Buckling-restrained brace

Abstract

To provide a buckling-restraining brace that can prevent damage to the slits and surrounding areas of a wooden restraint body due to the stiffening force acting from the core material. [Solution] The structure comprises a steel plate-shaped core material 10 and a wooden restraint body 20 formed by a pair of wooden restraint members 30, which are arranged to face at least two wide surfaces 10a of the core material 10. The core material 10 has a narrow section 11 at its longitudinal center where the width of the wide surface 10a is relatively narrow, and a wide section 12 at its longitudinal end where the width of the wide surface 10a is relatively wide. Reinforcing ribs 14 are joined to the wide surface 10a at the longitudinal end of the core material 10, giving it a cross-shaped cross section. A slit 35 that does not interfere with the reinforcing rib 14 is provided at a position corresponding to the reinforcing rib 14 of the pair of restraint members 30, and a reinforcing member 60 is attached to the inner wall surface of the slit 35.

Description

Technical Field

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

Background Art

[0002] Conventionally, as braces for forming building structures (column-beam structures, roof structures, etc.), buckling restraint braces with buckling prevention measures have been applied. As buckling restraint braces, there are various bracing forms, such as a form in which only steel plates reinforce the periphery of a steel core material, a form in which RC (Reinforced Concrete) reinforces the periphery of a steel core material, and a form in which the periphery of a steel core material is coated with steel and mortar.

[0003] By the way, recently, efforts have been made to improve the fire resistance and seismic resistance of wooden buildings (wooden houses, wooden warehouses, wooden stadiums, etc.). Wooden buildings inherently have advantages such as a high degree of freedom in floor plans and designs, a soothing effect due to natural wood, a humidity control effect of wood, and generally lower construction costs compared to steel-frame or RC structures depending on the building use such as houses. However, the improvement of the above-mentioned fire resistance and seismic resistance is one of the factors increasing the attention of wooden buildings including wooden buildings. When incorporating the above-mentioned conventional buckling restraint braces into the structure of such wooden buildings, it is inevitable that wooden columns and beams and buckling restraint braces having metal or concrete reinforcing materials will coexist, resulting in an unbalanced appearance.

[0004] Therefore, a measure may be considered to cover the entire buckling restraint brace with a wooden or paper panel or the like so that the metal or concrete reinforcing material cannot be visually recognized from the outside. However, this measure requires a great deal of labor, so there is a concern about an increase in construction costs. In addition, since conventional buckling restraint braces use a lot of metal, concrete, mortar, etc., they tend to be heavy, and it is structurally unbalanced to attach a heavy buckling restraint brace to lightweight wooden beams and columns constituting a wooden building.

[0005] Here, Patent Document 1 proposes a buckling-restrained brace suitable for use incorporated into the frame of a wooden building. Specifically, it is a buckling-restrained brace having a core material and a pair of restraining members arranged along both sides of the core material, wherein the core material is made of steel and the pair of restraining members are made of wood, and laminated timber is applied to these restraining members, and the laminated timber has laminations stacked parallel to the core material. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Patent No. 4901491 [Overview of the project] [Problems that the invention aims to solve]

[0007] According to the buckling-restrained brace described in Patent Document 1, the resistance of the buckling-restrained brace against overall buckling can be improved by using a pair of restraining members made of wood.

[0008] Incidentally, one form of the core material that forms a buckling-restrained brace is one in which the core material has a narrow section with a relatively narrow width at the center in the longitudinal direction and a wide section with a relatively wide width at the end in the longitudinal direction, with reinforcing ribs joined to the wide section at the end, giving it a cross-shaped cross section, and the ends of this cross-shaped cross section are bolted to the gusset plates or brackets of the frame. By making the end section wide and further giving it a cross-shaped cross section, the rigidity of the ends of the core material is relatively increased, suppressing the yielding of the ends that are joined to the frame during an earthquake, and by plasticizing the narrow section in the center, a buckling-restrained brace with excellent seismic energy absorption is created. More specifically, due to the displacement of the frame during an earthquake, a compressive force acts on the core material, and the seismic energy is absorbed as the core material, especially the narrow section, deforms in a higher-order buckling mode.

[0009] When the above-mentioned higher-order buckling mode deformation occurs in the narrow section of the core material, a stiffening force (compressive force) often acts on the wooden restraint body surrounding the core material. Therefore, the wooden restraint body surrounding the core material needs to have sufficient compression resistance to counteract the stiffening force. Generally, the wooden restraint body is provided over the entire narrow section of the core material and up to a point midway through the wide section. Furthermore, if the end of the core material has the above-mentioned cross-shaped cross section, slits are generally provided in the wooden restraint body at positions corresponding to the reinforcing ribs to prevent interference between the wooden restraint body and the reinforcing ribs.

