Column-beam joint structure

Abstract

A column-beam joining structure (1) comprises: a column (11) having a column body (12) configured from column H-shaped steel; and a beam (211B) having beam H-shaped steel (212), a pair of beam flanges (216) of the beam H-shaped steel being directly joined to a plate (16) to be joined of the column body via a welding part (218). The ratio of the total plastic yield strength of the column to the total plastic yield strength of the beam at an intersection position (P1) is 1.5-3.0, where the intersection position is defined as the position where the center axis (O1) of the column body and the center axis (O2) of the beam H-shaped steel intersect. The ratio of the total plastic yield strength of the beam to the total plastic yield strength of a portion (17a) within a vertical-direction beam depth range in a column web (17) of the column body configured from the column H-shaped steel at the intersection position is 1.05-1.5.

Description

[Technical Field]

[0001] The present invention relates to a beam-column joint structure. This application claims priority based on Japanese Patent Application No. 2023-099747, filed on June 19, 2023, the contents of which are incorporated herein by reference. [Background technology]

[0002] The Northridge earthquake occurred in the United States in 1994. Before the Northridge earthquake, a column-beam connection structure 200 shown in Fig. 20 was used (see Non-Patent Document 1). That is, the column-beam connection structure 200 includes a column 201 and a beam 211. The column 201 has a column body 202 made of H-shaped steel for columns (H-shaped steel), a pair of stiffeners (diaphragms; first reinforcing plates, continuous plates) 203, and a shear plate 204. The column body 202 has a pair of column flanges 206 and a column web 207, and extends in the vertical direction. Each stiffener 203 is a horizontal stiffener and is arranged along a horizontal plane. Each stiffener 203 is arranged in the same position in the vertical direction as a pair of beam flanges 216 (described later) of the beam 211. Each stiffener 203 is joined to a pair of column flanges 206 and a column web 207 of the column 201 (column main body 202) by welds 208 formed by welding. The shear plate 204 is joined to the column flange 206 of the column 201 by welding or the like.

[0003] The beam 211 has an H-shaped beam (H-shaped steel) 212 and a pair of backing metals 213. The H-shaped beam 212 is an H-shaped steel specified by, for example, JIS (Japanese Industrial Standards) G 3192:2014 Shape, dimensions, mass and tolerances thereof for hot-rolled shaped steel (hereinafter simply referred to as JIS G 3192). The beam H-shaped steel 212 has a pair of beam flanges 216 and a beam web 217. The pair of beam flanges 216 are arranged to face each other in the vertical direction. Of the pair of beam flanges 216, the beam flange 216 arranged on the top is the upper flange 216A, and the beam flange 216 arranged on the bottom is the lower flange 216B.

[0004] Each beam flange 216 is joined to the column flange 206 of the column body 202 by a weld 218, with a backing metal 213 attached below the beam flange 216. The beam web 217 and the shear plate 204 are connected to each other by fastening members 219 such as high-strength bolts. Note that the beam web 217 may be connected to the shear plate 204 by welding in addition to being connected to the shear plate 204 by the fastening members 219. The beam web 217 may also be joined to the column flange 206 directly by welding. In the beam-column joint structure 200, the column 201 and the beam 211 are connected to each other at a joint 222. The joint 222 is a so-called pre-northridge joint. Here, the portion of the column web 207 that is within the range of the beam 211 in the vertical direction is defined as the joint panel 207a.

[0005] The failure modes of the beam-column joint structure 200 due to the Northridge earthquake include Types A to D, which correspond to the cracks indicated by lines LA, LB, LC, and LD, as shown in FIG. Types A and B depend on the fracture toughness in the direction of tearing the column flange 206 parallel to the main surface of the column flange 206 (S direction (plate thickness direction S) in Figure 1 described later). In Type C, the line LC representing the crack propagates so as to penetrate the beam flange 216. Type D depends on the fracture toughness in the direction (L direction) that divides the column flange 206 in the material axis direction (longitudinal direction).

[0006] As shown in Figure 22, Type D is further induced by local bending deformation of the column flange 206 caused by shear deformation of the joint panel 207a. In the column-beam connection structure 200A shown in Figure 22, a pair of beams 211 are joined to the column 201. Local kink deformation occurs in the area R1 of the column flange 206 of the column 201 and in the area R2 of the beam flange 216 of the beam 211. These areas R1 and R2 are the areas where local bending deformation occurs. As described above, all of the cases except for Type C show that cracks occurred and propagated in the slits formed between the backing plate 213 of the lower flange 216B and the column 201.

[0007] The details of the beam-column joint structures used in current earthquake-resistant structures in Europe and the United States have been determined based on the failure pattern at joint 222 of beam-column joint structure 200 in the Northridge earthquake, so that the joints can withstand multiple repeated deformations. As a specific detailed structure, as shown in FIG. 23, the beam-column joint structure 200B is required to take the following measures (1) to (3). (1) The column 201 is reinforced by a stiffener 203. (2) The joint panel 207a of the column 201 is reinforced by a doubler plate (second reinforcing plate) 225 to thicken the column web 207. (3) After the end of the beam 211A is welded on site, the backing metal 213 attached to the bottom flange 216B of the beam 211A is removed and reinforcement welding is performed. That is, beam 211A does not have a backing plate 213 around the bottom flange 216B in each configuration of beam 211. A doubler plate 225 is provided on the column 201 and is joined to the joint panel 207a.

[0008] The joint 222A between the column 201 and the beam 211A is a so-called Post-Northridge joint. The joint 222A is a joint for preventing Type A to Type D destruction. Measures (1) and (2) suppress plastic deformation of the column flange 206 and the joint panel 207a. Measure (3) uses, for example, an arc gouging method to remove the backing metal 213. Reinforcing welding is performed from below the removed portion upward in the area where the backing metal 213 has been removed. Reinforcing welding eliminates slits that could be the starting point of fracture. These measures are effective in preventing early brittle fracture when a steel material with relatively low fracture toughness in the S and L directions is used for the column flange 206. [Prior art documents] [Non-patent literature]

[0009] [Non-Patent Document 1] Masaaki Nakajima, "Comparison of Beam-Column Joint Failures in Steel-Framed Buildings in the Southern Hyogo Prefecture Earthquake and the Northridge Earthquake in the United States," [online], April 1996, Annual Report of the Disaster Prevention Research Institute, Kyoto University, No. 39, B-1, [Retrieved August 3, 2022], Internet<http: / / www.dpri.kyoto-u.ac.jp / nenpo / no39 / 39b1 / a39b1p02.pdf> Summary of the Invention [Problem to be solved by the invention]

[0010] However, in the joint 222A of the beam-column joint structure 200B, all of the energy from the external force of an earthquake is absorbed by the plastic deformation of the beam 211A, so the ultimate performance of the joint 222A is limited by local buckling of the beam 211A. In addition, reinforcement using stiffeners and doubler plates and removal of backing metals impose a heavy burden on factory fabrication and on-site construction, which is a factor that reduces the productivity of architectural steel frames. On the other hand, it is desirable to ensure the structural stability of buildings that use beam-column joint structures.

