How To Design and Build More Earthquake-Resistant and

Cost-Effective Structures

Clifford J. Roblee, Ph.D., P.EExecutive Director, NEES Consortium, Inc.

Congressional Hazards Caucus Coalition BriefingEarthquakes: Mitigation Through Effective Design and Getting the Public Involved

Room 2325 Rayburn Building, Washington, D.C.September 20, 2005

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 WarningJust Assurance of Long-Term Occurrence

Earthquake Risk is Well Recognized by Experts, But Often Overlooked by Public Until It Is Too Late

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

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

... and Continues To Be Accomplished

Courtesy of University of Nevada, Reno

... and Continues To Be Accomplished

Courtesy of University of Nevada, Reno

… 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

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

Courtesy of Caltrans

Example: Verification to DeploymentInnovative Bridge Application of Very Large Friction Pendulum Bearings

NEES Shared-Use Infrastructure

[Operated by NEESinc]

Example: Applied Engr. ResearchExperimental 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

YieldYield

Add Members

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)

NEES Testing of Zipper Frame

Courtesy of Prof. Andrei Reinhorn University of Buffalo

NEES Testing of Zipper Frame

Courtesy of Prof. Andrei Reinhorn University of Buffalo

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