Beam end joint structure, beam end joint structure construction method and end tab
The beam-end joint structure integrates steel end tabs with partial-penetration welds to the beam flanges, addressing premature fracture issues by forming a unified structure that withstands repeated loads without requiring post-weld removal of end tabs, thus enhancing structural integrity.
Patent Information
- Application Number
- JP2024048565
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-03-25
- Publication Date
- 2025-10-07
AI Technical Summary
Existing beam-end joint structures with H-shaped beams are prone to premature fracture at the welds connecting the beam flanges to supporting members due to repeated loads, particularly at the slit bottom where end tabs are placed, necessitating additional effort to remove these tabs post-welding to prevent fracture.
A beam-end joint structure where steel end tabs are welded directly to the beam flanges, forming partial-penetration welds on the upper surfaces, and weld metal is filled into grooves on the end tabs and supporting members, ensuring the end tabs and flanges behave as a single unit, suppressing strain concentration and preventing premature fracture.
The configuration effectively prevents premature fracture by integrating the end tabs with the beam flanges, reducing the need for post-weld removal and simplifying the construction process while enhancing structural integrity under repeated loads.
Smart Images
Figure 2025148007000001_ABST
Abstract
Description
[Technical Field]
[0001] The present invention relates to a beam-end joint structure, a construction method for a beam-end joint structure, and an end tab. [Background technology]
[0002] In beam-end joint structures where H-shaped beams are connected to supporting members, there is a concern that fractures and damage may occur when the beam members are subjected to repeated loads due to earthquake motions and other factors. In such cases, the fracture origin is often the weld that connects the beam flange to supporting members such as diaphragms and column skin plates. If a weld defect exists within the beam flange width at this weld, the defect can initiate premature fracture. Because weld defects such as crater cracks are particularly likely to occur at the start and end of the weld, as described in Non-Patent Document 1, for example, steel end tabs with grooved edges are placed on both sides of the beam flange width at the beam end, and the weld groove between the beam flange and supporting member is extended to form the start and end of the weld outside the beam flange width. However, because the tip of the gap (the bottom of the slit) between the end tab and the beam flange can be the origin of premature fracture, it is recommended to remove the end tabs by gas cutting and grinding after welding the beam flange to the supporting member. [Prior art documents] [Non-patent literature]
[0003] [Non-Patent Document 1] Architectural Institute of Japan, "Steel Construction Technical Guidelines: Construction Site Execution Edition", 7th Edition, January 2018 Summary of the Invention [Problem to be solved by the invention]
[0004] However, there is no structural problem if the end tab portion remains in the beam end joint structure, and therefore, if the problem of early breakage of the slit bottom as described above is resolved, the extra effort required to remove the end tab portion can be reduced and the process can be simplified.
[0005] Therefore, the present invention aims to provide a beam end joint structure that does not undergo premature fracture even if the end tab portion is left in place after welding the beam flange and support member, a construction method for the beam end joint structure, and an end tab. [Means for solving the problem]
[0006] [1] A beam end joining structure for joining an H-shaped beam having a first flange, a second flange, and a web to a support member facing the end of the H-shaped beam in the material axis direction, comprising a first steel end tab arranged adjacent to at least the widthwise end of the first flange, wherein weld metal is filled between the entire groove formed at the end of the first flange in the material axis direction and the support member, and at least a portion of the groove formed in the first end tab and the support member to form a first weld, and weld metal is filled between the first flange and a second groove formed on the side of the first end tab that abuts against the first flange, to form a second weld. [2] The beam end joint structure described in [1], wherein the second weld is a partial penetration weld formed only on the upper surface side of the first end tab and the first flange. [3] A beam end joint structure as described in [1], wherein the first groove surface and the second groove surface do not intersect, and the second welded portion is spaced apart from the first welded portion. [4] A beam end joint structure according to [1], wherein in the first welded portion, weld metal is filled only in a portion between the first groove surface and the support member. [5] The beam end joint structure described in [1] further includes a second steel end tab arranged adjacent to the widthwise end of the second flange, wherein a third weld is formed by filling weld metal into the entire area between the groove formed at the end of the second flange in the material axis direction and the support member, and at least a portion between a third groove formed on the second end tab and the support member, and a fourth weld is formed by filling weld metal between the second flange and a fourth groove formed on the side of the second end tab that abuts against the second flange. [6] A construction method for a beam-end joint structure described in any one of [1] to [5], comprising the steps of: abutting a backing metal that forms the bottom of the groove where the first weld is formed against the underside of the first flange and the support member and assembling