[0010] When the core material has the narrow and wide sections described above, the boundary region between the narrow and wide sections is a region of cross-sectional change, making it prone to stress concentration and resulting in a tendency for the stiffening force described above to be large. However, if the slit in the wooden restraint body is close to this boundary region, there is a problem in that the stiffening force acting near the slit, which is a structurally weaker area in the wooden restraint body compared to other areas, makes it more susceptible to damage, including cracking. Furthermore, the buckling restraint brace described in Patent Document 1 does not disclose any means to resolve damage to the wooden restraint body corresponding to the end side of the core material.

[0011] The present invention has been made in view of the above problems, and relates to a buckling-restrained brace having a core material that has a narrow section that absorbs seismic energy and wide sections at both ends thereof, with reinforcing ribs joined to the wide sections, and a wooden restraint body surrounding the core material that has slits to prevent interference with the reinforcing ribs, and aims to provide a buckling-restrained brace that can suppress damage to the slits and surrounding areas of the wooden restraint body due to the stiffening force acting from the core material. [Means for solving the problem]

[0012] To achieve the above objective, one embodiment of the buckling-restrained brace according to the present invention is: A steel, plate-shaped core material, It has a wooden restraint body, which is made of a pair of wooden restraint members and is arranged to face at least two wide surfaces of the core material, The core material has a narrow section at its longitudinal center where the width of the wide surface is relatively narrow, and a wide section at its longitudinal end where the width of the wide surface is relatively wide. The wide surface at the longitudinal end of the core material has reinforcing ribs joined to it perpendicular to the wide surface, so that the cross-sectional shape is cross-shaped. Of the pair of restraining members, a slit is provided at a position corresponding to the reinforcing rib that does not interfere with the reinforcing rib. The slit is characterized by having a reinforcing material attached to its inner wall surface.

[0013] According to this embodiment, by attaching the reinforcing material to the inner wall surface of the slit, which is provided at a position corresponding to the reinforcing rib of the restraining material and does not interfere with the reinforcing rib, it is possible to suppress damage to the slit and its surrounding area in the wooden restraining body due to stiffening forces caused by deformation of higher-order buckling modes that occur at or near the boundary between the wide and narrow sections.

[0014] The reinforcing material can be formed, for example, by bending a steel plate so that it fits inside the inner wall surface of the slit, or by welding multiple steel plates together. Furthermore, the reinforcing material can be attached by fitting it into the inner wall surface of the slit, by bonding it to the inner wall surface of the slit with an adhesive, or by fastening it to the inner wall surface of the slit with screws or other fasteners.

[0015] In this embodiment, a steel core is surrounded by a wooden restraint body formed by a pair of wooden restraint members. 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 appearing disproportionate to the frame members. Here, the restraint members may be made of solid wood or of laminated timber with laminated laminas.

[0016] In this embodiment, since the core material has a cross-shaped cross-section due to the joining of reinforcing ribs perpendicular to the wide surface of the core material at its longitudinal end, when the buckling-restrained brace is attached to a gusset plate or the like with the wide surface of the core material positioned parallel to the structural plane of the building, the core material has reinforcing ribs perpendicular to the wide surface parallel to the structural plane, thereby increasing the rigidity in the outward direction at the end of the core material. In the gusset plate of the structural plane to which such a cross-shaped core material is attached, a fin stiffener is attached to the gusset plate, and the core material of the buckling-restrained brace and the gusset plate, and the reinforcing ribs and the fin stiffener are joined to each other via a splice plate using high-tension bolts or the like.

[0017] Furthermore, other embodiments of the buckling-restrained brace according to the present invention include: The cross-sectional shape of the inner wall surface of the slit is U-shaped, The reinforcing material is characterized in that it consists of a U-shaped piece having a U-shaped cross-section complementary to the cross-sectional shape of the slit, and the U-shaped piece abuts over the entire longitudinal area of ​​the inner wall surface.

[0018] According to this embodiment, a reinforcing material consisting of a U-shaped piece having a U-shaped cross-sectional shape complementary to the cross-sectional shape of the slit is in contact with the entire longitudinal area of ​​the inner wall surface of the slit. As a result, the reinforcing material can increase the load-bearing capacity of the entire slit against stiffening forces acting from the core material.

