Design method for seismic isolation structure of subway depot superstructure development

Abstract

A design method for a seismic isolation structure in the development of a subway depot superstructure is proposed. The seismic isolation structure reduces the seismic response of the superstructure, while simultaneously improving the stress condition of the substructure due to the reduced seismic response. The cross-section of the substructure frame columns can be effectively controlled, significantly improving the seismic performance of the entire structural system and ensuring structural safety and reliability. Furthermore, the second-floor slab within the projection range of the superstructure is reduced by one floor, resulting in a substantial reduction in the mass of the second floor, further decreasing the seismic response, improving the overall stress condition, effectively controlling the cross-section of the first-floor frame columns, and significantly saving costs. With only the large foundation floor below the isolation layer, the possibility of weak or soft floors is effectively reduced. At the same time, the height of the first floor of the superstructure is increased, allowing for more flexible layout of the first floor.

Description

Technical Field

[0001] This invention relates to the technical field of seismic isolation and vibration reduction in civil engineering, and in particular to a design method for a seismic isolation structure for the development of a subway depot roof. Background Technology

[0002] Development above subway depots typically involves multi-functional complexes integrating subway, public transportation, residential, commercial, and office spaces, improving land utilization and increasing revenue. The main characteristic of such developments is that the lower level houses industrial buildings, while the upper level houses residential or public buildings, with different structural forms chosen for the two parts due to their different functions. In high-seismic-intensity seismic zones, seismic isolation structures are increasingly becoming the preferred option for subway depot developments.

[0003] Currently, the seismic isolation layers in subway depot superstructure development are mostly located at the bottom of the upper single-tower structure and the top of the second floor of the main chassis. However, actual design reveals three main problems: First, because the vertical components of the upper structure within the track area cannot be grounded, the upper and lower structures have different stiffnesses. To meet the required fixed-stiffness ratio, a large number of shear walls need to be installed on the first and second floors of the main chassis, increasing costs. Second, the addition of numerous shear walls increases the overall stiffness and mass of the structure, thus increasing seismic forces. Third, the significant difference in floor height between the first and second floors of the main chassis in the depot leads to a large difference in stiffness, easily creating both a weak and soft story on the first floor. Therefore, a new design method for seismic isolation structures in subway depot superstructure development is needed, which offers advantages such as a reasonable structural form and good seismic performance while minimizing costs.

[0004] Therefore, in view of the above-mentioned defects, the designers of this invention, through dedicated research and design, and by integrating years of experience and achievements in related industries, have developed a method for designing a seismic isolation structure for the development of subway depot roofs, in order to overcome the aforementioned defects. Summary of the Invention

[0005] The purpose of this invention is to provide a design method for seismic isolation structures for subway depot roofs, which can overcome the above-mentioned defects, has a reasonable structural form, good seismic performance, and can also effectively save costs and reduce construction costs.

[0006] To achieve the above objectives, this invention discloses a method for designing a seismic isolation structure for the development of a subway depot roof, characterized by comprising the following steps:

[0007] Step S1. Determine the location of the seismic isolation layer; based on the building's function and the dimensions and arrangement of the vertical components of the superstructure and the substructure, determine a reasonable location for the seismic isolation layer;

[0008] Step S2. Define the vibration reduction target and fortification standard; based on the project conditions and existing experience, determine the vibration reduction target after adopting seismic isolation design, determine the target horizontal vibration reduction coefficient, and define the fortification standard of the structure;

[0009] Step S3. Superstructure layout: Based on the determined seismic reduction target, combined with the building layout and the location of the seismic isolation layer, the superstructure is determined according to the hinged model at the bottom of the upper support pier in the seismic isolation layer. By adjusting the model, the superstructure meets the corresponding seismic reduction target and fortification standard, and the number and location of the horizontal seismic isolation structure nodes that need to be arranged are determined.

[0010] Step S4. Arrange the isolation layer structure according to the support reaction force; calculate the static working condition of the non-isolation model, and determine the vertical reaction force at the node position of the horizontal isolation structure to be arranged under static action; determine the parameters of the isolation support according to the vertical reaction force.

[0011] Step S5. Calculate the horizontal damping coefficient; analyze the superstructure with isolation layer and the chassis, and calculate the isolation and non-isolation models according to the design earthquake to determine the horizontal damping coefficient. If the horizontal damping coefficient does not meet the requirements, adjust the isolation bearings to meet them.

[0012] Step S6. Design of the superstructure of the isolation layer; Determine the maximum value of the seismic influence coefficient after damping based on the damping coefficient, establish a non-isolated model, and verify the bearing capacity of the superstructure of the isolation layer under frequent earthquakes, taking into account the horizontal damping coefficient.

[0013] Step S7. Design of the seismic isolation layer structure; verify the maximum compressive stress of the bearing under the representative value of gravity load, and verify the tensile stress, compressive stress and maximum displacement of the bearing under rare earthquake action; for the seismic isolation layer piers, columns and connected components, use the vertical force, horizontal force and moment at the bottom of the seismic isolation bearing under rare earthquake action to verify the bearing capacity.

[0014] Step S8. Design of the substructure below the seismic isolation layer: The embedded stiffness ratio of the structure below the seismic isolation layer is checked and the normal section is designed according to the moderate or major earthquake, and the oblique section is designed according to the rare earthquake.

[0015] Step S9. Overall structural calculation; perform overall internal force and displacement calculation and analysis on the seismic isolation model under frequent earthquakes; perform elastoplastic time history verification analysis on the seismic isolation model under major earthquakes.

