JP7471996B2 - Steel piece for external diaphragm, column-beam joint structure and column-beam joint method - Google Patents

Description

The present invention relates to steel pieces for external diaphragms, column-beam joint structures, and column-beam joint methods.

A column-beam joint structure is known in which an external diaphragm is formed by attaching a steel plate to the outside of a steel pipe column, and stress is transmitted to the beam via the external diaphragm. Various techniques have been proposed to improve the workability of such external diaphragms. For example, Patent Document 1 describes a technique for forming an external diaphragm by partially penetrating and welding four steel plates divided around the circumferential direction of a steel pipe column to each other, and then fillet welding between the steel plate and the steel pipe column. Patent Document 2 describes a technique for optimizing the overhang width of the external diaphragm to reduce the overhanging portion of the external diaphragm and improve transportability and handling.

JP 2007-162368 A JP 2011-94406 A

Here, there are circular steel pipe columns and square steel pipe columns. Square steel pipe columns have a cross section in the shape of a rounded rectangle, and the outer periphery is formed by a flat plate portion and a curved corner portion. Such square steel pipe columns are manufactured, for example, by cold roll forming or cold press forming. As described in Patent Document 2, in order to efficiently transmit stress between the square steel pipe column and the beam, it is desirable to weld the external diaphragm to the peripheral surface of the steel pipe column not only at the flat plate portion but also at the corner portion.

However, in the case of square steel pipe columns, differences in the conditions during the manufacturing process cause variations in the curvature of the corners, which can lead to gaps between the steel plates cut out in advance for the external diaphragm and the circumferential surface of the steel pipe column, making welding difficult. If each steel plate were cut out to match the curvature of the corners, no gaps would form, but this would make the process complicated and unrealistic. Patent Documents 1 and 2 state that external diaphragms can also be applied to square steel pipe columns, but make no mention of how to deal with the variations in the curvature of the corners.

The present invention aims to provide a steel piece for an external diaphragm, a column-beam connection structure, and a column-beam connection method that can reduce the gap that occurs between the external diaphragm and the corner of a square steel pipe column using a simple process.

