Static structures (e.g. – buildings) – Means compensating earth-transmitted force – Relative motion means between a structure and its foundation
Patent
1988-08-15
1989-12-19
Safavi, Michael
Static structures (e.g., buildings)
Means compensating earth-transmitted force
Relative motion means between a structure and its foundation
248562, 248636, 248638, E04H 902, E04B 198
Patent
active
048873985
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a hydraulic buffer, filled with a compound that behaves like a liquid to a certain extent, mounted beneath the foundations of buildings and other structures in order to absorb the shocks of severe earthquakes.
SUMMARY OF THE INVENTION
The buffer according to the invention has an envelope made of flexible material, preferably rubber and preferably reinforced by any fabric, and formed with two parallel circular plate portions, separated by a layer of a compound with a liquid behaviour. The circular portions are connected to each other along their circumferences by a hollow torus, in such a way that the interior of the torus and the space between the circular plate portions communicate freely when the torus is mounted with its axis upright. The circular plate portions of flexible material are supported or backed by discs made from any rigid material like steel or aluminum, or by a square concrete plate. When the torus rests on a smooth surface, the lower rigid disc can be omitted in most cases. Furthermore, the envelope is provided with two access nipples, one for introducing the liquid-like compound and the other for venting purposes during filling of the buffer by a special filling device. Each nipple has a shutoff valve (not shown).
The number of buffers, the allowable load, and the hydrostatic pressure inside the buffer depend on the weight of the building under consideration, the construction of the foundation, and the energy absorption capability of the ground beneath the foundation.
The width of the torus should be selected such that the allowable amplitude of ground displacement shall be in accordance with local earthquake design specifications. Although the force shall be assumed to act in any horizontal direction, in most cases horizontal and vertical forces are acting simultaneously. For that reason the design shall also meet the requirement for fluctuating vertical load.
Since in several regulations for earthquake sensitive regions the maximum acting ground displacement is assumed at ninety centimeters, the torus should have at least the same width. In some cases it will be advisable that the buffers for a building or other structure be hydraulically connected to equalize the hydrostatic pressure during and/or after earthquakes. This is especially an advantage when permanent displacements remain.
It is an object of the invention to provide a safety device to protect buildings and other structures from damage and collapse during earthquakes that often result in disasters at the cost of many victims and much money.
The advantage of the invention when it is compared with existing safety devices, serving the same purpose and already known, are the uniform load, the large range of allowable ground displacement, the extremely low forces in the flexible parts of the buffer, resulting in a long rated life, a low resistance of the torus against the acting ground displacements during earthquakes, the self level adjusting capability, and the simplicity of the design.
BRIEF DESCRIPTION OF THE DRAWINGS
One embodiment of the invention will be explained, by way of example, with reference to the accompanying drawing, in which
FIG. 1 is an elevation view, in cross section, of the hydraulic buffer assembly,
FIG. 2 represents a detail, at an enlarged scale, of a portion of the hydraulic buffer, and
FIG. 3 is a detail of one of the access nipples.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
With reference to the figures, the preferred embodiment of the hydraulic buffer includes an impervious envelope 13 made of flexible material. The material is preferably rubber or rubber-like. Desirably, the torus is reinforced by metal wire or bars, radially inserted in the flexible material, in such a way that the final flexibility is not affected by the reinforcement. The envelope includes a first circular upper plate portion 1 and a second circular base plate portion 2 spaced from and coaxial with the first circular portion. A hollow torus 5 coaxially surrounds
REFERENCES:
patent: 3137466 (1964-06-01), Rasmussen
patent: 3141523 (1964-07-01), Dickie
patent: 4262886 (1981-04-01), De Salva et al.
patent: 4434382 (1984-02-01), Patel et al.
patent: 4492366 (1985-01-01), Ozawa et al.
patent: 4553744 (1985-11-01), Konishi et al.
patent: 4682753 (1987-07-01), Clark
patent: 4756513 (1988-07-01), Carlson et al.
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