Welded joint structure of upper and lower column members, welding joining method, and upper and lower column members

Abstract

To provide a welded joint structure of upper and lower column members excellent in terms of ease of construction, cost-effectiveness, and rationality, which is capable of changing conventional overly complex designs into rational designs; for example, the strength of a column joint (a connection point of hollow-section column members) can be designed to be lower than that of a column splice by devising countermeasures for situations where a connection does not satisfy the requirement of load-carrying capacity, a welding joining method, and upper and lower column members.SOLUTION: In the butt-welded joint of hollow-section column members 1, which are positioned vertically, the column members 1 are joined in such a way that openings 1a are formed on side surfaces so that the full plastic bending strength of the column members 1 is equal to or less than the fracture strength of the welded joint. An opening 1a is formed on a side surface of the lower column member 1. The lower column member 1a is installed vertically on an upper surface of a column-beam joint 10 or a column base. The upper and lower column members 1 are butt-welded together at the welded joint 2, with one or more areas left unwelded.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to the technical field of butt-welded joint structures of hollow cross-section column members arranged one above the other. [Background technology]

[0002] When joining hollow cross-section column members arranged above and below at a construction site using full penetration welding, the upper and lower column members are temporarily fixed using an erection piece (and splice plate), and after the first 2 to 3 passes of welding, the erection piece is cut or removed, and the remaining welding is done again, and the column member is finished with full penetration welding. Alternatively, the column member is divided into welding areas using an erection piece (and splice plate), and half of the divided area is first welded in several layers starting and ending at the erection piece position, and then the erection piece is cut or removed, and the remaining area is welded again and finished with full penetration welding. This is a common method. Therefore, in the conventional general welding method described above, the erection piece (and splice plate) acts as a baffle, so the welding work is divided into "welding" → "cutting or removing the erection piece" → "welding", which is a problem of poor work efficiency.

[0003] In recent years, as disclosed in Patent Documents 1 to 4, efforts have been made to improve the efficiency of welding work by introducing welding robots, but the welding work remains divided into "welding" → "cutting or removing the erection piece (or plumbing jig)" → "welding."

[0004] Incidentally, in the middle of page 103 of Non-Patent Document 1, it is stated that it is desirable to set column joints (joints of hollow cross-section column members) at positions where stress is small, and that it is desirable to set them at least 1.5D (D is the column outer diameter) away from the top of the beam (or diaphragm). Therefore, taking this statement into consideration, on-site column joints are often set at a position about 1m away from the floor (above the beam). When considering the distribution of bending moments caused by shear forces acting on hollow cross-section column members, the bending moment at the column joint is smaller than at the column connection, so even if the strength is lower than at the column connection, there is no problem with the structural performance of the entire building. However, the position of the column joint on site is designed and constructed with full penetration welding around the entire circumference of the hollow cross-section, ensuring performance and quality equivalent to that of the column-diaphragm weld at the column connection, which is the column in the most severe stress state and is prone to becoming the starting point of fracture or buckling, and in reality, the design and construction are excessive.

[0005] On the other hand, even though the above-mentioned statement "Even if the strength is lower than the column-joint part, there is no problem in terms of the structural performance of the entire building," designing the column joint position to be weaker than the column-joint part could lead to the possibility that the joint would not meet the required strength during actual on-site construction. However, there is currently no way to deal with such cases. Therefore, even though the above-mentioned statement "Even if the strength is lower than the column-joint part, there is no problem in terms of the structural performance of the entire building," the reality is that in structural designs that involve human lives, it is not possible to design the column joint position to be weaker than the column-joint part. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2018-53626 [Patent Document 2] Japanese Patent Application Publication No. 2019-155409 [Patent Document 3] Patent Publication No. 2021-65899 [Patent Document 4] Japanese Patent Publication No. 2022-146750 [Non-Patent Document 1] "Cold-Formed Square Steel Pipe Design and Construction Manual 2018 Edition" published by the Building Center of Japan, page 102, page 103 Summary of the Invention [Problem to be solved by the invention]

[0007] If it were possible to devise a countermeasure for cases where the aforementioned strength-bearing joints are not satisfied, it would clearly be more beneficial, as it would enable the position of the column joint to be designed with a lower strength than the column-to-column joint, thereby changing the conventional excessive design to a more rational design.

