Buckling restrained brace and method of manufacturing same

Abstract

The present invention provides a buckling restraint brace and its manufacturing method that improves the energy absorption performance of the axial force tube by devising a shape of the joint between the axial force tube of the buckling restraint brace and the joining members that are provided at both ends of the axial force tube and joined to the framework of the building structure, and that is easy to manufacture in a factory. [Solution] A buckling restraint brace having an axial force tube that bears axial force, a stiffening tube into which the axial force tube is inserted so as to cover the outer circumference of the axial force tube, a set of end plates joined to both ends of the axial force tube so as to close said ends, and a set of cross plates joined to both ends of the axial force tube via the end plates and serve as fixing parts to the main body of an architectural structure.

Description

Technical Field

[0001] The present invention relates to a buckling-restrained brace installed in a building structure and a method for manufacturing the same.

Background Art

[0002] There have been variously developed seismic or vibration control brace members that are installed obliquely in a framework composed of columns and beams of a building structure and that prevent buckling when a compressive axial force acts.

[0003] The buckling-restrained brace has, for example, an axial force tube disposed at the center of the buckling-restrained brace and a supplementary stiffening tube into which the axial force tube is inserted internally so as to cover the outer periphery of the axial force tube, like the double steel pipe type brace member disclosed in Patent Document 1. The axial force tube receives the axial force acting on the buckling-restrained brace, and the supplementary stiffening tube restrains the buckling deformation of the axial force tube.

[0004] When a compressive force acts on the axial force tube of the buckling-restrained brace during an earthquake, buckling deformation occurs in the axial force tube, but buckling is suppressed by the supplementary stiffening tube disposed so as to surround the outer periphery of the axial force tube. As a result, compared with the case where the supplementary stiffening tube is not provided, the strength of the brace member can be increased and the cross section can be reduced. Further, when a repeated load acts on the axial force tube of the buckling-restrained brace during an earthquake and the axial force tube yields and plasticizes, a rapid strength reduction due to plastic deformation of the axial force tube is suppressed. Thereby, an energy absorption effect due to plastic deformation of the axial force tube is exhibited with respect to the repeated load, and seismic energy acting on the building structure can be absorbed, enabling an economical and highly safe seismic design.

[0005] In a buckling restraint brace, it is common to provide joint members at both ends of the axial force pipe for joining to gusset plates or the like provided on the frame of the building structure. The joint member of the double steel pipe type brace material disclosed in Patent Document 1 is composed of joint pipes welded to both ends of the axial force pipe and a cross plate welded to the joint pipes, and the cross plate serves as a fixing portion to the frame of the building structure. In the double steel pipe type brace material disclosed in Patent Document 1, in order to increase the load-bearing capacity of the joint portion between the cross plate and the joint pipe, a notch is formed in the cross plate, and the joint pipe is inserted into this notch, and the two are welded together.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Non-Patent Documents

[0007]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] Here, in the buckling restraint brace disclosed in Patent Document 1, since the joint pipe is inserted into the supplementary stiffening pipe and welded to the end of the axial force pipe inside the supplementary stiffening pipe, the length of the axial force pipe is shorter than that of the supplementary stiffening pipe. Therefore, depending on the shape of the frame composed of columns and beams of the building structure, it may not be possible to ensure a sufficient length of the axial force pipe. In this case, the buckling restraint brace cannot be installed in the building structure, and the building structure cannot be made into a vibration control structure.

[0009] In the buckling restraint brace disclosed in Patent Document 1, at the joint between the connecting pipe and the cross plate, the welding length is required only for the length of the portion of the connecting pipe inserted into the notch of the cross plate. Therefore, the distance between the bolt hole provided in the cross plate for bolt-joining the cross plate to the frame of the building structure and the end of the axial force pipe increases by the amount of the welding length, and as a result, the length of the axial force pipe becomes shorter.

[0010] The axial force pipe of the buckling restraint brace absorbs energy when the expansion and contraction load due to seismic force acts and repeated plastic deformation occurs. As described above, when the length of the axial force pipe becomes shorter, the amount of seismic energy absorbed by the buckling restraint brace decreases accordingly. As a result, it becomes necessary to reinforce the columns and beams of the building structure against seismic force, and an economical design cannot be achieved.

[0011] The present invention has been made to solve the above problems, and by making the shape of the joint between the axial force pipe of the buckling restraint brace and the joint members provided at both ends of the axial force pipe and joined to the frame of the building structure such that the length of the axial force pipe with respect to the total length of the buckling restraint brace can be increased, the energy absorption performance of the axial force pipe is improved, and an object is to provide a buckling restraint brace that is easy to manufacture in a factory and a manufacturing method thereof.

