection method for connecting a first steel pipe and a second steel pipe using a pair of cast iron hardware each including a part, wherein one of the pair of cast iron hardware is divided into the first half contacting the inner peripheral surface of the pipe at least partially with the outer peripheral surface of the first steel pipe, and bringing the inner peripheral surface of the second half pipe into at least partial contact with the outer peripheral surface of the second steel pipe; and by tightening the pair of cast iron metal fittings against each other with the flange portion, the inner peripheral surface of the first half pipe of the other of the pair of cast iron metal fittings is at least partially replaced by the first steel pipe. and bringing the inner peripheral surface of the second half pipe into at least partial contact with the outer peripheral surface of the second steel pipe.

According to the above configuration, the distance between the bottoms of the inner peripheral surfaces of the first half pipe when the flange portions of the pair of cast iron hardware are brought into close contact with each other is set smaller than the outer diameter of the first steel pipe. By tightening the pair of cast iron hardware against each other, at least a part of the inner peripheral surface of the first half pipe comes into contact with the outer peripheral surface of the first steel pipe without any gap, and the first steel pipe The force due to the generated bending moment can be stably and efficiently transmitted by the bearing pressure between the first half pipe. The flanges of a pair of cast iron hardware are joined together by fastening means such as bolts. should be less. Moreover, unlike the conventional flange joint structure, there is no need for double joints for the same load, so the efficiency as a whole is further improved.

A structure with a complicated shape like the one in the present invention is expensive to manufacture by processing or welding steel plates or steel pipes, and it is difficult to ensure accuracy. However, it is possible to make a member with high precision at a relatively low cost.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the overhead wire support structure containing the connection structure of the steel pipe which concerns on the 1st Embodiment of this invention. FIG. 2 is a perspective view of a connecting structure of steel pipes in the example shown in FIG. 1; 3 is a cross-sectional view taken along line III-III of FIG. 2; FIG. FIG. 4 is a diagram showing a step of connecting steel pipes in the first embodiment of the present invention; FIG. 4 is a diagram showing a step of connecting steel pipes in the first embodiment of the present invention; FIG. 4 is a diagram for explaining an example using Shear key in the first embodiment of the present invention; 7 is a diagram showing an example in which the shear key has a tapered cross section in the example shown in FIG. 6. FIG. FIG. 7 is a view showing an overhead wire support structure including a steel pipe connection structure according to a second embodiment of the present invention; FIG. 9 is a perspective view of a connecting structure of steel pipes in the example shown in FIG. 8; It is a figure which shows the state which removed the beam in FIG. 9, and opened the cast-iron hardware. FIG. 10 is a diagram showing a process of connecting steel pipes in the second embodiment of the present invention; FIG. 10 is a diagram showing a process of connecting steel pipes in the second embodiment of the present invention; FIG. 13B is a view showing a steel pipe beam-column joint of a conventional overhead wire column, and is a view taken along line AA in FIG. 13B. FIG. 13B is a view showing a steel pipe beam-column joint of a conventional overhead wire column, taken along the line BB in FIG. 13A.

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the present specification and drawings, constituent elements having substantially the same functional configuration are denoted by the same reference numerals, thereby omitting redundant description.

(First embodiment)
FIG. 1 is a diagram showing an overhead wire support structure including a steel pipe connection structure according to a first embodiment of the present invention. The overhead wire support structure according to the present embodiment includes beams 1 and overhead wire poles 2, both of which are made of steel pipes. The beam 1 and overhead wire pole 2 are connected using a connection structure 10 including cast iron hardware 3A and 3B, which will be described later. A suspension structure 4 for suspending overhead wires is attached to the beam 1 . A bending moment is generated in the beam 1 by its own weight and the load of the suspension structure 4 and other facilities (not shown).

FIG. 2 is a perspective view of the steel pipe connection structure in the example shown in FIG. In the illustrated example, the connection structure 10 includes a beam 1 (first steel pipe), an overhead wire pole 2 (second steel pipe), and a pair of cast iron hardware 3A, 3B. The axis X of the beam 1 is perpendicular to the axis Y of the overhead wire column 2, and the cast iron hardware 3A, 3B is divided by a plane containing both of these axes X, Y. Each of the cast iron hardware 3A, 3B includes first half pipes 31A, 31B, second half pipes 32A, 32B, flange portions 331A, 331B, 332A, 332B, 333A, 333B, and these flange portions bolts 341A, 342A and nuts 341B, 342B, which are fastening means for tightening together.

