JP2022098141A - Beam joint structure and performance improving method therefor - Google Patents

Abstract

To provide a beam joint structure having a scallop, suppressed in early occurrence of cracks to the beam.SOLUTION: In a joint structure 100 of a steel beam 20 jointed to a steel column 10, the beam 20 is formed of an H-shaped steel, joined to the column 10 with the strong axis direction set along the vertical direction. A web part 23 of the beam 20 has a lower side scallop 25a cut out from an end face facing the column 10 toward a lower flange 21, and a thin part 26 with the thickness reduced from the lower side scallop 25a over a prescribed range.SELECTED DRAWING: Figure 2

Description

The present invention relates to a joining structure of a steel beam joined to a steel column and a method for improving the performance of the joining structure.

Patent Document 1 discloses a configuration in which a scallop is provided on a web portion of an H-shaped steel beam joined to a steel column.

Japanese Unexamined Patent Publication No. 2004-68385

Like the beam joining structure described in Patent Document 1, in order to continuously weld the flange portion of the beam to the steel column, the web portion of the beam is a substantially quarter circle cut out toward the flange portion. Shaped scallops are commonly provided. In such a configuration in which a scallop is provided on the web portion of the beam, when a vertical load or a torsional load is applied to the beam due to an earthquake or the like, stress is concentrated around the scallop and the flange portion of the beam is cracked at an early stage. May occur.

An object of the present invention is to prevent early cracking of a beam in a beam joining structure having a scallop.

The present invention is a joint structure of a steel beam joined to a steel column, wherein the beam is made of an H-shaped steel material having a pair of flange portions and a web portion sandwiched between the pair of flange portions. It is formed and joined to the pillar so that the strong axis direction is along the vertical direction, and the web portion is directed from the end face facing the pillar toward the lower flange of the pair of flange portions arranged vertically downward. It has a lower scallop cut out and a thickened portion whose thickness is reduced over a predetermined range from the lower scallop.

Further, the present invention is a method for improving the performance of a joining structure of a steel beam joined to a steel column, wherein the beam is formed by welding a pair of flange portions to a web portion. The web portion is joined to the beam so that the strong axis direction is along the vertical direction, and the web portion is cut out from the end face facing the column toward the lower flange of the pair of flange portions arranged vertically downward. In a method of improving the performance of a beam-joined structure having a welded lower scallop, a step of forming a thickened portion having a thickness reduced over a predetermined range from the lower scallop on the web portion and the lower side thereof. The present invention includes a step of expanding the lower scallop in the material axial direction of the beam by cutting the welded portion provided when the flange and the web portion are welded together with the web portion.

According to the present invention, in a beam joining structure having scallops, it is possible to prevent early cracking in the beam.

It is a side view of the beam joining structure which concerns on 1st Embodiment of this invention. It is an enlarged view of the part shown by the arrow A of FIG. It is a vertical sectional view along the line BB of FIG. It is a graph which shows the change of the deformation performance by a thickening part. It is a graph which shows the change of the fracture life by a thickened part. It is a side view of the beam joining structure which concerns on 2nd Embodiment of this invention.

Hereinafter, the beam joining structure and the method for improving the performance of the beam joining structure according to the embodiment of the present invention will be described with reference to the drawings.

<First Embodiment>
The beam joining structure 100 according to the first embodiment will be described with reference to FIGS. 1 to 3. The beam joint structure 100 is a structure of a joint portion of a steel beam 20 welded to a steel column 10 in a steel-framed building, and in the following, as shown in FIG. 1, along the vertical direction. The structure of the joint portion of the beams 20 arranged along the horizontal direction to be welded and joined to the column 10 erected vertically will be described as an example.

1 is a side view showing the beam joining structure 100 according to the first embodiment, FIG. 2 is an enlarged view showing an enlarged portion indicated by an arrow A in FIG. 1, and FIG. 3 is a view. 2 is an enlarged cross-sectional view showing an enlarged cross section along the line BB of 2. The pillar 10 is not limited to the one arranged strictly along the vertical direction, and the beam 20 is not limited to the one arranged strictly along the horizontal direction. Further, the columns 10 and the beams 20 are not limited to those joined at right angles to each other.

As shown in FIG. 1, the column 10 is formed by a steel pipe portion 11 formed of a square steel pipe and a diaphragm 12 provided between the steel pipe portions 11 in the vertical direction and integrated with the steel pipe portion 11 by butt welding. It is a constructed steel pipe column.