[0011] The present invention has been made in consideration of these problems, and aims to provide a column-beam joint structure that ensures the structural stability of buildings in which column-beam joint structures are used, while also having joints with high energy absorption performance. [Means for solving the problem]

[0012] In order to solve the above problems, the present invention proposes the following means. (1) Aspect 1 of the present invention comprises a column having a column body made of H-shaped steel for column, square steel pipe, or welded-assembled box section, and a beam having H-shaped steel for beam, in which a pair of beam flanges of the H-shaped steel for beam are directly joined to joined plates of the column body via welds, respectively, wherein the joined plates are the column flanges of the H-shaped steel for column, or flat plate portions of the square steel pipe and the welded-assembled box section, and when a position where a central axis of the column body and a central axis of the H-shaped steel for beam intersect is defined as an intersection position, the ratio of the total plastic strength of the column to the total plastic strength of the beam at the intersection position is 1.5 to 3.0, and the column web of the column body made of the H-shaped steel for column, or the flat plate portion of the column body made of the square steel pipe and the welded-assembled box section extending along the longitudinal direction of the beam at the intersection position The joint panel In the vertical direction, the ratio of the total plastic strength of the beam to the total plastic strength of the part within the range of the beam depth is 1.05 or more and 1.5 or less. When energy acts on the joint between the column and the beam, the joint panel yields, and the strength of the joint panel increases due to the yielding, followed by the beam yielding, and the energy is absorbed by both the beam and the joint panel. It is a column-beam joint structure.

[0013] In this invention, the inventors have found, through extensive research, that in order to improve the energy absorption capacity of a column-to-beam joint in a beam-column joint structure, it is necessary to have the joint panel, not just the beam, absorb the energy acting on the column-beam joint structure. In particular, it is preferable that the joint panel, which is expected to maintain a stable increase in strength after plasticization unless the column flange breaks, yields first, and then the beam yields following the increase in strength of the joint panel due to yielding. In other words, the beam-panel strength ratio, which is the ratio of the beam's total plastic strength to the joint panel's total plastic strength, needs to be 1.05 or higher for the joint panel to yield first. Furthermore, the joint panels are expected to increase in strength to approximately 1.5 times the total plastic strength due to strain hardening caused by repeated plastic deformation. In other words, by setting the beam-panel strength ratio to 1.5 or less, not only the joint panels but also the beams can be plasticized during the strength increase process after the joint panels have yielded first, allowing both the beams and the joint panels to absorb the energy acting on the column-beam joint structure. This improves the energy absorption capacity of the column-beam joint.

[0014] On the other hand, to ensure the structural stability of buildings that use beam-column joint structures, it is necessary to prevent the collapse of the building's floors due to column yielding. To achieve this, the columns must be sufficiently strong relative to the beams. Considering the increase in strength of the beams after plastic deformation, the column-beam strength ratio, which is the ratio of the column's total plastic strength to the beam's total plastic strength, is preferably 1.5 or higher. To prevent the columns from overperforming and becoming economically unreasonable, it is preferable to keep the column-beam strength ratio below around 2.5 to 3.0. As described above, by setting the beam-panel strength ratio to 1.05 or more and 1.5 or less, and the column-beam strength ratio to 1.5 or more and 3.0 or less, the structural stability of buildings that use column-beam joint structures can be ensured, and a column-beam joint structure with joints having high energy absorption performance can be provided.

[0015] (2) Aspect 2 of the present invention may be a column-beam joining structure as described in (1), which includes a backing plate joined to the lower flange of the pair of beam flanges located at the lower end and to the plate to be joined via the weld, the backing plate being attached below the lower flange, and the upper surface of the backing plate being formed with a slope that gradually slopes downward as it approaches the plate to be joined, and the weld is also formed within the slope. In this invention, the portion of the connection surface between the backing metal and the weld that is joined to the joined plate is inclined rather than perpendicular to the joined plate, which makes it possible to mitigate the concentration of strain at the tip of the slit that occurs at the boundary between the joined plate and the backing metal due to a load such as a bending moment acting on a beam, and to suppress the propagation of cracks from the tip of the slit toward the weld or the joined plate (the base material of the joined plate).

[0016] (3) Aspect 3 of the present invention is a method for determining the Charpy absorbed energy vE -20(S) The column-beam joint structure may be as described in (1) or (2), in which the strength is 35 J or more. In this invention, the toughness of the welded plate in the plate thickness direction at -20°C is higher by a certain amount compared to general welded plates. Generally, the toughness of the welded plate increases as the temperature of the welded plate increases. Since the toughness increases even more at the temperature at which the welded plate is actually used, it is possible to prevent the welded plate from fracturing in the plate thickness direction even when the welded plate is directly joined to a pair of beam flanges of an H-shaped beam steel on a beam via a weld.

[0017] (4) Aspect 4 of the present invention is a method for determining the Charpy absorbed energy vE 0(S) The column-beam joint structure may be as described in any one of (1) to (3), in which the strength of the beam-column joint is 47J or more. In this invention, the toughness of the plates to be joined in the plate thickness direction at 0°C is increased to a certain level. Generally, the toughness of the plates to be joined increases as the temperature of the plates to be joined increases. Since the toughness increases further at the temperature at which the plates to be joined are actually used, it is possible to prevent the plates from fracturing in the plate thickness direction even when the plates to be joined are directly joined to a pair of beam flanges of an H-shaped beam steel on a beam via welds.

[0018] (5) Aspect 5 of the present invention may be a column-beam joint structure described in any one of (1) to (4), which does not have a first reinforcing plate arranged at the same position as the pair of beam flanges in the vertical direction and joined to the column body. In this invention, the pillar does not have a first reinforcing plate joined to the pillar body, so that the pillar can be constructed relatively easily.

[0019] (6) Aspect 6 of the present invention may be a column-beam joint structure described in any one of (1) to (5), which does not have a second reinforcing plate joined to the column web or the flat plate portion so as to thicken the column web or the flat plate portion. In this invention, the pillar does not have a pillar web or a second reinforcing plate joined to the flat plate portion, so that the pillar can be constructed relatively easily. [Effects of the Invention]

[0020] The column-beam joint structure of the present invention can ensure the structural stability of buildings in which the column-beam joint structure is used, and can provide a column-beam joint structure having joints with high energy absorption performance. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a perspective view of a main part of a beam-column joint structure according to one embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged view of part A1 in FIG. [Figure 3] 1A and 1B are diagrams showing the shape of a Charpy test piece, where (A) is a plan view, (B) is a front view, and (C) is a cross-sectional view taken along the cutting line A3-A3 in (A). [Figure 4] FIG. 1 is a diagram illustrating the orientation of a test specimen and a notch when a Charpy test specimen is taken from a rolled steel material. [Figure 5] FIG. 1 is a diagram showing a procedure for taking Charpy test specimens in the plate thickness direction from a column flange. [Figure 6] FIG. 1 is a diagram showing test results according to JIS Z 2242 using a Charpy test piece in which the plane in which the notch is formed is perpendicular to the rolling direction. [Figure 7] FIG. 1 is a diagram showing test results according to JIS Z 2242 using a Charpy test piece in which the plane in which the notch is formed is perpendicular to the plate thickness direction. [Figure 8]FIG. 1 is a front view illustrating a building in which a column-beam joint structure is used. [Figure 9] FIG. 1 is a front view illustrating an outline of a test device for a beam-column joint structure. [Figure 10] FIG. 2 is a diagram illustrating a loading history 1 applied to a sample 1. [Figure 11] 10 is a diagram illustrating a loading history 2 applied to a sample 2. FIG. [Figure 12] 1 is a diagram showing the results of an experiment by the US Emergency Management Agency. [Figure 13] FIG. 1 shows experimental results from Shin's paper. [Figure 14] FIG. 10 is a diagram showing the experimental results of Sample 1. [Figure 15] 10A and 10B are diagrams showing the results of comparing the joints of the embodiment and the conventional joints. [Figure 16] 10 is a photograph showing the experimental results of an example. [Figure 17] FIG. 10 is a diagram comparing the strength ratio and maximum story drift angle in the column-beam joint structure of the embodiment and previous research. [Figure 18] 1 is a perspective view of a main part of a first modified example of a beam-column joint structure according to one embodiment of the present invention. [Figure 19] 10 is a perspective view of a main part of a second modified example of a beam-column joint structure according to one embodiment of the present invention. FIG. [Figure 20] This is a front view of the main parts of the beam-column joint structure that was used before the Northridge earthquake. [Figure 21] FIG. 10 is an enlarged view of a main part illustrating the failure mode of the beam-column joint structure. [Figure 22] This is a side view showing the state in which the joint panel of the column-beam joint structure is shear deformed. [Figure 23] This is an oblique view of the main parts of a beam-column joint structure that has been used since the Northridge earthquake. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, one embodiment of a beam-column joint structure according to the present invention will be described with reference to FIGS.

