CA2157942A1 - Sealed pressure seismic isolator - Google Patents
Sealed pressure seismic isolatorInfo
- Publication number
- CA2157942A1 CA2157942A1 CA002157942A CA2157942A CA2157942A1 CA 2157942 A1 CA2157942 A1 CA 2157942A1 CA 002157942 A CA002157942 A CA 002157942A CA 2157942 A CA2157942 A CA 2157942A CA 2157942 A1 CA2157942 A1 CA 2157942A1
- Authority
- CA
- Canada
- Prior art keywords
- isolator
- pressure
- gallery
- chambers
- seismic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04H—BUILDINGS OR LIKE STRUCTURES FOR PARTICULAR PURPOSES; SWIMMING OR SPLASH BATHS OR POOLS; MASTS; FENCING; TENTS OR CANOPIES, IN GENERAL
- E04H9/00—Buildings, groups of buildings or shelters adapted to withstand or provide protection against abnormal external influences, e.g. war-like action, earthquake or extreme climate
- E04H9/02—Buildings, groups of buildings or shelters adapted to withstand or provide protection against abnormal external influences, e.g. war-like action, earthquake or extreme climate withstanding earthquake or sinking of ground
- E04H9/021—Bearing, supporting or connecting constructions specially adapted for such buildings
- E04H9/0235—Anti-seismic devices with hydraulic or pneumatic damping
Abstract
A device-for seismic isolation is invented by the use of sealed hydrostatic uplift pressure to reduce the loads of a building, structure, or heavy equipment. After the reduced frictional force is overcome the structure undergoes horizontal sliding motions, thereby reducing the seismic induced stresses. The present invention is economical and suitable for all types of buildings, ranging from family homes to power generation stations. It utilizes the space between the Upper and Lower Foundation Mats by dividing it into pressure chambers, fitting the mats with bearing plates, sealing the chambers off, and then pressurizing them by elevated liquid tanks or compressed gas cylinders. Pressure chambers may be allocated underneath asymmetric heavy weights for reducing the danger of excessive torsional in-plane rotation of the Upper Foundation Mat under earthquake. The momentary compression and de-compression of the pressure chambers would regulate the net structural load, thereby counteracting both the main and localized vertical shocks. The reliability and low cost of the present invention will enable seismic isolation to become an affordable household safety feature for people dwelling in high-seismic areas.
Description
~1~7~2 SEALED ~kS:~u~ SE:ISMIC ISOLATOR
The invention presented herein is a device for lessening the destructive forces transmittable to buildings, structures, or heavy equipment during earthquakes. The outstanding features of the device are in its simplicity, versatility, reliability, low costs, and being virtually maintenance-free.
It is suitable to be used for practically all types of buildings, including family homes, commercial and apartment buildings, and power generation stations.
As in all existing seismic isolation schemes, a super-structure is founded on an Upper Foundation Mat. The Sealed Pressure Seismic Isolator works by sealing of f the Isolator Gallery, which is the space between the Upper and Lower Foundation Mats, and then pressurizing it. The net uplift pressure reduces the downward loads and, in turn, the frictional forces at the base plates.
In the drawings which illustrate ~ ts of the invention, Figures 1 and 2 illustrate the setup for a family home and for an industrial plant, respectively. Figures 3, 4 and 5 show a variety of base att~, L.
In Figure 1, the house is founded on the Upper Foundation Mat 1, and then onto the Exterior Curtain Wall 2 which .
encloses the entire Isolator Gallery and is anchored to the Short Base Plate 4. The Long Base Plate 5 is supported by the Lower Foundation Mat 6 which may have a water-proof surface or cover.
A Pressure Seal 3 is attached to the Short Base Plate to seal off the gap from the Long Base Plate. This Seal comprises a pressurizing hose which, when inf lated, undergoes a vertical expansion and presses against the rubber seal. Interior walls or pillars 7 are added where required.
In Figure 2, the Isolator Gallery of an industrial plant is shown to be compartmentalized into pressure chambers, with the high water pressure at the central zone 1 being stepped down to a medium-low pressure zone. Interior curtain walls 5 enclose the entire central zone. Water at atmospheric pressure is maintained outside the exterior curtain walls 6, which enclose the edges of the foundation mat, thereby forming a natural pressure seal to the pres6urized system.
