Different diameter column joint structure

Abstract

To provide a different-diameter column joining structure in which a lower column and an upper column having different diameters are joined to each other via a diaphragm, and which can smoothly transmit a force from the upper column to the lower column without involving thickening of a thickness of the diaphragm.SOLUTION: In a different-diameter column joining structure 100, a lower column 10 of a relatively large diameter is joined to a lower face 42 of a diaphragm 40, and an upper column 20 of a relatively small diameter is joined to an upper face 41. The lower column 10 comprises at least a square or circular steel pipe, and a reinforcing rib which is joined to the upper face 41 of the diaphragm 40 from a part of the upper column 20 overlaps a part of an upper end of the lower column in plan view.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a connection structure for columns with different diameters.

Background Art

[0002] In a steel frame building, a connection structure for columns with different diameters may be applied, in which the columns on the rooftop floor (upper columns) and the columns on the lower floor (lower columns) are formed of different members, and the upper columns are relatively smaller in size. For example, a form in which the lower columns are formed of relatively large-sized square steel pipes or the like, and the upper columns, which are the columns on the rooftop floor, are formed of shaped steel materials such as relatively small-sized square steel pipes or H-shaped steel. In such a connection structure for columns with different diameters, it is common that the lower columns are joined to the lower surface of the diaphragm and the upper columns are joined to the upper surface thereof.

[0003] Since the cross-sectional shapes and cross-sectional dimensions of the upper columns and the lower columns are different, it is difficult to smoothly transmit the forces acting on the upper columns to the lower columns, and there is a risk that the diaphragm, the upper columns, and the lower columns may be damaged. Therefore, there has been a problem that the plate thickness of the diaphragm has to be increased in order to ensure smooth transmission of forces from the upper columns to the lower columns.

[0004] Here, Patent Document 1 proposes a method for predicting the rigidity of a diaphragm and a method for designing the plate thickness in a joint portion of steel pipe columns with different diameters at the top and bottom. Among these, the method for designing the plate thickness of the diaphragm uses a method for predicting the rigidity of the diaphragm in a joint portion of steel pipe columns with different diameters at the top and bottom that are eccentric in two directions, where two adjacent sides of the cross-section of the upper column are aligned with two adjacent sides of the cross-section of the lower column, to obtain the rigidity of the diaphragm when a design load is applied to the upper column, and selects, as the material for the diaphragm, the steel plate with the thinnest plate thickness that satisfies the required rigidity from among a plurality of types of standardized steel plates with different plate thicknesses.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] While the diaphragm thickness design method for a steel pipe column joint of different diameters described in Patent Document 1 allows for high-precision design of the diaphragm thickness in a two-way eccentric column joint structure of different diameters, it does not disclose a means for achieving smooth force transmission from the upper column to the lower column without increasing the thickness of the diaphragm, regardless of whether or not there is eccentricity between the lower and upper columns in the column joint structure of different diameters.

[0007] The present invention has been made in view of the above problems, and aims to provide a column joint structure of different diameters in which a lower column and an upper column of different diameters are joined to each other via a diaphragm, which can achieve smooth force transmission from the upper column to the lower column without increasing the thickness of the diaphragm. [Means for solving the problem]

[0008] To achieve the above objective, one embodiment of the column joint structure of different diameters according to the present invention is: A column joint structure with different diameters, in which a relatively large diameter lower column is joined to the lower surface of a diaphragm, and a relatively small diameter upper column is joined to the upper surface of the lower column, The aforementioned lower column is equipped with at least a square or circular steel pipe, The reinforcing rib, which is joined from a part of the upper column to the upper surface of the diaphragm, is characterized in that, in a plan view, it overlaps a part of the upper end of the lower column.

[0009] According to this embodiment, in a joint structure in which an upper column and a lower column of different diameters are welded to the upper and lower surfaces of a diaphragm, a reinforcing rib joined from a part of the upper column to the upper surface of the diaphragm overlaps (laps) with a part of the upper end of the lower column in a plan view. As a result, the force acting on the upper column can be directly transmitted to the lower column from the base of the upper column and the reinforcing rib through the diaphragm, thus enabling smooth force transmission from the upper column to the lower column without increasing the thickness of the diaphragm. Here, the lower column is formed from a square steel pipe or a steel pipe, and the upper column is formed from a relatively small-diameter square steel pipe or steel pipe, as well as a shaped steel material such as an H-beam. In particular, when the upper column is a column on the rooftop floor, the load it supports is reduced, so an upper column made of shaped steel material may be used.

