Quantitative evaluation method for seismic performance index of ecc jacketed composite column

Abstract

The application relates to the technical field of seismic performance evaluation of ECC jacketed composite columns, and particularly provides a seismic performance index quantification evaluation method of an ECC jacketed composite column, which calculates key seismic performance indexes such as bearing capacity, cumulative energy dissipation, ductility coefficient and limit value of the repairability interval, combines weight analysis and importance coefficient adjustment, establishes a scientific and comprehensive seismic performance evaluation system, proposes a determination method of the damage point of the ECC jacketed composite column, accurately determines the damage state, especially introduces the repairability interval evaluation, divides the repair grades based on residual deformation and Park-Ang damage indexes, provides a basis for post-earthquake maintenance decision, comprehensively considers different loading conditions through the proposed seismic performance index evaluation index, sets clear engineering application threshold values, and is convenient for engineers to quickly evaluate and optimize design; the method has important significance for promoting the engineering application of the ECC jacketed composite column.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of seismic performance evaluation of ECC jacketed composite columns, in particular to a seismic performance index quantification evaluation method of ECC jacketed composite columns. BACKGROUND

[0002] Column members are the key parts in the whole frame structure, which are related to the stability, seismic performance and safety of the whole structure system. In particular in high seismic intensity earthquake zones, it is particularly important to enhance the seismic toughness of column members in frame structures, especially in new energy projects such as booster station fields and large energy infrastructure such as power plants. ECC, due to its excellent mechanical properties and strain hardening behavior, has been used in the form of jacket to enhance the seismic toughness of column members. However, the feasibility of the application of ECC jacketed composite columns in different projects still needs a quantitative seismic performance index evaluation to comprehensively consider all seismic performance indexes. Therefore, the present application provides a seismic performance index quantification evaluation method of ECC jacketed composite columns to evaluate the feasibility of the application of ECC jacketed composite columns in engineering. SUMMARY

[0003] The present application aims to provide a seismic performance index quantification evaluation method of ECC jacketed composite columns to solve the technical problems existing in the prior art, and the specific technical solutions are as follows:

[0004] A seismic performance index quantification evaluation method of ECC jacketed composite columns, comprising the following steps:

[0005] Step S1, determining the failure point of the ECC jacketed composite column;

[0006] Step S2, determining and calculating the seismic performance index; the seismic performance index includes the bearing capacity, cumulative energy dissipation, ductility coefficient and limit value of the repairable interval;

[0007] Step S3, calculating the weight coefficient of a single seismic performance index;

[0008] Step S4, calculating the seismic performance index evaluation index of the ECC jacketed composite column.

[0009] Further, in step S1, the failure point of the ECC jacketed composite column is determined as follows:

[0010] Step S1.1, obtaining the failure strength of the ECC jacketed composite column:

[0011] Calculating the stress of the longitudinal reinforcement;

[0012] Calculating the stress resultant force of the ECC jacketed area and the concrete area; obtaining the distance between the stress resultant force and the stress distribution at both ends;

[0013] Construct the moment equilibrium equation and force equilibrium equation; calculate the failure strength of the ECC-jacketed composite column;

[0014] Step S1.2: Obtain the failure displacement of the ECC-jacketed composite column, and then determine the failure point of the ECC-jacketed composite column.

[0015] Furthermore, in step S1.1:

[0016] The stress in the longitudinal reinforcement is:

[0017] ;

[0018] in, For the first Stress in the longitudinal reinforcement; This represents the ultimate compressive strain of the concrete. For the first The distance between the longitudinal reinforcement and the neutral axis of the column section. This is the distance from the inner edge of the concrete of the ECC jacket to the neutral axis of the column section. The neutral axis of the column section is the boundary between the compression zone and the tension zone of the column section. Indicates the serial number of the longitudinal reinforcement;

[0019] The stress in the ECC jacket region and the concrete region exhibits a trend of first increasing and then decreasing. This stress distribution can be simplified as the sum of a right-angled triangular stress distribution and an arc-shaped stress distribution. The resultant stress in the ECC jacket region and the concrete region... for:

[0020] ;

[0021] in, Indicates the height of the compression zone of the cross section; Indicates the width of the cross section; The edge stress representing the stress distribution of the ECC jacket, The peak stress represents the stress distribution in the ECC jacket.

[0022] The distance from the resultant stress to the two ends of the stress distribution is:

[0023] ;

[0024] ;

[0025] in, and These represent the distances from the resultant stress force to the two ends of the stress distribution;

[0026] Construct the moment equilibrium equations and force equilibrium equations:

[0027] ;

[0028] ;

[0029] in, The stress of the longitudinal reinforcing steel under tension. This refers to the cross-sectional area of ​​the longitudinal reinforcing bars under tension. The stress of the longitudinal reinforcing steel under compression. This refers to the cross-sectional area of ​​the longitudinal reinforcing bars under compression. It is a vertical axial force; The resultant force of the concrete in the compression zone; The resultant force of the ECC in the pressure zone; This indicates the distance of the longitudinal reinforcement at each point from the point on which the moment is calculated when taking the moment of the longitudinal reinforcement at the edge of the tension zone of the cross section. This indicates the distance of the ECC sleeve from the longitudinal reinforcement at the edge of the tension zone of the cross section when calculating the moment. This indicates the distance from the concrete to the longitudinal reinforcement at the edge of the tension zone of the cross section when taking moments. This indicates the distance from the axial force at the edge of the tension zone of the cross-section when calculating the moment of the longitudinal reinforcement; the serial number of the longitudinal reinforcement is... ; Let be the failure moment at the base of the column, and let be the failure strength, which is the ratio of the failure moment to the distance from the horizontal force to the base of the column.

