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# Earthquake Safe Structures

## Buildings can be made to withstand earthquakes; pipes can be designed to reduce fire hazard after an earthquake.

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Practice Earthquake Safe Structures

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A Better Bridge

### A Better Bridge

Credit: Joe Parks
Source: http://www.flickr.com/photos/parksjd/9687543333

In September 2013, the eastern span of the San Francisco-Oakland Bay Bridge was replaced by a new earthquake resistant bridge. This photo shows the bridge a few days after the new span was put into service and the old span was abandoned.

#### News You Can Use

Credit: CIRonline
Source: http://www.flickr.com/photos/43899883@N03/5572600126

Aftermath of the Loma Prieta earthquake [Figure2]

• People in the San Francisco Bay Area rely on bridges to get across the Bay. They also live with the constant threat of earthquakes.
• In the 1989 Loma Prieta earthquake, one 50-foot section of the upper deck of the Bay Bridge collapsed into the lower deck, killing one person.
• The eastern span of the bridge, connecting Emeryville and Yerba Buena Island, was made of a set of truss spans that were not earthquake resistant.
• The new eastern span should withstand an 8.5 magnitude earthquake, which could strike the San Andreas Fault to its west or the Hayward fault to its east.

#### Can You Apply It?

1. How would a bridge typically be anchored? How is this span anchored?
2. Why couldn’t the new span be anchored the normal way?
3. What is the design of the tower and legs? What does the tower do?
4. What happens to the bridge in an earthquake?
5. How is it that the same bridge may experience two different earthquakes during one seismic event? How will the bridge survive that?

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