SEAOC EPEP Pod around a strong motion recording station in Christchurch 2010.
By Jeffrey Hunt, Ph.D., P.E., Chair, SEAOC Post-Disaster Performance Observation Committee (PDPOC)
SEAOC’s Earthquake Performance Evaluation Program (EPEP) is supported by the SEAOC Post-Disaster Performance Observation Committee (PDPOC), a subcommittee of SEAOC’s Existing Building Committee. In response to a recommendation by SEAOC’s Vision 2000, the PDPOC was established in 2006 to gather building performance information that can be directly correlated to measured ground motions. Following an earthquake, personnel are deployed to survey all buildings within a “pod” around a ground motion recording station that registered minimum ground motion intensity triggers. A “pod” is defined as all buildings within a 500 ft radius of a recording station, and the triggers are a minimum peak ground acceleration of 0.2g and a minimum peak ground velocity of 20 cm/sec. During this survey a “short form” is completed for all buildings in each pod, regardless of whether they were damaged or not. The short form contains information such as building size, ASCE 31 building type, occupancy, and the extent of damage. In addition, photos of the each building within the pod are taken and cataloged. The PDPOC also has an “adopt-a-pod” program in which buildings are surveyed, categorized, and photographed prior to a seismic event. This information from adopt-a-pod facilitates post-earthquake deployment planning and data collection and allows “before and after” comparisons to be performed.
A number of training sessions to teach volunteers the methodology for consistently completing the pod surveys and short forms have been held throughout the State of California. To date, training sessions have been completed in San Diego, Pomona, San Francisco, and Sacramento. The PDPOC has deployed volunteers to the 2008 Chino Hills earthquake, the 2009 L’Aquila earthquake, the 2010 Eureka earthquake, the 2010 Sierra El Mayor earthquake, the 2011 New Zealand earthquakes, the 2014 La Habra earthquake, and the 2014 South Napa earthquake.
SEAOC EPEP survey data for the downtown Napa Pod after the 2014 South Napa earthquake.
By systemtically observing the behavior of both poor and well performing structures in close proximity to recorded ground motions, PDPOC is able to collect data that can be used for statistical and analytical studies. For example, the data gathered by the PDPOC can be used to develop and refine fragility functions that establish relationships between seismic intensity (PGA, PGV) and observed damage (e.g. shear cracks in concrete walls, cracking of drywall, overturning of equipment). Data collected by the PDPOC following the 2010 Sierra El Mayor earthquake was used to create fragility curves to define the cracking/sliding and toppling behavior of residential masonry chimneys. As the structural engineering community moves more towards performance based analysis and design (as exemplified with the adoption of the Risk Targeted Ground Motions in ASCE
7 -10 and the more widespread adoption of performance based approaches used by ATC-58, FEMA P695, HAZUS, etc.), it is becoming particularly important to gather data that directly relates building performance to ground motion intensity measures.
To learn more about SEAOC’s Earthquake Performance Evaluation Program or to become involved with the PDPOC, please contact the PDPOC chair or one of its local member contacts.
PDPOC Chair and SEAOSC contact:
Jeffrey Hunt, Ph.D., P.E. firstname.lastname@example.org
Marko Schotanus, S.E. MSchotanus@ruthchek.com
Emma Meehan, S.E. Egoodson@ruthchek.com
Fred Turner, S.E. email@example.com
Tony Court, S.E. firstname.lastname@example.org
SEAOC EPEP training in Pomona, CA in 2009.