Buckling Restrained Brace

Abstract

To provide a buckling restraining brace that is suitable for use by being incorporated in a frame of a wooden building or the like, and, for example, at the time of a large earthquake, prevents the frame and the buckling restraining brace from deforming to the outside of a structure plane, a core material forming the buckling restraining brace from pressing a restraining plate forming a wooden restraining material, and a side plate pulled by the restraining plate from cracking.SOLUTION: A buckling restraining brace includes: a core material 10 formed of steel and having a plate shape; and a wooden restraining material 20 formed by a pair of wooden restraining plates 21 arranged so as to face two wide surfaces 11a included in the core material 10 and a pair of wooden side plates 22 arranged so as to face two narrow surfaces 11b included in the core material 10 and connected to the pair of restraining plates 21. The side plates 22 and the restraining plates 21 have an axial length shorter than that of the core material 10. The wooden restraining material 20 is provided with, in an end thereof, a pair of first steel materials 30A that are arranged outside of the pair of restraining plates 21 and tightened to each other with a bolt to restrain the pair of restraining plate 21.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a buckling-restrained brace. [Background technology]

[0002] Buckling-restrained braces, which have been designed to prevent buckling, have traditionally been used as braces to form building frames (column-beam frames, roof frames, etc.). Buckling-restrained braces come in a variety of stiffening configurations, including a steel core reinforced only with steel plates, a steel core reinforced with reinforced concrete (RC), and a steel core covered with steel and mortar.

[0003] Recently, efforts have been made to improve the fire resistance and earthquake resistance of wooden buildings (such as wooden houses, wooden warehouses, and wooden stadiums). Wooden houses inherently have advantages such as a high degree of freedom in floor plan and design, the soothing effect of natural wood, the humidity-regulating properties of wood, and generally lower construction costs compared to steel-framed or reinforced concrete structures, depending on the building's intended use (e.g., residential). However, the improved fire resistance and earthquake resistance are one factor driving increased interest in wooden buildings, including wooden houses. When incorporating the conventional buckling restrained braces described above into the frame of such a wooden house, wooden columns and beams are mixed with buckling restrained braces with metal or concrete stiffeners, resulting in an unbalanced appearance.

[0004] One possible solution is to cover the entire buckling restrained brace with a wooden or paper panel, making the metal or concrete stiffener invisible from the outside. However, this requires a great deal of work, which raises concerns about increased construction costs. Furthermore, conventional buckling restrained braces tend to be heavy because they use a lot of metal, concrete, mortar, etc., and installing heavy buckling restrained braces inside the lightweight wooden beams and columns that make up a wooden house is structurally unbalanced.

[0005] Patent Document 1 proposes a buckling restrained brace suitable for use within the framework of wooden buildings such as wooden houses. Specifically, this is a buckling restrained brace that has a core material and a pair of restraining members arranged along both sides of the core material, where the core material is made of steel and the pair of restraining members are made of wood, and the restraining members are made of laminated lumber, with the lamina stacked parallel to the core material. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 4901491 Summary of the Invention [Problem to be solved by the invention]

[0007] The wooden restraint member that surrounds the steel core member that forms the buckling-restrained brace is composed of a pair of restraint plates that face the two wide surfaces of the core member and a pair of side plates that connect the ends of the pair of restraint plates, but buckling-restrained braces have the problem that when the frame and the buckling-restrained brace incorporated into the frame are significantly deformed outward during a major earthquake, for example, the core member presses into the restraint plates, and the restraint plates pressed into the core member pull on the side plates, causing cracks in the side plates. Patent Document 1 does not mention measures to prevent cracks in the side plates caused by the restraint plates pressed into the core member pulling on the side plates when the buckling-restrained brace is deformed outward.

[0008] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a buckling restrained brace that is suitable for use in a wooden building or the like, and that can prevent cracks from occurring in the side panels pulled by the restraining plates when the frame and buckling restrained brace deform outside the structural plane during a major earthquake, for example, and the core material that forms the buckling restrained brace presses into the restraining plates that form the wooden restraining material. [Means for solving the problem]

[0009] In order to achieve the above object, one aspect of the buckling restrained brace according to the present invention is as follows: A steel plate-shaped core material, a wooden restraining member formed by a pair of wooden restraining plates arranged so as to face the two wide surfaces of the core material, and a pair of wooden side plates arranged so as to face the two narrow surfaces of the core material and connected to the pair of restraining plates; the side plates and the restraining plates are shorter in axial length than the core material, The end of the wooden restraint material is provided with a pair of first steel members that are arranged outside the pair of restraint plates and are bolted together to restrain the pair of restraint plates.

[0010] According to this aspect, a pair of first steel members are provided at the ends of the wooden restraint material, which are arranged outside the pair of restraint plates and are bolted to each other to restrain the pair of restraint plates.This makes it possible to suppress cracks (splitting) that may occur at the ends of the side panels connected near the ends of the pair of restraint plates, which receive the strongest pushing force from the core material, when the frame and buckling restraint brace are deformed outside the structural plane.