The diaphragm 12 is a so-called through diaphragm, and is formed of a substantially square steel plate having a side length larger than that of the steel pipe portion 11. The diaphragms 12 are arranged in pairs at predetermined intervals in the vertical direction in accordance with the spacing between the pair of flange portions 21 and 22 of the beam 20 described later, and the thickness thereof is larger than the plate thickness of the flange portions 21 and 22. It is set thicker by a predetermined size.

Further, a gusset plate 14 to be joined to the web portion 23 of the beam 20 described later via a high-strength bolt (not shown) is welded to the steel pipe portion 11 arranged between the pair of diaphragms 12 along the vertical direction. There is.

The structure of the column 10 is not limited to the above-mentioned structure, and may be any structure as long as the beam 20 can be welded and joined. For example, a steel column made of H-shaped steel or a circular steel pipe. It may be a truss structure column formed by connecting a plurality of equilateral angle steels, or a concrete-filled steel pipe column formed by pouring concrete into a steel pipe. Further, the diaphragm 12 is not limited to the through diaphragm, and may be an inner diaphragm welded to the inside of the steel pipe portion 11 or may have a configuration in which the diaphragm is not provided.

The beam 20 is an H-shaped steel material having a pair of flange portions 21 and 22 and a web portion 23 sandwiched between the pair of flange portions 21 and 22, and is a pair of steel plates serving as a pair of flange portions 21 and 22. Is a so-called build H-shaped steel formed by welding and joining to a steel plate to be a web portion 23.

The beam 20 is joined to the column 10 by temporarily joining the web portion 23 to the gusset plate 14 via a high-strength bolt (not shown), and welding the pair of flange portions 21 and 22 to the diaphragm 12, respectively. That is, the beam 20 has a web portion 23 sandwiched between the lower flange 21 arranged in the lower vertical direction and the upper flange 22 arranged in the upper vertical direction in a state where the strong axis direction is along the vertical direction. It is joined to the pillar 10 in a state of being arranged along the vertical direction.

The joining of the web portion 23 to the pillar 10 is not limited to bolt joining with high-strength bolts, and may be performed by directly welding and joining the end face 23a of the web portion 23 to the pillar 10. In this case, the gusset plate 14 is not provided on the pillar 10.

In the welded joint of the beam 20 to the column 10, specifically, the backing metal 31 partially welded and fixed to the lower surface of each flange portion 21 and 22 and the side surface of the diaphragm 12 is attached to each flange portion 21 and 22. It is performed by complete penetration welding, which is provided in advance along the width direction of the above and continuously welds the facing portions of the flange portions 21 and 22 and the diaphragm 12 along the backing metal 31.

By performing welding, a welded portion 32 is formed in a region surrounded by each flange portion 21 and 22, a diaphragm 12, and a backing metal 31, and the welded portion 32 is used as each flange portion 21 and 22. A lower scallop 25a and an upper scallop 25b are previously formed on the web portion 23 so as to be continuously formed along the width direction of the web portion 23.

The lower scallop 25a substantially quadrants the web portion 23 from the end surface 23a of the web portion 23 facing the pillar 10 toward the lower flange 21 in the vicinity of the portion where the lower flange 21 and the diaphragm 12 are welded. It is a notch formed by notching the shape. By providing the lower scallop 25a, it is possible to form a welded portion 32 continuously along the backing metal 31 between the lower flange 21 and the diaphragm 12.

On the other hand, the upper scallop 25b has a substantially quadrant shape of the web portion 23 from the end surface 23a of the web portion 23 facing the pillar 10 toward the upper flange 22 in the vicinity of the portion where the upper flange 22 and the diaphragm 12 are welded. It is a notch formed by notching the flange. By providing the upper scallop 25b, it is possible to pass the backing metal 31 in advance along the width direction of the upper flange 22.

By providing the lower scallop 25a and the upper scallop 25b on the web portion 23 in this way, each of the flange portions 21 and 22 can be continuously welded to the diaphragm 12, and the column 10 and the beam 20 can be welded to each other. Sufficient connection strength can be secured. In addition, in order to prevent welding defects from occurring at the start and end of the welded portion 32, end tabs may be provided on the outer sides of the flange portions 21 and 22 in the width direction.

