Time domain identification method for building structure rigidity eccentric damage detection

Abstract

The invention discloses a time domain identification method for building structure rigidity eccentric damage detection in the technical field of building damage detection, and the method comprises the steps: enabling three sensors to be disposed at two selected measurement points of each floor, and obtaining the horizontal acceleration vibration response of each measurement point; the acceleration response of the mass center of each layer of the structure in the x direction, the y direction and the torsion direction is obtained through the motion relation between the structure measuring point and the mass center; carrying out structure eccentricity calculation by utilizing the improved structure translation-torsion coupling motion equation; determining candidate eccentricity ranges and increments, and determining a series of candidate stiffness center coordinates for each floor; substituting the candidate rigidity center coordinates of each floor into the translation-torsion coupling motion equation, and calculating the residual force of each candidate rigidity center coordinate; calculating the root-mean-square value of the residual force of each candidate stiffness center coordinate; and finding out a candidate rigidity center coordinate with the minimum root mean square value in each floor, namely the rigidity center coordinate of the corresponding floor.

Description

Technical Field

[0001] The invention relates to the technical field of building damage detection, and in particular to a time domain identification method for detecting eccentric damage of building structure stiffness. Background Art

[0002] During ground vibration, torsional vibration of building structures is mainly caused by two factors: the rotational component of ground motion and the misalignment between the center of mass and the center of stiffness. This misalignment causes the inertial force at the center of mass of the structure to exert a torsional moment on the center of stiffness, resulting in translational-torsional coupled vibration of the structure. Ignoring the eccentricity of stiffness will greatly underestimate the dynamic response of the structure to dynamic catastrophic loads, bringing significant risks to the structural safety assessment.

[0003] Existing methods for identifying the rigid center of multi-story buildings can be roughly divided into two categories:

[0004] Simple structures with known structural parameters can estimate their stiffness center through stiffness (flexibility) matrix or stiffness parameters. It can be used to deal with coaxial or non-coaxial (the positions of the stiffness centers of each floor in a multi-story building structure are not on the same vertical axis) stiffness eccentric buildings. Its limitation is that it requires knowing the stiffness parameters of the building structure, which is often not available in actual situations.

[0005] The stiffness center of structures with unknown stiffness parameters can be estimated from experimental data (dynamic response). The coherence function method does not take into account the interaction between structural layers and can only be used to identify single-layer stiffness eccentric structures or multi-layer coaxial stiffness eccentric structures.

[0006] In summary, the existing methods for identifying the rigid center of multi-story buildings have limitations and cannot handle complex structures with non-axial stiffness eccentricity when the structure has unknown stiffness parameters. Summary of the invention

[0007] The purpose of the present invention is to provide a time domain identification method for detecting eccentric damage of building structure stiffness, so as to solve the limitation of the method for identifying the rigid center of multi-story building in the prior art, and the technical problem that it is impossible to handle complex structures with non-axial stiffness eccentricity under the condition that the structure has unknown stiffness parameters.

[0008] In order to solve the above technical problems, the present invention specifically provides a time domain identification method for building structure stiffness eccentric damage detection, comprising the following steps:

[0009] Determining the physical properties of each floor of the building structure, including plan dimensions, mass, moment of inertia, and center of mass position;

[0010] The coordinate origin of each floor is selected at the center of mass of the floor. The dynamic analysis of the eccentric structure with bidirectional non-coaxial stiffness under the excitation of ground acceleration is carried out, and the matrix formula of the structural translation-torsion coupling motion equation is obtained as follows: M, K, and C are the mass matrix, stiffness matrix, and damping matrix of the structure, respectively. Represents the acceleration data in the x-direction, y-direction and torsion direction of the ground, Represents the acceleration data in the x-direction, y-direction and torsional direction at the center of mass of each floor;

[0011] Determine a candidate eccentricity range and increment, and determine a series of candidate stiffness center coordinates for each floor according to the candidate eccentricity range and increment;

[0012] Substituting the coordinates of the candidate stiffness center of each floor into the motion equation to obtain the motion equations in the x-direction and the y-direction, and then substituting the motion equations in the x-direction and the y-direction into the motion equation in the torsion direction to obtain a new equilibrium equation in the torsion direction;

[0013] Calculate the root mean square value of each candidate stiffness center coordinate according to the equilibrium equation of the new torsion direction;

[0014] Find the candidate stiffness center coordinate with the smallest RMS value in each floor, which is the stiffness center coordinate of the corresponding floor.