[0011] In this embodiment, a pair of restraining plates are connected by a pair of side plates to form a wooden restraining member with a closed structure made of four face plates, and the steel core member is surrounded by the wooden restraining member. With this configuration, even when the buckling restrained brace of this embodiment is applied to the frame of a wooden building, there is no risk of it giving an out-of-place appearance to the frame components. Here, the restraining plates and side plates may be made of solid wood or laminated lumber with laminated lamina.

[0012] Furthermore, in this embodiment, the wooden restraint member has a configuration in which a pair of side plates are connected to a pair of restraint plates, making the wooden restraint member easier to process. For example, the buckling restrained brace described in Patent Document 1 requires processing laminated lumber to create two wooden restraint members with L-shaped cross sections, turning them upside down, and connecting them with a core material sandwiched between them. In contrast, the buckling restrained brace of this embodiment can be produced by placing a core material between a pair of restraint plates, and then connecting a pair of side plates to a pair of restraint plates by adhesive or other means to produce the wooden restraint member. This makes the buckling restrained brace even easier to produce.

[0013] In another aspect of the buckling restrained brace according to the present invention, The first steel material has a cross-sectional shape perpendicular to its longitudinal direction that is a hat shape having a central U-shaped portion and two protruding portions protruding from both ends of the U-shaped portion, The corresponding protruding portions of the pair of first steel materials are brought into contact with each other, and bolts are inserted into bolt holes provided in both of the protruding portions and fastened by the bolts, The pair of U-shaped portions restrain the ends of the pair of side plates from the outside.

[0014] According to this aspect, by using a first steel member with a hat-shaped cross section and abutting the protruding portions of the pair of first steel members together and fastening them with bolts, the ends of the pair of restraining plates can be firmly restrained from the outside. In addition, the U-shaped portions of the pair of first steel members restrain the ends of the pair of side plates from the outside, which further enhances the restraining effect of the ends of the wooden restraining material.

[0015] In another aspect of the buckling restrained brace according to the present invention, The first steel member is formed of flat steel bars, and a pair of the flat steel bars are fastened together by a bolt. A pair of second steel members formed of separate flat steel bars are connected to the two narrow surfaces at the end of the core member so as to be perpendicular to the wide surface, The pair of second steel members restrain the ends of the pair of side plates from the outside.

[0016] According to this aspect, the pair of first steel members that restrain the ends of the pair of restraining plates from the outside and the pair of second steel members that restrain the ends of the pair of side plates from the outside are both formed from flat steel, so that the ends of the wooden restraining material can be firmly restrained with a simple end reinforcement structure.

[0017] In another aspect of the buckling restrained brace according to the present invention, The first steel material is formed of flat steel, A pair of second steel members is disposed between the pair of flat steel members, sandwiching the core member and the wooden restraint member, and the cross-sectional shape of the second steel members perpendicular to the longitudinal direction is U-shaped, with a central web portion and two flange portions at both ends of the web portion that are perpendicular to each other; Bolts are inserted into bolt holes provided in the pair of first steel members and the two flange portions therebetween, and are fastened by the bolts; The pair of web portions restrain the ends of the pair of side plates from the outside.

[0018] According to this aspect, the first steel material consists of a pair of flat steel bars that restrain the ends of a pair of restraint plates from the outside, and the second steel material has a U-shaped cross section and restrains the ends of a pair of side plates from the outside. These are bolted together to form a single unit, and the closed structure of the steel materials made up of the first steel material and the second steel material allows the ends of the wooden restraint material to be firmly restrained.

[0019] In another aspect of the buckling restrained brace according to the present invention, the core material has a narrow portion at a center side in a longitudinal direction where the width of the wide surface is relatively narrow, and a wide portion at an end side in a longitudinal direction where the width of the wide surface is relatively wide, The length of the side plate is set to be equal to or less than the length of the narrow portion of the core material.

[0020] According to this aspect, the length of the side panels is set to be less than the length of the narrow portion of the core material, so that the ends of the side panels come into contact with the ends of the wide portion of the core material, preventing the side panels from being damaged by pressure from the ends of the wide portion of the core material when the frame and buckling restraint brace are deformed, for example, during an earthquake.

[0021] In another aspect of the buckling restrained brace according to the present invention, The end of the side plate is provided with a recess that does not come into contact with the end of the wide portion of the core material.

[0022] According to this aspect, recesses are provided at the ends of the side panels that do not come into contact with the ends of the wide portions of the core material, thereby reliably preventing the ends of the wide portions of the core material from coming into contact with the side panels when the frame and buckling restraint braces deform during an earthquake. This reliably prevents the ends of the wide portions from coming into contact with the side panels, pressing against the side panels and damaging the side panels due to the pressing.

[0023] In another aspect of the buckling restrained brace according to the present invention, The narrow width portion is provided with a plasticized region that is most easily plasticized in the core material, The plasticized region is set inside the pair of first steel materials.

[0024] According to this embodiment, the plasticized region in the narrow portion of the core material is set inside a pair of first steel materials, so that even if the core material buckles in the plasticized region, the pair of restraining plates surrounding it are restrained by the pair of first steel materials outside them, so the buckled region of the core material can be firmly restrained.

