Column-beam joint construction

Abstract

To improve design and inhibit bearing strength from reducing.SOLUTION: A beam has flanges that are connected to a column. The aforesaid flange comprises, in a specific range extending from the part to be connected to the aforesaid column along the longitudinal direction of the aforesaid beam, a first widening part in which the flange width of one side in the width direction crossing the aforesaid longitudinal direction is widened, and in the aforesaid specific range, a second widening part in which the flange width of the other side in the aforesaid width direction is widened. When the proportion of the aforesaid first widening part to the sum value of the width of the aforesaid first widening part and the width of the aforesaid second widening part is x%, and the shear span ratio that is a ratio between a shear span and a beam depth is L / D, the aforesaid shear span ratio L / D of 3 or more and less than 4.5 yields {-10×(L / D)+45}≤x<50, while the aforesaid shear span ratio L / D of 4.5 or more yields 0<x<50.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to Column beam joint structure .

Background Art

[0002] At the joint between a beam and a column (hereinafter also referred to as the beam end joint), large stress may be generated due to external forces such as earthquakes and cause breakage. Therefore, a structure is known in which the width of the beam end of the flange of the beam is widened to reduce the stress at the beam end joint. Usually, a beam provided with widened portions of the same width on both left and right sides (hereinafter also referred to as a same-width haunch beam) is joined with the axis aligned with the column.

[0003] Also, due to reasons in the structural plan, there may be cases where the beam is joined eccentrically with respect to the column. In this case, when applying a same-width haunch beam, since widened portions are provided on both sides of the beam, even if the beam is made eccentric, for example, a large amount of space is required between the beam and the outer wall, which is not preferable in terms of design. Therefore, a beam provided with a widened portion only on one side (hereinafter also referred to as a one-sided haunch beam) has been proposed (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] One-sided haunch beams are prone to torsion, and depending on the dimensions of the beam, the yield strength is significantly reduced. In order to ensure the same yield strength as that of a same-width haunch beam, it is necessary to increase the cross-section of the flange more than that of the same-width haunch beam, which requires a large amount of steel.

[0006] The present invention has been made in view of such problems, and an object thereof is to improve the designability and suppress the reduction of strength.

Means for Solving the Problem

[0007] The main invention for achieving such an object is The column and the aforementioned a beam having a flange joined to a column A column-beam joint structure in which the two are joined. wherein the flange has a first widened portion in a predetermined range along the longitudinal direction of the beam from the joint with the column, where the width of the flange on one side in the width direction intersecting the longitudinal direction is widened, and a second widened portion in the predetermined range, where the width of the flange on the other side in the width direction is widened, and has when the ratio of the width of the first widened portion to the sum of the width of the first widened portion and the width of the second widened portion is x%, and the shear span ratio, which is the ratio of the shear span to the beam depth, is L / D, when the shear span ratio L / D is 3 or more and less than 4.5, {-10×(L / D)+45}≦x<50, and when the shear span ratio L / D is 4.5 or more, 0<x<50 can be, The beam is provided eccentrically to one side in the width direction relative to the column. It is characterized by this.

[0008] Other features of the present invention will be clarified by the description in this specification and the accompanying drawings.

Advantages of the Invention

[0009] According to the present invention, it is possible to improve the designability and suppress the decrease in the yield strength.

Brief Description of the Drawings

[0010] [Figure 1] Fig. 1A is a top view of the column-beam joint structure of the present embodiment, and Fig. 1B is a perspective view of the column-beam joint structure. [Figure 2] It is an explanatory view of the shape (hunch sharing ratio) of the widened portion. [Figure 3] It is an explanatory view of the analysis model. [Figure 4] It is a figure showing an example of the stress distribution by analysis. [Figure 5] Figures 5A to 5E are figures showing the relationship between the load Q and the deformation δ. [Figure 6] Figures 6A to 6E are figures showing the relationship between the ratio (aQy / cQy) of the analytical value aQy and the calculated value cQy of the yield strength and the hunch sharing ratio x. [Figure 7] It is an explanatory diagram of the range where the analytical value of the yield strength exceeds the calculated value.

Mode for Carrying Out the Invention

[0011] At least the following matters become clear from this specification and the attached drawings.

