US20060260222A1

US20060260222A1 - Rocking-type seismic isolation base for protecting structure against earthquake

Info

Publication number: US20060260222A1
Application number: US11/433,447
Authority: US
Inventors: Wei Lee
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-05-17
Filing date: 2006-05-15
Publication date: 2006-11-23
Also published as: JP3123586U; TWM283013U

Abstract

A rocking-type seismic isolation base for protecting structure against earthquake includes a body having a configuration similar to a generally recognized flying saucer. The base serves as a buffer when a structure is horizontally displaced relative to a supporting foundation of the structure, and largely reduces the vertical displacement of the structure. The rocking-type seismic isolation base also allows the displaced structure to automatically return to its original position. The base is provided at a bottom with a space for an anti-slipping lock to mount and freely move therein, so as to prevent the rocking-type base from horizontally slipping in a condition exceeded the designed seismic vibration. The rocking-type base may be cooperatively used with a saucer spring to further mitigate the vertical vibration.

Description

FIELD OF THE INVENTION

The present invention relates to a seismic isolation device applicable to the fields of civil engineering, construction, and mechanical engineering; and more particularly to a rocking-type seismic isolation base having a configuration similar to a generally recognized flying saucer and provided with a bottom space for mounting an anti-slipping lock therein.

BACKGROUND OF THE INVENTION

The currently available seismic isolation products for protecting a structure against earthquake mainly include lead rubber isolation bearings, friction-type isolation bases, etc. While the present invention and these conventional seismic isolation products employ similar principles for the same purpose of seismic isolation, the present invention is quite different from the conventional products in terms of its shape and mounting technique. According to a major seismic isolation principle, a seismic isolation product generally utilizes various kinds of components to enable a structure to have a swing period longer than the vibration period of a seismic origin, so as to achieve the object of seismic isolation.
It is known in general mechanical and seismic fields that when a relatively swinging component has different radiuses of swinging, the component may have an extended swinging period.

SUMMARY OF THE INVENTION

A primary object of the present invention is to provide a seismic isolation device to mitigate the influences of earthquake on a structure.
To achieve the above and other objects, the seismic isolation device according to the present invention is a rocking-type seismic isolation base including a body having a configuration similar to a generally recognized flying saucer. In a preferred embodiment of the present invention, the rocking-type seismic isolation base has a concave spherical upper surface having a relatively small rolling radius and a convex spherical lower surface having a relatively large rolling radius. The base so designed may have a swinging period larger than that of a seismic origin to achieve the effect of seismic isolation.
The rocking-type seismic isolation base serves as a buffer when a structure is horizontally displaced relative to a supporting foundation of the structure, and largely reduces the vertical displacement of the structure. The rocking-type seismic isolation base also allows the displaced structure to automatically return to its original position.
The rocking-type seismic isolation base is provided at a bottom with a space for an anti-slipping lock to mount and freely move therein, so as to prevent the rocking-type base from horizontally slipping in a condition exceeded the designed seismic vibration.
The rocking-type seismic isolation base may be cooperatively used with a saucer spring and/or a plunger piston to further mitigate the vertical vibration.

