Buckling-restrained brace

Abstract

In a buckling-restrained brace in which a wooden buckling-restraining member is attached around a steel plate-shaped core, the buckling-restraining member, which consists of multiple wooden members, is made into a simple structure, and the deformation of the core is strongly restrained and kept to a minimum by being configured in a way that is suited to the characteristics of the wooden members. [Solution] The buckling restraint member 21 has a pair of wide-face opposing members 22a, 22b that face both sides of the wide surface of the core material 11, and a pair of side edge restraint members 23a, 23b that abut against both of the pair of wide-face opposing members so as to sandwich them. The side edge restraint members are made by laminating board material 31a, 31b in which the wood fibers are oriented along the axis of the core material, and board material 32a, 32b in which the fibers are oriented in a direction approximately perpendicular to the axis of the core material and are continuous so as to span between both of the pair of wide-face opposing members. The side edge restraint member is provided with a groove in the axial direction of the core material, the side edge of the core material is fitted into the groove, and the displacement of the core material in the direction perpendicular to the axis is restrained within the groove.

Description

Technical Field

[0001] The present invention relates to a brace used to resist horizontal forces in a building having columns and beams as main structural members, and particularly to a brace provided with a buckling restraint material for suppressing buckling when a compressive force acts.

Background Art

[0002] Generally, braces are arranged in an inclined direction within a frame surrounded by columns and beams, or within a rectangular frame surrounded by beams, foundations, and columns, and restrain deformation when a horizontal force acts on the structural frame. Compressive or tensile forces act on the brace depending on the direction of the horizontal force, and in order to function effectively regardless of the direction of the force, buckling when a compressive force acts must be suppressed. In particular, when plastic deformation of the brace is allowed to absorb vibration energy during an earthquake or the like and effectively attenuate the vibration, it is necessary to prevent buckling.

[0003] In recent years, many technologies for lignifying structural members have been proposed, and proposals for using wooden materials as buckling restraint materials for braces are disclosed in, for example, Patent Document 1 and Patent Document 2. These technologies involve attaching wooden members so as to surround a core material made of steel, and restraining bending deformation of the core material with the wooden members.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] As described in Patent Document 1 or Patent Document 2, in order to attach wooden members to a steel core, it is necessary to attach multiple wooden members to the core in combination. When a buckling restraint material is composed of multiple wooden members in this way, a force acts in a direction that pulls apart the bonds between the multiple wooden members by restraining the buckling of the core. In addition, a force acts that tends to cause cracks in the wooden members whose fibers extend in the axial direction of the core. For this reason, a buckling restraint material made up of combined wooden members is required to firmly bond the multiple wooden members and effectively suppress the occurrence of axial cracks in the wooden members.

[0006] The buckling-restraining brace described in Patent Document 1 is constructed by fastening multiple wooden members, which are mounted around a core material, with multiple bolts arranged along the axis of the core material to form a buckling-restraining member. Two bolt rows are provided along both sides of the core material, and two more bolt rows are provided perpendicular to these two rows. As a result, the structure becomes complex during the processing of bolt holes, requiring many steps.

[0007] On the other hand, the brace described in Patent Document 2 connects multiple wooden members with two rows of bolts arranged on both sides of the core material, and prevents cracking in the buckling-restraining member by including a board material in which the wood fibers extend in the direction spanning between these bolt rows, that is, in a direction approximately perpendicular to the axis of the core material. However, for braces used in large structures, there is a need for a buckling-restraining brace that more strongly restrains the deformation of the core material and restrains it while keeping the deformation of the core material to a minimum.

[0008] The present invention has been made in view of the above circumstances, and its purpose is to provide a buckling-restraining brace that has a simple structure for a buckling-restraining member consisting of multiple wooden members attached around a steel core, and that can strongly restrain the deformation of the core with a configuration suited to the characteristics of the wooden members, thereby keeping the deformation of the core to a minimum. [Means for solving the problem]

[0009] To solve the above problems, the invention according to claim 1 is a buckling restraint brace having a long, narrow steel plate-shaped core material and a wooden buckling restraint member arranged along the axial direction of the core material and mounted so as to surround the core material, wherein the buckling restraint member has a pair of wide surface opposing members arranged to face each other on both sides along the axial direction of the core material at the center of the wide surface of the core material and a pair of side edge restraint members that each abut against both of the pair of wide surface opposing members and are joined so as to sandwich the pair of wide surface opposing members, wherein the side edge restraint member is made by laminating and bonding a plurality of plates including a plate material in which the wood fibers are oriented in the direction along the axis of the core material and a plate material in which the wood fibers are oriented in a direction substantially perpendicular to the axis of the core material and are continuous in the area spanning between both of the pair of wide surface opposing members, The buckling-restrained brace is provided in which the side edge restraining member has a groove in the axial direction of the core material, the side edge of the core material is fitted into the groove, and the displacement of the core material in a direction perpendicular to the axis is restrained within the groove.

[0010] In the buckling-restrained brace described above, when a compressive force is applied to the steel core, the buckling-restraining member, which is positioned to surround the core, restrains displacement in a direction perpendicular to the core's axis, thereby preventing buckling of the core. The core is pressed against the inner surface of the groove and restrained against deformation perpendicular to the wide surface of the plate-shaped core, i.e., buckling in the weak axis direction. As a result, a tensile force is generated in the side edge restraining member perpendicular to the wide surface of the core, but the plate material, whose fibers extend in a direction approximately perpendicular to the core's axis, resists the tensile force, suppressing cracking in the buckling-restraining member in the direction of the core's axis. Furthermore, the side edge restraint member is made by bonding together a plate in which the wood fibers are oriented along the axis of the core material and a plate in which the wood fibers are oriented almost perpendicular to the axis of the core material. This provides large bending rigidity in the axial direction of the core material, and allows for a sufficiently large cross-sectional area of ​​the plate in which the fibers extend perpendicular to the core material, resulting in a large restraining force against buckling of the core material.