[1] A steel piece for an external diaphragm having a straight portion extending in the longitudinal direction and corresponding to the shape of the flat portion on the outer periphery of a square steel pipe column, and a bending portion adjacent to the straight portion in the longitudinal direction and having a plurality of grooves formed in one direction intersecting the longitudinal direction, thereby allowing the steel piece to be bent along a corner portion on the outer periphery of the square steel pipe column.
[2] A steel piece for an outer diaphragm as described in [1], wherein the multiple grooves have a planar shape of a slit, V-shape, or trapezoid.
[3] A steel piece for an outer diaphragm described in [1] or [2], wherein the straight portion includes a first and a second straight portion, and the bent portion includes a first bent portion between the first and second straight portions.
[4] A steel piece for an outer diaphragm described in [3], wherein the straight portion further includes a third straight portion, and the bent portion further includes a second bent portion between the second and third straight portions.
[5] A steel piece for an outer diaphragm as described in [4], wherein the straight portion further includes a fourth and a fifth straight portion, and the bent portion further includes a third bent portion between the third and fourth straight portions, and a fourth bent portion between the fourth and fifth straight portions.
[6] A steel piece for an outer diaphragm described in any one of [1] to [5], in which, at least in the bending portion, a chamfer is formed on one or both corners of the side of the steel piece for an outer diaphragm, on the opening side of the multiple grooves or on the opposite side to the openings of the multiple grooves.
[7] A column-beam connection structure comprising a square steel pipe column having a flat portion and a corner portion on its outer periphery, an outer diaphragm joined to the outer periphery of the square steel pipe column, and a steel beam joined to the outer diaphragm, wherein the outer diaphragm is formed from a steel piece for the outer diaphragm having a straight portion joined to the flat portion and a bent portion adjacent to the straight portion and bent along the corner portion by forming a plurality of grooves on either the surface contacting the square steel pipe column or the surface opposite the square steel pipe column, thereby forming a bent portion.
[8] A beam connection structure as described in [7], in which the external diaphragm is fillet welded, partially penetrated welded or fully penetrated welded to the outer periphery of the square steel pipe column.
[9] A column-beam joining method comprising the steps of joining an external diaphragm to the outer periphery of a square steel pipe column having a flat plate portion and a corner portion on its outer periphery, and joining a steel beam to the external diaphragm, wherein the external diaphragm is formed from a steel piece for the external diaphragm having a straight portion joined to the flat plate portion and a bent portion adjacent to the straight portion and bent along the corner portion to be joined to the corner portion by forming a plurality of grooves on either the surface contacting the square steel pipe column or the surface opposite the square steel pipe column, and the step of joining the external diaphragm to the outer periphery of the square steel pipe column comprises the steps of joining the straight portion of the steel piece for the external diaphragm to the flat plate portion, and bending the bent portion of the steel piece for the external diaphragm along the corner portion to join it to the corner portion.
[10] A column-beam joining method as described in [9], in which the plurality of grooves are formed on a surface of the bent portion that contacts the square steel pipe column, and the bent portion is bent along the corner portion by reducing the openings of at least some of the plurality of grooves.
[11] A column-beam connection method as described in [9], in which the multiple grooves are formed on the surface opposite the square steel pipe column of the bent portion, and the bent portion is bent along the corner portion by enlarging the openings of at least some of the multiple grooves.
[12] A column-beam joining method described in any one of [9] to [11], in which the ends of four external diaphragm steel pieces, each of which includes a first and second straight portion and a first bend portion between the first and second straight portions, are joined together to form an external diaphragm.
[13] A column-beam joining method described in any one of [9] to [11], in which the ends of two steel pieces for an external diaphragm, each of which includes a first, second and third straight portion, a first bent portion between the first and second straight portions, and a second bent portion between the second and third straight portions, are joined together to form an external diaphragm.
[14] A column-beam joining method described in any one of [9] to [11], in which an outer diaphragm is formed by joining together both ends of a steel piece for an outer diaphragm, the steel piece including first, second, third, fourth and fifth straight sections, a first bent section between the first and second straight sections, a second bent section between the second and third straight sections, a third bent section between the third and fourth straight sections, and a fourth bent section between the fourth and fifth straight sections.
[15] A column-beam joining method described in any one of [9] to [14], in which the steel piece for the outer diaphragm is fillet welded, partially penetrated welded or fully penetrated welded to the outer periphery of the square steel pipe column.

According to the above configuration, the bent portion of the steel piece for the outer diaphragm can be bent along the corner of the square steel pipe column, thereby reducing the gap that occurs between the outer diaphragm and the corner of the square steel pipe column, and the outer diaphragm can be stably welded to the square steel pipe column even at the corner. Because the bent portion is a flexible portion in which multiple grooves are formed, the bent portion can be bent with a curvature that matches the corner during construction on site by a simple process such as manual work.

1 is a perspective view of a column-beam joint structure according to a first embodiment of the present invention; 2 is a cross-sectional view of the column-beam joint structure shown in FIG. 1 taken along line II-II. FIG. 2 is a perspective view of a steel piece for an external diaphragm used in the beam-column joint structure shown in FIG. 1 . FIG. 4 is a diagram for explaining the principle by which the outer diaphragm steel piece shown in FIG. 3 corresponds to the variation in curvature of the corner portion. FIG. 5 shows a modification of the example shown in FIG. 4 . FIG. 2 is a perspective view showing another example of a steel piece for an outer diaphragm according to the first embodiment of the present invention. FIG. 2 is a perspective view showing another example of a steel piece for an outer diaphragm according to the first embodiment of the present invention. FIG. 4 is a perspective view showing yet another example of a steel piece for an outer diaphragm according to the first embodiment of the present invention. FIG. 4 is a perspective view showing yet another example of a steel piece for an outer diaphragm according to the first embodiment of the present invention. FIG. 4 is a cross-sectional view of a column-beam joint structure according to a second embodiment of the present invention. FIG. 11 is a cross-sectional view of a column-beam joint structure according to a third embodiment of the present invention.

