Buckling-restrained brace

Abstract

To provide a buckling restrained brace suited to be used in an incorporated state in a frame of a wooden building or the like, and suppressed in manufacturing cost.SOLUTION: A buckling restrained brace 100 has: a steel plate-like core material 10; and a restriction material 20 having four wooden shaft materials 21 in which two wooden shafts 21 extending in a longitudinal direction of the core material 10 are adjacently arranged, on wide faces 11a, 12a of the core material 10, and jointing means 23 jointing the adjacent wooden shaft materials 21 with each other.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Conventionally, buckling-restrained braces provided with buckling prevention measures have been used as braces for forming building frames (column-beam frames, roof frames, etc.). Various stiffening configurations exist for buckling-restrained braces, including a configuration in which the periphery of a steel core material is stiffened only with a steel plate, a configuration in which the periphery of a steel core material is stiffened with RC (Reinforced Concrete), and a configuration in which the periphery of a steel core material is covered with a steel material and mortar.

[0003] In recent years, improvements in fire resistance and seismic performance of wooden buildings (wooden houses, wooden warehouses, wooden stadiums, etc.) have been pursued. Wooden houses inherently have advantages such as high flexibility in floor plans and designs, the healing effect of natural wood, the humidity control effect of wood, and generally lower construction costs compared to steel-framed structures and RC structures depending on the building use such as houses. The above-mentioned improvements in fire resistance and seismic performance are one of the factors increasing the attention toward wooden buildings including wooden houses. When the above-mentioned conventional buckling-restrained brace is incorporated into the frame of such a wooden house, wooden columns and beams and a buckling-restrained brace having a metal or concrete stiffening material are mixed, which inevitably results in an unbalanced appearance.

[0004] To address this, a measure has been considered in which the entire buckling-restrained brace is covered with a wooden or paper panel or the like to make the metal or concrete stiffening material invisible from the outside. However, this measure requires a great deal of work, so there is concern about an increase in construction costs. In addition, conventional buckling-restrained braces tend to be heavy because they frequently use metals, concrete, mortar, etc., and installing a heavy buckling-restrained brace in the lightweight wooden beams and columns that constitute a wooden house is structurally unbalanced.

[0005] Here, Patent Document 1 proposes a buckling-restrained brace suitable for use incorporated into the frame of wooden buildings, including wooden houses. 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, in which 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] Conventional buckling-restrained braces consist of a steel core surrounded by restraining plates, each made up of a pair of restraining plates facing the two wide surfaces of the core, and a pair of side plates connecting the ends of the restraining plates. However, these restraining plates and side plates each have their own unique cross-sectional shape and dimensions, and commonly available lumber cannot be used as is. As a result, the unit cost per unit area of ​​the restraining material is inevitably high, which often leads to high overall manufacturing costs for buckling-restrained braces.

[0008] This invention has been made in view of the above problems, and aims to provide a buckling-restrained brace that is suitable for use incorporated into the framework of wooden buildings and the like, and that can reduce manufacturing costs. [Means for solving the problem]

[0009] To achieve the above objective, one embodiment of the buckling-restrained brace according to the present invention is: A steel, plate-shaped core material, The present invention is characterized by having four wooden shafts, each of which two wooden shafts extending in the longitudinal direction of the core material are arranged adjacent to two wide surfaces of the core material, and a restraining member that includes connecting means for connecting adjacent wooden shafts to each other.

[0010] According to this embodiment, the restraining member that restrains the core material is formed by four wooden battens arranged on either side of the wide surface of the core material, and connecting means that connect adjacent wooden battens to each other. Since the wooden battens can be made of, for example, commonly available square timber, the manufacturing cost of the buckling-restrained brace is reduced. Here, wooden members other than commonly available square timber may be used for the wooden battens.

[0011] Furthermore, since the restraint member is formed from four wooden shank members, the processing of the restraint member becomes easier. For example, the buckling restraint brace described in Patent Document 1 requires processing laminated timber to produce two L-shaped restraint members, and then connecting them with the core material sandwiched between them by inverting them. In contrast, the buckling restraint brace of this embodiment is made by arranging four wooden shank members around a plate-shaped core material and connecting the wooden shank members to each other with connecting means to produce the restraint member, at which time the buckling restraint brace is produced. This makes the production of the buckling restraint brace even easier, and combined with the fact that the above-mentioned commonly available square timber can be used, the production cost of the buckling restraint brace can be reduced. Moreover, even if the wooden shank members are not made from commonly available square timber, this ease of production makes it possible to reduce production costs.

