A method for determining mechanical performance parameters of a buckling-restrained brace based on test data

Abstract

This invention discloses a method for determining the mechanical performance parameters of buckling-restrained braces based on experimental data, within the field of building energy dissipation and vibration reduction technology. The method includes: calculating the elastic stiffness using linear equation fitting based on the unloading law of the hysteresis curve of the buckling-restrained brace test; calculating the post-yield stiffness of the buckling-restrained brace using linear equation fitting based on the maximum load data points on the hysteresis curve under various loading levels, thereby calculating the post-yield stiffness coefficient of the buckling-restrained brace; plotting the elastic stiffness curve through the origin on the hysteresis curve and intersecting it with the post-yield stiffness curve, solving for the coordinates of the intersection point, and thus determining the yield bearing capacity and yield displacement of the tested buckling-restrained brace. This invention can accurately determine the values ​​of various mechanical performance parameters based on the experimental data of the buckling-restrained brace, thereby quickly and accurately determining whether the buckling-restrained brace is a qualified product.

Description

Technical Field

[0001] This invention relates to the field of building energy dissipation and vibration reduction technology, specifically to a method for determining the mechanical performance parameters of buckling-resistance braces based on experimental data. Background Technology

[0002] Whether the mechanical parameters of buckling-restrained braces meet the design requirements directly affects their energy dissipation and vibration reduction performance, which in turn directly relates to the seismic safety of the structure in which they are installed. Typically, after buckling-restrained braces are manufactured, they must undergo factory self-inspection and third-party testing. The test results are used to evaluate whether the buckling-restrained braces are qualified products. Only when the deviation between the test results and the theoretical design values ​​is controlled within the allowable range can they be used in actual engineering projects.

[0003] Currently, after buckling-restrained braces complete testing, product testing engineers mainly use bilinear models or Bouc-Wen models to fit the mechanical performance parameters of buckling-restrained braces. The accuracy of the fitting results of these two models is significantly affected by the selection of model parameters, and it is necessary to write computer programs to fit the mechanical performance parameters, which has problems such as unreliable calculation results and high calculation difficulty. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a method for determining the mechanical performance parameters of buckling-restrained braces based on experimental data. This method can directly determine various mechanical performance parameters of buckling-restrained braces by decomposing the data and establishing linear equations based on the load-displacement hysteresis curve data of the buckling-restrained braces. This method is of great significance for the performance testing and qualification determination of buckling-restrained brace products.

[0005] To achieve the above-mentioned technical effects, the present invention is implemented through the following technical solution:

[0006] A method for determining the mechanical performance parameters of buckling-resisted braces based on experimental data, characterized by comprising the following steps:

[0007] S1. Calculate the elastic stiffness based on the unloading law of the hysteresis curve of the buckling-restrained brace test. Load-displacement test data under various loading levels of buckling-restrained braces were used. Load-displacement hysteresis curves were plotted in an Excel spreadsheet with displacement data on the x-axis and load data on the y-axis. The data from the first load-displacement test was then extracted. Under stage loading, the data points on the unloading segments in the positive and negative directions of each hysteresis curve, i.e., the data points between the maximum load point and the zero load point, are fitted with linear equations to obtain the results for each stage. The load-displacement relationship of each unloading segment under stage loading is a straight line, i.e.:

[0008] (1)

[0009] In the formula, For the fitted first Load unloading segment under level loading, For the fitted first Displacement of the unloading segment under level loading. For the first The slope of the unloading segment under stage loading is the first level of the buckling-restrained brace. Elastic stiffness under level loading These are the fitting constants;

[0010] S2. Take the average value of the elastic stiffness calculated under each loading level in step S1 as the experimental value of the elastic stiffness of the buckling-restrained brace. :

[0011] (2)

[0012] S3. Extract the maximum load-displacement data points in the positive and negative directions after yielding on the hysteresis curves under each loading level, and fit the load-displacement linear equations after yielding in the positive and negative directions using linear equations, respectively:

[0013] (3)

