Buckling-restrained brace

Abstract

To provide a buckling-restrained brace that can effectively suppress the separation of restraining members even when the tensile force acting on the fasteners connecting the pair of restraining members during higher-order buckling of the core material causes the restraining members to separate. [Solution] The buckling-restraining brace 100 has a steel plate-shaped core material 10 and a wooden restraining body 20 formed by a pair of restraining members 30. The outer circumferential surface 31 of one restraining member 30A is provided with a plurality of countersunk grooves 34, and a first through hole 38 is provided that extends from each countersunk groove 34 to the contact surface 32. A lag screw bolt 50, equipped with male threads 51 and female threads 52, is embedded in the other restraining member 30B from the contact surface 32 to the interior, and a plurality of fasteners 60 are inserted through the corresponding first through holes 38 and screwed into the female threads 56.

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 covered 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 houses inherently have advantages such as a high degree of freedom in floor plans and designs, a soothing effect by natural wood, a humidity control effect of wood, and generally lower construction costs compared to steel frame or RC construction for building uses 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 houses. When incorporating the above-mentioned conventional buckling restraint braces into the structure of such wooden houses, 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 can 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 an increase in construction costs is a concern. 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 that make up a wooden house.

[0005] Here, Patent Document 1 proposes a structural member typified by a buckling-restrained brace. This structural member comprises a steel member of a predetermined length to be incorporated into a structure, and a stiffener made of a wood-based material that sandwiches the steel member while extending in the same direction as the steel member. The stiffeners that sandwich the steel member restrain it so that the steel member does not buckle as a whole when compressed in the longitudinal direction of the steel member, and end restraints are provided at both ends of the stiffeners in the longitudinal direction to restrain the steel member more strongly than at the center in the longitudinal direction.

[0006] In Patent Document 1, a pair of stiffeners made of wood-based material are bonded to each other with adhesive on the side of a steel member and fastened together with multiple bolts. For this bolt fastening, through holes are provided at corresponding positions on the pair of stiffeners, and counterbore grooves are provided on the outer surface of the stiffeners corresponding to the through holes. Washers are inserted on the heads of the bolts that are inserted through the through holes, and the bolts are fastened with nuts. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2020-148032 [Overview of the project] [Problems that the invention aims to solve]

[0008] According to the structural material described in Patent Document 1, the restraining portions provided at both ends in the longitudinal direction of the stiffeners provide stronger restraint between the stiffeners at both ends than in the longitudinal center of the stiffeners. Therefore, when the steel material is compressed in the longitudinal direction, if the curvature due to local buckling becomes large at both ends in the longitudinal direction of the steel material, even if the ends of the stiffeners are pushed apart by the curvature and subjected to high bearing stress, deformation and damage to the ends of the stiffeners can be suppressed.

[0009] Incidentally, when a frame incorporating buckling-restrained braces deforms during an earthquake, and the deformation of the frame causes, for example, the wide surface (weak axis direction) of the steel member (core member) of the buckling-restrained brace to deform in a higher-order buckling mode, the pair of stiffeners (restraining members) will try to separate from each other due to the local stiffening force (compression force) received from the core member undergoing higher-order buckling.

[0010] The present invention has been made in view of the above problems, and aims to provide a buckling-restrained brace that can effectively suppress the separation of a pair of restraining members when a stiffening force acts on a pair of restraining members due to higher-order buckling of the core material. [Means for solving the problem]

[0011] 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 aforementioned core material has a wooden restraint body which is formed by a pair of wooden restraint members that are wider than the core material and are arranged to face the two wide surfaces of the core material. In one of the restraining members, multiple counterbore grooves are provided on the lateral side of the region that sandwiches the core material. A first through-hole is provided in one of the restraining members, extending from each counterbore groove to the contact surface that contacts the core material. A lag screw bolt, having male threads on its outer circumference and female threads on its interior, is embedded in the contact surface of the other restraining member, from a position corresponding to the first through-hole in the contact surface that abuts against the core material, The pair of restraining members are joined by a plurality of fasteners, each having a head at one end of a shaft and a male screw at the other end of the shaft, which are loosely fitted into the corresponding first through holes and screwed into the female screw, and a washer is interposed between the head and the bottom surface of the counterbore groove.

