Buckling Restrained Brace

Abstract

To provide a buckling restraint brace which is suitable for use by being incorporated in a frame structure of a wooden building or the like, and deforms the frame structure and the buckling restraint brace out of the structure plane, for example, in the event of a large earthquake, and in which a core forming the buckling restraint brace presses into a restraint plate forming a wooden restraint material to eliminate generation of cracks in a side plate pulled by the restraint plate.SOLUTION: A buckling restraint brace 100 includes: a steel plate-shaped core 10; and a wooden restraint material 20 formed by a pair of wooden restraint plates 21 placed to face two wide surfaces 11a of the core 10, and a pair of wooden side plates 22 placed to face two narrow surfaces 11b of the core 10 and connected to the pair of restraint plates 21. Ends of the pair of restraint plates 21 are connected by an end restraint material 29A.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

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

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

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

[0005] Therefore, a buckling-restrained brace suitable for use in the framework of wooden buildings such as wooden houses has been proposed. Specifically, this is a buckling-restrained brace that has a core material and a pair of restraint members arranged along both sides of the core material, where the core material is made of steel and the pair of restraint members are made of wood, and the restraint members are made of laminated lumber, with the laminated lumber having lamina stacked parallel to the core material (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

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

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

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

[0009] In order to achieve the above object, one aspect of the buckling restrained brace according to the present invention is as follows: A steel plate-shaped core material, a wooden restraining member formed by a pair of wooden restraining plates arranged so as to face the two wide surfaces of the core material, and a pair of wooden side plates arranged so as to face the two narrow surfaces of the core material and connected to the pair of restraining plates; The ends of the pair of restraining plates are connected by an end restraining member.

[0010] According to this aspect, the ends of the pair of wooden restraint plates, which together with a pair of wooden side panels form a wooden restraint material, are connected and reinforced by end restraint materials. This makes it possible to suppress cracks (splitting) that may occur at the ends of the side panels connected at positions corresponding to the ends of the pair of restraint plates that receive the strongest pushing force from the core material when the frame and buckling restraint brace are deformed outside the structural plane.

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

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

[0013] In another aspect of the buckling restrained brace according to the present invention, The end restraint member is a rivet.

[0014] According to this aspect, since the end restraint material is a clamp, the ends of a pair of restraint plates can be firmly fixed together using commonly available, inexpensive materials, thereby making it possible to suppress cracks that may occur at the ends of the side plates.

[0015] In another aspect of the buckling restrained brace according to the present invention, The two piercing portions of the clamp are driven into and fixed to the pair of restraint plates, or the two piercing portions of the clamp are inserted into fixing holes opened in the pair of restraint plates and adhesively fixed.

[0016] According to this aspect, the fastener can be fixed to the restraint plate in either one of two ways: by hammering the piercing portion of the fastener into the restraint plate, or by inserting the piercing portion into a fixing hole in the restraint plate and adhesively fixing the fastener. In either way, the fastener can be firmly fixed to the end of the restraint plate.

[0017] For example, in a configuration in which the piercing portions of the fasteners are driven in and fixed, the fasteners can be easily fixed to the ends of the restraining plates. Here, the piercing portions of the fasteners are pierced into the ends of the side plates and then into the ends of the restraining plates. That is, the two piercing portions of the U-shaped fasteners are pierced near both ends of the side plates and then into the end faces of the pair of restraining plates, so that the ends of both the side plates and the pair of restraining plates are fixed via the fasteners.

[0018] On the other hand, in a configuration in which the piercing portions are inserted into fixing holes opened in the restraint plates and adhesively fixed, there is no risk of damaging the ends of the side plates or the restraint plates due to the driving force when driving the nails, and the initial rigidity of both the side plates and the restraint plates around the points of fixation by the nails can be maintained. That is, fixing holes that communicate with both are fixed in the vicinity of both ends of the side plates and in the end faces of the pair of restraint plates, and the piercing portions of the nails are inserted into the fixing holes and adhesively fixed, so that the piercing portions are adhesively fixed to both the side plates and the restraint plates, and the ends of both the side plates and the pair of restraint plates are fixed via the nails.

[0019] In another aspect of the buckling restrained brace according to the present invention, The end restraint material is one or more strip-shaped steel plates or fiber reinforcement materials that span a pair of restraint plates, and the steel plates or fiber reinforcement materials are connected to the pair of restraint plates, or the pair of restraint plates are indirectly connected to each other by connecting multiple steel plates or multiple fiber reinforcement materials to each other.

[0020] According to this aspect, the end restraint members are one or more strip-shaped steel plates or fiber reinforcement members that span the pair of restraint plates, thereby firmly reinforcing the ends of the restraint plates by wrapping the pair of restraint plates and the pair of side plates (wooden restraint members) together. Here, the steel plates or fiber reinforcement members may be wrapped across the pair of restraint plates and directly connected to the ends of the restraint plates. Alternatively, for example, two steel plates may be wrapped around the periphery of the wooden restraint member and the ends of the two steel plates may be connected to indirectly restrain (reinforce) the ends of the restraint plates. Examples of fiber reinforcement members include fiber-reinforced plastic plates such as carbon fiber reinforced plastics (CFRP) and glass fiber reinforced plastics (GFRP), and fiber-reinforced plastic sheets such as carbon fiber reinforced plastic sheets and glass fiber reinforced plastic sheets.

[0021] In another aspect of the buckling restrained brace according to the present invention, a non-contact groove that does not come into contact with the wide surface of the core material is provided at an end of the restraint plate; The area of ​​the restraint plate other than the non-contact groove is in contact with the wide surface of the core material.

[0022] According to this aspect, the end of the restraint plate is provided with a non-contact groove that does not contact the wide surface of the core material, and the area of ​​the restraint plate other than the non-contact groove is in contact with the wide surface of the core material. Therefore, when the frame and the buckling restrained brace deform outward from the structural plane, the non-contact groove is provided at the end of the restraint plate that receives the strongest pushing force from the core material. This eliminates or reduces contact between the core material and the restraint plate, thereby suppressing cracks that may occur in the end of the side plate connected to the position corresponding to the end of the restraint plate. In particular, the aforementioned configuration in which the end of the pair of restraint plates (and the end of the side plate) are connected by the end restraint member, combined with the configuration in which the non-contact groove is provided at the end of the restraint plate that does not contact the wide surface of the core material, further enhances the effect of suppressing cracks that may occur in the end of the side plate. Here, non-contact grooves are provided at each end of the pair of restraint plates facing the two wide surfaces of the core material in areas where the core material may abut against the restraint plate when the buckling restrained brace deforms outward from the structural plane.

[0023] The non-contact grooves at the ends of the restraint plate eliminate or reduce contact (prevent strong contact) between the ends of the restraint plate and the core material, while the areas of the restraint plate other than the non-contact grooves abut against the core material, ensuring that the restraint plate prevents the core material from buckling.