[0025] The boundary region between the wide and narrow sections of the core material is a transition region where the planar and cross-sectional areas of the core material change. Therefore, a plasticized region that is easily plasticized is formed on the narrow-section side of this transition region, and this transition region can absorb the additional bending moment acting on the core material. The additional bending moment (or simply, additional bending) refers to the bending moment that can act on the wooden restraint material due to large deformation of the frame and buckling-restrained brace, for example, during a major earthquake. In this manner, in this embodiment, the additional bending moment acting on the core material can be effectively absorbed by the narrow-section side of the boundary region between the wide and narrow sections of the core material.

[0026] The core material may have two or more wide portions whose width increases in multiple stages toward the end. For example, in a configuration having two wide portions, a plasticized region is formed in the region on the narrow portion side of the boundary region between the wide surface (relatively narrow wide portion) on the narrow portion side and the narrow portion.

[0027] In another aspect of the buckling restrained brace according to the present invention, a reinforcing rib orthogonal to the wide surface of the end of the core material in the longitudinal direction is joined to the wide surface, forming a cross-shaped cross section; The restraining plate is characterized in that a recess is provided at a position corresponding to the reinforcing rib so as not to interfere with the reinforcing rib.

[0028] According to this aspect, the longitudinal ends of the core material have a cross-shaped cross section due to the reinforcing ribs joined perpendicular to the wide faces of the core material. Therefore, when a buckling restrained brace is attached to a gusset plate with the wide faces of the core material arranged parallel to the structural face of the building, the core material has reinforcing ribs perpendicular to the wide faces parallel to the structural face, thereby increasing the rigidity of the end of the core material in the outward direction of the structural face. In the gusset plate of the structural face to which the core material with a cross cross section is attached, fin stiffeners are attached to the gusset plate, and the core material of the buckling restrained brace and the gusset plate, as well as the reinforcing ribs and fin stiffeners, are each joined via a splice plate with high-tension bolts or the like. In this aspect, recesses are provided in the restraint plate at positions corresponding to the reinforcing ribs, and these recesses are configured to prevent interference between the wooden restraint material and the reinforcing ribs.

[0029] Another aspect of the buckling restrained brace according to the present invention is: In plan view, a gap is formed between the recess provided in the restraint plate and the reinforcing rib.

[0030] According to this aspect, the gap between the recess of the restraining plate and the reinforcing rib can absorb the expansion and contraction of the core material when it expands and contracts in response to deformation of the structural surface, eliminating the problem of the expanding and contracting core material coming into contact with the wall of the recess of the restraining plate and causing damage to the wooden restraining material. Here, the setting of this gap is left to the discretion of the designer, and the amount of expansion and contraction of the core material is calculated based on the set inter-story deformation angle, and for example, the gap is set to be equal to or greater than the amount of expansion and contraction of the core material. Note that the "gap" here includes the gap between the longitudinal end of the recess and the reinforcing rib, as well as the gap between the side surface of the recess and the reinforcing rib.

[0031] In addition, another aspect of the buckling restrained brace according to this aspect is as follows: The present invention is characterized in that an insert plate is interposed between the wide surface of the core material and the restraining plate.

[0032] According to this aspect, when the core undergoes high-order buckling deformation, a pressing force or the like acts locally on the restraining plate from the core, and damage to the restraining plate due to this local force can be prevented. By interposing the insert plate between the wide face of the core and the restraining plate, the force acting from the convex portion during high-order buckling deformation of the core is first transmitted to the insert plate, and the transmitted force spreads inside the insert plate, and the force diffused inside the insert plate acts on the wooden restraining plate. This effectively prevents damage to the wooden restraining plate due to multiple local forces acting from the core. [Effects of the Invention]

[0033] As can be seen from the above explanation, the buckling restrained brace of the present invention is suitable for use within the framework of a wooden building or the like. For example, during a major earthquake, the framework and buckling restrained brace may deform outside the structural plane, causing the core material forming the buckling restrained brace to press into the restraining plates forming the wooden restraining member, preventing cracks from occurring in the side panels pulled by the restraining plates. [Brief explanation of the drawings]

[0034] [Figure 1] FIG. 2 is a perspective view of an example of a core material that forms the buckling restrained brace according to the first embodiment. [Figure 2] FIG. 2 is an exploded perspective view showing an example of a wooden restraint member that forms the buckling restrained brace according to the first embodiment, together with an example of a first steel member. [Figure 3] FIG. 2 is a perspective view of an example of a buckling restrained brace according to the first embodiment. [Figure 4] FIG. 10 is a perspective view of an example of a core material that forms a buckling restrained brace according to the second embodiment. [Figure 5] FIG. 10 is an exploded perspective view showing an example of a wooden restraint member that forms a buckling restrained brace according to a second embodiment, together with another example of a first steel material. [Figure 6] FIG. 10 is a perspective view of an example of a buckling restrained brace according to a second embodiment. [Figure 7] FIG. 11 is an exploded perspective view showing an example of a wooden restraint member that forms a buckling restrained brace according to the third embodiment, together with yet another example of the first steel member. [Figure 8] FIG. 11 is a perspective view of an example of a buckling restrained brace according to a third embodiment. [Figure 9] FIG. 2 is a diagram showing the buckling restraint brace according to the first embodiment incorporated into the frame of a wooden building or the like. [Figure 10] 1 is a diagram illustrating the deformation of the frame during a major earthquake and the additional bending moment at the buckling-restrained brace joint due to the deformation of the frame. [Figure 11] FIG. 10 is a diagram showing the overall buckling line of the buckling restraint brace. DETAILED DESCRIPTION OF THE INVENTION