[0008] The present invention was devised in consideration of the problems of the background art described above, and its purpose is to provide a welded joint structure and welding joint construction method for upper and lower column members, as well as upper and lower column members, that are excellent in workability, economy, and rationality, and that can change the conventional excessive design to a rational design by devising a countermeasure for when the inherent strength joint is not satisfied, such as making it possible to design the position of the column joint (the joint portion of the column member with a hollow cross section) to have a lower strength than the column connection portion. [Means for solving the problem]

[0009] As a means for solving the above problems, the welded joint structure of upper and lower column members according to the invention described in claim 1 is a butt-welded joint of hollow cross-section column members arranged above and below, The column members are joined with openings provided on their sides so that the total plastic bending strength of the column members is equal to or less than the fracture strength of the welded joint.

[0010] The invention described in claim 2 is characterized in that in the welded joint structure of upper and lower pillar members described in claim 1, an opening is provided on the side surface of the lower pillar member.

[0011] The invention described in claim 3 is characterized in that, in the welded joint structure of upper and lower column members described in claim 2, the lower column member is erected on the upper surface of the column-beam joint or column base.

[0012] The invention described in claim 4 is characterized in that, in the welded joint structure of upper and lower pillar members described in claim 1, the upper and lower pillar members are butt-welded, leaving one or more unwelded portions.

[0013] The invention described in claim 5 is characterized in that, in the welded joint structure of the upper and lower pillar members described in claim 4, the non-welded part is between the upper and lower pillar members and is at a position corresponding to the attachment site of the erection piece.

[0014] The invention described in claim 6 is characterized in that, in the welded joint structure of upper and lower pillar members described in claim 4, the total area of ​​the opening provided on the side of the pillar member is set to be equal to or larger than the total area of ​​the non-welded portion.

[0015] The upper and lower pillar members according to the invention recited in claim 7 are characterized in that they are used in the welded joint structure of the upper and lower pillar members recited in any one of claims 1 to 6.

[0016] The welding and joining method for upper and lower column members according to the invention described in claim 8 is a butt welding and joining method for hollow cross-section column members arranged above and below and equipped with erection pieces, The method comprises a step of temporarily fixing the upper pillar member by aligning it with the lower pillar member using the erection piece, a step of welding the upper and lower pillar members, and a step of removing the erection piece, In the welding process, in the welding between the upper and lower pillar members, the position corresponding to the attachment portion of the erection piece is left unwelded; The lower pillar member is characterized by having an opening on its side surface that is equal to or larger than the entire area of ​​the portion that is left unwelded.

[0017] The invention described in claim 9 is characterized in that, in the welding joining method for upper and lower column members described in claim 8, the lower column member is erected on the upper surface of the column-beam joint or the column base. [Effects of the Invention]

[0018] The welding and joining structure and welding and joining method for upper and lower pillar members, and the upper and lower pillar members according to the present invention have the following effects. (1) Even if the position of the column joint (the joint portion of the hollow cross-section column member) is weaker than the column connection, we have devised a solution that can easily satisfy the required strength by creating an opening (hole) on the side of the column member. This allows us to safely design the position of the column joint to be weaker than the column connection, thereby changing the conventional excessive design to a rational design. Therefore, we can realize a welded joint structure and welding joint construction method for upper and lower column members, as well as upper and lower column members, that are excellent in workability, economy, and rationality. (2) Specifically, based on the aforementioned "the position of the column joint can be designed with a lower strength than the column connection," even if the welding work is completed without welding the position corresponding to the erection piece attachment point (with an opening), even if the required strength of the joint cannot be met, it is now possible to easily meet the required strength by creating an opening (hole) on the side of the column member. Therefore, it is possible to omit the conventional finishing welding work after removing the erection piece, and the welding work can be performed continuously (in one go) without interruption. As a result, the amount of welding can be reduced, the welding work can be labor-saving, and work efficiency can be dramatically improved, resulting in a welded joint structure and welding method for upper and lower column members, as well as upper and lower column members, that are extremely easy to work with, economical, and rational. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a perspective view showing the main parts of the welded joint structure of upper and lower pillar members according to the present invention. FIG. [Figure 2] 2 is an explanatory diagram showing a welding joining method for joining upper and lower pillar members according to the present invention for the portion X in FIG. 1.