[0024] In another aspect of the buckling restrained brace according to the present invention, the core material has a narrow portion at a center side in a longitudinal direction where the width of the wide surface is relatively narrow, and a wide portion at an end side in a longitudinal direction where the width of the wide surface is relatively wide, The non-contact groove extends from an edge of the restraint plate to a position corresponding to the boundary between the wide portion and the narrow portion of the core material.

[0025] According to this aspect, the core material has a narrow portion at the center of its longitudinal direction, where the width of the wide surface is relatively narrow, and a wide portion at its longitudinal end, where the width of the wide surface is relatively wide. This allows the narrow portion at the center to be a region that is easily plasticized, and further allows the plasticization region to be limited to the narrow portion at the center. Furthermore, the boundary region between the wide portion and the narrow portion is a transition region where the planar area and cross-sectional area of ​​the core material change, so that this transition region can absorb additional bending moments acting on the core material. Additional bending moments (or simply, additional bending) refer to bending moments that can act on the wooden restraint material due to large deformation of the frame and buckling-restrained braces, for example, during a major earthquake. Thus, in this aspect, additional bending moments acting on the core material can be effectively absorbed by the boundary region between the wide portion and the narrow portion of the core material.

[0026] While the core material has a wide section and a narrow section, the restraint plate has a non-contact groove extending from its edge to a position corresponding to the boundary between the wide section and the narrow section of the core material, thereby making it possible to eliminate with a high degree of certainty the contact (pushing) of the core material against the end of the restraint plate.

[0027] In another aspect of the buckling restrained brace according to the present invention, a steel plate accommodating groove is provided in an inner surface of the side plate in a corresponding range corresponding to the non-contact groove between the pair of restraint plates, a reinforcing steel plate spanning each side surface of the pair of restraint plates is fixed to each side surface of the pair of restraint plates, The reinforcing steel plate is accommodated in the steel plate accommodation groove without contacting the inner wall surface of the steel plate accommodation groove.

[0028] According to this aspect, a steel plate accommodation groove is provided on the inner surface of the side plate in a range corresponding to the non-contact grooves between the pair of restraint plates, and a reinforcing steel plate, which is fixed to each of the pair of restraint plates and straddles the side surfaces of the pair of restraint plates, is accommodated in the steel plate accommodation groove without contacting the inner wall surface of the steel plate accommodation groove. This allows the reinforcing steel plate, which is fixed to the restraint plates and does not contact the side plate, to effectively resist tension from the side plate. This, combined with the non-contact grooves provided at the ends of the restraint plates, makes it possible to more effectively prevent cracks from occurring in the side plate. Furthermore, because the reinforcing steel plate does not contact the inner wall surface of the steel plate accommodation groove, there is no risk of the reinforcing steel plate pressing against the side plate and inducing cracks.

[0029] In another aspect of the buckling restrained brace according to the present invention, The fiber direction of the corresponding range of the side plate corresponding to the non-contact groove of the restraint plate is the short direction of the side plate, and the fiber direction outside the corresponding range is the long direction of the side plate.

[0030] According to this aspect, the fiber direction of the corresponding range of the side panel that corresponds to the non-contact groove of the restraining plate is the short direction of the side panel, so that the fiber direction with high strength of the wood is oriented along (or to some extent along) the direction of cracks that may occur in the side panel due to tension from the restraining plate (the short direction of the side panel), and the side panel can provide high resistance to cracks. On the other hand, the fiber direction of the side panel other than the corresponding range of the end is oriented along the longitudinal direction of the side panel, so that the fiber direction with high strength of the wood is oriented in the center part of the side panel where bending etc. is prominent, and therefore the bending strength of the center part can be high.

[0031] In another aspect of the buckling restrained brace according to the present invention, The side plates are characterized in that piercing means extending toward the pair of restraining plates are pierced into corresponding areas of the side plates that correspond to the non-contact grooves of the restraining plates.

[0032] According to this aspect, the piercing means extending toward the pair of restraining plates pierces the side plates in the corresponding ranges that correspond to the non-contact grooves of the restraining plates, and more specifically, the piercing means pierces in the direction along (or to some extent along) the direction of cracks that may occur in the side plates due to tension from the restraining plates (the short side direction of the side plates), so that the piercing means can provide high resistance to cracks. Here, examples of the piercing means include screws, nails, and bolts including lag screw bolts.

[0033] In another aspect of the buckling restrained brace according to the present invention, First bolt holes are opened at corresponding positions of the pair of restraint plates, the corresponding first bolt holes form first bolt hole units, and first long bolts are inserted into each of the plurality of first bolt hole units and fastened with nuts, Second bolt holes are opened at corresponding positions of the pair of side plates and the restraint plate, and second bolt hole units are formed by the corresponding second bolt holes, and second long bolts are inserted into each of the multiple second bolt hole units and tightened with nuts.

[0034] According to this aspect, the pair of restraint plates are joined by fastening the first-length bolts with nuts, and the pair of side plates are joined together with the restraint plate between them by fastening the second-length bolts with nuts, thereby forming a wooden restraint member that provides high restraint for the pair of restraint plates and the pair of side plates. This allows for the formation of a buckling-restrained brace with a highly rigid wooden restraint member that is less likely to break under additional bending moments that may act.

[0035] In another aspect of the buckling restrained brace according to the present invention, The contact surfaces of the restraint plate and the side plate are joined with an adhesive and fastened by the second long bolts.

[0036] According to this aspect, the contact surfaces of the restraint plate and the side plate are joined with adhesive and further tightened with second-long bolts, so that the adhesive surfaces that are the contact surfaces of the restraint plate and the side plate are crimped with the second-long bolts, making it possible to form a buckling restraint brace with wooden restraint material that has even stronger connection strength between the restraint plate and the side plate.

[0037] In another aspect of the buckling restrained brace according to the present invention, a reinforcing rib orthogonal to the wide surface of the end of the core material in the longitudinal direction is joined to the wide surface, forming a cross-shaped cross section; The wooden restraint member is characterized in that a slit is provided at a position corresponding to the reinforcing rib so as not to interfere with the reinforcing rib.

[0038] According to this aspect, the longitudinal ends of the core material have a cross-shaped cross section due to the reinforcing ribs that are perpendicular to the wide faces of the core material. Therefore, when a buckling-restrained brace is attached to a gusset plate with the wide faces of the core material arranged parallel to the structural face of a building, the core material has reinforcing ribs that are perpendicular to the wide faces that are parallel to the structural face, thereby increasing the rigidity of the end of the core material in the outward direction of the structural face. In the gusset plate of the structural face to which the core material with a cross cross section is attached, fin stiffeners are attached to the gusset plate, and the core material of the buckling-restrained brace and the gusset plate, as well as the reinforcing ribs and fin stiffeners, are each joined via a splice plate with high-tension bolts or the like. In this aspect, slits are provided in the wooden restraint material at positions corresponding to the reinforcing ribs, and these slits are configured to prevent interference between the wooden restraint material and the reinforcing ribs.

[0039] Another aspect of the buckling restrained brace according to the present invention is: In plan view, a gap is formed between the slit and the reinforcing rib.