[0016] In step S1, based on the building's function and the dimensions and layout of the upper residential buildings and the vertical support structure of the lower large base, the location of the seismic isolation layer is determined to be the top of the first floor of the large base. The second-floor slab and the upper transfer structure are directly installed at the lower end of the first-floor shear wall of the upper structure, and the upper transfer structure is directly connected to the seismic isolation layer. The seismic isolation layer consists of upper supports, seismic isolation bearings, and lower supports. The lower transfer structure is located at the top of the first floor of the large base. The first-floor top beam is supported by the first-floor vertical columns and the first-floor shear wall.

[0017] In step S2, based on Article 12.2.5 of the "Code for Seismic Design of Buildings" and its explanatory notes, and combined with the project conditions and existing experience, the target horizontal damping coefficient is controlled between 0.30 and 0.40 in the seismic isolation design, so as to achieve the design goal of reducing the seismic fortification intensity of the upper residential buildings by one degree.

[0018] In step S3, the superstructure is rationally arranged by combining the building layout, the location of the seismic isolation layer, and the column grid location of the substructure. When arranging the upper supports of the seismic isolation layer, no upper supports are arranged in the location without walls, and upper supports of the seismic isolation layer are arranged at intervals in the location with walls. The spacing between each row of upper supports is uniform. After determining the location of the upper supports of the seismic isolation layer, the bottom of the upper supports of the seismic isolation layer is hinged, and the superstructure is made to meet the corresponding vibration reduction target and fortification standard through modeling, and the specific location of the seismic isolation layer is determined.

[0019] In step S4, Yingjianke performs static load calculations on the non-isolated model to obtain the bottom vertical reaction force of the upper support of the isolation layer to be installed; the minimum area of ​​the isolation bearing is determined by dividing the vertical reaction force by the vertical pressure limit specified in 12.2.3 of the "Code for Seismic Design of Buildings".

[0020] Specifically: seismic isolation bearings with higher stiffness and tensile strength are arranged around the perimeter of the structure, using lead-core seismic isolation bearings, while seismic isolation bearings with lower stiffness are arranged in the center, using natural rubber bearings.

[0021] In step S5, the lower hinge of the non-isolated model is removed by Yingjianke, and the isolation layer and the large chassis model of the relevant range are established, and the model is defined as an isolation model.

[0022] Specifically, the first three periods of the non-isolated model, the first three periods of the superstructure of the isolated model, and the three periods with the largest vibration mass participation coefficient of the large chassis were selected for wave selection. Since the non-isolated model does not have a large chassis, the large chassis period and the large chassis period of the isolated model were taken to be the same value. According to the method provided in 5.1.2 of the "Code for Seismic Design of Buildings" and its explanatory notes, 5 natural waves and 2 artificial waves were selected for time history analysis. The average value of the results was taken. The shear force and overturning moment of each story above the isolation bearing of the non-isolated model and the isolated model were compared. The ratio of the two is the horizontal damping coefficient.

[0023] Specifically: a horizontal damping coefficient between 0.3 and 0.4 is acceptable. If the horizontal damping coefficient is less than 0.30, it indicates that there are too few lead-core seismic isolation bearings, the yield strength ratio is too small, and the horizontal seismic attenuation is too great. In order to eliminate the need to calculate vertical seismic events for the upper frame-supported residential buildings, it is necessary to increase the number of lead-core seismic isolation bearings. If the horizontal damping coefficient is greater than 0.40, it indicates that there are too many lead-core seismic isolation bearings, the yield strength ratio is too large, and the damping effect is poor. It is necessary to reduce the number of lead-core seismic isolation bearings and adjust the arrangement of the seismic isolation bearings to meet the requirements.

[0024] As can be seen from the above, the seismic isolation structure design method for the subway depot roof of the present invention has the following effects:

[0025] 1. The use of seismic isolation structures reduces the seismic response of the subway depot superstructure. At the same time, the stress condition of the substructure is improved due to the reduced seismic response of the superstructure. The cross-section of the substructure frame columns can be effectively controlled, and the seismic performance of the entire structural system is significantly improved, ensuring the safety and reliability of the structure. By moving the seismic isolation layer to the top of the first floor and separating the superstructure from the second-floor structure of the large base outside its projection range, the required embedment stiffness ratio can be met by simply arranging shear walls on the first floor of the large base, and the original shear walls on the second floor can be completely eliminated. At the same time, the mutual influence between the superstructure and the second-floor structure outside the projection range is reduced, and the cross-section of the frame columns on the second floor outside the projection range is effectively controlled. The second-floor structure within the projection range of the superstructure has one less top floor slab. The mass of the second floor is significantly reduced, further reducing the seismic response, improving the overall stress condition, effectively controlling the cross-section of the frame columns on the first floor, and greatly saving costs. On the other hand, with only the first floor of the large base below the seismic isolation layer, the possibility of weak and soft floors is effectively reduced. At the same time, the height of the first floor of the superstructure is increased, and the arrangement of the first floor of the superstructure is more flexible.

[0026] 2. Arrange the positions of the upper supports (bearings) according to the reasonable superstructure form, so that the position of the seismic isolation bearings and the stress are as uniform as possible, which facilitates the subsequent adjustment of the seismic isolation model and the selection of seismic isolation bearings; by appropriately enlarging the range of the seismic isolation layer through the transformation structure arrangement, so that the range of the seismic isolation layer corresponds to the column grid of the first floor, the bearing transformation can be reduced, and by "adding boots" to the superstructure, its overturning resistance can be enhanced.

[0027] 3. It effectively mitigates the impact of large edge deformation caused by structural torsion, making it easier to resist the tensile forces that may occur at the edge supports. The combined use of lead core supports and natural rubber supports can improve the efficiency of seismic isolation and ensure economy.