[0033] FIG. [Figure 3]This is a schematic diagram of an FEM analysis simulating a three-point bending test and the formula for the stress ratio (γ). As shown in the schematic diagram, in a three-point bending test, a moment gradient occurs where the moment is greatest at the position of load P and smallest at the position of the support. Similarly, when columns in a steel building frame are subjected to horizontal force due to an earthquake, a moment gradient occurs that is determined by the balance between the horizontal force due to the earthquake and the building's own weight. Therefore, the stress ratio (γ) is calculated taking into account that the stress acting on the column end and column joint varies depending on the moment gradient. [Figure 4] 1 is a table showing analysis parameters. [Figure 5] A is a model diagram of an FEM analysis related to the condition where a horizontal force is applied at 0 degrees to the center of the plate thickness of a through diaphragm, B is a left side view of A, and C is a diagram showing the size of the components, etc. Similarly, D is a model diagram of an FEM analysis related to the condition where a horizontal force is applied at 45 degrees to the center of the plate thickness of a through diaphragm, E is a left side view of D, and F is a diagram showing the size of the components, etc. Note that while the diagram is a 1 / 1 model, the actual analysis model is a 1 / 4 model. [Figure 6] 5A is a detailed view of the column-through diaphragm weld in FIG. 5, and FIG. 5B is a detailed view of the column joint weld in FIG. [Figure 7] A is a diagram showing a cross section at the position of the column joint (joint portion of a column member with a hollow cross section) of the present invention 1 and a cross section at the center of the hole portion (opening 1a) of the present invention 1, B is a diagram showing a cross section at the position of the column joint of the present invention 2 and a cross section at the center of the hole portion of the present invention 2, C is a diagram showing a cross section at the position of the column joint of the present invention 3 and a cross section at the center of the hole portion of the present invention 3, and D is a diagram showing a cross section at the position of the column joint of the present invention 4 and a cross section at the center of the hole portion of the present invention 4. [Figure 8] A is an analytical model diagram showing the boundary conditions when the force is applied in the 45-degree direction, and B is an analytical model diagram showing the boundary conditions when the force is applied in the 0-degree direction. [Figure 9] Graphs A to D are graphs showing the corresponding M-θ relationships for Conventional Examples 1 and 2 and Inventions 1 to 4, respectively, Conventional Example 1 and Invention 1, etc. [Figure 10]1 is a table showing the full plastic bending strength for Conventional Examples 1 and 2 and Inventions 1 to 4. [Figure 11] 1A and 1B are von Mises stress distribution diagrams for Conventional Example 1 and Conventional Example 2, respectively, at the time of full plastic bending yield strength. [Figure 12] 5A to 5D are von Mises stress distribution diagrams at the time of full plastic bending yield strength according to inventions 1 to 4, respectively. [Figure 13] 1 is a graph showing the results of tensile tests (SS curves) for four material properties. DETAILED DESCRIPTION OF THE INVENTION

[0020] Next, an embodiment of a welding joint structure and a welding joint method for upper and lower pillar members according to the present invention, as well as the upper and lower pillar members, will be described with reference to the drawings. [Example]

[0021] FIG. 1 shows the main parts of the welded joint structure of upper and lower pillar members 1, 1. The butt welded joints of hollow cross-section column members (square steel pipe columns) 1, 1 arranged above and below are joined 2, or more specifically, joined with a carrying capacity 2, with an opening 1a provided on the side of the column member 1 so that the total plastic bending strength of the column member 1 is equal to or less than the fracture strength of the welded joint. 1, the opening 1a is provided on the side surface of the lower pillar member 1. The lower pillar member 1 is erected on the upper surface of the through diaphragm 11 of the pillar-beam joint 10, but may also be erected on the upper surface of the pillar base. The hollow cross-section column member 1 is, as an example only, implemented with outer dimensions (D) of 750 x 750 mm and plate thickness (t) of 60 mm, and the welding position (column joint position) is implemented at a height of approximately 1200 mm from the position of the through diaphragm 11. Here, in this specification, the term "bearing strength connection" is used to mean ensuring the strength of the connection so that a force sufficient to exert the member's bearing strength can be transmitted without causing destruction at the connection. At the joint portion of the column members (column joint), in a butt joint structure of hollow cross-section column members arranged above and below, the "bearing strength connection" is satisfied when the total plastic bending strength of the column members is equal to or less than the fracture strength of the welded joint.

