Design and manufacturing method of buckling-restrained brace

Abstract

To provide a design and manufacturing method of a buckling-restrained brace capable of yielding a plasticized part by applying the appropriate axial force required for the buckling-restrained brace.SOLUTION: A design and manufacturing method of a buckling-restrained brace includes: a design step of determining the upper yield strength by setting a design shape of the plasticization part; and a manufacturing step of acquiring the actual yield strength. When the actual yield strength is less than the upper limit yield strength, the width of the plasticization part is corrected so that the yield axial force of the plasticization part after correction is the target yield axial force, and when the actual yield strength is greater than the upper yield strength, the actual yield strength is considered as the upper limit yield strength and the width of the plasticization part is corrected so that the corrected the yield axial force of the plasticization part after correction is closer to the target yield axial force.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to a method for designing and manufacturing a buckling restraint brace.

Background Art

[0002] Among buckling restraint braces attached to buildings and the like, for example, there are those provided with a core material formed of steel for bearing axial force and having a plasticized portion in the core material. The yield strength of the steel actually used for the core material of the buckling restraint brace may be greater than the yield strength planned for the steel used for the core material. At this time, while the core material can sufficiently secure the target yield axial force defined by the specifications of the buckling restraint brace, it does not yield even when an axial force greater than the target yield axial force occurs, and an excessively large axial force can occur.

[0003] Then, when an earthquake occurs, the plasticized portion in the core material of the buckling restraint brace does not plastically deform at the target yield axial force, which causes an excessive axial force to occur in the core material. As a result, a large load is applied to structural members such as columns and beams that should originally avoid damage in a building, and these may be damaged. Therefore, in a buckling restraint brace, it is preferable that the plasticized portion of the core material yields at the target yield axial force.

[0004] Here, although it is guaranteed that the steel used for the material of the core material satisfies the yield strength defined in the standard of the steel, there are variations in the actual yield strength of the steel. In order to cope with this, as a method for designing and manufacturing a buckling restraint brace by paying attention to the variation in the yield strength of the steel used as the material of the core material, for example, there is one disclosed in Patent Document 1.

[0005] The design and manufacturing method of Patent Document 1 measures the actual yield strength, which is the yield strength of the steel material actually used in the core material, during the manufacturing process, and corrects the plate width of the plasticized part in the core material from the designed shape according to the actual yield strength. As a result, even if there are variations in the actual yield strength of the steel material, it is possible to appropriately generate the target yield axial force set in the design process. Incidentally, in Patent Document 1, by adopting such a design and manufacturing method, it is said that ordinary steel with large variations in yield strength can also be adopted as the material for the core material, and there is an advantage of expanding the range of material selection.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] As described above, the design and manufacturing method of Patent Document 1 can yield the plasticized part of the core material with an appropriate axial force corresponding to the target yield axial force defined in the specifications of the buckling restraining brace by correcting the plate width of the plasticized part in the core material from the designed shape according to the actual yield strength of the steel material.

[0008] However, it is conceivable that the actual yield strength of the steel material may differ significantly from the reference value. In this case, in the design and manufacturing method of Patent Document 1, the correction amount for correcting the plate width of the plasticized part from the designed shape becomes a large correction amount corresponding to the large difference from the reference value, and the shape of the plasticized part will be significantly different from the shape designed with the reference yield strength (yield strength). As a result, for example, when correcting the length of the plasticized part so that the same rigidity as the core material of the designed shape can be maintained even in the core material with a reduced plate width, the length of the plasticized part may become extremely short. In this case, the amount of expansion and contraction borne per unit length of the plasticized part in the core material increases, and there is a risk that the fatigue resistance of the plasticized part will decrease.

[0009] In addition, if the yield strength of the actual steel material significantly differs from the reference value, the width of the plasticized portion may become extremely narrow due to shape correction, and it may not be possible to secure a sufficient width with respect to the plate thickness. Therefore, when cutting out the plasticized portion from the steel plate with a cutting machine, it becomes difficult to process the narrow-width plasticized portion, and there is a risk of a decrease in the shape accuracy of the plasticized portion. If the shape accuracy of the plasticized portion decreases, for example, stress concentration may occur in the plasticized portion when an axial load is applied during an earthquake. Thus, in the design and manufacturing method of Patent Document 1, by correcting the shape of the core material from the design reference shape, there is a risk of forming a shape that adversely affects the performance of the buckling restraint brace.

[0010] The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a design and manufacturing method for a buckling restraint brace that can yield a plasticized portion with an appropriate axial force required for the buckling restraint brace.

Means for Solving the Problems

[0011] To solve the above problems, the present invention proposes the following means. <1>The design and manufacturing method for a buckling restraint brace according to Aspect 1 of the present invention is a design and manufacturing method for a buckling restraint brace that is long and plate-shaped and includes a core material having a plasticized portion that is narrower in width at the central portion in the longitudinal direction than in the portions other than the central portion, and includes a design step and a manufacturing step. In the design step, based on the reference yield strength, which is the yield strength planned for the steel material used for the core material, such that the yield axial force of the plasticized portion becomes the target yield axial force, the design shape of the plasticized portion is set. An upper limit yield strength is set as a value predetermined as a value greater than the reference yield strength. In the manufacturing step, the actual yield strength, which is the yield strength of the steel material actually used for the core material, is obtained. When the actual yield strength is less than or equal to the upper limit yield strength, the plate width of the plasticized portion is corrected such that the yield axial force of the plasticized portion in the corrected shape approaches the target yield axial force. When the actual yield strength is greater than the upper limit yield strength, the actual yield strength is regarded as the upper limit yield strength, and the plate width of the plasticized portion is corrected such that the yield axial force of the plasticized portion in the corrected shape approaches the target yield axial force.