[0012] According to this embodiment, a first through-hole is provided in one of the pair of restraining members forming a wooden restraint body, extending from a plurality of counterbore grooves to the contact surface with the core material. A lag screw bolt, having male threads on its outer circumference and female threads on its interior, is embedded in the contact surface of the other restraining member, from a position corresponding to the first through-hole. A fastener, having a head at one end of the shaft and male threads at the other end of the shaft, is inserted through each first through-hole and screwed into the corresponding female threads of the lag screw bolt. As a result, when a stiffening force acts on the pair of restraining members due to higher-order buckling of the core material, and the pair of restraining members tend to separate due to the stiffening force, the lag screw bolt with male threads on its outer circumference and the washer disposed on the bottom surface of the counterbore groove, with which the head of the fastener contacts, resist, effectively suppressing the separation of the restraining members.

[0013] Furthermore, since multiple fasteners are arranged at intervals on the lateral side of the core material held by the pair of restraining members, these fasteners can function as spacers to prevent misalignment of the core material between the contact surfaces of the pair of restraining members, thus eliminating the need for a separate spacer to prevent misalignment of the core material.

[0014] In this embodiment, a steel core is surrounded by a pair of wooden restraining members. This configuration ensures that even when the buckling-restrained brace of this embodiment is applied to the frame of a wooden building, it does not give an appearance that is inconsistent with the structural members. Here, the restraining members may be made of solid wood or of laminated timber with laminated laminas.

[0015] Furthermore, the fasteners include various types of bolts, such as wood screws and coach screw bolts. In this embodiment of the buckling-restrained brace, the connection between a pair of restraining members is, in principle, made only by multiple fasteners, and the number of man-hours during manufacturing can be reduced by eliminating the need for adhesive connections.

[0016] Furthermore, other embodiments of the buckling-restrained brace according to the present invention include: The pair of restraining members are further connected by a plurality of drift pins.

[0017] According to this embodiment, since the pair of restraint members are further connected by a plurality of drift pins, when the entire buckling-restrained brace deforms in accordance with the deformation of the frame, the plurality of drift pins function to suppress the relative displacement of the pair of restraint members. As a result, the pair of restraint members can deform as a single unit without shifting relative to each other, and it becomes possible to counteract and suppress the deformation of the buckling-restrained brace based on the overall rigidity of the wooden restraint body. However, if the pair of restraint members do shift relative to each other, the rigidity of each restraint member will be taken into consideration, and it will no longer be possible to counteract the deformation of the buckling-restrained brace based on the overall rigidity of the wooden restraint body.

[0018] Furthermore, in other embodiments of the buckling-restrained brace according to the present invention, A pair of wooden spacers are provided at the lateral positions between the pair of restraining members. The spacer is characterized in that, at positions corresponding to the multiple fasteners and the drift pin, multiple second through holes and third through holes are provided, and the fasteners and the drift pin pass through the second through holes and third through holes.

[0019] According to this embodiment, a pair of spacers are arranged on the side of the core material in the space between the contact surfaces of the pair of restraining members, and fasteners and drift pins are passed through the second and third through holes of the spacers to fix the spacers in place, thereby preventing displacement of the core material. Furthermore, since the core material is completely surrounded by the pair of restraining members and the pair of spacers, the steel core material can be completely concealed in the general part of the buckling-restrained brace, thereby improving the appearance and design of the buckling-restrained brace.

[0020] Furthermore, in other embodiments of the buckling-restrained brace according to the present invention, The pair of spacers are characterized in that they are bonded to the contact surface of one of the restraining materials.

