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Soon the DMA portal will share a structural engineering assessment report for Chile that Peter Yanev and collaborators have prepared for the World Bank on Chile. This is a must read given the details included and the implications for sustainable investments in seismic prone regions. In the meantime, please visit this (link) for Peter Yanev’s article on March 28th in the New York Times: Shake, Rattle, Seattle.
We urge everyone to watch the Chile EERI/PEER Reconnaissance Briefing at UC Berkeley, with presentations on March 30th by:
- Jack Moehle, UC Berkeley, 27 March 2010 Offshore Maule, Chile Earthquake, Photo Gallery (PDF - click here)
- Keith Kelson - FUGRO WLA, Geologic Aspects of the M = 8.8 February 27, 2010 Chile Earthquake (PDF - click here)
- Jonathan Bray, UC Berkeley, Geotechnical Aspects of the M = 8.8 February 27, 2010 Chile Earthquake (PDF - click here)
- Mark Yashinsky, Caltrans, EERI/PEER/FHWA Bridge Team Report (PDF - click here)
- William Holmes, Rutherford & Chekene, Reconnaissance Report on Hospitals (PDF - click here)
Also see: Agenda, EERI, EERI Chile Earthquake Clearinghouse Website
Please also visit and promote the World Housing Encyclopedia
Some of the impressive sound bites from the presentations at Berkeley include:
- Only 0.5% of buildings were severely damaged
- At least 50% of hospital elevators failed in all of Chile. Patients had to be carried down stairwells for evacuation. Only 3 patients died, all from heart attacks
- Most hospitals had emergency generators and water tanks. The state of California in the US will require this for all hospitals by the year 2030.
- Suspended lay-in or “American” ceilings caused, by far, the most disruption in hospitals and other structures, generally due to the lack of seismic detailing. The building code specifies non-structural mitigation but there is a lack of implementation. (In this case it appears the engineers thought the architects would do it and vice versa).
- On structural damage to unanchored equipment, inventory etc. multiplied the losses caused by this earthquake.
- Street or market values of expensive high rise towers is plummeting due to fears over safety.
- A dangerous trend in Chile that was observed is that older structures would have 12 inch thick walls. The new standard is only 6 inches which is much less resilient.
- There were some repeat damages in Viña del Mar of buildings that were not retrofitted sufficiently.
More technical yet still important details include:
- There are no provisions or prohibitions for vertical irregularities in the NCH433 Chilean building code. Nor is confinement of boundary zones for reinforced concrete structures required.
- The coast in Lebú, Chile was raised 2 meters during the event, leaving the harbor high and dry – while the coast at Iloca sank 1 meter increasing the devastation by the tsunami.
- All 4 bridges connecting Concepción to the rest of the country were damaged, most notably the 2.3 km bridge in collapsed due to lateral spreading and liquefaction.
- Buildings in Concepción sited on marshy ground and/or landfill with shallow foundations endured tremendous liquefaction damage.
- The port in Coronel witnessed 1.2 meters of lateral displacement, shifting 10% of the containers, 1 moved 30 feet from its original location.
- Bridges along the Pan American Highway that suffered damage were not well seated, the girders lacked diaphragms, and the seismic bars did not perform as intended.
Those of you who are seasoned engineers or professionals in structural, geodynamics, seismic and other specialties will, no doubt, identify other critical sound bites and lessons. Please share