Design method of buckling-restrained brace based on mechanical property parameters

Abstract

The invention discloses a buckling-restrained brace design method based on mechanical property parameters, and relates to the field of anti-seismic component design method.The buckling-restrained brace design method comprises the following steps that the lengths and section sizes of an energy dissipation section, a transition section and a connecting section of a buckling-restrained brace are calculated according to the mechanical property parameters of the buckling-restrained brace in an actual structure; calculating the section size of the constraint steel sleeve according to an elastic stability theory; the wall thickness of the constraint steel sleeve is calculated according to the local stability theory, and the strength grade of the concrete filler is determined; determining the width-to-thickness ratio of the section of the connecting section according to a torsion instability theory; calculating the thickness of the unbonded material according to the Poisson effect when the energy consumption unit is pressed; the series stiffness of the connecting section, the transition section and the energy consumption section of the energy consumption unit is calculated, and the consistency of the series stiffness and the actual elastic stiffness of the buckling-restrained brace is checked. According to the method, the performance-based parameterized design of the buckling-restrained brace product can be realized according to the mechanical property parameters of the buckling-restrained brace provided by a structure engineer.

Description

Technical Field

[0001] The present invention relates to the field of seismic component design methods, and particularly to a design method for a buckling-restrained brace based on mechanical property parameters. Background Art

[0002] With the continuous development of industrialized towns and the increasing demand for the seismic performance of modern buildings, reducing the damage suffered by buildings under earthquake action and mitigating the losses to public life safety and property have become a primary task in contemporary engineering structure design.

[0003] Currently, the seismic design of building structures generally adopts increasing the damping of the structure or setting up isolation layers to reduce the energy input of the earthquake to the structure. Traditional buckling-restrained brace components mainly consist of an internal core material, an external restraint member, a non-bonding expandable material, and a non-bonding slip interface, and are connected between the beams and columns of the main structure. Under strong earthquake action, the buckling-restrained brace undergoes plastic deformation, having good hysteretic energy dissipation capacity and ductile deformation capacity, and can significantly reduce the damage degree of the main structure under earthquake action.

[0004] However, the current buckling-restrained brace components lack a systematic and effective design method, resulting in the buckling-restrained brace being difficult to exert the expected energy dissipation and shock absorption effect under strong earthquake action, and its function of protecting the main structure is difficult to achieve, thus unable to effectively improve the seismic performance of the structure. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a design method for a buckling-restrained brace based on mechanical property parameters. The method of the present invention systematically and comprehensively proposes a method for the structural design and calculation of the buckling-restrained brace, and the designed buckling-restrained brace meets the structural mechanical property parameters, thereby effectively exerting the damper function under actual earthquake action and being able to effectively dissipate earthquake energy after reaching the yield deformation to prevent the damage of buildings.

[0006] In order to achieve the above technical effects, the present invention is realized through the following technical solutions: A design method for a buckling-restrained brace based on mechanical property parameters, comprising the following steps: S1. Design the lengths and cross-sectional dimensions of the energy dissipation section, transition section, and connection section of the buckling-restrained brace according to the requirements of the seismic mechanical property parameters of the buckling-restrained brace in the building; S2. Calculate the cross-sectional dimensions of the restraint steel sleeve according to the elastic stability theory; S3. Calculate the wall thickness of the restraint steel sleeve and determine the strength grade of the concrete filling material according to the local stability theory; S4. Determine the cross-sectional width-to-thickness ratio of the connection section according to the torsional instability theory, and calculate the minimum width of the restraint steel sleeve of the buckling-restrained brace according to the Euler stability theory; S5. Calculate the thickness of the unbonded material according to the Poisson's effect when the energy dissipation unit is under compression; S6. Calculate the series stiffness of the three parts of the energy dissipation unit, namely the connection section, the transition section, and the energy dissipation section, and check the consistency between the series stiffness and the actual elastic stiffness of the buckling restraining brace; S7. Check the consistency between the yield displacement of the buckling restraining brace corresponding to the equivalent series stiffness and the actual yield displacement, and check the ultimate deformation capacity of the buckling restraining brace.

