US4226554A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for absorbing dynamic forces on structures
Assignee: Massachusetts Institute of Technology
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Filing: 1978-05-23
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Granted: 1980-10-07
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Expires: 1998-05-23
Abstract
Abstract An apparatus and method is provided for suppressing the dynamic response of structures such as offshore structures to forces, such as that of wind, wave or seismic excitation. A storage tank for liquid with a free surface is positioned on the structure and is designed to have a natural frequency equal to or nearly equal to the natural frequency of the structure. The storage tank containing the liquid reduces the dynamic response of the structure thereby reducing structural degradation such as metal fatique in the structure and increasing the useful life of the structure. The effect of the tank on the motion of the structure is that of a common dynamic absorber.
Inventors
- 👤 John K. Vandiver
- 👤 Shuhei Mitome
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 06:53
CPC Classifications
B; B63; B63B; B63B39/00; B63B39/005; E; E02; E02B; E02B1/00; E02B1/02; E04; E04H; E04H9/00; E04H9/02; E04H9/021; E04H9/0215; F; F16; F16F; F16F7/00; F16F7/10
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
101 words
In a fixed structure that exhibits a dynamic response to wind, water and/or seismic excitation, the improvement which comprises: means for damping said dynamic response comprising a storage tank containing a liquid with a free surface, said storage tank being positioned on and supported by said structure, the shape of said tank and the nature of the liquid being such as to effect a ratio of the uncoupled fundamental mode of the natural frequency of the tank containing liquid to the uncoupled fundamental mode of the natural frequency of the structure and the empty tank of between about 0.8 and 1.1.
Claim 2
Dependent Claim
101 words
In a fixed structure that exhibits a dynamic response to wind, water and/or seismic excitation, the improvement which comprises: means for damping said dynamic response comprising a storage tank containing a liquid with a free surface, said storage tank being positioned on and supported by said structure, the shape of said tank and the nature of the liquid being such as to effect a ratio of the uncoupled fundamental mode of the natural frequency of the tank containing liquid to the uncoupled fundamental mode of the natural frequency of the structure and the empty tank of between about 0.8 and 1.1.
Claim 3
Dependent Claim
17 words
The apparatus of claim 1 wherein said tank includes baffles to define the geometry of said tank.
Claim 4
Dependent Claim
16 words
The apparatus of claim 1 wherein said oscillating structure comprises a platform partially immersed in water.
Claim 5
Dependent Claim
13 words
The apparatus of claim 1 wherein said tank has a rectangular horizontal cross-section.
Claim 6
Independent Claim
101 words
The method for damping the dynamic response of a fixed structure to wind, water and/or seismic excitation which comprises: determining the fundamental mode of the natural frequency of the structure having an empty storage tank for a liquid positioned thereon and regulating the geometry of said tank and the extent to which said tank is filled with a liquid so as to effect a ratio of the uncoupled fundamental mode of the natural frequency of the tank containing liquid to the uncoupled fundamental mode of the natural frequency of the structure and the empty tank of between about 0.8 and 1.1.
Claim 7
Independent Claim
101 words
The method for damping the dynamic response of a fixed structure to wind, water and/or seismic excitation which comprises: determining the fundamental mode of the natural frequency of the structure having an empty storage tank for a liquid positioned thereon and regulating the geometry of said tank and the extent to which said tank is filled with a liquid so as to effect a ratio of the uncoupled fundamental mode of the natural frequency of the tank containing liquid to the uncoupled fundamental mode of the natural frequency of the structure and the empty tank of between about 0.8 and 1.1.
Claim 8
Dependent Claim
19 words
The method of claim 5 wherein the geometry of said tank is regulated with baffles positioned within said tank.
Claim 9
Dependent Claim
14 words
The method of claim 5 wherein said fixed structure is partially immersed in water.
Claim 10
Dependent Claim
19 words
The method of claim 5 wherein the geometry of said tank is regulated to have a rectangular horizontal cross-section.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-10-07 | 1984-04-07 | 1984-10-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-10-07 | 1988-04-07 | 1988-10-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-10-07 | 1992-04-07 | 1992-10-07 | $7700.00 | Window Closed / Lapsed |