Building unit column structure

Abstract

To provide a column structure of a building unit capable of setting the column freely while reducing labor and cost and capable of storing the column in an intermediate wall.SOLUTION: An outer wall WO dividing a living room RM of a building unit U1 and a garage GA is provided without having a lower side short girder 20a to be projected from a wall surface. A hollow column 40 is connected to an upper surface of a tip of the lower side short girder 20a and a lower surface of a roof girder 10a and provided inside of the outer wall WO. The hollow column 40 comprises an upper side end plate 41 and a lower side end plate 42. The lower side end plate 42 is in a dimension not projecting from the outer wall WO to the garage GA side and is fastened to an upper surface of the lower side short girder 20a by a bolt 101 and a nut 102. In addition, an insertion hole 42a fastening the lower side end plate 42 is provided in a hollow part of the hollow column 40.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a column structure for a building unit. [Background technology]

[0002] Conventionally, building units for constructing a unit building are known to be constructed by welding steel beams to the upper and lower ends of four steel columns arranged upright at the four corners of a rectangle (for example, Patent Document 1).

[0003] Furthermore, in such prior art, when connecting a column and a beam, it is common to connect the beam to the side of the upper and lower ends of the column, a so-called column-first connection. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-031220 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned conventional technology, the positions of the pillars are fixed to the four corners of the building unit, and if the positions of the pillars are to be set arbitrarily depending on the layout of the rooms, etc., the length and shape of the beams cannot be made constant, which requires effort and cost in manufacturing.

[0006] Furthermore, the interior of a building unit may be divided by intermediate walls, and in such cases, providing columns to ensure the rigidity of the intermediate walls would require dedicated columns, which would increase the effort and cost. When providing intermediate walls in this way, it is preferable that the columns that maintain the strength of the intermediate walls are located within the intermediate walls. Furthermore, if one side of the intermediate walls is exposed to the outside and the floor girders are only extended up to the intermediate wall, it is also preferable that the floor girders do not protrude to one side of the intermediate walls.

[0007] Therefore, the present disclosure aims to provide a column structure for a building unit that allows for increased flexibility in column configuration while reducing effort and cost, and that enables columns to be placed within intermediate walls. [Means for solving the problem]

[0008] The column structure of a building unit of the present disclosure is a column structure of a building unit formed by connecting an upper girder and a lower girder that face each other vertically with a column, wherein an intermediate wall that divides the interior of the building unit into an occupancy space and a non-occupancy space is provided in the middle of the building unit, the lower girder is provided with a lower short girder that is formed to a length from one end of the building unit to the position of the intermediate wall, and the column includes a hollow cylindrical hollow column that is provided inside the intermediate wall and is connected to the upper surface of the tip of the lower short girder and the lower surface of the upper girder that faces the upper surface, and the hollow column has upper end plates and lower end plates at its upper and lower ends. the upper end plate is fastened to the underside of the upper girder with fastening members, the lower end plate is sized so as not to protrude from the intermediate wall into the non-habitable space and is fastened to the upper surface of the lower short girder with fastening members, the fastening points of the lower end plate by the fastening members are provided within the hollow portions of the hollow columns, holes for inserting the fastening members are opened in the hollow columns, a mounting plate is provided at a position inside the unit of the upper girder at the position where the intermediate wall is installed, and an auxiliary beam for attaching the intermediate wall and a ceiling material for attaching a ceiling board are hung on the mounting plate. [Effects of the Invention]

