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

Abstract

The application discloses a design method of a buckling-restrained brace based on mechanical performance parameters and relates to the field of aseismic component design methods, and comprises the following steps: calculating the length and sectional size of an energy dissipation section, a transition section and a connecting section of the buckling-restrained brace according to the mechanical performance parameters of the buckling-restrained brace in an actual structure; calculating the sectional size of a restrained steel sleeve according to an elastic stability theory; calculating the wall thickness of the restrained steel sleeve and determining the strength grade of concrete filling material according to a local stability theory; determining the sectional width-thickness ratio of the connecting section according to a torsional instability theory; calculating the thickness of non-bonding material according to the Poisson effect when the energy dissipation unit is compressed; and calculating the series stiffness of the connecting section, the transition section and the energy dissipation section of the energy dissipation unit, checking the consistency of the series stiffness and the actual elastic stiffness of the buckling-restrained brace and the like. The application can realize the performance-based parameterized design of the buckling-restrained brace product according to the mechanical performance parameters of the buckling-restrained brace provided by a structural engineer.

Description

Technical Field

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

[0002] With the continuous development of industrialized cities and towns and the growing demand for seismic performance of modern buildings, reducing the damage suffered by buildings under earthquakes and alleviating the loss of public life and property has become a top priority in contemporary engineering structure design.

[0003] At present, the seismic design of building structures generally adopts the method of increasing the structural damping or setting up isolation layers to reduce the energy input of the earthquake to the structure. Traditional buckling-resistance braces are mainly composed of internal core materials, external restraining members, unbonded expandable materials and unbonded sliding interfaces, and are connected between the beams and columns of the main structure. Under the action of strong earthquakes, the buckling-resistance braces produce plastic deformation, have good hysteretic energy absorption capacity and ductile deformation capacity, and can significantly reduce the degree of damage to the main structure under the action of earthquakes.

[0004] However, the current buckling-resistance brace components lack a systematic and effective design method, which makes it difficult for the buckling-resistance brace to play the expected energy dissipation and shock absorption role under strong earthquakes. Its function of protecting the main structure is difficult to achieve, and it is 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 anti-buckling braces based on mechanical performance parameters. The method of the present invention systematically and comprehensively proposes a structural design and calculation method for anti-buckling braces, and the designed anti-buckling braces meet the structural mechanical performance parameters, thereby effectively playing the damper function under actual earthquake action, and can effectively dissipate seismic energy after reaching yield deformation to prevent damage to the building.

[0006] In order to achieve the above technical effects, the present invention is implemented through the following technical solutions:

[0007] A design method for a buckling-restrained brace based on mechanical performance parameters comprises the following steps:

[0008] S1. Design the length and cross-sectional dimensions of the energy dissipation section, transition section, and connection section of the buckling-resistor brace according to the requirements of the seismic mechanical performance parameters of the buckling-resistor brace in the building;

[0009] S2. Calculate the cross-sectional dimensions of the restraining steel casing according to elastic stability theory;

[0010] S3. Calculate the wall thickness of the restraining steel casing and determine the strength grade of the concrete filling material based on the local stability theory;

[0011] S4. Determine the cross-sectional width-to-thickness ratio of the connecting section based on the torsional instability theory, and calculate the minimum width of the buckling-restrained brace-constrained steel casing based on the Euler stability theory;

[0012] S5. Calculate the thickness of the unbonded material based on the Poisson effect when the energy dissipation unit is under pressure;

[0013] S6. Calculate the series stiffness of the energy dissipation unit connection section, transition section, and energy dissipation section, and verify the consistency of the series stiffness with the actual elastic stiffness of the buckling-restrained brace;

[0014] S7. Verify the consistency between the yield displacement of the buckling-restrained brace corresponding to the equivalent series stiffness and the actual yield displacement, and verify the ultimate deformation capacity of the buckling-restrained brace.