[0012] Here, in order to correct the shape of the plasticized portion so that the yield axial force of the plasticized portion of the core material approaches the target yield axial force, it is performed by making the width of the plasticized portion different from the width of the designed shape. At this time, if the correction amount of the shape of the plasticized portion is excessively large, for example, the width of the plasticized portion becomes extremely small, and as a result, the following problems are concerned. First, when the width of the plasticized portion becomes extremely small, the influence of the machining error on the width dimension appears and the cross-sectional shape becomes slightly non-uniform in the longitudinal direction, so that when an axial load is input, the stress distribution in the longitudinal direction does not become uniform and stress concentration occurs. In addition, when shortening the length of the plasticized portion to compensate for the decrease in the axial rigidity of the core material corresponding to the decrease in the width of the plasticized portion, the amount of expansion and contraction per unit length of the plasticized portion when a tensile-compressive axial load is repeatedly input increases, so there is a concern about the problem of deterioration of fatigue characteristics.

[0013] Therefore, according to Aspect 1, in the manufacturing process, when the actual yield strength is less than or equal to the upper limit yield strength, the plate width of the plasticized portion is corrected so that the yield axial force of the plasticized portion of the corrected shape approaches the target yield axial force. Further, when the actual yield strength is greater than the upper limit yield strength, regarding the actual yield strength as the upper limit yield strength, the plate width of the plasticized portion is corrected so that the yield axial force of the plasticized portion of the corrected shape approaches the target yield axial force. That is, even when correcting the shape of the plasticized portion, it is possible to suppress the correction amount from becoming excessively large. Therefore, it is possible to prevent the above-described problems from occurring.

Effect of the Invention

[0014] According to the present invention, it is possible to provide a method for designing and manufacturing a buckling restraint brace that can yield a plasticized portion with an appropriate axial force required in the buckling restraint brace.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0016] Hereinafter, with reference to the drawings, a design and manufacturing method of a buckling restraint brace 10 according to an embodiment of the present invention will be described. FIG. 1 is a conceptual diagram showing an example in which the buckling restraint brace 10 of the embodiment is provided in a building 1. As shown in FIG. 1, the building 1 includes, as structural materials such as a super high-rise building, columns 2, beam members 4, and a buckling restraint brace 10. The columns 2 are arranged at intervals in the lateral direction (horizontal direction) and are erected vertically. The beam members 4 are arranged at intervals in the vertical direction and are spanned horizontally between a pair of columns 2. The buckling restraint brace 10 is provided in an inclined manner at the intersection 6 of the column 2 and the beam member 4.

[0017] FIG. 2 is a conceptual diagram showing the buckling restraint brace 10 of the embodiment. FIG. 3 is a perspective view of the buckling restraint brace 10 of FIG. 2 disassembled. As shown in FIGS. 1 to 3, the buckling-restrained brace 10 includes, for example, a core material 12 that bears axial force, and a mortar 13 and a steel pipe 14 that restrain the core material 12. A buffer material (not shown) is interposed between the core material 12 and the mortar 13, for example. Therefore, the buffer material can prevent the axial force input to the core material 12 from being transmitted to the mortar 13 and the steel pipe 14. According to this buckling-restrained brace 10, it can be used as a seismic brace or a vibration damping damper having stable mechanical properties with the same characteristics in both tension and compression. Further, the buckling-restrained brace 10 is mainly utilized as a cross member of a building, and not only reduces the sway of the building during an earthquake, but also can suppress damage to the columns 2 and beam members 4.

[0018] The core material 12 is formed of a steel material (steel plate) in a long and plate shape. The core material 12 includes, for example, a pair of attachment portions 16, a pair of elastic portions 18, and a plasticization portion 20 (yield region). The plasticization portion 20 is located at the central portion in the longitudinal direction of the core material 12 and is formed to be narrower in width than the portions other than the central portion of the core material 12. The axial rigidity K of the core material 12 is Axial rigidity K = 1 / (1 / K2 + 1 / K1 + 1 / Kc + 1 / K1 + 1 / K2) represented by However, K1 = EA1 / L1 K2 = EA2 / L2 Kc = EAc / Lc A1: Average cross-sectional area of the elastic portion 18 L1: Length of the elastic portion 18 A2: Average cross-sectional area of the attachment portion 16 L2: Length of the attachment portion 16 Ac: Average cross-sectional area of the plasticization portion 20 Lc: Length of the plasticization portion 20 E: Elastic modulus of the core material 12

[0019] Further, the yield axial force Ny of the core material 12 is Yield axial force Ny = Acσy represented by However, σy: Yield strength of the core material 12 The yield axial force Ny refers to the load-bearing capacity when the plasticized portion 20 is pulled in the longitudinal direction of the core material 12. Hereinafter, the yield strength planned for the steel material used for the core material 12 in the design process may be referred to as the "reference yield strength σy".

[0020] Here, the steel material actually used for the core material 12 of the buckling restraint brace 10 is, for example, a JIS standard material such as SN490, SM490, SN400, or SM400. At this time, although the lower limit value of the yield strength of the core material 12 is guaranteed by the standard (for example, in the case of SN490B material with a plate thickness of 22 mm, it is 325 MPa or more), the specific yield strength varies depending on the lot of the steel material. Therefore, in the steel material actually used for the core material 12, a material with a yield strength different from the reference yield strength σy of the core material 12 set in the design process may be used. In that case, the yield axial force Ny and the yield displacement δy of the core material 12 may be different from those set in the design process. Hereinafter, the yield strength of the steel material actually used for the core material 12 may be referred to as the "actual yield strength σy".