[0012] Furthermore, because the core material is surrounded by four wooden framing members, it becomes a buckling-restrained brace with excellent aesthetic design. Therefore, even when applied to the frame of a wooden building, there is no risk of it appearing inconsistent with the structural members.

[0013] In this embodiment, the connecting means include not only axial forms such as nails, bolts, and screws, but also staples and the like that have two piercing parts and are U-shaped.

[0014] Furthermore, other embodiments of the buckling-restrained brace according to the present invention include: The aforementioned wooden frame material is characterized by being a square timber.

[0015] According to this embodiment, the use of square timbers for the wooden frame results in a buckling-restrained brace with reduced manufacturing costs.

[0016] Furthermore, other embodiments of the buckling-restrained brace according to the present invention include: The aforementioned connecting means is characterized by being a staple.

[0017] According to this embodiment, since the connecting means is a staple, the wooden slats arranged horizontally are connected by a U-shaped staple extending in the direction of alignment. This eliminates the need for a long connecting means compared to, for example, using a axial screw or bolt, and allows the wooden slats to be connected with the shortest possible connecting means. Furthermore, since there is no risk of the connecting means connecting the four wooden slats becoming complex and tangled, manufacturability is improved, contributing to the formation of a buckling-restrained brace with excellent aesthetic design.

[0018] Here, the staples connect adjacent wooden timbers in a direction perpendicular to the longitudinal direction of the core material, and multiple staples may be arranged at intervals along the longitudinal direction. Alternatively, for example, multiple staples may be arranged in a V-shape or inverted V-shape along the longitudinal direction of the core material to form a staple truss. By forming a staple truss in this way, adjacent wooden timbers can be connected more firmly, and the cross-sectional rigidity of the restraining member can be increased.

[0019] Furthermore, in other embodiments of the buckling-restrained brace according to the present invention, A surface plate is attached around the four wooden shaft members to conceal the connecting means.

[0020] According to this embodiment, since a surface plate for concealing the connecting means is attached around the wooden shaft member, a buckling-restrained brace excellent in appearance design can be formed. Here, by applying a wooden board (decorative board) or the like to the surface plate, a buckling-restrained brace excellent in appearance design can be manufactured while suppressing material costs.

[0021] Furthermore, in another embodiment of the buckling-restrained brace according to the present invention, the surface plate is formed of plywood.

[0022] According to this embodiment, since the surface plate is formed of plywood, the appearance design can be improved. Furthermore, since plywood is formed by laminating and bonding single veneers (such as veneers obtained by peeling a log in the form of a keel) with different fiber directions, the rigidity of the restraining member can also be increased, which is preferable.

[0023] Furthermore, in another embodiment of the buckling-restrained brace according to the present invention, the core member has a narrow width portion where the width of the wide surface is relatively narrow on the central side in the longitudinal direction thereof, and has a wide width portion where the width of the wide surface is relatively wide on the end side in the longitudinal direction thereof, a first gap is provided between the end face of the wide width portion of the core member and the surface plate, and a second gap is provided between the end face of the narrow width portion of the core member and the surface plate, a spacer is interposed in the second gap, a friction reducing means for reducing the frictional force between the spacer and the narrow width portion is provided between the two.

[0024] In this embodiment, the core material has a narrow section with a relatively narrow width on the central side in its longitudinal direction, and a wide section with a relatively wide width on the end side in its longitudinal direction. This makes the narrow section on the central side a region that is easily plasticized, and furthermore, the plasticization region can be limited to the narrow section on the central side. In addition, since the boundary region between the wide section and the narrow section is a change region in which the planar area and cross-sectional area of ​​the core material change, the additional bending moment acting on the core material can be absorbed in this change region. An additional bending moment (or simply additional bending) is a bending moment that acts on the core material and the restraining member as a result of deformation, for example, when the frame and buckling-restrained brace deform significantly during a major earthquake. Thus, in this embodiment, it becomes possible to effectively absorb the additional bending moment acting on the core material in the boundary region between the wide section and the narrow section of the core material.