FIG. 3 is a cross-sectional view taken along line III--III in FIG. As illustrated, the first half pipes 31A, 31B formed in the cast iron hardware 3A, 3B respectively have inner peripheral surfaces at least partially in contact with the outer peripheral surface of the beam 1 (first steel pipe). are arranged to The length along the axis X of the section where the first half tubes 31A and 31B and the beam 1 are in contact is preferably 1.0 times the outer diameter of the beam 1 or more. Here, the first half-split tubes 31A and 31B, as shown by the phantom lines in FIG. , the distance d between the bottoms of the inner peripheral surface is smaller than the outer diameter D of the beam 1 . Here, the distance d between the bottoms is the direction perpendicular to the bottoms of the first half tubes 31A and 31B, that is, the direction in which the half tubes extend (if the cross section of the half tube is circular, is the distance between the centrally located parts when viewed in the circumferential direction).

The first half tubes 31A and 31B are formed with an arcuate cross-section such that the cross-sectional radius of the inner peripheral surface is equal to or larger than the outer diameter of the beam 1 so that they can contact the outer peripheral surface of the beam 1 . By setting the distance d between the bottom portions as described above, the inner peripheral surfaces of the first half-split tubes 31A and 31B can be brought into close contact with the outer peripheral surface of the beam 1. FIG. Specifically, when the flanges 331A, 331B, 332A, 332B are tightened together using fastening means such as bolts 341A, 342A and nuts 341B, 342B, the flanges 331A, 331B, 332A, 332B The inner peripheral surfaces of the first half tubes 31A and 31B can be brought into close contact with the outer peripheral surface of the beam 1 while leaving a gap therebetween. As a result, force can be stably transmitted between the beam 1 and the cast iron hardware 3A, 3B by bearing pressure.

Referring to FIG. 2 again, the second half pipes 32A, 32B formed on the cast iron hardware 3A, 3B have inner peripheral surfaces at least partially aligned with the outer peripheral surfaces of the overhead wire poles 2 (second steel pipes). placed in contact with the As for the second half pipes 32A and 32B, the distance between the bottoms of the inner peripheral surfaces when the flange portions are brought into close contact is the same as the first half pipes 31A and 31B described above with reference to FIG. You may form so that it may become smaller than the outer diameter of the overhead wire pole 2. FIG.

The flange portions 331A, 331B, 332A, 332B, 333A, 333B of the cast iron hardware 3A, 3B are the side ends of the first half pipes 31A, 31B and the side ends of the second half pipes 32A, 32B. , respectively. Here, the side end portion of the half tube is the end portion in the direction orthogonal to the extending direction of the half tube (if the half tube has an arc-shaped cross section, the circumferential direction of the arc). The flange portions 331A, 331B and the flange portions 332A, 332B are formed continuously from the side ends of the first half pipes 31A, 31B and the second half pipes 32A, 32B, respectively. It is formed continuously at the side ends of the two half tubes 32A and 32B. By tightening the flange portions 331A and 331B, the flange portions 332A and 332B, and the flange portions 333A and 333B with fastening means such as bolts 341A and 342A and nuts 341B and 342B, the cast iron hardware 3A and 3B can be clamped against each other.

4 and 5 are diagrams showing the steel pipe connecting process in the first embodiment of the present invention. First, as shown in FIG. 4, the cast iron hardware 3A is attached to the overhead wire pole 2 (second steel pipe). At this time, the outer peripheral surface of the overhead wire pole 2 is brought into contact with the inner peripheral surface of the second half pipe 32A formed in the cast iron hardware 3A. On the other hand, on the inner peripheral surface of the first half tube 31A, a concave portion 311 for fitting a shear key, which will be described later, and a bolt hole 312 are shown. Next, as shown in FIG. 5, the beam 1 (first steel pipe) is attached to the cast iron hardware 3A. At this time, the outer peripheral surface of the beam 1 is brought into contact with the inner peripheral surface of the first half pipe 31A formed in the cast iron hardware 3A. After that, the cast iron hardware 3B is attached from the opposite side of the cast iron hardware 3A, and the outer peripheral surfaces of the beam 1 and the overhead wire pole 2 are brought into contact with the inner peripheral surfaces of the first and second half pipes 31B and 32B of the cast iron hardware 3B. Let Further, by tightening the flange portions of the cast iron hardware 3A, 3B to each other using bolts 341A, 342A and nuts 341B, 342B, the connecting structure as shown in FIG. 2 is constructed.