[0019] Furthermore, other embodiments of the buckling-restrained brace according to the present invention include: The cross-sectional shape of the inner wall surface of the slit is U-shaped, The reinforcing material is characterized in that it consists of a U-shaped piece having a U-shaped cross-sectional shape complementary to the cross-sectional shape of the slit, and the U-shaped piece abuts against a portion of the central area in the longitudinal direction of the inner wall surface.

[0020] According to this aspect, a reinforcing member composed of a U-shaped piece having a U-shaped cross-sectional shape complementary to the cross-sectional shape of the slit abuts on a partial region on the central side in the longitudinal direction of the inner wall surface. Thus, while reducing the material of the reinforcing member (for example, the amount of steel material), the reinforcing member can increase the load-bearing capacity of a region in the slit where there is a high possibility that a supplementary stiffness force acts on the core material.

[0021] Moreover, another aspect of the buckling restraint brace according to the present invention is characterized in that a partial region on the central side where the U-shaped piece abuts is set by the amount of elongation of the narrow portion.

[0022] According to this aspect, in a form in which a reinforcing member composed of a U-shaped piece abuts on a partial region on the central side in the longitudinal direction of the inner wall surface, by setting a partial region on the central side by the amount of elongation of the narrow portion, a partial region on the central side (a region where there is a high possibility that a supplementary stiffness force acts) can be reasonably set.

[0023] Here, the amount of elongation (Δ) can be set by the product of the longitudinal length L of the narrow portion or L / 2, which is half thereof, and a predetermined strain (δ). Since there are a pair of wide portions on both sides of the narrow portion and slits are provided at positions corresponding to the reinforcing ribs in both wide portions of the wooden restraint body, the total amount of elongation Δ of the narrow portion is L×δ. Although using L in the setting of the amount of elongation Δ results in a design on the safe side, whether to adopt L or L / 2 in the setting of the amount of elongation is a matter of the designer's judgment.

[0024] During a major earthquake, when compressive or tensile forces are applied to the core material, the narrow section of the core material deforms primarily. Compressive forces cause higher-order buckling mode deformation in the narrow section, and tensile forces cause the narrow section to stretch, and this process repeats. As described above, in the boundary region between the narrow and wide sections of the core material, the stiffening force acting on the wooden restraint body also increases due to stress concentration. Therefore, even if the narrow section stretches, by placing a reinforcing material consisting of a U-shaped piece in the central part of the slit within a range determined by the amount of elongation of the narrow section, the slit's resistance to the stiffening force caused by higher-order buckling mode deformation occurring at or near the boundary between the wide and narrow sections can be increased.

[0025] Furthermore, other embodiments of the buckling-restrained brace according to the present invention include: The cross-sectional shape of the inner wall surface of the slit is U-shaped, The reinforcing material is characterized by being made of a U-shaped piece having a U-shaped cross-section, and the cross-sectional dimensions decreasing toward the center in the longitudinal direction of the inner wall surface.

[0026] According to this embodiment, a U-shaped piece having a U-shaped cross-section and a shape in which the cross-sectional dimensions decrease toward the center in the longitudinal direction of the inner wall surface is provided inside the slit. As a result, the width of the U-shaped piece is wider at the ends of the slit, which ensures clearance when additional bending is applied, and as the cross-sectional dimensions of the U-shaped piece decrease toward the center, the amount of reinforcing material (e.g., amount of steel) can be reduced while increasing the slit's resistance to stiffening forces.

[0027] Furthermore, other embodiments of the buckling-restrained brace according to the present invention include: The reinforcing material is characterized in that it has a U-shaped piece and an end piece provided at the central end of the U-shaped piece, and the end piece abuts against the central end surface of the inner wall surface of the slit.

[0028] According to this embodiment, the reinforcing member has a U-shaped piece and an end piece provided at the central end of the U-shaped piece, and the end piece abuts against the central end surface of the inner wall surface of the slit, thereby further increasing the rigidity of the reinforcing member and further increasing the resistance of the slit to the stiffening force acting from the core material.

[0029] Furthermore, in other embodiments of the buckling-restrained brace according to the present invention, The wide portion comprises a first wide portion at the end and a second wide portion that is relatively narrower in width than the first wide portion. The second wide portion is continuous with the narrow portion, The end of the slit is located at an intermediate position in the second wide portion, The first wide portion is characterized by having bolt holes through which bolts are inserted when the frame is bolted to it.