Means for Solving the Problems

[0012] The means for solving the above problems are as follows. [1] A buckling restraint brace having an axial force pipe that bears an axial force, a supplementary rigid pipe into which the axial force pipe is inserted inside so as to cover the outer periphery of the axial force pipe, a set of end plates joined to both ends of the axial force pipe so as to close both ends thereof, and a set of cross plates joined to both ends of the axial force pipe via the end plates and serving as fixing portions to the frame of the building structure. [2] The buckling restraint brace according to [1], wherein a notch is provided at the outer edge of the end plate, the inner surface of the axial force pipe is fitted into the notch, and the axial force pipe and the end plate are welded and joined using a groove formed by the notch of the end plate and the end face of the axial force pipe. [3] A backing plate is provided on the side surface of the end plate on the axial force pipe side in a state of abutting against the inner surface of the axial force pipe, and the axial force pipe and the end plate are welded and joined using a groove formed by the side surface of the end plate, the backing plate, and the end surface of the axial force pipe. The buckling restraint brace according to [1]. [4] The stiffening pipe is fixed to the axial force pipe by a stiffening pipe fixing portion provided at one location in the length direction of the stiffening pipe. The buckling restraint brace according to any one of [1] to [3]. [5] The stiffening pipe fixing portion is configured by welding and joining the stiffening pipe to the axial force pipe using a welding hole provided in the stiffening pipe. The buckling restraint brace according to [4]. [6] The stiffening pipe fixing portion is configured by welding and joining one end of the stiffening pipe to the end plate joined to one end of the axial force pipe. The buckling restraint brace according to [4]. [7] A suspension piece is provided on the outer peripheral surface of the stiffening pipe. The buckling restraint brace according to any one of [1] to [3]. [8] A method for manufacturing the buckling restraint brace according to any one of [1] to [3], At least one of a set of the end plates is formed to have a planar shape smaller than the cross-sectional shape of the inner periphery of the stiffening pipe, The axial force pipe is inserted into the inside of the stiffening pipe from the side where the end plate having a planar shape smaller than the cross-sectional shape of the inner periphery of the stiffening pipe is joined, Next, the cross plate is joined to the end plate having a planar shape smaller than the cross-sectional shape of the inner periphery of the stiffening pipe. A method for manufacturing a buckling restraint brace. [Advantages of the Invention]

[0013] According to the buckling restraint brace and the manufacturing method thereof of the present invention, the cross plate serving as a fixing portion to the building structure body is joined to both ends of the axial force pipe via the end plate joined so as to close both ends of the axial force pipe. Therefore, the distance between the bolt holes provided in the cross plate for bolt-joining the cross plate to the building structure body and the end of the axial force pipe can be reduced.

[0014] As a result, the length of the axial force tube with respect to the total length of the buckling restraint brace can be increased. Thereby, the amount of seismic energy absorbed due to the seismic force acting on the axial force tube of the buckling restraint brace and causing plastic deformation in the axial force tube increases. For this reason, the building structure can be made into a structure with high vibration damping performance, and the economy of the entire building structure can be improved.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Figure 21

Figure 22

Figure 23

DETAILED DESCRIPTION OF THE INVENTION

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

[0017] As shown in FIGS. 1(a) to 1(c), the buckling-restrained brace 1 has 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 composed of a cylindrical steel pipe and bears the axial force input to the buckling-restrained brace 1. The stiffening tube 12 is also composed of a cylindrical steel pipe, and the axial force tube 11 is inserted into the stiffening tube 12 so that the stiffening tube 12 is arranged to cover the outer periphery of the axial force tube 11. The end plate 13 is composed of a disc-shaped steel plate and is welded to both ends of the axial force tube 11 so as to close both ends of the axial force tube 11. The cross plate 14 is formed by combining steel plates into a cross section and is welded to both ends of the axial force tube 11 via the end plate 13 to serve as a fixing part to the frame of a building structure (not shown). Specifically, on the building structure, a frame-side cross plate 21 is provided at a position facing the cross plate 14 of the buckling-restrained brace 1. Then, the cross plate 14 of the buckling-restrained brace 1 and the frame-side cross plate 21 of the building structure are frictionally joined by an attachment plate 22 and high-strength bolts, whereby the buckling-restrained brace 1 is fixed to the building structure. The stiffening tube 12 is fixed to the axial force tube 11 by a stiffening tube fixing part (described later) provided at one location in the length direction of the stiffening tube 12.

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

[0019] As shown in FIGS. 2 and 3, the 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 plate 13 is set to be equal to or less than the outer diameter of the axial force tube 11. A notch 13a is provided at the outer edge of the end plate 13 by machining, 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 using this groove, the axial force tube 11 and the end plate 13 are welded together. The surface of the weld metal W in the welding joint between the axial force tube 11 and the end plate 13 is made not to contact 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 an inclined surface that forms an inclination angle θ with respect to the radial direction of the end plate 13. 1 It is preferably an inclined surface. With this inclined surface, a groove angle can be provided at the groove of the welded joint between the axial force tube 11 and the end plate 13. Among 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 overlapping length L of the fitting portion between the flat portion of the notch 13a of the end plate 13 and the axial force tube 11 1 is desirably 5 to 10 mm. Among the flat portion of the notch 13a of the end plate 13, the length L of the portion excluding the fitting portion with the axial force tube 11 2 becomes the root gap of the groove of the welded joint between the axial force tube 11 and the end plate 13.

[0021] Also, as shown in FIGS. 2 and 3, the width of the cross plate 14 is different between the base portion 14a on the side joined to the end plate 13 and the tip portion 14b on the side joined to the structural side cross plate 21 of the building structure, and the latter is set larger.

[0022] The width of the base portion 14a of the cross plate 14 on the side joined to the end plate 13 is preferably set to be 20 mm or more smaller than the diameter of the end plate 13. By doing so, a welding margin h of 10 mm or more for circumferential welding between the outer edge portion of the end plate 13 and the base portion 14a of the cross plate 14 can be ensured. Also, the width of the base portion 14a of the cross plate 14 is constant, and the length L of the base portion 14a in the length direction of the buckling restraint brace 1 3 is set to a sufficient size so that the cross plate 14 does not contact the stiffening tube 12 when the axial force tube 11 is compressed and shrinks.