[0023] [1. Building composition] [1-1. Structure of column-beam joint structure] As shown in Fig. 1, a column-beam joint structure 1 of this embodiment is used in a building 2. The column-beam joint structure 1 includes a column 11 and a pair of beams 211B. The number of beams 211B included in the column-beam joint structure 1 is not limited, and may be one, or three or more. The column 11 has a column body 12 made of an H-shaped column steel (H-shaped steel). The column body 12 extends in the vertical direction (or the first direction). The column body 12 has a pair of column flanges (plates to be joined) 16 and a column web 17. The pair of column flanges 16 and the web 17 are preferably formed of rolled steel material.

[0024] The pair of column flanges 16 are arranged to face each other in the plate thickness direction S. The column web 17 is arranged between the pair of column flanges 16. The column web 17 is joined to the center of the pair of column flanges 16 in the width direction, respectively. For example, the column body 12 is formed of a high-toughness steel material. In the chemical composition of the column body 12, it is preferable that the S content is relatively low. Generally, S is an element that combines with Mn in a steel material and is contained in the steel material as an impurity. S forms MnS, which has the effect of embrittling the steel material. By having the column body 12 have a relatively low S content, the toughness of the column body 12 can be made relatively high.

[0025] In this example, the column 11 does not have the stiffener 203 and the doubler plate 225 as shown in Fig. 23 etc. However, the column 11 may have at least one of the stiffener 203 and the doubler plate 225.

[0026] As shown in Figures 1 and 2, the beam 211B has a pair of backing metals 21 instead of the pair of backing metals 213 in each configuration of the beam 211 (which extends in a second direction, which is horizontal in this example). As shown in FIG. 2, in this example, an inclined surface 216a that slopes gradually downward as it approaches the column flange 16 is formed at the end of each beam flange 216 on the column flange 16 side. In this example, the first direction and the second direction are substantially perpendicular to each other.

[0027] The backing metal 21 has a rectangular parallelepiped shape. Each backing metal 21 is attached below the corresponding beam flange 216 (lower flange 216B). More specifically, each backing metal 21 is attached from below the corresponding beam flange 216 to the corresponding beam flange 216 and column flange 16 by fillet welding, tack welding, or the like. Note that the backing metal 21 does not necessarily have to be used for the upper flange 216A, and a backing metal 213 may be used instead. An inclined surface 21a that slopes gradually downward as it approaches the column flange 16 is formed on the upper surface of the backing metal 21 at the end on the column flange 16 side. In other words, the backing metal 21 is chamfered. The inclined surface 21a is continuous with the inclined surface 216a of the beam flange 216. Welded portions 218 are respectively arranged within the inclined surface 216a of the beam flange 216 (on the inclined surface 216a) and within the inclined surface 21a of the backing metal 21 (on the inclined surface 21a). The backing metal 21 is joined to the beam flange 216 (lower flange 216B) and the column flange 16 via the welded portions 218. In this way, each beam flange 216 is directly joined to each column flange 16 of the column body 12 via a weld 218 . It is difficult to arrange a welded portion 218 between the column flange 16 and the backing metal 21, and a slit 21b is likely to be formed.

[0028] 1, the portion of the column web 17 that is within the range of the beam 211B in the vertical direction is defined as the joint panel 17a. The position where the central axis O1 of the column body 12 intersects with the central axis O2 of the beam 211B (H-shaped beam) is defined as the intersection position P1. In the beam-column joint structure 1, the column 11 and the pair of beams 211B are connected to each other at a joint 23. The intersecting position P1 is a node of the joint 23. Although the column body 12 is made of an H-shaped column steel, the column body may be made of a square steel pipe or a welded and assembled box section (welded and assembled box section column).

[0029] [1-2. Consideration of column flange materials] As shown in Figure 1, for example, when a load F1, which is a bending moment, acts on a pair of beams 211B, a force acts on the column flange 16, which is the joined plate, in the plate thickness direction S. The inventors thought that by using a material with high toughness in the plate thickness direction S for the column flange 16, the joint panel 17a will shear when the load F1 acts, and as a result, the column flange 16 will resist the load in the plate thickness direction S while undergoing bending deformation, and will absorb the energy of the load F1. Furthermore, if a force acts in the thickness direction S on a column flange that has low toughness in the thickness direction S, there is a risk of divot fracture occurring in the column flange.

[0030] JIS Z 2242:2018, Charpy Impact Test Method for Metallic Materials (hereinafter simply referred to as JIS Z 2242), is a known method for measuring the toughness of components. According to JIS Z 2242, a test is performed using a Charpy test specimen 150 as shown in FIG. 3. The axial length of the Charpy test specimen 150 is 55 mm. The cross-sectional shape of the Charpy test specimen 150 perpendicular to the axial direction is a rectangle measuring 10 mm x 10 mm. A notch 151 is formed on the outer surface of the Charpy test specimen 150 at the center in the axial direction. The notch 151 is formed on a plane S1 perpendicular to the axial direction. The notch 151 is a V-notch with a depth of 2 mm. The notch 151 is formed partially in the depth direction of the Charpy test specimen 150. The notch 151 extends in a direction perpendicular to the axial direction and is formed across the entire width of the Charpy test piece 150.

[0031] The orientation of the test piece and the notch when the Charpy test piece 150 is taken from a rolled steel material 155 such as a column flange 16 will be described with reference to Fig. 4. Note that Fig. 4 shows the Charpy test piece 150 schematically, including the shape of a notch 151, which will be described later. The rolled steel material 155 is produced by using a rolling mill to thin the steel in a thickness direction S while stretching it in a rolled direction L. Here, the direction perpendicular to the thickness direction S and the rolled direction L is called a width direction T. The rolled direction L and the width direction T are both thickness-orthogonal directions (directions perpendicular to the thickness direction S). For example, a Charpy test piece 150 in which the plane S1 on which the notch 151 is formed is perpendicular to the thickness direction S and the depth direction of the notch 151 is parallel to the width direction T is called an "ST" or "Charpy test piece 150". ST " is written as ". In JIS Z 2242, the plane S1 on which the notch 151 is formed is perpendicular to the roll direction L or the width direction T of the Charpy test piece 150 LS ,150 LT ,150 TS ,150 TL Charpy test piece 150 perpendicular to the plate thickness direction S is used. ST ,150 SL The Charpy impact test using the above is carried out in accordance with the procedures of JIS Z 2242, except for the procedure for taking the Charpy test piece 150 used.

