JP6807787B2 - Steel beam reinforcement structure - Google Patents

Description

The present invention relates to a steel beam reinforcing structure.

For example, a widening reinforcing structure is known in which a reinforcing plate is joined to a flange at an end of a steel beam of H-shaped steel to widen the width of the flange (see, for example, Patent Documents 1 and 2).

Japanese Unexamined Patent Publication No. 10-266340 Japanese Unexamined Patent Publication No. 11-61994

In the technique disclosed in Patent Document 1, the reinforcing plate is made of high-strength steel to enhance the reinforcing effect of the end portion of the steel frame beam.

However, local buckling is likely to occur at the flange portion whose width is widened by the reinforcing plate (hereinafter, referred to as “widened portion”). Therefore, the seismic performance of steel beams may deteriorate.

In consideration of the above facts, an object of the present invention is to suppress local buckling of the widened portion of the steel frame beam while enhancing the reinforcing effect of the end portion of the steel frame beam.

The steel beam reinforcing structure according to claim 1 has a pair of flanges facing each other in the vertical direction and a web connecting the pair of flanges, and the steel beam joined to the column and the side of the flange. A reinforcing plate joined to the end portion and the pillar to widen the width of the flange and have a higher strength than the flange is provided, and the flange and the reinforcing plate satisfy the formula (1).

According to the steel beam reinforcing structure according to claim 1, a reinforcing plate for widening the width of the flange is joined to the side end portion of the flange of the steel beam and the column. This reinforcing plate is said to have higher strength than the flange. As a result, the reinforcing effect of the end portion of the steel beam is enhanced.

Further, the flange and the reinforcing plate satisfy the formula (1). Therefore, the width-thickness ratio of the portion formed by the flange and the reinforcing plate (hereinafter referred to as “widening portion”) is set to FC rank or higher, that is, a plasticity ratio of 1 or higher.

As a result, even if the steel beam is plastically deformed in the vicinity of the end portion of the reinforcing plate opposite to the column, local buckling is suppressed in the widened portion. Therefore, the seismic performance of steel beams can be improved.

As described above, in the present invention, it is possible to suppress the local buckling of the widened portion of the steel frame beam while enhancing the reinforcing effect of the end portion of the steel frame beam.

The steel beam reinforcing structure according to claim 2 is the steel beam reinforcing structure according to claim 1, and the reinforcing plate satisfies the formula (2).

According to the steel beam reinforcing structure according to claim 2, the reinforcing plate satisfies the formula (2). As a result, the ratio of the width to the length of the reinforcing plate (hereinafter, referred to as “width-length ratio”) is set within a predetermined range.

Here, at the time of an earthquake, a part of the stress transmitted from the flange of the steel beam to the column is transmitted from the flange to the column via the reinforcing plate. At this time, if the width of the reinforcing plate is wide, there is a possibility that a portion where stress does not flow through the reinforcing plate may occur.

On the other hand, in the present invention, as described above, the width of the reinforcing plate is set within a predetermined range in which stress can be transmitted by setting the width-length ratio of the reinforcing plate according to the equation (2). As a result, waste of the reinforcing plate can be eliminated. Therefore, the cost of the reinforcing plate can be reduced.

The steel beam reinforcing structure according to claim 3 has a pair of flanges facing each other in the vertical direction and a web connecting the pair of flanges, and the steel beam joined to the column and the side of the flange. A reinforcing plate extending in the vertical direction from an end and joined to the column to have a higher strength than the flange is provided, and the reinforcing plate satisfies the formula (3).

According to the steel beam reinforcement structure according to claim 3, a reinforcing plate extending in the vertical direction from the side end of the flange of the steel beam is provided. This reinforcing plate is joined to the column and has higher strength than the flange. As a result, the reinforcing effect of the end portion of the steel beam is enhanced.

Further, the reinforcing plate satisfies the formula (3). Therefore, the width-thickness ratio of the reinforcing plate is set to FC rank or higher, that is, a plasticity ratio of 1 or higher.

As a result, even if the steel beam is plastically deformed in the vicinity of the end opposite to the column in the reinforcing plate, local buckling is suppressed in the reinforcing plate. Therefore, the seismic performance of steel beams can be improved.

As described above, in the present invention, it is possible to suppress the local buckling of the widened portion of the steel frame beam while enhancing the reinforcing effect of the end portion of the steel frame beam.

