Joint structure of column, flat beam and orthogonal beam

Abstract

To provide a joint structure of a column, a flat beam and an orthogonal beam capable of suppressing torsional deformation which may be generated in an overhang part of the flat beam while reducing the amount of reinforcing bars required for reinforcing the overhang part as much as possible.SOLUTION: In a joint structure 200 of a column, a flat beam, and an orthogonal beam, a reinforced concrete-made column 10, a reinforced concrete-made flat beam 20 overhanging from the column 10 to its periphery, and a reinforced concrete-made orthogonal beam 30 orthogonal to the flat beam 20 are joined; in the overhang 25 in the area where the orthogonal beam 30 does not extend out of the flat beam 20, the beam main reinforcement 40 of the orthogonal beam 30 extends out, and at least a plurality of beam main reinforcing bars 40 are surrounded by square-shaped torsion reinforcing bars 50,55 in the overhang part 25.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a joint structure between a column, a flat beam, and an orthogonal beam. [Background technology]

[0002] When attempting to lower the beam depth from the viewpoint of effective use of indoor space, the performance of the beam declines, and so in order to compensate for this decline in performance, construction is sometimes carried out in which the beam width is made wider than the column width, and beams with a width wider than the column width in this way are called flat beams or wide beams. In apartment buildings, etc., installing flat beams on the balcony side can create open spaces and add value to the building, and in areas with height restrictions, applying flat beams to each floor can lower the overall height of the building, making it possible to construct buildings with a specified number of floors, so the effects of applying flat beams are extremely high.

[0003] Here, Patent Document 1 proposes a joint structure between a column and a flat beam. Specifically, the joint structure relates to a column and a flat beam having a beam width wider than the column width, in which a plurality of first reinforcing bars, each divided into two and U-shaped, are fixed to the beam main reinforcing bars on the inside of the column width so as to surround a plurality of main beam reinforcing bars arranged in the flat beam, and a U-shaped second reinforcing bar consisting of a linear base and two feet is arranged on the outside of the column width of the flat beam from the flush outer surface side toward the inside of the flat beam, and the two feet are fixed to the first reinforcing bars. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-85188 Summary of the Invention [Problem to be solved by the invention]

[0005] According to the joint structure between a column and a flat beam described in Patent Document 1, the rigidity of the protruding portion of the flat beam is increased by the U-shaped reinforcing bars placed in the protruding portion of the flat beam that protrudes further to the side than the width of the column.

[0006] In a joint where a column and a flat beam are joined and an orthogonal beam perpendicular to the flat beam is further joined, when a horizontal force acts on the column during an earthquake, a specific internal force can be generated in the overhanging part of the flat beam, which is the area along the longitudinal direction of the orthogonal beam on the side (outside) of the column. This will be explained with reference to Figures 1 and 2.

[0007] Figure 1 is an oblique view illustrating the state in which horizontal force H acts on column 10 in a conventional joint structure 100 between a column, a flat beam, and an orthogonal beam during an earthquake, and Figure 2 is a diagram illustrating the internal forces acting on each part by disassembling column 10, flat beam 20, and orthogonal beam 30 in the joint structure 100 between a column, a flat beam, and an orthogonal beam shown in Figure 1.

[0008] The joint structure 100 shown in Fig. 1 is a joint structure between a reinforced concrete column 10, a reinforced concrete flat beam 20 that has a width B2 wider than the column width B1, a height h1, and extends in the X1 direction, and a flat orthogonal beam 30 that has a width B3 approximately the same as (or the same width as) the flat beam 20, a height h1 similar to that of the flat beam 20, and extends in the X2 direction perpendicular to the X1 direction. Here, the illustration of the column main reinforcement in the cross section of the column 10 is omitted.

[0009] Of the flat beam 20, a region of width B3 on the side of the column 10 in the extension direction of the orthogonal beam 30 becomes the protruding portion 25. Here, instead of width B3, a region of width B1 of the column 10 may be the protruding portion.

[0010] As shown in Figure 2, at each interface when the column 10, flat beam 20, and orthogonal beam 30 are disassembled, a bending moment M1 and a shear force S1 act on the interface between the column 10 and flat beam 20 in front of the direction of action of the horizontal force H, and a bending moment M2 and a shear force S2 act on the interface between the column 10 and flat beam 20 in the rear of the direction of action of the horizontal force H. These bending moments M1 and M2 can be resisted by the upper end main reinforcement and the lower end main reinforcement (neither shown) of the flat beam 20, which extend in the X1 direction, which is the longitudinal direction of the flat beam 20, and penetrate the column 10.

