JP2017061837A - Reinforcement structure for one-side widened steel beam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reinforcement structure capable of reducing a decrease in bearing force of a one-sided widening steel beam according to the present invention.SOLUTION: A reinforcement structure 10 for a one-side widened steel beam comprises: a steel beam 20 which is formed of H-shaped steel having an upper flange part 22 and a lower flange part 24 positioned one over the other and a web part 26, and has ends 20E joined to a steel column 30 and the upper flange part 22 joined to a slab; a pair of widening parts 40 which are provided at the ends 20E and widen flange widths of the upper flange part 22 and lower flange part 24 projecting from the web part 26 toward one side; and a pair of end ribs 50 which couple at least one of the upper flange part 22 and slab to the lower flange part 24 so as to restrict the lower flange part 24 from being displaced.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a reinforcing structure for one-side widened steel beam.

  A steel beam formed of H-shaped steel, and a pair of widened portions provided at an end portion of the steel beam and extending the flange width of the upper flange portion and the lower flange portion projecting from the web portion of the end portion to one side; There is known a one-side widened steel beam provided with (for example, see Patent Document 1).

Japanese Patent Laid-Open No. 11-140978

  However, with a one-side widened steel beam, eccentric bending occurs at the end during an earthquake, so the proof stress may be reduced.

  The present invention has been made in consideration of the above facts, and an object thereof is to reduce the decrease in the proof stress of the one-side widened steel beam.

  The reinforcing structure of the one-side widened steel beam according to claim 1 is formed of an H-shaped steel having a pair of an upper flange portion and a lower flange portion, and a web portion, and an end portion is joined to a column, A pair of steel beams in which the upper flange portion is joined to a slab, and a pair of the upper flange portion and the lower flange portion, which are provided at the end portion of the steel beam and extend from the web portion to one side. And a displacement regulating member that couples at least one of the upper flange portion and the slab with the lower flange portion and restricts the displacement of the lower flange portion.

  According to the reinforcing structure of the one-side widened steel beam according to the first aspect, the end portion of the steel beam is joined to the column. A pair of widened portions that widen the flange width of the upper flange portion and the lower flange portion that project from the web portion of the steel beam to one side are provided at the ends of the steel beam.

  Here, when a positive bending moment acts on the steel beam during an earthquake, the steel flange beam material acts on the lower flange portion, while the upper flange portion exerts a compressive force in the axial direction of the steel beam. Axial tensile force acts. At this time, since the cross sections of the upper flange portion and the lower flange portion are decentered by the widened portion at the end of the steel beam, eccentric bending occurs. Accordingly, the upper flange portion is displaced to the other side of the web portion, and the lower flange portion is to be displaced to one side of the web portion.

  However, in the present invention, the upper flange portion is joined to the slab. For this reason, the upper flange portion is not displaced because it is restrained by the slab, and displacement occurs only in the lower flange portion. In this case, local plasticization occurs in the vicinity of the boundary portion between the widened portion and the other portion in the lower flange portion, so that the proof stress of the steel beam may be reduced.

  On the other hand, in the present invention, at least one of the upper flange portion and the slab and the lower flange portion are connected by the displacement regulating member. Thereby, the displacement to the one side of the web part of the lower flange part at the time of an earthquake is controlled. As a result, local plasticization that occurs in the vicinity of the boundary between the widened portion and the other portion in the lower flange portion described above is suppressed. Accordingly, a decrease in the proof stress of the steel beam is reduced.

  The reinforcing structure for one-side widened steel beam according to claim 2 is the reinforcing structure for one-side widened steel beam according to claim 1, wherein the displacement restricting member is provided between the upper flange portion and the lower flange portion. It is disposed and includes an end rib that is positioned on an end side opposite to the column in the widened portion in plan view and joined to the upper flange portion and the lower flange portion.

  According to the reinforcing structure of the one-side widened steel beam according to the second aspect, the end rib is disposed between the upper flange portion and the lower flange portion. The end ribs are located on the end side opposite to the pillars in the widened portion, and are joined to the upper flange portion and the lower flange portion, respectively. Thereby, the displacement to the one side of the web part of the lower flange part at the time of an earthquake is effectively controlled (suppressed).

  Therefore, as described above, since local plasticization that occurs in the vicinity of the boundary between the widened portion and the other portion in the lower flange portion is suppressed, the decrease in the proof stress of the steel beam is further reduced.

  The reinforcing structure for one-side widened steel beam according to claim 3 is the reinforcing structure for one-side widened steel beam according to claim 2, wherein the width of the widened portion is the end of the widened portion opposite to the column. A column-side rib that is gradually or gradually widened from the column to the column and is joined to at least one of the pair of widened portions on the column side with respect to the end rib.

  According to the reinforcement structure of the one-side widened steel beam according to the third aspect, the width of the pair of widened portions is gradually or gradually increased from the end of the widened portion opposite to the column toward the column. Therefore, local buckling tends to occur on the column side in the widened portion.

