Column-beam joint construction

Abstract

To provide a column-beam joint structure that can reduce manufacturing costs by reducing the excess length of the steel plates that form the panel core. [Solution] The column-beam joint structure 100 is such that four steel plates 1 and 2 are welded together, an inner diaphragm 6 is welded to the upper end 12 of the panel core 10 of a four-sided box, the upper end of a steel column 20 is welded to the lower end 14 of the four-sided box, the upper flange 32 of a steel beam 30 made of H-shaped steel is welded to a position on the steel plates 1 and 2 corresponding to the inner diaphragm 6, the web 31 and lower flange 33 are welded to the steel plates 1 and 2, and the steel column is not joined to the upper surface of the inner diaphragm 6, and the bending strength of the steel column 20 is included in the design of the plate thickness tp based on the out-of-plane bending strength of the steel plates 1 and 2.

Description

[[Technical Field]]

[0001] The present invention relates to a column-beam joint structure. [[Background Art]]

[0002] For a column-beam joint in a steel frame building where a rectangular steel pipe is used as a steel column and an H-shaped steel is used as a steel beam, a through-diaphragm type, an internal diaphragm type and other types are adopted. The through-diaphragm type column-beam joint structure has a structure where, in a panel core formed of a rectangular steel pipe, through-diaphragms are welded and fixed at positions corresponding to the upper and lower flanges of the steel beam so as to protrude to the outside of the panel core. The flanges of the steel beam formed of H-shaped steel are welded to the through-diaphragms protruding outward, and the upper and lower rectangular steel pipe columns are welded to the upper and lower through-diaphragms. In addition, when the beam depths of the left and right steel beams are different, in addition to the upper and lower through-diaphragms, an internal diaphragm is welded in the panel core at a position corresponding to, for example, the flange of the steel beam with a smaller beam depth.

[0003] However, these column-beam joint structures provided with a plurality of diaphragms tend to require a large number of manufacturing man-hours during production, and also tend to have longer weld lengths. Accordingly, there are problems that manufacturing is generally complicated, time is required for manufacturing, and manufacturing costs tend to be high.

[0004] Therefore, Patent Document 1 proposes a column-beam joint structure for joining the columns and beams of a building in a so-called non-diaphragm type, which omits the diaphragm. The column-beam joint structure described in Patent Document 1 (here, column-beam joint structure) is a column-beam joint structure in which a square steel pipe column and a steel beam are joined to a non-diaphragm type steel panel core. The steel panel core consists of four steel plates joined to each other via welds, with a rectangular cross-sectional shape perpendicular to the extension direction, the thickness of the steel plates being greater than the thickness of the square steel pipe column, the core depth of the steel panel core being greater than the beam depth of the steel beam, and there being an excess length between the upper and / or lower end of the steel panel core and the upper and / or lower end of the steel beam, with the excess length lp of the excess length having a length that satisfies a conditional equation based on yield line theory. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 7009141 [Overview of the project] [Problems that the invention aims to solve]

[0006] According to the column-beam joint structure described in Patent Document 1, the excess length lp of the excess length portion is set to satisfy the conditional equation based on yield line theory, thereby enabling a rigid joint between the steel panel core and the steel beam, even while applying a non-diaphragm type to the steel panel core.

[0007] Incidentally, the column-beam joint structure described in Patent Document 1 is a typical intermediate-story column-beam joint structure in which upper and lower steel columns are welded to the upper and lower ends of the panel core. In contrast, in column-beam joint structures on the top floor of a building, or in column-beam joint structures supporting large spaces such as lobbies on intermediate floors, there are forms in which there are no steel columns at the upper end of the panel core.

[0008] The column-beam joint structure described in Patent Document 1 does not cover configurations where there are no steel columns at the upper end of the panel core. Furthermore, the load-bearing capacity of the steel columns joined to the panel core is not taken into account in the calculation formula. As a result, the excess length from the lower end of the panel core to the steel columns may become long. Therefore, a column-beam joint structure is desired that can further shorten the excess length, thereby reducing the height dimension of the panel core and lowering manufacturing costs.