As described above, according to the steel beam reinforcing structure according to the present invention, it is possible to suppress the local buckling of the widened portion of the steel beam while enhancing the reinforcing effect of the end portion of the steel beam.

FIG. 1 is a perspective view showing a steel beam and a column to which the steel beam reinforcing structure according to the first embodiment is applied. FIG. 2 is a plan view of the steel beam and column shown in FIG. 1 as viewed from above. FIG. 3 is a sectional view taken along line 3-3 of FIG. FIG. 4 is a partially enlarged view of FIG. 2 showing a reinforcing plate. FIG. 5 is a perspective view showing an analysis model of steel beams and columns. FIG. 6 is a side view showing the web of the steel beam shown in FIG. FIG. 7 is a stress distribution diagram showing the analysis results of the steel beam according to the embodiment. FIG. 8 is a stress distribution diagram showing the analysis results of the steel beam according to the comparative example. FIG. 9 is a cross-sectional view corresponding to FIG. 3 showing a steel beam to which the steel beam reinforcing structure according to the second embodiment is applied.

Hereinafter, the steel beam reinforcing structure according to the first embodiment will be described with reference to the drawings.

(Steel beam)
FIG. 1 shows a steel beam 20 to which the steel beam reinforcing structure 10 according to the present embodiment is applied. The steel beam 20 is formed in an H-shaped cross section. The steel beam 20 has a pair of upper and lower flanges 22 and 24 and a web 26.

The pair of upper and lower flanges 22, 24 are arranged so as to face each other in the vertical direction. Further, the pair of upper and lower flanges 22, 24 are connected by a web 26. For example, a concrete slab (not shown) is provided on the upper flange 22.

The web 26 is arranged between a pair of upper and lower flanges 22 and 24. The upper and lower ends of the web 26 are joined to the central portions of the pair of upper and lower flanges 22 and 24 in the width direction, respectively.

The steel beam 20 is a so-called non-bracket type steel beam, and its end portion is joined to the column beam joint portion 12S of the column 12 by welding or the like at the site, for example. The column 12 is a steel column formed by a square steel pipe. Further, the pillar 12 has four side wall portions 12A. A pair of diaphragms 14 are provided in the column-beam joint portion 12S of the column 12.

The pillar 12 is not limited to the square steel pipe, and may be, for example, a round steel pipe, an H-shaped steel, or the like, or a CFT or the like.

The pair of diaphragms 14 are, for example, through diaphragms. Further, the pair of diaphragms 14 are formed in a plate shape by a steel plate or the like. The pair of diaphragms 14 face each other in the material axis direction (vertical direction) of the pillar 12.

The pair of diaphragms 14 is not limited to the through diaphragm, and may be an inner diaphragm or an outer diaphragm. Further, the pair of diaphragms 14 may be provided as needed and may be omitted as appropriate.

The end faces 14T of the pair of diaphragms 14 are joined by welding or the like with the ends 22E and 24E of the pair of upper and lower flanges 22 and 24 on the pillar 12 side abutting each other. Further, the end portion 26E on the column 12 side of the web 26 is joined to the side wall portion 12A of the column-beam joint portion 12S by welding or the like in a state of being abutted against the side wall portion 12A.

Arc-shaped scallops 28 are formed at the upper and lower ends of the end portion 26E of the web 26, respectively. Further, the end portion 26E of the web 26 of the steel frame beam 20 may be joined to the side wall portion 12A of the column 12 via a gusset plate, a bolt or the like.

(Wide part)
As shown in FIGS. 2 and 3, the upper flange 22 at the end of the steel beam 20 is provided with a pair of reinforcing plates 40 that widen the width of the flange 22. Similarly, the lower flange 24 at the end of the steel beam 20 is provided with a pair of reinforcing plates 50 that widen the width of the flange 24.

The pair of reinforcing plates 40 and the pair of reinforcing plates 50 have the same configuration. Therefore, in the following, the configuration of the pair of reinforcing plates 40 will be described, and the description of the pair of reinforcing plates 50 will be omitted. Further, in the following, the portion formed by the flange 22 and the pair of reinforcing plates 40 will be referred to as the widening portion 30.

As shown in FIG. 2, the pair of reinforcing plates 40 are provided along the side end portions 22S on both sides in the width direction of the flange 22. Further, each reinforcing plate 40 is arranged over the end surface 22S1 of the side end portion 22S of the flange 22 and the end surface 14T of the diaphragm 14.

