Buckling-restrained brace and its manufacturing method

Abstract

To provide a buckling restraint brace with initial irregularity prevented or suppressed by suppressing welding strain with efficient welding, and a manufacturing method thereof.SOLUTION: A buckling restraint brace 100 includes: a plate-shaped steel core material 10; a pair of restraining materials 30 made of square steel pipe, in which the core material 10 has two wide surfaces 10a facing each other; an unbonded material 20 that is interposed between the core material 10 and the restraining materials 30; and a pair of stiffeners 50 that connect both sides of the pair of restraining materials 30 on the sides of the core material 10. The core material 10 is enclosed by the pair of restraining materials 30 and the pair of stiffeners 50, and at least the restraining materials 30 and the stiffeners 50 are connected via laser welding portions 60.SELECTED DRAWING: Figure 4

Description

Technical Field

[0005] ,

[0001] The present invention relates to a buckling restraint brace and a method for manufacturing the same.

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 bracing forms, such as a form in which the periphery of a steel core material is braced only with steel plates, a form in which the periphery of a steel core material is braced with RC (Reinforced Concrete), and a form in which the periphery of a steel core material is covered with steel materials and mortar.

[0003] Here, Patent Document 1 proposes a buckling restraint brace in which a core material is restrained by a restraint material formed of a pair of square steel pipes, and the buckling restraint brace that does not cause local failure in the restraint material receiving the pressing force from the core material. Specifically, it is a buckling restraint brace including a core material having joints for joining to other members at both ends of a plate-like portion, and restraint materials arranged to face each surface orthogonal to the weak axis direction of the plate-like portion. In this buckling restraint brace, both ends of the bracing material surrounding the core material are connected via welding portions by fillet welding.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] According to the buckling restraint brace described in Patent Document 1, it becomes easy to use members such as ready-made square steel pipes as the restraint material, and it is possible to suppress local failure of the restraint material receiving the pressing force from the core material without causing a cost increase.

[0006] Incidentally, in the buckling-restrained brace described in Patent Document 1, both ends of the stiffener are connected to the pair of restraint members surrounding the core material via welds formed by arc welding (fillet welding). As a result, a total of two long welds are required at both ends of one stiffener, and since two (a pair) of stiffeners are connected to the pair of restraint members, a total of four long welds are required. Therefore, this inherently involves the problem of a large amount of welding, and there is room for improvement regarding the amount of welding.

[0007] A large amount of welding naturally leads to longer welding times, and as a result, the constraining and stiffening materials are exposed to welding heat for a longer period, leading to greater welding distortion. For example, in cases where the cross-sections of the constraining and stiffening materials welded to each other are small, the effect of initial imperfections in buckling-restrained braces caused by welding distortion becomes greater.

[0008] This invention has been made in view of the above problems, and aims to provide a buckling-restrained brace in which welding distortion is suppressed by efficient welding and initial irregularities are suppressed or prevented, and a method for manufacturing the same. [Means for solving the problem]

[0009] To achieve the above objective, one embodiment of the buckling-restrained brace according to the present invention is: A steel, plate-shaped core material, A pair of restraining members made of rectangular steel pipes are arranged to face the two wide surfaces of the core material, An unbonded material interposed between the core material and the restraining material, The core material has a pair of stiffening members on its side, connecting both sides of the pair of restraining members. The core material is surrounded by the pair of restraining members and the pair of stiffening members. At least the restraining member and the stiffening member are connected via a laser-welded joint.

[0010] According to this embodiment, since at least the restraining member and the stiffening member are connected via a laser-welded joint, laser welding, which has a high energy density and excellent welding efficiency, can be applied, thereby suppressing welding distortion around the welded joint and resulting in a buckling-restrained brace in which initial imperfections are suppressed or prevented. This makes it possible to shorten the welding time, eliminate the need for correction when welding distortion occurs, and reduce the time required for spatter removal.