[0015] As a preferred embodiment of the present invention, for the numerical model of the building structure, a normally distributed random white noise signal with zero homogeneity and unit standard deviation is generated by a computer to simulate ground acceleration excitation;

[0016] Then the Newmark-Beta method is used to directly calculate the acceleration data of the center of mass of each floor in the x direction, y direction and torsional direction.

[0017] As a preferred embodiment of the present invention, for an actual building structure, a horizontal acceleration sensor is used to measure the horizontal acceleration of each floor measuring point in the x direction and the y direction, and then the acceleration of the center of mass of each floor in the x direction, the y direction and the torsional direction is obtained.

[0018] As a preferred embodiment of the present invention, the method of using a horizontal acceleration sensor to measure the horizontal acceleration of each floor measuring point in the x direction and the y direction is:

[0019] Two points are selected horizontally on each floor, one of which is equipped with a horizontal acceleration sensor in the x direction and the y direction, and the other is equipped with a horizontal acceleration sensor in the x direction or the y direction, so as to measure the acceleration data of each floor in the x direction and the y direction.

[0020] As a preferred implementation of the present invention, the measured horizontal acceleration data is subjected to zero mean processing, trend item removal and filtering processing to remove noise and interference, thereby improving recognition accuracy.

[0021] As a preferred implementation of the present invention, the horizontal acceleration sensor on each floor samples two signals in the x direction and the y direction of the ground at an interval of 0.02 seconds and continues sampling for 60 seconds.

[0022] As a preferred embodiment of the present invention, in order to consider the influence of measurement noise on the estimation, the obtained acceleration response is contaminated by Gaussian white noise, wherein the noise power is set to 10% of the original signal power.

[0023] As a preferred implementation manner of the present invention, the candidate eccentricity range is set to -2.5m to 2.5m, with an increment of 0.01m, and each floor has 251001 candidate stiffness center coordinates.

[0024] As a preferred embodiment of the present invention, when the size of the building structure to be identified is large and the lateral stiffness eccentricity accuracy to be identified is fine, the increment setting method is as follows:

[0025] First, set a large increment interval to obtain a candidate stiffness center coordinate group with a larger interval;

[0026] Calculate the root mean square values ​​of the candidate stiffness center coordinate groups with larger intervals one by one;

[0027] Determine the approximate position of the stiffness center based on the RMS value, and reduce the eccentricity range based on the approximate position;

[0028] Then set a small incremental interval, combined with the reduced eccentricity range, to obtain a candidate stiffness center coordinate group with a smaller interval;

[0029] Calculate the root mean square value of the candidate stiffness center coordinate group with smaller intervals one by one;

[0030] When the size of the building structure to be identified is small and the accuracy of the lateral stiffness eccentricity to be identified is not high, the increment setting method is as follows:

[0031] Only one increment interval is set to obtain candidate stiffness center coordinate groups, and the root mean square values ​​of the candidate stiffness center coordinate groups are calculated one by one.

[0032] As a preferred embodiment of the present invention, the equilibrium equations in the x-direction and the y-direction are substituted into the torsion direction to obtain the equilibrium equation of the structure in the new torsion direction:

[0033]

[0034] and It is the acceleration response time history data in the x-direction and y-direction of the ground;

[0035] and is the acceleration data in the x-direction and y-direction at the center of mass of the i-th layer of the structure;

[0036] m i is the mass of the i-th layer;

[0037] I i is the mass moment of inertia of the i-th layer;

[0038] e xi and e yi is the eccentricity of the i-th layer in the x-direction and the y-direction;

[0039] is the acceleration data in the torsion direction at the center of mass of the i-th layer of the structure.