[0012] A beam having a flange joined to a column, wherein the flange has a first widened portion in a predetermined range along the longitudinal direction of the beam from the joint with the column, where the flange width on one side in the width direction intersecting the longitudinal direction is widened, and a second widened portion in the predetermined range, where the flange width on the other side in the width direction is widened, and when the ratio of the width of the first widened portion to the sum of the width of the first widened portion and the width of the second widened portion is x%, and the shear span ratio, which is the ratio of the shear span to the beam depth, is L / D, when the shear span ratio L / D is 3 or more and less than 4.5, {-10×(L / D)+45}≦x<50, and when the shear span ratio L / D is 4.5 or more, 0<x<50. A beam characterized by this.

[0013] According to such a beam, it is possible to improve the designability and suppress the decrease in strength.

[0014] Such a beam, it is desirable that a diaphragm for widening the width of the column is provided on the column, and the flange is joined to the small end surface of the diaphragm.

[0015] According to such a beam, it is possible to make it more eccentric compared to the case of joining to the column body.

[0016] Such a beam is preferably connected within the width of the column and has a web perpendicular to the flange.

[0017] Such a beam can withstand shear forces.

[0018] In such a beam, it is preferable that the web is located in the center of the flange width of the flange.

[0019] With such a beam, it becomes easier to evaluate the effects of providing the first and second widening sections.

[0020] In such a beam, it is desirable that the end opposite to the joint within the predetermined range yields first, and then the joint yields.

[0021] Such beams can protect the joints.

[0022] Furthermore, a column-beam joint structure comprising the beam described above, characterized in that the column and the beam are joined together.

[0023] This type of column-beam joint structure allows for improved aesthetics and suppression of a decrease in load-bearing capacity.

[0024] In such a column-beam joint structure, it is desirable that the beam is provided eccentrically with respect to the column on one side in the width direction.

[0025] This type of column-beam joint structure is more effective because, for example, it can reduce the space between the exterior wall and the beam.

[0026] The following describes one embodiment of the present invention with reference to the drawings.

[0027] ===Execution=== <About column-beam connection structures> Figure 1A is a top view of the column-beam joint structure of this embodiment, and Figure 1B is a perspective view of the column-beam joint structure. Both figures show a portion of the frame consisting of columns and beams.

[0028] The column-beam joint structure of this embodiment is composed of a column 10 and a beam 20. Of the directions intersecting the vertical direction (horizontal direction), the direction along the longitudinal direction of the beam 20 is defined as the beam longitudinal direction (corresponding to the longitudinal direction), and the direction along the width direction of the beam 20 is defined as the beam width direction (corresponding to the width direction).

[0029] Column 10 is a vertical structural member that supports floors, beams, etc., in a structural building. As shown in the figure, column 10 in this embodiment is a square steel pipe. Column 10 also has a diaphragm 12.

[0030] The diaphragm 12 is a steel plate that increases the rigidity of the joint of the column 10. In this embodiment, the diaphragm 12 is a so-called through diaphragm, and is made by cutting the square steel pipe that makes up the column 10, sandwiching it between the sections, and welding them together. The diaphragm 12 also protrudes outward around the column 10. In other words, the diaphragm 12 widens the width of the column 10. A pair of diaphragms 12 are provided, one above the other, at positions corresponding to the flange 24 of the beam 20.

[0031] The beam 20 is a structural member that connects columns horizontally in a structural building. In this embodiment, the beam 20 is joined eccentrically to one side in the beam width direction with respect to the center of the column 10 (specifically, the side on which the widened portion 24a, described later, is formed).

[0032] As shown in Figures 1A and 1B, let L be the length of the beam 20 in the longitudinal direction (shear span), and let D be the depth of the beam 20. In the following explanation, the ratio of the shear span L to the beam depth D is called the shear span ratio L / D.

[0033] The shear span L is the length of a member for which the shear force can be considered constant, and is defined as the distance from the beam end joint to the inflection point (not shown) of the beam 20.

[0034] As shown in the figure, the beam 20 is an iron steel material (so-called H-beam) with an H-shaped cross-section perpendicular to the longitudinal direction of the beam, and has a web 22 and a flange 24.

[0035] The web 22 is a plate-like member connecting the upper and lower flanges 24 and is perpendicular to the upper and lower flanges 24. The web 22 is also joined to the column 10. Alternatively, a gusset plate (not shown) may be provided on the column 10, and the gusset plate and the web 22 may be joined by bolts and nuts. The web 22 can bear shear force. The web 22 is also located in the center of the flange width (flange width B, described later) of the flange 24. This makes it easier to evaluate the effects of the widened sections 24a and 24b, described later. The thickness of the web 22 is t w Let's assume that.

