JP7670977B2 - Beam joint structure - Google Patents

Description

The present invention relates to a beam joint structure.

For example, at the end of an H-shaped steel beam that is joined to a column, a scallop is formed by cutting out a portion of the web that contacts the flange. By forming the scallop, it is possible to prevent interference between the weld formed on the flange at the end of the H-shaped steel beam and the web. However, during an earthquake, strain is concentrated in the scallop, which is a cross-sectional defect, causing cracks to form, and the progression of the cracks can cause the flange to break.

To address this issue, for example, Patent Document 1 describes a technique for reinforcing the portion of the H-shaped steel beam where the scallop is formed by joining a tapered plate to the outside of the flange. Patent Document 2 describes a technique for reinforcing the scallop by filling it with welding after welding the flange. Patent Document 3 describes a technique in which the opening edge on the flange side of the scallop is formed in a straight line spaced away from the inner surface of the flange, and the groove surface for welding formed on the flange extends beyond the inner surface of the flange to the web side and intersects with the opening edge of the scallop.

JP 2013-7194 A JP 2015-224427 A JP 2020-133218 A

The technology of Patent Document 3 mentioned above makes it possible to prevent strain concentration and fracture at the bottom of the scallop that contacts the flange. However, Patent Document 3 only describes the case where the groove formed at the flange end of the H-shaped cross section beam opens toward the web, a so-called internal groove. For example, in the case of on-site welding, the lower flange side is an internal groove, but on the upper flange side, the groove formed at the flange end opens toward the opposite side from the web, a so-called external groove, so the configuration of the lower flange side described in Patent Document 3 cannot be adopted. Also, for example, in the case of factory welding, an external groove may be formed regardless of the top or bottom of the flange.

The present invention aims to provide a beam connection structure formed between an H-shaped steel beam and a support member that can prevent strain concentration and breakage when a groove that opens toward the opposite side of the web is formed at the end of the flange.

[1] A beam joint structure formed between an H-shaped steel beam and a support member, wherein a groove is formed in at least one flange at an end in the material axis direction of the H-shaped steel beam facing the support member, the groove being open toward the opposite side to the web of the H-shaped steel beam, and a scallop is formed at an end in the material axis direction of the web adjacent to the groove, the opening edge of the scallop is formed away from the at least one flange, a first inclined surface inclined with respect to the at least one flange is formed at an end of a fillet remaining portion between the opening edge of the scallop and the at least one flange, and a backing metal having a flat surface and a second inclined surface formed inclined with respect to the flat surface is arranged so that the flat surface abuts against the at least one flange to close a bottom of the groove and the second inclined surface abuts against the first inclined surface, and a weld metal is filled or layered in the groove.
[2] The opening edge of the scallop includes a curved portion and a straight portion, and the distance in the material axis direction from the boundary between the curved portion and the straight portion to the boundary between the at least one flange and the first inclined surface is 14 mm or more.
[3] A beam joint structure described in [1] or [2], wherein the angle at which the first inclined surface is inclined relative to at least one of the flanges is 60° or less.
[4] A beam joint structure described in any one of [1] to [3], wherein the second inclined surface is formed at least at one of two diagonal corners in the cross section of the backing metal.

The above configuration provides a slope at the intersection between the fillet remaining part and the flange, and also brings this intersection closer to the weld, preventing strain concentration and fracture at the intersection.

1 is a diagram showing an example (first example) of the overall configuration of a beam joining structure according to an embodiment of the present invention; 1 is a diagram showing an example (second example) of the overall configuration of a beam joining structure according to an embodiment of the present invention; 3 is an enlarged view of an upper flange welded portion in the beam joint structure shown in FIGS. 1 and 2 . FIG. 13A and 13B are diagrams showing modified examples of the shape of the backing metal. 4A to 4C are diagrams showing an example of the configuration of a lower flange weld portion. FIG. 4 is a diagram for explaining an example of dimensions of a welded portion in an embodiment of the present invention. FIG. 13 is a diagram showing analysis conditions when the angle θ is 30°. FIG. 7B is a contour diagram showing the distribution of equivalent plastic strain in the case of FIG. 7A. FIG. 7B is a contour diagram showing the distribution of equivalent plastic strain in the case of FIG. 7A. 1 is a graph showing the change in equivalent plastic strain with respect to distance x when the angle θ is 30°. FIG. 13 is a diagram showing analysis conditions when the angle θ is 60°. FIG. 9B is a contour diagram showing the distribution of equivalent plastic strain in the case of FIG. 9A. FIG. 9B is a contour diagram showing the distribution of equivalent plastic strain in the case of FIG. 9A. 1 is a graph showing the change in equivalent plastic strain with respect to distance x when the angle θ is 60°. FIG. 13 is a diagram showing analysis conditions of a comparative example. FIG. 11B is a contour diagram showing the distribution of equivalent plastic strain in the case of FIG. 11A.

