Buckling-restrained brace

Abstract

To provide a buckling-restraining brace that can 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, without compromising the aesthetic appearance. [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. Multiple countersunk grooves 34 are provided on the outer circumferential surface 31 of one of the restraining members 30A. A first lag screw bolt 50A, equipped with a male thread 51 and a first through hole 52, is embedded in the restraining member 30A, extending from each countersunk groove 34 to the contact surface 32. A second lag screw bolt 50B, equipped with a male thread 55 and a female thread 56, is embedded in the other restraining member 30B from the contact surface 32 to the interior. Multiple fasteners 60 are inserted through the corresponding first through holes 52 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 the periphery of a steel core material is braced only with steel plates, a form in which the periphery of a steel core material is braced with RC (Reinforced Concrete), and a form in which the periphery of a steel core material is 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 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 a house. 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 brace into the structure of such a wooden house, it is inevitable that wooden columns and beams and a buckling restraint brace having a metal or concrete bracing material will coexist, resulting in an unbalanced appearance.

[0004] Therefore, a measure of covering the entire buckling restraint brace with a wooden or paper panel or the like so that the metal or concrete bracing material cannot be visually recognized from the outside can be considered. However, this measure requires a great deal of labor and 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 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 the steel members (core members) of the buckling-restrained braces, for example, the wide surface (weak axis direction), 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) from the core member undergoing higher-order buckling. This force causing the stiffeners to separate acts as a tensile force on the bolts connecting the two stiffeners, and the washers tightened by nuts resist this tensile force. However, if the area of ​​the washers is small compared to the tensile force, the washers may sink into the bottom surface of the counterbore grooves of the stiffeners, and the stiffeners may break due to insufficient sinking resistance. Therefore, in order to improve the sinking resistance of the stiffeners, measures are taken to increase the planar dimensions of the counterbore grooves and increase the area of ​​the washers.

[0010] However, applying a washer with a similarly large planar dimension to a counterbore groove with such a large planar dimension leads to a decrease in the aesthetic appearance of the buckling-restrained brace. Although Patent Document 1 does not provide specific details, even if the counterbore groove is closed with a wooden plug, a wooden plug with a large planar dimension will reduce the aesthetic appearance of the buckling-restrained brace.

[0011] The present invention has been made in view of the above problems, and aims to provide a buckling-restrained brace that can suppress the separation of restraining members without using washers with large planar dimensions, even when a pair of restraining members attempt to separate due to higher-order buckling of the core material and a tensile force acts on the fastener connecting the restraining members, without reducing the aesthetic appearance. [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, 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. On the outer surface of one of the restraining members, a plurality of counterbore grooves are provided at the lateral positions of the region that sandwiches the core material. A first lag screw bolt, having male threads on its outer circumference and a first through-hole inside, is embedded in one of the restraining members, extending from each counterbore groove to the contact surface that abuts against the core material. A second lag screw bolt, having male threads on its outer circumference and female threads on its interior, is embedded in the other restraining material from a position corresponding to the first lag screw bolt on the contact surface that abuts against the core material, The pair of restraining members are joined together 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, being inserted through the corresponding first through-hole and screwed into the female screw.

[0013] According to this embodiment, in one of the pair of restraining members forming a wooden restraint body, a plurality of first lag screw bolts, each having a first through hole, are embedded from a plurality of counterbore grooves in one of the restraining members to the contact surface with the core material, and a plurality of second lag screw bolts, each having a female thread, are embedded from a position corresponding to each first lag screw bolt in the contact surface with the core material of the other restraining member to the interior, and fasteners having a head at one end of the shaft and a male thread on the other end of the shaft are inserted through each first through hole and screwed into the corresponding female threads, so that when the pair of restraining members try to separate due to higher-order buckling of the core material and a tensile force acts on the fasteners connecting the restraining members, the first lag screw bolts and second lag screw bolts, each having a male thread on their outer circumference, resist the tensile force and suppress the separation of the restraining members. In this way, the tensile force is resisted by the first and second lag screw bolts, eliminating the need for sinking resistance at the bottom of the counterbore groove using a washer with a large planar dimension. Consequently, separation of the restraining members is suppressed, while also preventing a decrease in the aesthetic appearance of the buckling-restrained brace.