[0030] According to this embodiment, the wide section comprises a first wide section at the end and a second wide section that is relatively narrower than the first wide section, and bolt holes through which bolts are inserted when bolted to the frame are provided in the first wide section, thereby allowing the reinforcing ribs joined to the wide section and the bolt holes provided in the wide section to be separated as much as possible. This makes it possible to suppress interference between the tool and the reinforcing ribs when bolting bolts through the bolt holes to connect to brackets of the frame, etc.

[0031] Furthermore, in other embodiments of the buckling-restrained brace according to the present invention, The wooden restraint body is characterized by further having a pair of wooden side plates that connect the corresponding ends of the pair of restraint members.

[0032] According to this embodiment, the wooden restraint body further has a pair of wooden side plates that connect the corresponding ends of a pair of restraint members, thereby allowing the core material to be surrounded by a wooden restraint body with a strong closed structure. Here, the wooden restraint members and side plates can be connected by adhesive, nails, screws, bolts, or a combination thereof. [Effects of the Invention]

[0033] As can be understood from the above explanation, the buckling-restrained brace of the present invention has a core material comprising a narrow section that absorbs seismic energy and wide sections at both ends thereof, with reinforcing ribs joined to the wide sections, and a wooden restraint body surrounding the core material having slits to prevent interference with the reinforcing ribs. In this buckling-restrained brace, it is possible to suppress damage to the slits and surrounding areas of the wooden restraint body due to the stiffening force acting from the core material. [Brief explanation of the drawing]

[0034] [Figure 1] This is a perspective view showing an example of a core material for forming a buckling-restrained brace according to the embodiment. [Figure 2] This is a perspective view of an example of a buckling-restrained brace according to an embodiment. [Figure 3] This is a view taken along the line III-III in Figure 2, which is a longitudinal cross-sectional view of the end of the buckling-restrained brace according to the embodiment. [Figure 4A] This is a perspective view showing an example of a reinforcing material attached to a slit. [Figure 4B] This is a perspective view showing another example of a reinforcing material attached to the slit. [Figure 4C] This is a perspective view showing yet another example of reinforcing material attached to the slit. [Figure 4D] This is a perspective view showing yet another example of reinforcing material attached to the slit. [Figure 5] Figure 2 is a view along the VV arrow, which is a longitudinal cross-sectional view of the central part of the buckling-restrained brace according to the embodiment. [Figure 6] This is a cross-sectional view taken along the line VI-VI in Figure 2, where the restraining material is cut at a point midway through its thickness. [Figure 7] This figure shows the buckling-restrained brace according to the embodiment incorporated into the frame of a wooden building or the like. [Figure 8] This figure illustrates the deformation patterns of the frame during a major earthquake and the additional bending moment at the buckling-restrained brace joints caused by the deformation of the frame. [Figure 9] This figure shows the overall buckling curve of the buckling-restrained brace. [Figure 10] This diagram illustrates buckling and stiffening forces in higher-order buckling modes of the core material. [Modes for carrying out the invention]

[0035] 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.

[0036] [Buckling-restrained brace according to an embodiment] First, 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 a perspective view showing an example of the core material forming the buckling-restrained brace according to the embodiment, and Figure 2 is a perspective view of an example of the buckling-restrained brace according to the embodiment. Figure 3 is a cross-sectional view taken along the line III-III in Figure 2, cut at an intermediate position in the thickness of the restraining material, and Figures 4A to 4B are perspective views showing an example of a reinforcing material attached to a slit. Furthermore, Figure 5 is a longitudinal cross-sectional view taken along the line VV in Figure 2, showing the central part of the buckling-restrained brace according to the embodiment, and Figure 6 is a transverse cross-sectional view taken along the line VI-VI in Figure 2, cut at an intermediate position in the thickness of the restraining material.

[0037] As shown in Figure 1, the core material 10 is formed from a long, slender, plate-shaped flat steel, 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.

[0038] More specifically, the wide section 12 comprises a first wide section 12A at the end and a second wide section 12B that is relatively narrower than the first wide section 12A. The width is tapered from the first wide section 12A to the second wide section 12B. Here, the wide section 12 may not have two wide sections of different widths, but rather a single wide section (wide section 12A only).

[0039] From the first wide section 12A to the second wide section 12B, a reinforcing rib 14 perpendicular to the wide surface 10a is welded to the center of the wide surface 10a, and the wide section 12 has a cross-shaped cross section.

[0040] The core material 10 has a narrow section 11 on the central side in its longitudinal direction and a wide section 12 on the end side in its longitudinal direction, thereby making the narrow section 11 on the central side a region that is easily plasticized (plasticization region).