[0035] The buckling restrained brace according to each embodiment will be described below with reference to the accompanying drawings. Note that in this specification and drawings, substantially identical components will be designated by the same reference numerals to avoid redundant description.

[0036] [Buckling-restrained brace according to the first embodiment] First, an example of a buckling-restrained brace according to the first embodiment will be described with reference to Figures 1 to 3. Here, Figure 1 is a perspective view of an example of a core material that forms the buckling-restrained brace according to the first embodiment, and Figure 2 is an exploded perspective view showing an example of a wooden restraining material that forms the buckling-restrained brace according to the first embodiment, together with an example of a first steel material. Also, Figure 3 is a perspective view of an example of a buckling-restrained brace according to the first embodiment.

[0037] 1, core material 10 is formed from a slender, plate-shaped flat steel, and has a narrow portion 13 at the center in the longitudinal direction where the wide surface 11a is relatively narrow, and two wide portions 12A, 12B at the ends in the longitudinal direction where the wide surface 11a is relatively wide (wide portion 12B at the end is wider than wide portion 12A). In addition, reinforcing ribs 14 perpendicular to wide surface 11a are welded to wide surface 11a at the ends in the longitudinal direction of core material 10, giving it a cross-shaped cross section.

[0038] By having a narrow width portion 13 at the center of the core material 10 in the longitudinal direction and a wide width portion 12 at the end of the longitudinal direction, the narrow width portion 13 at the center can be made into a region that is easy to plasticize (plasticization region A), and further, the plasticization region A can be limited to the narrow width portion 13 at the center.

[0039] In the core material 10, in the boundary region between the wide width portion 12A and the narrow width portion 13, the region on the narrow width portion 13 side is a change region where the planar area and cross-sectional area of ​​the core material 10 change and become smaller, and therefore a plasticized region A that is prone to plasticization is formed. In the illustrated example, reinforcing ribs 14 are attached particularly to the wide width portion 12, further increasing the rigidity of the wide width portion 12, which also makes it easier for a plasticized region A to form in the boundary region on the narrow width portion 13 side. The additional bending moment acting on the core material 10 is effectively absorbed in this plasticized region A.

[0040] The overall length t1 of the core material 10 is set to be longer than the overall lengths t2 and t3 of the restraining plates 21 and side plates 22 that form the wooden restraining material 20 described below.

[0041] Furthermore, as will be explained below, the wide portion 12 and the reinforcing rib 14 each have bolt holes 12a, 14a for bolting via a splice plate to a gusset plate provided on the structural face or a fin stiffener (see FIG. 9) attached to the gusset plate. When the buckling restrained brace 100 is attached to a gusset plate so that the wide surface 11a of the core material 10 is arranged parallel to the structural face of the building, the core material 10 has reinforcing ribs 14 that are perpendicular to the wide surface 11a that is parallel to the structural face, thereby increasing the rigidity of the end of the core material 10 in the direction outward from the structural face.

[0042] The core material 10 is preferably formed from a steel material with a low yield point such as SN material (rolled steel for building structures) or LYP material (extremely low yield point steel), which improves earthquake energy absorption due to yielding of the core material 10.

[0043] Of the two wide sections 12A, 12B of the core material 10, a pair of second steel members 40A made of flat steel are welded to the left and right narrow surfaces 11b of the relatively narrow wide section 12A in a manner perpendicular to the wide surface 11a of the core material 10.

[0044] The pair of second steel members 40A, together with the pair of first steel members 30A (see FIG. 2) described below, form a closed steel structure to restrain the end of the wooden restraint member 20.

[0045] The second steel material 40A also extends from the narrow surface 11b of the wide portion 12A toward the narrow portion 13 of the core material 10, forming a gap G1 between it and the narrow surface 11b of the narrow portion 13. The end of a side panel 22 (see FIG. 2) of the wooden restraint material 20, which will be described below, is loosely fitted into this gap G1.

[0046] 2, the wooden restraint member 20 has a pair of restraint plates 21 and a pair of side plates 22 connecting the pair of restraint plates 21, with the core material 10 disposed between the pair of restraint plates 21. There is a relationship of t2>t3 between the total length t2 of the restraint plates 21 and the total length t3 of the side plates 22, and including the total length t1 of the core material 10, there is a relationship of t1>t2>t3.