Each reinforcing plate 40 is formed in a rectangular shape extending in the longitudinal direction of the steel frame beam 20. One end 40A of the reinforcing plate 40 in the longitudinal direction is joined by welding or the like while being abutted against the end surface 14T of the diaphragm 14.

As shown in FIG. 4, a width reducing portion 42 is provided on the other end portion 40B side in the longitudinal direction of the reinforcing plate 40. The width reducing portion 42 is formed in a triangular shape in a plan view, and the width is narrowed toward the center side (opposite side of the column 12) of the steel frame beam 20 in the material axis direction.

Further, the width reducing portion 42 has an inclined end portion 42G that inclines toward the outside of the flange 22 from the central side of the steel frame beam 20 toward the column 12 side. The inclined end portion 42G is inclined with respect to the side end portion 22S (end surface 22S1) of the flange 22 at a predetermined inclination angle θ.

(Width-thickness ratio of widened part)
Here, when a pair of reinforcing plates 40 are provided on the upper flange 22, the rigidity of the steel frame beam 20 changes in the vicinity of the other end 40B of the pair of reinforcing plates 40. Therefore, during an earthquake, stress tends to be concentrated near the other end 40B of the pair of reinforcing plates 40. Therefore, in the present embodiment, a plastic hinge can be generated in the steel beam 20 near the other end 40B of the reinforcing plate 40 at the time of an earthquake. In other words, in the present embodiment, the position where the plastic hinge is generated during an earthquake can be moved from the joint portion between the steel beam 20 and the column 12 to the central side of the steel beam 20 in the material axial direction.

Further, the pair of reinforcing plates 40 are formed of a steel material having a higher strength than the flange 22. As a result, when stress is transmitted from the end of the steel beam 20 to the column 12 during an earthquake, the stress is more likely to be concentrated on the pair of reinforcing plates 40 than on the flange 22. As a result, the stress concentration on the joint portion (scallop 28) between the side wall portion 12A of the column 12 and the end portion 26E of the web 26 is relaxed.

On the other hand, as shown in FIG. 1, the width B ₂ of the widening portion 30 is wider than the width B ₁ of the other flange 22. Therefore, in the widening portion 30, local buckling is likely to occur during an earthquake. Then, if local buckling occurs in the widened portion 30, the deformation performance of the steel frame beam 20 may deteriorate.

As a countermeasure for this, in the present embodiment, the width-thickness ratio of the widening portion 30 is set so as to satisfy the equation (1).

However,
B ₂ : Total width of reinforcing plate and flange t ₁ : Flange plate thickness t ₂ : Reinforcing plate plate thickness F ₂ : Standard strength of reinforcing plate.

Supplementing the formula (1), for example, in the Building Standards Act, there are ranks (member ranks) such as FA, FB, FC, and FD as an index showing the plastic deformation performance (plasticity ratio) of a steel beam. This rank is determined by the width-thickness ratio of the flange of the steel beam, the width-thickness ratio of the web, and the reference strength of the steel grade (steel material). The ranks are FA, FB, FC, and FD in descending order of plastic deformation performance.

The FA rank steel beam has a plasticity ratio of 4, and the width-thickness ratio (B / t) of the flange is defined by the following formula (a).

However,
B: Width of the flange of the steel beam t: Plate thickness of the flange of the steel beam F: Standard strength of the steel grade of the flange (N / mm2)
Is.

Further, the FC rank steel beam has a plasticity ratio of 1, and the width-thickness ratio (B / t) of the flange is defined by the following formula (b).

However,
B: Width of the flange of the steel beam t: Plate thickness of the flange of the steel beam F: Standard strength of the steel grade of the flange (N / mm ² )
Is.

Here, in order to prevent local buckling from occurring in the widening portion 30 during an earthquake, the plasticity ratio of the widening portion 30 needs to be 1 or more. That is, the width-thickness ratio of the widening portion 30 needs to satisfy the FC rank (the above formula (b)).

Also, the width and thickness of the reinforcing plate 40 and _B 2, _{t 2,} when the thickness of the flange 22 and _{t 1,} the width-thickness ratio of the widening section _{30, (B 2/2) /} t 1 and (B _It is obtained as an intermediate value with 2/2) / t ₂ , but here, as shown in the following formula (c), the design on the safe side is made by adopting the larger value of the two. The width of the flange 22 is B ₁ .

