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 a required appropriate axial force to a buckling-restrained brace while preventing a decline in productivity during the manufacturing process.SOLUTION: A design and manufacturing method of buckling-restrained brace includes: a design step of setting a design shape of a plasticization part based on the standard yield strength so that the yield axial force of the plasticization part is a target yield axial force; and a manufacturing step of acquiring the actual yield strength of a steel that is used for the core material. When the actual yield strength is within an allowable range including the standard yield strength, the shape of the plasticization part is maintained to its design shape, and when the actual yield strength is outside the allowable range, the shape of the plasticization part is corrected so that the yield axial force is close 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, those having a core material formed of steel for bearing axial force and having a plasticized portion in the core material are known. 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. To address this, as a method for designing and manufacturing a buckling restraint brace by focusing on the variations 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] In the design and manufacturing method of Patent Document 1, during the manufacturing process, the actual yield strength, which is the yield strength of the steel material actually used for the core material, is measured, and the plate width of the plasticized part in the core material is corrected from the designed shape according to the actual yield strength. Thereby, 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 restraint 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. However, as described above, there are variations in the actual yield strength of the steel material used as the material for the core material, and it is almost impossible for the actual yield strength to match the reference yield strength. In most cases, there is a difference between the two.

[0008] Therefore, in the design and manufacturing method of Patent Document 1, in most cases, the shape of the plasticized part is corrected from the designed shape so that the actual yield strength of the actually used steel material also becomes the target yield axial force, and the operation settings of manufacturing devices such as cutting machines for cutting out the core material from the steel material are frequently changed from the settings corresponding to the designed shape. Frequently changing the operation settings of manufacturing devices causes a decrease in productivity in the manufacturing process.

[0009] The present invention has been made in view of the above-described circumstances, and an object thereof is to obtain a method for designing and manufacturing a buckling-restrained brace that can suppress a decrease in productivity in the manufacturing process and can yield a plasticized portion with an appropriate axial force required for the buckling-restrained brace.

Means for Solving the Problems

[0010] In order to solve the above problems, the present invention proposes the following means. <1>The method for designing and manufacturing a buckling-restrained brace according to Aspect 1 of the present invention is a method for designing and manufacturing a buckling-restrained brace including a core material that is long and plate-shaped and has a plasticized portion narrower in width than portions other than the central portion in the longitudinal direction, 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, so that the yield axial force of the plasticized portion becomes the target yield axial force, the design shape of the plasticized portion is set. 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 within the allowable range including the reference yield strength, the shape of the plasticized portion is maintained as the design shape. When the actual yield strength is outside the allowable range, the shape of the plasticized portion is corrected so that the yield axial force approaches the target yield axial force.

[0011] According to Aspect 1, 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, so that the yield axial force of the plasticized portion becomes the target yield axial force required for the buckling-restrained brace, the design shape of the plasticized portion is set. 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 within the allowable range including the reference yield strength, the shape of the plasticized portion is maintained as the designed shape. When the actual yield strength is outside the allowable range, the shape of the plasticized portion is corrected so that the yield axial force approaches the target yield axial force. As a result, even if the actual yield strength is different from the reference yield strength, as long as the actual yield strength is within the allowable range, the core material can be manufactured in the shape as designed. Therefore, in the manufacturing process, the opportunity to change the operation settings of the manufacturing apparatus for manufacturing the core material can be reduced, and the decrease in productivity in the manufacturing process can be suppressed. Also, when the actual yield strength is outside the allowable range, in the manufacturing process, the shape of the plasticized portion is corrected, and the yield axial force approaches the target yield axial force. Therefore, the plasticized portion can be made to yield with an appropriate axial force required in the buckling restraining brace.

Advantages of the Invention

[0012] According to the present invention, a decrease in productivity in the manufacturing process can be suppressed.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0014] Hereinafter, with reference to the drawings, a method for designing and manufacturing 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 a buckling restraint brace 10 according to an embodiment is provided in a building 1. As shown in FIG. 1, the building 1 includes, for example, columns 2, beam members 4, and a buckling restraint brace 10 as structural materials such as a super high-rise building. 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 shape at the intersection 6 of the column 2 and the beam member 4.