The non-symmetric heavy load situated directly above zone 2 in Figure 2 is counteracted by a medium-high pressure zone 2.
The aim is to brin~ the net weight in zone 2 down to a value similar to that found in zone 3. This is an important feature of the present invention. It reduces the torsional in-plane rotation of the Upper Foundation Mat as augmented by asymmetric ~7942 loads . SUCh 21 roiation causes excessive displ ~, at the corners of the mat and often leads to failure.
Figures 3, 4 and 5 identify different att~ Ls at the base plates. In Figure 3, an rubber pad 6 is embedded in between the Short Base Plate 4 and the Long Base Plate 5 to increase the resilience in the vertical direction. Pressure Seal 3 is affixed to Base Plate 4.
In Figure 4, a group of hard or flexible rollers 6 are inserted between the base plates 4 and 5, thereby reducing further the frictional force. The use of ball-bearing rollers under dynamic seismic condition is acceptable when the structural weights have already been reduced by the uplifting, sealed pressures.
In Figure 5, a rubber pad 6 is cdded in an assembly formed by a pair of Short Base Plates 4. A group of rollers 7 is inserted above the ~ong Base Plate 5. This system has added resilience for attenuating vertical shocks, and has extra low frictional force to facilitate ~i Ls in the horizontal direction .
Pressurization of the sealed pressure chambers may be achieved by elevated water tanks, as shown in Figures 1 and 2, and/or by cylinders of compressed air, all connected to the i ~I5~9~2 Isolator Gallery.
Pressurization may al90 be designed to be triggered by the initial motions of an earthquake, which as a rule requires a few seconds before reaching its destructive peak motion.
These initial motions can activate a motor or valve, or possibly a detonation of a small charge, all for the purpose of allowing water to flow from the tanks to the Isolator Gallery.
Nominally low pressures only, even at zero value, may then be maintained on a regular basis at the underside of the Upper Foundation Mat. This will lessen leakage, if any, in the ple62~uLized system.
Even without such automatic activation devices, the full hydrostatic pressure required for constant seismic isolation is merely 4 to 8 psig, which is low comparing even to the ordinary household water supply at the 50 to 60 psig range. Leakage, if any, will be negligible.
~ ince maintenance is hardly re~uired, the Isolator Gallery for homes and ordinary buildings may be reduced in height to a crawl-space, or less, for further savings.
In a sealed pressure system, the pressurizing f luid may be water, gas, any other liquid, or any cornbination thereof.
Also, all Long Base Plates may be attached to the top of the ~ 7g~2 Lower Foundation Mat, or attached to the bottom oi~ the Upper Foundation Mat, as desired.
The use of the present invention eliminates the need for expensive alternatives such as the Elastomeric Bearings with low-friction sliding plates as used by the French for the Roeberg Nuclear Plants in South Africa.
The Koeberg-type low frictional force is readily and ;nPl~rpnF:ively achieved by the present invention. With the structural weights being reduced by the uplifts at the pressure chambers, the resulting frictional forces at the base plates will be equivalent to those produced by the full weight under a low coefficient of friction.
The present invention is based on the physical fact that in a seismically isolated system it is the base shear, not the structural mass, which detprmi neR the dynamic response. An earthquake simply cannot transmit more force to a structure than through the base shear, which is the friction force itself. Therefore, there exists a one-to-one correlation between the effective friction force and the horizontal seismic dynamic force transmittable to the superstructure, regardless of mass.
The pressuri~ed chambers will also act as giant shock ~ 79~2 ab~orbers for seismic vibrations in the vertical direction.
Downward shocks would cause bleeding of the pressurized liquid and a momentary increase of the sealed uplift pressures, which cancel out the downward shock. Likewise, upward shocks would create a partial vacuum or momentary de-pressurization, which restores the weight and thereby cancels out the vertical acceleration .
Non-uniform horizontal translations would still occur in a symmetrical plant layout, as asymmetric loads would result from overturning or rocking motions caused by shocks in the orthogonal horizontal direction. The present invention, being self-ad~usting for vertical shocks, safely resolves this major and thorny problem.