[0007] Furthermore, a design method for a buckling restraining brace based on mechanical property parameters includes the following steps: S1. Design the lengths and cross-sectional dimensions of the energy dissipation section, the transition section, and the connection section of the buckling restraining brace according to the requirements of the seismic mechanical property parameters of the buckling restraining brace in the building, which specifically includes the following steps: S11. Calculate the cross-sectional area of the energy dissipation section of the buckling restraining brace according to the yield bearing capacity of the buckling restraining brace: : (1); In the formula η is the overstrength coefficient of the steel, that is, the ratio of the actual yield strength of the steel to the nominal yield strength, is the nominal yield strength of the steel; S12. Calculate the length of the energy dissipation section of the buckling restraining brace according to the yield displacement of the buckling restraining brace: : (2); In the formula, is the nominal yield strain of the steel, and the value range of λ is 0.65 - 0.75; S13. Calculate the length of the transition section of the buckling restraining brace , and the value is 3% - 5% of the total length L of the buckling restraining brace, that is , and the value range of α is 0.03 - 0.05; S14. Calculate the length of the connection section of the buckling restraining brace , and this length is the total length L of the brace minus the length of the energy dissipation section of the brace calculated in S12 and minus twice the length of the transition section calculated in S13, that is: S15. Calculate the cross-sectional area of the connection section of the buckling restraining brace , the elastic connection section of the buckling-restrained brace is always in the elastic working state. Therefore, the stress under the ultimate bearing capacity of the brace should be less than the yield strength of the steel , and thus the minimum cross-sectional area requirement of the connection section of the buckling-restrained brace can be determined: (4) In the formula, is the strain hardening adjustment coefficient of the steel; S2. Calculate the cross-sectional dimensions of the restraining steel casing according to the elastic stability theory. Specifically: According to the ultimate displacement of the buckling-restrained brace calculate the length of the restraining steel casing , the length of the restraining steel casing must ensure the normal movement of the buckling-restrained brace under the ultimate compression deformation and still effectively restrain the energy dissipation section and the transition section under the ultimate tensile deformation. Thus, the length of the restraining steel casing can be calculated as: (5); S3. Calculate the wall thickness of the restraining steel casing according to the local stability theory and determine the strength grade of the concrete filling material. Specifically: The buckling-restrained brace should not exhibit local instability during operation to ensure its stable hysteretic energy dissipation capacity. This requires that the wall thickness of the restraining steel casing of the buckling-restrained brace should not be too small, and the strength grade of the filled concrete is taken as C30. Calculate the minimum wall thickness of the restraining steel casing of the buckling-restrained brace : (6); In the formula, is the standard value of the compressive strength of the concrete in the restraining steel casing, is the design value of the yield strength of the steel, is the width of the energy dissipation section; S4. Determine the section width-thickness ratio of the connection section according to the torsional instability theory, and calculate the minimum width of the restraining steel casing of the buckling-restrained brace according to the Euler stability theory : (7); In the formula, is the elastic modulus of the steel; S5. Calculate the thickness of the unbonded material according to the Poisson effect when the energy dissipation unit is compressed. The thickness of the unbonded material layer is calculated by the following formula: (8); In the formula, is the Poisson's ratio of the steel; S6. Calculate the series stiffness of the three parts of the energy dissipation unit connection section, transition section, and energy dissipation section, and check the consistency between the series stiffness and the actual elastic stiffness of the buckling-restrained brace. Specifically, it includes the following steps: S61. Calculate the axial stiffness of the buckling-restrained brace connection section, transition section, and energy dissipation section. , , ; (9); (10); (11); S62. Calculate the equivalent axial series stiffness of the buckling-restrained brace according to the stiffness series principle. : (12); S63. Check whether the actual axial stiffness and actual yield displacement of the designed buckling-restrained brace are consistent with the given theoretical elastic stiffness and theoretical yield displacement, that is, whether the following two formulas are satisfied. If the following two formulas are not satisfied, adjust the steel grade or modify the connection section length and then recalculate the equivalent axial series stiffness of the brace until the following two formula requirements are met: , until the following two formula requirements are met: (13); (14); S7. Check the consistency between the yield displacement corresponding to the equivalent series stiffness of the buckling-restrained brace and the actual yield displacement, and check the ultimate deformation capacity of the buckling-restrained brace; for the check of the ultimate deformation capacity of the buckling-restrained brace, the maximum strain value of the energy dissipation section of the buckling-restrained brace should not exceed 0.03 to ensure the stable exertion of its hysteretic energy dissipation capacity, that is, the strain value of the buckling-restrained brace under the ultimate displacement should satisfy the following formula; if the following formula is not satisfied, reduce the length of the connection section and then recheck until the following formula requirements are met: (15).

[0008] Further, the cross-sectional form of the energy dissipation section of the buckling-restrained brace is "one-shaped" or "cross-shaped", and the thickness takes values of 10 mm to 80 mm; for the "one-shaped" cross-section, the cross-sectional width , takes values of 10 - 20; for the "cross-shaped" cross-section, the cross-sectional width , takes values of 5 - 10; after calculating according to the method of step S1, the cross-sectional width and thickness of the corresponding energy dissipation section of the buckling-restrained brace can be determined; in step S1, takes values related to the steel grade. For Q235 steel, takes 1.25, and for Q190 steel, Take 1.15 when the steel grade does not exceed 160, take 1.10.

