Design method of three-dimensional shock insulation / vibration isolation support for subway upper cover structure

Abstract

The invention discloses a design method of a three-dimensional shock / vibration isolation support for a subway upper cover structure, and relates to the technical field of building shock (vibration) double control, and the design method comprises the following steps: S1, setting a shock isolation target and a fortification standard; s2, designing an upper structure; s3, designing a three-dimensional shock insulation support and arranging a shock insulation layer according to the shear resistance, the compression resistance and the tension resistance; s4, establishing an elastic-plastic model of the seismic isolation structure; s5, checking the wind resistance of the shock insulation structure, the eccentricity rate of the shock insulation layer and the restoring force of the shock insulation layer; s6, carrying out fortification earthquake time history analysis on the elastic-plastic model of the seismic isolation structure; s7, rare occurrence earthquake time history analysis is carried out on the elastic-plastic model of the seismic isolation structure; and S8, carrying out vibration level contrastive analysis on the elastic-plastic model of the seismic isolation structure. Not only is shock insulation design of the subway upper cover structure achieved, but also shock absorption design is achieved, the design efficiency and accuracy are improved, and the reliability of a subway upper cover building development project is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of building seismic (vibration) dual control, and more specifically, to a design method for a three-dimensional seismic isolation / vibration isolation bearing for a subway superstructure. Background Art

[0002] With the economic improvement and accelerated urbanization in China, a large number of people have flocked to central cities, resulting in a sharp increase in the urban population, an expansion of the spatial scale, and a significant growth in the number of motor vehicles. However, the existing transportation facilities and road resources are difficult to match this growth, exacerbating traffic congestion and triggering environmental and traffic problems such as a decline in air quality, noise pollution, and an increase in traffic accidents, affecting the quality of life of residents and the urbanization process. To solve these problems, TOD (Transit-Oriented-Development), that is, "a development model oriented by public transportation", has emerged as the times require. It emphasizes comprehensive development centered on public transportation stations to optimize the urban layout and improve traffic efficiency. A large number of subway superstructure buildings have emerged in major cities in China, which not only facilitate travel, meet the living needs, but also promote economic development, improve the urban quality, and inject new vitality into the healthy development of urbanization.

[0003] However, at the same time, the operation of the subway will directly or indirectly cause vibrations in the surrounding environment, and will also cause the superstructure to vibrate again under environmental excitation, causing noise pollution to the urban environment and reducing the quality of life of urban residents. In response to the environmental vibration and secondary noise problems caused by subway operation, the current mainstream vibration reduction and isolation strategies cover three major aspects: direct control of the vibration source, blocking of the vibration propagation path, and implementation of vibration isolation at the building foundation level. In the field of building foundation vibration isolation, setting vibration isolation bearings is a commonly used method. Common vibration isolation bearing designs mainly focus on resisting the influence of horizontal seismic motion, such as laminated rubber bearings, thick-layer rubber bearings, lead-core rubber bearings, and friction pendulum bearings. These horizontal vibration isolation bearings are not only mature in theoretical research but also widely used in many engineering projects.

[0004] However, it cannot be ignored that in general, the vibration isolation (vibration reduction) effect of horizontal vibration isolation bearings is not obvious when dealing with vertical earthquakes or vertical environmental vibrations. At the same time, the potential impact of vertical environmental vibrations on the daily use of buildings is gradually attracting people's attention. Taking the buildings above underground transportation facilities in high-intensity earthquake areas as an example, in order to ensure the structural safety of such buildings, horizontal seismic isolation technology may be relied on, but at the same time, in order to meet the vibration comfort standards of the living or working environment, vertical vibration isolation measures are also indispensable.

[0005] Therefore, how to provide a reasonable and efficient design method for a three-dimensional seismic isolation bearing for a subway superstructure is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the present invention provides a design method for a three-dimensional seismic isolation / vibration support for a subway superstructure, aiming to solve the above technical problems.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A design method for a three-dimensional seismic isolation / vibration support for a subway superstructure comprises the following steps:

[0009] S1: Setting seismic isolation goals and fortification standards;

[0010] S2: superstructure design;

[0011] S3: Design three-dimensional isolation bearings and arrange isolation layers according to the shear, compression and tension resistance;

[0012] S4: Establish an elastoplastic model of the seismic isolation structure;

[0013] S5: Verify the wind resistance of the seismic isolation structure, the eccentricity of the seismic isolation layer, and the restoring force of the seismic isolation layer;

[0014] S6: Conduct earthquake time history analysis on the elastoplastic model of the seismic isolation structure;

[0015] S7: Conduct rare earthquake time history analysis on the elastoplastic model of the seismic isolation structure;

[0016] S8: Comparative analysis of vibration levels of the elastoplastic model of the isolation structure.