However,
min (t ₁ , t ₂ ): When t ₁ ≧ t ₂ , min (t ₁ , t ₂ ) = t ₂
When t ₁ <t ₂ , min (t ₁ , t ₂ ) = t ₁
Is.

In this case, when the above formula (c) is less than or equal to the above formula (b), that is, by satisfying the above formula (1), the widening portion 30 becomes FC rank or higher. As a result, local buckling of the widening portion 30 is suppressed during an earthquake.

(Width-length ratio of reinforcing plate)
Next, a description will be given length _{L 2} (longitudinal length) width to W of the reinforcing plate _{40 (= (B 2 -B 1} ) / 2) ratio (hereinafter referred to as "width length ratio").

As shown in FIG. 4, during an earthquake, a stress P is transmitted from the flange 22 to the other end 40B of the reinforcing plate 40, and this stress P has an inclination angle θ of 30 degrees with respect to the side end 22S of the flange 22. It is efficiently transmitted to the following range (θ ≦ 30 degrees).

Therefore, in the present embodiment, the width-length ratio of the reinforcing plate 40 is set so as to satisfy the following equation (2). As a result, the portion K in which stress is not transmitted from the reinforcing plate 40 can be omitted.

However,
B ₁ : Flange width B ₂ : Widening part width L ₂ : Reinforcing plate length.

(Action)
Next, the operation of the first embodiment will be described.

According to the steel beam reinforcing structure according to the present embodiment, a reinforcing plate 40 for widening the width of the flange 22 is joined to the flange 22 at the end of the steel beam 20. The reinforcing plate 40 has a higher strength than the flange 22. Thereby, the reinforcing effect of the end portion of the steel frame beam 20 can be enhanced.

Further, the widening portion 30 composed of the flange 22 and the reinforcing plate 40 is formed so as to satisfy the equation (1). As a result, the width-thickness ratio of the widening portion 30 is set to FC rank or higher, that is, a plasticity ratio of 1 or higher. As a result, even if the steel beam 20 is plastically deformed near the other end 40B of the reinforcing plate 40, local buckling is suppressed in the widened portion 30. Therefore, the seismic performance of the steel beam 20 can be improved.

As described above, in the present embodiment, it is possible to suppress the local buckling of the widening portion 30 while enhancing the reinforcing effect of the end portion of the steel frame beam 20.

Further, by making the pair of reinforcing plates 40 stronger than the flange 22, when the stress is transmitted from the end of the steel beam 20 to the column 12, the stress is concentrated on the pair of reinforcing plates 40 rather than the flange 22. It becomes easier to do. As a result, the stress concentration on the joint between the diaphragm 14 of the column 12 and the flange 22 of the steel beam 20 is relaxed. Therefore, damage to the joint between the diaphragm 14 of the column 12 and the flange 22 of the steel beam 20 is suppressed.

Further, if the pair of reinforcing plates 40 is made stronger than the flange 22, the width W of each reinforcing plate 40 can be narrowed. As a result, the material cost of the reinforcing plate 40 can be reduced, and the weight of the end portion of the steel frame beam 20 can be reduced.

Moreover, the reinforcing plate 40 is formed so as to satisfy the equation (2). As a result, the width-length ratio of the reinforcing plate 40 is set within a predetermined range.

Here, as shown in FIG. 4, a part of the stress P transmitted from the flange 22 of the steel frame beam 20 to the column 12 during an earthquake is transmitted from the flange 22 to the column 12 via the reinforcing plate 40. At this time, if the width W of the reinforcing plate 40 is wide, there is a possibility that a portion K in which stress does not flow through the reinforcing plate 40 may occur.

On the other hand, in the present embodiment, as described above, the width-length ratio of the reinforcing plate 40 is defined by the equation (2). As a result, the width W of the reinforcing plate 40 is set within a predetermined range in which stress can be transmitted. As a result, the region (site K) of the reinforcing plate 40 to which stress is not transmitted, that is, the waste of the reinforcing plate 40 can be eliminated. Therefore, the material cost of the reinforcing plate 40 can be further reduced, and the weight of the end portion of the steel frame beam 20 can be further reduced.

(analysis)
Next, the analysis will be described.

In this analysis, the stress states at the time of an earthquake were obtained by FEM analysis for the end of the steel beam 20 to which the steel beam reinforcing structure 10 according to the example was applied and the end of the steel beam 100 according to the comparative example.