[0023] The width of the tip portion 14b of the cross plate 14 on the side joined to the structural side cross plate 21 of the building structure is constant and is set to be approximately the same as the width of the structural side cross plate 21 of the building structure. Thereby, at the tip portion 14b of the cross plate 14, it becomes possible to frictionally join the cross plate 14 of the buckling restraint brace 1 and the structural side cross plate 21 of the building structure with the attachment plate 22 and high-strength bolts.

[0024] And between the base portion 14a and the tip portion 14b of the cross plate 14, an inclined portion 14c for changing the width of the cross plate 14 is provided. The inclination angle θ of the side surface of the cross plate 14 in the inclined portion 14c a is preferably 45° or less. By doing so, the axial force can be smoothly transmitted between the axial force tube 11 of the buckling restraint brace 1 and the building structure.

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

[0026] In the example shown in Fig. 4, an inclination angle θ is also provided on the end face of the axial force tube 11 facing the inclined surface of the notch 13a of the end plate 13. 2 And an included angle is provided at the root of the weld joint between the axial force tube 11 and the end plate 13 by the inclined surface of the notch 13a of the end plate 13 and the end face of the axial force tube 11. In this case, the inclination angle θ of the inclined surface of the notch 13a of the end plate 13 1 is 10° to 20°, the inclination angle θ of the end face of the axial force tube 11 2 is 30° to 40°, and the root gap L of the weld joint between the axial force tube 11 and the end plate 13 2 is desirably 3 to 7 mm.

[0027] In the example shown in Fig. 5, no inclination angle is provided on the end face of the axial force tube 11 facing the inclined surface of the notch 13a of the end plate 13. In this case, the inclination angle θ of the inclined surface of the notch 13a of the end plate 13 1 is 30° to 40°, and the root gap L of the weld joint between the axial force tube 11 and the end plate 13 2 is desirably 3 to 7 mm.

[0028] The example shown in Fig. 6 is the example shown in Fig. 4, and among the flat portions of the notch 13a of the end plate 13, the root gap L of the weld joint between the axial force tube 11 and the end plate 13 2A step within 1 mm is provided between the portion that becomes [the relevant part] and the fitting portion with the axial force tube 11. Similarly, in the example shown in FIG. 7, in the example shown in FIG. 5, among the flat portions of the notch 13a of the end plate 13, the root gap L of the weld joint between the axial force tube 11 and the end plate 13 2 A step within 1 mm is provided between the portion that becomes [the relevant part] and the fitting portion with the axial force tube 11. Thus, by providing a step in the flat portion of the notch 13a of the end plate 13, the root gap L of the weld joint between the axial force tube 11 and the end plate 13 2 can be easily adjusted to a predetermined length. Also, 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 becomes smaller, and the weld joint between the axial force tube 11 and the end plate 13 can be made more reliable. 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 notch 13a of the end plate 13 is adjusted by the above step, and the fitting of the inner surface of the axial force tube 11 to the notch 13a of the end plate 13 can be made smooth.

[0029] FIG. 8 shows a cross-sectional view of still another example of the joint form between the axial force tube 11 and the end plate 13 of the buckling restraint brace 1.

[0030] In the example shown in FIG. 8, no notch 13a is provided in the end plate 13. And a backing plate 13b is provided on the side surface of the end plate 13 on the side of the axial force tube 11 in a state of contacting the inner surface of the axial force tube 11, and the axial force tube 11 is welded to the end plate 13 using the weld joint formed by the side surface of the end plate 13, the backing plate 13b, and the end face of the axial force tube 11. An inclination angle θ 2 is provided on the end face of the axial force tube 11 facing the side surface of the end plate 13. And the side surface of the end plate 13 and the end face of the axial force tube 11 provide a weld joint angle at the weld joint between the axial force tube 11 and the end plate 13.

[0031] In the configuration shown in FIG. 8, although it is necessary to separately provide the backing plate 13b, machining for providing the notch 13a in the end plate 13 becomes unnecessary. When the yield strength of the buckling restraining brace 1 is large and the outer diameter of the end plate 13 is large, the cost of machining for providing the notch 13a in the end plate 13 becomes high. However, by adopting the configuration shown in FIG. 8, this machining becomes unnecessary, and the economy is improved.

[0032] FIGS. 9(a) and 9(b) respectively show a cross-sectional view and a side view of the peripheral portion of the fixing portion 15 of the stiffening pipe of the buckling restraining brace 1.

[0033] In the examples shown in FIGS. 9(a) and 9(b), the stiffening pipe 12 is fixed to the axial force pipe 11 by a fixing portion of the stiffening pipe provided at one location in the length direction of the stiffening pipe 12. The fixing portion of the stiffening pipe is configured by the stiffening pipe 12 being welded and joined to the axial force pipe 11 by plug welding 15 using the welding hole 12a provided in the stiffening pipe 12.