and welding them; abutting a side of the first end tab against the end of the first flange in the width direction, abutting a part of the underside of the first end tab against the backing metal, and filling weld metal between the second groove surface and the first flange to form the second weld; and filling weld metal into the groove to form the first weld. [7] A construction method for a beam-end joint structure described in [6], in which the step of forming the second weld is carried out after the step of forming the first weld or during the step of forming the first weld. [8] A steel end tab arranged adjacent to the widthwise end of a flange of an H-shaped cross-section beam in a beam-end joint structure, the end tab having upper and lower surfaces, a first side abutting the flange, a second side opposite the first side, and front and rear surfaces facing the material axis direction of the H-shaped cross-section beam, wherein a first groove surface is formed on the front surface such that the angle of the groove surface formed at the end of the flange in the material axis direction is aligned, and a second groove surface is formed between the upper surface and the first side surface, leaving the underside of the first side surface. [9] The end tab according to [8], wherein the second groove surface does not intersect with the first groove surface. [Effects of the Invention]
[0007] According to the above configuration, a weld is formed between the groove surface formed on the side of the end tab and the beam flange, so that even when the beam member is subjected to repeated loads due to earthquake motion or the like, the end tab and the beam flange behave as a single unit, effectively suppressing strain concentration at the bottom of the slit and preventing premature fracture. [Brief explanation of the drawings]
[0008] [Figure 1] 1 is a diagram showing an example of a beam-end joining structure according to a first embodiment of the present invention. [Figure 2] 1 is a diagram showing an example of a beam-end joining structure according to a first embodiment of the present invention. [Figure 3] 1 is a diagram showing an example of a beam-end joining structure according to a first embodiment of the present invention. [Figure 4] FIG. 10 is a diagram showing an example of a beam-end joining structure according to a second embodiment of the present invention. [Figure 5] 3A to 3C are diagrams showing examples of end tabs used in the first embodiment of the present invention. [Figure 6] 10A and 10B are diagrams showing examples of end tabs used in the second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION
[0009] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this specification and drawings, components having substantially the same functional configurations are designated by the same reference numerals, and redundant explanations will be omitted.
[0010] 1 to 3 are diagrams showing an example of a beam-end joint structure according to a first embodiment of the present invention. Each diagram shows the beam's material axis direction (X direction), beam width direction (Y direction), and beam depth direction (Z direction). 1 to 3 are arrow views taken along lines II, II-II, and III-III shown in each diagram. The beam-end joint structure 1 shown in these diagrams will be described below.
[0011] The beam-end joint structure 1 joins an H-shaped beam 2 to a support member facing the end of the beam in the axial direction. In the illustrated example, the support member includes a column 3 made of a rectangular steel pipe or the like and diaphragms 31 and 32. The diaphragms 31 and 32 are inserted in the middle of the column 3 and welded to it. The ends of the upper flange 21 and the lower flange 22 of the H-shaped beam 2 in the axial direction are joined to the diaphragms 31 and 32 by welds 41 and 42, respectively. Meanwhile, the end of the web 23 in the axial direction is joined to the side surface 33 of the column 3 by a weld 43. The splice plate 34 is used to position the H-shaped beam during construction and as a backing plate for the weld 43. Alternatively, the web 23 may not be directly welded to the side surface 33 of the column 3, but the splice plate 34 may be welded to the column 3 and then bolted to the web 23. In another example, the diaphragm may have an internal diaphragm structure in which it is attached to the inside of the column 3, and both the upper flange 21 and the lower flange 22 may be joined to the side surface 33 of the column 3 via welds.
[0012] At the end of the upper flange 21 in the material axis direction, a groove surface is formed between the upper flange 21 and the diaphragm 31 to form a groove 211 into which the weld metal of the welded portion 41 will be filled. Furthermore, steel end tabs 61 are arranged adjacent to both widthwise ends of the upper flange 21, and groove surfaces are also formed on the end tabs 61 that are angled to the groove surfaces of the end of the upper flange 21. The backing metal 51 arranged at the bottom of the groove 211 has a length corresponding to the combined width of the upper flange 21 and the end tabs 61 on both sides. This allows the groove 211 to extend beyond the widthwise ends of the upper flange 21. Note that the end tabs 61 are not structurally important, so it is not necessary to weld the entire width to the diaphragm 31. Therefore, the weld metal of the welded portion 41 only needs to fill the entire gap between the groove surface of the upper flange 21 and the diaphragm 31, and at least a portion of the gap between the groove surface (first groove surface) formed on the end tabs 61 and the diaphragm 31. For example, as shown in FIG. 1, by filling the weld metal only in a portion between the groove surface of the end tab 61 and the diaphragm 31 and not filling the weld metal up to the end of the end tab 61 opposite the upper flange 21, a member for preventing leakage of the weld metal at the end of the groove 221 is not required.
