JP2016180289A - Buckling-restrained brace and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a buckling-restrained brace which has intensity resistant to repeating great earthquakes with accurate restraint of a brace core material, can suppress warpage and post-repair that are a problem of welding and reduce a manufacturing cost.SOLUTION: A buckling-restrained brace 1 comprises: an external square pipe 4; a long tabular brace core material 2 which is arranged on the inner side of the external square pipe 4 and is brought into surface contact with the inner side of the external square pipe 4; and an inner square pipe 3 which is arranged on the inner side of the external square pipe 4, brought into surface contact with the surface opposite to the surface of the brace core material 2 brought into contact with the external squire pipe 4, and holds the brace core material 2 in the thickness direction with the external square pipe 4. The buckling-restrained brace 1 is formed with a caulking processing part 8 which is bent inward in the state where a side surface 41 of the external square pipe 4 and a side surface 31 of the inner square pipe 3 facing the direction orthogonal to the thickness direction of the brace core material 2 are overlapped with each other.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a buckling restrained brace for restraining a brace core material with a restraining member and a method for manufacturing the same.

  In buildings with a steel frame structure, buckling-restrained braces are used for bearing walls. Patent Documents 1 to 3 disclose this type of buckling restrained brace. Patent Documents 1 and 2 describe a buckling restrained brace having a structure in which a plurality of buckling restraining members are joined by welding in a state where a long plate-like brace core is sandwiched between a pair of buckling restraining members in the thickness direction. Is disclosed. Patent Document 3 discloses a structure in which a brace core material sandwiched between channel members is inserted into an external stiffener, and the brace core material is constrained by pressure from both sides of the entire external stiffener.

JP 2008-75280 A JP 2014-122462 A JP 2008-75281 A

  In the method of joining a buckling restraining member as disclosed in Patent Document 1 by welding, warping occurs due to shrinkage caused by welding. As a method for preventing the warp, a method in which the buckling restraining member is reversely warped in advance is conceivable, but a step of reverse warping is required. In this regard, in Patent Document 2, the occurrence of warpage can be effectively suppressed by optimizing the welding length and the welding position. However, since any method needs to perform a welding operation, there is a limit in suppressing warpage caused by welding. In addition, in order to obtain sufficient welding strength, welding burns and spatter occur, and it is necessary to remove spatters and repair the weld burn points, which improves productivity and reduces production costs. There was room for.

  In this regard, Patent Document 3 adopts a configuration in which an external stiffener that is sheathed on a brace core is deformed inward by pressure and the external stiffener is pressed against the brace core. However, in the configuration in which the brace core material is restrained by being deformed by the applied pressure, if the dimensional accuracy of each member is poor with respect to the product specifications, the restraining force on the brace core material may be reduced. For example, in the configuration disclosed in Patent Document 3, when the gap between the channel member and the external stiffener is large, the brace core material cannot be sufficiently restrained by the pressurized external stiffener. On the other hand, even when the gap between the groove member and the external stiffener is small, the flange of the groove member may be deformed inward. Thus, although the configuration disclosed in Patent Document 3 can solve the problems caused by welding, there is room for improvement in that the brace core material is accurately fixed.

  The present invention has a strength capable of withstanding repeated large earthquakes when the brace core material is accurately restrained, and can suppress warping and post-repair, which are problems of welding, and can reduce production costs. The purpose is to provide a bending restraint brace.

  The present invention provides an outer square tube, a long-plate-shaped brace core disposed inside the outer square tube and in surface contact with the inner side of the outer square tube, disposed inside the outer square tube, and the brace. An inner square tube that is in surface contact with a surface of the core opposite to the surface that contacts the outer square tube and sandwiches the brace core material in the thickness direction together with the outer square tube, and is orthogonal to the thickness direction The present invention relates to a buckling restrained brace in which a crimped portion that bends inward or outward in a state where the side surface of the outer square tube and the side surface of the inner square tube that face each other are overlapped is formed.

  The caulking portion is configured such that the brace core material in the outer square tube is disposed after applying a force pushing the both sides of the outer square tube toward the inner square tube in a direction perpendicular to the thickness direction. Preferably, it is formed by applying a force that pushes inward from the outside to the surface opposite to the surface on the opposite side.

  It is preferable that a plurality of the crimped portions are formed at intervals along the longitudinal direction of the brace core material.