[0040] As a preferred implementation manner of the present invention, the calculation formula of the root mean square value is:

[0041]

[0042] Where n is the number of samples in the analysis time response, j is the parameter at the jth layer, and I j is the mass moment of inertia of the jth layer of the structure, e xj and e yj Respectively represent the eccentricity of the rigid center of the jth layer relative to the center of mass in the x-direction and the y-direction, represents the rigid body rotation angle, represents the translational acceleration of the rigid body in the x direction, Represents the translational acceleration of the rigid body in the y direction.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] The present invention adopts a time domain analysis method to identify the lateral stiffness eccentricity of the building structure, which can avoid errors related to the Fourier transform of the signal, and performs dynamic analysis on the eccentric structure with bidirectional non-coaxial stiffness under environmental excitation. Taking into account the interaction between the layers of the building structure and the flat-torsion coupling effect of the eccentric structure, a motion equation based on the root mean square of the residual force in the time domain dynamic motion equation is proposed, which is used to simultaneously identify the stiffness center of multi-layer non-coaxial eccentric structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0046] Figure 1 It is a schematic diagram of the steps of the time domain stiffness center identification method of the present invention;

[0047] Figure 2 Schematic diagram of residual force of selected coordinate pairs of the first layer of a two-layer shear-type building model in an embodiment of the present invention;

[0048] Figure 3 Schematic diagram of residual force of selected coordinate pairs of the second layer of a two-layer shear-type building model in an embodiment of the present invention;

[0049] Figure 4 for Figure 2 The RMS value of the residual force;

[0050] Figure 5 for Figure 3 The RMS value of the residual force;

[0051] Figure 5 is the residual force of the selected coordinate pair of the second layer of the two-layer shear-type building model in the embodiment of the present invention;

[0052] Figure 6 Schematic diagram of two-dimensional rigid body motion in an embodiment of the present invention;

[0053] Figure 7 Schematic diagram of the evolution of the acceleration relationship between the measuring point and the center of mass in an embodiment of the present invention;

[0054] Figure 8 It is a basic parameter diagram of a two-layer shear-type building model in an embodiment of the present invention. DETAILED DESCRIPTION

[0055] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0056] The present invention specifically provides a time domain identification method for detecting eccentric damage of building structure stiffness, comprising the following steps:

[0057] A time domain identification method for detecting eccentric damage of building structure stiffness comprises the following steps:

[0058] Determining the physical properties of each floor of the building structure, including plan dimensions, mass, moment of inertia, and center of mass position;

[0059] The coordinate origin of each floor is selected at the centroid of the floor. The dynamic analysis of the eccentric structure with bidirectional non-coaxial stiffness under environmental excitation is carried out. According to the dynamic balance, the matrix formula of the structural translation-torsion coupling motion equation is obtained as follows:

[0060] Determine a candidate eccentricity range and increment, and determine a series of candidate stiffness center coordinates for each floor according to the candidate eccentricity range and increment;

[0061] Substituting the coordinates of the candidate stiffness center of each floor into the motion equation to obtain the motion equations in the x-direction and the y-direction, and then substituting the motion equations in the x-direction and the y-direction into the motion equation in the torsion direction to obtain a new equilibrium equation in the torsion direction;

[0062] Calculate the root mean square value of each candidate stiffness center coordinate according to the equilibrium equation in the new torsion direction. The root mean square value is the residual force.

[0063] Find the candidate stiffness center coordinate with the smallest RMS value in each floor, which is the stiffness center coordinate of the corresponding floor;

[0064] In the matrix formula, M, K, and C are the mass matrix, stiffness matrix, and damping matrix of the structure, respectively, and the expressions are as follows:

[0065]

[0066] in:

[0067] M: mass matrix of the entire structure;

[0068] C: damping matrix of the whole structure;

[0069] K: stiffness matrix of the whole structure;

[0070] ü g (t): acceleration data in the x, y and torsion directions of the ground;

[0071] ü(t): acceleration data of the center of mass x, y and torsional directions of each layer of the structure;

[0072] ω1: structural fundamental circular frequency;

[0073] ξ1: Damping ratio corresponding to the fundamental frequency of the structure;

[0074] Mxx : mass matrix in x direction;

[0075] M yy : mass matrix in y direction;

