Buckling restrained brace

Abstract

To provide a buckling restrained brace with an excellent earthquake energy absorption property for a core material.SOLUTION: A buckling restraint brace 60 includes: a steel plate-shaped core material 10; a pair of steel first restraint members 20 arranged to face two wide surfaces 11 of the core material 10; and a second restraint member 30 made of a square steel pipe surrounding the pair of first restraint members 20. A gap 40 having a difference value Δt between a width t1 between a pair of opposing inner walls 32 of the square steel pipe 30 and a total value t2 of a thickness t3 of the core material 10 and a height t4 in a thickness direction of the core material of the pair of first restraint members is provided inside the square steel pipe 30, a difference value Δt being set based on the height of a buckling wave of a higher mode in a weak axis direction of the core material 10.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a buckling restraint brace.

Background Art

[0002] Conventionally, as a brace for forming a building structure (column-beam structure, roof structure, etc.), a buckling restraint brace with buckling prevention measures has been applied. As the buckling restraint brace, there are various stiffening forms such as a form in which only a steel plate stiffens around a steel core material, a form in which RC (Reinforced Concrete) stiffens around a steel core material, and a form in which a steel core material is coated with steel and mortar.

[0003] Here, Patent Document 1 proposes a buckling restraint brace. This buckling restraint brace externally fits a first buckling restraint member made of a long rectangular metal cylinder to a long brace core material, and a long second buckling restraint member is interposed between the outer surface of the brace core material and the inner surface of the first buckling restraint member.

[0004] Both longitudinal ends of the brace core material protrude beyond both longitudinal ends of the first buckling restraint member and the second buckling restraint member, and the protruding portions at both longitudinal ends of the brace core material serve as connection portions for connecting to the structural members of the building. The second buckling restraint member has a cross-sectional groove shape, and the second buckling restraint member is interposed between both outer surfaces of the plate-shaped brace core material and one pair of opposing inner surfaces among the two pairs of opposing inner surfaces of the first buckling restraint member. The webs of the second buckling restraint members face both outer surfaces of the plate-shaped brace core material, and the tip portions of the flanges of the second buckling restraint members face one pair of opposing inner surfaces of the first buckling restraint member. The first buckling restraint member made of a rectangular metal cylinder has a deformed portion deformed inward by a pressing force from the outside toward the brace core material, and the deformed portion presses the first buckling restraint member against the brace core material via the second buckling restraint member.

Prior Art Documents

Patent Documents

[0005] Patent Document 1 Japanese Patent Application Laid-Open No. 2008-75281 SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0006] In the buckling restraint brace described in Patent Document 1, since a pair of wide surfaces of the core material are restrained in a state of being pressed by the webs of a pair of second buckling restraint members having a cross-sectional groove shape, there is a fear that the buckling deformation (higher-order buckling) of the higher-order mode in the weak axis direction (the direction orthogonal to the wide surface) of the core material is completely suppressed, and the earthquake energy absorption property of the core material is inhibited.

[0007] The present invention has been made in view of the above problems, and an object thereof is to provide a buckling restraint brace excellent in earthquake energy absorption property of a core material. MEANS FOR SOLVING THE PROBLEMS

[0008] In order to achieve the above object, one aspect of the buckling restraint brace according to the present invention is a buckling restraint brace having a steel plate-shaped core material, a pair of first restraint members made of steel disposed so as to face two wide surfaces of the core material, and a second restraint member made of a square steel pipe surrounding the pair of first restraint members, a gap of a difference value Δt between a width t1 between a pair of opposing inner walls of the square steel pipe, a thickness of the core material, and a total value t2 of heights in the thickness direction of the core material of the pair of first restraint members is provided inside the square steel pipe, and the difference value Δt is set based on a wave height of buckling of a higher-order mode in the weak axis direction of the core material.

[0009] According to this aspect, a gap of a difference value Δt between the width t1 between a pair of opposing inner walls of the second restraint member made of a square steel pipe and the total value t2 of the heights in the thickness direction of the core materials of the pair of first restraint members is provided inside the square steel pipe. Since the difference value Δt is set based on the height of the wave of buckling in the higher-order mode in the weak axis direction of the core material, there is no fear that the buckling in the higher-order mode in the weak axis direction of the core material will be completely suppressed. Therefore, it becomes a buckling restraint brace excellent in the earthquake energy absorption property of the core material.