[0028] 4. Perform overall calculations on the seismic isolation structure. Obtain the maximum deformation and stress of the supports, as well as the deformation and damage of the superstructure, through elastoplastic time history analysis under rare earthquakes. Adjust the support selection and arrangement to ensure that the structure meets the established seismic reduction targets and relevant standard and specification requirements, further improving the stability of the designed building. Optimize the design of the seismic isolation structure to further meet the corresponding requirements, improve the efficiency of seismic isolation, and ensure economy.

[0029] The details of this invention will become apparent from the following description and the accompanying drawings. Attached Figure Description

[0030] Figure 1 The diagram shows an initial design for a seismic isolation structure for a vehicle depot roof, as described in this invention.

[0031] Figure 2 Showing Figure 1 Elevation diagram of the upper-middle residential area.

[0032] Figure 3 The diagram shows a schematic elevation of the upper residential building within the design method for the seismic isolation structure of the subway depot roof development according to the present invention.

[0033] Figure 4 This diagram shows the elevation planar position of the second floor of the large chassis according to an embodiment of the present invention.

[0034] Figure 5 This diagram shows the horizontal position of the seismic isolation layer and the top elevation of the first floor of the main chassis according to an embodiment of the present invention.

[0035] Figure 6 A schematic planar diagram of the arrangement of the seismic isolation layer and seismic isolation bearings in an embodiment of the present invention is shown.

[0036] Figure label:

[0037] 1. Residential building; 11. First floor shear wall of the superstructure; 2. Superstructure transfer structure; 3. Seismic isolation layer; 31. Superstructure support structure; 32. Seismic isolation component; 33. Substructure support structure; 4. Substructure transfer structure; 5. Second floor of the main base; 51. Ordinary beam at the top of the second floor; 52. Vertical column of the second floor; 53. Shear wall of the second floor; 6. First floor of the main base; 61. Ordinary beam at the top of the first floor; 62. Vertical column of the first floor; 63. Shear wall of the first floor; 7. Floor slab; 71. Top floor slab of the third floor; 72. Top floor slab of the second floor; 73. Top floor slab of the first floor; 8. Seismic joint. Detailed Implementation

[0038] See Figures 1 to 6 This invention demonstrates the design method for developing a seismic isolation structure for the subway depot roof.

[0039] The seismic isolation structure design method for subway depot superstructure development of this invention belongs to the field of seismic isolation technology in civil engineering. It is applied to subway depot superstructure development projects and is mainly used to solve the stiffness problem and high cost problem caused by the different structural forms of the upper and lower structures. In a general sense, the target structure can be a residential building, educational building, hospital, or commercial building, etc., for superstructure development of subway depots.

[0040] In one specific embodiment, the seismic isolation structure design method for the subway depot roof of the present invention can be used. Figure 1 and Figure 2 The initial design of the vehicle depot roof development vibration isolation structure shown in the specific embodiment is optimized, combined with Figure 1 and Figure 2 The initial plan is as follows:

[0041] A seismic isolation structure was developed above a train depot in Beijing. The main chassis has two floors: the first floor is 14.6m high and serves as a subway maintenance depot; the second floor is 5.4m high and is an attached parking garage for the upper residential buildings; the upper tower is residential building 1; among them, residential building 1 is a shear wall structure, and the main chassis (including the second floor 5 and the first floor 6) is a frame-shear wall structure. Figure 1 and Figure 2 The initial plan involved installing a seismic isolation layer on top of the second-floor 5th layer of the large chassis, such as... Figure 1-2 As shown, the lower end of the vertical support structure 11 (a shear wall in this embodiment) of the first floor of the upper residential building is provided with a floor slab 71 and an upper transfer structure 2 (a transfer beam with a beam height of 1.4m in this embodiment); the upper transfer structure 2 is connected to the seismic isolation layer 3; the seismic isolation layer 3 is composed of an upper support structure 31, a seismic isolation component 32, and a lower support structure 33 (an upper support pier, a seismic isolation bearing, and a lower support pier in this embodiment, respectively); the lower end of the lower support structure 33 is provided with a second-floor roof slab 72 and a lower transfer structure 4 (a transfer beam with a beam height of 1.8m and built-in steel in this embodiment); the lower transfer structure 4 is located on the top of the second floor 5 of the large base. Within the projection range of the upper residential building 1, and outside the projection range of the upper residential building 1, is the second-floor roof ordinary beam 51; the second-floor roof ordinary beam 51 (including the lower transfer structure 4 within the projection range of the upper residential building and the second-floor roof ordinary beam 51 outside the projection range of the upper residential building) is supported on the second-floor vertical support structure (which may include the second-floor vertical column 52 and the second-floor shear wall 53) (in this embodiment, it is a frame column and a shear wall), and together with the first-floor roof ordinary beam 61 (beam height 1.2m) and the first-floor roof slab 73, it is supported on the first-floor vertical support structure (which may include the first-floor vertical column 62 and the first-floor shear wall 63) (in this embodiment, it is a frame column and a shear wall).