[0011] Furthermore, by applying laser welding, it becomes possible to make the thickness of the stiffener connected to the pair of restraining members as thin as possible. For example, when welding the end of a thin stiffener to a restraining member using conventional arc welding, the corners of the stiffener's end tend to melt down, so it is necessary to consider this melt-down when determining the thickness, which makes it difficult to reduce the thickness of the stiffener. However, with laser welding, there is no concern about such melt-down, so it becomes possible to make the stiffener as thin as possible while using the entire thickness of the plate as the leg length of the weld.

[0012] While laser welding technology has applications in other technical fields such as vehicle manufacturing, it has never been applied to the construction field. Therefore, its application to connecting the components of buckling-restrained braces is naturally a novel use.

[0013] Here, "at least the restraining member and the stiffening member are connected via a laser weld" means that there are two types of configurations: one in which only the restraining member and the stiffening member are connected via a laser weld, and the other configurations in which, in addition to the connection between the restraining member and the stiffening member, all other configurations are welded by laser welding.

[0014] In this embodiment, the unbonded material is made of an elastic material having deformation properties, such as butyl rubber. By interposing this unbonded material between the wide surface of the core material and the restraining material, the thickness of the unbonded material acts as a clearance, allowing higher-order mode buckling to occur within this clearance when the core material is subjected to compressive force. Furthermore, a slit may be provided on the wide surface of the core material to effectively induce higher-order mode buckling in its weak axis direction. Since providing a slit on the wide surface in this way weakens the strength of the core material in the strong axis direction, a spacer may be inserted into the slit on the wide surface as needed.

[0015] Furthermore, an intervening plate may be interposed between the unbonded material and the restraining material. In this configuration, by interposing, for example, a steel intervening plate between the unbonded material and the restraining material, the compressive force due to buckling of higher-order modes in the weak axis direction of the core material acts directly on the restraining material, effectively suppressing local failure of the restraining material.

[0016] Furthermore, other embodiments of the buckling-restrained brace according to the present invention include: The laser-welded portion is characterized in that it is located inside the end of the stiffening material.

[0017] According to this embodiment, since the restraining member and the stiffening member are connected via a laser-welded joint, the laser-welded joint can be set inward from the end of the stiffening member. This makes it possible to maximize the planar dimensions of the stiffening member, for example, by applying a stiffening member that extends to both ends or near the ends of a pair of restraining members, and then setting the laser-welded joint at an intermediate position within this wide stiffening member.

[0018] As the planar dimension of the stiffening member increases, the cross-sectional performance (sectional second moment of area) in both the weak axis direction and the strong axis direction of the core material increases, and both the out-of-plane and in-plane buckling resistance of the buckling-restrained brace improve. On the other hand, if the planar dimension of the stiffening member is large and its end is welded to the restraint material by arc welding, the distance from the center of the stiffening member (center of the core material) to the arc welding part will naturally become long, and the bending moment acting on the arc welding part will increase. Therefore, there is concern about the reduction in the strength of the arc welding part due to this bending moment. That is, in conventional arc welding or the like, since the end of the stiffening member becomes the welding location, due to the risk of damage caused by the bending moment of the arc welding part when the planar dimension of the stiffening member is increased, the planar dimension of the stiffening member cannot be increased. Therefore, it has been difficult to improve the buckling resistance against out-of-plane buckling in the weak axis direction of the buckling-restrained brace.

[0019] On the other hand, by providing a laser welding part at an intermediate position of the stiffening member, it becomes possible to suppress an increase in the bending moment acting on the welding part (laser welding part) while increasing the planar dimension of the stiffening member and enhancing the buckling resistance against out-of-plane buckling in the weak axis direction of the buckling-restrained brace.

[0020] Another aspect of the buckling-restrained brace according to the present invention is characterized in that the laser welding part is either in a linear continuous form or a linear intermittent form.

[0021] According to this aspect, since the laser welding part is linearly continuous or linearly intermittent, the restraint material and the stiffening member are connected in a low-strain manner along the longitudinal directions of both.

[0022] Another aspect of the buckling-restrained brace according to the present invention is characterized in that the laser welding part is a fiber laser welding part.

[0023] According to this aspect, since the laser welding part is a fiber laser welding part, among laser weldings, fiber laser welding has an even higher energy density, so the welding strain around the welding part is further suppressed, and the buckling restraint brace has an initial irregularity further suppressed or inhibited.

