JP7622723B2 - Joint structure between square steel pipe column and H-shaped steel beam and manufacturing method for joint structure - Google Patents

Description

The present invention relates to a joint structure between a column and a beam in a building and a manufacturing method for the joint structure, and in particular to a joint structure between a square steel pipe column and an H-shaped steel beam.

Square steel pipes, such as cold roll-formed square steel pipes and cold press-formed square steel pipes, are widely used as pillar materials for low- to mid-rise to high-rise steel buildings. At the joint between a square steel pipe column and an H-shaped steel beam, when a horizontal force acts on the building during an earthquake or other events, stress is transmitted from the flange of the H-shaped steel beam to the side of the square steel pipe column. To prevent localized deformation on the side of the square steel pipe column due to this stress, it is common practice to install horizontal stiffeners called diaphragms on the square steel pipe column at the same height as the flange of the H-shaped steel beam.

The joints between square steel pipe columns and H-shaped steel beams can be broadly classified into three types: the internal diaphragm type, which uses an internal diaphragm; the through diaphragm type, which uses a through diaphragm; and the external diaphragm type, which uses an external diaphragm.

Of these, the through diaphragm type is most commonly used for the connection between a square steel pipe column and an H-shaped steel beam. Figures 10(a) and 10(b) show a perspective view and a plan view of a connection between a square steel pipe column 81 and an H-shaped steel beam 82 using the through diaphragm type. Figure 11 shows a longitudinal cross-sectional view of the main parts of a connection between a square steel pipe column 81 and an H-shaped steel beam 82 using the through diaphragm type.

As shown in Figures 10(a) and 10(b) and Figure 11, in the joint between a square steel pipe column 81 and an H-shaped steel beam 82 using the through diaphragm type, a through diaphragm 85 is provided so as to penetrate the cross section of the square steel pipe column 81. Therefore, the joint between a square steel pipe column and an H-shaped steel beam using the through diaphragm type is assembled by cutting the square steel pipe column 81 at the position where the through diaphragm 85 is to be provided, inserting the through diaphragm 85 into the cut position, and welding the square steel pipe column 81 and the through diaphragm 85 together.

As shown in FIG. 11, the weld 86 between the square steel pipe column 81 and the through diaphragm 85 is fully welded, so that the performance of the square steel pipe column 81 is ensured even if the through diaphragm 85 is provided so as to penetrate the cross section of the square steel pipe column 81. The welding between the square steel pipe column 81 and the through diaphragm 85 is performed in a steel frame manufacturing factory or the like using automatic welding such as robot welding, which has high welding efficiency, so that a high-quality and stable weld 86 can be obtained.

However, as described above, the assembly of the joint between the square steel pipe column and the H-shaped steel beam using the through diaphragm type is performed by cutting the square steel pipe column 81 at the position where the through diaphragm 85 is to be installed, inserting the through diaphragm 85 at the cut position, and welding the square steel pipe column 81 and the through diaphragm 85 together. Therefore, it takes time and effort to cut the square steel pipe column 81 and to prepare the groove for full penetration welding of the square steel pipe column 81 to the through diaphragm 85, and the amount of welding tends to be large. In addition, high skill is required to ensure precision, such as aligning the square steel pipe column 81 that is joined above and below the through diaphragm 85.

Furthermore, the through diaphragm 85, which is provided to penetrate the cross section of the square steel pipe column 81, is considered to be part of the square steel pipe column 81 when the building is designed. As a prerequisite for this design, it is necessary to use a welding material with a strength equal to or greater than that of the square steel pipe column 81 for the weld 86 between the square steel pipe column 81 and the through diaphragm 85, which tends to increase material costs and construction load. For example, if high-strength steel is used for the square steel pipe column 81, it becomes necessary to use a high-strength welding material with a strength class equal to or greater than that of the square steel pipe column 81 for the weld 86 between the square steel pipe column 81 and the through diaphragm 85.

12(a) and 12(b) show a perspective view and a plan view of a joint between a square steel pipe column 81 and an H-shaped steel beam 82 using the internal diaphragm type. As shown in FIG. 12(a) and FIG. 12(b), in the joint between a square steel pipe column 81 and an H-shaped steel beam 82 using the internal diaphragm type, the internal diaphragm 84 is provided inside the square steel pipe column 81 without penetrating the cross section of the square steel pipe column 81. Therefore, the strength of the welding material used in the weld between the square steel pipe column 81 and the internal diaphragm 84 does not affect the performance of the square steel pipe column 81. In other words, it is not necessary to use a welding material having a strength equal to or greater than that of the square steel pipe column 81 for the weld between the square steel pipe column 81 and the internal diaphragm 84, and it is sufficient to use a welding material having a strength equal to or greater than that of the H-shaped steel beam 82.

