JP2017166518A - Slide support device and base isolation structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the peak of acceleration generating in an upper structure of a base isolation structure.SOLUTION: A slide support device 7 includes a slide part 8 attached to a lower structure 3, a support part 9 which is mounted on the slide part 8, and moves relative to the slide part 8 in the horizontal direction when horizontal force generating in the upper structure 2 goes above friction force between the slide part 8 and the support part 9, and a hollow elastic rubber 11 disposed between the support part 9 and the upper structure 2.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a sliding bearing device and a seismic isolation structure having the sliding bearing device.

  Seismic isolation technology reduces building shaking during an earthquake and provides a safe and secure living space. A sliding bearing is used as a component of the seismic isolation structure.

  As a sliding bearing, for example, an apparatus called a so-called elastic sliding bearing in which a laminated rubber and a sliding bearing are combined as disclosed in Patent Document 1 is known. This sliding bearing device has a sliding bearing mechanism disposed between the lower structure and the upper structure. The sliding support mechanism has an elastic-plastic body in which a ring-shaped laminated rubber plate and a lead disc arranged in a hole of the laminated rubber plate are combined. And this elasto-plastic body is integrated with the fluororesin layer via the steel plate and slides with respect to the resin coating layer provided in the lower structure. According to this sliding support mechanism, the relative displacement of the upper structure in the horizontal direction with respect to the lower structure can be allowed, and the load of the upper structure can be transmitted to and supported by the lower structure. That is, the seismic isolation effect due to the deformation of the laminated rubber is exhibited in a medium or small scale earthquake. Furthermore, in a large-scale earthquake, the seismic isolation effect due to the slip between the fluororesin layer and the resin coating layer is exhibited.

JP 2009-2461 A

  When a slip occurs in the sliding support device, the sliding support device reciprocates in accordance with the input acceleration direction of the earthquake. In this reciprocating movement of the sliding support device, an acceleration peak may occur in the seismic isolation structure when the moving direction of the sliding support device is reversed. In recent years, the performance of seismic isolation structures has improved, and the magnitude of acceleration generated in the seismic isolation structure during an earthquake tends to decrease. Therefore, there is a case where the influence of the acceleration accompanying the reversal of the moving direction cannot be ignored with respect to the acceleration generated in the seismic isolation structure during the earthquake.

  Therefore, an object of the present invention is to provide a sliding bearing device that can reduce the peak of acceleration generated in a base-isolated structure during an earthquake.

  One aspect of the present invention is a sliding support device applied to a seismic isolation structure provided between an upper structure and a lower structure, and is placed on the lower structure, and a horizontal force generated in the upper structure is applied to the lower structure. A bearing part that moves in a horizontal direction with respect to the lower structure, a lower surface that is disposed between the bearing part and the upper structure and is fixed to the main surface of the bearing part, and an upper part. And an elastic part that generates a horizontal restoring force corresponding to the relative displacement in the horizontal direction of the superstructure with respect to the support part, the lower surface of the elastic part and the elastic part of the elastic part A sliding bearing device with an area of the main surface smaller than the area of the main surface of the bearing.

  In this sliding bearing device, when the horizontal force acting on the upper structure exceeds the frictional force between the bearing section and the lower structure, the bearing section slides with respect to the lower structure. Next, the horizontal force of the upper structure is reduced while the slip is generated, and when the friction force is lower, the sliding of the support portion with respect to the lower structure is stopped. On the other hand, the upper structure tries to continue to move due to the inertial force, but this movement is hindered by the restoring force of the elastic portion, and the moving direction of the upper structure is reversed in the direction opposite to the original moving direction. A peak of acceleration occurs just before the moving direction is reversed and immediately before it starts to slide in the opposite direction. In this sliding support device, since the elastic coefficient of the elastic portion is smaller than usual, the peak of acceleration caused by reversal is reduced. Therefore, according to the sliding support device, it is possible to reduce the peak of acceleration generated in the seismic isolation structure during an earthquake.

  The area of the lower surface of the elastic portion and the main surface of the elastic portion may be 20% or more of the area of the main surface of the support portion. According to this configuration, it is possible to more suitably reduce the acceleration peak that occurs when the moving direction of the superstructure is reversed.

