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DIS
Seismic Isolater
The Need
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As an earthquake protection technology to the
specific needs and requirements for flexible structures, energy dissipation products are
installed in the structural frame and wall and will reduce interstory drift cause by
earthquakes. Dampers are introduced into structures in order to absorb much of the kinetic
energy created by wind, mild tremors as well as major seismic events. |
Seismic testing equipment
at the Energy Technology Engineering
Center in California. |
The Technology
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Seismic isolation bearings isolate a
structure from the ground motion produced by an earthquake. The energy absorption devices
are designed to absorb the energy associated with an earthquake. This seismic (Base)
Isolator consists of alternate layers of rubber and steel bonded together, with a cylinder
of pure lead tightly inserted through a hole in the middle. The rubber layers allow the
isolator to easily displace sideways, reducing the earthquake loads felt by the building
and its occupants. They also act as a spring, ensuring that the structure returns to its
original position after the shaking has stopped. |
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| By bonding the rubber to thin layers
of steel, the isolator becomes much stiffer under vertical loads so that the structure
will not move up and down during day-to-day use. Thick steel plates are bonded to the top and bottom surfaces to allow the
isolator to be solidly bolted to the structure above and to the foundation below. The
isolator lead core stops the structure from moving sideways under wind and other
non-seismic loads. During earthquake events, the lead is pushed sideways by the rubber and
steel layers absorbing a portion of the earthquake energy. This dampening affect helps to
further reduce the earthquake forces and help control the lateral displacement of the
structure. |
< Energy
Dissipation vs. Without Energy Dissipation > |
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| With Energy Dissipation |
Without
Energy Dissipation |
| Inter-story drift is
reduced by a factor of approximately two with the installation of energy dissipaters. |
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| < Seismic
Isolation vs. Without Seismic Isolation > |
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Seismically
Isolated Structure |
Conventional
Structure |
| The deformation pattern of
an isolated structure during an earthquake. Movement takes place at the level of the
isolators. Floor accelerations are low; the building, its occupants and loose contents are
safe. |
The deformation pattern of
a conventional structure during an earthquake. Accelerations of the ground are amplified
on the higher floors and the loose contents are damaged. Building deformations and
distortions could be permanent. |
The Benefits
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Pioneered by DIS Inc., seismic (base) isolation
reduces ground motions transmitted into structures. By isolating the effect of earthquakes
through state-of-the-art "shock absorbers", this technology can reduce the
effects of seismic forces up to eight times over, helping to not only ensure the survival
of the structure, but its ability to function afterwards without interruption to business. |
Status
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There are now 400 structures by seismic
isolation in 17 countries. 115 are in U.S. In new six story building at the Martin Luther
King/Drew Medical center in Los Angeles, California, DIS fabricated the largest High
Damping Rubber (HDR) isolators used to date, in U.S. At 40" in diameter and 20"
high, each unit weighs nearly two tons with attachment plates. Seventy isolators make this
one of the largest installed systems in U.S. |
Points of Contact
- DIS Inc., 3470 Mt. Diablo Blvd., Suite A200 Lafayette, CA
Tel (925) 283-1166 Fax (925) 283-4307. <www.dis-inc.com>
- Mr. Michael S. Higgins, Highway Innovative Technology
Evaluation Center (HITEC), Tel (202) 842-0555, <mshiggins@cerf.org>
References
- Civil Engineering Research Foundation, Highway Innovative
Technology Evaluation Center (HITEC) <http://www.cerf.org/hitec/eval/ongoing/seismic.htm>
- Dynamic Isolation System, Inc. <http://www.dis-inc.com/technolo.htm>
- HITEC, Civil Engineering Research Foundation (CERF),
Evaluation Findings for DIS, Inc., Elastomeric Bearings, CERF Report : Hitec 98-06. Sept.
1998. Product 5.
Disclaimer Statement
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Neither the Construction
Industry Institute nor Purdue University in any way endorses this
technology or represents
that the information presented can be relied upon without further investigation. |
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