[0010] Furthermore, other embodiments of the column joint structure of different diameters according to the present invention are: A column joint structure of different diameters comprising a panel core forming a panel zone, an upper diaphragm and a lower diaphragm joined to the upper and lower ends, respectively, an upper column joined to the upper surface of the upper diaphragm, and a lower column joined to the lower surface of the lower diaphragm, wherein the lower column is relatively larger in diameter than the upper column, The lower column and the panel core are comprised of at least a rectangular or circular steel pipe. The reinforcing rib, which is joined from a part of the upper column to the upper surface of the upper diaphragm, is characterized in that, in a plan view, it overlaps a part of the upper end of the panel core.

[0011] According to this embodiment, in a joint structure in which an upper column and a lower column are joined to the upper and lower diaphragms and lower diaphragms of a panel core, respectively, a reinforcing rib, for example, welded from a part of the upper column to the upper surface of the upper diaphragm, overlaps (laps) with a part of the upper end of the panel core in a plan view. As a result, the force acting on the upper column can be directly transmitted to the panel core from the legs of the upper column and the reinforcing rib through the upper diaphragm, thus enabling smooth force transmission from the upper column to the panel core and further to the lower column without increasing the thickness of the upper diaphragm. Here, the panel core and the lower column are formed from, for example, square steel pipes or steel pipes of the same diameter, while the upper column is formed from steel pipes or shaped steel materials of a relatively smaller diameter than these.

[0012] Furthermore, other embodiments of the column joint structure of different diameters according to the present invention are: The lower column is characterized by being formed from a concrete-filled steel pipe, in which concrete is filled inside the steel pipe.

[0013] According to this embodiment, in a joint structure in which upper and lower columns of different diameters are joined to the upper and lower surfaces of a diaphragm, the lower column is formed from a concrete-filled steel tube (CFT), which makes it possible to increase the axial compressive strength, bending strength, and deformation performance of the lower column. Furthermore, since the lower surface of the diaphragm is supported by the entire cross-section of the lower column made of concrete-filled steel tube, out-of-plane deformation (indentation) of the diaphragm downward is suppressed by the compressive reaction force of the concrete-filled steel tube. Combined with the increase in out-of-plane rigidity due to the reinforcing ribs of the upper column's base, including the diaphragm, it becomes possible to reduce the thickness of the diaphragm.

[0014] Furthermore, other embodiments of the column joint structure of different diameters according to the present invention are: The lower column and the panel core are characterized by being formed from concrete-filled steel pipes, in which concrete is filled inside the steel pipe.

[0015] According to this embodiment, in a joint structure in which an upper column and a lower column are joined to the upper and lower diaphragms and lower diaphragms of a panel core, respectively, the panel core and the lower column are formed from concrete-filled steel pipes, thereby increasing the axial compressive strength, bending strength, and deformation performance of the panel core and the lower column. Furthermore, since the lower surface of the upper diaphragm is supported by the entire cross-section of the panel core made of concrete-filled steel pipes, out-of-plane deformation (indentation) of the upper diaphragm downward is suppressed by the compressive reaction force of the concrete-filled steel pipes. Combined with the increase in out-of-plane rigidity due to the reinforcing ribs of the legs of the upper column, including the upper diaphragm, it becomes possible to reduce the thickness of the upper diaphragm.

[0016] Furthermore, other embodiments of the column joint structure of different diameters according to the present invention are: The upper column is characterized by being formed from H-shaped steel.

[0017] According to this embodiment, since the upper column is formed of H-shaped steel, for example, if the upper column is a column on the rooftop floor, it will be a column with suitable rigidity, and a column joint structure of different diameters can be formed with material costs kept to a minimum compared to the case in which square steel pipes or the like are used for the upper column.

[0018] Furthermore, other embodiments of the column joint structure of different diameters according to the present invention are: The reinforcing ribs are joined to the flange of the H-shaped steel, and the reinforcing ribs overlap a portion of the upper surface of the steel pipe located below the diaphragm or the upper diaphragm.

[0019] According to this embodiment, in a joint structure to which an upper column made of H-shaped steel is applied, by welding reinforcing ribs to the flange of the H-shaped steel, for example, the force acting on the upper column can be directly transmitted from the leg portion of the flange of the H-shaped steel and the reinforcing ribs via a diaphragm or upper diaphragm to the lower column or panel core.