[0034] Specifically, as shown in FIGS. 9(a) and 9(b), a fixing plate 11a is welded and joined to the center in the length direction of the axial force pipe 11. Also, a welding hole 12a is provided at the center in the length direction of the stiffening pipe 12. The diameter of this welding hole 12a is preferably 20 to 40 mm. Then, the fixing plate 11a of the axial force pipe 11 and the welding hole 12a of the stiffening pipe 12 are fixed by plug welding 15, thereby constituting the fixing portion of the stiffening pipe.

[0035] It is desirable that the supplementary rigid pipe fixing part be provided at two to three locations in the circumferential direction at the center in the length direction of the axial force pipe 11. In this way, by fixing the axial force pipe 11 and the supplementary rigid pipe 12 by plug welding 15, the gap between the outer surface of the axial force pipe 11 and the inner surface of the supplementary rigid pipe 12 can be made uniform in the circumferential direction, and the supplementary rigid effect of the axial force pipe 11 by the supplementary rigid pipe 12 can be reliably exerted. Further, by fixing the positions of the axial force pipe 11 and the supplementary rigid pipe 12, when the buckling restraint brace is installed obliquely, the supplementary rigid pipe 12 will not shift downward, and its end will not contact the end face of the cross plate 14, thus preventing problems such as damage to the painting. Furthermore, since the gap between the outer surface of the axial force pipe 11 and the inner surface of the supplementary rigid pipe 12 communicates at the supplementary rigid pipe fixing part due to local joining by plug welding, when rainwater or dust enters the gap between the axial force pipe 11 and the supplementary rigid pipe 12, it is easy to remove them.

[0036] Fig. 10 shows a cross-sectional view of another example of the supplementary rigid pipe fixing part of the buckling restraint brace 1.

[0037] In the example shown in Fig. 10, the supplementary rigid pipe fixing part is constituted by welding and joining one end of the supplementary rigid 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 supplementary rigid pipe welding part 13c is provided on the outer periphery of the end plate 13 by machining, and the inner surface of the supplementary rigid pipe 12 is in contact with the outer periphery of the supplementary rigid pipe welding part 13c. A part of the outer periphery of the supplementary rigid pipe welding part 13c protrudes axially outside the supplementary rigid pipe 12 from the end face of the supplementary rigid pipe 12, and the space between the end face of the supplementary rigid pipe 12 and the supplementary rigid pipe welding part 13c of the end plate 13 is fixed by fillet welding 16. Further, a notch 13a is provided on the outer edge part of the end plate 13 by machining, and the inner surface of the axial force pipe 11 is fitted into the notch 13a. In this state, a groove is formed from the notch 13a of the end plate 13 and the end face of the axial force pipe 11, and using this groove, the axial force pipe 11 and the end plate 13 are welded and joined by a welding metal W.

[0039] In this way, by fixing the axial force pipe 11 and the supplementary stiffening pipe 12 through the end plate 13 by means of fillet welding 16, the gap between the outer surface of the axial force pipe 11 and the inner surface of the supplementary stiffening pipe 12 can be made uniform in the circumferential direction, and the supplementary stiffening effect of the supplementary stiffening pipe 12 on the axial force pipe 11 can be reliably exerted. Further, by fixing the positions of the axial force pipe 11 and the supplementary stiffening pipe 12, when the buckling restraint brace is installed obliquely, the situation where the supplementary stiffening pipe 12 is displaced downward and its end contacts the end face of the cross plate 14, damaging the painting and other problems can be prevented. And when the buckling restraint brace 1 is installed obliquely on the building structure, by arranging the buckling restraint brace 1 so that the supplementary stiffening pipe fixing part 16 is on the upper side of the buckling restraint brace 1, the intrusion of rainwater, dust, etc. into the inside of the buckling restraint brace 1 can be prevented. In particular, when the buckling restraint brace 1 is installed outdoors and affected by wind and rain, by configuring the supplementary stiffening pipe fixing part as shown in FIG. 10, it is effective for the maintenance of the buckling restraint brace 1.

[0040] FIG. 11 shows a side view of an example in which a suspension piece 17 is provided on the buckling restraint brace 1.

[0041] As shown in FIG. 11, a suspension piece 17 is provided on the outer peripheral surface of the supplementary stiffening pipe 12 of the buckling restraint brace 1. The suspension piece 17 has a hole for passing a shackle or the like for hanging.

[0042] In this way, when installing the buckling restraint brace 1 on the structure of the building, the hoisting operation of the buckling restraint brace 1 by a crane or the like becomes easy. Thereby, the shortening of the process and the improvement of safety when installing the buckling restraint brace 1 on the building structure can be achieved.

[0043] It is desirable that two suspension pieces 17 are provided at equal intervals on both sides from the center in the length direction of the buckling restraint brace 1. In this way, the stability during the hoisting of the buckling restraint brace 1 is enhanced, and further improvement in safety can be achieved. [Thickness of the end plate] FIG. 12 schematically shows a situation where out-of-plane deformation has occurred in the end plate 13 of the buckling restraint brace 1 according to the present invention.

[0044] One side surface of the end plate 13 of the buckling restraint brace 1 according to this embodiment is joined to the cross-shaped cross section of the cross plate 14, and the other side surface is 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 restraint brace 1 due to seismic force, a local tensile force acts on the end plate 13 from the cross plate 14, resulting in non-uniform out-of-plane deformation. At this time, as indicated by the circle in FIG. 12, bending occurs at the joint of the end plate 13 with the cross plate 14, generating a large stress. It is necessary to set the plate thickness of the end plate 13 so that damage does not occur to the end plate 13 at this time.