[0014] Furthermore, when the entire buckling-restrained brace deforms in accordance with the deformation of the frame, the first and second lag screw bolts also function to suppress the relative displacement of the pair of restraining members. As a result, the pair of restraining members can deform as a single unit without shifting relative to each other, and thus 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 restraining members were to shift relative to each other, the rigidity of each individual restraining member would be taken into consideration, and it would no longer be possible to counteract the deformation of the buckling-restrained brace based on the overall rigidity of the wooden restraint body.

[0015] Furthermore, since multiple fasteners are spaced apart 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.

[0016] 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.

[0017] 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.

[0018] Furthermore, other embodiments of the buckling-restrained brace according to the present invention include: 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. On the outer surface of one of the restraining members, a plurality of counterbore grooves are provided at the lateral positions of the region that sandwiches the core material. A first lag screw bolt having an external male thread on its outer periphery and a first through hole inside is embedded in a state of extending from each seating groove of one of the restraining members to the contact surface contacting the core material. A plurality of fasteners each having a head at one end of a shaft portion and a male thread on the other end side of the shaft portion are inserted through the corresponding first through holes and screwed into the other restraining member, whereby the pair of restraining members are joined.

[0019] According to this aspect, a plurality of first lag screw bolts having first through holes are embedded from a plurality of seating grooves in one of the pair of restraining members forming the wooden restraint body to the contact surface with the core material. When a tensile force acts on the fastener connecting the restraining members to prevent the pair of restraining members from separating due to buckling of the core material, the first lag screw bolt having an external male thread on its outer periphery and the other restraining member whose tip is screwed resist to suppress the separation of the restraining members. This eliminates the need for the indentation bearing capacity of the bottom surface of the seating groove using a washer with a large planar dimension. Therefore, while suppressing the separation of the restraining members, it is possible to prevent a decrease in the appearance design property of the buckling restraint brace.

[0020] Another aspect of the buckling restraint brace according to the present invention is characterized in that the pair of restraining members are further connected by a plurality of drift pins.

[0021] According to this aspect, since the pair of restraining members are further connected by a plurality of drift pins, when the entire buckling restraint brace is deformed according to the deformation of the structure, the plurality of drift pins exhibit a function of suppressing the relative displacement of the pair of restraining members. Therefore, the pair of restraining members can be deformed integrally without shifting relative to each other, and it becomes possible to resist the deformation of the buckling restraint brace based on the overall rigidity of the wooden restraint body and suppress the deformation.

[0022] Also, in another aspect of the buckling restraint brace according to the present invention, At the lateral position between the pair of restraining members, a pair of wooden spacers are disposed. Among the spacers, a plurality of second through-holes and third through-holes are provided at positions corresponding to the plurality of fasteners and the drift pins respectively, and the fasteners and the drift pins penetrate through the second through-holes and the third through-holes.

[0023] According to this aspect, among the spaces between the abutting surfaces of the pair of restraining members, a pair of spacers are disposed on the side of the core material. By fixing the spacers by penetrating the fasteners and the drift pins through the second through-holes and the third through-holes of the spacers, displacement of the core material can be prevented. Furthermore, since the core material is completely surrounded by the pair of restraining members and the pair of spacers, the steel core material in the general part of the buckling restraining brace can be completely concealed, and the appearance design property of the buckling restraining brace can be further enhanced.

[0024] Also, in another aspect of the buckling restraining brace according to the present invention, the pair of spacers are adhered to the abutting surface of one of the restraining members.

[0025] According to this aspect, by adhering the pair of spacers to the abutting surface of one of the restraining members, the core material is disposed between the pair of spacers, the other restraining member is covered, and the pair of restraining members are connected by fasteners and drift pins, so that the manufacturing efficiency when manufacturing the wooden restraining body and the buckling restraining brace can be improved.