[0042] According to the "Code for Seismic Design of Buildings" (hereinafter referred to as the "Code"), the relevant components within the projection range of the first floor of a single-tower residential building and the second floor of a large-base residential building should meet the embedment stiffness ratio requirement. That is, the total shear stiffness of the lateral force resisting components within the projection range of the second floor of the large-base residential building should meet the embedment requirement of twice the shear stiffness of the first floor of the residential building (the "relevant range" can be extended by 20m or 3 spans from the projection range of the upper residential structure (main building, including the podium if there is one)). To meet this requirement, shear walls should be arranged at appropriate locations on the first and second floors of the large-base building according to the building function (such as the second-floor shear wall 53 and the first-floor shear wall 63 as shown in the figure). Furthermore, due to the significant difference in floor height between the first and second floors of the large-scale chassis, to ensure that the lateral stiffness ratio and shear capacity ratio of the second and first floors meet the code requirements—that is, to prevent the first floor from becoming a weak or soft floor—different thickness shear walls are used for the first and second floors. The first-floor shear wall (63) can be an 850mm thick steel plate shear wall, while the second-floor shear wall (53) can be a 650mm thick steel plate shear wall. Therefore, this extensive use of shear walls results in… Figure 1 and 2 The structure in this case has high overall stiffness and mass. During an earthquake, the seismic force is related to the structure's stiffness and mass; the greater the stiffness and mass, the greater the seismic force the structure can withstand. To resist the corresponding seismic force, the dimensions of the structural members must also increase accordingly, leading to a further increase in mass and ultimately resulting in high costs.

[0043] Therefore, the inventors of this invention, through creative labor, invented the following... Figure 3 The method for designing a seismic isolation structure for the superstructure of a subway depot, as shown, may include the following steps:

[0044] Step S1. Determine the location of the seismic isolation layer; based on the building's function and the dimensions and arrangement of the vertical components of the superstructure and substructure, determine a reasonable location for the seismic isolation layer. Specifically, refer to... Figure 3Based on the building's functional use and the dimensions and layout of the vertical support structure (which may include second-floor vertical columns 52, second-floor shear walls 53, first-floor vertical columns 62, and first-floor shear walls 63) of the upper residential building 1 and the lower large base, the location of the seismic isolation layer 3 is determined to be at the top of the first floor 6 of the large base. This requires increasing the first-floor height of the upper residential building 1, eliminating the third-floor roof slab 71, and directly installing the second-floor roof slab 72 at the lower end of the first-floor shear wall 11 of the upper structure, connecting it to the upper transfer structure 2. The beam height of the upper transfer structure 2 is 1.4m. The upper transfer structure 2 is directly connected to the seismic isolation layer 3. The seismic isolation layer 3 also consists of upper supports, seismic isolation bearings, and lower supports. To reduce transfers, based on the first-floor column grid layout, the lower supports of the seismic isolation layer are directly connected to the first-floor vertical columns 62, thereby expanding the range of the seismic isolation layer 3 to be no less than the projected range of the upper residential building 1. The upper transfer structure 2 is located within the range of the seismic isolation layer 3. Within the isolation layer 3, the ordinary beam 51 on the top of the second floor and the vertical column 52 on the second floor within the non-isolation layer range are separated by a seismic joint 8. To meet the requirement of "not hindering the large deformation of the isolation layer under rare earthquakes" in 12.2.7 of the "Code for Seismic Design of Buildings", the joint width is at least 0.5m. The ordinary beam 51 on the top of the second floor within the non-isolation layer range is supported on the vertical column 52 on the second floor (given that the second floor 5 of the large base does not need to meet the requirement of the isolation layer's embedment stiffness ratio, the shear wall 53 on the second floor within the non-isolation layer range can be removed). The lower end of the lower support pier 33 is composed of the first floor slab 73 and the lower transfer structure 4 (beam height 1.8m, with built-in steel). The lower transfer structure 4 is located on the top of the first floor 6 of the large base. The top beam of the first floor (including the lower transfer structure 4 within the projection range of the upper residential building and the ordinary beam 61 on the top of the first floor outside the projection range of the upper residential building) is supported on the vertical column 62 and the shear wall 63 of the first floor.

[0045] Step S2. Define the seismic reduction target and fortification standard; based on the project conditions and existing experience, determine the seismic reduction target after adopting seismic isolation design, determine the target horizontal seismic reduction coefficient, and define the fortification standard of the structure; specifically, according to Article 12.2.5 of the "Code for Seismic Design of Buildings" and its explanatory notes, combined with the project conditions and existing experience, the target horizontal seismic reduction coefficient in the seismic isolation design is controlled between 0.30 and 0.40 to achieve the design target of reducing the seismic fortification intensity of the upper residential buildings by one degree (the horizontal seismic reduction coefficient is the maximum ratio of the inter-story shear force and the overturning moment of each story obtained by elastic calculation); according to the "Code for Seismic Design of Buildings"... According to Article 3.11 and its explanatory notes of the "Technical Specification for Concrete Structures", the performance targets of the structure are determined. In this embodiment, the seismic performance target of the structure is set as C+ level. The performance levels under frequent earthquakes, design earthquakes, and estimated rare earthquakes are 1, 3, and 4 respectively (technical terms, as specified in the standard). Among them, the performance target under design earthquakes is slightly higher than level 3, that is, to control the transfer structure (which may include the upper transfer structure 2 and the lower transfer structure 4) and the upper and lower supports to maintain elasticity (linear deformation, which can be recovered when the load disappears) under design earthquakes, that is, to improve the design requirements of the transfer structure and the upper and lower supports.