[0040] According to this aspect, the gap between the slit and the reinforcing rib allows the core material to absorb expansion and contraction in response to structural deformation. This eliminates the problem of the core material contacting the slit wall and damaging the wooden restraint. The design of this gap is also left to the designer's discretion. The amount of expansion and contraction of the core material is calculated based on the set story deformation angle. For example, the gap is set to be equal to or greater than the amount of expansion and contraction of the core material. Note that the "gap" here includes the gap between the longitudinal end of the slit and the reinforcing rib, as well as the gap between the side surface of the slit and the reinforcing rib. The gap between the side surface of the slit and the reinforcing rib can be set to the same gap as the gap between the side surface of the wide portion of the core material and the side panel. Furthermore, the non-contact grooves in the restraint plate create a separate gap between the core material and the restraint plate. This gap is also set to a size that prevents the core material from strongly pressing against or abutting the restraint plate when the buckling-restrained brace deforms during a large earthquake.

[0041] In addition, another aspect of the buckling restrained brace according to this aspect is as follows: The present invention is characterized in that an insert plate is interposed between the wide surface of the core material and the restraining plate.

[0042] According to this aspect, the core material's high-order buckling deformation causes localized compressive forces to act on the restraining plate, preventing damage to the restraining plate due to these localized forces. By interposing the insert plate between the wide surface of the core material and the restraining plate, the force acting from the convex portion of the core material's high-order buckling deformation is first transmitted to the insert plate, which then spreads within the insert plate, and the diffused force within the insert plate acts on the wooden restraining plate. This effectively prevents damage to the wooden restraining plate due to multiple localized forces acting from the core material. [Effects of the Invention]

[0043] As can be seen from the above explanation, the buckling restrained brace of the present invention is suitable for use within the framework of a wooden building or the like. For example, during a major earthquake, the framework and buckling restrained brace may deform outward from the structural surface, causing the core material forming the buckling restrained brace to press into the restraining plates forming the wooden restraining member, preventing cracks from occurring in the side panels pulled by the restraining plates. [Brief explanation of the drawings]

[0044] [Figure 1] FIG. 2 is a perspective view showing an example of a core material that forms the buckling restrained brace according to the first embodiment, together with a spacer. [Figure 2] FIG. 2 is a perspective view of an example of a wooden restraint member that forms the buckling restrained brace according to the first embodiment. [Figure 3] FIG. 2 is a perspective view of an example of a buckling restrained brace according to the first embodiment. [Figure 4] FIG. 4 is a view taken in the direction of the arrow IV in FIG. 3. [Figure 5] FIG. 4 is a view taken along arrows VV in FIG. 3. [Figure 6] FIG. 6 is a view taken along the line VI-VI in FIG. 3. [Figure 7] FIG. 7 is a view taken along the line VII-VII in FIG. 3. [Figure 8] FIG. 8 is a view taken along the line VIII-VIII in FIG. 3. [Figure 9] FIG. 10 is a perspective view showing a first modified example of a wooden restraint material. [Figure 10] FIG. 10 is a perspective view showing a second modified example of the wooden restraint material. [Figure 11] FIG. 10 is a perspective view showing a third modified example of the wooden restraint material. [Figure 12] FIG. 10 is a perspective view showing a fourth modified example of the wooden restraint material. [Figure 13] FIG. 10 is a perspective view showing a fifth modified example of a wooden restraint material. [Figure 14] FIG. 10 is a perspective view showing a sixth modified example of a wooden restraint material. [Figure 15] FIG. 2 is a diagram showing the buckling restraint brace according to the first embodiment incorporated into the frame of a wooden building or the like. [Figure 16]1 is a diagram illustrating the deformation of the frame during a major earthquake and the additional bending moment at the buckling-restrained brace joint due to the deformation of the frame. [Figure 17] FIG. 11 is a perspective view showing an example of a core material that forms a buckling restrained brace according to a second embodiment, together with a spacer. [Figure 18] FIG. 10 is a longitudinal cross-sectional view of an example of a buckling restrained brace according to a second embodiment. [Figure 19] 19 is an enlarged view of part XIX in FIG. 18, illustrating how the force acting locally from the convex portion on the surface of the core material is diffused through the insertion plate and transmitted to the restraint plate. [Figure 20] FIG. 10 is a diagram showing the overall buckling line of the buckling restraint brace. DETAILED DESCRIPTION OF THE INVENTION

[0045] The buckling restrained brace according to each embodiment will be described below with reference to the accompanying drawings. Note that in this specification and drawings, substantially identical components will be designated by the same reference numerals to avoid redundant description.

[0046] [Buckling-restrained brace according to the first embodiment] <Core material> First, an example of a core material that forms the buckling restrained brace according to the first embodiment will be described with reference to Fig. 1. Here, Fig. 1 is a perspective view showing an example of a core material that forms the buckling restrained brace according to the first embodiment together with a spacer.

[0047] The core material 10 is formed from a long, slender, plate-shaped flat steel, and has a narrow portion 13 at the center in the longitudinal direction where the wide surface 11a is relatively narrow, and wide portions 12 at the ends in the longitudinal direction where the wide surface 11a is relatively wide. In addition, reinforcing ribs 14 perpendicular to the wide surface 11a are welded to the wide surface 11a at the ends in the longitudinal direction of the core material 10, giving it a cross-shaped cross section.

[0048] By having a narrow width portion 13 at the center of the core material 10 in the longitudinal direction and a wide width portion 12 at the end of the longitudinal direction, the narrow width portion 13 at the center can be made into a region that is easily plasticized, and further, the plasticized region can be limited to the narrow width portion 13 at the center.

[0049] Furthermore, as will be explained below, the wide portion 12 and the reinforcing rib 14 each have bolt holes 12a, 14a for bolting via a splice plate to a gusset plate provided on the structural face or a fin stiffener (see FIG. 11) attached to the gusset plate. When the buckling restrained brace 100 is attached to a gusset plate so that the wide face 11a of the core member 10 is arranged parallel to the structural face of the building, the core member 10 has reinforcing ribs 14 that are perpendicular to the wide face 11a that is parallel to the structural face, thereby increasing the rigidity of the end of the core member 10 in the direction outward from the structural face.

[0050] The core material 10 is preferably formed from a steel material with a low yield point such as SN material (rolled steel for building structures) or LYP material (extremely low yield point steel), which improves earthquake energy absorption due to yielding of the core material 10.

[0051] At the center of the narrow portion 13 of the core material 10, cylindrical steel protrusions 15 protrude from the left and right side surfaces of the narrow portion 13 (one example of the peripheral surface of the narrow portion 13). The protrusions 15 are joined to the side surfaces of the narrow portion 13 by welding or the like. The protrusions 15 engage with engagement holes formed in a wooden restraint material (see FIG. 2) described below. The protrusions 15 may also protrude from the upper and lower planes of the narrow portion 13. In this case, engagement holes are formed in the wooden restraint material (see FIG. 2) at corresponding positions in restraint plates 21, and the protrusions 15 engage with these engagement holes.

