JP2023111295A - Welded structure and method of manufacturing welded structure - Google Patents

Abstract

To provide a welded structure which improves fracture resistance of the welded structure by utilizing a backing strip without making execution difficult.SOLUTION: A welded structure includes a first plate-like member which has a first plate face, a second plate face and a first end face containing an inclined face at least partially, a second plate-like member which has a third plate face, a fourth plate face aligned in position with the second plate face and a second end face opposed to the first end face, a backing strip which is arranged so as to be brought into contact with the second plate face and the fourth plate face and faces a gap formed between an intersection of the first end face and the second plate face and an intersection of the second end face and the fourth plate face and welded metal filled into a space surrounded by the first end face, the second end face, and the backing strip, and is fillet-welded on the second plate face on the end part of the first plate-like member side, of both end parts of the first direction.SELECTED DRAWING: Figure 1

Description

The present invention relates to welded structures and methods of manufacturing welded structures.

For example, as described in Patent Document 1, in butt welding, a groove is formed between members to be welded (parts to be welded), and the groove is filled with a weld metal. It is common to make the tensile strength of the weld metal higher than the tensile strength of the part to be joined, but so-called undermatch joints are also known, in which the tensile strength of the weld metal is lower than the tensile strength of the part to be joined. ing. The backing metal is a member that prevents the weld metal from leaking out from the gap in the groove (root gap) in butt welding and prevents welding defects on the first layer side of the weld, filling the groove with the weld metal. It is joined to the part to be joined before joining. However, when welding the upper flange of a beam, for example, at a construction site, it is difficult to weld upward from the bottom of the part to be welded, so access is possible from the top of the part to be welded as shown in Fig. 11. It has been common practice to form a welded portion 95 between the joined portions 91 and 92 and a backing metal 93 at the bottom of the groove.

JP 2013-022599 A

However, when the backing metal is welded to the member at the bottom of the groove as shown in FIG. not joined to Therefore, for example, when welding the upper flange at a construction site, a slit-like gap 93S is formed between the backing metal 93 and the welded portions 91 and 92 because the backing metal is assembled and welded to the inner surface of the groove. be done. Furthermore, the material becomes discontinuous on both sides of the weld fusion line (FL) in the part on the side of the part to be welded where the groove is removed in the welded part. Since the material discontinuity is inclined with respect to the acting force, an in-plane shear force is generated along the discontinuity surface, increasing the strain at the site (see FIG. 12). Furthermore, since the tip of the gap 93S is discontinuous in shape, strain tends to concentrate at that portion. When a crack occurs due to strain concentration at the tip of the slit during an earthquake, the crack propagates near the weld fusion line where the in-plane shear force is high, and may lead to fracture. Also, if there is a location with low toughness near the weld fusion line, there is a risk that the crack generated at the tip of the slit will transform into a brittle crack, leading to early fracture. In addition, when welding at a factory, the assembly welding of the backing metal is performed on the outer surface of the groove, but since the assembly welding is generally performed by intermittent welding, It is easy to cause strain concentration as described above.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a welded structure and a method for manufacturing the welded structure that can improve the fracture resistance of the welded structure by using a backing metal without making the construction difficult. .

[1] A first plate surface facing a first side, a second plate surface facing a second side opposite the first side, and an obtuse angle to the first plate surface a first plate-like member having a first end surface at least partially including an inclined surface inclined to form an acute angle with respect to the second plate surface; and a third plate-like member directed to the first side a plate face, a fourth plate face facing the second side and aligned with the second plate face, and a fourth plate face not inclined with respect to the third and fourth plate faces but in the direction of the plate axis; a second plate-shaped member having a second end face facing the first end face in one direction; The backing metal facing the intersection with the second plate surface and the gap formed between the intersection of the second end surface and the fourth plate surface, the first end surface, the second end surface and the backing The space surrounded by the gold is filled with a weld metal, and the backing metal is fillet-welded to the second plate surface at the end on the first plate-like member side among both ends in the first direction. Welded construction.
[2] In the backing metal, when viewed from the first end face side, the intersection of the first fusion line formed along the first end face and the first plate face is projected onto the second plate face side. The welded structure according to [1], wherein the welded structure is continuously fillet-welded to the second plate surface at or beyond the position.
[3] The welded structure according to [1] or [2], wherein the tensile strength of the weld metal is lower than the tensile strength of at least the first plate member.
[4] The first plate-like member is a flange of an H-beam, a flange of an H-beam or a column skin plate, and the second plate-like member is a diaphragm, a flange of another H-beam, another H-section steel column flange or another column skin plate, the first direction being the material axial direction of the H-section steel beam, the H-section steel column, or the steel pipe column including the column skin plate, [1 ] to [3] any one welded structure.
[5] A method for manufacturing a welded structure according to any one of [1] to [4], comprising: a first step of fillet welding the backing metal to the second plate surface; A method of manufacturing a welded structure, comprising: a second step of placing the end face against the second end face, bringing the backing metal into contact with the fourth plate face, and filling the space with the weld metal.
[6] The method of manufacturing a welded structure according to [5], wherein the first step and the second step are performed at a factory or at a construction site.