[0046] Step S3. Superstructure Layout; Based on the determined seismic reduction targets, combined with the building layout and the location of the seismic isolation layer, the superstructure is determined according to the bottom hinged model of the upper support pier in the seismic isolation layer (non-seismic isolation model, without seismic isolation bearings and its substructure). By adjusting the model, the superstructure meets the corresponding seismic reduction targets and fortification standards, and the number and location of the horizontal seismic isolation structure nodes to be arranged are determined. Specifically, based on the determined seismic reduction targets, combined with the building layout, the location of the seismic isolation layer 3, and the column grid location of the substructure (which may include the second floor 5 and the first floor 6 of the large base), the superstructure is rationally arranged. The superstructure includes the upper residential building 1, the upper transfer structure 2, and the upper support pier of the seismic isolation layer, such as... Figure 4 and Figure 5 As shown; when arranging the upper supports of the seismic isolation layer, the upper supports 31 of the seismic isolation layer are not arranged in the locations without walls, and the upper supports of the seismic isolation layer are arranged at intervals in the locations with walls; the spacing between each row of upper supports is uniform; after determining the position of the upper supports of the seismic isolation layer, the column base of the upper supports 31 of the seismic isolation layer is hinged, and the model is used (optionally using the structural calculation software Yingjianke (or other available structural software, Yingjianke is used in this embodiment). This model is a non-seismic isolation model. By adjusting the model, the upper structure meets the corresponding vibration reduction target and fortification standard, and the specific arrangement position of the seismic isolation layer 3 is determined.

[0047] Step S4. Arrange the seismic isolation layer structure according to the support reaction force; calculate the static working condition of the non-isolation model to determine the vertical reaction force at the node position of the horizontal seismic isolation structure to be arranged under static action; determine the parameters of the seismic isolation bearings according to the vertical reaction force; specifically, the seismic isolation layer structure can be arranged according to the support reaction force; preferably, the bottom vertical reaction force of the upper support of the seismic isolation layer to be arranged can be calculated by Yingjianke calculation of the non-isolation model under static working condition; determine the minimum area of ​​the seismic isolation bearing (A=N / σ) according to the vertical reaction force divided by the vertical pressure limit specified in 12.2.3 of the "Code for Seismic Design of Buildings". In this case, the structure will be torsional, the displacement of the periphery of the structure will be large, and it may also be subjected to vertical tension. The seismic isolation bearings 321 with larger stiffness and larger tensile strength are arranged around the periphery of the structure. In a preferred embodiment of the present invention, lead core seismic isolation bearings can be used to arrange around the periphery of the structure, and the seismic isolation bearings 322 with smaller stiffness are arranged in the center position. Natural rubber bearings can be used, such as Figure 6 As shown.

[0048] Step S5. Calculate the horizontal damping coefficient; calculate and analyze the superstructure with isolation layer and the chassis (isolation model) within the relevant range, and calculate the isolation and non-isolation models according to the design earthquake. Use time history analysis to calculate the horizontal damping coefficient. If the horizontal damping coefficient does not meet the requirements, adjust the isolation bearings to meet them. If it still does not meet the requirements, readjust the stiffness of the superstructure or substructure and redesign the isolation structure. Specifically, it is preferable to use Yingjianke to cancel the lower hinge of the non-isolation model and establish a large chassis model with isolation layer and relevant range, and define the model as an isolation model. Based on the seismic design calculations using both isolated and non-isolated models, the first three periods of the non-isolated model and the first three periods of the superstructure (which may include the upper residential building 1, the upper transition structure 2, and the upper support structure 31) of the isolated model, as well as the three periods with the highest vibration mass participation coefficient of the large chassis, were selected for wave selection. Since the non-isolated model does not have a large chassis, the large chassis period can be taken as the same value as that of the isolated model, and since both represent the large chassis, they can be considered essentially equivalent. Following the method provided in Section 5.1.2 of the Seismic Design Code and its explanatory notes, 5 natural waves and 2 artificial waves were selected for time history analysis, and the average value was taken. The results were then compared with the non-isolated model. The ratio of the shear force and overturning moment of each story above the seismic isolation bearings in the seismic isolation model is the horizontal damping coefficient. If the horizontal damping coefficient is between 0.3 and 0.4, it meets the requirements. If the horizontal damping coefficient is less than 0.30, it indicates that there are too few lead-core seismic isolation bearings, the yield strength ratio is too small, and the horizontal seismic attenuation is too great. To prevent vertical seismic calculations for the upper frame-supported residential buildings, more lead-core seismic isolation bearings need to be added. If the horizontal damping coefficient is greater than 0.40, it indicates that there are too many lead-core seismic isolation bearings, the yield strength ratio is too large, and the damping effect is poor. The number of lead-core seismic isolation bearings needs to be reduced. Adjusting the arrangement of the seismic isolation bearings to meet the requirements usually suffices. If it still does not meet the requirements, the upper or lower structure needs to be readjusted, and steps S3 to S5 can be repeated for redesign.

[0049] Step S6. Design of the superstructure of the isolation layer; determine the maximum value of the seismic influence coefficient after damping based on the damping coefficient, establish a non-isolated model, and verify the bearing capacity of the superstructure of the isolation layer under frequent earthquakes, considering the horizontal damping coefficient. If it does not meet the requirements, readjust the superstructure and redesign it.

[0050] Step S7. Design of the seismic isolation layer structure; verify the maximum compressive stress of the bearings under the representative value of gravity load; perform wind resistance verification, horizontal force verification, eccentricity verification, yield-to-weight ratio verification, etc.; verify the tensile stress, compressive stress and maximum displacement of the bearings under rare earthquake action; for the seismic isolation layer piers, columns and connected components, use the vertical force, horizontal force and moment at the bottom of the seismic isolation bearings under rare earthquake action to verify the bearing capacity. If the requirements are not met, the isolation layer structure should be readjusted to meet them. Specifically, according to Article 12.2 of the Code for Seismic Design of Buildings (Code for Seismic Design of Buildings) and its explanatory notes, the maximum compressive stress and vertical deformation difference of the isolation bearings under the representative value of gravity load should be verified. Wind resistance, horizontal force, eccentricity, yield-to-weight ratio, and elastic restoring force should also be verified. The tensile stress, compressive stress, and maximum displacement of the isolation bearings under rare earthquakes should be verified. For the upper and lower piers 31 and 33 of the isolation layer, the upper transfer structure 2 and lower transfer structure 4 directly connected to the isolation layer, and the vertical column 62 directly connected to the lower transfer structure 4, the bearing capacity should be verified using the vertical force, horizontal force, and moment at the bottom of the isolation bearings under rare earthquakes, and shear elasticity and bending non-yielding should be considered. If the requirements are not met, the isolation layer should be readjusted to meet them.