[0047] The inner surfaces 21a of a pair of wooden constraining plates 21 are disposed so as to face the two wide surfaces 11a (see FIG. 1) of the core material 10, and the pair of wooden side plates 22, which are connected to the side surfaces 21b of the pair of constraining plates 21 with an adhesive, are disposed so as to face the two narrow surfaces 11b (see FIG. 1) of the core material 10. The adhesives used to connect the constraining plates 21 and the side plates 22 include urethane adhesives and epoxy adhesives. In addition to being connected with an adhesive, the constraining plates 21 and the side plates 22 can be connected with wood screws, wooden dowels, bolts, nails, and other driven or screwed materials that are driven or screwed into the sides of the side plates 22 from the sides of the side plates 22 into the interior of the constraining plates 21, thereby preventing separation of the constraining plates 21 and the side plates 22 at their joint interfaces in the event of a major earthquake or the like and functioning as a fail-safe to enhance the effect of preventing the side plates 22 from cracking.

[0048] At both ends of the inner surface 21a of the restraint plate 21, recesses 21c are provided to accommodate the reinforcing ribs 14 provided at the ends of the core material 10 so that the reinforcing ribs 14 do not come into contact with the restraint plate 21 when the core material 10 is arranged between a pair of restraint plates 21.

[0049] Although not shown in the figures, the length of the reinforcing rib 14 accommodated in the recess 21c and the length t4 of the recess 21c are set so that a predetermined gap is formed between the two when the reinforcing rib 14 is accommodated in the recess 21c. The presence of a gap between the reinforcing rib 14 and the recess 21c prevents the reinforcing rib 14 from coming into contact with the recess 21c and being pressed against the recess 21c when a buckling restrained brace incorporated into a frame is deformed during an earthquake, preventing damage to the restraint plate 21. It is also desirable to provide a gap of a predetermined width in the width direction of both the recess 21c and the reinforcing rib 14.

[0050] In addition, separate recesses 22a are provided at both ends of the side plates 22. These recesses 22a are provided at positions corresponding to the wide portions 12A of the core material 10 when the side plates 22 are disposed to the sides of the narrow portions 13 of the core material 10.

[0051] When the end of side plate 22 is loosely fitted into gap G1 (see FIG. 1) between second steel material 40A and narrow surface 11b of narrow portion 13, the end of wide portion 12A and the end of side plate 22 are not in contact or are in contact without pressing against each other. If the buckling restrained brace is deformed during an earthquake from this state, there is a risk that the end of wide portion 12A will press against the end of side plate 22, damaging side plate 22. However, by providing recess 22a at the end of side plate 22, even if the buckling restrained brace is deformed during an earthquake, the end of wide portion 12A can be accommodated in recess 22a, preventing damage to side plate 22 due to pressing from wide portion 12A.

[0052] The wooden restraint member 20 is manufactured by placing the core material 10 between a pair of restraint plates 21, and then connecting both side surfaces 21b of the pair of restraint plates 21 to a pair of side plates 22 with an adhesive, thereby manufacturing the wooden restraint member 20 with the core material 10 sandwiched between them. Furthermore, as described above, a fail-safe mechanism may be formed by driving or screwing a plurality of wood screws, wood dowels, screws, nails, etc. into the restraint plates 21 from the sides of the side plates 22.

[0053] The restraining plate 21 and the side plate 22 may be made of either solid wood or wood materials including laminated lumber made of laminated lamina. As will be described in detail below, the cross-sectional area, cross-sectional stiffness, Young's modulus, etc. of the wooden restraining member 20 are set so as to prevent global buckling of the buckling-restrained brace. This Young's modulus is determined by the wood material. Examples of wood materials include Japanese cypress, red pine, larch, fir, and Yezo spruce.

[0054] When a buckling restraint brace is incorporated into a frame, if the buckling restraint brace is deformed outside the structural plane during an earthquake, cracks (splits) may occur at the ends of the side panels 22 connected to positions corresponding to the ends of the pair of restraint plates 21 that receive the strongest pushing force from the core material 10.

[0055] Therefore, as shown in FIG. 2, a pair of first steel members 30A are disposed to restrain the ends of the pair of restraining plates 21 from the outside.

[0056] The first steel members 30A in the illustrated example are made of flat steel and have a plurality of bolt holes 30a (three in the illustrated example) on each side. The pair of first steel members 30A are aligned with the outside of the ends of the pair of restraint plates 21, and bolts 35 are inserted into the corresponding bolt holes 30a on both sides and tightened with nuts 36, thereby firmly restraining the pair of restraint plates 21 from the outside by the pair of first steel members 30A. Here, although only one set of bolts and nuts is shown in Figure 2, six sets of bolts and nuts corresponding to each bolt hole 30a are actually used.

[0057] As shown in Figure 3, a pair of first steel members 30A is engaged with a pair of second steel members 40A connected to a core member 10 incorporated into a wooden restraint member 20, and the pair of first steel members 30A is fastened together with multiple sets (six in the illustrated example) of bolts 35 and nuts 36, thereby forming a closed steel structure consisting of the pair of first steel members 30A and the pair of second steel members 40A. The end faces of the second steel members 40A and the end faces of the restraint plates 21 are, for example, flush with each other. Therefore, when the first steel members 30A are engaged with the second steel members 40A, the first steel members 30A abut against the end faces of the restraint plates 30A. Fastening the bolts 35 and nuts 36 forms a buckling-restrained brace 100 in which the pair of restraint plates 21 are restrained from their outside by the pair of first steel members 30A.