For achieving a low, basic friction for use with the present invention, base plates may be made of low friction material such as graphite, bronze, oxide-filmed steel, or steel plates lubricated by powered mica, etc.
The distinguishing features of the Sealed Pressure Seismic Isolator may be summarized as follows:
1) Attenuating Horizontal Vibrations. The upward pressures exerted by the pressure chambers reduce the downward loads, effectively achieving an equivalence of a low friction 3~
coefficient at the bearing plates.
2) Being effective for earthquakes of all magnitudes. It may start from a ground horizontal motion of 596 g (gravitational acceleration) or lower. In contrastr the low-friction steel plates start to function only at a 20~ g, at which point most homes would have collapsed.
3 ) Low Costs . They are merely small fraction6 of those of low-friction plates. This enables seismic isolation to become an affordable household feature.
The invention presented herein is a device for lessening the destructive forces transmittable to buildings, structures, or heavy equipment during earthquakes. The outstanding features of the device are in its simplicity, versatility, reliability, low costs, and being virtually maintenance-free.
It is suitable to be used for practically all types of buildings, including family homes, commercial and apartment buildings, and power generation stations.
As in all existing seismic isolation schemes, a super-structure is founded on an Upper Foundation Mat. The Sealed Pressure Seismic Isolator works by sealing of f the Isolator Gallery, which is the space between the Upper and Lower Foundation Mats, and then pressurizing it. The net uplift pressure reduces the downward loads and, in turn, the frictional forces at the base plates.
In the drawings which illustrate ~ ts of the invention, Figures 1 and 2 illustrate the setup for a family home and for an industrial plant, respectively. Figures 3, 4 and 5 show a variety of base att~, L.
In Figure 1, the house is founded on the Upper Foundation Mat 1, and then onto the Exterior Curtain Wall 2 which .
encloses the entire Isolator Gallery and is anchored to the Short Base Plate 4. The Long Base Plate 5 is supported by the Lower Foundation Mat 6 which may have a water-proof surface or cover.
A Pressure Seal 3 is attached to the Short Base Plate to seal off the gap from the Long Base Plate. This Seal comprises a pressurizing hose which, when inf lated, undergoes a vertical expansion and presses against the rubber seal. Interior walls or pillars 7 are added where required.
In Figure 2, the Isolator Gallery of an industrial plant is shown to be compartmentalized into pressure chambers, with the high water pressure at the central zone 1 being stepped down to a medium-low pressure zone. Interior curtain walls 5 enclose the entire central zone. Water at atmospheric pressure is maintained outside the exterior curtain walls 6, which enclose the edges of the foundation mat, thereby forming a natural pressure seal to the pres6urized system.
The non-symmetric heavy load situated directly above zone 2 in Figure 2 is counteracted by a medium-high pressure zone 2.
The aim is to brin~ the net weight in zone 2 down to a value similar to that found in zone 3. This is an important feature of the present invention. It reduces the torsional in-plane rotation of the Upper Foundation Mat as augmented by asymmetric ~7942 loads . SUCh 21 roiation causes excessive displ ~, at the corners of the mat and often leads to failure.
Figures 3, 4 and 5 identify different att~ Ls at the base plates. In Figure 3, an rubber pad 6 is embedded in between the Short Base Plate 4 and the Long Base Plate 5 to increase the resilience in the vertical direction. Pressure Seal 3 is affixed to Base Plate 4.
In Figure 4, a group of hard or flexible rollers 6 are inserted between the base plates 4 and 5, thereby reducing further the frictional force. The use of ball-bearing rollers under dynamic seismic condition is acceptable when the structural weights have already been reduced by the uplifting, sealed pressures.
In Figure 5, a rubber pad 6 is cdded in an assembly formed by a pair of Short Base Plates 4. A group of rollers 7 is inserted above the ~ong Base Plate 5. This system has added resilience for attenuating vertical shocks, and has extra low frictional force to facilitate ~i Ls in the horizontal direction .
Pressurization of the sealed pressure chambers may be achieved by elevated water tanks, as shown in Figures 1 and 2, and/or by cylinders of compressed air, all connected to the i ~I5~9~2 Isolator Gallery.
