How do bridges withstand earthquakes, hurricanes?

Careful design is required to create bridges that withstand extreme weather such as earthquakes and hurricanes.

It's one reason many bridges today are made of steel and concrete, AccuWeather explains.

Bridge designers continue to improve upon their methods to increase resiliency, and modern bridges incorporate back-up systems. Engineers have developed sturdier bridges by testing existing bridges during extreme weather and by using computer models.

For example, when at least a dozen bridges buckled from a deadly earthquake in 1971, California changed their bridge design.

"After that happened, if you drive around California and look under the bridges, there are metal restrainer cables tying the bridges down to the support piers so they can't fall off like they did," Dr. Michael Chajes, professor of civil and environmental engineering at the University of Delaware, told AccuWeather. "We also saw a lot of columns fail (during that earthquake), because we didn't understand at that point the effects that earthquakes would have on them."

In the rare event that a bridge collapses, it could be due to a flaw in either the design or the construction. It could also happen when an older bridge built to previous standards is not properly maintained.

Learn more on AccuWeather's site.
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