Method for evaluating performance of friction pendulum seismic isolation bearing in service state

Abstract

The application discloses a kind of performance evaluation methods of friction pendulum seismic isolation bearing in service state, comprising: S1, the horizontal sliding displacement and vertical force detection of the friction pendulum seismic isolation bearing being in service are carried out;S2, according to the data of detection, the sliding interface friction coefficient μ of the friction pendulum seismic isolation bearing in service is calculated;S3, according to the sliding interface friction coefficient μ of the friction pendulum seismic isolation bearing in service obtained, the seismic performance index of friction pendulum seismic isolation bearing is calculated, and the seismic performance index includes horizontal stiffness and effective damping ratio coefficient;S4, according to the influence of sliding interface state change and horizontal stiffness change on bridge structure seismic damage state, the seismic safety risk of the friction pendulum seismic isolation bearing of sliding interface state is classified.The method can obtain the sliding interface state of the friction pendulum seismic isolation bearing in service state and its specific friction characteristics, so as to evaluate the seismic performance of the friction pendulum seismic isolation bearing.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of bridge seismic safety and detection and evaluation technology. More specifically, the present application relates to a performance evaluation method for a friction pendulum seismic isolation bearing in a service state. BACKGROUND

[0002] In order to reduce the seismic damage risk of bridge structures under the action of earthquakes, highway bridge seismic design has shifted from structure seismic mitigation based on life safety to post-earthquake structure function recovery and rapid repair. Among them, the seismic isolation system bridge is a typical seismic system of highway bridges in China, that is, through the seismic isolation function of the seismic isolation bearing to protect the lower structure and the main beam from damage or slight damage, to meet the post-disaster emergency, damage repair, rapid repair, traffic capacity recovery and other reuse requirements, therefore, the seismic device is the key and vulnerable part of the bridge to achieve its seismic fortification goal.

[0003] As a widely used bearing in current practical engineering applications, the friction pendulum seismic isolation bearing is gradually deteriorated under the influence of multiple factors such as vehicle load, impact load, wind, temperature, corrosion, etc. during service, which brings more uncertainties and potential hazards to the safety of bridge structures and their seismic safety during operation. In order to timely and accurately determine the seismic capacity or safety risk level of the seismic isolation bridge structure at different service periods, further develop a scientific and reasonable bridge seismic safety hazard investigation, disposal and seismic resilience improvement scheme, reduce the seismic safety risk, and master the service state and deterioration law of the friction pendulum seismic isolation bearing.

[0004] Currently, the existing "Highway Bridge Technical Condition Evaluation Standard" (JTG / T H1-2011) and "Highway Bridge Bearing Capacity Detection and Evaluation Regulations" (JTG / T J21-2011) do not involve the detection and evaluation of friction pendulum seismic isolation bearings, which seriously restricts the development of bridge structure safety performance detection and evaluation work. In the actual bridge detection and evaluation process, only the appearance inspection of the friction pendulum seismic isolation bearing is carried out, such as rust, sliding, etc. Since the detection and inspection personnel do not understand the working principle of the friction pendulum seismic isolation bearing, the detection or monitoring of the continuous deformation of the related bearing is ignored, resulting in a lack of quantitative indicators representing the function and performance of the friction pendulum seismic isolation bearing, and the quantitative evaluation of the seismic safety performance of the friction pendulum seismic isolation bearing and its bridge structure cannot be realized. The ideal assumption is usually adopted, that is, the change of the mechanical performance of the bearing is not considered or the change of the mechanical performance of the bearing is assumed to reach a certain degree, and the bridge structure mechanical performance analysis is carried out, which brings great risk to the bridge structure safety and seismic safety evaluation.

[0005] According to the working principle, mechanical performance calculation model and related research results of the friction pendulum seismic isolation bearing, the main factors affecting the function and performance of the bearing are the friction characteristics of the sliding interface of the bearing in addition to the geometric configuration. Under the coupling action of long-term operation load, wind, temperature and other factors, the state of the sliding interface and the friction characteristics thereof of the friction pendulum seismic isolation bearing can change, which further affects the lateral stiffness, energy dissipation capacity and damping characteristics of the bearing. Therefore, the state of the sliding interface and the specific friction characteristics of the friction pendulum seismic isolation bearing in a certain operation period are one of the key indicators for accurately analyzing and evaluating the safety and seismic safety of the bridge structure. SUMMARY

[0006] The application provides a performance evaluation method for a friction pendulum seismic isolation bearing in a service state, which can obtain the state of the sliding interface and the specific friction characteristics of the friction pendulum seismic isolation bearing in the service state, so as to evaluate the seismic performance of the friction pendulum seismic isolation bearing.

[0007] In order to achieve these objects and other advantages of the present application, a performance evaluation method for a friction pendulum seismic isolation bearing in a service state is provided, comprising:

[0008] S1, detecting the horizontal sliding displacement and the vertical force of the friction pendulum seismic isolation bearing in service;

[0009] S2, calculating the friction coefficient μ of the sliding interface of the friction pendulum seismic isolation bearing in service according to the detected data, and the calculation process is as follows: μ0=a1+b1D(2); wherein, μ0 is the initial friction coefficient, a2 and b2 are the horizontal loading displacement amplitude and the compressive stress influence coefficient when the friction coefficient is measured, N is the number of cycles of the horizontal sliding displacement between the maximum value and the minimum value, a1 and b1 are linear fitting coefficients, and D is the horizontal sliding displacement;

[0010] S3, calculating the seismic performance indicators of the friction pendulum seismic isolation bearing, including the horizontal stiffness and the effective damping ratio coefficient, according to the obtained friction coefficient μ of the sliding interface of the friction pendulum seismic isolation bearing in service;

[0011] S4, classifying the safety risk of the friction pendulum seismic isolation bearing according to the influence of the change of the state of the sliding interface and the change of the horizontal stiffness on the seismic damage state of the bridge structure.