[0010] Moreover, since the core material is restrained by a pair of first restraint members and a second restraint member made of a square steel pipe surrounding these, it becomes a buckling restraint brace in which buckling failure is effectively suppressed.

[0011] Here, the steel first restraint member may be a shaped steel material such as a channel steel, or may be a square steel pipe, a flat steel, or the like.

[0012] Also, another aspect of the buckling restraint brace according to the present invention is characterized in that a part or all of the gap is provided between one or both of the core material and the first restraint member and between the first restraint member and the second restraint member.

[0013] According to this aspect, since the gap is provided between the core material and the first restraint member, between the first restraint member and the second restraint member, or both, in any form, there is no fear that the buckling in the higher-order mode in the weak axis direction of the core material will be completely suppressed. Therefore, it becomes a buckling restraint brace excellent in the earthquake energy absorption property of the core material. In addition, when a gap is provided in either one of the core material and the first restraint member or between the first restraint member and the second restraint member, the width of the gap is set to the difference value Δt. When gaps (for example, a first gap and a second gap) are provided in both, the total of the widths of the first gap and the second gap is set to the difference value Δt.

[0014] Also, another aspect of the buckling restraint brace according to the present invention is characterized in that a gap adjusting liner is interposed in the gap.

[0015] According to this aspect, since the gap adjustment liner is interposed in the gap, when the width of the gap when assembling them is, for example, larger than the differential value Δt set in design due to lot differences or the like of the core material, the first restraint material, and the second restraint material, by disposing the gap adjustment liner in the gap, the width of the gap can be relatively easily adjusted to the differential value Δt.

[0016] Also, another aspect of the buckling restraint brace according to the present invention is characterized in that a protrusion protruding laterally from the wide surface of the core material is fitted into a groove provided in at least one of the first restraint materials, and mutual displacement prevention between the first restraint material and the core material is achieved.

[0017] According to this aspect, by fitting a protrusion protruding laterally from the wide surface of the core material into the groove provided in the first restraint material, mutual displacement between the first restraint material and the core material can be effectively prevented.

[0018] Also, another aspect of the buckling restraint brace according to the present invention is characterized in that the ends of the narrow openings of both the first restraint material and the second restraint material are joined to each other by welding, and mutual displacement prevention between the first restraint material and the second restraint material is achieved.

[0019] According to this aspect, since the ends of the narrow openings of both the first restraint material and the second restraint material are joined to each other by welding, mutual displacement between the first restraint material and the second restraint material can be effectively prevented.

Advantages of the Invention

[0020] As can be understood from the above description, according to the buckling restraint brace of the present invention, a buckling restraint brace excellent in earthquake energy absorption of the core material can be provided.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Mode for Carrying Out the Invention

[0022] Hereinafter, the buckling restraint brace according to the embodiment will be described with reference to the accompanying drawings. In the present specification and drawings, substantially the same components may be denoted by the same reference numerals, and redundant descriptions may be omitted.

[0023] [Buckling Restraint Brace According to the Embodiment] With reference to FIGS. 1 and 2, an example of the buckling restraint brace according to the embodiment will be described. Here, both FIGS. 1 and 2 are longitudinal cross-sectional views taken at an intermediate position in the longitudinal direction of an example of the buckling restraint brace according to the embodiment, cut in a direction orthogonal to the longitudinal direction.

[0024] The buckling restraint brace 60 includes a core material 10, a pair of first restraint materials 20 disposed so as to face two wide surfaces 11 of the core material 10, and a second restraint material 30 made of a square steel pipe that surrounds the pair of first restraint materials 20.

[0025] The core material 10 is formed of an elongated steel plate, and is preferably formed of a steel material with a low yield point such as an SN material (rolled steel for building structures) or an LYP material (extra-low yield point steel material). By applying the core material 10 made of these materials, the earthquake energy absorption performance due to the yield of the core material 10 is improved.

