JP5596378B2 - Friction damper - Google Patents

Description

The present invention relates to a friction damper installed in a seismic isolation structure.

In the seismic isolation method, the natural period of the structure is set by installing a seismic isolation layer such as laminated rubber and linear guides between the structure (upper structure) and the foundation (lower structure). It is a construction method that reduces the earthquake acceleration input to the structure by increasing the period. Conventionally, in the seismic isolation system, a damping mechanism is provided in the seismic isolation layer so that the interlayer deformation does not become excessive. For example, in Patent Document 1, a first disk having an arm structure and a second disk having an arm structure that is pressed against the first disk via a friction material and is capable of relative rotational movement with respect to the first disk. There is disclosed a disk damper for a seismic isolation system in which one of the movable end portions of both disks is connected to a structure and the other is connected to a foundation.

JP-A-62-233386

In the case of a seismic isolation structure, the smaller the damping of the seismic isolation layer, the smaller the acceleration response magnification (response acceleration / input acceleration) in the high frequency range. That is, the seismic isolation effect is increased. For this reason, it is desirable that the damping of the seismic isolation layer be small for small and medium earthquakes where the input acceleration is small and the interlayer deformation of the seismic isolation layer is small. On the other hand, for large earthquakes with high input acceleration, it is desirable that the seismic isolation layer has a large attenuation so that the interlayer deformation of the seismic isolation layer does not become excessive. Therefore, a damper that can exhibit a small damping force when the input acceleration is small and the interlayer deformation of the base isolation layer is small, and a damper that can exhibit a large damping force when the input acceleration is large and the interlayer deformation of the base isolation layer is large is ideal. However, the conventional friction damper installed in the base isolation structure can always exhibit only a constant frictional force (damping force) regardless of the magnitude of the interlayer deformation of the base isolation layer.

The present invention has been made in view of such circumstances. When the input acceleration is small and the interlayer deformation of the seismic isolation layer is small, a small friction force is obtained. When the input acceleration is large and the interlayer deformation of the seismic isolation layer is large, a large friction force is obtained. It aims at providing the friction damper which can be exhibited.

To achieve the above object, a first invention is a friction damper installed in a seismic isolation layer provided between an upper structure and a lower structure,
A sliding member installed on the bottom surface of the upper structure via an elastic member that can be expanded and contracted in the vertical direction , a flat top portion formed on the upper surface of the lower structure, and an inclined portion formed around the top portion. A frustoconical protrusion having
The sliding member is disposed in a valley formed between the projecting portions arranged in a lattice shape in plan view, and the sliding member moves on the projecting portion in accordance with interlayer deformation of the seismic isolation layer. It is characterized by sliding.

The second invention is a friction damper installed in a seismic isolation layer provided between the upper structure and the lower structure,
A sliding member installed on the upper surface of the lower structure via an elastic member that can expand and contract in the vertical direction , a flat top portion formed on the bottom surface of the upper structure, and an inclined portion formed around the top portion. A frustoconical protrusion having
The sliding member is disposed in a valley formed between the projecting portions arranged in a lattice shape in plan view, and the sliding member moves on the projecting portion in accordance with interlayer deformation of the seismic isolation layer. It is characterized by sliding.

As the surface pressure acting on the sliding surface increases, the frictional force increases. In the first and second inventions, the elastic member is compressed as the sliding member climbs the inclined portion of the protruding portion, and the surface pressure acting between the sliding member and the protruding portion increases. As a result, the frictional force acting on the sliding member is increased, the surface pressure is maximized at the top of the protrusion, and the frictional force is also maximized. In the friction damper according to the first and second inventions, since the amount of interlayer deformation of the seismic isolation layer is small at the time of a small and medium earthquake, the sliding member also reciprocates at a low position of the protrusion, and only a small frictional force is generated. At the time of a large earthquake, since the amount of interlayer deformation of the seismic isolation layer is large, the sliding member also reciprocates to reach the top of the protrusion, and thus a large frictional force is generated.

In the friction damper according to the first and second inventions, at least one surface of the sliding member and the protrusion may be formed of a friction material. Thereby, a stable large frictional force can be generated.

In the friction damper according to the present invention, the sliding member slides on the protruding portion in accordance with the interlayer deformation of the seismic isolation layer provided between the upper structure and the lower structure. A small frictional force can be exerted for small interlaminar deformation, and a large frictional force can be exerted for large interlaminar deformation during a large earthquake, and an ideal seismic isolation structure can be realized.