[0009] Furthermore, in the step S12, the nominal yield strain of the steel is calculated by the following formula: (16).

[0010] Furthermore, in the step S15, the cross-sectional form of the connecting section of the buckling-restrained brace is "cross-shaped", and the cross-sectional thickness of the connecting section is the same as that of the energy dissipation section, that is , after calculating by the method of step 5, the out-of-plane free width of the cross-section of the connecting section can be calculated , and the torsional local stability of the connecting section is checked by the following formula: (17).

[0011] Furthermore, in the step S15, the strain hardening adjustment coefficient of the steel is related to the steel grade. For Q235 steel and Q190 steel take 1.5. When the steel grade does not exceed 160, take 2.0.

[0012] Furthermore, in the step S5, the Poisson's ratio of the steel is taken as 0.3.

[0013] Furthermore, the actual axial stiffness K e of the buckling-restrained brace calculated in the step S73 K s is larger than the theoretical axial stiffness. When the error exceeds 5%, steel with a larger grade can be selected or the length of the energy dissipation section can be reduced. Conversely, steel with a smaller grade can be selected or the length of the energy dissipation section can be increased until the error between the two does not exceed 5%.

[0014] At the same time, the present invention also discloses a computer system, which includes the above design method and can directly design the buckling-restrained brace based on the mechanical performance parameters.

[0015] The beneficial effects of the present invention are as follows: The method of the present invention systematically and comprehensively proposes the structural design and calculation method of the buckling-restrained brace, and at the same time innovatively proposes the length L c of the energy dissipation section of the buckling-restrained brace, L r the length of the restraint steel casing, b r, the concept and calculation method of the thickness of the unbonded material layer are proposed. A verification method for whether the actual axial stiffness and actual yield displacement of the buckling-restrained brace are consistent with the given theoretical elastic stiffness and theoretical yield displacement, and a method for checking the ultimate deformation capacity of the buckling-restrained brace are presented. The buckling-restrained brace designed by this method meets the structural mechanical property parameters, so as to quickly enter the buckling deformation stage during an actual earthquake and fail after reaching the yield strength to prevent the failure of building components. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for describing the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0017] Figure 1 is the front assembly view of the straight-shaped inner core buckling-restrained brace in Embodiment 1; Figure 2 is the top assembly view of the straight-shaped inner core buckling-restrained brace in Embodiment 1; Figure 3 is the processing drawing of the energy dissipation core plate of the straight-shaped inner core buckling-restrained brace in Embodiment 1; Figure 4 is the processing drawing of the stiffening rib of the end connection section of the straight-shaped inner core buckling-restrained brace in Embodiment 1; Figure 5 is the processing drawing of the restraint steel sleeve of the straight-shaped inner core buckling-restrained brace in Embodiment 1; Figure 6 is of Embodiment 1 Figure 1 sectional view 1-1; Figure 7 is of Embodiment 1 Figure 1 sectional view 2-2; Figure 8 is the assembly drawing of the cross-shaped inner core buckling-restrained brace in Embodiment 2; Figure 9 is the processing drawing of the main core plate of the energy dissipation inner core of the cross-shaped inner core buckling-restrained brace in Embodiment 2; Figure 10 is the processing drawing of the auxiliary core plate of the energy dissipation inner core of the cross-shaped inner core buckling-restrained brace in Embodiment 2; Figure 11 is the processing drawing of the restraint steel sleeve of the cross-shaped inner core buckling-restrained brace in Embodiment 2; Figure 12 is of Embodiment 2 Figure 8 sectional view 3-3; Figure 13 is of Embodiment 2 Figure 8 sectional view 4-4. Detailed implementation manners