[0009] In the column structure of the building unit of the present disclosure, the hollow column is a beam-supported structure in which the upper end plate is connected to the underside of the upper girder and the lower end plate is connected to the top of the lower short girder, thereby improving the flexibility of column design while reducing effort and cost. Also, because the lower end plate is fastened within the hollow of the hollow column, the hollow column can be placed within an intermediate wall without the lower end plate protruding from the lower short girder. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view showing an outline of a building unit U1 to which the column structure of the building unit of the first embodiment is applied. [Figure 2] FIG. 10 is a side view showing the structure of a hollow column 30 in the building unit U1. [Figure 3] 3 is a cross-sectional view showing the structure of the main part of the hollow column 30. FIG. [Figure 4] FIG. 10 is a side view showing the structure of a hollow column 40 in the building unit U1. [Figure 5] 10A and 10B are diagrams showing the connection structure of the upper end of the hollow column 40, where (a) is a side view seen from the direction of the short side of the unit, (b) is a cross-sectional view at the position of the Sb-Sb line in (a), and (c) is a cross-sectional view at the position of the Sc-Sc line in (a). [Figure 6] 1A and 1B are diagrams showing the connection structure of the lower end of the hollow column 40, in which (a) is a side view seen from the direction of the short side of the unit, and (b) is a cross-sectional view seen from the direction of the long side of the unit. [Figure 7] FIG. 10 is a side view showing the column structure of the building unit of the second embodiment. [Figure 8] FIG. 8 is an enlarged view of a main part of FIG. 7. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. (Embodiment 1) The column structure of the building unit of the first embodiment is applied to the building unit U1 shown in FIG.

[0012] (Outline of building unit) The building unit U1 shown in Figure 1 is used to construct a unit building (not shown), and is a unit used in particular to divide the interior of the unit into a living room RM and a garage GA. In the following description, the direction of arrow LS in the figure, which is along the long side of the building unit U1, will be referred to as the unit long side direction, the direction of arrow SS, which is along the short side of the building unit U1, will be referred to as the unit short side direction, the direction of arrow UP as the upward direction, and the direction of arrow DN as the downward direction. Furthermore, when constructing a unit building, other building units different from the building unit U1, such as the units described in Patent Document 1, can be used.

[0013] The building unit U1 comprises an upper frame 10, a lower frame 20, and a plurality of hollow columns 30, 40, 50.

[0014] The upper frame 10 is formed in a rectangular frame shape by welding together a pair of roof girders 10a, 10a extending in the direction of the long sides of the unit and roof girders 10b, 10b extending in the direction of the short sides of the unit. As shown in Figures 5(b) and 5(c), the roof girders 10a are formed from C-shaped steel material having an upper flange 13 and a lower flange 11 above and below the web 12.

[0015] Returning to FIG. 1, the lower frame 20 is formed in a rectangular frame shape by welding together a pair of lower short girders 20a, 20a extending in the unit long-side direction and floor girders 20b, 20b extending in the unit short-side direction. Since the building unit U1 is divided into a living room RM and a garage GA as described above, the lower short girders 20a, 20a are formed to be approximately half the length of the roof girders 10a, 10a, and the lower frame 20 is formed to be approximately half the size of the upper frame 10. Furthermore, as shown in FIG. 3, the lower short girders 20a are formed of a C-shaped steel member having an upper flange 23 and a lower flange 21 above and below a web 22.

[0016] Returning to Figure 1, the hollow columns 30, 40, 50 are rectangular cylindrical hollow members made of metal that support the upper frame 10 from below, and are structural columns (structural columns) with the required strength. The hollow columns 30, 40 also have the function of connecting the upper frame 10 and the lower frame 20, and as will be described in detail later, they are connected to the underside of the upper frame 10 and the top side of the lower frame 20, forming a so-called beam-type connection structure.

[0017] The dimension of the short side of each of the hollow columns 30, 40, 50 in the rectangular cylindrical shape is slightly smaller than the width of each of the girders 10a, 10b, 20a, 20b. Therefore, when a wall is provided that spans the roof girders 10a, 10b and girders 20a, 20b of the building unit U1 in the vertical direction, each of the hollow columns 30, 40 can be contained within the wall.

[0018] Each hollow column 30, 40, 50 is provided with an upper end plate 31, 41, 51 and a lower end plate 32, 42, 52 for connection.