[0030] Furthermore, step S1.2 specifically involves: obtaining the skeleton curve based on the hysteresis curve of the column; fitting a functional relationship that represents the change of the skeleton curve segment; inputting the failure intensity into the functional relationship to obtain the corresponding failure displacement, and thus obtaining the failure point.

[0031] Furthermore, in step S2, the bearing capacity, cumulative energy dissipation, and ductility coefficient are all calculated by obtaining the hysteresis curve of the column; the bearing capacity is the peak bearing capacity of the column, which is the bearing capacity corresponding to the highest point of the obtained hysteresis curve of the column; the cumulative energy dissipation is the sum of energy dissipated during the entire loading process when the column reaches the failure point, and the sum of energy dissipated is the sum of single-cycle energy dissipation obtained in each loading stage during the loading process; the ductility coefficient is the ratio of the failure displacement of the column when it reaches the failure point to the yield displacement of the column.

[0032] Furthermore, the repairable interval is divided by residual deformation and damage index; the residual deformation is the horizontal displacement corresponding to the reduction of horizontal bearing capacity to 0 in each loading stage of the hysteresis curve; the damage index is used to divide the repair interval according to the magnitude of the damage index value, wherein a damage index less than 0.25 is a no-repair interval, a damage index greater than 0.25 and less than 0.65 is a repairable interval, and a damage index greater than 0.65 is an unrepairable interval; the division of the repair interval is represented by residual deformation, the upper limit of the no-repair interval is the residual deformation corresponding to a damage index of 0.25, and the upper limit of the repairable interval is the residual deformation corresponding to a damage index of 0.65.

[0033] Furthermore, the steps for determining the residual deformation limits of the unrepairable and repairable intervals are as follows:

[0034] K1, Obtain the yield strength of the column. Yield displacement Destructive strength and limit displacement ;

[0035] K2, Obtain the energy dissipation of each loading stage in the hysteresis curve. Horizontal displacement and residual deformation of the column The functional expression for residual deformation versus horizontal displacement was obtained through fitting.

[0036] K3, will , , , and Substituting the functional expressions for residual deformation and horizontal displacement, and calculating the damage index of the column for each loading stage based on the Park-Ang model, the column is considered to be in the no-repair zone if the damage index is less than 0.25. If the damage index calculated for a certain loading stage is not greater than 0.25, and the damage index for the next loading stage is greater than 0.25, then the horizontal displacement obtained for that loading stage is the upper limit of the no-repair zone. Correspondingly, the upper limit of the residual deformation in the no-repair zone is calculated by fitting the functional expressions for residual deformation and horizontal displacement. The column with a damage index greater than 0.25 and less than 0.65 is considered repairable, while the column with a damage index greater than 0.65 is considered unrepairable. The upper limit of residual deformation for the repairable section is then calculated using the same method. ;

[0037] K4, the repair interval is represented as: (1) No repair required interval: (2) The interval that can be repaired: (3) Unrepairable intervals: .

[0038] Furthermore, in step S3, the weighting coefficient for a single seismic performance index is calculated as follows:

[0039] Calculate the comparison matrix of various seismic performance indices for ECC-clad composite columns; the comparison matrix is ​​as follows:

[0040] ;

[0041] For comparison matrices; To compare the elements in the matrix; μ This represents the ductility coefficient of the ECC jacketed composite column; This indicates the bearing capacity of the ECC-jacketed composite column; This indicates the cumulative energy dissipation of the ECC jacketed composite column; This represents the upper limit of residual deformation in the unrepairable section of the ECC jacketed composite column; This represents the upper limit of residual deformation in the repairable section of the ECC jacketed composite column;

[0042] The comparative eigenvalues ​​are calculated and normalized to obtain the weighting coefficients for the single seismic performance index of the column. Specifically:

[0043] The comparison feature values ​​are:

[0044] ;

[0045] They represent the first Characteristic values ​​of the ECC jacketed composite column; Indicates the serial number of the ECC jacketed assembly column;

[0046] The eigenvalues ​​of the ECC jacketed composite column are normalized:

[0047] ;

[0048] For the first Characteristic values ​​of the ECC jacketed composite column; For the first The normalized characteristic value of the ECC-clad composite column is also the weighting coefficient of the column's single seismic performance index.