[0018] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0019] A design method of a buckling-restrained brace based on mechanical property parameters provided by the present invention is characterized by comprising the following steps: S1. Design the lengths and cross-sectional dimensions of the energy dissipation section, transition section, and connection section of the buckling-restrained brace according to the requirements of the seismic mechanical property parameters of the buckling-restrained brace in the building, specifically including the following steps: S11. Calculate the cross-sectional area of the energy dissipation section of the buckling-restrained brace according to the yield bearing capacity of the buckling-restrained brace: : (1); In the formula η is the super-strength coefficient of the steel, that is, the ratio of the actual yield strength of the steel to the nominal yield strength, is the nominal yield strength of the steel; S12. Calculate the length of the energy dissipation section of the buckling-restrained brace according to the yield displacement of the buckling-restrained brace: : (2); In the formula, is the nominal yield strain of the steel, and the value range of λ is 0.65 - 0.75; S13. Calculate the length of the transition section of the buckling-restrained brace , and the value is 3% - 5% of the total length L of the buckling-restrained brace, that is , and the value range of α is 0.03 - 0.05; S14. Calculate the length of the connection section of the buckling-restrained brace , and this length is the total length L of the brace minus the length of the energy dissipation section of the brace calculated in S12 and minus twice the length of the transition section calculated in S13, that is: S15. Calculate the cross-sectional area of the connection section of the buckling-restrained brace , the elastic connection section of the buckling-restrained brace is always in the elastic working state. Therefore, the stress under the ultimate bearing capacity of the brace should be less than the yield strength of the steel , and thus the minimum cross-sectional area requirement of the connection section of the buckling-restrained brace can be determined: (4); In the formula, is the strain hardening adjustment coefficient of the steel; S2. Calculate the cross-sectional dimensions of the restraining steel casing according to the elastic stability theory. Specifically: According to the ultimate displacement of the buckling-restrained brace, calculate the length of the restraining steel casing. The length of the restraining steel casing must ensure the normal movement of the buckling-restrained brace under the ultimate compression deformation and still effectively restrain the energy dissipation section and the transition section under the ultimate tensile deformation. Thus, the length of the restraining steel casing can be calculated as: (5); S3. Calculate the wall thickness of the restraining steel casing and determine the strength grade of the concrete filling material according to the local stability theory. Specifically: The buckling-restrained brace should not exhibit local buckling during operation to ensure its stable hysteretic energy dissipation capacity. This requires that the wall thickness of the restraining steel casing of the buckling-restrained brace should not be too small. The strength grade of the filled concrete is taken as C30. Calculate the minimum wall thickness of the restraining steel casing of the buckling-restrained brace according to the local stability theory: (6); In the formula, is the standard value of the compressive strength of the concrete in the restraining steel casing, is the design value of the yield strength of the steel, is the width of the energy dissipation section; S4. Determine the section width-to-thickness ratio of the connection section according to the torsional buckling theory, and calculate the minimum width of the restraining steel casing of the buckling-restrained brace according to the Euler stability theory: (7); In the formula, is the elastic modulus of the steel; S5. Calculate the thickness of the unbonded material according to the Poisson effect when the energy dissipation unit is compressed. The thickness of the unbonded material layer is calculated as follows: (8); In the formula, is the Poisson's ratio of the steel; S6. Calculate the series stiffness of the three parts of the energy dissipation unit connection section, transition section, and energy dissipation section, and check the consistency between the series stiffness and the actual elastic stiffness of the buckling-restrained brace. Specifically, it includes the following steps: S61. Calculate the axial stiffness of the buckling restraint brace connection section, transition section, and energy dissipation section , , ; (9); (10); (11); S62. Calculate the equivalent axial series stiffness of the buckling restraint brace according to the principle of stiffness series connection : (12); S63. Check whether the actual axial stiffness and actual yield displacement of the designed buckling restraint brace are consistent with the given theoretical elastic stiffness and theoretical yield displacement, that is, whether the following two formulas are satisfied. If the following two formulas are not satisfied, adjust the steel grade or modify the connection section length and then recalculate the equivalent axial series stiffness of the support , until the following two formula requirements are met: (13); (14); S7. Check the consistency between the yield displacement corresponding to the equivalent series stiffness of the buckling restraint brace and the actual yield displacement, and check the ultimate deformation capacity of the buckling restraint brace; for the ultimate deformation capacity check of the buckling restraint brace, the maximum strain value of the energy dissipation section of the buckling restraint brace should not exceed 0.03 to ensure the stable exertion of its hysteretic energy dissipation capacity, that is, the strain value of the buckling restraint brace under the ultimate displacement should satisfy the following formula; if the following formula is not satisfied, reduce the length of the connection section and then recalculate until the following formula requirements are met: (15).

[0020] In this embodiment, the cross-sectional form of the energy dissipation section of the buckling restraint brace is "one - shaped" or "cross - shaped", and the thickness takes values from 10 mm to 80 mm; for the "one - shaped" cross - section, the cross - sectional width of the energy dissipation section , takes values from 10 to 20; for the "cross - shaped" cross - section, the cross - sectional width of the energy dissipation section , takes values from 5 to 10; after calculating by the method of step S1, the specific sizes of the cross - sectional width and thickness of the corresponding energy dissipation section of the buckling restraint brace can be determined; in step S1 the value of is related to the steel grade. For Q235 steel Take 1.15. When the steel grade does not exceed 160, take 1.10.

[0021] In this embodiment, in the step S12, The nominal yield strain of the steel is calculated by the following formula: (16).

