JP5948963B2 - Beam-column joint structure - Google Patents

Description

  The present invention relates to a column beam connection structure in which a column and a steel beam are rigidly bonded.

  Conventionally, in the column beam frame 1 as shown in the schematic side view of FIG. 1, the column 10 and the steel beam 20 are rigidly joined by welding or the like. Then, when an external force such as seismic force or wind load is input to the column beam frame 1 in the horizontal direction, the bending moment caused thereby is the span direction of the beam 20 (the beam 20 Since it is larger on the end side (hereinafter also referred to as the beam end side) than the center side in the longitudinal direction, the stress becomes maximum at the beam end 20ee, and as a result, the entire cross section first yields and is damaged at the beam end 20ee. To do. That is, in this case, the cross-sectional position that determines the overall strength of the beam 20 is the beam end 20ee. In the following, the cross-sectional position where the overall cross-section yields first and determines the overall strength of the beam 20 is referred to as a “dangerous cross-section position”.

As an example of a method for preventing damage at the beam end 20ee, as shown in the perspective view of FIG. 2A, by providing a haunch 25 at the end 20e of the beam 20 to increase the cross-sectional area of the end 20e, One example is to reduce the stress acting on the cross section of the end 20e (Patent Document 1). In the case of this method, based on the action of increasing the cross-sectional area by the haunch 25, the dangerous cross-section position approaches the center side in the span direction of the beam 20 from the beam end 20e as shown in the top view of FIG. 2B. Change to the new position. That is, the dangerous cross-section position moves to the position of the center end 25ee of the haunch 25.
Since the bending moment acting on the cross-section at the same position is smaller than that of the beam end 20ee, the beam 20 having a small cross-section can be used, and the cost can be reduced. Moreover, the stress degree of the welding part of beam end 20ee can be reduced, and the destruction of the said welding part can be prevented.

JP 2000-309980 A

  Here, when the haunch 25 is also considered to be a part of the beam 20, the cross-sectional shape of the beam 20 changes suddenly at the position of the end 25 ee of the haunch 25. That is, the cross-sectional area of the cross section has increased rapidly starting from the same position. Hereinafter, the position where the cross-sectional shape suddenly changes is referred to as a “cross-sectional sudden change position”. At this cross-sectional sudden change position, plastic strain concentrates on a part of the cross-section, that is, the point A in FIGS. 2A and 2B. (See the FEM analysis result in FIG. 10A).

  Further, the position of the end 25ee of the haunch 25 that is a sudden change position of the cross section is also a dangerous cross section position, that is, a position where the entire cross section of the beam 20 should be yielded first. And if such a position includes a portion where the plastic strain such as the point A is concentrated, particularly when the cross section at the sudden change position is plasticized by an external force such as seismic force or wind load, Very large plastic strain tends to be concentrated at the point A. As a result, damages proceed intensively at the point A, such as when cracks are intensively generated and propagated at the point A of the same cross section, and as a result, the performance of the entire cross section could not be fully utilized.

  The present invention has been made in view of the conventional problems as described above, and the purpose thereof is to shift a dangerous cross-section position from a cross-section sudden change position, thereby generating a large plastic strain in a part of the cross section at the cross-section sudden change position. This is to make full use of the performance of the entire cross section at the position where the cross section suddenly changes.

In order to achieve this object, the invention shown in claim 1
In a column beam connection structure in which a column and a steel beam are rigidly connected,
The steel beam has a reference cross-sectional portion having a reference cross-sectional shape of the steel beam, and a cross-sectional area having a cross-sectional area increased from the reference cross-sectional portion while being positioned closer to the end of the steel beam than the reference cross-sectional portion. An increase part,
The steel beam has an H-shaped steel as a main body,
The reference cross-sectional portion is located on the center side of the cross-sectional area increasing portion in the span direction of the steel beam, and is a portion of only the H-section steel,
The cross-sectional area increasing portion includes the H-section steel provided with the reference cross-sectional area portion and a haunch welded to the H-section steel, or a part of the H-section steel including the reference cross-sectional area portion. And a portion having a cross-sectional area larger than the reference cross-sectional portion,
A reinforcing member is joined to the reference cross-sectional portion and the cross-sectional area increasing portion while straddling the boundary position between the reference cross-sectional portion and the cross-sectional area increasing portion.