[0019] The connection structure of each of the hollow columns 30, 40, 50 will be explained below in order. (Connection structure of hollow column 30) As shown in FIG. 1, the hollow pillars 30 are provided at three locations near the corners of the upper frame 10 and the lower frame 20 at the end of the unit farther from the garage GA in the direction of the long side of the unit.

[0020] The upper end plate 31 and the lower end plate 32 of the hollow column 30 shown in Figure 2 are formed from a single steel plate with a thick plate thickness (for example, 4 to 6 mm), and the dimension in the unit long side direction is longer than the dimension in the same direction of the hollow column 30, and both ends protrude from the hollow column 30.

[0021] The upper end plate 31 abuts against the underside of the bottom flange 11 of the roof girder 10a and is fastened to the bottom flange 11 and a splice plate 61 (described later) with bolts 101 and nuts 102. The lower end plate 32 abuts against the top surface of the top flange 23 of the lower short girder 20a and is fastened to the top flange 23 and a splice plate 71 (described later) with bolts 101 and nuts 102.

[0022] Furthermore, reinforcing pieces 30a, 30b are provided on the outer periphery of the upper and lower ends of the hollow column 30. The reinforcing pieces 30a, 30b are formed from C-shaped steel plates that reinforce the upper and lower ends of the hollow column 30, and are joined to the outer periphery of the hollow column 30 and each end plate 31, 32 by welding.

[0023] Furthermore, in the roof girder 10a and the lower short girder 20a, at the fastening position of the hollow column 30, an upper stiffener 60 and a lower stiffener 70 are provided to transmit the stress in response to input from the hollow column 30 to each flange 11, 23 to the entire girder 10a, 20a.

[0024] The upper stiffener 60 comprises one splice plate 61 and two vertical plates 62, 62. The splice plate 61 is made of steel plate with the same thickness and external dimensions as the upper end plate 31, and is joined by welding to the upper surface of the lower flange 11 at the fastening position of the upper end plate 31. The vertical plates 62, 62 are formed from thin steel plates, and are joined by welding to the web 12, upper flange 13, and splice plate 61 so as to close the cross section of the roof girder 10a. The spacing between the vertical plates 62, 62 is approximately the same as the width dimension of the hollow column 30.

[0025] The lower stiffener 70 is similar to the upper stiffener 60 and includes one splice plate 71 and two vertical plates 72, 72. The splice plate 71 is formed from a steel plate with a thickness of about 4 to 6 mm, and is joined by welding to the underside of the upper flange 23 at the fastening position of the lower end plate 42. The vertical plates 72, 72 are formed from thin steel plates, and are joined by welding to the lower flange 21, web 22, and splice plate 71 so as to close the cross section of the lower short girder 20a.

[0026] The roof beams 10a, 10a are connected to ceiling joists. (ceiling material) A plurality of ceiling joists 14 are provided at intervals along the long side of the unit, and a ceiling surface material (not shown) is attached to the underside to form a ceiling surface.

[0027] Additionally, floor beams 17 are bridged across the lower short girders 20a, 20a in the direction of the short side of the unit. These floor beams 17 are attached via brackets 17a (see Figure 3), and a plurality of them are provided at intervals in the direction of the long side of the unit, with a floor surface material (not shown) attached to the upper side to form the floor surface FL (see Figures 4 and 6).

[0028] (Connection structure of hollow column 40) Next, we will explain the connection structure of the hollow column 40. Note that the column structure of the present disclosure is applied to the connection between this hollow column 40 and each of the girders 10a, 20a.

[0029] First, the unit structure at the installation position of the hollow column 40 will be described. As shown in Fig. 4, the hollow columns 40 are erected at positions where the exterior wall WO will be located, serving as a partition wall that divides the interior of the unit into an indoor living room RM and an outdoor garage GA. The tips of the lower short girders 20a are located inside the exterior surface of the exterior wall WO (see Fig. 1). That is, the tips of the lower short girders 20a are located inside the exterior wall WO so that the foundation 200, which is erected at the end of the garage GA, and the exterior wall WO are approximately flush with each other. The tips of the pair of lower short girders 20a, 20a are connected to the ends of the floor girders 20b (see Fig. 1).