[0021] Figure 4 is a graph for explaining the variations in the yield axial force Ny and the yield displacement δy in the buckling restraint brace 10 of the embodiment. In Figure 4, the vertical axis represents the yield axial force Ny of the core material 12, and the horizontal axis represents the yield displacement δy of the core material 12. Graph G1 shows the relationship between the yield axial force Ny and the yield displacement δy of the core material 12 using a steel material with the reference yield strength σy. Graph G2 is a graph showing the relationship between the yield axial force Ny and the yield displacement δy of the core material 12 using a steel material with the actual yield strength σy. As shown in Figure 4, the yield axial force Ny and the yield displacement δy of the core material 12 in Graph G2 are different values from the yield axial force Ny and the yield displacement δy of the core material 12 in Graph G1 because the actual yield strength σy is different from the reference yield strength σy.

[0022] In the seismic response analysis considered during the seismic design of a building 1 such as a super high-rise building shown in FIG. 1, the core material 12 is generally assumed to be a perfectly elastoplastic body, and a bilinear model is used. Here, when the variation in the yield axial force Ny and the axial rigidity K is large, the assumed range (variation) of the bilinear model also becomes large, and there is a risk that the reliability (i.e., accuracy) of the results of the seismic response analysis will decrease. At this time, for example, when the yield axial force Ny becomes a value larger than the design value due to variation, the plasticization of the core material 12 is delayed. As a result, there is a possibility that members supporting long-term loads, such as the columns 2, the beam members 4, and the intersections 6 between the columns 2 and the beam members 4, will plastify first.

[0023] The plasticization of members supporting long-term loads is not preferable from the viewpoint of the reparability of the damage to the building 1. On the other hand, the core material 12 (i.e., the buckling-restrained brace 10) is a member that does not need to support long-term loads, and even if it plastifies due to an earthquake, it can be replaced as needed. For this reason, even when the actual yield strength σy” is different from the reference yield strength σy due to variation, it is preferable that the yield axial force Ny of the core material 12 be as designed.

[0024] Next, the correction of the shape of the core material 12 when the actual yield strength σy” is different from the reference yield strength σy will be described with reference to FIGS. 5 and 6. In the present embodiment, the actual yield strength σy” is obtained, for example, from the actual measurement by a tensile test or the value described in the mill sheet for the actual steel material.

[0025] FIG. 5 is a plan view showing the design shape of the core material 12 of the embodiment. FIG. 6 is a plan view showing the shape obtained by correcting the core material 12 of the embodiment from the design shape. In the core material 12 shown in FIG. 5, the target yield axial force Ny, which is the yield axial force in the design process ” is the target yield axial force Ny ” =Acσy = WcTσy ··· (1) is represented by. However, the reference yield strength: σy the plate width of the plasticized portion 20: Wc the plate thickness of the plasticized portion 20: T Cross-sectional area of the plasticized part 20: Ac = WcT

[0026] Here, when the actual yield strength σy” is different from the reference yield strength σy, in order to maintain the target yield axial force Ny ” as shown in Fig. 6, by correcting the shape of the plasticized part 20, Ny = Ac”σy” = Wc”Tσy” ··· (2) it is necessary to satisfy However, the actual yield strength σy” Width of the plate of the plasticized part 20 after correction: Wc” Thickness of the plate of the plasticized part 20: T Cross-sectional area of the plasticized part 20 after correction: Ac” = Wc”T

[0027] Therefore, it is necessary to change the width Wc of the plate of the plasticized part 20 of the core material 12 in the design process to the width Wc” of the plate of the plasticized part 20 after correction based on the following formula (3). Wc” = Wcσy / σy” ··· (3) As a result, in the core material 12 formed of steel with an actual yield strength σy”, the target yield axial force Ny ” used in the design process can be obtained. Here, since the actual yield strength σy” is generally greater than the guaranteed value of the steel (the lower limit of the yield strength guaranteed by the standard), the relationship of σy < σy” holds. Therefore, according to the above formula (3), Wc > Wc”. Therefore, in the design process, by setting the standard for the steel planned to be used for the core material 12 with the reference yield strength σy to the guaranteed value guaranteed by the standard, the correction of the shape of the plasticized part 20 performed in the manufacturing process can be carried out by cutting out the steel so that the width Wc” of the plate of the plasticized part 20 after correction is narrower than the width Wc of the plate in the design process. That is, it is possible to avoid the correction of widening the width Wc of the plasticized part 20. As will be described below, in order to match the axial rigidity to the designed shape, the shape correction of increasing the length Lc of the plasticized part 20 can be avoided. This can avoid the problem that the length of the mounting part occupying the limited total length of the buckling restraint brace 10 cannot be ensured.

