Lessons Learned From The Chilean Earthquake – Steps We Can Take In The U.S.

Data gathered by a team of renowned structural and geotechnical engineers from the magnitude 8.8 earthquake that struck Chile on Feb. 27 may help to better understand how we can mitigate damage in quake-prone areas in the United States.

A six-member team of private sector quake experts was dispatched by the non-profit Los Angeles Tall Buildings Structural Design Council (LATBSDC), specifically to investigate the performance of tall buildings. Chile has similar design and construction practices to the U.S., where there's also an abundance of skyscrapers in major population areas.

Background
Chile, population 16.6 million, is almost twice the size of California, with 85 percent of the population living in urban areas. Nearly half live in three metro areas – Santiago, Valparaiso-Vina del Mar, and Concepcion-Talcahuano.

Chile is one of the most seismically active areas worldwide; in fact, the University of Chile's Servicio Sismologico reports that between 1570 and 2007, there have been 107 destructive quakes with a magnitude of 7.0 or greater. And since 1960, two of the world's five most powerful quakes (1960 and 2010) occurred in Chile (others were Kamchatka, 1952; Alaska, 1964; Sumatra, 2004).

The Chilean quake occurred at the convergence of the Nazca (oceanic) plate with the South American continental plate along a subduction zone where the Nazca plate moves under the South American plate. Confirmed fatalities to date are just under 500; more than 800,000 people were injured or displaced and damage is expected to top $30B(U.S.).

Chilean Structural Design Practice
Chile's building code, issued by the National Institute of Normalization in 1996, is similar to building codes used in the U.S. Concrete design, for example, is largely based on the American Concrete Institute (ACI) 318 Building Code Requirements for Structural Concrete. Chile's building code did allow for some exceptions to ACI requirements that may have caused damage in some buildings. These exceptions were that boundary elements should be provided at boundaries and edges around openings of structural walls when there is high extreme fiber stress under loading (including earthquakes), and that boundary elements should have transverse reinforcement with proper anchorage within the core of the boundary element.