  As a countermeasure, in the present invention, the column side rib is provided on the column side of the end rib. The columnar rib is joined to at least one of the pair of widened portions. Thereby, the local buckling of at least one of a pair of wide part at the time of an earthquake is suppressed. Therefore, a decrease in the proof stress of the steel beam is further reduced.

  As described above, according to the reinforcing structure for one-side widened steel beam according to the present invention, it is possible to reduce the decrease in the proof stress of the one-side widened steel beam.

It is a perspective view which shows the one side widened steel beam to which the reinforcement structure of the one side widened steel beam which concerns on 1st Embodiment was applied. FIG. 4 is a sectional view taken along line 2-2 in FIG. 3. It is the upper side figure (plan view) which looked at the one side widened steel beam shown by FIG. 1 from the upper side. It is the bottom view which looked at the one side widened steel beam shown by FIG. 1 from the lower side. It is sectional drawing corresponding to FIG. 2 which shows the one side widened steel beam to which the modification of the reinforcement structure of the one side widened steel beam which concerns on 1st Embodiment was applied. It is sectional drawing corresponding to FIG. 2 which shows the one side widened steel beam to which the reinforcement structure of the one side widened steel beam which concerns on 2nd Embodiment was applied. (A) is the perspective view corresponding to FIG. 1 which shows the one side widened steel beam to which the reinforcement structure of the one side widened steel beam which concerns on 3rd Embodiment is applied, (B) is shown in FIG. 7 (A). It is the top view (plan view) which looked at the one side widened steel beam seen from the upper side. It is sectional drawing corresponding to FIG. 2 which shows the one side widened steel beam to which the modification of the reinforcement structure of the one side widened steel beam which concerns on 1st Embodiment was applied. It is a perspective view corresponding to FIG. 1 which shows the analysis model based on the Example used by FEM analysis. It is a graph which shows the analysis result obtained by FEM analysis. It is the bottom view which looked at the analysis model concerning the comparative example used by FEM analysis from the lower side.

  Hereinafter, a reinforcing structure for a one-side widened steel beam according to an embodiment of the present invention will be described with reference to the drawings.

  First, the first embodiment will be described.

(One side widened steel beam)
1 and 2 show a one-side widened steel beam 12 to which the reinforcing structure 10 for a one-side widened steel beam according to the present embodiment is applied. The one-side widened steel beam 12 is, for example, an outer peripheral beam disposed on the outer peripheral portion of the structure, and supports the exterior material 16 (see FIG. 2) and the like. The one-side widened steel beam 12 includes a steel beam 20, a pair of widened portions 40, and a pair of end ribs 50.

(Steel beam)
As shown in FIG. 2, the steel beam 20 is formed of H-shaped steel, and connects a pair of upper flange portion 22 and lower flange portion 24 to a pair of upper flange portion 22 and lower flange portion 24. And a web portion 26 that performs the same. The upper flange portion 22 and the lower flange portion 24 are disposed to face each other in the vertical direction (beam forming direction). Further, on the upper flange portion 22, for example, a reinforced slab slab 14 is provided. The slab 14 and the upper flange portion 22 are joined via a plurality of studs (not shown) provided on the upper surface of the upper flange portion 22.

  A web portion 26 is disposed between the upper flange portion 22 and the lower flange portion 24. The upper and lower end portions of the web portion 26 are joined to the center portions in the width direction of the upper flange portion 22 and the lower flange portion 24, respectively. Further, the upper flange portion 22 and the lower flange portion 24 project from the web portion 26 to both sides (the arrow W1 side and the arrow W2 side) of the web portion 26 in the plate thickness direction. The steel beam 20 is a so-called non-bracket type steel beam, and its end 20E is joined to the joint 30J of the steel column 30 by welding or the like at the site, for example.

  As shown in FIG. 1, the steel column 30 is formed of a square steel pipe. Note that the steel column 30 is not limited to a square steel pipe, and may be, for example, a round steel pipe, an H-shaped steel, or the like, or a CFT. A pair of diaphragms 32 is provided in the joint 30 </ b> J of the steel column 30. The pair of diaphragms 32 is, for example, a through diaphragm. The pair of diaphragms 32 are formed in a plate shape with a steel plate or the like, and are disposed to face each other in the material axis direction of the steel column 30.

  The pair of diaphragms 32 are joined by welding or the like in a state where the ends of the upper flange portion 22 and the lower flange portion 24 on the steel column 30 side are respectively abutted. Further, the end of the web portion 26 on the steel column 30 side is joined to the side surface 30S of the joint portion 30J by welding or the like. The web portion 26 of the steel beam 20 may be joined to the side surface 30S of the steel column 30 via a gusset plate, a bolt, and the like. Further, the pair of diaphragms 32 is not limited to a through diaphragm, and may be an inner diaphragm or an outer diaphragm.