A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. Note that in this specification and the drawings, components having substantially the same functional configuration are designated by the same reference numerals to avoid redundant description.

1 and 2 are diagrams showing an example of the overall configuration of a beam joint structure according to an embodiment of the present invention. In the illustrated example, the beam joint structure between the H-shaped steel beam 1 and the support member 2A or the support member 2B is formed by on-site welding. The H-shaped steel beam 1 includes an upper flange 11, a lower flange 12, and a web 13. In the example of FIG. 1, the support member 2A includes a column 21A composed of a square steel pipe or a welded assembled box section column, and through diaphragms 22A, 23A attached to the column 21A. In this case, in the beam welded structure, the upper flange 11 and the lower flange 12 of the H-shaped steel beam 1 are welded to the end faces of the through diaphragms 22A, 23A, respectively. On the other hand, in the example of FIG. 2, the support member 2B includes a column 21B composed of a square steel pipe or a welded assembled box section column, and inner diaphragms 22B, 23B attached to the column 21B. In this case, in the beam joint structure, the upper flange 11 and the lower flange 12 of the H-shaped steel beam 1 are welded to the outer peripheral surface of the square steel pipe that constitutes the side of the column 21B or to the skin plate of the welded assembly box section column.

The configuration of the welded portion between the flange and the support member described below is the same whether the flange of the H-shaped steel beam 1 is welded to the end faces of the through diaphragms 22A, 23A as in the example of Figure 1 or to the side of the column 21B as in the example of Figure 2. In each example, the web 13 of the H-shaped steel beam 1 is joined to the side of the column 21A or 21B, but the method of joining the web 13 is not particularly limited. For example, the web 13 may be welded to these surfaces as in the example shown, or the web 13 may be bolted to a shear plate welded to these surfaces.

3 is an enlarged view of the upper flange weld in the beam joint structure shown in FIG. 1 and FIG. 2. In the illustrated example, at the end of the H-shaped steel beam 1 in the material axis direction facing the support member (not shown), an outer groove, i.e., a groove 111 opening toward the opposite side of the web 13, is formed in the upper flange 11. The bottom of the groove 111 is closed with a backing metal 3, and a weld metal 4 is filled or stacked in the groove 111 to form a weld. At the end of the material axis direction of the web 13 adjacent to the groove 111, a scallop 131, which is a notch for avoiding interference with such a weld, is formed. In the illustrated example, the scallop 131 is a composite circular shape including a small diameter arc portion on the web center side and a large diameter arc portion on the upper flange 11 side, but this example is not limited to this and various scallop shapes can be applied. The opening edge 132 on the upper flange 11 side of the scallop 131 is formed away from the upper flange 11. The portion between the opening edge 132 and the upper flange 11 is also referred to as the fillet remaining portion 133. The formation of the fillet remaining portion 133 makes it easier for the scallop 131 to intersect with the connection portion between the upper flange 11 and the web 13 (the welded portion in a welded assembled H-shaped cross-section beam, the fillet portion in a rolled H-shaped steel). Since shear strain increases at the intersection during an earthquake, it is possible to avoid concentration of strain and breakage at the bottom of the arc portion of the scallop 131 on the upper flange 11 side. The height h of the scallop 131 and the distance d from the opening edge 132 to the upper flange 11 are not particularly limited, but the height h is, for example, 25 mm or more and 40 mm or less from the viewpoint of welding workability and ensuring the strength of the web 13. The distance d is, for example, 2 mm or more and 13 mm or less from the viewpoint of forming the opening edge 132 at the fillet portion formed between the upper flange 11 and the web 13.