[0026] Also, in another aspect of the buckling restraining brace according to the present invention, the core material includes a narrow-width portion where the width of the wide-width surface is relatively narrow at the central side in the longitudinal direction thereof, and includes a wide-width portion where the width of the wide-width surface is relatively wide at the end side in the longitudinal direction thereof. The pair of spacers are disposed on the side of the narrow-width portion.

[0027] According to 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.

[0028] Here, the additional bending moment (or simply additional bending) refers to the bending moment that arises when, for example, a large earthquake causes significant deformation of the frame and buckling-restrained braces, resulting in a stiffening force acting on the wooden restraint members. Thus, in this embodiment, the additional bending moment generated in the core material can be effectively absorbed at the boundary region between the wide and narrow sections of the core material.

[0029] Furthermore, in other embodiments of the buckling-restrained brace according to the present invention, The restraining material is characterized in that a reinforcing shaft member is embedded inside it, extending from one side to the other of a pair of sides perpendicular to the contact surface.

[0030] 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.

[0031] Furthermore, other embodiments of the buckling-restrained brace according to the present invention include: The head of the fastener and the end of the first lag screw bolt are in metal-to-metal contact. The aforementioned counterbore groove is characterized by being sealed with a wooden plug.

[0032] According to this embodiment, the head of the fastener and the end of the first lag screw bolt are in metal-to-metal contact, thereby eliminating the need for a washer and transmitting the tensile force of the fastener to the first lag screw bolt, thereby preventing the pair of restraining members from separating due to the first and second lag screw bolts. Furthermore, the counterbore groove only needs to have a small planar dimension, and the planar dimension of the wooden plug fitted into this counterbore groove is also naturally small, so there is no risk that the counterbore groove and the wooden plug that closes it will detract from the aesthetic appearance of the buckling-restrained brace.

[0033] Furthermore, other embodiments of the buckling-restrained brace according to the present invention include: A washer is interposed between the head of the fastener and the end of the first lag screw bolt. The aforementioned counterbore groove is characterized by being sealed with a wooden plug.

[0034] According to this embodiment, although a washer is interposed between the head of the fastener and the end of the first lag screw bolt, the first lag screw bolt and the second lag screw bolt, or the first lag screw bolt and the other restraining member, resist the tensile force of the fastener, thereby preventing the pair of restraining members from separating. Therefore, it is not necessary to increase the planar dimensions of the counterbore groove and the washer to improve the indentation resistance of the restraining members. Consequently, the planar dimensions of the wooden plug fitted into this counterbore groove are also naturally reduced, so the counterbore groove and the wooden plug that closes it do not detract from the aesthetic appearance of the buckling-restrained brace. [Effects of the Invention]

[0035] As can be understood from the above explanation, the buckling-restrained brace of the present invention can suppress the separation of the restraining members even when a pair of restraining members attempt to separate due to higher-order buckling of the core material and a tensile force acts on the fastener connecting the restraining members, without using washers with large planar dimensions, and can provide a buckling-restrained brace that does not degrade the appearance and design. [Brief explanation of the drawing]

[0036] [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 4A] 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 4B] 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 another 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]

[0037] 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.

[0038] [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 a core material forming a 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 4A 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.

[0039] 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.

[0040] 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).

[0041] 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.

[0042] 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).

[0043] 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.

[0044] 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.

[0045] 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.

[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] 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.

[0048] 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.

[0049] 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.

[0050] 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, through holes 52 of the first lag screw bolt 50A embedded in the restraining member 30A are connected to each counterbore groove 34.

[0051] 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.

[0052] 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.

[0053] On the other hand, a pair of wooden spacers 40 are bonded to the lateral position in the shorter direction of the region of the contact surface 32 of the other restraining material 30B that sandwiches the core material 10.

[0054] In the spacer 40, second through holes 42 are provided at positions corresponding to each first lag screw bolt 50A of the restraining material 30A, and third through holes 43 are provided at positions corresponding to each drift pin hole 35. Furthermore, as shown in Figure 4, the female threads 56 of the second lag screw bolts 50B embedded in the restraining material 30B are in communication with the positions corresponding to the second through holes 42 in the restraining material 30B.

