JP7284684B2 - seismic isolation system - Google Patents

Description

The present invention relates to a seismic isolation system.

There is a seismic isolation system as a means to improve the seismic performance of equipment such as turbines and rolling mills and structures such as buildings. By installing the seismic isolation system under the structure to reduce the seismic load, the seismic isolation system absorbs the seismic energy during an earthquake and reduces the seismic load acting on the structure.

A seismic isolation system consists of seismic isolation devices that have the following functions: supporting performance for structures, damping performance for absorbing seismic energy during an earthquake, and restoration performance for returning to the original position against displacement that occurs during an earthquake. be.

Typical seismic isolation devices include laminated rubber, laminated rubber with lead plugs, sliding bearings, rolling bearings, oil dampers, steel dampers, and coil springs. used.

In particular, the laminated rubber has a laminated structure of thin rubber and thin steel plates, and achieves mechanical properties of low rigidity in the horizontal direction and high rigidity in the vertical direction, and has supporting performance and restoring performance. Furthermore, the laminated rubber containing lead plugs is a seismic isolation device in which a lead column is installed in the lamination direction of the laminated rubber, and hysteresis damping is imparted by plastic deformation of the lead column.

A seismic isolation system that combines laminated rubber and sliding bearings has also been proposed.

Japanese Patent Application Laid-Open No. 9-242818 (Patent Document 1) is a background art of this technical field. In Patent Document 1, a structure is mounted on a foundation by at least one or more laminated rubber layers in which elastic layers and rigid plate layers are alternately laminated in multiple layers, and at least four or more rolling bearings. A seismic isolation system that is horizontally movably supported, in which at least four or more rolling bearings are installed on or near the periphery of the bottom surface of the structure, and at least one or more laminated rubber is attached to the bottom surface of the structure. A seismic isolation system is described for installation in a space enclosed by four or more rolling bearings inside a building (see abstract).

JP-A-9-242818

Patent Literature 1 describes a seismic isolation system that combines laminated rubber and rolling bearings.

On the other hand, when an excessive seismic load acts on laminated rubber (hereinafter, including laminated rubber containing lead plugs), hardening occurs in which the laminated rubber greatly deforms and increases in rigidity. As a result, the seismic load acting on the structure may suddenly increase.

However, Patent Document 1 describes a sudden increase in the seismic load acting on the structure due to occurrence of hardening of the laminated rubber when an excessive seismic load acts, and measures to deal with this sudden increase in the seismic load. Not listed.

Accordingly, the present invention provides a seismic isolation system that exhibits excellent seismic isolation performance even when a strong seismic motion acts.

In order to solve the above-described problems, the seismic isolation system of the present invention is installed between a foundation and a structure, has laminated rubber and sliding bearings, and reduces the seismic load acting on the structure. is.

The sliding bearing forms a sliding surface with a circular planar shape and a concave inner and convex cross-sectional shape, and supports the sliding surface forming member fixed to the foundation and the structure. and a sliding member that slides on the sliding surface and is fixed to the structure during an earthquake.

According to the present invention, it is possible to provide a seismic isolation system that exhibits excellent seismic isolation performance by suppressing a rapid increase in seismic load input to a structure even when a strong seismic motion acts.

Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

It is an elevation view explaining the seismic isolation system described in a present Example. 1 is a perspective view explaining a multi-curved slide bearing 1 of a seismic isolation system described in this embodiment. FIG. FIG. 2 is a plan view for explaining the multi-curved sliding bearing 1 of the seismic isolation system described in this embodiment. 1 is a cross-sectional view for explaining a multi-curved slide bearing 1 of a seismic isolation system described in this embodiment. FIG. Cross-sectional view for explaining the (a) static state, (b) operating state when a design level seismic load is applied, and (c) operating state when an excessive design level seismic load is applied, of the seismic isolation system described in this embodiment. is. FIG. 4 is an explanatory diagram for explaining the relationship between horizontal load and horizontal displacement for explaining the horizontal dynamic characteristics of the seismic isolation system according to the present embodiment. It is an explanatory view explaining plane arrangement of a seismic isolation system described in this example.