[0045] In the buckling restraint brace 1, the collapse mechanism of the end plate 13 is composed of bending yield in the yield line portion of the end plate 13 and axial yield at the end of the axial force tube 11. When the out-of-plane yield strength evaluation formula of the end plate 13 is derived using the yield line theory based on this collapse mechanism, it becomes as shown in the following formula (1).

[0046] P ey =2×(1+√2)×t e 2 ×σ ey +π×t p ×(r-t p / 2)σ py ……(1) Here, P ey (N): The yield load of the end plate 13, r (mm): The outer radius of the axial force tube 11, σ ey (N / mm 2 ): The yield stress of the end plate 13, π: Pi, t e (mm): The plate thickness of the end plate 13, t p (mm): The plate thickness of the axial force tube 11, σ py (N / mm 2 ): The yield stress of the axial force tube 11.

[0047] Next, in order to confirm the out-of-plane deformation amount generated in the end plate 13 of the buckling restraint brace 1 according to the present invention, as well as the strain generated at the end of the axial force tube 11 and the end of the cross plate 14 joined to the end plate 13, a loading test was conducted, and this will be described below.

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

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

[0050] In the test specimens used in the supplementary loading test, the material of the end plate 13 is SN490B specified in Japanese Industrial Standard JISG3136 (Hot-Rolled Steel Sheets for Building Structures), and the plate thickness t e of the end plate 13 is 12 mm. Also, the material of the axial force tube 11 is STK400 specified in Japanese Industrial Standard JISG3444 (Carbon Steel Tubes for General Structure), the outer diameter Φ of the axial force tube 11 is 216.3 mm, and the plate thickness t p of the axial force tube 11 is 5.8 mm. Also, the material of the cross plate 14 is SN490B, the width of the cross plate 14 is 210 mm × 210 mm, and the plate thickness of the cross plate 14 is 16 mm.

[0051] Then, a tensile load was applied to the above test specimens, and a loading test was conducted under the condition of gradually increasing this tensile force. The out-of-plane deformation amount (mm) generated in the end plate 13 of the test specimens, as well as the strain (%) generated at the ends of the axial force tube 11 and the cross plate 14 joined to the end plate 13, were confirmed. Also, numerical analysis by the finite element method was performed on the analysis model simulating the above test specimens under the same loading conditions.

[0052] Figure 14 shows the relationship between the tensile load F (kN) and the out-of-plane deformation amount (mm) generated in the end plate 13 of the test specimens obtained by the above 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 the line obtained by bilinearly approximating the curve of the experimental value, and the thin dashed line is the line obtained by bilinearly approximating the curve of the analytical value. The yield load P of the end plate 13 yFor each of the lines (thick dashed line and thin dashed line) obtained by bilinearly approximating the curve of experimental values or analytical values, the value of the tensile load F (kN) at the intersection of the initial gradient and the secondary gradient was used. The ● mark and the ○ mark in Fig. 14 are respectively the points on the curve of experimental values (thick solid line) or the curve of analytical values (thin solid line) where the tensile load F (kN) is P y , 2 / 3P y , and 1 / 3P y and these points are plotted respectively.

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

[0054] Fig. 15 shows the distributions of the strain (%) generated at the end of the axial force tube 11 of the test specimen when the tensile load F (kN) is P y , 2 / 3P y , 1 / 3P y obtained by the above loading test and numerical analysis, respectively. The horizontal axis in Fig. 15 shows the positions at 0° and 90° which are the joints between the end plate 13 and the cross plate 14, and the positions in between for a 1 / 4 part of the cross section of the axial force tube 11.

[0055] As shown in Fig. 15, when the tensile load F (kN) is P y , large strains occur in the axial force tube 11 near 0° and 90° which are the joints between the end plate 13 and the cross plate 14, and it can be seen that the end plate 13 has undergone out-of-plane deformation and yielding has occurred in the axial force tube 11. Also, when the tensile load F (kN) is 2 / 3P y and 1 / 3P y , the strains in the axial force tube 11 are small, and it can be seen that the end plate 13 exhibits sufficient stiffness to disperse the stress generated in the axial force tube 11.

[0056] Fig. 16 shows the tensile load F (kN) obtained by the above loading test and numerical analysis, where the tensile load F (kN) is P y , 2 / 3P y , 1 / 3P yIt shows the distribution of the strain (%) generated at the end of the cruciform plate 14 of the test specimen when [conditions]. Fig. 16 shows the distribution of the axial strain of the cruciform plate 14 at a position 20 mm away from the surface of the end plate 13. The horizontal axis in Fig. 16 represents the intersection of the cruciform plate 14 as 0, and the tip in the width direction of the cruciform plate 14 is represented as -1 or 1.

[0057] As shown in Fig. 16, the strain generated at the end of the cruciform plate 14 increases toward the tip in the width direction of the cruciform plate 14. When the tensile load F (kN) is P y at [conditions], the analytical value of the strain generated at the end of the cruciform plate 14 is larger than the experimental value. This is similar to the fact that the analytical value of the out-of-plane deformation amount of the end plate 13 shown in Fig. 14 indicates a state where the yielding of the end plate 13 has progressed more than the experimental value. Thus, the analytical value of the strain generated at the end of the cruciform plate 14 indicates a state where the yielding of the end plate 13 occurs earlier compared to the experimental value. However, in the elastic range, the initial stiffness and the strain distribution of the end plate 13 show good correspondence between the experimental value and the analytical value, and since the analytical value is on the safe side, it is possible to evaluate the yield strength of the end plate 13 based on the analytical value.