  The brace core material has a reinforcing material standing on a plane portion at an end portion in the longitudinal direction, and the inner square tube has a slit formed at the end portion to avoid interference of the reinforcing material, and the caulking process The part is preferably formed on the center side of the slit of the inner square tube in the longitudinal direction of the outer square tube.

  The present invention relates to a method for manufacturing a buckling-restrained brace, wherein a bottom surface of a long plate-like brace having an inner square tube disposed on an upper surface is brought into surface contact with a bottom surface inside an outer square tube, thereby buckling-restrained brace. An assembly step for temporarily assembling the inner side tube and a side surface of the outer side square tube and a side surface of the inner side square tube overlapped with each other by applying a force pushing downward to the upper surface of the outer side square tube after the assembly step. And a pressurizing step in which a crimped portion that is bent in a straight line is formed.

  The method for manufacturing the buckling-restrained brace includes a pre-pressurizing step of applying in a horizontal direction a force for pushing the both sides of the outer square tube temporarily assembled in the assembly step toward the inner square tube side, The preliminary pressurizing step is preferably performed before the pressurizing step.

  According to the buckling-restrained brace of the present invention, the brace core material has a strength capable of withstanding repeated large earthquakes by being restrained with high accuracy, and can suppress warping and post-repair that are problems of welding and production. Cost can be reduced.

It is the perspective view which showed typically the buckling restraint brace which concerns on one Embodiment of this invention, and the mode of the inside. It is a disassembled perspective view of a buckling restraint brace. It is the XX sectional view taken on the line of FIG. It is the YY sectional view taken on the line of FIG. It is sectional drawing of the buckling restraint brace which shows a mode that a 1st pressurization process is performed. It is sectional drawing of the buckling restraint brace which shows a mode that a 2nd pressurization process is performed. It is a side view which shows the strength frame to which the buckling restraint brace of this embodiment was applied. It is a side view of the buckling restraint brace in the state where the connection plate is attached. It is a top view of the buckling restraint brace in the state where the connection plate was attached. It is a graph which shows the comparison result of the dynamic test of the crimping processed product of an Example, and a conventional product.

  Hereinafter, a preferred embodiment of a buckling restrained brace manufactured by the manufacturing method of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view schematically showing a buckling restrained brace 1 according to an embodiment of the present invention and an internal state thereof. FIG. 2 is an exploded perspective view of the buckling restrained brace 1. Each configuration shown in FIG. 2 is in a state before a caulking process described later is performed.

  As shown in FIGS. 1 and 2, the buckling restrained brace 1 of this embodiment includes a brace core material 2, an inner square tube 3, and an outer square tube 4. In the buckling restraint brace 1 of the present embodiment, the inner square tube 3 and the outer square tube 4 are fixed in a state of restraining the brace core material 2 by a crimping portion 8 formed by caulking.

  First, each structure of the buckling restrained brace 1 will be described. The brace core material 2 is formed in a long plate shape with a metal such as a steel plate. The brace core material 2 is formed with connecting portions 7 connected to structural materials such as columns and beams at both ends thereof.

  At both ends of the brace core material 2 of the present embodiment, reinforcing members 6 formed in an elongated plate shape are arranged upright. The reinforcing material 6 is joined to an intermediate portion in the width direction of the brace core material 2 so that the longitudinal direction thereof coincides with the longitudinal direction of the brace core material 2.

  The inner square tube 3 is a long rectangular tube formed of metal and functions as a restraining member for the brace core material 2. The inner square tube 3 of the present embodiment has slits 5 formed at both ends thereof. The slit 5 is for preventing interference with the reinforcing material 6 of the brace core material 2. Thereby, when the inner square tube 3 is overlapped with the brace core material 2, the reinforcing material 6 enters between the slits 5, and interference between the inner square tube 3 and the reinforcing material 6 of the brace core material 2 can be avoided. The size of the gap of the slit 5 is set so that a gap is generated between the slit 5 and the reinforcing material 6.

  The outer square tube 4 is a long rectangular tube formed of metal and functions as a restraining member for the brace core member 2 together with the inner square tube 3. The outer square tube 4 is set so that the inner diameter thereof is larger than the outer shape of the brace core material 2 and the inner square tube 3, and the brace core material 2 and the inner square tube 3 can be accommodated inside thereof. Yes. That is, the outer square tube 4 has an inner diameter in the width direction larger than the width of the brace core material 2 and the inner square tube 3, and an inner diameter in the height direction is a height direction in which the brace core material 2 and the inner square tube 3 are combined. The inner diameter dimension is larger than the above dimension.