[0017] Through the above technical scheme, the present invention provides a complete set of three-dimensional seismic isolation / vibration bearing design processes for subway superstructures, covering all aspects from setting goals to vibration level comparison analysis, so that the design process has rules to follow, improves the standardization and systematicness of the design, and avoids arbitrariness and omissions in the design process. The present invention comprehensively considers multiple key factors such as seismic isolation goals, superstructure design, shear, compression and tensile resistance of seismic isolation bearings, establishment of elastic-plastic models, wind resistance and restoring force verification, time history analysis under different earthquake conditions, and vibration level comparison, ensuring the comprehensiveness and reliability of the design, and can effectively cope with various complex working conditions that subway superstructures may face in actual operation. Through precise design and verification, the safety and comfort of subway superstructures in natural disasters such as earthquakes and subway operation vibrations can be significantly improved, the risk of structural damage can be reduced, the impact of vibration on personnel and equipment can be reduced, and the service life of the structure can be extended, providing a strong guarantee for the normal use and operation of subway superstructures.

[0018] Preferably, in the above design method of a three-dimensional seismic isolation / vibration isolation bearing for a subway superstructure, in step S1, according to engineering requirements and economy, the upper structure is designed for seismic isolation by reducing one degree or half a degree, and the initial horizontal seismic reduction coefficient is calculated. At the same time, a reasonable position of the seismic isolation layer is determined.

[0019] The beneficial effects of adopting the above technical solutions are as follows: According to engineering requirements and economy, it is allowed to design the upper structure for seismic isolation by reducing one degree or half a degree. This flexibility enables the design to better adapt to the characteristics and budget requirements of different projects, and optimize the cost-effectiveness while ensuring the seismic isolation effect. Calculating the initial horizontal seismic reduction coefficient and determining a reasonable position of the seismic isolation layer provide a clear quantitative basis and target orientation for subsequent design. By comparing the actual horizontal seismic reduction coefficient with the target value, deficiencies in the design can be promptly discovered and adjusted to ensure that the seismic isolation design achieves the expected seismic reduction effect, improving the accuracy and effectiveness of the design.

[0020] Preferably, in the above design method of a three-dimensional seismic isolation / vibration isolation bearing for a subway superstructure, in step S3, by calculating the static force conditions of the non-seismic isolation structure, the vertical reaction force at the node position where the seismic isolation bearing is to be arranged under static force is determined, and then the seismic isolation bearing is selected according to the vertical reaction force.

[0021] The beneficial effects of adopting the above technical solutions are as follows: By calculating the static force conditions of the non-seismic isolation structure, determining the vertical reaction force at the node position where the seismic isolation bearing is to be arranged, and then selecting the seismic isolation bearing according to the vertical reaction force, this selection method based on the actual force conditions can ensure that the seismic isolation bearing matches the force requirements of the structure, avoiding potential structural safety hazards or resource waste caused by improper selection of the bearing. It makes the design of the seismic isolation bearing more in line with the engineering reality, improves the adaptability and reliability of the seismic isolation bearing under different engineering conditions, provides a solid foundation for the stable operation of the subway superstructure, and at the same time reduces the engineering risks caused by the failure or insufficient performance of the seismic isolation bearing.

[0022] Preferably, in the above design method of a three-dimensional seismic isolation / vibration isolation bearing for a subway superstructure, in step S4, the seismic isolation structure is modeled and analyzed by Etabs, Sap2000 or Midas.

