JP2755868B2 - Seismic isolation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seismic isolation device mainly used for floor seismic isolation.

[0002]

BACKGROUND OF THE INVENTION Bearings of seismic isolation devices used for floor seismic isolation are fixed to a floor as an upper structure, and a sliding bearing that slides on a lower structure and a rolling bearing that rolls. Rolling bearings having a low coefficient of friction are advantageous for exhibiting an insulating effect from low-level vibration of the lower structure, and there are many examples.

For example, in Japanese Patent Publication No. 2-54040, a rolling element is provided between a bearing and an upper structure formed of a curved surface having a downwardly convex upper surface and a flat surface smoothly continuing from the curved surface. In the seismic isolation bearing, or Japanese Utility Model Publication No. 64-24242, the upper surface of the bearing body is formed as a downwardly convex conical surface, and a steel ball is stored in a viscous fluid on the bearing body with a spherical bearing. The supported seismic isolation bearings are announced.

However, in a seismic isolation bearing in which the upper surface of the bearing body is formed by a curved surface that is convex downward and a plane that is smoothly continuous with the curved surface, the radius of curvature of the plane portion is infinite and has a slope here. Therefore, the relative displacement of the bearing with respect to the bearing body, that is, the vibration cycle with respect to the vibration amplitude is constant.

[0005] The relationship between the vibration period T and the radius of curvature R is expressed by the following equation. g is the acceleration of gravity.

T = (1 / 2π) · (R / g) ^1/2 Generally, the period of a seismic motion is relatively short in many cases. Considering the restoring force of the bearing, the curvature cannot be made very small. The bearings and bearings that are directly received are likely to fall into resonance. In other words, although the restoring force can be maintained even if the vibration amplitude becomes excessive, the resonance state is inevitable for a seismic motion having a period substantially equal to the period of the vibration system determined by the curvature.

In other words, when the upper surface of the bearing body is constituted by a curved surface, the curvature of the curved surface is reduced to increase the period for the purpose of improving the seismic isolation performance of the rolling bearing. There was a contradiction that increasing the return force would increase the curvature and lower the seismic isolation performance.

Further, the conventional rolling bearing is mounted on a supporting body fixed to a lower structure and moves in two horizontal directions, so that it can cope only with seismic motion in two directions.

In the case where the seismic isolation bearing is formed by one conical surface, the period of the vibration system is constant as described above, and the range of the vibration period in which the seismic isolation effect can be exhibited is determined by the period determined by the cone angle. .

[0010] In addition, the viscous fluid is stored on the support body.
Turbulence resistance is not effective with the main damping force.

The present invention has been made in view of the problems that the bearing of the rolling bearing type seismic isolation device has.
It is intended to propose a new seismic isolation device that solves the above problem.

[0012]

According to the present invention, the upper surface of a bearing body for supporting a rolling bearing is formed by a curved surface having a downwardly convex curvature, so that resonance with the lower structure during operation is avoided, and the rolling bearing is supported. Have seismic isolation performance and ability to return to the original position.

The upper surface of the bearing body has a large curvature at the central portion where the rolling bearing is normally positioned, that is, the first curvature portion, and gives a relatively short first vibration period as a normal seismic isolation device, and its outer peripheral portion, that is, the second vibration period. In the curvature portion, a curved surface having a small curvature is formed to give a very long second vibration period, and the curvature changes, so that the periodic characteristic of the rolling bearing becomes non-linear, and resonance is avoided.

Further, by providing a large curvature at the outermost periphery, that is, a third curvature portion, a large restoring force is exerted against an excessive amplitude when the rolling bearing is relatively moved with respect to the bearing body, thereby providing a pawl. .

The ability to return to the original position is ensured by the central portion having a large curvature, that is, the first curvature portion, and the short-period ground motion can avoid resonance at the first curvature portion, but the amplitude becomes large due to the characteristics of the earthquake, When it exceeds one curvature, the seismic isolation effect is exerted irrespective of the characteristics of the earthquake motion by providing the second curvature having a small curvature, in other words, a long vibration period.

In addition, when a viscous fluid is stored on the bearing, a resistance plate is installed on the viscous fluid side of the rolling bearing, and when the rolling bearing moves by immersing the resistance plate in the viscous fluid, a gap between the viscous fluid and the resistance plate is required. The damping force is obtained by the shear frictional force generated in the above. Since the distance between the resistance plate and the bearing body is kept constant by the rolling bearing, the damping performance is also kept constant.

Further, a vertical spring for insulating the vertical vibration of the lower structure is arranged between the upper structure and the rolling bearing, and a rod which reaches the viscous fluid is protrudingly provided on the upper structure side so that a relative movement in the vertical direction can be achieved. The damping force is secured.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing one embodiment.

The seismic isolation device A of the present invention is fixed to a lower structure, and a support body 1 having a curved upper surface 1a, and a rolling member connected to the upper structure and supporting a vertical load while rolling on the support body 1. It consists of the bearing 2 and is installed between the floor slab, which is the lower structure, and the floor, which is the upper structure, and performs seismic isolation of the floor while avoiding resonance when the upper structure and the lower structure move relative to each other. It is.