[0058] With the buckling restrained brace 100, a pair of restraint plates 21 are connected by a pair of side plates 22 to form a wooden restraint member 20 with a closed structure made of four face plates, and the steel core member 10 is surrounded by the wooden restraint member 20. With this configuration, even when the buckling restrained brace 100 is applied to the frame of a wooden building, there is no risk of it appearing out of place with the frame components.

[0059] Furthermore, a pair of first steel members 30A are provided at the ends of the wooden restraint member 20, which are arranged outside the pair of restraint plates 21 and are bolted to each other to restrain the pair of restraint plates 21. This makes it possible to suppress cracks that may occur at the ends of the side panels 22 connected near the ends of the pair of restraint plates 21, which receive the strongest pushing force from the core member 10, when the frame and buckling restraint brace 100 are deformed outside the structural plane.

[0060] [Buckling-restrained brace according to the second embodiment] Next, an example of a buckling-restrained brace according to the second embodiment will be described with reference to Figures 4 to 6. Here, Figure 4 is a perspective view of an example of a core material that forms the buckling-restrained brace according to the second embodiment, and Figure 5 is an exploded perspective view showing an example of a wooden restraint material that forms the buckling-restrained brace according to the second embodiment, together with another example of the first steel material. Also, Figure 6 is a perspective view of an example of a buckling-restrained brace according to the second embodiment.

[0061] The core material 10A shown in FIG. 4 differs from the core material 10 shown in FIG. 1 in that it does not include a pair of second steel materials 40A.

[0062] As shown in Figure 5, with regard to the steel members that restrain the ends of the wooden restraint member 20, a pair of first steel members 30A that restrain a pair of restraint plates 21 from the outside are similar to the first steel members shown in Figures 2 and 3. On the other hand, the second steel member 40B is a steel member that has a central web portion 41 and two flange portions 42 that intersect at right angles on both ends of the web portion 41, and has a U-shaped cross section.

[0063] Bolts 35 are inserted into the bolt holes 30a of the pair of first steel materials 30A and the bolt holes 42a of the two flange portions 42 of the second steel material 40B located between them, and are tightened with nuts 36, so that the pair of restraint plates 21 are firmly restrained from the outside by the pair of first steel materials 30A.

[0064] Although not shown, the web portion 41 of the second steel material 40B may be welded to the narrow surface 11b of the wide portion 12A of the core material 10, like the second steel material 40A in FIG.

[0065] As shown in Figure 6, by forming a closed steel structure using a pair of first steel members 30A and a pair of second steel members 40B at both ends of the wooden restraint member 20, a buckling restraint brace 100A is formed in which a pair of restraint plates 21 are restrained from the outside by a pair of first steel members 30A.

[0066] The buckling restrained brace 100A also provides the same effects as the buckling restrained brace 100.

[0067] [Buckling-restrained brace according to the third embodiment] Next, an example of a buckling restrained brace according to a third embodiment will be described with reference to Figures 7 and 8. Here, Figure 7 is an exploded perspective view showing an example of a wooden restraint member that forms the buckling restrained brace according to the third embodiment, together with yet another example of the first steel member. Also, Figure 8 is a perspective view of an example of a buckling restrained brace according to the third embodiment.

[0068] In this embodiment, the same core material 10A as in the second embodiment is used.

[0069] As shown in Figure 7, the steel members restraining the ends of the wooden restraint material 20 are a pair of first steel members 30B, which have a central U-shaped portion 31 and two protruding portions 32 extending from both ends of the U-shaped portion 31, and have a hat-shaped cross-sectional shape.

[0070] The corresponding protrusions 32 of the pair of first steel materials 30B are abutted against each other, bolts 35 are inserted into the bolt holes 32a of both protrusions 32, and tightened with nuts 36, so that the pair of restraint plates 21 are firmly restrained from the outside by the pair of first steel materials 30B.

[0071] As shown in Figure 8, by forming a closed steel structure using a pair of first steel members 30B at both ends of the wooden restraint member 20, a buckling restraint brace 100B is formed in which a pair of restraint plates 21 are restrained from their outside by a pair of first steel members 30B.

[0072] The buckling restrained brace 100B also provides the same effects as the buckling restrained braces 100 and 100A.

[0073] Although not shown, in the buckling restraint braces 100, 100A, and 100B, an insert plate may be interposed between the wide surface 11a of the core member 10 and the inner surface 21a of the restraint plate 21. The insert plate may be either a steel plate or a wooden plate, and the wooden plate may be, for example, LVL (Laminated Veneer Lumber).