According to the first aspect of the present invention, the reinforcing member is joined across the cross-sectional sudden change position which is the boundary position between the reference cross-sectional portion and the cross-sectional area increasing portion. It is shifted from the sudden change position to the center side in the span direction of the steel beam (longitudinal direction of the steel beam). For example, the dangerous cross-sectional position is moved to the position of the center side of the reinforcing member in the span direction of the beam, and thereby the cross-sectional sudden change position and the dangerous cross-sectional position are separated from each other.
Therefore, when a bending moment due to an external force such as seismic force or wind load acts on the steel beam, plastic deformation proceeds mainly at the critical cross-section position, and plastic deformation at the cross-section sudden change position is suppressed. Strain generated in the cross section at the position where the cross section suddenly changes can be suppressed as a whole, and accordingly, the occurrence of concentrated plastic strain in a part of the cross section is also suppressed. Thereby, the performance of the whole cross section at the cross section sudden change position can be fully utilized.

The invention shown in claim 2 is the beam-column joint structure according to claim 1 ,
The reinforcing member is joined to a flange surface of the H-shaped steel flange.
According to the second aspect of the present invention, since the reinforcing member is joined to the flange surface of the flange of the H-shaped steel, a large plastic strain is concentrated on a part of the cross section at the sudden change position. It can be effectively prevented.

The invention shown in claim 3 is the column beam joint structure according to claim 1 or 2 ,
The reinforcing member is bonded to a web surface of the H-shaped steel web.
According to the third aspect of the present invention, since the reinforcing member is joined to the web surface of the H-shaped steel web, it is effective that large plastic strain is concentrated on a part of the cross section at the sudden change position. It becomes possible to prevent.

The invention shown in claim 4 is the column beam connection structure according to any one of claims 1 to 3,
The steel beam has, as a dangerous cross-section position, a position where the entire cross-section yields first due to a bending moment generated with an increase in external force,
Based on the joining of the reinforcing members, the dangerous cross-sectional position is shifted to a position on the center side in the span direction of the steel beam from the boundary position related to the cross-sectional area increasing portion.
According to the fourth aspect of the present invention, since the dangerous cross-sectional position is shifted in the span direction from the cross-sectional sudden change position that is the boundary position, a large plastic strain is concentrated on a part of the cross-section at the cross-sectional sudden change position. Can be reliably prevented.

The invention shown in claim 5 is the column beam connection structure according to claim 4,
The magnitude of the bending moment acting on the position to be the critical cross-sectional position is M1, the magnitude of the bending moment acting on the boundary position is M2,
When the plastic section modulus at the position to be the critical section position is Zp1, and the plastic section coefficient at the boundary position in a state where the reinforcing member is joined is Zp2,
The reinforcing member is designed so that the ratio α (= (M1 / Zp1) / (M2 / Zp2)) is larger than 1.
According to the fifth aspect of the present invention, since the reinforcing member is designed so that the ratio α is larger than 1, the position that should be the dangerous cross-section position is ahead of the cross-section sudden change position that is the boundary position. All sections will yield. That is, the position that should be the dangerous cross-section position can be reliably set as the dangerous cross-section position.

  According to the present invention, by shifting the critical cross-section position from the cross-section sudden change position, it is possible to prevent a large plastic strain from being generated in a part of the cross section at the cross-section sudden change position, and to fully utilize the performance of the entire cross section at the cross-section sudden change position. .