[0009] The present invention has been made in view of the above problems, and relates to a column-beam joint structure in which a steel column is welded to the lower end of a panel core, a steel column is not welded to the upper end, and a steel beam is welded to the side. The objective is to provide a column-beam joint structure that can reduce manufacturing costs by reducing the excess length of the steel plate forming the panel core. [Means for solving the problem]

[0010] To achieve the above objective, one embodiment of the column-beam joint structure according to the present invention is: A through diaphragm is welded to the upper edge of the panel core of a four-sided box, which is made up of four steel plates welded together. The upper end of the steel column is welded to the lower end of the four-sided box. The upper flange of the steel beam, which is made of H-shaped steel, is welded to the through diaphragm, and the web and lower flange are welded to the steel plate. The steel column is not joined to the upper surface of the aforementioned through diaphragm. The core depth of the panel core is greater than the beam depth of the steel beam, and there is an excess length between the lower end of the panel core and the lower end of the steel beam. The design of the plate thickness based on the out-of-plane bending strength of the steel plate is characterized in that the bending strength of the steel column is included.

[0011] In this embodiment, a through diaphragm is provided only at the upper end of the four-sided box, a steel column is welded to the lower end of the panel core, and no steel column is joined to the upper surface of the through diaphragm. In a column-beam joint structure in which a steel beam is welded to a steel plate, the bending strength of the steel column is included in the design of the plate thickness based on the out-of-plane bending strength of the steel plate. As a result, in column-beam joint structures on the top floor of a building, or column-beam joint structures supporting large spaces such as lobbies on intermediate floors, the length (excess length) can be shortened compared to the excess length based on conventional designs that do not include the bending strength of the steel column, and the height dimension of the panel core can be shortened, thus contributing to a reduction in the manufacturing cost of the panel core.

[0012] The upper flange of the steel beam is welded to the through diaphragm, and the upper surface of the upper flange and the upper surface of the through diaphragm are set to be flush, for example. Furthermore, the lateral center position of the steel plate of the panel core and the web of the steel beam (the lateral center of the steel beam) can be either perfectly aligned or the steel beam can be laterally eccentric with respect to the center of the panel core.

[0013] In addition to the configuration in which steel beams are welded to all four steel plates forming the panel core, there are also configurations in which steel beams are welded to three steel plates, configurations in which steel beams are welded to two mutually orthogonal steel plates or two opposing steel plates, and configurations in which steel beams are welded to one steel plate. In configurations in which two or more steel beams are welded together, each steel beam may be a stepped beam (a configuration in which the beam depths differ and the lower end levels of each steel beam are different).

[0014] In this embodiment, "no steel columns are joined to the upper surface of the through diaphragm" means that no structural steel beams are joined to the upper surface of the through diaphragm. More specifically, this includes both a configuration in which no members are joined at all, and a configuration in which non-structural members (such as bases for sheds or signs) are joined.

[0015] Furthermore, submerged arc welding is preferably used as the "welded joint." In submerged arc welding, a large-diameter wire is continuously placed at the welding point and a large current is passed through to form the weld, resulting in extremely high manufacturing (fabrication) efficiency for column-beam joint structures and the formation of high-quality welds.

[0016] Because the core depth of the panel core is greater than the beam depth of the steel beam, and there is an excess length between the lower end of the panel core and the lower end of the steel beam, the joint between the panel core and the steel beam can be made rigid. In addition, if seismic reinforcement braces such as buckling-restrained braces exist in the steel frame, the seismic reinforcement braces can be joined to the excess length. If there is no excess length, it may be necessary to join the seismic reinforcement braces to, for example, the steel column and take reinforcement measures at the joint on the steel column.