[0074] Due to the high-order buckling deformation of the core material 10, a pressing force acts locally on the inner surface 21a of the restraining plate 21 from the core material 10, and this local pressing force may cause damage to the restraining plate 21. In contrast, by interposing an insert plate between the core material 10 and the restraining plate 21, the pressing force acting from the convex portion during the high-order buckling deformation of the core material 10 is first transmitted to the insert plate, and the transmitted pressing force spreads inside the insert plate, and the pressure diffused inside the insert plate acts as a dispersed force on the wooden restraining plate 21. This effectively prevents damage to the wooden restraining plate 21 due to multiple local pressing forces acting from the core material 10.

[0075] [Framework incorporating buckling restraint braces] Next, an example of a building frame incorporating the buckling restrained brace of the first embodiment will be described with reference to Figures 9 and 10. Here, Figure 9 is a diagram showing the state in which the buckling restrained brace according to the first embodiment is incorporated into the frame of a wooden building or the like. Also, Figure 10 is a diagram explaining the deformation of the frame during a major earthquake and the additional bending moment at the buckling restrained brace joint resulting from the deformation of the frame. Note that the buckling restrained brace shown in the example may be incorporated into the frame of a steel (S) building, a reinforced concrete (RC) building, or an SRC (Steel Reinforced Concrete) building, in addition to the frame of a wooden building.

[0076] The frame S shown in Figure 9 is formed from wooden columns C and beams B that constitute a wooden building or the like. Gusset plates GP made of flat steel are attached to the two diagonally positioned corners. Fin stiffeners FS are welded to the surface of the gusset plates GP so that they are perpendicular to the surface. The fin stiffeners FS are joined to the gusset plates GP so that their center L3 intersects with the intersection O between the column center L1 of the column C and the beam center L2 of the beam B. The buckling restrained brace 100 is also arranged linearly passing through both diagonally positioned intersections O.

[0077] The gusset plate GP and the wide portion 12 of the core material 10 are joined by high tension bolts via a splice plate SP, and the fin stiffener FS and the reinforcing rib 14 are joined by high tension bolts via a splice plate SP.

[0078] As shown in Figure 10, when a large earthquake occurs, deformation of the structural plane can cause an additional bending moment, as shown in equation (1) below, to act on the buckling-restrained brace joint, assuming that the joint is rigid.

[0079]

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[0080] According to the buckling restraint brace 100, the ends of the restraint plates 21, which are likely to receive the strongest pushing force from the core material 10, are surrounded by a closed structure made up of a pair of first steel members 30A and a pair of second steel members 40B, and the pair of restraint plates 21 are restrained from the outside by the pair of first steel members 30A. This makes it possible to suppress cracks that may occur at the ends of the side plates 22 connected near the ends of the pair of restraint plates 21, which are likely to receive the strongest pushing force from the core material 10, when the structural face S to which the buckling restraint brace 100 is attached is significantly deformed during a major earthquake.

[0081] [Study of overall buckling] Next, we will explain the design method for preventing global buckling of buckling-restrained braces.

[0082] When designing a buckling-restrained brace, the following formula (2) must be satisfied to prevent global buckling of the buckling-restrained brace.

[0083]

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[0084] Here, the bending moment acting on the center of the restraint plate can be expressed by the following equation (3).

[0085]

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[0086] The condition for preventing the overall buckling of the wooden restraint member is to satisfy the following equation (4).

[0087]

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[0088] Equation (4) is shown in Figure 11 as the global bending stress curve for the buckling-restrained brace. In Figure 11, the upper side of the global bending stress curve is the safe zone, and the lower side is the dangerous zone. The design axial force of the wooden restraint member, the Euler load, the length of the general part of the core member, and the yield bending strength of the wooden restraint member are set so that they fall within the safe zone. Note that the global bending stress curve for the buckling-restrained brace shown in Figure 11 applies to both global buckling in the weak axis direction of the core member and global buckling in the strong axis direction.

[0089] In addition to examining the relationship between the yield bending strength of the wooden restraint material and the bending moment acting on it, it is also advisable to examine the fact that the short-term allowable bending strength of the wooden restraint material will be greater than the bending moment acting on it when the core material yields (formula omitted).

[0090] <Study on the compressive failure of wooden restraints> Next, we will explain how to evaluate the failure of wooden restraints due to the core material penetrating into the wooden restraint. To prevent the wooden restraint from failing due to the core material penetrating into the wooden restraint, we verify that the following formula (5) is satisfied.

[0091]

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[0092] Here, in addition to examining the relationship between the compressive strength of the restraining plate and the stiffening force acting on it, it is also advisable to examine the fact that the short-term allowable compressive strength of the restraining plate will be greater than the stiffening force acting when the core material yields (formula omitted).