[0058] Table 1 shows a comparison of the experimental value, analytical value, and calculated value by the above formula (1) of 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 by the above formula (1), and the experimental value and the calculated value show good correspondence. On the other hand, since the analytical value of the yield load of the end plate 13 is smaller than the experimental value, this analytical value is 0.83 times the calculated value by the above formula (1).

[0061] It is appropriate to design the buckling restraint brace 1 so that when the axial force tube 11 reaches its yield strength, the end plate 13 remains within the elastic range. Therefore, the yield load P ey (N) of the end plate 13 according to the yield line theory obtained from the above equation (1) is multiplied by a discount factor of 2 / 3 (= 1 / 1.5) to calculate the short-term allowable tensile strength P a (N) of the end plate 13 as shown in the following equation (2). Then, as shown in the following equation (3), it is safe to design such that the short-term allowable tensile strength P a (N) of the end plate 13 is greater than the yield strength P py (N) of the axial force tube 11. By using this discount factor, results on the safe side can also be obtained for the yield load P y of the end plate 13 obtained by the above numerical analysis.

[0062] P a = P ey / 1.5 ……(2) P a ≧ P py ……(3) The calculation of the required plate thickness t e (mm) of the end plate 13 is as follows: First, the yield strength P py (N) of the axial force tube 11 is obtained, and the short-term allowable tensile strength P a (N) of the end plate 13 is set according to the above equation (3). Then, the yield load P ey (N) of the end plate 13 is calculated according to the above equation (2), and the plate thickness t e (mm) of the end plate 13 is calculated according to the above equation (1).

[0063] Table 2 shows an example of calculating the required plate thickness t e (mm) of the end plate 13 according to the above equations (1) to (3).

[0064]

Table 2

[0065] However, in the calculation example shown in Table 2, the material of the axial force tube 11 was the low yield point steel pipe for building structures JFE-LY225S by JFE Steel Corporation. Also, the material of the end plate 13 was SN490C specified in Japanese Industrial Standard JISG3136 (rolled steel for building structures).

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

[0067] By setting the plate thickness t of the end plate 13 shown in FIGS. 3 to 7 to be equal to or greater than the required plate thickness t e (mm) of the end plate 13 obtained by the above calculation, it is possible to ensure that when the axial force tube 11 reaches its yield strength, the end plate 13 remains within the elastic range. As a result, the out-of-plane deformation of the end plate 13 is suppressed, the stress concentration at the joint between the end plate 13, the axial force tube 11, and the cross plate 14 is reduced, and the safety of the joint can be ensured.

[0068] FIGS. 17 and 18 are side views showing the length L (mm) of the expansion and contraction range in which relative displacement occurs between the axial force tube 11 of the buckling restraint brace 1 and the supplementary stiffening tube 12 due to the axial force tube 11 receiving a load and expanding and contracting. FIG. 17 shows an example in which the supplementary stiffening tube fixing portion that fixes the supplementary stiffening tube 12 to the axial force tube 11 is provided at the center in the longitudinal direction of the axial force tube 11 as shown in FIGS. 9(a) and 9(b). Also, FIG. 18 shows an example in which the supplementary stiffening tube fixing portion that fixes the supplementary 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 and it expands and contracts, while no axial load acts on the supplementary stiffening tube 12, so no expansion and contraction occurs in the supplementary stiffening tube 12. At this time, at the supplementary stiffening tube fixing portion, the relative displacement between the axial force tube 11 and the supplementary stiffening tube 12 is zero. And at the end face of the axial force tube 11 at a distance of the length L (mm) of the above expansion and contraction range from the supplementary stiffening tube fixing portion, a relative displacement δ (mm) proportional to the length L (mm) of the above expansion and contraction range occurs with respect to the supplementary stiffening tube 12.

[0070] When the axial strain generated in the axial force tube 11 when the axial force tube 11 receives 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 as in the following formula (4).

[0071] δ = ε × L ……(4) Figs. 19 and 20 show examples of the stress-strain relationship history curves of the axial force tube 11 obtained as a result of conducting a loading test in which an axial positive and negative alternating repeated load is applied to the buckling restraining brace 1. The horizontal axis in Figs. 19 and 20 represents the strain degree (%) of the axial force tube 11, and the vertical axis represents the stress degree (N / mm 2 ) of the axial force tube 11.

[0072] Fig. 19 shows an example in which the low yield point steel pipe JFE-LY225S for building structures by JFE Steel Corporation is used for the axial force tube 11. In the example shown in Fig. 19, the positive and negative alternating repeated load applied in the axial direction of the buckling restraining brace 1 is controlled based on the strain degree generated in the axial force tube 11, and the loading with a strain degree of ±2.0% is repeated. As a result, the stress-strain relationship of the axial force tube 11 shows a stable history curve, and it was confirmed that the axial force tube 11 exhibits a high energy absorption capacity in the range where the strain degree is up to ±2.0%.

