Buckling-restrained brace and its manufacturing method

Abstract

To provide a buckling restraint brace that improves the energy absorption performance of an axial force tube and is easy to manufacture in a factory, and a method for manufacturing the same. The present invention comprises an axial force pipe that bears the axial force, a stiffening pipe into which the axial force pipe is inserted so as to cover the outer periphery of the axial force pipe, a set of end plates that are joined to both ends of the axial force pipe so as to close both ends, and a set of cross plates that are joined to both ends of the axial force pipe via the end plates and serve as fixing parts to the skeleton of the building structure. e (mm) is set to a value equal to or greater than the value calculated by formula (1) below. P ey =2×(1+√2)×t e 2 ×σ ey +π×t p ×(rt p / 2)σ py ……(1) where P ey (N): yield load of the end plate, r (mm): outer radius of the axial force tube, σ ey (N / mm 2 ): yield stress of the end plate, π: pi, t p (mm): Plate thickness of the axial force tube, σ py (N / mm 2 ): the yield stress of the axial force tube.

Description

[Technical Field]

[0001] The present invention relates to a buckling restraint brace to be installed in an architectural structure, and a manufacturing method thereof. [Background technology]

[0002] Various types of buckling-restrained braces have been developed, which are earthquake-resistant or vibration-damping braces installed at an angle on the column-beam framework of an architectural structure, and which prevent buckling when a compressive axial force is applied.

[0003] A buckling-restrained brace, such as the double steel pipe brace material disclosed in Patent Document 1, has an axial force tube placed at the center of the buckling-restrained brace and a stiffening tube into which the axial force tube is inserted so as to cover the outer periphery of the axial force tube. The axial force tube receives the axial force acting on the buckling-restrained brace, and the stiffening tube restrains the buckling deformation of the axial force tube.

[0004] When a compressive force acts on the axial force pipe of a buckling-restrained brace during an earthquake, the axial force pipe undergoes buckling deformation, but the stiffening pipe, which surrounds the outer periphery of the axial force pipe, prevents buckling. This allows the strength of the brace material to be increased and the cross-section to be reduced compared to when stiffening pipes are not provided. Furthermore, when repeated loads act on the axial force pipe of a buckling-restrained brace during an earthquake, and the axial force pipe yields and becomes plastic, the rapid decrease in strength caused by plastic deformation of the axial force pipe is prevented. This allows the energy absorption effect of the plastic deformation of the axial force pipe to be exerted against repeated loads, absorbing the seismic energy acting on the building structure, enabling economical and safe seismic design.

[0005] In buckling-restrained braces, both ends of the axial force pipe are generally provided with connecting members for connecting to gusset plates or the like provided in the skeleton of the building structure. The connecting members of the double steel pipe brace material disclosed in Patent Document 1 consist of connecting pipes welded to both ends of the axial force pipe and cross plates welded to the connecting pipes, with the cross plates being the fixed parts to the skeleton of the building structure. In the double steel pipe brace material disclosed in Patent Document 1, in order to increase the strength of the joint between the cross plate and the connecting pipe, notches are formed in the cross plate, and the connecting pipes are inserted into these notches and welded to the two. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-223415 [Non-patent literature]

[0007] [Non-Patent Document 1] Architectural Institute of Japan, "Guidelines for Vibration Control Design of Steel Structures, 1st Edition," Architectural Institute of Japan, November 2014, pp. 32-34 Summary of the Invention [Problem to be solved by the invention]

[0008] In the buckling restrained brace disclosed in Patent Document 1, the connecting pipe is inserted into the stiffening pipe and welded to the end of the axial force pipe inside the stiffening pipe, so the length of the axial force pipe is shorter than the stiffening pipe. Therefore, depending on the shape of the building structure's column-beam frame, it may not be possible to ensure a sufficient length for the axial force pipe. In this case, the buckling restrained brace cannot be installed in the building structure, and the building structure cannot be made into a vibration-damping structure.

[0009] Furthermore, in the buckling restraint brace disclosed in Patent Document 1, the joint between the connecting pipe and the cross plate requires a weld length equal to the length of the connecting pipe inserted into the notch in the cross plate. Therefore, the distance between the bolt hole provided in the cross plate for bolting the cross plate to the skeleton of the building structure and the end of the axial force pipe becomes larger by the weld length, resulting in a shorter length of the axial force pipe.

[0010] The axial force pipe of a buckling-restrained brace absorbs energy by undergoing repeated plastic deformation due to the expansion and contraction load caused by seismic forces. As mentioned above, if the length of the axial force pipe is shortened, the amount of seismic energy absorbed by the buckling-restrained brace decreases accordingly. As a result, it becomes necessary to strengthen the columns and beams of the building structure against seismic forces, making it impossible to design economically.

[0011] The present invention has been made to solve the above-mentioned problems, and aims to provide a buckling restrained brace and a method for manufacturing the same that improves the energy absorption performance of the axial force tube by designing the shape of the joint between the axial force tube of the buckling restrained brace and the connecting members that are provided at both ends of the axial force tube and joined to the skeleton of the building structure so that the length of the axial force tube can be increased relative to the overall length of the buckling restrained brace. [Means for solving the problem]

[0012] The means for solving the above problems are as follows. [1] A buckling restraint brace having an axial force tube that bears an axial force, a stiffening tube into which the axial force tube is inserted so as to cover the outer periphery of the axial force tube, a pair of end plates joined to both ends of the axial force tube so as to close the ends, and a pair of cross plates joined to both ends of the axial force tube via the end plates and serving as fixing parts to the skeleton of an architectural structure. [2] A buckling restraint brace as described in [1], in which a notch is provided on the outer edge of the end plate, the inner surface of the axial force tube is fitted into the notch, and the axial force tube and the end plate are welded together using a groove formed by the notch of the end plate and the end face of the axial force tube. [3] A buckling restraint brace as described in [1], wherein a backing plate is provided on the side of the end plate facing the axial force tube so as to abut against the inner surface of the axial force tube, and the axial force tube and the end plate are welded together using a groove formed by the side of the end plate, the backing plate, and the end face of the axial force tube. [4] A buckling restraint brace described in any one of [1] to [3], wherein the stiffening tube is fixed to the axial force tube by a stiffening tube fixing portion provided at one location along the length of the stiffening tube. [5] A buckling restraint brace as described in [4], wherein the stiffening tube fixing portion is configured by welding the stiffening tube to the axial force tube using a welding hole provided in the stiffening tube. [6] A buckling restraint brace as described in [4], wherein the stiffening tube fixing portion is configured by welding one end of the stiffening tube to the end plate joined to one end of the axial force tube. [7] A buckling restraint brace according to any one of [1] to [3], wherein a hanging piece is provided on the outer peripheral surface of the stiffening tube. [8] A method for manufacturing a buckling restrained brace according to any one of [1] to [3], At least one of the pair of end plates is formed to have a planar shape smaller than a cross-sectional shape of an inner periphery of the stiffening tube, The axial force tube is inserted into the stiffening tube from the side where the end plate, which has a planar shape smaller than the cross-sectional shape of the inner periphery of the stiffening tube, is joined, Next, the cross plate is joined to the end plate, which has a planar shape smaller than the cross-sectional shape of the inner circumference of the stiffening tube, in a method for manufacturing a buckling restrained brace. [Effects of the Invention]