According to the above configuration, since the positions of the plate surfaces of the first and second members with which the backing metal contacts are aligned, the backing metal is fillet-welded to the first plate-like member before installation. It is possible to join with , and construction does not become difficult. By fillet-welding the backing metal to the first plate-shaped member and integrating the welded part on the groove side with the backing metal, it is possible to prevent the exposure of the tip of the gap, which can be the starting point of fracture during an earthquake, and prevent the strain concentration part. By transferring to the assembly weld toe, not only can strain concentration be alleviated in the region where the first plate-shaped member and the weld metal are in contact, but crack propagation along the vicinity of the weld fusion line can be avoided, and the welded structure The breaking resistance of can be improved.

It is a sectional view showing welding structure concerning one embodiment of the present invention. It is a figure for demonstrating the analysis conditions of a welded structure. 4 is a graph showing the maximum yield strength in the analysis results of the welded structure; 4 is a graph showing the equivalent plastic strain at position _P3 at the time of maximum proof stress in the analysis results of the welded structure; ₄ is a graph showing the equivalent plastic strain at positions _P1 and P4 at the time of maximum proof stress in the analysis results of the welded structure. 4 is a contour diagram showing distribution of equivalent plastic strain in Analysis Example 1. FIG. 4 is a contour diagram showing distribution of equivalent plastic strain in Analysis Example 2. FIG. FIG. 10 is a contour diagram showing the distribution of equivalent plastic strain in Analysis Example 3; FIG. 11 is a contour diagram showing the distribution of equivalent plastic strain in Analysis Example 4; FIG. 11 is a contour diagram showing distribution of equivalent plastic strain in Analysis Example 5; FIG. 3 is a cross-sectional view showing an example of a conventional welded structure; FIG. 4 is a diagram showing in-plane shear forces occurring along an inclined plane;

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the present specification and drawings, constituent elements having substantially the same functional configuration are denoted by the same reference numerals, thereby omitting redundant description.

FIG. 1 is a cross-sectional view showing a welded structure according to one embodiment of the present invention. In the illustrated example, the welded structure 10 is a butt weld formed between a first plate-like member 11 and a second plate-like member 12 . Here, in this specification, the plate-like member is a member having a shape that is large in length and width relative to the thickness, and the plate surface is a pair of surfaces of the plate-like member including the length direction and the width direction. is the aspect of Further, the end faces are two pairs of faces including the thickness direction among the faces of the plate member. Note that the end surfaces 11E and 12E shown in the example of FIG. 1 are surfaces that include the width direction and the thickness direction of the first plate member 11 and the second plate member 12, respectively. The welded structure 10 is applied to, for example, the following joints.
Between a column and a beam, in which the first plate-like member 11 is a flange or column skin plate of an H-beam, and the second plate-like member 12 is a diaphragm or column skin plate attached to a steel pipe column or H-beam. Joining part-Beam-to-beam joint where the first plate-shaped member 11 is a flange of an H-shaped steel beam and the second plate-shaped member 12 is a flange of another H-shaped steel beam-First plate-shaped member 11 is a column skin plate of a steel pipe column or a flange of an H-section steel column, and the second plate member 12 is a column skin plate of another steel pipe column or a flange of an H-section steel column Example of the above , the flange of the H-shaped steel beam may be an upper flange or a lower flange. Also, the steel pipe column may be formed of a square steel pipe or a welded assembled box-shaped cross-section member. It should be noted that the welded structure 10 is not limited to the above example, and can be widely applied to butt welds that are constructed on site.