[0028] After changing the plate width Wc of the plasticizing portion 20 to Wc”, in order for the axial rigidity Kc of the plasticizing portion 20 not to change, Kc = EAc / Lc = EWcT / Lc ··· (4) Kc = EAc” / Lc” = EWc”T / Lc” ··· (5) It is necessary to satisfy. However, elastic modulus of the core material 12: E Cross-sectional area of the plasticizing portion 20: Ac = WcT Length of the plasticizing portion 20: Lc Cross-sectional area of the plasticizing portion 20 after correction: Ac” = Wc”T Length of the plasticizing portion 20 after correction: Lc” Therefore, it is necessary to change the length Lc of the plasticizing portion 20 of the core material 12 in the design process to the length Lc” of the plasticizing portion 20 after correction based on the following equation (6). Lc” = LcWc” / Wc ··· (6)

[0029] Thereby, in the core material 12 formed of the actual steel material having the actual yield strength σy”, the axial rigidity Kc set in the design process can be obtained. Furthermore, by adjusting the yield axial force Ny and the axial rigidity Kc of the plasticizing portion 20 to the values set in the design process, it is also possible to obtain the yield displacement δy set at the time of design for the yield displacement δy.

[0030] Here, in the design process, if the guaranteed value of the steel material planned to be used for the core material 12 is set as the reference yield strength σy, the actual yield strength σy” will satisfy the relationship σy < σy” as described above, and the relationship Wc > Wc” will be established from equation (3). Also, the relationship Lc > Lc” will be established from equation (6).

[0031] Therefore, in the design process, if the guaranteed value of the steel material planned to be used for the core material 12 is set as the reference yield strength σy, corrections to increase the plate width Wc and the length Lc of the plasticized portion 20 in the core material 12 will not be performed, and the problem that the length of the attachment portion in the limited overall length of the buckling restraining brace 10 cannot be ensured can be avoided. Therefore, for example, even after ordering the steel material used for the core material 12, it is possible to change Wc to Wc” and change Lc to Lc” according to the actual yield strength σy” of the delivered steel material.

[0032] Next, a specific example of the design and manufacturing method of the buckling restraining brace 10 in the embodiment will be described with reference to FIGS. 7 to 9. FIG. 7 shows the actual yield strength σy of the steel material ” when it is assumed to follow a normal distribution. ” FIG. 7 is a distribution diagram showing the distribution of the actual yield strength σy. In FIG. 7, the horizontal axis represents the actual yield strength σy”. The graph G3 shows the statistically estimated distribution of the actual yield strength σy” in the steel material.

[0033] As shown in FIG. 7, for the actual yield strength σy” of the steel material following a normal distribution, with the standard deviation of the normal distribution being σ, 99.7% is included in the range of -3σ to +3σ with respect to the average value of the actual yield strength σy. Also, 95% of the actual yield strength σy” of the steel material is included in the range of -2σ to +2σ with respect to the average value of the actual yield strength σy. Further, 68% of the actual yield strength σy” of the steel material is included in the range of -1σ to +1σ with respect to the average value of the actual yield strength σy. ” In this embodiment, in the design process, it is assumed that the actual yield strength σy” of this steel material follows a normal distribution, and the reference yield strength σy is set considering the standard deviation σ of the actual yield strength σy in this case. ” Specifically, during design, the reference yield strength σy is ” Reference yield strength σy = average value of performance data - 2 × σ (standard deviation) Reference yield strength σy = average value of performance data - 1 × σ (standard deviation) ”

[0034] Specifically, during design, the reference yield strength σy is Reference yield strength σy = average value of performance data - 2 × σ (standard deviation) Reference yield strength σy = average value of performance data - 1 × σ (standard deviation) ​The reference yield strength σy = the average value of the actual data It was defined by selecting from the set levels.

[0035] In this embodiment, in the design process, the allowable range of the actual yield strength σy” is set as follows. The allowable range of the actual yield strength σy” is the allowable range of the variation in the yield strength of the steel material including the reference yield strength σy. That is, the allowable range of the variation in the actual yield strength σy” with respect to the reference yield strength σy defined as above is set to be within, for example, ±5% or ±10% of the reference yield strength σy. In this embodiment, in the manufacturing process, when the actual yield strength σy” is within the allowable range including the reference yield strength σy, for example, within ±5% of the reference yield strength σy, the shape correction of the plasticized portion 20 is not performed and the designed shape is maintained. When emphasizing productivity in the manufacturing process, the allowable range of the actual yield strength σy” may be made wider, for example, ±10% of the reference yield strength σy. However, it should be noted that if the allowable range of the actual yield strength σy” is large, the variation in the axial force of the buckling restraint brace 10, which is the product, also becomes large. Therefore, the allowable range of the actual yield strength σy” is preferably set as large as possible within the range allowable as the yield strength of the plasticized portion 20 In the range allowable as the yield strength, it is preferably set as large as possible.

[0036] Here, FIG. 7 shows a plurality of examples of the range in which the shape correction of the plasticized portion 20 is not required when the allowable range of the actual yield strength σy” is set to ±10% of the reference yield strength σy. In FIG. 7, the allowable range A shows the allowable range when the reference yield strength σy is set to a value 2σ lower than the average value of the actual data. The allowable range B shows the allowable range when the reference yield strength σy is set to a value 1σ lower than the average value of the actual data. The allowable range C shows the allowable range when the reference yield strength σy is set to the average value of the actual data.

[0037] When the allowable range A is set in the design engineering, that is, when the reference yield strength σy is set to a value 2σ lower than the average value of the actual data, if the actual yield strength σy” falls within the allowable range A shown in FIG. 7, the shape of the plasticizing part 20 is not corrected in the manufacturing process. On the other hand, if the actual yield strength σy” is out of the allowable range A, it is determined that the shape of the plasticizing part 20 needs to be corrected. Here, when the reference yield strength σy is set to a value 2σ lower than the average value of the actual data, as shown in FIG. 7, if the actual yield strength σy” is out of the allowable range A, for most of the actual yield strengths σy”, the relationship σy < σy” holds with respect to the reference yield strength σy set in the design engineering. Therefore, the correction of the plasticizing part 20 is to reduce the plate width Wc and the length Lc of the plasticizing part 20 set at the time of design, so the corresponding correction is easy.