[0014] (4)

[0015] In the formula, and These represent the loads after yielding in the positive and negative directions of the fitted buckling-resistance brace hysteresis curves, respectively. and These represent the displacements after yielding in the positive and negative directions, respectively, of the fitted buckling-resistance brace hysteresis curves. and These are the post-yield stiffnesses obtained by fitting the buckling-restrained brace in the positive and negative directions, respectively. and These are the fitting constants;

[0016] S4. Take the average value of the post-yield stiffness obtained by fitting in the positive and negative directions as the experimental value of the post-yield stiffness of the buckling-restrained brace. :

[0017] (5)

[0018] S5. Elastic stiffness obtained from steps S2 and S4 and post-yield stiffness Determine the post-yield stiffness coefficient of the buckling-restrained brace. :

[0019] (6)

[0020] S6. Draw a line through the origin on the hysteresis curve with a slope of... The straight line, and the slope is The stiffness lines after yielding intersect; calculate the coordinates of the intersection point. , This refers to the test value of the yield strength of the buckling-restrained brace. This refers to the experimental value of the yield displacement of the buckling-restrained brace, at the intersection point. The solution equation is:

[0021] (7)

[0022] (8)

[0023] In the formula, and These are the ordinate and abscissa of the fitted line, respectively. These are the fitting constants;

[0024] S7. Calculate the first using numerical integration methods. The area enclosed by the hysteresis curve of the buckling-resistive brace under level loading. The formula for calculating numerical integrals is:

[0025] (9)

[0026] In the formula, For the first Total number of data points on the hysteresis curve of buckling-restrained brace under level loading

[0027] S8. All the results calculated in step S7 By summing the results, the total energy dissipation of the buckling-restrained brace can be obtained. :

[0028] (10)

[0029] In the formula, The number of test loading levels for anti-buckling braces;

[0030] S9, Take out the first Maximum load in the positive and negative directions of the hysteresis curve of the buckling-restrained brace under level loading and And calculate the first one according to the following formula. Adjustment factor for bearing capacity of buckling-restrained braces under level loading :

[0031] (11)

[0032] S10. Take the adjustment coefficient of the buckling-restrained brace bearing capacity under each loading level in step S9. The maximum value is used as the test value for the buckling-restrained brace bearing capacity adjustment coefficient. :

[0033] (12)

[0034] S11. Compare the various mechanical performance parameters of the buckling-restrained brace determined from the test data in steps S1 to S10 with the theoretical design values. If the error between the test values ​​and theoretical design values ​​of each mechanical performance parameter does not exceed 15%, and the test value of the buckling-restrained brace bearing capacity adjustment coefficient is within acceptable limits... If the value does not exceed 1.3, the buckling brace is considered a qualified product; otherwise, it is considered an unqualified product.

[0035] Furthermore, the linear correlation coefficient of the linear fitting equation in step S1 The square value It should not be less than 0.95 to ensure sufficient fitting accuracy. If the value is less than 0.95, the fitting accuracy can be improved by reducing the number of data points near zero load on the unloading segment of the hysteresis curve.

[0036] The beneficial effects of this invention are: the method can directly determine the various mechanical performance parameters of buckling-restrained braces by decomposing the data and establishing linear equations based on the load-displacement hysteresis curve data of buckling-restrained braces, which is of great significance for the performance testing and qualification determination of buckling-restrained brace products. Attached Figure Description

[0037] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a flowchart of the method of the present invention;

[0039] Figure 2 It is a fitting diagram of the elastic stiffness of the buckling-resistance brace;

[0040] Figure 3 This is a fitting diagram of the stiffness of the buckling-resistance brace after yielding;

[0041] Figure 4 This is a diagram showing the determination of the yield capacity and yield displacement of buckling-restrained braces.