[0020] Here, as the joining form of the reinforcing rib to the flange of the H-shaped steel, there are forms in which a reinforcing rib arranged parallel to the flange is joined to the end face of the flange, forms in which the wide-width surface of the reinforcing rib is joined in a state of abutting against the wide-width surface outside the flange, forms in which a reinforcing rib arranged in a direction orthogonal to the flange is joined to the wide-width surface outside the flange, forms in which a reinforcing rib arranged parallel to the flange is joined to the end face of the flange and a reinforcing rib arranged in a direction orthogonal to the flange is joined to the wide-width surface outside the flange, forms in which reinforcing ribs arranged parallel to the web are joined to the end faces of the two flanges, and the like.

[0021] Further, another aspect of the different-diameter column joint structure according to the present invention is characterized in that the reinforcing rib is joined to the web of the H-shaped steel and the reinforcing rib overlaps a part of the upper surface of the steel pipe below the diaphragm or the upper diaphragm.

[0022] According to this aspect, in a joint structure to which an upper column made of H-shaped steel is applied, since the reinforcing rib is joined to the web of the H-shaped steel, for example, by welding, the force acting on the upper column can be directly transmitted from the leg portion of the web of the H-shaped steel and the reinforcing rib to the lower column or the panel core through the diaphragm or the upper diaphragm. Here, as the joining form of the reinforcing rib to the web of the H-shaped steel, there are forms in which a reinforcing rib arranged parallel to the flange is joined to the wide-width surface of the web, and the like.

[0023] Further, another aspect of the different-diameter column joint structure according to the present invention is characterized in that the reinforcing rib is joined to each of the two flanges and the web of the H-shaped steel and the reinforcing rib overlaps a part of the upper surface of the steel pipe below the diaphragm or the upper diaphragm.

[0024] According to this embodiment, in a joint structure to which an upper column made of H-shaped steel is applied, reinforcing ribs are welded to, for example, the flange and web of the H-shaped steel, so that the force acting on the upper column can be directly transmitted to the lower column or panel core from the legs of both the flange and web of the H-shaped steel and the reinforcing ribs via a diaphragm or upper diaphragm. Here, examples of the joining configuration of the reinforcing ribs to both the flange and web of the H-shaped steel include a configuration in which reinforcing ribs arranged in a direction perpendicular to the flange are joined to the wide outer surface of the flange, and reinforcing ribs arranged parallel to the flange are joined to the wide outer surface of the web. [Effects of the Invention]

[0025] As can be understood from the above explanation, the column joint structure of the present invention, in which a lower column and an upper column of different diameters are joined to each other via a diaphragm, enables smooth force transmission from the upper column to the lower column without increasing the thickness of the diaphragm. [Brief explanation of the drawing]

[0026] [Figure 1] This is a perspective view of an example of a column joint structure of different diameters according to the first embodiment. [Figure 2] This is a view from the direction arrow II in Figure 1, and is a plan view taken from above the diaphragm. [Figure 3A] Another example of the mounting configuration of the reinforcing ribs is shown in a plan view from above the diaphragm. [Figure 3B] Another example of the reinforcing rib mounting configuration is shown in a plan view from above the diaphragm. [Figure 4A] Another example of the reinforcing rib mounting configuration is shown in a plan view from above the diaphragm. [Figure 4B] Another example of the reinforcing rib mounting configuration is shown in a plan view from above the diaphragm. [Figure 4C] Another example of the reinforcing rib mounting configuration is shown in a plan view from above the diaphragm. [Figure 5A]Another example of the reinforcing rib mounting configuration is shown in a plan view from above the diaphragm. [Figure 5B] Another example of the reinforcing rib mounting configuration is shown in a plan view from above the diaphragm. [Figure 6] This is a perspective view of an example of a column joint structure with different diameters according to the second embodiment. [Figure 7] This is a perspective view of an example of a column joint structure with different diameters according to the third embodiment. [Modes for carrying out the invention]

[0027] Hereinafter, an example of a column joint structure with different diameters according to each embodiment will be described with reference to the attached drawings. In this specification and drawings, substantially identical components may be denoted by the same reference numerals to avoid redundant explanations.

[0028] [Column joint structure with different diameters according to the first embodiment] First, an example of a column joint structure of different diameters according to the first embodiment will be described with reference to Figures 1 to 5. Here, Figure 1 is a perspective view of an example of a column joint structure of different diameters according to the first embodiment, and Figure 2 is a view in the direction of arrow II in Figure 1, which is a plan view seen from above the diaphragm.