[0049] Furthermore, in step S4, the calculation of the seismic performance evaluation index specifically involves:

[0050] Assign importance coefficients to the weighting coefficients of each individual seismic performance index to obtain the sum of the seismic performance weighting coefficients of a single ECC-jacketed composite column. ;

[0051] Considering different load application methods, the final seismic performance evaluation index of the ECC-clad composite column is obtained.

[0052] Furthermore, the seismic performance weighting coefficients of a single ECC-jacketed composite column are accumulated. Represented as:

[0053] ;

[0054] in, and Indicates importance coefficient, ; Indicates the first The normalized value of the ductility coefficient of the ECC jacketed composite column. Indicates the first The normalized value of the bearing capacity of the ECC-jacketed composite column. Indicates the first The normalized value of the cumulative energy dissipation of the ECC jacketed composite column. Indicates the first The normalized value of the upper limit of residual deformation in the unrepairable section of the ECC jacketed composite column. Indicates the first The normalized value of the upper limit of residual deformation in the repairable section of the ECC jacketed composite column;

[0055] The final seismic performance evaluation index for ECC-clad composite columns is the average of the weighted seismic performance coefficients of ECC-clad composite columns obtained under different load application methods, expressed as:

[0056] ;

[0057] in, The seismic performance evaluation index for ECC-clad composite columns; for Different ways of applying loads.

[0058] The application of the technical solution of the present invention has the following beneficial effects:

[0059] This invention provides a quantitative evaluation method for the seismic performance of ECC-clad composite columns. This method establishes a comprehensive and scientific seismic performance evaluation system by calculating key seismic performance indicators such as bearing capacity, cumulative energy dissipation, ductility coefficient, and repairability interval limits, combined with weighting analysis and importance coefficient adjustment. It innovatively proposes a method for determining the failure point of ECC-clad composite columns, accurately determining the failure state through the plane section assumption and stress distribution equivalence method. Specifically, it introduces a repairability interval evaluation, classifying repair levels based on residual deformation and the Park-Ang damage index, providing a basis for post-earthquake maintenance decisions. The proposed seismic performance evaluation index comprehensively considers different loading conditions and sets clear engineering applicable thresholds (≥0.80), facilitating rapid evaluation and design optimization by engineers. This method can be used for performance evaluation of seismic strengthening of existing buildings and can guide the seismic design of new structures, which is of great significance for promoting the engineering application of ECC-clad composite columns.

[0060] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0061] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0062] Figure 1 This is a flowchart of the method for quantitatively evaluating the seismic performance of ECC-jacketed composite columns in this invention;

[0063] Figure 2 This is a flowchart for determining the residual deformation limit of the repairable range of the ECC jacketed composite column. Detailed Implementation

[0064] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered.

[0065] In the description of this invention, it should be noted that the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", "front", "back", "lateral", "longitudinal", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0066] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0067] Example:

[0068] See Figure 1 This embodiment provides a method for quantitatively evaluating the seismic performance of ECC-jacketed composite columns, including the following steps:

[0069] Step S1: Determine the failure point of the ECC jacketed composite column, including:

[0070] Step S1.1: Obtain the failure strength of the ECC-clad composite column, including: calculating the stress of the longitudinal reinforcement; calculating the resultant stress in the ECC-clad area and the concrete area; obtaining the distance of the resultant stress from the two ends of the stress distribution; constructing the moment equilibrium equation and the force equilibrium equation; and calculating the failure strength of the ECC-clad composite column.

[0071] The failure point of ECC-jacketed columns differs from that of ordinary concrete columns; ECC-jacketed composite columns should be distinguished from internally mounted ECC-jacketed composite columns and externally mounted ECC-jacketed composite columns.

[0072] When the composite column with built-in ECC sleeve reaches its failure point, the concrete edge inside the ECC sleeve reaches its ultimate compressive strain. The ECC sleeve at the outer edge of the core concrete is not considered in the calculation due to excessive damage. When calculating the yield point, the column section is assumed to conform to the plane section assumption, meaning the strain of the column section is considered linearly. Combining this with the value of the ultimate compressive strain at the concrete edge inside the ECC sleeve, the stress of the longitudinal reinforcement can be calculated. Specifically, the stress of the longitudinal reinforcement is:

[0073] ;

[0074] in, For the first Stress in the longitudinal reinforcement; This represents the ultimate compressive strain of the concrete. For the first The distance between the longitudinal reinforcement and the neutral axis of the column section. This is the distance from the inner edge of the concrete of the ECC jacket to the neutral axis of the column section. The neutral axis of the column section is the boundary between the compression zone and the tension zone of the column section. Indicates the serial number of the longitudinal reinforcement;

[0075] The stress in the ECC jacket region and the concrete region exhibits a trend of first increasing and then decreasing. This stress distribution can be simplified as the sum of a right-angled triangular stress distribution and an arc-shaped stress distribution. The resultant stress in the ECC jacket region and the concrete region... for:

[0076] ;

[0077] in, Indicates the height of the compression zone of the cross section; Indicates the width of the cross section; The edge stress representing the stress distribution of the ECC jacket, The peak stress represents the stress distribution in the ECC jacket.