  The elastic portion may include a restoring force generating portion that has a ring shape and a restoring force non-generating portion surrounded by the restoring force generating portion. According to this structure, it is possible to suppress the action of the moment generated when the support portion slides, and to reduce the uneven distribution of the surface pressure between the support portion and the lower structure.

  The elastic portion may further include a support portion that is disposed in the restoring force non-generating portion and fixed to the support portion and the upper structure. According to this structure, the axial force along the vertical direction of the sliding support device can be suitably supported by the support portion.

  The elastic part may further have a damping part formed in the restoring force non-generating part. According to this structure, it is possible to easily provide the damping element connected in parallel to the elastic portion that is the spring element.

  The elastic portion has at least four plate-like sheets, and the plate-like sheets may be arranged at equal intervals around the central axis in the vertical direction of the support portion. According to this structure, it is possible to suppress the action of the moment generated when the support portion slides, and to reduce the uneven distribution of the surface pressure between the support portion and the lower structure.

  Another embodiment of the present invention is a seismic isolation structure provided between an upper structure and a lower structure, and includes a sliding support device provided between the upper structure and the lower structure. When the horizontal force generated on the structure and generated in the upper structure exceeds the frictional force between the lower structure and the bearing, the bearing moves in the horizontal direction with respect to the lower structure. And having a lower surface fixed to the main surface of the support portion and a main surface fixed to the upper structure, and having a horizontal restoring force corresponding to the relative displacement in the horizontal direction of the upper structure with respect to the support portion. And an area of the lower surface of the elastic portion and the main surface of the elastic portion is smaller than the area of the main surface of the support portion. According to this seismic isolation structure, since the above-described sliding support device is provided, it is possible to more suitably reduce the acceleration peak that occurs when the moving direction of the upper structure is reversed. Therefore, the performance of the seismic isolation structure can be improved.

  ADVANTAGE OF THE INVENTION According to this invention, the peak of the acceleration which generate | occur | produces in a base isolation structure at the time of an earthquake can be reduced.

FIG. 1 is a diagram illustrating a building to which a seismic isolation structure including a sliding bearing device according to the present embodiment is applied. FIG. 2 is a diagram illustrating the sliding support device according to the present embodiment. FIG. 3 is a diagram illustrating the operation of the sliding support device. FIG. 4 is a diagram illustrating the operation of the sliding support device. FIG. 5 is a diagram illustrating the operation of the sliding support device according to the comparative example. FIG. 6 is a graph illustrating an example of a method for setting the sliding support device according to the embodiment. FIG. 7 is a graph showing the effect of the sliding bearing device according to the example. FIG. 8 is a graph showing the effect of the sliding support device according to the example. FIG. 9 is a view showing a sliding support device according to a modification.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 1, a building 100 has a base isolation structure 1, an upper structure 2, and a lower structure 3. The seismic isolation structure 1 is disposed between the upper structure 2 and the lower structure 3. The seismic isolation structure 1 reduces the amplitude and acceleration of seismic waves transmitted from the lower structure 3 to the upper structure 2. For example, the seismic isolation structure 1 is designed so that the acceleration response value on the seismic isolation structure 1 at the time of a large earthquake is about 50 Gal. The seismic isolation structure 1 includes an earthquake elastic spring 4 (elastic device), an oil damper 6, and a sliding support device 7.

The earthquake elastic spring 4 connected to the upper structure 2 and the lower structure 3 sets the period (T2) of the seismic isolation structure 1. The period (T2 = 2π√ (m / k2)) is determined by the elastic coefficient (k2) of the earthquake elastic spring 4 and the mass (m) of the superstructure 2. This earthquake elastic spring 4 has an isolation structure. 1 cycle is set to the long period of. for example, the elastic modulus of the seismic elastic spring 4 (k2) is 15-story height 60 m, is about 6t / cm at each floor of floor area 1000 m ² building The oil damper 6 reduces the acceleration in the seismic isolation structure 1.