[0042] Figure 5 This is a schematic diagram of energy dissipation calculation for buckling-restrained braces;

[0043] Figure 6 It is the hysteresis curve of the buckling-resistance brace test;

[0044] Figure 7 This is a load-displacement relationship fitting graph of the unloading segment of the hysteresis curve under Level 1 loading;

[0045] Figure 8 This is a load-displacement relationship fitting graph of the unloading segment of the hysteresis curve under Level 2 loading;

[0046] Figure 9 This is a load-displacement relationship fitting graph of the unloading segment of the hysteresis curve under level 3 loading;

[0047] Figure 10 This is a load-displacement relationship fitting diagram of the unloading segment of the hysteresis curve under level 4 loading;

[0048] Figure 11 This is the fitting diagram of the stiffness of the buckling-resistance brace after yielding in the verification example;

[0049] Figure 12 This is a diagram showing the determination of the yield bearing capacity and yield displacement of the buckling-resistance brace in the verification example. Detailed Implementation

[0050] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0051] like Figure 1 As shown, the present invention provides a method for determining the mechanical performance parameters of a buckling-resistance brace based on experimental data, comprising the following steps:

[0052] A method for determining the mechanical performance parameters of buckling-resisted braces based on experimental data, characterized by comprising the following steps:

[0053] S1. Calculate the elastic stiffness based on the unloading law of the hysteresis curve of the buckling-restrained brace test. Load-displacement test data under various loading levels of buckling-restrained braces were used. Load-displacement hysteresis curves were plotted in an Excel spreadsheet with displacement data on the x-axis and load data on the y-axis. The data from the first load-displacement test was then extracted. Under stage loading, the data points on the unloading segments in the positive and negative directions of each hysteresis curve, i.e., the data points between the maximum load point and the zero load point, are fitted with linear equations to obtain the results for each stage. The load-displacement relationship lines for each unloading segment under staged loading are shown below. Figure 2 As shown, that is:

[0054] (1)

[0055] In the formula, For the fitted first Load unloading segment under level loading, For the fitted first Displacement of the unloading segment under level loading. For the first The slope of the unloading segment under stage loading is the first stage of the buckling-restrained brace. Elastic stiffness under level loading These are the fitting constants;

[0056] S2. Take the average value of the elastic stiffness calculated under each loading level in step S1 as the experimental value of the elastic stiffness of the buckling-restrained brace. :

[0057] (2)

[0058] S3. Extract the maximum load-displacement data points in the positive and negative directions after yielding on the hysteresis curves under each loading level, and fit the load-displacement linear equations after yielding in the positive and negative directions using linear equations, respectively:

[0059] (3)

[0060] (4)

[0061] In the formula, and These represent the loads after yielding in the positive and negative directions of the fitted buckling-resistance brace hysteresis curves, respectively. and These represent the displacements after yielding in the positive and negative directions, respectively, of the fitted buckling-resistance brace hysteresis curves. and These are the post-yield stiffnesses obtained by fitting the buckling-restrained brace in the positive and negative directions, respectively. and These are the fitting constants;

[0062] S4. Take the average value of the post-yield stiffness obtained by fitting in the positive and negative directions as the experimental value of the post-yield stiffness of the buckling-restrained brace. :

[0063] (5)

[0064] S5. Elastic stiffness obtained from steps S2 and S4 and post-yield stiffness Determine the post-yield stiffness coefficient of the buckling-restrained brace. :

[0065] (6)

[0066] S6. Draw a line through the origin on the hysteresis curve with a slope of... The straight line, and the slope is The stiffness lines after yielding intersect; calculate the coordinates of the intersection point. , This refers to the test value of the yield strength of the buckling-restrained brace. This refers to the experimental value of the yield displacement of the buckling-restrained brace, at the intersection point. The solution equation is:

[0067] (7)

[0068] (8)

[0069] In the formula, and These are the ordinate and abscissa of the fitted line, respectively. These are the fitting constants;

[0070] S7. Calculate the first using numerical integration methods. The area enclosed by the hysteresis curve of the buckling-resistive brace under level loading. The formula for calculating numerical integrals is:

[0071] (9)

[0072] In the formula, For the first Total number of data points on the hysteresis curve of buckling-restrained brace under level loading