[0052] Thin, rectangular column-shaped spacers 16 are arranged in the X1 direction on both the left and right sides of the narrow portion 13, and the core material 10 is housed inside a wooden restraint material (described below) with the spacers 16 arranged on both the left and right sides of the narrow portion 13. The spacers 16 may be either steel or wooden members. The spacers 16 may also have a shape other than that shown in the illustration, such as a cylindrical shape. The spacer 16 has a plurality of bolt holes 16a (three in the illustrated example) spaced apart in the longitudinal direction, through which first long bolts (described below) are inserted.

[0053] <Wooden restraint material> Next, an example of a wooden restraint member that forms the buckling restrained brace according to the first embodiment will be described with reference to Fig. 2. Here, Fig. 2 is a perspective view of an example of a wooden restraint member that forms the buckling restrained brace according to the first embodiment.

[0054] The wooden restraint member 20 has a pair of restraint plates 21 and a pair of side plates 22 connecting the pair of restraint plates 21, with the core material 10 being disposed in a gap 25 between the pair of restraint plates 21. The pair of wooden restraint plates 21 are disposed so as to face the two wide surfaces 11a (see FIG. 1) of the core material 10, and the pair of wooden side plates 22 connected to the pair of restraint plates 21 are disposed so as to face the two narrow surfaces 11b (see FIG. 1) of the core material 10.

[0055] First bolt holes 21a each having a counterbore are opened at corresponding positions on a pair of restraint plates 21, and two corresponding first bolt holes 21a form a first bolt hole unit 21b. In the illustrated example, two first bolt hole units 21b are provided in the width direction of restraint plate 21 and six are provided in the longitudinal direction of restraint plate 21, for a total of twelve first bolt hole units 21b.

[0056] When core material 10 is disposed in gap 25 between a pair of restraint plates 21, each bolt hole 16a opened in spacer 16 is positioned at a position corresponding to each first bolt hole unit 21b, and these bolt holes 16a also form first bolt hole unit 21b. First long bolts 31 are inserted into first bolt hole units 21b and tightened with nuts 33. More specifically, a washer 32 is disposed in the counterbore of one of first bolt holes 21a forming first bolt hole unit 21b, first long bolt 31 is inserted into first bolt hole unit 21b via washer 32, a washer 34 is disposed in the counterbore of the other first bolt hole 21a, and nut 33 is tightened onto the thread groove at the tip of first long bolt 31 protruding outward from washer 34.

[0057] Meanwhile, second bolt holes 22a, 21c are opened at corresponding positions on a pair of side plates 22 and restraint plate 21, respectively, and second bolt hole unit 22b is formed by corresponding second bolt holes 22a, 21c. Second bolt hole unit 22b is provided at a position where it does not interfere with first bolt hole unit 21b, and in the illustrated example, two are provided in the width direction of side plate 22 and seven are provided in the length direction of side plate 22, for a total of fourteen second bolt hole units 22b.

[0058] Second-long bolts 41 are inserted into each second bolt hole unit 22b and tightened with nuts 43. More specifically, a washer 42 is disposed in the counterbore of one of the second bolt holes 22a that form second bolt hole unit 22b, second-long bolts 41 are inserted into second bolt hole unit 22b via washer 42, a washer 44 is disposed in the counterbore of the other second bolt hole 22a, and nut 43 is tightened onto the thread groove at the tip of second-long bolt 41 that protrudes outward from washer 44.

[0059] In addition, when tightening the second-long bolt 41 with the nut 43, adhesive is applied to the contact surfaces of the restraint plate 21 and the side plate 22, and the second-long bolt 41 is tightened with the nut 43 before the adhesive hardens.

[0060] Here, the adhesive may be a urethane adhesive or an epoxy adhesive, but it is preferable to use a urethane adhesive that takes a certain amount of time to harden (for example, about 24 hours) so that after the adhesive is applied to the contact surfaces of restraint plate 21 and side plate 22, second-long bolts 41 can be tightened with nuts 43 before the adhesive hardens. The adhesive surface formed by the hardening of the adhesive is firmly pressed against the second-long bolts 41 by the tightening force applied by nuts 43.

[0061] In this way, a pair of restraint plates 21 are restrained together by tightening multiple first long bolts 31 with nuts 33, and a pair of side plates 22 and restraint plates 21 are restrained together by tightening second long bolts 41 with nuts 43 via the adhesive surfaces, thereby forming a wooden restraint material 20 with a closed structure in which the restraint plates 21 and side plates 22 are firmly joined.

[0062] If high joint strength as in the illustrated example is not required, the wooden restraint member 20 may be formed by bonding the pair of restraint plates 21 and the pair of side plates 22 together using only an adhesive.

[0063] The left and right side panels 22 have engagement holes 22c formed at their longitudinal center positions, into which the protrusions 15 of the core material 10 engage. The engagement of the protrusions 15 of the core material 10 with the engagement holes 22c formed in the wooden restraint member 20 prevents the core material 10 inserted inside the wooden restraint member 20 from biasing to one end of the wooden restraint member 20. Therefore, even if the core material 10 biases to one end of the wooden restraint member 20 in this way, the other end of the wooden restraint member 20, where the core material 10 is not present, does not become a weak spot in terms of strength.

[0064] Furthermore, spacer 16 has bolt holes 16a that form first bolt hole unit 21b, and first long bolts 31 are inserted through these bolt holes 16a, thereby preventing spacer 16 from moving in the longitudinal direction of core material 10. As will be explained below with reference to FIG. 11 , buckling restrained braces are generally arranged diagonally on a structural plane, so spacer 16 is prone to moving diagonally downward. This movement of spacer 16 can easily create a large gap diagonally upward between the end of spacer 16 and wide portion 12 of core material 10. Therefore, the diagonally upward region of the buckling restrained brace where spacer 16 is not present is prone to becoming a weak spot. However, by inserting first long bolts 31 through bolt holes 16a of spacer 16 as shown in the figure, this movement of spacer 16 is eliminated, and no weak spot due to the movement of spacer 16 occurs.

[0065] As is clear from Figure 2, although the ends of a pair of restraint plates 21 are fixed to the side plates 22 via adhesive, they are not fixed by the second long bolts 41, so it is difficult to say that a strong closed structure is formed at the ends of the wooden restraint material 20.

[0066] Therefore, when buckling restraint braces are incorporated into a frame and are deformed outside the structural plane during an earthquake, cracks (splits) may occur at the ends of the side panels 22 connected to positions corresponding to the ends of the pair of restraint plates 21 that receive the strongest pushing force from the core material 10.

[0067] Therefore, as shown in FIG. 2, the ends of the pair of restraint plates 21 are connected to each other by a plurality of rivets 29A (an example of end restraint members).

[0068] The clamp 29A is a metal fitting having an overall U-shape, and has a linear connecting portion 29a and two piercing portions 29b formed by bending the connecting portion 29a at right angles at both ends.