[0022] In this embodiment, in the step S15, the cross-sectional form of the connection section of the buckling-restrained brace is "cross-shaped", and the cross-sectional thickness of the connection section is the same as that of the energy dissipation section, that is , after calculating according to the method in step 5, the out-of-plane free width of the cross-section of the connection section can be calculated , and the torsional local stability of the connection section is checked by the following formula: (17).

[0023] In this embodiment, in the step S15, the strain hardening adjustment coefficient of the steel is related to the steel grade. For Q235 steel and Q190 steel take 1.5. When the steel grade does not exceed 160, take 2.0.

[0024] In this embodiment, in the step S5, the Poisson's ratio of the steel is taken as 0.3.

[0025] In this embodiment, the actual axial stiffness K e of the buckling-restrained brace calculated in the step S73 K s is larger than the theoretical axial stiffness. When the error exceeds 5%, steel with a larger grade can be selected or the length of the energy dissipation section can be reduced. On the contrary, steel with a smaller grade can be selected or the length of the energy dissipation section can be increased until the error between the two does not exceed 5%.

[0026] At the same time, the present invention also discloses a computer system, which includes the above design method and can directly design the buckling-restrained brace based on the mechanical property parameters.

[0027] The effectiveness of the present design method is further verified by the following specific design process: Example 1

[0028] In this example, the cross-sectional form of the energy dissipation section of the buckling-restrained brace is "one-shaped": In a certain actual engineering project, the mechanical property parameters of the buckling-restrained brace provided by the structural engineer are as follows in the table: Brace model <![CDATA[Yield bearing capacity F Y (kN)]]> <![CDATA[Yield displacement U Y (mm)]]> <![CDATA[Elastic stiffness K s (kN / mm)]]> <![CDATA[Ultimate displacement U max (mm)]]> Brace length (mm) BRB 2500 5.5 455 14.4 3500 Step 1: Select Q355 steel for the design of the buckling-restrained brace energy dissipation component, that is f . Then the cross-sectional area of the energy dissipation section of the buckling-restrained brace is:

[0029] Take the thickness of the energy dissipation section , then the width of the energy dissipation section .

[0030] Step 2: Among the given design parameter conditions, the yield displacement of the buckling-restrained brace , then the length of the energy dissipation section of the buckling-restrained brace is:

[0031] Step 3: The length of the transition section of the buckling-restrained brace is taken as 4% of the total length of the brace, that is

[0032] Step 4 The length of the connection section of the buckling-restrained brace is the total length of the brace L minus the length of the energy dissipation section of the brace calculated in Step 2 and minus twice the length of the transition section calculated in Step 3 , that is:

[0033] Step 5: The connection section of the buckling-restrained brace is always in the elastic working state under the elastic working state, and its stress under the ultimate bearing capacity of the brace should be less than the yield strength of the steel , the minimum cross-sectional area of the connection section of the buckling-restrained brace is: , take the cross-sectional area of the connection section as 2.2 times the cross-sectional area of the energy dissipation section , that is , meeting the requirement.

[0034] Step 6: Calculate the length of the constraint steel casing according to the ultimate displacement of the buckling-restrained brace . The length of the constraint steel casing must ensure the normal movement of the buckling-restrained brace under the ultimate compression deformation and still effectively constrain the energy dissipation section and the transition section under the ultimate tensile deformation. The length of the constraint steel casing is: , round up, that is, take .

[0035] Step 7: The buckling-restrained brace should not exhibit local buckling during operation to ensure its stable hysteretic energy dissipation capacity. It is required that the wall thickness of the steel casing restraining the buckling-restrained brace should not be too small, and the strength grade of the filled concrete is taken as C30. Calculate the minimum wall thickness of the steel casing restraining the buckling-restrained brace according to the local stability theory. : , rounded up, that is, take Step 8: The buckling-restrained brace should not exhibit overall buckling during operation to ensure its sufficient stable bearing capacity and hysteretic energy dissipation capacity. Calculate the minimum width of the steel casing restraining the buckling-restrained brace according to Euler's stability theory. :

[0036] When takes the value of 370 mm, , the calculation result meets the requirements of the flexural stiffness.

[0037] Step 9: When the buckling-restrained brace is subjected to an axial compression load, the energy dissipation section will produce axial compression deformation. Due to the Poisson effect, lateral expansion will occur simultaneously. The space for this expansion deformation is provided by the unbonded layer pasted on the surface of the energy dissipation component of the buckling-restrained brace. The thickness of the unbonded material layer cannot be too large, otherwise the buckling deformation curvature of the energy dissipation section of the buckling-restrained brace is relatively large, thereby reducing the fatigue life of the buckling-restrained brace. The thickness of the unbonded material layer is: , rounded up, that is, take .