[0029] The disparate diameter column joint structure 100 is formed by welding the upper end 11 of a relatively large-diameter lower column 10 to the lower surface 42 of a diaphragm 40 (through diaphragm), and welding the lower end 21 of a relatively small-diameter upper column 20 to the upper surface 41 of the diaphragm 40. Here, "joining" in the following description is, in principle, welding, but bolting or other methods may be applied as needed.

[0030] The lower column 10 is formed from a square steel pipe. Here, the lower column may be formed from a steel pipe other than a square steel pipe.

[0031] The diaphragm 40 is formed from a steel plate that is rectangular (or square) in plan view, and the illustrated example is a steel plate that is square in plan view.

[0032] On the other hand, the upper column 20 is made of an H-shaped steel beam with a web 22 and a flange 23, and has a smaller cross-sectional dimension than the square steel pipe 10. Here, the upper column may be made of other shaped steel materials such as channel steel, square steel pipes, or steel pipes in addition to the H-shaped steel beam.

[0033] The illustrated column joint structure 100 is a joint structure in a steel-framed building in which the upper column 20 forms the column of the rooftop floor. Since the load supported by the upper column 20 does not need to be relatively small, an upper column 20 made of H-shaped steel is used.

[0034] As shown in Figure 2, the column centers of the lower column 10 and the upper column 20 coincide with each other. However, the column centers of both the lower and upper columns may be eccentric in one or two of the two orthogonal directions (X and Y directions) of the planar rectangle of the diaphragm 40.

[0035] Reinforcement ribs 50 are joined to a total of four end faces 23a of two flanges 23 of the leg portion of the upper column 20. More specifically, the two orthogonal end faces 50a and 50b of the reinforcement rib 50 are joined to the end face 23a of the flange 23 and the upper surface 41 of the diaphragm 40, respectively. Here, the reinforcement rib 50 in the illustrated example is formed from a steel plate with a rectangular shape in plan view, but it may be formed from a steel plate with various shapes in plan view, such as a steel plate with a triangular shape or a steel plate with a trapezoidal shape in plan view.

[0036] As clearly shown in Figure 2, in the illustrated example, the multiple (four in the illustrated example) reinforcing ribs 50 are all arranged parallel to the flange 23 in a plan view, and a portion of them overlaps (wraps) with a portion of the upper end 11 of the lower column 10 below the diaphragm 40.

[0037] In this way, the reinforcing rib 50, which is joined from a part of the upper column 20 to the upper surface 41 of the diaphragm 40, overlaps with a part of the upper end 11 of the lower column 10 in a plan view. For example, when a horizontal force H during an earthquake or strong wind, as shown in Figure 1, acts on the upper column 20 and a compressive force P acts on the diaphragm 40 from the base of the upper column 20, this compressive force P can be directly transmitted from the reinforcing rib 50 to the lower column 10 via the diaphragm 40.

[0038] This makes it possible to smoothly transmit the force acting on the upper column 20 to the lower column 10 via the diaphragm 40 without increasing the thickness of the diaphragm 40.

[0039] If reinforcing ribs are absent, as shown in Figure 2, in the case where the upper column 20 completely fits into the cross-section of the lower column 10 due to the different-diameter column joint structure, the point on the diaphragm 40 where the compressive force P from the upper column 20 acts is not directly supported by the lower column 10. Therefore, the thickness of the diaphragm 40 needs to be thick enough to withstand the compressive force P, and the thickness of the diaphragm inevitably becomes thicker.

[0040] In contrast, the reinforcing rib 50 joined to the upper column 20 overlaps the upper end 11 of the lower column 10 in a plan view, allowing the compressive force P to be directly transmitted to the lower column 10, thus eliminating the need to increase the thickness of the diaphragm 40. More specifically, the application of the reinforcing rib 50 makes it possible to reduce the thickness of the diaphragm 40 compared to conventional diaphragms.

[0041] For example, if the thickness of the steel plate exceeds 50 mm, it may limit the grade of steel fabrication plants that can process it. Therefore, reducing the thickness of the diaphragm 40 will lead to an increase in the number of steel fabrication plants that can process it.

