Beam-column joints and their design methods

Abstract

To make a collapse form of the whole building into a whole collapse having a large energy absorbing amount by making the collapse form of a column-beam joint part not into a column collapse form but into a column-beam joint part collapse form in the column-beam joint part of a welded assembly box-shaped cross-section column and a steel beam.SOLUTION: A column beam joint part of a welded assembly box-shaped cross-section column and a steel beam is constituted by mutually joining four skin plates by corner welding, wherein the corner welding is one or both of under-match welding and partial penetration welding, a total value Σb Mp* of bending moments of material ends when the steel beam attached to a joint part panel of the beam-column joint part is in a fully plastic state, a total value Σc Mp* of fully plastic moments of material ends of the welded assembly box-shaped cross-section column attached to the joint part panel, a total plastic momentpMp1* of the joined part panel and a total plastic moment pMp2* of the joint part panel when it is assumed that the corner welding is overmatch welding and complete penetration welding are made to satisfy a prescribed relation.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a beam-column joint between a welded box section member formed by four skin plates joined together by corner welding and a steel beam, and a design method for the joint. [Background technology]

[0002] Square steel pipes, such as cold-roll-formed square steel pipes, cold-press-formed square steel pipes, and welded-assembled box section members, are often used for column members in buildings. Relatively inexpensive cold-roll-formed square steel pipes and cold-press-formed square steel pipes are often used for column members in mid- to low-rise and high-rise buildings. In contrast, column members in super-high-rise buildings require extremely high rigidity and strength, so welded-assembled box section members, which can be made larger in cross section, thicker, and stronger, are often used.

[0003] Here, welded box sections have a higher manufacturing cost than cold-roll-formed square steel pipes or cold-press-formed square steel pipes. This is due to the fact that the steel plates that make up the skin plates of welded box sections are expensive due to the increased strength of the sections, and also because welding construction management during the manufacturing of welded box sections requires a lot of man-hours and manufacturing time.

[0004] In particular, when the wall thickness of a welded box section member is extremely thick, the weld depth becomes large when the skin plates of the welded box section member are joined together by corner welding. Corner welding of welded box section members is often performed using CO2 welding or submerged arc welding, but in either case, when the corner weld depth becomes large, the corner weld cannot be performed in a single pass and the number of welding passes increases. As a result, the corner welds become multi-layered, which increases the manufacturing cost and lengthens the manufacturing time of the welded box section member.

[0005] Furthermore, in the case of multi-pass submerged arc welding, as disclosed in Non-Patent Documents 1 and 2, for example, it is necessary to perform thermal management of the interpass temperature and its holding time, as well as the post-heat temperature and its holding time, in order to prevent the weld metal from prematurely fractured at a low level and thereby reducing the strength below the base metal specification strength.

[0006] With submerged arc welding, the maximum weld depth that can be achieved in one pass is approximately 60 mm. Therefore, when using submerged arc welding to fabricate welded box-section members with a wall thickness of 60 mm or more, the corner welds become multi-layer submerged arc welding. This requires the above-mentioned heat management, which significantly lengthens the manufacturing time for welded box-section members.

[0007] To address these issues, one possible approach is to reduce the thickness of the skin plates that make up the welded box section member and increase the strength of the skin plates to compensate for the resulting decrease in overall strength of the welded box section member. This approach allows corner welding of the welded box section member to be performed using a single-pass CO2 welding or submerged arc welding. However, because the strength of the welded skin plates that make up the welded box section member must also be increased, the workability of corner welding can be reduced.

[0008] Furthermore, for example, Patent Document 1 proposes a method for manufacturing a box column in which the corners of a welded box section member are fillet welded from the inside. However, welding work inside a welded box section member places a high workload on the welder and may be dangerous. Therefore, as disclosed in Non-Patent Document 3, for example, partial penetration welding has been considered for corner welding of welded box section members.