[0011] The invention according to claim 2 is a buckling-restrained brace according to claim 1, wherein each of the pair of side edge restraining members is provided with an intermediate layer between two boards in which the direction of the wood fibers is aligned with the axis of the core material, and one or more boards in which the direction of the wood fibers is approximately perpendicular to the axis of the core material.

[0012] In this buckling-restrained brace, two plates, with the wood fibers oriented along the axis of the core material, are formed to sandwich an intermediate layer containing a plate with the wood fibers oriented almost perpendicular to the axis of the core material. As a result, the plate with axially oriented fibers maintains high bending rigidity in the axial direction of the core material, and the thickness of the intermediate layer can be appropriately set to provide high resistance to cracking.

[0013] The invention according to claim 3 is a buckling-restrained brace according to claim 1, wherein the side edge of the core material fitted into the groove provided in the side edge restraining member is within the range of the thickness of the plate material in which the wood fibers are oriented in a direction substantially perpendicular to the axis of the core material.

[0014] In this buckling-restrained brace, the side edges of the core material are thrust into the plate material where the wood fibers are oriented approximately perpendicular to the axis of the core material. The force pressing the buckling restraint material due to buckling in the weak axis direction acts from the side edges of the wide surface of the core material onto the plate material where the fibers are oriented approximately perpendicular to the axis. In other words, the bearing pressure acts in the direction of the wood fibers of the plate material, where the wood fibers are continuous and approximately perpendicular to the axis of the core material. When a large bearing pressure is applied to wood, the deformation of the bearing surface, i.e., the deformation that causes the core material to sink into the wood, is significantly smaller when the bearing pressure is applied in the direction of the wood fibers than when it is applied perpendicular to the wood fibers. Therefore, by thrusting the core material into the plate material where the wood fibers are oriented perpendicular to the axis, it is possible to suppress the deformation of the buckling restraint material and strongly restrain the core material. Furthermore, buckling in the weak axis direction exerts a compressive force that pushes a portion of the buckling restraint member out of the core material, and a shear force acts on the buckling restraint member perpendicular to the axis of the core material. In this buckling restraint brace, the side edge of the core material is within the thickness range of the plate material where the wood fibers are continuous in a direction approximately perpendicular to the axis of the core material, so the shear force acts in the direction of the wood fibers of the plate material where the fibers are perpendicular to the axis of the core material. Generally, the strength of wood when a shear force acts in the direction of the fibers is about two to three times that when a shear force acts perpendicular to the direction of the fibers. In the buckling restraint brace according to this claim, as described above, the shear force that acts when restraining buckling in the weak axis direction acts in the direction of the wood fibers. Therefore, the buckling restraint member has great resistance to shear failure in the weak axis direction.

[0015] The invention according to claim 4 is a buckling-restrained brace according to claim 1, wherein a steel plate is mounted along the axial direction of the core material, extending from the portion of the side edge restraining member that abuts against the surface facing the wide surface opposing member, through the portion along the inner surface of the groove, to the portion that abuts against the bottom surface of the groove.

[0016] In this buckling-restrained brace, the force that restrains the buckling of the core material acts on the side edge restraining member via a steel plate. As a result, the force is distributed, deformation of the side edge restraining member is suppressed, and deformation of the core material can be strongly restrained. In particular, for deformation due to buckling in the direction parallel to the wide surface of the core material, i.e., in the strong axis direction, the restraining force is distributed not only to the bottom surface of the groove formed in the side edge restraining member, but also to the surface facing the wide surface opposing member via the steel plate. This makes it possible to suppress deformation due to bearing pressure from the core material and cracking of the side edge restraining member. Furthermore, the steel plate may be continuous from the surface facing one of the wide-faced opposing members along one of the inner surfaces of the groove and through the bottom surface of the groove to the inner surface on the opposite side and the surface facing the wide-faced opposing member on the other side of the groove. However, as described in claim 5 below, it is preferable to use a steel plate that extends from the surface facing the wide-faced opposing member through the inner surface of the groove to the bottom surface of the groove, and to divide such a pair of steel plates at a position along the bottom surface of the groove. Furthermore, the steel plates used may also be those with a coating applied to the surface facing the core material to reduce friction, a coating layer formed on it, or other measures taken to reduce friction with the core material.

[0017] The invention according to claim 5 is a buckling-restrained brace according to claim 4, wherein the steel plate is composed of a pair of members mounted along both sides of the groove and is divided at a position along the bottom surface of the groove.

[0018] When deformation occurs in a higher-order buckling mode in the weak axial direction of the core material, a strong pressing force acts on both inner surfaces of the groove. If the steel plate is continuous from one inner surface to the opposite inner surface, the core material is strongly pressed against both inner surfaces of the groove, and there is a risk that the steel plate will restrict the axial displacement of the core material. In the buckling-restrained brace of the invention according to claim 5, the steel plate is divided at the bottom of the groove, and the portions along both sides of the groove are separated, thereby mitigating the restriction on the axial expansion and contraction of the core material.

[0019] The invention according to claim 6 is a buckling-restrained brace according to claim 1, wherein the core material has widened portions at both ends in which the wide surface is enlarged, and the buckling-restraining member is mounted so as to surround a standard portion in the axial direction of the core material in which the wide surface excluding the widened portions is of equal width.

[0020] If the buckling restraint material is provided to surround the widened section of the core material, it will sever the orthogonal members included in the side edge restraint members, causing the buckling restraint material to lose strength at its ends. However, in this buckling restraint brace, the buckling restraint material is limited to the standard section, thus avoiding the loss of strength at the ends of the buckling restraint material. Furthermore, if the buckling restraint material is provided to the widened section, it becomes necessary to process the side edge restraint members, etc., to accommodate the change in the cross-sectional dimensions of the core material in the widened section. However, by limiting the buckling restraint material to the standard section, these processes become unnecessary, and the manufacturing of the buckling restraint material is simplified.

