Friction pendulum shock insulation support and monitoring method thereof

Abstract

The invention discloses a friction pendulum shock insulation support and a monitoring method thereof. The friction pendulum shock insulation support comprises an upper seat plate; a lower seat plate; the spherical crown sliding block is arranged between the upper seat plate and the lower seat plate; the polytetrafluoroethylene friction plates are arranged at the upper end and the lower end of the spherical crown sliding block; and the sensing mechanism is arranged between the lower seat plate and the teflon friction plate below the lower seat plate, or is arranged between the lower seat plate and the teflon friction plate below the lower seat plate and between the upper seat plate and the teflon friction plate above the upper seat plate. The friction pendulum shock insulation support has the following advantages and effects that a sensing module of the whole friction pendulum shock insulation support is formed by adopting an external resistance type sensing mechanism, the comprehensive monitoring function is achieved, data such as horizontal displacement and vertical pressure can be obtained in real time, the real-time displacement and compressive stress distribution condition of the spherical crown sliding block can be mastered, and the safety and reliability of the friction pendulum shock insulation support are improved. Therefore, the use condition of the friction pendulum shock insulation support is evaluated, dynamic monitoring support is provided for structural safety, whether the spherical crown sliding block slides to a dangerous area or not is conveniently judged, and fine management of the structure is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of civil engineering seismic isolation, and in particular to a friction pendulum seismic isolation support and a monitoring method thereof. Background Art

[0002] The friction pendulum isolation bearing is a device used in the seismic design of building structures. Its main function is to convert the horizontal displacement caused by the earthquake into relative slip inside the device through the sliding friction behavior of the ball cap slider, thereby reducing the seismic effect on the superstructure and improving the safety and durability of the building. The design of this bearing is inspired by the principle of the pendulum, that is, using swinging to consume or transfer seismic energy, thereby reducing the energy transmitted to the superstructure.

[0003] The friction pendulum isolation bearing is mainly composed of an upper bearing plate, a lower bearing plate, an intermediate sliding layer (usually polytetrafluoroethylene or other low-friction materials) and a lateral limiter. When an earthquake occurs, the bearing allows the building to move horizontally to a limited extent, consuming the seismic energy through the friction of the sliding layer. At the same time, the lateral limiter limits the maximum displacement of the building to prevent it from shaking excessively and causing damage.

[0004] The long-term stability of the friction pendulum isolation bearing is of great significance to the overall safety of the building. However, the performance monitoring of the friction pendulum isolation bearing is still a difficult problem in the current field of seismic isolation technology. At present, the stress monitoring of the bearing has certain limitations because the building structure still bears huge vertical loads during an earthquake, and the local stress condition of the spherical cap cannot be evaluated in real time.

[0005] At the same time, real-time displacement monitoring of the bearing during an earthquake is also a difficult problem. If the displacement of the bearing in two directions in the horizontal plane is to be monitored in real time and errors caused by bearing torsion are to be avoided, the cost is high and the installation is complicated. It is also impossible to determine whether the spherical crown has slipped to the dangerous area, and the actual use status of the bearing cannot be evaluated in real time, thus making it impossible to achieve refined management of the structure. This needs to be improved. Summary of the invention

[0006] In view of the deficiencies in the prior art, an object of the present invention is to provide a friction pendulum seismic isolation bearing which has the effect of finely managing the structure.

[0007] The above technical objectives of the present invention are achieved through the following technical solutions: A friction pendulum isolation support, comprising:

[0008] The upper seat plate is horizontally arranged, and the lower end surface is arranged in an arc shape;

[0009] The lower seat plate is horizontally arranged, and the upper end surface is arranged in an arc shape;

[0010] A ball crown slider is arranged between the upper seat plate and the lower seat plate;

[0011] PTFE friction plates are arranged at the upper and lower ends of the ball crown slider;

[0012] A sensing mechanism is arranged between the lower seat plate and the polytetrafluoroethylene friction plate below the ball crown slider, or between the lower seat plate and the polytetrafluoroethylene friction plate below the ball crown slider and between the upper seat plate and the polytetrafluoroethylene friction plate above the ball crown slider;

[0013] The sensing mechanism includes a thin film varistor, an inert protective layer and a stainless steel plate. The thin film varistor is arranged horizontally, the inert protective layer is arranged at the upper and lower ends of the thin film varistor, and the stainless steel plate is arranged above the upper inert protective layer.