[0009] Furthermore, with the recent increase in the size of high-rise buildings and the lengthening of column spans, there is a need for larger cross-sections and stronger steel beams. In other words, depending on the type of building, the cross-section of a beam is determined primarily to prevent beam deflection from exceeding the deflection limit as column spans increase, which may necessitate larger cross-sections and stronger steel beams. When large-section, high-strength steel beams are attached to a beam-column joint, the total full plastic strength of one or more beam members attached around the beam-column joint panel tends to be large. Furthermore, if the total full plastic strength of the beam members exceeds the total full plastic strength of the column members attached above and below the beam-column joint panel, damage may be concentrated at the column members' ends when a large bending moment acts on the beam-column joint, potentially resulting in a column-like collapse of the beam-column joint.

[0010] If the collapse pattern of the column-beam joint becomes a column collapse pattern, there is a high risk that the collapse pattern of the entire building will be a partial collapse pattern with a small amount of energy absorption, rather than a total collapse pattern with a large amount of energy absorption, and there is a risk that a story of the building will collapse with a relatively small amount of earthquake input energy. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Patent No. 5157556 [Non-patent literature]

[0012] [Non-Patent Document 1] Makoto Yuda and three others, "Study on Multi-Layer Submerged Arc Welding of Extra-Thick Box Corner Joints (SA440) Part 1: Test Outline and Preliminary Test Results," Proceedings of the Annual Meeting of the Architectural Institute of Japan (Kinki), Architectural Institute of Japan, September 2014, pp. 1045-1046 [Non-patent document 2] Takao Fukumoto and three others, "Study on Multi-Layer Submerged Arc Welding of Extra-Thick Box Corner Joints (SA440) Part 2: Preliminary Test Considerations and Actual Test Results," Proceedings of the Annual Meeting of the Architectural Institute of Japan (Kinki), Architectural Institute of Japan, September 2014, pp. 1047-1048 [Non-patent document 3] Suetomi Inoue and two others, "Study on the Load Carrying Capacity of Box Columns Assembled by Partial Penetration Welding (Part 1. Experimental Plan and Partial Penetration Welding Shear Experiments)," Proceedings of the Annual Meeting of the Architectural Institute of Japan (Kyushu), Architectural Institute of Japan, October 1989, pp. 1253-1254 [Non-patent document 4] Architectural Institute of Japan, "Guidelines for Plastic Design of Steel Structures, 3rd Edition," Architectural Institute of Japan, February 2017, pp. 150-155 [Non-patent document 5] Architectural Institute of Japan, "Guidelines for Design of Steel Structure Connections, 3rd Edition," Architectural Institute of Japan, March 2012, pp. 225-226 [Non-patent document 6] Maito Kurita and three others, "Study on the Structural Performance of Ultra-High Strength Steel CFT Members Assembled by Undermatching Welding Part 14: Hysteretic Behavior and Strength Evaluation of CFT Joint Panels with a Width-Thickness Ratio of 16.7", Proceedings of the Annual Meeting of the Architectural Institute of Japan (Tohoku), Architectural Institute of Japan, September 2018, pp. 1425-1426 Summary of the Invention [Problem to be solved by the invention]

[0013] To avoid the collapse mode of a beam-column joint, given the cross-section of the beam, the full plastic strength of the beam-column joint panel must be less than the sum of the full plastic strengths of the column members' ends to ensure the collapse mode. However, because the internal diaphragm type is often used in beam-column joints between welded box columns and steel beams, it is difficult to reduce the full plastic strength of the beam-column joint panel by, for example, reducing the column thickness at the beam-column joint panel compared to the column thickness elsewhere. Thus, in beam-column joints between welded box columns and steel beams, it is difficult to reduce the full plastic strength of the beam-column joint panel less than the sum of the full plastic strengths of the columns.

[0014] In view of the above problems, the present invention aims to change the collapse mode of the column-beam joint between a welded box section column and a steel beam from a column-beam joint to a column-beam joint panel collapse mode rather than a column collapse mode, thereby enabling the collapse mode of the entire building to be a systemic collapse mode with a large amount of energy absorption. [Means for solving the problem]

[0015] In order to solve the above problems, the present invention has the following features.

[0016] [1] A column-beam joint between a welded box section column and a steel beam, which is constructed by joining four skin plates together with corner welds, and the corner welds are one or both of undermatch welding and partial penetration welding, and the total bending moment Σ at the end of the steel beam when the steel beam attached to the joint panel of the column-beam joint is in a fully plastic state b M p * , the total plastic moment Σ of the end of the welded box section column attached to the joint panel c M p * , the total plastic moment of the joint panel p M p1 * , the total plastic moment of the joint panel when the corner weld is assumed to be an overmatch weld and a full penetration weld. p M p2* A beam-column joint that satisfies the relationships in the following equations (1) and (2).