Pressurization may al90 be designed to be triggered by the initial motions of an earthquake, which as a rule requires a few seconds before reaching its destructive peak motion.
These initial motions can activate a motor or valve, or possibly a detonation of a small charge, all for the purpose of allowing water to flow from the tanks to the Isolator Gallery.
Nominally low pressures only, even at zero value, may then be maintained on a regular basis at the underside of the Upper Foundation Mat. This will lessen leakage, if any, in the ple62~uLized system.
Even without such automatic activation devices, the full hydrostatic pressure required for constant seismic isolation is merely 4 to 8 psig, which is low comparing even to the ordinary household water supply at the 50 to 60 psig range. Leakage, if any, will be negligible.
~ ince maintenance is hardly re~uired, the Isolator Gallery for homes and ordinary buildings may be reduced in height to a crawl-space, or less, for further savings.
In a sealed pressure system, the pressurizing f luid may be water, gas, any other liquid, or any cornbination thereof.
Also, all Long Base Plates may be attached to the top of the ~ 7g~2 Lower Foundation Mat, or attached to the bottom oi~ the Upper Foundation Mat, as desired.
The use of the present invention eliminates the need for expensive alternatives such as the Elastomeric Bearings with low-friction sliding plates as used by the French for the Roeberg Nuclear Plants in South Africa.
The Koeberg-type low frictional force is readily and ;nPl~rpnF:ively achieved by the present invention. With the structural weights being reduced by the uplifts at the pressure chambers, the resulting frictional forces at the base plates will be equivalent to those produced by the full weight under a low coefficient of friction.
The present invention is based on the physical fact that in a seismically isolated system it is the base shear, not the structural mass, which detprmi neR the dynamic response. An earthquake simply cannot transmit more force to a structure than through the base shear, which is the friction force itself. Therefore, there exists a one-to-one correlation between the effective friction force and the horizontal seismic dynamic force transmittable to the superstructure, regardless of mass.
The pressuri~ed chambers will also act as giant shock ~ 79~2 ab~orbers for seismic vibrations in the vertical direction.
Downward shocks would cause bleeding of the pressurized liquid and a momentary increase of the sealed uplift pressures, which cancel out the downward shock. Likewise, upward shocks would create a partial vacuum or momentary de-pressurization, which restores the weight and thereby cancels out the vertical acceleration .
Non-uniform horizontal translations would still occur in a symmetrical plant layout, as asymmetric loads would result from overturning or rocking motions caused by shocks in the orthogonal horizontal direction. The present invention, being self-ad~usting for vertical shocks, safely resolves this major and thorny problem.
For achieving a low, basic friction for use with the present invention, base plates may be made of low friction material such as graphite, bronze, oxide-filmed steel, or steel plates lubricated by powered mica, etc.
The distinguishing features of the Sealed Pressure Seismic Isolator may be summarized as follows:
1) Attenuating Horizontal Vibrations. The upward pressures exerted by the pressure chambers reduce the downward loads, effectively achieving an equivalence of a low friction 3~
coefficient at the bearing plates.
2) Being effective for earthquakes of all magnitudes. It may start from a ground horizontal motion of 596 g (gravitational acceleration) or lower. In contrastr the low-friction steel plates start to function only at a 20~ g, at which point most homes would have collapsed.
3 ) Low Costs . They are merely small fraction6 of those of low-friction plates. This enables seismic isolation to become an affordable household feature.
4 ) Attenuating Vertical Vibrations . The pressure chambers act as shock absorbers f or vertical shocks through momentary pressurization or de-pressurization. It is especially effective for counteracting localized vertical shocks induced by orthogonal rocking motions.
5) Reducing Risks of Torsion in Asymmetric Plants. The upward pressure of a pressurlzed chamber placed underneath an asymmetric heavy weight would reduce the torsional moment produced by the said weight, thus minim; ~ing the dangerous horizontal rotation of the mat.
6) Re-centering of Plant after a Major Earthquake. By a moderate increase of the sealed pressures to counteract most of ~ . ~57~42 the structural weight, re-centering is readily performed through lateral jacking. Without such a re-centering, most of the connecting pipes etc. will be very much failure-prone after being locked in permanently displaced configurations by an earthquake .