[0013] According to the buckling restrained brace and its manufacturing method of the present invention, the cross plate, which serves as the fixing portion to the skeleton of the building structure, is joined to both ends of the axial force pipe via end plates that are joined to close both ends of the axial force pipe, thereby reducing the distance between the ends of the axial force pipe and the bolt holes provided in the cross plate for bolting the cross plate to the skeleton of the building structure.

[0014] As a result, the length of the axial force pipe can be increased relative to the overall length of the buckling restrained brace. This increases the amount of seismic energy absorbed by the plastic deformation caused by the seismic force acting on the axial force pipe of the buckling restrained brace. This allows the building structure to have high vibration control properties, improving the overall economic efficiency of the building structure. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1(a) is a side view showing a buckling restrained brace according to one embodiment of the present invention, and FIG. 1(b) and FIG. 1(c) are cross-sectional views of the buckling restrained brace shown in FIG. 1(a) taken along lines IB-IB and IC-IC, respectively. [Figure 2] FIG. 2 is an enlarged view of a main part of the buckling restrained brace shown in FIG. 1(a). [Figure 3] FIG. 3 is an enlarged view of a main part of the buckling restrained brace shown in FIG. 1(a). [Figure 4] FIG. 4 is a cross-sectional view showing an example of a joining configuration between an axial force tube and an end plate of a buckling restrained brace according to one embodiment of the present invention. [Figure 5] FIG. 5 is a cross-sectional view showing another example of the joining configuration between the axial force tube and the end plate of a buckling restrained brace according to one embodiment of the present invention. [Figure 6] FIG. 6 is a cross-sectional view showing yet another example of the joining configuration between the axial force tube and the end plate of a buckling restrained brace according to one embodiment of the present invention. [Figure 7] FIG. 7 is a cross-sectional view showing yet another example of the joining configuration between the axial force tube and the end plate of a buckling restrained brace according to one embodiment of the present invention. [Figure 8] FIG. 8 is a cross-sectional view showing yet another example of the joining configuration between the axial force tube and the end plate of a buckling restrained brace according to one embodiment of the present invention. [Figure 9] 9(a) and 9(b) are a cross-sectional view and a side view, respectively, of a buckling restrained brace showing an example of a stiffening tube fixing portion of a buckling restrained brace according to one embodiment of the present invention. [Figure 10]FIG. 10 is a cross-sectional view of a buckling restrained brace showing another example of a stiffening tube fixing portion of a buckling restrained brace according to an embodiment of the present invention. [Figure 11] FIG. 11 is a side view showing an example of a hanging piece of a buckling restrained brace according to one embodiment of the present invention. [Figure 12] FIG. 12 is a perspective view showing a schematic diagram of out-of-plane deformation occurring in an end plate of a buckling restrained brace according to one embodiment of the present invention. [Figure 13] 13(a) and 13(b) are side views showing a test specimen used in a loading test to confirm the amount of out-of-plane deformation that occurs in the end plate of a buckling restrained brace according to one embodiment of the present invention. [Figure 14] FIG. 14 is a graph showing the results of a loading test to confirm the amount of out-of-plane deformation that occurs in the end plate of a buckling restrained brace according to one embodiment of the present invention. [Figure 15] FIG. 15 is a graph showing an example of the distribution of strain occurring at the end of an axial force tube of a buckling restrained brace according to one embodiment of the present invention. [Figure 16] FIG. 16 is a graph showing an example of the distribution of strain occurring at the ends of the cross plates of a buckling restrained brace according to one embodiment of the present invention. [Figure 17] FIG. 17 is a side view showing the length of the expansion / contraction range in which the axial force tube of a buckling restrained brace according to one embodiment of the present invention expands and contracts under load, causing relative displacement between it and the stiffening tube. [Figure 18] FIG. 18 is a side view showing the length of the expansion / contraction range in which the axial force tube of a buckling restrained brace according to one embodiment of the present invention expands and contracts under load, causing relative displacement between it and the stiffening tube. [Figure 19] FIG. 19 is a graph showing an example of the stress-strain relationship of an axial force tube of a buckling restrained brace according to an embodiment of the present invention. [Figure 20] FIG. 20 is a graph showing another example of the stress-strain relationship of an axial force tube of a buckling restrained brace according to an embodiment of the present invention. [Figure 21]21(a) and 21(b) are graphs showing an example of the relative displacement between the axial force tube and the stiffening tube of a buckling restrained brace according to one embodiment of the present invention. [Figure 22] FIG. 22 is a diagram showing the relationship between the outer diameter of the axial force tube and the inner diameter of the stiffening tube of a buckling restrained brace according to one embodiment of the present invention. [Figure 23] FIG. 23 is a diagram showing an example of the steps of a method for manufacturing a buckling restrained brace according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of a buckling restrained brace and a manufacturing method thereof according to the present invention will be described with reference to the drawings. Buckling Restrained Brace Fig. 1(a) shows a side view of a buckling-restrained brace 1 according to one embodiment of the present invention. Fig. 1(b) and Fig. 1(c) show cross-sectional views of the buckling-restrained brace 1 shown in Fig. 1(a) taken along line IB-IB and line IC-IC, respectively.