[0017] Σ c M p * < p M p2 * ···(1) p M p1 * <Σ c M p * <Σ b M p * ···(2) Here, if a steel beam does not have an enlarged portion such as a haunch or a reinforcing material at its end and has a uniform cross section in the axial direction, the steel beam will be in a fully plastic state at the end. Therefore, in this case, the bending moment at the end when the steel beam is in a fully plastic state will be equal to the full plastic moment of the steel beam. Furthermore, if a steel beam has an enlarged portion such as a haunch or a reinforcing material at its end, the steel beam may be in a fully plastic state at a boundary between a portion where the enlarged portion or reinforcing material is provided and a portion where it is not provided. In this case, the bending moment at the end when the steel beam is in a fully plastic state will be larger than the full plastic moment of the steel beam at the boundary, etc., depending on the bending moment distribution in the axial direction of the steel beam. Therefore, when an enlarged portion or reinforcing material such as a haunch is provided at the end of a steel beam, the bending moment at the end of the steel beam when it is in a fully plastic state is calculated, taking into account that the bending strength of the steel beam changes in the axial direction due to the provision of the enlarged portion or reinforcing material.

[0018] [2] The tensile strength of the skin plate is 780N / mm 2 The above is the column-beam joint described in [1].

[0019] [3] A column-beam joint according to [1] or [2], wherein the groove depth of the corner weld is 60 mm or less.

[0020] [4] A column-beam joint according to [1] or [2], wherein the inside of the welded box section member is filled with concrete.

[0021] [5] A column-beam joint as described in [3], in which concrete is filled inside the welded box section member.

[0022] [6] The corner welds are either undermatch welds or partial penetration welds, or both, and the sum of the bending moments Σ at the ends of the steel beams attached to the joint panels of the column-beam joints when the beams are in a fully plastic state is calculated from the thickness and standard strength of the skin plate, the cross-sectional shape and standard strength of the steel beams, and the welding depth and standard strength of the corner welds. b M p * , the total plastic moment Σ of the end of the welded box section column attached to the joint panel c M p * , the total plastic moment of the joint panel p M p1 * , the total plastic moment of the joint panel when the corner weld is assumed to be an overmatch weld and a full penetration weld. p M p2 * a design method for a beam-column joint, the method including setting the plate thickness and standard strength of the skin plate, the cross-sectional shape and standard strength of the steel beam, and the weld depth and standard strength of the weld metal of the corner weld so as to satisfy the relationship of the following equations (1) and (2).

[0023] Σ c M p * < p M p2 * ···(1) p M p1 * <Σ c M p * <Σ b M p * ···(2) Here, if a steel beam does not have an enlarged portion such as a haunch or a reinforcing material at its end and has a uniform cross section in the axial direction, the steel beam will be in a fully plastic state at the end. Therefore, in this case, the bending moment at the end when the steel beam is in a fully plastic state will be equal to the full plastic moment of the steel beam. Furthermore, if a steel beam has an enlarged portion such as a haunch or a reinforcing material at its end, the steel beam may be in a fully plastic state at a boundary between a portion where the enlarged portion or reinforcing material is provided and a portion where it is not provided. In this case, the bending moment at the end when the steel beam is in a fully plastic state will be larger than the full plastic moment of the steel beam at the boundary, etc., depending on the bending moment distribution in the axial direction of the steel beam. Therefore, when an enlarged portion or reinforcing material such as a haunch is provided at the end of a steel beam, the bending moment at the end of the steel beam when it is in a fully plastic state is calculated, taking into account that the bending strength of the steel beam changes in the axial direction due to the provision of the enlarged portion or reinforcing material.

[0024] [7] The tensile strength of the skin plate is 780N / mm 2 The above is the design method for a column-beam joint described in [6].

[0025] [8] A method for designing a beam-column joint according to [6] or [7], wherein the groove depth of the corner weld is 60 mm or less.