[0042] Furthermore, the reinforcing ribs 50 improve the out-of-plane rigidity and load-bearing capacity of the diaphragm 40, thereby suppressing deformation of the legs of the upper column 20 during earthquakes, and improving the load-bearing capacity of the legs of the upper column 20 by easing the stress gradient in the legs.

[0043] Furthermore, since the reinforcing rib 50 is a member that transmits the pressing force P from the upper column 20 to the lower column 10, the thickness of the reinforcing rib 50 is set to a thickness that provides sufficient rigidity to transmit the pressing force P, and the dimensions of the reinforcing rib 50 are set to dimensions that ensure a welding length that can transmit the pressing force P.

[0044] Next, with reference to Figures 3 to 5, other examples of the mounting configuration of the reinforcing ribs will be described. In each of the examples described below, the reinforcing ribs 50 and 50A are welded to a part of the upper column 20 and also welded to the upper surface 41 of the diaphragm 40, as in the examples shown in Figures 1 and 2.

[0045] First, Figures 3A and 3B show examples where the reinforcing ribs 50 and 50A are arranged parallel to the flange 23 of the upper column 20 (in a direction perpendicular to the web 22), similar to the mounting configuration shown in Figures 1 and 2.

[0046] The example shown in Figure 3A is a configuration in which the wide surface 50c of a reinforcing rib 50A, which is wider than the reinforcing rib 50 shown in Figure 1, etc., is in contact with the wide surface 23b of the outer surface 23b of the flange 23. Each reinforcing rib 50A overlaps both of the opposing end edges of the lower column 10.

[0047] On the other hand, the example shown in Figure 3B is a configuration in which reinforcing ribs 50 arranged parallel to the flange 23 are joined to the center of the wide surface 22a of the web 22 of the upper column 20. Each reinforcing rib 50 wraps around each of the opposing pair of end edges of the lower column 10.

[0048] In the examples shown in Figures 3A and 3B, the compressive force caused by the horizontal force H acting on the upper column 20 in a direction parallel to the flange 23 can be directly transmitted to the lower column 10 via the diaphragm 40.

[0049] Next, Figures 4A to 4C show an example in which the reinforcing ribs 50 and 50A are arranged in a direction perpendicular to the flange 23 of the upper column 20 (parallel to the web 22).

[0050] The example shown in Figure 4A is a configuration in which a portion of the wide surface 50c of a reinforcing rib 50A, which is arranged perpendicular to the flange 23, is joined to the end faces 23a of the two flanges 23. Each reinforcing rib 50A wraps around both of the opposing end sides of the lower column 10.

[0051] On the other hand, the example shown in Figure 4B is a configuration in which the end faces 50a of multiple (two in the illustrated example) reinforcing ribs 50, which are arranged in a direction perpendicular to the flange 23, are joined to the wide outer surface 23b of the flange 23. In plan view, the two reinforcing ribs 50 extend laterally from two points on the wide surface 23b of the flange 23 that are equidistant from the web 22, and each reinforcing rib 50 laps over the corresponding end edge of the lower column 10.

[0052] Although not shown in the illustration, in addition to the configuration with two reinforcing ribs 50 shown in the illustration, there may also be configurations in which three or more reinforcing ribs are joined to the wide surface 23b of the flange 23. In the configuration with three reinforcing ribs, the three reinforcing ribs extend laterally from a total of three points on the wide surface 23b: one corresponding to the web 22 and two points equidistant from the web 22. On the other hand, in the configuration with four reinforcing ribs, a total of four reinforcing ribs are arranged in two sets, each at two different equidistant points from the web 22 on the wide surface 23b.

[0053] On the other hand, the example shown in Figure 4C is a configuration in which the end face 50a of the reinforcing rib 50, which is arranged in a direction perpendicular to the flange 23, is joined to the central position (corresponding to the web 22) of the wide outer surface 23b of the flange 23. In plan view, each reinforcing rib 50 wraps around the corresponding end edge of the lower column 10.

[0054] As shown in the examples in Figures 4A to 4C, in all cases, the compressive force caused by the horizontal force H acting on the upper column 20 in a direction parallel to the web 22 can be directly transmitted to the lower column 10 via the diaphragm 40.

[0055] Next, Figures 5A and 5B show examples that include both a plurality of reinforcing ribs 50 arranged parallel to the flange 23 of the upper column 20 (in a direction perpendicular to the web 22) and a plurality of reinforcing ribs 50 arranged perpendicular to the flange 23 (parallel to the web 22).