[0021] The invention according to claim 7 is the buckling restraint brace according to claim 6, wherein at both ends of the core material, reinforcing ribs are provided which are attached substantially perpendicular to both surfaces of the wide surface, and the reinforcing ribs are provided in a range longer than the widened portion from both ends of the core material, and at both ends of the buckling restraint material, notches are provided in the wide surface facing member to avoid interference with the reinforcing ribs.

[0022] By providing reinforcing ribs at both ends of the core material, the ends of the core material are integrated with the reinforcing ribs and reinforced, and the cross-sectional area increases. As a result, when a compressive force or a tensile force acts on the buckling restraint brace, the portion where plastic deformation occurs in the core material is limited to the standard portion at the center, excluding the range where the reinforcing ribs are provided. Further, the reinforcing ribs are set longer than the widened portion of the core material, and since the bending rigidity in the weak axis direction increases in this portion, the possibility of buckling in the weak axis direction is limited to a limited range at the center excluding the range where the reinforcing ribs are provided, and the buckling restraint material effectively restrains buckling. And although the range where the reinforcing ribs are provided overlaps with the range where the buckling restraint material is mounted, interference between the two is avoided by providing notches in the wide surface facing member.

[0023] The invention according to claim 8 is the buckling restraint brace according to any one of claims 1 to 7, wherein on the opposing surface of the wide surface facing member and the side edge restraint member or on the opposing surface of the side edge restraint member and the wide surface facing member, an adhesive escape groove for discharging the excess of the adhesive for joining these two members is formed in the axial direction of the core material.

[0024] When joining a pair of wide surface facing members so as to sandwich them between a pair of side edge restraining members, if an adhesive is applied to one or both of the facing surfaces and strongly pressed, excess adhesive moves along the facing surfaces and flows into the escape grooves formed in the facing surfaces. Then, it flows in the axial direction of the buckling restraint member and is discharged. As a result, it is possible to suppress the adhesive from flowing between the core material and the wide surface facing member or between the core material and the side edge restraining member, and to avoid the core material being adhered to the buckling restraint member and restricting the relative displacement between the core material and the buckling restraint member. Also, it is possible to avoid the adhesive flowing out to the outer peripheral surface of the buckling restraint member and deteriorating the appearance. Note that one or more escape grooves for the adhesive can be provided, and it is desirable to provide them at positions close to the core material on the facing surfaces of the wide surface facing member and the side edge restraining member and at positions close to the outer peripheral surface.

[0025] The invention according to claim 9 is the buckling restraint brace according to any one of claims 1 to 3, wherein the side edge restraining member includes a continuous plate material in a direction in which the fibers of the wood are substantially perpendicular to the axis of the core material and spanning between both of the pair of wide surface facing members, and a first adjusting surface that becomes one inner surface of the groove is formed on a first constituent member, and a second adjusting surface that becomes the other inner surface of the groove is formed on a second constituent member. The distance between the first adjusting surface and the second adjusting surface is adjusted to a distance that abuts or is close to both surfaces of the wide surface of the core material, and the first constituent member and the second constituent member are joined.

[0026] In this buckling-restrained brace, the side edge restraining member is formed by joining a member that is divided into a first component with a first adjustment surface that forms one inner surface of the groove and a second component with a second adjustment surface that forms the other inner surface of the groove. This allows for precise setting of the distance between the two opposing inner surfaces within the groove. Furthermore, it becomes easier to finish the inner surfaces smoothly. As a result, when the side edges of the core material are fitted in, the groove can be precisely set so that the inner surfaces of the groove abut against both sides of the wide surface or face each other with a very small gap, thereby reducing the restraining force that restrains the buckling of the core material, i.e., the force acting on the inner surface of the groove. In addition, because the inner surface of the groove is smooth, even when the inner surface of the groove abuts against the core material, the force that restrains the relative displacement between the core material and the side edge restraining member in the axial direction can be reduced.

[0027] The invention according to claim 10 is a buckling-restrained brace according to claim 9, wherein a shear resistance member is sandwiched between the joint surface of the first component and the second component, the member having a plurality of pointed convex portions, the convex portions having a tip that penetrates the first component and the convex portions having a tip that penetrates the second component.

[0028] In this buckling-restrained brace, a compressive force acts on the core material fitted into the groove, and when the side edge restraining members restrain the buckling of the core material, a force acts on the inner surface of the groove in a direction that tends to widen the groove. As a result, a shear force may act on the joint surface between the first component, on which one inner surface is formed, and the second component, on which the other inner surface is formed. However, the shear resistance members sandwiched at the joint surface restrain the relative displacement of the first and second components, and the width of the groove can be kept constant. [Effects of the Invention]

[0029] As described above, in the buckling-restrained brace of the present invention, the buckling-restraining member, which consists of multiple wooden members attached around a steel core, has a simple structure, and the deformation of the core can be strongly restrained with a configuration that is suited to the characteristics of the wooden members, thereby keeping the deformation of the core to a minimum. [Brief explanation of the drawing]