(Widening part)
As shown in FIGS. 3 and 4, the end 20E of the steel beam 20 on the side of the steel column 30 has the flange width D of the upper flange 22 and the lower flange 24 at the end 20E of the web portion 26. A pair of widened portions 40 are provided that extend only to one side (the arrow W1 side, hereinafter also referred to as “the widened side”). The pair of widened portions (widened plates) 40 are formed in a plate shape from a steel plate or the like. The pair of widened portions 40 are formed in a triangular shape (right triangle shape) in plan view, and are arranged so that the width d gradually increases toward the steel column 30 side.

  The pair of widened portions 40 are respectively provided along end portions (tip portions) 22A and 24A on the distal side in the extending direction of the upper flange portion 22 and the lower flange portion 24 that extend from the web portion 26 to the widened side. Yes. In other words, the pair of widened portions 40 are provided along the end portions 22A and 24A along the longitudinal direction of the upper flange portion 22 and the lower flange portion 24, respectively.

  Further, the pair of widened portions 40 are joined by welding or the like in a state where each end portion 40A is abutted against the end portions 22A, 24A of the upper flange portion 22 and the lower flange portion 24, and the end portions 22A, 24A is extended to one side of the web part 26, respectively. Thereby, in the edge part 20E of the steel beam 20, the flange width D (including the widened part 40) of the upper flange part 22 and the lower flange part 24 is the end part on the opposite side to the steel column 30 in the pair of widened parts 40. It is gradually expanded from 40B toward the steel column 30. Further, the end portions 40C on the steel column 30 side of the pair of widened portions 40 are joined by welding or the like in a state of abutting against the pair of diaphragms 32, respectively.

  Here, as shown in FIG. 3, the steel beam 20 is arranged in a state of being brought closer to one side in the width direction of the steel column 30 (the side opposite to the widened side) with respect to the steel column 30. In other words, the material axis (column center) C2 of the steel column 30 is arranged at a position (a position away from) on the wide side from the material axis C1 of the steel beam 20. The end 20E of the steel beam 20 is joined to the steel column 30 in an eccentric state.

  As shown in FIG. 2, for example, an exterior material 16 is disposed on the side opposite to the widening side of the steel beam 20. The exterior material 16 is, for example, an outer wall material such as a concrete panel or a spun cleat panel, or various finishing materials. The exterior material 16 is attached to a plurality of brackets 18 provided on the upper flange portion 22. In addition, the attachment structure of the exterior material 16 with respect to the steel frame beam 20 can be changed suitably. Further, the upper widened portion 40 is joined to the slab 14 via, for example, a stud (not shown).

(End rib)
As shown in FIG. 3, a pair of end ribs 50 as a pair of displacement restricting members are provided on both sides of the web portion 26. The pair of end ribs 50 are formed in a plate shape from a steel plate or the like. The pair of end ribs 50 are disposed on both sides of the web portion 26 between the upper flange portion 22 and the lower flange portion 24 with the material axis direction (arrow X1, X2 direction) of the steel beam 20 as the plate thickness direction. Has been.

  In the pair of end ribs 50, the position of the steel beam 20 in the material axis direction is positioned on the end 40 </ b> B side opposite to the steel column 30 in the pair of widened portions 40. Here, the end 40B side of the pair of widened portions 40 is, for example, when the total length of the widened portion 40 (the length along the material axis direction of the steel beam 20) is L, It means a region of 0.25 L from the end 40B to both sides in the material axis direction of the steel beam 20 (a peripheral region of the end 40B).

  As shown in FIG. 2, the pair of end ribs 50 are joined to the lower surface of the upper flange portion 22, the upper surface of the lower flange portion 24, and the side surface of the web portion 26 by welding or the like. Accordingly, the upper flange portion 22 and the lower flange portion 24 are connected by the pair of end ribs 50, and the displacement of the web portion 26 of the lower flange portion 24 relative to the upper flange portion 22 in the plate thickness direction is restricted. .

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

  According to the reinforcing structure 10 for a one-side widened steel beam according to the present embodiment, the steel beam 20 is a non-bracket type steel beam, and its end 20E is welded to the joint 30J of the steel column 30 in the field. Joined by etc.

  Here, the positive bending moment acting on the steel beam 20 during an earthquake is maximized at both ends of the steel beam 20, that is, at the welded portion (joint portion) between the steel beam 20 and the steel column 30. On the other hand, quality control is often difficult for on-site welds (on-site welds). Therefore, at the time of an earthquake, the welded portion between the steel beam 20 and the steel column 30 is likely to be broken, and it may be difficult for the steel beam 20 to exhibit sufficient strength.

  In contrast, in the present embodiment, a pair of widened portions 40 is provided at the end 20E of the steel beam 20. By the pair of widened portions 40, the flange width D of the upper flange portion 22 and the lower flange portion 24 that project from the web portion 26 to one side (arrow W1 side) is widened. Thereby, since the cross-sectional area of the upper side flange part 22 and the lower side flange part 24 increases in the edge part 20E of the steel beam 20, the stress which acts on the welding part of the steel beam 20 and the steel column 30 is reduced.