The first plate member 11 has a plate surface 111 directed upward, a plate surface 112 directed downward, and an end surface 11E. The end surface 11E is an inclined surface that forms an obtuse angle with respect to the upper plate surface 111 and an acute angle with respect to the lower plate surface 112 . On the other hand, the second plate member 12 has a plate surface 123 directed upward, a plate surface 124 directed downward, and an end surface 12E. The end surface 12E is not inclined with respect to the plate surfaces 123,124. The end surfaces 11E and 12E of the first plate-like member 11 and the second plate-like member 12 face each other in the X direction in the figure. The X direction is the axial direction of the H-shaped steel beam when the first plate member 11 is a flange of the H-shaped steel beam. Since the end surface 11E is an inclined surface as described above, generally a groove (single inclination) is formed between the first plate-like member 11 and the second plate-like member 12 .

Here, the positions of the lower plate surfaces 112 and 124 of the first plate-like member 11 and the second plate-like member 12 (in the Y direction in the drawing, that is, the positions in the height direction) are determined by the backing metal described later. are aligned for contact. On the other hand, the positions of the upper plate surfaces 111 and 123 are aligned in the illustrated example, but they do not necessarily have to be aligned in other examples. That is, the plate thicknesses of the first plate-like member 11 and the second plate-like member 12 do not necessarily have to be the same. Further, the end surface 11E of the first plate-shaped member 11 does not necessarily have to be formed entirely with an inclined surface. A face may be formed.

The backing metal 13 is arranged so as to contact the lower plate surfaces 112 and 124 of the first plate-like member 11 and the second plate-like member 12, respectively. The root gap of the groove formed between the plate member 12 is closed. Specifically, the backing metal 13 is provided between the intersection of the end surface 11E of the first plate member 11 and the plate surface 112 and the intersection of the end surface 12E of the second plate member 12 and the plate surface 124. Facing the crevice that forms. The welded structure 10 is constructed by filling the space surrounded by the grooves, that is, the end surfaces 11E and 12E and the backing metal 13 with the weld metal 14 . By filling the weld metal 14, the first plate-like member 11 and the second plate-like member 12 are each melted, forming a fusion line 11F along the end face 11E and a fusion line 12F along the end face 12E. . It should be noted that the weld metal 14 does not necessarily have to be filled in a single application, and may be filled in the groove by being laminated a plurality of times.

In this embodiment, the backing metal 13 is attached to the plate surface 112 by the fillet weld 15 at the end on the side of the first plate member 11 among both ends in the direction (X direction) in which the base materials face each other. spliced. For example, when beams are welded together or a beam and a column are welded at a construction site, the backing metal 13 is used to assemble the first plate-like member 11 and the second plate-like member 12 using the backing metal 13. It is difficult to perform the fillet welding for joining the surfaces because the fillet welding must be performed in an upward posture.

The fillet weld 15 may be constructed, for example, at a factory that manufactures or processes the H-shaped steel beam including the first plate member 11, or may be constructed at a construction site before erection. In these steps, for example, the fillet weld 15 can be applied while the H-shaped steel beam is turned upside down. Easy. However, in order to suppress deformation of the backing metal due to continuous fillet welding, intermittent fillet welding may be performed in advance in the groove surface.

Furthermore, in the present embodiment, in the cross section of the welded structure 10 as shown in FIG. The contact length _L1 between the plate surface 112 of the first plate member 11 and the backing metal 13 is the intersection point _P1 between the fusion line 11F and the upper plate surface 111 when viewed from the fusion line 11F side. is projected downward, or the fillet weld 15 of the continuous weld is formed at the position P ₂ or beyond the position P ₂ , so that when a crack occurs at the fillet weld toe, the mother Fracture can be induced at the cross section of the material. Further, the leg length _L3 of the fillet welded portion 15 is preferably 4 mm or more in terms of stress transmission and thermal conditions.