[0078] In a right-angled triangle stress distribution, the ratio of the distance from the resultant force to the two ends of the stress distribution is 1:2; in an arc-shaped stress distribution, the ratio is 1:1; the distance from the resultant force to the two ends of the stress distribution is:

[0079] ;

[0080] ;

[0081] in, and These represent the distances from the resultant stress force to the two ends of the stress distribution;

[0082] Construct the moment equilibrium equations and force equilibrium equations:

[0083] ;

[0084] ;

[0085] in, The stress of the longitudinal reinforcing steel under tension. This refers to the cross-sectional area of ​​the longitudinal reinforcing bars under tension. The stress of the longitudinal reinforcing steel under compression. This refers to the cross-sectional area of ​​the longitudinal reinforcing bars under compression. It is a vertical axial force; The resultant force of the concrete in the compression zone; The resultant force of the ECC in the pressure zone; This indicates the distance of the longitudinal reinforcement at each point from the point on which the moment is calculated when taking the moment of the longitudinal reinforcement at the edge of the tension zone of the cross section. This indicates the distance of the ECC sleeve from the longitudinal reinforcement at the edge of the tension zone of the cross section when calculating the moment. This indicates the distance from the concrete to the longitudinal reinforcement at the edge of the tension zone of the cross section when taking moments. This indicates the distance from the axial force at the edge of the tension zone of the cross-section when calculating the moment of the longitudinal reinforcement; the serial number of the longitudinal reinforcement is... ; Let be the failure moment at the base of the column, and let be the failure strength, which is the ratio of the failure moment to the distance from the horizontal force to the base of the column.

[0086] In this embodiment, the failure strength of the composite column with built-in ECC jacket is calculated through the above calculation process. The value of the failure strength is approximately the bearing capacity corresponding to when the peak bearing capacity of the column drops to 75% of its peak bearing capacity.

[0087] Step S1.2: Obtain the failure displacement of the ECC-jacketed composite column, and then determine the failure point of the ECC-jacketed composite column. Specifically: Obtain the skeleton curve based on the column's hysteresis curve. The skeleton curve is the envelope formed by the maximum points of each loading stage in the column's hysteresis curve. Fit a functional relationship representing the change of this skeleton curve segment. The failure displacement should appear in the descending segment of this functional relationship. Input the failure intensity into this functional relationship to obtain the corresponding failure displacement, and thus obtain the failure point.

[0088] When the externally ECC-jacketed composite column reaches the failure point, the ECC jacket perpendicular to the horizontal force loading direction completely fails, and the concrete outside the stirrups also reaches the ultimate strain failure. The concrete at the edge of the stirrups begins to reach the ultimate strain. The calculation process of the failure strength of the externally ECC-jacketed composite column is similar to that of the internally ECC-jacketed composite column, so it will not be shown in detail. Its failure strength is also approximately the bearing capacity corresponding to the column's peak bearing capacity decreasing to 75%.

[0089] Step S2: Determine and calculate seismic performance indicators; the seismic performance indicators include bearing capacity, cumulative energy dissipation, ductility coefficient, and limits on the repairability range; specifically:

[0090] The bearing capacity, cumulative energy dissipation, and ductility coefficient are all calculated by obtaining the hysteresis curve of the column; the bearing capacity is the peak bearing capacity of the column, which is the bearing capacity corresponding to the highest point of the obtained hysteresis curve of the column; the cumulative energy dissipation is the sum of energy dissipated during the entire loading process when the column reaches the failure point, and the sum of dissipated energy is the sum of single-cycle energy dissipation obtained in each loading stage during the loading process; the ductility coefficient is the ratio of the failure displacement of the column when it reaches the failure point to the yield displacement of the column; the yield displacement of the column can be obtained by the equivalent elastoplastic energy method in seismic solution calculation;

[0091] The repairable interval is defined by residual deformation and a damage index. The residual deformation is the horizontal displacement corresponding to the reduction of the horizontal bearing capacity to 0 at each loading level in the hysteresis curve. The damage index is used to divide the repair interval based on its value: a damage index less than 0.25 indicates an interval requiring no repair; a damage index greater than 0.25 but less than 0.65 indicates a repairable interval; and a damage index greater than 0.65 indicates an unrepairable interval. The division of the repair interval is represented by residual deformation. The upper limit of the interval requiring no repair is the residual deformation corresponding to a damage index of 0.25, and the upper limit of the repairable interval is the residual deformation corresponding to a damage index of 0.65. In this embodiment, the repair interval includes a repairable interval and an unrepairable interval, and the repairable interval includes a repairable interval and an interval requiring no repair.