  Further, as described above, the bending moment generated in the steel beam 20 at the time of the earthquake is maximized at the welded portion between the steel beam 20 and the steel column 30, and is on the center side (arrow X1 side) of the steel beam 20 in the material axis direction. It gets smaller as you go. On the other hand, in this embodiment, by providing the pair of widened portions 40 at the end 20E of the steel beam 20, the position where the plastic hinge is generated moves to the center side in the material axis direction of the steel beam 20. More specifically, the position where the plastic hinge is generated moves to the vicinity of the end 40 </ b> B opposite to the steel column 30 in the pair of widened portions 40. Thereby, a plastic hinge can be generated in the steel beam 20 at a position where the bending moment is smaller than the welded portion between the steel beam 20 and the steel column 30.

  Moreover, in general, in the joint portion (welded portion) between the steel beam 20 and the steel column 30, the cross-sectional area of the web portion 26 cannot be taken into account when calculating the bending strength of the steel beam 20. At a position away from the center side of the steel beam 20 (arrow X1 side), the bending strength of the steel beam 20 can be calculated in consideration of the cross-sectional area of the web portion 26. Therefore, the steel beam 20 can be easily designed.

  In the present embodiment, a pair of widened portions 40 is provided only on the upper flange portion 22 and the lower flange portion 24 that extend to one side of the web portion 26. And as FIG. 2 shows, the steel beam 20 is arrange | positioned in the state brought near to the one side (opposite side to the widening side) of the width direction of the steel column 30. As shown in FIG.

  Thereby, since the exterior material 16 can be arrange | positioned along the side surface of the steel beam 20 and the steel column 30 on the opposite side to the widening side in the steel beam 20, the bracket which protrudes from the steel beam 20 to the exterior material 16 side. The protrusion amount of 18 becomes short. Therefore, the size of the bracket 18 can be reduced, and the required number of brackets 18 can be reduced.

  Further, when the protruding amount of the bracket 18 becomes long, the torsional moment M generated around the material axis of the steel beam 20 due to the weight of the exterior material 16 becomes large. However, by shortening the protruding amount of the bracket 18, The torsional moment M can be reduced.

  Here, in the one-side widened steel beam 12, when a positive bending moment acts on the steel beam 20 during an earthquake, a compressive force in the material axis direction of the steel beam 20 acts on the upper flange portion 22, while A tensile force in the axial direction of the steel beam 20 acts on the side flange portion 24. At this time, since the cross sections of the upper flange portion 22 and the lower flange portion 24 are eccentric by the pair of widened portions 40 at the end portion 20E of the steel beam 20, an eccentric bending (eccentric bending moment) occurs. Therefore, as will be described in the FEM analysis described later, the upper flange portion 22 is displaced to the other side (arrow W2 side) of the web portion 26, and the lower flange portion 24 is moved to one side (arrow W1 side) of the web portion 26. Try to displace (see FIG. 11).

  However, in the present embodiment, the upper flange portion 22 is joined to the slab 14 (see FIG. 2). Therefore, the upper flange portion 22 is not displaced because it is restrained by the slab 14, and only the lower flange portion 24 is displaced to the other side of the web portion 26. For this reason, local plasticization is likely to occur near the boundary portion (near the end portion 40B) 24R between the widened portion 40 and other portions in the lower flange portion 24, and the proof stress of the steel beam 20 may be reduced.

  In addition, supplementing the eccentric bending, for example, as shown in FIG. 4, the lower flange portion 24 is provided with a tensile force S <b> 1 that acts on a portion where the widened portion 40 is not provided during an earthquake, and the widened portion 40. Deviation occurs in the tensile force S2 acting on the selected portion. The eccentric bending Q occurs in the lower flange portion 24 due to the displacement of the tensile forces S1 and S2.

  In contrast, in the present embodiment, the upper flange portion 22 and the lower flange portion 24 are connected by a pair of end ribs 50. Thereby, the displacement of the lower flange portion 24 is restrained by the slab 14 via the pair of end ribs 50 and the upper flange portion 22. Accordingly, the displacement of the lower flange portion 24 toward the wide side (arrow X1 side) at the time of the earthquake is restricted. As a result, local plasticization occurring in the vicinity of the boundary portion 24R of the lower flange portion 24 is suppressed. Therefore, a decrease in the proof stress of the steel beam 20 is reduced.

  Further, the pair of end ribs 50 are located on the end 40 </ b> B side opposite to the steel column 30 in the pair of widened portions 40. Thereby, the displacement of the wide side of the lower flange portion 24 is effectively regulated (suppressed). Therefore, as described above, since the local plasticization that occurs in the vicinity of the boundary portion 24R of the lower flange portion 24 is suppressed, the decrease in the proof stress of the steel beam 20 is further reduced.