[0013] Similarly, a groove surface is formed at the end of the lower flange 22 in the material axis direction to form a groove 221 between the diaphragm 32 and the end of the lower flange 22, through which weld metal is filled into the weld zone 42. Steel end tabs 62 are arranged adjacent to both widthwise ends of the lower flange 22, and groove surfaces are also formed on the end tabs 62 that are angled to match the groove surfaces at the ends of the lower flange 22. The backing metal 52 arranged at the bottom of the groove 221 has a length corresponding to the combined width of the lower flange 22 and the end tabs 62 on both sides, and the groove 221 extends beyond the widthwise ends of the lower flange 22. The weld metal of the weld zone 42 is filled entirely between the groove surface of the lower flange 22 and the diaphragm 32, and at least partially between the groove surface (first groove surface) formed on the end tabs 62 and the diaphragm 32. In the above explanation, similar end tabs 61, 62 are arranged on both the upper flange 21 side and the lower flange 22 side to form welds 41, 42, but it is also possible to adopt the above-mentioned end tab and weld configuration on only one of the upper flange 21 side and the lower flange 22 side, and form a weld on the other side using, for example, another known method.
[0014] Furthermore, in this embodiment, welds are also formed between the end tabs and the beam flanges. As shown in Fig. 3, weld metal is filled between the upper flange 21 and a groove surface (second groove surface) formed on the side surface of the end tab 61 that abuts against the upper flange 21, forming weld 44. Weld metal is also filled between the lower flange 22 and a groove surface (second groove surface) formed on the side surface of the end tab 62 that abuts against the lower flange 22, forming weld 45. Conventional end tabs are fixed by assembly welding to backing metals (backing metals 51 and 52 in this embodiment) that are placed at the bottom of the grooves formed together with the beam flanges. However, in this embodiment, the end tabs 61 and 62 are welded directly to the upper flange 21 and the lower flange 22 by welds 44 and 45.
[0015] By welding the end tabs directly to the beam flanges in this way, the end tabs 61, 62 and the upper and lower flanges 21, 22 behave as a single unit, effectively suppressing strain concentration at the bottom of the slit and preventing premature fracture, even when the H-section beam 2 is subjected to repeated loads due to earthquake motion or other factors. While cracks may originate at the weld start and end points on the opposite side of the welds 41, 42 in the welds 44, 45, cracks initiated from these points propagate toward the base material of the beam flange, which has good toughness, making premature fracture unlikely. Furthermore, by welding the end tabs directly to the beam flanges, assembly welding to secure the end tabs to the backing strips is unnecessary. The assembly welding within the grooves 211, 221 is limited to attaching the backing strips 51, 52 to the upper and lower flanges 21, 22, respectively. This minimizes the impact of weld metal from the assembly welding being mixed into the weld metal from the main welds 41, 42.
[0016] Unlike known beam flange widening components at beam ends, end tabs 61, 62 are not structurally significant components. Therefore, they do not need to be welded to diaphragms 31, 32 across their entire width. Furthermore, welds 44, 45 between upper flange 21 and lower flange 22 may be partial-penetration welds rather than full-penetration welds. Specifically, as shown in FIG. 3 , weld 44 may be a partial-penetration weld formed only on the upper surfaces of end tab 61 and upper flange 21, and weld 45 may be a partial-penetration weld formed only on the upper surfaces of end tab 62 and lower flange 22. In this case, unlike K-groove welds that also form grooves on the undersides of the end tabs and beam flanges, or full-penetration welds that place backing metal at the bottom of the grooves, the end tabs can be installed only from the upper surfaces of the beam flanges, simplifying on-site installation.