It is a schematic side view of the column beam structure 1 which also wrote the bending moment figure. FIG. 2A is a perspective view of a conventional beam-column joint structure, and FIG. 2B is a top view thereof. It is an external appearance perspective view of the column beam junction structure concerning this embodiment. It is the same top view. It is explanatory drawing of ratio (alpha) used for the design of the cross section of the reinforcing member. FIG. 5A is a cross-sectional view of the H-shaped steel that is the main body of the beam 20, and FIG. 5B is a cross-sectional view of the H-shaped steel in which the reinforcing steel materials 30 and 30 are joined to the flanges 20f and 20f of the H-shaped steel. FIG. 5C is a cross-sectional view of the H-shaped steel in which the reinforcing steel material 30 is joined to the H-shaped steel web 20w. It is a perspective view at the time of joining the reinforcing steel material 30 to the lower surface of the upper flange 20f, and the upper surface of the lower flange 20f. FIG. 7A is an external perspective view of a modification of the present embodiment, and FIG. 7B is a top view thereof. It is a column beam connection structure model used for FEM analysis. FIG. 9A is an explanatory view of a case without reinforcing steel corresponding to a comparative example, and FIG. 9B is an explanatory view of a flange reinforcing case corresponding to the present embodiment. FIG. 9C is an explanatory diagram of a web reinforcing case corresponding to a modification of the present embodiment. It is an analysis result (for relative comparison) of a case without a reinforced steel material. It is an analysis result (for relative comparison) of a flange reinforcement case. It is an analysis result (for relative comparison) of a web reinforcement case. It is an analysis result (for absolute evaluation) of a case without a reinforced steel material. It is an analysis result (for absolute evaluation) of a flange reinforcement case. It is an analysis result (for absolute evaluation) of a web reinforcement case. FIG. 12A is a graph showing the equivalent plastic strain (%) generated at the point A of the lower flange 20f with the deformation angle R as a parameter. FIG. 12A is a graph of a case without reinforcing steel, and FIG. 12B is a flange reinforcing case. FIG. 12C is a graph of the web reinforcing case. 13A to 13C are schematic perspective views showing other examples of the shape of the horizontal haunch 25. 3 is a schematic perspective view showing a cross-sectional area increasing portion 20e formed by a vertical haunch 26. FIG. It is a schematic perspective view at the time of comprising the cross-sectional area increase part 20e of the beam 20 with a single member.

=== This Embodiment ===
FIG. 3A is an external perspective view of a column beam joint structure according to the present embodiment, and FIG. 3B is a top view thereof.
As shown in FIG. 3A, the column 10 has, for example, a steel square pipe having a rectangular cross section as a main body, and the beam 20 is a steel beam. In this example, the H section steel having a H cross section has a main body. To do. The columns 10 and the beams 20 are rigidly joined to each other. That is, the column 10 has a pair of upper and lower through diaphragms 12 and 12. The upper flange 20 f and the lower flange 20 f of the beam 20 are connected to the corresponding through diaphragms 12 and 12 by welding or the like. The web 20w is directly connected to the outer peripheral surface 10s of the column 10 by welding or the like, whereby the column 10 and the beam 20 are rigidly joined.

  The “rigid connection” is a connection mode capable of transmitting a moment. In the example of FIG. 3A, the diaphragm 12 is used through the rigid joint. However, the diaphragm 12 is not limited to this, and the outer diaphragm may be used, or the diaphragm may not be used. The flange 20f may be directly connected to the outer peripheral surface 10s of the column 10, or may be bolted instead of welding. Also, the column 10 is not limited to the above-described square pipe, and a column having a different cross-sectional shape or a column having another structure can be applied as long as the beam 20 can be rigidly joined. For example, a steel round pipe having a circular cross section may be used, a CFT (concrete-filled steel pipe) may be used, or an RC or SRC column may be used.

  Horizontal hunches 25, 25... Are provided at the end 20 e of the beam 20, that is, in the vicinity 20 e of the joint portion of the beam 20 with the column 10. As described above, the horizontal hunches 25, 25... Increase the cross section of the end 20e of the beam 20 to prevent damage to the beam end 20ee. That is, when the portion of only the H-shaped steel located on the center side in the span direction with respect to the end portion 20e in the beam 20 is defined as the reference cross-sectional portion 20b having the standard cross-sectional shape of the beam 20, this reference cross-sectional portion 20b In addition, the horizontal hunches 25, 25... Are integrally provided as a part of the end 20e for the purpose of increasing the cross-sectional area of the end 20e of the beam 20. The horizontal haunch 25 is, for example, a rectangular steel plate in plan view, and is horizontally provided on both sides of the upper flange 20f and the lower flange 20f in the beam width direction. Specifically, each horizontal hunch 25, 25 for the upper flange 20f is abutted against both side surfaces of the upper flange 20f in the beam width direction and joined together by welding or the like, and each horizontal hunch for the lower flange 20f. 25 and 25 are abutted against the side surfaces of the lower flange 20f on both sides in the beam width direction and joined together by welding or the like, and further, the horizontal hunches 25, 25 for the upper flange 20f and the lower flange 20f, respectively. Are integrally joined to the through diaphragms 12 and 12 of the column 10 by welding or the like on the side surface on the column 10 side.