However, welding between the square steel pipe column 81 and the inner diaphragm 84 is performed by dropping the inner diaphragm 84 into the square steel pipe column 81, making it extremely difficult to control the assembly precision and welding conditions of the inner diaphragm 84 and backing metal, as well as to inspect and repair the welded joints.

13(a) and 13(b) show a perspective view and a plan view of a joint between a square steel pipe column 81 and an H-shaped steel beam 82 using the external diaphragm type. As shown in FIG. 13(a) and FIG. 13(b), in the joint between a square steel pipe column 81 and an H-shaped steel beam 82 using the external diaphragm type, the external diaphragm 83 is provided on the outside of the square steel pipe column 81 without penetrating the cross section of the square steel pipe column 81. Therefore, as in the case of the internal diaphragm type, the strength of the welding material used in the weld between the square steel pipe column 81 and the external diaphragm 83 does not affect the performance of the square steel pipe column 81. In other words, for the weld between the square steel pipe column 81 and the external diaphragm 83, it is not necessary to use a welding material having a strength equal to or greater than that of the square steel pipe column 81, and it is sufficient to use a welding material having a strength equal to or greater than that of the H-shaped steel beam 82.

As shown in Figures 13(a) and 13(b), in the joint between a square steel pipe column 81 and an H-shaped steel beam 82 using the external diaphragm type, welding between the square steel pipe column 81 and the external diaphragm 83 is performed from the outside of the square steel pipe column 81. This makes it easy to attach the external diaphragm 83 to the square steel pipe column 81, and ensures assembly precision between the components. Furthermore, since no diaphragm is inserted inside the square steel pipe column 81, it is also easy to work with when filling the inside of the square steel pipe column 81 with concrete.

Figures 14 to 16 show longitudinal cross-sectional views of the main parts of the joint between a square steel pipe column 81 and an H-shaped steel beam 82 using an external diaphragm. Figure 14 shows an example in which the weld 87 between the square steel pipe column 81 and the external diaphragm 83 is fillet welded. Figure 15 shows an example in which the weld 88 between the square steel pipe column 81 and the external diaphragm 83 is fully welded. Figure 16 shows an example in which the weld 89 between the square steel pipe column 81 and the external diaphragm 83 is partially welded.

The square steel pipe column 81 and the outer diaphragm 83 are generally joined by fillet welding as shown in Figure 14, or by full penetration welding or partial penetration welding after groove preparation on the outer diaphragm 83 as shown in Figures 15 and 16. Semi-automatic gas shielded arc welding is used for these fillet welding, full penetration welding, and partial penetration welding, but compared to automatic welding such as robot welding used in the through diaphragm type, production efficiency tends to be lower.

As shown in Figures 13(a) and 13(b), the corners 81c of the cold-formed steel pipe column 81 have a radius, making it more difficult to weld the outer diaphragm 83 than to the flat portion of the side of the steel pipe column 81. In particular, when joining the outer diaphragm 83 to the steel pipe column 81 by full penetration welding or partial penetration welding, it is difficult to perform groove preparation on the outer diaphragm 83 that is attached near the corners 81c of the steel pipe column 81.

As shown in FIG. 13(b), in the joint between a square steel pipe column 81 and an H-shaped steel beam 82 using an external diaphragm, the protruding width 83h of the external diaphragm 83 from the side of the square steel pipe column 81 is often made large in order to ensure the strength of the column-beam joint. Therefore, when a square steel pipe column 81 with an external diaphragm 83 attached is manufactured in a steel frame manufacturing factory and transported to a construction site, if the protruding width 83h of the external diaphragm 83 is large, the number of square steel pipe columns 81 that can be loaded onto a transport vehicle at one time is limited, which tends to reduce transport efficiency.

Therefore, Patent Documents 1 and 2 propose an external diaphragm that can ensure the strength of the column-beam joint while reducing the protruding width of the external diaphragm, and a column-beam joint structure using the same.

Specifically, Patent Document 1 proposes using a sleeve-shaped outer diaphragm formed by bending flat steel outward so that it fits the outer periphery of a square steel pipe column, thereby reducing the planar shape compared to conventional outer diaphragms.

Patent Document 2 also proposes combining four L-shaped steel pieces to form an outer diaphragm, and using a thicker material for the L-shaped steel pieces to reduce the dimensions of the outer diaphragm. The L-shaped steel pieces are joined together by fillet welding or partial penetration welding on the front and back surfaces.

