Seismic Performance of Concrete Bridges during Canterbury Earthquakes

In less than six months the city of Christchurch, experienced two major earthquakes on September 4, 2010 and February 22, 2011. The former was generated by rupture of the previously unknown Greendale fault releasing a magnitude (M_w) 7.1 earthquake at 30-40km away from the city, while the latter event, a M_w 6.2, was less than 10km from the Central Business District on a buried fault at beneath of the city. Lifelines sustained widespread damage in Christchurch City and the closest districts of Selwyn and Waimakariri. However, no major bridge collapses were registered, and only twenty bridges required closure due to damage caused by the two earthquakes. Canterbury soils are susceptible to liquefaction, and the resulting lateral spreading caused extensive damage to roads/bridge approaches and the associates lifelines. Authors aim to provide a seismic damage assessment overview of Canterbury bridges, emphasizing unexpected issues that are still not properly detailed in New Zealand and overseas standards.