FIG. 6 is a diagram for explaining an example of using shear key in the first embodiment of the present invention. The shear key 51 is fitted into the recess 311 formed in the inner peripheral surface of the first half tube 31A as described with reference to FIG. combined. A bolt hole 511 is formed in the shear key 51, and a bolt (not shown) is inserted through the bolt hole 312 and the bolt hole 511 on the side of the first half tube 31A to fix the shear key 51 to the cast iron hardware 3A. can be done. By fixing the shear key 51 to the first half tube 31 A and the beam 1 respectively, the axial force acting on the beam 1 can be stably transmitted via the shear key 51 . For example, by forming the bolt holes 511 of the shear keys 51 at appropriate positions by on-site construction, or by preparing and properly using a plurality of shear keys 51 with different positions of the bolt holes 511 , it is possible to prevent dimensional errors in the axial direction of the beam 1 and installation errors. The position can be adjusted between the cast iron metal fittings 3A and 3B corresponding to errors.

FIG. 7 is a diagram showing an example in which the shear key has a tapered cross section in the example shown in FIG. 6, and corresponds to a sectional view along the line VII-VII in the state where the shear key in FIG. 6 is fitted. In this case, the shear key 51 is arranged so that the cross-sectional dimension decreases from the recess 311 toward the opening 11 . When the cast iron hardware 3A and 3B are tightened against each other, the tapered shape of the shear key 51 is inserted into the opening 11, so that the shear key 51 and the beam 1 are in contact with each other without a gap. In this case, the inner peripheral surface of the first half tube 31A contacts the beam 1 through the shear key 51 rather than directly.

In the first embodiment of the present invention as described above, the cast iron hardware 3A, 3B is a plane that includes both the axis X of the beam 1 (first steel pipe) and the axis Y of the overhead wire column (second steel pipe). and are clamped against each other at the flanges. By dividing the cast iron metal fittings 3A and 3B by the plane including the axis of each steel pipe, the force due to the bending moment acting on the steel pipe is applied directly to fastening means such as bolts that tighten the flange portions of the cast iron metal fittings 3A and 3B. The number of fastening means can be reduced. The force due to the bending moment is transmitted by bearing pressure to the first half tubes 31A, 31B in contact with the beam 1, further transmitted inside the cast iron fittings 3A, 3B, to the second half tubes 32A, 32B. The bearing pressure is transmitted to the contacting overhead wire pole 2 . The transmission of force by such bearing pressure is more stable and efficient than when fastening means such as bolts are used. Since the cast iron hardware 3A, 3B has a complex shape including two half pipes and a flange, it is advantageous to integrally form them by casting. Cast iron also has the advantage of being highly corrosion resistant and resistant to fatigue because it has no welds.

In addition, for example, when connecting steel pipes with a flange joint formed along a plane perpendicular to the axis of the steel pipe, it is difficult to adjust the position for dimensional errors and mounting errors in the axial direction of the steel pipes. When a steel pipe is sandwiched between halved pipes divided by a plane including the axis of the steel pipe, the position of the steel pipe can be adjusted in the axial direction. Even when a shear key is used as described above, the axial position of the steel pipe can be adjusted only by adjusting the bolt hole position of the shear key. As a result, even when constructing an overhead wire support structure such as that shown in FIG. can be simplified.

(Second embodiment)
FIG. 8 is a diagram showing an overhead wire support structure including a steel pipe connection structure according to a second embodiment of the present invention. The overhead wire support structure according to the present embodiment includes beams 1A and 1B and overhead wire poles 2 made of steel pipes as in the first embodiment described above. Each of the beams 1A and 1B and the overhead wire pole 2 may be connected using the connection structure 10 including the cast iron hardware 3A and 3B, for example, as in the first embodiment described above, but the example is not limited. do not have. On the other hand, in this embodiment, since the distance between the overhead wire poles 2 is wide, the two beams 1A and 1B are connected using a connection structure 20 including cast iron hardware 6A and 6B, which will be described later. A bending moment is also generated in the beams 1A and 1B due to their own weight and the load of the suspension structure 4 and other facilities (not shown).

9 is a perspective view of the steel pipe connection structure in the example shown in FIG. 8. FIG. In the illustrated example, connection structure 20 includes beam 1A (first steel pipe), beam 1B (second steel pipe), and a pair of cast iron hardware 6A, 6B. The beams 1A, 1B have a common axis X, and the cast iron hardware 6A, 6B are divided by a plane containing this axis X. Referring also to FIG. 10 showing the state in which the beams 1A and 1B are removed and the cast iron hardware 6A and 6B are opened, each of the cast iron hardware 6A and 6B has first half pipes 61A and 61B (first half pipes 61A and 61B). tube 61A is shown in FIG. 10), second half tubes 62A, 62B, flanges 631A, 631B, 632A, 632B, and bolts 641A, which are fastening means for tightening these flanges together. , 642A and nuts 641B, 642B.