[0025] Furthermore, by having a first gap between the end face of the wide portion of the core material and the surface plate, when the frame into which the buckling-restrained brace is incorporated and the buckling-restrained brace deform within the frame plane, contact between the end face of the wide portion of the core material and the surface plate is eliminated or mitigated, thereby suppressing cracks that may occur in the surface plate due to this contact. Moreover, since the wooden frame members are arranged so as to sandwich the wide surface of the core material, there is no risk of interference between the end face of the wide portion of the core material and the wooden frame members during deformation within the frame plane.

[0026] Furthermore, a second gap is provided between the end face of the narrow section of the core material and the surface plate, and a spacer is interposed in the second gap, thereby preventing buckling of the core material in the strong axis direction (direction parallel to the wide surface). As previously described, the narrow section on the central side of the core material is a plastic deformation region, but by interposing a spacer between the end face of the narrow section of the core material and the surface plate, vibration energy during earthquakes and other events can be effectively absorbed by the plastic deformation of the narrow section of the core material while suppressing buckling of the core material in the strong axis direction. The spacer may be made of steel, a hard resin, or wood. In addition to a form in which the spacer has a length that extends over the entire narrow section of the core material, the spacer may also be made of two spacers that are half the length of the narrow section, or three spacers that are one-third the length of the narrow section.

[0027] Furthermore, by providing friction-reducing means between the spacer and the narrow portion of the core material to reduce the frictional force between them, when the core material buckles in a higher-order buckling mode in the strong axial direction, the frictional force between the end face of the narrow portion of the core material and the spacer during buckling deformation is reduced by the friction-reducing means. This frictional force is then transmitted to the surface plate via the spacer, and this frictional force acts on the surface plate as an axial force that was not considered in the design, thus preventing the surface plate from being damaged.

[0028] Furthermore, in other embodiments of the buckling-restrained brace according to the present invention, The friction-reducing means is characterized by having a curved end face that is convex toward the other side of at least one of the spacer or the narrow portion.

[0029] According to this embodiment, the friction-reducing means is a curved end face that is convex toward the other side of at least one of the spacer or the narrow section, so that the curved end face that is convex toward the other side makes line contact with the side surface (end face) of the other side. In this state, when the core material buckles in a higher-order buckling mode in the strong axis direction, the peak of the buckling deformation at the end of the narrow section and the end face of the spacer make point contact, and it is possible to significantly reduce the frictional force between the spacer and the end face of the narrow section of the core material compared to when they are in surface contact with each other.

[0030] Here, "a curved end face convex toward the other side on at least one of the spacer or the narrow section" includes forms in which the end face of the spacer is curved toward the narrow section, forms in which the end face of the narrow section is curved toward the spacer, and forms in which both end faces are curved toward the other. As mentioned above, since the spacer can be set to about 1 / 2 or 1 / 3 of the total length of the narrow section, from the viewpoint of machinability, it is preferable to make the end face of the relatively short spacer curved.

[0031] Furthermore, in other embodiments of the buckling-restrained brace according to the present invention, The friction-reducing means is characterized by being a round steel bar interposed between the end face of the spacer and the end face of the narrow portion.

[0032] According to this embodiment, since the friction reduction means is a round steel interposed between the end face of the spacer and the end face of the narrow section, when the core material buckles in a higher-order buckling mode in the strong axial direction, the peak of the buckling deformation at the end of the narrow section and the round steel make point contact, making it possible to significantly reduce the frictional force that can be transmitted from the narrow section to the spacer. As a result, the frictional force that can be transmitted from the spacer to the surface plate is reduced, and the unexpected axial force acting on the surface plate can be suppressed.

[0033] Furthermore, other embodiments of the buckling-restrained brace according to the present invention include: The present invention is characterized in that a pair of wooden shaft members, facing each other with the core material in between, are further connected by assembly bolts that pass through the second gap.

[0034] According to this embodiment, the assembly bolts that pass through the second gap further connect the pair of wooden shaft members facing each other with the core material in between, which is preferable because it improves the ease of assembly of the wooden shaft members (manufacturability of the restraining material), and the assembly bolts can function as a fail-safe for the connecting means (a backup connecting means in case of damage to the connecting means or release of the connection by the connecting means during deformation in the event of an earthquake).