The main body of the rolling bearing 2 is connected to a frame F for supporting a load on the upper structure, and a plurality of ball bearings 2 ₁ or 2 which rotate in an arbitrary direction while contacting the supporting body 1 at the lower end thereof. It has a structure in which one ball bearing having a diameter is stored.

The upper surface 1a of the scaffold 1, as shown in Figure 1 below
It has a convex curvature , the curvature at the center where the rolling bearing 2 is normally located is large, and the curvature at the outer periphery is smaller than that at the center. FIG. 2 shows the plane of FIG.

FIG. 3 shows a restoring force characteristic corresponding to the relative position of the rolling bearing 2 with respect to the curved bearing body 1 shown in FIG.
As shown in FIG. 1, when the lower structure moves relative to the upper structure from the normal state located at the center of FIG. 1, the vibration period of the rolling bearing 2 is limited by the amount of movement within the center of large curvature. Is small, and within this range, the original position return force of the rolling bearing 2 is high. The period of the movement amount over the range of the outer peripheral portion deviating from the center becomes longer, and the seismic isolation effect of the rolling bearing 2 increases as the relative movement amount increases.

When the amount of movement is large due to the difference in curvature between the central portion and the outer peripheral portion, the vibration period changes, and resonance with the input from the lower structure is avoided.

As shown in FIG. 1, when the rolling bearing 2 makes an excessive relative movement with respect to the supporting body 1, it is stopped and, at the same time, the outermost periphery is provided to have a returning force to the original position. The curvature of the closer part is increased. This portion may be a conical surface having an infinite radius of curvature.

The damping when the rolling bearing 2 moves relatively is obtained by the viscous fluid 3 stored on the bearing body 1 as shown.

[0026] In the viscous fluid 3, rolling is installed on ball bearing 2 ₁ of the support 2 resistance sheet 2 ₂ immersed, rolling principally resistive plate movement of the support 2 during relative movement of the bearing body 1
Is attenuated by shear resistance force generated 2 ₂ of the lower surface.

[0027] While the vibration in the vertical direction between the lower structure and the upper structure is interrupted by a vertical spring 2 ₃ which are arranged vertically oriented shaft on the body of the support 2 rolling, the attenuation during vertical vibration underside of the superstructure It is ensured by projecting the rod 2 ₄ reaching the viscous fluid 3 from. The effect of attenuation will form a rod 2 ₄ into a plurality of cylinders and wall plate can be adjusted by changing the area immersed in the viscous fluid 3.

[0028]

The present invention has been described above. Since the upper surface of the bearing body for supporting the rolling bearing is formed by a curved surface having a downwardly convex curvature , the rolling bearing sandwiches the boundary where the curvature changes. When the period becomes nonlinear and the vibration amplitude is large and reaches the second curvature portion, the vibration system has a long period, and thus exhibits the seismic isolation function efficiently.

Further, since the curvature of the normal position of the rolling bearing is large, the rolling bearing can be provided with the ability to return to the original position after the movement, and the vibration amplitude becomes excessively large and the second curvature portion or more. , The third curvature is large, and the vibration amplitude is stopped.

At the same time that the viscous fluid is stored on the bearing, a resistance plate or a rod is installed on the viscous fluid side of the rolling bearing, and these are immersed in the viscous fluid to move the rolling bearing when moving or vertical vibration. Vibration can be damped. The viscous fluid also has the effect of lubricating the rolling bearing and preventing rust.

In addition, since the seismic isolation device and the damper are realized by a single device by combining the rolling bearing and the viscous fluid as the damper, the mechanism required for the seismic isolation is simplified, and the manufacturing cost is reduced. Reduction is achieved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a seismic isolation device.

FIG. 2 is a plan view of FIG.

FIG. 3 is a restoring force characteristic diagram corresponding to the curvature of the bearing of the rolling bearing of FIG. 1;

[Explanation of symbols]

A ... seismic isolation device, 1 ... bearing body, 1a ... top surface, 2 ... rolling bearing, 2 ₁ ... ball bearing, 2 ₂ ... resistance plate, 2 ₃
…… Vertical spring, 2 ₄ …… Rod, 3 …… Viscous fluid, F ……
flame.

Claims (3)

(57) [Claims] 1. A seismic isolation device comprising: a support fixed to a lower structure and having a curved upper surface; and a rolling support connected to the upper structure and supporting a vertical load while rolling on the support. In the device, the upper surface of the bearing body has a downward convex curvature , and the curvature of the central portion where the rolling bearing is normally located gives the first cycle of the seismic isolation device in a range where the amplitude is small,
The curvature of the outer peripheral portion is made smaller than the curvature of the central portion to give a second period longer than the first period, and the curvature of the outermost peripheral portion is made sufficiently large to stop the excessive amplitude. And seismic isolation device. 2. A viscous fluid is stored on a support, and a resistance plate is provided on a viscous fluid side of the rolling bearing, and the resistance plate is immersed in the viscous fluid, and a viscous fluid between the resistance plate and the support is provided. The seismic isolation device according to claim 1, wherein the damping force is obtained by shear friction of the fluid. 3. A vertical spring whose axis is oriented vertically is arranged between the upper structure and the rolling bearing, and a rod reaching the viscous fluid is protrudingly provided on the upper structure side. Item 4. The seismic isolation device according to Item 2.