  As a result, the inner square tube 3 can be accommodated together with the brace core material 2 inside the outer square tube 4 even when the brace core material 2 is overlapped in the thickness direction of the inner square tube 3. In other words, the width of the inner square tube 3 is set to be slightly smaller than the inner diameter dimension of the outer square tube 4 in the width direction. The height of the inner square tube 3 is equal to that of the brace core 2 and the inner corner tube. It can be said that the combined height of the tubes 3 is set to be smaller than the inner diameter dimension of the outer square tube 4 in the height direction.

  Moreover, it is preferable that the dimension of the longitudinal direction of the outer side angle tube 4 and the inner side angle tube 3 is substantially the same length mutually. In the present embodiment, in consideration of the connecting portion 7 of the brace core material 2, the longitudinal dimensions of the outer square tube 4 and the inner square tube 3 are slightly shorter than the brace core material 2.

  Next, the crimping process part 8 is demonstrated. As shown in FIG. 1, a plurality of crimped portions 8 formed by crimping are formed at predetermined intervals (for example, 250 mm) in the longitudinal direction of the buckling restrained brace 1. Each of the crimping parts 8 has a predetermined length (for example, about 50 mm) in the longitudinal direction.

  Here, the part which is not crimped in the buckling restraint brace 1 is compared with the crimped part 8. FIG. 3 is a cross-sectional view taken along the line XX of FIG. 1 and shows a state where the crimping process of the buckling restrained brace 1 is not performed. FIG. 4 is a cross-sectional view taken along the line YY of FIG. 1 and shows a state of the crimped portion 8.

  As shown in FIG. 3, a gap is formed between the inner square tube 3 and the outer square tube 4 at a portion where the crimping process is not performed. On the other hand, as shown in FIG. 4, in the crimping portion 8, a bent portion 50 that bends inward in a state where a part of the side surface 41 of the outer square tube 4 and a part of the side surface 31 of the inner square tube 3 are folded together. It is formed. The upper side surface 42 of the outer square tube 4 and the upper side surface 32 of the inner square tube 3 are in contact with each other.

  By forming the bent portion 50 on the side surface 31 of the inner square tube 3 and the side surface 41 of the outer square tube 4, movement in the thickness direction and the horizontal direction of the inner square tube 3 is restricted, and the inner corner tube 4 is moved inward. The square tube 3 is joined. Furthermore, in the present embodiment, the upper side surface 42 of the outer square tube 4 and the upper side surface 32 of the inner square tube 3 are in contact with each other, and the movement in the thickness direction of the inner square tube 3 is also restricted by this vertical contact. The

  Thereby, the brace core material 2 is firmly restrained in the thickness direction by the inner corner tube 3 and the outer corner tube 4. As described above, since the plurality of crimped portions 8 are formed along the longitudinal direction, the brace core material 2 is appropriately restrained also in the longitudinal direction. In the buckling restraint brace 1 of the present embodiment, the crimped portion 8 is formed inside the portion where the slit 5 is formed from the viewpoint of securing the rigidity of the inner square tube 3.

  As described above, in the present embodiment, the brace core material 2 is constrained by fixing the pair of constraining members composed of the inner square tube 3 and the outer square tube 4 by the crimping portion 8.

  Next, the manufacturing method of the buckling restraint brace 1 of this embodiment is demonstrated. FIG. 5 is a cross-sectional view of the buckling restrained brace 1 showing how the first pressurizing step is performed. FIG. 6 is a cross-sectional view of the buckling restrained brace 1 showing a state in which the second pressurizing step is performed.

  The manufacturing method of the buckling restrained brace 1 of this embodiment includes a setting process, a caulking process, a bending correction process, and main processes.

  As shown in FIG. 2, in the setting step, the buckling-restrained brace 1 that is the object of caulking is temporarily assembled using the brace core material 2, the inner square tube 3, and the outer square tube 4. More specifically, the inner square tube 3 is arranged on the surface (the upper surface of the brace core material 2) where the reinforcing material 6 is joined in the brace core material 2. At this time, the reinforcing member 6 is positioned inside the slit 5 so that both end portions of the inner square tube 3 and the reinforcing member 6 of the brace core member 2 do not interfere with each other. Thereby, the upper surface of the brace core material 2 and the lower surface of the inner square tube 3 are in a state of facing each other.