[0026] [9] A method for designing a beam-column joint according to [6] or [7], wherein the interior of the welded box section member is filled with concrete.

[0027]

[10] A method for designing a beam-column joint as described in [8], in which concrete is filled inside the welded box section member. [Effects of the Invention]

[0028] According to the beam-column joint and its design method of the present invention, corner welds in welded box-section columns are either undermatch welds or partial penetration welds, or both. This allows the full plastic strength of the joint panel of the beam-column joint to be less than the sum of the full plastic strengths of the ends of the steel beams attached to the joint panel. Furthermore, by making the full plastic strength of the joint panel of the beam-column joint less than the sum of the full plastic strengths of the ends of the column members attached above and below the beam-column joint panel, the collapse mode of the beam-column joint can be the beam-column joint panel collapse mode. This allows the collapse mode of the beam-column joint to be the beam-column joint panel collapse mode rather than the column collapse mode, and the collapse mode of the entire building to be the overall collapse mode with high energy absorption, even when the steel beam has a large cross section or high strength and the sum of the full plastic strengths of the ends of the beam members attached to the beam-column joint panel is large.

[0029] In addition, since the corner welding of the welded box section column is one or both of undermatch welding and partial penetration welding, the workability of the corner welding of the welded box section column can be greatly improved, and the manufacturing cost and manufacturing period can be greatly reduced. [Brief explanation of the drawings]

[0030] [Figure 1] Fig. 1(a) is a perspective view showing an example of a beam-to-column joint of the present invention, and Fig. 1(b) is a cross-sectional view of a welded box section member. [Figure 2] Figures 2(a) and 2(b) are a cross-sectional view and a side view of a welded box section member. Figures 2(c) and 2(d) are a cross-sectional view and a side view of a mechanical model of a welded box section member. Figures 2(e) and 2(f) are a cross-sectional view and a side view of a mechanical model when a shear force acts on a welded box section member from the 0° direction. [Figure 3] 3(a) to 3(c) are side views showing the shear deformation region and bending deformation region that occur when a shear force acts on a welded box cross-section member from the 0° direction. [Figure 4] FIG. 4 is a graph showing the strength of the panel portion of a beam-to-column joint when a shear force acts on a welded box section member from the 0° direction. [Figure 5] 5(a) and 5(b) are diagrams showing test specimens used in a loading test carried out to verify the effects of the beam-column joint and its design method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0031] Hereinafter, embodiments of the beam-column joint and the design method thereof according to the present invention will be described in detail with reference to the drawings.

[0032] Fig. 1(a) shows a beam-column joint 1 of this embodiment. Fig. 1(b) shows a cross-sectional view of a welded box section column 10 that constitutes the beam-column joint panel portion of the beam-column joint 1.

[0033] As shown in Figures 1(a) and 1(b), the beam-column joint 1 of this embodiment is a beam-column joint between a steel beam 20 and a welded box section column 10 formed by four skin plates 11, 12 joined together by corner welds 13. In this embodiment, the steel beam 20 is made of an H-shaped steel, but the steel beam in the present invention is not limited to this.

[0034] 1(a) shows an example of a column-beam joint of the present invention in which welded box section columns 10 are attached to the top and bottom of the column-beam joint panel, and steel beams 20 are attached to the left and right of the column-beam joint panel. However, the present invention is not limited to this example and can also be applied to cases in which a welded box section column 10 is attached only below the column-beam joint panel, or to cases in which one or three or more steel beams 20 are attached around the column-beam joint panel.

[0035] As shown in Figure 1(b) , in the beam-to-column joint 1 of this embodiment, the corner welds 13 joining the four skin plates 11, 12 are partial penetration welds. However, the corner welds of the present invention are not limited to this, and may be full penetration undermatch welds or partial penetration and undermatch welds.

[0036] Furthermore, the shape and material strength of the skin plates 11, 12 and corner welds 13 of the welded box section column 10 that constitute the beam-to-column joint 1 of this embodiment, as well as the steel beam 20, are set to satisfy the relationships of the following equations (1) and (2). That is, the plate thickness t and yield strength σ of the skin plates 11, 12 of the welded box section column 10 are y , the welding depth t of the corner weld 13 w and the strength of the weld metal σ yw , and the cross-sectional size and yield strength of the steel beam 20 are set so as to satisfy the relationships of the above formulas (1) and (2).