[0012] Preferably, step S1 is specifically:

[0013] S101, obtaining the test data of the vertical force and the horizontal sliding displacement of the friction pendulum seismic isolation bearing for at least one day;

[0014] S102, filtering the test data to obtain the maximum vertical force, the minimum vertical force and the average vertical force of the friction pendulum seismic isolation bearing, so as to determine the compressive stress value of the friction pendulum seismic isolation bearing;

[0015] S103, extracting the maximum and minimum horizontal sliding displacement, and calculating the cycle number of the horizontal sliding displacement between the maximum and minimum values within the detection time.

[0016] Preferably, before step S2, further comprising: using model test and theoretical derivation method to calculate the influence parameters of the friction pendulum seismic isolation bearing interface friction characteristics, to obtain the calculation formula (1) and formula (2) of the sliding interface friction coefficient of the friction pendulum seismic isolation bearing, the influence parameters including: horizontal sliding displacement cycle number, horizontal sliding displacement, horizontal loading displacement amplitude and compressive stress, wherein when using model test, the model of the friction pendulum seismic isolation bearing used is the same as the model of the service friction pendulum seismic isolation bearing.

[0017] Preferably, in step S3, A, for horizontal stiffness: under the influence of sliding interface state, the calculation method of the horizontal stiffness of the friction pendulum seismic isolation bearing is:

[0018] Wherein, K is the horizontal stiffness of the friction pendulum seismic isolation bearing corresponding to the horizontal sliding displacement D at the service time t years, t≥0, W is the vertical force, μ is the friction coefficient considering the influence of service time, α is the horizontal stiffness amplification coefficient of the friction pendulum seismic isolation bearing, the value range is 1.3-1.5;

[0019] If the horizontal stiffness of the friction pendulum seismic isolation bearing is calculated according to the cumulative cycle number of sliding displacement, the calculation method is:

[0020] Wherein, K i is the horizontal equivalent stiffness of the friction pendulum seismic isolation bearing under the i th horizontal cumulative cycle number, K o is the horizontal equivalent stiffness of the friction pendulum seismic isolation bearing under the first horizontal sliding displacement cycle number, a3 and b3 are the horizontal loading displacement amplitude and compressive stress influence coefficient when measuring the horizontal stiffness, respectively, and N is the horizontal sliding displacement cycle number;

[0021] B, for the effective damping ratio coefficient β eq , the calculation method is: β eq =A+BN (5), A and B are the horizontal loading displacement amplitude and compressive stress influence coefficient when measuring the effective damping ratio coefficient, respectively, and N is the horizontal sliding displacement cycle number.

[0022] Preferably, S5 is further included, which is to classify the post-earthquake damage state of the service friction pendulum seismic isolation bearing according to the horizontal deformation as a quantitative characterization index, specifically:

[0023] S501, the displacement parameter of the friction pendulum seismic isolation bearing for classification: the horizontal sliding displacement D of the service friction pendulum seismic isolation bearing, the displacement demand value X under normal operating load S , the design displacement X D , and the ultimate displacement X L ;

[0024] S502, A, when D≤X S and the horizontal sliding displacement is resettable, the post-earthquake damage state of the service friction pendulum seismic isolation bearing is intact;

[0025] B, when D≤X S and the sliding friction characteristics change within a short distance, the post-earthquake damage state of the service friction pendulum seismic isolation bearing is slightly damaged;

[0026] C, when X S <D≤X D and the interface sliding function is deteriorated within a limited horizontal sliding distance, the horizontal sliding displacement cannot be completely restored, the post-earthquake damage state of the service friction pendulum seismic isolation bearing is moderate damage;

[0027] D, when X D <D≤X L and the interface sliding function is deteriorated; the horizontal sliding displacement cannot be restored, the post-earthquake damage state of the service friction pendulum seismic isolation bearing is serious damage;

[0028] E, when D>X L and the connecting piece of the service friction pendulum seismic isolation bearing fails, the rubber is extruded, and the sliding function fails, the post-earthquake damage state of the service friction pendulum seismic isolation bearing is extremely serious damage.

[0029] Preferably, in step S4, the seismic safety risk of the friction pendulum seismic isolation bearing with sliding interface state is classified, specifically: A, when the sliding interface friction coefficient change Δμ of the service friction pendulum seismic isolation bearing is ≤5%, and the shear stiffness change ΔK is ≤10%, the safety risk level is I good;

[0030] B, when the sliding interface friction coefficient change 5%<Δμ≤10% of the service friction pendulum seismic isolation bearing, and the shear stiffness change 10%<ΔK≤20%, the safety risk level is II slight deterioration;

[0031] C. When the change amount of the sliding interface friction coefficient of the service friction pendulum seismic isolation bearing is 10% < Δμ ≤ 40%, and the change amount of the shear stiffness is 20% < ΔK ≤ 40%, the safety risk level is III moderate deterioration;

[0032] D. When the change amount of the sliding interface friction coefficient of the service friction pendulum seismic isolation bearing is Δμ > 40%, and the change amount of the shear stiffness is ΔK > 40%, the safety risk level is IV severe deterioration;

[0033] E. When the change amount of the sliding interface friction coefficient of the service friction pendulum seismic isolation bearing is Δμ > 40%, and the seismic performance does not meet the verification requirements, the safety risk level is V extremely severe deterioration;

[0034] Wherein, Δμ is the change amount of the sliding interface friction coefficient of the service friction pendulum seismic isolation bearing and the initial sliding friction coefficient, and ΔK is the change amount of the horizontal stiffness of the service friction pendulum seismic isolation bearing and the horizontal stiffness at the first horizontal sliding displacement cycle.