A preferred embodiment of the present invention will be described in detail below with reference to the attached drawings. Note that in this specification and the drawings, components having substantially the same functional configuration are designated by the same reference numerals, and redundant explanations will be omitted.

Figure 1 is a perspective view of a column-beam joint structure according to a first embodiment of the present invention. As shown in the figure, the column-beam joint structure 1 includes a square steel pipe column 2, an outer diaphragm 3 joined to the outer periphery of the square steel pipe column, and a steel beam 4 joined to the outer diaphragm 3. The square steel pipe column 2 has a rounded rectangular cross section and has a flat plate portion 21 and a corner portion 22 on the outer periphery. The outer diaphragm 3 is formed from a steel piece for the outer diaphragm as described later, and is joined to the flat plate portion 21 and the corner portion 22 on the outer periphery of the square steel pipe column 2 by, for example, fillet welding, partial penetration welding, or full penetration welding. The steel beam 4 has an H-shaped cross section and has flanges 41, 42 and a web 43. In the column-beam joint structure 1, the outer diaphragm 3 is arranged at positions corresponding to the flanges 41, 42 of the steel beam 4, and the flanges 41, 42 and the outer diaphragm 3 are joined by, for example, butt welding.

Figure 2 is a cross-sectional view of the beam-column joint structure shown in Figure 1 along line II-II. As shown in the figure, in this embodiment, the outer diaphragm 3 is formed by joining the ends of two outer diaphragm steel pieces 3A and 3B arranged along the outer periphery of the square steel pipe column 2. Note that, for the sake of explanation, the ends of the outer diaphragm steel pieces 3A and 3B are shown in Figure 2, but since the ends are butt-welded, for example, they are not necessarily visible after joining. The outer diaphragm steel pieces 3A and 3B include a straight portion 31 joined to the flat plate portion 21 on the outer periphery of the square steel pipe column 2, and a bent portion 32 adjacent to the straight portion 31 and joined to the corner portion 22 of the square steel pipe column 2. A plurality of grooves 33 are formed on the surface of the bent portion 32 that contacts the square steel pipe column 2. In this case, the bent portion 32 can be bent along the corner portion 22 of the square steel pipe column 2 by reducing the openings of at least some of the grooves 33.

3 is a perspective view of an outer diaphragm steel piece used in the beam-column joint structure shown in FIG. 1. In this embodiment, the outer diaphragm 3 is formed by joining the outer diaphragm steel piece 3A as shown in the figure to the outer periphery of the square steel pipe column 2 by, for example, fillet welding, partial penetration welding, or full penetration welding. Although the outer diaphragm steel piece 3A is shown in the figure, the outer diaphragm steel piece 3B shown in FIG. 2 is similarly configured. The outer diaphragm steel piece 3A is a strip-shaped steel piece cut out from a thick steel plate. The outer diaphragm steel piece 3A has a straight portion 31 extending in the longitudinal direction and a bent portion 32 adjacent to the straight portion 31 in the longitudinal direction and having multiple grooves 33 formed in one direction intersecting the longitudinal direction. Here, the formation of multiple grooves 33 in one direction means that all of the multiple grooves 33 are cut from one side of the outer diaphragm steel piece 3A at the bent portion 32. In the example shown in the figure, the multiple grooves 33 have a slit-like planar shape. More specifically, the outer diaphragm steel piece 3A has three straight portions 31A, 31B, and 31C and two bent portions 32A and 32B. The bent portion 32A is between the straight portions 31A and 31B, and the bent portion 32B is between the straight portions 31B and 31C. As described with reference to FIG. 2, the outer diaphragm 3 can be formed by joining the ends of the outer diaphragm steel pieces 3A and 3B, each of which includes the straight portions 31A, 31B, and 31C and the bent portions 32A and 32B, as described above.