[0035] Furthermore, in other embodiments of the buckling-restrained brace according to the present invention, The wide surface at the longitudinal end of the core material has reinforcing ribs joined to it perpendicular to the wide surface, giving it a cross-shaped cross-section. In the aforementioned wooden frame material, a notch is provided at a position corresponding to the reinforcing rib, which does not interfere with the reinforcing rib. The reinforcing rib is housed in a recess formed by the notch in the adjacent wooden frame, with a gap between them.

[0036] According to this embodiment, at the longitudinal end of the core material, reinforcing ribs perpendicular to the wide surface of the core material are joined, giving it a cross-shaped cross section. Therefore, when the buckling-restrained brace is attached to the gusset plate such that the wide surface of the core material is arranged parallel to the structural plane of the building, the core material has reinforcing ribs perpendicular to the wide surface parallel to the structural plane, thus increasing the rigidity in the outward direction of the structural plane 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, fin stiffeners are attached to the gusset plate, and the core material of the buckling-restrained brace and the gusset plate, and the reinforcing ribs and fin stiffeners are joined to each other via splice plates using high-tension bolts or the like.

[0037] Furthermore, notches are provided in the wooden frame members at positions corresponding to the reinforcing ribs, so as not to interfere with the reinforcing ribs. The reinforcing ribs are housed in recesses formed by the notches in adjacent wooden frame members with a gap between them. This prevents or suppresses damage to the restraint members caused by the reinforcing ribs coming into contact with and being pressed against them during deformation of the frame and buckling-restrained braces.

[0038] Furthermore, in other embodiments of the buckling-restrained brace according to the present invention, The invention is characterized in that a paint layer is formed on at least one of the wide surface of the core material and the contact surface of the wooden shaft that contacts the core material, in order to reduce the frictional force between them.

[0039] According to this embodiment, since a paint layer is formed on at least one of the wide surface of the core material and the contact surface of the wooden frame that abuts the core material, the frictional force between the wide surface of the core material and the contact surface of the wooden frame can be effectively reduced when the frame and buckling-restrained brace deform in the out-of-plane direction of the frame plane. This eliminates the risk that the deformation of the core material will be restrained due to frictional force, resulting in insufficient energy absorption during earthquakes.

[0040] Here, "a paint layer is formed on at least one of the wide surface of the core material and the contact surface of the wooden frame" includes forms in which a paint layer is formed only on the wide portion of the core material, forms in which a paint layer is formed only on the contact surface of the wooden frame, and forms in which a paint layer is formed on both. [Effects of the Invention]

[0041] As can be understood from the above explanation, the buckling-restrained brace of the present invention is suitable for use incorporated into the framework of wooden buildings and the like, and provides a buckling-restrained brace that can reduce manufacturing costs. [Brief explanation of the drawing]

[0042] [Figure 1] This is a perspective view showing an example of a core material forming a buckling-restrained brace according to the embodiment, together with friction-reducing means and spacers. [Figure 2] This is a perspective view of an example of a restraint material forming a buckling-restrained brace according to the embodiment. [Figure 3] This is a perspective view of an example of a buckling-restrained brace according to an embodiment. [Figure 4] This is a view from arrow IV-IV in Figure 3. [Figure 5] This is a view along the VV arrow in Figure 3. [Figure 6] This is a view along the line VI-VI in Figure 3. [Figure 7] This diagram illustrates the contact state between the core material and the round steel when the core material undergoes buckling deformation in a higher-order mode in the strong axis direction. [Figure 8]This figure shows the buckling-restrained brace according to the embodiment incorporated into the frame of a wooden building or the like. [Figure 9] 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 10] This figure shows the overall buckling curve of the buckling-restrained brace. [Modes for carrying out the invention]

[0043] 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.

[0044] [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 7. Here, Figure 1 is a perspective view showing an example of a core material forming a buckling-restrained brace according to the embodiment, together with friction-reducing means and spacers, and Figure 2 is a perspective view of an example of a restraining material forming a buckling-restrained brace according to the embodiment. Furthermore, Figure 3 is a perspective view of an example of a buckling-restrained brace according to the embodiment, and Figures 4, 5, and 6 are views taken along arrows IV-IV, VV, and VI-VI in Figure 3, respectively.

