Statistics

Earthquake Resistant Bridges

Jacqueline Stoy

4/24/2013

Geography of Cultural Diversity 3350:275

Tuesday/Thursday 12:05-12:55

Throughout history, bridges have been a primary means of transportation. Unfortunately, natural disasters have come to destroy such bridges on many occasions. One of the most deadly natural disasters to face the bridges is earthquakes. The movement of the ground causes the supporting beams and columns to twist and collapse, often resulting in injury or death for those crossing the bridges. Because of the lack of safety on bridges during the quakes, engineers and researchers have been developing ways to ensure bridges stay in tact. Upgrading such bridges enhances the Nature-Culture/ecology in our society.

The beginning of earthquake resistant bridges

Bridges are a main component of the transportation infrastructure as we know it today. There are over “575,000 highway bridges nationwide, and over $5 billion are allocated yearly from the federal budget for bridge repairs” (Misha). The structure of a bridge is designed to resist the expected loads that will act on it.  The loads experienced by the bridge in an earthquake can be as strong as or stronger than gravity. In many cases the direction also rapidly changes. Bridge failure during strong earthquakes poses not only a threat of fatalities but causes a substantial interruption of emergency efforts.

“On October 17th, 1989, the Loma Prieta Earthquake hit San Francisco Bay Area with a Richter scale of 6.9 for moment magnitude and 7.1 for surface magnitude” ("Collapse). This quake caused issues to the Oakland Bay Bridge, a popular bridge allowing workers to commute from the suburbs into San Francisco. During the earthquake, the upper deck collapsed, blocking the lower deck. This caused a car to drive off the bridge, ending in death for the passengers. As a result of the accident, the bridge was shut down for approximately one month to undergo repairs and changes to the...