Research Opportunities -- Improving Earthquake-Resilient Construction

Stephen MahinByron and Elvira Nishkian Professor of

Structural EngineeringDirector, Pacific Earthquake Engineering

Research CenterUniversity of California, Berkeleymahin@berkeley.edu

Quake Summit 2010 San Francisco, CA September 9, 2010

Seismic Performance Goals?Preserve Life Safety and Prevent Collapse

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If collapse can be prevented, what level of damage is acceptable?

Fractured Spiral Fractured Spiral Fractured Bar

Buckled Bars

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Yielded and buckled members

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Local Failure

Permanent Offset

Fracture

Research traditionally focuses on achieving ductile behaviorBrittle fractures were detected in welded steel moment connections following Northridge, Kobe & other earthquakes.

Fracture

OLD: Brittle fractures, possible collapse hazard

Fracture

Research traditionally focuses on achieving ductile responseBrittle fractures were detected in welded steel moment connections following Northridge, Kobe & other earthquakes. Integrated analytical, theoretical and experimental research

lead to connections dependable ductile behavior

Is this what we really want?

Fracture

NEW: Ductile, large inelastic displacement capacity Local buckling, fracture & permanent offset

Difficult & costly repair

Ricles et al

Even moderate damage may mean buildings lose their functionality

Natural disasters cause wide-spread moderate damage

Such damage can have substantial long-lasting social, economic and cultural impacts on a city.

Sustainable development

UN Brundtland Commission“ meet needs of present generations without compromising the ability of future generations to meet their needs”

Selection of materials; Use of recycled materials; Consideration of material re-use and disassembly

for reuse; Energy efficiency Durability and longevity Reparability More efficient and lower impact construction; More efficient design methods, and more efficient

structural systems and layouts; Integration of structural forms to help achieve the

needs of other disciplines; Reducing the impacts of abnormal events such

earthquakes by minimizing the need for repair and disruption of service.

“Resiliency”

Beyond Safety: Issues for Sustainable and Earthquake-Resilient Structures

In Earthquake Engineering, our future challenge is to develop new or improved structures that:

protect public safety, and are economical, but that can be constructed quickly with minimal

disruption to the public and to the environment, and

can withstand strong earthquake ground shaking (and other hazards) safely, with little disruption or cost associated with post-earthquake inspections and repairs.

Recycle

Such approaches are consistent with, and supportive of, emerging trends related to sustainable development and “green” design.

Resilient structures, networks and communities

Sheltering in Place vs.

Damage Free

Sheltering in Place vs.

Damage Free

Beyond Safety: Issues for Sustainable and Earthquake-Resilient Structures

Safety Reduce post-earthquake disruption

and speed recovery of normal operations

Recycle

Systems that:Place damage known locationsMake it easy to inspectMake it economical to repair

Systems that:Minimize lateral displacements Minimize accelerationsMinimize residual displacements

Beyond Minimum Safety: Disaster-Resilient Structures

Recycle

Numerous structural concepts possible High performance materials Self-centering structural

concepts Rocking Foundations Next-generation braced and

damped systems Inertial damping systems Seismic Isolation

Assessing trade-offs in improving performance by increasing strength,

stiffness and toughness?

Performance-Based Earthquake Engineering (PBEE) Evaluation

PerformanceFramework

EnvironmentalHazard

Structure Simulation Evaluation

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Robust ProceduresAccurate Models

Effective InelasticMechanisms

PBEE

NEES capabilities People Ideas Tools

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Collaboratory By bringing researchers, educators and students

together with the members of the broad earthquake engineering and information technology communities, providing them ready access to powerful experimental, computational, information management and communications tools, and facilitating interaction as if they were “right across the hall,” the NEES collaboratory will be a powerful catalyst for transforming the face of earthquake engineering.

After William Wulf, NRC (1989)

Collaboratory

The missing link….. A principal aspect of collaboratories were

campaigns. Broad, scientifically challenging problems of national

importance Worked on by:

Grand Challenges Small group projects Individual investigator projects Government and academic organizations Private companies

Centers such as PEER focus on broad problem focused research themes

NEES can be harnessed to enable campaigns suggested by NEHRP strategic plan and other important social and scientific problems.

Concluding RemarksPBEE concepts can be used to proactively

achieve designs that are not only safer and more economical, but also more resilient.

PBEE investigations show significant impacts associated with nonstructural damage in small earthquakes and with structural damage and permanent offsets in larger events.

New technologies, devices and materials enable structures to minimize nonstructural and structural damage and to self-center.

Concluding RemarksPBEE provides the critical framework to

assess tradeoffs in performance and cost. Many opportunities as well as scientific and

technical challenges related achieving resilient communities, including buildings, transportation and lifelines.

Problems are multidisciplinary in nature and require collaboration among various disciplines, design professionals and industry.

ありがとうございました

THANK YOU

http://peer.berkeley.eduhttp://nees.org