[0015] Furthermore, a design method of a buckling-restrained brace based on mechanical performance parameters includes the following steps:

[0016] S1. Design the length and cross-sectional dimensions of the energy dissipation section, transition section, and connection section of the buckling restraint brace according to the requirements of the seismic mechanical performance parameters of the buckling restraint brace in the building, specifically including the following steps:

[0017] S11. According to the yield bearing capacity F of the buckling-restrained brace Y Calculate the cross-sectional area A of the energy dissipation section of the buckling-restrained brace c :

[0018]

[0019] Where η is the super strength coefficient of steel, that is, the ratio of the actual yield strength of steel to the nominal yield strength, f Y is the nominal yield strength of the steel;

[0020] S12, according to the yield displacement U of the buckling-restrained brace Y Calculate the length L of the energy dissipation section of the buckling-resistance brace c :

[0021]

[0022] Where,∈ Y The nominal yield strain of steel, λ, ranges from 0.65 to 0.75;

[0023] S13. Calculate the length L of the transition section of the buckling-resistance brace t , is 3% to 5% of the total length of the buckling-restrained brace L, i.e. L t =αL, α ranges from 0.03 to 0.05;

[0024] S14. Calculate the length L1 of the buckling-resistance brace connection section, which is the total length L of the brace minus the length L of the support energy-absorbing section calculated in S12. c and subtract twice the transition length L calculated in S13 t ,Right now:

[0025]

[0026] S15. Calculate the cross-sectional area A1 of the buckling-restrained brace connection. The elastic connection of the buckling-restrained brace is always in an elastic working state, so its stress under the ultimate bearing capacity of the brace should be less than the yield strength of the steel f Y , from which the minimum cross-sectional area requirement of the buckling-restrained brace connection section can be determined:

[0027]

[0028] Where ω is the strain hardening adjustment coefficient of steel;

[0029] 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-resistance support U max Calculate the length L of the restraining steel casing r The length of the restraining steel casing must ensure that the buckling restraint brace can move normally under the ultimate compression deformation and can still effectively restrain the energy dissipation section and transition section under the ultimate tensile deformation. Therefore, the length of the restraining steel casing can be calculated as:

[0030] L r =L-4×U max (5);

[0031] S3. Calculate the wall thickness of the restraining steel casing and determine the strength grade of the concrete filling material based on the local stability theory. Specifically, the buckling restraint brace should not experience 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 restraint brace should not be too small, and the filling concrete strength grade should be C30. Calculate the minimum wall thickness t of the restraining steel casing of the buckling restraint brace based on the local stability theory. r :

[0032]

[0033] Where, f ck is the standard value of concrete compressive strength in the constrained steel casing, f is the design value of steel yield strength, b c is the width of the energy consumption section;

[0034] S4. Determine the cross-sectional width-to-thickness ratio of the connecting section based on the torsional instability theory, and calculate the minimum width b of the buckling restraint steel casing based on the Euler stability theory. r :

[0035]

[0036] Where E is the elastic modulus of steel;

[0037] S5. Calculate the thickness of the unbonded material based on the Poisson effect when the energy dissipation unit is under pressure. The thickness of the unbonded material layer is calculated as follows:

[0038]

[0039] Where v is the Poisson's ratio of steel;

[0040] S6. Calculate the series stiffness of the energy dissipation unit connection section, transition section, and energy dissipation section, and verify the consistency of the series stiffness with the actual elastic stiffness of the buckling-restrained brace. Specifically, the following steps are included:

[0041] S61. Calculate the axial stiffness K of the buckling-restrained brace connection section, transition section, and energy dissipation l , K t , K c ;

[0042]

[0043]

[0044] S62. Calculate the equivalent axial series stiffness K of the buckling-restrained brace based on the stiffness series principle. e :

[0045]

[0046] S63. Verify whether the actual axial stiffness and yield displacement of the designed buckling-restrained brace are consistent with the given theoretical elastic stiffness and 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 recalculate the equivalent axial series stiffness K of the brace: e , until the following two requirements are met:

[0047]

[0048] S7. Verify the consistency between the yield displacement of the buckling restraint brace under the equivalent series stiffness and the actual yield displacement, and verify the ultimate deformation capacity of the buckling restraint brace. When verifying the ultimate deformation capacity 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 performance of its hysteretic energy dissipation capacity. That is, the strain value of the buckling restraint brace under ultimate displacement should satisfy the following formula. If the following formula is not satisfied, reduce the length of the connecting section and re-calculate until the following formula is satisfied:

[0049]

[0050] Furthermore, the cross-section of the buckling-resistance support energy dissipation section is in the form of a "straight" or "cross" shape, and the thickness t c The value is 10mm~80mm; for the "I-shaped" section, the width of the energy dissipation section b c =β1t c , β1 takes a value of 10-20; for the "cross-shaped" section, the width of the energy dissipation section b c =β2t c , β2 takes a value of 5-10; calculate A according to the method of step S1 c Then, the cross-sectional width b of the corresponding buckling-resistance brace energy-absorbing section can be determined. c and thickness t c the value of η in step S1 is related to the steel grade, Q235 steel η is taken as 1.25, Q190 steel η is taken as 1.15, when the steel grade does not exceed 160, η is taken as 1.10.