[0056] In the example shown in Figure 5A, the end face 50a of a reinforcing rib 50 arranged perpendicular to the flange 23 is joined to a position on the wide outer surface 23b of the flange 23 corresponding to the web 22, and the end face 50a of a reinforcing rib 50 arranged parallel to the flange 23 is joined to the central position on the wide outer surface 22a of the web 22. In plan view, a total of four reinforcing ribs 50 each wrap around the end edge of the corresponding lower column 10.

[0057] On the other hand, the example shown in Figure 5B is a configuration in which the end faces 50a of multiple (two in the illustrated example) reinforcing ribs 50 arranged perpendicular to the flange 23 are joined at a position equidistant from the web 22 of the wide outer surface 23b of the flange 23, and the end faces 50a of reinforcing ribs 50 arranged parallel to the flange 23 are joined to the end face 23a of the flange 23. In plan view, a total of eight reinforcing ribs 50 each wrap around the end edge of the corresponding lower column 10.

[0058] As shown in the examples in Figures 5A and 5B, in both cases, the compressive forces resulting from the horizontal forces H acting on the upper column 20 in two directions—one parallel to the web 22 and the other parallel to the flange 23—can be directly transmitted to the lower column 10 via the diaphragm 40.

[0059] [Column joint structure with different diameters according to the second embodiment] Next, an example of a column joint structure of different diameters according to the second embodiment will be described with reference to Figure 6. Here, Figure 6 is a perspective view of an example of a column joint structure of different diameters according to the second embodiment.

[0060] The column joint structure 100A differs from the column joint structure 100 in that the lower column 10A is a concrete-filled steel pipe in which concrete 60 is filled inside a square steel pipe.

[0061] Because the lower column 10A is a concrete-filled steel pipe (CFT), a so-called confinement effect (mutual restraint effect) is achieved between the filled concrete 60 and the square steel pipe, making it possible to improve the axial compressive strength, bending strength, and deformation performance of the lower column 10A.

[0062] Furthermore, the improved load-bearing capacity and deformation performance of the lower column 10A allows for smaller column dimensions and higher floor heights compared to square steel pipes without concrete filling, making it suitable for large-scale buildings such as large spaces and skyscrapers.

[0063] Furthermore, since the lower surface 42 of the diaphragm 40 is supported by the entire cross-section of the lower column 10A, which is made of concrete-filled steel pipe, the out-of-plane deformation of the diaphragm 40 downward is suppressed by the compressive reaction force of the concrete-filled steel pipe 10A. Combined with the increase in out-of-plane rigidity due to the reinforcing ribs 50 of the leg portion of the upper column 20, including the diaphragm 40, the thickness of the diaphragm 40 can be reduced.

[0064] [Column joint structure with different diameters according to the third embodiment] Next, an example of a column joint structure of different diameters according to the third embodiment will be described with reference to Figure 7. Here, Figure 7 is a perspective view of an example of a column joint structure of different diameters according to the third embodiment.

[0065] The column joint structure 100B differs from the column joint structures 100 and 100A in that it has a panel core 30 that forms a panel zone.

[0066] More specifically, an upper diaphragm 40A (through diaphragm) and a lower diaphragm 40B (through diaphragm) are joined to the upper end 31 and lower end 32 of a panel core 30 formed from a rectangular steel pipe, respectively. The lower end 21 of an upper column 20 formed from an H-shaped steel is joined to the upper surface 41 of the upper diaphragm 40A, and the upper end of a lower column 10, which is relatively larger in diameter than the upper column 20 and formed from a rectangular steel pipe, is joined to the lower surface 42 of the lower diaphragm 40B.

[0067] The lower column 10 and the panel core 30 are formed from square steel pipes of the same dimensions. In the illustrated example, the web 71 of the beam 70, which is formed from H-shaped steel, is joined to the side surface of the panel core 30, the upper flange 72 is joined to the end face of the upper diaphragm 40A, and the lower flange 73 is joined to the end face of the lower diaphragm 40B.

[0068] In the column joint structure 100B with different diameters, all four reinforcing ribs 50 are arranged parallel to the flange 23 in a plan view, and a portion of them overlaps with a portion of the upper end 31 of the panel core 30 below the diaphragm 40.