JP 2006-002351 A JP 2016-108868 A

Here, to ensure the quality of the weld between the square steel pipe column and the external diaphragm, it is necessary to ensure the root spacing between the square steel pipe column and the external diaphragm with appropriate precision. If the root spacing is too small, welding defects are more likely to occur, and if the root spacing is too large, the amount of welding increases, deteriorating workability. However, in Patent Document 1, localized residual stress occurs in the flat steel when bending the flat steel out of plane, which makes it difficult to ensure dimensional precision when manufacturing the external diaphragm and assembly precision when attaching the external diaphragm to the square steel pipe column.

In addition, Patent Documents 1 and 2 assume that the square steel pipe column and the outer diaphragm are joined by fillet welding using gas-shielded arc welding, or by partial penetration welding after groove preparation on the outer diaphragm. Therefore, there is an issue that the manufacturing efficiency is likely to be low compared to automatic welding such as robot welding used in the through diaphragm type.

The present invention was made to solve these problems, and aims to provide a joint structure between a square steel pipe column and an H-shaped steel beam, and a manufacturing method for the joint structure, that has high manufacturing efficiency and ensures high assembly accuracy between the components.

To solve the above problems, the present invention has the following features:

[1] A joint structure between a square steel pipe column and an H-shaped steel beam, in which an H-shaped steel beam is joined to a square steel pipe column via an external diaphragm, in which a welding hole surrounded by a metal is provided between the side surface of the square steel pipe column and the end face of the external diaphragm, and the square steel pipe column and the external diaphragm are joined by a weld formed by filling the welding hole with molten metal by electroslag welding.

[2] The connection structure between the square steel pipe column and the H-shaped steel beam described in [1], in which the outer diaphragm is extended to the corner of the square steel pipe column, the corner of the square steel pipe column has a radius, a filler material made of a steel plate is provided in the gap between the outer diaphragm and the corner of the square steel pipe column that is caused by the radius, and the welding hole is extended linearly from the side of the square steel pipe column to the side of the filler material.

[3] The joining structure of a square steel pipe column and an H-shaped steel beam described in [1] or [2], in which a partition made of a steel piece is provided inside the welding hole so that the welding hole is divided into two or more holes in the thickness direction of the outer diaphragm.

[4] A joint structure between a square steel pipe column and an H-shaped steel beam described in [1] or [2], in which the yield strength of the outer diaphragm is greater than the yield strength of the flange of the H-shaped steel beam.

[5] A joint structure between a square steel pipe column and an H-shaped steel beam described in [3], in which the yield strength of the outer diaphragm is greater than the yield strength of the flange of the H-shaped steel beam.

[6] A manufacturing method for a joint structure between a square steel pipe column and an H-shaped steel beam, in which an H-shaped steel beam is joined to a square steel pipe column via an external diaphragm, in which a welding hole is provided by surrounding the area between the side surface of the square steel pipe column and the end face of the external diaphragm with a metal strip, and the welding hole is filled with molten metal by electroslag welding with a heat input of 100 to 1500 kJ/cm to form a weld, thereby joining the square steel pipe column to the external diaphragm.

[7] The manufacturing method for a joint structure between a square steel pipe column and an H-shaped steel beam described in [6], in which the outer diaphragm is extended to the corner of the square steel pipe column, and the corner of the square steel pipe column has a radius, and a filler material made of a steel plate is provided in the gap between the outer diaphragm and the square steel pipe column caused by the radius, so that the welding hole is extended linearly from the side of the square steel pipe column to the side of the filler material.

[8] A method for manufacturing a joint structure between a square steel pipe column and an H-shaped steel beam described in [6] or [7], in which a partition wall made of a steel piece is provided inside the welding hole so that the welding hole is divided into two or more holes in the thickness direction of the outer diaphragm.

[9] A method for manufacturing a joint structure between a square steel pipe column and an H-shaped steel beam described in [6] or [7], in which the yield strength of the outer diaphragm is greater than the yield strength of the flange of the H-shaped steel beam.

[10] A method for manufacturing a joint structure between a square steel pipe column and an H-shaped steel beam described in [8], in which the yield strength of the outer diaphragm is greater than the yield strength of the flange of the H-shaped steel beam.

In the joint structure between a square steel pipe column and an H-shaped steel beam and the manufacturing method of the joint structure according to the present invention, the square steel pipe column and the external diaphragm are joined by electroslag welding. Electroslag welding is a welding method that applies a large heat input of up to several million J/cm, and is extremely efficient compared to manual or semi-automatic gas-shielded arc welding. Therefore, the manufacturing efficiency can be significantly improved compared to the joint structure between a square steel pipe column and an H-shaped steel beam using a general external diaphragm type that is joined by gas-shielded arc welding.

In addition, in the joint structure between a square steel pipe column and an H-shaped steel beam and the manufacturing method of the joint structure according to the present invention, electroslag welding between the square steel pipe column and the outer diaphragm is performed from the outside of the square steel pipe column. This ensures assembly precision for the root spacing between the side of the square steel pipe column and the end face of the outer diaphragm, the backing metal, etc.