[0035] Preferably, it further comprises S6, according to the lateral stiffness and displacement ductility of the pier column as quantitative characterization indexes, and the influence of the service performance deterioration on the damage state thereof, the seismic safety risk of the friction pendulum seismic isolation bridge is classified and divided.

[0036] The present application at least includes the following beneficial effects:

[0037] Firstly, by detecting the horizontal sliding displacement and the vertical force, the key parameters of the service friction pendulum seismic isolation bearing can be obtained. Both the direct measurement parameters such as the horizontal sliding displacement and the vertical force are considered, and the key performance indexes such as the sliding interface friction coefficient, the horizontal stiffness and the effective damping ratio coefficient are further calculated through these parameters, so that the working state of the friction pendulum seismic isolation bearing is reflected from multiple dimensions. Therefore, the performance of the friction pendulum seismic isolation bearing can be comprehensively evaluated from multiple dimensions. Overall, the evaluation method includes multiple steps such as basic data detection, friction coefficient calculation, seismic performance index calculation, safety risk and damage state level division, which comprehensively evaluates the performance of the friction pendulum seismic isolation bearing and avoids the one-sidedness of single index evaluation.

[0038] Second, according to the influence of the sliding interface state change and the horizontal stiffness change on the seismic damage state of the bridge structure, the safety risk of the friction pendulum seismic isolation bearing is graded, the safety risk of the friction pendulum seismic isolation bearing can be found in time. Once the risk level is high, corresponding maintenance or replacement measures can be taken in time to avoid the damage of the bridge structure due to the poor performance of the bearing in the earthquake and other natural disasters, and the safety of the bridge is ensured. The horizontal deformation of the friction pendulum seismic isolation bearing is taken as a quantitative characterization index, the post-earthquake damage state of the service friction pendulum seismic isolation bearing is graded, the evaluation result is more intuitive and clear, and the damage degree of the friction pendulum seismic isolation bearing can be clearly reflected.

[0039] Other advantages, objects and features of the present application will be apparent from the following description, and will be understood by those skilled in the art. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 The performance evaluation method flowchart of the friction pendulum seismic isolation bearing in the service state of the present application;

[0041] Figure 2 The data graph of the relationship between the horizontal loading displacement amplitude and the horizontal force;

[0042] Figure 3 The data graph of the relationship between the friction coefficient of the friction pendulum seismic isolation bearing and the horizontal loading displacement amplitude;

[0043] Figure 4 The bridge seismic risk safety risk grade division standard (friction pendulum seismic isolation bearing);

[0044] Figure 5 The damage state division standard of the friction pendulum seismic isolation bearing;

[0045] Figure 6 The bridge pier seismic safety risk grade division standard;

[0046] Figure 7 The pier column seismic damage state division standard;

[0047] Figure 8 The seismic safety risk grade division standard of the seismic measure;

[0048] Figure 9 The seismic safety risk grade division of the seismic isolation beam bridge;

[0049] Figure 10 The relationship between the vertical displacement of different measuring points and time in the laboratory test is shown in the schematic diagram;

[0050] Figure 11The figure shows the relationship between vertical displacement and vertical force in the laboratory test. DETAILED DESCRIPTION

[0051] The application will be further described in conjunction with the accompanying drawings so that those skilled in the art can carry out the application according to the description and specific examples herein provided.

[0052] It should be understood that the terms such as "have", "contain" and "include" used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0053] It should be noted that the experimental methods described in the following embodiments are all conventional methods unless otherwise specified, and the reagents and materials can be obtained from commercial channels unless otherwise specified. In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mount", "connect", "arrange" should be understood broadly, for example, they can be fixedly connected, arranged, or detachably connected, arranged, or integrally connected, arranged. For those skilled in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances. The orientations or positional relationships indicated by the terms "transverse", "longitudinal", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0054] As shown in Figure 1 The embodiment of the present application provides a performance evaluation method for a friction pendulum seismic isolation bearing in a service state, which comprises the following steps:

[0055] S1, detecting the horizontal sliding displacement and vertical force of the friction pendulum seismic isolation bearing in service.

[0056] Specifically, step S1 comprises the following steps:

[0057] S101, acquiring the vertical force and horizontal sliding displacement test data of the friction pendulum seismic isolation bearing for at least one day;

[0058] S102, filtering the test data to acquire the maximum vertical force, minimum vertical force and average vertical force of the friction pendulum seismic isolation bearing, so as to determine the compressive stress value of the friction pendulum seismic isolation bearing;

[0059] S103, extracting the maximum and minimum values of the horizontal sliding displacement, and calculating the cycle number of the horizontal sliding displacement between the maximum and minimum values within the detection time.