[0015] FIG. 2 is a conceptual diagram showing the buckling restraint brace 10 according to the embodiment. FIG. 3 is a perspective view of the buckling restraint brace 10 shown in FIG. 2 disassembled. As shown in FIGS. 1 to 3, the buckling restraint brace 10 includes, for example, a core material 12 that bears an axial force, and a mortar 13 and a steel pipe 14 that restrain the core material 12. In the buckling restraint brace 10, for example, a buffer material (not shown) is interposed between the core material 12 and the mortar 13. 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 restraint 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. In addition, the buckling restraint brace 10 is mainly utilized as a cross member of a building, and not only can reduce the sway of the building during an earthquake, but also can suppress damage to the columns 2 and the beam members 4.

[0016] The core member 12 is formed of a steel material (steel plate) in a long and plate shape. The core member 12 includes, for example, a pair of attachment portions 16, a pair of elastic portions 18, and a plasticized portion 20 (yield region). The plasticized portion 20 is located at the central portion in the longitudinal direction of the core member 12 and is formed to be narrower in width than the portions other than the central portion of the core member 12. The axial rigidity K of the core member 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 plasticized portion 20 Lc: Length of the plasticized portion 20 E: Elastic modulus of the core member 12

[0017] Also, the yield axial force Ny of the core member 12 is Yield axial force Ny = Acσy represented by However, σy: Yield strength of the core member 12 The yield axial force Ny refers to the bearing capacity when the plasticized portion 20 is pulled in the longitudinal direction of the core member 12. Hereinafter, the yield strength planned for the steel material used for the core member 12 in the design process may be referred to as the "reference yield strength σy".

[0018] Here, the steel materials actually used for the core material 12 of the buckling restraint brace 10 are JIS standard materials such as SN490, SM490, SN400, and 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 will 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 "actual yield strength σy".

[0019] FIG. 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 FIG. 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 a 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 an actual yield strength σy. As shown in FIG. 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.

[0020] 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, if the variations in the yield axial force Ny and the axial rigidity K are large, the assumed range (variation) of the bilinear model also becomes large, and the reliability (i.e., accuracy) of the results of the seismic response analysis may decrease. At this time, for example, when the buckling axial force Ny becomes larger than the design value due to variations, 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 column 2, the beam member 4, and the intersection 6 between the column 2 and the beam member 4, may plastify earlier.

[0021] The plasticization of members supporting long-term loads is not preferable from the perspective of the reparability of damage to the building 1. On the other hand, the core material 12 (that is, the buckling restraint 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. Therefore, even when the actual yield strength σy” is different from the reference yield strength σy due to variations, it is preferable that the buckling axial force Ny of the core material 12 be as designed.

[0022] 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 actual measurements by a tensile test or values described in a mill sheet for actual steel materials.

[0023] FIG. 5 is a plan view showing the designed shape of the core material 12 of the embodiment. FIG. 6 is a plan view showing the shape of the core material 12 of the embodiment corrected from the designed shape. In the core material 12 shown in FIG. 5, the target buckling axial force Ny”, which is the buckling axial force in the design process, is Target buckling axial force Ny” = Acσy = WcTσy ··· (1) represented by. However, reference yield strength: σy Plate width of the plasticized part 20: Wc Plate thickness of the plasticized part 20: T Cross-sectional area of the plasticized part 20: Ac = WcT

[0024] Here, when the actual yield strength σy” is different from the reference yield strength σy, in order to maintain the target buckling axial force Ny”, by correcting the shape of the plasticized part 20 as shown in FIG. 6, Ny = Ac”σy” = Wc”Tσy” ··· (2) needs to be satisfied. However, the actual yield strength σy” Width of the plasticized part 20 after correction: Wc” Thickness of the plasticized part 20: T Cross-sectional area of the plasticized part 20 after correction: Ac” = Wc”T