[0022] In the embodiment of Fig. 1, two hollow cross-section column members (square steel pipe columns) 1, 1 arranged above and below are butt welded 2, leaving one or more unwelded portions (openings) 3. In the embodiment of Fig. 1, the welding is done by full penetration welding. The non-welded portions 3 are located between the upper and lower pillar members 1, 1, at positions corresponding to the attachment locations of the erection piece 7 and the splice plate 8. In the embodiment of FIG. 1, the non-welded portions 3 are located at four locations in total, one at approximately the center of each of the four sides of the pillar member 1, but this is not limited to this. As shown in FIG. 7B, the non-welded portions 3 may be located at four locations in total, at each corner portion (corner portion) of the pillar member 1. The number and locations of the non-welded portions 3 can be appropriately changed depending on the structural design. Of course, as shown in FIGS. 7C and 7D, there are also cases where the entire circumference of the hollow cross section is fully penetrated and welded without providing any non-welded portions (openings). Here, in this specification, the "non-welded portion" may be referred to as an "opening" for convenience, but it should be noted that there are cases where the non-welded portion does not constitute an "opening", such as when an end tab remains after welding and blocks a hole. Furthermore, in this specification, the hole drilled in the side of the (lower) column member 1 is referred to as the "opening 1a," and the part of the column joint that is not welded is referred to as the "opening" for convenience, and it should be noted that "opening 1a" and "opening" are clearly used to refer to different parts.

[0023] Next, the opening 1a, which is a feature of the present invention, will be described. In the embodiment of Fig. 1, the openings (holes) 1a are implemented in a substantially elliptical shape and are provided in a total of four locations, one at each of the approximately central portions of the four side surfaces of the lower pillar member 1 and below the erection piece 7, but this is not limited to this, and as shown in Fig. 7B, the openings 1a may be provided in a total of four locations at each corner portion (corner portion) of the pillar member 1. The number and locations of the openings 1a can be appropriately changed according to the structural design. Incidentally, the hole processing of the openings 1a can be easily performed not only in a factory but also on site. In terms of structural design, the overall area of ​​the opening 1a is set to be equal to or larger than the overall area of ​​the non-welded portion (opening) 3 formed at the welded joint 2 of the upper and lower column members 1, 1.

[0024] Specifically, eight erection pieces 7 according to the embodiment of Fig. 1 are used, one at the approximate center of each of the four sides of the upper and lower column members 1, 1. The splice plates 8 are arranged two by two so as to sandwich the erection pieces 7, 7 arranged above and below, so a total of eight are used in four locations. The erection pieces 7 and the splice plates 8 are fastened with fasteners such as high-strength bolts 9.

[0025] Thus, the welding joining method for the upper and lower column members 1, 1 according to the present invention is a butt welding joining method for hollow cross-section column members 1, 1 arranged above and below and equipped with an erection piece 7, and includes the steps of: aligning and temporarily fixing the upper column member 1 to the lower column member 1 using fasteners such as the erection piece 7, splice plate 8, and high-strength bolt 9; welding the upper and lower column members 1; and removing the erection piece 7 as well as the fasteners such as the splice plate 8 and high-strength bolt 9. In the welding process, the position corresponding to the attachment site of the erection piece 7 is left unwelded when welding between the upper and lower pillar members. The lower pillar member 1 is completed with the welding joining method in a state where it has an opening 1a on its side that is equal to or larger than the entire area of ​​the part 3 that was left unwelded (see Figure 2). Incidentally, the symbol 7' in Figure 2 indicates the mark left after the erection piece 7 was removed.