[0014] Another object of the present invention is to provide a method for monitoring a friction pendulum isolation bearing, which has the effect of finely managing the structure.

[0015] The above technical objectives of the present invention are achieved through the following technical solutions: A monitoring method for a friction pendulum isolation bearing, wherein the contact surface between the ball crown slider and the sensor mechanism is circular, and the applied stress is continuous along the radial direction, that is, there is no concentrated shear stress on the contact surface, and the calculation process includes the following steps:

[0016] S1, obtain the measuring point data. The sensor mechanism is used to measure the normal stress by a series of small measuring points. The measured values ​​of these measuring points are regarded as the average stress of the area around the measuring points. The position of each measuring point is (r i ,θ i ,σ i ), where r i and θ i are the polar coordinate positions of the measuring points on the entire contact circle, σ i is the stress value measured at the corresponding position;

[0017] S2, fitting stress distribution function, performs fitting calculation based on the data of each measuring point to obtain the approximate stress distribution function of the contact surface. The fitted stress distribution function is:

[0018] σ(r,θ)≈f(r,θ);

[0019] Where f(r,θ) is the stress distribution function after three-dimensional fitting, which is used to represent the stress distribution of the entire contact area. The output three-dimensional stress distribution cloud map can be used for bearing status monitoring;

[0020] S3, function integration, according to the stress distribution function f(r,θ), the total pressure can be calculated by the following integral formula:

[0021]

[0022] Where R is the radius of the contact circle. Similarly, the integration of the two-dimensional stress distribution function of each column is the total pressure F2, and the average value is taken with the above total pressure to obtain the final value;

[0023] S4, numerical integration. If the stress distribution function f(r,θ) is very complex and difficult to be directly integrated, the integration is performed by using a refined numerical method to discretize the contact circle into fine grids, each with an area of ​​r. i ΔrΔθ, the spacing between adjacent grid center points is at least one order of magnitude smaller than the spacing between adjacent measuring points, then the approximate calculation formula for total pressure is:

[0024]

[0025] Where N is the total number of discrete grids, Δr and Δθ are the discrete intervals in the radial and angular directions respectively;

[0026] S5, support force calculation, the support vertical pressure calculation formula is:

[0027] N = Fcosα;

[0028] Among them, α is the inclination angle of the bearing spherical crown;

[0029] S6, bearing displacement calculation, the measurement range of the positioning mechanism is the friction surface of the upper and lower bearings, which is a circular surface. After the spherical cap slider is compressed, the circular surface that displays the stress distribution data in the entire measurement circular surface is the contact circular surface of the spherical cap slider. The display cloud map is fitted to form a circular function to express the contact surface of the spherical cap slider, and the center point of the circular function (r c ,θ c ,σ c ), the displacement of the ball cap slider relative to the upper and lower supports is:

[0030] Δ1=r c1 , Δ2=r c2 ;

[0031] If the sensor mechanism is only set on the lower seat plate, the support displacement is calculated by the following formula:

[0032] Δ=2r c2 ;

[0033] If sensing mechanisms are installed on both the upper and lower supports, the support displacement is calculated by the following formula:

[0034] Δ=r c1 +r c2 ;

[0035] On the force cloud diagram of the sensing mechanism, the current displacement of the spherical crown slider and the historical displacement dynamic data can be automatically displayed through program calculation, recorded and saved, and then uploaded to the cloud, so as to realize real-time health monitoring of the friction pendulum isolation bearing.