[0023] The beneficial effects of adopting the above technical solutions are as follows: By using professional software such as Etabs, Sap2000 or Midas to model and analyze the isolated structure, these software have high accuracy and reliability in the field of structural engineering, and can accurately simulate the mechanical behavior and response characteristics of the isolated structure under various working conditions, providing more accurate data support and analysis results for the design. Using professional software for modeling and analysis can greatly improve the design efficiency, shorten the design cycle, and also help to discover potential problems in the design and make timely optimization adjustments, thereby improving the overall quality of the design and ensuring that the isolated structure design meets the engineering requirements and safety standards.

[0024] Preferably, in the above design method of a three-dimensional isolation / vibration isolation bearing for a subway superstructure, in step S5, the wind resistance bearing capacity of the isolation layer is greater than the product of the wind load partial coefficient and the standard value of the horizontal shear force of the isolation layer under the action of the wind load.

[0025] The beneficial effects of adopting the above technical solutions are as follows: Stipulating that the wind resistance bearing capacity of the isolation layer must be greater than the product of the wind load partial coefficient and the standard value of the horizontal shear force of the isolation layer under the action of the wind load, this requirement ensures from a mechanical perspective that the isolation layer has sufficient bearing capacity and stability under the action of the wind load, can effectively resist the destructive effect of the wind load on the structure, and guarantee the safe operation of the subway superstructure under harsh meteorological conditions such as strong winds. By strictly requiring the wind resistance bearing capacity of the isolation layer, the overall stability of the subway superstructure is further enhanced, enabling it to maintain stable mechanical properties in the face of external factors such as wind load, reducing the deformation and displacement of the structure, and reducing the risk of structural damage and safety accidents caused by the wind load.

[0026] Preferably, in the above design method of a three-dimensional isolation / vibration isolation bearing for a subway superstructure, in step S6, according to the results of the time-history analysis of the isolated structure under the fortification earthquake and the calculation results of the non-isolated structure under the fortification earthquake, the actual horizontal seismic reduction coefficient β of the isolated structure is obtained 1 , and β 1 is compared with the target horizontal seismic reduction coefficient β. If β 1 is less than β, then the next step of the design is carried out; otherwise, return to the third step for adjustment.

[0027] The beneficial effects of adopting the above technical solutions are as follows: By conducting a time-history analysis of the isolated structure under the fortification earthquake on the elastic-plastic model of the isolated structure and comparing the analysis results with the calculation results of the non-isolated structure under the fortification earthquake, the actual horizontal seismic reduction coefficient β of the isolated structure can be accurately obtained 1 , this evaluation method based on time-history analysis is closer to the actual earthquake conditions, providing a scientific and accurate basis for judging the seismic reduction effect of the isolated design. Comparing β 1 with β, if β 1If the requirements are not met, it will be promptly returned to the third step for adjustment. This closed-loop design adjustment mechanism ensures that the seismic isolation design can be continuously optimized until the expected seismic reduction goal is achieved, improving the adaptability and reliability of the design and avoiding poor seismic isolation effects or structural safety hazards caused by design deviations.

[0028] Preferably, in the above design method of a three-dimensional seismic isolation / vibration isolation bearing for a subway superstructure, in steps S5 - S8: If the three points in step S5 cannot be satisfied simultaneously, it will be returned to step S3 for adjustment; in step S6, check whether the new horizontal seismic reduction coefficient meets the requirements. If it does not meet the requirements, it will be returned to step S3 for adjustment; in step S7, check the compressive stress, tensile stress, and deformation of the seismic isolation bearing under rare earthquake actions. If it does not meet the requirements, it will be returned to step S3 for adjustment; in step S8, the vibration level includes the vibration acceleration level and the vertical Z vibration level VL. Z .; Both the vibration acceleration level and the vertical Z vibration level need to be less than the limits given by the corresponding specifications, otherwise it will be returned to step S3 for adjustment.

[0029] The beneficial effects of adopting the above technical solutions are as follows: In steps S5 - S8, multiple key performance indicators of the seismic isolation structure are checked, such as wind resistance bearing capacity, horizontal seismic reduction coefficient, compressive stress, tensile stress, and deformation under rare earthquake actions, and the vibration level, etc. When the requirements are not met, it will be promptly returned to step S3 for adjustment. This comprehensive and detailed checking and adjustment process ensures that the seismic isolation design can meet the engineering requirements and safety standards in all key aspects, improving the rigor and reliability of the design. Especially checking the compressive stress, tensile stress, and deformation of the seismic isolation bearing under rare earthquake actions, and comparing and analyzing the vibration level. These requirements enable the design to fully consider the performance of the structure under extreme earthquake conditions and vibration environments, ensuring that the subway superstructure still has good seismic isolation performance and structural safety when facing extreme disasters such as rare earthquakes, and guaranteeing the safety of personnel's lives and property and the normal use function of the structure.

