Buckling-restrained brace

Abstract

To provide a buckling restraint brace capable of suppressing the decrease in buckling strength against out-of-plane buckling while reducing the amount of welding when weld-connecting a restraining material and a stiffener.SOLUTION: A buckling restraint brace includes: a plate-shaped steel core material 10; a pair of restraining materials 30 consisting of channel steel, which are arranged so that a web is in contact with two wide surfaces 10a of the core material 10; a pair of stiffeners 50 made of angle iron that is arranged to surround the core material 10 and the restraining materials 30; and an unbonded material 20 interposed between the core material 10 and the restraining materials 30, and both adjacent end regions 60 of the pair of stiffeners 50 are welded together.SELECTED DRAWING: Figure 3

Description

Background Art

[0002]

[0001] Conventionally, as braces for forming building frameworks (column and beam frameworks, roof frameworks, etc.), buckling-restrained braces with buckling prevention measures have been applied. As buckling-restrained braces, 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 coated with steel and mortar.

[0002] Here, Patent Document 1 proposes a buckling-restrained brace in which a core material is restrained by a restraining material formed of a pair of square steel pipes, and the buckling-restrained brace does not cause local failure in the restraining material that receives a pressing force from the core material. Specifically, it is a buckling-restrained brace including a core material having joints for joining to other members at both ends of a plate-shaped portion, and restraining materials arranged to face each surface orthogonal to the weak axis direction of the plate-shaped portion. In this buckling-restrained brace, both ends of a bracing member are connected to a pair of restraining materials surrounding the core material through welded portions by fillet welding.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] According to the buckling-restrained brace described in Patent Document 1, it becomes easy to use members such as ready-made square steel pipes as restraining materials, and it is possible to suppress local failure of the restraining material that receives a pressing force from the core material without causing high costs.

[0005] Incidentally, in the buckling-restrained brace described in Patent Document 1, both ends of the stiffener are connected to a 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 a 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. Due to the large amount of welding, the welding time is naturally longer, and as a result of the restraint members and stiffeners being exposed to welding heat for a longer time, welding distortion also increases.

[0006] Furthermore, for buckling-restrained braces with relatively low axial forces applied to typical houses, commercially available square steel pipes of the aforementioned size do not exist. Therefore, when using commercially available square steel pipes, slitting or other processing is required to reduce the cross-sectional area of ​​the core material, which ultimately leads to increased manufacturing costs.

[0007] Therefore, as an alternative configuration, channel steel is used as the restraining material instead of square steel pipes, and a stiffening material is connected to the pair of channel steels via fillet welds while a core material is sandwiched between the two channel steels. However, even with this configuration, a total of two long welds are required at both ends of one stiffening material, and since two (a pair) of stiffening materials are connected to a pair of restraining materials, a total of four long welds are required, so it is not possible to reduce the amount of welding. Furthermore, in this alternative configuration, since channel steel is used as the restraining material, one less steel plate is needed compared to square steel pipes, and since the opening of the channel steel is located at the weak axis end of the buckling-restrained brace, the cross-sectional performance (second moment of area) in the weak axis direction becomes smaller, which may lead to a decrease in the buckling resistance of the buckling-restrained brace against out-of-plane buckling in the weak axis direction.

[0008] This invention has been made in view of the above problems, and aims to provide a buckling-restrained brace that reduces the amount of welding at the welded joint connecting the restraining member and the stiffening member, while suppressing the reduction in buckling resistance against out-of-plane buckling. [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 channel steel are arranged so as to bring the web into contact with the two wide surfaces of the core material, A pair of stiffening members made of angle steel are arranged to surround the core material and the restraining material, The system includes an unbonded material interposed between the core material and the restraining material, The pair of stiffeners are characterized in that their adjacent end regions are welded together.

[0010] According to this embodiment, the structure has a pair of restraint members made of channel steel and a pair of stiffener members made of angle steel arranged to surround the core material and the restraint members. The adjacent end regions of the pair of stiffener members are welded together, so that there are only two welds connecting the pair of stiffener members, and the amount of welding can be significantly reduced compared to the four welds described above.

[0011] Furthermore, by using channel steel as the restraining material while having a configuration in which a pair of restraining materials are completely surrounded by a pair of angle steel, it becomes possible to change the restraining material from the above-mentioned square steel pipe to channel steel, thereby preventing an increase in manufacturing costs in the production of relatively low-axial-force buckling-restrained braces applicable to general houses, while suppressing a decrease in the cross-sectional performance (second moment of area) in the weak axis direction, and thus suppressing a decrease in the buckling resistance of the buckling-restrained brace against out-of-plane buckling in the weak axis direction.

[0012] 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.

[0013] 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.

[0014] Furthermore, other embodiments of the buckling-restrained brace according to the present invention include: The end faces of both stiffening members are welded together.

[0015] According to this embodiment, by welding the corresponding end faces of a pair of stiffeners together, a buckling-restrained brace can be formed in which the core material and a pair of restraint members are surrounded by a pair of stiffeners made of angle steel.