[0051] Step S8. Design of the substructure below the seismic isolation layer; the embedded stiffness ratio of the structure below the seismic isolation layer shall be checked and the normal section shall be designed according to the moderate or major earthquake, and the oblique section shall be designed according to the rare earthquake; specifically, according to Article 12.2 of the "Code for Seismic Design of Buildings", the embedded stiffness ratio of the structure below the seismic isolation layer shall be checked. If it is not satisfied, the arrangement of the first-floor shear wall 63 of the large base shall be adjusted to meet it; the normal section of the components shall be designed according to the moderate or major earthquake, and the oblique section shall be designed according to the rare earthquake.

[0052] Step S9. Overall structural calculation; perform overall internal force and displacement calculation and analysis on the seismic isolation model under frequent earthquakes; perform elastoplastic time history verification analysis on the seismic isolation model under major earthquakes.

[0053] Therefore, through this embodiment, all the original shear walls on the second floor can be eliminated; simultaneously, the mutual influence between the upper residential building 1 and the second floor 5 of the large base within the non-isolation layer range is reduced, effectively controlling the cross-section of the vertical columns 52 of the second floor outside the range; the second floor structure within the projection range of the upper structure has one less top floor slab 71; the mass of the second floor is significantly reduced, further reducing the seismic response, improving the overall stress condition, effectively controlling the cross-section of the vertical columns and shear walls 63 of the first floor, and the thickness of the shear walls of the first floor can be reduced from 850mm to 600mm, greatly saving costs; on the other hand, there is only the first floor 6 of the large base below the isolation layer, effectively reducing the possibility of weak and soft layers; at the same time, the height of the first floor shear walls 11 of the upper structure is increased, and the arrangement of the first floor shear walls 11 of the upper structure is more flexible. After comparison, the optimized solution of this embodiment saves about 18% of the cost compared with the original solution.

[0054] The above description is a preferred embodiment of this application and the technical principles used therein. It is not intended to limit the scope of protection of this application. For those skilled in the art, any obvious changes such as equivalent transformations or simple substitutions based on the technical solutions of this application, without departing from the spirit and scope of the invention, shall fall within the scope of protection of this invention.

[0055] Therefore, the method for designing a seismic isolation structure for the subway depot roof of the present invention may include the following steps:

[0056] Step S1. Determine the location of the seismic isolation layer; based on the building's function and the dimensions and arrangement of the vertical components of the superstructure and the substructure, determine a reasonable location for the seismic isolation layer.

[0057] Step S2. Define the seismic reduction target and fortification standard; based on the project conditions and existing experience, determine the seismic reduction target after adopting seismic isolation design, determine the target horizontal seismic reduction coefficient, and define the fortification standard of the structure.

[0058] Step S3. Superstructure layout: Based on the determined seismic reduction target, combined with the building layout and the location of the seismic isolation layer, calculate the superstructure according to the hinged model of the upper support column bottom (non-seismic isolation model, without seismic isolation bearings and its lower structure). By adjusting the model, make the superstructure meet the corresponding seismic reduction target and fortification standard, and determine the number and location of the horizontal seismic isolation structure nodes that need to be arranged.

[0059] Step S4. Arrange the isolation layer structure according to the support reaction force calculated above; calculate the static working condition of the non-isolation model, and determine the vertical reaction force at the node position of the isolation layer 3 to be arranged under static action; determine the parameters of the isolation support according to the vertical reaction force.

[0060] Step S5. Calculate the damping coefficient; Calculate and analyze the superstructure with isolation layer (isolation model), and calculate the isolation and non-isolation models according to the design earthquake. Use time history analysis to calculate the horizontal damping coefficient. If the horizontal damping coefficient does not meet the requirements, adjust the isolation bearings to meet them. If it still does not meet the requirements, readjust the stiffness of the superstructure or substructure and redesign the isolation structure.

[0061] Step S6. Design of the superstructure of the isolation layer; determine the maximum value of the seismic influence coefficient after damping based on the damping coefficient, establish a non-isolated model, and verify the bearing capacity of the superstructure of the isolation layer under frequent earthquakes, considering the horizontal damping coefficient. If it does not meet the requirements, readjust the superstructure and redesign the isolation structure.

[0062] Step S7. Design of the seismic isolation layer structure; verify the maximum compressive stress of the bearings under representative gravity loads; perform wind resistance calculations, horizontal force calculations, eccentricity calculations, and yield-to-weight ratio calculations; verify the tensile stress, compressive stress, and maximum displacement of the bearings under rare earthquakes; for the seismic isolation layer piers, columns, and connected components, perform bearing capacity calculations using the vertical force, horizontal force, and moment at the bottom of the seismic isolation bearings under rare earthquakes. If the requirements are not met, readjust the seismic isolation layer structure to meet them.

[0063] Step S8. Design of the substructure below the seismic isolation layer; the embedded stiffness ratio of the structure below the seismic isolation layer is checked and the normal section is designed according to the moderate or major earthquake, and the oblique section is designed according to the rare earthquake.