[0017] Furthermore, other embodiments of the column-beam joint structure according to the present invention are: An internal diaphragm is welded to the upper end of the panel core of a four-sided box, which is made up of four steel plates welded together. The upper end of the steel column is welded to the lower end of the four-sided box. The upper flange of the steel beam, which is made of H-shaped steel, is welded to the steel plate at a position corresponding to the inner diaphragm, and the web and lower flange are welded to the steel plate. The steel column is not joined to the upper surface of the inner diaphragm. The core depth of the panel core is greater than the beam depth of the steel beam, and there is an excess length between the lower end of the panel core and the lower end of the steel beam. The design of the plate thickness based on the out-of-plane bending strength of the steel plate is characterized in that the bending strength of the steel column is included.

[0018] According to this aspect, the present invention relates to a column-beam joint structure in which an inner diaphragm is provided only at the upper end of a four-sided box, a steel column is welded to the lower end of a panel core, no steel column is joined to the upper surface of the inner diaphragm, and a steel beam is welded to a steel plate. Since the bending resistance of the steel column is included in the design of the plate thickness based on the out-of-plane bending resistance of the steel plate, in a column-beam joint structure for the top floor of a building or a column-beam joint structure that supports a large space such as a lobby even on an intermediate floor, the length (extra length) of the extra length portion can be shortened compared with that of an extra length portion based on a conventional design that does not include the bending resistance of the steel column, and the height dimension of the panel core can be reduced, thereby contributing to the reduction of the manufacturing cost of the panel core.

[0019] Another aspect of the column-beam joint structure according to the present invention is the steel column is formed of a rectangular steel pipe, wherein the rectangular steel pipe is located inside the plate thickness of the panel core.

[0020] According to this aspect, since the steel column is formed of a rectangular steel pipe, a column-beam joint structure with high versatility and to which a rational steel material is applied can be formed.

[0021] Furthermore, since the rectangular steel pipe is located inside the plate thickness of the panel core, that is, the plate thickness of the steel plate is set to be thicker than the plate thickness of the steel column formed of the rectangular steel pipe, a highly rigid column-beam joint structure can be formed.

[0022] Another aspect of the column-beam joint structure according to the present invention is a plate thickness tp of the steel plate satisfies the following two conditional expressions (A) and (B) based on the yield line theory. [Mathematics]

[0023] According to this embodiment, the thickness of the steel plate forming the panel core is set so as to satisfy the conditional equation based on yield line theory, while also including the bending strength of the steel column, thereby providing a column-beam joint structure with sufficient structural strength.

[0024] Furthermore, other embodiments of the column-beam joint structure according to the present invention are: When the steel beam is aligned with the lateral center of the steel plate, The above conditions (A) and (B) are characterized in that they satisfy the following equation (C).

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[0025] According to this embodiment, by further satisfying equation (C) in the conditional equation based on yield line theory, the steel beam is aligned with the lateral center of the steel plate, and a column-beam joint structure with sufficient structural strength can be provided.

[0026] Furthermore, other embodiments of the column-beam joint structure according to the present invention are: When the steel beam is positioned at an eccentric location different from the lateral center of the steel plate, The above conditions (A) and (B) are characterized in that they do not satisfy the following equation (C).

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[0027] According to this embodiment, by failing to satisfy equation (C) in the conditional equation based on yield line theory, the steel beam is positioned at an eccentric position different from the lateral center position of the steel plate, thereby providing a column-beam joint structure with sufficient structural strength. [Effects of the Invention]

[0028] As can be understood from the above explanation, the column-beam joint structure of the present invention relates to a column-beam joint structure in which a steel column is welded to the lower end of the panel core, a steel column is not welded to the upper end, and a steel beam is welded to the side. By reducing the excess length of the steel plate forming the panel core, it is possible to reduce manufacturing costs. [Brief explanation of the drawing]

[0029] [Figure 1] This is a perspective view showing an example of a panel core and an internal diaphragm, disassembled, that form a column-beam joint structure according to the embodiment. [Figure 2] This is a view from the direction of arrow II in Figure 1. [Figure 3] This is a perspective view of an example of a column-beam joint structure according to the embodiment. [Figure 4] This is a view from the arrow pointing in direction IV in Figure 3. [Figure 5] Figure 3 is a cross-sectional view of the VV section. [Figure 6] This is a diagram illustrating the out-of-plane bending yield mechanism. [Modes for carrying out the invention]

[0030] The column-beam joint structure according to the embodiment will be described below with reference to the attached drawings. In this specification and the drawings, substantially identical components may be denoted by the same reference numerals to avoid redundant explanations.