7) Safety for After-shocks. Most major earthquakes world-wide had severe after-shocks. A sliding plate seismic isolator may fail in an after-shock, when the Upper Foundation mat has already been badly misplaced and rotated under the main quake. The present invention will avoid such failure through an immediate re-centering.
8) Secure Scheduling. Expensive construction delays are avoided by using the present invention: manufacturers are plentiful; material sources are local; manufacturing processes are simple; special acceptance tests are not required; delivery is immediate; and the installation is straight-forward and does not require special tools.
Claims (9)
1. A system having base plates installed in the Isolator Gallery, i.e., the space in between the Upper and the Lower Foundation Mats, where it is filled with water, air, other fluid, or any combination thereof, and be pressurized above atmospheric pressure, which creates a net upward force for reducing the load of the superstructure transmitting to the base plates and the frictional force actuating therein.
2. A system as defined in claim 1, wherein some rolling device, such as ball-rollers, are inserted in between the base plates to further reduce the frictional force
3. A system as defined in claim 1 or 2, wherein elastomeric pads are added to increase the resilience for attenuating vibrations in the vertical direction.
4. A system as defined in claim 1, 2, or 3, wherein the Isolator Gallery is compartmentalized into pressure chambers, with pressure seals installed to regulate the pressure drops across the chambers.
5. A system as defined in claim 1, 2, 3 or 4, wherein the outermost pressure is created by liquid under atmospheric pressure, acting as a natural seal and damper.
6. A system as defined in claim 1, 2, 3, 4 or 5, wherein the height of the Isolator Gallery may range from zero to a full height suitable for inspection and services.
7. A system as defined in claim 1, 2, 3, 4, 5 or 6, wherein the long base plate of each wall or pillar may be attached to the bottom of the Upper Foundation Mat, or be attached to the top of the Lower Foundation Mat.
8. A system as defined in claim 1, 2, 3, 4, 5, 6 or 7, wherein the Isolator Gallery is regularly under full pressures required for seismic isolation.
9. A system as defined in claim 1, 2, 3, 4, 5, 6 or 7, wherein the full pressures required in the Isolator Gallery for seismic isolation are activated only for the duration of each earthquake.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002157942A CA2157942A1 (en) | 1995-09-11 | 1995-09-11 | Sealed pressure seismic isolator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002157942A CA2157942A1 (en) | 1995-09-11 | 1995-09-11 | Sealed pressure seismic isolator |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2157942A1 true CA2157942A1 (en) | 1997-03-12 |
Family
ID=4156579
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002157942A Abandoned CA2157942A1 (en) | 1995-09-11 | 1995-09-11 | Sealed pressure seismic isolator |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2157942A1 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104818777A (en) * | 2015-04-14 | 2015-08-05 | 王球华 | Frame building avoiding collapse or damage in the case of major earthquakes |
| US9963901B2 (en) * | 2014-02-10 | 2018-05-08 | Takahiro Kanzaki | Seismic isolator |
| CN114486320A (en) * | 2022-04-15 | 2022-05-13 | 中国飞机强度研究所 | Emergency processing system and method for pressure imbalance for aircraft testing |
-
1995
- 1995-09-11 CA CA002157942A patent/CA2157942A1/en not_active Abandoned
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9963901B2 (en) * | 2014-02-10 | 2018-05-08 | Takahiro Kanzaki | Seismic isolator |
| CN104818777A (en) * | 2015-04-14 | 2015-08-05 | 王球华 | Frame building avoiding collapse or damage in the case of major earthquakes |
| CN104818777B (en) * | 2015-04-14 | 2017-07-07 | 王球华 | The not bad Framework Building of no collapsing with strong earthquake |
| CN114486320A (en) * | 2022-04-15 | 2022-05-13 | 中国飞机强度研究所 | Emergency processing system and method for pressure imbalance for aircraft testing |
| CN114486320B (en) * | 2022-04-15 | 2022-06-24 | 中国飞机强度研究所 | Emergency processing system and processing method for pressure imbalance for aircraft testing |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |
Effective date: 20010911 |