[0036] In a preferred example, the present invention can be further configured as follows: In step S2: the function fitting calculation method is as follows:

[0037] A1: Through the measurement point data of each row with the same y coordinate, the fitting calculation is performed on the data of each row to obtain the stress distribution two-dimensional function of the same y coordinate. Assume that the measurement point data of the jth row is (x i ,σ y (x i ,y j )), where x i is the x-coordinate of the j-th row measurement point, σ(x i ,y j ) is the corresponding stress data, which is obtained by fitting and calculating using linear interpolation, polynomial regression, and spline interpolation methods:

[0038] σ y (x i ,y j )≈f y (x i ,y j );

[0039] A2: The fitting results for each row can be obtained in the following form:

[0040] σ(x,y j )≈f j (x);

[0041] Among them, f j (x) is the stress distribution function of the jth row. The stress distribution function fitting results of each row are interpolated and fitted. Through bilinear interpolation and spline interpolation methods, the stress distribution function on the entire contact circle surface can be obtained:

[0042] σ(x,y)≈f(y)(x)=f(r,θ);

[0043] Among them, f(y)(x) reflects the change of stress in the x direction with the y coordinate.

[0044] In a preferred example, the present invention can be further configured as follows: in the fitting calculation method A1 of step S2, the stress distribution function f on the jth row of the contact circle surface is obtained j (x), is a two-dimensional curve function, and the evaluation indicators are the following three points:

[0045] First, local stress extreme value: the peak value of the curve function is the maximum value of the local stress, reflecting the maximum stress borne by a certain point on the ball cap slider. The extreme point is found by calculating the derivative of the curve function, and the maximum value of the extreme points of each row of the curve function is selected as the stress peak value of the entire circular surface. The size of the peak value determines the stress concentration degree of the ball cap slider material at a certain point, which is used to judge whether the local position is close to the yield or failure limit of the contact surface material;

[0046] The second point, stress eccentricity: the peak point abscissa x of the defined curve function peak , which is the eccentricity of the peak point in the jth row, is used to describe the eccentricity of the jth row. The larger the eccentricity, the greater the eccentricity of the stress distribution, which may lead to structural instability.

[0047] The third point is distribution uniformity: calculate the coefficient of variation CV of the stress values ​​of each measuring point in the jth row, that is, the ratio of the standard deviation to the mean value to measure the uniformity of the stress distribution on the spherical cap. The larger the CV value, the more uneven the stress distribution. When CV tends to 0, it means that the stress distribution on the surface of the spherical cap slider is basically uniform, and there is no local stress protrusion on the material surface.

[0048] In summary, the present invention has the following beneficial effects: by adopting an external resistive sensing mechanism to form a sensing module of the entire friction pendulum isolation bearing, it has a comprehensive monitoring function, can obtain horizontal displacement, vertical pressure and other data in real time, and can grasp the real-time displacement and compressive stress distribution of the ball crown slider, and then evaluate the use status of the friction pendulum isolation bearing, provide dynamic monitoring support for structural safety, and facilitate judgment of whether the ball crown slider slides to a dangerous area, thereby realizing refined management of the structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 Schematic diagram of two layout modes of the sensor mechanism of Example 1;

[0050] Figure 2 is a schematic structural diagram of the sensing mechanism of Example 1;

[0051] Figure 3 is a schematic diagram of the support subjected to the resultant force in Example 2;

[0052] Figure 4 is a schematic diagram of the compressive fitting stress distribution of Example 2;

[0053] Figure 5 It is the two-dimensional stress distribution function curve of the jth row.