[0069] The two piercing portions 29b of the U-shaped clamp 29A are pierced near both ends of the side plate 22, and then further pierced into the end faces of the pair of restraining plates 21, thereby fixing both ends of the side plate 22 and the pair of restraining plates 21 via the clamps 29A. In the illustrated example, three clamps 29A are driven into both ends of the left and right side plates 22, forming a strong closed structure at both ends of the wooden restraining member 20.

[0070] Here, the method of fixing the clamp 29A may be a method of hammering in and fixing, or a method of inserting the piercing portion 29b into a fixing hole (not shown) formed in the end face of the restraint plate 21 and adhesively fixing with an adhesive. More specifically, fixing holes that communicate with both ends of the side plate 22 and the end faces of the pair of restraint plates 21 are provided, and the piercing portion 29b is inserted into these communicating fixing holes and adhesively fixed with an adhesive filled in the fixing holes. Here, as described above, a urethane adhesive or an epoxy adhesive is used as the adhesive.

[0071] In addition, non-contact grooves 23 that do not come into contact with the wide surface 11a of the core material 10 housed in the gap 25 are provided at both ends of the restraint plate 21, and the area of ​​the restraint plate 21 other than the non-contact grooves 23 (the area on the central side) comes into contact with the wide surface 11a of the core material 10. This configuration and the effects achieved by this configuration will be described in detail below.

[0072] The restraining plate 21 and the side plate 22 may be made of either solid wood or wood materials including laminated lumber made of laminated lamina. As will be described in detail below, the cross-sectional area, cross-sectional stiffness, Young's modulus, etc. of the wooden restraining member 20 are set so as to prevent global buckling of the buckling-restrained brace. This Young's modulus is determined by the wood material. Examples of wood materials include Japanese cypress, red pine, larch, fir, and Yezo spruce.

[0073] At the end of restraint plate 21, a slit 24 is provided at a position that corresponds to reinforcing rib 14 when core material 10 is housed in gap 25, so that it does not interfere with reinforcing rib 14. A plurality of separate clamps 29A' are also driven into the periphery of slit 24 in restraint plate 21, reinforcing the area around slit 24. Note that clamps 29A' are members that are provided as needed and are not essential components.

[0074] <Buckling restrained brace> Next, an example of a buckling-restrained brace according to the first embodiment, formed using the core material 10 and wooden restraint material 20 described above, will be described with reference to Figures 3 to 14. Here, Figure 3 is a perspective view of an example of a buckling-restrained brace according to the first embodiment. Also, Figures 4, 5, 6, 7, and 8 are a view taken in the direction of arrow IV in Figure 3, a view taken in the direction of arrows VV in Figure 3, a view taken in the direction of arrows VI-VI in Figure 3, a view taken in the direction of arrows VII-VII in Figure 3, and a view taken in the direction of arrows VIII-VIII in Figure 3, respectively.

[0075] The buckling restraint brace 100 is constructed such that wooden restraint members 20 are arranged to surround the narrow section 13 and part of the wide section 12 of the core material 10, and the cross-shaped portion of the end of the wide section 12 extends beyond the end of the wooden restraint member 20, with the bolt holes 12a, 14a of the wide section 12 and reinforcing rib 14 that extend outward facing the outside.

[0076] A core material 10 is disposed in a gap 25 between a pair of restraint plates 21, a plurality of first long bolts 31 are inserted through the pair of restraint plates 21 and spacers 16 and fastened with nuts 33, second long bolts 41 are inserted through the pair of side plates 22 and restraint plates 21 and fastened with nuts 43, and the ends of the pair of restraint plates 21 are connected by fasteners 29A driven from the outside of the side plates 22, thereby forming a buckling restrained brace 100. As shown in the figure, the extension direction of the first long bolts 31 is the weak axis direction of the core material 10, and the extension direction of the second long bolts 41 is the strong axis direction of the core material 10.

[0077] The buckling-restrained brace 100 has a configuration in which the core material 10 is surrounded by wooden restraint members 20, which are formed by a pair of restraint plates 21 and a pair of side plates 22 that are tightly fastened together by fastening a plurality of first-length bolts 31 and second-length bolts 41 with nuts, resulting in a buckling-restrained brace with high buckling strength. Furthermore, by connecting the ends of the pair of restraint plates 21 with clamps 29A, the buckling-restrained brace has a strong closed structure at the ends. Furthermore, because the steel core material 10 is surrounded by wooden restraint members 20, the buckling-restrained brace 100 does not appear out of place with the structural components when applied to the frame of a wooden building.

[0078] In the illustrated buckling restraint brace 100, the core material 10 is accommodated within the gap 25 of the wooden restraint material 20 with spacers 16 arranged on the left and right sides of the narrow width portion 13, and the protrusions 15 extending laterally from the sides of the narrow width portion 13 are engaged with the engagement holes 22c.

[0079] A gap G1 of width t1 is provided between the side surface of the wide portion 12 of the core material 10 and the side plate 22 of the wooden restraint material 20.

[0080] Furthermore, non-contact grooves 23 are formed at the ends of the constraining plates 21 to prevent the constraining plates 21 from contacting the wide portions 12 of the core material 10, and a gap G3 of height t2 is provided between the non-contact grooves 23 and the wide portions 12. As shown in detail in Figure 7, these non-contact grooves 23 are provided in a range from the edge of the constraining plates 21 to a position corresponding to the additional bending absorption area A of the core material 10 (boundary region A between the wide portions 12 and the narrow portions 13).

[0081] 7 and 8, the boundary region A between the wide section 12 and the narrow section 13 is a transition region where the planar area and cross-sectional area of ​​the core material 10 change, and therefore serves as an additional bending absorption area where the additional bending moment acting on the core material 10 can be absorbed in this transition region. In this way, the additional bending moment acting on the core material 10 is effectively absorbed in the boundary region A between the wide section 12 and the narrow section 13 of the core material 10, and the gap G1 provided between the core material 10 and the side panel 22 of the wooden restraint member 20 prevents the additional bending moment acting on the core material 10 from acting on the side panel 22 of the wooden restraint member 20.

[0082] Furthermore, a gap G2 having a width t3 in the longitudinal direction of the reinforcing rib 14 and a width t1 on one side of the reinforcing rib 14 is provided between the reinforcing rib 14 and the slit 24 in the restraining plate 21 of the wooden restraining member 20. By providing gap G1 between the side surface of the wide portion 12 and the side plate 22 of the wooden restraining member 20, if the structural surface to which the buckling restrained brace 100 is attached undergoes significant deformation, this gap G1 can absorb the deformation of the core material 10, preventing so-called additional bending moment from acting on the wooden restraining member 20. Meanwhile, the presence of gap G2 between the slit 24 and the reinforcing rib 14 allows gap G2 to absorb the expansion and contraction of the core material 10 when it expands or contracts in response to deformation of the structural surface, eliminating the problem of the expanding or contracting core material 10 coming into contact with the wall of the slit 24 and causing damage to the wooden restraining member 20.