[0021] According to this aspect, by adhering a pair of spacers to the contact surface of one of the restraint members, a core material is disposed between the pair of spacers, the other restraint member is covered, and the pair of restraint members are connected with fasteners or drift pins, the manufacturing efficiency when manufacturing the wooden restraint body and the buckling restraint brace can be improved.

[0022] Further, in another aspect of the buckling restraint brace according to the present invention, the core material includes a narrow-width portion having a relatively narrow width of the wide-width surface at the central side in the longitudinal direction thereof, and a wide-width portion having a relatively wide width of the wide-width surface at the end side in the longitudinal direction thereof, characterized in that the pair of spacers are disposed on the side of the narrow-width portion.

[0023] According to this aspect, since the core material has a narrow-width portion having a relatively narrow width of the wide-width surface at the central side in the longitudinal direction thereof, and a wide-width portion having a relatively wide width of the wide-width surface at the end side in the longitudinal direction thereof, the central narrow-width portion can be made into a region where plasticization is easy, and further, the plasticization region can be limited to the central narrow-width portion. In addition, since the boundary region between the wide-width portion and the narrow-width portion is a changing region where the planar area and the cross-sectional area of the core material change, the additional bending moment acting on the core material can be absorbed in this changing region.

[0024] Here, the additional bending moment (or simply, additional bending) is, for example, when the structure and the buckling restraint brace are greatly deformed during a large earthquake, a bending moment generated based on the supplementary stiffness force acting on the wooden restraint member due to this deformation. Thus, in this aspect, the additional bending moment generated in the core material can be effectively absorbed in the boundary region between the wide-width portion and the narrow-width portion of the core material.

[0025] Further, in another aspect of the buckling restraint brace according to the present invention, characterized in that a reinforcing shaft member extending from one side to the other side of a pair of side surfaces orthogonal to the contact surface is embedded inside the restraint member.

[0026] In this embodiment, a reinforcing shaft member is embedded inside the restraint material, extending from one side to the other of a pair of sides perpendicular to the contact surface, thereby increasing the rigidity of the restraint material, which is preferable. Examples of the reinforcing shaft member include screws and nails. Furthermore, "the reinforcing shaft member extends from one side to the other of a pair of sides" includes both a form in which the reinforcing shaft member extends across the pair of sides to the other side, and a form in which the reinforcing shaft member extends from one side but does not reach the other side.

[0027] Furthermore, other embodiments of the buckling-restrained brace according to the present invention include: The aforementioned counterbore groove is characterized by being sealed with a wooden plug.

[0028] According to this embodiment, since the counterbore groove is closed with a wooden plug, it is possible to prevent the head of the fastener from being exposed through the counterbore groove, thereby reducing the aesthetic appearance of the buckling-restrained brace. [Effects of the Invention]

[0029] As can be understood from the above explanation, according to the buckling-restrained brace of the present invention, a stiffening force acts on the pair of restraint members due to higher-order buckling of the core material, and this stiffening force effectively suppresses the separation of the pair of restraint members. [Brief explanation of the drawing]

[0030] [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 an exploded perspective view of a pair of restraint members forming a wooden restraint body. [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 taken along the line IV-IV in Figure 3, which is a longitudinal cross-sectional view in the short direction of an example of a buckling-restrained brace according to the embodiment. [Figure 5] Figure 3 is a view along the VV arrow, which is a longitudinal cross-sectional view of an example of a buckling-restrained brace according to the embodiment. [Figure 6]This diagram illustrates the function of preventing the pair of restraint members from separating when the core material undergoes higher-order buckling. [Figure 7] This figure shows an example of a 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]

[0031] 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.

[0032] [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, Figure 2 is an exploded perspective view of a pair of restraint members forming a wooden restraint body, and Figure 3 is a perspective view of an example of a buckling-restrained brace according to the embodiment. Furthermore, Figure 4 is a view taken along the line IV-IV in Figure 3, which is a longitudinal section view in the short direction of an example of a buckling-restrained brace according to the embodiment, and Figure 5 is a view taken along the line VV in Figure 3, which is a longitudinal section view in the long direction of an example of a buckling-restrained brace according to the embodiment.

