‘Smart’ Shock Absorbers Take the Quake
To envision what a building undergoes in an earthquake, Satish Nagarajaiah suggests imagining yourself standing in a moving bus or train.
“Riders make their bodies and muscles tense when the bus moves, and they relax as soon as the sudden motion stops,” said Nagarajaiah, professor in civil and environmental engineering and in mechanical engineering and materials science. “The typical steel-framed building or bridge can’t do that, but we want to find technologies like adaptive stiffness and damping systems that can give structures that ability.”
About 100 U.S. buildings and bridges — including the famed Golden Gate Bridge — have been built or are being retrofitted with large, passive dampers that use pistons and hydraulic fluid to absorb the impact of sudden shocks the way that shock absorbers do in a car. But passive dampers are designed to perform the same way in every earthquake, and as quake researchers have discovered in recent years, not all quakes are created equal. The 1994 Northridge earthquake in California, the 1995 Kobe earthquake in Japan, the 1999 Chi Chi earthquake in Taiwan and the 2008 Sichuan earthquake in China are each examples of quakes that delivered a massive initial shockwave that was particularly damaging for structures near the epicenter.
“Our aim is to create smart structures that can sense what kind of shock is arriving and react with the best possible strategy to minimize damage,” said Nagarajaiah, principal investigator on the project, which is funded by $1.6 million from the National Science Foundation. Nagarajaiah’s past research on smart structures and structural control for seismic protection has led to quake-protection systems that have been implemented in China and Japan.Learn more:
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