[0045] 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 t1 of the wide surface 11a is relatively narrow, and a wide section 12 at the end of its longitudinal direction where the width t2 of the wide surface 12a is relatively wide. Furthermore, reinforcing ribs 13 perpendicular to the wide surface 12a are welded to the wide surface 12a at the end of the core material 10 in the longitudinal direction, giving it a cross-shaped cross section. Here, the wide section 12 has a stepped (single-step) form where the width widens in a tapered manner from the narrow section 11, but it may also have a multi-step form where the width widens in two or more steps.

[0046] 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.

[0047] The core material 10 has a narrow section 11 on its longitudinal central side and a wide section 12 on its longitudinal end side. This makes the region A on the wide section side of the narrow section 11 located in the central side a region that is easily plasticized, and furthermore, this region A that is easily plasticized can be limited to the region on the wide section side of the narrow section 11.

[0048] Furthermore, bolt holes 12c and 13a are provided in the wide section 12 and the reinforcing rib 13, respectively, for bolt connection via splice plates to gusset plates provided on the structural surface and fin stiffeners attached to the gusset plates (see Figure 8), as described below.

[0049] When the buckling-restrained brace 100 is attached to the gusset plate such that the wide surfaces 11a and 12a of the core material 10 are arranged parallel to the structural plane of the building, the core material 10 has reinforcing ribs 13 perpendicular to the wide surfaces 11a and 12a that are 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.

[0050] A paint layer 15 is formed on the wide surface 11a of the narrow section 11. As shown in Figures 2, 5, and 6, the contact surface 21b of the wooden frame 21 comes into contact with the wide surface 11a. However, because the paint layer 15 is formed on the wide surface 11a, the frictional force between the wide surface 11a of the narrow section 11 and the contact surface 21b of the wooden frame 21 can be effectively reduced when the frame incorporating the buckling-restrained brace deforms in the out-of-plane direction of the frame surface. This eliminates the concern that the deformation of the core material 10 may be restrained due to the frictional force between the two, resulting in insufficient energy absorption during earthquakes.

[0051] Furthermore, instead of forming the paint layer 15 only on the wide surface 11a of the core material 10 as shown in the illustrated example, the paint layer may be formed on the contact surface 21b of the wooden frame material 21, or the paint layer may be formed on both the wide surface 11a and the contact surface 21b.

[0052] A second gap 16 is formed on the side of the narrow section 11 due to the difference in width between it and the wide section 12. First, a round steel bar 17 is placed in the X1 direction so as to abut against the end face 11b of the narrow section 11, and multiple spacers 18 (two in the illustrated example) are placed on the round steel bar 17 in the X2 direction, so that the second gap 16 is closed by the round steel bar 17 and the spacers 18.

[0053] Here, the spacer 18 is formed from a steel member, a hard resin member, a wooden member, or the like.

[0054] An assembly bolt 25, as shown in Figure 2, is inserted through the gap 19a between the two spacers 18, and another assembly bolt 25 is provided on the opposite side of the gap 19a in each spacer 18. In this illustrated example, two spacers 18 are arranged along the longitudinal direction of the narrow section 11, but a single relatively long spacer may be provided, or three or more relatively short spacers may be provided.

[0055] As shown in Figure 2, the restraining member 20, which is arranged around the core material 10 and restrains the core material 10, has a total of four wooden shaft members 21, each of which is arranged adjacent to a pair of wide surfaces 11a and 12a of the core material 10, and a plurality of connecting means 23 that connect adjacent wooden shaft members 21 to each other.

[0056] The connecting means 23 is formed by U-shaped staples. Multiple staples 23 connect adjacent wooden shaft members 21 in a direction perpendicular to the longitudinal direction of the core material 10, and the multiple staples 23 are arranged at intervals along the longitudinal direction.

[0057] Because the connecting means 23 is formed by a staple, the wooden shafts 21 that are aligned horizontally are connected by the connecting means that extends in the direction in which they are aligned. Therefore, compared to cases where shaft-shaped connecting means such as screws or bolts are used, there is no need to make the connecting means 23 long, and it becomes possible to connect the wooden shafts 21 with the shortest possible connecting means. In addition, since there is no risk of the connecting means 23 connecting the four wooden shafts 21 becoming intricately intertwined, the manufacturability is improved.