Embodiments of the present invention will be described below with reference to the drawings. It should be noted that substantially the same or similar configurations are denoted by the same reference numerals, and the description may be omitted if the description is redundant.

First, the configuration of the seismic isolation system described in this embodiment will be described.

FIG. 1 is an elevational view illustrating the seismic isolation system described in this embodiment.

The seismic isolation system described in this embodiment reduces the seismic load acting on the structure 3 during an earthquake. It is installed between the upper surface of the foundation 4 installed in the direction (this space may be hereinafter referred to as a "seismic isolation layer").

The laminated rubber 2 has a laminated structure of thin rubber and thin steel plates. The laminated rubber 2 has a lower portion fixed to the upper surface of the foundation 4 and an upper portion fixed to the lower surface of the structure 3 . The laminated rubber 2 may be laminated rubber containing a lead plug in which a lead column is installed in the lamination direction of the laminated rubber 2 .

Next, the multi-curved sliding bearing 1 of the seismic isolation system described in this embodiment will be described.

FIG. 2 is a perspective view explaining the multi-curved sliding bearing 1 of the seismic isolation system described in this embodiment, FIG. 3 is a plan view explaining the multi-curved sliding bearing 1 of the seismic isolation system described in this embodiment, FIG. 4 is a cross-sectional view for explaining the multi-curved sliding bearing 1 of the seismic isolation system described in this embodiment.

The multi-curved surface sliding bearing 1 has a circular planar shape as shown in FIG. 4, and a sliding member 5 that supports the structure 3, slides on the sliding surface 6 during an earthquake, and is fixed to the structure 3. The sliding surface forming member 10 has a sliding surface 6 having a concave shape 8 and a convex shape 9, and a flat bottom surface. The concave shape 8 and the convex shape 9 are then connected to form a series of smooth surfaces.

Here, the sliding surface of the sliding bearing of the present embodiment is not simply concave in cross section, but has a concave shape 8 and a convex shape 9, so that it is called a "multi-curved surface sliding bearing 1".

In the multi-curved sliding bearing 1 , the bottom surface of the sliding surface forming member 10 is fixed to the base 4 , and the sliding member 5 slides on the sliding surface 6 . Also, in the multi-surface sliding bearing 1 , one end of the sliding member 5 is fixed to the structure 3 , and the other end of the sliding member 5 slides on the sliding surface 6 .

Moreover, the multi-surface sliding bearing 1 has a stationary member 7 that stops the sliding of the sliding member 5 on the outer peripheral portion of the sliding surface forming member 10 . That is, the stationary member 7 suppresses displacement of the sliding member 5 .

Next, the operation of the seismic isolation system described in this embodiment will be described with reference to FIG.

FIG. 5 shows the seismic isolation system described in this embodiment: (a) static state, (b) operating state when design level seismic load is applied, and (c) operating state when design level seismic load is applied. It is a sectional view explaining.

FIG. 5 shows the case where one multi-curved sliding bearing 1 and two laminated rubbers 2 on both sides thereof are installed in the seismic isolation layer.

The laminated rubber 2 has its upper portion fixed to the structure 3 and its lower portion fixed to the foundation 4 .
A sliding member 5 of the multi-curved sliding bearing 1 is fixed to the structure 3 , and a sliding surface forming member 10 is fixed to the foundation 4 .

FIG. 5(a) shows a static state (initial state) where no seismic load is acting. and the center of the concave shape 8). Moreover, the laminated rubber 2 is not shear-deformed, and no displacement occurs between the upper portion and the lower portion.

FIG. 5(b) shows the operating state under design level seismic loads. Due to the action of the seismic load, the structure 3 is displaced to the right side (horizontal direction) of the paper surface (the foundation 4 is displaced to the left side (horizontal direction) of the paper surface).