[0017] As a first example, the beam-end joint structure 1 according to the first embodiment described above can be constructed by the following steps. After the support members, i.e., the column 3, the diaphragms 31 and 32, and the H-section beam 2, are positioned in their predetermined positions, the backing metals 51 and 52 are abutted against the upper flange 21 and the diaphragm 31 and the lower flange 22 and the diaphragm 32, respectively, and assembly welding is performed. Next, the sides of the end tabs 61 and 62 are abutted against the widthwise ends of the upper flange 21 and the lower flange 22, respectively, and portions of their lower surfaces are abutted against the backing metals 51 and 52, and then the welds 44 and 45 are formed. Next, the weld start and end ends of the welds 44 and 45 that protrude toward the grooves 211 and 221 are machined with a grinder or the like to align them with the groove surfaces, and the grooves 211 and 221 are filled with weld metal to form the welds 41 and 42. The process of joining the web 23 of the H-section beam 2 to the side of the column 3 with the weld 43 can be carried out before, after, or at any time during the above process.
[0018] As a second example, construction can be performed using the following steps. After the support members, the column 3, diaphragms 31 and 32, and H-section beam 2, are positioned in their predetermined positions, the backing metals 51 and 52 are abutted against the upper flange 21 and diaphragm 31 and the lower flange 22 and diaphragm 32, respectively, and assembly welding is performed. Next, the sides of the end tabs 61 and 62 are abutted against the widthwise ends of the upper flange 21 and the lower flange 22, respectively, and a portion of their lower surfaces is abutted against the backing metals 51 and 52, and then assembly welding is performed to the backing metals 51 and 52. Next, the grooves 211 and 221 are welded, and the welding is stopped once before the pass that reaches the groove faces of the end tabs 61 and 62, forming welds 44 and 45. Next, the start and end welding portions of welds 44, 45 that protrude toward grooves 211, 221 are processed with a grinder or the like to align them with the groove surface, and then welding of grooves 211, 221 is resumed to form welds 41, 42. In any of the above examples, if the shape of the start and end welding portions of welds 44, 45 does not pose a problem in forming welds 41, 42, there is no need to perform surface processing with a grinder or the like after welds 44, 45 are formed.
[0019] FIG. 4 is a diagram illustrating an example of a beam-end joint structure according to a second embodiment of the present invention. This embodiment differs from the first embodiment in that, as described below, the two grooves formed in the end tab do not intersect, and the weld (second weld) between the end tab and the beam flange is spaced apart from the weld (first weld) between the beam flange and the end tab and the support member. In the illustrated example, the weld 45A between the end tab 62 and the lower flange 22 is spaced apart from the weld 42 between the lower flange 22 and the end tab 62 and the diaphragm 32. In this case, in the construction process described above as the second example, it is also possible to form the weld 45A after welding all of the groove 221 to form the weld 42. Similarly, the weld between the end tab 61 and the upper flange 21 may be spaced apart from the weld 41 between the upper flange 21 and the end tab 61 and the diaphragm 31. The remaining configuration is similar to that of the first embodiment, and therefore a detailed description thereof will be omitted.
[0020] According to the second embodiment described above, taking the bottom flange 22 side as an example, because weld 45A is separated from weld 42, the weld start and end portions of weld 45A do not protrude into groove 221 when weld 45A is formed, eliminating the need for a process using a grinder or the like to align the weld start and end portions that protrude into groove 221 with the groove surface. Furthermore, because weld 45A is present, when subjected to repeated loads, end tab 62 and bottom flange 22 behave as a single unit, effectively suppressing strain concentration at the slit bottom, while the slit remaining between weld 45A and weld 42 means that if a crack starts at the weld start and end portions of weld 42, the crack is guided into the slit, temporarily suppressing its propagation.
[0021] The configuration of the end tabs used in the above-described embodiment of the present invention will be further described below. Each figure shows the beam axis direction (X direction), beam width direction (Y direction), and beam depth direction (Z direction) when end tabs 6A and 6B are arranged in beam-end joint structure 1 as end tabs 61 and 62 described above.
[0022] FIG. 5 illustrates an example of an end tab used in the first embodiment of the present invention. The end tab 6A has an upper surface 601 and a lower surface 602 that face the beam depth direction when placed in the beam-end joint structure 1, a first side surface 603 that abuts the beam flange, a second side surface 604 on the opposite side, and front and rear surfaces 605 that face the beam axis direction when placed in the beam-end joint structure 1. The front surface has a first groove surface 606 that is angled to the groove surface formed at the end of the beam flange in the material axis direction. A second groove surface 607A is formed between the upper surface 601 and the first side surface 603, leaving the lower surface 602 side of the first side surface 603 untouched. In the end tab 6A, the second groove surface 607A is formed over the entire length of the corner between the upper surface 601 and the first side surface 603, and the first groove surface 606 and the second groove surface 607A intersect. Depending on which side of the beam flange the end tab 6A is disposed, the position of the second groove surface 607A is reversed in the left-right direction.
