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How To Design and Build More Earthquake-Resistant and Cost-Effective Structures Clifford J. Roblee, Ph.D., P.E Executive Director, NEES Consortium, Inc. Congressional Hazards Caucus Coalition Briefing Earthquakes: Mitigation Through Effective Design and Getting the Public Involved Room 2325 Rayburn Building, Washington, D.C. September 20, 2005
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Earthquake Risk is Well Recognized by Experts, But Often Overlooked by Public Until It Is Too Late Courtesy Paul Somerville, URS NHK Nagoya Office, Kobe, Japan, January 17, 1995 There Is No Radar, No Intelligence, For Short-Term Warning Just Assurance of Long-Term Occurrence
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Earthquake Risk is Well Recognized by Experts, But Often Overlooked by Public Until It Is Too Late
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Perspective: EQ Risk Mitigation Engineering/Construction of Resilient Infrastructure is Best Mitigation Strategy –Complements Land Use, (Potential) Early Warning, and Emergency Response Strategies –100% Effectiveness is Technically Feasible … Issues Surround Cost-Effectiveness Success Requires: –Effective Design Tools for Hazard Identification –Cost-Effective Engineering Solutions for Varied: Performance Objectives (Life Safety, Post-EQ Functionality, Life-Cycle Costs, etc.) Hazard Types (Shaking, Fault Offset, Liquefaction, Landslide, Tsunami) and Levels of Hazard Infrastructure Types (Buildings, Bridges, Lifelines, Dams, etc.) Construction Materials (Steel, Concrete, Timber, Soil, etc.) Construction Methods (Cast-in-Place, Pre-Fab Components, etc.) –Political Skill & Will: Public-Interest Policies & Decisions (Market Alone Insufficient) Smart Codes & Design Practices Applied by Knowledgeable Workforce –Good Construction & Maintenance Practices Earthquakes Remain An Important National Hazard to Life And Property ($4B/Yr) –Affect Our Homes, Work, Commerce, Economy, Social Fabric, & National Prestige
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Much Has Been Accomplished … Modern Ductile Details Initial Failure at ~0.6g Courtesy of Caltrans Older Brittle Details Total Failure at ~0.2g Retrofit Priority Courtesy of Caltrans
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... and Continues To Be Accomplished Courtesy of University of Nevada, Reno
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... and Continues To Be Accomplished Courtesy of University of Nevada, Reno
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… Much Still Remains To Be Done Extreme Loading Conditions Near-Fault Directivity Fault Crossing – Large Offset Liquefaction – Lateral Spread Landslide Performance-Based Design Quantitative Risk Assessment Account for Variability & Uncertainty Multiple Performance Objectives Cost-Effectiveness Post-Yield Behavior Highly Non-Linear Problem Controlled Sequence of Yield Requires Large-Scale Testing Reliable Simulation System vs. Component Performance Compounding Error & Uncertainty Fault-to-Rebar for Variability Socio-Economic Impact System & Network Functionality Consequences on Commerce/Individuals/Society Innovative Technologies Devices: Base Isolation, Energy Absorption, etc. Details: Materials, Connections, Systems, etc. Goals Tools
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Advancing EQ-Resilient Infrastructure Why Accelerate Innovation? $100’s Billions in Annual US Construction in Seismic Areas Typical Infrastructure Design Life: 30-100 Years Retrofit is More Costly and Less Effective Than New Construction The Innovation Process (10-30 Years) Basic Research: Ideas & Discovery of Fundamental Concepts/Techniques Applied Research (Development): Evaluation, Testing, Refinement, Design Models Verification: Prototype/Trial Applications & Monitoring, Pre-Guidelines Professional Acceptance & Adoption: Code & Standards Development Deployment: Routine Application by Stakeholders What’s Needed to Accelerate Innovation? Strategic Plan for Research (including Development) Balanced Portfolio of Basic and Applied Research Stakeholder Involvement in Both Planning and Guiding Research Advanced Testing Facilities & Knowledgeable Researchers (e.g. NEES) Political Will (Public Support & $$$) for Research thru Deployment
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Courtesy of Caltrans Example: Verification to Deployment Innovative Bridge Application of Very Large Friction Pendulum Bearings
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NEES Shared-Use Infrastructure [Operated by NEESinc]
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Example: Applied Engr. Research Experimental Validation & Refinement of “Zipper Frame System” Concept Courtesy of Prof. Roberto Leon, Georgia Tech. Behavior controlled by brace buckling - system is unable to redistribute forces efficiently Conventional Steel Braced Frame Zipper struts tie all brace-to-beam intersection points together and force all the compression braces to buckle simultaneously (Khatib, Mahin, Pister) Zipper Frame Weakens After First Yield Strengthens After First Yield Yield Add Members
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NEES Testing of Zipper Frame Courtesy of Prof. Roberto Leon, Georgia Tech. Fast-Hybrid Component Test (Colorado) Simultaneous Substructure Test (Berkeley)Static Frame-System Test (GaTech) Dynamic Frame-System Test (Buffalo)
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NEES Testing of Zipper Frame Courtesy of Prof. Andrei Reinhorn University of Buffalo
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NEES Testing of Zipper Frame Courtesy of Prof. Andrei Reinhorn University of Buffalo
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Closing Perspective “We are not about to predict earthquakes. As one door closes, another opens. If we can’t predict earthquakes, then let’s learn to live safely with them. Isn’t it better if we can build buildings that don’t fall down. Then, rather than try to evacuate populations and then come back to a destroyed city, we don’t have to leave, and our cities survive. It seems to me that this really is the best solution, and the way to do that is to begin to identify buildings that are collapse risks and begin to improve them or get rid of them.” Dr. Ross Stein, Geophysicist, USGS Menlo Park “Science Friday” Interview, June 24, 2005
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