[0041] Furthermore, in the illustrated example, reinforcing ribs 14 are attached to the wide section 12, and the rigidity of the wide section 12 is further increased, making the narrow section 11 more susceptible to plastic deformation. The additional bending moment acting on the core material 10 is effectively absorbed in the narrow section 11, which is the plastic deformation region.

[0042] Furthermore, bolt holes 12a and 14a are provided in the wide section 12 and the reinforcing rib 14, respectively, for bolt connection via splice plates to gusset plates provided on the structural surface and fin stiffeners (see Figure 7) attached to the gusset plates, as described below.

[0043] When the buckling-restrained brace 100 is attached to the gusset plate such that the wide surface 10a of the core material 10 is arranged parallel to the structural plane of the building, the core material 10 has reinforcing ribs 14 perpendicular to the wide surface 10a that is parallel to the structural plane, thereby increasing the rigidity of the end of the core material 10 in the direction outward of the structural plane.

[0044] The core material 10 is preferably made of a steel material with a low yield point, such as SN material (rolled steel for building structures) or LYP material (ultra-low yield point steel), which improves the seismic energy absorption due to the yielding of the core material 10.

[0045] In the core material 10 shown in the figure, the length between the boundaries P, P of the wide section 12 and the narrow section 11 on the left and right sides (i.e., the length of the narrow section 11 in the longitudinal direction) is L.

[0046] As shown in Figure 2, a pair of wooden restraining members 30 are arranged so as to sandwich a pair of wide surfaces 10a of the core material 10, and a pair of wooden side plates 40 are connected to the ends of the pair of restraining members 30, thereby forming a wooden restraining body 20, and a buckling restraining brace 100 is formed by surrounding the core material 10 with the wooden restraining body 20.

[0047] Here, the restraint member 30 and the side plate 40 are connected by one or more of the following: adhesive, nails, screws, or bolts. The wooden restraint body may also be formed by only a pair of restraint members (a form without side plates), in which case the pair of restraint members are connected to each other by adhesive, nails, screws, etc.

[0048] A slit 35 is provided at the longitudinal end of the restraining member 30, and a portion of the reinforcing rib 14, which is joined to the end of the core material 10, is loosely fitted into the slit 35, thereby preventing interference between the restraining member 30 and the reinforcing rib 14.

[0049] The restraining member 30 is a laminated timber formed by laminating and bonding multiple laminas together. As will be explained in detail below, the cross-sectional area, sectional stiffness, Young's modulus, etc., of the wooden restraining body 20 are set in order to prevent overall buckling of the buckling-restrained brace. This Young's modulus is determined by the type of wood. Examples of wood types include cypress, Japanese red pine, Japanese larch, fir, and Yezo spruce.

[0050] The wooden restraint body 20 surrounds the long, narrow portion 11 of the steel core material 10, thereby forming a buckling restraint brace 100 with excellent aesthetic design. Here, although not shown in the figures, the core material 10 may have protrusions on both wide surfaces 10a of the narrow portion 11, and the restraint material 30 may have grooves on the wide surface corresponding to the protrusions, with the protrusions fitting into the grooves on both sides to prevent the core material 10 from shifting relative to the restraint material 30.

[0051] As shown in Figure 3, a gap G1 of a predetermined width is provided between the slit 35 of the restraint member 30 and the reinforcing rib 14. This gap G1 absorbs the deformation of the core material 10 (and reinforcing rib 14) when the structural surface to which the buckling restraint brace 100 is attached deforms significantly in the strong axis direction or weak axis direction, thereby preventing the reinforcing rib 14 from acting on the restraint member 30 and damaging the wooden restraint body 20.

[0052] Furthermore, in the end region of the core material 10, a gap G2 is provided between the wide portion 12 and the side plate 40 and the restraining member 30, as shown in Figure 3. This gap G2, like the gap G1, absorbs the deformation of the core material 10 and prevents the wide portion 12 of the core material 10 from acting on the side plate 40 and the restraining member 30, thereby preventing damage to the wooden restraint body 20.

[0053] On the other hand, the central region of the core material 10 is restrained by the wide surface 10a of the core material 10 contacting the wide surface of the restraining member 30, as shown in Figure 5. In contrast, a spacer 50 is interposed between the narrow surface 10b of the core material 10 and the side plate 40 to prevent the core material 10 from shifting toward the side plate 40. Here, the spacer 50 may be fixed to one of the restraining members 30 with nails, screws, or the like. Furthermore, although not shown in the figures, these members may be joined to each other by a pair of restraining members 30 and a spacer 50 with multiple bolts passing through them.