  Incidentally, as shown in FIG. 3B, the end portion 20e of the beam 20 including the horizontal hunches 25, 25... This corresponds to the “cross-sectional area increasing portion 20e”. In addition, since the cross-sectional area of the beam 20 increases from the position of the end 25ee of the center side in the span direction of the beam 20 in the horizontal haunch 25, the position is hereinafter referred to as a “section sudden change position”. The abrupt cross-sectional change position corresponds to a “boundary position” according to the claims, that is, a “boundary position between the reference cross-sectional portion 20b and the cross-sectional area increasing portion 20e”.

  Here, in the present embodiment, as shown in FIGS. 3A and 3B, the reinforcing steel material 30 as an example of the reinforcing member 30 is placed on the upper surface of the upper flange 20f and the lower surface of the lower flange 20f. It is joined and integrated in a state straddling 20 span directions (longitudinal directions). Specifically, the reinforcing steel material 30 is, for example, a rectangular flat plate member having a predetermined thickness, so that substantially the entire surface of one side thereof is brought into close contact with the upper surface of the upper flange 20f so as not to protrude outward in the beam width direction from the upper flange 20f. While being positioned, it is joined by whole circumference fillet welding. On the other hand, the same reinforcing steel material 30 (not shown in FIGS. 3A and 3B) is joined to the lower surface of the lower flange 20f with the same specifications.

  Based on the joining of the reinforcing steel materials 30 and 30, the dangerous cross-sectional position of the beam 20 is moved to the center side in the span direction from the cross-sectional sudden change position as shown in FIG. 3B. As a result, it is possible to prevent a large plastic strain from being generated in a part of the cross section at the position where the cross section suddenly changes, and to take full advantage of the performance of the entire cross section at the position where the cross section suddenly changes. As a result, it is possible to prevent damage to the beam 20 starting from the sudden change position of the cross section, and even if the beam 20 is damaged, in that case, the danger cross section position is preferentially damaged. This will be described in detail below.

  FIG. 2B described above shows the positional relationship between the sudden change position of the cross section and the dangerous cross section position in the case where the reinforcing steel member 30 is not installed, but when the reinforcing steel member 30 is not provided as shown in FIG. 2B. The position of the end 25ee of the horizontal haunch 25 is a sudden section change position and a dangerous section position.

  Here, at the sudden change position of the cross section, the strain tends to be concentrated on a part of the cross section, that is, the point A portion in FIG. 2B (see, for example, the FEM analysis result of FIG. 10A). On the other hand, the dangerous cross-section position is a position where the entire cross-section yields first in the beam 20, but if such a position includes a portion where strain is concentrated such as the above-mentioned A point portion, When the cross section at the position where the cross section suddenly changes is plasticized by an external force such as seismic force or wind load, a very large plastic strain is concentrated especially at the point A portion. Then, cracks are intensively generated and propagated at the point A portion of the same cross section, and the damage progresses intensively at the point A portion. It cannot be in a state where it deforms and resists external force, and therefore the performance of the entire cross section cannot be fully utilized.

In this regard, when the reinforcing steel member 30 is joined as shown in FIG. 3B, the beam 20 portion having the reinforcing steel member 30 can bear the cross-sectional integral of the reinforcing steel member 30 and more stress. The bending strength of 20 increases. Thereby, as shown in FIG. 3B, the dangerous cross-section position moves to the center side in the span direction of the beam 20 from the cross-section sudden change position, that is, the dangerous cross-section position is shifted from the cross-section sudden change position to the central side and separated from each other. It becomes a state. Then, since there is no portion where the plastic strain is concentrated like the above-mentioned point A portion at the cross-section risk position shifted to the center side, the same cross-section is also obtained when the entire cross section of the beam 20 is first yielded. Plastic deformation progresses almost uniformly over the entire surface.
In addition, when a bending moment due to an external force such as seismic force or wind load acts on the beam 20, plastic deformation mainly proceeds at the critical cross-section position, and plastic deformation at the cross-section sudden change position is suppressed. The plastic strain generated in the cross section at the sudden change position can be suppressed as a whole, and accordingly, the occurrence of a large plastic strain concentrated on a part of the cross section is also suppressed. Thereby, the performance of the whole cross section at the cross section sudden change position can be fully utilized.