In this embodiment, an inclined surface 134 inclined with respect to the upper flange 11 is formed at the end of the fillet remaining portion 133. The backing metal 3 has a flat surface 31 that abuts against the upper flange 11 to close the bottom of the groove 111, and an inclined surface 32 that is formed at an angle with respect to the flat surface 31 and abuts against the inclined surface 134 at the end of the fillet remaining portion 133. The angle at which the inclined surface 32 is inclined with respect to the flat surface 31 corresponds to the angle at which the end of the fillet remaining portion 133 is inclined with respect to the upper flange. In this specification, "abutting" means that at least a part of the two surfaces is in contact, and does not necessarily mean that the entire surfaces are in close contact with each other without any gaps. Also, as shown in FIG. 3, the inclined surface 112 at the end of the upper flange 11 that forms the groove 111, and a part of the flat surface 31 of the backing metal 3 that closes the bottom of the groove 111 are melted into the weld metal 4.

By forming the inclined surface 134 at the end of the fillet uncut portion 133 as described above, a gradient is applied to the intersection P between the fillet uncut portion 133 and the upper flange 11. In addition, by forming the inclined surface 32 on the backing metal 3 at an angle corresponding to the inclined surface 134, the backing metal 3 can be abutted against the upper flange 11 and the inclined surface 134 at both the flat surface 31 and the inclined surface 32, respectively, and the intersection P is moved away from the bottom of the scallop 131 by the amount of the inclined surface 32, and is brought closer to the welded portion, specifically the weld metal 4. Since the bottom of the scallop 131 is prone to plasticization and strain concentration during an earthquake, the concentration of strain at the intersection P is reduced if the intersection P is far from the scallop 131, the flat surface 132 is long, and a large amount of the fillet uncut portion 133 can be secured. In addition, since the weld metal 4 is stronger than the base material, the H-shaped steel beam 1, and is less likely to become plastic during an earthquake, the closer the intersection P is to the weld, the less concentrated the strain at the intersection P. If the intersection P is moved away from the bottom surface of the scallop 131, the concentration of strain can be sufficiently reduced, but if the intersection P is moved closer to the weld than the point Q where the weld toe on the outer surface of the flange is projected onto the inner surface of the flange, the intersection P is moved away from the vicinity of the weld toe on the outer surface of the flange, which becomes plastic during an earthquake, and the concentration of strain can be further reduced. In this way, in this embodiment, the intersection P between the fillet remaining portion 133 and the upper flange 11 is sloped, and the intersection P is moved away from the bottom of the scallop 131, thereby reducing the concentration of strain at the intersection P.

Furthermore, this embodiment is advantageous in that the backing plate 3 can be formed with a single cross section as shown in FIG. 3, so that the backing plate 3 can be easily processed. As a modified example, as shown in FIG. 4, inclined surfaces 32A and 32B may be formed at two diagonal corners in the cross section of the backing plate 3A. The cross section of the backing plate is usually rectangular, and the inclined surfaces are formed by cutting or grinding off the corners of this rectangle. The backing plate 3A having the two inclined surfaces 32A and 32B is also easy to process because it has a single cross section. In addition, when forming a beam joint structure by on-site welding, the backing plate 3A is easy to work because the inclined surface 32A or the inclined surface 32B can be abutted against the inclined surface 134 at the end of the fillet remaining portion 133 regardless of whether the front or back surface is used.

The backing metal 3 can also be used in the welded portion on the lower flange 12 side as shown in the example of FIG. 5. In the example of FIG. 5, a scallop 135 is formed on the web 13 on the lower flange 12 side as well as on the upper flange 11 side, and a fillet uncut portion 137 is formed between the opening edge 136 of the scallop 135 and the lower flange 12. An inner groove, that is, a groove 121 opened toward the web 13 side is formed by the end of the fillet uncut portion 137 and the inclined surfaces 138, 122 of the end of the lower flange 12, and the bottom of the groove 121 is closed with the flat surface 31 of the backing metal 3, and the weld metal 4 is filled or stacked in the groove 121 to form a welded portion. In this case, even if the inclined surface 32 is formed on the backing metal 3, there is no problem in abutting the flat surface 31 against the lower flange 12. Although not shown, the same applies when the backing metal 3A shown in FIG. 4 is used.

