The city of Christchurch, New Zealand experienced a series of destructive earthquakes over the past year. On September 4, 2010 a magnitude 7.1 earthquake struck the Darfield region of Canterbury, New Zealand. The epicenter of the earthquake was 40 km from the city of Christchurch, resulting in minor damage to the area’s infrastructure. Subsequently, the area had hundreds of aftershocks, more than two dozen were 5.0 M or more, the worst of which was on February 22, 2011 (6.3 M). This one took place only 10 km south of Christchurch and caused more than 180 deaths, as well as significant damage to the surrounding area.
In order to better assess the seismic performance of bridges under earthquakes of this magnitude and frequency and help to inform decisions on the retrofit or replacement of damaged bridges, we developed a detailed database to collect damage and performance data on a small group of bridges affected by the recent earthquakes. Our responsibilities included documenting information on the foundation of each structure, calculating the mass of bridge components, traveling into the field to collect concrete samples and measurements, and categorizing evidence of damage progression. The compiled work was reviewed by researchers who will use the information to determine which bridges will be selected for detailed inspections. These case studies may reveal new findings about soil-structure interaction as a result of seismic activity and solutions to mitigate bridge damage.
During this project we had the unique opportunity of traveling to Christchurch, New Zealand, to gain hands-on field experience in structural engineering. We were able to observe first-hand how much the city was affected by the recent earthquakes. The seismic activity significantly damaged many of the multi-story buildings, deeming them unsafe. Most streets were blocked by fences and army patrols were positioned at street corners allowing access only to those who had authorization. We also traveled to a suburban part of the area where many of the houses had been abandoned, leaving the streets desolate. Some of the homes only contained internal damage, but others leaned towards one side or displayed large cracks and gaps between their walls and the ground. The opportunity to participate on a reconnaissance mission following an earthquake is something many earthquake engineers dream of having the opportunity to do (including our mentor, Lelli Van Den Einde, from UCSD's Department of Structural Engineering). This field experience demonstrated the significance an earthquake can have, not only on structural systems, but on the community. This provided us with a hands-on opportunity to learn about earthquake engineering, the technical requirements needed to design resistance to future earthquakes, and their devastating impact on communities.
This PRIME project was part of a joint pilot program between PRIME and the Network for Earthquake Engineering Simulation (NEES) in an effort to develop an ‘international research experience for undergraduates’ program in earthquake engineering that will leverage the expertise of PRIME in the hopes of establishing long-term ties between the two. Christopher Manco was the first non-UCSD student to participate in PRIME. For more on this story, and about another structural-engineering project undertaken by PRIME’s Monica Chan in Taiwan, visit www.calit2.net/newsroom/release.php?id=1890.
PARTICIPATING RESEARCHERS: U Auckland: Liam Wotherspoon; UCSD: Lelli Vande Einde