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Use of Advanced Technologies for Seismic Hazard Mitigation

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... civil engineering structures are designed for life safety in an earthquake. ... layers of rubber and steel Friction pendulum system allows the ... – PowerPoint PPT presentation

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Title: Use of Advanced Technologies for Seismic Hazard Mitigation


1
Use of Advanced Technologies for Seismic Hazard
Mitigation
  • Keri L. Ryan
  • Assistant Professor
  • Civil and Environmental Engineering
  • Utah State University

2
To meet minimum code standards, civil engineering
structures are designed for life safety in an
earthquake.
3
Many devices are available to protect structures
from earthquakes.
4
Seismic isolation and damping can reduce force
and displacement demands so structure remains
elastic or damage free
5
Seismic isolation reduces the forces transferred
to a structure by lengthening its natural period
Displacement
Period
k1,m1
k2,m2
6
Lead rubber bearings provide lateral flexibility
and weight carrying capacity with alternating
layers of rubber and steel
Bilinear model
7
Friction pendulum system allows the structure to
slide on a curved friction surface.
Bilinear model
8
Viscous or friction dampers dissipate energy to
reduce structural response.
9
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.
  • Control algorithms decide what magnetic field to
    apply.

10
Worldwide Scenario
  • United States
  • 80 isolated buildings and 60 buildings using
    dampers
  • Retrofit of landmark historic buildings
  • New design of emergency response facilities and
    supercomputing centers
  • Worldwide
  • gt 2000 isolated buildings in Japan
  • Several hundred applications in China and Taiwan
  • Widespread commercial and residential use

11
Obstacles to Use of Seismic Isolation in the
United States
  • Cost of devices and accessories
  • Inability to convey benefits to building owners
  • Complex and inconsistent design code
  • Strict performance goals
  • Extensive testing and peer review
  • Typical design office inexperienced and does not
    try to sell technology

12
NEES TIPS Project (NSF Award No. CMMI-0724208)
Tools to Facilitate Widespread Use of Isolation
and Protective Systems
  • 4 year, 1.5 million, multi-institutional grant
  • Shaking table and hybrid testing at SUNY Buffalo
    and UC Berkeley
  • Full scale tests on worlds largest shake table,
    E-Defense, in Japan

13
(No Transcript)
14
NEES TIPS Project (NSF Award No. CMMI-0724208)
Tools to Facilitate Widespread Use of Isolation
and Protective Systems
  • 4 year, 1.5 million, multi-institutional grant
  • Shaking table and hybrid testing at SUNY Buffalo
    and UC Berkeley
  • Full scale tests on worlds largest shake table,
    E-Defense, in Japan

15
¼ scale test at UC Berkeley
Full scale test at E-Defense, Japan
16
TIPS Project Objectives
  • Fill knowledge gaps regarding modeling and
    performance
  • Component characterization tests
  • Isolator and damper modeling
  • Performance limit states
  • Full scale testing
  • Worldwide information database

17
Isolator behavior is complex and rate/scale
dependent.
18
TIPS Project Objectives
  • Fill knowledge gaps regarding modeling and
    performance
  • Component characterization tests
  • Isolator and damper modeling
  • Performance limit states
  • Full scale testing
  • Worldwide information database

19
TIPS Project Objectives
  • Reduce cost of using seismic isolation
  • Component sensitivity study
  • Configuration and detailing issues
  • Improved static design procedure for regular
    buildings
  • Tools to meet performance goals
  • High performance system tests
  • Extend performance-based analysis tools to
    isolated buildings
  • Needs assessment and professional participation

20
Strategies for cost reduction
  • Move isolation plane
  • Architectural detailing, electrical, plumbing to
    accommodate displacements

21
Strategies for cost reduction
  • Simplified Design
  • Isolator deformation
  • Distribution of static forces
  • Sensitivity study of devices to reduce need for
    testing
  • Allow moderate yielding

22
TIPS Project Objectives
  • Reduce cost of using seismic isolation
  • Component sensitivity study
  • Configuration and detailing issues
  • Improved static design procedure for regular
    buildings
  • Tools to meet performance goals
  • High performance system tests
  • Extend performance-based analysis tools to
    isolated buildings
  • Needs assessment and professional participation

23
Long term vision
  • 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.

24
Applications of Fractional Calculus
  • Fractional Control Algorithms
  • Applied to fast hybrid testing of MR dampers
    (Abdollah Shafieezadeh)
  • Fractional Modeling of Seismic Isolation Bearings

25
Modeling issues
  • Amplitude dependence
  • Frequency dependence
  • Strain hardening of high damping rubber
  • Cyclic degradation (recoverable and
    non-recoverable)

26
  • Currently
  • Complex models up to 10 parameters to be fitted
  • Everyone uses bilinear models
  • Vision
  • Simpler models using fractional calculus
  • Determine and capture essential effects
  • Provide tools to fit models using database test
    data
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