[0017] As shown in Figures 1(a) to 1(c), the buckling restrained brace 1 comprises an axial force tube 11, a stiffening tube 12, a set of end plates 13, and a set of cross plates 14. The axial force tube 11 is made of a cylindrical steel pipe and bears the axial force input to the buckling restrained brace 1. The stiffening tube 12 is also made of a cylindrical steel pipe, and is inserted into the stiffening tube 12 so that the stiffening tube 12 covers the outer periphery of the axial force tube 11. The end plates 13 are made of circular steel plates and are welded to both ends of the axial force tube 11 so as to close both ends. The cross plates 14 are made by combining steel plates to form a cross cross section and are welded to both ends of the axial force tube 11 via the end plates 13 to form a fixed part to the skeleton of an architectural structure (not shown). Specifically, the architectural structure has a frame-side cross plate 21 provided opposite the cross plate 14 of the buckling restrained brace 1. The cross plate 14 of the buckling restrained brace 1 and the frame-side cross plate 21 of the architectural structure are friction-joined with splice plates 22 and high-strength bolts, thereby securing the buckling restrained brace 1 to the architectural structure. The stiffening pipe 12 is fixed to the axial force pipe 11 by a stiffening pipe fixing part (described later) provided at one point along the length of the stiffening pipe 12.

[0018] 2 and 3 show enlarged views of the main parts of the buckling restrained brace 1 shown in FIG. 1(a).

[0019] 2 and 3 , end plates 13 welded to both ends of the axial force tube 11 are inserted into the stiffening tube 12 together with the axial force tube 11, and the outer diameter of the end plates 13 is equal to or smaller than the outer diameter of the axial force tube 11. A notch 13a is machined on the outer edge of the end plate 13, and the inner surface of the axial force tube 11 is fitted into this notch 13a. In this state, a groove is formed by the notch 13a of the end plate 13 and the end face of the axial force tube 11, and the axial force tube 11 and the end plate 13 are welded together using this groove. The surface of the weld metal W at the welded joint between the axial force tube 11 and the end plate 13 does not come into contact with the inner surface of the stiffening tube 12.

[0020] Of the notch 13a of the end plate 13, the portion facing the end face of the axial force tube 11 is preferably an inclined surface that forms an inclination angle θ1 with respect to the radial direction of the end plate 13. This inclined surface allows the groove of the weld joint between the axial force tube 11 and the end plate 13 to have a groove angle. Of the notch 13a of the end plate 13, the flat portion other than the inclined surface serves as a backing for the weld metal W. The overlap length L1 of the fitting portion between the flat portion of the notch 13a of the end plate 13 and the axial force tube 11 is preferably 5 to 10 mm. The length L2 of the flat portion of the notch 13a of the end plate 13 excluding the fitting portion with the axial force tube 11 becomes the root gap of the weld joint between the axial force tube 11 and the end plate 13.

[0021] As shown in Figures 2 and 3, the width of the cross plate 14 is different between the base 14a on the side joined to the end plate 13 and the tip 14b on the side joined to the cross plate 21 on the frame side of the architectural structure, with the latter being set larger.

[0022] The width of the base 14a of the cross plate 14 on the side that is joined to the end plate 13 is preferably set to be at least 20 mm smaller than the diameter of the end plate 13. This ensures a weld allowance h of at least 10 mm for box welding between the outer edge of the end plate 13 and the base 14a of the cross plate 14. The width of the base 14a of the cross plate 14 is also set to be constant, and the length L3 of the base 14a in the longitudinal direction of the buckling restrained brace 1 is set to be large enough so that the cross plate 14 does not come into contact with the stiffening tubes 12 when the axial force tubes 11 contract under compressive force.

[0023] The width of tip 14b of cross plate 14, which is joined to cross plate 21 on the side of the building structure, is constant and set to be approximately the same as the width of cross plate 21 on the side of the building structure. This makes it possible to frictionally join cross plate 14 of buckling restrained brace 1 and cross plate 21 on the side of the building structure at tip 14b of cross plate 14 using splice plate 22 and high-strength bolts.

[0024] Between the base 14a and the tip 14b of the cross plate 14, an inclined portion 14c is provided to change the width of the cross plate 14. The inclination angle θ of the side surface of the inclined portion 14c of the cross plate 14 is a is preferably 45° or less. In this way, the axial force can be smoothly transmitted between the axial force pipe 11 of the buckling restrained brace 1 and the architectural structure.

[0025] 4 to 7 show cross-sectional views of other examples of the joining configuration between the axial force tube 11 and the end plate 13 of the buckling restrained brace 1. FIG.

[0026] 4, an inclination angle θ2 is also provided on the end face of the axial force tube 11 that faces the inclined surface of the notch 13a of the end plate 13. The inclined surface of the notch 13a of the end plate 13 and the end face of the axial force tube 11 provide a groove angle in the groove of the welded joint between the axial force tube 11 and the end plate 13. In this case, it is desirable that the inclination angle θ1 of the inclined surface of the notch 13a of the end plate 13 be 10° to 20°, the inclination angle θ2 of the end face of the axial force tube 11 be 30° to 40°, and the root gap L2 of the groove of the welded joint between the axial force tube 11 and the end plate 13 be 3 to 7 mm.

[0027] 5, no inclination angle is provided on the end face of the axial force tube 11 that faces the inclined surface of the notch 13a of the end plate 13. In this case, it is desirable that the inclination angle θ1 of the inclined surface of the notch 13a of the end plate 13 is 30° to 40°, and the root gap L2 of the groove of the welded joint between the axial force tube 11 and the end plate 13 is 3 to 7 mm.

[0028] The example shown in FIG. 6 is the same as the example shown in FIG. 4 , except that a step of 1 mm or less is provided between the flat portion of the notch 13a of the end plate 13, which will form the root gap L2 of the groove of the welded joint between the axial force tube 11 and the end plate 13, and the mating portion with the axial force tube 11. Similarly, the example shown in FIG. 7 is the same as the example shown in FIG. 5 , except that a step of 1 mm or less is provided between the flat portion of the notch 13a of the end plate 13, which will form the root gap L2 of the groove of the welded joint between the axial force tube 11 and the end plate 13, and the mating portion with the axial force tube 11. By providing a step in this way on the flat portion of the notch 13a of the end plate 13, it is easy to adjust the root gap L2 of the groove of the welded joint between the axial force tube 11 and the end plate 13 to a predetermined length. Furthermore, the gap between the inner surface of the axial force tube 11 and the flat portion of the notch 13a of the end plate 13 is reduced, thereby ensuring a more reliable welded joint between the axial force tube 11 and the end plate 13. In particular, when the actual dimension of the inner diameter of the axial force tube 11 is smaller than the specified value, the gap between the inner surface of the axial force tube 11 and the flat portion of the cutout portion 13a of the end plate 13 is adjusted by the above-mentioned step, and the inner surface of the axial force tube 11 can be smoothly fitted into the cutout portion 13a of the end plate 13.