BRIEF DESCRIPTION OF THE DRAWINGS

The structure and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings, wherein
FIG. 1 is a side view of a rocking-type seismic isolation base having a concave spherical upper surface according to a preferred embodiment of the present invention for protecting a structure against earthquake, wherein an anti-slipping lock is associated with the base;
FIG. 2 is a side view showing the rocking-type seismic isolation base of FIG. 1 before and after rocking;
FIG. 3 is a side view showing the rocking-type seismic isolation base of the present invention associated with an anti-slipping lock and a saucer spring assembly;
FIG. 4 shows the rocking-type seismic isolation base of FIG. 3 before and after rocking;
FIGS. 5-1, 5-2, and 5-3 are top, front, and side views, respectively, of the rocking-type seismic isolation base according to the preferred embodiment of the present invention, wherein the base is provided with a bottom space for the anti-slipping lock to mount therein;
FIGS. 6-1, 6-2, and 6-3 are bottom, front, and side views, respectively, of a saucer spring assembly for rotatably mounted in the concave spherical upper surface of the rocking-type seismic isolation base of the present invention;
FIGS. 7-1, 7-2, and 7-3 are top, front, and side views, respectively, of an anti-slipping lock for associating with the rocking-type seismic isolation base of the present invention, wherein the anti-slipping lock has a ball-shaped locking head;
FIG. 8 schematically shows a rocking-type seismic isolation base having a convex spherical upper surface according to a second embodiment of the present invention; and
FIG. 9 schematically shows a rocking-type seismic isolation base according to a third embodiment of the present invention, wherein the base has a concave spherical upper surface associated with a plunger piston and a saucer spring.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Please refer to FIG. 1 that is a side view schematically showing a rocking-type seismic isolation base 1 according to a preferred embodiment of the present invention for protecting a structure against earthquake.
As shown, the rocking-type seismic isolation base 1 of the present invention has a configuration similar to a generally recognized flying saucer, and includes a concave spherical upper surface 5 allowing a correspondingly shaped member to rotate and slide thereon, and a convex spherical lower surface 6 allowing the base 1 to rotate and roll or rock on a foundation surface 2. The concave spherical upper surface 5 has a radius smaller than that of the convex spherical lower surface 6. The concave spherical upper surface 5 is in tight and firm contact with a contact surface of the same radius pre-provided on the structure, while the convex spherical lower surface 6 is in point contact with the foundation surface 2.
When rolling or rocking, the base 1 moves horizontally relative to the foundation surface 2. Since the rocking-type base 1 rolls or rocks to move, a friction between the convex spherical lower surface 6 and the foundation surface 2 is relatively small to allow the base 1 to easily move horizontally. On the other hand, a friction between a sliding article and a supporting surface is relatively large. Therefore, the condition of horizontal sliding would not occur under generally relatively small seismic vibration.
With the concave spherical upper surface 5 having a relatively small rolling radius and the convex spherical lower surface 6 having a relatively large rolling radius, the base 1 so designed may have a swinging period larger than that of a seismic origin to achieve the effect of seismic isolation. Meanwhile, as shown in FIG. 2, when the base 1 rolls and moves, a center of sphere 7 of the concave upper surface 5 of the base 1 before rolling is shifted to a point indicated by a reference number of “8”. A geometrically positional relation between the center of sphere 7 and the center of sphere 8 indicates that the rocking-type seismic isolation base 1 provides a relatively large horizontal displacement, compared to the relatively small vertical displacement.
From a comparison between the shifted center of sphere 8 and the original center of sphere 7 of the concave spherical upper surface 5 of the rocking-type seismic isolation base 1, it can be seen from FIG. 2 that the shifted center of sphere 8 is always offset from a perpendicular line 9 passing a bearing point of the rolling base 1. It is also found the offset distance increases with the increased displacement of the rolling base 1, which indicates the rocking-type seismic isolation base 1 has the property of automatically returning to an original position.
While it is ensured the rocking-type seismic isolation base 1 would not slide to displace within the designed seismic vibration condition, any possible special condition exceeded the seismic vibration design condition must still be taken into consideration. For this purpose, the base 1 is provided at the convex spherical lower surface 6 with a bottom space 4 for an anti-slipping lock 3 to mount thereto, so as to enhance the safety in using the rocking-type seismic isolation base 1 of the present invention. From an observation of a geometrically positional relation between the bottom space 4 and the anti-slipping lock 3, it is found the bottom space 4 preferably has a curved inner surface to provide an optimal moving condition for the anti-slipping lock 3.
Generally, when a seismic isolation device is cooperatively used with a damping device, it is possible to provide the whole structure with an enhanced earthquake-resistant condition. Therefore, it is strongly recommended that a structure should be designed to allow direct mounting of a vertical earthquake vibration cushion spring thereto, so as to cooperate with an overall earthquake resisting solution.
Please refer to FIG. 3. In a most preferred embodiment of the present invention, the rocking-type seismic isolation base 1 is associated with, in addition to the anti-slipping lock 3, a saucer spring assembly 10 that is in contact with a structure 11. In this manner, the base 1 of the present invention not only provides the basic seismic isolation function, but also the effect of mitigating the vertical earthquake vibration. From FIG. 4, it can be clearly seen when the base 1 with the anti-slipping lock 3 and the saucer spring assembly 10 rocks, the structure 11 is displaced from an original position 12 to a displaced position 13. Again, the rolling or rocking base 1 with the anti-slipping lock 3 and the saucer spring assembly 10 produces a horizontal displacement relatively larger than a vertical displacement.
FIGS. 5-1, 5-2, and 5-3 are top, front, and side views, respectively, of the rocking-type seismic isolation base 1 according to the preferred embodiment of the present invention. As shown, the base 1 includes the concave spherical upper surface 5, the convex spherical lower surface 6, and the bottom space 4 for the anti-slipping lock 3 to mount and freely move therein. Therefore, the base 1 is allowed to rock and swing on the foundation surface 2 as shown in FIGS. 1 and 3.
FIGS. 6-1, 6-2, and 6-3 are bottom, front, and side views, respectively, of the saucer spring assembly 10. As shown, the saucer spring assembly 10 includes a saucer spring 15 provided on a top of a bearing device 14. The bearing device 14 defines a spherical contact surface 16 that fitly and rotatably contacts with the concave spherical upper surface 5 when the bearing device 14 is directly mounted on the top of the base 1 to link the base 1 to the structure 11, so as to mitigate the vertical earthquake vibration applied to the structure 11.
FIGS. 7-1, 7-2, and 7-3 are top, front, and side views, respectively, of the anti-slipping lock 3. As shown, the anti-slipping lock 3 has a ball-shaped locking head for smoothly contact with the curved inner surface of the bottom space 4.
FIG. 8 schematically shows a rocking-type seismic isolation base according to a second embodiment of the present invention. In the second embodiment, the base 1 has a ball-shaped top defining a convex spherical upper surface 17 having a center of sphere 7, and a convex spherical lower surface 6. The convex spherical upper surface 17 is fitly and rotatably engaged with a corresponding concave spherical surface 19 formed on a structure 18.
FIG. 9 schematically shows a rocking-type seismic isolation base according to a third embodiment of the present invention. In the third embodiment, the base 1 has a convex spherical lower surface 6, and a concave spherical upper surface having a center of sphere 7. A plunger piston 20 is located on the top of the base 1 with a ball-shaped lower end fitly and rotatably engaged with the concave spherical upper surface of the base 1. And, a saucer spring 21 is located between an upper end of the plunger piston 20 and a structure 22, which is provided with a cavity corresponding to the plunger piston 20 and the saucer spring 21. With these arrangements, the plunger piston 20 may have a relatively large vertical stroke within a predetermined planar area.

Claims

1. A rocking-type seismic isolation base for protecting a structure against earthquake, comprising a body having a configuration similar to a generally recognized flying saucer, and including a spherical upper surface allowing a member having correspondingly shaped matching surface to rotate and slide thereon, and a convex spherical lower surface allowing the base to rotate, roll, or rock on a foundation surface; wherein said spherical upper surface has a small radius relative to said spherical lower surface.

2. The rocking-type seismic isolation base for protecting a structure against earthquake as claimed in claim 1, wherein said body is provided at said convex spherical lower surface with a bottom space having a curved inner surface for an anti-slipping lock device to mount and freely rotate and move in said bottom space.