[0073] Fig. 20 shows an example in which STKN400B defined in Japanese Industrial Standard JISG3444 (carbon steel pipe for general structures) is used for the axial force tube 11. In the example shown in Fig. 20, the positive and negative alternating repeated load applied in the axial direction of the buckling restraining brace 1 is controlled based on the strain degree generated in the axial force tube 11, and the loading with strain degrees of ±0.25%, ±0.5%, ±0.75%, ±1.0%, ±1.25%, and ±1.5% is performed one cycle at a time. As a result, the stress-strain relationship of the axial force tube 11 shows a stable history curve, and it was confirmed that the axial force tube 11 exhibits a high energy absorption capacity in the range where the strain degree is up to ±1.5%.

[0074] From these results, when the buckling restraining brace 1 is used as a vibration damping member that exhibits energy absorption capacity during an earthquake, the maximum strain degree ε of the axial force tube 11 of the buckling restraining brace 1 max(%) is preferably determined as shown in the following formula (5) or (6), for example. 1) When using the low yield point steel pipe for building structures JFE-LY225S or JFE-LY100S by JFE Steel Corporation for the axial force pipe 11 ε max = ±2.0% ……(5) 2) When using STKN400B or STKN490B defined in Japanese Industrial Standard JISG3475 (Carbon steel pipes for building structures), or STK400 or STK490 defined in Japanese Industrial Standard JISG3444 (Carbon steel pipes for general structures) for the axial force pipe 11 ε max = ±1.5% ……(6) Also, when using the buckling restraint brace 1 as a seismic brace within the elastic range of the axial force pipe 11, the maximum strain ε of the axial force pipe 11 of the buckling restraint brace 1 max (%) is preferably set to ±0.2% or less.

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

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

[0077] Figure 21(a) shows the state near the joint of the end plate 13, the axial force pipe 11 joined to both sides thereof, and the cross plate 14 when no axial load acts on the axial force pipe 11. At this time, the relationship of the following formula (8) holds.

[0078] c = a + b = h / tanθ a + b ……(8) Here, h (mm): the weld root between the end plate 13 and the cruciform plate 14, a (mm): the horizontal length of the diagonal end of the cruciform plate 14 with respect to the weld root h (mm) between the end plate 13 and the cruciform plate 14, b (mm): the base length of the cruciform plate 14, θ a (°): is the inclination angle of the end face of the cruciform plate 14.

[0079] Figure 21(b) shows a state in which an axial compressive load acts on the axial force tube 11, the axial force tube 11 contracts, and the position of the outer side surface of the end plate 13 is displaced inside the stiffening tube 12. The maximum value δ max (mm) of the relative displacement δ (mm) between the axial force tube 11 and the stiffening tube 12 is as shown in the above formula (7). The maximum value δ max (mm) of this relative displacement δ (mm) should be within the range that satisfies the following formula (9) so as to prevent the stiffening tube 12 and the cruciform plate 14 from coming into contact and being damaged.

[0080] c > δ max ……(9) The size of the weld root h (mm) between the end plate 13 and the cruciform plate 14 is preferably set to satisfy the relationship of the following formula (10). By doing so, a sufficient weld cross-section between the end plate 13 and the cruciform plate 14 can be ensured, and the joint strength between the end plate 13 and the cruciform plate 14 can be ensured.

[0081] h ≥ 10 (mm) ……(10) Also, as described above, an inclined portion 14c for changing the width of the cruciform plate 14 is provided between the base portion 14a and the tip portion 14b of the cruciform plate 14. The inclination angle θ a(°) is preferably set to satisfy the relationship of the following formula (11). By doing so, the axial force of the axial force tube 11 is evenly distributed to the cross plate 14, and the variation in the shear force acting on the high-strength bolts joining the cross plate 14 and the structural side cross plate 21 of the building structure is suppressed, ensuring the joint force of the high-strength bolt friction joint. As a result, the area of the cross plate 14 can be reduced as much as possible to reduce the member weight and prevent interference between the cross plate 14 and other members.

[0082] θ a ≦45(°) ……(11) Table 3 shows an example of designing the cross plate 14 of the buckling restraint brace 1 based on the above formulas. By the above formulas (5) to (9), damage due to contact between the stiffening tube 12 and the cross plate 14 is prevented, and during an earthquake, the buckling restraint brace 1 exhibits stable energy absorption capacity, realizing a safe and economical building structure with high vibration control performance.

[0083]

Table 3

[0084] In FIG. 22, the outer diameter D of the axial force tube 11 of the buckling restraint brace 1 according to an embodiment of the present invention 1 (mm) and the inner diameter D of the stiffening tube 12 2 (mm) are shown.

[0085] If the difference between the outer diameter D of the axial force tube 11 1 (mm) and the inner diameter D of the stiffening tube 12 2 (mm) is too small, the excess portion of the weld between the axial force tube 11 and the end plate 13 interferes with the inner surface of the stiffening tube 12, inhibiting the smooth expansion and contraction of the axial force tube 11.

[0086] To prevent such problems, the outer diameter D of the axial force tube 11 1 (mm) and the inner diameter D of the stiffening tube 12 2 (mm) are preferably set to satisfy the relationship of the following formula (12).