[0051] Furthermore, in step S12, ∈ Y The nominal yield strain of steel is calculated as follows:

[0052]

[0053] Furthermore, in step S15, the cross-sectional form of the buckling-resistance brace connecting section is a "cross-shaped" section, and the cross-sectional thickness t1 of the connecting section is the same as that of the energy dissipation section, that is, t1 = t c After calculating A1 according to the method in step 5, the cross-sectional free width of the connecting section can be calculated. The torsional local stability of the connection segment is verified according to the following formula:

[0054] Furthermore, in step S15, the value of the strain hardening adjustment coefficient ω of the steel is related to the grade of the steel. For Q235 steel and Q190 steel, ω is 1.5. When the steel grade does not exceed 160, ω is 2.0.

[0055] Furthermore, in step S5, the Poisson's ratio v of the steel is set to 0.3.

[0056] Furthermore, the actual axial stiffness K of the buckling-resistance brace is calculated in step S73. e Specific theoretical axial stiffness K s If the error is large and exceeds 5%, you can choose a larger grade of steel or reduce the length of the energy-consuming section. Otherwise, choose a smaller grade of steel or increase the length of the energy-consuming section until the error between the two does not exceed 5%.

[0057] At the same time, the present invention also discloses a computer system, which includes the above-mentioned design method and can be used to design a buckling-restrained brace directly based on mechanical performance parameters.

[0058] The beneficial effects of the present invention are as follows: The method of the present invention systematically and comprehensively proposes a method for the structural design and calculation of the anti-buckling support, and innovatively proposes the length L of the energy dissipation section of the anti-buckling support. c , the length of the restraining steel casing L r , the minimum width b of the buckling restraint steel casing r , the concept and calculation method of the thickness of the unbonded material layer, and proposed a verification method for whether the actual axial stiffness and actual yield displacement of the anti-buckling brace are consistent with the given theoretical elastic stiffness and theoretical yield displacement, as well as a method for checking the ultimate deformation capacity of the anti-buckling brace. The anti-buckling brace designed by this method meets the structural mechanical performance parameters, so that it quickly enters the buckling deformation stage in an actual earthquake, and is destroyed after reaching the yield strength to prevent the damage of building components. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0060] Figure 1 This is a front view of the assembly of the I-shaped inner core buckling restraint support in Example 1;

[0061] Figure 2 This is a top view of the I-shaped inner core buckling restraint support assembly in Example 1;

[0062] Figure 3 This is a processing diagram of the I-shaped inner core buckling-resistance brace energy-dissipating core plate in Example 1;

[0063] Figure 4 This is a processing diagram of the stiffening ribs of the end connection section of the I-shaped inner core buckling restraint brace in Example 1;

[0064] Figure 5 This is a processing diagram of the straight inner core buckling restraint support steel casing in Example 1;

[0065] Figure 6 Example 1 Figure 1 Middle 1-1 cross-section;

[0066] Figure 7 Example 1 Figure 1 Section 2-2;

[0067] Figure 8This is an assembly diagram of the cross-core buckling-restrained brace in Example 2;

[0068] Figure 9 This is a processing diagram of the cross-shaped inner core anti-buckling brace energy-absorbing inner core main core plate in Example 2;

[0069] Figure 10 This is a processing diagram of the cross-shaped inner core buckling restraint brace energy dissipation inner core sub-core plate in Example 2;

[0070] Figure 11 This is a processing diagram of the cross-shaped inner core buckling restraint brace restraint steel casing in Example 2;

[0071] Figure 12 Example 2 Figure 8 Section 3-3;

[0072] Figure 13 Example 2 Figure 8 Section 4-4. DETAILED DESCRIPTION

[0073] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0074] The present invention provides a design method for a buckling-restrained brace based on mechanical performance parameters, which is characterized by comprising the following steps:

[0075] S1. Design the length and cross-sectional dimensions of the energy dissipation section, transition section, and connection section of the buckling restraint brace according to the requirements of the seismic mechanical performance parameters of the buckling restraint brace in the building, specifically including the following steps:

[0076] S11. According to the yield bearing capacity F of the buckling-restrained brace Y Calculate the cross-sectional area A of the energy dissipation section of the buckling-restrained brace c :

[0077]

[0078] Where η is the super strength coefficient of steel, that is, the ratio of the actual yield strength of steel to the nominal yield strength, f Y is the nominal yield strength of the steel;

[0079] S12, according to the yield displacement U of the buckling-restrained brace Y Calculate the length L of the energy dissipation section of the buckling-resistance brace c :

[0080]

[0081] Where,∈ Y The nominal yield strain of steel, λ, ranges from 0.65 to 0.75;

[0082] S13. Calculate the length L of the transition section of the buckling-resistance brace t , is 3% to 5% of the total length of the buckling-restrained brace L, i.e. L t =αL, α ranges from 0.03 to 0.05;

[0083] S14. Calculate the length L1 of the buckling-resistance brace connection section, which is the total length L of the brace minus the length L of the support energy-absorbing section calculated in S12. c and subtract twice the transition length L calculated in S13 t ,Right now:

[0084]

[0085] S15. Calculate the cross-sectional area A1 of the buckling-restrained brace connection. The elastic connection of the buckling-restrained brace is always in an elastic working state, so its stress under the ultimate bearing capacity of the brace should be less than the yield strength of the steel f Y , from which the minimum cross-sectional area requirement of the buckling-restrained brace connection section can be determined:

[0086]

[0087] Where ω is the strain hardening adjustment coefficient of steel;

[0088] 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-resistance support U max Calculate the length L of the restraining steel casing r The length of the restraining steel casing must ensure that the buckling restraint brace can move normally under the ultimate compression deformation and can still effectively restrain the energy dissipation section and transition section under the ultimate tensile deformation. Therefore, the length of the restraining steel casing can be calculated as:

[0089] L r =L-4×U max (5);

[0090] S3. Calculate the wall thickness of the restraining steel casing and determine the strength grade of the concrete filling material based on the local stability theory. Specifically, the buckling restraint brace should not experience 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 restraint brace should not be too small, and the filling concrete strength grade should be C30. Calculate the minimum wall thickness t of the restraining steel casing of the buckling restraint brace based on the local stability theory. r :

[0091]

[0092] Where, f ck is the standard value of concrete compressive strength in the constrained steel casing, f is the design value of steel yield strength, b c is the width of the energy consumption section;

[0093] S4. Determine the cross-sectional width-to-thickness ratio of the connecting section based on the torsional instability theory, and calculate the minimum width b of the buckling restraint steel casing based on the Euler stability theory. r :

[0094]

[0095] Where E is the elastic modulus of steel;

[0096] S5. Calculate the thickness of the unbonded material based on the Poisson effect when the energy dissipation unit is under pressure. The thickness of the unbonded material layer is calculated as follows:

[0097]

[0098] Where ν is the Poisson's ratio of steel;

[0099] S6. Calculate the series stiffness of the energy dissipation unit connection section, transition section, and energy dissipation section, and verify the consistency of the series stiffness with the actual elastic stiffness of the buckling-restrained brace. Specifically, the following steps are included:

[0100] S61. Calculate the axial stiffness K of the buckling-restrained brace connection section, transition section, and energy dissipation l , K t , K c ;

[0101]

[0102] S62. Calculate the equivalent axial series stiffness K of the buckling-restrained brace based on the stiffness series principle. e :

[0103]

[0104] S63. Verify whether the actual axial stiffness and yield displacement of the designed buckling-restrained brace are consistent with the given theoretical elastic stiffness and 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 recalculate the equivalent axial series stiffness K of the brace: e , until the following two requirements are met:

[0105]

[0106] S7. Verify the consistency between the yield displacement of the buckling restraint brace under the equivalent series stiffness and the actual yield displacement, and verify the ultimate deformation capacity of the buckling restraint brace. When verifying the ultimate deformation capacity 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 performance of its hysteretic energy dissipation capacity. That is, the strain value of the buckling restraint brace under ultimate displacement should satisfy the following formula. If the following formula is not satisfied, reduce the length of the connecting section and re-calculate until the following formula is satisfied:

[0107]

[0108] In this embodiment, the cross-section of the buckling-resistance brace energy-absorbing section is in the form of a "straight" or "cross" shape, and the thickness t c The value is 10mm~80mm; for the "I-shaped" section, the width of the energy dissipation section b c =β1t c , β1 takes a value of 10-20; for the "cross-shaped" section, the width of the energy dissipation section b c =β2t c , β2 takes a value of 5-10; calculate A according to the method of step S1 c Then, the cross-sectional width b of the corresponding buckling-resistance brace energy-absorbing section can be determined. c and thickness t c the value of η in step S1 is related to the steel grade, Q235 steel η is taken as 1.25, Q190 steel η is taken as 1.15, when the steel grade does not exceed 160, η is taken as 1.10.