FIG. 1 is a plan view of a joint structure between a square steel pipe column and an H-shaped steel beam according to a first embodiment of the present invention. FIG. 2 is a vertical cross-sectional view showing a main part of a joint structure between a square steel pipe column and an H-shaped steel beam according to a first embodiment of the present invention. FIG. 3 is a vertical cross-sectional view showing a main part of a joint structure between a square steel pipe column and an H-shaped steel beam according to a first embodiment of the present invention. FIG. 4 is a diagram showing the shape of a steel plate in a joint structure of a square steel pipe column and an H-shaped steel beam of the present invention. 5(a) to 5(c) are diagrams showing the manufacturing procedure of the joint structure of the present invention between a square steel pipe column and an H-shaped steel beam. FIG. 6 is a plan view showing an example of the shape of an exterior diaphragm in a joint structure of a square steel pipe column and an H-shaped steel beam of the present invention. 7(a) and 7(b) are plan views showing other examples of the shape of the exterior diaphragm in the joint structure of a square steel pipe column and an H-shaped steel beam of the present invention. FIG. 8 is a vertical cross-sectional view showing a main part of a joint structure between a square steel pipe column and an H-shaped steel beam according to a second embodiment of the present invention. FIG. 9 is a vertical cross-sectional view showing a main part of a joint structure between a square steel pipe column and an H-shaped steel beam according to a second embodiment of the present invention. 10(a) and 10(b) are a perspective view and a plan view showing a joint between a square steel pipe column and an H-shaped steel beam using a through diaphragm type joint. FIG. 11 is a vertical cross-sectional view showing a main portion of a joint between a square steel pipe column and an H-shaped steel beam using a through diaphragm type joint. 12(a) and 12(b) are a perspective view and a plan view showing a joint between a square steel pipe column and an H-shaped steel beam using an internal diaphragm type. Figures 13(a) and 13(b) are a perspective view and a plan view showing a joint between a square steel pipe column and an H-shaped steel beam using an external diaphragm type. FIG. 14 is a vertical cross-sectional view showing a main part of a joint between a square steel pipe column and an H-shaped steel beam using an external diaphragm type. FIG. 15 is a vertical cross-sectional view showing a main part of a joint between a square steel pipe column and an H-shaped steel beam using an external diaphragm type. FIG. 16 is a vertical cross-sectional view showing a main part of a joint between a square steel pipe column and an H-shaped steel beam using an external diaphragm type.

Hereinafter, with reference to the drawings, an embodiment of a joint structure between a square steel pipe column and an H-shaped steel beam and a manufacturing method of the joint structure of the present invention will be described in detail.
First Embodiment
Fig. 1 shows a plan view of a joint structure between a square steel pipe column and an H-shaped steel beam according to a first embodiment of the present invention. Fig. 2 and Fig. 3 show longitudinal sectional views of the main parts of the joint structure between a square steel pipe column and an H-shaped steel beam according to the first embodiment of the present invention.

As shown in Figures 1 to 3, the joint structure between a square steel pipe column and an H-shaped steel beam in this embodiment is a square steel pipe column 1 to which an H-shaped steel beam 2 is joined via an outer diaphragm 3. Specifically, as shown in Figure 2, a welding hole 32 surrounded by a backing metal 31 is provided between the side surface of the square steel pipe column 1 and the end face of the outer diaphragm 3. Then, as shown in Figure 3, the square steel pipe column 1 and the outer diaphragm 3 are joined by a weld 5 formed by filling the welding hole 32 with molten metal by electroslag welding.

As shown in FIG. 1, the cross-sectional shape of the electroslag welding hole 32 is rectangular, similar to the electroslag welding hole between the skin plate and the inner diaphragm at the joint between the box section column and the H-shaped steel beam using the inner diaphragm type.

In addition, in the joint structure of the square steel pipe column and the H-shaped steel beam of this embodiment, as shown in Figure 1, the outer diaphragm 3 is extended to the corner 1c of the square steel pipe column 1 and beyond the corner 1c. In addition, the corner 1c of the square steel pipe column 1 has a radius, and in the gap between the outer diaphragm 3 caused by this radius, a filler material 4 made of a steel plate that matches the shape of the corner 1c is provided as shown in Figure 4.