[0024] Also, in another aspect of the buckling restraint brace according to the present invention, At both ends of the core material, a pair of joint plates that are joined to other members perpendicular to the wide surface are fixed, A reinforcing plate is fixed to the pair of joint plates, and the end of the restraint material is housed in a space formed by the wide surface, the pair of joint plates, and the reinforcing plate.

[0025] According to this aspect, a pair of joint plates perpendicular to the wide surface are fixed at both ends of the core material, a reinforcing plate is fixed to the pair of joint plates, and the end of the restraint material is housed in a space formed by the wide surface, the pair of joint plates, and the reinforcing plate, so that a buckling restraint brace having a high-strength end structure is obtained. Here, examples of other members to which the joint plates are joined include connection fixtures such as brackets and gusset plates that project into the plane from the corners of the building structure. Also, when the end of the core material is used as a web, the pair of joint plates perpendicular to this web become a pair of flanges.

[0026] Also, one aspect of the manufacturing method of the buckling restraint brace according to the present invention is A pair of unbonded materials are abutted against two wide surfaces of a steel plate-shaped core material, the pair of unbonded materials are sandwiched by a pair of restraint materials made of square steel pipes, and on both sides of the pair of restraint materials on the side of the core material, they are connected by welding with a pair of supplementary stiffening materials. At this time, the welding is performed by laser welding.

[0027] According to this embodiment, by laser welding a pair of stiffening members to both sides of a pair of restraining members on the side of the core material, the two members can be connected under excellent welding efficiency. Since the welding speed is faster than arc welding, welding distortion around the weld can be suppressed, and a buckling-restrained brace can be manufactured in which initial irregularities are suppressed or prevented. [Effects of the Invention]

[0028] As can be understood from the above explanation, the buckling-restrained brace and its manufacturing method of the present invention provide a buckling-restrained brace in which welding distortion is suppressed by efficient welding and initial irregularities are suppressed or prevented. [Brief explanation of the drawing]

[0029] [Figure 1] This is an exploded perspective view of an example of a buckling-restrained brace according to an embodiment. [Figure 2] This is a longitudinal cross-sectional view perpendicular to the axis of the buckling-restrained brace according to the embodiment, before assembly. [Figure 3A] This is a perspective view showing a state in which a pair of stiffening members are connected to a pair of restraining members by an example of a laser weld. [Figure 3B] This is a perspective view showing a pair of stiffening members connected to a pair of restraining members by another example of a laser-welded joint. [Figure 4] This is a perspective view of an example of a buckling-restrained brace according to an embodiment. [Figure 5A] This is a longitudinal cross-sectional view of a conventional example in which a pair of stiffening members are connected to a pair of restraining members by an arc weld, and shows examples of the bending moment acting on the arc weld and the width of the stiffening members. [Figure 5B] This is a longitudinal cross-sectional view of an embodiment in which a pair of stiffening members are connected to a pair of restraining members by a laser weld, and shows examples of the bending moment acting on the laser weld and the width of the stiffening members. [Figure 6]This is a schematic longitudinal cross-sectional view of a buckling-restrained brace in the direction perpendicular to the axis, illustrating the state in which the compressive force during higher-order mode buckling acts from the core material to the restraining material. [Modes for carrying out the invention]

[0030] The buckling-restrained brace and its manufacturing method according to the embodiment will be described below with reference to the attached drawings. In this specification and drawings, substantially identical components may be denoted by the same reference numerals to avoid redundant explanations.

[0031] [Buckling-restrained brace according to an embodiment and its manufacturing method] An example of a buckling-restrained brace and its manufacturing method according to an embodiment will be described with reference to Figures 1 to 6. Here, Figure 1 is an exploded perspective view of an example of a buckling-restrained brace according to an embodiment, and Figure 2 is a longitudinal cross-sectional view of the end of the buckling-restrained brace according to an embodiment, perpendicular to the axis, in the state before assembly. Figures 3A and 3B are perspective views showing a state in which a pair of stiffening members are connected to a pair of restraining members by an example of a laser weld.