[0031] [Column-beam joint structure according to an embodiment] An example of a column-beam joint structure according to the embodiment will be described with reference to Figures 1 to 6. Here, Figure 1 is a perspective view showing an example of a panel core and an internal diaphragm formed in the column-beam joint structure according to the embodiment, and Figure 2 is a view taken in the direction of arrow II in Figure 1. Figure 3 is a perspective view of an example of a column-beam joint structure according to the embodiment, and Figures 4 and 5 are a view taken in the direction of arrow IV and VV in Figure 3, respectively. Furthermore, Figure 6 is a diagram illustrating the out-of-plane bending yield mechanism.

[0032] The steel panel core 10 is formed from a total of four steel plates 1 and 2, two of each with different widths. At both ends of the relatively short steel plate 2, a tapered groove 2a with an inclination angle of approximately 20 to 50 degrees is formed along the extension direction of the steel plate 2. The long steel plate 1 and the short steel plate 2 are arranged as shown in Figure 1, and backing plates 4 are placed inside the four corners along the short steel plate 2. Welds 3 are formed in the grooves 2a, forming a hollow, rectangular prism-shaped steel panel core 10 (a four-sided box).

[0033] As shown in Figure 2, the planar shape of the panel core 10 is a square with side length Dp. However, depending on the cross-sectional shape of the lower column joined to the lower end 14 of the panel core 10, the panel core may have a shape other than a square, for example, a rectangular planar shape.

[0034] Furthermore, an internal diaphragm 6 is fitted in the X direction and welded into the interior of the upper end 12 of the panel core 10 in the illustrated example. The thickness tp of the steel plates 1 and 2 that form the panel core 10 is thicker than that of a typical panel core with multiple diaphragms, and this thickness tp will be explained in detail below.

[0035] The welded joint 3 can be formed using various welding methods, including other arc welding methods such as arc spot welding, arc stud welding, gas shielded arc welding, and plasma welding, as well as electroslag welding, electron beam welding, and laser beam welding. However, the submerged arc welded joint 3 is formed using submerged arc welding, which offers the best balance of manufacturing efficiency and quality.

[0036] Submerged arc welding is a welding method in which granular flux is scattered along the weld line, a solid wire is continuously supplied through it, and an arc is generated between the base metal and the wire while they are covered in flux, melting both and joining them together.

[0037] Submerged arc welding is more than ten times more efficient than conventional manual welding because it uses a large diameter wire and a large current. Furthermore, it generally penetrates deeply, resulting in stable weld quality, a uniform and aesthetically pleasing bead appearance, and the formation of highly reliable welded joints. For example, it is possible to manufacture panel cores 10 as shown in Figure 1 continuously by producing pieces several times longer than the panel core 10 shown in Figure 1 and then cutting them. This manufacturing method allows for even more efficient production of panel cores 10.

[0038] The panel core 10, a hollow rectangular prism with a square shape in plan view, is formed by joining four thick steel plates 1 and 2 together at submerged arc welds 3. This panel core is extremely rigid and has good manufacturing efficiency. Furthermore, by adjusting the width, length, and thickness of the steel plates 1 and 2 as desired, panel cores of various shapes and dimensions can be obtained.

[0039] Furthermore, as explained below, in designing the plate thickness of the steel plates 1 and 2 forming the panel core 10 in the illustrated example based on their out-of-plane bending strength, the bending strength of the steel column 20 (see Figure 3) welded to the panel core 10 is included (considered). Therefore, the plate thickness is thicker than that set based on a design that does not consider the bending strength of the steel column 20.