[0032] Figure 5 shows the Charpy test piece 150 from the column flange 16. SL Here, the plate thickness of the column flange 16 is defined as t1 (mm). The surface of the column flange 16 facing the plate thickness direction S, to which the extending bar 156 (described later) is joined, is called the surface 16a. SL The distance between the notch 151 and the surface 16a in the thickness direction S is defined as t2 (mm).

[0033] A cylindrical extension rod 156 is joined by friction welding to the surface 16a of the column flange 16. The reason for joining by friction welding is to keep the heat-affected zone (HAZ) formed at the joint between the column flange 16 and the extension rod 156 as small as possible. This makes it possible to manufacture the Charpy test specimen 150 in a form that does not cause thermal effects on the notch 151 of the Charpy test specimen 150. At this time, the extension rod 156 is arranged so that its axial direction is along the plate thickness direction S. For example, the length of the extension rod 156 is 120 mm, and the diameter of the extension rod 156 is 30 mm. The material forming the extension rod 156 is preferably the same as the material forming the column flange 16. Friction welding is performed so that the entire cross section of the extension rod 156 is joined to the surface 16a of the column flange 16.

[0034] For example, when the plate thickness t1 is 40 mm or less, the distance t2 is set to (t1 / 4). When the plate thickness t1 is more than 40 mm, the distance t2 is set to 10 mm. Because a heat-affected zone is formed, albeit in a narrow range, at the joint between the column flange 16 and the extension rod 156, it is preferable to set the distance t2 as described above according to the plate thickness t1. For example, the plate thickness t1 of the column flange 16 is 19 mm or more.

[0035] Generally, the greater the Charpy absorbed energy measured according to JIS Z 2242, the higher the toughness.

[0036] FIG. 6 shows a Charpy test piece 150 in which a plane S1 on which a notch 151 is formed is perpendicular to the rolling direction L. LT The horizontal axis in Figure 6 shows the test results according to JIS Z 2242 using a Charpy test piece of 150 LT The vertical axis represents the temperature (°C) of the Charpy test piece 150, and the vertical axis represents the Charpy absorbed energy (J). LS ,150 LT ,150 TS ,150 TLThe Charpy absorbed energy in the roll direction L is expressed as vE (L,T) He says. Although the direction perpendicular to the thickness of the plate is the roll direction L, the direction perpendicular to the thickness of the plate may be the width direction T.

[0037] The open circles represent the results for the high-toughness steel material used in the column flange 16. The solid line L1 represents a curve that approximates the results represented by the open circles. The open triangles represent the results for a common steel material (hereinafter referred to as conventional steel material) that has traditionally been used in the column flange 16 for comparison. The dotted line L2 represents a curve that approximates the results represented by the open triangles. Line L3 represents the required performance based on Eurocodes and AISC (American Institute of Steel Construction). The required performance is a Charpy absorbed energy of 27 J or more at temperatures between -21°C and -20°C.

[0038] For both high-toughness steel and conventional steel, the Charpy absorbed energy increased as the temperature increased. Regardless of the temperature, the Charpy absorbed energy of the high-toughness steel was greater than that of the conventional steel. At temperatures between -60°C and 80°C, the Charpy absorbed energy of both the high-toughness steel and the conventional steel met the required performance based on Eurocodes and AISC.

[0039] Here, the measured Charpy absorbed energy vE in the roll direction L at -20°C based on JIS Z 2242 for high toughness steel materials -20(L,T) In Figure 6, point P -20(L,T) Charpy absorbed energy vE in the roll direction L at 0°C based on JIS Z 2242 for high toughness steel materials 0(L,T) In Figure 6, point P 0(L,T) Shown as:

[0040] FIG. 7 shows a Charpy test piece 150 in which a plane S1 on which a notch 151 is formed is perpendicular to the thickness direction S. SLThe test results according to JIS Z 2242 using a Charpy test piece 150 are shown. The meanings of the axes, legends, and lines L1 and L2 are the same as in Figure 6. SL In this case, the required performance is not specified in the Eurocodes or AISC. Hereinafter, the plane S1 on which the notch 151 is formed is perpendicular to the thickness direction S of the Charpy test piece 150. ST ,150 SL The Charpy absorbed energy in the thickness direction S is expressed as vE (S) He says. Charpy test piece 150 SL Even in the case of 150 Charpy test pieces LT Furthermore, the same tendency was observed for the 150 Charpy test piece. SL In the case of , the difference between the Charpy absorbed energy of the high toughness steel and the Charpy absorbed energy of the conventional steel became large.

[0041] Here, the measured Charpy absorbed energy vE in the thickness direction S at -20°C based on JIS Z 2242 for high toughness steel materials -20(S) In Figure 7, point P -20(S) Charpy absorbed energy vE in the thickness direction S at 0°C based on JIS Z 2242 for high toughness steel 0(S) In Figure 7, point P 0(S) Shown as: Charpy absorbed energy vE -20(S) The Charpy absorbed energy vE is preferably 35 J or more. -20(S) It is more preferable that the Charpy absorbed energy vE is 47J or more. 0(S) The Charpy absorbed energy vE is preferably 47 J or more. 0(S) It is more preferable that the value is 70J or more.

[0042] Charpy absorbed energy vE at -20°C -20(L,T) and Charpy absorbed energy vE -20(S) However, it is preferable to satisfy the formula (6). vE -20(S) ≧0.5×vE-20(L,T) (6) That is, Charpy absorbed energy vE at -20°C -20(S) The toughness in the thickness direction S of the column flange 16 corresponding to the Charpy absorbed energy vE -20(L,T) It is preferable that the toughness be at least a certain percentage relative to the toughness in the roll direction L of the corresponding column flange 16. Also, the Charpy absorbed energy vE at 0°C 0(L,T) and Charpy absorbed energy vE 0(S) However, it is preferable to satisfy the formula (7). vE 0(S) ≧0.5×vE 0(L,T) (7) That is, the Charpy absorbed energy vE at 0°C 0(S) The toughness in the thickness direction S of the column flange 16 corresponding to the Charpy absorbed energy vE 0(L,T) It is preferable that the toughness be at least a certain percentage relative to the toughness in the roll direction L of the corresponding column flange 16.

[0043] In this way, by making the toughness of the column flange 16 in the thickness direction S a certain percentage or more of the toughness of the column flange 16 in the roll direction L, the difference in the toughness of the column flange 16 depending on the direction becomes small, and stable crack growth is induced, resulting in a ductile fracture behavior and a joint with higher energy absorption performance. Note that, as a method for measuring the toughness of a component, other standards that can obtain results similar to those of JIS Z 2242, such as ISO 148-1:2016 Metallic Materials-Charpy pendulum impact test Part 1: Test method, ASTM E23-18 Standard Test Methods for Notched Bar Impact Testing of Metallic Materials, BS EN ISO 148-1:2016 Metallic Materials-Charpy pendulum impact test Part 1: Test method, and DIN EN ISO 148-1:2016 Metallic Materials-Charpy pendulum impact test Part 1: Test method, may also be used.

[0044] Furthermore, the Charpy absorbed energy vE at -20°C -20(L,T) and Charpy absorbed energy vE -20(S) However, it is preferable that the formula (6') is satisfied. vE -20(L,T) ≧vE -20(S) (6') That is, Charpy absorbed energy vE at -20°C -20(L,T) The toughness of the column flange 16 in the roll direction L corresponding to the Charpy absorbed energy vE -20(S) It is preferable that the toughness in the thickness direction S of the corresponding column flange 16 be equal to or greater than that of the corresponding column flange 16. Also, the Charpy absorbed energy vE at 0°C 0(L,T) and Charpy absorbed energy vE 0(S) However, it is preferable that the formula (7') is satisfied. vE 0(L,T) ≧vE 0(S) (7') That is, the Charpy absorbed energy vE at 0°C 0(L,T) The toughness of the column flange 16 in the roll direction L corresponding to the Charpy absorbed energy vE 0(S)It is preferable that the toughness in the thickness direction S of the corresponding column flange 16 be equal to or greater than that of the corresponding column flange 16.