[0029] FIG. 8 shows a cross-sectional view of yet another example of the joining configuration between the axial force tube 11 and the end plate 13 of the buckling restrained brace 1.

[0030] In the example shown in Fig. 8, no notch 13a is provided in the end plate 13. A backing plate 13b is provided on the side of the end plate 13 facing the axial force tube 11 so as to abut against the inner surface of the axial force tube 11, and the axial force tube 11 is welded to the end plate 13 using a groove formed by the side of the end plate 13, the backing plate 13b, and the end face of the axial force tube 11. An inclination angle θ2 is provided on the end face of the axial force tube 11 facing the side of the end plate 13. A groove angle is provided in the groove of the welded joint between the axial force tube 11 and the end plate 13 by the side of the end plate 13 and the end face of the axial force tube 11.

[0031] The configuration shown in Figure 8 requires the provision of a separate backing plate 13b, but does not require machining to create notches 13a in end plates 13. If the yield strength of buckling-restrained brace 1 is high and the outer diameter of end plates 13 is large, the cost of machining to create notches 13a in end plates 13 will be high. However, the configuration shown in Figure 8 eliminates this machining, improving economy.

[0032] 9(a) and 9(b) show a cross-sectional view and a side view, respectively, of the area surrounding stiffening tube fixing portion 15 of buckling restrained brace 1.

[0033] 9(a) and 9(b), the stiffening pipe 12 is fixed to the axial force pipe 11 by a stiffening pipe fixing portion provided at one location in the longitudinal direction of the stiffening pipe 12. The stiffening pipe fixing portion is configured by welding the stiffening pipe 12 to the axial force pipe 11 by plug welding 15 using a weld hole 12a provided in the stiffening pipe 12.

[0034] Specifically, as shown in Figures 9(a) and 9(b), a fixing plate 11a is welded to the center in the longitudinal direction of the axial force tube 11. Furthermore, a weld hole 12a is provided in the center in the longitudinal direction of the stiffening tube 12. The diameter of this weld hole 12a is preferably 20 to 40 mm. The fixing plate 11a of the axial force tube 11 and the weld hole 12a of the stiffening tube 12 are fixed by plug welding 15 to form a stiffening tube fixing portion.

[0035] It is desirable that the stiffening pipe fixing portions be provided at two or three locations circumferentially in the center of the longitudinal direction of the axial force pipe 11. Fixing the axial force pipe 11 and the stiffening pipe 12 by plug welding 15 in this manner makes it possible to uniform the gap between the outer surface of the axial force pipe 11 and the inner surface of the stiffening pipe 12 in the circumferential direction, ensuring that the stiffening pipe 12 provides a stable stiffening effect for the axial force pipe 11. Furthermore, by fixing the positions of the axial force pipe 11 and the stiffening pipe 12, it is possible to prevent problems such as the stiffening pipe 12 shifting downward and its end coming into contact with the end face of the cross plate 14, damaging the paint, when the buckling restrained brace is installed at an angle. Furthermore, because the axial force pipe 11 and the stiffening pipe 12 are locally joined by plug welding, the gap between the outer surface of the axial force pipe 11 and the inner surface of the stiffening pipe 12 is connected at the stiffening pipe fixing portions, making it easy to remove rainwater or dust that may have entered the gap between the axial force pipe 11 and the stiffening pipe 12.

[0036] FIG. 10 shows a cross-sectional view of another example of the stiffening tube fixing portion of the buckling restraint brace 1.

[0037] In the example shown in FIG. 10, the stiffening pipe fixing portion is constructed by welding one end of the stiffening pipe 12 to an end plate 13 joined to one end of the axial force pipe 11.

[0038] Specifically, as shown in Fig. 10, a stiffening pipe weld 13c is formed by machining on the outer periphery of the end plate 13, and the inner surface of the stiffening pipe 12 is in contact with the outer periphery of this stiffening pipe weld 13c. A portion of the outer periphery of the stiffening pipe weld 13c protrudes axially outward beyond the end face of the stiffening pipe 12, and the end face of the stiffening pipe 12 and the stiffening pipe weld 13c of the end plate 13 are fixed together by a fillet weld 16. In addition, a notch 13a is formed by machining on the outer edge of the end plate 13, and the inner surface of the axial force pipe 11 is fitted into this notch 13a. In this state, a groove is formed between the notch 13a of the end plate 13 and the end face of the axial force pipe 11, and the axial force pipe 11 and the end plate 13 are welded together using this groove with weld metal W.

[0039] In this way, by fixing the axial force pipe 11 and the stiffening pipe 12 via the end plate 13 by fillet welds 16, the gap between the outer surface of the axial force pipe 11 and the inner surface of the stiffening pipe 12 can be made uniform in the circumferential direction, ensuring that the stiffening pipe 12 can provide the stiffening effect of the axial force pipe 11. Furthermore, by fixing the positions of the axial force pipe 11 and the stiffening pipe 12, when the buckling restrained brace is installed at an angle, it is possible to prevent problems such as the stiffening pipe 12 shifting downward and its end coming into contact with the end face of the cross plate 14, damaging the paint. Furthermore, when the buckling restrained brace 1 is installed at an angle in a building structure, by positioning the buckling restrained brace 1 so that the stiffening pipe fixing part 16 is on the upper side of the buckling restrained brace 1, it is possible to prevent rainwater, dust, and the like from entering the interior of the buckling restrained brace 1. In particular, when the buckling restrained brace 1 is installed outdoors and is exposed to wind and rain, configuring the stiffening pipe fixing part as shown in Figure 10 is effective in preserving the buckling restrained brace 1.

[0040] FIG. 11 shows a side view of an example in which a buckling restrained brace 1 is provided with a hanging piece 17.

[0041] As shown in Figure 11, a hanging piece 17 is provided on the outer circumferential surface of the stiffening tube 12 of the buckling restrained brace 1. The hanging piece 17 has a hole for passing a shackle or the like for hanging.

[0042] This makes it easier to suspend the buckling restrained brace 1 using a crane or similar device when installing the buckling restrained brace 1 on the framework of an architectural structure. This shortens the process and improves safety when installing the buckling restrained brace 1 on an architectural structure.