[0023] FIG. 6 illustrates an example of an end tab used in the second embodiment of the present invention. The end tab 6B has an upper surface 601, a lower surface 602, a first side surface 603, a second side surface 604, a rear surface 605, and a first groove surface 606, similar to the example in FIG. 5 above. Meanwhile, in the end tab 6B, the second groove surface 607B is formed only at a portion of the corner between the upper surface 601 and the first side surface 603, and the first groove surface 606 and the second groove surface 607B do not intersect. Note that the position of the second groove surface 607B is reversed left and right depending on which side of the beam flange the end tab 6B is positioned on. In the second embodiment, for example, by using the end tab 6B as the end tabs 61 and 62, the weld between the end tab and the beam flange can be separated from the weld between the beam flange and the end tab and the support member. Since no missing portion is formed in the first groove surface 606 due to the intersection with the second groove surface 607B, the first groove surface 606 can be aligned with the groove surface of the beam flange to form a groove surface without any gaps. [Explanation of symbols]
[0024] 1...beam end joint structure, 2...H-shaped cross section beam, 21...upper flange, 22...lower flange, 23...web, 211, 221...groove, 3...column, 31...diaphragm, 32...diaphragm, 33...side, 34...splice plate, 41, 42, 43, 44, 45, 45A...weld, 51, 52...backing plate, 61, 62, 6A, 6B...end tab, 601...upper surface, 602...lower surface, 603...first side, 604...second side, 605...rear surface, 606...first groove surface, 607A, 607B...second groove surface.
Claims
1. A beam end joining structure in which an H-shaped cross section beam having a first flange, a second flange, and a web is joined to a support member facing an end of the H-shaped cross section beam in a material axis direction, a first steel end tab disposed adjacent at least a widthwise end of the first flange; a weld metal is filled into an entire area between a groove surface formed at an end of the first flange in the material axis direction and the support member, and into at least a portion between a first groove surface formed at the first end tab and the support member, to form a first weld; a second welded portion formed between the first flange and a second groove formed on a side surface of the first end tab that abuts against the first flange, by filling weld metal between the first flange and the second groove surface.
2. 2. The beam-end joint structure according to claim 1, wherein the second weld is a partial penetration weld formed only on the upper surface sides of the first end tab and the first flange.
3. The beam-end joint structure according to claim 1 , wherein the first groove surface and the second groove surface do not intersect, and the second welded portion is spaced apart from the first welded portion.
4. The beam-end joint structure according to claim 1 , wherein the first welded portion is filled with weld metal only in a portion between the first groove surface and the support member.
5. a second steel end tab located adjacent a widthwise end of the second flange; a weld metal is filled into an entire area between a groove surface formed at an end of the second flange in the material axis direction and the support member, and into at least a portion between a third groove surface formed in the second end tab and the support member, to form a third weld; 2. The beam end joint structure according to claim 1, wherein a fourth weld is formed by filling a weld metal between a fourth groove formed on a side surface of the second end tab that abuts against the second flange and the second flange.
6. A construction method for the beam-end joint structure according to any one of claims 1 to 5, a step of assembling and welding a backing metal that forms a bottom of the groove where the first weld portion is to be formed, by abutting the backing metal against a lower surface of the first flange and the support member; a step of abutting a side surface of the first end tab against an end portion of the first flange in the width direction, abutting a portion of a lower surface of the first end tab against the backing metal, and filling a weld metal between the second groove surface and the first flange to form the second weld; filling the groove with weld metal to form the first weld; A construction method for beam-end joint structures, including:
7. 7. A method for constructing a beam-end joint structure as described in claim 6, wherein the step of forming the second weld is performed after the step of forming the first weld or during the step of forming the first weld.
8. A steel end tab disposed adjacent to the widthwise end of a flange of an H-section beam in a beam end joint structure, The beam has an upper surface and a lower surface, a first side surface that abuts against the flange, a second side surface opposite to the first side surface, and a front surface and a rear surface that face in the material axis direction of the H-shaped cross section beam, A first groove surface is formed on the front surface, the angle of which is aligned with the groove surface formed at the end of the flange in the material axis direction, An end tab, wherein a second groove surface is formed between the upper surface and the first side surface, leaving a lower surface side of the first side surface.
9. The end tab of claim 8 , wherein the second groove face does not intersect with the first groove face.