Use of Advanced Technologies for Seismic Hazard Mitigation Keri L. Ryan Assistant Professor Civil and Environmental Engineering Utah State University

To meet minimum code standards, civil engineering structures are designed for “life safety” in an earthquake.

Many devices are available to protect structures from earthquakes.

Seismic isolation and damping can reduce force and displacement demands so structure remains elastic or “damage free” Fixed - base structure Isolated Structure

Seismic isolation reduces the forces transferred to a structure by lengthening its natural period Acceleration k1,m1k2,m2 Displacement k1,m1k2,m2 Period

Lead rubber bearings provide lateral flexibility and weight carrying capacity with alternating layers of rubber and steel fbfb ubub Q kbkb k1k1 Bilinear model

Friction pendulum system allows the structure to slide on a curved friction surface. fbfb ubub Q kbkb k1k1 Bilinear model

Viscous or friction dampers dissipate energy to reduce structural response.

“Smart” dampers use feedback control to adjust the amount of damping in real time. MR (magneto-rheological) damper uses a fluid that changes viscosity in the presence of a magnetic field. MR (magneto-rheological) damper uses a fluid that changes viscosity in the presence of a magnetic field. Control algorithms decide what magnetic field to apply. Control algorithms decide what magnetic field to apply.

Worldwide Scenario United States United States 80 isolated buildings and 60 buildings using dampers80 isolated buildings and 60 buildings using dampers Retrofit of landmark historic buildingsRetrofit of landmark historic buildings New design of emergency response facilities and supercomputing centersNew design of emergency response facilities and supercomputing centers Worldwide Worldwide > 2000 isolated buildings in Japan Several hundred applications in China and Taiwan Widespread commercial and residential use

Obstacles to Use of Seismic Isolation in the United States Cost of devices and accessories Cost of devices and accessories Inability to convey benefits to building owners Inability to convey benefits to building owners Complex and inconsistent design code Complex and inconsistent design code Strict performance goals Strict performance goals Extensive testing and peer review Extensive testing and peer review Typical design office inexperienced and does not try to sell technology Typical design office inexperienced and does not try to sell technology

NEES TIPS Project (NSF Award No. CMMI ) Tools to Facilitate Widespread Use of Isolation and Protective Systems 4 year, $1.5 million, multi- institutional grant 4 year, $1.5 million, multi- institutional grant Shaking table and hybrid testing at SUNY Buffalo and UC Berkeley Shaking table and hybrid testing at SUNY Buffalo and UC Berkeley Full scale tests on world’s largest shake table, E-Defense, in Japan Full scale tests on world’s largest shake table, E-Defense, in Japan

NEES TIPS Project (NSF Award No. CMMI ) Tools to Facilitate Widespread Use of Isolation and Protective Systems 4 year, $1.5 million, multi- institutional grant 4 year, $1.5 million, multi- institutional grant Shaking table and hybrid testing at SUNY Buffalo and UC Berkeley Shaking table and hybrid testing at SUNY Buffalo and UC Berkeley Full scale tests on world’s largest shake table, E-Defense, in Japan Full scale tests on world’s largest shake table, E-Defense, in Japan

¼ scale test at UC Berkeley Full scale test at E- Defense, Japan

TIPS Project Objectives Fill knowledge gaps regarding modeling and performance Fill knowledge gaps regarding modeling 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 rate/scale dependent.

TIPS Project Objectives Fill knowledge gaps regarding modeling and performance Fill knowledge gaps regarding modeling 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 Objectives Reduce cost of using seismic isolation Reduce cost of using seismic isolation Component sensitivity studyComponent sensitivity study Configuration and detailing issuesConfiguration and detailing issues Improved static design procedure for regular buildingsImproved static design procedure for regular buildings Tools to meet performance goals Tools to meet performance goals High performance system testsHigh performance system tests Extend performance-based analysis tools to isolated buildingsExtend performance-based analysis tools to isolated buildings Needs assessment and professional participation Needs assessment and professional participation

Strategies for cost reduction Architectural detailing, electrical, plumbing to accommodate displacements Architectural detailing, electrical, plumbing to accommodate displacements Move isolation plane Move isolation plane

Strategies for cost reduction Simplified Design Simplified Design Isolator deformationIsolator deformation Distribution of static forcesDistribution of static forces Sensitivity study of devices to reduce need for testing Sensitivity study of devices to reduce need for testing Allow moderate yielding Allow moderate yielding

TIPS Project Objectives Reduce cost of using seismic isolation Reduce cost of using seismic isolation Component sensitivity studyComponent sensitivity study Configuration and detailing issuesConfiguration and detailing issues Improved static design procedure for regular buildingsImproved static design procedure for regular buildings Tools to meet performance goals Tools to meet performance goals High performance system testsHigh performance system tests Extend performance-based analysis tools to isolated buildingsExtend performance-based analysis tools to isolated buildings Needs assessment and professional participation Needs assessment and professional participation

Long term vision Vulnerability of isolated buildings to long period, high velocity pulses from very rare motions remains an issue. Vulnerability of isolated buildings to long period, high velocity pulses from very rare motions remains an issue. Smart structures and smart isolation systems that can tune their frequencies in real time. Smart structures and smart isolation systems that can tune their frequencies in real time.

Applications of Fractional Calculus Fractional Control Algorithms Fractional Control Algorithms Applied to fast hybrid testing of MR dampers (Abdollah Shafieezadeh)Applied to fast hybrid testing of MR dampers (Abdollah Shafieezadeh) Fractional Modeling of Seismic Isolation Bearings Fractional Modeling of Seismic Isolation Bearings

Modeling issues Amplitude dependence Amplitude dependence Frequency dependence Frequency dependence Strain hardening of high damping rubber Strain hardening of high damping rubber Cyclic degradation (recoverable and non-recoverable) Cyclic degradation (recoverable and non-recoverable)

Currently Currently Complex models – up to 10 parameters to be fittedComplex models – up to 10 parameters to be fitted Everyone uses bilinear modelsEveryone uses bilinear models Vision Vision Simpler models using fractional calculusSimpler models using fractional calculus Determine and capture essential effectsDetermine and capture essential effects Provide tools to fit models using database test dataProvide tools to fit models using database test data fbfb ubub Q kbkb k1k1