On the other hand, in the configuration in which the lower scallop 25a is provided on the web portion 23, when a vertical load or a torsional load acts on the beam 20 due to an earthquake or the like, the load is transmitted to the lower flange 21 via the web portion 23. At that time, stress is concentrated around the lower end of the lower scallop 25a, and the lower flange 21 is cracked at an early stage starting from the stress concentration portion, and as a result, the beam 20 may be broken at an early stage.

In particular, as shown in FIG. 2, in the build H-section steel in which the lower flange 21 and the web portion 23 are welded together, the periphery of the end face side welded portion 24a formed on the most end face 23a side of the web portion 23. That is, the welding heat-affected portion is relatively located around the portion where the lower end portion of the lower scallop 25a is joined to the lower flange 21 by performing rotary welding in which the working time is longer than that of linear welding. Formed over a wide area. Since the base metal of the weld heat-affected zone is denatured and brittle due to the heat during welding, when stress is concentrated around the lower end of the lower scallop 25a on which the weld heat-affected zone is formed, the lower side starts from this portion. Cracks are likely to occur in the flange 21.

In order to avoid such a phenomenon, in the present embodiment, the web portion 23 is provided with a thickening portion 26 whose thickness is reduced over a predetermined range from the lower scallop 25a.

As shown in FIG. 3, the thickness t2 of the thickened portion 26 is thinner than the plate thickness t1 in the other portion of the web portion 23, that is, the plate thickness t1 of the steel plate forming the web portion 23. It is a portion, and as shown in FIG. 2, is provided at a predetermined height from the upper surface 21a of the lower flange 21 over a predetermined range from the lower scallop 25a along the material axial direction (longitudinal direction) of the beam 20. ..

Specifically, the thickness t2 of the thickened portion 26 is set to, for example, half or less of the plate thickness t1 of the web portion 23, and the height H2 of the thickened portion 26 in the vertical direction from the upper surface 21a of the lower flange 21. Is set in a range not exceeding 5 mm from the scallop height H1, which is the maximum height of the lower scallop 25a, for example.

Further, the length L2 in the material axis direction of the beam 20 from the end surface 23a of the web portion 23 of the portion where the thickening portion 26 is provided, that is, the web in the material axial direction of the beam 20 in the portion where the thickening portion 26 is provided. The length L2 from the end surface 23a to the portion farthest from the end surface 23a of the portion 23 is, for example, the scallop length which is the maximum length of the lower scallop 25a in the material axis direction of the beam 20 from the end surface 23a of the web portion 23. It is set to twice or more of L1.

The setting ranges of the thickness t2, the height H2, and the length L2 of the thickened portion 26 are merely examples, and the thickness t2 of the thickened portion 26 is not limited to this range. It suffices if it is thinner than the original thickness of the portion 23, and the height H2 of the thickened portion 26 exceeds 5 mm from the scallop height H1 unless the rigidity of the web portion 23 is extremely reduced. It may be equal to or lower than the scallop height H1.

Further, as shown in FIGS. 2 and 3, the material axial direction welded portion 24b (welded portion) formed when the lower flange 21 and the web portion 23 are fillet welded along the material axial direction of the beam 20. ) Is provided, the thickening portion 26 is provided over the welded portion 24b in the material axial direction, and is formed by removing a part thereof along the upper surface 21a of the lower flange 21 by cutting or the like.

In the example shown in FIG. 3, the thickness of the web portion 23 of the portion where the thickening portion 26 is provided is the same thickness (t2) toward the lower flange 21 even at the portion where the material axial welded portion 24b is formed. ), But in the portion where the material axial welded portion 24b is formed, for example, as shown by the alternate long and short dash line (26a) in FIG. 3, a certain amount of surplus of the material axial welded portion 24b remains. In addition, the thickness may gradually increase toward the lower flange 21. The plane on the lower flange 21 side formed by removing a part of the welded portion 24b in the material axial direction is preferably located on the same plane as the upper surface 21a of the lower flange 21, but strictly speaking. It does not have to be flush.

In this way, the thickened portion 26 is formed by reducing the thickness of the web portion 23 or the material axial welded portion 24b welded to the web portion 23 and the lower flange 21.

The thickened portion 26 having the above shape can be formed by using a general tool such as an end mill before the beam 20 is welded to the column 10 or after the beam 20 is welded to the column 10. For example, it is possible to later process the thickened portion 26 on the beam 20 of the already constructed building.