[0076] M θθ : mass moment of inertia matrix;

[0077] m i : The quality of the i-th layer;

[0078] I i : mass moment of inertia of the i-th layer;

[0079] K xx : stiffness matrix in x direction;

[0080] K yy : Stiffness matrix in y direction;

[0081] K θθ : Stiffness matrix in torsion direction;

[0082] K xθ : the translation-torsion coupling stiffness matrix in the x-direction;

[0083] K yθ : the translation-torsion coupling stiffness matrix in the y direction;

[0084] k xi : The stiffness of the structure in the x direction of the i-th layer;

[0085] k yi : The stiffness of the structure in the y direction of the i-th layer;

[0086] e xi : The eccentricity of the structure layer in the x direction;

[0087] e yi : The eccentricity of the i-th layer of the structure in the y direction.

[0088] The environmental excitation refers to ground acceleration excitation, that is, the dynamic response of the structure caused by the action of ground acceleration, that is, the acceleration response and torsional response of the center of mass of each floor in the x-direction and y-direction.

[0089] The present invention adopts a time domain analysis method to identify the lateral stiffness eccentricity of the building structure, which can avoid errors related to the Fourier transform of the signal, and performs dynamic analysis on the eccentric structure with bidirectional non-coaxial stiffness under environmental excitation. Taking into account the interaction between the layers of the building structure and the flat-torsion coupling effect of the eccentric structure, a motion equation based on the root mean square of the residual force in the time domain dynamic motion equation is proposed, which is used to simultaneously identify the stiffness center of multi-layer non-coaxial eccentric structures.

[0090] Furthermore, for the numerical model of the building structure, a normally distributed random white noise signal with zero homogeneity and unit standard deviation is generated by computer to simulate the ground acceleration excitation;

[0091] Then the Newmark-Beta method is used to directly calculate the acceleration response and torsional acceleration response in the x and y directions at the center of mass of each floor.

[0092] For actual building structures, horizontal acceleration sensors are used to measure the horizontal acceleration of each floor's measuring point in the x-direction and y-direction, and then the acceleration of each floor's centroid in the x-direction, y-direction, and torsional direction is obtained. The measurement method is as follows:

[0093] Two points are selected horizontally on each floor, one of which is equipped with a horizontal acceleration sensor in the x direction and the y direction, and the other is equipped with a horizontal acceleration sensor in the x direction or the y direction, so as to measure the acceleration data of each floor in the x direction and the y direction.

[0094] The specific method of coupling is as follows: Figure 6 The schematic diagram of two-dimensional rigid body motion is shown in:

[0095] CM is the mass center and CR is the stiffness center:

[0096]

[0097] Since the floor angle is very small, sin θ ≈ θ, cos θ ≈1 ;

[0098] The equation becomes:

[0099] This gives the kinematic relationship between the center of mass and the center of rigidity of the structure.

[0100] like Figure 7 As shown, according to the acceleration and position of measuring points A and B (A measures the X direction, B measures the X and Y directions), the acceleration relationship between the structural measuring point and the center of mass is obtained:

[0101]

[0102] This is how to couple the horizontal acceleration data of the measuring point to obtain the acceleration data in the three directions of center of mass x, y and torsion.

[0103] Furthermore, the measured horizontal acceleration data is subjected to zero mean processing, trend removal and filtering processing to remove noise and interference, thereby improving recognition accuracy.

[0104] Furthermore, the horizontal acceleration sensors on each floor sample two signals in the x-direction and y-direction of the ground at an interval of 0.02 s and continue sampling for 60 s.

[0105] Furthermore, in order to consider the impact of measurement noise on the estimation, the obtained acceleration response is contaminated by Gaussian white noise, where the noise power is set to 10% of the original signal power.

[0106] Preferably, the candidate eccentricity range is set to -2.5m to 2.5m, with an increment of 0.01m, and each floor has 251001 candidate stiffness center coordinates.