[0058] Here, the arrangement of the multiple clamps 23 may be in a configuration other than the illustrated example, such as being arranged in a V-shape or inverted V-shape along the longitudinal direction of the core material 10 to form a clamp truss. By forming a clamp truss in this way, adjacent wooden frame members 21 can be connected more firmly, and the cross-sectional rigidity of the restraining member can be increased.

[0059] The wooden frame 21 is formed from commonly available square timber. Examples of such square timber include solid wood such as cedar or pine, as well as laminated timber with laminated laminas, with a cross-section of 105mm (105mm square) or 120mm (120mm square). The length of the square timber 21 can be set to approximately 3m, for example, depending on the length of the core material 10. Forming the wooden frame 21 from square timber in this way is preferable because it reduces the manufacturing cost of the buckling-restrained brace.

[0060] The wooden frame member 21 has a contact surface 21b that abuts against the wide surfaces 11a and 12a of the core material 10, and an end surface 21a that abuts against the other adjacent wooden frame member 21. Notches 21c are provided at both ends of the wooden frame member 21 in the longitudinal direction. As shown in Figures 3 and 4, a recess 21g is formed by the notches 21c of both adjacent wooden frame members 21, and the reinforcing rib 13 is housed in the recess 21g with a gap between it and the wall surface of the recess 21g.

[0061] The wooden frame member 21 is provided with bolt holes 21e through which assembly bolts 25 are inserted, and counterbore grooves 21d at the ends of the bolt holes 21e. The assembly bolts 25 are inserted through the second gap 16 into the corresponding bolt holes 21e of the pair of wooden frame members 21 that sandwich the core material 10, and their heads 25a are accommodated in the counterbore grooves 21d of one of the wooden frame members 21. Furthermore, a fastening nut 26 is screwed onto the threaded groove at the other end, and the fastening nut 26 is accommodated in the counterbore grooves 21d of the other wooden frame member 21.

[0062] Four surface panels 28 are arranged around the outer circumference of four wooden frame members 21 and connected to the wooden frame members 21 with adhesive. In the illustrated example, the surface panels 28 are made of plywood.

[0063] By arranging the surface plate 28 around the outer periphery of the restraint member 20, the numerous staples 23 exposed on the outer surface of the wooden shaft member 21 can be concealed, leading to the formation of a buckling-restrained brace with excellent aesthetic design.

[0064] Furthermore, since the surface plate 28 is made of plywood, which is a laminate of veneers with different fiber directions, the rigidity of the restraining material 20 can be increased. If rigidity is not expected from the surface plate, a wooden board (decorative board) or the like may be used.

[0065] In the restraint member 20, in addition to adjacent wooden frame members 21 being connected by multiple staples 23, multiple assembly bolts 25 further connect a pair of wooden frame members 21 facing each other with the core material 10 in between. This improves the ease of assembly of the wooden frame members 21 (manufacturability of the restraint member 20), and it is preferable that the assembly bolts 25 function as a fail-safe for the staples 23 (a backup connecting means in case the staples 23 are damaged or the connection by the staples 23 is released during deformation caused by an earthquake).

[0066] Here, as a means of reducing friction, instead of the round steel shown in the illustrated example, at least one of the end faces of the spacer or the end face of the narrow section may be a curved end face that is convex toward the other side. In this form, even if the curved end face that is convex toward the other side is in contact with the other end face, it is normally in line contact, and during an earthquake, the peaks of the buckling deformation become point contact, leading to a reduction in frictional force.

[0067] As shown in Figure 3, the core material 10 is restrained by the restraining member 20, thereby forming a buckling-restrained brace 100.

[0068] As shown in Figure 4, at the longitudinal end of the core material 10, a first gap 21f is formed between the end face 12b of the wide portion 12 and the surface plate 28.

[0069] In this way, by providing a first gap 21f between the end face 12b of the wide portion 12 of the core material 10 and the surface plate 28, when the frame into which the buckling-restrained brace 100 (see Figure 3) is incorporated and the buckling-restrained brace 100 deform within the frame plane, contact between the end face 12b of the wide portion 12 of the core material 10 and the surface plate 28 is eliminated or mitigated, making it possible to suppress cracks that may occur in the surface plate 28 due to this contact.