[0030] [Figure 1] This is a schematic side view showing a portion of the structural frame of a building in which a buckling-restrained brace, which is one embodiment of the present invention, is used. [Figure 2] Figure 1 is a schematic perspective showing a portion of the buckling-restrained brace. [Figure 3] Figure 2 is a schematic cross-sectional view of the buckling-restrained brace shown. [Figure 4] Figure 2 is an exploded perspective view of the buckling-restrained brace shown. [Figure 5] Figure 2 is a schematic cross-sectional view illustrating the effects of the configuration of the buckling-restrained brace shown. [Figure 6] This is a schematic cross-sectional view of a buckling-restrained brace, which is another embodiment of the present invention. [Figure 7] Figure 6 is a schematic perspective view showing some of the components that make up the buckling-restrained brace. [Figure 8] Figure 6 is a schematic cross-sectional view illustrating the effects of the configuration of the buckling-restrained brace shown. [Figure 9] Figure 6 is an exploded perspective view illustrating some of the components of the buckling restraint member shown. [Figure 10] This is a schematic cross-sectional view showing the process of manufacturing the side edge restraint member of the buckling-restrained brace according to the present invention. [Figure 11] Figure 10 shows a schematic perspective view and a front view illustrating an example of a shear resistance member that can be used with the side edge restraint member. [Figure 12] This is a schematic cross-sectional view showing another example of the process for manufacturing the side edge restraint member of the buckling-restrained brace according to the present invention. [Modes for carrying out the invention]

[0031] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figure 1 is a schematic side view showing a portion of the structural frame of a building in which a buckling-restrained brace, which is one embodiment of the present invention, is used. Figure 2 is a schematic perspective view showing a portion of the buckling-restrained brace shown in Figure 1, Figure 3 is a schematic cross-sectional view, and Figure 4 is an exploded perspective view of the same buckling-restrained brace. This buckling-restrained brace 1 is installed within the frame of the structural frame, which is formed in a rectangle by columns 2 and 3, the beam 4 of the lower floor, and the beam 5 of the upper floor. The two braces are positioned with their inclination directions opposite to each other, with their lower ends joined to the joint between the beam 4 of the lower floor and columns 2 and 3, and their upper ends joined to the center of the span of the beam 5 of the upper floor. As a result, when a horizontal force acts on a building whose main structural members are columns and beams, a compressive force acts on one of the two buckling-restrained braces 1 and a tensile force acts on the other, suppressing inter-story deformation between the lower and upper floors.

[0032] The buckling-restrained brace 1 described above comprises a core material 11 made of steel and a wooden buckling-restraining member 21 provided to surround the core material. The core material 11 described above is made of a strip-shaped steel plate, and at both ends the wide surface of the strip-shaped core material 11 is widened from the central part, forming a widened section 11a for joining to a structural frame such as a column. At the ends including the widened section 11a, reinforcing ribs 12 made of steel plates of almost the same thickness are welded almost vertically to both sides of the strip-shaped core material 11, forming a cross-shaped cross section. These stiffening ribs 12 are provided in a range slightly longer than the widened section 11a from both ends of the core material 11, and some extend to the standard section where the wide surface is of almost equal width. Multiple bolt holes 13 are provided in the widened section 11a and the reinforcing rib 12, and they are bolted to the structural frame via a splice plate that is placed between them and the connecting plate 6 provided on the structural frame.

[0033] The buckling restraint member 21 described above is made up of multiple wooden members and is provided to surround the core material 11 along its axial direction. The multiple wooden members include a pair of wide-face opposing members 22a, 22b that face the two wide faces of the core material 11, and a pair of side edge restraint members 23a, 23b that have width in the thickness direction of the core material 11 and contact both of the wide-face opposing members 22a, 22b so as to sandwich them. These wooden members have approximately the same length in the axial direction of the core material 11 and surround the standard section in which the wide faces in the central part of the core material in the longitudinal direction are approximately equal in width, except for the widened portions 11a provided near both ends of the core material 11. In other words, the widened portions 11a of the core material protrude from both end faces of the buckling restraint member 21.

[0034] The wide-face opposing members 22a, 22b and the side edge restraining members 23a, 23b are joined together by adhesive and fastened with multiple bolts 26. As shown in Figure 4, the wide-face opposing members 22a, 22b and the side edge restraining members 23a, 23b are provided with multiple bolt holes 24, 25 at positions on both sides of the core material 11. The bolt holes 24, 25 in the wide-face opposing members 22a, 22b and the side edge restraining members 23a, 23b correspond to each other during joining. Bolts 26 are inserted through these bolt holes 24, 25 and fastened from one side edge restraining member 23a through one wide-face opposing member (22a or 22b) and the other side edge restraining member 23b, thereby joining these members together.

[0035] The wide-face opposing members 22a and 22b described above can be made of solid wood, laminated timber made by bonding together small-section wood with fibers extending in the axial direction of the core material, laminated veneer lumber (LVL), cross-laminated timber (CLT), etc., and the width of the surface facing the wide surface of the core material 11 is smaller than the width of the standard part of the core material 11. The surface facing the core material is either in contact with the wide surface of the core material 11 or faces both sides of the core material 11 with a small gap between them. When positioned in contact with the core material 11, they are not strongly pressed together, but rather allow relative displacement of the core material 11 and the wide-face opposing members 22a and 22b along the opposing surface in the axial direction of the core material 11. When facing with a gap, the gap should be small enough to restrain the bending deformation of the core material 11 and effectively suppress buckling, for example, it is desirable to have a gap of about 0.1 mm to 1.0 mm.

[0036] Near the ends of the wide, opposing members 22a and 22b, notches 22c are formed on the surfaces facing the core material 11 to avoid interference with the reinforcing ribs 12 provided at the ends of the core material 11.

[0037] The above-mentioned side edge restraint members 23a and 23b are made by laminating and bonding together, for example, plates with a thickness of about 20 mm to 40 mm, and cross-laminated timber (CLT) can be used. In this embodiment, two plates (axial plates) 31a and 31b, whose fiber direction is in the axial direction of the core material 11, are laminated and bonded together with two layers of plates (orthogonal plates) 32a and 32b, whose fiber direction is almost perpendicular to the core material 11. These side edge restraint members 23a and 23b have grooves 33 formed in the axial direction of the core material 11, approximately in the center of the surface facing the wide surface opposing members 22a and 22b. These grooves 33 have a width slightly wider than the thickness of the core material 11, and when the side edge restraint members 23a and 23b come into contact with the wide surface opposing members 22a and 22b, the side edges of the core material 11 fit into the grooves 33, and the bottom surface 33a of the groove has a depth such that it contacts or faces the narrow surface of the core material 11 with a very small gap. Furthermore, the bottom surface 33a of the groove is within the thickness range of the orthogonal members 32b of the side edge restraint members 23a and 23b, and the portion of the core material 11 adjacent to the side edge of the wide surface faces the orthogonal members 32b that constitute the inner surface of the groove 33.