[0083] 4 and 5, in the buckling restrained brace 100, non-contact grooves 23 are provided in the restraint plate 21 over the range from its edge to a position corresponding to the additional bending absorption area A of the core material 10. Meanwhile, as shown in FIG. 6, the area of ​​the restraint plate 21 other than the non-contact grooves 23 is in contact with the narrow portion 13 of the core material 10.

[0084] With the above configuration, when the frame S (see Figure 11) and the buckling restraint brace 100 are deformed outside the structural plane, the non-contact groove 23 eliminates or reduces contact (prevents strong contact) between the core material 10 and the restraint plate 21 at the end of the restraint plate 21, which is likely to receive the strongest pushing force from the core material 10.

[0085] In this way, by eliminating or mitigating the pressure from the core material 10 on the restraint plates 21, it is possible to suppress cracks that may occur at the ends of the side panels 22 that are connected at positions corresponding to the ends of the restraint plates 21. When the restraint plates 21 are pressed into the core material 10, cracks that occur in the side panels 22 due to tension from the pressed-in restraint plates 21 tend to occur significantly in the short-side direction or a direction close to the short-side direction in the longitudinal cross section of the wooden restraint material 20, as shown in Figures 4 and 5, but this cracking is effectively eliminated.

[0086] In the illustrated example, the ends of a pair of restraint plates 21 are connected (reinforced) by clamps 29A driven into the outside of the side plates 22, and this reinforcing structure, combined with the non-contact grooves 23 which eliminate or reduce contact between the core material 10 and the restraint plates 21, further enhances the effect of suppressing cracking of the side plates 22 due to tension from the restraint plates 21.

[0087] In addition, the non-contact grooves 23 at the ends of the restraint plate 21 eliminate or reduce the contact between the ends of the restraint plate 21 and the core material 10, while the areas of the restraint plate 21 other than the non-contact grooves 23 (the central areas) come into contact with the core material 10, thereby ensuring that the restraint plate 21 can prevent the core material 10 from buckling.

[0088] 7 and 8, by providing narrow section 13 at the center of core member 10, a relatively large gap G4 (larger than gap G1 between wide section 12 at the end of core member 10 and side panel 22) exists between narrow section 13 and side panel 22. By interposing spacer 16 in gap G4 to close gap G4, buckling in the strong axis direction of core member 10 (direction parallel to wide surface 11a of core member 10) can be prevented. As a result, global buckling of buckling-restrained brace 100 is suppressed and the compressive strength of buckling-restrained brace 100 is improved, thereby providing excellent seismic reinforcement for a frame incorporating buckling-restrained brace 100 and a building including this frame.

[0089] Next, first to fifth modified examples of the wooden restraining member that forms the buckling restrained brace 100 will be described with reference to Figures 9 to 14. Each modified example of the wooden restraining member has a distinctive side panel.

[0090] 9 shows a wooden restraint member 20A in which two strip-shaped steel plates 29B (another example of an end restraint member) are wrapped around the ends of the wooden restraint member 20A, and the ends of the two steel plates 29B are connected to indirectly restrain (reinforce) the ends of a pair of restraint plates 21. Here, in the illustrated example, the wooden restraint member 20A has the end reinforced by one strip-shaped steel plate 29B, but the end of the wooden restraint member 20A may also be reinforced by two or more strip-shaped steel plates 29B.

[0091] In this way, by restraining the ends of the pair of restraint plates 21 from each other by the strip-shaped steel plate 29B, cracks that may occur in the side plates 22 due to tension from the restraint plates 21 can be suppressed.

[0092] 10 shows a wooden restraint 20B in which two strip-shaped fiber reinforcement members 29C (another example of an end restraint member) are wrapped around the end of the wooden restraint 20B, and the ends of the two fiber reinforcement members 29C are connected to each other, thereby indirectly restraining (reinforcing) the ends of a pair of restraint plates 21. Here, in the illustrated example, the wooden restraint 20C has the end of the wooden restraint 20B reinforced with two strip-shaped fiber reinforcement members 29C, but the end of the wooden restraint 20B may also be reinforced with one, three or more strip-shaped fiber reinforcement members 29C.

[0093] In this way, by restraining the ends of the pair of restraining plates 21 with the strip-shaped fiber reinforcing material 29C, cracks that may occur in the side plates 22 due to tension from the restraining plates 21 can be suppressed.

[0094] The wooden restraint material 20C shown in Figure 11 has a side panel 22A that has a central side panel 26 and end side panels 27 at both ends of the central side panel 26, and the central side panel 26 and the end side panels 27 are connected by adhesive or the like.

[0095] The end side plates 27 are located in a corresponding range to the non-contact grooves 23 of the restraint plate 21, and the grain direction of the wood of the end side plates 27 is oriented in the short direction of the side plates 22A. On the other hand, the grain direction of the wood of the central side plate 26 is arranged in the long direction of the side plates 22A.

[0096] Further, the ends of the pair of restraint plates 21 are connected (reinforced) by a plurality of (three in the illustrated example) clamps 29A driven into the outer sides of the end side plates 27.

[0097] In this way, the fiber direction of the end side plates 27 of the side plates 22A that are in the corresponding ranges corresponding to the non-contact grooves 23 of the restraining plate 21 is the short direction of the side plate 22A, and therefore the fiber direction with high wood strength is oriented along (or to some extent along) the direction of cracks that may occur in the end side plates 27 due to tension from the restraining plate 21 (the short direction of the side plate 22A), and therefore the end side plates 27 can provide high resistance to cracks. On the other hand, the fiber direction of the central side plate 26 of the side plates 22A that are outside the corresponding ranges of the end plates is oriented along the longitudinal direction of the central side plate 26, and therefore the fiber direction with high wood strength is oriented in the central portion of the side plate 22A where bending, etc. is prominent, and therefore the bending strength of the central portion can be high.

[0098] Furthermore, by connecting the ends of the pair of restraint plates 21 with clamps 29A, a strong closed structure can be formed at the end of the wooden restraint material 20C. Instead of clamps 29A, as shown in Figures 9 and 10, the end of the wooden restraint material may be wrapped around a strip-shaped steel plate 29B or a strip-shaped fiber reinforcing material 29C, thereby forming a strong closed structure at the end.

[0099] 12, a wooden restraint member 20D is pierced by a plurality of piercing means 28 (three in the illustrated example) extending toward the pair of restraint plates (in the short direction of the side plates 22B) in the range of the side plates 22B that corresponds to the non-contact grooves 23 of the restraint plates 21. Here, the piercing means 28 may be a screw, a nail, a bolt including a lag screw bolt, or the like.

[0100] Furthermore, the ends of the pair of restraint plates 21 are connected (reinforced) by a plurality of (three in the illustrated example) clamps 29A driven into the outside of the side plate 22B.