[0054] Figure numerals: 1. upper seat plate; 2. lower seat plate; 3. ball crown slider; 4. polytetrafluoroethylene friction plate; 5. sensing mechanism; 51. thin film varistor; 52. inert protective layer; 53. stainless steel plate. DETAILED DESCRIPTION

[0055] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0056] Embodiment 1:

[0057] like Figure 1 As shown, a friction pendulum seismic isolation support includes an upper seat plate 1, a lower seat plate 2, a ball crown slider 3, a polytetrafluoroethylene friction plate 4 and a sensor mechanism 5.

[0058] like Figure 1 As shown, the upper seat plate 1 and the lower seat plate 2 are both arranged horizontally, the lower end surface of the upper seat plate 1 is arranged in an arc shape, and the upper end surface of the lower seat plate 2 is arranged in an arc shape, and the arc surfaces of the upper seat plate 1 and the lower seat plate 2 are arranged relative to each other and interlocked.

[0059] like Figure 1 As shown, the ball crown slider 3 is arranged between the upper seat plate 1 and the lower seat plate 2, and the polytetrafluoroethylene friction plate 4 is arranged at the upper and lower ends of the ball crown slider 3. The sensing mechanism 5 is arranged between the lower seat plate 2 and the polytetrafluoroethylene friction plate 4 below the ball crown slider 3, or between the lower seat plate 2 and the polytetrafluoroethylene friction plate 4 below the ball crown slider 3 and between the upper seat plate 1 and the polytetrafluoroethylene friction plate 4 above the ball crown slider 3.

[0060] like Figure 2 As shown, the sensing mechanism 5 includes a thin film varistor 51, an inert protective layer 52 and a stainless steel plate 53. The thin film varistor 51 is horizontally arranged, and the inert protective layer 52 is arranged at the upper and lower ends of the thin film varistor 51. The inert protective layer 52 adopts a protective film material of PC, PET and other materials. The stainless steel plate 53 is arranged above the upper inert protective layer 52.

[0061] When the sensing mechanism 5 is subjected to stress, the thin film varistor 51 is compressed and causes a change in resistance value, thereby causing the output voltage to transmit a change signal for collection and output. In addition, due to the inert protective layer 52, the corrosion resistance and water resistance of the sensing mechanism 5 will meet the requirements of the engineering application environment.

[0062] Therefore, by adopting the external resistance type sensing mechanism 5 to form the sensing module of the entire friction pendulum isolation support, it has a comprehensive monitoring function, can obtain horizontal displacement, vertical pressure and other data in real time, and has a stress-force-displacement integrated monitoring function.

[0063] It can also grasp the real-time displacement and compressive stress distribution of the ball crown slider 3, and then evaluate the use status of the friction pendulum isolation bearing, provide dynamic monitoring support for structural safety, and facilitate judgment on whether the ball crown slider 3 slides to the dangerous area, thereby realizing refined management of the structure.

[0064] Embodiment 2:

[0065] like Figure 3 , Figure 4 , Figure 5 As shown, a monitoring method for a friction pendulum isolation bearing is shown, the contact surface between the ball cap slider 3 and the sensor mechanism 5 is circular, and the applied stress is continuous along the radial direction, that is, there is no concentrated shear stress on the contact surface. The calculation process includes the following steps:

[0066] S1, obtain the measuring point data. The sensor mechanism 5 is used to measure the normal stress by a series of small measuring points. The measured values ​​of these measuring points are regarded as the average stress of the area around the measuring points. The position of each measuring point is (r i ,θ i ,σ i ), where r i and θ i are the polar coordinate positions of the measuring points on the entire contact circle, σ i is the stress value measured at the corresponding position.

[0067] S2, fitting stress distribution function, performs fitting calculation based on the data of each measuring point to obtain the approximate stress distribution function of the contact surface. The fitted stress distribution function is:

[0068] σ(r,θ)≈f(r,θ);

[0069] Among them, f(r,θ) is the stress distribution function after three-dimensional fitting, which is used to represent the stress distribution of the entire contact area. The output three-dimensional stress distribution cloud map can be used for support status monitoring.

