Seismic isolation systems comprising a load-bearing surface having a polymeric material

Abstract

A new seismic isolation bearing assembly is disclosed. The assembly includes a first isolation bearing plate, a second isolation bearing plate, and a moveable bearing element disposed between the first and second isolation bearing plates, each of the first and second isolation plates comprises a solid material and a surface facing the other isolation plate comprising a polymeric material different from the solid material. The polymeric material is effective to enhance the operability of the assembly.

Claims

1. A seismic isolation bearing assembly comprising: a first isolation bearing plate; a second isolation bearing plate; and a moveable bearing element disposed between the first and second isolation bearing plates, each of the first and second isolation plates comprises a solid material and a surface facing the other isolation plate comprising a polymeric material different from the solid material, said polymeric material being tacky and causing a reduction in sliding, stopping, and/or skipping of the movable bearing element as it moves across the surfaces of the first and second isolation plates, wherein the polymeric material comprises a 100% polyurea polymer, has a hardness (Shore D) of about 45-55, a tensile strength of about 2800-3200 pounds per square inch (psi), a tear resistance of about 500-600 pounds per linear inch (pli) and a percent elongation of about 400-500, and said polymeric material has a thickness in the range from about 0.5 mm to about 5 mm and is sufficiently durable to have a useful life on the isolation bearing plates selected from the group consisting of a) about 5 years and b) greater than about 5 years.

2. The assembly of claim 1, wherein the solid material comprises a metal.

3. The assembly of claim 1, wherein the polymeric material is effective to enhance the operability of the assembly relative to the assembly without the polymeric material.

4. The assembly of claim 1 which provides at least one of (1) increased operational smoothness, (2) increased operational safety, (3) increased operation efficiency, (4) increased operational reliability, and (5) reduced incidence of bearing assembly failure; each of (1) through (5) being relative to a substantially identical bearing assembly without the polymeric material.

5. The assembly of claim 1, wherein the polymeric material consists essentially of a 100% polyurea polymer.

6. The assembly of claim 1, wherein the first and second isolation barrier plates each includes a roughened or textured surface on which the polymeric material is located.

7. The assembly of claim 1, wherein the first and second isolation bearing plates each includes a sandblasted surface on which the polymeric material is located.

8. The assembly of claim 1, wherein at least one of the first and second bearing plates includes a surface facing the moveable bearing element which varies in at least one of angle and curvature over the extent of the surface.

9. The assembly of claim 1, wherein at least one of the first and second bearing plates includes a first surface portion which is substantially linear in a vertical plane passing through the center of the bearing plate.

10. The assembly of claim 1, wherein at least one of the first and second bearing plates includes a first surface portion which is curved in a vertical plane passing through the center of the bearing plate.

11. The assembly of claim 1, wherein at least one of the first and second bearing plates includes a first surface portion which is substantially linear in a vertical plane passing through the center of the bearing plate, and a second surface portion which is curved in a vertical plane passing through the center of the bearing plate.

12. The assembly of claim 1, wherein the first and second isolation bearing plates each have an outer polygonal periphery; include a recessed hardened load-bearing surface component; and a hardened frame component sufficiently strong to support the recessed hardened load-bearing surface component.

13. The assembly of claim 12, wherein said frame component is welded to said load-bearing surface component.

14. The assembly of claim 13, wherein the load-bearing surface component has a cross sectional profile in a vertical plane passing through the center of the load-bearing surface component comprising a shape selected from the group consisting of: i) a combination of linear and curved shapes; ii) a combination of different linear shapes; and iii) a combination of different curved shapes.

15. The assembly of claim 12, wherein the polygonal periphery is an octagonal periphery.

16. The assembly of claim 12, wherein the frame component comprises a series of holes useful in joining the frame component to at least one other component of said isolation platform or flooring system.

17. The assembly of claim 16, wherein the at least one other component is selected from the group consisting of: i) another isolation bearing plate; ii) a connecting component; iii) a frame element of said isolation platform or flooring system; and iv) a floor or foundation.