[0026] In short, as stated in the second paragraph of the above paragraph

[0004] , the welded joint structure of the upper and lower column members 1, 1 according to the present invention is such that "when the bending moment distribution caused by the shear force acting on a column member with a hollow cross section is taken into consideration, the bending moment at the column joint position is smaller than that at the column connection part, and therefore even if the strength is lower than that at the column connection part, there is no problem in terms of the structural performance of the entire building," and therefore the applicant has determined that there is no problem in terms of structural performance even if the amount of welding at the column joint position (the joint part of the column members) is reduced to some extent. On the other hand, although it was stated above that "even if the strength is lower than that of the column-joint section, there is no problem with the structural performance of the entire building," designing the column joint position to be weaker than the column-joint section could lead to cases where the required strength of the joint is not met during actual on-site construction. Therefore, the applicant devised a solution that can easily satisfy the required strength of the joint by drilling a hole in the side of the column member, even if the column joint position is weaker than the column connection part.The applicant analyzed whether it is possible to balance the technical idea of ​​reducing the amount of welding in the column joint (welded joint) with the technical idea of ​​drilling an opening in the side of the lower column member (base material) so as to satisfy the required strength of the joint.As a result of the analysis, the applicant concluded that it is possible to balance them, as described below.

[0027] The analysis involved using FEM analysis to verify whether there would be any problems with the structural performance of the building as a whole even if some parts were left unwelded. The FEM analysis model is a model that simulates the three-point bending test, which is the most common test for comparing the structural performance of hollow cross-section column members, as shown in Figure 3. The analysis parameters are shown in Figure 4.

[0028] For a member having a hollow cross-section column member of a steel building frame having a column joint portion (joint portion of the column member) and a through diaphragm welded to the beam attachment portion of the column member (see Figures 3 and 5), For each of the cases where the column joint is fully penetrated welded around the entire circumference of the cross section, and for the case where the column joint has an opening in one or more places where the start and end of the weld do not intersect and the upper and lower hollow cross-section column members are joined by full penetration welding, a numerical analysis was carried out using the finite element method to determine the bending moment and deformation angle relationship of the member and the full plastic bending strength when a horizontal external force such as an earthquake is applied, with the parameters being ``opening width,'' ``opening position,'' ``force application direction (direction of horizontal force application),'' and ``presence or absence of holes in the base material.''

[0029] The analytical model is shown in Figures 5A and 5B, but this analysis was performed using a 1 / 4 model in consideration of the symmetry of the analytical model. In this numerical analysis, the geometry of the hollow cross-section column member of the steel building frame was set to external dimensions (D) 750 x 750 mm, plate thickness (t) 60 mm, corner curvature radius (outer periphery) R = 210 mm, column member length L / 2 = 2000 mm, the plate thickness of the through diaphragm was 60 mm, and the projection dimension of the through diaphragm from the hollow cross-section column member was set to 30 mm, as shown in Figure 6A. The geometry of the weld between the column member and the through diaphragm was set to a root gap of 7 mm, a groove angle of the column body of 35 degrees, a weld height of 15 mm on the through diaphragm side, and a backing plate of 9 mm x 25 mm, and the penetration of the weld was not taken into account. In addition, as shown in Figure 6B, the shape of the weld at the column joint was set to a groove on the upper floor column side, with a root gap of 7 mm, a groove angle of 35 degrees, and a backing plate of 9 mm x 50 mm, and the excess weld and penetration of the weld were not taken into consideration. Common types of hollow cross-section column components (square steel pipes) are formed into a circle continuously from hot-rolled coils, the seams are electrically resistance welded to form a circular steel pipe, and then sized from all four sides and formed into a square steel pipe (cold-roll-formed square steel pipes), cold-press-formed square steel pipes, in which thick plates are bent using a press and the seams are welded using submerged arc welding or other methods (hot-roll-formed square steel pipes and hot-press-formed square steel pipes), in which steel is rolled or press-formed while heated, and welded-assembled box cross-section columns, commonly known as four-sided boxes, which are made by welding four steel plates corresponding to each side of a square.However, this analysis model has a cross-sectional shape corresponding to cold-press-formed square steel pipes for architectural structures BCP325.