By joining the backing metal 13 to the plate surface 112 of the first plate-like member 11 at the fillet weld 15 as described above, the exposure of the tip of the gap, which is a shape discontinuity point, is eliminated, and the backing metal and the cover are eliminated. Since it is possible to prevent separation from the joining material during an earthquake, concentration of strain can be alleviated. Furthermore, by forming the fillet weld 15 at or beyond position _P2 , the strain concentration at _the fillet weld toe can be alleviated more than the strain at the weld toe. Furthermore, plastic deformation of the weld can be suppressed. In addition, by alleviating the plasticization of the base material in the vicinity of the weld joint line, the plastic restraint effect of the low-strength portion can be enhanced. In addition, the longer the length of _L1 , the better, in order to alleviate the strain concentration on the weld root side. However, if _L1 is long, the cross-sectional loss (scallop) of the beam web provided for installing the backing metal when welding the beams together becomes large, and it is possible that the necessary bending strength as a member cannot be sufficiently secured. There is In addition, if _L1 is lengthened, the weight of the backing metal itself becomes too large, and there is a possibility that it may not be possible to carry it by hand when attaching it to a member. Therefore, it is desirable to set the size of the scallop to a size that can ensure the design yield strength, and to suppress the length of _L1 to the size of the scallop or less.

According to the embodiment of the present invention described above, the lower plate surfaces 112 and 124 of the first plate member 11 and the second plate member 12 are aligned, and these plate surfaces 112 and 124 are aligned. Since the backing metal 13 is brought into contact with 124, even if the backing metal 13 is joined to the first plate-like member 11 before erection, positional deviation during erection can be absorbed. Therefore, the fillet weld 15 can be constructed, for example, in a state in which the first plate-like member 11 is turned upside down, and this does not make construction difficult.

In the above embodiment, the backing metal 13 is joined only to the first plate member 11 at the fillet weld 15. A welded portion may be formed near the intersection of 12E and plate surface 124 to join backing metal 13 to both first plate-like member 11 and second plate-like member 12 .

In the embodiment of the present invention, the tensile strength of the parts to be joined (the first plate-shaped member 11 and the second plate-shaped member 12 in the above example) and the tensile strength of the weld metal (the weld metal 14 in the above example) is not particularly limited. In other words, the tensile strength of the weld metal may be higher than the tensile strength of the part to be joined as in a general example, or the tensile strength of the weld metal may be lower than the tensile strength of the part to be joined. It can be a joint. Although undermatched joints have advantages, they also have the disadvantage that strain is concentrated on the welded portion and breakage is likely to occur. In addition, the tensile strength of each to-be-joined part does not need to be the same. Therefore, in the case of the above embodiment, an undermatched joint is defined as a case where the tensile strength of the weld metal 14 is at least lower than the tensile strength of the first plate member 11 .

FIG. 2 is a diagram for explaining analysis conditions for a welded structure. In order to verify the effect of the embodiment of the present invention as described above, structural analysis was performed using a model as shown in FIG. The first plate-shaped member 11 and the second plate-shaped member 12, which are the parts to be joined, both have a plate thickness _t1 of 22 mm and a plate width W of 150 mm, and are made of 780 N/mm grade ² steel (tensile strength of 866 N /mm ² ). For the weld metal 14, the strain relationship equivalent to 590 N/mm ² class was converted into the true stress-true strain relationship (tensile strength 659 N/mm ² ). The end surface of the first plate member 11 forming the groove is formed with an inclined surface with a groove angle of 35°. The size of the root gap between the first plate member 11 and the second plate member 12 is 7 mm. The backing metal 13 has a plate thickness _t2 of 9 mm, a plate width W that is the same as that of the part to be joined, and is made of 490 N/mm class ² steel (tensile strength 594 N/mm ² ). The length L of the backing metal 13, the contact lengths L ₁ and L ₂ with the part to be joined (see FIG. 1), and the joining state are different in Analysis Examples 1 to 5 shown in Table 1, respectively. In each example, the backing metal 13 was joined to the weld metal 14 at the root gap portion, and in addition, the fillet weld 15 (see FIG. 1) was formed in the example where the fillet weld is "Yes" in Table 1. . The fillet weld 15 is formed of YGW11 wire (tensile strength 594 N/mm ² ) defined in JIS Z3312, and has a leg length of 4.5 mm.