The first half pipes 61A, 61B formed on the cast iron hardware 6A, 6B, respectively, are arranged such that the inner peripheral surfaces thereof are at least partially in contact with the beam 1A (first steel pipe). In addition, the second half pipes 62A and 62B are arranged so that the inner peripheral surfaces are at least partially in contact with the beam 1B (second steel pipe). Since the beams 1A and 1B have a common axis X as described above, the first half-tube 61A and the second half-tube 62A, and the first half-tube 61B and the second half-tube 62B are Each is formed continuously. Here, as in the first embodiment described above with reference to FIG. , the distance between the bottoms of the inner peripheral surfaces of the first half tubes 61A and 61B is smaller than the outer diameter of the beam 1A. Similarly, when the flange portions are closely attached between the cast iron hardware 6A and 6B, the distance between the bottoms of the inner peripheral surfaces of the second half pipes 62A and 62B is smaller than the outer diameter of the beam 1B. For example, when the beams 1A and 1B have different outer diameters, the inner peripheral surfaces of the first half pipes 61A and 61B and the inner peripheral surfaces of the second half pipes 62A and 62B which are continuously formed A step may be formed between the

FIG. 10 also shows shear keys 51 and 52 that fit into recesses formed in the inner peripheral surfaces of the first half tube 61A and the second half tube 62A. These shear keys 51 and 52 also fit into the apertures formed in the beams 1A and 1B, respectively. The configuration for adjusting the positions of the beams 1A and 1B with respect to the cast iron metal fittings 6A and 6B according to the positions of the bolt holes of the shear keys 51 and 52 in accordance with the axial dimensional errors and mounting errors of the beams 1A and 1B is the first embodiment. can be employed in this embodiment as well. Further, a configuration in which the shear keys 51 and 52 are formed to have a tapered cross section so as to contact the beams 1A and 1B without gaps can also be adopted as in the first embodiment.

11 and 12 are diagrams showing the steel pipe connecting process in the second embodiment of the present invention. As shown in FIG. 11, first, the cast iron hardware 6A is attached to the beam 1A (first steel pipe). At this time, the outer peripheral surface of the beam 1A is brought into contact with the inner peripheral surface of the first half pipe 61A formed in the cast iron hardware 6A, and the shear key 51 is fitted into the opening formed in the beam 1A. Next, as shown in FIG. 12, the beam 1B (second steel pipe) is attached to the cast iron hardware 6A. At this time, the outer peripheral surface of the beam 1B is brought into contact with the inner peripheral surface of the second half pipe 62A formed in the cast iron hardware 6A, and the shear key 52 (not shown in FIG. 12) is formed in the beam 1B. fit into the hole. Although the beams 1A and 1B are illustrated so that their end faces are in contact with each other, there may be a gap between the end faces of the beams 1A and 1B. The length along the axis X of the section where the first half tubes 61A, 61B and the beam 1A contact is preferably 1.0 times or more the outer diameter of the beam 1A. Similarly, the length along the axis X of the contact section between the second half tubes 62A, 62B and the beam 1B is preferably 1.0 times or more the outer diameter of the beam 1B.

After that, the cast iron hardware 6B is attached from the side opposite to the cast iron hardware 6A, and the outer peripheral surfaces of the beams 1A and 1B are brought into contact with the inner peripheral surfaces of the first and second half pipes 61B and 62B of the cast iron hardware 6B. Further, by tightening the flange portions of the cast iron hardware 6A, 6B to each other using bolts 641A, 642A and nuts 641B, 642B, a connecting structure as shown in FIG. 9 is constructed.

By providing a hinge (not shown) between the flange portion 631A and the flange portion 631B, for example, as shown in FIGS. It can be held in a state of being connected to each other. Workability is further improved by not having to store and transport the cast iron hardware 6A and 6B separately. A similar hinge can be provided between the flanges 333A and 333B of the cast iron metal fittings 3A and 3B in the above-described first embodiment, for example.