  Further, the pair of end ribs 50 are provided on both sides of the web portion 26. Thereby, compared with the case where the edge part rib 50 is provided in the one side of the web part 26, the displacement to the wide side of the lower flange part 24 at the time of an earthquake is reduced. Therefore, a decrease in the proof stress of the steel beam 20 is further reduced.

  Next, a modification of the first embodiment will be described.

  In the said 1st Embodiment, although the edge part rib 50 was joined to the upper side flange part 22, the lower side flange part 24, and the web part 26, the said 1st Embodiment is not restricted to this. The end rib 50 may be joined to at least the upper flange portion 22 and the lower flange portion 24 to connect the upper flange portion 22 and the lower flange portion 24.

  In the first embodiment, the pair of end ribs 50 are provided on both sides of the web part 26 of the steel beam 20. However, the end ribs 50 may be provided only on one side of the web part 26.

  Moreover, in the said 1st Embodiment, although the edge part rib 50 was used as a displacement control member, the said 1st Embodiment is not restricted to this. As the displacement regulating member, for example, as shown in FIG. 5, a connecting plate 52 joined to the end portions 22B and 24B opposite to the widened side of the upper flange portion 22 and the lower flange portion 24 may be used. .

  Specifically, the connection plate 52 is formed in a plate shape with a steel plate or the like, and is disposed on the opposite side (arrow W2 side) of the web portion 26 to face the web portion 26. Further, the connecting plate 52 is positioned on the end 40B (see FIG. 3) side opposite to the steel column 30 in the pair of widened portions 40. The connecting plate 52 has an upper end joined to the end 22B of the upper flange 22 by welding or the like, and a lower end joined to the end 24B of the lower flange 24 by welding or the like.

  By connecting the upper flange portion 22 and the lower flange portion 24 by the connecting plate 52 in this manner, the displacement of the lower flange portion 24 toward the widening side during an earthquake is reduced. Therefore, the same effect as the first embodiment can be obtained.

  The connecting plate 52 may be provided on both sides of the web portion 26 or may be provided only on one side of the web portion 26.

  Moreover, in the said 1st Embodiment, although a pair of edge part rib 50 is located in the edge part 40B side on the opposite side to the steel pillar 30 in a pair of wide part 40, the said embodiment is not restricted to this. The positions of the pair of end ribs 50 in the material axis direction of the steel beam 20 can be changed as appropriate.

  Next, a second embodiment will be described. In the following description, members having the same configurations as those of the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  FIG. 6 shows a one-side widened steel beam 62 to which the reinforcing structure 60 for one-side widened steel beam according to the second embodiment is applied. The one-side widened steel beam 62 includes the steel beam 20, a pair of widened portions 40, and a pair of connecting members 70.

  The pair of connecting members 70 as the pair of displacement regulating members are formed of, for example, a steel plate or a shape steel. As in the first embodiment, the pair of connecting members 70 are disposed on both sides of the web portion 26 of the steel beam 20, and the end portions 40B on the opposite side of the steel pillar 30 in the pair of widened portions 40 (see FIG. 3) and is connected to the lower flange portion 24 and the slab 14.

  Specifically, the pair of connecting members 70 are inclined to the opposite sides toward the slab 14 from the lower flange portion 24, and each upper end portion passes through the outside of the upper flange portion 22 and reaches the slab 14. ing. A flange portion 72 is provided at the upper end portion of the connecting member 70. A plurality of studs 74 are provided on the upper surface of the flange portion 72. By embedding these studs 74 in the slab 14, the upper end portion of the connecting member 70 is joined to the slab 14. In addition, the joining method with the slab 14 of the connection member 70 can be changed suitably.

  On the other hand, the lower end portion of the connecting member 70 is joined to the lower flange portion 24 via the gusset plate 76. The gusset plate 76 is joined to the upper surface of the lower flange portion 24 and the side surface of the web portion 26 by welding or the like. The lower end portion of the connecting member 70 is joined to the gusset plate 76 by a bolt 78 and a nut (not shown). The pair of connecting members 70 restricts the displacement of the lower flange portion 24 toward the wide side.

  In addition, the joining method of the connection member 70 with respect to the lower flange part 24 can be changed as appropriate. For example, the connection member 70 may be joined to the lower flange part 24 by welding or the like.

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

  According to the present embodiment, the pair of connecting members 70 are disposed on both sides of the web portion 26 of the steel beam 20. The pair of connecting members 70 are located on the end 40B side opposite to the steel column 30 in the pair of widened portions 40, and connect the lower flange portion 24 and the slab 14.

  Thereby, the displacement to the wide side of the lower flange part 24 at the time of an earthquake is restrained (restricted) by the slab 14 via the pair of connecting members 70. As a result, as described above, local plasticization that occurs in the vicinity of the boundary portion 24R (see FIG. 4) between the widened portion 40 and the other portion in the lower flange portion 24 is suppressed. Therefore, a decrease in the proof stress of the steel beam 20 is reduced.