[0026] Furthermore, although not shown in the drawings, it is preferable that slits are provided on the wide surface 11 of the core material 10 so that the axial force adjustment (or load-bearing capacity adjustment) acting on the core material 10 can be made by these slits. Due to these slits, when the core material 10 receives an axial force (compressive force), buckling in the higher-order mode occurs effectively in the weak axis direction of the core material 10. Furthermore, while providing slits on the wide surface 11 of the core material 10, it is more preferable that by inserting spacers into the slits, it is possible to suppress a decrease in strength in the strong axis direction while adjusting the axial force of the core material 10.

[0027] Among one wide surface 11 of the core material 10, at, for example, the central position in the longitudinal direction, a steel columnar protrusion 15 shown by a one-dot chain line in FIG. 1 is fixed by welding or the like and protrudes laterally.

[0028] On the other hand, the first restraint member 20 is formed of a channel steel having a web 21 and a pair of flanges 22 that bend and rise at both ends of the web 21, and is arranged such that the web 21 faces the wide surface 11 of the core material 10. Here, the first restraint member may be formed of a square steel pipe, flat steel, or the like in addition to the channel steel in the illustrated example.

[0029] At, for example, the central position in the longitudinal direction of the web 21 of one first restraint member 20, a groove 25 shown by a one-dot chain line is provided, and by fitting the protrusion 15 of the core material 10 into the groove 25, mutual displacement prevention between the first restraint member 20 and the core material 10 is achieved.

[0030] Also, inside the second restraint member 30 made of a square steel pipe, the core material 10 and the pair of first restraint members 20 are accommodated without being joined to each other.

[0031] More specifically, substantially the entire area of the core material 10 and the pair of first restraint members 20 are not fixed to each other. The ends of the pair of first restraint members 20 and the second restraint member 30 are butt-welded or the like to prevent mutual displacement between the pair of first restraint members 20 and the second restraint member 30. And as described above, since the protrusion 15 is fitted into the groove 25 between one of the first restraint members 20 and the core material 10 to prevent mutual displacement, the core material 10, the pair of first restraint members 20, and the second restraint member 30 are substantially not fixed to each other in a posture where mutual displacement is prevented, and form a buckling restraint brace 60.

[0032] In the buckling restraint brace 60, the width between a pair of opposing inner walls 32 of the square steel pipe 30 is t1. Also, the thickness of the core material 10 is t3, and the height of the pair of first restraint members 20 in the thickness direction of the core material 10 is t4. Therefore, the total value t2 of the thickness of the core material 10 and the height of the pair of first restraint members 20 is t2 = t3 + 2×t4.

[0033] And in the buckling restraint brace 60 of the illustrated example, t1 is set to be larger than t2. Therefore, inside the second restraint member 30, a gap 40 with a difference value Δt of t1 - t2 is formed in the thickness direction of the core material.

[0034] Here, the gap 40 in the illustrated example is provided between the web 21 of one of the first restraint members 20 and one wide surface 11 of the core material 10. However, a first gap and a second gap (the sum of the widths of the first gap and the second gap is the difference value Δt) may be provided between both wide surfaces 11 of the core material 10 and both first restraint members 20, or a gap may be provided between the end 22a of the flange 22 of one or both of the first restraint members 20 and the inner wall 32 of the square steel pipe 30.

[0035] The difference value Δt (t1 - t2) corresponding to the width of the gap 40 is set based on the height of the wave of the higher-order mode buckling in the weak axis direction of the core material 10.

[0036] With this configuration, since there is no risk that the buckling of the higher-order mode in the minor axis direction of the core material 10 will be completely suppressed by the first restraint member 20 or the second restraint member 30, it becomes a buckling restraint brace 60 with excellent earthquake energy absorption performance of the core material 10.

[0037] Moreover, since the core material 10 is restrained by a pair of first restraint members 20 and a second restraint member 30 made of a square steel pipe surrounding them, it becomes a buckling restraint brace 60 in which buckling failure is effectively suppressed.