[0069] In the different-diameter column joint structure 100B, the reinforcing rib 50, which is welded from a part of the upper column 20 to the upper surface 41 of the upper diaphragm 40A, overlaps with a part of the upper end 31 of the panel core 30 in a plan view. As shown in Figure 7, when a horizontal force H acts on the upper column 20 during an earthquake or strong wind, and a compressive force P acts on the upper diaphragm 40A from the base of the upper column 20, this compressive force P can be directly transmitted from the reinforcing rib 50 to the panel core 30 via the upper diaphragm 40A, and further transmitted to the lower column 10 via the lower diaphragm 40B.

[0070] This makes it possible to smoothly transmit the force acting on the upper column 20 to the panel core 30 and the lower column 10 via the upper diaphragm 40A without increasing the thickness of the upper diaphragm 40A.

[0071] In this configuration, even in the column joint structure 100B with different diameters, both the panel core 30 and the lower column 10 may be concrete-filled steel pipes with concrete filled inside. In this configuration, since the lower surface of the upper diaphragm 40A is supported by the entire cross-section of the panel core made of concrete-filled steel pipe, the out-of-plane deformation of the upper diaphragm 40A downward is suppressed by the compressive reaction force of the concrete-filled steel pipe. Combined with the increase in out-of-plane rigidity due to the reinforcing ribs 50 of the leg portion of the upper column 20, including the upper diaphragm 40A, the thickness of the upper diaphragm 40A can be reduced.

[0072] Other embodiments may be used in which other components are combined with the configurations listed in the above embodiments, and the present invention is not limited in any way to the configurations shown herein. In this regard, modifications can be made without departing from the spirit of the present invention, and can be appropriately determined according to the application form. [Explanation of symbols]

[0073] 10: Lower column (square steel pipe) 10A: Lower column (concrete-filled steel pipe) 11:Top edge 20: Upper column (H-shaped steel) 21: Bottom edge 22: Web 22a: Wide surface 23: Flange 23a: End face 23b: Wide surface 30: Panel core 31:Top edge 32: Bottom edge 40: Diaphragm 41:Top surface 42: Bottom surface 40A: Upper diaphragm 40B: Lower diaphragm 50, 50A: Reinforcement ribs 50a, 50b: End surface 50c: Wide surface 60: Concrete 70: Beam (H-shaped steel) 100, 100A, 100B: Different diameter column joint structure

Claims

1. A column joint structure with different diameters, in which a relatively large diameter lower column is joined to the lower surface of a diaphragm, and a relatively small diameter upper column is joined to the upper surface of the lower column, The aforementioned lower column is equipped with at least a square or circular steel pipe, The aforementioned upper column is formed from H-shaped steel, A column joint structure of different diameters, characterized in that a reinforcing rib, which is joined from a part of the upper column to the upper surface of the diaphragm, overlaps a part of the upper end of the lower column in a plan view.

2. A column joint structure of different diameters comprising a panel core forming a panel zone, an upper diaphragm and a lower diaphragm joined to the upper and lower ends, respectively, an upper column joined to the upper surface of the upper diaphragm, and a lower column joined to the lower surface of the lower diaphragm, wherein the lower column is relatively larger in diameter than the upper column, The lower column and the panel core are comprised of at least a rectangular or circular steel pipe. The aforementioned upper column is formed from H-shaped steel, A column joint structure of different diameters, characterized in that a reinforcing rib, which is joined from a part of the upper column to the upper surface of the upper diaphragm, overlaps a part of the upper end of the panel core in a plan view.

3. The column joint structure of different diameters according to claim 1, characterized in that the lower column is formed from a concrete-filled steel pipe in which concrete is filled inside the steel pipe.

4. The column joint structure of different diameters according to claim 2, characterized in that the lower column and the panel core are formed from concrete-filled steel pipes in which concrete is filled inside the steel pipe.

5. The column joint structure of different diameters according to claim 1 or 2, characterized in that the reinforcing rib is joined to the flange of the H-shaped steel, and the reinforcing rib overlaps a part of the upper surface of the steel pipe located below the diaphragm or the upper diaphragm.

6. The column joint structure of different diameters according to claim 1 or 2, characterized in that the reinforcing rib is joined to the web of the H-shaped steel, and the reinforcing rib overlaps a part of the upper surface of the steel pipe located below the diaphragm or the upper diaphragm.

7. The column joint structure of different diameters according to claim 1 or 2, characterized in that the reinforcing ribs are joined to each of the two flanges and webs of the H-shaped steel, and the reinforcing ribs overlap a part of the upper surface of the steel pipe located below the diaphragm or the upper diaphragm.

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