18. The assembly of claim 12, wherein said load bearing surface component has a substantially circular shape in a top view.

19. The assembly of claim 12, wherein said load bearing surface component has a substantially polygonal shape in a top view.

20. A seismic isolation bearing assembly comprising: a first isolation bearing plate; a second isolation bearing plate; and a moveable bearing element disposed between the first and second isolation bearing plates, wherein at least one of the first and second isolation plates comprises a solid material and a surface facing the other isolation plate comprising a coating from about 0.5 mm to about 5 mm thick comprising a polymeric material different from and bonded to the solid material of said at least one of the first and second isolation plates, wherein the polymeric material comprises a polyurea polymer, said polyurea polymer having a hardness (Shore D) of about 45-55, a tensile strength of about 2800-3200 pounds per square inch (psi), a tear resistance of about 500-600 pounds per linear inch (pli) and a percent elongation of about 400-500.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows one example of a finished polygonal (octagonal) isolation bearing plate of the present invention.

(2) FIG. 2 shows an intermediate stage in the fabrication of the polygonal (octagonal) isolation bearing plate of FIG. 1, showing certain of the components.

(3) FIG. 3 shows a cross sectional view of a polygonal (octagonal) isolation bearing plate of FIG. 1.

(4) FIG. 3A is an enlarged cross-sectional view of a portion of the isolation bearing plate, shown as 3A in FIG. 3, showing this portion of the isolation bearing plate in more detail.

(5) FIG. 4 is a block diagram setting forth steps to provide the isolation bearing plate of FIGS. 3 and 3A in accordance with the present invention.

(6) FIG. 5 is a diagram of one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

(7) Referring now to the drawings, FIG. 1 shows one example of a finished polygonal bearing plate of the present invention, showing rear fastener holes, while FIG. 2 shows the load-bearing surfaces of the same bearing plate. FIG. 3 is a cross section of the bearing plate of FIG. 1.

(8) In this example, the load-bearing surface component 100 is preferably fashioned from a metal (such as stainless steel) as a circular, symmetrical item, having a central area 102 comprising a radius in cross section; see FIG. 3. Surrounding this central area is a annular area comprising a region of constant slope 104. The bearing surface in this example is drilled and tapped with screw holes 106 for later securing of the bearing plate to an underlying or overlaying surface, if desired. The load-bearing surface 100 is welded to a circular steel band 110 and a flat bottom plate 112; this assembly is then joined, for example welded, to a frame component 114 comprising lengths of a hardened material (cold rolled steel (CRS) in this case) formed, for example, by welding, into an octagon. As shown, each side of the frame is drilled and tapped 118 for joining to, for example, framing or connector components or other bearing plates with screws or bolts.

(9) The assembly shown in FIG. 2 comprises eight spaces 116 (appearing substantially as triangles in the two dimensional top view of FIG. 2) between the steel band 110 and the frame component 114. Filler pieces of metal are then welded to the assembly to fill in the spaces.

(10) As shown in FIGS. 3 and 3A, load bearing surface 100 includes a sandblasted upper surface 130 which is coated with a polyurea top coating 140.

(11) This structure is produced by sandblasting the upper (top) portion 120 of at least the load bearing surface 100 so that the resulting sandblasted surface 130 is roughened. See FIG. 3A. When a polyurea composition is applied to this roughened surface, for example, as a liquid, dry, or flowable material, the polyurea material 140, after being allowed to cure, set or solidify, as in the form of a film or layer and securely adheres to or is held to the roughened surface 130. The film or layer of polyurea material may be slightly sticky or tacky.

(12) The polyurea material film or layer 140 is sufficiently thick to be wear resistant and to remain in place and effective, for example, to avoid or reduce sliding, skidding and/or stopping of the rolling member which is placed between bearing surface 100 and a complementary bearing facing the upper surface (140) of bearing 100. As noted elsewhere in this application, reducing or eliminating such skidding and/or stopping, provides substantial advantages.

(13) In other examples surfaces other than the load-bearing surfaces alone of the seismic isolation bearing may be coated with the polymeric coating. For example, the entire seismic isolation bearing may be so coated.