  Incidentally, in the example of FIGS. 3A and 3B, a rectangular flat plate member is used as the reinforcing steel member 30 and the member is joined to the flange 20f by full-side fillet welding. The present invention is not limited to this as long as the stress can be applied. For example, the bonding method may be bonding with an appropriate adhesive, or friction bonding by tightening a fastening member such as a bolt, and the reinforcing steel member 30 may have a polygonal shape other than a rectangle or a circle. It may be good, and the compound shape which combined these may be sufficient.

By the way, if the above-mentioned reinforcing steel material 30 is joined, the position of the central end 30ee of the reinforcing steel material 30 generally yields as a critical cross-sectional position, so that the cross-sectional sudden change position is at a position different from the dangerous cross-sectional position. However, when it is desired to set a position different from the sudden section change position as the critical section position more reliably, the section of the reinforcing steel material 30 may be designed so as to satisfy the following expression 1.
Ratio α = (M1 / Zp1) / (M2 / Zp2)> 1 (1)
Here, as shown in the perspective view of FIG. 4, M1 in the above equation is a bending moment acting on a position to be set as a dangerous sectional position, and M2 is a bending moment acting on a sudden section change position, Zp1 Is a plastic section modulus at a position to be set as a dangerous section position, and Zp2 is a plastic section coefficient at a section sudden change position.

For example, in the example of FIG. 3B described above, the dangerous cross-sectional position is to be set to the position of the center end 30ee of the reinforcing steel material 30. In this case, M1 and Zp1 are expressed by the following formula 2 and the following formula 3, respectively. Is done. In the example of FIG. 3B, since there is no marginal reinforcing steel material 30 at the critical cross-section position, Zp1 is the plastic section modulus of the portion where the reinforcing steel material 30 is not present in the beam 20, that is, the H-section steel alone. It is a plastic section modulus. As shown in FIG. 4, P in the following equation 2 is a vertical load P (shearing) acting on the inflection point of the moment in the span direction of the beam 20 when a horizontal external force such as seismic force or wind load is assumed. L2 in Formula 2 is the distance from the inflection point of the moment at which the vertical load P acts to the dangerous cross-section position. Further, the meaning of each symbol B, tf, d, tf, tw in the following expression 3 is also shown in FIG. 5A.
M1 = P × L1 (2)
Zp1 = B × tf × (d−tf) + (1/4) × (d−2 × tf) ² × tw (3)

On the other hand, M2 and Zp2 at the section sudden change position are expressed by the following formula 4 and the following formula 5, respectively. Since the reinforcing steel material 30 exists at the position where the cross section suddenly changes, Zp2 is the plastic section modulus of the portion of the beam 20 where the reinforcing steel material 30 is present, that is, the plastic cross section based on both the H-shaped steel and the reinforcing steel material 30. It is a coefficient. In addition, L2 in the following formula 4 is a distance from the inflection point of the moment to which the vertical load P acts as shown in FIG. 4 to the sudden change position of the cross section, and each symbol Bfp in the following formula 5 , Tfp are also shown in FIG. 5B.
M2 = P × L2 (4)
Zp2 = B × tf × (d−tf)
+ (1/4) × (d−2 × tf) ² + Bfp × tfp × (d + tfp) (5)