[0060] In the above steps, the upper connecting plate of the friction pendulum seismic isolation bearing is connected with the bridge or superstructure, and the lower connecting plate is connected with the pier column. For the friction pendulum seismic isolation bearing in service, the vertical force measuring device and the horizontal displacement testing device are installed in the space range of the beam bottom and the pier top. The horizontal displacement testing device can be a contact or non-contact laser displacement sensor. The vertical force measuring device can be a pressure sensor arranged at the connecting position of the friction pendulum seismic isolation bearing to measure the vertical load of the friction pendulum seismic isolation bearing. The test data of the vertical force and the horizontal sliding displacement of the friction pendulum seismic isolation bearing are obtained for at least one day, and then the test data are filtered to obtain the maximum vertical force, the minimum vertical force and the average vertical force of the friction pendulum seismic isolation bearing. The pressure stress value can be obtained by dividing the vertical force by the bearing area, so that the maximum pressure stress value, the minimum pressure stress value and the average pressure stress value can be calculated. The maximum value and the minimum value of the horizontal sliding displacement are extracted from the filtered test data, and the number of cycles of the horizontal sliding displacement between the maximum value and the minimum value within the monitoring time is calculated.

[0061] S2, according to the detected data, calculating the sliding interface friction coefficient μ of the friction pendulum seismic isolation bearing in service, the calculation process is: μ0=a1+b1D (2); wherein, μ0 is the initial friction coefficient, a2 and b2 are the horizontal loading displacement amplitude and the pressure stress influence coefficient when the friction coefficient is measured, N is the number of cycles of the horizontal sliding displacement between the maximum value and the minimum value, a1 and b1 are linear fitting coefficients, and D is the horizontal sliding displacement.

[0062] Before step S2, it further includes step S1-2: using model test and theoretical derivation method to calculate the influence parameters of the friction pendulum seismic isolation bearing interface friction characteristics, and obtaining the calculation formula (1) and formula (2) of the sliding interface friction coefficient of the friction pendulum seismic isolation bearing. When the model test is used, the model of the friction pendulum seismic isolation bearing used is the same as that of the friction pendulum seismic isolation bearing in service.

[0063] In the above steps, the influence parameters of the friction pendulum seismic isolation bearing interface friction characteristics need to be calculated by model test and theoretical derivation method. As shown in Figure 2 and Figure 3 , the relationship data graph between the horizontal loading displacement amplitude and the horizontal force is given in Figure 2 , the relationship data graph between the friction coefficient of the friction pendulum seismic isolation bearing and the horizontal loading displacement amplitude is given in Figure 3 , and it can be seen from Figure 3 that the friction coefficient of the friction pendulum seismic isolation bearing is related to the horizontal loading displacement amplitude, the number of cycles of the horizontal sliding displacement and other parameters. By analyzing Figure 2 and Figure 3The relationship calculation formula of the friction coefficient of the sliding interface of the friction pendulum bearing with the cycle number of the accumulated horizontal displacement can be obtained by processing the relationship data graph.

[0064] μ0 is the initial friction coefficient, which changes with the change of the horizontal loading displacement, b2 is the pressure stress influence coefficient when the friction coefficient is measured, the pressure stress influence coefficient is an index reflecting the change degree of various performance parameters of the friction pendulum bearing under different pressure stress states, which reflects the influence of the vertical pressure stress on the horizontal mechanical properties of the bearing, and the relationship between the horizontal loading displacement amplitude and the horizontal force will change with the change of the pressure stress, and the specific value or change rule of the pressure stress influence coefficient can be determined by analyzing the horizontal loading data under different pressure stresses.

[0065] In addition, for the friction pendulum bearing, the friction coefficient of the sliding interface changes with the sliding displacement when the sliding block slides along the entire sliding curve, and in the current analysis of the stress performance of the friction pendulum bearing, an ideal constant friction coefficient is usually used, which does not conform to the actual situation. Therefore, in order to more accurately obtain the mechanical properties of the friction pendulum bearing, the initial friction coefficient μ0 can be obtained through the friction test of the same type of bearing: μ0=a1+b1D(2), a1 and b1 are linear fitting coefficients, and D is the horizontal sliding displacement.

[0066] According to the horizontal sliding displacement test data of the service friction pendulum bearing, the initial sliding friction coefficient of the friction pendulum bearing within a certain horizontal sliding displacement range is calculated through formula (2). Then, the cycle number of the horizontal sliding displacement within a certain test time is calculated, and then the sliding interface friction coefficient of the current friction pendulum bearing is calculated by using formula (1).

[0067] S3, according to the obtained sliding interface friction coefficient μ of the service friction pendulum bearing, the seismic performance index of the friction pendulum bearing is calculated, and the seismic performance index includes the horizontal stiffness and the effective damping ratio coefficient.

[0068] In step S3, A, for the horizontal stiffness: under the influence of the sliding interface state, the calculation method of the horizontal stiffness of the friction pendulum bearing is:

[0069] Wherein, K is the horizontal stiffness of the friction pendulum bearing corresponding to the horizontal sliding displacement D at the service time t years, t≥0, the cycle number N of the horizontal sliding displacement is the accumulated reciprocating cycle number of the friction pendulum bearing horizontal displacement measured when the bridge service time is t years, W is the vertical force, μ is the friction coefficient considering the influence of the service time, and α is the horizontal stiffness amplification coefficient of the friction pendulum bearing, the value range is 1.3-1.5.

[0070] If the horizontal stiffness of the friction pendulum seismic isolation bearing is calculated according to the cumulative cycle number of the sliding displacement, the calculation method is:

[0071] Wherein, K i is the horizontal equivalent stiffness of the friction pendulum seismic isolation bearing under the i th horizontal cumulative cycle number, K o is the horizontal equivalent stiffness of the friction pendulum seismic isolation bearing under the first horizontal sliding displacement cycle number, which is specifically the value corresponding to the 20% of the design displacement, a3 and b3 are the horizontal loading displacement amplitude and the compressive stress influence coefficient when measuring the horizontal stiffness, which can be determined according to the test data, and N is the horizontal sliding displacement cycle number.