[0032] The buckling-restrained brace 100 comprises a core material 10, a pair of restraint members 30 arranged to face the two wide surfaces 10a of the core material 10, and an unbonded material 20 interposed between the core material 10 and the restraint members 30. In addition to the illustrated example, an interposition plate may be interposed between the unbonded material 20 and the restraint members 30.

[0033] The core material 10 is preferably made of steel with a low yield point, such as SN material (rolled steel for building structures) or LYP material (ultra-low yield point steel). By applying a core material 10 made of these materials, the seismic energy absorption performance due to yielding of the core material 10 is improved.

[0034] The core material 10 is formed from an elongated steel plate, and has a narrow section 11 at the center of its longitudinal direction where the width of the wide surface 10a is relatively narrow, and a wide section 12 at the end of its longitudinal direction where the width of the wide surface 10a is relatively wide.

[0035] The core material 10 has a narrow section 11 on its longitudinal central side and a wide section 12 on its longitudinal end side. This makes the narrow section 11 on the central side a region that is easily plasticized, and furthermore, the plasticization region can be limited to the narrow section 11 on the central side.

[0036] At the center of the narrow section 11 of the core material 10, cylindrical steel projections 15 protrude from the two wide surfaces 10a of the narrow section 11. The projections 15 are joined to the wide surfaces 10a of the narrow section 11 by welding or the like.

[0037] Furthermore, elongated slits 14 are provided on both sides of the projection 15 of the narrow portion 11 of the core material 10, and steel spacers 17 are inserted through the slits 14 in the X1 direction.

[0038] The slit 14 is a small hole for adjusting the load-bearing capacity of the core material 10, and the spacer 17 functions as an internal deformation prevention material that prevents the core material 10 from deforming inward (deformation in the strong axis direction) due to the presence of the slit 14. The spacer 17 inserted through the slit 14 is positioned by a pair of restraining members 30.

[0039] A pair of steel plates, each consisting of a connecting plate 13, are joined to the wide sections 12 at both ends of the core material by welding or other means, perpendicular to the wide surface 10a and connected to other members.

[0040] The wide section 12 and the connecting plate 13 are provided with bolt holes 12a and 13a, respectively, which are aligned with the bolt holes of connecting jigs (other members) such as brackets and gusset plates that protrude into the structural plane from corners of a building frame (not shown), and are bolted together.

[0041] A reinforcing plate 18 made of steel is joined to a pair of connecting plates 13 by welding or the like, and the end of the restraining member 30 is housed in the space formed by the wide portion 12 of the core material 10, the pair of connecting plates 13, and the reinforcing plate 18.

[0042] The unbonded material 20 is interposed between the narrow portion 11 of the core material 10 and the restraining material 30, and the thickness of the unbonded material 20 provides a clearance so that when the building frame deforms, a compressive force acts on the core material 10, causing buckling (wavy deformation) of a higher-order mode in the out-of-plane direction (weak axis direction) in the narrow portion 11.

[0043] For example, an elastic material such as butyl rubber can be used as the unbonded material 20. In addition, a projection hole 20a is provided at the center of the longitudinal direction of the unbonded material 20, into which the projection 15 of the core material 10 fits.

[0044] The restraining member 30 is formed from a rectangular steel pipe with a rectangular cross-section, and the side corresponding to the longer side of the rectangle is in contact with the unbonded material 20. The side of the restraining member 30 that is in contact with the unbonded material 20 is also provided with a projection hole 30a into which the projection 15 of the core material 10 fits.

[0045] On the side of the core material 10, a pair of stiffeners 50 made of steel plates connect both sides (the sides corresponding to the shorter sides of the rectangle) of a pair of restraining members 30 by welding or the like, and the core material 10 is surrounded by the pair of restraining members 30 and the pair of stiffeners 50.

[0046] As shown in Figures 3A and 3B, a pair of stiffening members 50 are connected to the left and right sides of a pair of restraining members 30 by laser-welded joints 60, 60A.

[0047] The example shown in Figure 3A is a configuration in which the restraining member 30 and the stiffening member 50 are connected by a linear, continuous laser weld 60 along the longitudinal direction of both members.