[0011] On the other hand, torsional moments T1 and T2 caused by bending moments M1 and M2 act on the interface between the column 10 and the overhanging portion 25, causing deformation in the Z direction, which is the vertical direction, in the overhanging portion 25. However, it is difficult to suppress these torsional moments T1 and T2 and the vertical deformation caused by the torsional moments T1 and T2 (torsional deformation caused by the torsional moments). Furthermore, even if the U-shaped reinforcing bars described in Patent Document 1 are applied, it remains difficult to suppress torsional deformation because the reinforcing bars do not extend in a direction that suppresses the vertical deformation caused by the torsional moments T1 and T2.

[0012] Furthermore, in Patent Document 1, the reinforcement arrangement is such that U-shaped reinforcing bars and restraining bars are placed in the protruding section, which requires a large number of reinforcing bars and a large amount of reinforcing bars to reinforce the protruding section, and it is undeniable that the construction work is time-consuming.

[0013] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a joint structure between a column, a flat beam, and an orthogonal beam that can suppress torsional deformation that may occur in the protruding portion while reducing the amount of steel bars required to reinforce the protruding portion of the flat beam as much as possible. [Means for solving the problem]

[0014] In order to achieve the above object, one aspect of the joint structure of a column, a flat beam, and an orthogonal beam according to the present invention is as follows: A joint structure of a column, a flat beam, and an orthogonal beam, in which a column made of reinforced concrete, a flat beam made of reinforced concrete extending from the column to its periphery, and a reinforced concrete orthogonal beam perpendicular to the flat beam are joined, In the flat beam, the main beam reinforcement of the orthogonal beam extends to the protruding portion in the region where the orthogonal beam does not extend, In the protruding portion, at least a plurality of the main beam reinforcements are surrounded by square-shaped twist reinforcement bars.

[0015] According to this aspect, the main beam reinforcement of the orthogonal beam extends to the protruding portion in the area of ​​the flat beam where the orthogonal beam does not extend, and at least a plurality of the main beam reinforcement is surrounded by L-shaped torsional reinforcement in the protruding portion. As a result, only L-shaped torsional reinforcement is added, and therefore the amount of steel required to reinforce the protruding portion can be reduced as much as possible while suppressing torsional deformation that may occur in the protruding portion of the flat beam.

[0016] Here, "at least a plurality of beam main reinforcements are surrounded by square-shaped torsional reinforcement" means the following: In other words, when the orthogonal beam is a flat orthogonal beam with a height similar to that of a flat beam, it includes a configuration in which the upper and lower main reinforcement bars of the orthogonal beam extend to the protruding portion and are surrounded by torsional reinforcement. Here, the number of torsional reinforcement bars may be one or more, as needed.

[0017] In another embodiment, when the orthogonal beam is taller than the flat beam, the upper main reinforcements of the orthogonal beam extend to the overhanging portion, but the lower main reinforcements cannot extend to the overhanging portion because they are located below the underside of the overhanging portion. Therefore, in order to arrange square-shaped torsional reinforcement in the overhanging portion, a constructional reinforcement is arranged in the overhanging portion at a position below the upper main reinforcement, and the torsional reinforcement surrounds the upper main reinforcement and the constructional reinforcement.

[0018] Another aspect of the joint structure of a column, a flat beam, and an orthogonal beam according to the present invention is as follows: The orthogonal beam and the flat beam have the same beam depth, The beam main reinforcement includes an upper end main reinforcement and a lower end main reinforcement, The upper end main reinforcement and the lower end main reinforcement extend to the protruding portion, In the protruding portion, the torsional reinforcement bars surround a plurality of the upper end main reinforcements and the lower end main reinforcements.

[0019] According to this embodiment, in a flat configuration in which the orthogonal beam has the same beam depth as the flat beam, the upper and lower main reinforcements of the orthogonal beam extending to the protruding portion of the flat beam are surrounded by L-shaped torsional reinforcement bars, thereby making it possible to suppress torsional deformation that may occur in the protruding portion of the flat beam while reducing the amount of steel bars required to reinforce the protruding portion as much as possible.