[0030] The material properties of the hollow section column members (square steel pipe columns) are 490N / mm 2 The material properties of the through diaphragm and backing plate are strength level 490N / mm 2 The numerical analysis was carried out using SN490C rolled steel plate for building structures, and the weld metal was made using the material properties of JIS Z 3312 YGW18. Figure 13 shows the true stress-true strain values ​​actually entered into the analysis based on the material property tensile test results (SS curve). Example: 490N / mm 2 The present invention is aimed at steel materials with a strength level of 490N / mm 2 Not limited to steel materials of 400N / mm 2 class, 520N / mm 2 class, 550N / mm 2 class, 570N / mm 2 class, 590N / mm 2 class, 780N / mm 2 class, 1000N / mm 2 It can be applied to steel materials and weld metals of a wide range of strength levels, including grades 100 and 120. Incidentally, in Figure 13, a) shows the value for the flat part of the column (pillar member), b) shows the value for the corner part of the column, c) shows the value for the through diaphragm and backing plate, and d) shows the value for the weld metal. The standard strength F is 400N / mm 2For grade steel, 215, 235, 295, etc., 490N / mm 2 For grade steel, 295, 325, 345, 365, 400, etc., 520N / mm 2 For grades 325, 335, 355, 385, etc., 550N / mm 2 For grade steel, 385, 570N / mm 2 For grades, 420, 430, 440, 450, 460, etc., 590N / mm 2 For grade steel, 440, 500, 780N / mm 2 For grade steel, 630, 700, etc., 1000N / mm 2 For grade steel, 880 is common. In Ministry of Construction Notification No. 2464 of 2000, the Minister of Land, Infrastructure, Transport and Tourism (MLIT) sets the standard strength F of steel materials according to the type and quality of the steel material, a value used to determine the allowable stress and material strength used in the structural design of steel frames for construction. The standard strength F of JIS-compliant products is determined based on the lower limit of the yield point specified in the JIS standard, but taking into account the influence of the yield ratio of the steel material in steel frames for construction, if 0.7 times the lower limit of the tensile strength is smaller than the lower limit of the yield point, the smaller value is used. On the other hand, for products certified by the Minister of Land, Infrastructure, Transport and Tourism (MLIT), the standard strength F is determined individually after review by the Ministry of Land, Infrastructure, Transport and Tourism.

[0031] A list of analysis parameters is shown in Figure 4. As mentioned above, the analysis parameters for the conventional example and the present invention example are the "opening width," "opening position," "force application direction (direction of horizontal force application)," and "presence or absence of holes in the base material" of the column joint.

[0032] Conventional Examples 1 and 2, in which the column joint is fully welded around the entire circumference of the cross section and no openings are provided, have a column joint located 1000 mm (1 m) away from the through diaphragm (following the description in the first paragraph of paragraph number

[0004] above), and Conventional Example 1 is the one in which the force application direction is 0 degrees (the direction in which the distance to the outermost edge of the cross section of the hollow cross section column is the smallest), while Conventional Example 2 is the one in which the force application direction is 45 degrees (the direction in which the distance to the outermost edge of the cross section of the hollow cross section column is the largest). The analysis parameters according to present inventions 1 to 4 in FIG. 4 will be explained below.

[0033] The present invention 1 has a column joint at a position 1000 mm away from the through diaphragm, and as shown in the center of FIG. 7A, a 30 mm wide opening 1a is provided in a total of four places, one on each of the four side surfaces (below the erection piece 7) of the base material (lower column member 1). Also, as shown on the right side of FIG. 7A, one 30 mm wide opening is provided in each of the approximately central parts of each side of the upper and lower column members 1, 1, for a total of four places. The force application direction is the 0 degree direction. Invention 2 has a column joint located 1000 mm away from the through diaphragm, and as shown in the center of Figure 7B, a 30 mm wide opening 1a is provided in each corner of the base material (lower column member 1), for a total of four. Also, as shown on the right side of Figure 7B, a 30 mm wide opening is provided in each corner of the upper and lower column members 1, 1, for a total of four. The force application direction is 45 degrees. In the present invention 3, a column joint is located 1000 mm away from the through diaphragm, and as shown in the center of FIG. 7C, a 30 mm wide opening 1a is provided in four locations, one on each of the four side surfaces (below the erection piece 7) of the base material (lower column member 1). Also, as shown on the right side of FIG. 7C, no openings are provided, and the entire circumference of the hollow cross section is fully penetrated and welded. The force application direction is 0 degrees. Invention 4 has a column joint located 1000 mm away from the through diaphragm, and as shown in the center of Figure 7D, four 30 mm wide openings 1a are provided, one at each corner of the base material (lower column member 1). Also, as shown on the right side of Figure 7D, no openings are provided, and the entire circumference of the hollow cross section is fully penetrated and welded. The force is applied at a 45-degree angle.