By the way, in this embodiment, although the reinforcement steel materials 30 and 30 were each provided in both the upper flange 20f and the lower flange 20f, it is not restricted to this at all, and you may provide in either one. Even so, there is a corresponding effect.
In the present embodiment, as shown in FIGS. 3A and 3B, the reinforcing steel materials 30 and 30 are joined to the upper surface of the upper flange 20f and the lower surface of the lower flange 20f, respectively. , 30, or in addition, as shown in the perspective view of FIG. 6, reinforcing steel members 30, 30 may be provided on the lower surface of the upper flange 20f and the upper surface of the lower flange 20f. However, in that case, in order to avoid interference with the web 20w, a pair of divided pieces 30d and 30d formed by dividing the reinforcing steel material 30 into two in the beam width direction are joined to the respective positions sandwiching the web 20w. Become. Further, as shown in FIG. 6, when the reinforcing steel material 30 (30d, 30d) is provided only on the lower surface of the upper flange 20f without providing the reinforcing steel material 30 on the upper surface of the upper flange 20f, the upper surface of the upper flange 20f. Can be made a flat surface without the reinforcing steel material 30, so that a floor material such as a deck plate can be easily placed on the upper flange 20f.

  FIG. 7A is an external perspective view of a modification of the present embodiment, and FIG. 7B is a top view thereof. In the above-described embodiment, the reinforcing steel material 30 is joined to the flange 20f of the beam 20, but in this modification, the reinforcing steel material 30 is joined to the web 20w of the beam 20 as shown in FIGS. 7A and 7B. Yes. And this point is mainly different from the above-described embodiment, and is otherwise substantially the same as the above-described embodiment.

  That is, in this modified example, the reinforcing steel material 30 is joined to the web 20w of the beam 20 so as to straddle the cross section sudden change position by the horizontal hunches 25, 25. It is shifted to the center in the span direction. More specifically, the sudden change position of the cross section is shifted to the position of the end 30ee on the center side in the span direction of the beam 20 in the reinforcing steel material 30. Therefore, the same effects as those of the above-described embodiment can be obtained.

Incidentally, the plastic section modulus Zp1 at the position of sudden change of the cross section when the reinforcing steel material 30 is joined to the web 20w in this way is given by, for example, the following formula 6. Note that the meaning of the symbol twp in Equation 6 is also shown in FIG. 5C.
Zp1 = B × tf × (d−tf)
+ (1/4) × (d−2 × tf) ² × (tw + twp) (6)
7A and 7B, as the reinforcing steel material 30, a rectangular steel plate having a long side in the height direction of the web 20w is joined and integrated to the web 20w of the beam 20 by whole-wall fillet welding. The planar shape and joining method are not limited to this, as in the case of the above-described embodiment.

  By the way, since the inventors of the present application have previously examined the effect of reducing the concentration of plastic strain at the point A at the position where the cross section suddenly changes by FEM (finite element method) analysis, the following Will be described.

  FIG. 8 shows a beam-column joint structure model used for the FEM analysis. In this analysis, the vicinity of the joint between the column 10 and the beam 20 is shown in the vertical direction, the span direction of the beam 20, and the beam width direction. Half of each of the three directions was taken out and divided into rectangular elements for modeling. Further, in order to simulate the action state of horizontal external force such as seismic force or wind load, an upward load P is applied to the center position in the span direction of the beam 20 to change the deformation angle R (= δ / L), The change of equivalent plastic strain at that time was analyzed. Note that δ and L related to the deformation angle R are the upper displacement δ of the center position and the distance L from the center position to the core of the column 10, respectively. Further, various specifications such as dimensions of the column 10, the beam 20, the horizontal hunch 25, and the reinforcing steel material 30 used for the analysis are also shown in FIGS. 8 and 9A to 9C.

  Although examination cases are shown in FIGS. 9A to 9C, three cases were examined. That is, as a comparative example, the reinforcing steel members 30 and 30 are provided for each of the flanges 20f and 20f as a case simulating the above embodiment as a case without the reinforcing steel members 30 of FIG. 9B, and the web reinforcement case of FIG. 9C in which the reinforcing steel material 30 is joined to the web 20w were studied as a case simulating the above modification.