[0030] Preferably, in the above design method of a three-dimensional seismic isolation / vibration isolation bearing for a subway superstructure, in step S8, the calculation formula for the vibration acceleration level: where a is the effective value of the vibration acceleration, a 0 is the reference acceleration, a 0 = 10 -6 m / s 2 . The vertical Z vibration level VL Z The calculation formula: where L a,i is the vibration acceleration level measured at the i-th center frequency, and Wi is the weighting factor in the Z direction at this frequency.

[0031] The beneficial effects of adopting the above technical solutions are as follows: The vibration acceleration level and the vertical Z vibration level VL are provided. Z Calculation formulas are provided, through which the vibration level values of the isolated structure under vibration conditions can be accurately calculated and compared with the limit values given in the corresponding specifications. This precise vibration level evaluation method provides a scientific and quantitative means for judging whether the isolation design meets the vibration comfort standard, helps to optimize the isolation design, and improves the use comfort of the subway superstructure. Ensure that both the vibration acceleration level and the vertical Z vibration level are less than the specification limit values, so as to ensure that the vibration level of the subway superstructure is within the acceptable range of personnel, reduce the discomfort of vibration to personnel and the noise pollution to the surrounding environment, improve the environmental friendliness and social and economic benefits of the subway superstructure, and at the same time meet the high requirements of modern society for the vibration comfort and environmental protection performance of buildings.

[0032] As can be seen from the above technical solutions, compared with the prior art, the present invention discloses a design method for a three-dimensional isolation / vibration isolation bearing for a subway superstructure. Compared with the prior art, the present invention not only solves the isolation design of the subway superstructure, but also solves the vibration reduction design, improves the design efficiency and accuracy, and ensures the reliability of the subway superstructure development project. Brief Description of the Drawings

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0034] Figure 1 The attached drawing is a flowchart of the design method for a three-dimensional isolation / vibration isolation bearing for a subway superstructure provided by the present invention. Detailed Embodiments

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0036] See the attached Figure 1 , the embodiments of the present invention disclose a design method for a three-dimensional isolation / vibration isolation bearing for a subway superstructure, including the following steps:

[0037] S1: Set the seismic isolation target and fortification criteria; according to the engineering requirements and economy, conduct seismic isolation design for the superstructure by reducing the seismic fortification intensity by one degree or half a degree, calculate the initial horizontal seismic reduction coefficient, and determine the reasonable position of the seismic isolation layer at the same time. The horizontal seismic reduction coefficient refers to the maximum value of the ratio of the inter-story shear force (bending moment) of the seismic isolation structure and the non-seismic isolation structure in elastic calculation or time history analysis.

[0038] S2: Design of the superstructure; determine the superstructure according to the hinged model at the bottom of the upper pier in the seismic isolation layer, and conduct cross-section design of the superstructure according to the seismic reduction target, combined with the layout of the building and the position of the seismic isolation layer.

[0039] S3: Select seismic isolation bearings and arrange the seismic isolation layer; in this implementation, the seismic isolation bearings used are for the invention patent application: a three-dimensional combined seismic isolation and energy dissipation bearing, with the publication number CN115653119A.