[0033] 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.

[0034] 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).

[0035] 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.

[0036] 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).

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] On the other hand, as shown in Figure 2, a wooden restraint body 20 is formed by a pair of wooden restraint members 30 that are wider than the core material 10 and are arranged to face the two wide surfaces 10a of the core material 10.

[0042] 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.

[0043] A slit 36 ​​is provided in the contact surface 32 at the longitudinal end of the restraining member 30 that abuts against the core material 10. A portion of the reinforcing rib 14, which is joined to the end of the core material 10, is inserted through the slit 36, thereby preventing interference between the restraining member 30 and the reinforcing rib 14.

[0044] Furthermore, on the outer circumferential surface 31 of one of the restraining members 30A, a plurality of counterbore grooves 34 (six in the illustrated example) are provided along the longitudinal direction in the lateral position in the short direction of the region sandwiching the core material 10, and drift pin holes 35 are provided on the side of each counterbore groove 34. As shown in Figure 4, a plurality of first through holes 38 are provided inside the restraining member 30A, and each first through hole 38 is in communication with the corresponding counterbore groove 34.

[0045] Furthermore, multiple (six in the illustrated example) reinforcing shaft members 37 are driven into the interior of one of the restraining members 30A, extending from one side to the other of a pair of side surfaces 33 perpendicular to the contact surface 32. Here, screws, nails, etc., can be used as reinforcing shaft members 37.

[0046] In this way, the rigidity of the restraining member 30 is increased by providing a plurality of reinforcing shaft members 37 spaced apart in the longitudinal direction within the restraining member 30.

[0047] On the other hand, a pair of wooden spacers 40 are bonded to the lateral position in the shorter direction of the contact surface 32 of the other restraining material 30B in the region that sandwiches the core material 10.

[0048] In the spacer 40, a second through-hole 42 is provided at a position corresponding to each first through-hole 38 of the restraining material 30A, and a third through-hole 43 is provided at a position corresponding to each drift pin hole 35. Furthermore, as shown in Figure 4, the female thread 52 of a lag screw bolt 50 embedded in the restraining material 30B is connected to the position corresponding to the second through-hole 42 in the restraining material 30B.

[0049] As shown in Figure 4, when the pair of restraint members 30A and 30B are assembled to form the wooden restraint body 20, the corresponding counterbore groove 34 and the first through hole 38, the second through hole 42 of the spacer 40 and the female thread 52 of the lag screw bolt 50 are in communication with each other, and a bolt 60 (an example of a fastener) is inserted and screwed into it.

[0050] Furthermore, as shown in Figure 5, a drift pin hole 35B is provided in the other restraint member 30B at a position corresponding to the third through hole 43, and the drift pin hole 35A of the corresponding restraint member 30A, the third through hole 43 of the spacer 40, and the drift pin hole 35B of the restraint member 30B are in communication with each other, so that a drift pin 70 can be driven in.

[0051] Returning to Figure 2, the other restraint member 30B also has multiple (six in the illustrated example) reinforcing shaft members 37 embedded inside, extending from one side to the other of a pair of side surfaces 33 perpendicular to the contact surface 32.

[0052] As shown in Figure 3, a pair of restraint members 30 are arranged so as to sandwich a pair of wide surfaces 10a of the core material 10. Bolts 60 are inserted through the counterbore grooves 34, the first through hole 38, and the second through hole 42 of each pair, and the tips of the bolts 60 are screwed into the female threads 52. Drift pins 70 are driven into the drift pin holes 35A, the third through hole 43, and the drift pin hole 35B of each pair, thereby forming a wooden restraint body 20. The core material 10 is then surrounded by the wooden restraint body 20 to form a buckling restraint brace 100. Here, as shown in Figure 3, a reinforcing shaft member 37A extending in the weak axis direction is driven into the longitudinal end of the wooden restraint body 20, thereby integrating the longitudinal end of the wooden restraint body 20.