[0101] In this way, piercing means 28 extending toward the pair of constraining plates pierces side plate 22B in a range corresponding to non-contact groove 23 of constraining plate 21. More specifically, piercing means 28 pierces in a direction along (or to some extent along) the direction of cracks that may occur in side plate 22B due to tension from constraining plate 21 (the short side direction of the side plate). This allows piercing means 28 to provide high resistance to cracks. Furthermore, by connecting the ends of pair of constraining plates 21 to each other with clamps 29A, a strong closed structure can be formed at the end of wooden constraining member 20D.

[0102] 13, a wooden restraint member 20E has a steel plate accommodating groove 22e that is rectangular in plan view from the inside, on the inner surface of a side plate 22C (the surface facing the non-contact groove 23), in a corresponding area that corresponds to the non-contact groove 23 between the pair of restraint plates 21. A reinforcing steel plate 45 that is rectangular in plan view and spans each side surface is fixed to each side surface of the pair of restraint plates 21. For example, the reinforcing steel plate 45 is fixed to the side surfaces of the pair of restraint plates 21 by adhesive, drill screws, or both.

[0103] Here, the planar dimensions of the reinforcing steel plate 45 are set smaller than the planar dimensions of the steel plate accommodating groove 22e, and further, the thickness of the reinforcing steel plate 45 is set thinner than the groove depth of the steel plate accommodating groove 22e.

[0104] When a reinforcing steel plate 45 is fixed to the side surfaces of a pair of restraint plates 21 and the pair of restraint plates 21 and side plates 22 are connected so as to accommodate the reinforcing steel plate 45 in the steel plate accommodating groove 22e, the reinforcing steel plate 45, which has dimensions smaller than the planar dimensions and depth of the steel plate accommodating groove 22e, is accommodated in the steel plate accommodating groove 22e without coming into contact with the inner wall surface of the steel plate accommodating groove 22e.

[0105] On the left and right sides of the pair of restraint plates 21, reinforcing steel plates 45 are accommodated in the steel plate accommodating groove 22e without contacting the side plates 22C, and the pair of side plates 22C are connected to the pair of restraint plates 21, thereby forming the wooden restraint material 20E.

[0106] In this way, the reinforcing steel plate 45, which does not contact the side plate 22C, is fixed to the side surfaces of the pair of restraint plates 21, and therefore the reinforcing steel plate 45 can withstand with high resistance the pulling force from the side plate 22. At this time, because the reinforcing steel plate 45 does not contact the inner wall surface of the steel plate accommodating groove 22e, there is no risk that the reinforcing steel plate 45 will press against the side plate 22C and induce cracks.

[0107] On the other hand, the wooden restraint material 20F shown in Figure 14 has a configuration in which multiple nails 29A are driven into the ends of a pair of restraint plates 21 to connect the ends of the pair of restraint plates 21, and then side panels 22 are fixed to the outside of the restraint plates 21 via adhesive.

[0108] In this way, by arranging the side plates 22 on the outside of the multiple rivets 29A connecting the ends of the restraint plates 21, the rivets 29A can be concealed so that they cannot be seen from the outside, which not only has the effect of suppressing cracking of the side plates 22 due to pulling from the restraint plates 21, but also results in a wooden restraint material 20F with excellent external design.

[0109] In the wooden restraint materials 20A, 20B, 20C, 20D, 20E, and 20F according to the first to sixth modified examples, the ends of a pair of restraint plates 21 are connected to each other by an end restraint material 29A, and further, the pair of restraint plates 21 have non-contact grooves 23 at both ends that eliminate or mitigate the pressure exerted by the wide portion 12 of the deforming core material 10. In addition, the ends of the side plates 22A and 22B are reinforced against cracks by end side plates 27 in the fiber direction that follows the crack direction, multiple piercing means 28, and reinforcing steel plates 45, so that cracks that may occur in the side plates 22, 22A, 22B, and 22C can be eliminated even more effectively.

[0110] <Example of application of buckling restrained braces to a frame> Next, an example of application of a buckling restrained brace to a frame will be described with reference to Figures 15 and 16. Here, Figure 15 is a diagram showing the buckling restrained brace according to the first embodiment incorporated into the frame of a wooden building or the like. Also, Figure 16 is a diagram explaining the deformation of the frame during a major earthquake and the additional bending moment at the buckling restrained brace joint resulting from the deformation of the frame. Note that the buckling restrained brace shown in the example may be incorporated into the frame of a steel (S) building, a reinforced concrete (RC) building, or a steel reinforced concrete (SRC) building, in addition to the frame of a wooden building.

[0111] The frame S shown in Figure 15 is formed from wooden columns C and beams B that constitute a wooden building or the like. Gusset plates GP made of flat steel are attached to the two diagonally positioned corners. Fin stiffeners FS are welded to the surface of the gusset plates GP so that they are perpendicular to the surface. The fin stiffeners FS are joined to the gusset plates GP so that their center L3 intersects with the intersection O between the column center L1 of the column C and the beam center L2 of the beam B. The buckling restrained brace 100 is also arranged in a line that passes through both diagonally positioned intersections O.

[0112] The gusset plate GP and the wide portion 12 of the core material 10 are joined by high tension bolts via a splice plate SP, and the fin stiffener FS and the reinforcing rib 14 are joined by high tension bolts via a splice plate SP.

[0113] As shown in Figure 16, when a large earthquake occurs, deformation of the structural plane can cause an additional bending moment, as shown in equation (1) below, to act on the buckling-restrained brace joint, assuming that the joint is rigid.

[0114]

number

[0115] According to the buckling-restrained brace 100, a gap G1 of width t1 is provided between the side surface of the wide section 12 of the core material 10 and the side panel 22 of the wooden restraint member 20. This allows gap G1 to absorb the deformation of the core material 10 when the structural surface to which the buckling-restrained brace 100 is attached undergoes significant deformation, preventing additional bending moments from acting on the wooden restraint member 20. Furthermore, a gap G2 of width t2 is provided between the reinforcing rib 14 and the slit 24 of the restraint plate 21 of the wooden restraint member 20 in the longitudinal direction of the reinforcing rib 14 and on the side of the reinforcing rib 14, allowing gap G2 to absorb the expansion and contraction of the core material 10 when it expands and contracts in response to deformation of the structural surface. This prevents the expanding and contracting core material 10 from coming into contact with the wall of the slit 24, which could lead to damage to the wooden restraint member 20. Furthermore, the ends of the restraint plate 21, which are likely to receive the strongest pushing force from the core material 10, are connected together by multiple end restraint members 29A, and gaps G3 are formed by non-contact grooves 23 at these ends.Gap G3 eliminates or reduces contact between the core material 10 and the restraint plate 21, thereby effectively suppressing cracks that may occur at the ends of the side plates 22 connected at positions corresponding to the ends of the restraint plate 21.

[0116] [Buckling-restrained brace according to the second embodiment] Next, an example of a core material forming a buckling restrained brace according to the second embodiment will be described with reference to Figures 17 to 19. Here, Figure 17 is a perspective view showing an example of a core material forming a buckling restrained brace according to the second embodiment together with a spacer, and Figure 18 is a longitudinal cross-sectional view of an example of a buckling restrained brace according to the second embodiment. Furthermore, Figure 19 is an enlarged view of part XIX in Figure 18, and illustrates how a force acting locally from a convex portion on the surface of the core material is diffused via an insertion plate and transmitted to the restraining plate.