[0040] Calculate the static working conditions of the non-seismic isolation structure, determine the vertical reaction force at the node position where the seismic isolation bearing is to be arranged under static action, and then select the seismic isolation bearing according to the vertical reaction force, requiring that the vertical reaction force at the node position of the seismic isolation bearing is less than the design value of the compressive bearing capacity of the seismic isolation bearing specified in the code. The horizontal equivalent stiffness and equivalent damping ratio can be adjusted by changing the rubber layer area and thickness of the lead rubber bearing in the three-dimensional seismic isolation bearing, the size of the lead core, and the size and quantity of the U-shaped steel bars, etc. The shear resistance can be adjusted by changing the materials and sizes of the upper and lower sleeves and the sleeve stiffeners. The vertical equivalent stiffness and equivalent damping ratio can be adjusted by changing the size of the lead rubber bearing and the size, quantity, and placement method of the disc springs in the disc spring group to adjust the vertical equivalent stiffness. The lead rubber bearing provides a certain tensile capacity; the disc spring group can also be pre-compressed. When the bearing is in tension, part of the tensile force will be offset by the vertical pre-pressure of the disc spring group; secondly, the disc spring group can effectively limit the upward transmission of seismic action. The steel cable provides an additional tensile function.

[0041] S4: Establish an elastoplastic model of the seismic isolation structure; model and analyze the seismic isolation structure through commercial or scientific research software. These software include but are not limited to Etabs, Sap2000, and Midas, etc.

[0042] S5: Conduct calculations such as wind resistance of the seismic isolation structure, eccentricity of the seismic isolation layer, and restoring force of the seismic isolation layer; the wind resistance bearing capacity of the seismic isolation layer should be greater than the product of the wind load partial coefficient and the standard value of the horizontal shear force of the seismic isolation layer under wind load. The stiffness center and mass center of the seismic isolation layer should preferably coincide, and the eccentricity under the action of the seismic fortification intensity earthquake should be kept at a low level. When the seismic isolation layer uses seismic isolation bearings and dampers, the seismic isolation layer should basically return to its original position after the earthquake. The restoring force corresponding to the maximum horizontal displacement of the seismic isolation layer under the action of the rare earthquake should be greater than the corresponding ratio of the sum of the yield force and the frictional force of the seismic isolation layer.

[0043] S6: Conduct a time - history analysis of the elastoplastic model of the isolated structure under the fortification earthquake; the input seismic wave should meet the requirements of the time - history seismic wave input in the code for time - history analysis. Based on the results of the time - history analysis of the elastoplastic model of the isolated structure under the fortification earthquake and the calculation results of the non - isolated structure under the fortification earthquake, obtain the actual horizontal seismic reduction coefficient β of the isolated structure. 1 , Compare β 1 with the target horizontal seismic reduction coefficient β. If β 1 is less than β, proceed to the next step of the design; otherwise, return to the third step for adjustment.

[0044] S7: Conduct a time - history analysis of the elastoplastic model of the isolated structure under the rare earthquake; the ultimate horizontal displacement of the isolation rubber bearing under the limit of the vertical average compressive stress should not be too large. Under the simultaneous action of the rare horizontal and vertical earthquakes, the tensile stress of the isolation rubber bearing should be kept within a certain safety range. The compressive stress of the isolation rubber bearing under the rare earthquake should be less than the limit value specified in the code.

[0045] S8: Conduct a comparative analysis of the vertical Z - vibration level VLZ of the elastoplastic model of the isolated structure; select the measured vibration source, similar - site vibration source or subway vibration simulation source for the subway vibration source. After conducting a time - history analysis using finite - element software, extract the acceleration time - history of the part with the maximum vibration, and calculate the vibration acceleration level and the vertical Z - vibration level respectively according to the formula , and compare them with the limit values given in the code. If either of them exceeds the limit value, it does not meet the vibration comfort requirements and needs to return to the third step for adjustment. a is the effective value of the vibration acceleration, a 0 is the reference acceleration, a 0 = 10 -6 m / s 2 . L a,i is the vibration acceleration level measured at the i - th center frequency, and Wi is the weighting factor in the Z - direction at this frequency.

[0046] Example:

[0047] Suppose a commercial building on top of a subway in a high - intensity seismic area is designed. This building needs to maintain structural safety and service comfort under subway operation and earthquake action. In this example, the three - dimensional combined isolation and energy - dissipation bearing in the invention patent application "CN115653119A" will be used for the design.

[0048] Design parameters:

[0049] Building height: 15 meters;

[0050] Number of building floors: 3 floors;

[0051] Building use: Commercial;

[0052] Seismic fortification intensity: 8 degrees;

[0053] Site category: Class II;

[0054] Structural form: Reinforced concrete frame structure;

[0055] Position of the isolation layer: Bottom of the first floor.