[0038] When the reference yield strength σy = the average value of the actual data - 1σ, if the actual yield strength σy” falls within the allowable range B shown in FIG. 7, the shape of the plasticizing part 20 is not corrected in the manufacturing process. On the other hand, if the actual yield strength σy” is out of the allowable range B, it is determined that the shape of the plasticizing part 20 needs to be corrected. At this time, if σy < σy” holds, the correction of the plasticizing part 20 is to reduce the plate width Wc and the length Lc of the plasticizing part 20 set at the time of design, so the corresponding correction is easy.

[0039] When the reference yield strength σy = the average value of the actual data, if the actual yield strength σy” falls within the allowable range C shown in FIG. 7, the shape of the plasticizing part 20 is not corrected in the manufacturing process. On the other hand, if the actual yield strength σy” is out of the allowable range C, it is determined that the shape of the plasticizing part 20 needs to be corrected. At this time, if σy < σy” holds, the correction of the plasticizing part 20 is to reduce the plate width Wc and the length Lc of the plasticizing part 20 set at the time of design, so the corresponding correction is easy.

[0040] Here, when the reference yield strength σy = the average value of the actual data - 1σ, or when the reference yield strength σy = the average value of the actual data, it is probabilistically considered that σy > σy”. To cope with this situation, it is necessary to correct by increasing the plate width Wc and the length Lc of the plasticized part 20.

[0041] At this time, when the reference yield strength σy = the average value of the actual data - 1σ, that is, when it is judged whether correction is necessary based on the allowable range B, since the correction amount when increasing the plate width Wc and the length Lc of the plasticized part 20 is relatively small, it is possible to cope by leaving a margin in the cutting method during the manufacturing process in the design process, but the yield of the steel material deteriorates.

[0042] However, when the reference yield strength σy = the average value of the actual data, that is, when judging whether correction is necessary based on the allowable range C, if the actual yield strength σy” is a value significantly different from the upper limit value or the lower limit value of the allowable range C, the correction amount when increasing the plate width Wc and the length Lc of the plasticized part 20 becomes relatively large, it becomes difficult to appropriately perform shape correction, and the steel material with the actual yield strength σy” cannot be used. Therefore, when emphasizing the yield of the steel material, it is not preferable to set the reference yield strength σy = the average value of the actual data.

[0043] Since the yield strength of the steel material used for the core material 12 is generally JIS standard materials such as SN490, SM490, SN400, and SM400, the lower limit value guaranteed by the standard is determined. Hereinafter, the lower limit value of the yield strength guaranteed by the steel material standard may be referred to as the “guaranteed value”. Therefore, the reference yield strength σy may be set to 1.3 times the guaranteed value of the yield strength of the steel material, and the allowable range of variation may be set to ±10% of the reference yield strength σy. Thereby, since it is statistically inferred that the actual yield strength σy” falls within the allowable range in many cases, it is possible to increase as much as possible the cases where the shape of the plasticized part does not need to be corrected.

[0044] Incidentally, regardless of the above, the reference yield strength σy may be set to the guaranteed value which is the lower limit of the yield strength guaranteed by the steel material standard. In this case, since all the actual yield strengths σy” of the steel materials to be delivered are equal to or higher than the reference yield strength σy, it is possible to reliably suppress the need for correction to increase the plate width Wc and the length Lc of the plasticized portion 20.

[0045] Alternatively, the reference yield strength σy may be set to, for example, the guaranteed value of the steel material planned to be used for the core material 12. In this case, it is preferable to set the lower limit value of the allowable range to the reference yield strength σy. That is, when the guaranteed value of the steel material planned to be used for the core material 12 is taken as the reference yield strength σy, if the actual yield strength σy” is within the allowable range D shown in FIG. 7, the shape of the plasticized portion 20 may not be corrected in the manufacturing process. On the other hand, when the actual yield strength σy” is out of the allowable range D, it is determined that correction of the shape of the plasticized portion 20 is necessary. At this time, when σy < σy” holds, the correction of the plasticized portion 20 is to reduce the plate width Wc and the length Lc of the plasticized portion 20 set at the time of design, so the correction response is easy. Incidentally, the allowable range D is an allowable range in which the lower limit value is the reference yield strength σy and the upper limit value is a value of +20% of the reference yield strength σy when the reference yield strength σy is the guaranteed value of the steel material planned to be used for the core material 12. That is, the allowable range D allows only a range larger than the reference yield strength σy.

[0046] Next, a specific example of the design and manufacturing method of the buckling restraint brace 10 of the embodiment will be described with reference to FIGS. 8 and 9. FIG. 8 is a flowchart for explaining the design process and the manufacturing process in the design and manufacturing method of the buckling restraint brace 10 of the embodiment. As shown in FIG. 8, the design and manufacturing method of the buckling restraint brace 10 includes a design process of setting the design shape of the plasticized portion 20, and a manufacturing process of manufacturing the plasticized portion 20 based on the design shape of the plasticized portion 20 and the actual yield strength σy” set in the design process.