By providing such a thickening portion 26 on the web portion 23, the cross-sectional area at the portion where the web portion 23 is connected to the lower flange 21 is smaller than that at the portion where the thickening portion 26 is not provided. It becomes smaller around the lower scallop 25a where the thick portion 26 is provided.

In other words, by providing the thickening portion 26, the area around the lower scallop 25a that can transmit the load to the lower flange 21 via the web portion 23 is reduced. Therefore, the load acting on the lower flange 21 is reduced around the lower scallop 25a, and as a result, stress is suppressed from being concentrated around the lower end of the lower scallop 25a.

As a result, early cracking is suppressed in the weld heat-affected zone formed around the portion where the lower end of the lower scallop 25a is joined to the lower flange 21, and the beam 20 is broken at an early stage. It can be suppressed.

Subsequently, with reference to FIGS. 4A and 4B, changes in the deformation performance of the beam 20 due to the provision of the thickening portion 26 will be described. FIG. 4A is a graph showing a change in deformation performance when the thickness t2 of the thickened portion 26 is changed, and FIG. 4B shows a change in breaking life when the length L2 of the thickened portion 26 is changed. It is a graph.

The graph of FIG. 4A corresponds to the web portion 23 on which the lower scallop 25a is formed, the lower flange 21 to which the web portion 23 is welded and joined, and the diaphragm 12 to which the lower flange 21 is welded and joined, respectively. The results of measuring the amount of deformation of the test piece in the load direction when a tensile load is applied in the direction in which the member corresponding to the lower flange 21 and the member corresponding to the diaphragm 12 are separated from the test piece having at least the member. Shown.

The solid line A in the graph of FIG. 4A is not provided with the thickening portion 26, that is, the deformation amount of the test piece corresponding to the conventional beam joining structure in which the thickness t2 of the thickening portion 26 is equal to the plate thickness t1. The one-dot chain line B indicates the amount of deformation of the test piece corresponding to the beam joining structure 100 according to the present embodiment in which the thickness t2 of the thickened portion 26 is set to one half of the plate thickness t1. The chain line C shows the amount of deformation of the test piece corresponding to the beam joining structure 100 according to the present embodiment in which the thickness t2 of the thickened portion 26 is set to one-third of the plate thickness t1.

Assuming that the final point is when the load acting on each test piece drops to 90% of the maximum load in the plastic range, the amount of deformation when the final point is reached is determined by the thickening portion 26 as shown in FIG. 4A. The thickness t2 of the thickened portion 26 is smaller than the deformation amount δB when the deformation amount δA is the smallest when it is not provided and the thickness t2 of the thickened portion 26 is half of the plate thickness t1. It can be seen that the deformation amount δC when it is one-third of t1 is larger.

That is, the thickening portion 26 is provided by providing the thickening portion 26 as described above in the web portion 23 and setting the thickness t2 to about one-half to one-third of the plate thickness t1. It can be said that it is possible to improve the plastic deformation performance as compared with the case without it.

In the graph of FIG. 4B, the beam 20 has a predetermined plasticity ratio (for an analytical model having at least a beam 20 having a web portion 23 on which the lower scallop 25a is formed and a column 10 to which the beam 20 is joined. The result is shown by oscillating at μ = 2.0) and calculating the number of repetitions until the lower flange 21 breaks by simulation.

In the graph of FIG. 4B, the horizontal axis shows the ratio (L2 / L1) of the length L2 of the thickening portion 26 to the scallop length L1, and the vertical axis shows the breaking life when the thickening portion 26 is not provided. The ratio of the breaking life when 1 is shown.

As shown in FIG. 4B, as the ratio (L2 / L1) of the length L2 of the thickened portion 26 to the scallop length L1 is made larger than 2, the breaking life is improved and the ratio (L2 / L1) is about 4. Then, it can be seen that the improvement of the breaking life is slowed down.

That is, by setting the ratio (L2 / L1) of the length L2 of the thickening portion 26 to the scallop length L1 to about 2 to 4, the breaking life is improved as compared with the case where the thickening portion 26 is not provided. It can be said that it is possible to make it.

By providing the thickening portion 26 having a predetermined thickness over a predetermined range from the lower scallop 25a in this way, early cracking of the lower flange 21 is suppressed, and the plastic deformation capacity and fracture of the beam 20 are suppressed. The life can be improved.

According to the above first embodiment, the following effects are obtained.