In the illustrated example, the outer diaphragm steel piece 3A has a substantially square rectangular cross section, but in other examples, the outer diaphragm steel piece 3A may have a rectangular cross section, for example, a rectangular cross section that is flatter in the horizontal direction. Also, the outer diaphragm steel piece does not necessarily have to have a strictly rectangular cross section. For example, the outer diaphragm steel piece may have a chamfer for partial penetration welding or full penetration welding as in the example described below, or a chamfer may be formed for other purposes, so that at least a portion of the outer diaphragm steel piece 3A has a substantially rectangular cross section including a chamfer.

Figure 4 is a diagram for explaining the principle of how the outer diaphragm steel pieces shown in Figure 3 respond to the variation in curvature of the corners. In the illustrated example, the case where the outer diaphragm steel pieces 3A, 3B are joined to the outer circumference of two square steel pipe columns 2A, 2B with different curvatures of the corners 22 is described. In the square steel pipe column 2A, the radius of curvature of the corners 22 is R1, and in the square steel pipe column 2B, the radius of curvature of the corners 22 is R2 (R1>R2). In the case of the square steel pipe column 2A, the openings of many of the multiple grooves 33 formed in the bending portion 32 of the outer diaphragm steel pieces 3A, 3B gradually shrink, so that the bending portion 32 bends with a relatively large curvature and can fit along the corners 22 with a curvature radius R1 with a small gap. On the other hand, in the case of the square steel pipe column 2B, the openings of only some of the multiple grooves 33 formed in the bent portion 32 of the outer diaphragm steel pieces 3A and 3B are greatly reduced, so that the bent portion 32 bends with a relatively small curvature and can fit along the corner portion 22 with a curvature radius R2 with a small gap.

As shown in the figure, even in the bent portion 32 in which multiple grooves 33 are formed, the non-bent section is joined to the flat plate portion 21 of the square steel pipe column 2A, 2B. In other words, while the straight portion 31 is joined entirely to the flat plate portion 21, the bent portion 32 does not necessarily have to be joined entirely to the corner portion 22, and a portion of the bent portion 32 may be joined to the flat plate portion 21. In this way, when the difference in the bent section of the bent portion 32 corresponds to the different curvatures of the square steel pipe column 2, the difference in the length of the section joined to the flat plate portion 21 at the bent portion 32 causes a difference in the distance between the ends of the outer diaphragm steel pieces 3A, 3B when they are arranged along the outer periphery of the square steel pipe column 2A, 2B as shown in Figure 4. Specifically, in the example of the square steel pipe column 2A, there is almost no distance between the ends of the steel pieces 3A and 3B for the outer diaphragm, whereas in the example of the square steel pipe column 2B, a gap of distance d occurs between the ends of the steel pieces 3A and 3B for the outer diaphragm. Such a gap can be filled, for example, by adjusting the root spacing during butt welding. Specifically, when butt welding the ends of the steel pieces 3A and 3B for the outer diaphragm, for example, in the example of the square steel pipe column 2A, partial penetration welding without a root spacing or full penetration welding with a minimum root spacing is performed. On the other hand, in the example of the square steel pipe column 2B, full penetration welding with a large root spacing is performed.

As described above, in the first embodiment of the present invention, the bent portion 32 of the steel pieces 3A, 3B for the outer diaphragm can be bent along the corner 22 of the square steel pipe column 2, thereby reducing the gap between the outer diaphragm 3 and the corner 22 of the square steel pipe column 2, and the outer diaphragm 3 can be stably welded to the square steel pipe column 2 even at the corner 22. Since the bent portion 32 is a flexible portion in which multiple grooves 33 are formed, the bent portion 32 can be bent with a curvature that matches the corner 22 during construction on site by a simple process such as manual work.

Figure 5 is a diagram showing a modified example of the example shown in Figure 4. In the example shown in Figure 4, the length of the outer diaphragm steel pieces 3A, 3B is set based on the square steel pipe column 2A with a relatively large curvature of the corner 22, and the gap between the ends of the outer diaphragm steel pieces 3A, 3B is filled in the square steel pipe column 2B with a relatively small curvature of the corner 22. In contrast, in the example of Figure 5, as shown in Figure 5 (A), the length of the outer diaphragm steel pieces 3A, 3B is set based on the square steel pipe column 2B with a relatively small curvature of the corner 22. In this case, when placing the outer diaphragm steel pieces 3A, 3B along the outer circumference of the square steel pipe column 2A with a relatively large curvature of the corner 22 as shown in Figure 5 (B), the straight part 31 of at least one of the outer diaphragm steel pieces 3A, 3B can be cut by the excess length, so that the ends of the outer diaphragm steel pieces 3A, 3B can be appropriately butted and joined.