[0054] Returning to Figure 3, the slit 35 provided at the longitudinal end of the restraint member 30 has a U-shaped cross-section on its inner wall surface. More specifically, as shown in Figure 4A, which shows the end of the restraint member 30 turned over, the inner wall surface of the slit 35 provided on the opposing surface 31 comprises a pair of side surfaces 35a along the longitudinal direction of the restraint member 30, a bottom surface 35b connecting the pair of side surfaces 35a, and an end surface 35c on the central side of the restraint member 30. Note that in the orientation of Figure 4A, the bottom surface 35b is literally the bottom surface, but when inverted, the bottom surface 35b becomes the top surface, but in this specification, it is collectively referred to as the bottom surface 35b.

[0055] A first reinforcing member 60 (an example of a reinforcing member), consisting of a U-shaped piece 61 having the same length t1 and a U-shaped cross-sectional shape complementary to the inner wall surface, is fitted into the inner wall surface of a slit 35 of length t1 in a position where it abuts against a pair of side surfaces 35a and a bottom surface 35b.

[0056] The first reinforcing member 60 is formed into a U-shape by bending a steel plate or by welding multiple steel plates together.

[0057] The first reinforcing member 60 is attached to the slit 35 by fitting it into the slit 35, by bonding it to the inner wall surface via an adhesive (not shown), or by fastening it to the inner wall surface via fasteners such as screws (not shown).

[0058] As shown in Figures 2, 3, and 4A, the attachment of the first steel reinforcing member 60 to the inner wall surface of the slit 35 suppresses damage to the slit 35 and its surrounding area in the restraining member 30 due to stiffening forces caused by deformation of higher-order buckling modes occurring at or near the boundary P between the wide portion 12 and the narrow portion 11 of the core material 10. Furthermore, as shown in Figure 4A, the first reinforcing member 60 abuts the entire longitudinal area of ​​the inner wall surface of the slit 35 (the entire area of ​​the side surface 35a and the bottom surface 35b), thereby increasing the overall load-bearing capacity of the slit 35 against stiffening forces acting from the core material 10.

[0059] On the other hand, Figures 4B to 4D show other examples of reinforcing members attached to the slit 35.

[0060] The example shown in Figure 4B is a configuration in which a second reinforcing member 60A (another example of a reinforcing member), consisting of a U-shaped piece 61A, abuts against a portion of the longitudinal central region of the inner wall surface of the slit 35, and has a length t2 that is shorter than the longitudinal length t1 of the slit 35.

[0061] Here, the length t2 is set, for example, by the amount of elongation of the narrow section 11 of the core material 10. As shown in Figure 6, when the length of the narrow section 11 in the longitudinal direction is L, the amount of elongation (Δ) can be set by the product of the length L or half of it, L / 2, and a predetermined strain (δ). Since there is a pair of wide sections 12 on both sides of the narrow section 11, and there are slits 35 at positions corresponding to the reinforcing ribs 14 in both wide sections 12 of the wooden restraint body 20, the total amount of elongation Δ of the narrow section 11 is L × δ, but using L when setting the amount of elongation Δ results in a design on the safe side.

[0062] When setting the elongation amount Δ, the strain can be set in the range of, for example, 0.015 (1.5% of length L) to 0.03 (3% of length L).

[0063] In the boundary region between the narrow section 11 and the wide section 12 of the core material 10, the stiffening force acting on the wooden restraint body 20 also increases due to stress concentration. Therefore, even if the narrow section 11 elongates, by arranging the second reinforcing member 60A in the central part of the slit 35 within a range determined by the amount of elongation of the narrow section 11, the resistance of the slit 35 to the stiffening force caused by the deformation of higher-order buckling modes occurring at or near the boundary P between the wide section 12 and the narrow section 11 can be increased.

[0064] As shown in Figure 4B, the second reinforcing member 60A is shorter in length than the reinforcing member 60, thus reducing the amount of steel required for manufacturing. Furthermore, the second reinforcing member 60A can increase the load-bearing capacity in the area of ​​the slit 35 where stiffening forces are likely to act from the core material 10.

[0065] On the other hand, in the example shown in Figure 4C, the third reinforcing member 60B (yet another example of a reinforcing member) is formed by a U-shaped piece 61B having a U-shaped cross-section, and the cross-sectional dimensions decrease toward the center in the longitudinal direction of the inner wall surface of the slit 35.

