Liquefaction Effects on Buildings in the Central Business District of Christchurch

The Canterbury earthquake sequence provides an exceptional opportunity to investigate the effects of varying degrees of liquefaction on the built environment. Many multistory buildings in the Central Business District were heavily damaged by liquefaction-induced ground movements during the Christchurch earthquake, but not by other earthquakes (e.g., the Darfield and June 2011 events). Cone penetration test (CPT)-based liquefaction triggering evaluations were conservative. The conservatism in the liquefaction triggering assessments led to post-liquefaction ground settlement estimates that were generally similar for the large events in the earthquake sequence, whereas significant ground settlements and building damage in the CBD were only observed for the Christchurch earthquake. Moreover, the liquefaction-induced ground settlement procedures do not capture important shear-induced deformation mechanisms and the effects of ground loss due to sediment ejecta. Performance-based earthquake engineering requires improved procedures to capture the differing levels of performance observed in Christchurch.