  The pair of connecting members 70 are positioned on the end 40 </ b> B side opposite to the steel column 30 in the pair of widened portions 40. Thereby, the displacement to the wide side of the lower flange part 24 is controlled effectively. Therefore, a decrease in the proof stress of the steel beam 20 is further reduced.

  Further, the pair of connecting members 70 are disposed on both sides of the web portion 26. By this pair of connecting members 70, the lower flange portion 24 and the slab 14 that extend from the lower end portion of the web portion 26 to both sides are connected to each other. Thereby, compared with the case where the connection member 70 is arrange | positioned only at the one side of the web part 26, the displacement to the wide side of the lower flange part 24 at the time of an earthquake is reduced more. Therefore, a decrease in the proof stress of the steel beam 20 is further reduced.

  Next, a modification of the second embodiment will be described.

  In the second embodiment, the pair of connecting members 70 are provided on both sides of the web portion 26. However, the second embodiment is not limited thereto. The connecting member 70 may be provided only on one side of the web portion 26. Moreover, as a connection member, not only a steel plate and a shape steel but linear members, such as a reinforcing bar, PC steel rod, a wire, may be sufficient, for example.

  Moreover, in the said 2nd Embodiment, although a pair of connection member 70 is located in the edge part 40B side on the opposite side to the steel pillar 30 in a pair of wide part 40, the said 2nd Embodiment is not restricted to this. The positions of the pair of connecting members 70 in the material axis direction of the steel beam 20 can be changed as appropriate.

  Further, the upper end side of the connecting member 70 may be joined to both the slab 14 and the upper flange portion 22. Further, the steel beam 20 may be provided with both the connecting member 70 and the end rib 50 (see FIG. 1) in the first embodiment. That is, the displacement regulating member can connect the lower flange portion 24 and at least one of the upper flange portion 22 and the slab 14.

  Next, a third embodiment will be described. In the following description, members having the same configurations as those of the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  FIGS. 7A and 7B show a one-side widened steel beam 82 to which the reinforcing structure 80 for one-side widened steel beam according to the third embodiment is applied. The one-side widened steel beam 82 includes a steel beam 20, a pair of widened portions 40, a pair of end ribs 50, and a column-side rib 84.

  The column side rib 84 is formed in a plate shape by a steel plate or the like, and is disposed between the pair of widened portions 40 with the material axis direction of the steel beam 20 being the plate thickness direction. Further, the column side rib 84 is disposed across the web portion 26 and the pair of widened portions 40. Further, the column side ribs 84 are disposed closer to the steel column 30 than the pair of end ribs 50.

  More specifically, the column-side ribs 84 are disposed on the steel column 30 side of the pair of end ribs 50 and at a portion where the width d of the pair of widened portions 40 is the widest. Further, the column-side rib 84 is disposed in the vicinity of the steel column 30. The column-side rib 84 is joined to the lower surface of the upper widened portion 40, the lower surface of the upper flange portion 22, the upper surface of the lower widened portion 40, the upper surface of the lower flange portion 24, and the side surface of the web portion 26 by welding or the like. Has been. The pillar-side ribs 84 impart rigidity (out-of-plane rigidity) to the pair of widened portions 40, the upper flange portion 22, and the lower flange portion 24.

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

  According to the present embodiment, the pair of widened portions 40 is provided at the end 20 </ b> E of the steel beam 20. By the pair of widened portions 40, the flange width D of the upper flange portion 22 and the lower flange portion 24 gradually increases from the end portion 40 </ b> B opposite to the steel column 30 in the pair of widened portions 40 toward the steel column 30. It has been spread.

  Here, when the flange width D of the upper flange portion 22 and the lower flange portion 24 is widened by the pair of widened portions 40, the stress acting on the welded portion between the steel beam 20 and the steel column 30 during an earthquake is reduced. Further, local buckling tends to occur in the pair of widened portions 40, the upper flange portion 22, and the lower flange portion 24, and the proof stress of the steel beam 20 may be reduced.

  On the other hand, in this embodiment, the column side rib 84 is provided between the pair of widened portions 40. The column side ribs 84 are disposed closer to the steel column 30 than the pair of end ribs 50. That is, the column side rib 84 is disposed at a position where the flange width D of the upper flange portion 22 and the lower flange portion 24 is widened. The column side ribs 84 are joined to the pair of widened portions 40, the upper flange portion 22, the lower flange portion 24, and the web portion 26, respectively. The pillar-side ribs 84 provide rigidity to the pair of widened portions 40, the upper flange portion 22, and the lower flange portion 24. Therefore, the pair of widened portions 40, the upper flange portion 22, and the lower flange portion 24 during an earthquake. The local buckling is suppressed. Since the upper widened portion 40 and the upper flange portion 22 are restrained by the slab 14, local buckling is less likely to occur compared to the lower flange portion 24.

  Further, as described above, the bending moment acting on the steel beam 20 at the time of an earthquake is maximized at the welded portion between the steel beam 20 and the steel column 30. Therefore, local buckling is likely to occur at the steel column 30 side portion of the pair of widened portion 40, upper flange portion 22, and lower flange portion 24.