[0038] For example, when the gap 40 is set large, although the restraint effect of the peaks and valleys of the core material 10 that has buckled in the higher order in the minor axis direction (X1 direction) becomes small, it becomes difficult to suppress the plastic deformation of the core material 10 in the minor axis direction.

[0039] On the contrary, when the gap 40 is set small, although the restraint effect of the peaks and valleys of the core material 10 that has buckled in the higher order in the minor axis direction (X1 direction) becomes high, the plastic deformation of the core material 10 in the minor axis direction is easily suppressed.

[0040] Therefore, how much to restrain and plastically deform the core material 10 that has buckled in the higher order in the minor axis direction (what gap 40 with what difference value Δt to set) is a matter left to the designer.

[0041] As an example, after calculating the height of the wave of the buckling of the higher-order mode in the minor axis direction of the core material 10, the width of the gap (difference value Δt) can be set within a range of about 10 to 20% of the thickness of the core material 10. More specifically, when the thickness of the core material 10 is 10 mm, the width of the gap 40 (difference value Δt) can be set to about 1 to 2 mm.

[0042] FIG. 2 shows a modified example of the buckling restraint brace in the same manner as FIG. 1. The buckling restraint brace 60A shown in FIG. 2 is in a form in which a steel gap adjustment liner 50 is interposed in the gap 40A.

[0043] According to the buckling restraint brace 60A, since the gap adjustment liner 50 for 40A is interposed in the gap, when the width Δt' of the gap at the time of assembling them is, for example, larger than the differential value Δt set in design due to lot differences or the like of each of the core material 10, the first restraint material 20, and the second restraint material 30, by disposing the gap adjustment liner 50 having a thickness t5 in the gap, a gap 40A having a width of a desired differential value Δt can be formed relatively easily.

[0044] Therefore, when manufacturing the buckling restraint brace 60A, for example, a plurality of gap adjustment liners 50 having different thicknesses in mm units are prepared, and a suitable gap adjustment liner 50 is inserted into the gap according to the result of gap measurement to adjust the width of the gap, and it is preferable to manufacture the buckling restraint brace 60A.

[0045] In addition, other embodiments in which other components are combined or the like may be used for the configurations and the like described in the above embodiments, and the present invention is not limited to the configurations shown here at all. In this regard, it can be changed without departing from the gist of the present invention, and can be appropriately determined according to the application form.

Explanation of Reference Numerals

[0046] 10: Core material 11: Wide surface 15: Projection 20: First restraint material (grooved steel) 21: Web 21a: Side surface 22: Flange 22a: End face 25: Groove 30: Second restraint material (square steel pipe) 32: Inner wall 40, 40A: Gap 50: Gap adjustment liner 60, 60A: Buckling restraint brace

Claims

1. A buckling-restrained brace having a steel plate-shaped core material, a pair of first restraint materials made of steel disposed so as to face two wide surfaces of the core material, and a second restraint material made of a square steel pipe surrounding the pair of first restraint materials, wherein a gap of a difference value Δt between the width t1 between a pair of opposed inner walls of the square steel pipe and the total value t2 of the thickness of the core material and the height in the thickness direction of the core material of the pair of first restraint materials is provided inside the square steel pipe, and the difference value Δt is set based on the height of the wave of the buckling of the higher-order mode in the weak axis direction of the core material. The buckling-restrained brace is characterized by this.

2. The buckling-restrained brace according to claim 1, wherein part or all of the gap is provided between one or both of the core material and the first restraint material and between the first restraint material and the second restraint material.

3. The buckling-restrained brace according to claim 1 or 2, wherein a gap adjusting liner is interposed in the gap.

4. The buckling-restrained brace according to claim 1 or 2, wherein a protrusion protruding laterally from the wide surface of the core material is fitted into a groove provided in at least one of the first restraint materials, and mutual displacement prevention between the first restraint material and the core material is achieved.

5. The buckling-restrained brace according to claim 1 or 2, wherein the ends of the mouths of both the first restraint material and the second restraint material are joined to each other by welding, and mutual displacement prevention between the first restraint material and the second restraint material is achieved.

Images