[0092] See Figure 2 The steps for determining the residual deformation limits of the unrepairable and repairable intervals are as follows:

[0093] K1, Obtain the yield strength of the column. Yield displacement Destructive strength and limit displacement Specifically, the skeleton curve is obtained through the hysteresis curve, and the corresponding functional relationship describing the change of the skeleton curve is fitted; yield strength ( The yield strength is obtained through the equivalent elastic-plastic energy method, and is generally considered to be 80% of the peak strength. Substituting this into the functional relationship yields the corresponding yield displacement. ); destructive strength ( The calculation can be obtained through the process described above. The calculated failure strength is generally 75% of the peak strength of the column. Combining this with the functional relationship, the corresponding ultimate displacement can be obtained. );

[0094] K2, Obtain the energy dissipation of each loading stage in the hysteresis curve. Horizontal displacement and residual deformation of the column Energy dissipation per stage of loading The area of ​​the hysteresis loop obtained by each loading stage in the hysteresis curve is represented by the sum of the areas of the hysteresis loops obtained by each loading stage, which yields the corresponding cumulative energy dissipation; the horizontal displacement represents the displacement corresponding to the peak point of the hysteresis loop obtained by each horizontal loading stage; the residual deformation of the column ( This refers to the displacement corresponding to the decrease in bearing capacity to 0 in the hysteresis loop obtained by each loading stage in the hysteresis curve; the functional expression of residual deformation and horizontal displacement is obtained by fitting.

[0095] K3, will , , , and Substituting the functional expressions for residual deformation and horizontal displacement, and calculating the damage index of the column for each loading stage based on the Park-Ang model, the column is considered to be in the no-repair zone if the damage index is less than 0.25. If the damage index calculated for a certain loading stage is not greater than 0.25, and the damage index for the next loading stage is greater than 0.25, then the horizontal displacement obtained for that loading stage is the upper limit of the no-repair zone. Correspondingly, the upper limit of the residual deformation in the no-repair zone is calculated by fitting the functional expressions for residual deformation and horizontal displacement. The column with a damage index greater than 0.25 and less than 0.65 is considered repairable, while the column with a damage index greater than 0.65 is considered unrepairable. The upper limit of residual deformation for the repairable section is then calculated using the same method. ;

[0096] K4, the repair interval is represented as: (1) No repair required interval: (2) The interval that can be repaired: (3) Unrepairable intervals: .

[0097] Step S3: Calculate the weighting coefficient of a single seismic performance index; specifically:

[0098] Calculate the comparison matrix of various seismic performance indices for ECC-clad composite columns; the comparison matrix is ​​as follows:

[0099] ;

[0100] For comparison matrices; To compare the elements in the matrix, let's take the cumulative energy dissipation comparison matrix as an example. , This indicates the serial number of the ECC-clad composite column, and so on, to calculate other seismic performance indicators. μ This represents the ductility coefficient of the ECC jacketed composite column; This indicates the bearing capacity of the ECC-jacketed composite column; This indicates the cumulative energy dissipation of the ECC jacketed composite column; This represents the upper limit of residual deformation in the unrepairable section of the ECC jacketed composite column; This represents the upper limit of residual deformation in the repairable section of the ECC jacketed composite column;

[0101] In this embodiment, the seismic performance indicators include bearing capacity, cumulative energy dissipation, ductility coefficient, and the limit value of the repairable range (i.e., the upper limit value of residual deformation in the non-repairable range and the upper limit value of residual deformation in the repairable range). Therefore, a comparison matrix of five single seismic performance indicators is constructed, and then the comparison eigenvalues ​​are calculated and normalized to obtain the weight coefficient of the single seismic performance indicator of the column.

[0102] The comparative eigenvalues ​​are calculated and normalized to obtain the weighting coefficients for the single seismic performance index of the column. Specifically:

[0103] The comparison feature values ​​are:

[0104] ;

[0105] They represent the first Characteristic values ​​of the ECC jacketed composite column; Indicates the serial number of the ECC jacketed assembly column;

[0106] The eigenvalues ​​of the ECC jacketed composite column are normalized:

[0107] ;

[0108] For the first Characteristic values ​​of the ECC jacketed composite column; For the first The normalized characteristic value of the ECC-clad composite column is also the weighting coefficient of the column's single seismic performance index.

[0109] Step S4: Calculate the seismic performance evaluation index of the ECC-clad composite column; specifically:

[0110] Assign importance coefficients to the weighting coefficients of each individual seismic performance index to obtain the sum of the seismic performance weighting coefficients of a single ECC-jacketed composite column. The seismic performance weighting coefficients of a single ECC-jacketed composite column are accumulated. Represented as:

[0111] ;

[0112] in, and Indicates importance coefficient, ; Indicates the first The normalized value of the ductility coefficient of the ECC jacketed composite column. Indicates the first The normalized value of the bearing capacity of the ECC-jacketed composite column. Indicates the first The normalized value of the cumulative energy dissipation of the ECC jacketed composite column. Indicates the first The normalized value of the upper limit of residual deformation in the unrepairable section of the ECC jacketed composite column. Indicates the first The normalized value of the upper limit of residual deformation in the repairable section of the ECC jacketed composite column;

[0113] In seismic design, ensuring the structure meets load-bearing capacity requirements is a prerequisite for preventing structural collapse and is also crucial for seismic design. Furthermore, ductility coefficient and energy dissipation are prerequisites for ductility design to prevent rapid damage development, and repairability is an important indicator for post-earthquake structural repair. Therefore, based on engineering practice and previous research, μ , , , and The recommended importance coefficients are 1.5, 4, 3, 0.5, and 1.