In the state of FIG. 5(b), the slide member 5 slides within the range of the concave shape 8 in the multi-curved plain bearing 1. As shown in FIG. Also, in this state, the laminated rubber 2 undergoes shear deformation, and displacement occurs in the horizontal direction between the upper portion and the lower portion.

In the state shown in FIG. 5(b), the sliding member 5 is sliding within the range of the concave shape 8, and the multi-curved sliding bearing 1 has an axis generated by supporting the structure 3. The multi-curved plain bearing 1 exhibits damping performance due to the action of the resistance generated by the force and the friction (sliding friction) between the sliding member 5 and the sliding surface 6 .

FIG. 5(c) shows the operating state when a seismic load exceeding the design level acts. Here, the over-design level is the case where an earthquake that exceeds the earthquake level assumed in normal design acts. should be reduced.

In the state shown in Fig. 5(c), an earthquake load larger than that shown in Fig. 5(b) acts, causing the structure 3 to be displaced (foundation 4 is displaced to the left side (horizontal direction) of the paper surface to a greater extent than in FIG. 5(b).

In the state of FIG. 5(c), the sliding member 5 of the multi-curved plain bearing 1 slides up to the range of the convex shape 9. As shown in FIG. Moreover, in this state, the laminated rubber 2 undergoes shear deformation, and a displacement larger than that shown in FIG. 5B occurs in the horizontal direction between the upper portion and the lower portion.

Next, the horizontal dynamic characteristics of the seismic isolation system described in this embodiment will be described with reference to FIG.

The left diagram of FIG. 6 shows the relationship between the horizontal load and horizontal displacement of the laminated rubber 2, the middle diagram of FIG. The figure shows the relationship between the horizontal load and the horizontal displacement as a seismic isolation system, which is the sum of the relationship between the horizontal load and the horizontal displacement of the laminated rubber 2 and the multi-surface sliding bearing 1. The relationship with displacement is stiffness.

As displacement amounts shown in FIG. 6, D1 indicates linear limit displacement (upper limit displacement at which the rigidity of the laminated rubber is constant), and D2 indicates damage limit displacement (displacement at which the laminated rubber is excessively deformed and damaged).

In addition, the multi-curved sliding bearing 1 actually generates a resistance force due to sliding friction during operation. The resistance force due to sliding friction is excluded.

Furthermore, the relationship between the horizontal load and the horizontal displacement of the laminated rubber 2 shown in the left diagram of FIG. Let it be shown by two stiffnesses where ning occurs and the stiffness increases.

On the other hand, in the relationship between the horizontal load and the horizontal displacement of the seismic isolation system of the present invention shown in the right side of FIG. . The characteristics of the multi-curved sliding bearing 1 are set so that the seismic isolation system shown in this embodiment can obtain such dynamic characteristics.

In the relationship between the horizontal load and the horizontal displacement of the multi-curved plain bearing 1 shown in the central diagram of FIG. In the range exceeding the linear limit displacement D1, the laminated rubber 2 has negative rigidity (negative slope) so as to offset the increase in rigidity.

In the conventional seismic isolation system that includes laminated rubber in its configuration, when a powerful earthquake that exceeds the design level acts, hardening occurs, the seismic load transmitted to the structure 3 increases, and the structure 3 The seismic load acting on the On the other hand, in the seismic isolation system shown in this embodiment, since the rigidity does not change even in the range exceeding the linear limit displacement D1, even if a strong earthquake with a level exceeding the design acts, it will act on the structure 3 It is possible to suppress a sudden increase in the seismic load caused by the earthquake.

In addition, the multi-surface sliding bearing 1 has positive rigidity in the range up to the linear limit displacement D1 because the sliding surface 6 has the concave shape 8, and the seismic isolation system bears part of the stiffness of Thereby, the rigidity to be imparted to the laminated rubber 2 can be reduced.