[0047] First, a specific example of setting the design shape of the plasticized portion 20 in the design process will be described. In the design process, the design shape of the plasticizing portion 20 is set based on the reference yield strength σy of the steel material so that the yield axial force Ny of the plasticizing portion 20 becomes the target yield axial force. Hereinafter, the reference yield strength σy may be referred to as "reference yield strength σy1 (reference yield strength)". The target yield axial force is set, for example, based on the specifications of the buckling restraint brace 10 so that the plasticizing portion 20 yields with an appropriate axial force. The reference yield strength σy1 is the yield strength planned for the steel material used for the core material 12. Also, in the design process, an upper limit yield strength σy2 (upper limit yield strength) is set. The upper limit yield strength σy2 is a yield strength outside the allowable range of the yield strength including the reference yield strength σy1, and is a value predetermined as a value larger than the reference yield strength σy1.

[0048] Next, a specific example of manufacturing the plasticizing portion 20 in the manufacturing process will be described. In the manufacturing process, an actual yield strength σy” is obtained. The actual yield strength σy” is obtained, for example, by actually measuring the yield strength of the steel material actually used as the core material 12. Alternatively, the actual yield strength σy” is obtained from the value described in the mill sheet of the steel material actually used as the core material 12.

[0049] When the obtained actual yield strength σy” is within the allowable range of the yield strength, the plasticizing portion 20 is not corrected. When the obtained actual yield strength σy” is outside the allowable range of the yield strength and is equal to or less than the upper limit yield strength σy2, the plate width Wc of the plasticizing portion 20 is corrected so that the yield axial force Ny of the plasticizing portion 20 after correction approaches the target yield axial force. That is, according to the shape after correction, the plasticizing portion 20 is cut out by a cutting machine or the like to manufacture the core material 12.

[0050] On the other hand, when the actual yield strength σy” is outside the allowable range of the yield strength and greater than the upper limit yield strength σy2, the actual yield strength σy” is regarded as the upper limit yield strength σy2, and the plate width Wc of the plasticized part 20 is corrected so that the yield axial force Ny of the plasticized part 20 in the corrected shape approaches the target yield axial force. That is, according to the corrected shape, the plasticized part 20 is cut out by a cutting machine or the like to manufacture the core material 12.

[0051] Here, the relationship between the actual yield strength σy” and the correction amount of the plate width Wc (plate width correction amount) will be described based on FIG. 9. FIG. 9 is a graph for explaining the relationship between the actual yield strength σy” and the plate width correction amount. In FIG. 9, the vertical axis represents the plate width correction amount of the plasticized part 20, and the horizontal axis represents the actual yield strength σy”. The graph G4 shows the relationship between the actual yield strength σy” and the plate width correction amount.

[0052] As shown in FIG. 9, when the actual yield strength σy” is between the reference yield strength σy1 and the upper limit yield strength σy2, that is, when the obtained actual yield strength σy” is outside the allowable range of the yield strength and less than or equal to the upper limit yield strength σy2, the plate width correction amount of the plasticized part 20 increases as the actual yield strength σy” moves away from the reference yield strength σy1. That is, for example, when the actual yield strength σy” is in the region P1 shown in FIG. 9, the plate width correction amount of the plasticized part 20 increases as it moves away from the reference yield strength σy1.

[0053] On the other hand, when the actual yield strength σy” exceeds the upper limit yield strength σy2, that is, when the actual yield strength σy” is outside the allowable range of the yield strength and greater than the upper limit yield strength σy2, the actual yield strength σy” is regarded as the upper limit yield strength σy2. That is, for example, when the actual yield strength σy” is in the region P2 shown in FIG. 9, the actual yield strength σy” is regarded as the upper limit yield strength σy2. This suppresses the plate width correction amount of the plasticized part 20 to be constant when the actual yield strength σy” exceeds the upper limit yield strength σy2. In this way, the plate width correction amount of the plasticized part 20 is adjusted as appropriate.

[0054] In the manufacturing process, when the actual yield strength σy” is outside the allowable range of the yield strength and is less than or equal to the upper yield strength σy2, the shape of the plasticized portion 20 may be corrected so that the yield axial force Ny of the plasticized portion 20 in the corrected shape becomes the target yield axial force. In addition, when the actual yield strength σy” is outside the allowable range of the yield strength and is greater than the upper yield strength σy2, the actual yield strength σy” is regarded as the upper yield strength σy2, and on this basis, the shape of the plasticized portion 20 may be corrected so that the yield axial force Ny of the plasticized portion 20 in the corrected shape becomes the target yield axial force.

[0055] Furthermore, the axial rigidity K shown by the plasticized portion 20 in the designed shape formed of a steel material with a reference yield strength σy1 may be preset as the reference axial rigidity, and the plasticized portion 20 may be corrected so that the axial rigidity K becomes the reference axial rigidity. That is, in the manufacturing process, while correcting the plate width Wc of the plasticized portion 20 so that the yield axial force Ny of the plasticized portion 20 becomes the target yield axial force, the length Lc of the plasticized portion 20 may be corrected so that the axial rigidity K of the plasticized portion 20 based on the corrected plate width Wc becomes the reference axial rigidity. In this case, the upper yield strength σy2 is a value greater than the reference yield strength σy1, and is predetermined as the yield strength when the length of the corrected plasticized portion 20 becomes the limit length defined as the shortest allowable length. Note that the limit length is the length that can ensure the fatigue strength of the core material 12. The limit length of the plasticized portion 20 is, for example, the length that shows at least 80% or more of the fatigue strength shown by the plasticized portion 20 in the designed shape. Note that the fatigue strength can be represented by the number of repetitions (fatigue life) until fracture occurs under a repeated load equal to or greater than the fatigue limit, or the magnitude of the repeated load that is equal to or greater than the fatigue limit and does not fracture until the target number of repetitions.