6 and 7 are perspective views showing another example of the outer diaphragm steel piece according to the first embodiment of the present invention. In the illustrated example, two chamfers 34 are formed on the outer diaphragm steel piece 3A at the bent portion 32. Specifically, the chamfers 34 are formed on one or both corners of the side surface 35 of the outer diaphragm steel piece 3A at the opening side of the multiple grooves 33. In this embodiment, the side surface 35 on the opening side of the multiple grooves 33 is directed toward the square steel pipe column 2, so that when the outer diaphragm steel piece 3A is arranged along the square steel pipe column 2, the chamfers 34 form a groove between the outer diaphragm steel piece 3A and the square steel pipe column 2. Using this groove, the bent portion 32 of the outer diaphragm steel piece 3A can be partially welded to the square steel pipe column 2. In another example, the bent portion 32 may be fully welded to the square steel pipe column 2 by forming a larger groove. In the example of FIG. 6, the straight portion 31 of the outer diaphragm steel piece 3A is not formed with a chamfer 34, so the straight portion 31 may be fillet welded to the square steel pipe column 2. On the other hand, in the example of FIG. 7, the chamfer 34 is formed on both the straight portion 31 and the bent portion 32 of the outer diaphragm steel piece 3A, so the entire outer diaphragm steel piece 3A including the straight portion 31 and the bent portion 32 can be partially welded to the square steel pipe column 2. In another example, a larger groove may be formed to completely weld the entire outer diaphragm steel piece 3A including the straight portion 31 and the bent portion 32 to the square steel pipe column 2. As described later, in another embodiment, a chamfer may be formed on one or both corners of the side surface 36 of the outer diaphragm steel piece 3A on the opposite side to the openings of the multiple grooves 33. In addition, if the outer diaphragm steel piece 3A is not chamfered, in addition to fillet welding the outer diaphragm steel piece 3A to the square steel pipe column 2, it is also possible to position the outer diaphragm steel piece 3A so that there is a gap between it and the square steel pipe column 2, and use this gap as a groove to fully penetrate and weld the outer diaphragm steel piece 3A to the square steel pipe column 2.

8 and 9 are perspective views showing yet another example of the outer diaphragm steel piece according to the first embodiment of the present invention. In the example described so far, the outer diaphragm 3 is formed by the outer diaphragm steel pieces 3A and 3B, each of which corresponds to 1/2 of the outer circumference of the square steel pipe column 2, but this embodiment is not limited to such an example. For example, as shown in FIG. 8, an outer diaphragm steel piece 3C corresponding to 1/4 of the outer circumference of the square steel pipe column 2 may be provided. In this case, the outer diaphragm steel piece 3C has two straight portions 31A and 31B and one bent portion 32A therebetween. For example, the outer diaphragm 3 can be formed by joining the ends of four outer diaphragm steel pieces 3C, each of which has straight portions 31A and 31B and a bent portion 32A. Alternatively, the outer diaphragm 3 may be formed by joining the ends of the outer diaphragm steel piece 3C and another outer diaphragm steel piece corresponding to 3/4 of the outer circumference of the square steel pipe column 2.

Also, for example, as shown in FIG. 9, an outer diaphragm steel piece 3D corresponding to the entire circumference of the square steel pipe column 2 may be provided. In this case, the outer diaphragm steel piece 3D includes five straight portions 31A, 31B, 31C, 31D, and 31E and four bent portions 32A, 32B, 32C, and 32D. The bent portion 32A is between the straight portions 31A and 31B, the bent portion 32B is between the straight portions 31B and 31C, the bent portion 32C is between the straight portions 31C and 31D, and the bent portion 32D is between the straight portions 31D and 31E. In the case of the outer diaphragm steel piece 3D, the outer diaphragm 3 can be formed by joining both ends of the outer diaphragm steel piece 3D, i.e., the ends of the straight portions 31A and 31E opposite to the bent portions 32A and 32D shown in the figure.