[0109] In this embodiment, in step S12, ∈ Y The nominal yield strain of steel is calculated as follows:

[0110]

[0111] In this embodiment, in step S15, the cross-sectional form of the buckling-resistance brace connecting section is a "cross-shaped" section, and the cross-sectional thickness t1 of the connecting section is the same as that of the energy dissipation section, that is, t1 = t c After calculating A1 according to the method in step 5, the cross-sectional free width of the connecting section can be calculated. The torsional local stability of the connection segment is verified according to the following formula:

[0112] In this embodiment, in step S15, the value of the strain hardening adjustment coefficient ω of the steel is related to the grade of the steel. For Q235 steel and Q190 steel, ω is 1.5. When the steel grade does not exceed 160, ω is 2.0.

[0113] In this embodiment, in step S5, the Poisson's ratio v of the steel is set to 0.3.

[0114] In this embodiment, the actual axial stiffness K of the buckling-resistance brace calculated in step S73 is e Specific theoretical axial stiffness K s If the error is large and exceeds 5%, you can choose a larger grade of steel or reduce the length of the energy-consuming section. Otherwise, choose a smaller grade of steel or increase the length of the energy-consuming section until the error between the two does not exceed 5%.

[0115] At the same time, the present invention also discloses a computer system, which includes the above-mentioned design method and can be used to design a buckling-restrained brace directly based on mechanical performance parameters.

[0116] The effectiveness of this design method is further verified by combining the specific design process below:

[0117] Example 1

[0118] In this embodiment, the cross-section of the buckling-resistance brace energy-absorbing section is in the form of a "straight line":

[0119] In an actual engineering project, the mechanical performance parameters of the buckling-restrained brace provided by the structural engineer are shown in the following table:

[0120]

[0121] Step 1: Select Q355 steel to design the buckling-resistance support energy dissipation component, i.e. ff Y =335MPa. Then the cross-sectional area of ​​the energy-absorbing section of the buckling-restrained brace is:

[0122]

[0123] Take the thickness of the energy dissipation section t c =20mm, then the width of the energy consumption section

[0124] Step 2: Under given design parameters, the yield displacement U of the buckling-restrained brace is Y =5.5mm, then the length of the energy-absorbing section of the buckling-resistance brace is:

[0125]

[0126] Step 3: The length of the transition section of the buckling-resistance brace is 4% of the total brace length, i.e.

[0127] L t =0.04×L=0.04×3500=140mm

[0128] Step 4: The length of the buckling-resistance brace connection section L1 is the total length of the brace L minus the length of the support energy dissipation section L calculated in step 2. c and subtract twice the transition length L calculated in step 3t ,Right now:

[0129]

[0130] Step 5: The connection section is always in the elastic working state under the elastic working state of the buckling restraint support. The stress under the ultimate bearing capacity of the support should be less than the yield strength f of the steel. Y , the minimum cross-sectional area of ​​the buckling-restrained brace connection section is: The cross-sectional area A1 of the connecting section is 2.2 times the cross-sectional area A1 of the energy-consuming section, i.e. A1 = 13772 mm 2 , meeting A1>10563mm 2 requirements.

[0131] Step 6: According to the ultimate displacement U of the buckling restraint support max Calculate the length L of the restraining steel casing r The length of the restraining steel casing must ensure that the buckling restraint brace can move normally under the ultimate compression deformation and can still effectively restrain the energy dissipation section and transition section under the ultimate tensile deformation. The length of the restraining steel casing is:

[0132] L r =L-4×U max =3500-4×14.4=3442mm, round up to get L r =3400mm.