[0038] The orthogonal members 32a and 32b of the above-mentioned side edge restraint members 23a and 23b have continuous fibers in the area facing the pair of wide surface opposing members 22a and 22b, and in the thickness excluding the portion cut out by the groove 33, they prevent axial cracking from occurring in the side edge restraint members 23a and 23b. The combination of lamination of the axial member and the orthogonal member of the above-mentioned side edge restraining members 23a and 23b can be designed as appropriate, but it is desirable to provide an intermediate layer containing an orthogonal member between the two axial members 31a and 31b, as shown in the embodiment in Figure 3. The intermediate layer contains one or more orthogonal members and may contain an axial member, but it is desirable to laminate the plate material such that the bottom surface of the groove is located within the thickness range of the orthogonal member in the intermediate layer.

[0039] As shown in Figure 3, the bolts 26 are arranged almost parallel to the wide surface of the core material 11, at positions away from the wide surface on both sides of the core material 11, and at predetermined intervals in the axial direction of the core material. Each of these bolts 26 passes through a pair of side edge restraint members 23a, 23b and a wide surface opposing member (22a or 22b), and by tightening the twisted nuts 27, the pair of side edge restraint members 23a, 23b and the wide surface opposing members 22a, 22b sandwiched between them are pressed together.

[0040] In this type of buckling-restrained brace 1, the core material 11, which is connected at both ends to the structural frame of the building, resists inter-story deformation between the upper and lower floors of the building. When compressive forces are applied, bending deformation is restrained by the buckling-restraining member 21, and buckling is suppressed. Furthermore, when compressive plastic deformation repeatedly occurs in the core material 11 during earthquakes, etc., restraining buckling causes the stress-strain curve to form a large loop, making it possible to effectively absorb vibrational energy.

[0041] On the other hand, the buckling restraint member 21 is firmly bonded to the side edge restraint members 23a and 23b and the wide surface opposing members 22a and 22b by adhesive and bolts 26. Between the two rows of bolts positioned on both sides of the core material 11, the side edge restraint members 23a and 23b include orthogonal members 32a and 32b, whose fibers extend in a direction perpendicular to the axis of the core material 11. These orthogonal members prevent cracking or failure of the buckling restraint member 21. In other words, wood has great tensile strength in the direction of its fibers, and the tensile resistance of the orthogonal members 32a and 32b, whose fibers extend in a direction almost perpendicular to the axis of the core material 11, prevents cracking of the side edge restraint members 23a and 23b in the axial direction.

[0042] Furthermore, grooves 33 are provided in the side edge restraint members 23a and 23b, into which the side edges of the core material 11 are fitted. When the core material 11 attempts to buckle in the direction perpendicular to the wide surface, i.e., in the weak axis direction, as shown in Figure 5, a pressing force is applied to the inner surface of the grooves 33 provided in the side edge restraint members 23a and 23b and to the wide surface opposing members 22a and 22b. At this time, the portion of the core material 11 adjacent to the side edge, i.e., the portion indicated by reference numeral 11b in Figure 5, comes into contact with the orthogonal member 32b within the groove 33, and the pressing force acts in the direction of the fibers of the orthogonal member 32b. Generally, when a large bearing force is applied to wood, the deformation of the bearing surface, i.e., the deformation that causes the wood to sink in, is smaller when the bearing force is applied in the direction of the wood fibers than when it is applied perpendicular to the direction of the fibers. Therefore, the deformation of the core material 11 is suppressed to a small extent by the orthogonal member 32b, and the core material 11 is strongly restrained.

[0043] Furthermore, when a pressing force is applied from the core material 11 to the inner surface of the groove 33 and the wide-faced opposing member, the wide surface of the core material 11 acts to push the opposing portion of the buckling restraint member 21 outward. That is, it acts to push outward the area including the wide-faced opposing member 22b enclosed by the two dashed lines 41 shown in Figure 5 and the core material 11, generating a shear force along the dashed line 41. At this time, the side edge of the core material 11 is within the thickness range of the orthogonal member 32b, whose fibers extend in a direction approximately perpendicular to the axis of the core material 11, so that at the position of the dashed line 41, the wood fibers extend in the direction in which the shear force acts. Wood generally has a greater shear strength against a shear force acting in the direction of the wood fibers than when a shear force acts perpendicular to the fibers. Therefore, because the side edges of the core material 11 are within the thickness range of the orthogonal material 32b, it has great resistance to shear failure of the buckling restraint material 21 due to buckling in the weak axis direction of the core material 11.

[0044] Furthermore, in this buckling-restrained brace 1, the buckling restraint member 21 is installed so as to surround a range limited to the standard part of the core material 11, excluding the widened portion 11a, and does not restrain the widened portion 11a of the core material. The cross-section of the core material 11 is enlarged in the widened portion, and the bending stiffness is increased, so the bending stiffness changes between the widened portion and the standard part. If there is a sudden change in bending stiffness, when the structural frame deforms, the bending deformation of the buckling-restrained brace 1 may concentrate at the part where the bending stiffness changes, that is, at the boundary between the widened portion and the standard part. In this buckling-restrained brace 1, the buckling restraint member 21 restrains the bending deformation limited to the standard part, while allowing the bending deformation between the widened portion and the standard part. This makes it possible to suppress buckling of the core material 11 and prevent the buckling restraint member 21 from being damaged by a large local bearing pressure acting from the core material 11.