[0070] The function fitting calculation method is as follows:

[0071] A1: Through the measurement point data of each row with the same y coordinate, the fitting calculation is performed on the data of each row to obtain the stress distribution two-dimensional function of the same y coordinate. Assume that the measurement point data of the jth row is (x i ,σ y (x i ,y j )), where x i is the x-coordinate of the j-th row measurement point, σ(x i ,y j ) is the corresponding stress data, which is obtained by fitting and calculating using linear interpolation, polynomial regression, and spline interpolation methods:

[0072] σ y (x i ,y j )≈f y (x i ,y j );

[0073] A2: The fitting results for each row can be obtained in the following form:

[0074] σ(x,y j )≈f j (x);

[0075] Among them, f j (x) is the stress distribution function of the jth row. The stress distribution function fitting results of each row are interpolated and fitted. Through bilinear interpolation and spline interpolation methods, the stress distribution function on the entire contact circle surface can be obtained:

[0076] σ(x,y)≈f(y)(x)=f(r,θ);

[0077] Among them, f(y)(x) reflects the change of stress in the x direction with the y coordinate.

[0078] In the fitting calculation method A1 of step S2, the stress distribution function f of the jth row on the contact circle surface is obtained. j (x), is a two-dimensional curve function, and the evaluation indicators are the following three points:

[0079] First, local stress extreme value: The peak value of the curve function is the maximum value of the local stress, which reflects the maximum stress borne by a certain point on the ball cap slider 3. The extreme point is found by calculating the derivative of the curve function, and the maximum value of the extreme points of each row of the curve function is selected as the stress peak value of the entire circular surface. The size of the peak value determines the stress concentration degree of the ball cap slider 3 material at a certain point, which is used to judge whether the local position is close to the yield or failure limit of the contact surface material;

[0080] The second point, stress eccentricity: the peak point abscissa x of the defined curve function peak , which is the eccentricity of the peak point in the jth row, is used to describe the eccentricity of the jth row. The larger the eccentricity, the greater the eccentricity of the stress distribution, which may lead to structural instability.

[0081] The third point is distribution uniformity: calculate the coefficient of variation CV of the stress values ​​of each measuring point in the jth row, that is, the ratio of the standard deviation to the mean value to measure the uniformity of the stress distribution on the spherical cap. The larger the CV value, the more uneven the stress distribution. When CV tends to 0, it means that the stress distribution on the surface of the spherical cap slider 3 is basically uniform, and there is no local stress protrusion on the material surface.

[0082] S3, function integration, according to the stress distribution function f(r,θ), the total pressure can be calculated by the following integral formula:

[0083]

[0084] Among them, R is the radius of the contact circle. Similarly, the combination and integration of the two-dimensional stress distribution function of each column is the total pressure F2, and the average value is taken with the above total pressure to obtain the final value.

[0085] S4, numerical integration. If the stress distribution function f(r,θ) is very complex and difficult to be directly integrated, the integration is performed by using a refined numerical method to discretize the contact circle into fine grids, each with an area of ​​r. i ΔrΔθ, the spacing between adjacent grid center points is at least one order of magnitude smaller than the spacing between adjacent measuring points, then the approximate calculation formula for total pressure is:

[0086]

[0087] Where N is the total number of discrete grids, Δr and Δθ are the discrete intervals in the radial and angular directions, respectively.

[0088] S5, support force calculation, the support vertical pressure calculation formula is:

[0089] N = Fcosα;

[0090] Where α is the inclination angle of the bearing spherical crown.