The backing metal 31 and the welding hole 32 extend linearly from the side of the square steel pipe column 1 to the side of the filler 4. The backing metal 31 and the welding hole 32 extending horizontally in FIG. 1 extend linearly from the side of the square steel pipe column 1 to the side of the filler 4, and further to between the outer diaphragms 3. That is, the welding hole 32 is formed on the side of the square steel pipe column 1 by being surrounded by the square steel pipe column 1, the outer diaphragm 3, and the backing metal 31, and is formed at the corner 1c of the square steel pipe column 1 by being surrounded by the filler 4, the outer diaphragm 3, and the backing metal 31. The both ends of the welding hole 32 extending horizontally in FIG. 1 are formed by being surrounded by the space between the outer diaphragms 3 and the backing metal 31. This configuration makes it possible to join the outer diaphragm 3 by electroslag welding up to the corner 1c of the square steel pipe column 1, and even beyond the corner 1c to the space between the outer diaphragms 3, over a length equal to or greater than the outer diameter of the square steel pipe column 1.

The H-shaped steel beam 2 connected to the square steel pipe column 1 can be either a rolled H-shaped steel or a welded assembled H-shaped steel.

The backing plate 31 can be made of the same steel material as that used in electroslag welding between the skin plate and the inner diaphragm at the joint between the box section column and the H-shaped steel beam using the inner diaphragm type.

The filler 4 attached to the corner 1c of the square steel pipe column 1 is made of a steel plate having a strength equal to or greater than that of the outer diaphragm 3. In order to facilitate electroslag welding, the plate thickness of the filler 4 is set equal to or greater than the plate thickness _td of the outer diaphragm 3.

In addition, in order to prevent molten metal from leaking out of the welding hole 32 during electroslag welding, the filler 4 is arranged to be in contact with the square steel pipe column 1 at the start of the radius of the corner 1c of the square steel pipe column 1. In contrast, at the center of the radius of the corner 1c of the square steel pipe column 1, the square steel pipe column 1 and the filler 4 do not necessarily need to be in contact, and there may be a gap between the filler 4 and the corner 1c of the square steel pipe column 1. For example, in FIG. 4, an example is shown in which the side surface of the filler 4 facing the corner 1c of the square steel pipe column 1 is formed into a curved shape that matches the radius of the corner 1c, but a part of the side surface of the filler 4 facing the corner 1c of the square steel pipe column 1 may include a flat surface.

In addition, it is preferable that the yield strength of the exterior diaphragm 3 is greater than the yield strength of the flange of the H-shaped steel beam 2 attached to the exterior diaphragm 3. In this way, the protruding width h d of the exterior diaphragm 3 shown in Fig. ₁ can be reduced without reducing the strength of the beam-column joint against the stress acting on the side surface of the square steel pipe column 1 from the flange 21 of the H-shaped steel beam 2 during an earthquake or the like. Then, when the square steel pipe column 1 attached to the exterior diaphragm 3 is manufactured in a steel frame manufacturing factory and transported to a construction site, the transportation efficiency of the square steel pipe column 1 is less likely to be impaired by the protruding width h _d of the exterior diaphragm 3.

Figures 5(a) to 5(c) show the manufacturing procedure for the joint structure of a square steel pipe column and an H-shaped steel beam in this embodiment.

First, as shown in FIG. 5(a), the filler material 4 is attached to the corner 1c of the square steel pipe column 1. When attaching the filler material 4 to the square steel pipe column 1, it is preferable to avoid direct welding to the corner 1c of the square steel pipe column 1, and to weld the tip of the filler material 4 in the plate thickness direction to the start position of the radius of the corner 1c of the square steel pipe column 1. In this way, it is possible to suppress the deterioration of mechanical performance caused by welding in the corner 1c of the square steel pipe column 1 manufactured by cold roll-formed square steel pipes or cold press forming.

Next, as shown in FIG. 5(b), the square steel pipe column 1 is laid on its side, and the outer diaphragm 3 and backing metal 31 are temporarily attached to the two opposing sides, and a welding hole 32 is provided in a straight line from the side of the square steel pipe column 1 to the side of the filler material 4. Then, the welding hole 32 is filled with molten metal by electroslag welding to form a weld 5, and the square steel pipe column 1 and the outer diaphragm 3 are joined.

Then, rotate the square steel pipe column 1 by 90°. Then, as shown in FIG. 5(c), temporarily attach the outer diaphragm 3 and the backing metal 31 to the remaining two sides of the square steel pipe column 1, and provide a linear welding hole 32 from the side of the square steel pipe column 1 to the side of the filler material 4, and further to the space between the outer diaphragms 3. Then, fill the welding hole 32 with molten metal by electroslag welding to form a weld 5, and join the square steel pipe column 1 and the outer diaphragm 3.

In the above example of the manufacturing procedure, the filler 4 is first attached to the corner 1c of the square steel pipe column 1, but a member that combines the filler 4, the outer diaphragm 3, and the backing metal 31 into one unit may be manufactured in advance, and this member may be attached to the square steel pipe column 1. In this way, the manufacturing procedure for the joint structure of the square steel pipe column and the H-shaped steel beam of this embodiment can be simplified.

