Contact: John Blair, john.blair@nist.gov
FOR IMMEDIATE RELEASE NIST 97-06
Mar. 3, 1997
Contact: John Blair NEW GUIDELINES MAY SOON
(301) 975-4261 MEAN MORE BUILDINGS
john.blair@nist.gov PROTECTED BY EARTHQUAKE
SHOCK ABSORBERS
Slide to the left, slide to the right and don't fall down. No, it's
not a new dance, but a building with shock absorbers--a feature that
could someday save more lives and property in earthquake-prone regions
of the United States. Researchers at the Commerce Department's National
Institute of Standards and Technology have taken the first step toward
making it easier for the construction industry to include these shock
absorbers, more commonly called seismic base isolation systems, in their
building plans. The agency's Building and Fire Research Laboratory has
developed testing guidelines for the devices that can be the basis for
standards of reliability and capacity. Seismic base isolation systems,
generally designed to protect structures of fewer than 10 stories from
the dangerous effects of strong ground shaking, isolate a structure from
the moving ground by inserting a flexible rubber layer, or teflon-steel
sliding interface, at or near the structure's foundation. The interface
isolates the shaking of the ground from the shaking of the structure,
and minimizes damage to the structure.
Many base isolators have been used in bridges. They also have been
used for fire stations, emergency command centers, liquid storage tanks
and historically significant buildings. For example, the 1994 renovation
of the historic U.S. Court of Appeals building in San Francisco included
the installation of 256 sliding base isolation bearings.
Up until now, these devices had to be custom designed for each site
and individually tested. No general testing standard existed.
"That's about to change," says BFRL structural engineer Andrew
Taylor. "New testing standards, based on NIST guidelines, will provide
comparable data on different systems and components and will define
minimum levels of reliability and capacity. These tests will make it
easier for engineers and the industry to market these devices. For the
first time, the sale of "off-the-shelf" seismic base isolation systems
could become a possibility."
NIST structural engineers developed the guidelines with extensive
industry collaboration, as part of the BFRL's participation in the
National Earthquake Hazard Reduction Program. The guidelines can be used
to conduct pre-qualification, prototype and quality control tests of
elastomeric, sliding or hybrid isolation systems. They include general
requirements of the test facility, instrumentation, calibration, data
acquisition, data analysis and reporting of results.
The American Society of Civil Engineers is currently reviewing the
guidelines. ASCE approval of testing standards for seismic base
isolation systems, based on the NIST guidelines, is expected by the end
of the year.
For technical information, contact Andrew W. Taylor, Rm. B158
Building Research Bldg., NIST, Gaithersburg, Md. 20899-0001,
(301) 975-6078, e-mail: andrew.taylor@nist.gov.
A non-regulatory agency of the Commerce Department's Technology
Administration, NIST promotes U.S. economic growth by working with
industry to develop and apply technology, measurements and standards.
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