[0070] Furthermore, a second gap 16 is provided between the end face 11b of the narrow portion 11 of the core material 10 and the surface plate 28, and a spacer 18 is interposed in the second gap 16, thereby preventing buckling of the core material 10 in the strong axis direction. As described above, the narrow portion 11 on the central side of the core material 10 has a plastic deformation region A, but by interposing the spacer 18 between the end face 11b of the narrow portion 11 of the core material 10 and the surface plate 28, vibration energy during earthquakes and the like can be effectively absorbed by the plastic deformation of the narrow portion 11 of the core material 10 while suppressing buckling of the core material 10 in the strong axis direction.

[0071] When the frame and buckling-restrained brace 100 deform during an earthquake, a compressive force N acts on the core material 10, as shown in Figure 7, and the core material 10 can buckle and deform in a higher-order buckling mode in its strong axis direction. If the end face 11b of the core material 10 and the end face of the spacer 18 are in surface contact, the frictional force generated between them is transmitted from the spacer to the surface plate, and this frictional force causes an unexpected axial force to act on the surface plate.

[0072] As shown in Figure 7, the presence of a round steel bar 17, which is a friction-reducing means, between the end face 11b of the narrow section 11 and the spacer 18 allows the core material 10 to buckle and deform in a higher-order buckling mode. This causes the peak of the buckling deformation 11' on the end face 11b of the narrow section 11 to make point contact with the round steel bar 17, significantly reducing the frictional force that can be transmitted from the narrow section 11 to the spacer 18. As a result, the frictional force that can be transmitted from the spacer 18 to the surface plate 28 is reduced, preventing unexpected axial forces from acting on the surface plate 28.

[0073] Here, we will outline the method for manufacturing the buckling-restrained brace 100. First, two adjacent wooden shaft members 21 are connected with multiple staples 23, and then the core material 10 is placed on the contact surfaces 21b of each wooden shaft member 21 so that the lower wide surfaces 11a and 12a of the core material 10 are in contact with each other.

[0074] Next, two separate wooden shaft members 21 are connected to each other with multiple clamps 23, and the two separate wooden shaft members 21 are placed on the wide upper surfaces 11a and 12a of the core material 10 so that their respective contact surfaces 21b are in contact with each other. Assembly bolts 25 are then inserted through the corresponding bolt holes 21e and fastened with fastening nuts 26.

[0075] Next, by connecting the pair of wooden shaft members 21 that sandwich the core material 10 with multiple staples 23, an intermediate body is produced in which four wooden shaft members 21 are connected by multiple staples 23 and multiple assembly bolts 25.

[0076] Finally, by bonding four surface plates 28 to the outer surface of the intermediate body, the buckling-restrained brace 100 shown in Figures 3 to 6 is fabricated.

[0077] [Example of applying buckling-restrained braces to a structural frame] Next, with reference to Figures 8 to 10, examples of the application of buckling-restrained braces to a frame will be described. Here, Figure 8 shows the buckling-restrained brace according to the embodiment incorporated into the frame of a wooden building or the like. Figure 9 illustrates 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.

[0078] The frame S shown in Figure 8 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.

[0079] The gusset plate GP and the wide portion 12 of the core material 10 are joined via the splice plate SP by high-tension bolts, and the fin stiffener FS and the reinforcing rib 13 are joined via the splice plate SP by high-tension bolts.

[0080] As shown in Figure 9, 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.

[0081]

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[0082] With the buckling-restrained brace 100, the core material 10, which has a cross-shaped cross-section, is surrounded by a restraining member 20 equipped with four wooden shaft members 21. This increases the rigidity of the frame S in both the in-plane and out-plane directions, making it possible to form a frame S with a high deformation suppression effect.

[0083] <Consideration of overall buckling> Next, we will explain a design method for preventing overall buckling of a buckling-restrained brace.

[0084] In designing buckling-restrained braces, the following equation (2) should be satisfied so that overall buckling of the buckling-restrained brace does not occur.

[0085]

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[0086] Here, the bending moment acting at the center of the wooden frame can be expressed by the following equation (3).

[0087]

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[0088] The condition for preventing overall buckling of the restraint material is that the following equation (4) is satisfied.