[0045] Furthermore, if the buckling restraint member 21 is provided to surround the widened portion of the core material 11, it will sever the orthogonal members included in the side edge restraint members 23a and 23b, causing the buckling restraint member 21 to lose strength at its ends. However, by limiting the provision of the buckling restraint member 21 to the standard portion, this loss of strength at the ends of the buckling restraint member 21 can be avoided. Additionally, if the buckling restraint member 21 is provided to the widened portion, it will be necessary to process the side edge restraint members, etc., to accommodate the change in the cross-sectional dimensions of the core material 11 in the widened portion. However, by limiting the provision of the buckling restraint member 21 to the standard portion, these processes become unnecessary, and the production of the buckling restraint member 21 becomes easier.

[0046] In addition to the above configuration, the following configuration can also be adopted for the buckling-restrained brace 1 described above. A coating that reduces friction and is water-repellent can be formed on the surfaces of the wide-face-facing members 22a, 22b and the side-edge-restraining members 23a, 23b that face the core material 11. The coating can be formed, for example, by applying or spraying a silicone resin. This prevents moisture from penetrating near the surfaces of the wide-face-facing members 22a, 22b and the side-edge-restraining members 23a, 23b that face the core material 11, reduces friction between the core material 11 and the buckling restraining member 21, and reduces the restraint of the axial deformation of the core material 11 by the buckling restraining member 21. Therefore, the effect of absorbing vibration energy when plastic deformation occurs in the core material 11 is well maintained.

[0047] Figure 6 is a cross-sectional view of a buckling-restrained brace, which is another embodiment of the present invention. This buckling-restrained brace uses the same core material 11 as the buckling-restrained brace 1 shown in Figures 2 and 3, and the buckling-restraining member 51 is also the same as the buckling-restrained brace 1 shown in Figure 2, with a pair of wide-face-facing members 52a, 52b and a pair of side-edge-restraining members 53a, 53b joined together to surround the core material 11. The wide-face-facing members 52a, 52b are the same as those used in the buckling-restrained brace 1 shown in Figures 2 and 3, and the side-edge-restraining members 53a, 53b are similarly made by laminating and bonding axial members 61a, 61b and orthogonal members 62a, 62b, forming a groove 54 into which the core material 11 is fitted. Steel plates 55 are attached to these side-edge-restraining members 53a, 53b from a part of the surface facing the wide-face-facing members 52a, 52b along the inner surface and bottom surface of the groove 54. As shown in Figure 7, these steel plates 55 are fitted into the groove 54 over almost the entire length of the side edge restraining members 53a and 53b, and are continuous from the surfaces facing the wide surface opposing members 52a and 52b on both sides of the groove 54 to a position along the inner surface of the groove 54 and a position along the bottom surface, with the steel plates 55 mounted on both sides of the groove 54 being separated in the middle of the bottom surface of the groove.

[0048] Furthermore, while the steel plate can be a continuous piece extending from one side of the groove 54 to the inside of the groove 54 and to the other side, as shown in Figure 7(b) (steel plate 56), it is preferable that it be separated on both sides of the groove 54 at a position along the bottom surface inside the groove, as shown in Figure 7(a).

[0049] The buckling-restrained braces shown in Figures 6 and 7 function similarly to the buckling-restrained brace 1 shown in Figures 2 and 3, and also produce the effects described below. When the core material 11 attempts to buckle in the direction parallel to the wide surface, i.e., in the strong axis direction, a pressing force acts on the bottom surface of the groove 54 from the narrow surface of the core material 11 via the steel plate 55, as shown by arrow 42 in Figure 8. Also, as shown by arrow 43 in Figure 8, a pressing force in the direction parallel to the wide surface of the core material 11 acts on the opposing surfaces of the wide surface opposing members 52a and 52b of the side edge restraining member 53a via the steel plate 55, thus distributing the force that restrains the displacement of the core material 11. The pressing force acting from the core material 11 on the bottom surface of the groove 54 generates a tensile force at the position along the dashed line 44 shown in Figure 8. However, since the pressing force acting from the core material 11 is distributed via the steel plate 55 to the opposing surfaces of the wide surface opposing members 52a and 52b, the tensile force acting on the surface shown by the dashed line 44 is reduced, and cracking of the orthogonal member 62b can be suppressed. Furthermore, because the pressing force from the core material 11 is concentrated at the center of the side edge restraint member 53a in the width direction, it is possible to suppress the occurrence of axial cracks on the outer surface of the side edge restraint member 53a at the position indicated by the dashed line 45 in Figure 8.

[0050] Furthermore, as shown in Figure 7(a), the separation of the steel plate 55 on both sides along the bottom surface of the groove 54 allows the core material 11 to deform in a higher-order buckling mode in the weak axial direction, and when the core material 11 is strongly pressed against both inner surfaces within the groove 54, relative displacement of the two separated steel plates 55 is permitted, thereby easing the constraint on the axial expansion and contraction of the core material 11.

[0051] In the buckling-restrained brace 51 shown in Figure 6, narrow grooves 57 are provided on the surfaces of the wide-face-facing members 52a and 52b that face the side edge restraining members 53a and 53b. As shown in Figures 6 and 9, these grooves 57 are provided in portions close to the surface facing the core material 11 and in portions close to the outer circumferential surface of the buckling-restraining member, and are continuous in the axial direction of the core material 11. These grooves 57 function as relief grooves 57 for adhesive applied to the opposing surfaces when joining the wide surface-facing member and the side edge-restraining member.