  Next, the inner square tube 3 installed on the upper surface of the brace core 2 is inserted into the outer square tube 4. As a result, the lower surface of the brace core material 2 and the bottom surface, which is one surface inside the outer square tube 4, face each other. At this time, it is preferable that the brace core material 2 is disposed at the center of the outer square tube 4 so that the distance between the inner side surface of the outer square tube 4 and both ends of the brace core material 2 becomes equal. Moreover, it is preferable to temporarily fix the brace core material 2 and the inner square tube 3 by an appropriate method such as welding, double-sided tape, or adhesive from the viewpoint of preventing displacement and dropping during positioning and conveyance.

  In the caulking process, caulking is performed in two stages, a first pressurizing process and a second pressurizing process. In addition, as an apparatus for performing the crimping process, there is a crushing mold apparatus capable of crushing in a horizontal direction and a downward direction, and having a groove-shaped mold (not shown) in which a processing target is set. Used.

  First, the 1st pressurization process which is the prepressurization process of a 2nd pressurization process is demonstrated. As shown in FIG. 5, in the first pressurizing step, pressurization is performed from the both sides in the horizontal direction of the outer square tube 4 after the setting step to the side surface 41 (in the direction of the white arrow in FIG. 5). . As a result, each side surface 41 of the outer square tube 4 begins to bend inward, eventually reaches the side surface 31 of the inner square tube 3, and the buckling start point 9 is formed. In the first pressurizing step, the inner square tube 3 is adjusted to the center position in the left-right direction inside the outer square tube 4, and positioning is also performed.

  A 2nd pressurization process is demonstrated. The second pressurizing step is a pressurizing step corresponding to the main processing in caulking processing. As shown in FIG. 6, a pressurizing member such as a press punch is placed on the inner side (indicated by the white arrow in FIG. 6) with respect to the upper side surface 42 of the outer square tube 4 in which the buckling starting point 9 is formed. In the direction). Since the buckling start point 9 is formed in the first pressurizing step, the side surface 41 of the outer rectangular tube 4 is smoothly bent inward, and the side surface 41 of the outer rectangular tube 4 and the side surface 31 of the inner rectangular tube 3 are folded. A bent portion 50 that bends in a bent state is formed. By forming the buckling start point 9 in the first pressurizing step, the crimped portion 8 can be formed in a good shape.

  In addition, a 1st pressurization process and a 2nd pressurization process can be suitably adjusted according to required intensity | strength. For example, the pressurizing position and the number of places to press in the first pressurizing step are appropriately set according to the performance required for the buckling restraint brace 1. For example, in the first pressurizing step, the pressurization is adjusted so that the distance is 20 mm from the upper side surface 42 of the outer square tube 4 and the length in the longitudinal direction is 50 mm and the depth is about 5 mm. In the second pressurizing step, the pressurization is adjusted so that the crushing processing amount is 5 mm, and the crimping processing portion 8 is formed so that the buckling restrained brace 1 has a strength as required.

  The bending correction process is performed after the caulking process. Since the second pressurizing step is a crushing process on one side, warping may occur. In the present embodiment, the bending generated in the second pressurizing step is corrected by the three-point lash correction.

  As described above, the buckling restrained brace 1 of the present embodiment is manufactured through the setting process, the crimping process, and the bending correction process. The manufactured buckling restrained brace 1 is used for a pillar, a beam, or the like that is a structural material of a building. The example which applied the buckling restraint brace 1 manufactured in this way to the support | pillar 12 is demonstrated. FIG. 7 is a side view showing the load-bearing frame 15 to which the buckling restrained brace of this embodiment is applied. FIG. 8 is a side view of the buckling restrained brace 1 with the connection plate 10 attached. FIG. 9 is a plan view of the buckling restrained brace 1 with the connection plate 10 attached thereto.

  As shown in FIG. 7, two buckling restraint braces 1 are used for the load-bearing frame 15. The buckling restraint brace 1 has an end portion on one side fixed to a support column 12 to be attached via a connection plate 10.

  As shown in FIGS. 8 and 9, the connection plate 10 is a plate member having a substantially right triangle, and is used in pairs. One set of connection plates 10 is fixed in a state where one end of the brace core 2 is sandwiched in the width direction. By fixing the connection plate 10 to the support column 12 on one side, one end of the buckling restraint brace 1 is fixed to the support column 12. As shown in FIG. 7, one of the two buckling-restraining braces 1 has one end fixed to the upper portion of the column 12 via the connection plate 10 and the remaining one is one side. Is fixed to the lower part of the support column 12 via the connection plate 10.