  The sliding bearing device 7 connected to the upper structure 2 and the lower structure 3 so as to be in parallel to the earthquake elastic spring 4 has the following functions. As a first function, the sliding support device 7 functions as an elastic element when a relatively small vibration is input to the lower structure 3. Specifically, when the upper structure 2 moves in the horizontal direction relative to the lower structure 3, the sliding support device 7 generates a restoring force opposite to the moving direction. In this case, the sliding support device 7 is handled as an elastic element connected in parallel to the earthquake elastic spring 4. As a second function, the sliding support device 7 functions as a sliding element when a relatively large vibration is input to the lower structure. Specifically, the sliding support device 7 is a case where the upper structure 2 moves in the horizontal direction relative to the lower structure 3 and is determined by the acceleration acting on the upper structure 2 and the mass of the upper structure 2. When the horizontal excitation force exceeds the frictional force of the sliding support device 7, it slides in the horizontal direction.

  As shown in FIG. 2, the sliding support device 7 includes a sliding portion 8, a support portion 9, and a hollow elastic rubber 11.

  The sliding portion 8 realizes the sliding function of the sliding support device 7 in cooperation with the support portion 9. The sliding portion 8 is a disk-like member provided on the main surface 3 a of the lower structure 3. The members constituting the sliding portion 8 are formed of a material having a small friction coefficient. For example, the sliding portion 8 can use a fluororesin. For example, the friction coefficient between the sliding portion 8 and the support portion 9 is about 0.5% to 1.0%.

  The support part 9 cooperates with the sliding part 8 to realize the sliding function of the sliding support device 7 and supports the weight of the upper structure 2 along the vertical direction. The support portion 9 is a metal columnar member that forms the base of the sliding support device 7. The lower surface 9 b of the support portion 9 that faces the sliding portion 8 has a smaller coefficient of friction than the sliding portion 8. For example, the lower surface 9b of the support portion 9 may be a resin plate 12 provided on the lower surface of a metal main body.

  The hollow elastic rubber 11 generates a horizontal restoring force. This restoring force corresponds to the amount of relative displacement in the horizontal direction of the upper structure 2 with respect to the support portion 9. The hollow elastic rubber 11 is disposed between the main surface 9 a of the support portion 9 and the lower surface 2 a of the upper structure 2. The hollow elastic rubber 11 has a restoring force generating part 13 and a restoring force non-generating part 14. The restoring force generator 13 is a member having a ring shape. The height of the restoring force generating portion 13 can be made smaller than the height of the support portion 9 and can be made compact. That is, the hollow elastic rubber 11 is not a so-called laminated rubber. Further, since the restoring force generator 13 only follows the amount of deformation when the moving direction of the upper structure 2 is reversed, there is no need to allow large deformation and there is no need to use laminated rubber.

  The restoring force generator 13 has a lower surface 13 b fixed to the main surface 9 a of the support portion 9 and a main surface 13 a fixed to the upper structure 2. Therefore, when the upper structure 2 moves in the horizontal direction with respect to the lower structure 3, the main surface 13a moves in the horizontal direction with respect to the lower surface 13b of the restoring force generating portion 13, and the restoring force generating portion 13 is sheared in the horizontal direction. Deformation occurs. This shear deformation causes a restoring force. A through-hole is formed in the restoring force generating part 13, and this through-hole corresponds to the restoring force non-generating part 14. That is, the restoring force non-generating part 14 is a space formed between the main surface 9 a of the support part 9 and the upper structure 2. Therefore, the restoring force non-generating unit 14 does not generate a restoring force. In addition, you may form the attenuation | damping part which enclosed the viscous material and gave the damping effect to the restoring force non-generation part 14 as needed.

  The outer diameter of the restoring force generating portion 13 is substantially the same as the outer diameter of the support portion 9. The inner diameter of the restoring force non-generating portion 14 is constant. Then, the area of the main surface 13a and the lower surface 13b of the restoring force generating part 13 is smaller than the area of the main surface 9a of the support part 9 by the amount of the restoring force non-generating part 14. Specifically, the area of the main surface 13a and the lower surface 13b of the restoring force generating portion 13 is less than the area of the main surface 9a of the support portion 9, and is 20% or more of the area of the main surface 9a in the support portion 9. is there. Desirably, the area of the main surface 13a and the lower surface 13b of the restoring force generating part 13 is 70% or less and 20% or more of the area of the main surface 9a in the support part 9. More preferably, the area of the main surface 13a and the lower surface 13b of the restoring force generating portion 13 is 40% or less and 20% or more of the area of the main surface 9a in the support portion 9.