[0052] When a pair of wide-face opposing members 52a, 52b are joined by a pair of side-edge restraining members 53a, 53b, the adhesive applied to one or both of the opposing surfaces moves along the opposing surfaces due to the strong pressure applied to both surfaces. The excess adhesive then flows into the adhesive relief groove 57 formed on the opposing surfaces and is discharged by flowing in the axial direction of the buckling restraining member 51. This prevents the adhesive from flowing between the core material 11 and the wide-face opposing members 52a, 52b or between the core material 11 and the side-edge restraining members 53a, 53b, thus preventing the core material 11 from bonding with the buckling restraining member 51 and restraining the relative displacement of both. It also prevents the adhesive from flowing out onto the outer surface of the buckling restraining member 51 and spoiling its appearance. Such relief grooves 57 can also be provided in the buckling-restrained brace 1 shown in Figures 2 and 3.

[0053] In the brace having the buckling restraint member described above, the displacement of the core material is restrained within the groove of the side edge restraint member in the event of buckling in the so-called weak axis direction. By setting a small gap between the core material and the inner surface of the groove, the restraining force acting on the side edge restraint member can be reduced. For this reason, it is desirable to set the groove so that the opposing inner surfaces of the groove are in contact with or very close to both sides of the core material with only a small gap. In order to form the groove so accurately, the side edge restraint member can be configured as follows.

[0054] As shown in Figure 10, the side edge restraint member 71 can be made of laminated and bonded board material 72, similar to the buckling restraint member shown in Figures 2 and 3, for example, cross-laminated timber (CLT), and includes board material 72a in which the direction of the wood fibers is in the axial direction of the core material 11, and board material 72b in which the direction of the wood fibers is approximately perpendicular to the core material 11. Such a laminated member can be formed by manufacturing two members by dividing the bottom surface of the groove 73 at a joint surface 74 that is approximately parallel to the laminated surface of the board material 72, as shown in Figure 10(a), and then joining these two members together.

[0055] The first component 71a, which has a first adjustment surface 73a formed on one inner surface of the groove 73, includes a board material 72b in which the direction of the wood fibers is approximately perpendicular to the axis of the core material 11, and this board material 72b is continuous with the region facing both of the two wide surface opposing members 75. The second component 71b has a second adjustment surface 73b formed on the other inner surface of the groove 73, and a board material 72c included in this second component 71b, in which the direction of the wood fibers is approximately perpendicular to the axis of the core material, is connected to the first component 71a. It is desirable that the first adjustment surface 73a and the second adjustment surface 73b be finished smoothly.

[0056] The first component 71a and the second component 71b are joined at a distance that allows the core material 11 to be fitted with the first adjustment surface 73a and the second adjustment surface 73b facing each other, such that the first adjustment surface 73a and the second adjustment surface 73b are in contact with or close to both sides of the core material 11. The joining can be done with the core material 11 or a steel plate of the same thickness as the core material 11 sandwiched between the first adjustment surface 73a and the second adjustment surface 73b.

[0057] As shown in Figure 10(b), the pair of side edge restraint members 71, each having a groove 73, are joined by fitting the side edge of the core material 11 into the groove 73, sandwiching two wide, opposing members 75, applying adhesive, and tightening bolts 77. The joined buckling restraint member 70 has a joint surface 74 between the first component 71a and the second component 71b, extending from the bottom surface of the groove 73 into which the core material 11 is fitted, almost parallel to the laminated surface of the plate material 72 constituting the side edge restraint member 71. A shear force acts on this joint surface 74 when restraining buckling of the core material 11 in the weak axis direction. This shear force may be resisted by an adhesive with sufficient adhesive strength, or by sandwiching a shear resistance member between the joint surface 74.

[0058] As the shear resistance member 76, for example, a steel member as shown in Figure 11 can be used. This shear resistance member 76 is made by making numerous cuts in a thin steel plate and bending up small, pointed triangular convex portions 76a. The convex portions 76a protrude from both sides of the steel plate and are distributed in multiple directions in the axial direction and perpendicular to the axis of the core material 11. This shear resistance member 76 is in the axial direction of the core material 11 and is sandwiched between the first component 71a and the second component 71b along the axial direction of the core material 11. By pressing them together tightly, the convex portions 76a penetrate the plate material 72 on both sides of the joint surface 74, preventing the plate material 72 from shifting on both sides of the joint surface 74. Furthermore, the shear resistance members are not limited to those shown in Figure 11; other forms can also be used, such as those with convex portions that penetrate both sides of the joint surface and are independently and dispersed.

[0059] Furthermore, the forms of the first and second components constituting the side edge restraint member are not limited to those shown in Figure 10, and for example, forms such as those shown in Figure 12 can also be adopted. In the side edge restraint member 81 shown in Figures 12(a) and (b), the joint surface 84 between the first component 81a and the second component 81b is set approximately parallel to the laminated surface of the plate material 82 from one corner of the bottom surface of the groove 83, but is bent toward the contact surface with the wide surface opposing member 85 before reaching the side edge of the plate material 82. Furthermore, in the side edge restraint member 91 shown in Figures 12(c) and (d), the joint surface 94 between the first component 91a and the second component 91b is set to be inclined toward the laminated surface of the plate material 92, from one corner of the bottom surface of the groove 93 toward the side edge of the contact surface with the wide surface opposing member 95. Even with these side edge restraint members 81 and 91, grooves 83 and 93 into which the core material 11 is fitted can be accurately formed, and the buckling of the core material 11 can be restrained in the same way as the side edge restraint member 71 and buckling restraint member 70 shown in Figure 10.