[0038] Step 10: Calculate the axial stiffness of the connection section, transition section and energy dissipation section of the buckling-restrained brace , , :

[0039] Step 11: Calculate the equivalent axial series stiffness of the buckling-restrained brace according to the stiffness series principle :

[0040] Step 12: Check whether the actual axial stiffness and actual yield displacement of the designed buckling-restrained brace are consistent with the given theoretical elastic stiffness and theoretical yield displacement, that is: Both are less than 5%, and the verification result meets the requirements.

[0041] Step 13: Check the ultimate deformation capacity of the buckling - restrained brace. The maximum strain value of the energy - dissipating section of the buckling - restrained brace should not exceed 0.03 to ensure the stable exertion of its hysteretic energy - dissipation capacity. That is, the strain value of the buckling - restrained brace under the ultimate displacement should satisfy: The calculated result is less than 3%, and the verification result meets the requirements.

[0042] Check the torsional stability of the extended connection section of the buckling - restrained brace: The cross - section thickness of the connection section of the buckling - restrained brace , the extended free width of the connection section . And check the torsional local stability of the connection section according to the following formula: , 8.35 < 10.58, the verification result meets the requirements, and torsional instability will not occur.

[0043] Finally, according to the calculation results, the structural design drawing of the buckling - restrained brace is shown in Figure 1 - 7. Embodiment 2

[0044] In this embodiment, the cross - section form of the energy - dissipating section of the buckling - restrained brace is "cross - shaped": In a certain actual engineering project, the mechanical property parameters of the buckling - restrained brace provided by the structural engineer are as follows in the table: Brace model <![CDATA[Yield bearing capacity F Y (kN)]]> <![CDATA[Yield displacement U Y (mm)]]> <![CDATA[Elastic stiffness K s (kN / mm)]]> <![CDATA[Ultimate displacement U max (mm)]]> Brace length (mm) BRB 2000 5.7 351 24 4300 Calculate the processing parameters of the buckling - restrained brace product according to the steps in Claim 1: Step 1: Select Q235 steel for the design of the energy - dissipating component of the buckling - restrained brace, that is . Then the cross - section area of the energy - dissipating section of the buckling - restrained brace is:

[0045] Take the thickness of the energy - dissipating section , then the width of the energy - dissipating section .

[0046] Step 2: Among the given design parameter conditions, the yield displacement of the buckling - restrained brace , then the length of the energy - dissipating section of the buckling - restrained brace is:

[0047] Step 3: The length of the transition section of the buckling - restrained brace is taken as 4% of the total length of the brace, that is

[0048] Step 4 The length of the connection section of the buckling - restrained brace Total length for support L Subtract the length of the energy-dissipating section of the support calculated in Step 2 And subtract twice the length of the transition section calculated in Step 3 , that is:

[0049] Step 5: The connection section of the buckling-restrained brace is always in the elastic working state under the elastic working state of the brace. The stress under the ultimate bearing capacity of the support should be less than the yield strength of the steel , the minimum cross-sectional area of the connection section of the buckling-restrained brace is: , take the cross-sectional area of the connection section to be 2.2 times the cross-sectional area of the energy-dissipating section , that is , satisfying requirements.

[0050] Step 6: Calculate the length of the restraining steel casing according to the ultimate displacement of the buckling-restrained brace , the length of the restraining steel casing must ensure the normal movement of the buckling-restrained brace under the ultimate compressive deformation and still effectively restrain the energy-dissipating section and the transition section under the ultimate tensile deformation. The length of the restraining steel casing is: , round up, that is, take .

[0051] Step 7: The buckling-restrained brace should not exhibit local buckling during operation to ensure its stable hysteretic energy-dissipating capacity. It is required that the wall thickness of the restraining steel casing of the buckling-restrained brace should not be too small, and the strength grade of the filled concrete is taken as C30. Calculate the minimum wall thickness of the restraining steel casing of the buckling-restrained brace according to the local stability theory : , round up, that is, take .

[0052] Step 8: The buckling-restrained brace should not exhibit overall buckling during operation to ensure its sufficient stable bearing capacity and hysteretic energy-dissipating capacity. Calculate the minimum width of the restraining steel casing of the buckling-restrained brace according to the Euler stability theory :

[0053] When takes the value of 400 mm, , satisfying the requirements of the flexural stiffness.

[0054] ​Step 9: When the buckling-restrained brace is subjected to an axial compression load, axial compression deformation will occur in the energy dissipation section. Due to the Poisson effect, lateral expansion will simultaneously occur, and the space for this expansion deformation is provided by the unbonded layer pasted on the surface of the energy dissipation component of the buckling-restrained brace. The thickness of the unbonded material layer cannot be too large, otherwise the buckling deformation curvature of the energy dissipation section of the buckling-restrained brace will be relatively large, thereby reducing the fatigue life of the buckling-restrained brace. The thickness of the unbonded material layer is: , rounded up, that is, take .