It is a schematic diagram of the friction damper which concerns on one embodiment of this invention. It is an arrangement view of the friction damper. It is a schematic diagram for demonstrating the principle of a friction damper. It is a graph of the energy absorbed by a friction damper. It is a longitudinal cross-sectional view of an elastic member. It is a longitudinal cross-sectional view of the elastic member which concerns on a modification. It is the schematic diagram which looked at the guide part from the bottom.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention. The same applies to the case where the sliding member is installed on the upper surface of the lower structure and the protrusion is formed on the bottom surface of the upper structure. Only the case of installing and forming a protrusion on the upper surface of the lower structure will be described.

1 and 2 show a friction damper 10 according to an embodiment of the present invention. A laminated rubber 11, which is an example of a seismic isolation device, is interposed between the upper structure 12 and the lower structure 13, and the friction damper 10 is installed in a space between the laminated rubber 11 and the laminated rubber 11 in plan view. (See FIG. 2).

The friction damper 10 includes a plurality of protrusions 16 having a trapezoidal cross section formed on the upper surface of the lower structure 13, a sliding member 15 that slides on the protrusions 16, and one end connected to the sliding member 15. The upper structure 12 is generally composed of an elastic member 14 that can be expanded and contracted in the vertical direction.

Each protrusion 16 has a truncated cone shape having a flat top portion 16a and an inclined portion 16b formed around the flat top portion 16a, and is arranged in a lattice shape in plan view as shown in FIG. On the other hand, the sliding member 15 is disposed in a trough 17 formed between the protrusions 16. A metal such as concrete or iron can be used as the material of the protrusion 16, and a metal such as iron can be used as the material of the sliding member 15.
The elastic member 14 may be any member that can expand and contract in one direction and can apply a biasing force to the sliding member 15 along with expansion and contraction. For example, a spring such as a spring can be used.

In addition, you may form the surface of the sliding member 15 and the projection part 16 with a friction material. The material of the friction material is not particularly limited, and a conventionally known material can be used.

Next, the principle of the friction damper 10 according to the present embodiment will be described with reference to FIG. In FIG. 3, A and D indicate the lowest points of the inclined portion 16b, and B and C indicate both ends of the top portion 16a.
The inclination angle of the inclined portion 16b of the protrusion 16 is θ, and the elastic member 14 (sliding member 15) is displaced by x in the horizontal direction from the lowest point A of the inclined portion 16b. F is a normal direction component of F with respect to the inclined surface, and F is an inclined surface direction component of F. Further, when the spring constant in the vertical direction of the elastic member 14 is k and the coefficient of dynamic friction between the sliding member 15 and the protrusion 16 is μ ′, the following equation is established.

F = k · tanθ · x (1)
Fv = Fcosθ (2)
Fu = μ'Fv (3)

Substituting Equations (1) and (2) into Equation (3) gives Fu as follows.
Fu = μ′Fv = μ′k · tan θ cos θ · x
= Μ'k · sinθ · x (4)

On the other hand, when the displacement of the elastic member 14 (sliding member 15) moved along the inclined surface is L, L can be expressed by the following equation.
L = x / cos θ (5)

FIG. 4 is a graph with Fu on the vertical axis and L on the horizontal axis. The area surrounded by the broken line corresponds to the energy consumed by the friction damper 10. As is clear from FIG. 4, the frictional force increases as the elastic member 14 (sliding member 15) moves the inclined portion 16b of the protruding portion 16 from A to B, and the top portion 16a (that is, the range of B to C). ), The frictional force is maximized. Further, when the elastic member 14 (sliding member 15) moves the inclined portion 16b of the protruding portion 16 from C toward D, the frictional force starts to decrease.

When the friction damper 10 is applied to a base-isolated structure, since the interlayer deformation of the base isolation layer is small during a small and medium earthquake, the sliding member 15 is small by reciprocating between the low position of the inclined portion 16b and the valley portion 17. Demonstrates frictional force (damping force), and during large earthquakes, the interlayer deformation of the seismic isolation layer is large. Therefore, the sliding member 15 reciprocates from the inclined portion 16b to the top portion 16a to exert a large frictional force (damping force). To do.
In designing the friction damper 10, the amount of deformation of the seismic isolation layer during a small and large earthquake is assumed by seismic response analysis and the like, and the inclined portion 16 b and the top portion 16 a are based on the sliding amount of the sliding member 15. The width (length) of each is determined.