The configuration of the welded portion of the internal groove as shown in the example of FIG. 5 can be, for example, the configuration described in JP 2020-133218 A, and various known groove shapes and welding methods can be applied without being limited to this example. In another embodiment, for example, when the beam joint is formed by factory welding, an external groove is also formed on the lower flange 12 side, that is, a groove that opens toward the opposite side to the web 13. In this case, a weld similar to the example described above with reference to FIG. 3 may also be formed on the lower flange 12 side.

Figure 6 is a diagram for explaining an example of the dimensions of the welded portion in an embodiment of the present invention. Note that FIG. 6 illustrates a backing metal 3 similar to that in FIG. 3, but the same applies when the backing metal 3A illustrated in FIG. 4 is used. In addition, some reference numerals are omitted in FIG. 6 for the sake of explanation. In the illustrated example, the opening edge of the scallop 131 includes a curved portion including the above-mentioned compound circle and a straight portion, and the boundary between the curved portion and the straight portion is illustrated as point A, and the boundary between the straight portion and the inclined surface 134 is illustrated as point B. Furthermore, the contact point between the inclined surface 134 and the upper flange 11 (intersection P illustrated in FIG. 3) is illustrated as point C. In order to more effectively reduce the concentration of strain at the intersection (point C) between the fillet remaining portion 133 and the upper flange 11, it is desirable to increase the distance x between points A and C, and further to reduce the angle θ (0<θ<90°) at which the inclined surface 134 is inclined relative to the upper flange 11.

Specifically, assuming a typical size of H-shaped steel beam, it is desirable that the angle θ is 60° or less, and the distance x is 14 mm or more. In this specification, the distance x is the distance between points A and C in the axial direction of the H-shaped steel beam 1. However, as shown in the analysis results described later, even if either the angle θ or the distance x is outside the above range, the concentration of strain at point C can be reduced by adjusting the other, so the angle θ and the distance x do not necessarily have to be within the above range.

Hereinafter, with reference to FIG. 7A to FIG. 11B, the results of the analysis for verifying the effect of the embodiment of the present invention will be described. Common to the analysis models of each example, the cross section of the H-shaped section beam has a height (distance from the upper surface of the upper flange to the lower surface of the lower flange) of 700 mm, a flange width of 200 mm, a web plate thickness of 12 mm, and a flange plate thickness of 19 mm. The model is a 1/2 model considering symmetry, and is a cantilever type in which only one end of the H-shaped steel beam is supported at the fixed end. The length of the cantilever beam is 3500 mm, and a monotonic load is applied in one direction to the beam end opposite the fixed end. A 20-node structural solid is used as the modeling element. The stress-strain relationship was obtained by converting the tensile test results of the material used in the past experiment into a true stress-true strain relationship and approximating it to a multi-linear relationship. The von Mises yield condition was adopted as the yield condition, and the solver was the general-purpose nonlinear structural analysis program "ANSYS 2021 R1". The yield point was 367 N/ ^mm2 for the flange and web, the full plastic moment of the beam was 1705 kNm, and the rotation angle of the beam end during full plastic bending moment was 0.00765 rad. The equivalent plastic strains shown below are all values at the time when the displacement of the beam end is 3.0 _{δ P} (δ _P is the deformation amount during full plastic moment of the beam). Also, the backing metal is not shown in the contour diagram.

7A to 7C and 8 are diagrams showing analysis conditions and results when the angle θ is 30°. As shown in FIG. 7A, the angle θ at which the fillet remaining part is inclined with respect to the upper flange is set to 30°, and the distance x from the boundary between the curved part and the straight part of the scallop opening edge to the inclined surface is changed. The contour diagrams of FIG. 7B and FIG. 7C show the distribution of equivalent plastic strain when x=14.3 mm and when x=17.3 mm, respectively. In both cases, it can be seen that the concentration of strain at the intersection (point C) between the fillet remaining part and the upper flange is reduced. The graph of FIG. 8 shows the change in the equivalent plastic strain ε _eq of point C and the node with the highest strain among the nodes at the scallop bottom with respect to the distance x. When θ=30°, if the distance x is 14 mm or more, the strain at point C is lower than the strain level at the scallop bottom, and it can be said that the concentration of strain is sufficiently reduced.