[0037] Σ c M p * < p M p2 * ···(1) p M p1 * <Σ c M p * <Σ b M p * ···(2) In addition, the design method for a beam-column joint according to this embodiment determines the plate thickness t and the reference strength σ of the skin plates 11 and 12 so as to satisfy the relationship between the above formulas (1) and (2). y , the welding depth t of the corner weld 13 w and the strength of the weld metal σ yw , as well as the cross-sectional size and standard strength of the steel beam 20.

[0038] Here, in the above equations (1) and (2), Σ b M p * is the total bending moment at the end of the steel beam 20 attached to the joint panel of the beam-column joint 1 when it is in a fully plastic state, and Σ c M p * is the total value of the total plastic moment at the end of the welded box section column 10 attached to the joint panel. p M p1 *is the total plastic moment of the joint panel, p M p2 * is the total plastic moment of the joint panel when the corner weld 13 is assumed to be an overmatched weld with full penetration.

[0039] Bending moment at the end of the steel beam 20 when it is in a fully plastic state b M p * , the total plastic moment at the end of the welded box section column 10 c M p * , and the full plastic moment of the joint panel when the corner weld 13 is assumed to be an overmatched weld and fully penetrated. p M p2 * can be calculated by the method described in Non-Patent Document 4, for example.

[0040] In addition, the full plastic moment of the joint panel taking into account the reduction in strength due to the corner weld 13 being either an undermatch weld or a partial penetration weld, or both, p M p1 * The following was considered regarding this matter.

[0041] First, as shown in Fig. 2(a) to Fig. 2(d), in a welded box section column 10, the plate thickness t of the skin plate and the welding depth t of the corner weld are w is assumed to be sufficiently small compared to the plate width of the skin plates 11 and 12, and the skin plates 11 and 12 are concentrated at the center of the plate thickness, and a mechanical model was established that ignores the shear stress occurring in the plate thickness direction of the skin plates 11 and 12.

[0042] It was assumed that when a shear force acts on the welded box column 10, shear deformation and bending deformation occur in each part of the welded box column 10 as follows.

[0043] First, as shown in Figures 2(e) and 2(f), when the direction of the shear force acting on the welded box section column 10 is parallel to the width direction of one of the pair of opposing skin plates 11 and the other pair of opposing skin plates 12 (hereinafter referred to as "when a force is applied in the 0° direction"), the following assumptions were made. That is, the pair of skin plates 11 parallel to the shear force have a width (d c It is assumed that shear deformation occurs in the area of (-X) mm, and bending deformation occurs at the top and bottom ends of the beam-column joint panel in the area of width (X / 2) mm at both ends in the width direction. However, d c is the distance between the center of the thickness of the skin plates 11 and 12 of the welded box section column 10, and d is the distance between the center of the thickness of the skin plates 11 and 12 of the welded box section column 10 with respect to the width D of the welded box section column 10. c =Dt, and the range of X is 0≦X≦d c / 2. Furthermore, it was assumed that all corner welds 13 undergo shear deformation.

[0044] In the dynamic model described above, the value of X is set to 0≦X≦d c The shear strength of the beam-column joint panel of the welded box column 10 was calculated while varying the shear strength within the range of 1 / 2. The smallest value among these shear strengths was then taken as the shear strength of the beam-column joint panel of the welded box column 10. Specifically, the calculations were carried out with reference to the calculation methods described in Non-Patent Documents 4 and 5. In this way, the shear strength of the beam-column joint panel of the welded box column 10 was calculated. p M pa The results were as shown in the following equations (3) to (5).

[0045] When applying force in the 0° direction, (1) 1≦(t w σ yw ) / (t σ y ) (see Figure 3(a)),

[0046]

number

[0047] (2)1-√3(d c / d b )≦(t w σ yw ) / (t σ y ) ≦ 1 (see Figure 3(b)),

[0048]

number

[0049] (3)(t w σ yw ) / (t σ y )≦1-√3(d c / d b ) (see Figure 3(c)),

[0050]

number

[0051] However, d in the above formulas (4) to (5) b is the height of the panel at the column-beam joint. p M p0 The "guidelines" are values calculated using the following formula (6).