[0055] 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 grooves 34 communicate with the first through hole 52 of the first lag screw bolt 50A, the second through hole 42 of the spacer 40, and the female thread 56 of the second lag screw bolt 50B, respectively, so that a bolt 60 (an example of a fastener) can be inserted and screwed in.

[0056] 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.

[0057] 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.

[0058] 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 52, and the second through hole 42 of each pair, and the tips of the bolts 60 are screwed into the female threads 56. 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.

[0059] 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 restraining 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 restraining body 20 and the spacers 40.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] As already explained with reference to Figure 4A, one restraining member 30A has a first through-hole 52 of the first lag screw bolt 50A embedded in it so as to communicate with a counterbore groove 34 facing the outer surface 31, and the other restraining member 30B has a second lag screw bolt 50B embedded in it so as to communicate with a second through-hole 42 of a spacer 40 that is bonded to its contact surface 32.

[0064] The first lag screw bolt 50A has a male thread 51 on its outer circumference and is embedded inside the restraining material 30A by being screwed into a machined hole (not shown) provided in the restraining material 30A. On the other hand, the second lag screw bolt 50B also has a male thread 55 on its outer circumference and is embedded inside the restraining material 30B by being screwed into a machined hole (not shown) provided from the contact surface 32 of the restraining material 30B to the interior.

[0065] 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.

[0066] The bolt 60, inserted through the first through-hole 52 via the counterbore groove 34, connects the pair of restraint members 30 with a head 63 in a metal-to-metal contact position with the upper end 53 of the first lag screw bolt 50A, as the male thread 62 of the bolt is screwed into the female thread 56 of the second lag screw bolt 50B.

[0067] Here, although not shown in the diagram, instead of the head 63 of the bolt 60 and the upper end 53 of the first lag screw bolt 50A making metal-to-metal contact, a washer (not shown) may be interposed between them.

[0068] The head 63 of the bolt 60 housed in the counterbore groove 34 is concealed by inserting a wooden plug 38 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 39 are also inserted into the ends of the drift pin holes 35A and 35B to conceal the ends of the drift pins 70.

[0069] Here, Figure 4B is a longitudinal section view in the short direction of another example of a buckling-restrained brace according to the embodiment, and is shown in an embodiment corresponding to Figure 4A.

[0070] One of the restraining members 30B of the wooden restraining body 20 that forms the buckling restraining brace 100A shown in the figure differs from the buckling restraining brace 100 in that it does not have a second lag screw bolt 50B, and the male thread 62 at the tip of the bolt 60 is directly screwed into the inside of the restraining member 30B.

[0071] The buckling-restrained brace 100A eliminates the need for the second lag screw bolt 50B while firmly connecting the pair of restraining members 30, thereby reducing the manufacturing cost of the buckling-restrained brace 100A.

[0072] Next, referring to Figure 6, the effects of applying the first lag screw bolt 50A and the second lag screw bolt 50B shown in Figure 4A 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.

[0073] 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.

[0074] 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.

[0075] In this case, the first lag screw bolt 50A and the second lag screw bolt 50B, which are screwed into the inside of the pair of restraining members 30 and have male threads 51 and 55 on their outer circumference, resist and exert a circumferential friction force Q in a direction that suppresses the separation of the pair of restraining members 30 (towards the core material 10), thereby suppressing the separation of the restraining members 30 from each other.

[0076] In this way, the pair of first lag screw bolts 50A and second lag screw bolts 50B resist the tensile force N acting on the bolt 60. This eliminates the need to, for example, apply a washer with a large planar dimension to a counterbore groove with a large planar dimension to increase the indentation resistance of the counterbore groove while resisting the tensile force N. Thus, it also prevents a decrease in the aesthetic appearance of the buckling-restrained brace caused by the large planar dimension of the counterbore groove and the large planar dimension of the wooden plug fitted inside it.