In the beam joining structure 100 having the above configuration, the web portion 23 of the beam 20 formed of the H-shaped steel material welded to the steel column 10 has a thickness of the lower scallop 25a and the lower scallop 25a over a predetermined range. A thickening portion 26 having a reduced thickness is provided.

In this way, by providing the thickening portion 26 having a predetermined thickness over a predetermined range from the lower scallop 25a, the load is transmitted to the lower flange 21 via the web portion 23 around the lower scallop 25a. The possible area is reduced. Therefore, the load acting on the lower flange 21 is reduced around the lower scallop 25a, and as a result, stress is suppressed from being concentrated around the lower end of the lower scallop 25a. As a result, it is possible to prevent the lower flange 21 from being cracked at an early stage and to prevent the beam 20 from being broken at an early stage.

Further, since the connection area between the web portion 23 and the lower flange 21 is reduced in the portion where the thickening portion 26 is provided, the plastic deformation performance of the lower flange 21 is reduced around the portion where the thickening portion 26 is provided. Will be improved. As a result, the energy absorption performance of the beam 20 with respect to the seismic force is improved, and as a result, the seismic resistance of the building to which the beam joining structure 100 having the above configuration is applied can be improved.

<Second Embodiment>
Next, the beam joining structure 200 according to the second embodiment of the present invention will be described with reference to FIG. Hereinafter, the points different from those of the first embodiment will be mainly described, and the description of the same or equivalent configurations as those described in the first embodiment will be omitted.

The beam joining structure 200 according to the second embodiment has a beam joining structure according to the first embodiment described above in that a thinning portion 26 having a predetermined thickness is provided from the lower scallop 25a over a predetermined range. Same as 100, but with the beam joining structure 100 according to the first embodiment described above, in that an enlarged scallop 125a formed by expanding the lower scallop 25a in the material axis direction of the beam 20 is provided. It's different. Note that FIG. 5 is an enlarged view showing a portion corresponding to FIG. 2.

As shown in FIG. 5, the enlarged scallop 125a is a notch provided at a position farther from the end surface 23a of the web portion 23 than the lower scallop 25a in the material axis direction of the beam 20, and is a notch provided with the lower scallop 25a. It is formed in almost the same shape.

Specifically, in the enlarged scallop 125a, the end face side welded portion 24a formed when the web portion 23 on which the lower scallop 25a is formed and the lower flange 21 are welded and joined to the upper surface 21a of the lower flange 21. It is formed by removing the web portion 23 along the same direction by cutting or the like, and cutting the portion of the web portion 23 provided with the lower scallop 25a by a predetermined length along the material axis direction.

Further, the web portion 23 of the beam 20 provided with the enlarged scallop 125a has a predetermined length L2 in the material axial direction of the beam 20 from the end surface 23a of the web portion 23, as in the first embodiment. A thickening portion 26 having a predetermined height H2 in the vertical direction from the upper surface 21a of the side flange 21 is provided over a predetermined range from the lower scallop 25a.

Therefore, in the beam joining structure 200, the step of forming the thickened portion 26 whose thickness is reduced over a predetermined range from the lower scallop 25a on the web portion 23 and the welding joining of the lower flange 21 and the web portion 23 are performed. The lower scallop 25a is expanded in the material axis direction of the beam 20 by cutting the end face side welded portion 24a, which is a welded portion provided at the time of the process, together with the web portion 23 to form an enlarged scallop 125a. It is formed through a process. Either of these two steps may be performed first.

The thickened portion 26 and the enlarged scallop 125a having the above shape are formed by using a general tool such as an end mill before the beam 20 is welded to the column 10 or after the beam 20 is welded to the column 10. For example, it is also possible to later process the thickened portion 26 and the expanded scallop 125a on the beam 20 of the already constructed building.

Here, the periphery of the end face side welded portion 24a formed at the lower end of the lower scallop 25a is an embrittled weld heat affected zone as described above. Therefore, when the load is transmitted to the lower flange 21 via the web portion 23 and the end face side welded portion 24a, the end face side welded portion 24a and the lower flange 21 are generated at the portion where the end face side welded portion 24a and the lower flange 21 are fused closest to the end face 23a. Stress is concentrated on the end face side heat affected zone P1 (see FIG. 5), and there is a possibility that the lower flange 21 may be cracked at an early stage starting from the end face side heat affected zone P1 and its periphery.

On the other hand, in the present embodiment, by expanding the lower scallop 25a to form the enlarged scallop 125a as described above, the lower end position of the enlarged scallop 125a is set to the web portion 23 rather than the lower end position of the lower scallop 25a. It is located away from the end face 23a of.