[0016] Furthermore, other embodiments of the buckling-restrained brace according to the present invention include: The end face of one stiffening member and the side surface of the other stiffening member are welded together.

[0017] According to this embodiment, a buckling-restrained brace can be formed in which a core material and a pair of restraining members are surrounded by a pair of stiffening members made of angle steel, by welding the end face of one stiffening member to the side surface of the other stiffening member.

[0018] Furthermore, in other embodiments of the buckling-restrained brace according to the present invention, The angle steel has a curvature surface inside its bent portion, the length of the web of the channel steel is set shorter than the width of the core material, and in a posture where the channel steel is surrounded by the angle steel, the end of the channel steel does not interfere with the curvature surface. This is a characteristic feature.

[0019] According to this aspect, by setting the length of the web of the channel steel shorter than the width of the core material, in a posture where the channel steel is surrounded by the angle steel, it is possible to configure such that the end of the channel steel does not interfere with the curvature surface provided in the angle steel.

[0020] Further, in another aspect of the buckling restraint brace according to the present invention, the angle steel has a curvature surface inside its bent portion, among the channel steel, the end face of the flange at a position corresponding to the curvature surface is a tapered surface, and in a posture where the channel steel is surrounded by the angle steel, the end of the channel steel does not interfere with the curvature surface. This is a characteristic feature.

[0021] According to this aspect, among the channel steel, by making the end face of the flange at a position corresponding to the curvature surface provided in the angle steel a tapered surface, in a posture where the channel steel is surrounded by the angle steel, it is possible to configure such that the end of the channel steel does not interfere with the curvature surface provided in the angle steel.

[0022] Further, 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-width surface are fixed, a reinforcing plate is fixed to the pair of joint plates, and the ends of the restraint material and the supplementary rigid material are accommodated in the space formed by the wide-width surface, the pair of joint plates, and the reinforcing plate. This is a characteristic feature.

[0023] According to this aspect, a pair of joint plates perpendicular to the wide-width surface are fixed at both ends of the core material, a reinforcing plate is fixed to the pair of joint plates, and the end portion of the restraint material is accommodated in the space formed by the wide-width surface, the pair of joint plates, and the reinforcing plate, thereby becoming a buckling restraint brace having a high-strength end structure. 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 corner portions of the building structure. Further, when the end portion of the core material is used as a web, the pair of joint plates perpendicular to this web become a pair of flanges.

Effects of the Invention

[0024] As can be understood from the above description, according to the buckling restraint brace of the present invention, it is possible to provide a buckling restraint brace in which the reduction in buckling strength against out-of-plane buckling is suppressed while reducing the welding amount of the welded portion connecting the restraint material and the stiffening material.

Brief Description of the Drawings

[0025] [Figure 1] It is an exploded perspective view of an example of the buckling restraint brace according to the embodiment. [Figure 2] It is a longitudinal sectional view in the direction perpendicular to the axis of the buckling restraint brace according to the embodiment. [Figure 3] It is a perspective view of an example of the buckling restraint brace according to the embodiment. [Figure 4] It is a longitudinal sectional view in the direction perpendicular to the axis of a conventional buckling restraint brace.. [Figure 5] It is a longitudinal sectional view in the direction perpendicular to the axis of a modified example of the buckling restraint brace according to the embodiment. [Figure 6] It is a schematic longitudinal sectional view in the direction perpendicular to the axis of the buckling restraint brace for explaining the state in which a pressing force acts on the restraint material during buckling in a higher-order mode.

Modes for Carrying Out the Invention

[0026] The buckling-restrained brace 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.

[0027] [Buckling-restrained brace according to an embodiment] An example of a buckling-restrained brace according to the 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 the embodiment, and Figure 2 is a longitudinal cross-sectional view of the buckling-restrained brace according to the embodiment in the direction perpendicular to the axis. Figure 3 is a perspective view of an example of a buckling-restrained brace according to the embodiment.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] The restraining member 30 is formed from channel steel, and the unbonded material 20 abuts against the web of the channel steel in the X2 direction. The web of the restraining member 30 that abuts against the unbonded material 20 is also provided with projection holes 30a into which the projections 15 of the core material 10 fit.

[0041] A pair of stiffeners 50 made of angle steel are arranged around a pair of restraint members 30 that sandwich the core material 10 from above and below, and the end regions of both angle steels 50 are welded together so that the core material 10 and the pair of restraint members 30 are surrounded by the pair of stiffeners 50, forming a buckling-restrained brace 100 as shown in Figures 2 and 3.

[0042] As shown in Figure 2, at two end regions 60 of the pair of stiffeners 50, the end face 51 of one stiffener 50 and the side surface 52 of the other stiffener 50 are joined via a weld Y.

[0043] The bent portion of the stiffener 50, which is formed from angle steel, has a curved surface 53. Therefore, in order to prevent the ends of the pair of restraining members 30, which are housed inside the pair of stiffeners 50, from interfering with the curved surface 53 of the stiffeners 50, the width of the web of the restraining member 30 is set to be shorter than the width of the flange or core material 10 of the stiffener 50.