[0052]

number

[0053] Here, the " p M p0 The "Guideline" is a strength evaluation formula for a beam-column joint panel described in Non-Patent Document 5, and is the value of the bending moment acting on the beam-column joint panel when the entire beam-column joint panel undergoes shear deformation and reaches its full plastic strength. p M p0The "Guideline" is currently the most widely used formula for evaluating the strength of beam-to-column joint panels in welded box section members constructed so that corner welds 13 are full penetration welds and overmatch welds in which the strength of the weld metal in the corner welds exceeds the strength of the base material.

[0054] The shear strength of the column-beam joint panel of the welded box section column 10 calculated by the above formulas (3) to (5) p M pa is the yield strength of the weld metal of the corner weld (t w σ yw ) and base material yield strength (t σ y ) and the ratio (t w σ yw ) / (t σ y ) and the aspect ratio db / dc of the beam-column joint panel. This is explained below.

[0055] Figure 4 shows the ratio of the yield strength of the corner weld 13 to the base material yield strength (t w σ yw ) / (t σ y ) is changed in the range of 0.0 to 1.2, the shear strength of the beam-column joint panel when a force is applied in the 0° direction calculated using the above formulas (3) to (5) p M pa The value of " p M p0 Ratio to "Guidelines" p M pa / ( p M p0 The change in the aspect ratio d of the panel at the column-beam joint b / d c The graph shows the cases where is 1.0, 1.5, and 2.0.

[0056] As shown in Figure 4, the yield strength (t w σ yw ) and base material yield strength (t σ y ) and the ratio (t w σ yw ) / (t σ y ) decreases, the strength of the beam-column joint panel decreases, and the aspect ratio d b / dc The larger the value, the greater the decrease in the strength of the beam-column joint panel. In other words, by using either or both of undermatch welding and partial penetration welding for the corner welds 13 at least in the joint panel portion of the beam-column joint 1, the full plastic strength of the joint panel of the beam-column joint 1 can be reduced. p M p1 * The full plastic yield strength of the joint panel, taking into account the reduction in yield strength due to the corner welds 13 being either undermatch welds or partial penetration welds, can be reduced. p M p1 * As shown in Figure 4, the yield strength (t w σ yw ) and base material yield strength (t σ y ) and the ratio (t w σ yw ) / (t σ y ) can be understood based on

[0057] In addition, in the beam-column joint 1 and the design method thereof according to the present embodiment, the tensile strength of the skin plates 11 and 12 constituting the welded box section column 10 is set to 780 N / mm 2 At present, the strength of the steel plates generally used as skin plates for welded box section columns is 780N / mm 2 It is about 780N / mm 2 Steel plates of grades 780N / mm or higher tend to have smaller fracture elongation than steels with lower strength, and when they are used as skin plates for welded box section columns, the skin plates are generally not expected to have deformation capacity and are designed to be used within the elastic range. However, as described in Non-Patent Document 6, 2 It has been reported that even steel of this grade exhibits a large deformation capacity within the panel at the beam-to-column joint. 2 Even when steel plates of this class are used for the skin plates 11, 12, the collapse type of the column-beam joint 1 between the welded box section column 10 and the steel beam 20 is a column joint panel collapse type, and the deformation capacity of the column-beam joint 1 can be sufficiently secured.

[0058] In addition, in the beam-to-column joint 1 and its design method of this embodiment, the groove depth of the corner welds 13 is preferably 60 mm or less. As mentioned above, the maximum weld depth that can be achieved in one pass with submerged arc welding is approximately 60 mm. Therefore, when fabricating a welded box section member with a wall thickness of 60 mm or more using submerged arc welding with overmatch welding and full penetration welding, the corner welds 13 become multi-layer submerged arc welding, which requires post-heat management, significantly lengthening the fabrication period of the welded box section member.