[0114] Considering different load application methods, the final seismic performance evaluation index of the ECC-clad composite column is obtained. The final seismic performance evaluation index of the ECC-clad composite column is the average of the accumulated seismic performance weighting coefficients of the ECC-clad composite column obtained under different load application methods, expressed as:

[0115] ;

[0116] in, The seismic performance evaluation index for ECC-clad composite columns; for Different ways of applying loads.

[0117] The higher the seismic performance evaluation index of ECC-clad composite columns, the better the overall performance of the ECC-clad composite columns, and the more suitable they are for engineering promotion. This invention recommends that the evaluation index be 0.8 or above, which fully meets the requirements for engineering promotion and application.

[0118] This embodiment provides finite element analysis results for 78 sets of column specimens for evaluation and analysis, specifically including the following:

[0119] Step 1: Finite element models of 78 sets of column specimens were established using ABAQUS, including circular cross-section columns, rectangular cross-section columns, and square cross-section columns; the cross-sectional areas of the three types of column sections were 1257 cm². 2 (Diameter (D) is 40cm), 1225cm 2 (Side length 35cm) and 1200cm 2(Side length is 30×40cm) Ensure that the cross-sectional area error of the three column sections is less than 5% for easy horizontal comparison; in addition, keep the error of the longitudinal steel reinforcement ratio and the stirrup volume reinforcement ratio of the three column sections within 5% for easy comparison and analysis.

[0120] The three different column specimens included four different reinforcement methods: increasing the diameter of the longitudinal reinforcement bars, increasing the column cross-section, using an external ECC-jacketed composite column, and using an internal ECC-jacketed composite column. The jacket thickness of the internal ECC-jacketed composite column was 80 mm, and the jacket thickness of the external ECC-jacketed composite column was 40 mm. Horizontal loading was controlled by displacement, with each loading increment being 5 mm, and each increment being repeated twice until a total of 50 mm was reached. Vertical loading employed both constant axial compression ratio loading and variable axial compression ratio loading. The constant axial compression ratio was 0.6, and the variable axial compression ratio was (0.6 ± 0.35). =3), indicating that its axial compression ratio changes by ±0.35, and the rate of change is... It is three times the horizontal loading; the specific number of sample groups is shown in the table below:

[0121] Table 1. Column specimen setup for circular cross-section columns

[0122]

[0123] Table 2. Column specimen setup for square cross-section columns

[0124]

[0125] Table 3. Column specimen setup for rectangular cross-section columns

[0126]

[0127] In addition, the modeling method of this model refers to the "Standard for Design of Concrete Structures" (GB / T 50010-2010 (2024 edition)), the Mander constitutive model of confined concrete and the Clough model (degenerate bilinear hysteresis model), etc. The model has been verified by experiments and the error is <5%.

[0128] Step 2: Based on the calculation method provided by this invention, the seismic performance indicators of the 78 sets of column tests were obtained. Furthermore, for ordinary concrete columns, the failure point was determined according to the concrete structure design standard, considering the strength corresponding to a decrease in peak bearing capacity to 85% as the failure strength. The corresponding failure displacement can then be obtained on the corresponding skeleton curve. The failure index of ordinary concrete columns can then be calculated using the calculation method provided by this invention. See the table below for details:

[0129] Table 4 Seismic performance indicators of 78 column specimens in this embodiment

[0130]

[0131] In particular, because the hysteresis curve of the column obtained when using vertical variable axial force loading has obvious asymmetry on both sides, when calculating the seismic performance index, and μ Take the average of the two sides. and The calculation is then performed based on the side that is more severely damaged (the side with a faster rate of bearing capacity degradation).

[0132] Step 3: Quantitatively evaluate the seismic performance indicators according to the method provided by this invention, and calculate the normalized values ​​of the single seismic performance indicators for each group of column samples, as shown in Table 5. In seismic design, meeting the bearing capacity design requirements is a prerequisite for preventing structural collapse and is also a key aspect of seismic design. Furthermore, ductility coefficient and energy dissipation are prerequisites for ductile design to prevent rapid damage development, while repairability is an important indicator for post-earthquake repair. Therefore, based on engineering practice and previous research... μ、 、 、 and The importance coefficients were set to 1.5, 4, 3, 0.5, and 1, respectively. Through calculation, the normalized values ​​of the seismic performance indicators and the seismic performance evaluation indices for the 78 column specimens were as follows:

[0133] Table 5. Normalized values ​​and seismic performance indexes of the 78 column specimens in this embodiment.

[0134]

[0135] A higher seismic performance evaluation index for ECC-clad composite columns indicates superior overall performance and greater suitability for engineering application. This invention recommends an evaluation index of 0.80 or higher for full compliance with engineering application requirements. The results also show that, for ECC-clad composite columns with sufficient cladding height, their seismic performance evaluation index is significantly higher than traditional methods of enhancing column seismic performance (such as increasing column cross-section or diameter of longitudinal reinforcement). This further demonstrates the promising future of ECC-clad composite columns for engineering application.