[0053] In the buckling-restrained brace 100, the pair of wide surfaces 10a of the core material 10 are in contact with the contact surfaces 32 of the pair of restraint materials 30, and the pair of narrow surfaces 10b are in contact with the pair of spacers 40, and the brace is surrounded and restrained by the wooden restraint body 20 and the spacers 40.

[0054] Here, the fastener 60 can be fitted with various bolts, including coach screw bolts, and can also be fitted with wood screws or other fasteners.

[0055] In the manufacture of this buckling-restrained brace 100, since a pair of spacers 40 are bonded to the contact surface 32 of one of the restraining members 30B, a core material 10 can be placed between the pair of spacers 40, the other restraining member 30A can be placed over it, and the pair of restraining members 30 can be connected with fasteners 60 and drift pins 70 to improve the manufacturing efficiency when producing the wooden restraining body 20 and the buckling-restrained brace 100.

[0056] As shown in Figure 3, a gap G1 of a predetermined width is provided between the slit 36 ​​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.

[0057] As already explained with reference to Figure 4, one restraining member 30A is provided with a first through hole 38 that communicates with a counterbore groove 34 facing the outer circumferential surface 31, and the other restraining member 30B is embedded with a lag screw bolt 50 with a female thread 52 that communicates with a second through hole 42 of a spacer 40 that is bonded to its contact surface 32.

[0058] The outer circumference of the lag screw bolt 50 is provided with a male thread 51, and it is screwed into a machined hole (not shown) that extends from the contact surface 32 of the restraining material 30B to the interior, thereby being embedded inside the restraining material 30B.

[0059] The bolt 60 has a shaft portion 61, a head portion 63 is provided at one end of the shaft portion 61, and a male thread 62 is provided at the other end of the shaft portion 61.

[0060] The bolt 60, inserted through the first through hole 38 via the counterbore groove 34, connects the pair of restraint members 30 with its head 63 in contact with the washer 65 located at the bottom of the counterbore groove 34, by screwing the male thread 62 into the female thread 52 of the lag screw bolt 50.

[0061] The head 63 of the bolt 60 housed in the counterbore groove 34 is concealed by inserting a wooden plug 39A above it. Furthermore, as shown in Figure 5, after the drift pins 70 are driven into the drift pin hole 35A, the third through hole 43, and the drift pin hole 35B, wooden plugs 39B are also inserted into the ends of the drift pin holes 35A and 35B to conceal the ends of the drift pins 70.

[0062] Next, referring to Figure 6, the effects of applying the lag screw bolt 50 shown in Figure 4 will be explained. Here, Figure 6 is a diagram illustrating the function of suppressing the separation of the pair of restraining members when the core material undergoes higher-order buckling.

[0063] During an earthquake, the core material 10, particularly the narrow section 11, absorbs seismic energy by undergoing higher-order buckling in the weak axis direction. A stiffening force P (compressive force) acts on the upper and lower restraint members 30A and 30B from the peak of the buckling during this higher-order buckling of the core material 10.

[0064] In this way, the stiffening force P applied from the core material 10 causes the upper and lower restraining members 30 to move away in the X direction, and a tensile force N is generated in the bolt 60.

[0065] In this case, a lag screw bolt 50, which is screwed into the interior of one restraint member 30B and has a male thread 51 on its outer circumference, and a washer 65, which is positioned at the bottom of the counterbore groove 34 of the other restraint member 30A, resist each other. A circumferential frictional force Q1 is exerted between the male thread 51 of the lag screw bolt 50 and the restraint member 30B in a direction that suppresses the separation of the pair of restraint members 30 (towards the core material 10), and the washer 65 similarly exerts a bearing pressure Q2 in a direction that suppresses the separation of the pair of restraint members 30, thereby preventing the restraint members 30 from separating from each other.