[0060] The brace having the buckling restraint member described above is an embodiment of the present invention, and the present invention is not limited to these, but can be designed as appropriate within the scope of the present invention. [Explanation of Symbols]

[0061] 1: Buckling-restrained brace, 2: Column, 3: Column, 4: Beam on the lower floor, 5: Beam on the upper floor, 6: Connecting plate 11: Core material, 11a: Widened portion of the core material, 11b: Portion adjacent to the side edge of the core material, 12: Reinforcing rib, 13: Bolt holes provided in the core material and reinforcing rib, 21: Buckling restraint member, 22a, 22b: Wide face-facing member, 22c: Notch provided in the wide face-facing member, 23a, 23b: Side edge restraint member, 24, 25: Bolt hole, 26: Bolt, 27: Nut, 31a, 31b: Plate material with the fiber direction aligned with the core material axis (axial material), 32a, 32b: Plate material with the fiber direction approximately perpendicular to the core material (orthogonal material), 33: Groove provided in the side edge restraining member, 33a: Bottom surface of the groove, 41: A dashed line indicating the expected shear failure surface, 42: Force acting from the core material to the bottom surface of the groove, 43: Force acting from the core material through the steel plate to the wide surface of the side edge restraining member facing the opposing member, 44: A dashed line indicating the expected location of crack occurrence, 45: A dashed line indicating the expected location of crack, 51: Buckling restraint member, 52a, 52b: Wide face-facing member, 53a, 53b: Side edge restraint member, 54: Groove provided in the side edge restraint member, 55, 56: Steel plate installed in the groove, 57: Narrow groove that functions as an adhesive escape groove, 61a, 61b: Axial members constituting the side edge restraint member, 62a, 62b: Orthogonal members constituting the side edge restraint member, 71: Side edge restraint member, 71a: First component member, 71b: Second component member, 72: Plate material constituting the side edge restraint member, 72a: Plate material with fiber direction aligned with the core material axis, 72b: Plate material with fiber direction approximately perpendicular to the core material, 73: Groove, 73a: First adjustment surface, 73b: Second adjustment surface, 74: Joining surface, 75: Wide surface opposing member, 76: Shear resistance member, 76a: Convex portion of shear resistance member, 77: Bolt, 81: Side edge restraint member, 81a: First component member, 81b: Second component member, 82: Plate material constituting the side edge restraint member, 83: Groove, 84: Joint surface, 85: Wide surface opposing member, 91: Side edge restraint member, 91a: First component member, 91b: Second component member, 92: Plate material constituting the side edge restraint member, 93: Groove, 94: Joint surface, 95: Wide surface opposing member

Claims

1. A long, slender, plate-shaped core made of steel, A buckling restraint brace comprising: a wooden buckling restraint member arranged along the axial direction of the core material and mounted so as to surround the core material, The buckling restraint member comprises a pair of wide surface-facing members arranged to face each other on both sides along the axial direction of the core material at the center of the wide surface of the core material, It comprises a pair of side edge restraint members, each of which abuts against both of the pair of wide surface opposing members and is coupled to the pair of wide surface opposing members so as to sandwich them, The side edge restraint member is formed by laminating and bonding together a plurality of boards, including boards in which the wood fibers are oriented along the axis of the core material, and boards in which the wood fibers are oriented approximately perpendicular to the axis of the core material, and which are continuous in the area spanning between the pair of wide, opposing members. The buckling-restrained brace is characterized in that the side edge restraining member has a groove in the axial direction of the core material, the side edge of the core material is fitted into the groove, and the displacement of the core material perpendicular to the axis is restrained within the groove.

2. The buckling-restrained brace according to claim 1, characterized in that each of the pair of side edge restraining members has an intermediate layer between two boards in which the direction of the wood fibers is aligned with the axis of the core material, and one or more boards in which the direction of the wood fibers is approximately perpendicular to the axis of the core material.

3. The buckling-restrained brace according to claim 1, characterized in that the side edge of the core material fitted into the groove provided in the side edge restraining member is within the range of the thickness of the plate material in which the wood fibers are oriented in a direction substantially perpendicular to the axis of the core material.

4. The buckling restraint brace according to claim 1, characterized in that a steel plate, which is continuous from the portion of the side edge restraint member that abuts against the surface facing the wide surface opposing member, through the portion along the inner surface of the groove, to the portion that abuts against the bottom surface of the groove, is mounted along the axial direction of the core material.

5. The buckling-restrained brace according to claim 4, characterized in that the steel plate is composed of a pair of members mounted along both sides of the groove and is divided at a position along the bottom surface of the groove.

6. The core material has widened portions at both ends where the wide surface is enlarged, The buckling restraint brace according to claim 1, characterized in that the buckling restraint member is mounted so as to surround the standard portion in the axial direction of the core material, where the widened surface, excluding the widened portion, is of equal width.

7. The core material is provided with reinforcing ribs attached to both ends of the wide surface, almost perpendicular to both sides. The reinforcing ribs are provided from both ends of the core material in a range longer than the widened portion, The buckling-restraining brace according to claim 6, characterized in that at both ends of the buckling-restraining member, notches are provided in the wide-face-facing member to avoid interference with the stiffening rib.

8. The buckling-restrained brace according to any one of claims 1 to 7, characterized in that an adhesive drainage groove for draining excess adhesive used to join the two members is formed in the axial direction of the core material on the surface of the wide-face-facing member facing the side edge restraining member, or on the surface of the side edge restraining member facing the wide-face-facing member.

9. The aforementioned side edge restraining member is A first component member having a first adjustment surface formed on one of the inner surfaces of the groove, which includes a continuous plate material spanning between both of the pair of wide, opposing members, with the wood fibers oriented in a direction substantially perpendicular to the axis of the core material, It is composed of a second component member having a second adjustment surface formed on the other inner surface of the groove, The buckling-restrained brace according to any one of claims 1 to 3, characterized in that the distance between the first adjustment surface and the second adjustment surface is adjusted to a distance where they abut or are close to both sides of the wide surface of the core material, and the first component and the second component are joined together.

10. The buckling-restrained brace according to claim 9, characterized in that a shear resistance member is sandwiched between the joint surface of the first component and the second component, the shear resistance member having a plurality of pointed convex portions, each having a convex portion that penetrates the first component and a convex portion that penetrates the second component.

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