[0025] Therefore, it is necessary to change the width Wc of the plasticized part 20 of the core material 12 in the design process to the width Wc” of the plasticized part 20 after correction based on the following formula (3). Wc” = Wcσy / σy” ··· (3) Thus, in the core material 12 formed of the steel material with the 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 material (the lower limit value 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 material planned to use the reference yield strength σy for the core material 12 to the guaranteed value, the correction of the shape of the plasticized part 20 performed in the manufacturing process can be carried out by cutting out the steel material so that the width Wc” of the plasticized part 20 after correction is narrower than the width Wc in the design process. That is, it is possible to avoid the correction of widening the width Wc of the plasticized part 20, and as will be described below, in order to match the axial rigidity to the designed shape, it is possible to avoid the shape correction of increasing the length Lc of the plasticized part 20. This can avoid the problem that the length of the attachment part in the limited overall length of the buckling restraint brace 10 cannot be ensured.

[0026] After changing the width Wc of the plasticized part 20 to Wc”, in order to ensure that the axial rigidity Kc of the plasticized part 20 does not change, Kc = EAc / Lc = EWcT / Lc ··· (4) Kc = EAc” / Lc” = EWc”T / Lc” ··· (5) needs to be satisfied. However, elastic modulus of the core material 12: E Cross-sectional area of the plasticized part 20: Ac = WcT Length of the plasticized part 20: Lc Cross-sectional area of the plasticized portion 20 after correction: Ac” = Wc”T Length of the plasticized portion 20 after correction: Lc” Therefore, it is necessary to change the length Lc of the plasticized portion 20 of the core material 12 in the design process to the length Lc” of the plasticized portion 20 after correction based on the following formula (6). Lc” = LcWc” / Wc ··· (6)

[0027] As a result, 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 plasticized 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.

[0028] Here, in the design process, if the reference yield strength σy is set to the guaranteed value of the steel material planned to be used for the core material 12, the actual yield strength σy” will satisfy the relationship σy < σy” as described above, and the relationship Wc > Wc” will hold from formula (3). Also, the relationship Lc > Lc” will hold from formula (6).

[0029] For this reason, in the design process, if the reference yield strength σy is set to the guaranteed value of the steel material planned to be used for the core material 12, there will be no correction to increase the plate width Wc and the length Lc of the plasticized portion 20 in the core material 12, and the problem of not being able to secure the length of the attachment portion in the limited overall length of the buckling restraint brace 10 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 Lc to Lc” according to the actual yield strength σy” of the delivered steel material.

[0030] Next, a specific example of the design and manufacturing method of the buckling restraint brace 10 in the embodiment will be described based on FIGS. 7 to 9. FIG. 7 is a distribution diagram showing the distribution of the actual yield strength σy” of the steel material assuming that it follows a normal distribution. 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.

[0031] 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”. Furthermore, 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 standard deviation σ of the actual yield strength σy” in that case is considered to set the reference yield strength σy.

[0032] Specifically, at the time of 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) Reference yield strength σy = average value of performance data selected and defined from the setting levels as such.

[0033] 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, during 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 plasticizing part 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, will also increase. 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 plasticizing part 20.

[0034] Here, FIG. 7 shows a plurality of examples of the range in which the shape correction of the plasticizing part 20 is unnecessary 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 indicates the allowable range when the reference yield strength σy is set to a value 2σ lower than the average value of the actual performance data. The allowable range B indicates the allowable range when the reference yield strength σy is set to a value 1σ lower than the average value of the actual performance data. The allowable range C indicates the allowable range when the reference yield strength σy is set to the average value of the actual performance data.

[0035] When the allowable range A is set in the design process, that is, when the reference yield strength σy is set to a value 2σ lower than the average value of the actual performance 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 outside the allowable range A, it is determined that the shape correction of the plasticizing part 20 is necessary. Here, when the reference yield strength σy is set to a value 2σ lower than the average value of the actual performance data, as shown in FIG. 7, if the actual yield strength σy” is outside 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 process. Therefore, the correction of the plasticizing part 20 will reduce the plate width Wc and length Lc of the plasticizing part 20 set at the time of design, so the corresponding correction is easy.

[0036] When the reference yield strength σy is set as 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 plasticized portion 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 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 design time, so the corresponding correction is easy.