  On the other hand, in this embodiment, the column side rib 84 is disposed in the vicinity of the steel column 30. Thereby, the local buckling of a pair of wide part 40, the upper side flange part 22, and the lower side flange part 24 is suppressed efficiently.

  In the present embodiment, the pair of widened portions 40 are connected to each other by the column side ribs 84. Thereby, the rigidity of a pair of widened part 40 is improved compared with the case where a pair of widened part 40 is stiffened by a separate pillar side rib, for example. Similarly, the upper flange portion 22 and the lower flange portion 24 are connected by the column side rib 84. Thereby, compared with the case where the upper flange part 22 and the lower flange part 24 are stiffened by separate column side ribs 84, the rigidity of the upper flange part 22 and the lower flange part 24 is enhanced. Therefore, local buckling of the pair of widened portion 40, upper flange portion 22, and lower flange portion 24 during an earthquake is further suppressed.

  Further, the column side rib 84 is also joined to the web portion 26. Thereby, the local buckling of the pair of widened portions 40, the upper flange portion 22, and the lower flange portion 24 is further suppressed, and the local buckling of the web portion 26 is also suppressed. Therefore, a decrease in the proof stress of the steel beam 20 is further reduced.

  Next, a modification of the third embodiment will be described.

  In the said 3rd Embodiment, although the column side rib 84 was each joined to a pair of wide part 40, the upper side flange part 22, the lower side flange part 24, and the web part 26, the said 3rd Embodiment is not restricted to this. The column side rib 84 only needs to be joined to at least one of the pair of widened portions 40. Further, separate pillar-side ribs may be joined to the pair of widened portions 40.

  Moreover, in the said 3rd Embodiment, although the column side rib 84 is arrange | positioned in the position where the width | variety d of a pair of wide part 40 is the widest, the said 3rd Embodiment is not restricted to this. For example, the column-side rib 84 may be disposed on the center side (arrow X1 side) of the steel beam 20 from the position shown in FIG. 7B.

  Next, a modification of the pair of widened portions will be described. In the following, various modified examples will be described by taking the first embodiment as an example, but these modified examples are also applicable to the second and third embodiments as appropriate.

  In the said 1st Embodiment, although the wide part 40 is formed in triangle shape by planar view, the shape of a wide part is not restricted to this. For example, as shown in FIG. 8, the widened portion 90 may be formed in a trapezoidal shape in plan view.

  Specifically, the widened portion 90 is formed in a rectangular shape with the material axis direction of the steel beam 20 as the longitudinal direction in plan view. The widened portion 90 has a cross section increasing portion 90G and a constant cross section 90H. The cross-section increasing portion 90G is formed in a triangular shape in plan view, and the width d1 is gradually increased from the end portion 90B opposite to the steel column 30 in the widened portion 90 toward the steel column 30. The constant cross section 90H is formed in a rectangular shape in plan view, and is disposed on the steel column 30 side of the cross section increasing portion 90G. The width d2 of the constant section 90H is constant. Here, the constant is a concept including a slight increase / decrease in the width d2 due to a manufacturing error or the like.

  Thus, the shape of the pair of widened portions can be changed as appropriate. Further, for example, in the modification shown in FIG. 8, the cross-section increasing portion 90 </ b> G can be omitted from the pair of widened portions 90. Furthermore, although illustration is omitted, for example, by forming the widened portion in a step shape, the width of the widened portion is gradually increased from the end of the widened portion opposite to the steel column 30 toward the steel column 30. You may do it.

  In the first embodiment, for example, the widened portion 90 is joined to the end portion 22A of the upper flange portion 22, but the upper flange portion 22 and the widened portion 90 may be cut out from a wide steel plate, for example. . In addition, for example, the widened portion can be provided in the upper flange portion 22 by joining the contact plate having the widened portion in a state of being superimposed on the upper flange portion 22. The same applies to the widened portion provided in the lower flange portion 24. Furthermore, the shape of the pair of widened portions may be the same or different.

  Next, the FEM analysis of the proof stress of the one side widened steel beam will be described.

(Analysis model)
FIG. 9 shows an analysis model of the one-side widened steel beam 100 and the steel column 30 according to the embodiment. The one-side widened steel beam 100 has the same configuration as the one-side widened steel beam 12 according to the first embodiment except that the shape of a pair of widened portions (the widened portion 40 and the widened portion 90) is different.

  In this analysis, as Comparative Example 1, an analysis model of the one-side widened steel beam 110 (see FIG. 11) in which the pair of end ribs 50 is omitted from the one-side widened steel beam 100 (see FIG. 9) according to the example is used. It was. Furthermore, as Comparative Example 2, wide portions were respectively provided on the upper flange portion and the lower flange portion extending from the web portion of the steel beam to both sides, and the steel column material axis was disposed on the steel beam material axis. An analytical model of double-side widened steel beams (not shown) was used.