[0117] The buckling restrained brace 100A differs from the buckling restrained brace 100 in that an insert plate 17 is interposed between the wide surface 11a of the core material 10 and the restraining plate 21. Either a steel plate or a wooden plate can be used as the insert plate 17, and the wooden plate can be, for example, laminated veneer lumber (LVL). Note that in this embodiment, too, the protrusions 15 may extend beyond the upper and lower planes of the narrow portion 13.

[0118] In the wide surface of the inner plate 17, a slit 18 is opened at the longitudinal end at a position corresponding to the reinforcing rib 14 of the core material 10 so as not to interfere with the reinforcing rib 14. In addition, the inner plate 17 is opened with a bolt hole 17a at a position corresponding to the bolt hole 16a opened in the spacer 16, and a first long bolt 31 shown in Figure 2 is inserted therethrough.

[0119] With the buckling-restrained brace 100A, as shown in FIG. 19 , higher-order buckling deformation of the core material 10 causes a localized compressive force P to act from the core material 10 on the restraining plate 21. This localized force P can lead to damage to the wooden restraining plate 21. Therefore, by interposing an insert plate 17 between the wide surface 11a of the core material 10 and the restraining plate 21, the force P acting from the convex portion 10a of the higher-order buckling deformation of the core material 10 is first transmitted to the insert plate 17. The transmitted force P then spreads within the insert plate 17, and the dispersed force within the insert plate 17 acts on the wooden restraining plate 21 as a dispersed force q. This effectively prevents damage to the wooden restraining plate 21 due to multiple localized forces P acting from the core material 10.

[0120] [Study of overall buckling] Next, we will explain the design method for preventing global buckling of buckling-restrained braces.

[0121] When designing a buckling-restrained brace, the following formula (2) must be satisfied to prevent global buckling of the buckling-restrained brace.

[0122]

number

[0123] Here, the bending moment acting on the center of the restraint plate can be expressed by the following equation (3).

[0124]

number

[0125] The condition for preventing the overall buckling of the wooden restraint member is to satisfy the following equation (4).

[0126]

number

[0127] Equation (4) is shown in Figure 20 as the global bending stress curve for the buckling-restrained brace. In Figure 20, the upper side of the global bending stress curve is the safe zone, and the lower side is the dangerous zone. The design axial force of the wooden restraint member, the Euler load, the length of the general part of the core member, and the yield bending strength of the wooden restraint member are set so that they fall within the safe zone. Note that the global bending stress curve for the buckling-restrained brace shown in Figure 20 applies to both global buckling in the weak axis direction of the core member and global buckling in the strong axis direction.

[0128] In addition to examining the relationship between the yield bending strength of the wooden restraint material and the bending moment acting on it, it is also advisable to examine the fact that the short-term allowable bending strength of the wooden restraint material will be greater than the bending moment acting on it when the core material yields (formula omitted).

[0129] <Study on the compressive failure of wooden restraints> Next, we will explain how to evaluate the failure of wooden restraints due to the core material penetrating into the wooden restraint. To prevent the wooden restraint from failing due to the core material penetrating into the wooden restraint, we verify that the following formula (5) is satisfied.

[0130]

number

[0131] In addition to examining the relationship between the compressive strength of the restraining plate and the stiffening force acting on it, it is also advisable to examine whether the short-term allowable compressive strength of the restraining plate is greater than the stiffening force acting when the core material yields (formula omitted).

[0132] <Consideration of specifications for the first long bolt (weak axis direction bolt) and the second long bolt (strong axis direction bolt)> Next, a method for setting the specifications of the first long bolts (weak axis direction bolts) and the second long bolts (strong axis direction bolts) will be described.

[0133] When setting the specifications for the first long bolts (weak axis direction bolts) and second long bolts (strong axis direction bolts), the sum of the yield strengths of each long bolt must be set to be equal to or greater than the sum of the reinforcing forces acting on the wooden restraint material, and the specifications of each long bolt (yield stress, number, effective cross-sectional area (effective cross-sectional area per bolt and total effective cross-sectional area due to the number of bolts), etc.) must be determined so as to satisfy the following formula (6).

[0134]

number

[0135] It should be noted that the present invention is not limited to the configurations shown here, and other embodiments may be possible in which other components are combined with the configurations described in the above embodiments. In this regard, the present invention can be modified within the scope of the present invention, and can be appropriately determined depending on the application form. [Explanation of symbols]

[0136] 10: Core material 11a: Wide surface 11b:Narrow side 12: Wide section 12a: Bolt hole 13: Narrow section 14: Reinforcing rib 14a: Bolt hole 15: Protrusion 16: Spacer 16a: Bolt hole 17: Interpolation board 17a: Bolt hole 20, 20A, 20B, 20C, 20D, 20E: Wooden restraints 21: Restraint plate 21a: First bolt hole 21b: First bolt hole unit 21c: Second bolt hole 22,22A,22B,22C: Side plate 22a: Second bolt hole 22b: Second bolt hole unit 22c: Engagement hole 22d: Steel plate accommodation groove 23: Non-contact groove 24: Slit 25: Gap 26: Center side panel 27: End side plate 28: Piercing method 29A: Hammer (end restraining material) 29A':Hachi 29B: Steel plate (end restraining material) 29C: Fiber reinforcement material (edge ​​restraint material) 29a: Joint 29b: Piercing part 31: First long bolt 32: Washer 33: Nut 34: Washer 41: Second long bolt 42: Washer 43: Nut 44: Washer 45: Steel plate for reinforcement 100,100A: Buckling restrained brace G1, G2, G3, G4, G5: Gap A: Additional bending absorption area (boundary area) S: Frame (composition) C: Pillar B: Beam GP: Gusset plate FS: Fin stiffener SP: Splice plate

Claims

1. A steel plate-shaped core material, a wooden restraining member formed by a pair of wooden restraining plates arranged so as to face the two wide surfaces of the core material, and a pair of wooden side plates arranged so as to face the two narrow surfaces of the core material and connected to the pair of restraining plates; The ends of the pair of restraint plates are connected by end restraint members, which are clamps, A buckling restraint brace characterized in that the two piercing portions of the clamp are inserted into fixing holes opened in the pair of restraint plates and fixed by adhesive.

2. a non-contact groove that does not come into contact with the wide surface of the core material is provided at an end of the restraint plate; 2. The buckling restraint brace according to claim 1, wherein the area of ​​the restraint plate other than the non-contact groove is in contact with the wide surface of the core material.

3. the core material has a narrow portion at a center side in a longitudinal direction where the width of the wide surface is relatively narrow, and a wide portion at an end side in a longitudinal direction where the width of the wide surface is relatively wide, 3. The buckling restraint brace according to claim 2, wherein the non-contact groove extends from an edge of the restraint plate to a position corresponding to the boundary between the wide portion and the narrow portion of the core material.

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