[0045] In this way, the toughness of the column flange 16 in the roll direction L is equal to or greater than the toughness of the column flange 16 in the plate thickness direction S, so that fracture in the plate thickness direction is suppressed, and even when the crack propagates in the direction through the plate thickness, the crack propagation becomes stable and the fracture behavior becomes ductile, resulting in a joint with higher energy absorption performance.

[0046] [1-3. Provisions regarding the total plastic strength of each component of a beam-column joint structure] Generally, in the design of beam-column joint structures, the intersection position is used as the reference when calculating the full plastic strength of columns, beams, etc. Note that full plastic strength refers to the external force acting on a member that has a shape that extends in a predetermined reference direction, such as a beam, when the entire cross section of the member perpendicular to the reference direction is put into a plastic state. Here, the total plastic strength M of the beam 211B at the intersection position P1 pb Full plastic strength M of column 11 against pc The ratio of the column-beam strength ratio (M pc / M pb ) is defined as the total plastic strength M of the joint panel 17a at the intersection position P1. pp Full plastic strength M of beam 211B against pb The ratio of the beam panel strength ratio (M pb / M pp ) is stipulated. In the following [4.], we will consider the range of column-beam strength ratio and beam-panel strength ratio in order to ensure the structural stability of the building 2 and provide a column-beam joint structure 1 having a joint 23 with high energy absorption performance, which is the objective of this invention.

[0047] [1-4. Calculation method for full plastic strength] An example of a method for calculating full plastic strength will be described using a building 4 that uses a column-beam joint structure 3 shown in Fig. 8. The column-beam joint structure 3 includes one column 11 and six beams 211B. In this example, it is assumed that the heights of the six beams 211B are equal, and that the distances between adjacent beams 211B in the vertical direction (the heights of the columns 11) are equal. The ends of the six beams 211B that are not joined to the pillar 11 are joined to the second pillar 51, respectively. Here, the direction in which the pair of second columns 51 are arranged is referred to as the left-right direction. The position where the central axis O1 of the column 11 or the central axis O3 of the second column 51 intersects with the central axis O2 of the beam 211B is referred to as a node.

[0048] Symbols for the specifications of the beam-column joint structure 3 are defined as follows. Note that the units used for each symbol are the units shown in Table 1, which will be described later. L l , R l: Distance between the nodes of the left and right beams 211B relative to the joint 23 L l', R l': the inside length of the left and right beams 211B relative to the joint 23 T h , B h: Distance between the nodes of the upper and lower columns 11 relative to the joint 23 T h', B h': The inner length of the upper and lower columns 11 relative to the joint 23 bL Z p , bR Z p : Plastic section modulus of left and right beams 211B for joint 23 cT Z p , cB Z p : Plastic section modulus of upper and lower columns 11 relative to joint 23 bL F, bR F: Reference strength of material strength of left and right beams 211B for joint 23 cT F, cBF: Reference strength of the material strength of the upper and lower columns 11 relative to the joint 23 p F: Reference strength of material strength of joint panel 17a

[0049] b H:Because of beam 211B c H: Because of Pillar 11 b t f :Beam flange thickness 216 c t f : Thickness of column flange 16 t p : Thickness of web 17 (if the column body is made of a square steel pipe or a welded assembled box section, the thickness of the flat plate part of the square steel pipe or the welded assembled box section (see flat plate part 33B in Figure 18)) d b : Distance between the center of thickness of a pair of beam flanges 216 (= b H- b t f ) d c : Distance between the center of thickness of a pair of column flanges 16 (= c H- c t f ) where the effective volume of the joint panel V e is obtained by equations (11) and (12).

[0050]

number

[0051] At this time, the total plastic strength M of beam 211B pb is obtained by equation (15). The full plastic strength of the column M pc is obtained by equation (16). The full plastic strength of the joint panel M pp is obtained by equation (17).

[0052]

number

[0053] For example, the floor height (distance) above and below the joint 23 T h, B h) is assumed to be 4500 mm. L l, R Assume l is 9000 mm. The beam-panel strength ratio and column-beam strength ratio were calculated for Cases 1 to 5 shown in Table 1.

[0054] [Table 1]

[0055] For example, in Case 1, a column body made of H-shaped steel for columns is used. The cross-sectional dimensions of the column body are H-458 x 427 x 40 x 50 (height x width x web thickness x flange thickness, in mm), and the standard strength is cT F, cB F was set to 235N / mm2. In Case 1, the beam-panel strength ratio was 1.411, and the column-beam strength ratio was 2.983.

[0056] [1-5. Other components of the building] The building 2 includes a floor slab and the like (not shown). The floor slab is supported from below by beams 211B and the like of the beam-column joint structure 1. The building 2 may have multiple stories (storeies) separated in the vertical direction by floor slabs and the like. For example, the building 2 is used with equipment such as desks and filing cabinets placed on the floor slab.

[0057] [2. Manufacturing method of high toughness steel] The chemical composition of the high toughness steel material is such that the S content is 0.011 mass% or less. The S content can be measured using a combustion-infrared absorption method. The chemical composition of other elements in the high toughness steel material may be set as appropriate. An example of the chemical composition includes C: 0.05 to 0.20% (mass %), Si: 0.05 to 0.60%, Mn: 0.50 to 2.00%, P: 0.035% or less, and S: 0.011% or less.

[0058] High toughness steel can be obtained by heating a cast slab having the above-mentioned chemical composition to 1050 to 1350°C and performing finish rolling at 600 to 950°C. Furthermore, it is preferable that the finish rolling be followed by accelerated cooling, and that the accelerated cooling be stopped at a temperature of 100°C or higher and 600°C or lower.

[0059] [3. Experiment to examine the strength ratio of column-beam joint structures] An experiment was conducted by attaching the column-beam joint structure 1 to the experimental apparatus 160 shown in Fig. 9. Hereinafter, one of the pair of beams 211B provided in the column-beam joint structure 1 may be referred to as beam 211BA and the other as beam 211BB. The column-beam joint structure 1 was installed in a state where it was laid on its side relative to its arrangement in an actual building, with the structural plane of the column and beam on a horizontal plane. The experimental device 160 includes a reaction wall connection jig 161, beam jacks 162A and 162B, a column jack 163, a horizontal stiffening jig 164, an axial force frame 165, pantograph jigs 166A and 166B, and a reaction force jig 167.

[0060] A reaction wall connection jig 161 is attached to the reaction wall of the test site. Beam jacks 162A and 162B and an axial force frame 165 are fixed to the reaction wall connection jig 161. A column jack 163 is fixed to the end of the axial force frame 165 opposite to the end to which the reaction wall connection jig 161 is joined. The beam jack 162A alternately moves upward and downward the end of the beam 211BA opposite to the end joined to the column main body 12. The beam jack 162B alternately moves upward and downward the end of the beam 211BB opposite to the end joined to the column main body 12. The pillar jack 163 moves the lower end of the pillar body 12. The horizontal stiffening jig 164 and the pantograph jigs 166A and 166B are attached to the reaction floor of the test site and suppress deformation of the column body 12 and beam 211B of the test specimen out of the structural plane. Both ends of the reaction force jig 167 are respectively joined to the lower end of the column main body 12 and the reaction force wall connection jig 161. The reaction force jig 167 transmits the reaction forces generated by the beam jacks 162A and 162B.

