new technologies in earthquake engineering - a summary

7/27/2019 New Technologies in Earthquake Engineering - A Summary

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UB CSEECIE 423 SPRING 2001

NEW TECHNOLOGIES IN

EARTHQUAKE ENGINEERING

- A SUMMARY




NEW TECHNOLOGIES

• Seismic isolation

♦ Location in structure (above foundation)

♦ Types of hardware♦ Sample applications

• Passive energy dissipation

♦ Location in structure (over height of structure)

♦ Types of hardware

♦ Sample applications

• Smart materials and semi-active control

♦ Controllable fluids and controllable solids




SEISMIC ISOLATION

Period lengthening

• isolator flexibility• period shift

• fixed base period

• isolated period

• force reduction

• displacement increase




SEISMIC ISOLATION

Displacements

• isolator flexibility• period shift

• isolator displacement

♦ energy dissipation

• building displacement

♦ damage reduction




SEISMIC ISOLATION

Energy dissipation• hysteretic

♦ high-damping rubber ♦ yielding of lead

♦ friction

♦ external hardware

§ hybrid systems

• viscous♦ high-damping rubber

♦ external hardware




ISOLATION HARDWARE

• Two classes in USA

♦ Elastomeric

§ Low-damping natural rubber (NR)

§ High-damping rubber

§ Lead-rubber (LR)

♦ Sliding

§ Friction Pendulum (FP)

§ FIP Industriale (FIP)

• Isolation of bridges

♦ Maximize energy dissipation

§ LR bearings

§ FP bearings

§ NR bearings with dampers




ISOLATION HARDWARE

• LR bearing




ISOLATION HARDWARE

• FP bearing




FULL-SCALE DYNAMIC TESTING• Large-size hardware

♦ Mission-critical

§ Buildings

§ Bridges§ Infrastructure

♦ Unknown reliability

♦ Velocity-dependentmechanical characteristics

♦ Degradation in responsewith repeated cycling due§ Damage

§ Heating




FULL-SCALE DYNAMIC TESTING• SRMD Test Machine

♦ Horizontal capacity

§ 4500 kN per actuator

§2500 mm stroke

§ 1.8 metres/sec

§ 19.3m3/min servovalves

♦ Vertical capacity

§ 72 MN

• Construction

♦ Mission-critical hardware§ Cyclic behavior

§ Degradation of response athigh speeds

§ Construction quality




FULL-SCALE DYNAMIC TESTING

• FP bearing test data

♦ Benecia-Martinez bridge

♦ Largest seismic isolators♦ Full-scale dynamic verification




IMPLEMENTATION OF ISOLATORS

IN INFRASTRUCTURE





IN INFRASTRUCTURE





IN BRIDGES

Benecia-Martinez Bridge

San Francisco Bay Area





IN BRIDGES

Kodiak, Alaska

Cold temperature application





IN BRIDGES

Rio Hondo Bridge

Los Angeles, California




ISOLATION IMPLEMENTATION

HISTORIC BUILDINGS

• San Francisco City Hall

♦ San Francisco

♦

LR bearings

• Court of Appeals Building

♦ San Francisco

♦

FP bearings





IN BUILDINGS

• Ataturk Airport

♦ Istanbul, Turkey

♦

FP bearings♦ Fluid viscous dampers

• AboveNet

♦ San Francisco

♦

FP bearings




PASSIVE ENERGY

DISSIPATION DEVICES

1. Displacement

2. Velocity

1a. Metallic-yielding damper 1b. Friction damper

Force

Displacement

Force

Displacement

Force

Displacement

Force

Displacement

2a. Viscoelastic damper 2b. Viscous damper

• Classification of damping hardware




PASSIVE ENERGY

DISSIPATION DEVICES

• Function of energy dissipation devices




METALLIC YIELDING DAMPERS

• Added Damping and Stiffness (ADAS)

♦ 1980s US technology

♦ concept based on work of Skinner and Kelly

• Triangular ADAS (TADAS)

♦ variant on ADAS

♦ patented in Taiwan but widely available

• Unbonded braces

♦ 1980s Japanese technology

♦ patented by Nippon Steel




ADAS DAMPERS




TADAS DAMPERS




UNBONDED BRACES




VISCOELASTIC DAMPERS

• Solid viscoelastic (VE) dampers

♦ 1960s technology for wind applications

♦ extended for seismic applications by Kelly, 3M, et al

• Fluid viscoelastic dampers

♦ viscous damping walls

♦ developed in Japan in 1980s and 1990s

• Fluid viscous dampers

♦ most popular in the United States at this time

♦ extension of DOD and DOE technologies




SOLID VE DAMPERS




FLUID VE DAMPERS




FLUID VISCOUS DAMPERS




SEMI-ACTIVE CONTROL

• MR fluid damper

♦ Notre DameMaximum current

Constant currentoperating curve

Zero current

Extension

Large force at small or zero

velocity is possible

Compression

Any arbitrary curve within

operational envelope ispossible

xc)xsgn()u(F p && +µ= xc)xsgn()u(F p && +µ=

F F

x &x &




SEMI-ACTIVE CONTROL

• 200 kN prototype damper

LORD

RheoneticTM Seismic Damper

MR-9000

3-Stage Piston

Diameter: 20 cmStroke: 16 cmPower: < 50 watts, 22 volts

Thermal ExpansionAccumulator

MR Fluid3-Stage Piston

Diameter: 20 cmStroke: 16 cm




FINISHED

new technologies in earthquake engineering - a summary

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