[0087] D2 -D 1 ≧6 (mm) ……(12) Also, when the outer diameter D of the axial force tube 11 1 and the inner diameter D of the stiffening tube 12 2 have too large a difference, when an axial load acts on the axial force tube 11, the effect of the stiffening tube 12 restraining the deformation of the axial force tube 11 cannot be fully exerted. Then, for the repeated axial load during an earthquake, buckling of the axial force tube 11 becomes prominent, the resistance to the axial load decreases, and the buckling restraint brace 1 cannot fully exert its energy absorption capacity.

[0088] Therefore, in order to fully exert the energy absorption capacity of the buckling restraint brace 1, the outer diameter D of the axial force tube 11 1 (mm) and the inner diameter D of the stiffening tube 12 2 (mm) are preferably set to satisfy the relationship of the following formula (13).

[0089] D 2 -D 1 ≦25 (mm) ……(13) Combining the above formulas (12) and (13), the outer diameter D of the axial force tube 11 1 (mm) and the inner diameter D of the stiffening tube 12 2 (mm) are preferably set to satisfy the relationship of the following formula (14).

[0090] 6 (mm) ≦ D 2 -D 1 ≦25 (mm) ……(14) Note that the above formulas (13) and (14) are applicable when the dimensions generally used for the buckling restraint brace 1, specifically, when the lengths of the axial force tube 11 and the stiffening tube 12 are 4000 - 14000 mm. When the lengths of the axial force tube 11 and the stiffening tube 12 are larger than this, in order to fully exert the energy absorption capacity of the buckling restraint brace 1, the upper limit value of (D 2 -D 1 ) in the above formulas (13) and (14) is preferably set to be smaller than 25 mm.

[0091] Also, in order to prevent the auxiliary stiffening pipe 12 from buckling, it is preferable that the auxiliary stiffening pipe 12 be designed to satisfy the following formula (15) in consideration of the gap e (mm) between the axial force pipe 11 and the auxiliary stiffening pipe 12 and the buckling length l (mm) of the axial force pipe 11.

[0092]

Number

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

[0094]

Number

[0095]

Number

[0096] where P R (N): Design axial force of the auxiliary stiffening pipe 12, b M b1 (N·mm): Short-term allowable bending strength of the auxiliary stiffening pipe 12, E (N / mm 2 ): Young's modulus of the auxiliary stiffening pipe 12, I b (mm 4 ): Second moment of area of the auxiliary stiffening pipe 12, l (mm): Buckling length of the axial force pipe 11, e (mm): Gap between the axial force pipe 11 and the auxiliary stiffening pipe 12, ν 0 (mm): Initial deflection of the auxiliary stiffening pipe (= l / 1000).

[0097] Note that 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 designing the supplementary rigid pipe 12 based on the above formulas. According to the above formulas (15) to (17), the gap e (mm) between the axial force pipe 11 and the supplementary rigid pipe 12 can be appropriately set according to the length l (mm) of the axial force pipe 11, so that the buckling restraint brace 1 can exhibit a stable energy absorption capacity during an earthquake, and a safe and economical building structure with high vibration control performance can be realized.

[0099]

Table 4

[0100] [Manufacturing method of buckling restraint brace] FIG. 23 shows an example of the procedure of the manufacturing method of the buckling restraint brace 1 according to an embodiment of the present invention.

[0101] The manufacturing method of the buckling restraint brace of this embodiment is a method for manufacturing the above-mentioned buckling restraint brace 1. The buckling restraint brace 1 manufactured by this manufacturing method is formed such that at least one of a set of end plates 13 has a planar shape smaller than the cross-sectional shape of the inner circumference of the supplementary rigid pipe 12.

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

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

[0104] In this way, the manufacturing method of the buckling restraint brace of the present embodiment is completed.

Explanation of Reference Numerals

[0105] 1 Buckling restraint brace 11 Axial force tube 11a Fixed plate 12 Supplementary stiffening tube 12a Welding hole 13 End plate 13a Notch 13b Backing plate 13c Supplementary stiffening tube welding part 14 Cruciform plate 14a Base part 14b Tip part 14c Inclined part 15 Plug welding (supplementary stiffening tube fixing part) 16 Fillet welding (supplementary stiffening tube fixing part) 17 Hanging piece W Welding metal 21 Structure-side cruciform plate 22 Attachment plate

Claims

1. an axial force tube 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 ends of the axial force tube so as to close the both ends; A pair of cross plates are joined to both ends of the axial force tube via the end plates and serve as fixing parts to a skeleton of an architectural structure. a backing plate is provided on a side surface of the end plate facing the axial force tube in such a manner as to abut against an inner surface of the axial force tube; A buckling restraint brace, in which the axial force tube and the end plate are welded together using a groove formed by the side surface of the end plate, the backing plate, and the end face of the axial force tube.

2. 2. 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.

3. The buckling restraint brace according to claim 2 , 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.

4. 3. The buckling restraint brace according to claim 2, 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.

5. The buckling restraint brace according to any one of claims 1 to 4, wherein a hanging piece is provided on an outer peripheral surface of the stiffening tube.

6. A method for manufacturing a buckling restraint brace according to any one of claims 1 to 4, 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 circumference of the stiffening tube, The axial force tube is inserted into the stiffening tube from the side to which the end plate having a planar shape smaller than the cross-sectional shape of the inner circumference of the stiffening tube is joined, Next, the cross plate is joined to the end plate having a planar shape smaller than the cross-sectional shape of the inner circumference of the stiffening tube, in a method for manufacturing a buckling restraint brace.

Images