[0056] Specific design steps:

[0057] S1. Set the isolation goal and fortification standard:

[0058] Vibration reduction goal: The upper structure is designed for seismic isolation with one degree reduction.

[0059] Initial horizontal vibration reduction coefficient: Calculate the maximum ratio of the inter-story shear force (moment) of the non-isolated structure and the isolated structure for each floor. Assume the initial value is 0.5.

[0060] Position of the isolation layer: Bottom of the first floor.

[0061] S2. Design of the upper structure:

[0062] Hinged model at the bottom of the upper pier: Assume the height of the upper pier is 3 meters and the bottom adopts a hinged model.

[0063] Section design: According to the vibration reduction goal, combined with the layout of the building and the position of the isolation layer, carry out the section design of the upper structure. Assume the section size of each frame column is 600mm×600mm and the section size of the beam is 300mm×600mm.

[0064] S3. Design of three-dimensional isolation bearings and layout of the isolation layer:

[0065] Calculate the static working condition:

[0066] Vertical reaction force: Through static analysis, determine the vertical reaction force at the position of each isolation bearing node. Assume the vertical reaction force of each bearing node is 1000kN.

[0067] Select isolation bearings:

[0068] Isolation bearing model: According to the vertical reaction force of 1000kN, select the three-dimensional combined isolation energy dissipation bearing in the patent "CN115653119A", and its designed compressive bearing capacity is 1200kN.

[0069] Adjust mechanical characteristics:

[0070] Shear resistance design:

[0071] Area and thickness of the rubber layer: The area of the rubber layer is 0.5m 2 , and the thickness is 0.1m.

[0072] Lead core size: The diameter of the lead core is 0.05 m.

[0073] U-shaped steel bar size and quantity: The diameter of the U-shaped steel bar is 0.02 m, and the quantity is 10 pieces.

[0074] Compressive design:

[0075] Lead rubber bearing size: The height is 0.3 m.

[0076] Disc spring group: The diameter of each disc spring is 0.2 m, the quantity is 5 pieces, and the placement method is in series.

[0077] Tensile design:

[0078] Preloaded disc spring group: The preload is 200 kN.

[0079] Steel cable: Provides additional tensile function, and the diameter is 0.03 m.

[0080] S4. Establish an elastoplastic model of the seismic isolation structure:

[0081] Modeling software: Use Etabs for modeling and analysis.

[0082] Model verification: By comparing the calculation results of the non-seismic isolation structure, verify the rationality of the seismic isolation structure model. Assume that the inter-story shear force of the non-seismic isolation structure under the fortification earthquake is 1500 kN, the inter-story shear force of the seismic isolation structure is 750 kN, and the initial horizontal seismic reduction coefficient is 0.5.

[0083] S5. Conduct wind resistance, eccentricity of the seismic isolation layer, and restoring force of the seismic isolation layer check calculations:

[0084] Wind resistance bearing capacity:

[0085] Partial coefficient of wind load: 1.4

[0086] Standard value of the horizontal shear force of the seismic isolation layer under wind load: 300 kN

[0087] Design value of the wind resistance bearing capacity of the seismic isolation layer: 500 kN

[0088] Wind resistance bearing capacity of the seismic isolation layer: According to the "Standard for Seismic Isolation Design of Buildings" GB / T 51408-2021, the wind resistance bearing capacity of the seismic isolation layer should not be less than 1.5 times the standard value of the horizontal shear force of the seismic isolation layer under wind load. The calculation result is 1.4×300 kN = 420 kN, which is less than 500 kN, meeting the requirements.

[0089] Eccentricity:

[0090] Coincidence of the stiffness center and the mass center: By adjusting the layout of the seismic isolation layer, ensure the coincidence of the stiffness center and the mass center.