[0107] Furthermore, when the size of the building structure to be identified is large and the lateral stiffness eccentricity accuracy to be identified is fine, the increment setting method is as follows:

[0108] First, set a large increment interval to obtain a candidate stiffness center coordinate group with a larger interval;

[0109] Calculate the root mean square values ​​of the candidate stiffness center coordinate groups with larger intervals one by one;

[0110] Determine the approximate position of the stiffness center based on the RMS value, and reduce the eccentricity range based on the approximate position;

[0111] Then set a small incremental interval, combined with the reduced eccentricity range, to obtain a candidate stiffness center coordinate group with a smaller interval;

[0112] Calculate the root mean square value of the candidate stiffness center coordinate group with smaller intervals one by one;

[0113] When the size of the building structure to be identified is small and the accuracy of the lateral stiffness eccentricity to be identified is not high, the increment setting method is as follows:

[0114] Only one increment interval is set to obtain candidate stiffness center coordinate groups, and the root mean square values ​​of the candidate stiffness center coordinate groups are calculated one by one.

[0115] Furthermore, the equilibrium equations in the x-direction and y-direction (i.e., the above-mentioned translation-torsion coupling motion equations) are substituted into the torsion direction to obtain the equilibrium equation of the new torsion direction of the building structure:

[0116] For the first layer:

[0117] For the i-th layer (middle layer):

[0118] For the top layer:

[0119] Substituting the above formulas for the x-direction and y-direction of each layer into the twist direction, we get the following formula:

[0120]

[0121] and It is the acceleration response time history data in the x-direction and y-direction of the ground;

[0122] and is the acceleration data in the x-direction and y-direction at the mass center of the i-th layer of the structure;

[0123] m i is the mass of the i-th layer;

[0124] I i is the mass moment of inertia of the i-th layer;

[0125] e xi and e yi is the eccentricity of the i-th layer in the x-direction and the y-direction;

[0126] is the acceleration data in the torsion direction at the center of mass of the i-th layer of the structure.

[0127] Furthermore, the calculation formula of the root mean square value is:

[0128]

[0129] Where n is the number of samples in the analysis time response, and j is the parameter at the jth layer. j is the mass moment of inertia of the jth layer of the structure, e xj and e yj Respectively represent the eccentricity of the rigid center of the jth layer relative to the center of mass in the x-direction and the y-direction, represents the rigid body rotation angle, represents the acceleration of the rigid body in the x direction, Represents the translational acceleration of the rigid body in the y direction.

[0130] The following is a detailed description of the specific method of time domain analysis to identify the lateral stiffness eccentricity of building structures. Here, a two-story shear building model with bidirectional lateral stiffness eccentricity is taken as an example:

[0131] 1) Obtain the basic parameters of the building structure, the plane dimensions of the first and second floors, the mass of each floor, the mass moment of inertia of each floor, the position of the center of mass of the first and second floors, the lateral stiffness of the first and second floors in the x and y directions, the stiffness center coordinates of the first floor, the mass center coordinates of the second floor, and the specific parameters of the model are shown in Figure 8 Table in. Stiffness proportional damping, the damping ratio of the fundamental mode is taken as 0.05.

[0132] It should be noted that the basic parameters obtained here include the parameters of the numerical model and the actual building. The lateral stiffness used here is set in the numerical model to obtain the acceleration response in three directions at the center of mass of each layer of the structure. This is the physical parameter of the structure in the numerical model. The acceleration response at the center of mass of each layer of the structure can be obtained through the perfect physical parameters of the structure in the numerical model and the acceleration excitation of the ground. However, when the acceleration response is used to identify the eccentricity of the structure in the future, the lateral stiffness parameter is not used in the motion equation. That is, if for an actual structure, the acceleration response at the center of mass of each layer can be obtained through the response of the measuring point, after obtaining the acceleration at the center of mass, it is brought into the motion equation (this motion equation does not need to input the lateral stiffness parameter) to obtain the eccentricity of each layer. In short, it is not necessary to know the lateral stiffness to identify the eccentricity of each layer of the structure. The lateral stiffness mentioned here is only for calculating the acceleration of the center of mass of each layer of the structure in the numerical model, but it can actually be obtained through measurement.

[0133] 2) For actual structures, acceleration sensors are arranged at selected locations on each floor. Specifically, two points (denoted as A and B) are selected on each floor, and sensors are installed at these two points to measure the acceleration in the x and y directions. The sensor layout needs to ensure that the vibration response of the structure can be fully captured.