[0136] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for quantitatively evaluating the seismic performance of ECC-jacketed composite columns, characterized in that, Includes the following steps: Step S1: Determine the failure point of the ECC jacketed composite column; Step S2: Determine and calculate seismic performance indicators; the seismic performance indicators include bearing capacity, cumulative energy dissipation, ductility coefficient, and limits of the repairability range; Step S3: Calculate the weighting coefficient of a single seismic performance index; Step S4: Calculate the seismic performance evaluation index of the ECC-jacketed composite column; In step S1, the specific point of failure of the ECC jacketed composite column is determined as follows: Step S1.1: Obtain the breaking strength of the ECC-jacketed composite column: Calculate the stress in the longitudinal reinforcement; Calculate the resultant stress in the ECC jacket region and the concrete region; obtain the distance of the resultant stress from both ends of the stress distribution. Construct the moment equilibrium equation and force equilibrium equation; calculate the failure strength of the ECC-jacketed composite column; Step S1.2: Obtain the failure displacement of the ECC-jacketed composite column, and then determine the failure point of the ECC-jacketed composite column; In step S1.1: The stress in the longitudinal reinforcement is: ； in, For the first m Stress in the longitudinal reinforcement; This represents the ultimate compressive strain of the concrete. u m For the first m The distance between the longitudinal reinforcement and the neutral axis of the column section. This is the distance from the inner edge of the concrete of the ECC jacket to the neutral axis of the column section. The neutral axis of the column section is the boundary between the compression zone and the tension zone of the column section. m Indicates the serial number of the longitudinal reinforcement; The stress in the ECC jacket region and the concrete region exhibits a trend of first increasing and then decreasing. This stress distribution can be simplified as the sum of a right-angled triangular stress distribution and an arc-shaped stress distribution. The resultant stress in the ECC jacket region and the concrete region... F c for: ； in, x Indicates the height of the compression zone of the cross section; b Indicates the width of the cross section; The edge stress representing the stress distribution of the ECC jacket, The peak stress represents the stress distribution in the ECC jacket. The distance from the resultant stress to the two ends of the stress distribution is: ； ； in, y 1 and y 2 represents the distance from the resultant stress force to both ends of the stress distribution; Construct the moment equilibrium equations and force equilibrium equations: ； ； in, The stress of the longitudinal reinforcing steel under tension. A 1~ A v This refers to the cross-sectional area of ​​the longitudinal reinforcing bars under tension. The stress of the longitudinal reinforcing steel under compression. A v+1 ~ A m This refers to the cross-sectional area of ​​the longitudinal reinforcing bars under compression. N It is a vertical axial force; F c-c The resultant force of the concrete in the compression zone; F c-ECC The resultant force of the ECC in the pressure zone; S 1~ S v-1 , S v ~ S m-1 This indicates the distance of the longitudinal reinforcement at each point from the point on which the moment is calculated when taking the moment of the longitudinal reinforcement at the edge of the tension zone of the cross section. S ECC This indicates the distance of the ECC sleeve from the longitudinal reinforcement at the edge of the tension zone of the cross section when calculating the moment. S c This indicates the distance from the concrete to the longitudinal reinforcement at the edge of the tension zone of the cross section when taking moments. S This indicates the distance from the longitudinal reinforcement at the edge of the tension zone of the cross section when calculating the moment of the longitudinal reinforcement; the longitudinal reinforcement is numbered 1, 2, ... v ... m ; M u The failure moment is the bending moment at the base of the column, and the failure strength is the ratio of the failure moment to the distance from the horizontal force to the base of the column. Step S1.2 specifically involves: obtaining the skeleton curve based on the hysteresis curve of the column; fitting a functional relationship that represents the change of the skeleton curve segment; inputting the failure intensity into the functional relationship to obtain the corresponding failure displacement, and thus obtaining the failure point.

2. The method for quantitatively evaluating the seismic performance of an ECC-jacketed composite column according to claim 1, characterized in that, In step S2, the bearing capacity, cumulative energy dissipation, and ductility coefficient are all calculated by obtaining the hysteresis curve of the column; the bearing capacity is the peak bearing capacity of the column, which is the bearing capacity corresponding to the highest point of the obtained hysteresis curve of the column; the cumulative energy dissipation is the sum of energy dissipated during the entire loading process when the column reaches the failure point, and the sum of energy dissipated is the sum of single-cycle energy dissipation obtained in each loading stage during the loading process; the ductility coefficient is the ratio of the failure displacement of the column when it reaches the failure point to the yield displacement of the column.