[0020] Another aspect of the joint structure of a column, a flat beam, and an orthogonal beam according to the present invention is as follows: In the orthogonal beam, the upper end main reinforcement bars and the lower end main reinforcement bars are surrounded by a plurality of shear reinforcement bars having the same square shape as the torsional reinforcement bars.

[0021] According to this aspect, steel bars of the same standard, name and shape can be applied to the torsional reinforcement in the overhanging section and the shear reinforcement in the orthogonal beam, thereby preventing incorrect reinforcement placement and enabling efficient reinforcement placement work.

[0022] In another aspect of the joint structure of a column, a flat beam, and an orthogonal beam according to the present invention, The orthogonal beams have a beam depth greater than that of the flat beams, The beam main reinforcement includes an upper end main reinforcement and a lower end main reinforcement, The upper end main reinforcement extends to the overhanging portion, A plurality of assembly reinforcements parallel to the upper end main reinforcement are arranged in the protruding portion, In the protruding portion, the torsional reinforcement bars surround the plurality of upper end main reinforcements and the assembly reinforcements.

[0023] According to this aspect, when the orthogonal beam has a greater beam depth than the flat beam, the upper main reinforcements of the orthogonal beam extend to the overhanging portion, but the lower main reinforcements are located below the underside of the overhanging portion and therefore cannot extend to the overhanging portion. Therefore, by arranging the assembly reinforcement at a position below the upper main reinforcements in the overhanging portion, it is possible to arrange the torsional reinforcement so as to surround the upper main reinforcements and the assembly reinforcement. This makes it possible to suppress torsional deformation that may occur in the overhanging portion of the flat beam while minimizing the amount of reinforcing bars required to reinforce the overhanging portion as much as possible.

[0024] Another aspect of the joint structure of a column, a flat beam, and an orthogonal beam according to the present invention is as follows: In the orthogonal beam, the upper end main reinforcements and the lower end main reinforcements are surrounded by square-shaped shear reinforcements that are larger than the torsional reinforcements.

[0025] According to this embodiment, in the orthogonal beam, which is taller than the flat beam, the multiple upper and lower main reinforcements of the orthogonal beam are surrounded by square-shaped shear reinforcement bars that are larger than the torsional reinforcement bars, thereby forming a joint structure with an orthogonal beam having high shear rigidity and a flat beam having high torsional rigidity.

[0026] Another aspect of the joint structure of a column, a flat beam, and an orthogonal beam according to the present invention is as follows: The present invention is characterized in that a plurality of the torsional reinforcement bars are arranged in the protruding portion.

[0027] According to this aspect, by arranging multiple torsional reinforcement bars in the protruding portion, a joint structure can be formed having a flat beam with a protruding portion having high torsional rigidity.

[0028] In another aspect of the joint structure of a column, a flat beam, and an orthogonal beam according to the present invention, The beam main reinforcement is characterized in that it has a bent portion formed by bending at its end portion.

[0029] According to this aspect, the main beam reinforcement has a bent portion formed at its end by bending processing, so that the required anchorage length of the main beam reinforcement extending to the protruding portion can be secured by the bent portion, and anchorage of the main beam reinforcement at the protruding portion with the desired pull-out strength can be achieved. [Effects of the Invention]

[0030] As can be understood from the above explanation, the joint structure of the column, flat beam, and orthogonal beam of the present invention can suppress torsional deformation that may occur in the protruding portion while reducing the amount of steel bars required to reinforce the protruding portion of the flat beam as much as possible. [Brief explanation of the drawings]

[0031] [Figure 1] FIG. 1 is a perspective view illustrating a state in which a horizontal force during an earthquake acts on a column in a conventional joint structure of a column, a flat beam, and an orthogonal beam. [Figure 2] 2 is a diagram illustrating the internal forces acting on each part of the joint structure of the column, flat beam, and orthogonal beam shown in FIG. 1, with the column, flat beam, and orthogonal beam disassembled. FIG. [Figure 3] FIG. 2 is a perspective view showing an example of a joint structure between a column, a flat beam, and an orthogonal beam according to the first embodiment, showing the main beam reinforcement bars and the torsional reinforcement bars. [Figure 4] 4 is a view seen in the direction of an arrow IV in FIG. 3, showing the main beam reinforcement bars, the torsional reinforcement bars, and the shear reinforcement bars seen from above. [Figure 5] 4 is a view seen in the direction of the arrow V in FIG. 3, showing the main beam reinforcement bars and the torsional reinforcement bars seen from the side. [Figure 6] FIG. 10 is a perspective view showing an example of a joint structure between a column, a flat beam, and an orthogonal beam according to the second embodiment, showing the main beam reinforcement bars and the torsional reinforcement bars. [Figure 7] 7 is a view seen in the direction of arrow VII in FIG. 6, showing the main beam reinforcement bars, the torsional reinforcement bars, and the shear reinforcement bars seen from above. [Figure 8] 8 is a view seen in the direction of arrow VIII in FIG. 6, showing the main beam reinforcement bars and the torsional reinforcement bars seen from the side. DETAILED DESCRIPTION OF THE INVENTION