[0091] S6, bearing displacement calculation, the measurement range of the positioning mechanism is the friction surface of the upper and lower bearings, which is a circular surface. After the spherical cap slider is compressed, the circular surface that displays the stress distribution data in the entire measurement circular surface is the contact circular surface of the spherical cap slider. The display cloud map is fitted to form a circular function to express the contact surface of the spherical cap slider, and the center point of the circular function (r c ,θ c ,σ c ), the displacement of the ball cap slider relative to the upper and lower supports is:

[0092] Δ1=r c1 , Δ2=r c2 ;

[0093] If the sensor mechanism is only set on the lower seat plate, the support displacement is calculated by the following formula:

[0094] Δ=2r c2 ;

[0095] If sensing mechanisms are installed on both the upper and lower supports, the support displacement is calculated by the following formula:

[0096] Δ=t c1 +r c2 ;

[0097] On the force cloud diagram of the sensor mechanism 5, the current displacement and historical displacement dynamic data of the ball crown slider can be automatically displayed through program calculation, and then uploaded to the cloud after being recorded and saved, so as to realize real-time health monitoring of the friction pendulum isolation bearing.

[0098] The specific embodiments are merely explanations of the present invention and are not limitations of the present invention. After reading this specification, those skilled in the art may make modifications to the embodiments without any creative contribution as needed. However, such modifications are protected by the patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A friction pendulum isolation support, characterized in that: include: The upper seat plate (1) is arranged horizontally, and the lower end surface is arranged in an arc shape; The lower seat plate (2) is arranged horizontally, and the upper end surface is arranged in an arc shape; A ball crown slider (3) is arranged between the upper seat plate (1) and the lower seat plate (2); Polytetrafluoroethylene friction plates (4) are arranged at the upper and lower ends of the ball crown slider (3); A sensing mechanism (5) is arranged between the lower seat plate (2) and the polytetrafluoroethylene friction plate (4) below the spherical crown slider (3), or between the lower seat plate (2) and the polytetrafluoroethylene friction plate (4) below the spherical crown slider (3) and between the upper seat plate (1) and the polytetrafluoroethylene friction plate (4) above the spherical crown slider (3); The sensing mechanism (5) comprises a thin film varistor (51), an inert protective layer (52) and a stainless steel plate (53); the thin film varistor (51) is arranged horizontally, the inert protective layer (52) is arranged at the upper and lower ends of the thin film varistor (51), and the stainless steel plate (53) is arranged above the upper inert protective layer (52).

2. A method for monitoring a friction pendulum isolation support, characterized in that: The contact surface between the ball cap slider (3) and the sensor mechanism (5) is circular, and the applied stress is continuous along the radial direction, that is, there is no concentrated shear stress on the contact surface. The calculation process includes the following steps: S1, obtaining the measuring point data. The sensor mechanism (5) is provided with a series of small measuring points for measuring the normal stress. The measured values ​​of these measuring points are regarded as the average stress of the area around the measuring points. The position of each measuring point is (r i ,θ i ,σ i ), where r i and θ i are the polar coordinate positions of the measuring points on the entire contact circle, σ i is the stress value measured at the corresponding position; S2, fitting stress distribution function, performs fitting calculation based on the data of each measuring point to obtain the approximate stress distribution function of the contact surface. The fitted stress distribution function is: σ(r,θ)≈f(r,θ); Where f(r,θ) is the fitted three-dimensional stress distribution function, which is used to represent the stress distribution of the entire contact area. The output three-dimensional stress distribution cloud map can be used for bearing status monitoring; S3, function integration, according to the stress distribution function f(r,θ), the total pressure can be calculated by the following integral formula: Where R is the radius of the contact circle. Similarly, the integration of the two-dimensional stress distribution function of each column is the total pressure F2, and the average value is taken with the above total pressure to obtain the final value; S4, numerical integration. If the stress distribution function f(r,θ) is very complex and difficult to be directly integrated, the integration is performed by using a refined numerical method to discretize the contact circle into fine grids, each with an area of ​​r. i ΔrΔθ, the spacing between adjacent grid center points is at least one order of magnitude smaller than the spacing between adjacent measuring points, then the approximate calculation formula for total pressure is: Where N is the total number of discrete grids, Δr and Δθ are the discrete intervals in the radial and angular directions respectively; S5, support force calculation, the support vertical pressure calculation formula is: N = Fcosα; Among them, α is the inclination angle of the bearing spherical crown; S6, bearing displacement calculation, the measurement range of the positioning mechanism is the friction surface of the upper and lower bearings, which is a circular surface. After the spherical cap slider (3) is compressed, the circular surface that displays the stress distribution data in the entire measurement circular surface is the contact circular surface of the spherical cap slider (3). The display cloud map is fitted to form a circular function to express the contact surface of the spherical cap slider (3), and the center point of the circular function (r c ,θ c ,σ c ), the displacement of the ball crown slider (3) relative to the upper and lower supports is: Δ1=r c1 ,Δ2=r c2 If the sensor mechanism (5) is only provided on the lower seat plate, the displacement of the support is calculated by the following formula: Δ=2r c2 ; If the sensor mechanism (5) is provided on both the upper and lower supports, the support displacement is calculated by the following formula: Δ=r c1 +r c2 ; On the force cloud diagram of the sensor mechanism (5), the current displacement and historical displacement dynamic data of the spherical crown slider (3) can be automatically displayed through program calculation, recorded and saved, and then uploaded to the cloud, so as to realize real-time health monitoring of the friction pendulum isolation bearing.