[0061] The specifications of column-beam joint structure 1 are as shown in Table 2.

[0062] [Table 2]

[0063] As shown in Table 2, the cross-sectional dimensions of the column body 12 were H-498 x 432 x 45 x 70. The length of the column body 12 was 4550 mm. The yield strength of the column body 12 was 379 N / mm 2 The tensile strength is 546N / mm 2 It was decided. The column body 12 is made of high-toughness steel as shown in Figures 6 and 7, and its chemical composition, in mass%, is C: 0.16%, Si: 0.30%, Mn: 1.40%, P: 0.017%, and S: 0.004%. The S content of the high-toughness steel is relatively low compared to general steel.

[0064] As shown in Table 2, the cross-sectional dimensions of the beam H-shaped steel 212 were H-650 x 300 x 16 x 25. The length of the beam H-shaped steel 212 (the distance between the beam jack 162A and the beam jack 162B) was 8000 mm. The yield strength of the beam H-shaped steel 212 was 380 N / mm 2 The tensile strength is 513N / mm 2 It was decided. At this time, the column-beam strength ratio was 2.34, and the beam-panel strength ratio was 1.43.

[0065] The beam-column joint structure 1 does not have a stiffener or a doubler plate, and backing metals with sloped surfaces remain on both the upper flange 216A and the lower flange 216B of the beam flange 216.

[0066] The experimental apparatus 160 is placed in a first movement state, in which the end of beam 211BA is moved upward by beam jack 162A, and at the same time, the end of beam 211BB is moved downward by beam jack 162B. The experimental apparatus 160 is placed in a second movement state, in which the end of beam 211BA is moved downward by beam jack 162A, and at the same time, the end of beam 211BB is moved upward by beam jack 162B. The experimental apparatus 160 alternately repeats the first movement state and the second movement state as one cycle, thereby applying a load that causes antisymmetric bending to the beam-column joint structure 1. Samples 1 and 2 were prepared, each having the same configuration as a beam-column joint structure 1. A load was applied to Sample 1 according to loading history 1 shown in FIG. 10, and a load was applied to Sample 2 according to loading history 2 shown in FIG. 11.

[0067] 10 and 11, the horizontal axis represents cycles (loading cycles), and the vertical axis represents the story deformation angle (rad) of the beam-column joint structure 1. Load history 1 is the loading history used in the standard loading history for performance verification tests of seismic structural joints as defined in the US design standard ANSI / AISC341-16. AISC is an organization that sets standards for steel structures in the US and issues seismic design regulations for steel structures. Load history 2 is the loading history used in the Seismic Structure Investigation Project SAC. SAC is a project organized to investigate countermeasures against the failure of welded joints in steel structures that occurred in the Northridge earthquake. In both Samples 1 and 2, a constant compressive axial force (5000 kN), which was 20% of the yield axial force, was applied to the column body 12 by the column jack 163. While applying the constant compressive axial force to the column body 12, multiple cycles of load were applied to the pair of beams 211B.

[0068] Here, the experimental results of joints in previous studies are shown in Figures 12 and 13. In Figures 12, 13, and Figure 14 described later, the horizontal axis represents the story drift angle (rad), and the vertical axis represents the story shear force (kN), which is the load. Figure 12 shows the results of an experiment conducted by the Federal Emergency Management Agency (hereinafter simply referred to as FEMA) in 1997. The junction used in this experiment was the Pre-Northridge Junction. Figure 13 shows the experimental results from Shin's paper (hereinafter simply referred to as Shin. See [7.]). The joint used in this experiment is the Post-Northridge joint. FIG. 14 shows the results of Sample 1 (Example) of this test.

[0069] The ranges on the horizontal axes in Figures 12 to 14 are the same, and the ranges on the vertical axes in Figures 12 to 14 are the same. The story shear force on the vertical axis varies depending on the cross-sectional dimensions of the test specimen, etc., and therefore cannot be directly compared. On the other hand, the story drift angle on the horizontal axis represents the deformation capacity of the beam-column joint structure. When story shear force is maintained up to a range where the story drift angle is large, this indicates that the structure has higher deformation capacity. The maximum story drift angle in Figure 14 is 0.08 rad, which is significantly higher than the maximum story drift angles in Figures 12 and 13, and it is clear that the structure has high deformation capacity. In addition, in Figures 12 to 14, the area surrounded by the curves of the experimental results represents the energy absorbed by the beam-column joint structure, and the cumulative absorbed energy in each loading cycle represents the energy absorption performance of the beam-column joint structure. Figure 14 maintains the story shear force for more cycles than Figures 12 and 13, so the cumulative absorbed energy is extremely large. For this reason, it was found that the joint 23 of the beam-column joint structure 1 shown in Figure 14 has higher energy absorption performance than the joints of FEMA and Shin.

[0070] Figure 15 shows the results of comparing the beam-column joint structure 1 of the example with conventional joints such as those of FEMA. Figure 15 also shows the results of the Chi & Uang paper (hereinafter simply referred to as Chi & Uang; see [7.]), the Ricles paper (hereinafter simply referred to as Ricles; see [7.]), and the Rahiminia & Namba paper (hereinafter simply referred to as Rahiminia & Namba; see [7.]) as conventional joints. For each joint, the joint classification, stiffener, doubler plate, and backing plate are shown. "Retained" in the backing plate column means that the backing plate is retained and present. "Removed" in the backing plate column means that the backing plate is removed and there is no backing plate.

[0071] For example, the beam-column joint structure 1 of the embodiment does not have a stiffener or a doubler plate, but has a backing metal.

[0072] The story drift angle (rad) is shown as the deformation capacity for each joint at the top of Figure 15. In Figure 15, the required capacity (0.04) of the American design standard AISC341-18 is shown by the solid line L5. The US design standard AISC341-18 assumes loading according to Loading Procedure 1. The US design standard AISC341-18 stipulates that the required performance of joints in earthquake-resistant structures is that when the story drift angle becomes 0.04 rad, at least 80% of the full plastic strength remains.

[0073] FIG. 15 shows test results of the column-beam joint structure 1 of the example. In the joint panel yield column, "Yes" means that the joint panel yields during the test, and "No" means that the joint panel does not yield during the test. In the fabrication and construction column, "×" (bad) means that the fabrication and construction is poor, and "○" (good) means that the fabrication and construction is good. In the seismic performance column, "×" means that the seismic performance is poor, "○" means that the seismic performance is good, and "◎" (very good) means that the seismic performance is very good. For example, in the example of beam-column joint structure 1, the joint panel yielded during the test. The manufacturing and construction of beam-column joint structure 1 was easy because it did not have stiffeners or doubler plates, and its seismic performance was very good.

[0074] The joint 23 of the beam-column joint structure 1 of the example significantly exceeded the required capacity of the American design standard AISC341-18, represented by line L5. Samples 1 and 2 showed almost the same failure mode. This demonstrates that the joint 23 of the beam-column joint structure 1 of the example consistently exceeded the required performance of joints in earthquake-resistant structures under the test conditions. The ultimate state of the joint 23 of the beam-column joint structure 1 of the example is similar to Type D in Non-Patent Document 1. That is, a crack that occurred on the surface of the column flange 16 exhibited a fracture mode that penetrated in the plate thickness direction.