[0037] When the reference yield strength σy is set as 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 plasticized portion 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 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 design time, so the corresponding correction is easy.

[0038] Here, when the reference yield strength σy is set as the average value of the actual data - 1σ or when the reference yield strength σy is set as the average value of the actual data, it is probabilistically considered that σy > σy”. To cope with this situation, correction is required to increase the plate width Wc and the length Lc of the plasticized portion 20.

[0039] At this time, when the reference yield strength σy is set as the average value of the actual data - 1σ, that is, when the necessity of correction is judged based on the allowable range B, since the correction amount when increasing the plate width Wc and the length Lc of the plasticized portion 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.

[0040] However, when the reference yield strength σy is set to the average value of the actual data, that is, when determining whether correction is necessary based on the allowable range C, if the actual yield strength σy” is significantly different from the upper or lower limit value of the allowable range C, the correction amount when increasing the plate width Wc and length Lc of the plasticized portion 20 becomes relatively large, making it difficult to appropriately perform shape correction and rendering the steel material with the actual yield strength σy” unusable. Therefore, when emphasizing the yield of steel materials, it is not preferable to set the reference yield strength σy to the average value of the actual data.

[0041] Since JIS standard materials such as SN490, SM490, SN400, and SM400 are generally used for the steel material used for the core material 12, the lower limit value guaranteed by the standard is defined. 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. As a result, since it is statistically inferred that the actual yield strength σy” in many cases will fall within the allowable range, it is possible to increase as much as possible the cases where the shape of the plasticized portion does not need to be corrected.

[0042] Regardless of the above, the reference yield strength σy may be set to the guaranteed value, which is the lower limit value 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 will be equal to or higher than the reference yield strength σy, it is possible to surely suppress the need for correction to increase the plate width Wc and length Lc of the plasticized portion 20.

[0043] Next, a specific example of the design and manufacturing method of the buckling restraint brace 10 of the embodiment will be described based on FIGS. 8 and 9. FIG. 8 is a flowchart for explaining the design process and manufacturing process in the design and manufacturing method of the buckling restraint brace 10 of the embodiment. As shown in Fig. 8, the method for designing and manufacturing the buckling restraint brace 10 includes a design process of setting the design shape of the plasticizing portion 20, and a manufacturing process of manufacturing the plasticizing portion 20 based on the design shape of the plasticizing portion 20 set in the design process and the actual yield strength σy”.

[0044] First, a specific example of setting the design shape of the plasticizing portion 20 in the design process will be described. In the design process, based on the reference yield strength σy of the steel material, the design shape of the plasticizing portion 20 is set so that the yield axial force Ny of the plasticizing portion 20 becomes the target yield axial force. 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 at an appropriate axial force.

[0045] The reference yield strength σy is set, for example, to 1.3 times the guaranteed value of the steel material planned to be used for the core material 12. The guaranteed value is the lower limit of the yield strength guaranteed by the steel material standard. 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 of the yield strength is guaranteed. Therefore, the lower limit of the yield strength guaranteed by the standard is used as the guaranteed value, and the reference yield strength σy is set to 1.3 times the guaranteed value.

[0046] Regardless of the above, the reference yield strength σy may be set, for example, based on the yield strength of the steel material used as the material of the core material 12 in the past. Specifically, the distribution of the actual yield strength σy” is analyzed from the database of the actual yield strength σy” of the steel material used as the material of the core material 12 in the past, and the most frequent value of the obtained distribution is set as the reference yield strength σy, or a value smaller than the most frequent value by a predetermined ratio (for example, 10%) is set as the reference yield strength σy so that the shape correction that widens the width more than the core material 12 of the design shape can be minimized.

[0047] Alternatively, the reference yield strength σy may be set, for example, to 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” falls 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 corresponding correction is easy. The allowable range D is an allowable range in which, when the reference yield strength σy is the guaranteed value of the steel material planned to be used for the core material 12, 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. That is, the allowable range D allows only a range larger than the reference yield strength σy.

[0048] Next, a specific example of manufacturing the plasticized portion 20 in the manufacturing process will be described. In the manufacturing process, the 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 on the mill sheet of the steel material actually used as the core material 12.