Figure 10 is a cross-sectional view of a column-beam joint structure according to the second embodiment of the present invention. Note that Figure 10 is a view similar to Figure 4 in the first embodiment, and the steel beam is omitted. In this embodiment, the steel pieces 5A and 5B for the outer diaphragm forming the outer diaphragm 3 have a straight portion 31 and a bent portion 32, and a plurality of grooves 53 having a V-shaped planar shape are formed in the bent portion 32. In this case, as in the first embodiment, the bent portion 32 can be bent along the corner portion 22 of the square steel pipe column 2 by reducing the openings of at least a part of the plurality of grooves 53. In other respects, the configuration of this embodiment is similar to that of the first embodiment, so duplicated explanations will be omitted. In this embodiment, the same effects as those described for the first embodiment above can be obtained. Note that in other embodiments, the planar shape of the plurality of grooves formed in the bent portion of the steel piece for the outer diaphragm is not limited to the slit shape or V-shape as in the above example, and the plurality of grooves may be formed in a trapezoidal planar shape with a flat portion formed at the tip of the V-shape, for example. The modified examples described for the first embodiment can be applied to the second embodiment and other embodiments as described above.

Figure 11 is a cross-sectional view of a beam-column joint structure according to the third embodiment of the present invention. Note that the steel beam is also omitted from the illustration in Figure 11. In this embodiment, the outer diaphragm steel piece 6A has a straight portion 31 and a bent portion 32 as in the first embodiment, and a plurality of grooves 33 are formed in the bent portion 32. As a difference from the first embodiment, the plurality of grooves 33 are formed on the surface of the outer diaphragm steel piece 6A opposite the square steel pipe column 2 of the bent portion 32. In this case, the bent portion 32 can be bent along the corner portion 22 of the square steel pipe column 2 by enlarging at least a part of the opening of the plurality of grooves 33. In other respects, the configuration of this embodiment is similar to that of the first embodiment, so a duplicated description will be omitted. In this embodiment, the same effects as those described above for the first embodiment can be obtained. In addition, the modified examples described for the first embodiment can be applied to the third embodiment as described above. Specifically, for example, the chamfer 34 shown in Figures 6 and 7 can also be formed on the outer diaphragm steel piece 6A of this embodiment. As described above, the outer diaphragm steel piece 6A is positioned with the side opposite the openings of the grooves 33 facing the square steel pipe column 2, so the chamfer is formed on one or both corners of the side of the outer diaphragm steel piece 6A (side 36 shown in Figures 6 and 7) opposite the openings of the grooves 33.

The above describes in detail preferred embodiments of the present invention with reference to the attached drawings, but the present invention is not limited to these examples. It is clear that a person skilled in the art of the technical field to which the present invention pertains can come up with various modified or revised examples within the scope of the technical ideas described in the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

1...beam-column joint structure, 2, 2A, 2B...square steel pipe column, 21...flat plate section, 22...corner section, 3...outer diaphragm, 3A, 3B, 3C, 3D, 5A, 5B, 6A...steel pieces for outer diaphragm, 31, 31A, 31B, 31C, 31D, 31E...straight section, 32, 32A, 32B, 32C, 32D...bent section, 33, 53...groove, 34...chamfer, 35, 36...side, 4...steel beam, 41, 42...flange, 43...web, R1, R2...radius of curvature, d...distance.