[0064] Step S9. Overall structural calculation; perform overall internal force and displacement calculation and analysis on the seismic isolation model under frequent earthquakes; perform elastoplastic time history verification analysis on the seismic isolation model under major earthquakes.

[0065] By adopting the above technical solution, the use of seismic isolation structures is used to reduce the seismic response of the subway depot superstructure. At the same time, the stress condition of the substructure is also improved due to the reduction in the seismic response of the superstructure. The cross-section of the substructure frame columns can be effectively controlled, and the seismic performance of the entire structural system is significantly improved, ensuring the safety and reliability of the structure. In addition, when determining a reasonable location for the seismic isolation layer, this application can move the seismic isolation layer down to the top of the first floor by cooperating with other disciplines. By moving the seismic isolation layer to the top of the first floor and separating the superstructure from the second-floor structure of the large base outside its projection range, the required embedment stiffness ratio can be met by simply arranging shear walls on the first floor of the large base, and the original shear walls on the second floor can be completely eliminated. At the same time, the mutual influence between the superstructure and the second-floor structure outside the projection range is reduced, and the cross-section of the frame columns on the second floor outside the projection range is effectively controlled. The second-floor structure within the projection range of the superstructure has one less top floor slab. The mass of the second floor is significantly reduced, further reducing the seismic response, improving the overall stress condition, effectively controlling the cross-section of the frame columns on the first floor, and greatly saving costs. On the other hand, with only the first floor of the large base below the seismic isolation layer, the possibility of weak and soft floors is effectively reduced. At the same time, the height of the first floor of the superstructure is increased, and the arrangement of the first floor of the superstructure is more flexible.

[0066] Optionally, in steps S1-S3, the location of the seismic isolation layer and the damping target are determined, and a non-isolated model is established through the target damping coefficient. After the superstructure is reasonably arranged, the location of the seismic isolation bearings is determined in conjunction with the column grid location of the substructure, according to the principle of "avoiding bearings where there are no walls, and placing more bearings where there are many walls; keeping the spacing between multiple rows of bearings as uniform as possible; and not hindering the large deformation of the seismic isolation layer under rare earthquakes". The range of the seismic isolation layer can be appropriately expanded according to the column grid of the first floor.

[0067] By adopting the above technical solutions, the positions of the upper supports (bearings) are arranged according to the reasonable superstructure form, so that the position of the seismic isolation bearings and the stress are as uniform as possible, which facilitates the adjustment of the seismic isolation model and the selection of seismic isolation bearings. By appropriately enlarging the range of the seismic isolation layer through the transformation structure arrangement, the range of the seismic isolation layer corresponds to the column grid of the first floor, which can reduce the bearing transformation. By "adding boots" to the superstructure, its overturning resistance is enhanced.

[0068] Optionally, in steps S4 and S5, the parameters of the seismic isolation bearings are adjusted to meet the requirements, and the bearings are arranged according to the principle of "lead core seismic isolation bearings are arranged around the perimeter and natural rubber bearings are arranged in the middle" as much as possible.

[0069] By adopting the above technical solutions, the impact of large edge deformation caused by structural torsion is effectively mitigated, making it easier to resist the tensile forces that may occur at the edge supports. The combined use of lead core supports and natural rubber supports can improve the efficiency of seismic isolation and ensure economy.

[0070] According to the design requirements, if the calculated horizontal damping coefficient is less than the target horizontal damping coefficient, the design, verification and optimization of the upper structure of the isolation layer, the isolation layer and the lower structure of the isolation layer of the seismic isolation model will be carried out, and the performance target of the piers will be appropriately increased to enhance the safety of the isolation layer.

[0071] By adopting the above technical solutions, the seismic isolation structure is calculated as a whole. The maximum deformation and stress of the bearings, as well as the deformation and damage of the superstructure, are obtained through elastoplastic time history analysis under rare earthquakes. The bearing selection and arrangement are adjusted to ensure that the structure meets the determined seismic reduction target and relevant standard and specification requirements, thereby further improving the stability of the designed building. Through the optimized design of the seismic isolation structure, the seismic isolation structure can further meet the corresponding requirements, improve the efficiency of seismic isolation, and ensure economy.

[0072] It is obvious that the above description and account are merely illustrative and not intended to limit the disclosure, application, or use of this invention. Although embodiments have been described and illustrated in the accompanying drawings, the invention is not limited to the specific examples exemplified by the drawings and described in the embodiments as currently considered the best mode for carrying out the teachings of the invention. The scope of the invention will include any embodiments falling within the foregoing description and the appended claims.

