Connections to Seattle: Implications for Local Buildings and Lifelines - Mark Pierepiekarz
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2013 EERI Annual Meeting Session: Christchurch Earthquakes Workshop
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Connections to Seattle: Implications for Local Buildings and Lifelines - Mark Pierepiekarz
- 1. Connections to Seattle: Implications for Local Buildings and Lifelines PRESENTED BY: MARK R. PIEREPIEKARZ, P.E., S.E. MRP ENGINEERING, LLC mrp@mrpengineering.com www.mrpengineering.com (425) 430-0500
- 2. Agenda • Local seismicity • Seattle fault • Lifeline systems • Local building stock • Seattle URM buildings • Conclusions
- 3. PNW is Earthquake Country
- 4. 2010 M8.8 Chile PNW—M9.0 Scenario Vancouver Santiago Seattle Portland Concepcion Source: USGS Stronger shaking →
- 5. Notable Earthquake Events … Source: Tokyo Tech, CUEE, Midorikawa Lab.
- 6. … and Subduction Events! 2010 Chile (M8.8) 2011 Japan (M9.0) Source: Tokyo Tech, CUEE, Midorikawa Lab.
- 9. 2001 M6.8 Seattle Earthquake: A Moderate Event?
- 10. M6.7 Scenario Ground Motions Seattle Modeled fault Tacoma
- 11. New Zealand Pre-2010 Seismic Hazard
- 12. New Zealand Pre-2010 Seismic Hazard
- 13. New Zealand Pre-2010 Seismic Hazard
- 14. M6.7 Seattle Scenario • Economic loss: $33 billion • 1,600 deaths; 24,000 injured • Buildings destroyed: 9,700 • Buildings, unsafe: > 29,000 • Buildings, use restricted: > 154,500 • Transportation: severely restricted • Fires: 130 • Recovery period: several years • http://seattlescenario.eeri.org
- 15. Seattle Liquefaction Risk 2011 Tokyo Source: Seattle Fault Earthquake Scenario Project
- 16. Juan Pablo II Bridge (1974), Concepción
- 17. Lifelines • Water • Wastewater • Liquid fuel • Natural gas • Electric power • Communications • Pipeline network damage controlled by liquefaction • Fault rupture damages N-S trending pipelines
- 19. What Structures Are Most Vulnerable? Reinforced concrete frames
- 20. What Structures Are Most Vulnerable? Wood frames with soft-story Tilt-ups Source: EERI
- 22. City of Seattle Recommendations for an Unreinforced Masonry Policy The City of Seattle is considering a mandate for all unreinforced masonry (URM) buildings to undergo a seismic retrofit to reduce the risk of injury and loss of life in the case of an earthquake. URM buildings are known to be unsafe. http://www.seattle.gov/dpd/Emergency/ UnreinforcedMasonryBuildings/ URMSeismicHazardsStudy/default.asp
- 23. Retrofitted URM Building New Wall Ties
- 24. Why is URM policy necessary? • Public safety • Historic and cultural character preservation • Economic vitality of neighborhoods • 1949 and 1965 earthquakes: – URM buildings significantly damaged • 2001 Nisqually earthquake: – 67% of unsafe buildings were URMs • Seattle fault is a major concern
- 25. Status of Seattle’s URM Buildings • 1,000+ URM structures within the city limits • Some seismically retrofitted to improve safety to some degree • URM buildings house a range of occupancies • Previous URM ordinances abandoned: – Construction cost concerns
- 26. Seattle Retrofit Policy Today • Unbraced URM parapets must be abated or braced. • Only a major addition or alteration requires a seismic report. – Findings or substantial non-compliance trigger mandatory seismic retrofit.
- 27. “Proposed” URM Retrofit Requirements • Brace parapets • Connect floors and roofs to URM walls • Interconnect floor and roof framing • Strengthen weak bearing walls • “Go beyond minimum” approach is encouraged
- 28. URM Policy Goals and Objectives Primary: • Improve life safety Secondary: • Preserve historic and significant landmarks • Preserve buildings important to a neighborhood • Improve earthquake resiliency • Minimize post-event demolition
- 29. How is URM building risk ranked? Risk Comment • Schools Critical • Critical facilities • >3 stories and weak soils High • >100 occupants Medium • Other URMs
- 30. Recommended Timeline for Completing a Retrofit Risk Time (years) Critical 7 High 10 Medium 13 If the program takes effect in 2014, retrofits to be completed by 2027
- 31. What are the “proposed” steps in a URM retrofit? 1. Notification from jurisdiction 2. Structural assessment 3. Construction permit application 4. Permit approval 5. Retrofit construction completion
- 32. What will make the policy more effective? • Easily understandable requirements • Broad-based support • Options for financial support to reduce retrofit costs • Early participation encouragement • Retrofit “beyond the minimum” encouragement
- 33. Conclusions • Damaging earthquakes do occur in unexpected locations. • PNW is earthquake country. • Vulnerable buildings must be upgraded. • Critical lifelines must be protected • The time to act is now.
Notas del editor
- Seismic Risk Evaluation: Longview, Washington July 26, 2005--Mark R. Pierepiekarz, PE, SE, and Charlene F. Hails, PE, SE
- We should heed lessons from Chile and Japan…because it could happen here… The last one happned on jan 29 1700, we know this form our friends in Japan (and gelogic evidence here), in fact there is evidence of several such events overthe last 2000 years or so..
- Until 2010 we were primarily dealing with events caused by shallow faults (damaging) by relatively short in duration ( 10 to 30 seconds) You hear the richter magnitude We, as engineers, tend to look at the recorded ground shaking (and correlate that to damage) at a site of interest Duration of shaking is AS IMPORTANT…. Seismic Risk Evaluation: Longview, Washington July 26, 2005--Mark R. Pierepiekarz, PE, SE, and Charlene F. Hails, PE, SE
- Chile and Japan earthquakes were game changers Structures were asked to sustain 3 to 4 min of strong shaking - with repairable damage (and occupant safety) - Life safety is not enough (impacts and costs are too great) – we really want immediate occupancy and functionality (whether we know it or not) Seismic Risk Evaluation: Longview, Washington July 26, 2005--Mark R. Pierepiekarz, PE, SE, and Charlene F. Hails, PE, SE