[0066] In this way, the lag screw bolt 50 and the washer 65 counteract the tensile force N acting on the bolt 60, effectively suppressing the separation of the restraining members 30.

[0067] Furthermore, in the buckling-restrained brace 100, the pair of restraint members 30 are further connected by multiple drift pins 70, and since the multiple drift pins 70 can suppress the mutual displacement of the pair of restraint members 30, the overall integrity of the wooden restraint body 20 during deformation can be guaranteed.

[0068] [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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072]

number

[0073] 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.

[0074] [Consideration of overall buckling] Next, we will explain a design method for preventing overall buckling of a buckling-restrained brace.

[0075] In designing buckling-restrained braces, the following equation (2) should be satisfied so that overall buckling of the buckling-restrained brace does not occur.

[0076]

number

[0077] Here, the bending moment acting at the center of the restraining member can be expressed by the following equation (3).

[0078]

number

[0079] The condition for preventing overall buckling of the wooden restraint body is that the following equation (4) is satisfied.

[0080]

number

[0081] 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.

[0082] 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).

[0083] [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 wooden restraints due to indentation. In buckling restraint braces 100, etc., in order to prevent the wooden restraint from failing due to the core material indenting into the wooden restraint, we verify that the following equation (5) is satisfied.

[0084]

number

[0085] 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).

[0086] 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]

[0087] 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 30,30A,30B:Restraint material 31: Outer surface 32: Contact surface 33: Side view 34: Counterbore groove 35, 35A, 35B: Drift pin holes 36: Slit 37,37A: Reinforcement shaft members 38: First through hole 39A, 39B: Wood plug 40: Spacer 42: Second through hole 43: Third through hole 50: Lag screw bolt 51: Male screw 52: Female thread 60: Bolt (fastener) 61: Shaft 62: Male screw 63:Head 65: Washer 70: Drift Pin 100: Buckling-restrained brace G1: Gap P: Stiffening force (pressing force) Q1: Circumferential friction force Q2: Support pressure S: Frame (composition) C: Pillar B: Beam GP: Gusset Plate FS: Finstiffna SP: Splice Plate

Claims

1. A steel, plate-shaped core material, The aforementioned core material has a wooden restraint body which is formed by a pair of wooden restraint members that are wider than the core material and are arranged to face the two wide surfaces of the core material. In one of the restraining members, multiple counterbore grooves are provided on the lateral side of the region that sandwiches the core material. A first through-hole is provided in one of the restraining members, extending from each counterbore groove to the contact surface that contacts the core material. A lag screw bolt, having male threads on its outer circumference and female threads on its interior, is embedded in the contact surface of the other restraining member, from a position corresponding to the first through-hole in the contact surface that abuts against the core material, A buckling-restraining brace characterized in that a plurality of fasteners, each having a head at one end of a shaft and a male screw at the other end of the shaft, are loosely fitted into the corresponding first through holes and screwed into the female screws, thereby joining the pair of restraining members, and a washer is interposed between the head and the bottom surface of the counterbore groove.

2. The buckling-restrained brace according to claim 1, characterized in that the pair of restraining members are further connected by a plurality of drift pins.

3. A pair of wooden spacers are provided at the lateral positions between the pair of restraining members. The buckling-restrained brace according to claim 2, characterized in that, among the spacers, a plurality of second through holes and a third through hole are provided at positions corresponding to a plurality of fasteners and a drift pin, and the fasteners and the drift pin pass through the second through hole and the third through hole.

4. The buckling-restrained brace according to claim 3, characterized in that the pair of spacers are bonded to the contact surface of one of the restraining members.

5. 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 buckling-restrained brace according to claim 4, characterized in that the pair of spacers are arranged on the side of the narrow portion.

6. The buckling-restrained brace according to claim 5, characterized in that a reinforcing shaft member is embedded inside the restraining material, extending along a pair of sides perpendicular to the contact surface.

7. The buckling-restrained brace according to claim 6, characterized in that the aforementioned counterbore groove is closed with a wooden plug.

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