[0066] According to the third reinforcing member 60B, a U-shaped piece 61B is provided inside the slit 35, having a U-shaped cross-section and a shape in which the cross-sectional dimensions decrease toward the center in the longitudinal direction of the inner wall surface of the slit 35. As a result, the width of the U-shaped piece is wider at the end of the slit 35, which ensures clearance when additional bending is applied, and the amount of steel material required for manufacturing can be reduced as the cross-sectional dimensions of the U-shaped piece 61B decrease toward the center.

[0067] On the other hand, the example shown in Figure 4D is a fourth reinforcing member 60C (yet another example of a reinforcing member) which has a U-shaped piece 61 and an end piece 62 provided at the central end of the U-shaped piece 61, with the end piece 62 in contact with the central end face 35c of the slit 35. Here, the U-shaped piece 61 and the end piece 62 are joined to each other by welding.

[0068] The fourth reinforcing member 60C has a U-shaped piece 61 and an end piece 62 provided at the central end of the U-shaped piece 61, and the end piece 62 abuts against the central end face 35c of the slit 35. As a result, the rigidity of the fourth reinforcing member 60C is even higher than that of the first reinforcing member 60, and the load-bearing capacity of the slit 35 against the stiffening force acting from the core material 10 can be further increased.

[0069] Although not shown in the illustrations, the end pieces may be attached to the central end of the U-shaped piece 61A shown in Figure 4B or the U-shaped piece 61B shown in Figure 4C.

[0070] As shown in Figures 4A to 4D, by attaching reinforcing members 60, 60A, 60B, and 60C to the slits 35 of the restraint member 30, damage to the slits 35 and surrounding areas of the wooden restraint body 20 due to the stiffening force acting from the core material 10 can be effectively suppressed.

[0071] [Framework incorporating buckling-restrained braces] Next, an example of a building frame incorporating the buckling-restrained brace 100 will be described with reference to Figures 7 and 8. Here, Figure 7 shows the buckling-restrained brace according to the embodiment incorporated into the frame of a wooden building or the like. Figure 8 is a diagram illustrating the deformation of the frame during a major earthquake and the additional bending moment at the buckling-restrained brace joint caused by the deformation of the frame. Note that the buckling-restrained brace in the illustrated example may be incorporated not only into the frame of a wooden building, but also into the frame of a steel (S) building, a reinforced concrete (RC) building, or a steel-reinforced concrete (SRC) building.

[0072] The frame S shown in Figure 7 is formed by wooden columns C and beams B that make up a wooden building. Gusset plates GP made of flat steel are attached to the two diagonal corners. Fin stiffeners FS are welded to the surface of the gusset plates GP so as to be perpendicular to the surface. The fin stiffeners FS are joined to the gusset plates GP so that their center L3 intersects the intersection point O of the column center L1 of column C and the beam center L2 of beam B. The buckling-restrained braces 100 are also arranged linearly, passing through the intersection points O of both diagonally opposite positions.

[0073] The gusset plate GP and the wide portion 12 of the core material 10 are joined via a splice plate SP by high-tension bolts, and the fin stiffener FS and the reinforcing rib 14 are joined via a splice plate SP by high-tension bolts.

[0074] As shown in Figure 8, during a major earthquake, the structural plane deforms, and in the buckling-restrained brace joint, an additional bending moment shown in equation (1) below may act, assuming the joint is rigid.

[0075]

number

[0076] In the buckling-restrained brace 100, the core material 10 is restrained by a wooden restraint body 20 including a pair of wooden restraint members 30, thereby suppressing overall buckling of the buckling-restrained brace 100. Consequently, the buckling-restrained brace 100 has resistance to both overall buckling and higher-order buckling of the core material 10. Therefore, it becomes possible to form a frame S with excellent seismic resistance.

[0077] [Consideration of overall buckling] Next, we will explain a design method for preventing overall buckling of a buckling-restrained brace.

[0078] In designing buckling-restrained braces, the following equation (2) should be satisfied so that overall buckling of the buckling-restrained brace does not occur.

[0079]

number

[0080] Here, the bending moment acting at the center of the restraining member can be expressed by the following equation (3).

[0081]

number

[0082] The condition for preventing overall buckling of the wooden restraint body is that the following equation (4) is satisfied.

[0083]

number

[0084] Equation (4) is shown in Figure 9 as the overall buckling curve of the buckling-restrained brace. In Figure 9, the area above the overall buckling curve is the safety zone, and the area below is the danger zone. The design axial force of the wooden restraint, Euler load, length of the general part of the core material, and yield bending strength of the wooden restraint are set so that they fall within the safety zone. Note that the overall buckling curve of the buckling-restrained brace shown in Figure 9 is valid for both overall buckling in the weak axis direction and overall buckling in the strong axis direction of the core material.