  The other end portions of the two buckling-restraining braces 1 are each fixed to a receiving member (not shown) via the common connector 11. The receiving member is a member constituting a bearing wall such as the support column 12. In the example described with reference to FIGS. 7 to 9, the two buckling-restrained braces 1 constitute a part of the load-bearing frame 15 and function as load-bearing walls.

According to the buckling restrained brace 1 of the present embodiment described above, the following effects are obtained.
The buckling restrained brace 1 of the present embodiment includes an outer square tube 4, a long plate-like brace core 2 that is disposed inside the outer square tube 4 and is in surface contact with the inner side of the outer square tube 4, and an outer square tube. An inner square tube 3 that is disposed inside 4 and that is in surface contact with the surface of the brace core 2 opposite to the surface that contacts the outer square tube 4 and sandwiches the brace core 2 in the thickness direction together with the outer square tube 4. . The buckling restrained brace 1 has a caulking process in which the side face 41 of the outer square tube 4 and the side face 31 of the inner square tube 3 facing in the direction perpendicular to the thickness direction of the brace core 2 are bent inward in an overlapping state. Part 8 is formed.

  Thereby, the brace core material 2 can be restrained with high accuracy without performing the welding operation while maintaining the strength that can withstand repeated large earthquakes. Accordingly, it is possible to suppress warping and post-repair, which are problems of welding, and to reduce production costs.

  The crimping section 8 applies a force for pushing the both side surfaces 41 of the outer square tube 4 toward the inner square tube 3 in a direction (horizontal direction) perpendicular to the thickness direction of the brace core 2, and then 4 is formed by applying a force that pushes inward (downward) from the outside to the upper side surface 42 that is the surface opposite to the side on which the brace core material 2 is disposed. As a result, the buckling starting point 9 is formed and then the crushing process is performed, so that the shape of the crimped portion 8 can be stabilized and the brace core material 2 can be restrained more appropriately.

  A plurality of crimping portions 8 are formed at intervals along the longitudinal direction of the brace core material 2. Thereby, the brace core material 2 can be restrained stably over the longitudinal direction.

  The brace core material 2 has a reinforcing material 6 erected on a plane portion at the end in the longitudinal direction, and the inner square tube 3 is formed with a slit 5 to avoid interference of the reinforcing material 6 at the end. The crimping portion 8 is formed on the center side of the slit 5 of the inner square tube 3 in the longitudinal direction of the outer square tube. Thereby, since the crimping process part 8 is formed avoiding the part in which the slit 5 of the inner side square tube 3 is formed, the fall of the rigidity of the edge part of the inner side square tube 3 can be prevented.

  As mentioned above, although preferable one Embodiment of the buckling restraint brace 1 of this invention was described, this invention is not restrict | limited to the above-mentioned embodiment, It can change suitably. For example, it is good also as a structure which increases the location which performs a crimping process and suppresses the force which tries to deform | transform so that the brace core material 2 may wave out of a surface.

  The caulking process of the above embodiment can be changed as appropriate. For example, in the first pressurizing step, a crimped portion that is pushed inward from the inner side of the inner square tube 3 and bent outward can be formed. Alternatively, the first pressurizing step, which is a preliminary processing, may be omitted, and the crimped portion may be formed only by pressurizing the upper side surface 42 of the outer square tube 4 from above.

  Furthermore, the structure of the brace core material 2, the inner square tube 3, and the outer square tube 4 is not limited to the above embodiment, and can be changed as appropriate. For example, a groove may be formed in the outer square tube, and a lip groove steel may be adopted as the outer square tube or the inner square tube.

  Next, a description will be given of the results of comparison between the buckling restrained brace of the embodiment to which the present invention is applied and the buckling restrained brace of the comparative example joined by welding of conventional welding by repeated dynamic tests.

  First, the crimped processed product of an Example is demonstrated. The crimped product of the example to which the present invention is applied is the same as the buckling restrained brace 1 of the above embodiment. In the present embodiment, the brace core material having a length in the longitudinal direction of 1301 mm and the outer square tube 4 having a length in the longitudinal direction of 1125 mm was used. In the buckling restraint brace 1 of the embodiment, seven crimping portions 8 having a length in the longitudinal direction of 50 mm are formed at intervals. In the embodiment, the crimped portion 8 is formed such that the interval is set relatively wide on the center side and the interval is relatively narrow on the end side. More specifically, the distance from the crimping process part 8 arrange | positioned in the center of the buckling restraint brace 1 to the adjacent crimping process part 8 is set to 256.5 mm, respectively. On the other hand, the distance from the caulking part 8 adjacent to the central caulking part 8 to the next caulking part 8 is 128 mm. Furthermore, the distance to the adjacent caulking part 8 is also set to 128 mm.