[0036] The flanges 24 are plate-shaped members positioned at the upper and lower edges of the beam 20, respectively. The longitudinal ends of the flanges 24 are welded to the end faces of the diaphragm 12 of the column 10. This joint (in this case, the joint with the diaphragm 12) is also called the beam end joint (or haunch base). As mentioned above, the diaphragm 12 widens the column width of the column 10. Therefore, by joining the flanges 24 to the diaphragm 12, greater eccentricity can be achieved compared to joining them to the column 10 body.

[0037] Furthermore, the flange 24 extends in a predetermined range along the longitudinal direction of the beam from the beam end joint (L in Figure 1A). h The flange 24 has widened sections 24a and 24b within the range indicated by (length L). h Within the specified range, the position corresponding to the end opposite to the haunch base end (the widening start position) is also called the haunch tip.

[0038] As shown in Figure 1A, outside the above-mentioned predetermined range (LL hIn the part of , the width of the flange 24 is constant, and the width of the flange 24 (corresponding to the flange width) is denoted as B. Also, the thickness of the flange 24 is t f is denoted as

[0039] The widened part 24a (corresponding to the first widened part) is provided on one side in the beam width direction of the flange 24 within the above-mentioned predetermined range, and widens the flange width on the one side of the flange 24. As shown in Fig. 1A, the width (maximum width) of the widened part 24a is B h1 . Specifically, from the hunch tip, as it goes toward the column 10, the width of the widened part 24a becomes wider and reaches the width B h1 .

[0040] The widened part 24b (corresponding to the second widened part) is provided on the other side in the beam width direction of the flange 24 within the above-mentioned predetermined range, and widens the flange width on the other side of the flange 24. As shown in Fig. 1A, the width (maximum width) of the widened part 24b is B h2 . Specifically, from the hunch tip, as it goes toward the column 10, the width of the widened part 24b becomes wider and reaches the width B h2 .

[0041] As shown in Fig. 1A, in the beam 20 (flange 24) of this embodiment, the width B of the widened part 24b h2 and the width B of the widened part 24a h1 are different, and the width B of the widened part 24a h1 is smaller than the width B of the widened part 24b h2 (B h1 < B h2 ). Also, if the total width of the widened part (hereinafter also referred to as the widened part width) is B h (= B h1 + B h2 ), then the width BH of the hunch base end of the flange 24 is BH = B + B h using the flange width B and the widened part width B h .

[0042] Note that, with respect to the widened part width B h (corresponding to the added value), the width B of the widened part 24a h1This proportion is also called the haunch share x (%), and in this embodiment, the conditions are defined as follows.

[0043] If the shear span ratio L / D is 3 or more and less than 4.5, {-10 × (L / D) + 45} ≤ x < 50 If the shear span ratio L / D is 4.5 or greater, 0 <x<50 As a result, as will be described later, it is possible to improve the aesthetic appearance and suppress the decrease in structural strength.

[0044] ===Regarding the design and evaluation of beam 20=== Next, the design and evaluation of the beam 20 in this embodiment will be described.

[0045] <<Regarding the shape of the widened section (haunch distribution ratio)>> Figure 2 is an explanatory diagram of the shape of the widened section (haunch distribution).

[0046] The beam shown on the left side of Figure 2 has widened sections on both sides of the flange with equal width (50% on each side). Hereafter, such beams (beams with widened sections on both sides of the flange with equal width) will be called equal-width haunch beams, or simply equal-width haunches. The beam shown on the right side of Figure 2 has a widened section on only one side of the flange (0% on each side). Hereafter, such beams will be called single-sided haunch beams, or simply single-sided haunches.

[0047] In this embodiment, as shown in the center of Figure 2, the widths of the widened sections (widened sections 24a, 24b) on both sides of the flange 24 are made different. In the following description, such a beam will be referred to as a haunch beam with varying widths, or simply as a haunch with varying widths.

[0048] In the haunches of the same width, different widths, and one-sided configurations shown in Figure 2, the joint position between the column 10 and the web 22 is the same in all cases (eccentric with respect to the center of the column 10). However, the joint between the flange 24 (specifically the widened sections 24a and 24b) and the diaphragm 12 differs in each case. Specifically, since the widths of the widened sections 24a and 24b differ in the haunches of the same width, different widths, and one-sided configurations, the width of the diaphragm 12 (length in the beam width direction) is changed to allow connection with the entire flange. For example, in the haunches of the same width, the width of the diaphragm 12 in the beam width direction (amount protruding from the column 10) is the largest, while in the haunches of one-sided configurations, the width of the diaphragm 12 (amount protruding from the column 10) is the smallest.

