The objective of this Rapid Research Response (RAPID) award is to gather perishable data on the damage to two precast concrete buildings during the February 2011 magnitude 6.3 Christchurch, New Zealand, earthquake. This project is a collaboration among researchers from the University of California-San Diego, University of Arizona, and University of Canterbury. Project team members will travel to Christchurch and catalog earthquake damage (foundation, structural and non-structural) through visual observation. The post-earthquake structural state will be determined by means of collecting ambient vibration and potential aftershock dynamic response. An array of accelerometers loaned from the NEES facility at the University of California, Los Angeles will be temporarily deployed to monitor and record these vibrations. Sensors will be strategically distributed to capture the predominant modes of vibration and concentrated at the foundation to capture soil-structure interaction. This data will be post-processed for a first-level system identification and characterization of the damaged buildings.
Cataloging post-earthquake damage is an established practice for the benefit of seismic design. Forensic engineering is an essential catalyst of modern building codes. The technique advances the field of earthquake engineering leading to better designs, seismic details, and construction methods. These two buildings are important to the earthquake engineering research community and the precast concrete industry in the United States because of relevant construction and designs. With state-of-the-art seismic design guidelines in place, the two buildings performed as intended, well beyond the life-safety minimum of seismic design philosophy in New Zealand and the United States. Structural damage was sustained as expected, with the buildings' structural integrity remaining intact. To replicate this desirable performance in future buildings, the damage needs documenting to advance the earthquake engineering practice before repairs eliminate the opportunity. Participation by researchers at three universities in two countries will strengthen the infrastructure for research on an international level. Educational outreach is leveraged by introducing an undergraduate student to international collaborative research, forensic engineering, sensors, data acquisition, and seismic resilience with an NSF-supported Research Experiences for Undergraduates site through the Pacific Earthquake Engineering Research Center at the University of California, Berkeley.
, a field investigation was conducted to document precast concrete buildings that sustained damaged during the earthquake and subsequent aftershocks. The buildings investigated were a 9-story moment resisting frame structure and a 5-story parking garage with shear walls. Both structures were repaired and have subsequently reopened. Observable damage was cataloged and sensors deployed to capture structural dynamic characteristics. These tasks were successfully completed with a post-doctoral scholar leading an undergraduate intern and NEES personnel on a two-week site visit to Christchurch. International collaboration with engineers involved in the buildings’ designs and researchers at the University of Canterbury facilitated the realization of objectives by gaining access to the buildings, providing insight into the structural damage, and assisting in the damage observations and data acquisition. Damage documentation was primarily achieved through photographic evidence. A systematic sequence of photographs was used to thoroughly archive the damage and its location inside the building. Field notes and measurements supplemented these photographs and were relied upon for the creation of damage maps. Structural monitoring with high fidelity instrumentation delivered ambient vibration data and triggered aftershock recordings for system identification purposes of the damaged structures. Observed damage patterns were consistent with current NZ seismic design philosophy. Plastic deformations concentrated in regions especially detailed for seismic energy dissipation, but both structures had regions that experienced excessive damage. These damage patterns were archived to enable future numerical model verification.