FIG. 5 shows an example of the elastic member 14 and the sliding member 15.
In this example, consideration is given so that the elastic member 14 does not deform in the horizontal direction. Specifically, the base end is fixed to the bottom surface of the upper structure 12, the inner cylinder 22 extending downward, the outer cylinder 21 that is externally mounted on the inner cylinder 22, and one end fixed to the outer periphery of the outer cylinder 21. The elastic member 14 is schematically constituted by the spring 20 having the other end fixed to the bottom surface of the upper structure 12, and the hemispherical sliding member 15 is fixed to the bottom surface of the outer cylinder 21. Further, a low friction material 23 having a small friction coefficient, such as polytetrafluoroethylene, is interposed between the inner cylinder 22 and the outer cylinder 21, and air holes 24 are provided in the peripheral wall of the outer cylinder 21. Yes.
In this example, when the hemispherical sliding member 15 slides on the protrusion 16, the outer cylinder 21 moves only in the vertical direction and restrains the elastic member 14 from deforming in the horizontal direction.

6 and 7 show an elastic member 18 according to a modification.
In this example, the elastic member 18 includes an inner cylinder 26 whose base end is fixed to the bottom surface of the upper structure 12, a guide portion 27 attached to the bottom surface of the inner cylinder 26, and a guide portion 27 that guides the elastic member 18. The outer cylinder 25 is movable in the direction, and the spring 20 has one end fixed to the outer periphery of the outer cylinder 25 and the other end fixed to the bottom surface of the upper structure 12. A hemispherical sliding member 15 is fixed to the bottom surface of the outer cylinder 25.

The guide portion 27 is mounted on the bottom surface of the inner cylinder 26 and is rotatable on a horizontal plane, and a pair of pulleys 29 that are juxtaposed on the rotation plate 28 and are in contact with the inner wall surface of the outer cylinder 25. , 30 and a belt 31 that is tucked between a pair of pulleys 29, 30.
In this example, when a horizontal force H is applied from a direction different from the conveying direction of the belt 31 (see the left figure in FIG. 7), the rotating plate 28 rotates in a horizontal plane, and the conveying direction of the belt 31 in the plan view. The direction of action of the horizontal force H coincides (see the right figure in FIG. 7).

Although one embodiment of the present invention has been described above, the present invention is not limited to the configuration described in the above-described embodiment, and is within the scope of matters described in the claims. Other possible embodiments and modifications are also included. For example, in the above-described embodiment, the shape of the protrusion is a truncated cone and the shape of the sliding member is a hemispherical shape, but it is needless to say that the shape is not limited to this and may be other shapes. In the above-described embodiment, the projections are arranged in a lattice shape in plan view, but other different arrangement patterns such as arranging the projection portions in a staggered pattern in plan view may be used.

10: friction damper, 11: laminated rubber, 12: upper structure, 13: lower structure, 14: elastic member, 15: sliding member, 16: protrusion, 16a: top, 16b: inclined part, 17: valley Part, 18: elastic member, 20: spring, 21: outer cylinder, 22: inner cylinder, 23: low friction material, 24: air hole, 25: outer cylinder, 26: inner cylinder, 27: guide part, 28: times Moving plate, 29, 30: pulley, 31: belt

Claims (3)

A friction damper installed in a seismic isolation layer provided between the upper structure and the lower structure,
A sliding member installed on the bottom surface of the upper structure via an elastic member that can be expanded and contracted in the vertical direction , a flat top portion formed on the upper surface of the lower structure, and an inclined portion formed around the top portion. A frustoconical protrusion having
The sliding member is disposed in a valley formed between the projecting portions arranged in a lattice shape in plan view, and the sliding member moves on the projecting portion in accordance with interlayer deformation of the seismic isolation layer. Friction damper characterized by sliding. A friction damper installed in a seismic isolation layer provided between the upper structure and the lower structure,
A sliding member installed on the upper surface of the lower structure via an elastic member that can expand and contract in the vertical direction , a flat top portion formed on the bottom surface of the upper structure, and an inclined portion formed around the top portion. A frustoconical protrusion having
The sliding member is disposed in a valley formed between the projecting portions arranged in a lattice shape in plan view, and the sliding member moves on the projecting portion in accordance with interlayer deformation of the seismic isolation layer. Friction damper characterized by sliding. The friction damper according to claim 1 or 2, wherein at least one surface of the sliding member and the protrusion is formed of a friction material.

Images