The rigidity of the laminated rubber 2 in the range exceeding the linear limit displacement D1 increases from the rigidity of the laminated rubber 2 in the range up to the linear limit displacement D1 due to hardening. By reducing the rigidity to be imparted to the laminated rubber 2, the increase in the rigidity of the laminated rubber 2 in the range exceeding the linear limit displacement D1 can be reduced.

Furthermore, in the range exceeding the linear limit displacement D1, the increased amount of rigidity of the laminated rubber 2 becomes small, so that the convex shape 9 of the multi-curved sliding bearing 1 is provided corresponding to the increased amount of rigidity of the laminated rubber 2. Rigidity can also be reduced, and the seismic isolation system can be rationally configured.

Thus, according to the present embodiment, it is possible to construct a rational seismic isolation system as a combination of the laminated rubber 2 and the multi-surface sliding bearing 1, and it is possible to provide a seismic isolation system excellent in arrangement. .

Next, a method of setting the concave shape 8 and the convex shape 9 for embodying the relationship between the horizontal load and the horizontal displacement of the multi-curved sliding bearing 1 will be described.

Rigidity K of the multi-curved sliding bearing 1 is obtained from the formula (1) using the weight W to be supported and the radius of curvature R of the sliding surface.

K=W/R (1)
Based on the formula (1), the curvature radius R of the concave shape 8 or the curvature radius R of the convex shape 9 are combined with the rigidity of the laminated rubber 2 and set so as to obtain the rigidity of the seismic isolation system.

For example, when considering a seismic isolation system composed of one multi-curved sliding bearing 1 and one laminated rubber 2 for simplification, the stiffness of the laminated rubber 2 in the range up to the linear limit displacement D1 is K21, K22 is the rigidity of the laminated rubber 2 in the range exceeding the linear limit displacement D1, K00 is the rigidity of the seismic isolation system, K11 is the rigidity of the multi-surface sliding bearing 1 in the range up to the linear limit displacement D1, and exceeds the linear limit displacement D1. Assuming that the stiffness of the multi-surface sliding bearing 1 in the range is K12 (negative stiffness), K11 is obtained by K00-K21, and K12 is obtained by K00-K22. The radius of curvature R of the concave shape 8 is obtained by W/K11, and the radius of curvature R of the convex shape 9 is obtained by W/K12.

In addition, since the multi-curved surface sliding bearing 1 of this embodiment has the stationary member 7 on the outer peripheral portion of the sliding surface forming member 10, the seismic isolation system deforms beyond the damage limit displacement D2 in the absence of the stationary member 7. Even if a strong earthquake load such as a 2 damage can be suppressed.

Since the weight of the structure 3 is supported by the multi-curved sliding bearing 1 and the laminated rubber 2 that constitute the seismic isolation system, by changing the number of combinations of the multi-curved sliding bearing 1 and the laminated rubber 2, the multi-curved sliding A support weight W per bearing 1 can be adjusted.

In this embodiment, the laminated rubber 2 having two stiffnesses and the multi-curved sliding bearing 1 are combined, but the present invention is not limited to this combination. The seismic isolation device and the poly-curved sliding bearing 1 may be used in combination.

In that case, by setting the cross-sectional shape of the sliding surface 6 according to the rigidity change of the combined seismic isolation device, it is possible to construct a seismic isolation system having dynamic characteristics effective in reducing the seismic load.

Furthermore, although the present embodiment shows a seismic isolation system having constant stiffness, the present invention is not limited to a seismic isolation system having constant stiffness. According to the present invention, by changing the cross-sectional shape of the sliding surface 6, it is possible to set a dynamic characteristic effective for reducing the seismic load acting on the structure 3.

Next, the operation of the seismic isolation system of this embodiment after an earthquake will be described.

In the operating state shown in FIG. 5(b), both the laminated rubber 2 and the multi-surface sliding bearing 1 have positive rigidity, and can be restored to the initial state shown in FIG. 5(a) by restoring force after an earthquake. is.