  10A to 10C show analysis results when the deformation angle R = 0.02 (= 2%). In these figures, the magnitude (%) of the equivalent plastic strain is shown in shades, that is, a large equivalent plastic strain is generated in the dark portion, and a small equivalent plastic strain is generated in the thin portion. It shows that. 10A is an analysis result of the case without the reinforcing steel material, FIG. 10B is an analysis result of the flange reinforcement case, and FIG. 10C is an analysis result of the web reinforcement case. 10A to 10C are used for relative comparison among the three cases, and the shade scales (correspondence between shade and magnitude (%) of plastic strain) shown in the right part of each drawing are aligned with each other. Yes.

  On the other hand, FIGS. 11A to 11C show the same scale results as those shown in FIGS. 10A to 10C, which are individually scaled so that absolute evaluation can be performed for each case, as in FIGS. 10A to 10C. FIG. 11A shows the analysis result of the case without the reinforcing steel material, FIG. 11B shows the analysis result of the flange reinforcement case, and FIG. 11C shows the analysis result of the web reinforcement case.

  Referring to FIGS. 10A to 10C, compared with the case without the reinforcing steel material of FIG. 10A, in the flange reinforcing case of FIG. 10B and the web reinforcing case of FIG. And, it can be seen that the plastic strain spreads and distributes over a wide area around it. Therefore, if the reinforcing steel 30 is joined, it is possible to disperse the plastic strain over a wide range by applying a stress to the portion around the A point portion in a wide range, and the plastic strain at the A point portion is correspondingly increased. It was confirmed that the concentration of was reduced.

  In the flange reinforcing case of FIG. 10B, the plastic strain at the point A is greatly reduced. Further, referring to FIG. 11B in which the gray scale is individually adjusted, in this flange reinforcing case, a small plastic strain is present in the beam. It can be seen that they are distributed substantially uniformly and widely over the width direction. Therefore, it is thought that it is very effective to join the reinforcing steel material 30 to the flange 20f.

12A to 12C are graphs in which the equivalent plastic strain (%) generated at the point A portion of the lower flange 20f is arranged using the deformation angle R as a parameter.
Referring to these figures, compared with the case without reinforcing steel in FIG. 12A, the flange reinforcing case in FIG. 12B and the web reinforcing case in FIG. 12C have a point A over almost the entire range of the deformation angle R of 0 to 3%. It can be seen that the equivalent plastic strain in the portion is small. Therefore, it was confirmed that the concentration of the plastic strain at the point A can be reduced by joining the reinforcing steel material 30 to the flange 20f of the beam 20 or the web 20w.

  In particular, in the flange reinforced case of FIG. 12B, the size of the equivalent plastic strain is substantially halved over the substantially entire range of the deformation angle R of 0 to 3% compared to the case without the reinforced steel material of FIG. 12A. ing. Therefore, from the viewpoint of the effect of reducing the concentration of plastic strain at the point A, it is considered preferable to join the reinforcing steel material 30 to the flange 20f rather than the web 20w.

=== Other Embodiments ===
As mentioned above, although embodiment of this invention was described, this invention is not limited to this embodiment, The deformation | transformation as shown below is possible in the range which does not deviate from the summary.

  In the above-described embodiment, the H-shaped steel is used as the main body of the steel beam 20, but the present invention is not limited to this. For example, C-shaped cross-section grooved steel may be used as the main body of the beam 20, or a rectangular cross-section steel square pipe may be used as the main body.

  In the above-described embodiment, the reinforcing steel material 30 is exemplified as the reinforcing member. However, the reinforcing steel material 30 is not limited to this as long as the member can bear stress. For example, the reinforcing member may be made of a metal other than steel, or the reinforcing member may be formed of a non-metallic material such as resin, or a composite material such as FRP.

  In the above-described embodiment, a rectangular steel plate in a plan view is illustrated as the horizontal haunch 25, but the shape is not limited to a rectangular shape. For example, as shown in FIG. 13A, the corner portion of the horizontal haunch 25 cut out into a tapered shape may be used, or as shown in FIG. 13B, the corner portion of the horizontal haunch 25 cut out into a rectangular shape may be used. Further, as shown in FIG. 13C, a horizontal haunch 25 cut out by a circular hole may be used. Each of FIGS. 13A to 13C shows a sudden change position of each cross section (in each example, the position where the cross-sectional area increases discontinuously in a step shape is a sudden change position of the cross section) and plastic strain. The A point portion where the points are concentrated is shown.