[0072] B, for the effective damping ratio coefficient β eq , the calculation method is: β eq =A+BN (5), A and B are the horizontal loading displacement amplitude and the compressive stress influence coefficient when measuring the effective damping ratio coefficient, and N is the horizontal sliding displacement cycle number. The equivalent damping ratio coefficient increases linearly with the increase of the cumulative cycle number of the horizontal sliding displacement.

[0073] S4, according to the influence of the change of the sliding interface state and the change of the horizontal stiffness on the seismic damage state of the bridge structure, the seismic safety risk of the friction pendulum seismic isolation bearing with sliding interface state is classified.

[0074] Wherein, in step S4, the safety risk of the friction pendulum seismic isolation bearing with sliding interface state is classified, specifically: A, when the change amount of the sliding interface friction coefficient of the service friction pendulum seismic isolation bearing Δμ≤5%, the change amount of the shear stiffness ΔK≤10%, the safety risk level is I good;

[0075] B, when the change amount of the sliding interface friction coefficient of the service friction pendulum seismic isolation bearing 5% < Δμ≤10%, the change amount of the shear stiffness 10% < ΔK≤20%, the safety risk level is II slight deterioration;

[0076] C, when the change amount of the sliding interface friction coefficient of the service friction pendulum seismic isolation bearing 10% < Δμ≤40%, the change amount of the shear stiffness 20% < ΔK≤40%, the safety risk level is III moderate deterioration;

[0077] D, when the change amount of the sliding interface friction coefficient of the service friction pendulum seismic isolation bearing Δμ>40%, the change amount of the shear stiffness ΔK>40%, the safety risk level is IV serious deterioration;

[0078] E, when the change amount of the sliding interface friction coefficient of the service friction pendulum seismic isolation bearing Δμ>40%, the seismic performance does not meet the verification requirements, the safety risk level is V extremely serious deterioration.

[0079] wherein, Δμ is the change of the friction coefficient of the sliding interface of the service friction pendulum seismic isolation bearing and the initial sliding friction coefficient, and ΔK is the change of the horizontal stiffness of the service friction pendulum seismic isolation bearing and the horizontal stiffness under the first horizontal sliding displacement cycle.

[0080] In the above steps, the safety risk of the friction pendulum seismic isolation bearing in the sliding interface state is mainly classified, and more detailed classification content can be referred to Figure 4 Figure 4 In the above steps, the safety risk of the friction pendulum seismic isolation bearing in the sliding interface state is mainly classified, and more detailed classification content can be referred to

[0081] It should be noted that in the E level of the safety risk classification, the verification requirement is according to the performance requirement of bridge seismic isolation design in section 10.4 of the current "Code for Seismic Design of Highway Bridges" (JTG / T 2231-01-2020), i.e. under E2 earthquake action, the bridge pier, pier and foundation can have local slight damage, but still in elastic state, and can continue to be used after repair or simple repair; after the combination of E2 earthquake action effect and permanent effect in the longitudinal and transverse directions of the bridge, the strength of the bridge pier, pier and foundation should be calculated according to the relevant provisions of the current code for design of highway bridges and culverts; and the seismic isolation device should be calculated according to 10.4.3. Because, after the increase of the friction coefficient of the sliding interface of the friction pendulum bearing, the lateral stiffness and recoverable force of the bearing will be affected; in addition, the horizontal force transmitted to the pier column will change, which may not meet the performance requirement of the bridge pier strength. It is concluded that when the friction coefficient of the sliding interface of the friction pendulum bearing increases by 40%, the horizontal stiffness of the friction pendulum bearing increases, the stress of the lower pier column increases, the damage of the pier column increases, and the risk of not meeting the performance requirement increases.

[0082] S5, according to the horizontal deformation of the friction pendulum seismic isolation bearing as a quantitative characterization index, the damage state of the service friction pendulum seismic isolation bearing is classified, specifically:

[0083] S501, the displacement parameter of the friction pendulum seismic isolation bearing for classification: the horizontal sliding displacement D of the service friction pendulum seismic isolation bearing, the value X of the displacement demand under normal operating load S , the design displacement X D , and the ultimate displacement X L .

[0084] S502, A, when D≤X S ​When D>X and the connection of the service friction pendulum seismic isolation bearing is invalid, the rubber is extruded, and the sliding function is invalid, the post-earthquake damage state of the service friction pendulum seismic isolation bearing is extremely severe damage.

[0085] B, when D≤X S and the sliding friction characteristics change in a short distance, the post-earthquake damage state of the service friction pendulum seismic isolation bearing is slight damage.

[0086] C, when X S <D≤X D and the interface sliding function is deteriorated, the horizontal sliding displacement cannot be completely restored, and the post-earthquake damage state of the service friction pendulum seismic isolation bearing is moderate damage.

[0087] D, when X D <D≤X L and the interface sliding function is deteriorated; the horizontal sliding displacement cannot be restored, and the post-earthquake damage state of the service friction pendulum seismic isolation bearing is severe damage.

[0088] E, when D>X L and the connection of the service friction pendulum seismic isolation bearing is invalid, the rubber is extruded, and the sliding function is invalid, the post-earthquake damage state of the service friction pendulum seismic isolation bearing is extremely severe damage.