(14) For example, the entire isolation bearing may be sandblasted, then with a polyuria coating.

(15) The coating may be applied by spraying the polymer onto the surface, for example, onto a sandblasted surface. An advantage of polyurea polymers such as the two-component isocyanate/resin polyurea system sold as Rhino Extreme, 11-50 GT. The isocyanate and resin are sprayed using high pressure plural component spray equipment. The coating is 100% solids, no VOC's and no solvents, is chemically resistant, and has high tensile, tear, and elongation properties. It has a hardness (Shore D) of about 45 to 55, tensile strength of about 2800-3200 psi, tear resistance of about 500-600 pli, and a percent elongation of about 400-500.

(16) FIG. 4 is a block diagram setting forth steps to provide the isolation bearing plate of FIGS. 3 and 3A in accordance with the present invention.

(17) FIG. 5 shows one embodiment of the present invention. This embodiment depicts a substantially flat, generally planar lower pan segment 201 having a first side, and a second side opposite the first side having at least two upward facing recesses 203. A substantially flat, generally planar upper pan segment 205 has a first side, and a second side opposite the first side having at least two downward-facing recesses structured to oppose the upward-facing recesses 203. The opposing recesses are aligned to define at least two cavities therebetween, each cavity containing at least one rigid ball 207 rollably supporting the upper pan segment 205 upon the lower pan segment 201. A cross-section passing through the center of at least one recess defines a line along the surface of the recess comprising a combination of shapes selected from the group consisting of: i) a straight line and a curve, ii) a first curve and a second curve different from the first curve, and iii) a first straight line and a second straight line having a different slope than the first straight line. Each such isolation platform is structured to be linked to at least one additional isolation platform using a plurality of rigid connecting members 209 linking contiguous upper pan segments 205 and contiguous lower pan segments 201.

(18) The first and second isolation bearing plates are provided. Such plates can be conventional in size, shape and structure. Such plates are often made of hardened materials, such as steel and/or other metals.

(19) The load bearing surfaces of each of the first and second isolation bearing plates are sandblasted, or otherwise roughened, so that a coating can be placed on, and remain on, the load bearing surfaces of the isolation bearing plates. After such surface treatment/preparation, the load bearing surfaces of both the first and second isolation bearing plates are contacted with a polymeric material, such as polyurea, to form a coating of the polymer on the load bearing surfaces of the first and second isolation bearing plates.

(20) The first and second isolation bearing plates are assembled with a bearing member, e.g., ball, roller and the like, therebetween so that the bearing member comes into contact with the coating on the first and second isolation bearing plates, thereby reducing skidding and/or stopping of the ball or roller during operation. Such reduced skidding and/or stopping during operation results in improved operational efficiencies of the seismic isolation bearing assembly. Put another way, placing a polymeric coating on load-bearing surfaces of the first and second bearing plates, in accordance with the present invention, provides substantial benefits with regard to the operation of the seismic isolation bearing assembly relative to such an assembly without the polymeric coating on the first and second bearing plates.

(21) The surface treatment or roughening, e.g., sandblasting, of the load bearing surfaces is effective in holding or maintaining the polymeric material coatings in place on the first and second bearing plates so that the coatings are maintained on the load bearing surfaces and are effective for longer periods of time to improve the operation of the assembly.

(22) Although the foregoing invention has been exemplified and otherwise described in detail for purposes of clarity of understanding, it will be clear that modifications, substitutions, and rearrangements to the explicit descriptions may be practiced within the scope of the appended claims. For example, the inventions described in this specification can be practiced within elements of, or in combination with, other any features, elements, methods or structures described herein. Additionally, features illustrated herein as being present in a particular example are intended, in other aspects of the present invention, to be explicitly lacking from the invention, or combinable with features described elsewhere in this patent application, in a manner not otherwise illustrated in this patent application or present in that particular example. The language of the claims shall solely define the invention. All publications and patent documents cited herein are hereby incorporated by reference in their entirety for all purposes to the same extent as if each were so individually denoted.