That is, as shown in FIG. 5, the lower end position of the enlarged scallop 125a, which is the position where the web portion 23 and the lower flange 21 are connected on the end surface 23a side, is the end surface side heat affected zone in the material axis direction of the beam 20. It will be located at a place separated from P1 by a predetermined first distance D1. The size of the first distance D1 is set to, for example, twice or more the second distance D2, which is the distance from the end face side heat-affected zone P1 to the lower end position of the lower scallop 25a.

Therefore, the load transmitted to the lower flange 21 via the web portion 23 acts on the vicinity of the lower end position of the enlarged scallop 125a away from the end face side heat affected zone P1 and acts on the end face side heat affected zone P1. The concentration of stress is suppressed. As a result, it is possible to prevent early cracking in the lower flange 21 starting from the end face side heat-affected zone P1 and its periphery.

In order to improve the embrittlement of the weld heat affected zone, after removing the end face side welded portion 24a to form the enlarged scallop 125a, the lower flange is directed from the lower end position of the enlarged scallop 125a toward the end face 23a of the web portion 23. It is preferable to apply a peening treatment to the upper surface 21a of the 21. By applying the peening treatment to the range including the portion from which the end face side welded portion 24a has been removed in this way, the portion from which the end face side welded portion 24a has been removed, the end face side heat affected zone P1, and the periphery thereof can be used at an early stage. It is possible to suppress the occurrence of cracks.

Subsequently, with reference to FIG. 4A, changes in the deformation performance of the beam 20 due to the provision of the thickened portion 26 and the enlarged scallop 125a will be described. The graph of FIG. 4A shows the web portion 23 on which the lower scallop 25a or the enlarged scallop 125a is formed, the lower flange 21 to which the web portion 23 is welded and joined, and the diaphragm 12 to which the lower flange 21 is welded and joined. The amount of deformation of the test piece in the load direction when a tensile load is applied in the direction of separating the member corresponding to the lower flange 21 and the member corresponding to the diaphragm 12 with respect to the test piece having at least the member corresponding to each of the above. The measurement result is shown.

The solid line A in the graph of FIG. 4A shows the amount of deformation of the test piece corresponding to the conventional beam joining structure in which the lower scallop 25a is provided but the thickening portion 26 is not provided as described above, and is a broken line. In D, the thickness t2 of the thickened portion 26 is set to one half of the plate thickness t1, and the above-mentioned enlarged scallop 125a is formed. Shows the amount.

Assuming that the final point is when the load acting on each test piece drops to 90% of the maximum load in the plastic range, the amount of deformation when the final point is reached is the thickening portion 26 and the thickening portion 26 and the amount of deformation when the final point is reached. It can be seen that the deformation amount δD when the thickened portion 26 and the enlarged scallop 125a are provided is significantly larger than the deformation amount δA when the enlarged scallop 125a is not provided. Further, the deformation amount δD when the thickening portion 26 and the enlarged scallop 125a are provided is the deformation amount of the test piece corresponding to the beam joining structure 100 according to the above-mentioned first embodiment in which only the thickening portion 26 is provided. It is larger than δB and δC.

That is, by providing the thickening portion 26 and the enlarged scallop 125a, the plastic deformation performance is significantly improved as compared with the case where the thickening portion 26 is not provided or only the thickening portion 26 is provided. It can be said that it is possible.

According to the above-mentioned second embodiment, in addition to the same effect as the above-mentioned first embodiment, the following effects are exhibited.

In the beam joining structure 200 having the above configuration, the thickness of the web portion 23 of the beam 20 formed of the H-shaped steel material welded to the steel column 10 is reduced from the lower scallop 25a over a predetermined range. A thick portion 26 and an enlarged scallop 125a formed by expanding the lower scallop 25a in the material axis direction of the beam 20 are provided.

In this way, by expanding the lower scallop 25a in the material axis direction of the beam 20 to form the enlarged scallop 125a, the load transmitted to the lower flange 21 via the web portion 23 is the end face side heat affected zone. It acts around the lower end position of the enlarged scallop 125a, which is separated from P1 by a predetermined first distance D1. As a result, stress concentration on the end face side heat-affected zone P1 is suppressed, and as a result, the lower flange 21 is prevented from being cracked at an early stage starting from the end face side heat-affected zone P1 and its periphery. Can be done.