[0034] <Horizontal force application conditions> As described above, in Conventional Examples 1 and 2 and Inventions 1 to 4, numerical analysis was carried out under the condition that horizontal forces were applied to the center of the plate thickness of the through diaphragm at 0 degrees (the direction in which the distance to the outermost edge of the cross section of the hollow cross section is the shortest) and 45 degrees (the direction in which the distance to the outermost edge of the cross section of the hollow cross section is the longest), and the column head on the opposite side was fixed so as not to move horizontally. Incidentally, FIG. 8A is an analytical model diagram showing boundary conditions when the force application direction is at 45 degrees, and FIG. 8B is an analytical model diagram showing boundary conditions when the force application direction is at 0 degrees.

[0035] <Analysis results> Figures 9A to 9D show the relationship between the bending strength M (horizontal force × length from the center of the through diaphragm thickness to the column head on the opposite side) and the deformation angle θ of the hollow cross-section column (horizontal displacement of the center of the through diaphragm thickness / length from the center of the through diaphragm thickness to the column head on the opposite side) for Conventional Examples 1 and 2 and Inventions 1 to 4. Figure 10 also shows the full plastic bending strength for Conventional Examples 1 and 2 and Inventions 1 to 4.

[0036] In the field of architectural steel frames, there are various methods for calculating full-plastic bending strength, but in this analysis, full-plastic bending strength is defined as the intersection of the initial stiffness in the bending strength M-deformation angle θ relationship of the hollow cross-section column and 1 / 3 of the initial stiffness with the tangent to the intersection of the M-θ relationship. 11A and 11B and 12A to 12D show von Mises stress distribution diagrams at the time of full plastic bending yield strength for Conventional Examples 1 and 2 and Inventions 1 to 4. When comparing the relationship between the bending strength M and the deformation angle θ of the hollow cross-section column of Conventional Example 1, in which the horizontal force application direction is 0 degrees, with that of Invention 1 (see Figure 9A), it can be seen that they follow almost the same history, and that the presence or absence of an opening (hole) in the base material (lower column member 1) or an opening in the column joint does not reduce the strength or rigidity. Similarly, when comparing the bending strength M-deformation angle θ relationship of the hollow cross-section column of Conventional Example 2 and Invention 2, in which the horizontal force is applied in a 45-degree direction (see Figure 9B), it is found that they follow almost the same history, and that the presence or absence of an opening (hole) in the base material (lower column member 1) or an opening in the column joint does not reduce the strength or rigidity. Similarly, when comparing the bending strength M-deformation angle θ relationship of the hollow cross-section column of Conventional Example 1 and Invention 3, in which the horizontal force application direction is 0 degrees (see Figure 9C), it is found that they follow almost the same history, and that the presence or absence of an opening (hole) in the base material (lower column member 1) does not reduce the strength or rigidity. Similarly, when comparing the bending strength M-deformation angle θ relationship of the hollow cross-section column of Conventional Example 2, in which the horizontal force application direction is 0 degrees, with that of Invention 4 (see Figure 9D), it is found that they follow almost the same history, and that the presence or absence of an opening (hole) in the base material (lower column member 1) does not reduce the strength or rigidity. In the comparison of full plastic bending strength, as shown in Figure 10, the full plastic bending strength of Invention 1 is 1,000 times that of Conventional Example 1, and it can be seen that the full plastic bending strength does not decrease depending on whether or not there is an opening (hole) in the base material (lower column member 1) or an opening in the column joint. Similarly, the full plastic bending strength of present invention 2 is 0.998 times the full plastic bending strength of conventional example 2, and it can be seen that the full plastic bending strength does not decrease substantially depending on whether or not there is an opening (hole) in the base material (lower column member 1) or whether or not there is an opening in the column joint. Similarly, the full plastic bending strength of present invention 3 is 1,000 times that of conventional example 1, and it can be seen that the full plastic bending strength does not decrease depending on whether or not there is an opening (hole) in the base material (lower column member 1). Similarly, the full plastic bending strength of present invention 4 is 0.997 times that of conventional example 2, and it can be seen that the full plastic bending strength is not reduced substantially by the presence or absence of an opening (hole) in the base material (lower column member 1).