[0049] As shown in Figure 2, if the beam is eccentrically positioned relative to the column, for example, near the exterior wall, a haunch of equal width would require a lot of space between the beam and the exterior wall because widened sections are provided on both sides, which is undesirable from an aesthetic standpoint. On the other hand, a haunch on one side allows for a compact installation, but it is prone to twisting, which may reduce its yield strength.

[0050] Therefore, in this embodiment, by using haunches of varying widths, we aim to improve the aesthetic appearance and suppress the reduction in load-bearing capacity.

[0051] As shown in Figure 2, the width B of the widened section 24a h1 If we let this be x%, then the width B of the widened section 24b is h2 This becomes (100-x)%. For example, width B h1 If it is 20%, the width B of the widened section 24b h2 This becomes 80%, width B h1 and width B h2 The sum of the values ​​(widening section width B) h Width B for ) h1 The ratio is 20 / (20+80) = 1 / 5.

[0052] Below, the width of the widened section B h Width B h1 We conducted an analysis (FEM analysis) using the proportion of haunch contribution (x%) as a parameter to confirm the effect of the haunch contribution on bearing capacity.

[0053] <<About the analysis conditions>> The conditions for the analysis are shown below. Note that the unit of length (including width, thickness, etc.) is mm. • Beam shape: Horizontal haunch beam (see Figure 2) ·Column cross section: □-600×600×32 • Beam section (beam depth D, flange width B, web thickness t) w , flange thickness t f ) Cross section a: H-600×200×19×25 (SN490B) Cross section b: H-600×200×12×25 (SN490B) Cross section c: H-600×200×7.5×25(SN490B) • Beam eccentricity: Yes (eccentricity amount 0.33Dc (Dc: column diameter)) • Haunch distribution ratio (x%): 0 (one side), 5, 10, 15, 20, 30, 40, 50 (same width) • Widening section length L h :300 (=0.5D) • Widening section width B h With the haunch tip as the critical cross-section (the point where yielding occurs first), the widened section width B is set such that the full plastic bending strength at the base of the haunch, considering the moment gradient, is 1.2 times that of the full plastic bending strength at the haunch tip. h The design was created to ensure that the full plastic bending strength at the base of the haunch is 1.2 times that of the haunch tip, which is generally 490 N / mm². 2 Steel beams using graded steel (such as SN490B) are expected to have a 1.2 times increase in strength (see "National Institute for Land and Infrastructure Management, Ministry of Land, Infrastructure, Transport and Tourism, et al.: Commentary on Technical Standards for Structural Structures of Buildings, 2020 Edition"). Furthermore, it is desirable to design the beam so that the load at which the full plastic bending strength of the haunch base is reached is at least 1.2 times the load at which the full plastic bending strength of the haunch tip is reached. This prevents yielding at the haunch base with a load at least 1.2 times the load at the tip after yielding. Thus, failure at the haunch base can be prevented (the haunch base is protected).

[0054] Below, the width of the widened section B h This document outlines the specific design procedure.

[0055] Full plastic bending strength M of the flange at the base end of the haunch f This can be expressed by the following equation (1). M f =BH×t f × (Dt f ) × σy ·····(1) Here, BH: Haunch base width t f Flange thickness σy: Yield point or proof strength

[0056] Furthermore, the required bending strength M of the haunch base. fd This can be expressed by the following equation (2). M fd =α×M p ×L / (LL h ) × σy ·····(2) Here, α: rate of increase in bearing capacity (=1.2) M p Full plastic bending strength Z at the tip of the haunch p ×σy Z p Plasticity coefficient of the haunch tip

[0057] From equations (1) and (2), the fully plastic bending strength M of the flange at the base end of the haunch is obtained. f And the required bending strength M at the base end of the haunch. fd The ratio M f / M fd The widened section width B should be approximately 1.0. h We made that decision.

[0058] <<About the analysis model>> Figure 3 is a schematic diagram of the analysis model. The figure shows a haunch beam of different widths (in this embodiment), but the same model was used for haunch beams of the same width and haunch beams on one side.

[0059] <Analysis Model> • T-shaped frame (column length: 3000mm, beam length: span L)

[0060] <Cross-sectional quantities> Beam depth D (mm): 600 · Shear span L (mm): 1800, 2400, 2700, 3000, 3600 · Shear span ratio L / D: 3, 4, 4.5, 5, 6 · Diaphragm: Plate thickness 32 mm (protrusion dimension 25 mm)

[0061] <Analysis elements> · As the first quadrilateral shell elements, the beam flange within a range of 1200 mm from the beam end connection is mesh-divided at a pitch of 10 mm, and the others are divided at a pitch of 50 mm.