(analysis method)
In this analysis, as shown in FIG. 9, both the upper and lower end portions 30U and 30L of the steel column 30 and the both sides (arrow W1 and arrow W2) of the web portion 26 of the upper flange portion 22 of the steel beam 20 in the plate thickness direction. In a state in which the displacement is set to be fixed (displacement in the material axis direction of the steel beam 20, displacement in the material axis direction of the steel column 30, and rotational deformation are in an unconstrained state), a predetermined value on the center side in the material axis direction of the steel beam 20 A vertically upward load F was input to the position, and the relationship between the load F (shearing force) and the displacement of the steel beam 20 at the input position of the load F was graphed (see FIG. 10).

(Analysis result)
FIG. 10 shows graphs J, K1, and K2 showing the analysis results of the example, comparative example 1, and comparative example 2, respectively. Comparing these graphs J, K1, and K2, it can be seen that the proof stress and rigidity of the graph K2 (analytical model of both-side widened steel beam according to Comparative Example 2) are the highest. However, in the analytical model of the both-side widened steel beam according to Comparative Example 2, since the widened portion is provided on both sides of the web portion, the fitting with the above-described exterior material 16 (see FIG. 2) may be deteriorated.

  Next, in FIG. 10, it turns out that the yield strength and rigidity of graph K1 (analysis model of the one side widened steel beam 110 which concerns on the comparative example 1) become the lowest. Here, FIG. 11 shows a bottom view showing the analysis result of the deformation state of the one-side widened steel beam 110 according to the comparative example 1 to which the load F is inputted. As shown in FIG. 11, in the one-side widened steel beam 110, the lower flange portion 24 moves toward the widened side (arrow W <b> 1 side) with respect to the upper flange portion 22 due to the eccentric bending generated at the end 20 </ b> E of the steel beam 20. It can be seen that it is displaced. In FIG. 11, the upper flange portion 22 is indicated by a solid line, and the lower flange portion 24 is indicated by a two-dot chain line.

  Further, when the stress distribution in the deformed state of the lower flange portion 24 shown in FIG. 11 is analyzed, local plasticization occurs in the vicinity of the boundary portion 24R between the widened portion 90 and other portions in the lower flange portion 24. I understand. From this, in the one side widened steel beam 110 which concerns on the comparative example 1, it is thought that yield strength and rigidity fell rather than the both-side widened steel beam which concerns on the comparative example 2 like the graph J1 of FIG.

  On the other hand, as shown in the graph J of FIG. 10, the proof stress and the rigidity of the analytical model of the one-side widened steel beam 100 according to the example are from the analytical model (graph K2) of the double-side widened steel beam according to the comparative example 2. Although it is low, it turns out that it becomes higher than the analytical model (graph K1) of the one side widened steel beam 100 concerning the comparative example 1. FIG. This is because in the analysis model of the one-side widened steel beam 100 according to the embodiment, the displacement of the lower flange portion 24 toward the widened side is restricted by the pair of end ribs 50, and the boundary portion of the lower flange portion 24 described above. This is probably because local plasticization occurring in the vicinity 24R is suppressed.

  As mentioned above, although one embodiment of the present invention was described, the present invention is not limited to such an embodiment, and one embodiment and various modifications may be used in combination as appropriate, and the gist of the present invention will be described. Of course, various embodiments can be implemented without departing from the scope.

10 One-side widened steel beam reinforcement structure 14 Slab 20 Steel beam 20E End (end of steel beam)
22 Upper flange portion 24 Lower flange portion 26 Web portion 30 Steel column (column)
40 Widened portion 40B End (end of the widened portion opposite to the column)
50 End rib (displacement regulating member)
52 Connection plate (displacement regulating member)
60 One-side widened steel beam reinforcement structure 70 Connecting member (displacement regulating member)
80 One-side widened steel beam reinforcement structure 84 Column-side rib 90 Widened portion 90B End (end of the widened portion opposite to the column)
100 One side widened steel beam D Flange width

Claims (3)

A steel beam having a pair of upper flange portion and lower flange portion, and a web portion, formed of H-shaped steel, the end portion being joined to a column, and the upper flange portion being joined to a slab,
A pair of widened portions provided at the end of the steel beam and extending the flange width of the upper flange portion and the lower flange portion projecting from the web portion to one side;
A displacement regulating member that connects at least one of the upper flange part and the slab and the lower flange part, and regulates displacement of the lower flange part;
Reinforced structure of one side widened steel beam. The displacement restricting member is disposed between the upper flange portion and the lower flange portion, and is located on an end side opposite to the column in the widened portion in a plan view, and the upper flange portion And an end rib joined to the lower flange portion,
The reinforcing structure of the one-side widened steel beam according to claim 1. The width of the widened portion is gradually or stepwise widened from the end of the widened portion opposite to the column toward the column,
Column side ribs joined to at least one of the pair of widened portions are provided on the column side with respect to the end ribs.
The reinforcement structure of the one-side widened steel beam according to claim 2.