[0089] In the above steps, mainly for the horizontal deformation of the friction pendulum seismic isolation bearing as a quantitative characterization index, the post-earthquake damage state of the service friction pendulum seismic isolation bearing is classified and divided, and more detailed classification content please refer to Figure 5 In Figure 5 , according to the whole process of force deformation evolution of the friction pendulum seismic isolation bearing under horizontal seismic load, based on the seismic vulnerability analysis of the bearing of the seismic isolation bridge and its damage deformation control target, taking the horizontal deformation of the friction pendulum seismic isolation bearing as a quantitative characterization index, considering the friction sliding energy dissipation function and the change law of mechanical properties of the friction pendulum seismic isolation bearing, and the influence on the seismic damage and traffic function, starting from the displacement demand value (X S ), design displacement (X D ), and limit displacement (X L ) under normal operating load, the quantitative classification evaluation standard of the damage state of the service friction pendulum seismic isolation bearing is developed.

[0090] S6, according to the lateral stiffness and displacement ductility of the pier column as a quantitative characterization index, combined with the influence of its service performance deterioration on its seismic damage state, the seismic safety risk of the friction pendulum seismic isolation bridge is classified and divided.

[0091] In Figure 6In the present application, combined with the existing research results on the seismic performance of durable deterioration pier columns and the test results of the structural bending cracking damage pier seismic performance carried out by the present application, based on the vulnerability analysis results of the pier columns under the influence of different bending stiffness, taking the lateral stiffness and displacement ductility of the pier columns as the quantitative characterization indexes, considering the influence of the service performance deterioration on the seismic damage state, the seismic safety risk grade division standard for the service pier columns is developed. Among the existing single damage model, cumulative damage model and comprehensive damage model, the displacement or deformation part contributes more to the damage degree, the cumulative energy consumption coefficient is very small, and the discrete type is large, which is generally ignored. The estimation of the above damage model for the moderate damage degree is basically the same as the test phenomenon, which is suitable for the damage discrimination of the lower pier columns of the seismic mitigation and isolation beam bridge structure. Based on the theoretical calculation of the bending ductility pier column damage index, combined with the pier column damage and performance level division standard based on the residual lateral displacement rate, the seismic damage state division standard suitable for the bending ductility pier column is formed, as shown in Figure 7 Combined with the influence of various seismic measures on the bridge seismic damage mode or the risk probability of increasing the damage degree, the seismic safety risk grade evaluation standard is developed, as shown in Figure 8

[0092] According to the vulnerable components of the seismic mitigation and isolation beam bridge under the action of horizontal seismic load, considering the key role of each vulnerable component on the typical damage failure mode and the correlation between components, and the influence law of each service state factor on the damage failure probability of vulnerable components and system, the seismic safety risk grade division standard of highway bridge is developed, as shown in Figure 9 The division criteria are as follows:

[0093] (1) Taking the seismic safety risk grade of the key and vulnerable seismic mitigation and isolation device as the benchmark, the seismic safety risk grade of the system structure changes;

[0094] (2) When the service state of the seismic mitigation and isolation device, pier and seismic measure deteriorates at the same time, according to the influence of each part on the structure seismic damage state (not considering the interaction between components), under the corresponding structure system seismic safety risk benchmark grade, the corresponding combined seismic safety risk grade is given;

[0095] (3) Considering the correlation of the seismic mitigation and isolation device, pier and seismic measure under the action of earthquake and the influence on the structure seismic damage state, the more reasonable combined seismic safety risk grade is further determined.

[0096] (4) When the service state of the seismic mitigation and isolation device, pier and seismic measure deteriorates at the same time, when the seismic safety risk grade of the seismic mitigation and isolation device is less than that of other components, the seismic safety risk grade of the structure system is taken as the higher grade.

[0097] ​In conclusion, the application can solve the problems of lack of friction pendulum seismic isolation bearing service condition detection and evaluation method and index, lack of friction pendulum seismic isolation bearing and bridge structure anti-seismic safety evaluation grading and quantitative evaluation standard, and provide support for timely and accurately grasping the anti-seismic safety risk of friction pendulum seismic isolation bearing and bridge structure and disposal opportunity, strategy, etc.

[0098] In addition, it also needs to be explained that for the service bridge, when testing the friction pendulum seismic isolation bearing service state index, in order to reduce the field construction workload, time and economic cost, and embody the advantages of test technology such as implementability, convenience and reliability, the following points need to be understood in advance before installing the test system on site:

[0099] 1) The basic information of the friction pendulum seismic isolation bearing type, design parameters and displacement sliding direction, etc. provides basis for further developing the mechanical deformation performance index of the friction pendulum seismic isolation bearing and its test scheme;

[0100] 2) The spatial scale of the friction pendulum seismic isolation bearing installation position, such as the width, thickness of the friction pendulum seismic isolation bearing cushion layer, whether there is a pre-embedded steel plate, etc. provides reference for further developing the test instrument installation scheme;

[0101] 3) The power supply and network conditions of the bridge site provide reference for further forming the test instrument, data acquisition instrument, data transmission system, etc.

[0102] For the service bridge, because the upper structure load has been applied to the friction pendulum seismic isolation bearing before testing, the theoretical vertical stress of the friction pendulum seismic isolation bearing at different positions can be obtained by calculation, further test instruments are arranged on the symmetric side of the friction pendulum seismic isolation bearing, the change amount of the stress performance of the friction pendulum seismic isolation bearing under the action of vehicle, temperature, wind and other loads is tested, and through long-term observation of the change trend of single test instrument data and the relative amount change trend of symmetric test index, the state and performance change of the friction pendulum seismic isolation bearing are judged, and further applied to the analysis of the change rule of the anti-seismic performance of the friction pendulum seismic isolation bearing and the bridge with the service state and operation time. Therefore, on the basis of mastering the basic design parameters and performance parameters of the friction pendulum seismic isolation bearing, the sampling frequency and accuracy of the test instrument used are tested and verified to determine the reliability of the test data.

