The Rion-Antirion Bridge- earthquake proof

I have started writing an essay on the Rion-Antirion bridge, the largest multi-span cable-stayed bridge that spans the Gulf of Corinth in Greece, an area of high seismicity and large rift expansion. I was inspired by the program 'Richard Hammond's Engineering Connections' to find out more. I thought that it tied in nicely with this project, to know about the possibilities of infrastructure other than buildings to withstand earthquakes.

The engineers working on this project were able to overcome the seemingly impossible challenges due to the extreme conditions of the location with innovative solutions. Since its completion in 2004 it has already proven its ability to withstand earthquakes. The bridge has also proven to be a link of great necessity with 10,000 vehicles crossing on a daily basis. [1]

The aim of an earthquake-proof bridge was achieved due to:

• the deck being suspended entirely by cables allowing it to move freely during an earthquake;
• the pylons being built on gravel allowing them to move freely;
•  Fluid viscous dampers prevent the deck from rocking too much.

Other features:

• The weak soil was reinforced using steel piles which transfer the forces to lower soil;
• restraints were connected to the fluid viscous dampers to prevent the deck rocking and thus suffering wind induced oscillation when there is no seismic activity;
• the restraints were built to break under a certain load i.e. in an earthquake allow the fluid viscous dampers to start;

On April 13, 2005, the Rion-Antirion Bridge was given “The Outstanding Civil Engineering Achievement (OCEA)” award by the American Society of Civil Engineers (ASCE). [2] The project set numerous world records including: longest cable-stayed suspended bridge deck and deepest bridge foundations. It was the first time steel pipes were used to reinforce weak soil and to have moving pier bases.