[0040] Furthermore, the excess length of the excess portion 40 (see Figure 5) between the lower ends of the steel plates 1 and 2 and the lower end of the steel beam 30 (see Figure 3) welded to the steel plates 1 and 2 is shorter than the excess length of the excess portion set based on a design that does not take into account the bending strength of the steel column 20.

[0041] Thus, in the design based on the out-of-plane bending strength of the steel plates 1 and 2, the steel columns 20 are taken into consideration, and the presence of the excess length portion 40 allows the plate thickness of the steel plates 1 and 2 to be made as thin as possible, although still thicker than the plate thickness of the steel columns 20, and the excess length of the excess portion between the upper or lower ends of both the steel plates 1 and 2 and the steel beam 30 can be made as short as possible. As a result, the material cost of the steel plates 1 and 2 can be reduced, and the manufacturing cost of the panel core 10 can be reduced.

[0042] Since the panel core 10 is equipped with an internal diaphragm 6 only at its upper end and does not have an internal diaphragm inside, concrete can be easily filled into the panel core 10, for example, when taking measures to further increase its rigidity by filling it with concrete.

[0043] Although not shown in the diagram, a panel core with the same shape and dimensions as the panel core 10 shown in Figure 1 can also be obtained by using four steel plates of the same type, each steel plate having a groove at only one end, and welding the grooves together with the sides of adjacent steel plates.

[0044] In the column-beam joint structure 100, steel beams 30 made of H-shaped steel are welded to each steel plate 2 of the panel core 10 that forms the panel zone, and square steel pipes of the same cross-sectional shape that form the lower columns 20 are welded to the lower end 14 of the panel core 10. Here, the illustrated example shows a configuration in which a steel beam 30 is joined to only one steel plate 2, but it is also possible to have a configuration in which a steel beam 30 is joined to the other steel plates 1, 2 as well. Furthermore, although not shown in the illustration, the web 31 of the steel beam 30 is connected to each steel plate 1, 2 by fillet welding, and the flanges 32, 33 are connected by full penetration welding. In addition, the steel columns 20 made of square steel pipes are also connected to the end faces of each steel plate 1, 2 by full penetration welding.

[0045] In other words, the column-beam joint structure 100 in the illustrated example does not have steel columns above the panel core 10, and is a column-beam joint structure that supports a large space such as a lobby on an intermediate floor, or the top floor of a building.

[0046] Here, the diaphragm provided at the upper end of the panel core 10 may be a through diaphragm 6A as shown in Figure 6, instead of the inner diaphragm 6 in the illustrated example.

[0047] As shown in Figure 4, the overall dimensions of both the panel core 10 and the steel column 20, as well as the plate thickness tp of the steel plates 1 and 2, are set such that the cross-section of the steel column 20 is completely contained within the cross-section of the panel core 10.

[0048] The plate thickness tp of steel plates 1 and 2 is such that the cross-section of the steel column 20 is completely accommodated, and is greater than the thickness tc of the steel column 20. Also, as shown in Figure 4, the steel column 20 has curved sections (R sections) with a radius of curvature r at all four corners, and is a steel pipe column that is square in plan view with side length Dp.

[0049] For square steel pipes 20, cold-formed square steel pipes for building structures, such as BCR (Box Column Roll, registered trademark) and BCP (Box Column Press, registered trademark), are used. These are square steel pipes manufactured by the Iron and Steel Federation of Japan, based on SN material (building structural steel). In addition, square steel pipes 20 can also be made from JIS products based on JIS G 3466 (square steel pipes for general structural use), such as STKR400 and STKR490.

[0050] Since the entire cross-section of the rectangular steel pipe 20, which has rounded corners in a typical configuration, is completely housed within the cross-section of the panel core 10, axial force, bending, and other forces from the rectangular steel pipe 20 can be effectively transmitted to the panel core 10.