3. The method for monitoring a friction pendulum isolation bearing according to claim 2, characterized in that: In step S2: the function fitting calculation method is as follows: A1: Through the measurement point data of each row with the same y coordinate, the fitting calculation is performed on the data of each row to obtain the stress distribution two-dimensional function of the same y coordinate. Assume that the measurement point data of the jth row is (x i ,σ y (x i ,y j )), where x i is the x-coordinate of the j-th row measurement point, σ(x i ,y j ) is the corresponding stress data, which is obtained by fitting and calculating using linear interpolation, polynomial regression, and spline interpolation methods: σ y (x i ,and j )≈f y (x i ,and j ); A2: The fitting results for each row can be obtained in the following form: σ(x,y j )≈f j (x); Among them, f j (x) is the stress distribution function of the jth row. The stress distribution function fitting results of each row are interpolated and fitted. Through bilinear interpolation and spline interpolation methods, the stress distribution function on the entire contact circle surface can be obtained: σ(x,y)≈f(y)(x)=f(r,θ); Among them, f(y)(x) reflects the change of stress in the x direction with the y coordinate.

4. The method for monitoring a friction pendulum isolation bearing according to claim 3 is characterized in that: In the fitting calculation method A1 of step S2, the stress distribution function f of the jth row on the contact circle surface is obtained. j (x), is a two-dimensional curve function, and the evaluation indicators are the following three points: First, local stress extreme value: the peak value of the curve function is the maximum value of the local stress, reflecting the maximum stress borne by a certain point on the spherical cap slider (3). The extreme point is found by calculating the derivative of the curve function, and the maximum value of the extreme points of each row of the curve function is selected as the stress peak value of the entire circular surface. The size of the peak value determines the stress concentration degree of the spherical cap slider (3) material at a certain point, which is used to judge whether the local position is close to the yield or failure limit of the contact surface material; The second point, stress eccentricity: the peak point abscissa x of the defined curve function peak , which is the eccentricity of the peak point in the jth row, is used to describe the eccentricity of the jth row. The larger the eccentricity, the greater the eccentricity of the stress distribution, which may lead to structural instability. The third point is distribution uniformity: the coefficient of variation CV of the stress values ​​of each measuring point in the jth row is calculated, that is, the ratio of the standard deviation to the mean value to measure the uniformity of the stress distribution on the spherical cap. The larger the CV value, the more uneven the stress distribution. When the CV tends to 0, it means that the surface stress distribution of the spherical cap slider (3) is basically uniform, and there is no local stress protrusion on the material surface.

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