Bridges

Many State Highway (SH) bridges were subjected to strong shaking in the 2010 Darfield and 2011 Christchurch earthquakes. Most of these bridges were designed prior to 1970 and although designed for earthquakes a working stress de-sign approach was used which did not produce the ductility resilience required by current design standards. Structural damage was observed on a number of bridges but this did not require the bridges to be closed. The paper presents an assessment of the intensity of shaking at a number of typical bridge sites, describes the bridge damage and suggests reasons why the performance of the bridges was better than expected.