[0085] In addition to examining the relationship between the yield bending strength of the wooden restraint and the bending moment acting on it, it is also advisable to examine that the short-term allowable bending strength of the wooden restraint is greater than the bending moment acting at the time of core material yielding (formulas omitted).

[0086] [Investigation of the failure of wooden restraints due to indentation] Next, with reference to Figure 10, we will explain the method for examining the failure of the wooden restraint body due to indentation. In the buckling-restrained brace 100, in order to prevent the wooden restraint body from failing due to the core material indenting into it, we must verify that the following equation (5) is satisfied.

[0087]

number

[0088] Here, in addition to checking the relationship between the indentation resistance of the restraining material and the stiffening force acting on it, it is also advisable to check that the short-term allowable indentation resistance of the restraining material is greater than the stiffening force acting at the time of core material yielding (formulas omitted).

[0089] 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]

[0090] 10: Core material 10a: Wide surface 10b:Narrow side 11: Narrow section 12: Wide section 12A: First wide section (wide section) 12B: Second wide section (wide section) 12a: Bolt hole 14: Reinforcement Ribs 14a: Bolt hole 20: Wooden restraints 30: Restraint material 31: Opposing surface 35: Slit (inner wall surface) 35a: Side 35b: Bottom 35c: End face 38: Shaft member (wood screw) 40: Side panel 50: Spacer 60: First reinforcing material (reinforcing material) 60A: Second reinforcing material (reinforcing material) 60B: Third reinforcing material (reinforcing material) 60C: Fourth reinforcing material (reinforcing material) 61, 61A, 61B: U-shaped piece 62: End piece 100: Buckling-restrained brace P: Boundary A: Plasticization region G1, G2: Gap S: Frame (composition) C: Pillar B: Beam GP: Gusset Plate FS: Finstiffna SP: Splice Plate

Claims

1. A steel, plate-shaped core material, It has a wooden restraint body, which is made of a pair of wooden restraint members and is arranged to face at least two wide surfaces of the core material, The core material has a narrow section at its longitudinal center where the width of the wide surface is relatively narrow, and a wide section at its longitudinal end where the width of the wide surface is relatively wide. The wide surface at the longitudinal end of the core material has reinforcing ribs joined to it perpendicular to the wide surface, so that the cross-sectional shape is cross-shaped. Of the pair of restraining members, a slit is provided at a position corresponding to the reinforcing rib that does not interfere with the reinforcing rib. A buckling-restrained brace characterized in that a reinforcing material is attached to the inner wall surface of the slit.

2. The cross-sectional shape of the inner wall surface of the slit is U-shaped, The buckling-restrained brace according to claim 1, characterized in that the reinforcing material consists of a U-shaped piece having a U-shaped cross-sectional shape complementary to the cross-sectional shape of the slit, and the U-shaped piece abuts over the entire longitudinal area of ​​the inner wall surface.

3. The cross-sectional shape of the inner wall surface of the slit is U-shaped, The buckling-restrained brace according to claim 1, characterized in that the reinforcing material consists of a U-shaped piece having a U-shaped cross-sectional shape complementary to the cross-sectional shape of the slit, and the U-shaped piece abuts against a portion of the central area in the longitudinal direction of the inner wall surface.

4. The buckling-restrained brace according to claim 3, characterized in that the portion of the central area to which the U-shaped piece abuts is determined by the amount of elongation of the narrow portion.

5. The cross-sectional shape of the inner wall surface of the slit is U-shaped, The buckling-restrained brace according to claim 1, characterized in that the reinforcing material consists of a U-shaped piece having a U-shaped cross-sectional shape, and the cross-sectional dimensions decreasing toward the center in the longitudinal direction of the inner wall surface.

6. The buckling-restrained brace according to any one of claims 2, 3, or 5, characterized in that the reinforcing member has a U-shaped piece and an end piece provided at the central end of the U-shaped piece, and the end piece abuts against the central end surface of the inner wall surface of the slit.

7. The wide portion comprises a first wide portion at the end and a second wide portion that is relatively narrower in width than the first wide portion. The second wide portion is continuous with the narrow portion, The end of the slit is located at an intermediate position in the second wide portion, The buckling-restrained brace according to any one of claims 2, 3, or 5, characterized in that bolt holes through which bolts are inserted when the brace is bolted to the frame are provided in the first wide portion.

8. The buckling restraint brace according to any one of claims 2, 3, or 5, characterized in that the wooden restraint body further comprises a pair of wooden side plates connecting the corresponding ends of a pair of restraint members.

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