[0133] Step 7: The buckling restraint brace should not experience local instability during operation to ensure its stable hysteretic energy dissipation capacity. The wall thickness of the buckling restraint brace steel casing should not be too small, and the filling concrete strength grade should be C30. According to the local stability theory, the minimum wall thickness t of the buckling restraint brace steel casing is calculated. r :

[0134] Round up, i.e. take t r =3mm

[0135] Step 8: The buckling restraint brace should not show any overall instability during operation to ensure that it has sufficient stable bearing capacity and hysteretic energy dissipation capacity. Calculate the minimum width b of the buckling restraint brace steel casing according to Euler stability theory. r :

[0136]

[0137] When b r When the value is 370mm,

[0138] The calculation results meet the bending stiffness requirements.

[0139] Step 9: When the buckling restraint is subjected to an axial compressive load, the energy dissipation section will produce axial compression deformation. Due to the Poisson effect, it will also expand in the lateral direction. The space for this expansion deformation is provided by the non-bonded layer attached to the surface of the buckling restraint energy dissipation component. The thickness of the non-bonded material layer should not be too large, otherwise the buckling deformation curvature of the buckling restraint energy dissipation section will be large, thereby reducing the fatigue life of the buckling restraint. The thickness of the non-bonded material layer is:

[0140] Round up, i.e. take t m =1mm.

[0141] Step 10: Calculate the axial stiffness K of the buckling-resistance brace connection section, transition section, and energy dissipation l , K t , K c :

[0142] Step 11: Calculate the equivalent axial series stiffness K of the buckling-restrained brace according to the stiffness series principle e :

[0143]

[0144] Step 12: Verify whether the actual axial stiffness and yield displacement of the designed buckling-restrained brace are consistent with the given theoretical elastic stiffness and yield displacement, that is:

[0145]

[0146] Both are less than 5%, and the verification results meet the requirements.

[0147] Step 13: Verify the ultimate deformation capacity of the buckling restraint. The maximum strain value of the energy dissipation section of the buckling restraint should not exceed 0.03 to ensure the stable performance of its hysteretic energy dissipation capacity. That is, the strain value of the buckling restraint under the ultimate displacement should meet the following requirements:

[0148] The calculated result is less than 3%, and the verification result meets the requirements.

[0149] Verify the torsional stability of the extended connection section of the buckling restraint brace: The cross-sectional thickness of the buckling restraint brace connection section is t1 = t c =20mm, the free width of the connecting section The torsional local stability of the connection segment is verified according to the following formula:

[0150]

[0151] 8.35<10.58, the verification results meet the requirements and torsional instability will not occur.

[0152] Finally, based on the calculation results, the structural design diagram of the buckling-restrained brace is obtained as shown in Figure 1-7.

[0153] Example 2

[0154] In this embodiment, the cross-section of the buckling-resistance brace energy-absorbing section is a "cross-shaped" shape:

[0155] In an actual engineering project, the mechanical performance parameters of the buckling-restrained brace provided by the structural engineer are shown in the following table:

[0156]

[0157] Calculate the processing parameters of the buckling-restrained brace product according to the steps in the embodiment:

[0158] Step 1: Select Q235 steel to design the buckling-resistance support energy dissipation component, i.e. f Y =235MPa. Then the cross-sectional area of ​​the energy-absorbing section of the buckling-restrained brace is:

[0159]

[0160] Take the thickness of the energy dissipation section t c =18mm, then the width of the energy consumption section

[0161] Step 2: Under given design parameters, the yield displacement U of the buckling-restrained brace is Y =5.7mm, then the length of the energy-absorbing section of the buckling-restrained brace is:

[0162]

[0163] Step 3: The length of the transition section of the buckling-resistance brace is 4% of the total brace length, i.e.

[0164] L t =0.04×L=0.04×4300=172mm

[0165] Step 4: The length of the buckling-resistance brace connection section L1 is the total length of the brace L minus the length of the support energy dissipation section L calculated in step 2. c and subtract twice the transition length L calculated in step 3 t ,Right now:

[0166]

[0167] Step 5: The connection section is always in the elastic working state under the elastic working state of the buckling restraint support. The stress under the ultimate bearing capacity of the support should be less than the yield strength f of the steel. y , the minimum cross-sectional area of ​​the buckling-restrained brace connection section is: The cross-sectional area A1 of the connecting section is 2.2 times the cross-sectional area A1 of the energy-consuming section, i.e. A1 = 13617 mm 2 , meeting A1≥12767mm 2 requirements.

[0168] Step 6: According to the ultimate displacement U of the buckling restraint support max Calculate the length L of the restraining steel casing r The length of the restraining steel casing must ensure that the buckling restraint brace can move normally under the ultimate compression deformation and can still effectively restrain the energy dissipation section and transition section under the ultimate tensile deformation. The length of the restraining steel casing is:

[0169] L r =L-4×U max =4300-4×24=4204mm, round up to get L r =4200mm.