[0048] Since the laser-welded joint 60 can connect stacked members by irradiating various parts of the member with a laser, the weld can be placed at an intermediate position on the wide surface of the stiffener 50, as shown in the illustrated example, without the constraint that the weld is limited to the end of the stiffener, as in conventional arc welding. Therefore, the laser-welded joint 60 can be set at various positions on the wide surface of the stiffener 50, and its position can be adjusted as desired by the designer.

[0049] Because laser welding has a high energy density and excellent welding efficiency, it can significantly reduce welding time compared to general arc welding, etc., thereby suppressing welding distortion around the weld and reducing initial imperfections in the interconnected restraint material 30 and stiffener material 50.

[0050] In this case, it is preferable to use fiber laser welding, which has a significantly higher energy density among laser welding methods, and to connect the restraining member 30 and the stiffening member 50 via the fiber laser welded joint 60. By applying fiber laser welding, welding efficiency can be further increased, making it possible to further shorten the welding time and further suppress welding distortion.

[0051] When manufacturing the buckling-restrained brace 100, in addition to welding the restraining member 30 and the stiffening member 50 as shown in the illustrated example, laser welding may also be applied to the welding points between other members. By applying laser welding to the welding points between members in this way, welding time can be shortened, correction of welding distortion can be eliminated, and the time required for spatter removal can be reduced. As a result, the manufacturing efficiency of the buckling-restrained brace 100 can be significantly improved compared to when it is manufactured by conventional arc welding.

[0052] On the other hand, the example shown in Figure 3B is a configuration in which the two members are connected by linear, intermittent laser welds 60A along the longitudinal direction of the restraining member 30 and the stiffening member 50. It is preferable that fiber laser welding is also applied to these laser welds 60A.

[0053] According to the laser-welded section 60A, in addition to being able to connect the entire area of ​​the restraining material 30 and the stiffening material 50, the amount of welding can be reduced, making it possible to further suppress welding distortion.

[0054] At a minimum, a pair of restraining members 30 and a pair of stiffening members 50 are connected by a linear laser weld 60 (or laser weld 60A) to produce the buckling-restrained brace 100 shown in Figure 4.

[0055] Next, with reference to Figure 5, the structural performance effects of applying laser welding will be explained. Here, Figure 5A is a longitudinal cross-sectional view of a conventional example in which a pair of stiffeners are connected to a pair of restraining members by an arc weld, and shows examples of the bending moment acting on the arc weld and the width of the stiffeners. Figure 5B is a longitudinal cross-sectional view of an embodiment in which a pair of stiffeners are connected to a pair of restraining members by a laser weld, and shows examples of the bending moment acting on the laser weld and the width of the stiffeners.

[0056] As shown in Figure 5A, when a stiffener 50 is connected to a restraint member 30 by an arc weld AW, the end of the stiffener 50 becomes the arc weld AW. Therefore, when out-of-plane buckling in the weak axis direction acts on the buckling-restrained brace, if the length t1 from the axis of the stiffener 50 (the strong axis line shown in the figure) to the arc weld AW becomes long, there is a risk of damage to the arc weld AW due to the bending moment M1 acting on the arc weld AW.

[0057] Therefore, it is not possible to increase the length t1, and consequently, it is difficult to increase the width L1 of the stiffening member 50.

[0058] Furthermore, in arc welding, the corners at the ends of the stiffener 50 tend to melt down, so the thickness must be set to account for this melt-down, and therefore it becomes difficult to reduce the thickness of the stiffener 50.

[0059] In contrast, as shown in Figure 5B, by connecting the stiffener 50 to the restraint member 30 via the laser-welded joint 60, the laser-welded joint 60 can be set to a desired position inside the end of the stiffener 50 (a position at a length t2 from the axis of the stiffener 50). This eliminates the problem of the bending moment M2 acting on the laser-welded joint 60 becoming larger even when the width L2 of the stiffener 50 is increased, and prevents damage to the laser-welded joint 60 due to the bending moment M2.