The analysis model was a 1/2 model considering symmetry in the Z direction (the width direction of the plate member), and a 16-node structural solid was used as the modeling element. The analysis variables are the backing strip length and installation position of the weld formed by the weld metal 14 . The loading method was monotonic loading in which forced displacement D in the X direction (positive) was applied to the end of the second plate member 12 in the X direction. The X-direction end of the first plate member 11 is restrained from being displaced in each of the X, Y, and Z directions, and the X-direction end of the second plate member 12 is also restrained from being displaced in the Y and Z directions. constrained. Also, the displacement of the plane of symmetry is constrained in the Z direction. The von Mises yield condition was adopted as the yield condition, and the general-purpose finite element analysis software “ANSYS 2021 R1” was used as the solver.

FIG. 3 is a graph showing the maximum yield strength in the analysis results of the welded structure. The vertical axis indicates the maximum proof stress σ _max , and the horizontal axis indicates the contact length _L1 with the joined portion. As shown in the graph, in both Analysis Example 1 and Analysis Example 5, the maximum yield strength σ _max of the welded structure exceeds the tensile strength of the weld metal (659 N/mm ² ), and the tensile strength standard value of the welded part (780 N/mm ² ), but Analysis Examples 2 to 5, in which the backing metal is fillet-welded, have a higher maximum proof stress and are on the safe side in terms of structural performance.

4 and 5 are graphs showing the equivalent plastic strain of the groove inner root portion P ₃ , the weld toe P ₁ and the fillet weld toe P ₄ at the time of the maximum yield strength of the analysis results of the welded structure. The groove inner root portion _P3 and the fillet weld toe _P4 are shown in FIG. In the graphs of FIGS. 4 and 5, the vertical axis indicates the equivalent plastic strain, and the horizontal axis indicates the contact length _L1 with the welded portion. As shown in FIG. 4, in analysis example 2 (No. 2), compared to analysis example 1 (No. 1), fillet welding is performed outside the groove, so that strain in the groove inner root portion _P3 are mitigated. Further, as shown in FIG. 5, in analysis examples 3 and 4, the fillet weld 15 is formed near the position _P2 or beyond the position _P2 compared to the analysis example 2 (No. 2). By doing so, the strain of the fillet weld toe _P4 can be sufficiently relieved from the strain of the weld toe _P1 . Furthermore, plastic deformation of the weld can be suppressed.

6 to 10 are contour diagrams showing the distribution of the equivalent plastic strain at the time of the maximum proof stress of the analysis results of the welded structure. As shown in FIG. 6, in Analysis Example 1, strain concentration is observed in the region where the first plate member and the weld metal are in contact. This is because the in-plane shear force (see Fig. 12) generated on the inclined surface tends to increase the strain at the material discontinuity, and the gap between the backing metal and the plate surface becomes the shape discontinuity point, where the strain is most concentrated. It is for Therefore, as shown in FIG. 7, in Analysis Example 2 in which the backing metal is fillet welded to the plate surface of the first plate member, the backing metal and the plate surface are integrated without any gap. In order to eliminate the exposure of the tip of the gap, which is a shape discontinuity point, and to prevent the backing metal and the material to be joined from separating during an earthquake, the concentration in the above region is alleviated. Furthermore, as shown in FIG. 8, in Analysis Example 3 in which the backing metal extends toward the first plate-shaped member, the strain concentration around the assembly weld is kept away from the strain concentration near the weld joint line, and the weld joint By alleviating the plasticity of the base material near the line, the plastic restraint effect of the low-strength portion can be enhanced, so the strain concentration in the gap between the backing metal and the plate surface is further alleviated. In this analysis example 3, the fillet weld between the backing metal and the first plate member is slightly on the groove side of the opening position of the groove (positions P ₁ and P ₂ shown in FIG. 1). The length _L1 is the position of _P2 , and strain concentration at the fillet weld toe can be alleviated compared to Analysis Example 2. As shown in FIG. 9, in Analysis Example 4 in which the backing metal is stretched toward the first plate-shaped member, the strain distribution inside the first plate-shaped member spreads further, and the first plate-shaped member The concentration of strain in the area where the weld metal and the weld metal are in contact is further relaxed. On the other hand, as shown in FIG. 10, in Analysis Example 5, the length _L1 and the length _L2 are horizontally moved by the same length, but in this case also, the same effect as in Analysis Example 3 can be obtained. It is understood that The in-plane shear force increases with the difference in tensile strength between the weld metal and the base metal. increase markedly.