[0075] However, as shown in Figure 16, the crack LF occurred and propagated on the upper flange 216A side, indicating that the backing plate 213 with the inclined surface 21a effectively functioned as a means to prevent fracture originating from the lower flange 216B. As shown in Figure 16, white plaster was applied in advance to the surface of the beam-column joint structure 1. In the beam-column joint structure 1, the plaster peeled off in the plasticized areas, revealing the black base of the column body 12, etc. In other words, it was found that not only did the column 11 and beam 211B kink, but the joint panel 17a and the beam flange 216 and beam web 217 at the end of the beam 211B also plasticize, absorbing energy.

[0076] In addition, research is currently underway into the degree of margin (redundancy) against collapse in the event of an extremely large earthquake exceeding the scale assumed in the design, and into the evaluation of remaining performance after an earthquake (determining whether repairs are possible).Among these, it has been found that the performance of the joint 23 of the column-beam joint structure 1 of the embodiment has a high advantage from these perspectives.

[0077] [4. Consideration of strength ratio] The column-to-beam strength ratio, beam-panel strength ratio, and maximum story drift angle obtained from the example beam-column joint structure 1, Shin's literature, Rahiminia & Namba's literature, and Ricles' literature are shown in Figure 17. Shin's literature, Rahiminia & Namba's literature, and Ricles' literature are literature based on previous research. Table 3 shows whether stiffeners were used in the examples and previous studies.

[0078] [Table 3]

[0079] If a slab is present, the slab is supported from below by beams. For example, UT01 in Shin's reference has stiffeners but no doubler plates, no backing strips, and no slabs.

[0080] 5. Effects of this embodiment As explained above, the inventors have found, after extensive research, that in order to improve the energy absorption performance of the joint 23 between the column 11 and the beam 211B in the beam-column joint structure 1, it is necessary to absorb the energy acting on the beam-column joint structure 1 not only in the beam 211B but also in the joint panel 17a. In particular, it is preferable that the joint panel 17a, which is expected to have a stable increase in strength after plasticization as long as the column flange 16 does not break, yields first, and then the beam 211B yields following the increase in strength of the joint panel 17a due to yielding. In other words, the total plastic strength M of the joint panel 17a pp Full plastic strength M of beam 211B against pb The beam-panel strength ratio, which is the ratio of the above, should be 1.05 or more so that the joint panel 17a yields first. Furthermore, the joint panel 17a is expected to have its strength increased to approximately 1.5 times its total plastic strength due to strain hardening caused by repeated plastic deformation. In other words, by setting the beam-panel strength ratio to 1.5 or less, not only the joint panel 17a but also the beam 211B can be plasticized during the strength increase process after the joint panel 17a has yielded first, and both the beam 211B and the joint panel 17a can absorb the energy acting on the beam-column joint structure 1. This improves the energy absorption performance of the joint 23 between the column 11 and the beam 211B.

[0081] On the other hand, to ensure the structural stability of a building 2 in which a column-beam joint structure 1 is used, it is necessary to prevent the collapse of stories due to the yielding of the column 11. To achieve this, the column 11 needs to be sufficiently strong relative to the beam 211B. Considering the increase in strength of the beam 211B after plasticization, the column-beam strength ratio, which is the ratio of the total plastic strength of the column 11 to the total plastic strength of the beam 211B, is preferably 1.5 or more. To prevent the column 11 from overperforming and becoming economically unreasonable, it is preferable to keep the column-beam strength ratio to around 2.5 to 3.0 or less.

[0082] In contrast, previous studies shown in Figure 17 have found few cases where the beam-panel strength ratio is 1.05 or greater, in which the joint panel yields first. This is thought to be because conventional steel materials and joint details have prevented the joint panel from yielding first. Previous studies have shown that when the beam-panel strength ratio is 1.05 or higher, the column-beam strength ratio is mainly small, being 1.5 or less, and previous studies in which the joint panel yields first have assumed cases where the column strength is relatively small. When the column-to-beam strength ratio is large, exceeding 1.5, the thickness of the column flange is large, and the effect of local bending deformation (kinking) of the column flange becomes significant, which can lead to early fracture. In contrast, when the column-to-beam strength ratio is small, the thickness of the column flange is relatively thin, so the effect of local bending deformation of the column flange when the joint panel yields is small, making fracture less likely to occur. For these reasons, previous research has avoided column-beam connection structures with a strength balance in which the beam-panel strength ratio is in the range of 1.05 to 1.5 (range R6 shown in Figure 17) and the column-beam strength ratio is in the range of 1.5 to 3.0 (range R7 shown in Figure 17).

[0083] By setting the beam-panel strength ratio to 1.05 or more and 1.5 or less, and the column-beam strength ratio to 1.5 or more and 3.0 or less, the structural stability of the building 2 in which the column-beam joint structure 1 is used can be ensured, and a column-beam joint structure 1 having a joint 23 with high energy absorption performance can be provided. If the column 11 of the column-beam joint structure 1 does not have the stiffener 203 and the doubler plate 225, the column 11 can be easily manufactured and installed.

[0084] In Table 1, Case 1 is a column-beam joint structure using H-shaped steel for column 11, and Case 2 is a column-beam joint structure using a welded assembled box section for column 11, but both satisfy the ranges of beam-panel strength ratio and column-beam strength ratio, and are examples. Case 3 does not satisfy the range of beam-panel strength ratio and is a comparative example. Case 4 does not satisfy the range of column-beam strength ratio and is a comparative example. Case 5 does not satisfy the range of beam-panel strength ratio and column-beam strength ratio and is a comparative example.

[0085] A slope 21a is formed on the backing metal 21. Therefore, the portion of the connection surface between the backing metal 21 and the welded portion 218 that is joined to the column flange 16 is not perpendicular but is sloped relative to the column flange 16. For this reason, for example, it is possible to alleviate the concentration of strain at the tip of the slit 21b that occurs at the boundary between the column flange 16 and the backing metal 21 due to a load such as a bending moment acting on the beam 211B, and it is possible to suppress the progression of cracks from the tip of the slit 21b toward the welded portion 218 or the column flange 16.

[0086] Charpy absorbed energy vE in the thickness direction S of the column flange 16 at -20°C based on JIS Z 2242 -20(S) However, the strength of the column flange 16 may be 35 J or more. In this case, the toughness of the column flange 16 in the plate thickness direction S at -20°C becomes higher than a certain level. Generally, the higher the temperature of the column flange, the higher the toughness of the column flange. Since the toughness becomes even higher at the temperature at which the column flange 16 is actually used, even when the column flange 16 is directly joined to a pair of beam flanges 216 of the beam H-shaped steel 212 of the beam 211B via the welded joints 218, it is possible to prevent the column flange 16 from breaking in the plate thickness direction S. Charpy absorbed energy vE -20(S) ,vE -20(L,T)However, there are cases where equation (6) is satisfied. In this case, the Charpy absorbed energy vE -20(S) The toughness in the thickness direction S of the column flange 16 corresponding to the Charpy absorbed energy vE -20(L,T) This is equal to or greater than a certain percentage of the toughness in the roll direction L of the column flange 16 corresponding to the column flange 16. As a result, the difference in toughness of the column flange 16 depending on the direction becomes smaller, and stable crack propagation is induced, resulting in a ductile fracture property and a joint with higher energy absorption capacity.