[0049] Then, it is determined whether or not the obtained actual yield strength σy” is within the allowable range including the reference yield strength σy. The method of setting the allowable range is as described above. When the actual yield strength σy” falls within the allowable range including the reference yield strength σy, it is determined that correction of the shape of the plasticized portion 20 is unnecessary. That is, the plasticized portion 20 is cut out by a manufacturing apparatus such as a cutting machine to manufacture the core material 12 while maintaining the operation setting of the manufacturing apparatus such as a cutting machine for cutting out the core material 12 from the steel material without changing it from the setting corresponding to the designed shape. On the other hand, when the actual yield strength σy” deviates from the allowable range including the reference yield strength σy, it is determined that correction of the plasticized portion 20 is necessary. That is, the shape of the plasticized portion 20 is corrected so that the yield axial force Ny approaches the target yield axial force. Specifically, in accordance with the corrected shape, the plasticized portion 20 is cut out by a cutting machine or the like to manufacture the core material 12.

[0050] In this embodiment, the correction amount when correcting the shape of the plasticized portion 20 is set stepwise according to the magnitude of the actual yield strength σy”. By this, compared with the case of determining the correction amount each time, the decrease in productivity in the manufacturing process is more efficiently suppressed. Note that in this embodiment, an allowable yield axial force range is set. The allowable yield axial force range is the range of the yield axial force Ny indicated by the plasticized portion 20 of the designed shape, and is the range of the yield axial force Ny corresponding to the allowable range based on the reference yield strength σy. And in the manufacturing process, the shape of the plasticized portion 20 is corrected so that the yield axial force Ny of the plasticized portion 20 of the corrected shape falls within the allowable yield axial force range.

[0051] Next, a specific example of manufacturing the plasticized portion 20 in the manufacturing process will be described in detail with reference to FIG. 9. FIG. 9 is a flowchart for explaining the manufacturing process in the design and manufacturing method of the buckling restraint brace 10 according to the embodiment. The upper limit yield strength in the figure is a value larger than the reference yield strength σy outside the allowable range of the variation of the actual yield strength σy” based on the reference yield strength σy.

[0052] In the manufacturing process, when the actual yield strength σy” is less than or equal to the upper limit yield strength, the shape of the plasticized portion 20 is corrected so that the yield axial force Ny of the plasticized portion 20 of the corrected shape falls within the allowable yield axial force range. On the other hand, when the actual yield strength σy” is greater than the upper limit yield strength, the shape of the plasticized portion 20 is corrected so that the yield axial force Ny of the plasticized portion 20 of the corrected shape becomes the upper limit of the allowable yield axial force range. By this, the correction amount of the plasticized portion 20 is suppressed. Through the above process, the buckling restraint brace 10 according to this embodiment is manufactured.

[0053] As described above, according to the method for designing and manufacturing the buckling restraint brace 10 of the embodiment, as shown in FIGS. 3 and 8, in the design process, the design shape of the plasticizing portion 20 is set based on the reference yield strength σy, which is the yield strength planned for the steel material used for the core material 12, such that the yield axial force Ny of the plasticizing portion 20 becomes the target yield axial force required for the buckling restraint brace 10. The target yield axial force is the target yield axial force required for the buckling restraint brace 10.

[0054] Next, in the manufacturing process, the actual yield strength, which is the yield strength of the steel material actually used for the core material 12, is obtained by the mill sheet or actual measurement of the steel material. And when the actual yield strength σy” is within the allowable range including the reference yield strength σy, the shape of the plasticizing portion 20 is maintained as the design shape. And when the actual yield strength σy” is outside the allowable range, the shape of the plasticizing portion 20 is corrected so that the yield axial force Ny approaches the target yield axial force. Thereby, even if the actual yield strength σy” is different from the reference yield strength σy, as long as the actual yield strength σy” is within the allowable range, the core material 12 can be manufactured in the shape as 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 the decrease in productivity in the manufacturing process can be suppressed.