  Next, the operation and effect of the sliding bearing device 7 will be described. As shown in part (a) of FIG. 3, when no earthquake vibration is applied, no relative movement in the horizontal direction occurs between the upper structure 2 and the lower structure 3. Therefore, the bearing portion 9 of the sliding bearing device 7 does not slide with respect to the sliding portion 8, and the hollow elastic rubber 11 does not undergo shear deformation. In this state, the weight of the upper structure 2 is supported by the support portion 9 in the slide support device 7.

  As shown in part (a) of FIG. 4, when a vibration due to a relatively large earthquake is applied, the horizontal force F <b> 1 acting on the upper structure 2 generates a frictional force F <b> 2 between the support part 9 and the sliding part 8. The support part 9 slides with respect to the sliding part 8 by exceeding. Next, while the slip is generated, the horizontal force F1 of the upper structure 2 decreases, and when the friction force F2 is reduced, the sliding of the support portion 9 with respect to the sliding portion 8 stops. On the other hand, as shown in part (b) of FIG. 4, the upper structure 2 tries to continue to move due to the inertial force F3, but this movement is hindered by the restoring force F4 of the hollow elastic rubber 11. As shown in part (c) of FIG. 4, the moving direction of the upper structure 2 is reversed in the direction opposite to the initial moving direction by the restoring force F4. In a transient state after the moving direction is reversed, an acceleration peak occurs.

  Here, in the seismic isolation structure provided with the general sliding bearing device according to the comparative example, the sliding bearing and the laminated rubber are used together in a planar manner. Then, it is assumed that the influence of the elastic rubber installed in series with the sliding bearing is mitigated, and the acceleration response value on the seismic isolation structure at the time of a large earthquake is about 200 Gal. When the acceleration response value on the seismic isolation structure is about 200 Gal, the acceleration peak when the moving direction is reversed is not easily revealed. However, in reality, if the elastic rubber included in the sliding bearing is hard (elastic modulus is large), the vibration frequency of the structure suddenly increased in the time zone when no sliding occurred, and the moving direction was reversed. The acceleration peak tends to increase.

  On the other hand, in the base isolation structure 1 according to the present embodiment, the acceleration response value on the base isolation structure 1 is set to be about 50 Gal. If it does so, the acceleration peak when a moving direction will reverse will be easy to be revealed. In the sliding support device 7, the first elastic coefficient (k1) of the hollow elastic rubber 11 is suppressed to about 15 times the second elastic coefficient (k2) of the earthquake elastic spring 4 (usually Therefore, the peak of acceleration caused by the reversal of the moving direction is reduced.

  Here, the sliding support device 201 according to the comparative example shown in FIG. 5 includes a laminated rubber portion 202 and a support portion 203 in which a plurality of elastic rubbers are laminated. When the thickness of the laminated rubber portion 202 is increased, when the superstructure 2 vibrates, a swinging motion (see arrow N1) with the horizontal direction as the rotation axis is likely to occur, and thus rotational stability tends to be reduced. According to this swaying motion, the surface pressure N2 at which the support portion 9 presses the sliding portion 8 is biased. Since the high-performance seismic isolation structure tends to increase the number of repeated sliding operations, it is desirable to suppress the uneven distribution of the surface pressure that causes the frictional state between the sliding portion 8 and the bearing portion 9 to be biased.

  In the sliding support device 7 according to the present embodiment, the hollow elastic rubber 11 is a single layer and is formed of a thin rubber sheet, and thus has a small thickness. Accordingly, it is possible to suppress a decrease in rotational stability with the horizontal direction as the rotation axis, and to suppress uneven distribution of the surface pressure distribution between the support portion 9 and the sliding portion 8.