[0056] In the manufacturing process, the plate width Wc of the plasticized portion 20 may be corrected so that the yield axial force Ny of the plasticized portion 20 becomes the target yield axial force. In this case, the upper yield strength σy2 is predetermined as the yield strength when the plate width Wc of the corrected plasticized portion 20 becomes the limit allowable width defined as the shortest allowable width. The allowable tolerance width is the length that can ensure the processing accuracy of the core material 12. The allowable tolerance width of the plasticized portion 20 is, for example, at least three times or more the plate thickness of the core material 12.

[0057] Furthermore, a predetermined range including the reference yield strength σy1 and not including the upper limit yield strength σy2 may be set in advance as an allowable range, and the correction of the plasticized portion 20 may be determined in consideration of the allowable range. That is, in the manufacturing process, when the actual yield strength σy” is within the allowable range, the shape of the plasticized portion 20 is not corrected. On the other hand, when the actual yield strength σy” is outside the allowable range and is less than or equal to the upper limit yield strength σy2, the shape of the plasticized portion 20 may be corrected so that the yield axial force Ny of the plasticized portion 20 after correction approaches the target yield axial force.

[0058] As described above, according to the design and manufacturing method of the buckling restraint brace 10 of the embodiment, the following effects can be obtained. Here, in order to correct the shape of the plasticized portion 20 so that the yield axial force Ny of the plasticized portion 20 of the core material 12 approaches the target yield axial force, it is performed by making the width of the plasticized portion 20 different from the width of the designed shape. At this time, if the correction amount of the shape of the plasticized portion 20 is excessively large, for example, the width of the plasticized portion 20 becomes extremely small, and as a result, the following problems are concerned. First, when the width of the plasticized portion 20 becomes extremely small, the influence of the processing error on the width dimension appears and the cross-sectional shape becomes slightly non-uniform in the longitudinal direction, so that when an axial load is input, the stress distribution in the longitudinal direction does not become uniform and stress concentration occurs. Also, when shortening the length Lc of the plasticized portion 20 to compensate for the decrease in the axial rigidity of the core material 12 due to the decrease in the width of the plasticized portion 20, the expansion and contraction amount per hit of the plasticized portion 20 when a tensile-compressive axial load is repeatedly input becomes large, so there is a concern about the problem of deterioration of fatigue characteristics.

[0059] Therefore, as shown in FIGS. 3, 8, and 9, in the manufacturing process, when the actual yield strength σy” is less than or equal to the upper limit yield strength σy2, the plate width Wc of the plasticized portion 20 is corrected so that the yield axial force Ny of the plasticized portion 20 in the corrected shape approaches the target yield axial force. Further, when the actual yield strength σy” is greater than the upper limit yield strength σy2, the actual yield strength σy” is regarded as the upper limit yield strength σy2, and the plate width Wc of the plasticized portion 20 is corrected so that the yield axial force Ny of the plasticized portion 20 in the corrected shape approaches the target yield axial force. That is, even if the shape of the plasticized portion is corrected, it is possible to suppress the correction amount from becoming excessively large. Therefore, the above-described problem can be prevented from occurring.

[0060] Further, the shape of the plasticized portion 20 may be corrected so that the yield axial force Ny of the plasticized portion 20 in the corrected shape becomes the target yield axial force. Thereby, even when the reference yield strength σy1 and the actual yield strength σy” are different, the yield axial force Ny of the plasticized portion 20 can be made as designed.

[0061] Furthermore, in the manufacturing process, while correcting the plate width Wc of the plasticized portion 20 so that the yield axial force Ny of the plasticized portion 20 becomes the target yield axial force, the length Lc of the plasticized portion 20 may be corrected so that the axial rigidity K of the plasticized portion 20 at the corrected plate width Wc becomes the reference axial rigidity. The reason for adjusting the axial rigidity K with the length Lc of the plasticized portion 20 is that the axial rigidity K changes as a result of adjusting the yield axial force Ny of the plasticized portion 20 by correcting the plate width Wc. In this case, the upper limit yield strength σy2 is predetermined as the yield strength when the length Lc of the corrected plasticized portion 20 becomes the limit length defined as the shortest allowable length.

[0062] Thereby, for example, by setting the limit length to a length capable of ensuring the fatigue fracture strength of the core material 12, the length Lc of the plasticized portion 20 can be kept within a range of lengths capable of ensuring the fatigue fracture strength allowable for the core material 12. Therefore, the fatigue strength of the plasticized portion 20 can be kept within an allowable range. Thereby, for example, it is possible to suppress the plasticized portion 20 from suffering fatigue fracture when an axial vibration load is repeatedly input to the buckling restraint brace 10.

[0063] Further, in the manufacturing process, the plate width Wc of the plasticizing portion 20 may be corrected so that the yield axial force Ny of the plasticizing portion 20 becomes the target yield axial force. In this case, the upper limit yield strength σy2 is predetermined as the yield strength when the plate width Wc of the plasticizing portion 20 after correction becomes the limit allowable width defined as the shortest allowable width. By setting the limit allowable width for the plate width Wc of the plasticizing portion 20 in this way, for example, it is possible to suppress the difficulty of processing the plasticizing portion 20 and to suppress the occurrence of a decrease in shape accuracy.

