Behavior of Base isolated Structures in the Christchurch Earthquake

A 7.0M earthquake that struck off New Zealand’s South Island early on Saturday, September 4,2010 (12:35:46 PM EDT) has reportedly caused extensive damage to the buildings and roads in the region. The epicenter was 55 km north-west of the city of Christchurch at a depth of 12 km.The earthquake occurred as a result of strike-slip faulting within the crust of the Pacific plate, near the eastern foothills of the Southern Alps at the western edge of the Canterbury Plains. In this paper, the effect of base isolation on seismic performance of New Zealand’s structures has been investigated. To eliminate the damage, base isolation has been popular as one of the most favorable alternatives in New Zealand, America, Japan that developed quickly since1970s incivil structures, such as buildings and bridges, subjected to earthquake. This system has been considered as one of the most effective way to reduce the structural and non-structural damages and the number of victims in Christchurch earthquake. Based on observations carried out after the earthquake, the buildings which equipped with base isolation systems; through reducing acceleration, base shear to the structure, drift and increasing displacement had satisfactory performance and limited damages viewed in those buildings.