[0073] S8. All the results calculated in step S7 By summing the results, the total energy dissipation of the buckling-restrained brace can be obtained. :

[0074] (10)

[0075] In the formula, The number of test loading levels for anti-buckling braces;

[0076] S9, Take out the first Maximum load in the positive and negative directions of the hysteresis curve of the buckling-restrained brace under level loading and And calculate the first one according to the following formula. Adjustment factor for bearing capacity of buckling-restrained braces under level loading :

[0077] (11)

[0078] S10. Take the adjustment coefficient of the buckling-restrained brace bearing capacity under each loading level in step S9. The maximum value is used as the test value for the buckling-restrained brace bearing capacity adjustment coefficient. :

[0079] (12)

[0080] S11. Compare the various mechanical performance parameters of the buckling-restrained brace determined from the test data in steps S1 to S10 with the theoretical design values. If the error between the test values ​​and theoretical design values ​​of each mechanical performance parameter does not exceed 15%, and the test value of the buckling-restrained brace bearing capacity adjustment coefficient is within acceptable limits... If the value does not exceed 1.3, the buckling brace is considered a qualified product; otherwise, it is considered an unqualified product.

[0081] In this embodiment, the linear correlation coefficient of the linear fitting equation in step S1 The square value It should not be less than 0.95 to ensure sufficient fitting accuracy. If the value is less than 0.95, the fitting accuracy can be improved by reducing the number of data points near zero load on the unloading segment of the hysteresis curve.

[0082] Verification Example

[0083] Table 1 shows the theoretical mechanical performance parameters submitted to the manufacturer for the design and production of buckling-restrained braces in a certain engineering project. After completing the production of the buckling-restrained braces, the manufacturer, according to the specifications, should conduct a factory self-inspection of the mechanical performance of the products to determine whether the manufactured products are qualified. Figure 6 The hysteresis curve of the buckling-resistive brace obtained through a quasi-static test is shown.

[0084] Table 1 Theoretical values ​​of mechanical performance parameters of buckling-restrained braces

[0085] Support Model Yield load F y (kN) Yield displacement D y (mm) Elastic stiffness K 1 (kN / mm) <![CDATA[Post-yield stiffness K 2 (kN / mm)]]> Post-yield stiffness coefficient Energy dissipation (kN·mm) Load-bearing capacity adjustment coefficient Energy-consuming type 4000 15 266.67 13.33 0.05 6443755 ≤1.3

[0086] according to Figure 1 The flowchart is used for calculation, and the steps are as follows:

[0087] Step 1: Based on the load-displacement hysteresis curve data obtained from the experiment, extract the data points of the unloading segments in the positive and negative directions of each hysteresis curve under loading levels 1, 2, 3, and 4 respectively. Use linear equations to fit the data to obtain the load-displacement hysteresis curves for each level. The load-displacement linear curves of each unloading segment under stage loading are shown below. Figure 7 , 8 As shown in Figures 9 and 10, the fitted linear equation is:

[0088] (13) (Level 1 loading in the positive direction)

[0089] (14) (Negative direction of Level 1 loading)

[0090] (15) (Level 2 loading in the positive direction)

[0091] (16) (Negative direction of level 2 loading)

[0092] (17) (Level 3 loading in the positive direction)

[0093] (18) (Negative direction of level 3 loading)

[0094] (19) (Level 4 loading in the positive direction)

[0095] (20) (Level 4 loading in the negative direction)

[0096] Step 2: The elastic stiffness of the buckling-restrained brace under each loading level obtained from the fitting calculation in Step 1 are as follows: The elastic stiffness corresponding to the first loading level is: , The elastic stiffness corresponding to the second level of loading is: , The elastic stiffness corresponding to the third level of loading is: , The elastic stiffness corresponding to the 4th level of loading is: , The average value of the elastic stiffness calculated by fitting under each loading level is taken as the experimental value of the elastic stiffness of the buckling-restrained brace. :

[0097] (twenty one)