According to the above analysis results, the backing metal is integrated with the plate surface of the first plate member by fillet welding to eliminate the exposure of the leading edge of the gap, which is a point of discontinuity in shape, and In order to prevent the bonding material from separating during an earthquake, it was shown to be effective in mitigating strain concentration at the tip of the gap 93S shown in FIG. In addition, by extending the backing metal toward the first plate-like member or moving the entire backing metal toward the first member, the strain concentration around the assembly weld is reduced from the strain concentration near the weld joint line. It is shown that the strain concentration at the tip of the gap 93S can be effectively alleviated because the plasticity restraint effect of the undermatched portion can be enhanced by moving away and mitigating the plasticization of the base material in the vicinity of the weld joint line. was done. As a guideline for extending or moving the backing metal, the value of Analysis Example 4 (the fillet weld is formed at position _P2 or a position beyond position _P2 ) may be adopted. However, as shown in Analysis Examples 2 and 3, even if the backing metal is shorter than this, the effect of alleviating strain concentration can be obtained.

Although the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited to these examples. It is obvious that a person skilled in the art of the technical field to which the present invention belongs can conceive of various modifications or modifications within the scope of the technical idea described in the claims. Naturally, it is understood that it belongs to the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 10... Welded structure 11... 1st plate-shaped member 111, 112... Plate surface 11E... End surface 11F... Weld line (FL) 12... 2nd plate-shaped member 123, 124... Plate surface, 12E ... end face, 12F ... weld line (FL), 13 ... backing metal, 14 ... weld metal, 15 ... fillet weld.

Claims (6)

a first plate surface directed to a first side, a second plate surface directed to a second side opposite said first side, and an obtuse angle to said first plate surface; a first plate-like member having a first end surface at least partially including an inclined surface inclined to form an acute angle with respect to the second plate surface;
a third plate surface facing said first side, a fourth plate surface facing said second side and aligned with said second plate surface, and said third and fourth plate surfaces a second plate-shaped member having a second end surface that is not inclined with respect to the plate member and that faces the first end surface in a first direction that is the axial direction of the plate;
arranged to contact the second plate surface and the fourth plate surface, respectively, the intersection of the first end surface and the second plate surface, and the second end surface and the fourth plate a backing metal facing a gap formed between intersections with the surfaces, and a weld metal filling a space surrounded by the first end face, the second end face and the backing metal; A welded structure in which a patch is fillet-welded to the second plate surface at an end portion on the first plate-like member side among both end portions in the first direction. When viewed from the first end face side, the backing metal has a crossing point between a first fusion line formed along the first end face and the first plate face, which is positioned on the second plate face side. 2. The welded structure according to claim 1, wherein the welded structure is continuously fillet welded to said second plate surface at a position projected onto or beyond said position. The welded structure according to claim 1 or 2, wherein the tensile strength of the weld metal is at least lower than the tensile strength of the first plate member. The first plate member is an H-shaped steel beam flange, an H-shaped steel column flange, or a column skin plate,
the second plate member is a diaphragm, another H-beam flange, another H-beam column flange or another column skin plate;
4. The first direction according to any one of claims 1 to 3, wherein the H-section steel beam, the H-section steel column, or the steel pipe column including the column skin plate. Welded construction. A method for manufacturing a welded structure according to any one of claims 1 to 4,
a first step of fillet welding the backing metal to the second plate surface;
and a second step of placing the first end face against the second end face, bringing the backing metal into contact with the fourth plate face, and filling the space with the weld metal. Method. 6. The method of manufacturing a welded structure according to claim 5, wherein said first step and said second step are performed at a factory or at a construction site.

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