[0103] A friction pendulum seismic isolation bearing of the same type and model as the one used in the actual project is purchased, and a laboratory test of the vertical force and vertical displacement of the friction pendulum seismic isolation bearing is designed and carried out according to the vertical force and vertical displacement indicators to be tested, the relationship curve between the test vertical displacement and the vertical force is obtained, the change amount of the vertical force represented by the change amount of the vertical displacement can be obtained, and the difference in the stress state of the friction pendulum seismic isolation bearing corresponding to the symmetric displacement change amount is obtained, the absolute vertical force and vertical displacement value of the current friction pendulum seismic isolation bearing is back calculated, and the service state of the friction pendulum seismic isolation bearing, such as slip and uneven stress, is judged. Figure 10 and Figure 11 As shown in Figure 10 , the No. 1 measuring point and the No. 3 measuring point are symmetrical, and the vertical displacement deviation of the local void phenomenon exists, in Figure 11 , the vertical force-vertical displacement curve of the friction pendulum seismic isolation bearing is obtained by using different test instruments, and the relationship between the change amount of the vertical displacement and the change amount of the vertical force can be obtained.

[0104] According to the pseudo-static test of the friction pendulum seismic isolation bearing, the friction coefficient of the friction pendulum seismic isolation bearing can be fitted, such as the friction pendulum seismic isolation bearing model FPB3000-ZX-e150-0 with a compressive stress of 6Mpa.

[0105] Firstly, the initial friction coefficient of the friction pendulum seismic isolation bearing under a compressive stress of 6MPa is obtained from the pseudo-static test result, which is about 0.02; then, the horizontal loading displacement accumulates cycles, and when the horizontal loading displacement reaches 30mm, the change curve of the friction coefficient is fitted as formula μ = μ0 + 0.0048e 0.005N . According to this method, the sliding interface friction coefficient under different loading displacements can be obtained. When N = 100 cycles are reached, the sliding interface friction coefficient of the friction pendulum seismic isolation bearing is equal to 0.027. After determining the sliding interface friction coefficient (0.027) corresponding to a certain horizontal sliding displacement D (such as 30mm), the change value of the vertical force (2652kN) in a day is brought into formula (3), so that the stiffness of the friction pendulum seismic isolation bearing under the corresponding horizontal sliding displacement (300mm) can be calculated, which is 334kN / m. Then, according to the change amount of the sliding interface friction coefficient 35%, the shear stiffness change amount 35.0%, the safety risk level can be determined as III moderate deterioration. At this time, the corresponding state of the friction pendulum seismic isolation bearing is that the service friction pendulum seismic isolation bearing characteristics change, and the post-earthquake damage state will be slightly damaged.

[0106] According to the change law of the effective damping ratio coefficient with the number of cycles β eq = 0.39 + 5.27 x 10 -4N, when the cycle is 100 times, the effective damping ratio coefficient of the friction pendulum seismic mitigation support is further calculated as 0.45, finally, the calculated stiffness and effective damping ratio coefficient of the friction pendulum seismic mitigation support are input into the mechanical constitutive relation of the friction pendulum seismic mitigation support in the finite element numerical model, and the seismic performance of the whole bridge under the influence of the service friction pendulum seismic mitigation support is analyzed.

[0107] The number of devices and the scale of processing illustrated here are for the purposes of simplicity and clarity in illustrating the application. Other applications, modifications, and variations of the application will be apparent to persons skilled in the art.

[0108] Although embodiments of the application have been disclosed in connection with the specified embodiments, it should be understood that they are not intended to limit the scope of the application to the particular configurations and arrangements described. It is intended to cover all possible modifications and equivalents within the scope of the following claims, and their scope is to be determined not with reference to the above description, but instead by referring to the appended claims along with the full range of equivalents to which they are entitled.

Claims

1. A method for performance evaluation of a friction pendulum seismic isolation bearing in service, characterized by, The method comprises the following steps: S1, detecting the horizontal sliding displacement and vertical force of the service friction pendulum seismic isolation bearing; S2, according to the detected data, the sliding interface friction coefficient μ of the service friction pendulum seismic isolation bearing is calculated, and the calculation process is: μ0=a1+b1D(2); Wherein, μ0 is the initial friction coefficient, a2 and b2 are the horizontal loading displacement amplitude and compressive stress influence coefficient respectively when the friction coefficient is measured, N is the cycle number of the horizontal sliding displacement between the maximum value and the minimum value, a1 and b1 are linear fitting coefficients, and D is the horizontal sliding displacement; S3, according to the obtained sliding interface friction coefficient μ of the service friction pendulum seismic isolation bearing, the seismic performance index of the friction pendulum seismic isolation bearing is calculated, and the seismic performance index includes horizontal stiffness and effective damping ratio coefficient; S4, according to the influence of the change of the sliding interface state and the change of the horizontal stiffness on the seismic damage state of the bridge structure, the seismic safety risk of the friction pendulum seismic isolation bearing with the sliding interface state is classified; In step S3, A, for horizontal stiffness: under the influence of the sliding interface state, the calculation method of the horizontal stiffness of the friction pendulum seismic isolation bearing is: K = W (D - t) / (t + D) (1) wherein, K is the horizontal stiffness of the friction pendulum seismic mitigation support corresponding to the horizontal sliding displacement D at the service time t years, t >= 0, W is the vertical force, mu is the friction coefficient considering the influence of the service time, alpha is the horizontal stiffness amplification coefficient of the friction pendulum seismic mitigation support, and the value range is 1.3~1.5; If the horizontal stiffness of the friction pendulum seismic isolation bearing is calculated according to the cumulative cycle number of the sliding displacement, the calculation method is: wherein K i is the horizontal equivalent stiffness of the friction pendulum seismic isolation bearing at the i-th horizontal cumulative sliding displacement cycle, K o is the horizontal equivalent stiffness of the friction pendulum seismic isolation bearing at the first horizontal sliding displacement cycle, a3 and b3 are the horizontal loading displacement amplitude and the compressive stress influence coefficient, respectively, at the time of measuring the horizontal stiffness, and N is the number of horizontal sliding displacement cycles. B. For the effective damping ratio coefficient β eq which is calculated as follows: β eq = A + BN (5), where A and B are the horizontal loading displacement amplitude and the compressive stress influence coefficient, respectively, and N is the number of horizontal sliding displacement cycles.