(Analysis model)
5 and 6 show an analysis model of the steel beam 20 to which the steel beam reinforcing structure 10 according to the embodiment is applied. Further, in Table 1 below, various dimensions and the like of the columns 12, the diaphragm 14, and the steel beams 20 and 100 according to the examples and the comparative examples are shown.

Further, Table 2 below shows various dimensions and the like of the reinforcing plate 40 according to the embodiment and the reinforcing plate 102 according to the comparative example. The only difference between the steel beam 20 according to the embodiment and the steel beam 100 according to the comparative example is the width W of the reinforcing plates 40 and 102 and the steel type (steel material).

Specifically, as shown in Table 2, the reinforcing plate 40 according to the embodiment has higher strength than the flanges 22 and 24 of the steel frame beam 20. The width W of the reinforcing plate 40 is set to 26 mm. On the other hand, the reinforcing plate 102 according to the comparative example has the same strength as the flanges 22 and 24 of the steel frame beam 20. Further, the width W of the reinforcing plate 102 according to the comparative example is set to 50 mm.

(analysis method)
As shown in FIG. 5, an upward load F was input to a predetermined position of the steel frame beam 20, and the stress distribution generated at the ends of the steel frame beams 20 and 100 was obtained by analysis. The support conditions for the upper and lower ends of the pillar 12 are fixed.

(Analysis result)
FIG. 7 shows the stress distribution at the end of the steel beam 20 according to the embodiment obtained from the analysis. On the other hand, FIG. 8 shows the stress distribution at the end of the steel beam 100 according to the comparative example obtained from the analysis. Note that FIGS. 7 and 8 show the stress distribution of the flange 24 on the lower side of the steel beam 20, 100. Further, in FIGS. 7 and 8, the concentration of the portion having high stress is high.

As shown in FIGS. 7 and 8, it can be seen that the pair of reinforcing plates 50 according to the embodiment has more stress than the pair of reinforcing plates 102 according to the comparative example. As a result, the stress concentration on the joint between the diaphragm 14 of the column 12 and the flange 24 of the steel beam 20 is relaxed. Therefore, damage to the joint between the diaphragm 14 of the column 12 and the flange 24 of the steel beam 20 can be suppressed.

(Second Embodiment)
Next, the second embodiment will be described. In the second embodiment, members and the like having the same configuration as the first embodiment are designated by the same reference numerals, and the description thereof will be omitted as appropriate.

As shown in FIG. 9A, in the steel beam reinforcing structure 60 according to the second embodiment, a pair of reinforcing plates 70 and 80 are provided on the pair of flanges 22 and 24 above and below the steel beam 20. There is.

The pair of reinforcing plates 70 and the pair of reinforcing plates 80 have the same configuration. Therefore, in the following, the configuration of the pair of reinforcing plates 70 will be described, and the description of the pair of reinforcing plates 80 will be omitted. Further, in the following, the portion formed by the flange 22 and the pair of reinforcing plates 70 is referred to as the widening portion 72.

The pair of reinforcing plates 70 are formed in a rectangular shape extending in the longitudinal direction of the steel frame beam 20. The pair of reinforcing plates 70 are arranged on both sides of the flange 22 in the width direction so as to face each other. Each reinforcing plate 70 is joined by welding or the like with its central portion in the width direction (vertical direction) abutting against the end surface 22S1 of the side end portion 22S of the flange 22.

Further, the reinforcing plate 70 extends from the side end portion 22S of the flange 22 to both sides in the vertical direction. One end (not shown) of the reinforcing plate 70 in the longitudinal direction is joined to the end surface 14T (see FIG. 1) of the diaphragm 14 by welding or the like. As a result, the stress acting on the steel beam 20 at the time of an earthquake is transmitted to the column 12 via the flange 22 and the pair of reinforcing plates 70.

Further, each reinforcing plate 70 is made of a steel material having a higher strength than the flange 22. As a result, the reinforcing effect of the end portion of the steel frame beam 20 is enhanced.

Further, the reinforcing plate 70 is formed so as to satisfy the following formula (3). As a result, the occurrence of local buckling of the widening portion 72 is suppressed.

However,
h: Extension length of the reinforcing plate extending vertically from the flange t ₂ : Thickness of the reinforcing plate F ₂ : Reference strength of the reinforcing plate.