[0134] 3) For the numerical model, a computer generates a normally distributed random white noise signal with a mean of zero and a unit standard deviation to simulate the environmental acceleration of the ground. The two signals in the x and y directions of the ground are sampled at intervals of 0.02s and last for 60s. The Newmark-Beta method is used to calculate the acceleration response in the x and y directions and the acceleration response in the torsional direction at the center of mass of the top plate of the structure. In order to consider the impact of measurement noise on the estimation, the acceleration response obtained above is contaminated by Gaussian white noise, where the noise power is set to 10% of the original signal power.

[0135] 4) The origin of the coordinate system for the first and second floors is set at the mass center of the respective floor slabs. The eccentricity range studied for each floor in the x and y directions is from -2.5m to 2.5m with an increment of 0.01m. There are 251,001 pairs of coordinates to be analyzed when finding the stiffness center of each floor. Each pair of candidate functions is substituted into the equation of motion to obtain the residual force value.

[0136] 5) Figure 4 and Figure 5 The RMS values ​​of the residual forces for ply 1 and ply 2 are given for different coordinate pairs. The results show that they vary slowly with a single curvature within the studied eccentricity range. This indicates that the heuristic method used in the direct analysis can obtain the true coordinates of the stiffness center.

[0137] Figure 2 and Figure 3Represent the residual force of the selected coordinate pair. The red line at the back of the figure has the smallest change and is close to zero, which is considered to be related to the true coordinate pair of the stiffness center. The RMS values ​​of the residual forces of the 1st and 2nd layer calculation results with and without noise are (4.36N·m, 8.76N·m) and (0.19N·m, 0.26N·m), respectively. Note that the presence of noise will significantly affect the RMS value of the residual force.

[0138] 6) The eccentricity resolution of this study is 0.01 m. Since the RMS value of the residual force varies monotonically with the coordinate pair, a more efficient search technique can be used to consider candidate coordinate pairs selected at larger intervals, such as 0.1 m, to obtain the same Figure 3 A similar set of results is then obtained. The approximate location of the center of rigidity is then determined in a similar manner. Another set of candidate coordinate pairs is then selected with finer increments of 0.01 m or less to calculate the RMS value of the residual force in the formula. This process can be adjusted and repeated to meet any specified resolution accuracy requirement for the location of the center of rigidity.

[0139] The above embodiments are only exemplary embodiments of the present application and are not intended to limit the present application. The protection scope of the present application is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present application within the essence and protection scope of the present application, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present application.

Claims

1. A time domain identification method for detecting eccentric damage of building structure stiffness, characterized in that: The following steps are involved: Determine the physical properties of each floor of the building structure, including plan dimensions, mass, moment of inertia, and center of mass location; The center of mass of each floor is selected as the coordinate origin of the floor, and the dynamic analysis of the eccentric structure with bidirectional non-coaxial stiffness under the excitation of ground acceleration is carried out. The matrix formula of the structural translation-torsion coupling motion equation is obtained as follows: M, K, and C are the mass matrix, stiffness matrix, and damping matrix of the structure, respectively. g (t) represents the acceleration response time history data in the x-direction, y-direction and torsion direction of the ground, and ü(t) represents the acceleration data in the x-direction, y-direction and torsion direction at the center of mass of each floor; Determine a candidate eccentricity range and increment, and determine a series of candidate stiffness center coordinates for each floor according to the candidate eccentricity range and increment; Substituting the coordinates of the candidate stiffness center of each floor into the motion equation to obtain the motion equations in the x-direction and the y-direction, and then substituting the motion equations in the x-direction and the y-direction into the motion equation in the torsion direction to obtain a new equilibrium equation in the torsion direction; Calculate the root mean square value of each candidate stiffness center coordinate according to the equilibrium equation of the new torsion direction; Find the candidate stiffness center coordinate with the smallest RMS value in each floor, which is the stiffness center coordinate of the corresponding floor.