  In the above-described embodiment, the horizontal hunches 25, 25,... Are provided on the H-shaped steel flanges 20f, 20f in order to make the end 20e of the beam 20 an increased cross-sectional area, but the present invention is not limited to this. For example, as shown in FIG. 14, the end 20 e of the beam 20 may be an increased cross-sectional area by providing a vertical haunch 26 on the H-shaped steel web 20 w. In the example of FIG. 14, the vertical haunch 26 is formed by a lower end of the web 20 w protruding downward toward the beam end 20 ee. In this case, the position of the end 26ee on the center side in the span direction of the beam 20 in the vertical haunch 26 is a sudden change position of the cross section, so that the reinforcing steel members 30 and 30 are connected to the flange 20f and the web 20w across the position. Are joined to at least one of them. In the example of FIG. 14, reinforcing steel materials 30 and 30 are joined to both the flange 20f and the web 20w, respectively.

  In the above-described embodiment, the end 20e of the beam 20 is joined by welding or the like to the upper and lower flanges 20f, 20f of the H-section steel, which are separate from the H-section steel forming the main body of the beam 20. However, the present invention is not limited to this, and the cross-sectional area increasing portion may be formed of a single member. For example, as shown in the schematic perspective view of FIG. 15, the flange width of the center side portion of the flange 20 f in the beam width direction is narrower than the end portion 20 e of the beam 20 in the span direction. If a part of both ends are cut out and reduced in width, a cross-sectional area increasing portion 20e made of a single member is formed at the end of the H-shaped steel.

1 column beam frame, 10 columns, 10s outer peripheral surface, 12 through diaphragm,
20 beam (steel beam), 20b reference section,
20e end (cross-sectional area increasing part), 20ee beam end,
20f flange, 20w web,
25 horizontal haunch, 25ee end, 26 vertical haunch, 26ee end,
30 Reinforced steel (reinforcing member), 30d Divided pieces,
30ee end,

Claims (5)

In a column beam connection structure in which a column and a steel beam are rigidly connected,
The steel beam has a reference cross-sectional portion having a reference cross-sectional shape of the steel beam, and a cross-sectional area having a cross-sectional area increased from the reference cross-sectional portion while being positioned closer to the end of the steel beam than the reference cross-sectional portion. An increase part,
The steel beam has an H-shaped steel as a main body,
The reference cross-sectional portion is located on the center side of the cross-sectional area increasing portion in the span direction of the steel beam, and is a portion of only the H-section steel,
The cross-sectional area increasing portion includes the H-section steel provided with the reference cross-sectional area portion and a haunch welded to the H-section steel, or a part of the H-section steel including the reference cross-sectional area portion. And a portion having a cross-sectional area larger than the reference cross-sectional portion,
A beam-to-column connection structure, wherein a reinforcing member is joined to the reference cross-section portion and the cross-sectional area increasing portion while straddling a boundary position between the reference cross-section portion and the cross-sectional area increasing portion. The beam-column joint structure according to claim 1 ,
A beam-column joining structure, wherein the reinforcing member is welded to a flange surface of the flange of the H-shaped steel . The beam-column joint structure according to claim 1 or 2 ,
A beam-column joining structure, wherein the reinforcing member is welded to a web surface of the H-shaped steel web. The beam-column joint structure according to any one of claims 1 to 3,
The steel beam has, as a dangerous cross-section position, a position where the entire cross-section yields first due to a bending moment generated with an increase in external force,
The column beam characterized in that, based on the joining of the reinforcing members, the dangerous cross-section position is shifted to a position on the center side in the span direction of the steel beam with respect to the boundary position related to the cross-sectional area increasing portion. Junction structure. The beam-column joint structure according to claim 4,
The magnitude of the bending moment acting on the position to be the critical cross-sectional position is M1, the magnitude of the bending moment acting on the boundary position is M2,
When the plastic section modulus at the position to be the critical section position is Zp1, and the plastic section coefficient at the boundary position in a state where the reinforcing member is joined is Zp2,
The column beam connection structure, wherein the reinforcing member is designed so that the ratio α (= (M1 / Zp1) / (M2 / Zp2)) is larger than 1.