[0043] It is desirable to provide two hanging pieces 17 at equal intervals on both sides of the center in the longitudinal direction of the buckling restrained brace 1. This increases stability when the buckling restrained brace 1 is hung, further improving safety. [End plate thickness] FIG. 12 shows a schematic diagram of an end plate 13 of a buckling-restrained brace 1 according to the present invention in which out-of-plane deformation occurs.

[0044] The end plate 13 of the buckling-restrained brace 1 according to this embodiment has one side joined to the cruciform cross section of the cross plate 14, and the other side joined to the circular cross section of the axial force tube 11. Therefore, as shown in FIG. 12, when a tensile load acts on the buckling-restrained brace 1 due to an earthquake force, a local tensile force acts from the cross plate 14 on the end plate 13, causing non-uniform out-of-plane deformation. At this time, as shown by the circles in FIG. 12, bending occurs at the joint between the end plate 13 and the cross plate 14, generating large stress. The thickness of the end plate 13 must be set to prevent damage to the end plate 13.

[0045] In the buckling-restrained brace 1, the collapse mechanism of the end plate 13 consists of bending yielding at the yield line portion of the end plate 13 and axial yielding at the end of the axial force tube 11. Using the yield line theory based on this collapse mechanism, the out-of-plane yield strength evaluation formula for the end plate 13 can be derived as shown in the following equation (1).

[0046] P ey =2×(1+√2)×t e 2 ×σ ey +π×t p ×(rt p / 2)σ py ……(1) where P ey (N): Yield load of the end plate 13, r (mm): Outer radius of the axial force tube 11, σ ey (N / mm 2 ): Yield stress of the end plate 13, π: Pi, t e (mm): Plate thickness of end plate 13, t p (mm): Thickness of axial force tube 11, σ py (N / mm 2 ): Yield stress of the axial force pipe 11.

[0047] Next, we conducted a load test to confirm the amount of out-of-plane deformation occurring in the end plate 13 of the buckling restraint brace 1 of the present invention, as well as the degree of distortion occurring in the ends of the axial force tube 11 and the cross plate 14 joined to the end plate 13. This is described below.

[0048] Figures 13(a) and 13(b) show side views of the specimen used in this loading test.

[0049] As shown in Figures 13(a) and 13(b), the test specimen used in this loading test was configured to include the end plate 13 of the buckling restraint brace 1 and the joint portion between the axial force tube 11 and cross plate 14 joined to both sides of the end plate 13.

[0050] In the specimen used in this loading test, the material of the end plate 13 is SN490B specified in the Japanese Industrial Standard JIS G3136 (rolled steel for building structures), and the plate thickness of the end plate 13 is t e The material of the axial force tube 11 is STK400 as specified in the Japanese Industrial Standard JIS G3444 (general structural carbon steel tube), the outer diameter Φ of the axial force tube 11 is 216.3 mm, and the plate thickness t p The material of the cross plate 14 was SN490B, the width of the cross plate 14 was 210 mm x 210 mm, and the plate thickness of the cross plate 14 was 16 mm.

[0051] A loading test was then conducted under the condition that a tensile load was applied to the above test specimen and this tensile force was gradually increased, and the amount of out-of-plane deformation (mm) occurring in the end plate 13 of the test specimen, as well as the degree of strain (%) occurring in the end of the axial force tube 11 and the end of the cross plate 14 joined to the end plate 13 were confirmed. In addition, a numerical analysis was conducted using the finite element method on an analytical model simulating the above test specimen under the same loading conditions.

[0052] Figure 14 shows the relationship between the tensile load F (kN) and the out-of-plane deformation (mm) of the end plate 13 of the test specimen, obtained by the above-mentioned loading test and numerical analysis. In Figure 14, the thick solid line indicates the experimental value, the thin solid line indicates the analytical value, the thick dashed line is a bilinear approximation of the curve of the experimental value, and the thin dashed line is a bilinear approximation of the curve of the analytical value. The yield load P of the end plate 13 yis the value of the tensile load F (kN) at the intersection of the initial gradient and the secondary gradient for each of the bilinear approximation lines (thick dashed line and thin dashed line) of the curve of the experimental value or the analytical value. The ● and ◯ marks in Figure 14 indicate the points on the curve of the experimental value (thick solid line) or the curve of the analytical value (thin solid line) where the tensile load F (kN) is P y , 2 / 3P y , and 1 / 3P y The points where

[0053] As shown in FIG. 14, the initial stiffness of the end plate 13 shows a good correspondence between the experimental value and the analytical value. However, the yield load P y The analytical value is about 14% smaller than the experimental value.

[0054] Figure 15 shows the relationship between the tensile load F (kN) and P obtained from the above loading test and numerical analysis. y , 2 / 3P y , 1 / 3P y 15 shows the distribution of strain (%) that occurs at the end of the axial force tube 11 of the test specimen when the axial force tube 11 is axially loaded. The horizontal axis of Fig. 15 shows the 0° and 90° positions, which are the joints between the end plate 13 and the cross plate 14, for one-quarter of the cross section of the axial force tube 11, as well as each position in between.

[0055] As shown in Figure 15, when the tensile load F (kN) is P y When the tensile load F (kN) is 2 / 3P, a large strain occurs in the axial force tube 11 near the 0° and 90° angles where the end plate 13 and the cross plate 14 join, and the end plate 13 deforms out of plane, causing the axial force tube 11 to yield. y and 1 / 3P y It can be seen that, at this time, the strain of the axial force tube 11 is small, and the end plate 13 exerts sufficient rigidity to disperse the stress generated in the axial force tube 11.

[0056] Figure 16 shows the relationship between the tensile load F (kN) and P obtained from the above loading test and numerical analysis. y , 2 / 3P y , 1 / 3P y16 shows the distribution of strain (%) that occurs at the end of the cross plate 14 of the test specimen when the cross plate 14 is axially stretched. Figure 16 shows the distribution of strain in the axial direction of the cross plate 14 at a position 20 mm away from the surface of the end plate 13. The horizontal axis of Figure 16 represents the intersection of the cross plate 14 as 0, and the tip of the cross plate 14 in the width direction as -1 or 1.

[0057] As shown in FIG. 16, the strain generated at the end of the cross plate 14 increases toward the tip of the cross plate 14 in the width direction. y When the strain distribution is greater than the experimental value, the analytical value of the strain at the end of the cross plate 14 is greater than the experimental value. This is similar to the analytical value of the out-of-plane deformation of the end plate 13 shown in Figure 14, which indicates that the end plate 13 has already yielded more rapidly than the experimental value. Thus, the analytical value of the strain at the end of the cross plate 14 indicates that the end plate 13 has already yielded earlier than the experimental value. However, in the elastic range, the initial stiffness and strain distribution of the end plate 13 show a good correspondence between the experimental and analytical values, and the analytical value is on the safe side, so it is possible to evaluate the strength of the end plate 13 using the analytical value.