<Example 1>
The sliding support device 7 reduces the elastic coefficient by making the area of the hollow elastic rubber 11 smaller than the area of the support portion 9. Therefore, an example of a method for setting the area of the hollow elastic rubber 11 will be described. FIG. 6 shows the relationship with the response acceleration on the base isolation structure 1 (graph G1a), the degree of acceleration peak reduction (graph G1b), the deformation amount on the base isolation structure 1 (graph G1c), and the area ratio (graph G1d). Indicates. Specifically, the horizontal axis is the area ratio. The area ratio (A) is expressed by equation (1). Further, the reduction rate (F) is expressed by equation (2).
A = S / SA (1)
A: Area ratio S: Area of main surface (or lower surface) of restoring force generating portion SA: Area of main surface of supporting portion F = (E1-E2) / E1 (2)
F: Reduction rate E1: Acceleration when the area of the main surface (or lower surface) of the restoring force generator 13 is equal to the area of the main surface of the bearing 9 E2: Area of the main surface (or lower surface) of the restoring force generator 13 Acceleration when is a predetermined value

  Referring to the response acceleration (graph G1a) and the area ratio (graph G1d), it was found that the response acceleration decreases as the area ratio decreases (that is, the elastic modulus decreases). Further, referring to the response reduction rate (graph G1b) and the area ratio (graph G1d), it was found that when the area ratio was 20% or less, the degree of reduction in the reduction rate was moderate. Further, referring to the horizontal deformation amount (graph G1c) and the area ratio (graph G1d) in the seismic isolation structure 1, it was found that the horizontal deformation amount is substantially unchanged.

On the other hand, the proof stress of the rubber used for the hollow elastic rubber 11 has been verified up to 150 N / mm ² . Under the condition that the area of the main surface 13a (or the lower surface 13b) of the restoring force generating portion 13 is equal to the area of the main surface 9a of the support portion 9 and the surface pressure is 20 N / mm ² , It shows that the yield strength is not reached even when the area of the elastic rubber 11 is reduced to about 14%. Accordingly, by setting the area of the main surface 13a (or the lower surface 13b) of the restoring force generating portion 13 (that is, the rubber horizontal rigidity) to 20%, the function as the sliding support device 7 is exhibited by the normal seismic isolation rubber strength. However, it was found that an acceleration peak reduction effect can be obtained.

<Example 2>
In Example 2, the relationship between the elastic coefficient of the hollow elastic rubber 11 and the response acceleration on the seismic isolation structure 1 was confirmed by calculation. The elastic modulus of the hollow elastic rubber 11 is a reference example in which the elastic modulus when the area of the main surface 13a (or the lower surface 13b) of the restoring force generating portion 13 is equal to the area of the main surface 9a of the support portion 9 is 100%. In this reference example, five conditions with elastic modulus of 75%, 50%, 30%, 20% and 10% were set. Parts (a) to (c) in FIG. 7 and parts (a) to (c) in FIG. 8 are diagrams showing calculation results. In each figure, the horizontal axis indicates time (seconds), and the vertical axis indicates acceleration (Gal). In each figure, graph G2 shows the time history of frictional force (ton), graph G3 shows response acceleration (Gal) on seismic isolation structure 1, and graph G4 shows top response acceleration (Gal). .

  Part (a) of FIG. 7 is a calculation result when the elastic modulus is 100%, and part (b) of FIG. 7 is a calculation result when the elastic coefficient is 75%. The part c) is a calculation result when the elastic modulus is 50%. Part (a) of FIG. 8 shows the calculation result when the elastic modulus is 30%, and part (b) of FIG. 8 shows the calculation result when the elastic coefficient is 20%. The part c) is a calculation result when the elastic modulus is 10%.

  Note the frictional force (graph G2). In the graph G2, the period in which the frictional force is constant is a period in which slip occurs in the slide support device 7. On the other hand, the period in which the frictional force is changed in the graph G2 is a period in which the reversal of the moving direction of the upper structure 2 occurs in the sliding support device 7. For example, paying attention to the period G2a in part (a) of FIG. 7, it can be seen that a peak occurs in the response acceleration on the seismic isolation structure 1 (graph G3) due to the reversal of the moving direction of the upper structure 2.

Table 1 shows the relationship between the elastic coefficient, the corresponding peak response acceleration on the base isolation structure 1, and the displacement of the base isolation structure 1. Referring to Table 1, for example, when the elastic coefficient is 20%, the peak value of the response acceleration on the seismic isolation structure 1 can be reduced to about 60% when the elastic coefficient is 100%.

  The present invention has been described in detail based on the embodiments. However, the present invention is not limited to the above embodiment. The present invention can be variously modified without departing from the gist thereof.