[0055] Calculate the axial stiffness of the connection section, transition section, and energy dissipation section of the buckling-restrained brace , , :

[0056] Step 11: Calculate the equivalent axial series stiffness of the buckling-restrained brace according to the stiffness series principle :

[0057] Step 12: Check whether the actual axial stiffness and actual yield displacement of the designed buckling-restrained brace are consistent with the given theoretical elastic stiffness and theoretical yield displacement, that is: Both are less than 5%, and the check result meets the requirements.

[0058] The check result meets the requirements.

[0059] Step 13: Check the ultimate deformation capacity of the buckling-restrained brace. The maximum strain value of the energy dissipation section of the buckling-restrained brace should not exceed 0.03 to ensure the stable exertion of its hysteretic energy dissipation capacity, that is, the strain value of the buckling-restrained brace under the ultimate displacement should satisfy: The calculation result is less than 3%, and the check result meets the requirements.

[0060] Check the torsional stability of the extended connection section of the buckling-restrained brace: The cross-sectional thickness of the connection section of the buckling-restrained brace , and the extended free width of the connection section . And check the torsional local stability of the connection section according to the following formula: , ,

[0061] The verification result meets the requirements, and torsional instability will not occur.

[0062] The finally obtained design structure diagram of the buckling-restrained brace is shown in Figure 8-13.

[0063] In the description of this specification, the descriptions referring to the terms "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

Claims

1. A design method of a buckling-restrained brace based on mechanical property parameters, characterized in that, Including the following steps: S1. Design the lengths and cross-sectional dimensions of the energy dissipation section, transition section, and connection section of the buckling-restrained brace according to the requirements of the seismic mechanical property parameters of the buckling-restrained brace in the building; S2. Calculate the cross-sectional dimension of the restraint steel sleeve according to the elastic stability theory; S3. Calculate the wall thickness of the restraint steel sleeve and determine the strength grade of the concrete filling material according to the local stability theory; S4. Determine the width-thickness ratio of the cross-section of the connection section according to the torsional instability theory, and calculate the minimum width of the restraint steel sleeve of the buckling-restrained brace according to the Euler stability theory; S5. Calculate the thickness of the unbonded material according to the Poisson effect when the energy dissipation unit is compressed; S6. Calculate the series stiffness of the connection section, transition section, and energy dissipation section of the energy dissipation unit, and check the consistency between the series stiffness and the actual elastic stiffness of the buckling-restrained brace; S7. Check the consistency between the yield displacement of the buckling-restrained brace corresponding to the equivalent series stiffness and the actual yield displacement, and check the ultimate deformation capacity of the buckling-restrained brace.