[0058] Table 1 shows a comparison of the experimental values, analytical values, and calculated values ​​according to the above formula (1) for the yield load of the end plate 13.

[0059] [Table 1]

[0060] The experimental value of the yield load of the end plate 13 is 0.95 times the calculated value using the above formula (1), and the experimental and calculated values ​​correspond well. On the other hand, the analytical value of the yield load of the end plate 13 is smaller than the experimental value, and therefore this analytical value is 0.83 times the calculated value using the above formula (1).

[0061] The buckling-restrained brace 1 should be designed so that the end plate 13 is within the elastic range when the axial force tube 11 reaches its yield strength. Therefore, the yield load P of the end plate 13 according to the yield line theory, obtained by the above equation (1), is ey The calculated value of (N) is multiplied by the discount factor 2 / 3 (= 1 / 1.5) to obtain the short-term allowable tensile strength P of the end plate 13 as shown in the following formula (2). a Then, the short-term allowable tensile strength P of the end plate 13 is calculated as shown in the following formula (3). a (N) is the yield strength P of the axial force pipe 11 py It is safe to design it so that it is larger than the yield load P (N) of the end plate 13 obtained by the above numerical analysis. y Even for this, results are obtained that are sufficiently on the safe side.

[0062] P a =P ey / 1.5 ……(2) P a ≧P py ...(3) The thickness t required for the end plate 13 e (mm), first calculate the yield strength P of the axial force pipe 11 py (N) is obtained, and the short-term allowable tensile strength P of the end plate 13 is calculated using the above formula (3). a (N) is set. Then, the yield load P of the end plate 13 is calculated by the above formula (2). ey (N) is calculated, and the thickness t of the end plate 13 is calculated using the above formula (1). e The procedure is to calculate (mm).

[0063] Table 2 shows the plate thickness t required for the end plate 13 according to the above formulas (1) to (3). e An example of calculating (mm) is shown below.

[0064] [Table 2]

[0065] In the calculation examples shown in Table 2, the material of the axial force pipe 11 was JFE-LY225S, a low yield point steel pipe for building structures manufactured by JFE Steel Corporation. The material of the end plate 13 was SN490C specified in the Japanese Industrial Standard JIS G3136 (rolled steel for building structures).

[0066] As shown in Table 2, the yield strength P of the axial force pipe 11 py The larger (N), the greater the plate thickness t required for the end plate 13. e (mm) becomes larger.

[0067] The plate thickness t of the end plate 13 shown in FIGS. 3 to 7 is calculated by the above-mentioned calculation. e By setting the distance (mm) or more, the end plate 13 can be kept within the elastic range when the axial force tube 11 reaches its yield strength. This prevents out-of-plane deformation of the end plate 13, reduces stress concentration at the joints between the end plate 13 and the axial force tube 11, and the cross plate 14, and ensures safety at the joints.

[0068] 17 and 18 are side views showing the length L (mm) of the expansion and contraction range in which the axial force tube 11 of the buckling restrained brace 1 expands and contracts under load, causing relative displacement between it and the stiffening tube 12. Fig. 17 shows an example in which the stiffening tube fixing part that fixes the stiffening tube 12 to the axial force tube 11 is provided in the center of the axial force tube 11 in the longitudinal direction, as shown in Figs. 9(a) and 9(b). Fig. 18 shows an example in which the stiffening tube fixing part that fixes the stiffening tube 12 to the axial force tube 11 is provided at one end of the axial force tube 11, as shown in Fig. 10.

[0069] When an axial load acts on the axial force tube 11, axial strain occurs in the axial force tube 11, causing it to expand and contract, whereas no axial load acts on the stiffening tube 12, and therefore no expansion or contraction occurs in the stiffening tube 12. At this time, the relative displacement between the axial force tube 11 and the stiffening tube 12 is zero at the stiffening tube fixing part. Then, at the end face of the axial force tube 11, which is a distance from the stiffening tube fixing part by the length L (mm) of the expansion and contraction range, a relative displacement δ (mm) proportional to the length L (mm) of the expansion and contraction range occurs with respect to the stiffening tube 12.

[0070] If the axial strain generated in the axial force tube 11 when the axial force tube 11 is subjected to an axial load is ε, the relative displacement δ (mm) between the end face of the axial force tube 11 and the stiffening tube 12 is expressed by the following equation (4).

[0071] δ = ε × L ……(4) Figures 19 and 20 show examples of hysteresis curves of the stress-strain relationship of the axial force tube 11, obtained as a result of a loading test in which cyclic axial loads were applied to the buckling-restrained brace 1. The horizontal axis of Figures 19 and 20 shows the strain (%) of the axial force tube 11, and the vertical axis shows the stress intensity (N / mm 2 ) is shown.

[0072] Figure 19 shows an example in which JFE-LY225S, a low-yield-point steel pipe for building structures manufactured by JFE Steel Corporation, was used for the axial force tube 11. In the example shown in Figure 19, the alternating positive and negative cyclic load applied to the axial direction of the buckling-restrained brace 1 was controlled based on the strain generated in the axial force tube 11, and a load was repeatedly applied until the strain reached ±2.0%. As a result, it was confirmed that the stress-strain relationship of the axial force tube 11 showed a stable hysteresis curve, and that the axial force tube 11 exhibited high energy absorption capacity within a strain range of up to ±2.0%.

[0073] Figure 20 shows an example in which STKN400B, specified in Japanese Industrial Standard JIS G3444 (general structural carbon steel pipe), is used for the axial force pipe 11. In the example shown in Figure 20, the alternating positive and negative cyclic load applied to the buckling-restrained brace 1 in the axial direction was controlled based on the strain generated in the axial force pipe 11, and one cycle of load was applied to achieve strains of ±0.25%, ±0.5%, ±0.75%, ±1.0%, ±1.25%, and ±1.5%. As a result, it was confirmed that the stress-strain relationship of the axial force pipe 11 showed a stable hysteresis curve, and that the axial force pipe 11 exhibited high energy absorption capacity within a strain range of up to ±1.5%.