[0093] It should be noted that the present invention is not limited to the configurations shown here, and other embodiments may be possible in which other components are combined with the configurations described in the above embodiments. In this regard, the present invention can be modified within the scope of the present invention, and can be appropriately determined depending on the application form. [Explanation of symbols]

[0094] 10, 10A: Core material 11a: Wide surface 11b:Narrow side 12, 12A, 12B: Wide section 12a: Bolt hole 13: Narrow section 14: Reinforcing rib 14a: Bolt hole 15:Second steel plate 15A: 2nd steel plate (flat steel) 17: Interpolation board 17a: Bolt hole 20: Wooden restraint 21: Restraint plate 21a:Inside 21b: Side 21c: Recess 22: Side panel 22a: Recess 30: 1st steel material 30A: 1st steel material (flat steel) 30B: 1st steel material 30a: Bolt hole 31: U-shaped section 32: Protruding part 32a: Bolt hole 35: Bolt 36: Nut 40:Second steel material 40A:Second steel material (flat steel) 40B:Second steel material 41: Web Department 42: Flange part 42a: Bolt hole 100, 100A, 100B: Buckling restraint brace A: Plasticization region S: Frame (composition) C: Pillar B: Beam GP: Gusset plate FS: Fin stiffener SP: Splice plate

Claims

1. A steel plate-shaped core material, a wooden restraining member formed by a pair of wooden restraining plates arranged so as to face the two wide surfaces of the core material, and a pair of wooden side plates arranged so as to face the two narrow surfaces of the core material and connected to the pair of restraining plates; the side plates and the restraining plates are shorter in axial length than the core material, a pair of first steel members are provided at the ends of the wooden restraint member, the first steel members being arranged on the outside of the pair of restraint plates and fastened to each other with bolts to restrain the pair of restraint plates; the core material has a narrow portion at a center side in a longitudinal direction where the width of the wide surface is relatively narrow, and a wide portion at an end side in a longitudinal direction where the width of the wide surface is relatively wide, The length of the side plate is set to be equal to or less than the length of the narrow portion of the core material, The narrow width portion is provided with a plasticized region that is most easily plasticized in the core material, A buckling-restrained brace, characterized in that the plasticized region is set within the pair of first steel members.

2. 2. The buckling restraint brace according to claim 1, wherein the end of the side plate is provided with a recess that does not come into contact with the end of the wide portion of the core material.

3. A steel plate-shaped core material, a wooden restraining member formed by a pair of wooden restraining plates arranged so as to face the two wide surfaces of the core material, and a pair of wooden side plates arranged so as to face the two narrow surfaces of the core material and connected to the pair of restraining plates; the side plates and the restraint plates are shorter in axial length than the core material, a pair of first steel members are provided at the ends of the wooden restraint member, the first steel members being arranged on the outside of the pair of restraint plates and fastened to each other with bolts to restrain the pair of restraint plates; a reinforcing rib orthogonal to the wide surface of the end of the core material in the longitudinal direction is joined to the wide surface, forming a cross-shaped cross section; A buckling restraint brace, characterized in that the restraint plate has a recess at a position corresponding to the reinforcing rib so as not to interfere with the reinforcing rib.

4. The first steel material has a cross-sectional shape perpendicular to its longitudinal direction that is a hat shape having a central U-shaped portion and two protruding portions protruding from both ends of the U-shaped portion, The corresponding overhanging portions of the pair of first steel materials are brought into contact with each other, and bolts are inserted into bolt holes provided in both of the overhanging portions and fastened by the bolts, 4. The buckling restraint brace according to claim 1, wherein the pair of U-shaped portions restrain the ends of the pair of side plates from the outside.

5. A steel plate-shaped core material, a wooden restraining member formed by a pair of wooden restraining plates arranged so as to face the two wide surfaces of the core material, and a pair of wooden side plates arranged so as to face the two narrow surfaces of the core material and connected to the pair of restraining plates; the side plates and the restraining plates are shorter in axial length than the core material, a pair of first steel members are provided at the ends of the wooden restraint member, the first steel members being arranged on the outside of the pair of restraint plates and fastened to each other with bolts to restrain the pair of restraint plates; The first steel member is formed of flat steel bars, and a pair of the flat steel bars are fastened together by a bolt. A pair of second steel members formed of separate flat steel bars are connected to the two narrow surfaces at the end of the core member so as to be perpendicular to the wide surface, A buckling-restrained brace, characterized in that the pair of second steel members restrain the ends of the pair of side plates from the outside.

6. A steel plate-shaped core material, a wooden restraining member formed by a pair of wooden restraining plates arranged so as to face the two wide surfaces of the core material, and a pair of wooden side plates arranged so as to face the two narrow surfaces of the core material and connected to the pair of restraining plates; the side plates and the restraining plates are shorter in axial length than the core material, a pair of first steel members are provided at the ends of the wooden restraint member, the first steel members being arranged on the outside of the pair of restraint plates and fastened to each other with bolts to restrain the pair of restraint plates; The first steel material is formed of flat steel, A pair of second steel members is disposed between the pair of flat steel members, sandwiching the core member and the wooden restraint member, and the cross-sectional shape of the second steel members perpendicular to the longitudinal direction is U-shaped, with a central web portion and two flange portions at both ends of the web portion that are perpendicular to each other; Bolts are inserted into bolt holes provided in the pair of first steel members and the two flange portions therebetween, and are fastened by the bolts; A buckling restrained brace, characterized in that the pair of web portions restrain the ends of the pair of side plates from the outside.

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