Use of Advanced Technologies Use of Advanced Technologies for Seismic Hazard Mitigationfor Seismic Hazard Mitigation

Keri L. RyanKeri L. RyanAssistant ProfessorAssistant Professor

Civil and Environmental EngineeringCivil and Environmental EngineeringUtah State UniversityUtah State University

To meet minimum code standards, civil To meet minimum code standards, civil engineering structures are designed for engineering structures are designed for

“life safety” in an earthquake.“life safety” in an earthquake.

Many devices are available to protect Many devices are available to protect structures from earthquakes.structures from earthquakes.

Seismic isolation and damping can reduce Seismic isolation and damping can reduce force and displacement demands so force and displacement demands so

structure remains elastic or “damage free”structure remains elastic or “damage free”

Fixed - base structure Isolated Structure

Seismic isolation reduces the forces Seismic isolation reduces the forces transferred to a structure by transferred to a structure by

lengthening its natural periodlengthening its natural periodA

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Lead rubber bearings provide lateral Lead rubber bearings provide lateral flexibility and weight carrying capacity flexibility and weight carrying capacity

with alternating layers of rubber and steelwith alternating layers of rubber and steel

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Bilinear model

Friction pendulum system allows the Friction pendulum system allows the structure to slide on a curved friction structure to slide on a curved friction

surface.surface.

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Bilinear model

Viscous or friction dampers dissipate Viscous or friction dampers dissipate energy to reduce structural response.energy to reduce structural response.

““Smart” dampers use feedback control to Smart” dampers use feedback control to adjust the amount of damping in real time.adjust the amount of damping in real time.

MR (magneto-rheological) MR (magneto-rheological) damper uses a fluid that damper uses a fluid that changes viscosity in the changes viscosity in the presence of a magnetic field. presence of a magnetic field.

Control algorithms decide what Control algorithms decide what magnetic field to apply. magnetic field to apply.

Worldwide ScenarioWorldwide Scenario

United States United States • 80 isolated buildings 80 isolated buildings

and 60 buildings and 60 buildings using dampersusing dampers

• Retrofit of landmark Retrofit of landmark historic buildingshistoric buildings

• New design of New design of emergency response emergency response facilities and facilities and supercomputing supercomputing centerscenters

WorldwideWorldwide• > 2000 isolated > 2000 isolated

buildings in Japanbuildings in Japan• Several hundred Several hundred

applications in China applications in China and Taiwanand Taiwan

• Widespread Widespread commercial and commercial and residential useresidential use

Obstacles to Use of Seismic Isolation in Obstacles to Use of Seismic Isolation in the United Statesthe United States

Cost of devices and accessoriesCost of devices and accessories Inability to convey benefits to Inability to convey benefits to

building ownersbuilding owners Complex and inconsistent design Complex and inconsistent design

codecode Strict performance goalsStrict performance goals Extensive testing and peer reviewExtensive testing and peer review Typical design office inexperienced Typical design office inexperienced

and does not try to sell technologyand does not try to sell technology

NEES TIPS Project NEES TIPS Project (NSF Award No. CMMI-0724208)(NSF Award No. CMMI-0724208) Tools to Facilitate Widespread Use of Tools to Facilitate Widespread Use of

Isolation and Protective SystemsIsolation and Protective Systems

4 year, $1.5 million, multi-4 year, $1.5 million, multi-institutional grantinstitutional grant

Shaking table and Shaking table and hybrid testinghybrid testing at at SUNY Buffalo and UC BerkeleySUNY Buffalo and UC Berkeley

Full scale tests on world’s largest Full scale tests on world’s largest shake table, E-Defense, in Japanshake table, E-Defense, in Japan

NEES TIPS Project NEES TIPS Project (NSF Award No. CMMI-0724208)(NSF Award No. CMMI-0724208) Tools to Facilitate Widespread Use of Tools to Facilitate Widespread Use of

Isolation and Protective SystemsIsolation and Protective Systems

4 year, $1.5 million, multi-4 year, $1.5 million, multi-institutional grantinstitutional grant

Shaking table and hybrid testing at Shaking table and hybrid testing at SUNY Buffalo and UC BerkeleySUNY Buffalo and UC Berkeley