[0074] From these results, when the buckling-restrained brace 1 is used as a vibration control member that exerts energy absorption capacity during an earthquake, the maximum strain ε of the axial force pipe 11 of the buckling-restrained brace 1 is maxIt is preferable to determine (%) according to the following formula (5) or (6), for example. 1) When using low yield point steel pipe for building structures JFE-LY225S or JFE-LY100S manufactured by JFE Steel Corporation for the axial force pipe 11 ε max =±2.0% ……(5) 2) When STKN400B or STKN490B specified in the Japanese Industrial Standard JIS G3475 (carbon steel pipes for building structures) or STK400 or STK490 specified in the Japanese Industrial Standard JIS G3444 (carbon steel pipes for general structures) is used for the axial force pipe 11 ε max =±1.5% ……(6) In addition, when the buckling-restrained brace 1 is used as an earthquake-resistant brace within the elastic range of the axial force tube 11, the maximum strain ε max (%) is preferably set to ±0.2% or less.

[0075] Then, from the above formula (4), the maximum value δ of the relative displacement between the end face of the axial force tube 11 and the stiffening tube 12 is max (mm) is calculated as shown in the following formula (7).

[0076] δ max =ε max ×L ……(7) 21(a) and 21(b) show an example of the relative displacement δ (mm) between the axial force tube 11 and the stiffening tube 12 of the buckling restrained brace 1 according to one embodiment of the present invention.

[0077] 21(a) shows the state near the joint between the end plate 13 and the axial force tube 11 and cross plate 14 joined to both sides of the end plate 13 when no axial load is acting on the axial force tube 11. At this time, the relationship of the following equation (8) holds.

[0078] c=a+b=h / tanθ a +b ……(8) Here, h (mm): welding margin between end plate 13 and cross plate 14, a (mm): horizontal length of the diagonal end of cross plate 14 relative to welding margin h (mm) between end plate 13 and cross plate 14, b (mm): base length of cross plate 14, θ a (°): The inclination angle of the end face of the cross plate 14.

[0079] 21(b) shows a state in which an axial compressive load acts on the axial force tube 11, causing the axial force tube 11 to shrink and the position of the outer side surface of the end plate 13 to be displaced toward the inside of the stiffening tube 12. The maximum value δ of the relative displacement δ (mm) between the axial force tube 11 and the stiffening tube 12 at this time is max (mm) is as shown in the above formula (7). The maximum value δ of this relative displacement δ (mm) is max If (mm) is set within a range that satisfies the following formula (9), it is possible to prevent the stiffening tube 12 and the cross plate 14 from coming into contact with each other and being damaged.

[0080] c>δ max ……(9) The size of the welding allowance h (mm) between the end plate 13 and the cross plate 14 is preferably set to satisfy the relationship of the following formula (10). In this way, a sufficient welding cross section between the end plate 13 and the cross plate 14 can be secured, and the joining strength between the end plate 13 and the cross plate 14 can be ensured.

[0081] h≧10(mm) ……(10) As described above, the inclined portion 14c for changing the width of the cross plate 14 is provided between the base portion 14a and the tip portion 14b of the cross plate 14. The inclination angle θ of the side surface of the cross plate 14 at the inclined portion 14c is aIt is preferable to set the angle (°) so as to satisfy the relationship of the following equation (11). In this way, the axial force of the axial force pipe 11 is evenly distributed to the cross plate 14, the variation in shear force acting on the high-strength bolts joining the cross plate 14 to the cross plate 21 on the frame side of the building structure is suppressed, and the joining force of the high-strength bolt friction joint is ensured. As a result, the area of ​​the cross plate 14 can be reduced as much as possible, reducing the weight of the component and preventing interference between the cross plate 14 and other components.

[0082] θ a ≦45(°) ……(11) Table 3 shows an example of the design of the cross plate 14 of the buckling-restrained brace 1 based on the above equations. Equations (5) to (9) above prevent damage due to contact between the stiffening tube 12 and the cross plate 14, and enable the buckling-restrained brace 1 to exhibit stable energy absorption capabilities during earthquakes, resulting in a safe and economical architectural structure with high vibration control performance.

[0083] [Table 3]

[0084] FIG. 22 shows the relationship between the outer diameter D1 (mm) of the axial force tube 11 and the inner diameter D2 (mm) of the stiffening tube 12 of the buckling restrained brace 1 according to one embodiment of the present invention.

[0085] If the difference between the outer diameter D1 (mm) of the axial force tube 11 and the inner diameter D2 (mm) of the stiffening tube 12 is too small, the excess weld between the axial force tube 11 and the end plate 13 will interfere with the inner surface of the stiffening tube 12, hindering the smooth expansion and contraction of the axial force tube 11.

[0086] To prevent such problems, it is preferable to set the outer diameter D1 (mm) of the axial force tube 11 and the inner diameter D2 (mm) of the stiffening tube 12 so as to satisfy the relationship of the following formula (12).

[0087] D2-D1≧6(mm) ……(12) Furthermore, if the difference between the outer diameter D1 of the axial force tube 11 and the inner diameter D2 of the stiffening tube 12 is too large, the stiffening tube 12 will not be able to fully restrain the deformation of the axial force tube 11 when an axial load acts on the axial force tube 11. As a result, buckling of the axial force tube 11 will become more pronounced due to repeated axial loads during an earthquake, reducing the resistance to the axial load and preventing the buckling-restrained brace 1 from fully exhibiting its energy absorption capacity.

[0088] Therefore, in order to fully utilize the energy absorption capacity of the buckling restraint brace 1, it is preferable to set the outer diameter D1 (mm) of the axial force tube 11 and the inner diameter D2 (mm) of the stiffening tube 12 so as to satisfy the relationship in equation (13) below.

[0089] D2-D1≦25(mm) ……(13) Combining the above formulas (12) and (13), it is preferable that the outer diameter D1 (mm) of the axial force tube 11 and the inner diameter D2 (mm) of the stiffening tube 12 are set so as to satisfy the relationship of the following formula (14).

[0090] 6(mm)≦D2-D1≦25(mm)……(14) The above formulas (13) and (14) apply to the dimensions of the buckling restrained brace 1 that are generally used, specifically, when the lengths of the axial force pipe 11 and stiffening pipe 12 are 4000 to 14000 mm. If the lengths of the axial force pipe 11 and stiffening pipe 12 are longer than this, it is desirable to set the upper limit of (D2 - D1) in the above formulas (13) and (14) to less than 25 mm in order to fully utilize the energy absorption capacity of the buckling restrained brace 1.