Claims (15)

A straight portion extending in the longitudinal direction and corresponding to the shape of the flat plate portion of the outer periphery of the square steel pipe column;
a bending portion adjacent to the straight portion in the longitudinal direction and formed with a plurality of grooves in a direction intersecting the longitudinal direction, thereby enabling the steel piece for an external diaphragm to be bent along a corner portion of the outer periphery of the square steel pipe column. The steel piece for an outer diaphragm according to claim 1, wherein the plurality of grooves have a slit-like, V-shaped, or trapezoidal planar shape. the straight portion includes a first straight portion and a second straight portion,
3. The steel piece for an outer diaphragm according to claim 1, wherein the bent portion includes a first bent portion located between the first and second straight portions. The straight portion further includes a third straight portion,
4. The outer diaphragm steel piece according to claim 3, wherein the bent portion further includes a second bent portion between the second and third straight portions. the straight portion further includes a fourth and a fifth straight portion,
5. The steel piece for an outer diaphragm according to claim 4, wherein the bent portion further includes a third bent portion between the third and fourth straight portions, and a fourth bent portion between the fourth and fifth straight portions. The steel piece for the outer diaphragm according to any one of claims 1 to 5, wherein at least in the bent portion, a chamfer is formed on one or both corners of the side surface of the steel piece for the outer diaphragm, on the opening side of the grooves or on the side opposite to the openings of the grooves. A square steel pipe column having a flat plate portion and a corner portion on an outer periphery;
An outer diaphragm joined to the outer periphery of the square steel pipe column;
A column-beam joint structure comprising: a steel beam joined to the outer diaphragm,
This is a column-beam connection structure, in which the external diaphragm is formed from a steel piece for the external diaphragm having a straight portion joined to the flat plate portion and a bent portion adjacent to the straight portion and bent along the corner portion by forming a plurality of grooves on either the surface contacting the square steel pipe column or the surface opposite the square steel pipe column. The beam joint structure according to claim 7, wherein the outer diaphragm is fillet welded, partially penetrated welded or fully penetrated welded to the outer periphery of the square steel pipe column. A column-beam joining method including a step of joining an exterior diaphragm to an outer periphery of a square steel pipe column having a flat plate portion and a corner portion on an outer periphery, and a step of joining a steel beam to the exterior diaphragm,
The outer diaphragm is formed of a steel piece for an outer diaphragm having a straight portion joined to the flat plate portion, and a bent portion adjacent to the straight portion and bent along the corner portion by forming a plurality of grooves on either a surface in contact with the square steel pipe column or a surface opposite to the square steel pipe column, and joined to the corner portion,
The step of joining an outer diaphragm to the outer periphery of the square steel pipe column includes:
a step of joining the straight portion of the outer diaphragm steel piece to the flat portion;
and a step of bending the bent portion of the outer diaphragm steel piece along the corner and joining it to the corner. The plurality of grooves are formed on a surface of the bent portion that contacts the square steel pipe column,
The column-beam joining method according to claim 9 , wherein the bent portion is bent along the corner portion by reducing openings of at least some of the plurality of grooves. The plurality of grooves are formed on a surface of the bent portion opposite to the square steel pipe column,
The column-beam joining method according to claim 9 , wherein the bent portion is bent along the corner portion by enlarging openings of at least some of the plurality of grooves. The beam-column joining method according to any one of claims 9 to 11, in which the outer diaphragm is formed by joining together the ends of four steel pieces for the outer diaphragm, each of which includes a first and second straight portion and a first bent portion between the first and second straight portions. The beam-column joining method according to any one of claims 9 to 11, in which the outer diaphragm is formed by joining together ends of two steel pieces for the outer diaphragm, each of which includes a first, second and third straight portion, a first bent portion between the first and second straight portions, and a second bent portion between the second and third straight portions. The column-beam joining method according to any one of claims 9 to 11, in which the outer diaphragm is formed by joining together both ends of the steel piece for the outer diaphragm, which includes the first, second, third, fourth and fifth straight sections, a first bent section between the first and second straight sections, a second bent section between the second and third straight sections, a third bent section between the third and fourth straight sections, and a fourth bent section between the fourth and fifth straight sections. A beam-column joining method according to any one of claims 9 to 14, in which the outer diaphragm steel piece is fillet welded, partially penetrated welded or fully penetrated welded to the outer periphery of the square steel pipe column.

Images