In the joint structure of the square steel pipe column and the H-shaped steel beam of this embodiment, the outer diaphragm 3 is attached to the outside of the square steel pipe column 1, so electroslag welding between the square steel pipe column 1 and the outer diaphragm 3 is performed from the outside of the square steel pipe column 1. This ensures assembly precision for the root clearance G between the surface of the square steel pipe column 1 and the end face of the outer diaphragm 3, the backing plate 31, and the like.

The root spacing G between the surface of the square steel pipe column 1 and the end face of the external diaphragm 3 in the joint structure of the square steel pipe column and the H-shaped steel beam of this embodiment can be set to an appropriate dimension, similar to the root spacing between the inner surface of the box section column and the end face of the internal diaphragm in the joint between the box section column and the H-shaped steel beam using the internal diaphragm type.

In addition, in the joint structure of the square steel pipe column and the H-shaped steel beam of this embodiment, the square steel pipe column 1 and the external diaphragm 3 are joined by electroslag welding. Therefore, compared to the joint structure of the square steel pipe column and the H-shaped steel beam using the general external diaphragm type, which is joined by gas-shielded arc welding, the manufacturing efficiency can be significantly improved.

Figures 6(a), 6(b), 7(a), and 7(b) show modified shapes of the outer diaphragm 3 in the joint structure of a square steel pipe column and an H-shaped steel beam of this embodiment.

6(a) and 6(b) are modified examples in which the width of the outer diaphragm 3A is reduced from the width of the outer diaphragm 3 shown in FIG. 1. In the example shown in FIG. 1, the filler material 4 is attached to the corner 1c of the square steel pipe column 1, making it possible to join the outer diaphragm 3 having a width equal to or greater than the outer diameter of the square steel pipe column 1 by electroslag welding. In contrast, in this modified example, it is not necessary to attach the filler material 4 to the corner 1c of the square steel pipe column 1. In this modified example, the outer diaphragm 3 can be extended to a position that does not overlap the radius of the corner 1c of the square steel pipe column 1. The square steel pipe column 1 and the outer diaphragm 3 are joined by a weld 5 formed by filling the welding hole 32 with molten metal by electroslag welding, as in the examples shown in FIGS. 1 to 3. Also, as shown in Figures 3(a) and 3(b), the external diaphragm 3 is joined to one to four of the four sides of the square steel pipe column 1, depending on the number of H-shaped steel beams 2 attached to the square steel pipe column 1.

Figure 4(a) shows a modified example in which a polygonal steel plate is used as the outer diaphragm 3B. Also, Figure 4(b) shows a modified example in which a circular arc is included in part of the planar shape of the outer diaphragm 3C. As shown in Figure 4(b), by including a circular arc in part of the planar shape of the outer diaphragm 3C, stress can be smoothly transmitted from the flange 21 of the H-shaped steel beam 2 to the side of the square steel pipe column 1 via the outer diaphragm. This is preferable because it can prevent cracks and breaks from occurring in the outer diaphragm 3.

In addition, the manufacturing method of the joint structure between a square steel pipe column and an H-shaped steel beam in this embodiment is realized by performing electroslag welding so that the heat input is 100 to 1500 kJ/cm when manufacturing the joint structure between the square steel pipe column 1 and the H-shaped steel beam 2 described above.
Second Embodiment
8 and 9 show longitudinal sectional views of essential parts of a joint structure between a square steel pipe column and an H-shaped steel beam according to a second embodiment of the present invention.

As shown in Figures 8 and 9, in the joint structure of the square steel pipe column and the H-shaped steel beam of this embodiment, the flange 21 of the H-shaped steel beam 2 and the outer diaphragm 3 have a larger plate thickness than the joint structure of the square steel pipe column and the H-shaped steel beam of the first embodiment. When electroslag welding with a large heat input is applied to general steel materials for architectural structures, the toughness of the welded part 5 by electroslag welding decreases, and brittle fracture is likely to occur in the welded part 5 due to the stress transmitted from the flange 21 of the H-shaped steel beam 2 to the outer diaphragm 3 during an earthquake. In particular, when the plate thickness of the outer diaphragm 3 is large as in this embodiment, the amount of heat input required to ensure penetration of the weld metal into the members surrounding the welding hole during electroslag welding increases, which is likely to cause a significant decrease in the toughness of the welded part 5.