[0032] Hereinafter, an example of a joint structure between a column, a flat beam, and an orthogonal beam according to each embodiment will be described with reference to the accompanying drawings. Note that in this specification and the drawings, substantially identical components may be designated by the same reference numerals to avoid redundant description.

[0033] [First embodiment of the joint structure between a column, a flat beam, and an orthogonal beam] First, an example of a joint structure between a column, a flat beam, and an orthogonal beam according to the first embodiment will be described with reference to Fig. 3 to Fig. 5. Here, Fig. 3 is a perspective view showing an example of a joint structure between a column, a flat beam, and an orthogonal beam according to the first embodiment, and is a view showing the main beam reinforcement bars and torsional reinforcement bars. Also, Fig. 4 is a view taken in the direction of arrow IV in Fig. 3, showing the main beam reinforcement bars, torsional reinforcement bars, and shear reinforcement bars seen from above, and Fig. 5 is a view taken in the direction of arrow V in Fig. 3, showing the main beam reinforcement bars and torsional reinforcement bars seen from the side.

[0034] The joint structure 200 between a column, a flat beam, and an orthogonal beam is a joint structure between a reinforced concrete column 10, a reinforced concrete flat beam 20 that has a width B2 wider than the column width B1, a height h1, and extends in the X1 direction, and a flat orthogonal beam 30 that has a width B3 similar to that of the flat beam 20, a height h1 similar to that of the flat beam 20, and extends in the X2 direction perpendicular to the X1 direction. Here, the illustration of the column main reinforcement in the cross section of the column 10 is omitted.

[0035] Of the flat beam 20, the region of width B3 on both sides in the X2 direction, which is the extension direction of the orthogonal beam 30 in the column 10 (the region surrounded by the dotted line in FIG. 3) becomes the protruding portion 25. Here, instead of the width B3, the region of width B1 of the column 10 may be the protruding portion.

[0036] As already explained with reference to Figure 2, torsional moments T1 and T2 caused by bending moments M1 and M2 act on this protruding portion 25, and torsional deformation in the Z direction, which is the vertical direction, due to torsional moments T1 and T2 can occur.

[0037] The beam main reinforcements 40 of the flat orthogonal beam 30 include a plurality of upper end main reinforcements 40A, 40B and a plurality of lower end main reinforcements 45A, 45B. Here, the upper end main reinforcements 40A and the lower end main reinforcements 45A are beam main reinforcements arranged relatively inward, while the upper end main reinforcements 40B and the lower end main reinforcements 45B are beam main reinforcements arranged relatively outward. In reality, there are also upper end main reinforcements and lower end main reinforcements passing through the interior of the column 10, but to make the drawing easier to understand, these beam main reinforcements are omitted from Fig. 3. Furthermore, the shear reinforcement of the orthogonal beam 30 is also omitted from Fig. 3.

[0038] Each main beam reinforcement 40 of the orthogonal beam 30 passes through the protruding portion 25 of the flat beam 20, passes along the side of the column 10 (the main beam reinforcement not shown passes through the inside of the column 10), and further extends to the outer protruding portion 25. At the end of each main beam reinforcement 40, bending portions 42, 47 are provided.

[0039] By having the bent parts 42, 47 at the ends of the beam main reinforcement 40, the required anchorage length for the beam main reinforcement 40 extending to the outer overhanging part 25 can be ensured by the bent parts 42, 47, and the beam main reinforcement 40 with the desired pull-out resistance can be anchored in the overhanging part 25. Here, if the desired pull-out resistance is achieved even without the bent parts 42, 47, the bent parts 42, 47 may be unnecessary.

[0040] In the two overhanging portions 25, a plurality of upper end main reinforcements 40A, 40B and lower end main reinforcements 45A, 45B are surrounded by a plurality of square-shaped torsional reinforcements 50, 55.