Claims

1. A method for designing a seismic isolation structure for the development of a subway depot roof, characterized in that... It includes the following steps: Step S1. Determine the location of the seismic isolation layer; based on the building's function and the dimensions and arrangement of the vertical components of the superstructure and the substructure, determine a reasonable location for the seismic isolation layer; Based on the building's function and the dimensions and layout of the upper residential buildings and the lower large base's vertical support structure, the location of the seismic isolation layer is determined to be the top of the first floor of the large base. The second-floor slab and the upper transfer structure are directly installed at the lower end of the first-floor shear wall of the upper structure, and the upper transfer structure is directly connected to the seismic isolation layer. The seismic isolation layer consists of upper supports, seismic isolation bearings, and lower supports. The lower transfer structure is located at the top of the first floor of the large base. The first-floor top beam is supported by the first-floor vertical columns and the first-floor shear wall. Step S2. Define the vibration reduction target and fortification standard; based on the project conditions and existing experience, determine the vibration reduction target after adopting seismic isolation design, determine the target horizontal vibration reduction coefficient, and define the fortification standard of the structure; Step S3. Superstructure layout: Based on the determined seismic reduction target, combined with the building layout and the location of the seismic isolation layer, the superstructure is determined according to the hinged model at the bottom of the upper support pier in the seismic isolation layer. By adjusting the model, the superstructure meets the corresponding seismic reduction target and fortification standard, and the number and location of the horizontal seismic isolation structure nodes that need to be arranged are determined. Step S4. Arrange the isolation layer structure according to the support reaction force; calculate the static working condition of the non-isolation model, and determine the vertical reaction force at the node position of the horizontal isolation structure to be arranged under static action; determine the parameters of the isolation support according to the vertical reaction force. Step S5. Calculate the horizontal damping coefficient; analyze the superstructure with isolation layer and the chassis, and calculate the isolation and non-isolation models according to the design earthquake to determine the horizontal damping coefficient. If the horizontal damping coefficient does not meet the requirements, adjust the isolation bearings to meet them. In this process, Yingjianke cancels the lower hinge of the non-isolated model and establishes an isolation layer and a large chassis model of the relevant range, defining the model as an isolation model. Wave selection was performed by taking the first three periods of the non-isolated model, the first three periods of the superstructure of the isolated model, and the first three periods of the large chassis with the largest vibration mass participation coefficient. Since the non-isolated model does not have a large chassis, the large chassis period is taken to be the same as that of the isolated model. According to the method provided in 5.1.2 of the "Code for Seismic Design of Buildings" and its explanatory notes, 5 natural waves and 2 artificial waves were selected for time history analysis. The average value of the results was taken. The shear force and overturning moment of each story above the isolation bearing of the non-isolated model and the isolated model were compared. The ratio of the two values ​​is the horizontal damping coefficient. Step S6. Design of the superstructure of the isolation layer; Determine the maximum value of the seismic influence coefficient after damping based on the damping coefficient, establish a non-isolated model, and verify the bearing capacity of the superstructure of the isolation layer under frequent earthquakes, taking into account the horizontal damping coefficient. Step S7. Design of the seismic isolation layer structure; verify the maximum compressive stress of the bearing under the representative value of gravity load, and verify the tensile stress, compressive stress and maximum displacement of the bearing under rare earthquake action; for the seismic isolation layer piers, columns and connected components, use the vertical force, horizontal force and moment at the bottom of the seismic isolation bearing under rare earthquake action to verify the bearing capacity. Step S8. Design of the substructure below the seismic isolation layer: The embedded stiffness ratio of the structure below the seismic isolation layer is checked and the normal section is designed according to the moderate or major earthquake, and the oblique section is designed according to the rare earthquake. Step S9. Overall structural calculation; perform overall internal force and displacement calculation and analysis on the seismic isolation model under frequent earthquakes; perform elastoplastic time history verification analysis on the seismic isolation model under major earthquakes.

2. The method for designing a seismic isolation structure for the development of a subway depot roof as described in claim 1, characterized in that: In step S2, based on Article 12.2.5 of the "Code for Seismic Design of Buildings" and its explanatory notes, and combined with the project conditions and existing experience, the target horizontal damping coefficient is controlled between 0.30 and 0.40 in the seismic isolation design, so as to achieve the design goal of reducing the seismic fortification intensity of the upper residential buildings by one degree.

3. The method for designing a seismic isolation structure for the development of a subway depot roof as described in claim 1, characterized in that: In step S3, the superstructure is rationally arranged by combining the building layout, the location of the seismic isolation layer, and the column grid location of the substructure. When arranging the upper supports of the seismic isolation layer, no upper supports are arranged in the locations without walls, and upper supports of the seismic isolation layer are arranged at intervals in the locations with walls. The spacing between each row of upper supports is uniform. After determining the location of the upper supports of the seismic isolation layer, the bottom of the upper supports of the seismic isolation layer is hinged, and the superstructure is made to meet the corresponding vibration reduction target and fortification standard through modeling, and the specific location of the seismic isolation layer is determined.

4. The method for designing a seismic isolation structure for the development of a subway depot roof as described in claim 1, characterized in that: In step S4, the static working condition calculation of the non-isolated model is performed by Yingjianke to calculate the bottom vertical reaction force of the upper support of the isolation layer to be arranged; the minimum area of ​​the isolation bearing is determined by dividing the vertical reaction force by the vertical pressure limit specified in 12.2.3 of the "Code for Seismic Design of Buildings".

5. The method for designing a seismic isolation structure for the development of a subway depot roof as described in claim 4, characterized in that: Seismic isolation bearings with higher stiffness and tensile strength are arranged around the perimeter of the structure, using lead-core seismic isolation bearings. Seismic isolation bearings with lower stiffness are arranged in the center, using natural rubber bearings.

6. The method for designing a seismic isolation structure for the development of a subway depot roof as described in claim 1, characterized in that: A horizontal damping coefficient between 0.3 and 0.4 is acceptable. If the horizontal damping coefficient is less than 0.30, it indicates that there are too few lead-core seismic isolation bearings, the yield strength ratio is too small, and the horizontal seismic attenuation is too great. In order to eliminate the need to calculate vertical seismic events for the upper frame-supported residential buildings, it is necessary to increase the number of lead-core seismic isolation bearings. If the horizontal damping coefficient is greater than 0.40, it indicates that there are too many lead-core seismic isolation bearings, the yield strength ratio is too large, and the damping effect is poor. It is necessary to reduce the number of lead-core seismic isolation bearings and adjust the arrangement of the seismic isolation bearings to meet the requirements.

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