[0030] Next, we will explain the hollow column 40. Similar to the hollow column 30, the hollow column 40 is provided with reinforcing pieces 40a, 40b at the upper and lower ends, an upper end plate 41, and a lower end plate 42. The reinforcing piece 40a has the same configuration as the reinforcing piece 30a described above, so its explanation will be omitted.

[0031] Like the upper end plate 31 of the hollow column 30 described above, the upper end plate 41 is abutted against the underside of the lower flange 11 of the roof girder 10a and fastened to the lower flange 11 and splice plate 61 by bolts 101 and nuts 102, as shown in Figure 5.

[0032] An upper stiffener 60 is provided at the position on roof girder 10a where upper end plate 41 is fastened.

[0033] 4 and 5, a mounting plate 500 is provided on the roof girders 10a, 10a at the position where the hollow column 40 is installed. Ceiling joists as ceiling materials 14 The auxiliary beam 520 is used to fix the roof girder 10a without interfering with the upper stiffener 60 or the upper end plate 41, and is formed from steel plate, with its upper and lower edge portions fixed by welding to the upper flange 13 and lower flange 11 of the roof girder 10a.

[0034] The mounting plate 500 is also provided with a ceiling material bracket 501 for fixing the end of the ceiling joist 14 and an auxiliary beam bracket 502 for fixing the end of the auxiliary beam 520.

[0035] The auxiliary beam 520 is formed of a channel steel material having a U-shaped cross section, and is used to attach the exterior wall WO.

[0036] Next, we will explain the joining structure of the lower end of the hollow column 40. The configurations of the lower end plate 42 and lower stiffener 570 used to join the lower end of this hollow column 40 are different from the configurations of the lower end plate 32 and lower stiffener 70 used to join the lower end of the hollow column 30.

[0037] The lower end plate 42 is formed from a steel plate with a thickness of about 4 to 6 mm and is welded to the lower end of the hollow column 40. The lower end plate 42 is provided so as not to protrude from the lower short girder 20a, and protrudes only in the direction away from the garage GA in the unit longitudinal direction, without protruding from the hollow column 40 on the garage GA side. Of the two insertion holes 42a, 42b for inserting bolts 101, the insertion hole 42a on the garage GA side is located in the hollow portion of the hollow column 40. In other words, the insertion hole 42a opens into the hollow portion of the hollow column 40.

[0038] The other insertion hole 42b is formed in the part of the lower end plate 42 that protrudes from the hollow column 40.

[0039] A circular work hole 43 is opened at the lower end of the hollow pillar 40. This work hole 43 is used when inserting the bolt 101 into the insertion hole 42a. The reinforcing piece 40b at the lower end of the hollow pillar 40 has a wide portion 40c whose opening width is widened from the middle to the upper part in the vertical direction so as not to block the work hole 43.

[0040] Next, a description will be given of the lower stiffener 570. The lower stiffener 570 includes a splice plate 571, a vertical plate 572, and a beam end plate 573.

[0041] The splice plate 571 is formed from a steel plate of the same thickness as the previously described splice plate 71, and its dimension in the unit longitudinal direction is approximately the same as that of the lower end plate 42. Furthermore, insertion holes 571a, 571b for inserting bolts 101 are formed so as to be positioned coaxially with the insertion holes 42a, 42b of the lower end plate 42. The splice plate 571 is joined by welding to the underside of the upper flange 23 of the lower short girder 20a.

[0042] The vertical plate 572 is joined by welding to the lower surface of the splice plate 571 and to the inner surfaces of the lower flange 21 and web 22 of the lower short girder 20a.