[0060] Therefore, it becomes possible to increase the buckling resistance of the buckling-restrained brace 100 against out-of-plane buckling in the weak axis direction by increasing the width L2 (and planar dimensions) of the stiffener 50, while suppressing the increase in bending moment acting on the laser-welded joint 60 (achieving both).

[0061] Furthermore, since laser welding eliminates the concern of burn-through at the corners of the material that occurs with conventional arc welding, it becomes possible to minimize the thickness of the stiffening material 50 connected to the restraining material 30.

[0062] Next, with reference to Figure 6, we will explain the buckling of higher-order modes occurring in the strong axis direction of the core material 10.

[0063] The buckling-restrained brace 100 is incorporated into the building frame by bolting its ends to connecting fixtures provided at corners or other locations within the building frame. When the building frame deforms during an earthquake, external forces such as horizontal forces during the earthquake enter the ends of the buckling-restrained brace 100 via the connecting fixtures. These external forces are transmitted as compressive forces from the ends of the core material 10 to its entire surface, causing the entire core material 10 to undergo plastic deformation, thereby exhibiting its energy absorption performance during earthquakes.

[0064] In other words, when a compressive force is applied to the core material 10, buckling (wave-like deformation) of higher-order modes occurs in the strong axis direction throughout the entire core material 10. By causing the entire core material 10 to buckle as uniformly as possible, the overall plastic deformation performance of the buckling-restrained brace 100 can be achieved.

[0065] The compressive force acting on the core material 10 causes buckling in higher modes, and the peaks of the wave-like deformation due to buckling come into contact with the restraining material 30, thereby applying a pressing force Q to the stiffening material 50 as shown in Figure 6.

[0066] The local yield strength of the stiffening material 50 is set so that it does not suffer local failure under a locally acting compressive force Q.

[0067] Furthermore, other embodiments may be used in which other components are combined with the configurations listed in the above embodiments, and the present invention is not limited in any way to the configurations shown herein. In this regard, modifications can be made without departing from the spirit of the present invention, and can be appropriately determined according to the application form. [Explanation of Symbols]

[0068] 10: Core material 10a: Wide surface 11: Narrow section 12: Wide section 12a: Bolt hole 13: Joint plate 13a: Bolt hole 14: Slit 15: Protrusion 17: Spacer 18: Reinforcement plate 20: Unbonded material 20a:Protrusion hole 30: Retaining material (square steel pipe) 30a:Protrusion hole 50: Stiffener 60, 60A: Laser welded section (fiber laser welded section) 100: Buckling-restrained brace Q: Pressing force AW: Arc welding section

Claims

1. A steel, plate-shaped core material, A pair of restraining members made of rectangular steel pipes are arranged to face the two wide surfaces of the core material, An unbonded material interposed between the core material and the restraining material, The core material has a pair of stiffening members on its side, connecting both sides of the pair of restraining members. The core material is surrounded by the pair of restraining members and the pair of stiffening members. At least the restraining member and the stiffening member are connected via a laser welded joint, A buckling-restrained brace characterized in that the laser-welded portion is located inside the end of the stiffening material.

2. The buckling-restrained brace according to claim 1, characterized in that the laser-welded portion is either a linear continuous form or a linear intermittent form.

3. The buckling-restrained brace according to claim 1 or 2, characterized in that the laser-welded portion is a fiber laser-welded portion.

4. A pair of connecting plates are fixed to both ends of the core material, perpendicular to the wide surface, and joined to other members. A buckling-restrained brace according to any one of claims 1 to 3, characterized in that a reinforcing plate is fixed to the pair of connecting plates, and the end of the restraining member is housed in the space formed by the wide surface, the pair of connecting plates, and the reinforcing plate.

5. A method for manufacturing a buckling-restrained brace, A method for manufacturing a buckling-restrained brace, characterized by having a steel, plate-shaped core material, a pair of unbonded materials abutting against two wide surfaces of the core material, the pair of unbonded materials being sandwiched between a pair of restraining members made of square steel pipes, and welding both sides of the pair of restraining members together with a pair of stiffening members on the side of the core material, wherein the welding is performed by laser welding inside the ends of the stiffening members.

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