Therefore, in the joint structure of the square steel pipe column and the H-shaped steel beam of this embodiment, as shown in Fig. 8 and Fig. 9, a partition wall 33 made of a steel piece is provided inside the welding hole surrounded by the surface of the square steel pipe column 1, the end face of the outer diaphragm 3, and the backing metal 31. As a result, the welding hole surrounded by the surface of the square steel pipe column 1, the end face of the outer diaphragm 3, and the backing metal 31 is divided into two welding holes 34, 35 in the plate thickness direction of the outer diaphragm 3. In this way, the widths _w1 , _w2 of each welding hole 34, 35 in the plate thickness direction of the outer diaphragm 3 can be reduced. That is, even if the plate thickness of the flange 21 of the H-shaped steel beam 2 or the outer diaphragm 3 is large, the heat input required to ensure the penetration of the weld metal into the members surrounding the welding hole during electroslag welding can be reduced, and a significant decrease in the toughness of the welded portion 5 can be suppressed.

The above describes the embodiment of the joint structure between a square steel pipe column and an H-shaped steel beam and the manufacturing method of the joint structure of the present invention, but the specific configuration of the present invention is not limited to the above-mentioned embodiment, and the design can be changed without departing from the gist of the present invention.

For example, although the widths _w1 , _w2 of the welding holes 34, 35 are the same in Fig. 8 and Fig. 9, the widths _w1 , _w2 of the welding holes 34, 35 may be different. Also, although Fig. 8 and Fig. 9 show an example in which the welding hole surrounded by the side surface of the square steel pipe column 1, the end face of the outer diaphragm 3, and the backing metal 31 is divided into two welding holes 34, 35, the welding hole may be divided into three or more welding holes in the thickness direction of the outer diaphragm 3. It is preferable to appropriately set the number of divisions and width of the welding hole in consideration of the type and dimensions of the steel material used, the welding conditions of the electroslag welding, etc., so that brittle fracture of the welded portion 5 can be effectively suppressed against the stress transmitted from the flange 21 of the H-shaped steel beam 2 to the outer diaphragm 3 during an earthquake or the like.

In the second embodiment of the joint structure between a square steel pipe column and an H-shaped steel beam, a partition wall 33 was provided inside the welding hole, dividing the outer diaphragm 3 into two welding holes 34 and 35 in the thickness direction, to verify how much the heat input of electroslag welding can be reduced.

First, calculation examples No. 1 to 3 were set based on the joint structure of a square steel pipe column and an H-shaped steel beam of the first embodiment shown in Figures 2 and 3. Table 1 shows the outer diameter _Dc and wall thickness _tc of the square steel pipe column 1, the protruding width _hd and plate thickness _td of the outer diaphragm 3, and the root spacing G and width _w0 of the welding hole 32 in each of calculation examples No. 1 to 3.

As shown in Table 1, in Calculation Examples No. 1 to 3, the outer diameter _Dc of the square steel pipe column 1 was changed to three types, namely, 500 mm, 800 mm, and 1000 mm. In addition, in Calculation Examples No. 1 to 3, the wall thickness _tc of the square steel pipe column 1, and the protruding width _hd and plate thickness _td of the outer diaphragm 3 were changed so as to correspond to the size of the outer diameter _Dc of the square steel pipe column 1. The root spacing G of the welding hole 32 was set to 23 mm in all of Calculation Examples No. 1 to 3.

The amount of heat input required to ensure penetration of the weld metal into the members surrounding the weld hole 32 during electroslag welding varies depending on the dimensions of the members surrounding the weld hole 32. Therefore, in this embodiment, the heat input of calculation example No. 1 was assumed to be 300 kJ/cm as a calculation standard. The calculation of the amount of heat input of calculation examples No. 2 and 3 was performed based on the cross-sectional area of the weld hole 32, the wall thickness _tc of the square steel pipe column 1, the protruding width _hd of the outer diaphragm 3, and the plate thickness _td of calculation examples No. 2 and 3 relative to calculation example No. 1. The calculation results are also shown in Table 1.

As can be seen from calculation examples No. 1 to 3 in Table 1, when the plate thickness _td of the outer diaphragm 3 is small, the heat input of electroslag welding is kept small, and a significant decrease in the toughness of the welded portion 5 is unlikely to occur. In contrast, as the plate thickness _td of the outer diaphragm 3 increases, the heat input of electroslag welding also increases, making it more likely that a significant decrease in the toughness of the welded portion 5 will occur.

Next, calculation example No. 3A based on the joint structure of the square steel pipe column and the H-shaped steel beam of the second embodiment shown in Figures 8 and 9 was set up to calculate the heat input of electroslag welding. Table 2 shows the outer diameter _Dc and wall thickness _tc of the square steel pipe column 1, the protruding width _hd and plate thickness _td of the outer diaphragm 3, and the root spacing G and widths _w1 and _{w2 of the welding holes 34 and 35 in calculation example No. 3A. Calculation example No. 3A is a calculation example in which a partition wall 33 is provided inside the welding hole 32 of calculation example No. 3} shown in Table 1, and the outer diaphragm 3 is divided into two welding holes 34 and 35 in the plate thickness direction. The thickness B of the partition wall 33 in calculation example No. 3A was set to 15 mm, and the widths _w1 and _w2 of the welding holes 34 and 35 were set to 22.5 mm, respectively.