[0043] The beam end plate 573 also has the function of closing the opening at the tip of the lower short girder 20a, and also has the function of transmitting stress by pairing with the vertical plate 572 of the lower stiffener 570.

[0044] Therefore, the beam end plate 573 is formed in a shape that can close the opening at the tip of the lower short girder 20a. Then, it is welded in advance to one end face of the splice plate 571 while abutting against it. Furthermore, the splice plate 571 is formed with a chamfered portion 571c to strengthen the weld to the beam end plate 573. This makes it possible to make the weld strength between the splice plate 571 and the beam end plate 573 stronger than the bolt strength.

[0045] As described above, by forming the splice plate 571 and the beam end plate 573 as an integral part, the beam end plate 573 is positioned to close the opening at the tip of the lower short girder 20a when the splice plate 571 is welded to the upper flange 23. Furthermore, after the splice plate 571 is installed, the beam end plate 573 is welded to the web 22 and lower flange 21 of the lower short girder 20a.

[0046] (50 hollow column structure) Returning to Figure 1, the hollow column 50 will now be described. Compared to the hollow columns 30, 40, the legs of the hollow column 50 are extended downward by a distance equivalent to the height of the foundation 200, and a lower end plate 52 at the lower end is connected to the foundation 200. The lower end plate 52 is similar to the lower end plate 32 of the hollow column 30. An upper end plate 51 similar to the upper end plates 31, 41 of the hollow columns 30, 40 is provided at the top end of the hollow column 50, and is fastened to the bottom flange 11 of the roof girder 10b with bolts and nuts (not shown).

[0047] (Effects of the First Embodiment) The effects of the first embodiment are listed below. (1) The column structure of the building unit of embodiment 1 is formed by connecting roof girders 10a, 10b as upper girders and lower short girders 20a and floor girders 20b as lower girders, which face each other vertically, with hollow columns 30, 40, 50. An exterior wall WO is provided in the middle of the building unit U1 as an intermediate wall that partitions the interior of the building unit U1. The lower short girders 20a are formed to a length from one end of the building unit U1 to the position of the exterior wall WO.

[0048] The hollow columns 30, 40, and 50 include a hollow cylindrical column 40 that is connected to the upper surface of the tip of the lower short girder 20a and the underside of the roof girder 10a facing this upper surface and is provided inside the exterior wall WO. The hollow column 40 has an upper end plate 41 and a lower end plate 42 at its upper and lower ends. The upper end plate 41 is fastened to the underside of the roof girder 10a with fastening members such as bolts 101 and nuts 102. The lower end plate 42 is sized so as not to protrude from the exterior wall WO, and is fastened to the upper surface of the lower short girder 20a with bolts 101 and nuts 102. Furthermore, an insertion hole 42a for fastening the lower end plate 42 is provided within the hollow portion of the hollow column 40.

[0049] Therefore, the lower end plate 42 and its fastening partner, the lower short girder 20a, can be installed so as not to protrude from the wall surface of the exterior wall. In other words, if a hollow column 30 is used as the column at the tip of the lower short girder 20a, one end of the lower end plate 32 and the lower short girder 20a will protrude from the rising part of the foundation 200 and the wall surface of the exterior wall WO toward the garage GA, deteriorating the appearance quality and usability of the garage GA.

[0050] In contrast, in embodiment 1, the lower end plate 42 and the lower short girder 20a do not protrude beyond the rising portion of the foundation 200 and the wall surface of the exterior wall WO, resulting in high appearance quality and ease of use.

[0051] (2) In the column structure of the building unit of the first embodiment, the hollow column 40 has a work hole 43 for inserting the bolt 101. Therefore, even if a fastening point is provided inside the hollow column 40, fastening work can be performed.

[0052] Furthermore, in the first embodiment, the reinforcing piece 40b is provided to surround the hollow column 40 at the position where the work hole 43 is provided, so that the strength of the hollow column 40 can be ensured even when the work hole 43 is provided.