[0098] Step 3: Extract the maximum load-displacement data points after yielding in the positive and negative directions on the hysteresis curves under each loading level, and fit the load-displacement linear equations after yielding in the positive and negative directions using linear equations, such as... Figure 11 As shown, the fitted linear equation is:

[0099] (twenty two)

[0100] (twenty three)

[0101] Step 4: The post-yield stiffness of the buckling-restrained brace obtained from the fitting in Step 3 in the positive and negative directions are respectively... , The average value of the post-yield stiffness obtained by fitting in the positive and negative directions is taken as the experimental value of the post-yield stiffness of the buckling-restrained brace. :

[0102] (twenty four)

[0103] Step 5: Based on the elastic stiffness obtained in Steps 2 and 4 and Calculate the post-yield stiffness coefficient of the buckling-restrained brace. :

[0104] (25)

[0105] Step 6: Plot a line on the hysteresis curve through the origin with a slope of... The straight line, and the slope is The stiffness lines after yielding intersect; calculate the coordinates of the intersection point. , This refers to the test value of the yield strength of the buckling-restrained brace. This refers to the test value of the yield displacement of the buckling-resistance brace, such as... Figure 12 As shown, the intersection point The solution equation is:

[0106] (26)

[0107] (27)

[0108] Solving equations (26) and (27) yields the coordinates of the intersection point (15.2, 3960), which is the experimental value of the yield bearing capacity of the buckling-restrained brace. Test values ​​of yield displacement of buckling-restrained braces .

[0109] Step 7: Calculate the area enclosed by the hysteresis curves of the buckling-restrained brace under each loading level using the numerical integration method, i.e., formula (9). , , , .

[0110] Step 8: Apply all the calculations obtained in step 7 By summing the results, the total energy dissipation of the buckling-restrained brace can be obtained. :

[0111] (28)

[0112] Step 9: Take out the first Maximum load in the positive and negative directions of the hysteresis curve of the buckling-restrained brace under level loading and The corresponding level is: Level 1 loading. , Level 2 loading , Level 3 loading , Level 4 loading , And calculate the first according to formula (11). Adjustment factor for bearing capacity of buckling-restrained braces under level loading :

[0113] (29)

[0114] (30)

[0115] (31)

[0116] (32)

[0117] Step 10: Take the adjustment coefficients for the bearing capacity of the buckling-restrained braces under each loading level in Step 9. The maximum value is used as the test value for the buckling-restrained brace bearing capacity adjustment coefficient. :

[0118] (33)

[0119] Step 11: Compare the various mechanical performance parameters of the buckling-restrained brace determined from the test data in Steps 1 to 10 with the theoretical design values ​​in Table 1. If the error between the test values ​​and the theoretical design values ​​of each mechanical performance parameter does not exceed 15%, and the test value of the buckling-restrained brace bearing capacity adjustment coefficient is within acceptable limits... If the value does not exceed 1.3, the buckling brace is considered a qualified product; otherwise, it is considered an unqualified product. Specific comparisons are shown in Table 2.

[0120] Table 2 Comparison of theoretical and experimental values ​​of mechanical performance parameters of buckling-restrained braces

[0121]

[0122] As can be seen from the comparison results of the parameters in Table 2, the deviations between the theoretical design values ​​and the experimental values ​​of the various mechanical performance parameters of the buckling-restrained brace are all less than 15%. Therefore, through the comparative analysis of the test results, it can be determined that the buckling-restrained brace is a qualified product and has passed the factory inspection.

[0123] In the description of this specification, references to terms such as "an embodiment," "example," and "specific example" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above 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 one or more embodiments or examples.