[0051] As shown in Figure 5, the column-beam joint structure 100 is formed by welding the upper flange 32 of a steel beam 30 made of H-shaped steel to a position corresponding to the inner diaphragm 6 on the steel plate 2, making the upper surface 34 of the upper flange 32 and the upper surface of the upper flange 6 flush, welding the web 31 and the lower flange 33 to the steel plate, and welding the lower column 20, which is a steel column, to the lower end 14 of the panel core 10.

[0052] In the illustrated example of the column-beam joint structure 100, the steel beam 30 is aligned with the lateral center of the steel plate 2 of the panel core 10. However, the steel beam 30 may be positioned at an eccentric location different from the lateral center of the steel plate 2.

[0053] The height of the panel core 10 is set higher than the beam depth of the steel beam 30, and an excess length portion 40 of excess length lp is provided between the lower flange 33 of the steel beam 30 and the lower end 14 of the panel core 10.

[0054] Thus, when there is an excess length lp between the panel core 10 and the steel beam 30, this excess length lp satisfies the yield bending strength formula based on yield line theory, thereby enabling a rigid connection between the panel core 10 and the steel beam 30.

[0055] Furthermore, although not shown in the diagram, if seismic reinforcement braces (buckling-restrained braces) are present within the steel frame structure, these seismic reinforcement braces can be connected to the excess length section 40. This eliminates the need to connect the seismic reinforcement braces to the steel column 20 while simultaneously implementing reinforcement measures for the steel column 20 when the excess length section 40 is not present.

[0056] [Method for setting panel core thickness based on yield line theory] In designing the plate thickness tp of the steel plates 1 and 2 of the panel core 10 (four-sided box) that forms the column-beam joint structure 100, the plate thickness is set to satisfy the following two conditional equations (Q1) and (Q2) based on yield line theory, including the bending strength of the steel column 20. Here, in the illustrated example model, a through diaphragm 6A is welded to the upper end of the panel core 10, and the steel beam 30 is joined to the panel core 10 by welding the upper flange 32 of the steel beam 30 to the through diaphragm 6A.

[0057] Conditional equation (Q1) is an equation that satisfies the condition that the out-of-plane bending yield strength is equal to or greater than the yield bending moment of the beam, and conditional equation (Q2) is an equation that satisfies the condition that the out-of-plane bending maximum strength is equal to or greater than the product of the beam's full plastic bending moment and the joint coefficient (ultimate strength). Determine the plate thickness that satisfies both conditions, and set the plate thickness of steel plates 1 and 2 to be equal to or greater than the calculated plate thickness.

[0058]

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[0059] To determine these two conditions, calculations based on yield line theory are performed. Here, Figure 6 illustrates the out-of-plane bending yield mechanism, where Figure 6(a) is a front view of the panel core seen from the steel beam side, Figure 6(b) is a top view of the panel core seen from above, and Figure 6(c) is a side view of the panel core seen from the side.

[0060] In equations (Q1) and (Q2) above, the right-hand side of each equation is the product of the yield bending moment of the steel beam, the full plastic bending moment, and the joint coefficient (ultimate strength). Equations (Q1) and (Q2) are conditional equations that the sum of the bending strengths of the steel beam and the panel core is greater than the yield bending moment or full plastic moment of the steel beam. The left-hand side of equations (Q1) and (Q2) includes the plate thickness tp of the steel plates 1 and 2 that form the panel core 10. The thickness of the panel core 10 is determined by finding the plate thickness tp that satisfies both of these equations.

[0061] In the above equations (Q1) and (Q2), if the steel beam 30 is aligned with the lateral center position of the steel plates 1 and 2, then the following equation (Q3) shall be satisfied in the conditions of equations (Q1) and (Q2). If the steel beam 30 is positioned at an eccentric position different from the lateral center position of the steel plates 1 and 2, then the following equation (Q3) shall not be satisfied in the conditions of equations (Q1) and (Q2).