[0041] More specifically, a plurality of upper end main reinforcements 40A and a plurality of lower end main reinforcements 45A, which are arranged relatively inward, are surrounded by a plurality of L-shaped torsional reinforcements 50, which have relatively small dimensions when viewed from the front, and a plurality of upper end main reinforcements 40B and a plurality of lower end main reinforcements 45B, which are arranged relatively outward, are surrounded by a plurality of L-shaped torsional reinforcements 55, which have relatively large dimensions when viewed from the front.

[0042] Due to their shape and arrangement, the square-shaped torsional reinforcement bars 50, 55 effectively act against torsional deformation in the Z direction, which is the vertical direction in the protruding portion 25, and suppress the torsional deformation.

[0043] Here, in Figures 3 and 4, for ease of understanding, each bending section 42, 47 is shown slightly offset, and the two types of torsional reinforcement bars 50, 55 are also shown slightly offset, but if they do not interfere with each other, they may be arranged in a position where they overlap each other when viewed from the top or side.

[0044] As shown in Figure 4, the orthogonal beam 30 has two types of square-shaped torsional reinforcement bars 50, 55 arranged in the protruding portion 25, and shear reinforcement bars 60, 65 of the same standard, name, and shape, surrounding a corresponding plurality of upper end main reinforcements 40A and lower end main reinforcements 45A, and a corresponding plurality of upper end main reinforcements 40B and lower end main reinforcements 45B, respectively.

[0045] According to the joint structure 200, the main beam reinforcement 40 of the orthogonal beam 30 extends to the protruding portion 25 (outer protruding portion 25) in the area of ​​the flat beam 20 where the orthogonal beam 30 does not extend, and at least a plurality of the main beam reinforcement 40 are surrounded by L-shaped torsional reinforcement bars 50, 55 in the protruding portion 25. As a result, only the L-shaped torsional reinforcement bars 50, 55 are added, and therefore, the amount of steel bars required to reinforce the protruding portion 25 can be reduced as much as possible while suppressing torsional deformation that may occur in the protruding portion 25 of the flat beam 20.

[0046] In addition, by using steel bars of the same standard, name and shape for the torsional reinforcement bars 50, 55 in the protruding portion 25 and the shear reinforcement bars 60, 65 in the orthogonal beam 30, incorrect reinforcement can be prevented and efficient reinforcement work can be achieved.

[0047] [Second embodiment of the joint structure between a column, a flat beam, and an orthogonal beam] Next, an example of a joint structure between a column, a flat beam, and an orthogonal beam according to the second embodiment will be described with reference to Fig. 6 to Fig. 8. Fig. 6 is a perspective view showing an example of a joint structure between a column, a flat beam, and an orthogonal beam according to the second embodiment, in which the main beam reinforcement bars and the torsional reinforcement bars are seen through. Fig. 7 is a view taken in the direction of arrow VII in Fig. 6, in which the main beam reinforcement bars, the torsional reinforcement bars, and the shear reinforcement bars are seen through from above, and Fig. 8 is a view taken in the direction of arrow VIII in Fig. 6, in which the main beam reinforcement bars and the torsional reinforcement bars are seen through from the side.

[0048] The joint structure 300 of a column, a flat beam, and an orthogonal beam differs from the joint structure 200 in that the orthogonal beam 30A has a beam depth h2 that is higher than the beam depth h1 of the flat beam 20.

[0049] Since the orthogonal beam 30A is taller than the flat beam 20, the upper end main reinforcements 40C of the orthogonal beam 30A extend to the outer protruding portion 25 and their bent portions 42 are fixed, whereas the lower end main reinforcements 45C are located below the underside of the outer protruding portion 25 and therefore cannot extend to the protruding portion 25.

[0050] Therefore, in the overhanging part 25, assembly reinforcement 48 is arranged at a position below the upper end main reinforcement 40C, and the bent part 49 at the end of the assembly reinforcement 48 is fixed to the outer overhanging part 25. Then, in each of the two overhanging parts 25, a plurality of upper end main reinforcement 40C and a plurality of assembly reinforcement 48 are surrounded by a plurality of square-shaped torsional reinforcement 58.

[0051] Due to its shape and arrangement, the square-shaped torsional reinforcement bars 58 effectively act against torsional deformation in the Z direction, which is the vertical direction in the protruding portion 25, and suppress the torsional deformation.