<Modification 1>
As shown in part (a) of FIG. 9, the sliding support device 7 </ b> A may include an axial force supporting elastic rubber 16 (supporting part) disposed in the restoring force non-generating part 14. The axial force supporting elastic rubber 16 has a cylindrical shape, and is arranged so that the center axis A1 thereof coincides with the center axis A2 of the support portion 9. According to the sliding bearing device 7A including the axial force supporting elastic rubber 16, a bending moment is borne by the hollow elastic rubber 11, and an axial force is borne by the elastic rubber 16 for supporting the axial force. Therefore, even when a large axial force is applied, the axial force is borne by the elastic rubber 16 for supporting the axial force, so that the effect of reducing the acceleration peak in the hollow elastic rubber 11 can be suitably achieved.

<Modification 2>
As shown in FIG. 9B, the sliding support device 7B may be an elastic portion 13A having four circular elastic rubbers 17 (plate-like sheets). The circular elastic rubber 17 is disposed at the four corners on the main surface 9a of the support portion 9. In other words, the circular elastic rubbers 17 are arranged at equal intervals around the central axis A <b> 2 in the vertical direction of the support portion 9. The circular elastic rubber 17 can be easily manufactured by a single punching process on a rubber sheet. Further, the shape factor (S1 = (D−d) / 4t: D: outer diameter, d: inner diameter, t: thickness) that affects the stability of horizontal deformation in the circular elastic rubber 17 can be increased. Furthermore, according to the elastic portion 13A having the circular elastic rubber 17, the stability against a high axial force can be improved.

DESCRIPTION OF SYMBOLS 1 ... Seismic isolation structure, 2 ... Superstructure, 3 ... Lower structure, 4 ... Elastic spring (elastic device) for earthquakes, 6 ... Oil damper, 7 ... Sliding bearing device, 8 ... Sliding part, 9 ... Bearing part, 11 ... Hollow elastic rubber (elastic part), 13 ... restoring force generating part, 14 ... restoring force non-generating part.

Claims (7)

A sliding support device applied to a seismic isolation structure provided between an upper structure and a lower structure,
A support portion mounted on the lower structure and moving in a horizontal direction with respect to the lower structure when a horizontal force generated in the upper structure exceeds a frictional force with the lower structure;
The lower portion is disposed between the support portion and the upper structure, and has a lower surface fixed to the main surface of the support portion and a main surface fixed to the upper structure, and the upper structure is horizontal with respect to the support portion. An elastic portion that generates a restoring force in the horizontal direction corresponding to the amount of relative displacement in the direction,
The sliding bearing device, wherein an area of a lower surface of the elastic portion and a main surface of the elastic portion is smaller than an area of the main surface of the supporting portion.   The sliding bearing device according to claim 1, wherein an area of a lower surface of the elastic portion and a main surface of the elastic portion is 20% or more of an area of the main surface of the supporting portion.   The sliding support device according to claim 1 or 2, wherein the elastic portion includes a ring-shaped restoring force generating portion and a restoring force non-generating portion surrounded by the restoring force generating portion.   The sliding support device according to claim 3, wherein the elastic portion further includes a support portion that is disposed in the restoring force non-generating portion and is fixed to the support portion and the upper structure.   The sliding support device according to claim 3 or 4, wherein the elastic portion further includes a damping portion formed in the restoring force non-generating portion. The elastic part has at least four plate-like sheets,
The sliding support device according to claim 1 or 2, wherein the plate-like sheets are arranged at equal intervals around a central axis line in a vertical direction of the support portion. A seismic isolation structure provided between the upper structure and the lower structure,
A sliding bearing device provided between the upper structure and the lower structure;
The sliding support device is
A support portion mounted on the lower structure and moving in a horizontal direction with respect to the lower structure when a horizontal force generated in the upper structure exceeds a frictional force with the lower structure;
The lower portion is disposed between the support portion and the upper structure, and has a lower surface fixed to the main surface of the support portion and a main surface fixed to the upper structure, and the upper structure is horizontal with respect to the support portion. An elastic portion that generates a restoring force in the horizontal direction corresponding to the amount of relative displacement in the direction,
The area of the lower surface of the elastic part and the main surface of the elastic part is a seismic isolation structure smaller than the area of the main surface of the support part.

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