[0062]

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[0063] Whether the steel beam 30 is aligned horizontally with the steel plates 1 and 2 or is eccentrically aligned horizontally, by taking into account the yield strength of the steel column 20, it becomes possible to set the plate thickness tp of the steel plates 1 and 2 to be thinner while satisfying the two conditional equations.

[0064] Furthermore, in setting the excess length lp of the excess length portion 40 of the panel core 10, consider the case in Figure 6 where the yield line AA' occurs on the steel column 20 side of the boundary between the steel panel core 10 and the steel column 20. Determine the yield bending moment of the steel panel core 10 and the steel column 20 per unit length of the yield line AA' and calculate the excess length lp.

[0065] In calculating this excess length lp, by taking into account the yield strength of the steel column 20, it becomes possible to set the excess length l of the excess section to a shorter length.

[0066] In the column-beam joint structure 100 equipped with the excess length portion 40 of the excess length lp set in this manner, the joint structure between the panel core 10 and each steel beam 30 can be made rigid, and furthermore, the presence of the excess length lp makes it possible to make the plate thickness of the panel core 10 relatively thinner compared to the case without the excess length.

[0067] Furthermore, 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]

[0068] 1,2: Steel plate 2a: Bevel 3: Welded joint (submerged arc weld) 4: Backing metal 6: Internal diaphragm (diaphragm) 6A: Through diaphragm (diaphragm) 10: Panel core (4-sided box) 11: Side view 12:Top edge 14: Bottom edge 20: Steel columns (lower columns, square steel pipes) 30: Steel beam (H type steel) 31: Web 32: Upper flange 33: Lower flange (flange) 34:Top surface 40:Extra length 100: Column beam joint structure

Claims

1. A through diaphragm is welded to the upper end of the panel core of a four-sided box, which is made up of four steel plates welded together. The upper end of the steel column is welded to the lower end of the four-sided box. The upper flange of the steel beam, which is made of H-shaped steel, is welded to the through diaphragm, and the web and lower flange are welded to the steel plate. The steel column is not joined to the upper surface of the aforementioned through diaphragm. The core depth of the panel core is greater than the beam depth of the steel beam, and there is an excess length between the lower end of the panel core and the lower end of the steel beam. A column-beam joint structure characterized in that the design of the plate thickness based on the out-of-plane bending strength of the steel plate includes the bending strength of the steel column.

2. An internal diaphragm is welded to the upper end of the panel core of a four-sided box, which is made up of four steel plates welded together. The upper end of the steel column is welded to the lower end of the four-sided box. The upper flange of the steel beam, which is made of H-shaped steel, is welded to the steel plate at a position corresponding to the inner diaphragm, and the web and lower flange are welded to the steel plate. The steel column is not joined to the upper surface of the inner diaphragm. The core depth of the panel core is greater than the beam depth of the steel beam, and there is an excess length between the lower end of the panel core and the lower end of the steel beam. A column-beam joint structure characterized in that the design of the plate thickness based on the out-of-plane bending strength of the steel plate includes the bending strength of the steel column.

3. The aforementioned steel columns are formed from square steel pipes, The column-beam joint structure according to claim 1 or 2, characterized in that the rectangular steel pipe is located inside the thickness of the panel core.

4. The column-beam joint structure according to claim 2, characterized in that the plate thickness tp of the steel plate satisfies the following two conditional equations (A) and (B) based on yield line theory. [Math 1]

5. When the steel beam is aligned with the lateral center of the steel plate, The column-beam joint structure according to claim 4, characterized in that the following formula (C) is satisfied in the above-mentioned conditional formulas (A) and (B). [Math 2]

6. When the steel beam is positioned at an eccentric location different from the lateral center of the steel plate, The column-beam joint structure according to claim 4, characterized in that the following equation (C) is not satisfied in the above-mentioned conditional equations (A) and (B). [Math 2]

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