[0091] Eccentricity under the action of fortification intensity earthquake:

[0092] The distances from the resultant line of the total seismic forces in the X and Y directions of the structure above the isolation layer to the stiffness center of the isolation layer: ex and ey

[0093] The coordinates of the i-th bearing of the isolation layer: Xi and Yi

[0094] The axial force of the i-th bearing of the isolation layer under the representative value of gravity load: Nl,i

[0095] The horizontal equivalent stiffness of the i-th bearing of the isolation layer: Kex,i and Key,i

[0096] The coordinates of the stiffness center: Xk and Yk

[0097] The coordinates of the centroid: Xg and Yg

[0098] Eccentricity: ex = |Xg - Xk|

[0099] Eccentricity: ey = |Yg - Yk|

[0100] Calculation of elastic radius:

[0101] The torsional stiffness of the isolation layer: Kt

[0102] Elastic radius:

[0103] Elastic radius:

[0104] Calculation of eccentricity ratio:

[0105] Eccentricity ratio:

[0106] Eccentricity ratio:

[0107] Calculation result: Assume ρ x = 0.02 = 2% and ρ y = 0.02 = 2%, both are less than 3%, meeting the requirements.

[0108] The calculation result is 0.02, remaining at a low level.

[0109] Restoring force:

[0110] According to "Standard for Seismic Isolation Design of Buildings" GB / T 51408 - 2021:

[0111] The maximum horizontal displacement under the action of rare earthquake: 200 mm

[0112] The restoring force corresponding to the maximum horizontal displacement of the isolation layer under the action of rare earthquake: 500 kN

[0113] Yield force of the isolation layer: 300 kN

[0114] Frictional force of the isolation layer: 100 kN

[0115] Calculation result: 500 kN, which is greater than 1.2×(300 kN + 100 kN) = 480 kN, that is, the restoring force corresponding to the maximum horizontal displacement of the isolation layer under rare earthquake action is greater than 1.2 times the sum of the yield force and frictional force of the isolation layer, meeting the requirements.

[0116] S6. Conduct time - history analysis of the elastic - plastic model of the isolated structure under the fortification earthquake:

[0117] Input earthquake wave: Select the time - history earthquake wave that meets the code requirements, assuming the peak acceleration is 0.3g.

[0118] Horizontal seismic reduction coefficient: According to the Standard for Seismic Isolation Design of Buildings GB / T 51408 - 2021, the actual horizontal seismic reduction coefficient β 1 :

[0119] Input earthquake wave: Select the time - history earthquake wave that meets the code requirements, assuming the peak acceleration is 0.3g.

[0120] Inter - story shear force of the non - isolated structure: 1500 kN

[0121] Inter - story shear force of the isolated structure: 675 kN

[0122] Actual horizontal seismic reduction coefficient β 1 : 675 / 1500 = 0.45

[0123] Target horizontal seismic reduction coefficient β: 0.5

[0124] Comparison result: β 1 < β, meeting the requirements, proceed to the next step of design.

[0125] S7. Conduct time - history analysis of the elastic - plastic model of the isolated structure under rare earthquake:

[0126] Compressive stress and tensile stress:

[0127] Limit value of vertical average compressive stress: 10 MPa

[0128] Compressive stress under rare earthquake action: The calculation result is 8 MPa, which is less than 10 MPa, meeting the requirements.

[0129] Tensile stress under rare earthquake action: The calculation result is 0.6 MPa, which is less than 1 MPa, remaining within the safe range.

[0130] Deformation check:

[0131] Ultimate horizontal displacement: The calculated result is 250 mm, which is less than the code limit of 300 mm, meeting the requirements.

[0132] S8. Conduct a vibration level comparison analysis on the elastoplastic model of the isolated structure:

[0133] Vibration acceleration level:

[0134] Effective value of vibration acceleration a: 0.05 m / s 2

[0135] Reference acceleration a 0 : 10 -6 m / s 2

[0136] Calculation formula:

[0137] Calculation result:

[0138] Vertical Z vibration level VLZ:

[0139] Center frequency: Assume 10 frequency points, and the vibration acceleration level and weighting factor for each frequency point are shown in the following table:

[0140] i <![CDATA[L a,i (dB)]]> wi 1 100 1 2 102 1 3 104 1 4 106 1 5 108 1 6 110 1 7 112 1 8 114 1 9 116 1 10 118 1

[0141] Calculation formula:

[0142] Calculation result:

[0143] Vibration level comparison:

[0144] Code limit: The limit of vibration acceleration level is 120 dB, and the limit of vertical Z vibration level is 120 dB.

[0145] Comparison result: The vibration acceleration level of 104 dB and the vertical Z vibration level of 119 dB are both less than the code limit, meeting the requirements.