[0055] Also, if the actual yield strength σy” is outside the allowable range, in the manufacturing process, the shape of the plasticizing portion 20 is corrected, and the yield axial force Ny will approach the target yield axial force. Therefore, the plasticizing portion 20 can be made to yield with an appropriate axial force required for the buckling restraint brace 10.

[0056] Further, when correcting the shape of the plasticizing portion 20 in the manufacturing process, the shape of the plasticizing portion 20 is corrected so that the yield axial force Ny of the plasticizing portion 20 after correction is within the allowable yield axial force range. Here, since the allowable yield axial force range is the range of the yield axial force Ny indicated by the core material 12 of the design shape and is the range of the yield axial force Ny corresponding to the allowable range, by correcting the shape of the plasticizing portion 20, the yield axial force Ny of the core material 12 becomes the yield axial force Ny within the allowable yield axial force range. Thereby, for example, by setting the allowable yield axial force range based on the yield axial force Ny obtained in the buckling restraining brace 10, the plasticizing portion 20 can be made to yield with an appropriate axial force obtained in the buckling restraining brace 10.

[0057] Here, in order to correct the shape of the plasticizing portion 20 so that the yield axial force Ny of the plasticizing portion 20 of the core material 12 approaches the target yield axial force, it is performed by making the plate width Wc of the plasticizing portion 20 different from the width of the design shape. At this time, if the correction amount of the shape of the plasticizing portion 20 is excessively large, for example, the width of the plasticizing portion 20 becomes extremely small, and as a result, the following problems are concerned. First, when the width of the plasticizing portion 20 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. Also, when shortening the length Lc of the plasticizing 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 plasticizing portion 20, the amount of expansion and contraction per unit length Lc of the plasticizing portion 20 when the tensile and compressive axial loads are repeatedly input increases, so that there is a concern about the problem of deterioration of fatigue characteristics. Therefore, in the manufacturing process, when the actual yield strength σy” is less than or equal to the upper yield strength, the shape of the plasticized part 20 is corrected so that the yield axial force Ny of the plasticized part 20 after correction is within the allowable yield axial force range. When the actual yield strength σy” is greater than the upper yield strength, the shape of the plasticized part 20 is corrected so that the yield axial force Ny of the plasticized part 20 after correction becomes the upper limit of the allowable yield axial force range. The upper yield strength is a value greater than the reference yield strength σy outside the allowable range. That is, even if the shape of the plasticized part 20 is corrected, it is possible to prevent the correction amount from becoming excessively large. Therefore, the above-mentioned problems can be prevented from occurring.

[0058] Further, when the actual yield strength σy” is outside the allowable range, that is, the correction amount when correcting the shape of the plasticized part 20 is set step by step according to the magnitude of the actual yield strength σy”. Thereby, for example, compared with the case where the correction amount of the plasticized part 20 is proportional to the magnitude of the difference between the actual yield strength σy” and the reference yield strength σy, the frequency of changing the operation settings of manufacturing equipment such as a cutting machine can be reduced, and a decrease in productivity in the manufacturing process can be suppressed more efficiently.

[0059] Also, the reference yield strength σy is set to a value 1.3 times the guaranteed value of the steel material planned to be used for the core material 12. Thereby, since it is statistically estimated that the actual yield strength σy” will fall within the allowable range in many cases, it is possible to increase the number of cases where the shape of the plasticized part 20 does not need to be corrected as much as possible.

[0060] Also, the reference yield strength σy is set based on the yield strength of the steel material used as the material for the core material 12 in the past. Thereby, an appropriate reference yield strength σy is set based on past performance so that the actual yield strength σy” will fall within the allowable range in many cases. Therefore, it is possible to increase the number of cases where the shape of the plasticized part 20 does not need to be corrected as much as possible.