In the operating state shown in FIG. 5(c), the laminated rubber 2 has positive rigidity, and the multi-surface sliding bearing 1 has negative rigidity. Although the multi-surface sliding bearing 1 has negative stiffness, the entire seismic isolation system has positive stiffness, so a restoring force acts and the system can be restored to the initial state shown in Fig. 5(a). .

Next, the planar layout of the seismic isolation system described in this embodiment will be described.

FIG. 7 is a planar layout of the seismic isolation system described in this embodiment. In FIG. 7, the seismic isolation layer is provided with 8 multi-curved sliding bearings 1 and 11 laminated rubbers 2, and the multi-curved sliding bearings 1 are placed outside the laminated rubbers 2 (outside the seismic isolation layer). Installed.

In the arrangement example of FIG. 7, the axial force fluctuation acts on the seismic isolation system due to the rocking behavior caused by the action of the vertical and horizontal seismic motions due to the lamination rubber 2 with relatively small axial proof stress placed inside. When doing so, damage to the seismic isolation system can be prevented.

This embodiment is not limited to the planar arrangement of FIG. 7, and even when the cardinal numbers of the multi-curved sliding bearing 1 and the laminated rubber 2 are changed, the multi-curved sliding bearing 1 is arranged on the outer peripheral side. Thus, fluctuations in axial force acting on the laminated rubber 2 can be reduced.

The present invention is not limited to the above-described embodiments, and includes various modifications. For example, the above-described embodiments are specifically described in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described.

Also, part of the configuration of one embodiment can be replaced with part of the configuration of another embodiment. Alternatively, the configuration of another embodiment can be added to the configuration of one embodiment. Alternatively, a part of the configuration of each embodiment can be deleted, a part of another configuration can be added, and a part of another configuration can be substituted.

For example, instead of the laminated rubber 1, a seismic isolation device such as an elastic sliding bearing, a linear guide, or a coil spring can be combined with the multi-curved sliding bearing 1. In this case, the seismic load acting on the structure 3 can be reduced by setting the cross-sectional shape of the sliding surface 6 of the multi-surface sliding bearing 1 according to the dynamic characteristics of the combined seismic isolation device.

Furthermore, a damping member such as an oil damper or a steel damper can be added to the combination of the multi-curved sliding bearing 1 and the laminated rubber 2 . As a result, the seismic isolation response characteristics can be effectively adjusted, and an excellent seismic response reduction effect can be exhibited.

Reference Signs List 1 Multi-curved sliding bearing 2 Laminated rubber 3 Structure 4 Foundation 5 Sliding member 6 Sliding surface 7 Stationary member 8 Concave shape 9 Convex shape 10 Sliding surface forming member

Claims (5)

A seismic isolation system installed between a foundation and a structure, having laminated rubber and sliding bearings, and reducing seismic loads acting on the structure,
The sliding bearing forms a sliding surface having a circular planar shape and a cross-sectional shape that is concave on the inner side and convex on the outer side, and is fixed to the base. a sliding member that supports and slides on a sliding surface during an earthquake and is fixed to the structure. A seismic isolation system according to claim 1,
A seismic isolation system, wherein the sliding bearing has a stationary member that stops the sliding of the sliding member on an outer peripheral portion of the sliding surface forming member. A seismic isolation system according to any one of claims 1 and 2,
A seismic isolation system, wherein the radius of the concave shape is the same as the linear limit displacement of the laminated rubber, and the radius of the convex shape is smaller than the damage limit displacement of the laminated rubber. A seismic isolation system according to any one of claims 1 to 3,
A seismic isolation system according to claim 1, wherein the sliding bearing has a rigidity that offsets an increase in rigidity of the laminated rubber in a range exceeding the linear limit displacement of the laminated rubber. A seismic isolation system according to any one of claims 1 to 4,
A seismic isolation system, wherein the sliding bearing is installed outside the laminated rubber.

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