Next, the operation of the second embodiment will be described.

According to the steel beam reinforcing structure 60 according to the present embodiment, the side end portion 22S of the flange 22 of the steel frame beam 20 is provided with a reinforcing plate 70 extending from the side end portion 22S to both sides in the vertical direction. .. One end of the reinforcing plate 70 in the longitudinal direction is joined to the column 12. Further, the reinforcing plate 70 is said to have higher strength than the flange 22 of the steel frame beam 20. Thereby, the reinforcing effect of the end portion of the steel frame beam 20 can be enhanced.

Further, the reinforcing plate 70 is formed so as to satisfy the above formula (3). As a result, the width-thickness ratio of the reinforcing plate 70 is set to FC rank or higher, that is, a plasticity ratio of 1 or higher.

Therefore, even if the steel beam 20 is plastically deformed in the vicinity of the other end in the longitudinal direction of the reinforcing plate 70, local buckling of the reinforcing plate 70 is suppressed. Therefore, the seismic performance of the steel beam 20 can be improved.

As described above, in the present embodiment, it is possible to suppress the local buckling of the widened portion 72 of the steel frame beam 20, more specifically, the pair of reinforcing plates 70, while enhancing the reinforcing effect of the end portion of the steel frame beam 20.

Further, since the pair of reinforcing plates 70 extend from the side end portions 22S of the flange 22 to both sides in the vertical direction, the width of the widening portion 72 is narrowed as compared with the widening portion 30 in the first embodiment. , The reinforcing effect of the end portion of the steel frame beam 20 can be enhanced.

As shown in FIG. 9B, it is also possible to provide the reinforcing plate 74 on the upper surface of the upper flange 22 or the lower surface of the lower flange 24. In this case, the reinforcing effect of the end portion of the steel frame beam 20 can be further enhanced.

Further, in the above embodiment, the reinforcing plate 70 extends from the side end portion 22S of the flange 22 to both sides in the vertical direction, but the above embodiment is not limited to this. The reinforcing plate may extend from the side end of the flange 22 to only one side (upper or lower) in the vertical direction.

(Modification example)
Next, modifications of the first embodiment and the second embodiment will be described. In the following, various modifications will be described using the first embodiment as an example, but these modifications can also be appropriately applied to the second embodiment.

The reinforcing plate 40 of the first embodiment may have a higher strength than the flange 22 of the steel frame beam 20, and its steel type (steel material) can be changed as appropriate.

Further, in the first embodiment, the pair of reinforcing plates 40 are provided on both sides of the flanges 22 and 24 of the steel frame beam 20, but the reinforcing plates 40 may be provided only on one side of the flanges 22 and 24.

Although one embodiment of the present invention has been described above, the present invention is not limited to such an embodiment, and one embodiment and various modifications may be used in combination as appropriate. Of course, it can be carried out in various modes as long as it does not deviate.

10 Steel beam reinforcement structure 12 Column 20 Steel beam 22 Flange 22S Side end 24 Flange 26 Web 40 Reinforcement plate 50 Reinforcement plate 60 Steel beam reinforcement structure 70 Reinforcement plate 80 Reinforcement plate

Claims (3)

A steel beam having a pair of flanges facing each other in the vertical direction and a web connecting the pair of flanges, and being joined to a column.
A reinforcing plate joined to the side end portion of the flange and the column to widen the width of the flange and to have higher strength than the flange.
With
The flange and the reinforcing plate satisfy the formula (1).
Steel beam reinforcement structure.

However,
B ₂ : Total width of reinforcing plate and flange t ₁ : Flange plate thickness t ₂ : Reinforcing plate plate thickness F ₂ : Standard strength of reinforcing plate. The reinforcing plate satisfies the formula (2).
The steel beam reinforcing structure according to claim 1.

However,
B ₁ : Flange width L ₂ : Length of reinforcing plate. A steel beam having a pair of flanges facing each other in the vertical direction and a web connecting the pair of flanges, and being joined to a column.
A reinforcing plate that extends vertically from the side end of the flange and is joined to the column to have higher strength than the flange.
With
The reinforcing plate satisfies the formula (3).
Steel beam reinforcement structure.

However,
h: Extension length of the reinforcing plate extending vertically from the flange t ₂ : Thickness of the reinforcing plate F ₂ : Reference strength of the reinforcing plate.