[0053] (3) The column structure of the building unit of embodiment 1 is provided with a lower stiffener 570 at the connection point of the lower end plate 42 of the lower short girder 20a, which transmits the stress in response to input from the hollow column 40 to the entire lower short girder 20a.

[0054] Therefore, even in a structure in which the lower end plate 42 is fastened to the lower short girder 20a by the bolts 101 and nuts 102, the joining strength of the column can be ensured.

[0055] (4) In the column structure of the building unit of embodiment 1, the lower stiffener 570 includes a splice plate 571 arranged along the back surface of the fastening surface of the lower end plate 42 of the lower short girder 20a, and a beam end plate 573 as a vertical plate that is welded to cover the opening at the tip of the lower short girder 20a. The beam end plate 573 is welded to the splice plate 571 in advance so that it can cover the opening in the lower short girder 20a when the splice plate 571 is installed.

[0056] Therefore, compared to a case where the splice plate 571 and the beam end plate 573 are separate parts and are installed independently on the lower short girder 20a, this method is easier to work with. Additionally, in the first embodiment, the splice plate 571 is provided with a chamfered portion 571c, which makes it easier to ensure the welding strength of the beam end plate 573 compared to when the chamfered portion 571c is not provided. This ensures high welding strength, making it easier to ensure the joining strength between the hollow column 40 and the lower short girder 20a.

[0057] (5) In the column structure of the building unit of the first embodiment, a mounting plate 500 is provided on the roof girder 10a at the position where the exterior wall WO is installed, inside the unit. The mounting plate 500 is then provided with an auxiliary beam 520 for attaching the exterior wall WO and a ceiling board. Ceiling joist 14 is being bridged.

[0058] Therefore, the auxiliary beam 520 and Ceiling joist 14 can be installed without interfering with the hollow column 40 or the upper end plate 41 and upper stiffener 60 that connect the upper end of this hollow column 40 to the roof girder 10a.

[0059] (Other embodiments) The second embodiment shown in FIGS. 7 and 8 will be described below.

[0060] In this second embodiment, the structure of connecting the lower end plate 242 provided at the lower end of the hollow column 240 to the lower short girder 20a is different from that of the hollow column 40 in the first embodiment.

[0061] The lower end plate 242 is joined by welding to the upper surface of the upper flange 23 of the lower short girder 20a. Furthermore, since the lower end plate 242 is joined to the upper flange 23 by welding, the lower end plate 242 is not provided with insertion holes 42a, 42b for inserting the bolts 101 therethrough.

[0062] Furthermore, since the lower end plate 242 is welded, a higher connection strength can be obtained than with fastening using bolts 101 and nuts 102, so the lower short girder 20a is not provided with a lower stiffener 570. Therefore, the beam end plate 573 is welded to the lower short girder 20a in advance.

[0063] In this second embodiment, the hollow columns 240 are also of a beam-supported structure, so as described above in (1), they can be installed anywhere, and a high degree of design freedom can be obtained compared to a column-supported structure. In addition, the lower short girder 20a can ensure high connection strength while preventing it from protruding from the exterior wall WO.

[0064] The above has described in detail an embodiment of the column structure of the building unit of the present disclosure with reference to the drawings, but the specific configuration is not limited to this embodiment, and design changes that do not deviate from the gist of the present invention are included in the present invention.