In the second embodiment of the present invention as described above, the cast iron hardware 6A, 6B is divided by a plane containing the common axis X of the beam 1A (first steel pipe) and the beam 1B (second steel pipe). , are clamped against each other at the flanges. By dividing the cast iron metal fittings 6A and 6B by the plane including the axis of each steel pipe, the force due to the bending moment acting on the steel pipe is applied directly to fastening means such as bolts that tighten the flange portions of the cast iron metal fittings 6A and 6B. The number of fastening means can be reduced. Forces due to bending moments are transmitted from each of the beams 1A, 1B to the first half-tube 61A, 61B and the second half-tube 62A, 62B respectively by bearing pressure. The transmission of force by such bearing pressure is more stable and efficient than when fastening means such as bolts are used. The advantages of forming the cast iron hardware 6A, 6B by casting are also obtained in the same manner as in the first embodiment.

In the embodiment described above, the shear key has an elliptical shape. This is to reduce the stress concentration at the ends and to increase the shear cross-sectional area of the shear key while reducing the cross-sectional loss of the steel pipe. . Since the shape of the shear key is determined by design, it is not limited to an ellipse in other embodiments, and various shapes such as a circle, an ellipse, and a rectangle with rounded corners are possible.

Although the preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to these examples. It is obvious that a person skilled in the art of the technical field to which the present invention belongs can conceive of various modifications or modifications within the scope of the technical idea described in the claims. Naturally, it is understood that it belongs to the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1, 1A, 1B... Beam 2... Overhead wire pole 3A, 3B... Cast iron hardware 4... Suspension structure 6A, 6B... Cast iron hardware 10, 20... Connection structure 11... Opening 31A, 31B... Third 1 half tube 32A, 32B... second half tube 51, 52... shear key 511... bolt hole 61A, 61B... first half tube 62A, 62B... second half tube, 311... recessed part, 312... bolt hole, 331A, 331B, 332A, 332B, 333A, 333B... flange part, 341A, 342A... bolt, 341B, 342B... nut, 631A, 631B, 632A, 632B... flange part.

Claims (7)

a first steel pipe, a second steel pipe, and a pair of cast iron hardware divided by a plane containing the axis of the first steel pipe and the axis of the second steel pipe;
each of said pair of cast iron hardware comprising:
a first split pipe whose inner peripheral surface is at least partially in contact with the outer peripheral surface of the first steel pipe;
a second half pipe having an inner peripheral surface at least partially in contact with an outer peripheral surface of the second steel pipe;
a flange portion formed continuously on the side end portion of the first half pipe and the side end portion of the second half pipe, respectively, and capable of clamping the pair of cast iron hardware to each other; including
Steel pipe connection structure, wherein the distance between the bottoms of the inner peripheral surfaces of the first half pipe when the flanges of the pair of cast iron hardware are brought into close contact with each other is smaller than the outer diameter of the first steel pipe. . The steel pipe connection structure according to claim 1, wherein the axis of the first steel pipe is perpendicular to the axis of the second steel pipe. the first steel pipe and the second steel pipe have a common axis;
the first half-tube and the second half-tube are formed continuously with each other;
2. The distance between the bottoms of the inner peripheral surfaces of the second half pipe when the flanges of the pair of cast iron hardware are brought into close contact with each other is smaller than the outer diameter of the second steel pipe. A connecting structure of steel pipes as described. The length along the axis of the first steel pipe of the section where the first half pipe and the first steel pipe are in contact is 1.0 times or more the outer diameter of the first steel pipe. The connecting structure of steel pipes according to any one of claims 1 to 3. 1 to 4, further comprising a shear key fitted to each of the recess formed in the inner peripheral surface of the first half pipe and the opening formed in the peripheral surface of the first steel pipe. 5. The connecting structure of steel pipes according to any one of 4. The shear key has a tapered shape with a cross-sectional dimension that decreases from the recess toward the opening,
The steel pipe connection structure according to claim 5, wherein the inner peripheral surface of the first half pipe contacts the first steel pipe via the shear key. a first half-tube, a second half-tube, and flange portions continuously formed on the side ends of the first half-tube and the side ends of the second half-tube, respectively; A steel pipe connection method for connecting a first steel pipe and a second steel pipe using a pair of cast iron hardware included in
For one of the pair of cast iron hardware, the inner peripheral surface of the first half pipe is at least partially in contact with the outer peripheral surface of the first steel pipe, and the inner peripheral surface of the second half pipe is contacted. at least partially contacting the outer peripheral surface of the second steel pipe;
By clamping the pair of cast iron hardware against each other at the flange portion, the other of the pair of cast iron hardware is at least partially aligned with the outer circumference of the first steel pipe. A method of connecting steel pipes, comprising the step of bringing the inner peripheral surface of the second half pipe into at least partial contact with the outer peripheral surface of the second steel pipe.

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