2. The design method of a buckling-restrained brace based on mechanical property parameters according to claim 1, characterized in that, Including the following steps: S1. Design the lengths and cross-sectional dimensions of the energy dissipation section, transition section, and connection section of the buckling-restrained brace according to the requirements of the seismic mechanical property parameters of the buckling-restrained brace in the building, specifically including the following steps: S11. Calculate the cross-sectional area of the energy dissipation section of the buckling-restrained brace according to the yield bearing capacity of the buckling-restrained brace :​ （1）； In the formula η is the overstrength coefficient of steel, that is, the ratio of the actual yield strength of steel to the nominal yield strength, is the nominal yield strength of steel; S12. Calculate the length of the energy dissipation section of the buckling-restrained brace based on the yield displacement of the buckling-restrained brace :​ （2）； In the formula, the nominal yield strain of the steel, where the value range of λ is 0.65 - 0.75; S13. Calculate the length of the transition section of the buckling-restrained brace , with a value of 3% - 5% of the total length of the buckling-restrained brace L , that is , where the value range of α is 0.03 - 0.05; S14. Calculate the length of the connection section of the buckling-restrained brace , which is the total length of the brace L minus the length of the energy-dissipation section of the brace calculated in S12 and minus twice the length of the transition section calculated in S13 , that is: （3）； S15. Calculate the cross-sectional area of the buckling-restrained brace connection segment The elastic connection segment of the buckling-restrained brace is always in the elastic working state. Therefore, its stress under the ultimate bearing capacity of the brace should be less than the yield strength of the steel Thus, the minimum cross-sectional area requirement of the buckling-restrained brace connection segment can be determined as follows: （4）； In the formula, is the strain strengthening adjustment coefficient of steel; S2. Calculate the cross-sectional dimensions of the constrained steel casing according to the elastic stability theory, specifically: according to the ultimate displacement of the buckling restraining brace calculate the length of the constrained steel casing , the length of the constrained steel casing must ensure the normal movement of the buckling restraining brace under ultimate compressive deformation and still effectively restrain the energy dissipation section and transition section under ultimate tensile deformation. Thus, the length of the constrained steel casing can be calculated as follows: （5）； S3. Calculate the wall thickness of the restrained steel casing and determine the strength grade of the concrete filling material according to the local stability theory. Specifically: The local instability phenomenon should not occur during the working process of the buckling - resistant brace to ensure its stable hysteretic energy - dissipation capacity. This requires that the wall thickness of the restrained steel casing of the buckling - resistant brace should not be too small. The strength grade of the filled concrete is taken as C30, and the minimum wall thickness of the restrained steel casing of the buckling - resistant brace is calculated according to the local stability theory : （6）； In the formula, is the standard value of the compressive strength of concrete in the confined steel casing, is the design value of the yield strength of steel, is the width of the energy dissipation section; S4. Determine the sectional width-thickness ratio of the connection section according to the torsional buckling theory, and calculate the minimum width of the steel casing with buckling restraint braces according to the Euler stability theory : （7）； In the formula, is the elastic modulus of the steel; S5. Calculate the thickness of the unbonded material according to the Poisson effect when the energy dissipation unit is compressed. The thickness of the unbonded material layer is calculated according to the following formula: （8）； In the formula, is the Poisson's ratio of the steel; S6. Calculate the series stiffness of the connection section, transition section, and energy dissipation section of the energy dissipation unit, and check the consistency between the series stiffness and the actual elastic stiffness of the buckling-restrained brace, specifically including the following steps: S61. Calculate the axial stiffness of the buckling-restrained brace connection section, transition section, and energy dissipation section , , ; （9）； （10）； （11）； S62. Calculate the equivalent axial series stiffness of the buckling-restrained brace according to the stiffness series principle :[[]]END]] （12）； S63. Check whether the actual axial stiffness and actual yield displacement of the buckling-restrained brace obtained from the design verification are consistent with the given theoretical elastic stiffness and theoretical yield displacement, that is, whether the following two equations are satisfied. If the following two equations are not satisfied, adjust the steel grade or modify the length of the connection section and then recalculate the equivalent axial series stiffness of the brace until the following two equations are satisfied: （13）； （14）； S7. Check the consistency between the yield displacement of the buckling-restrained brace corresponding to the equivalent series stiffness and the actual yield displacement, and check the ultimate deformation capacity of the buckling-restrained brace; Check the ultimate deformation capacity of the buckling-restrained brace. The maximum strain value of the energy dissipation section of the buckling-restrained brace should not exceed 0.03 to ensure the stable exertion of its hysteretic energy dissipation capacity, that is, the strain value of the buckling-restrained brace at the ultimate displacement should satisfy the following formula; If the following formula is not satisfied, then reduce the length of the connection section and recheck until the requirements of the following formula are met: （15）。 3. A design method of a buckling-restrained brace based on mechanical property parameters according to claim 2, characterized in that, The cross-sectional form of the energy dissipation section of the buckling-restrained brace is "one-shaped" or "cross-shaped", and the thickness ranges from 10 mm to 80 mm; for the "one-shaped" cross-section, the cross-sectional width of the energy dissipation section , ranges from 10 to 20; for the "cross-shaped" cross-section, the cross-sectional width of the energy dissipation section , ranges from 5 to 10; after calculating according to the method of step S1, the specific sizes of the cross-sectional width and thickness of the corresponding energy dissipation section of the buckling-restrained brace can be determined; in step S1, is related to the grade of the steel. For Q235 steel takes 1.25, for Q190 steel takes 1.

15. When the steel grade does not exceed 160, takes 1.

10.

4. A design method of a buckling-restrained brace based on mechanical property parameters according to claim 2, characterized in that, In the step S12, The nominal yield strain of the steel is calculated according to the following formula: （16）。 5. A design method of a buckling-restrained brace based on mechanical property parameters according to claim 2, wherein, In the step S15, the cross-sectional form of the buckling-restrained brace connection segment is "cross-shaped", and the cross-sectional thickness of the connection segment is the same as that of the energy dissipation segment, that is . After calculating according to the method in step 5, the out-of-plane free width of the cross-section of the connection segment can be calculated , and the torsional local stability of the connection segment is checked by the following formula: （17）。 6. The design method of a buckling-restrained brace based on mechanical property parameters according to claim 2, characterized in that, In the step S15, the strain strengthening adjustment coefficient of the steel is related to the grade of the steel. For Q235 steel and Q190 steel take 1.

5. When the steel grade does not exceed 160, take 2.

0.

7. A design method of a buckling-restrained brace based on mechanical property parameters according to claim 2, characterized in that, In the step S5, the Poisson's ratio of the steel is taken as 0.3.

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