[0064] Furthermore, in the manufacturing process, the actual yield strength σy” of the steel material actually used for the core material 12 is measured to obtain the actual yield strength σy”, or the actual yield strength σy” is obtained from the value described in the mill sheet for the steel material. Thereby, for example, it is possible to surely obtain an accurate value for the actual yield strength σy”.

[0065] Also, in the manufacturing process, when the actual yield strength σy” is within the allowable range, the shape of the plasticizing portion 20 may not be corrected. On the other hand, when the actual yield strength σy” is outside the allowable range and is equal to or less than the upper limit yield strength σy2, the shape of the plasticizing portion 20 may be corrected so that the yield axial force Ny of the plasticizing portion 20 after correction approaches the target yield axial force. Thereby, even if the actual yield strength σy” is different from the reference yield strength σy1, as long as the actual yield strength σy” is within the allowable range, the core material 12 can be manufactured in the shape of the design shape. Therefore, in the manufacturing process, the opportunity to change the operation setting of the manufacturing apparatus for manufacturing the core material 12 can be reduced, and a decrease in productivity in the manufacturing process can be suppressed.

[0066] Also, if the actual yield strength is outside the allowable range, in the manufacturing process, the shape of the plasticizing portion 20 is corrected, and the yield axial force Ny approaches the target yield axial force. Therefore, the plasticizing portion 20 can be made to yield with an appropriate axial force required in the buckling restraining brace 10.

[0067] Note that the technical scope of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, when the actual yield strength σy” is outside the allowable range and is equal to or less than the upper limit yield strength σy2, the shape of the plasticizing portion 20 may be corrected as follows. That is, the shape of the plasticizing portion 20 may be corrected so that the yield axial force Ny of the plasticizing portion 20 having the shape after correction becomes the target yield axial force, or so that it falls within the allowable yield axial force range. Even in this case, a decrease in productivity in the manufacturing process can be suppressed.

[0068] In addition, without departing from the spirit of the present invention, it is possible to appropriately replace the components in the above-described embodiments with well-known components, and the above-described modified examples may be appropriately combined.

Explanation of Reference Numerals

[0069] 1 Building 2 Column 4 Beam member 6 Intersection 10 Buckling-restrained brace 12 Core material 13 Mortar 14 Steel pipe 16 Mounting portion 18 Elastic portion 20 Plasticizing portion A Allowable range B Allowable range C Allowable range Wc Plate width Lc Length σy Reference yield strength σy” Actual yield strength

Claims

1. A method for designing and manufacturing a buckling-restrained brace, comprising a core material that is long and plate-shaped and has a plasticized portion at the central part in the longitudinal direction, the width of which is narrower than that of the portions other than the central part. The method includes a design process and a manufacturing process. In the design process: Based on the reference yield strength, which is the yield strength planned for the steel material used for the core material, such that the yield axial force of the plasticized portion becomes the target yield axial force, the design shape of the plasticized portion is set. An upper limit yield strength is set as a value determined in advance to be greater than the reference yield strength. In the manufacturing process: The actual yield strength, which is the yield strength of the steel material actually used for the core material, is obtained. When the actual yield strength is less than or equal to the upper limit yield strength, the plate width of the plasticized portion is corrected so that the yield axial force of the plasticized portion in the corrected shape approaches the target yield axial force. When the actual yield strength is greater than the upper limit yield strength, the actual yield strength is regarded as the upper limit yield strength, and the plate width of the plasticized portion is corrected so that the yield axial force of the plasticized portion in the corrected shape approaches the target yield axial force. This is a method for designing and manufacturing a buckling-restrained brace, characterized by the above.

2. In the manufacturing process, the shape of the plasticized portion is corrected so that the yield axial force of the plasticized portion in the corrected shape becomes the target yield axial force. This is a method for designing and manufacturing a buckling-restrained brace according to Claim 1, characterized by the above.

3. Taking the axial rigidity shown by the plasticized portion in the design shape formed of the steel material with the reference yield strength as the reference axial rigidity. In the manufacturing process, the plate width of the plasticized portion is corrected so that the yield axial force of the plasticized portion becomes the target yield axial force, and the length of the plasticized portion is corrected so that the axial rigidity of the plasticized portion at the corrected plate width becomes the reference axial rigidity. The upper limit yield strength is the yield strength when the length of the corrected plasticized portion becomes the limit length defined as the shortest allowable length. This is a method for designing and manufacturing a buckling-restrained brace according to Claim 1, characterized by the above.

4. In the manufacturing process, the plate width of the plasticized portion is corrected so that the yield axial force of the plasticized portion becomes the target yield axial force. The upper limit yield strength is the yield strength when the plate width of the corrected plasticized portion becomes the limit allowable width defined as the shortest allowable width. This is a method for designing and manufacturing a buckling-restrained brace according to Claim 1, characterized by the above.

5. ​ In the manufacturing process, the actual yield strength is obtained by actually measuring the yield strength of the steel material actually used for the core material, or the actual yield strength is obtained from the value described in the mill sheet for the steel material. The method for designing and manufacturing a buckling restraint brace according to any one of claims 1 to 4, characterized by the above.

6. A predetermined range including the reference yield strength and not including the upper limit yield strength is defined as an allowable range. In the manufacturing process, when the actual yield strength is within the allowable range, the shape of the plasticized portion is not corrected. When the actual yield strength is outside the allowable range and is less than or equal to the upper limit yield strength, the shape of the plasticized portion is corrected so that the yield axial force of the plasticized portion after correction approaches the target yield axial force. The method for designing and manufacturing a buckling restraint brace according to any one of claims 1 to 4, characterized by the above.

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