[0146] Through the specific design steps and calculation analysis provided in this embodiment, the three-dimensional isolation / vibration support design method of the present invention has been successfully applied to the commercial building project on the top of the subway. The design results show that the isolated structure has good isolation performance and structural safety under the action of fortification earthquake and rare earthquake, and at the same time meets the requirements of vibration comfort. This provides a reliable reference and practical guidance for the isolation design of similar projects.

[0147] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the various embodiments, reference can be made to each other. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple. For the relevant parts, reference can be made to the description in the method section.

[0148] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. A design method for a three-dimensional seismic isolation / vibration support for a subway superstructure, characterized in that: The following steps are involved: S1: Setting seismic isolation goals and fortification standards; S2: superstructure design; S3: Design three-dimensional isolation bearings and arrange isolation layers according to the shear, compression and tension resistance; S4: Establish an elastoplastic model of the seismic isolation structure; S5: Verify the wind resistance of the seismic isolation structure, the eccentricity of the seismic isolation layer, and the restoring force of the seismic isolation layer; S6: Conduct earthquake time history analysis on the elastoplastic model of the seismic isolation structure; S7: Conduct rare earthquake time history analysis on the elastoplastic model of the seismic isolation structure; S8: Comparative analysis of vibration levels of the elastoplastic model of the isolation structure.

2. The design method of a three-dimensional seismic isolation / vibration support for a subway superstructure according to claim 1 is characterized in that: In step S1, according to engineering requirements and economic feasibility, the upper structure is lowered by one degree or half a degree for seismic isolation design, and the initial horizontal damping coefficient is calculated, and the reasonable isolation layer position is determined.

3. The design method of a three-dimensional seismic isolation / vibration support for a subway superstructure according to claim 1 is characterized in that: In step S3, the static working condition of the non-isolated structure is calculated to determine the vertical reaction force at the node position of the isolation bearing to be arranged under the static action, and then the isolation bearing is selected according to the vertical reaction force.

4. The design method of a three-dimensional seismic isolation / vibration support for a subway superstructure according to claim 1 is characterized in that: In step S4, the seismic isolation structure is modeled and analyzed by Etabs, Sap2000 or Midas.

5. The design method of a three-dimensional seismic isolation / vibration support for a subway superstructure according to claim 1 is characterized in that: In step S5, the wind bearing capacity of the seismic isolation layer is greater than the product of the wind load partial coefficient and the standard value of the horizontal shear force of the seismic isolation layer under the wind load.

6. The design method of a three-dimensional seismic isolation / vibration support for a subway superstructure according to claim 1 is characterized in that: In step S6, the actual horizontal damping coefficient β1 of the seismic isolation structure is obtained according to the earthquake time-history analysis results of the elastoplastic model of the seismic isolation structure and the earthquake calculation results of the non-seismic isolation structure. β1 is compared with the target horizontal damping coefficient β. If β1 is less than β, the next design step is carried out, otherwise, return to the third step for adjustment.

7. The design method of a three-dimensional seismic isolation / vibration support for a subway superstructure according to claim 1 is characterized in that: In step S5-step S8: if the three points in step S5 cannot be met at the same time, return to step S3 for adjustment; in step S6, check whether the new horizontal damping coefficient meets the requirements, if not, return to step S3 for adjustment; if in step S7, the seismic isolation bearing is subjected to the compressive stress, tensile stress and deformation verification under the action of rare earthquakes, if not, return to step S3 for adjustment; in step S8, the vibration level includes the vibration acceleration level and the vertical Z vibration level VL Z ; Both the vibration acceleration level and the vertical Z vibration level need to be less than the limit values ​​given by the corresponding specifications, otherwise return to step S3 for adjustment.

8. The design method of a three-dimensional seismic isolation / vibration support for a subway superstructure according to claim 7 is characterized in that: In step S8, the vibration acceleration level is calculated as follows: Where a is the effective value of vibration acceleration, a0 is the reference acceleration, a0=10 -6 m / s 2 . Vertical Z vibration level VL Z The calculation formula is: Where L a,i is the vibration acceleration level measured at the ith center frequency, and Wi is the weighting factor in the Z direction at this frequency.

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