3. The method for quantitatively evaluating the seismic performance of an ECC-jacketed composite column according to claim 2, characterized in that, The repairable interval is divided by residual deformation and damage index; the residual deformation is the horizontal displacement corresponding to the reduction of horizontal bearing capacity to 0 in each loading stage of the hysteresis curve; the damage index is used to divide the repair interval according to the magnitude of the damage index value, wherein a damage index less than 0.25 is a no-repair interval, a damage index greater than 0.25 and less than 0.65 is a repairable interval, and a damage index greater than 0.65 is an unrepairable interval; the division of the repair interval is represented by residual deformation, the upper limit of the no-repair interval is the residual deformation corresponding to a damage index of 0.25, and the upper limit of the repairable interval is the residual deformation corresponding to a damage index of 0.

65.

4. The method for quantitatively evaluating the seismic performance of an ECC-jacketed composite column according to claim 3, characterized in that, The steps for determining the residual deformation limits for the unrepairable and repairable intervals are as follows: K1, Obtain the yield strength of the column. F y Yield displacement θ y Destructive strength F u and limit displacement θ u ; K2, Obtain the energy dissipation of each loading stage in the hysteresis curve. q Horizontal displacement and residual deformation of the column θr ; The functional expression of residual deformation and horizontal displacement was obtained by fitting; K3, will θ y , θ u , F y , q and θr Substituting the functional expressions for residual deformation and horizontal displacement, and calculating the damage index of the column for each loading stage based on the Park-Ang model, the column is considered to be in the no-repair zone if the damage index is less than 0.

25. If the damage index calculated for a certain loading stage is not greater than 0.25, and the damage index for the next loading stage is greater than 0.25, then the horizontal displacement obtained for that loading stage is the upper limit of the no-repair zone. Correspondingly, the upper limit of the residual deformation in the no-repair zone is calculated by fitting the functional expressions for residual deformation and horizontal displacement. θ 1r The column with a damage index greater than 0.25 and less than 0.65 is considered repairable, while the column with a damage index greater than 0.65 is considered unrepairable. The upper limit of residual deformation for the repairable section is then calculated using the same method. θ 2r ; K4, the repair interval is represented as: (1) No repair required interval: θr < θ 1r (2) The interval that can be repaired: θ 1r ≤ θr ≤ θ 2r (3) Unrepairable intervals: θr > θ 2r .

5. The method for quantitatively evaluating the seismic performance of an ECC-jacketed composite column according to claim 1, characterized in that, In step S3, the weighting coefficient for a single seismic performance index is calculated as follows: Calculate the comparison matrix of various seismic performance indices for ECC-clad composite columns; the comparison matrix is ​​as follows: ； D For comparison matrices; To compare the elements in the matrix; μ This represents the ductility coefficient of the ECC jacketed composite column; P This indicates the bearing capacity of the ECC-jacketed composite column; Q This indicates the cumulative energy dissipation of the ECC jacketed composite column; θ 1r This represents the upper limit of residual deformation in the unrepairable section of the ECC jacketed composite column; θ 2r This represents the upper limit of residual deformation in the repairable section of the ECC jacketed composite column; The comparative eigenvalues ​​are calculated and normalized to obtain the weighting coefficients for the single seismic performance index of the column. Specifically: The comparison feature values ​​are: ； b 1~ b n They represent the 1st to the 2nd. n Characteristic values ​​of the ECC jacketed composite column; i Indicates the serial number of the ECC jacketed assembly column; The eigenvalues ​​of the ECC jacketed composite column are normalized: ； b i For the first i Characteristic values ​​of the ECC jacketed composite column; c i For the first i The normalized characteristic value of the ECC-clad composite column is also the weighting coefficient of the column's single seismic performance index.

6. The method for quantitatively evaluating the seismic performance of an ECC-jacketed composite column according to claim 5, characterized in that, In step S4, the calculation of the seismic performance evaluation index is specifically as follows: Assign importance coefficients to the weighting coefficients of each individual seismic performance index to obtain the sum of the seismic performance weighting coefficients of a single ECC-jacketed composite column. R ; Considering different load application methods, the final seismic performance evaluation index of the ECC-clad composite column is obtained.

7. The method for quantitatively evaluating the seismic performance of an ECC-jacketed composite column according to claim 6, characterized in that, Accumulated seismic performance weighting coefficients for single ECC-jacketed composite columns R Represented as: ； in, k 1. k 2. k 3. k 4 and k 5 represents the importance coefficient. k 1+ k 2+ k 3+ k 4+ k 5 = 10; Indicates the first i The normalized value of the ductility coefficient of the ECC jacketed composite column. Indicates the first i The normalized value of the bearing capacity of the ECC-jacketed composite column. Indicates the first i The normalized value of the cumulative energy dissipation of the ECC jacketed composite column. Indicates the first i The normalized value of the upper limit of residual deformation in the unrepairable section of the ECC jacketed composite column. Indicates the first i The normalized value of the upper limit of residual deformation in the repairable section of the ECC jacketed composite column; The final seismic performance evaluation index for ECC-clad composite columns is the average of the weighted seismic performance coefficients of ECC-clad composite columns obtained under different load application methods, expressed as: ； in, R i The seismic performance evaluation index for ECC-clad composite columns; l for l Different ways of applying loads.

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