Then, the heat input due to electroslag welding was calculated for calculation example No. 3A using the same method as calculation examples No. 1 to 3. The calculation results are also shown in Table 2.

As can be seen from calculation example No. 3A in Table 2, by dividing the electroslag welding hole into two welding holes 34, 35 by partition 33 and applying electroslag welding to each of the welding holes 34, 35, the heat input is reduced to the same level as calculation example No. 1 in Table 1. In other words, it was confirmed that by dividing the electroslag welding hole into two welding holes 34, 35 by partition 33 and applying electroslag welding to each of the welding holes 34, 35, a significant decrease in the toughness of the welded portion 5 can be suppressed.

1 Square steel pipe column 1c Corner 2 H-shaped steel beam 21 Flange 22 Web 3, 3A to 3C External diaphragm 31 Backing metal 32, 34, 35 Welding hole 33 Partition wall 4 Filling material w ₀ to w ₂ Width of welding hole 5 Welded part D _c Outer diameter of square steel pipe column t _c Wall thickness of square steel pipe column t _d Plate thickness of external diaphragm h _d Projecting width of external diaphragm G Root spacing B Thickness of partition wall 81 Square steel pipe column 81c Corner 82 H-shaped steel beam 821 Flange 83 External diaphragm 83h Projecting width of external diaphragm 84 Internal diaphragm 85 Through diaphragm 86 to 89 Welded part

Claims (10)

A joint structure between a square steel pipe column and an H-shaped steel beam, in which an H-shaped steel beam is joined to a square steel pipe column via an external diaphragm,
A joining structure between a square steel pipe column and an H-shaped steel beam, in which a welding hole surrounded by a metal is provided between the side surface of the square steel pipe column and the end face of the external diaphragm, and the square steel pipe column and the external diaphragm are joined by a weld formed by filling the welding hole with molten metal by electroslag welding. The outer diaphragm is extended to the corner of the square steel pipe column,
The corners of the square steel pipe column have a radius, and a filler made of a steel plate is provided in the gap between the corners and the outer diaphragm caused by the radius,
The connection structure between a square steel pipe column and an H-shaped steel beam as described in claim 1, wherein the welding hole extends linearly from the side of the square steel pipe column to the side of the filling material. The joining structure of a square steel pipe column and an H-shaped steel beam according to claim 1 or 2, in which a partition wall made of a steel piece is provided inside the welding hole so that the welding hole is divided into two or more holes in the thickness direction of the outer diaphragm. The joint structure between a square steel pipe column and an H-shaped steel beam according to claim 1 or 2, in which the yield strength of the outer diaphragm is greater than the yield strength of the flange of the H-shaped steel beam. The joint structure between a square steel pipe column and an H-shaped steel beam according to claim 3, wherein the yield strength of the outer diaphragm is greater than the yield strength of the flange of the H-shaped steel beam. A manufacturing method for a joint structure between a square steel pipe column and an H-shaped steel beam, in which an H-shaped steel beam is joined to a square steel pipe column via an external diaphragm,
A manufacturing method for a joint structure of a square steel pipe column and an H-shaped steel beam, comprising: providing a welding hole by surrounding the area between the side surface of the square steel pipe column and the end face of the outer diaphragm with a metal strip; filling the welding hole with molten metal by electroslag welding with a heat input of 100 to 1500 kJ/cm to form a weld, thereby joining the square steel pipe column and the outer diaphragm. The outer diaphragm is extended to a corner of the square steel pipe column, and the corner of the square steel pipe column has a radius,
The manufacturing method of the joint structure of a square steel pipe column and an H-shaped steel beam as described in claim 6, wherein a filler material made of a steel plate is provided in the gap created between the outer diaphragm by the curve, so that the welding hole is extended linearly from the side of the square steel pipe column to the side of the filler material. The method for manufacturing a joint structure between a square steel pipe column and an H-shaped steel beam according to claim 6 or 7, in which a partition made of a steel piece is provided inside the welding hole so that the welding hole is divided into two or more holes in the thickness direction of the outer diaphragm. The manufacturing method for a joint structure between a square steel pipe column and an H-shaped steel beam according to claim 6 or 7, wherein the yield strength of the outer diaphragm is greater than the yield strength of the flange of the H-shaped steel beam. The manufacturing method for a joint structure between a square steel pipe column and an H-shaped steel beam according to claim 8, wherein the yield strength of the outer diaphragm is greater than the yield strength of the flange of the H-shaped steel beam.

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