  The buckling restrained brace of the comparative example is a conventional product that restrains the brace core material by welding. The configuration is the same as the buckling restrained brace disclosed in Patent Document 2. The buckling restrained brace of the comparative example is welded at 14 points with a predetermined interval in the longitudinal direction, and the length in the longitudinal direction at one welding point is 15 mm.

  The dynamic test is performed under the condition that the amplitude of ± 1/70 rad is repeated at 0.3 Hz with respect to the crimped processed product of the example (buckling restraint brace 1) and the comparative example (buckling restraint brace of Patent Document 2). went. For both the buckling restrained brace 1 of the example and the buckling restrained brace of the comparative example, a bearing wall was constructed in the same state as shown in FIG. 7 and set in a test apparatus. The length of the column 12 is 2600 mm, and the distance between the receiving member to which the common connector 11 is fixed and the column 12 is 900 mm. Further, on the both sides of the load-bearing frame 15, the same struts as the struts 12 are arranged one by one with a distance of 600 mm. The graph of FIG. 10 shows the comparison result of this test.

  As shown in FIG. 10, the buckling restrained brace 1 of the caulking processed product of the example can maintain the same strength as the buckling restrained brace of the comparative example joined by welding in the first and second bodies. I understand that. Note that the number of repetitions in FIG. 10 is the number of repetitions in which the buckling-restrained brace was able to maintain an effective yield strength, and is the number of times from the start of the experiment until the buckling-restraining brace breaks. Since the amplitude of 1/70 rad is equivalent to seismic intensity 7, it was shown that the buckling-restrained brace 1 of the present invention has enough strength to withstand repeated large earthquakes as in the conventional product. is there.

DESCRIPTION OF SYMBOLS 1 Buckling restraint brace 2 Brace core material 3 Inner corner tube 4 Outer corner tube 5 Slit 6 Reinforcement material 8 Caulking processing part 31 Side surface 41 Side surface

Claims (6)

An outer square tube,
A long plate-like brace core disposed inside the outer square tube and in surface contact with the inner side of the outer square tube;
An inner angle that is disposed inside the outer square tube and is in surface contact with a surface of the brace core opposite to the surface that contacts the outer square tube, and sandwiches the brace core in the thickness direction together with the outer square tube. Tube,
With
A buckling-restraining brace in which a crimped portion that bends inward or outward in a state where the side surface of the outer square tube and the side surface of the inner square tube that face in a direction perpendicular to the thickness direction overlap is formed. The caulking processing part is
After applying a force for pushing the both sides of the outer square tube toward the inner square tube in a direction perpendicular to the thickness direction, the outer square tube is opposite to the side where the brace core material is disposed. The buckling restrained brace according to claim 1, which is formed by applying a force for pushing the surface from the outside to the inside.   The buckling restrained brace according to claim 1 or 2, wherein a plurality of the crimped portions are formed at intervals along the longitudinal direction of the brace core material. The brace core material has a reinforcing material erected on the plane portion of the end portion in the longitudinal direction,
The inner square tube is formed with a slit at its end to avoid interference with the reinforcing material,
The buckling restrained brace according to any one of claims 1 to 3, wherein the crimped portion is formed in a center side of the slit of the inner square tube in a longitudinal direction of the outer square tube. A method of manufacturing a buckling-restrained brace,
An assembly step of temporarily assembling a buckling-restrained brace by bringing the bottom surface of the long plate-like brace core material having the inner square tube arranged on the upper surface into surface contact with the bottom surface inside the outer square tube;
After the assembling process, a caulking portion that is bent inward is formed by applying a force pushing downward on the upper surface of the outer square tube, with the side surface of the outer square tube and the side surface of the inner square tube overlapping. A pressing step,
Of manufacturing a buckling-restrained brace including: Including a pre-pressurizing step of applying in a horizontal direction a force to push the inner square tube side against both side surfaces of the outer square tube in a state of being temporarily assembled in the assembly step;
The method for manufacturing a buckling-restrained brace according to claim 5, wherein the preliminary pressurizing step is performed before the pressurizing step.

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