[0077] Furthermore, when the entire buckling-restrained brace 100 deforms in accordance with the deformation of the frame, the first lag screw bolt 50A and the second lag screw bolt 50B also function to suppress the relative displacement of the pair of restraint members 30. As a result, the pair of restraint members 30 can deform as a single unit without shifting relative to each other, and thus it becomes possible to counteract and suppress the deformation of the buckling-restrained brace 100 based on the overall rigidity of the wooden restraint body 20.

[0078] In the illustrated buckling-restrained brace 100, the pair of restraint members 30 are further connected by a plurality of drift pins 70. The plurality of drift pins 70 further suppress the mutual displacement of the pair of restraint members 30, thereby more reliably ensuring the overall integrity of the wooden restraint body 20 during deformation.

[0079] Furthermore, in the buckling-restrained brace 100A shown in Figure 4B, the tensile force N acting on the bolt 60 is counteracted by the circumferential friction force of the first lag screw bolt 50A and the circumferential friction force at the threaded portion between the male thread 62 of the bolt 60 and the restraining material 30B.

[0080] [Structure 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.

[0081] 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.

[0082] The gusset plate GP and the wide portion 12 of the core material 10 are joined via a splice plate SP using high-tension bolts, and the fin stiffener FS and the reinforcing rib 14 are joined via a splice plate SP using high-tension bolts.

[0083] 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.

[0084]

number

[0085] 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.

[0086] [Consideration of overall buckling] Next, we will explain a design method for preventing overall buckling of a buckling-restrained brace.

[0087] In designing buckling-restrained braces, the following equation (2) should be satisfied so that overall buckling of the buckling-restrained brace does not occur.

[0088]

number

[0089] Here, the bending moment acting at the center of the restraining member can be expressed by the following equation (3).

[0090]

number

[0091] The condition for preventing overall buckling of the wooden restraint body is that the following equation (4) is satisfied.

[0092]

number

[0093] 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.

[0094] 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).

[0095] [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.

[0096]

number

[0097] 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).

[0098] 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]

[0099] 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 38,39: Wood plug 40: Spacer 42: Second through hole 43: Third through hole 50A: First lag screw bolt 50B: Second lag screw bolt 51: Male screw 52: First through hole 53:Top edge 55: Male screw 56: Female thread 60: Bolt (fastener) 61: Shaft 62: Male screw 63:Head 70: Drift Pin 100,100A: Buckling-restrained brace G1: Gap P: Stiffening force (pressing force) Q: Circumferential friction force 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. On the outer surface of one of the restraining members, a plurality of counterbore grooves are provided at the lateral positions of the region that sandwiches the core material. A first lag screw bolt, having male threads on its outer circumference and a first through-hole inside, is embedded in one of the restraining members, extending from each counterbore groove to the contact surface that abuts against the core material. A second lag screw bolt, having male threads on its outer circumference and female threads inside, is embedded in the other restraining member from a position corresponding to the first lag screw bolt on the contact surface that abuts against the core material, A buckling-restraining brace characterized in that a 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, being inserted through the corresponding first through-hole and screwed into the female screw.

2. 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. On the outer surface of one of the restraining members, a plurality of counterbore grooves are provided at the lateral positions of the region that sandwiches the core material. A first lag screw bolt, having male threads on its outer circumference and a first through-hole inside, is embedded in one of the restraining members, extending from each counterbore groove to the contact surface that abuts against the core material. A buckling-restraining brace characterized in that a 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, being screwed into the other restraining member by being inserted through the corresponding first through hole.

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

4. A pair of wooden spacers are provided at the lateral positions between the pair of restraining members. The buckling-restrained brace according to claim 3, 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.

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

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

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

8. The head of the fastener and the end of the first lag screw bolt are in metal-to-metal contact. The buckling-restrained brace according to claim 7, characterized in that the aforementioned counterbore groove is closed with a wooden plug.

9. A washer is interposed between the head of the fastener and the end of the first lag screw bolt. The buckling-restrained brace according to claim 7, characterized in that the aforementioned counterbore groove is closed with a wooden plug.

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