[0044] To compare with the buckling-restrained brace 100, Figure 4 shows a longitudinal cross-sectional view of a conventional buckling-restrained brace in the direction perpendicular to the axis.

[0045] Conventional buckling-restrained braces 100' have a configuration in which a pair of stiffeners 50' made of steel plates are connected to a pair of restraint members 30' made of square steel pipes via a welded joint Y.

[0046] As already explained, in the case of the buckling-restrained brace 100' with relatively low axial force that is applied to general houses, there are no commercially available square steel pipes of the size described above. Therefore, when using commercially available square steel pipes, it is necessary to perform slitting or other processing to reduce the cross-section of the core material 10, which leads to increased manufacturing costs.

[0047] Furthermore, if the width L of the pair of stiffeners 50' is increased to raise the overall rigidity of the buckling-restrained brace 100', the increased width of the stiffeners 50' leads to a larger displacement δ in the strong axis direction, and the out-of-plane bending rigidity of the stiffeners 50' decreases, which is undesirable.

[0048] In contrast, the buckling-restrained brace 100 shown in Figure 2 is made of channel steel, which makes it possible to accommodate buckling-restrained braces with relatively low axial forces that are applied to general houses. In addition, although the restraining member 30 is made of channel steel, it is surrounded by a pair of stiffeners 50 made of angle steel, which suppresses the decrease in the cross-sectional performance (second moment of area) of the buckling-restrained brace 100 in both the strong axis direction and the weak axis direction, thereby suppressing the decrease in buckling resistance against out-of-plane buckling.

[0049] Furthermore, regarding the amount of welding between the restraining member and the stiffening member, the buckling-restrained brace 100' shown in Figure 4 requires a total of four long welds Y, whereas the buckling-restrained brace 100 shown in Figure 2 requires only two long welds Y. This significantly reduces the amount of welding and also helps to mitigate the effects of welding strain.

[0050] Next, with reference to Figure 5, a modified example of the buckling-restrained brace according to the embodiment will be described. Here, Figure 5 is a longitudinal cross-sectional view perpendicular to the axis of a modified example of the buckling-restrained brace according to the embodiment.

[0051] The buckling-restrained brace 100A differs from the buckling-restrained brace 100 in that the end faces 51 and side faces 52 are connected via a weld Y, in which the end faces 51 and side faces 52 are connected via a weld Y.

[0052] In the buckling-restrained brace 100A, the bent portion of the stiffener 50, which is made of angle steel, has a curved surface 53. Here, the end faces of the pair of restraint members 30 housed inside the pair of stiffener members 50, the ends corresponding to the curved surface 53, are tapered surfaces 31, thereby preventing interference with the curved surface 53 of the stiffener members 50.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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 stiffener 50, thereby applying a pressing force Q to the stiffener 50 as shown in Figure 6.

[0057] 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.

[0058] 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]

[0059] 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: Restraint material (channel steel) 31: End face (tapered surface) 30a:Protrusion hole 50: Stiffener (angle steel) 51: End face 52: Side view 53: Curvature surface 60: End area 100,100A: Buckling-restrained brace Y: Welded section Q: Pressing force

Claims

1. A steel, plate-shaped core material, A pair of restraining members made of channel steel are arranged so as to bring the web into contact with the two wide surfaces of the core material, A pair of stiffening members made of angle steel are arranged to surround the core material and the restraining material, The system includes an unbonded material interposed between the core material and the restraining material, The adjacent end regions of the pair of stiffeners are welded together. The angle steel has a curved surface on the inside of its bent portion. A buckling-restrained brace characterized in that the length of the web of the channel steel is set to be shorter than the width of the core material, and in a position in which the channel steel is surrounded by the angle steel, the end of the channel steel does not interfere with the curvature surface.

2. A steel, plate-shaped core material, A pair of restraining members made of channel steel are arranged so as to bring the web into contact with the two wide surfaces of the core material, A pair of stiffening members made of angle steel are arranged to surround the core material and the restraining material, The system includes an unbonded material interposed between the core material and the restraining material, The adjacent end regions of the pair of stiffeners are welded together. The angle steel has a curved surface on the inside of its bent portion. A buckling-restrained brace characterized in that, of the channel steel, the end face of the flange located at a position corresponding to the curvature surface is a tapered surface, and in a posture in which the channel steel is surrounded by the angle steel, the end of the channel steel does not interfere with the curvature surface.

3. The buckling-restrained brace according to claim 1 or 2, characterized in that the end faces of both stiffeners are welded together.

4. The buckling-restrained brace according to claim 1 or 2, characterized in that the end face of one stiffener and the side surface of the other stiffener are welded together.

5. 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 4, characterized in that a reinforcing plate is fixed to the pair of connecting plates, and the ends of the restraining member and the stiffening member are housed in the space formed by the wide surface, the pair of connecting plates, and the reinforcing plate.

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