Full scale tests on world’s largest Full scale tests on world’s largest shake table, E-Defense, in Japanshake table, E-Defense, in Japan

¼ scale test at UC ¼ scale test at UC BerkeleyBerkeley

Full scale test at E-Full scale test at E-Defense, JapanDefense, Japan

TIPS Project ObjectivesTIPS Project Objectives

Fill knowledge gaps regarding Fill knowledge gaps regarding modeling and performancemodeling and performance• Component characterization testsComponent characterization tests• Isolator and damper modelingIsolator and damper modeling• Performance limit statesPerformance limit states• Full scale testingFull scale testing• Worldwide information databaseWorldwide information database

Isolator behavior is complex and Isolator behavior is complex and rate/scale dependent.rate/scale dependent.

TIPS Project ObjectivesTIPS Project Objectives

Fill knowledge gaps regarding Fill knowledge gaps regarding modeling and performancemodeling and performance• Component characterization testsComponent characterization tests• Isolator and damper modelingIsolator and damper modeling• Performance limit statesPerformance limit states• Full scale testingFull scale testing• Worldwide information databaseWorldwide information database

TIPS Project ObjectivesTIPS Project Objectives

Reduce cost of using seismic isolationReduce cost of using seismic isolation• Component sensitivity studyComponent sensitivity study• Configuration and detailing issuesConfiguration and detailing issues• Improved static design procedure for regular Improved static design procedure for regular

buildingsbuildings Tools to meet performance goalsTools to meet performance goals

• High performance system testsHigh performance system tests• Extend performance-based analysis tools to Extend performance-based analysis tools to

isolated buildingsisolated buildings Needs assessment and professional Needs assessment and professional

participationparticipation

Strategies for cost reductionStrategies for cost reduction

Architectural detailing, electrical, plumbing Architectural detailing, electrical, plumbing to accommodate displacementsto accommodate displacements

Move isolation planeMove isolation plane

Strategies for cost reductionStrategies for cost reduction Simplified DesignSimplified Design

• Isolator deformationIsolator deformation• Distribution of static forcesDistribution of static forces

Sensitivity study of Sensitivity study of devices to reduce need devices to reduce need for testingfor testing

Allow moderate Allow moderate yieldingyielding

TIPS Project ObjectivesTIPS Project Objectives

Reduce cost of using seismic isolationReduce cost of using seismic isolation• Component sensitivity studyComponent sensitivity study• Configuration and detailing issuesConfiguration and detailing issues• Improved static design procedure for regular Improved static design procedure for regular

buildingsbuildings Tools to meet performance goalsTools to meet performance goals

• High performance system testsHigh performance system tests• Extend performance-based analysis tools to Extend performance-based analysis tools to

isolated buildingsisolated buildings Needs assessment and professional Needs assessment and professional

participationparticipation

Long term visionLong term vision

Vulnerability of isolated buildings to Vulnerability of isolated buildings to long period, high velocity pulses from long period, high velocity pulses from very rare motions remains an issue.very rare motions remains an issue.

Smart structures and smart isolation Smart structures and smart isolation systems that can tune their systems that can tune their frequencies in real time.frequencies in real time.

Applications of Fractional CalculusApplications of Fractional Calculus

Fractional Control Algorithms Fractional Control Algorithms • Applied to fast hybrid testing of MR Applied to fast hybrid testing of MR

dampers (Abdollah Shafieezadeh)dampers (Abdollah Shafieezadeh)

Fractional Modeling of Seismic Fractional Modeling of Seismic Isolation BearingsIsolation Bearings

Modeling issuesModeling issues

Amplitude Amplitude dependencedependence

Frequency Frequency dependencedependence

Strain hardening of Strain hardening of high damping high damping rubberrubber

Cyclic degradation Cyclic degradation (recoverable and (recoverable and non-recoverable)non-recoverable)

CurrentlyCurrently• Complex models – Complex models –

up to 10 parameters up to 10 parameters to be fittedto be fitted

• Everyone uses Everyone uses bilinear modelsbilinear models

VisionVision• Simpler models Simpler models

using fractional using fractional calculuscalculus

• Determine and Determine and capture essential capture essential effectseffects

• Provide tools to fit Provide tools to fit models using models using database test datadatabase test data

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