Figures 9A to 9C and 10 show the analysis conditions and results when the angle θ is 60°, as described above. As shown in Figure 9A, the angle θ is set to 60° and the distance x is changed. The contour diagrams in Figures 9B and 9C show the distribution of equivalent plastic strain when x = 11.3 mm and when x = 17.3 mm, respectively. In both cases, it can be seen that the concentration of strain at point C is reduced. As shown in the graph in Figure 10, when θ = 60°, if the distance x is 12 mm or more, the strain at point C falls below the strain level at the bottom of the scallop, and it can be said that the concentration of strain is sufficiently reduced.

Figures 11A and 11B show the analysis conditions and results for a comparative example in which no inclined surface was formed at the end of the fillet remaining part. As shown in Figure 11A, no inclined surface was formed, and the fillet remaining part was cut off perpendicular to the upper flange at a position 9.5 mm from the boundary between the curved part and the straight part of the scallop opening edge, and the backing metal had a normal rectangular cross section. From the distribution of equivalent plastic strain shown in the contour diagram of Figure 11B, it can be seen that strain is concentrated at the intersection (point C) between the fillet remaining part and the upper flange.

From the results of the above analysis, it was found that forming an inclined surface at the end of the fillet remaining part and appropriately setting the distance x is effective in reducing the concentration of strain at the intersection between the fillet remaining part and the upper flange. If the angle θ is made larger, as in the case of θ = 60°, a flat surface can be ensured even if the distance x is relatively short, and the concentration of strain is effectively reduced. Also, even if the flat surface is relatively small, as in the case of θ = 30°, the concentration of strain can be effectively reduced by increasing the distance x. Whether to increase the angle θ or increase the distance x can be appropriately selected depending on, for example, the size of the backing metal.

The above describes in detail preferred embodiments of the present invention with reference to the attached drawings, but the present invention is not limited to these examples. It is clear that a person skilled in the art of the technical field to which the present invention pertains can conceive of various modified or revised examples within the scope of the technical ideas described in the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

1... H-shaped steel beam, 11... upper flange, 12... lower flange, 13... web, 2A, 2B... support member, 21A... square steel pipe column, 21B... assembled welded box section column, 22A, 23A... through diaphragm, 22B, 23B... inner diaphragm, 3, 3A... backing metal, 4... weld metal, 31... flat surface, 32, 32A, 32B... inclined surface, 111, 121... groove, 112, 122... inclined surface, 131, 135... scallop, 132, 136... opening edge, 133, 137... fillet remaining portion, 134, 138... inclined surface.

Claims (4)

A beam connection structure formed between an H-shaped steel beam and a support member,
At the end of the H-shaped steel beam in the material axis direction facing the support member, at least one flange is formed with a groove that opens toward the opposite side to the web of the H-shaped steel beam,
A scallop is formed at an end of the web in the material axis direction adjacent to the groove, and an opening edge of the scallop is formed away from the at least one flange,
a first inclined surface inclined with respect to the at least one flange is formed at an end of a fillet remaining portion between an opening edge of the scallop and the at least one flange;
A backing metal having a flat surface and a second inclined surface formed at an angle with respect to the flat surface is arranged so that the flat surface abuts against the at least one flange to close the bottom of the groove, and the second inclined surface abuts against the first inclined surface;
A beam joint structure in which the groove is filled or layered with weld metal. The opening edge of the scallop includes a curved portion and a straight portion,
2. The beam joint structure according to claim 1, wherein the distance in the material axis direction from the boundary between the curved portion and the straight portion to the boundary between the at least one flange and the first inclined surface is 14 mm or more. The beam joint structure according to claim 1 or 2, wherein the angle at which the first inclined surface is inclined relative to at least one of the flanges is 60° or less. The beam joint structure according to any one of claims 1 to 3, wherein the second inclined surface is formed on at least one of two diagonal corners in the cross section of the backing metal.

Images