[0062] <Boundary conditions> · Column: The upper and lower ends restrain displacement and rotation around the z-axis. · Beam: The y-direction ends (beam ends) restrain rotation around the y-axis and z-axis, and a forced displacement is applied in the z-direction. In addition, the displacement of the beam in the x-direction is restrained at a position 1200 mm from the beam end connection so that the beam does not undergo lateral buckling.

[0063] Note that the x-direction corresponds to the beam width direction in Figure 1, the y-direction corresponds to the beam longitudinal direction in Figure 1, and the z-direction corresponds to the vertical direction in Figure 1.

[0064] [[ID=了26]] <<Regarding the analysis results>> Figures 4A to 4C are diagrams showing an example of the stress distribution obtained by analysis. Each figure shows the von Mises stress distribution at the yield strength analytical value aQy of the cross-section b (H-600×200×12×25). Figure 4A shows the result at x = 50%, Figure 4B shows the result at x = 20%, and Figure 4C shows the result at x = 0%.

[0065] From Figures 4A to 4C, the following can be confirmed. · At x = 50% (equal-width haunch beam), stress occurs evenly on both sides of the beam. · At x = 0% (one-sided haunch beam), stress concentrates on either the left or right side of the beam. · When 0 < x < 50 (unequal-width haunch beam), it shows an intermediate tendency between the equal-width haunch beam and the one-sided haunch beam.

[0066] Figures 5A to 5E show the relationship between load Q and deformation δ. Figures 5A to 5E show the cases where the shear span ratio L / D is 3, 4, 4.5, 5, and 6, respectively. Here again, the analysis results for section b (H-600×200×12×25) are shown, and the figures for sections a and c are omitted.

[0067] The analytical yield strength value aQy was defined as the load at which the tangential stiffness in the load-deformation-δ relationship decreased to 1 / 3 of the initial stiffness (see "Building Research Institute, Japan Iron and Steel Federation: Research Committee Report on Structural Performance Evaluation Test Methods for Steel Structures, April 2002"). This method allows for the determination of yield strength if the load-deformation relationship is obtained, thus enabling a unified evaluation. However, the method for determining yield strength is not limited to the above.

[0068] Furthermore, the dashed line in the figure represents the calculated yield strength cQy (equivalent to the design value) when the haunch tip is considered a critical cross-section, and was calculated using the following equation (3). cQy=cMy / (LL h ) ·····(3) Here, cMy: Calculated yield bending moment of a uniform cross-section of a beam L: Shear span of the beam L h : Widening section length A uniform cross-sectional area of ​​a beam refers to a portion of the beam where the cross-sectional shape perpendicular to the longitudinal direction of the beam is the same (in this embodiment, a portion where a widened section is not formed on the flange).

[0069] The following can be confirmed from Figures 5A to 5E. The smaller the haunch contribution ratio x, the smaller the yield strength in the load-deformation-δ relationship. • A smaller shear span ratio L / D results in a larger difference in the load-deformation-δ relationship due to differences in the haunch distribution ratio x.

[0070] For each shear span ratio L / D, the relationship between the haunch contribution ratio x and the beam's yield strength (analytical value aQy: load when tangential stiffness decreases to 1 / 3 of initial stiffness) was determined from the load Q-deformation δ relationship.

[0071] Figures 6A to 6E show the relationship between the ratio of the analytical yield strength aQy to the calculated yield strength cQy (aQy / cQy) and the haunch contribution ratio x. In each figure, the horizontal axis represents the haunch contribution ratio x%, and the vertical axis represents the ratio of the analytical yield strength aQy to the calculated yield strength cQy (aQy / cQy).

[0072] Figures 6A to 6E show the results for shear span ratios L / D of 3, 4, 4.5, 5, and 6, respectively. Each figure also shows the results for sections a, b, and c, respectively. If the vertical axis (aQy / cQy) is greater than 1 (i.e., the analytical yield strength value aQy exceeds the calculated value cQy), then it can be said that a reduction in the calculated strength is not necessary.