[0059] In contrast, in the beam-column joint 1 of this embodiment, the welding depth t w By reducing the groove depth of the corner welds 13 to a minimum, partial penetration welding is possible, and by making the groove depth of the corner welds 13 60 mm or less, the corner welds 13 can be welded in one pass even when the skin plates 11, 12 of the welded box column 10 have a large thickness t. This eliminates the need for post-heat management, as is required when welding a welded box member with a thickness of 60 mm or more using full-penetration multi-layer submerged arc welding. This significantly improves the ease of welding the corner welds 13, and significantly reduces the manufacturing cost and time for the welded box column 10. When the skin plates 11, 12 of the welded box column 10 have a thickness t of approximately 65 mm or less, the above-mentioned effects can be achieved by using partial penetration welding for the corner welds 13, even if the groove depth of the corner welds 13 is not 60 mm or less.

[0060] By using undermatch or partial penetration welding for the corner welds 13, the strength of the welded box column 10 is significantly affected mainly at the joint panel portion. However, in order for the welded box column 10 to reliably transmit shear forces in areas other than the joint panel portion, the ratio of the strength of the weld metal of the corner welds 13 of the welded box column 10 to the strength of the base metal (t w σ yw ) / (t σ y ) is preferably 0.3 or more.

[0061] The beam-to-column joint 1 and its design method of this embodiment can also be applied to a welded box section column 10 in which the interior is filled with concrete (not shown). [Example]

[0062] In order to verify the effectiveness of the beam-column joint and its design method of the present invention, the collapse mode of the beam-column joint was confirmed by numerical analysis, which will be explained below.

[0063] In this numerical analysis, a planar cross-shaped frame analysis model shown in Figure 5 was subjected to a numerical analysis under the condition that an axial force was applied to the welded box section column 10 while shear forces were applied anti-symmetrically to both ends of the steel beam 20, and the collapse mode of the beam-column joint 1 was confirmed.

[0064] Specifically, the yield strength σ of the skin plates 11 and 12 constituting the welded box section column 10 of the planar cross frame is y 630N / mm 2 The column width was 800 mm, the plate thickness t was 80 mm, and the column height was 12,000 mm. Two types of corner welds 13 were set: corner weld A (example of the present invention) and corner weld B (comparison example). B For the weld metal yield strength σ yw 630N / mm 2 , groove depth t w The analytical model was set up assuming that the welding was performed with multi-pass submerged arc welding to achieve even match welding, with the welding distance set at 80 mm. A For the weld metal yield strength σ yw 325N / mm 2 , groove depth t w The analytical model was set up assuming that the welding was performed in one pass with the distance between the joint and the joint being 50 mm, resulting in an undermatch weld.

[0065] In addition, the yield strength of the steel beam 20 was set to 440 N / mm in order to simulate the case where the bending moment at the end of the steel beam 20 is large when the steel beam 20 is in a fully plastic state. 2The beam width was 600 mm, the beam depth was 1600 mm, the beam flange thickness was 80 mm, the beam web thickness was 40 mm, and the beam length was 24000 mm.

[0066] The upper end of the welded box section column 10 in the axial direction is supported by pin rollers, and the lower end of the welded box section column 10 is supported by pins. The axial force ratio is 0.4 (the yield axial force of the welded box section column 10 is N y So, 0.4N y ) is assumed to act. As shown in FIG. 5, when a shear force Q acts in the up and down opposite directions on the end of the steel beam 20 in the axial direction, the total bending moment Σ of the end of the steel beam 20 when the steel beam 20 attached to the joint panel is in a fully plastic state is b M p * , the total plastic moment Σ of the end of the welded box section column 10 attached to the joint panel c M p * , full plastic moment of the joint panel p M p1 * or p M p2 * The results of this numerical analysis are shown in Table 1.

[0067] [Table 1]

[0068] As shown in Table 1, in the comparative example of corner weld 13 and corner weld B, the total bending moment Σ at the end of the steel beam 20 when it is in a fully plastic state is b M p * , the total plastic moment of the end of the welded box section column 10 Σ c M p * , full plastic moment of the joint panel p M p2 * Among them, Σ c M p *In other words, it is highly likely that damage will be concentrated at the ends of the welded box section columns 10 adjacent to the joint panel of the beam-column joint 1, and that the collapse mode of the beam-column joint 1 will be a column collapse mode.