2. A time domain identification method for detecting eccentric damage of building structure stiffness according to claim 1, characterized in that: For the numerical model of the building structure, a computer is used to generate a normal distribution random white noise signal with zero homogeneity and unit standard deviation to simulate the ground acceleration excitation; Then the Newmark-Beta method is used to directly calculate the acceleration data of the center of mass of each floor in the x-direction, y-direction and torsion direction; To account for the effect of measurement noise on the estimation, the obtained acceleration responses are contaminated with Gaussian white noise, where the noise power is set to 10% of the original signal power.

3. A time domain identification method for detecting eccentric damage of building structure stiffness according to claim 1, characterized in that: For actual building structures, horizontal acceleration sensors are used to measure the horizontal acceleration of each floor measuring point in the x and y directions, and then the acceleration of the center of mass of each floor in the x, y and torsional directions is obtained.

4. A time domain identification method for detecting eccentric damage of building structure stiffness according to claim 3, characterized in that: The method of using horizontal acceleration sensors to measure the horizontal acceleration of each floor point in the x-direction and y-direction is as follows: Two points are selected horizontally on each floor, one of which is equipped with a horizontal acceleration sensor in the x direction and the other is equipped with a horizontal acceleration sensor in the x direction or the y direction, so as to measure the acceleration data of each measuring point on each floor in the x direction and the y direction.

5. A time domain identification method for detecting eccentric damage of building structure stiffness according to claim 4, characterized in that: The measured horizontal acceleration data are processed by zero mean, trend removal and filtering to remove noise and interference, thereby improving the recognition accuracy.

6. A time domain identification method for detecting eccentric damage to building structure stiffness according to claim 4, characterized in that: The horizontal acceleration sensors on each floor sample two signals in the x and y directions of the ground at an interval of 0.02s and continue sampling for 60s.

7. A time domain identification method for detecting eccentric damage of building structure stiffness according to claim 1, characterized in that: The candidate eccentricity range is set to -2.5m to 2.5m with an increment of 0.01m, and each floor has 251001 candidate stiffness center coordinates.

8. The time domain identification method for detecting eccentric damage of building structure stiffness according to claim 1, characterized in that: When the size of the building structure to be identified is large and the lateral stiffness eccentricity accuracy to be identified is fine, the increment setting method is as follows: First, set a large increment interval to obtain a candidate stiffness center coordinate group with a larger interval; Calculate the root mean square values ​​of the candidate stiffness center coordinate groups with larger intervals one by one; Determine the approximate position of the stiffness center based on the RMS value, and reduce the eccentricity range based on the approximate position; Then set a small incremental interval, combined with the reduced eccentricity range, to obtain a candidate stiffness center coordinate group with a smaller interval; Calculate the root mean square value of the candidate stiffness center coordinate group with smaller intervals one by one; When the size of the building structure to be identified is small and the accuracy of the lateral stiffness eccentricity to be identified is not high, the increment setting method is as follows: Only one increment interval is set to obtain candidate stiffness center coordinate groups, and the root mean square values ​​of the candidate stiffness center coordinate groups are calculated one by one.

9. The time domain identification method for detecting eccentric damage of building structure stiffness according to claim 1, characterized in that: The equilibrium equation for the new torsion direction is: and It is the acceleration response time history data in the x-direction and y-direction of the ground; and is the acceleration data in the x-direction and y-direction at the mass center of the i-th layer of the structure; m i is the mass of the i-th layer; I i is the mass moment of inertia of the i-th layer; e xi and e yi is the eccentricity of the i-th layer in the x-direction and the y-direction; is the acceleration data in the torsion direction at the center of mass of the i-th layer of the structure.

10. A time domain identification method for detecting eccentric damage of building structure stiffness according to claim 9, characterized in that: The calculation formula of the root mean square value is: Where n is the number of samples in the analysis time response, j is the parameter at the jth layer, and I j is the mass moment of inertia of the jth layer of the structure, e xj and e yj Respectively represent the eccentricity of the rigid center of the jth layer relative to the center of mass in the x-direction and the y-direction, represents the rigid body rotation angle, represents the translational acceleration of the rigid body in the x direction, Represents the translational acceleration of the rigid body in the y direction.

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