Claims

1. A method for determining the mechanical performance parameters of a buckling-resistance brace based on experimental data, characterized in that, Includes the following steps: S1. Calculate the elastic stiffness based on the unloading law of the hysteresis curve of the buckling-restrained brace test. Load-displacement test data under various loading levels of buckling-restrained braces were used. Load-displacement hysteresis curves were plotted in an Excel spreadsheet with displacement data on the x-axis and load data on the y-axis. The data from the first load-displacement test was then extracted. Under stage loading, the data points on the unloading segments in the positive and negative directions of each hysteresis curve, i.e., the data points between the maximum load point and the zero load point, are fitted with linear equations to obtain the results for each stage. The load-displacement relationship of each unloading segment under stage loading is a straight line, i.e.: （1） In the formula, For the fitted first Load unloading segment under level loading, For the fitted first Displacement of the unloading segment under level loading. For the first The slope of the unloading segment under stage loading is the first stage of the buckling-restrained brace. Elastic stiffness under level loading These are the fitting constants; S2. Take the average value of the elastic stiffness calculated under each loading level in step S1 as the experimental value of the elastic stiffness of the buckling-restrained brace. : （2） S3. Extract the maximum load-displacement data points in the positive and negative directions after yielding on the hysteresis curves under each loading level, and fit the load-displacement linear equations after yielding in the positive and negative directions using linear equations, respectively: （3） （4） In the formula, and These represent the loads after yielding in the positive and negative directions of the fitted buckling-resistance brace hysteresis curves, respectively. and These represent the displacements after yielding in the positive and negative directions, respectively, of the fitted buckling-resistance brace hysteresis curves. and These are the post-yield stiffnesses obtained by fitting the buckling-restrained brace in the positive and negative directions, respectively. and These are the fitting constants; S4. Take the average value of the post-yield stiffness obtained by fitting in the positive and negative directions as the experimental value of the post-yield stiffness of the buckling-restrained brace. : （5） S5. Elastic stiffness obtained from steps S2 and S4 and post-yield stiffness Determine the post-yield stiffness coefficient of the buckling-restrained brace. : （6） S6. Draw a line through the origin on the hysteresis curve with a slope of... The straight line, and the slope is The stiffness lines after yielding intersect; calculate the coordinates of the intersection point. , This refers to the test value of the yield strength of the buckling-restrained brace. This refers to the experimental value of the yield displacement of the buckling-restrained brace, at the intersection point. The solution equation is: （7） （8） In the formula, and These are the ordinate and abscissa of the fitted line, respectively. These are the fitting constants; S7. Calculate the first using numerical integration methods. The area enclosed by the hysteresis curve of the buckling-resistive brace under level loading. The formula for calculating numerical integrals is: A i = ∑ j = 1 n F j + 1 x + F j x ⋅ D j + 1 x - D j x 2 （9） In the formula, For the first Total number of data points on the hysteresis curve of buckling-resistive brace under stage loading; S8. All the results calculated in step S7 By summing the results, the total energy dissipation of the buckling-restrained brace can be obtained. : （10） In the formula, The number of test loading levels for anti-buckling braces; S9, Take out the first Maximum load in the positive and negative directions of the hysteresis curve of the buckling-restrained brace under level loading and And calculate the first one according to the following formula. Adjustment factor for bearing capacity of buckling-restrained braces under level loading : （11） S10. Take the adjustment coefficient of the buckling-restrained brace bearing capacity under each loading level in step S9. The maximum value is used as the test value for the buckling-restrained brace bearing capacity adjustment coefficient. : （12） S11. Compare the various mechanical performance parameters of the buckling-restrained brace determined from the test data in steps S1 to S10 with the theoretical design values. If the error between the test values ​​and theoretical design values ​​of each mechanical performance parameter does not exceed 15%, and the test value of the buckling-restrained brace bearing capacity adjustment coefficient is within acceptable limits... If the value does not exceed 1.3, the buckling brace is considered a qualified product; otherwise, it is considered an unqualified product.

2. The method for determining the mechanical performance parameters of a buckling-resistance brace based on experimental data according to claim 1, characterized in that, The linear correlation coefficient of the linear fitting equation in step S1 The square value It should not be less than 0.95 to ensure sufficient fitting accuracy. If the value is less than 0.95, the fitting accuracy can be improved by reducing the number of data points near zero load on the unloading segment of the hysteresis curve.

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