[0061] Here, depending on the actual yield strength σy", there are cases where the actual yield strength σy" is smaller than the lower limit value of the allowable range. In such cases, in order to make the yield axial force Ny of the plasticized part 20 approach the target yield axial force, a correction is made to widen the plate width Wc of the plasticized part 20 to be wider than the width of the designed shape. In order to match the axial rigidity K of the core material 12 with the widened plate width Wc to the axial rigidity K of the core material 12 of the designed shape, it is necessary to increase the length Lc of the plasticized part 20. This causes, for example, the length L2 of the attachment parts 16 at both ends required for attachment to be insufficient in the buckling restraint brace 10 whose overall length is limited according to the structural dimensions to which the buckling restraint brace 10 is attached, which is not preferable. Therefore, the reference yield strength σy is set to the guaranteed value of the steel material planned to be used for the core material 12. Thereby, since it is possible to prevent the actual yield strength σy" from falling below the reference yield strength σy, it is possible to avoid the actual yield strength σy" from becoming smaller than the lower limit value of the allowable range. Therefore, it is possible to avoid the correction of widening the width of the plasticized part 20. Thereby, it is possible to suppress the occurrence of the above-described problem.

[0062] Also, in the manufacturing process, the yield strength 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".

[0063] Note that the technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

[0064] In addition, within the scope not departing from the spirit of the present invention, it is possible to appropriately replace the components in the above-described embodiment with well-known components, and the above-described modification examples may be appropriately combined.

Explanation of Reference Numerals

[0065] 1 Building 2 Column 4 Beam Member 6 Intersection 10 Buckling restraint brace 12 Core material 13 Mortar 14 Steel pipe 16 Mounting part 18 Elastic part 20 Plasticized part A Allowable range B Allowable range C Allowable range D Allowable range Wc Plate width 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 that is narrower in width at the central portion in the longitudinal direction than the portions other than the central portion, 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, so that the yield axial force of the plasticized portion becomes the target yield axial force, the design shape of the plasticized portion is set. The manufacturing process includes obtaining the actual yield strength, which is the yield strength of the steel material actually used for the core material. When the actual yield strength is within the allowable range including the reference yield strength, the shape of the plasticized portion is maintained as the design shape. When the actual yield strength is outside the allowable range, the shape of the plasticized portion is corrected so that the yield axial force approaches the target yield axial force. A method for designing and manufacturing a buckling-restrained brace, characterized by the above.

2. The range of the yield axial force indicated by the core material of the design shape and corresponding to the allowable range is defined as the allowable yield axial force range. In the manufacturing process, the shape of the plasticized portion is corrected so that the yield axial force of the plasticized portion of the corrected shape is within the range of the allowable yield axial force range. The method for designing and manufacturing a buckling-restrained brace according to Claim 1, characterized by the above.

3. When the reference yield strength is exceeded and the value greater than the reference yield strength is defined as the upper limit yield strength. In the manufacturing process, when the actual yield strength 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 of the corrected shape is within the range of the allowable yield axial force range. When the actual yield strength is greater than the upper limit yield strength, the shape of the plasticized portion is corrected so that the yield axial force of the plasticized portion of the corrected shape becomes the upper limit of the allowable yield axial force range. The method for designing and manufacturing a buckling-restrained brace according to Claim 2, characterized by the above.

4. In the manufacturing process, the correction amount when correcting the shape of the plasticized portion is set stepwise according to the magnitude of the actual yield strength. The method for designing and manufacturing a buckling-restrained brace according to any one of Claims 1 to 3, characterized by the above.

5. In the design process, the reference yield strength is set to a value that is 1.3 times the guaranteed value guaranteed by the specifications for the steel material planned to be used for the core material. The method for designing and manufacturing a buckling-restrained brace according to any one of Claims 1 to 3, characterized by the above.

6. ​ ​ In the said design process, the said reference yield strength is set based on the yield strength of the steel material that has been used as the material of the said core material in the past. The method for designing and manufacturing a buckling-restrained brace according to any one of claims 1 to 3, characterized in that.

7. In the said design process, the said reference yield strength is set to the guaranteed value guaranteed by the standard for the steel material planned to be used for the said core material. The method for designing and manufacturing a buckling-restrained brace according to any one of claims 1 to 3, characterized in that.

8. In the said manufacturing process, the yield strength of the steel material actually used for the said core material is measured actually to obtain the said actual yield strength, or the said actual yield strength is obtained from the value described in the mill sheet for the said steel material. The method for designing and manufacturing a buckling-restrained brace according to any one of claims 1 to 3, characterized in that.

Images