[0052] The lower end main reinforcement 45C of the orthogonal beam 30A extends to the inside of the column 10, and the bent portion 47 at the end of the lower end main reinforcement 45C is arranged so as to extend downward of the column 10.

[0053] As shown in Figure 7, in the orthogonal beam 30A, square-shaped shear reinforcement 68, which is larger than the square-shaped torsional reinforcement 58 arranged in the protruding portion 25, surrounds multiple upper end main reinforcements 40C and lower end main reinforcements 45C.

[0054] According to the joint structure 300, the main beam reinforcement 40 of the orthogonal beam 30A extends to the protruding portion 25 (outer protruding portion 25) in the area of ​​the flat beam 20 where the orthogonal beam 30A does not extend, and at least a plurality of the main beam reinforcement 40 are surrounded by L-shaped torsional reinforcement bars 58 in the protruding portion 25.Since only the L-shaped torsional reinforcement bars 58 are added, the amount of steel bars required to reinforce the protruding portion 25 can be reduced as much as possible while suppressing torsional deformation that may occur in the protruding portion 25 of the flat beam 20.

[0055] The present invention is not limited to the configurations shown here, and other embodiments may be possible in which other components are combined with the configurations described in the above embodiments. In this regard, the present invention can be modified within the scope of the present invention, and can be appropriately determined depending on the application form. [Explanation of symbols]

[0056] 10: Pillar 20: Flat beam 25: Protruding part 30, 30A: Orthogonal beam 40: Beam main reinforcement 40A, 40B: Top main reinforcement 42: Bent section 45A, 45B: Bottom main reinforcement 47: Bent section 48: Assembly muscles 49: Bent section 50, 55, 58: Torsion reinforcement 60, 65, 68: Shear reinforcement 200, 300: Joint structure of column, flat beam and perpendicular beam (joint structure) H:Horizontal force M1, M2: Bending moment S1, S2: Shear force T1, T2: Torsional moment

Claims

1. A joint structure of a column, a flat beam, and an orthogonal beam, in which a column made of reinforced concrete, a flat beam made of reinforced concrete extending from the column to its periphery, and a reinforced concrete orthogonal beam perpendicular to the flat beam are joined, In the flat beam, the main beam reinforcement of the orthogonal beam extends to the protruding portion in the region where the orthogonal beam does not extend, A joint structure between a column, a flat beam, and an orthogonal beam, characterized in that in the protruding portion, at least a plurality of the main beam reinforcements are surrounded by square-shaped torsional reinforcement bars.

2. The orthogonal beam and the flat beam have the same beam depth, The beam main reinforcement includes an upper end main reinforcement and a lower end main reinforcement, The upper end main reinforcement and the lower end main reinforcement extend to the protruding portion, 2. The joint structure of a column, a flat beam, and an orthogonal beam according to claim 1, wherein the torsional reinforcement bars surround the upper end main reinforcements and the lower end main reinforcements in the protruding portion.

3. The joint structure of a column, a flat beam, and an orthogonal beam described in claim 2, characterized in that in the orthogonal beam, the plurality of upper end main reinforcements and the lower end main reinforcements are surrounded by a plurality of shear reinforcement bars in the same square shape as the torsional reinforcement bars.

4. The orthogonal beams have a beam depth greater than that of the flat beams, The beam main reinforcement includes an upper end main reinforcement and a lower end main reinforcement, The upper end main reinforcement extends to the overhanging portion, A plurality of assembly reinforcements parallel to the upper end main reinforcement are arranged in the protruding portion, 2. The joint structure of a column, a flat beam, and an orthogonal beam according to claim 1, wherein the torsional reinforcement bars surround the upper end main reinforcements and the assembly reinforcements in the protruding portion.

5. 5. The joint structure of a column, a flat beam, and an orthogonal beam according to claim 4, characterized in that in the orthogonal beam, a plurality of the upper end main reinforcements and the lower end main reinforcements are surrounded by square-shaped shear reinforcement bars that are larger than the torsional reinforcement bars.

6. The joint structure of a column, a flat beam, and an orthogonal beam according to any one of claims 1 to 5, characterized in that a plurality of the torsional reinforcement bars are arranged in the overhanging portion.

7. 7. The joint structure of a column, a flat beam, and an orthogonal beam according to claim 1, wherein the main beam reinforcement has a bent portion formed by bending at its end.

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