[0065] For example, in the embodiment, an example in which a pair of lower short girders are provided is shown, but it is also possible to use only one of the pair of lower short girders, with the other being formed to the same length as the upper girders. In this case, the wall perpendicular to the intermediate wall (exterior wall WO) can be extended to the entire length of the unit. Also, in the embodiment, hollow columns 30, 40, and 50 with similar cross-sectional shapes are shown as columns, but columns other than hollow column 40 can be columns with a column-dominant structure rather than a beam-dominant structure, or columns with a different shape or dimensions from hollow column 40. [Explanation of symbols]

[0066] 10a Roof beam (upper beam) 20a Lower short girder 21 Lower flange 22 Web 23 Upper flange 40 hollow pillar 41 Upper end plate 42 Lower end plate 42a Insertion hole 42b Insertion hole 43 Working opening 60 Upper stiffener 61 Plate 62 Vertical board 70 Lower stiffener 71 Plate 72 Vertical board 101 Bolts (fastening members) 102 Nut (fastening member) 240 Hollow Pillar 242 Lower end plate 500 Mounting Plate 501 Ceiling bracket 502 Bracket for auxiliary beam 510 Ceiling materials 520 Auxiliary beam 570 Lower stiffener 571 Plate 571a, 571b Insertion holes 573 Beam end plate (vertical plate) GA Garage RM room U1 Building Unit WO exterior wall (intermediate wall)

Claims

1. A column structure of a building unit formed by connecting upper and lower girders that face each other vertically with columns, An intermediate wall is provided in the intermediate portion of the building unit to divide the interior of the building unit into a living space and a non-living space, The lower girder is provided with a lower short girder formed to a length from one end of the building unit to the position of the intermediate wall and extending in the long side direction of the building unit, The column includes a hollow cylindrical column that is connected to an upper surface of the tip end of the lower short girder and a lower surface of the upper girder that faces the upper surface and is provided inside the intermediate wall, The hollow column has upper and lower end plates at its upper and lower ends, the upper end plate is fastened to the lower surface of the upper girder by a fastening member; The lower end plate is sized so as not to protrude from the intermediate wall toward the non-habitable space, and is fastened to the upper surface of the lower short girder with fastening members; a fastening point of the lower end plate by the fastening member is provided within the hollow portion of the hollow column; A hole for inserting the fastening member is opened in the hollow post, a mounting plate is provided on the upper girder at a position inside the unit where the intermediate wall is installed; An auxiliary beam for attaching the intermediate wall and a ceiling material for attaching a ceiling board are spanned over the mounting plate, A stiffener is provided at a joint of the lower end plate of the lower short girder to transmit stress due to input from the hollow column to the entire lower short girder, The stiffener includes a splice plate arranged along the back surface of the fastening surface of the lower end plate of the lower short girder, a first vertical plate joined to the underside of the splice plate by welding and extending along the hollow column, and a second vertical plate welded to close an opening at the tip end of the lower short girder in the long side direction, The second vertical plate is welded to the splice plate in advance so that the opening in the lower short girder can be closed when the splice plate is installed.

2. A column structure of a building unit formed by connecting upper and lower girders that face each other vertically with columns, An intermediate wall is provided in the intermediate portion of the building unit to divide the interior of the building unit into a living space and a non-living space, The lower girder is provided with a lower short girder formed to a length from one end of the building unit to the position of the intermediate wall and extending in the long side direction of the building unit, The column includes a hollow cylindrical column that is connected to an upper surface of the tip end of the lower short girder and a lower surface of the upper girder that faces the upper surface and is provided inside the intermediate wall, The hollow column has upper and lower end plates at its upper and lower ends, the upper end plate is fastened to the lower surface of the upper girder by a fastening member; The lower end plate is sized so as not to protrude from the intermediate wall toward the non-habitable space, and is joined to the upper surface of the lower short girder by welding, A stiffener is provided at a joint of the lower end plate of the lower short girder to transmit stress due to input from the hollow column to the entire lower short girder, The stiffener includes a splice plate arranged along the back surface of the fastening surface of the lower end plate of the lower short girder, a first vertical plate joined to the underside of the splice plate by welding and extending along the hollow column, and a second vertical plate welded to close an opening at the tip end of the lower short girder in the long side direction, The second vertical plate is welded to the splice plate in advance so that the opening in the lower short girder can be closed when the splice plate is installed.

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