[0073] The following can be confirmed from Figures 6A to 6E. The smaller the haunch contribution ratio x, the smaller the ratio (aQy / cQy) between the analytical value aQy and the calculated value cQy, and the lower the yield strength. When the shear span ratio L / D=3, the analytical yield strength value aQy is lower than the calculated value cQy at x=10%. On the other hand, at x=15% or higher, the analytical yield strength value aQy is higher than the calculated value cQy. When the shear span ratio L / D=4, the analytical yield strength value aQy is lower than the calculated value cQy at x=0%. On the other hand, at x=5% or higher, the analytical yield strength value aQy is higher than the calculated value cQy. • When the shear span ratio L / D = 4.5, 5, or 6, even at x = 0%, the analytical yield strength value aQy exceeds the calculated value cQy.

[0074] Furthermore, when the shear span ratio L / D falls within the conditions of this embodiment, the haunch distribution ratio x% (lower limit) can be determined by interpolation (e.g., linear interpolation) of results for nearby shear span ratios L / D. For example, when the shear span ratio L / D is 3.5, it can be determined by linear interpolation between the lower limit of the haunch distribution ratio x when the shear span ratio L / D is 3 and the lower limit of the haunch distribution ratio x when the shear span ratio L / D is 4.

[0075] Figure 7 is an explanatory diagram of the range where the analytical yield strength value aQy exceeds the calculated value cQy. The horizontal axis of the figure represents the shear span ratio L / D, and the vertical axis represents the haunch contribution ratio x (%). Areas where a reduction in calculated strength is not confirmed are hatched with diagonal lines. Areas that are not hatched are areas where a reduction in calculated strength is confirmed to be necessary (L / D ≥ 3), or areas that have not been considered (L / D < 3).

[0076] From Figure 7, the conditions under which a reduction in calculated load-bearing capacity is unnecessary are: • If the shear span ratio L / D is 3 or more and less than 4.5 (3 ≤ L / D < 4.5), {-10 × (L / D) + 45} ≤ x < 50 • If the shear span ratio L / D is 4.5 or greater (L / D ≥ 4.5), 0 <x<50 That's what happened.

[0077] In other words, by determining the shear span ratio L / D and the haunch contribution ratio x so as to satisfy the above relationship, it is possible to improve the aesthetic appearance and suppress the reduction in load-bearing capacity.

[0078] ===Regarding other embodiments=== The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit its interpretation. The present invention can be modified and improved without departing from its spirit, and it goes without saying that equivalents thereof are included. In particular, embodiments described below are also included in the present invention.

[0079] In the embodiment described above, the column 10 was a square steel pipe, but it is not limited to this; for example, it may be a round steel pipe or an H-shaped steel pipe.

[0080] Furthermore, although the diaphragm 12 in the above-described embodiment was a through diaphragm, it is not limited to this. For example, it may be an internal diaphragm provided on the inside (inside) of the column, or an external diaphragm provided on the outside of the column. In the case of an internal diaphragm, the flange 24 of the beam 20 will be joined to the column body rather than to the diaphragm. [Explanation of Symbols]

[0081] 10 pillars 12 diaphragms 20 beams 22 Web 24 flange 24a Widening section (First widening section) 24b Widening section (Second widening section)

Claims

1. A column-beam joint structure in which a column and a beam having a flange joined to the column are joined, The aforementioned flange is A first widened section is provided, extending from the joint with the column along the longitudinal direction of the beam, in a predetermined range, where the flange width on one side in the width direction intersecting the longitudinal direction is widened. Within the predetermined range, a second widened portion is provided, in which the flange width on the other side in the width direction is widened. It has, When the ratio of the width of the first widened section to the sum of the widths of the first widened section and the second widened section is x%, and the shear span ratio, which is the ratio of the shear span to the beam depth, is L / D, When the shear span ratio L / D is 3 or more and less than 4.5, {-10 × (L / D) + 45} ≤ x < 50, When the shear span ratio L / D is 4.5 or greater, 0 < x < 50, The beam is provided eccentrically to one side in the width direction relative to the column. A column-beam joint structure characterized by the following features.

2. The column-beam joint structure according to claim 1, The column is provided with a diaphragm that widens the width of the column. The flange is joined to the end face of the diaphragm. A column-beam joint structure characterized by the following features.

3. A column-beam joint structure according to claim 1 or claim 2, Connected within the width of the column and having a web perpendicular to the flange, A column-beam joint structure characterized by the following features.

4. The column-beam joint structure according to claim 3, The web is located in the center of the flange width of the flange. A column-beam joint structure characterized by the following features.

5. A column-beam joint structure according to claim 1 or claim 2, The design is such that the end opposite to the joint in the predetermined range yields first, and then the joint yields. A column-beam joint structure characterized by the following features.

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