[0170] Step 7: The buckling restraint brace should not experience local instability during operation to ensure its stable hysteretic energy dissipation capacity. The wall thickness of the buckling restraint brace steel casing should not be too small, and the filling concrete strength grade should be C30. According to the local stability theory, the minimum wall thickness t of the buckling restraint brace steel casing is calculated. r :

[0171] Round up, i.e. take t r =3mm.

[0172] Step 8: The buckling restraint brace should not show any overall instability during operation to ensure that it has sufficient stable bearing capacity and hysteretic energy dissipation capacity. Calculate the minimum width b of the buckling restraint brace steel casing according to Euler stability theory. r :

[0173] When b r When the value is 400mm, Meet the bending stiffness requirements.

[0174] Step 9: When the buckling restraint is subjected to an axial compressive load, the energy dissipation section will produce axial compression deformation. Due to the Poisson effect, it will also expand in the lateral direction. The space for this expansion deformation is provided by the non-bonded layer attached to the surface of the buckling restraint energy dissipation component. The thickness of the non-bonded material layer should not be too large, otherwise the buckling deformation curvature of the buckling restraint energy dissipation section will be large, thereby reducing the fatigue life of the buckling restraint. The thickness of the non-bonded material layer is:

[0175] Round up, i.e. take t m =1mm.

[0176] Calculate the axial stiffness K of the buckling-resistance brace connection section, transition section, and energy dissipation l , K t , K c :

[0177]

[0178] Step 11: Calculate the equivalent axial series stiffness K of the buckling-restrained brace according to the stiffness series principle e :

[0179]

[0180] Step 12: Verify whether the actual axial stiffness and yield displacement of the designed buckling-restrained brace are consistent with the given theoretical elastic stiffness and yield displacement, that is:

[0181]

[0182]

[0183] Both are less than 5%, and the verification results meet the requirements.

[0184] The verification results meet the requirements.

[0185] Step 13: Verify the ultimate deformation capacity of the buckling restraint. The maximum strain value of the energy dissipation section of the buckling restraint should not exceed 0.03 to ensure the stable performance of its hysteretic energy dissipation capacity. That is, the strain value of the buckling restraint under the ultimate displacement should meet the following requirements:

[0186] The calculated result is less than 3%, and the verification result meets the requirements.

[0187] Verify the torsional stability of the extended connection section of the buckling restraint brace: The cross-sectional thickness of the buckling restraint brace connection section is t1 = t c =18mm, the free width of the connecting section The torsional local stability of the connection segment is verified according to the following formula:

[0188]

[0189] The verification results meet the requirements and torsional instability will not occur.

[0190] The final design structure diagram of the buckling-restrained brace is shown in Figure 8-13.

[0191] Throughout this specification, reference to terms such as "one embodiment," "example," or "specific example" indicates that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Claims