[0087] Charpy absorbed energy vE in the thickness direction S of the column flange 16 at 0°C based on JIS Z 2242 0(S) However, the toughness may be 47J or more. In this case, the toughness of the column flange 16 in the plate thickness direction S at 0°C becomes higher than a certain level. Generally, the toughness of the column flange increases as the temperature of the column flange increases. Since the toughness becomes even higher at the temperature at which the column flange 16 is actually used, even when the column flange 16 is directly joined to a pair of beam flanges 216 of the beam H-shaped steel 212 of the beam 211B via the welded joints 218, it is possible to prevent the column flange 16 from breaking in the plate thickness direction S. Charpy absorbed energy vE 0(S) ,vE 0(L,T) However, there are cases where equation (7) is satisfied. In this case, the Charpy absorbed energy vE 0(S) The toughness in the thickness direction S of the column flange 16 corresponding to the Charpy absorbed energy vE 0(L,T) This is equal to or greater than a certain percentage of the toughness in the roll direction L of the column flange 16 corresponding to the column flange 16. As a result, the difference in toughness of the column flange 16 depending on the direction becomes smaller, and stable crack propagation is induced, resulting in a ductile fracture property and a joint with higher energy absorption capacity.

[0088] The pillar 11 may not have the stiffener 203. In this case, the pillar 11 can be processed relatively easily. The column 11 may not have the doubler plate 225. In this case, the column 11 can be processed relatively easily.

[0089] [6. Other] Although one embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and configuration changes, combinations, deletions, etc. are also included within the scope that does not deviate from the gist of the present invention. For example, in the above embodiment, the beam-column joint structure 1 may not include the backing metals 21, 213 by removing the backing metals 21, 213. For example, when the backing metal 21 is removed and no backing metal 21 is provided, the shape shown in FIG. 2 is one in which the backing metal 21 is not provided, and the shape of the welded portion 218 and the like remains the same as the shape shown in FIG.

[0090] As in a beam-to-column joint structure 1A of a first modified example shown in Fig. 18, a column main body 32 of a column 31 may be configured with a welded and assembled box-shaped cross section. In Fig. 18, a part of the column main body 32 is shown cut away. In this example, the column main body 32 is configured by welding a pair of flat plate portions (joined plates) 33A and a pair of flat plate portions 33B to each other. The pair of flat plate portions 33A are arranged to face each other. The pair of flat plate portions 33B are arranged to face each other. Each flat plate portion 33B is joined to an end portion of the pair of flat plate portions 33A. A pair of beam flanges 216 of the beam H-shaped steel 212 are directly joined to the respective flat plate portions 33A via welded portions 218. The pair of flat plate portions 33B extend along the longitudinal direction of the beam 211B.

[0091] The joint panel 33Ba is a portion of the pair of flat plate portions 33B that is within the range of the beam 211B in the vertical direction. In the beam-column joint structure 1A, the column 31 and the pair of beams 211B are connected to each other at the joint 35. A beam-panel strength ratio is defined for this joint panel 33Ba, as in this embodiment. The beam-column joint structure 1A of the first modified example may have at least one of the stiffener 203 and the doubler plate 225. In the case of the beam-to-column joint structure 1A of the first modification, the column-to-beam strength ratio is also 1.5 or more and 3.0 or less. The beam-to-panel strength ratio based on the joint panel 33Ba is 1.05 or more and 1.5 or less.

[0092] As in a beam-to-column connection structure 1B of a second modified example shown in Fig. 19, a column body 42 of a column 41 may be made of a square steel pipe manufactured by bending and welding steel plates. In Fig. 19, a part of the column body 42 is shown cut away.

[0093] The H-shaped steel for columns and the H-shaped steel for beams are not limited to the H-shaped steel defined by JIS G 3192, but may be steel material having an H-shaped cross section perpendicular to the axial direction.

[0094] [7. References] Shin: Shin, S. 2017, “Experimental and analytical investigation of panel zone behavior in steel moment frames”, PhD Thesis, Department of Civil, Architectural and Environmental Engineering, University of Texas at Austin, TX, USA. Chi & Uang: Chi, B., and C.-M. Uang. 2002, “Cyclic response and design recommendations of reduced beam section moment connections with deep columns”, Journal of Structural Engineering, 128 (4): 464-473, American Society of Civil Engineers. Ricles: Ricles, JM, C. Mao, L.-W. Lu, and JW Fisher. 2000, Development and evaluation of improved details for ductile welded unreinforced flange connections, SAC Background Document, Report No. SAC / BD-00 / 24, SAC Joint Venture, Sacramento, CA, USA. Rahiminia & Namba : Rahiminia, F., and H. Namba, 2013, “Joint panel in steel moment connections, part 1: experimental test results”, Journal of Constructional Steel Research, 89: 272-283. [Industrial Applicability]

[0095] The column-beam joint structure ensures the structural stability of buildings in which it is used, and can be applied to column-beam joint structures with joints that have high energy absorption performance. Therefore, it has great industrial applicability. [Explanation of symbols]

[0096] 1,1A,1B Column beam joint structure Pillars 11, 31, 41 12, 32, 42 Pillar body 16 Column flange (joined plate) 17 Pillar web 21 Backing plate 21a Slope 33A Flat plate part (joint plate) 211B Beam 212 H-shaped steel for beams 203 Stiffener (first reinforcing plate) 216 Beam flange 216B Lower flange 218 Welded Parts 225 Doubler Plate (Second Reinforcement Plate) O1,O2 Center axis P1 Intersection position S Thickness direction

Claims

1. A column having a column body made of a column H-shaped steel, a square steel pipe, or a welded assembly box cross section; A beam having an H-shaped beam, wherein a pair of beam flanges of the H-shaped beam are directly joined to joined plates of the column body via welds; Equipped with The joined plate is a column flange of the column H-shaped steel, or a flat plate portion of the square steel pipe and the welded assembly box cross section, When the position where the central axis of the column body and the central axis of the H-shaped steel for the beam intersect is defined as the intersection position, At the intersection position, the ratio of the total plastic strength of the column to the total plastic strength of the beam is 1.5 or more and 3.0 or less; At the intersection position, in the column web of the column main body made of the column H-shaped steel, or in the joint panel which is the flat plate portion extending along the longitudinal direction of the beam in the column main body made of the square steel pipe and the welded assembled box cross section, the ratio of the total plastic strength of the beam to the total plastic strength of a portion within the range of the beam depth in the vertical direction is 1.05 or more and 1.5 or less, A column-beam joint structure in which, when energy acts on the joint between the column and the beam, the joint panel yields, and following the increase in the strength of the joint panel due to yielding, the beam yields, and the energy is absorbed by both the beam and the joint panel.

2. a backing metal joined to the lower flange of the pair of beam flanges disposed at the lower end and the joined plate via the welded portion; The backing metal is attached below the lower flange, The upper surface of the backing plate is formed with a slope that gradually slopes downward as it approaches the plate to be joined, The beam-column joint structure according to claim 1 , wherein the welded portion is also formed in the inclined surface.

3. Charpy absorbed energy vE in the thickness direction of the joined plate at -20 ° C. －２０（Ｓ） The column-beam joint structure according to claim 1 or 2, wherein the strength is 35 J or more.

4. Charpy absorbed energy vE in the thickness direction of the joined plate at 0 ° C. ０（Ｓ） The column-beam joint structure according to claim 1 or 2, wherein the strength is 47J or more.

5. 3. The column-beam joint structure according to claim 1, wherein the structure does not include a first reinforcing plate that is positioned at the same position as the pair of beam flanges in the vertical direction and joined to the column body.

6. The column-beam joint structure according to claim 1 or 2, which does not have a second reinforcing plate joined to the column web or the flat plate portion so as to thicken the column web or the flat plate portion.

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