Designing Bridges That Stand Up To Quakes

The collapse of an Oakland (Calif.) freeway and heavy damage to bridges during the Loma Prieta earthquake in the San Francisco Bay Area two years ago taught a tragic lesson. Now, a team of engineers at the National Center for Earthquake Engineering Research at the State University of New York at Buffalo and Watson Bowman Acme Corp. of Amherst, N. Y., has developed a system to protect bridges and other structures from quakes.

The technology relies on a construction design called base isolation. When an earthquake strikes, a series of disc bearings and so-called displacement control devices enables the upper structure of the bridge to move a few inches independent of the supporting piers. Acting like complex springs, the system returns the bridge deck to its original position and enables the structure to absorb ground-motion energy.

Project director Michael C. Constantinou, associate professor of civil engineering at SUNY Buffalo, says the new system will allow bridges to be built safely close to earthquake faults. The technology can also be used to retrofit existing bridges.

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