SAN FRANCISCO--(BUSINESS WIRE)--More than 150 engineers, architects and graduate students joined forces over the weekend to conduct a block-by-block survey of San Francisco’s multi-unit residential wood-frame buildings, including the so-called “soft-story” structures located throughout the City that are potentially at risk during earthquakes. These volunteers, organized by the Earthquake Engineering Research Institute’s Northern California Chapter (EERI-NC) and the Structural Engineers Association of Northern California (SEAONC), collected data on structures in downtown neighborhoods including the Mission, Haight-Ashbury, and Telegraph Hill. Their data will be used by City authorities to assess further the City’s vulnerable housing stock leading to mitigation strategies that will ultimately reduce the seismic risks posed by these buildings. Joining the volunteers from EERI-NC and SEAONC were members of the San Francisco branches of the American Institute of Architects (AIA), American Society of Civil Engineers (ASCE), and graduate students from UC Berkeley, San Francisco State and Stanford University. Soft-story buildings are those in which the first story is substantially more flexible than the stories above, typically due to multiple openings for garage doors and entrance ways. These structures perform poorly in earthquakes. In the 1994 Northridge Earthquake, 16 people were killed and 34,000 housing units were left uninhabitable by soft-story building collapses. Closer to home, in the 1989 Loma Prieta Earthquake, 2 lives were lost and 7,700 housing units were rendered uninhabitable due to soft-stories. In light of this, it is perhaps not surprising that a 2006 study by Kircher et al., prompted by the recent anniversary of the Great San Francisco Earthquake, concluded that soft-story wood buildings were among the most vulnerable building types when estimating losses due to a repeat of the 1906 event. Last year, Assembly Bill 304 was signed into law by California Governor Arnold Schwarzenegger, allowing local governments to identify soft-story buildings as potentially hazardous to life and to establish local standards to retrofit them. Other California cities, such as Berkeley and Fremont, have surveyed their buildings but none has as large an inventory as San Francisco. The City’s Department of Building Inspection (SFDBI) staff has studied key neighborhoods, but it would take them months, or even years, to canvass the entire city. Saturday’s event provided a hands-on opportunity for seismic-safety advocates from varying backgrounds – structural and civil engineers, geologists, seismologists, architects, building officials and others – to work together to perform a great community service. What’s more, the exercise was an excellent learning experience for future post-disaster surveys. According to Ray Lui, Manager of SFDBI’s Structural Safety and Emergency Planning Division, “Collecting reliable data efficiently and systematically is far easier before the big quake than afterward. Plus it can give us a chance to head off seismic hazards before they occur.” He should know. Lui coordinated SEAONC’s efforts for the State’s Office of Emergency Service (OES) Safety Assessment Volunteers (SAV) in New Orleans following Hurricane Katrina. EERI is a national, nonprofit technical society dedicated to advancing the science and practice of earthquake engineering by improving understanding of the impact of earthquakes on the physical, social, economic, political and cultural environment. SEAONC, founded in 1930, is also a non-profit technical society, committed to advancing the art and science of structural engineering.