1. A design method for a buckling-restrained brace based on mechanical performance parameters, characterized in that: The following steps are involved: S1. Design the length and cross-sectional dimensions of the energy dissipation section, transition section, and connection section of the buckling restraint brace according to the requirements of the seismic mechanical performance parameters of the buckling restraint brace in the building, specifically including the following steps: S11. Based on the yield capacity of the buckling-restrained brace Calculate the cross-sectional area of ​​the energy-absorbing section of the buckling-resistance brace : （1）； Where η is the super strength 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 the steel; S12. According to the yield displacement of the buckling-restrained brace Calculate the length of the energy-absorbing section of the buckling-resistance brace : （2）； Where, The nominal yield strain of steel, λ, ranges from 0.65 to 0.75; S13. Calculate the length of the transition section of the buckling-resistance brace , is taken as the total length of the buckling-restrained brace 3%~5% of , α ranges from 0.03 to 0.05; S14. Calculate the length of the buckling-restrained brace connection segment , which is the total length of the support Subtract the length of the support energy dissipation section calculated in S12 and subtract twice the transition length calculated in S13 ,Right now: （3）； S15. Calculate the cross-sectional area of ​​the buckling-restrained brace connection segment The elastic connection section of the buckling-restrained brace is always in an elastic working state, so its stress under the ultimate bearing capacity of the support should be less than the yield strength of the steel. , from which the minimum cross-sectional area requirement of the buckling-restrained brace connection section can be determined: （4）； Where ω is the strain hardening adjustment coefficient of steel; S2. Calculate the cross-sectional dimensions of the restraining steel casing according to the elastic stability theory. Specifically: Calculate the length of the restraining steel casing The length of the restraining steel casing must ensure that the buckling restraint brace can move normally under the ultimate compression deformation and can still effectively restrain the energy dissipation section and transition section under the ultimate tensile deformation. Therefore, 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 based on the local stability theory. Specifically, the buckling restraint brace should not experience 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 restraint brace should not be too small, and the filling concrete strength grade should be C30. Calculate the minimum wall thickness of the restraining steel casing of the buckling restraint brace based on the local stability theory. : （6）； Where, To constrain the standard value of concrete compressive strength in steel casing, is the design value of steel yield strength, is the width of the energy consumption section; S4. Determine the cross-sectional width-to-thickness ratio of the connection section based on the torsional instability theory, and calculate the minimum width of the buckling-restrained brace-constrained steel casing based on the Euler stability theory. : （7）； Where, is the elastic modulus of steel; S5. Calculate the thickness of the unbonded material based on the Poisson effect when the energy dissipation unit is under pressure. The thickness of the unbonded material layer is calculated as follows: （8）； Where, is the Poisson's ratio of steel; S6. Calculate the series stiffness of the energy dissipation unit connection section, transition section, and energy dissipation section, and verify the consistency of the series stiffness with the actual elastic stiffness of the buckling-restrained brace. Specifically, the following steps are included: S61. Calculate the axial stiffness of the buckling-restrained brace connection section, transition section, and energy dissipation 、 、 : （9）； （10）； （11）； S62. Calculate the equivalent axial series stiffness of the buckling-restrained brace based on the stiffness series principle : （12）； S63. Verify whether the actual axial stiffness and yield displacement of the designed buckling-restrained brace are consistent with the given theoretical elastic stiffness and 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 recalculate the equivalent axial series stiffness of the brace. , until the following two requirements are met: （13）； （14）； Where, is the theoretical axial stiffness; S7. Verify the consistency between the yield displacement of the buckling restraint brace under the equivalent series stiffness and the actual yield displacement, and verify the ultimate deformation capacity of the buckling restraint brace. When verifying the ultimate deformation capacity 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 performance of its hysteretic energy dissipation capacity. That is, the strain value of the buckling restraint brace under ultimate displacement should satisfy the following formula. If the following formula is not satisfied, reduce the length of the connecting section and re-calculate until the following formula is satisfied: （15）。 2. The design method of a buckling-restrained brace based on mechanical performance parameters according to claim 1, characterized in that: The cross-section of the buckling-resistance support energy-absorbing section is in the form of a "straight" or "cross" shape, and the thickness is The value ranges from 10 mm to 80 mm. For the "I-shaped" section, the width of the energy dissipation section is , The value is 10-20; for the "cross-shaped" section, the width of the energy dissipation section , The value is 5-10; calculate according to the method of step S1 Then, the cross-sectional width of the corresponding buckling-resistance brace energy-absorbing section can be determined. and thickness the value of η in step S1 is related to the steel grade, Q235 steel η is taken as 1.25, Q190 steel η is taken as 1.15, when the steel grade does not exceed 160, η is taken as 1.

10.

3. The design method of a buckling-restrained brace based on mechanical performance parameters according to claim 1, characterized in that: In the step S12, The nominal yield strain of steel is calculated as follows: （16）。 4. The design method of a buckling-restrained brace based on mechanical performance parameters according to claim 1, characterized in that: In step S15, the cross-sectional form of the buckling-resistance brace connecting section is "cross-shaped", and the cross-sectional thickness of the connecting section is Same as the energy consumption section, that is , calculated according to the method in step 15 After that, the cross-sectional free width of the connecting section can be calculated. , and the torsional local stability of the connection segment is verified according to the following formula: （17）。 5. The design method of a buckling-restrained brace based on mechanical performance parameters according to claim 1, characterized in that: In step S15, the value of the strain hardening adjustment coefficient ω of the steel is related to the grade of the steel. For Q235 steel and Q190 steel, ω is 1.

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

0.

6. The design method of a buckling-restrained brace based on mechanical performance parameters according to claim 1, characterized in that: In step S5, the Poisson's ratio of the steel The value of is 0.3.

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