[0089]

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[0090] Equation (4) is shown in Figure 10 as the overall buckling curve of the buckling-restrained brace. In Figure 10, 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 restraining material, the Euler load, the length of the general part of the core material, and the yield bending strength of the restraining material are set so that they fall within the safety zone. Note that the overall buckling curve of the buckling-restrained brace shown in Figure 10 is valid for both overall buckling in the weak axis direction and overall buckling in the strong axis direction of the core material in a configuration in which the core material has a strong axis direction and a weak axis direction.

[0091] In addition to checking the relationship between the yield bending strength of the restraining material and the bending moment acting on it, it is also advisable to check that the short-term allowable bending strength of the restraining material is greater than the bending moment acting on it when the core material yields (formulas omitted).

[0092] <Investigation of indentation failure of wooden frame materials> Next, we will explain the method for examining the failure of the wooden frame due to the core material embedding into it. In order to prevent the wooden frame from failing due to the core material embedding into it, we must verify that the following equation (5) is satisfied.

[0093]

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[0094] In addition to examining the relationship between the indentation resistance of the wooden frame and the bracing force acting on it, it is also advisable to examine whether the short-term allowable indentation resistance of the wooden frame is greater than the bracing force acting at the time of core material yielding (formulas omitted).

[0095] 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]

[0096] 10: Core material 11: Narrow section 11a: Wide surface 11b: End face 12: Wide section 12a: Wide surface 12b: End face 12c: Bolt holes 13: Reinforcement Ribs 13a: Bolt hole 15:Paint layer 16: Second gap 17: Friction reduction means (round steel) 18: Spacer 20: Restraint material 21: Wooden frame 21a: End face 21b: Contact surface 21c: Notch 21d: Counterbore groove 21e: Bolt hole 21f: First gap 21g: recessed area 23: Connecting means (metal clamp) 25: Assembly bolts 26: Fastening nut 28: Surface panel (plywood) 100: Buckling-restrained brace A: Region that is easily plasticized (region that absorbs additional bending) S: Frame (composition) C: Pillar B: Beam GP: Gusset Plate FS: Finstiffna SP: Splice Plate

Claims

1. A steel, plate-shaped core material, A buckling-restrained brace characterized by having four wooden battens arranged adjacent to each of the two wide surfaces of the core material, with two wooden battens extending in the longitudinal direction of the core material, and a restraining member equipped with connecting means for connecting adjacent wooden battens to each other.

2. The buckling-restrained brace according to claim 1, characterized in that the aforementioned wooden frame member is a square timber.

3. The buckling-restrained brace according to claim 1 or 2, characterized in that the connecting means is a staple.

4. The buckling-restrained brace according to claim 1 or 2, characterized in that a surface plate is attached around the four wooden shaft members to conceal the connecting means.

5. The buckling-restrained brace according to claim 4, characterized in that the surface plate is made of plywood.

6. 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 core material has a first gap between the end face of the wide portion and the surface plate, and a second gap between the end face of the narrow portion and the surface plate. A spacer is interposed in the second gap, The buckling-restrained brace according to claim 4, characterized in that friction-reducing means are provided between the spacer and the narrow portion to reduce the frictional force between them.

7. The buckling-restrained brace according to claim 6, characterized in that the friction-reducing means is a curved end face that is convex toward the other side of at least one of the spacer or the narrow portion.

8. The buckling-restrained brace according to claim 6, characterized in that the friction-reducing means is a round steel bar interposed between the end face of the spacer and the end face of the narrow portion.

9. The buckling-restrained brace according to claim 6, characterized in that a pair of wooden shaft members facing each other with the core material in between are further connected by assembly bolts that pass through the second gap.

10. The wide surface at the longitudinal end of the core material has reinforcing ribs joined to it perpendicular to the wide surface, giving it a cross-shaped cross-section. In the aforementioned wooden frame material, a notch is provided at a position corresponding to the reinforcing rib, which does not interfere with the reinforcing rib. The buckling-restrained brace according to claim 1 or 2, characterized in that the reinforcing rib is housed in a recess formed by the notch of the adjacent wooden frame member with a gap between them.

11. The buckling-restrained brace according to claim 1 or 2, characterized in that a paint layer is formed on at least one of the wide surface of the core material and the contact surface of the wooden shaft that contacts the core material, for reducing the frictional force between them.

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