The following modifications are also within the scope of the present invention, and the configurations shown in the modifications may be combined with the configurations described in the above-described embodiments, or the configurations described in the following different modifications may be combined. It is also possible.

In each of the above embodiments, the thickness of the thickened portion 26 is constant over the entire area. The thickness of the thickened portion 26 does not have to be constant over the entire area. For example, the thickness may be gradually reduced toward the end surface 23a of the web portion 23, or gradually reduced toward the lower flange 21. You may do it.

Further, in each of the above embodiments, the thickening portion 26 is provided only around the lower scallop 25a. In order to prevent early cracking in the weld heat-affected zone formed on the lower flange 21 due to the action of a load downward in the vertical direction through the web portion 23 on the lower flange 21, at least the lower side. A thickening portion 26 may be provided around the side scallop 25a, but the welding heat affected zone is also formed around the portion where the upper end portion of the upper scallop 25b is joined to the upper flange 22. Therefore, the thickening portion 26 may be provided around the upper scallop 25b in addition to the periphery of the lower scallop 25a. By providing the thickening portion 26 around the upper scallop 25b in this way, it is possible to prevent early cracking in the weld heat affected zone of the upper flange 22.

Further, in each of the above embodiments, the shape of the lower scallop 25a and the enlarged scallop 125a is a substantially quadrant shape. The shapes of the lower scallop 25a and the enlarged scallop 125a are not limited to this, and may be a combination of a plurality of arcs having different curvatures. It may have a shape having.

Further, in each of the above embodiments, the beam 20 is a build H-shaped steel, but the beam 20 may be a steel material having a web portion 23 and a lower flange 21 integrated with the web portion 23. For example, it may be a so-called roll H-shaped steel which is an H-shaped steel formed by rolling.

Although the embodiments of the present invention have been described above, the above-described embodiments show only a part of the application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above-described embodiments. do not have.

100, 200 ... Beam welded structure 10 ... Pillar 20 ... Beam 21 ... Lower flange 21a ... Upper surface of lower flange 21 23 ... Web part 23a ... Web part 23 End face 24a ... End face side welded part 24b ... Material axial welded part 25a ... Lower scallop 26 ... Thickened part 125a ... Enlarged scallop H1 ... Scallop height L1 ... Scallop Length t1 ... Plate thickness of web portion 23 t2 ... Thickness of thickened portion 26 H2 ... Height of thickened portion 26 L2 ... Length of thickened portion 26 P1 ... End face Side heat influence part D1 ... 1st distance D2 ... 2nd distance

Claims (5)

It is a joint structure of steel beams that are joined to steel columns.
The beam is formed of an H-shaped steel material having a pair of flange portions and a web portion sandwiched between the pair of flange portions, and is joined to the column so that the strong axis direction is along the vertical direction.
The web part is
A lower scallop cut out from the end face facing the pillar toward the lower flange arranged vertically downward among the pair of flange portions.
It has a thickened portion, the thickness of which is reduced over a predetermined range from the lower scallop.
Beam joint structure. The thickened portion is provided so that the height in the vertical direction from the lower flange does not exceed 5 mm from the maximum height in the vertical direction of the lower scallop.
The beam joining structure according to claim 1. The length from the end face of the portion of the portion provided with the thickened portion to the portion farthest from the end face of the web portion in the material axis direction of the beam is the length from the end face in the material axis direction of the beam. More than twice the maximum length of the lower scallop,
The beam joining structure according to claim 1 or 2. The beam is formed by welding and joining the pair of flange portions to the web portion.
The thickened portion is provided over a welded portion where the lower flange and the web portion are welded and joined along the material axis direction of the beam.
The beam joining structure according to any one of claims 1 to 3. It is a method of improving the performance of the joint structure of steel beams joined to steel columns.
The beam is formed by welding and joining a pair of flange portions to the web portion, and the beam portion is joined to the column so that its strong axis direction is along the vertical direction, and the web portion is formed from an end face facing the column. In a method of improving the performance of a beam joint structure having a lower scallop notched toward a lower flange located vertically downward of a pair of flanges.
A step of forming a thickened portion having a thickness reduced over a predetermined range from the lower scallop on the web portion.
It has a step of expanding the lower scallop in the material axial direction of the beam by cutting the welded portion provided when the lower flange and the web portion are welded together with the web portion.
How to improve the performance of beam joint structure.

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