[0091] Furthermore, in order to prevent the stiffening tube 12 from bending and buckling, it is preferable to design the stiffening tube 12 to satisfy the following formula (15), taking into consideration the gap e (mm) between the axial force tube 11 and the stiffening tube 12 and the buckling length l (mm) of the axial force tube 11.

[0092]

number

[0093] However, in the above equation (15),

[0094]

number

[0095]

number

[0096] and P R (N): design axial force of the stiffening pipe 12, b M b1 (N·mm): Short-term allowable bending strength of stiffening tube 12, E (N / mm 2 ): Young's modulus of stiffening tube 12, I b (mm 4 ): moment of inertia of stiffening tube 12, l (mm): buckling length of axial force tube 11, e (mm): gap between axial force tube 11 and stiffening tube 12, ν0 (mm): initial deflection of stiffening tube (=l / 1000).

[0097] The above formula (15) is a calculation formula derived based on the design method described in Non-Patent Document 1.

[0098] Table 4 shows an example of the design of the stiffening pipe 12 based on the above formulas. Using formulas (15) to (17) above, the gap e (mm) between the axial force pipe 11 and the stiffening pipe 12 can be appropriately set according to the length l (mm) of the axial force pipe 11, allowing the buckling restrained brace 1 to exhibit stable energy absorption capacity during an earthquake, resulting in a safe and economical building structure with high vibration control performance.

[0099] [Table 4]

[0100] [Manufacturing method for buckling restrained braces] FIG. 23 shows an example of the steps of a method for manufacturing a buckling restrained brace 1 according to one embodiment of the present invention.

[0101] The manufacturing method for a buckling restrained brace of this embodiment is a method for manufacturing the above-mentioned buckling restrained brace 1. In the buckling restrained brace 1 manufactured by this manufacturing method, at least one of a pair of end plates 13 is formed to have a planar shape that is smaller than the cross-sectional shape of the inner periphery of the stiffening tube 12.

[0102] As shown in FIG. 23 , in the manufacturing method of the buckling restrained brace of this embodiment, first, in step S1, end plates 13 are welded to both ends of the axial force tube 11. Next, in step S2, the outer surface of the axial force tube 11 is painted. Next, in step S3, the inner surface of the stiffening tube 12 is painted. Next, in step S4, the axial force tube 11 is inserted into the stiffening tube 12 from the side where the end plate 13, which has a planar shape smaller than the cross-sectional shape of the inner circumference of the stiffening tube 12, is joined. Next, in step S5, the stiffening tube 12 is fixed to the axial force tube 11 with the stiffening tube fixing part. Next, in step S6, cross plates 14 are welded to the end plates 13 on both sides of the axial force tube 11. Next, in step S7, the outer surface of the stiffening tube 12 and the cross plate 14 are painted.

[0103] In the above-mentioned step S6, the cross plate 14 is welded to the end plates 13 on both sides of the axial force tube 11 at the same time. Alternatively, in step S6, only one of the end plates 13 on both sides of the axial force tube 11 may be welded. In this case, in step S6, one of the pair of end plates 13 that is formed to have a planar shape smaller than the cross-sectional shape of the inner circumference of the stiffening tube 12 is selected and joined to the cross plate 14. Then, joining of the other end plate 13 of the pair of end plates 13 to the cross plate 14 can be performed at any stage before the above-mentioned step S5.

[0104] In this manner, the manufacturing method for the buckling restrained brace of this embodiment is completed. [Explanation of symbols]

[0105] 1. Buckling-restrained brace 11 Axial force tube 11a Fixed plate 12 Stiffening tube 12a Welding hole 13 End plate 13a Notch 13b Backing plate 13c Stiffening pipe weld 14 Cross Plate 14a base 14b Tip 14c Slope 15 Plug welding (stiffening pipe fixing part) 16 Fillet weld (stiffening pipe fixing part) 17 Hanging piece W weld metal 21 Frame side cross plate 22 Connection plate

Claims

1. an axial force pipe that bears an axial force; a stiffening tube into which the axial force tube is inserted so as to cover an outer periphery of the axial force tube; a pair of end plates joined to both end portions of the axial force tube so as to close the both end portions; a pair of cross plates joined to both ends of the axial force pipe via the end plates and serving as fixing parts to the skeleton of the architectural structure; a notch is provided on an outer edge portion of the end plate, and when the axial force tube and the end plate are welded together using a groove formed by the notch and the end face of the axial force tube, the inner surface of the axial force tube is overlapped and fitted onto the notch in a state where the notch serves as a backing for the groove, In this state, the axial force tube and the end plate are welded together, A buckling restraint brace, wherein a step is provided between a portion of the notch that becomes a root gap of the groove and a fitting portion with the axial force pipe.

2. 2. The buckling restraint brace according to claim 1, wherein the overlap length of the fitting portion between the end plate and the axial force tube is 5 to 10 mm.

3. 3. The buckling restraint brace according to claim 1, wherein the stiffening tube is fixed to the axial force tube by a stiffening tube fixing portion provided at one location in the longitudinal direction of the stiffening tube.

4. 4. The buckling restraint brace according to claim 3, wherein the stiffening tube fixing portion is configured by welding the stiffening tube to the axial force tube using a weld hole provided in the stiffening tube.

5. 4. The buckling restraint brace according to claim 3, wherein the stiffening tube fixing portion is configured by welding one end of the stiffening tube to the end plate joined to one end of the axial force tube.

6. 3. The buckling restraint brace according to claim 1, wherein a hanging piece is provided on the outer peripheral surface of the stiffening tube.

7. A method for manufacturing a buckling restrained brace according to claim 1 or 2, comprising: At least one of the pair of end plates is formed to have a planar shape smaller than a cross-sectional shape of an inner periphery of the stiffening tube, The axial force tube is inserted into the stiffening tube from the side where the end plate, which has a planar shape smaller than the cross-sectional shape of the inner periphery of the stiffening tube, is joined, Next, the cross plate is joined to the end plate, which has a planar shape smaller than the cross-sectional shape of the inner circumference of the stiffening tube, in a method for manufacturing a buckling restrained brace.

8. A method for manufacturing a buckling restrained brace according to claim 1 or 2, comprising: When the axial force tube and the end plate are welded together using a groove formed by the notch and the end face of the axial force tube, the inner surface of the axial force tube is overlapped and fitted onto the notch in a state where the notch serves as a backing for the groove, The axial force tube and the end plate are welded together in the above state, in accordance with a method for manufacturing a buckling restrained brace.

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