[0069] In contrast, in the example of the present invention in which the corner weld 13 is corner weld A, the total bending moment Σ b M p * , the total plastic moment of the end of the welded box section column 10 Σ c M p * , full plastic moment of the joint panel p M p1 * Of these, p M p1 * In other words, the collapse mode of the beam-column joint 1 can be the collapse mode of the joint panel. p M p1 * and the total plastic moment Σ at the end of the welded box section column 10 c M p * Relative to p M p * / Σ c M p * is 0.77, and when the joint panel collapses, the strength of the end of the welded box section column 10 still has about 20 to 30 percent of its remaining strength.

[0070] From the above, it has been confirmed that the column-beam joint and its design method of the present invention can cause the collapse pattern of the column-beam joint to be that of the column-beam joint panel rather than that of the column, even when the steel beam has a large cross section or high strength and the total value of the full plastic strength of the ends of the beam members attached to the column-beam joint panel is large. [Explanation of symbols]

[0071] 1 Column beam joint 10 Welded box section columns 11, 12 Skin Plate 13 Corner welding 20 Steel beams t Skin plate thickness t w Corner weld depth σ y Skin plate yield strength σ yw Yield strength of corner weld weld metal

Claims

1. A column-beam joint between a welded box section column and a steel beam, which is formed by four skin plates joined together by corner welding, the corner weld is one or both of an undermatch weld and a partial penetration weld; The sum of the bending moments at the ends of the steel beams attached to the joint panel of the beam-column joint when they are in a fully plastic state Σ ｂ M ｐ ＊ , the total plastic moment Σ of the end of the welded box section column attached to the joint panel ｃ M ｐ ＊ , the total plastic moment of the joint panel ｐ M ｐ１ ＊ , the total plastic moment of the joint panel when the corner weld is assumed to be an overmatch weld and a full penetration weld. ｐ M ｐ２ ＊ A column-beam joint that satisfies the following equations (1) and (2). S ｃ M ｐ ＊ < ｐ M ｐ２ ＊ ・・・(1) ｐ M ｐ１ ＊ <S ｃ M ｐ ＊ <S ｂ M ｐ ＊ ・・・(2)

2. The tensile strength of the skin plate is 780 N / mm ２ The column-beam joint according to claim 1 .

3. The column-beam joint according to claim 1 or 2, wherein the groove depth of the corner weld is 60 mm or less.

4. 3. The beam-column joint according to claim 1, wherein the inside of the welded box section column is filled with concrete.

5. The beam-column joint according to claim 3 , wherein the interior of the welded box section column is filled with concrete.

6. A design method for a column-beam connection between a welded box section column formed by four skin plates joined together by corner welds and a steel beam, comprising: the corner weld is one or both of an undermatch weld and a partial penetration weld; The sum Σ of the bending moments at the ends of the steel beams when the steel beams attached to the joint panel of the beam-column joint are in a fully plastic state is calculated from the plate thickness and standard strength of the skin plate, the cross-sectional shape and standard strength of the steel beams, and the weld depth and standard strength of the corner welds. ｂ M ｐ ＊ , the total plastic moment Σ of the end of the welded box section column attached to the joint panel ｃ M ｐ ＊ , the total plastic moment of the joint panel ｐ M ｐ１ ＊ , the total plastic moment of the joint panel when the corner weld is assumed to be an overmatch weld and a full penetration weld. ｐ M ｐ２ ＊ a design method for a column-beam joint, the method including: setting the plate thickness and standard strength of the skin plate, the cross-sectional shape and standard strength of the steel beam, and the weld depth and standard strength of the weld metal of the corner weld so as to satisfy the relationship of the following formulas (1) and (2). S ｃ M ｐ ＊ < ｐ M ｐ２ ＊ ・・・(1) ｐ M ｐ１ ＊ <S ｃ M ｐ ＊ <S ｂ M ｐ ＊ ・・・(2)

7. The tensile strength of the skin plate is 780 N / mm ２ The method for designing a beam-column joint according to claim 6 .

8. 8. The method for designing a beam-to-column joint according to claim 6 or 7, wherein the groove depth of the corner weld is 60 mm or less.

9. 8. The method for designing a beam-column joint according to claim 6, wherein the interior of the welded box section column is filled with concrete.

10. The method for designing a beam-column joint according to claim 8 , wherein the inside of the welded box section column is filled with concrete.

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