2. The method for evaluating the performance of the friction pendulum seismic mitigation and isolation support in service according to claim 1, wherein Step S1 specifically comprises: S101, obtaining the vertical force and horizontal sliding displacement test data of the friction pendulum seismic isolation bearing for at least one day; S102, filtering the test data to obtain the maximum vertical force, minimum vertical force and average vertical force of the friction pendulum seismic isolation bearing, so as to determine the compressive stress value of the friction pendulum seismic isolation bearing; S103, extracting the maximum and minimum values of the horizontal sliding displacement, and calculating the cycle number of the horizontal sliding displacement between the maximum and minimum values within the detection time.

3. The method for evaluating the performance of the rocking-bearing under service state according to claim 1, wherein, Before step S2, further comprising: using model test and theoretical derivation method to calculate the influence parameters of the friction characteristics of the friction pendulum seismic isolation bearing interface, obtaining the calculation formula (1) and formula (2) of the sliding interface friction coefficient of the friction pendulum seismic isolation bearing, and the influence parameters include: horizontal sliding displacement cycle number, horizontal sliding displacement, horizontal loading displacement amplitude and compressive stress; wherein, when the model test is used, the model of the friction pendulum seismic isolation bearing used is the same as that of the service friction pendulum seismic isolation bearing.

4. The method for evaluating the performance of the rocking-bearing under service state according to claim 1, wherein, Further comprising S5, according to the horizontal deformation of the friction pendulum seismic isolation bearing as a quantitative characterization index, the post-earthquake damage state of the service friction pendulum seismic isolation bearing is classified, specifically: S501, the displacement parameter of the friction pendulum seismic isolation bearing relied on in hierarchical division: horizontal sliding displacement D of the service friction pendulum seismic isolation bearing, displacement demand value X under normal operation load S , design displacement X D , limit displacement X L ; S502、A, when D≤X S When D≤X and the horizontal sliding displacement can be reset, the post-earthquake damage state of the service friction pendulum seismic isolation bearing is perfect. B, when D≤X S When the short-distance sliding friction characteristics change, the post-earthquake damage state of the service friction pendulum seismic isolation bearing is slight damage. C. when X S D. when X D When the interface sliding function deteriorates within a limited horizontal sliding distance and the horizontal sliding displacement cannot be completely recovered, the service friction pendulum seismic isolation bearing is in a medium damage state after earthquake. D, when X D D≤X L horizontal sliding displacement is basically unrecoverable, the post-earthquake damage state of the service friction pendulum seismic isolation bearing is serious damage; E, when D>X L When D>X, and the connecting member of the service friction pendulum seismic isolation bearing fails, the rubber is extruded, and the sliding function fails, the post-earthquake damage state of the service friction pendulum seismic isolation bearing is extremely serious damage.

5. The method for assessing the performance of a seismic isolation bearing in service according to claim 1, wherein In step S4, the seismic safety risk of the friction pendulum seismic isolation bearing with the sliding interface state is classified, specifically: A, when the sliding interface friction coefficient change Δμ of the service friction pendulum seismic isolation bearing is less than or equal to 5%, and the shear stiffness change ΔK is less than or equal to 10%, the safety risk level is I good; B, when the sliding interface friction coefficient change 5% < Δμ ≤ 10% of the service friction pendulum seismic isolation bearing, and the shear stiffness change 10% < ΔK ≤ 20%, the safety risk level is II slight deterioration; C, when the sliding interface friction coefficient change 10% < Δμ ≤ 40% of the service friction pendulum seismic isolation bearing, and the shear stiffness change 20% < ΔK ≤ 40%, the safety risk level is III moderate deterioration; D. When the change amount of the sliding interface friction coefficient of the in-service friction pendulum seismic isolation bearing is greater than 40%, and the change amount of the shear stiffness is greater than 40%, the safety risk level is IV, which is serious deterioration; E. When the change amount of the sliding interface friction coefficient of the in-service friction pendulum seismic isolation bearing is greater than 40%, and the seismic performance does not meet the verification requirements, the safety risk level is V, which is extremely serious deterioration; Wherein, Δμ is the change amount of the sliding interface friction coefficient of the in-service friction pendulum seismic isolation bearing and the initial sliding friction coefficient, and ΔK is the change amount of the horizontal stiffness of the in-service friction pendulum seismic isolation bearing and the horizontal stiffness at the first horizontal sliding displacement cycle.

6. The method for assessing the performance of a seismic isolation bearing in service according to claim 1, wherein It also includes S6, according to the lateral stiffness and displacement ductility of the pier column as the quantitative characterization index, combined with the influence of its service performance deterioration on its seismic damage state, the seismic safety risk of the friction pendulum seismic isolation bridge is classified and divided.

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