[0037] Therefore, the welding and joining structure and welding and joining method for upper and lower pillar members and the upper and lower pillar members according to the present invention have the following effects. (1) Even if the position of the column joint (the joint portion of the hollow cross-section column member) is weaker than the column connection portion, it can be said that, based on the results of the FEM analysis, a solution has been devised that can easily satisfy the required strength of the connection by providing an opening (hole) 1a on the side of the column member 1. Therefore, it is possible to safely design the position of the column joint to be weaker than the column connection portion, and to change the conventional excessive design to a rational design. Therefore, it is possible to realize a welded joint structure and welding joint construction method for upper and lower column members, as well as upper and lower column members, that are excellent in workability, economy, and rationality. (2) Specifically, based on the aforementioned "the position of the column joint can be designed with a lower strength than the column connection," even if welding work is completed without welding the position corresponding to the erection piece 7 attachment point, the FEM analysis results showed that the structural performance of the entire building can be maintained with almost no degradation. Furthermore, the technical idea of ​​reducing the amount of welding at the column joint (welded joint) and the technical idea of ​​drilling an opening on the side of the lower column member (base material) can be balanced to satisfy the required strength. Therefore, it became clear that omitting the conventional finishing welding work after removing the erection piece 7 would not adversely affect the structural performance of the entire building. Therefore, it was found that welding work can be performed continuously (in one go) without interruption. As a result, the amount of welding can be reduced, welding work can be labor-saving, and work efficiency can be dramatically improved, resulting in a welded joint structure and welding method for upper and lower column members, as well as upper and lower column members, that are extremely easy to construct, economical, and rational.

[0038] Although the embodiments of the present invention have been described above based on the drawings, it should be noted that the present invention is not limited to the illustrated examples and includes the range of design modifications and application variations that are normally made by those skilled in the art, provided that they do not deviate from the technical concept of the present invention. [Explanation of symbols]

[0039] 1 Column member 1a Opening (hole) 2 Welded joints 3 Non-welded areas (openings) 7 Erection Piece 7' Erection piece trace 8 splice plates 9 High-strength bolts 10 Column beam joint 11 Through diaphragm

Claims

1. In a butt welding joint of hollow cross-section column members arranged above and below, A welded joint structure of upper and lower column members, characterized in that the column members are joined with openings provided on their side surfaces so that the total plastic bending strength of the column members is equal to or less than the fracture strength of the welded joint.

2. 2. The welded joint structure of upper and lower pillar members according to claim 1, wherein an opening is provided on a side surface of the lower pillar member.

3. 3. The welded joint structure of upper and lower column members according to claim 2, wherein the lower column member is erected on the upper surface of a column-beam joint or a column base.

4. 2. The welded joint structure of upper and lower pillar members according to claim 1, wherein the upper and lower pillar members are butt-welded, leaving one or more unwelded portions.

5. The welded joint structure of the upper and lower pillar members according to claim 4, wherein the non-welded portion is between the upper and lower pillar members and is at a position corresponding to the attachment portion of the erection piece.

6. 5. A welded joint structure for upper and lower pillar members as described in claim 4, characterized in that the total area of ​​the opening provided on the side surface of the pillar member is set to be equal to or larger than the total area of ​​the non-welded portion.

7. Upper and lower pillar members, characterized in that they are used in the welded joint structure of upper and lower pillar members described in any one of claims 1 to 6.

8. A butt welding joining method for hollow cross-section column members arranged above and below each other and equipped with erection pieces, The method comprises a step of temporarily fixing the upper pillar member by aligning it with the lower pillar member using the erection piece, a step of welding the upper and lower pillar members, and a step of removing the erection piece, In the welding process, in the welding between the upper and lower pillar members, the position corresponding to the attachment portion of the erection piece is left unwelded; A welding method for joining upper and lower pillar members, characterized in that the lower pillar member has an opening on its side that is larger than the entire area of ​​the portion that remains unwelded.

9. 9. The welding method for joining upper and lower column members according to claim 8, wherein the lower column member is erected on the upper surface of a column-beam joint or a column base.

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