Seismic Design of Nonstructural Building Components
January 12-15, 2015
Quito, Ecuador
Chapter 10Introduction to Seismic Isolation and Dissipation
Seismic Design and Analysis of Nonstructural Components
Andre Filiatrault, Ph.D., Eng.
Seismic Design of Nonstructural Building Components
January 12-15, 2015
Quito, Ecuador
CONTENT
1. Fundamental Concepts
2. Categories of Supplemental Damping and Seismic Isolation Systems
3. Hysteretic Dampers
4. Viscous Dampers
5. Laminated Rubber Bearings
6. Lead-rubber Bearings
7. Friction Pendulum System
Seismic Design of Nonstructural Building Components
January 12-15, 2015
Quito, Ecuador
1. Fundamental Concepts
Basic performance objective of conventional seismic design: life safety
Life safety performance objective not sufficient for important structures
To increase seismic performance level at reasonable cost: supplemental damping and seismic isolation
Seismic Design of Nonstructural Building Components
January 12-15, 2015
Quito, Ecuador
Not
O.K.
O.K.
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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1. Fundamental Concepts
Supplemental Damping Systems:
Special devices mechanical dampers
Mechanical energy dissipation through heat by movements of the structural elements
Protect main structural elements
If all seismic energy dissipated mechanically: no damage
Seismic Design of Nonstructural Building Components
January 12-15, 2015
Quito, Ecuador
1. Fundamental Concepts
Seismic Isolation Systems:
Installation of isolators beneath supporting points of the structure
Buildings: isolators located between superstructure and foundation
Bridges: isolators located between deck and piers
Isolators have much lower lateral stiffness than superstructure
Isolators limit transfer of seismic energy to superstructure
If no seismic energy transmitted to superstructure: no damage
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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1. Fundamental Concepts
Components of Seismic Isolation Systems:
Isolator
Lateral stiffness much less than superstructure
Increase effective period of vibration
Sliding surface, rubber pad, etc.
Supplemental damping mechanism
Dissipate residual seismic input energy
Limits displacements of isolator
Reduces force transmitted to superstructure
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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1. Fundamental Concepts
Components of Seismic Isolation Systems:
Seismic Design of Nonstructural Building Components
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1. Fundamental Concepts
E-Defense Experiments: 5 story steel moment frame
Seismic Design of Nonstructural Building Components
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1. Fundamental Concepts
Illustrative Example
Seismic Design of Nonstructural Building Components
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Point A: original portal frame, T = 1.0 sec
Point B: portal frame with added viscous damper, z = 20%, T = 1.0 sec
Point C: portal frame with added hysteretic damper, z = 20%, T = 0.55 sec
Point D: portal with added bracing system, z = 5%, T = 0.55 sec
Point E: base isolated portal frame, z = 5%, T = 2.0 sec
Point F: base isolated portal frame, z = 20%, T = 2.0 sec
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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1. Fundamental Concepts
It is a combination of period shift and added energy dissipation that must be
considered jointly in order to fully understand the effectiveness of added
supplemental damping devices and/or base isolation systems on the seismic
response of a structure.
Note: Behavior and analysis more complex if structure undergoes
inelastic deformations
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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2. Categories of Supplemental Damping and Seismic Isolation Systems
Discussed in this presentation
Seismic Design of Nonstructural Building Components
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3. Hysteretic Dampers
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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3. Hysteretic Dampers
Metallic Dampers
Hysteretic Behaviour of Yielding Steel Elements
Seismic Design of Nonstructural Building Components
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3. Hysteretic Dampers Metallic Dampers
Geometrical Considerations Metallic dampers can be used as part of chevron bracing systems.
Yielding devices dissipate energy through relative horizontal. displacement between apex of chevron and above floor level.
If metallic plates used, act as fixed-fixed beams.
To distribute inelastic strains, it is desirable that plastic moment at any section be reached simultaneously.
Geometry of the device must be optimized.
Seismic Design of Nonstructural Building Components
January 12-15, 2015
Quito, Ecuador
3. Hysteretic Dampers Geometrical Considerations
Seismic Design of Nonstructural Building Components
January 12-15, 2015
Quito, Ecuador
Geometrical Considerations
3. Hysteretic Dampers
Seismic Design of Nonstructural Building Components
January 12-15, 2015
Quito, Ecuador
Geometrical Considerations
3. Hysteretic Dampers
Seismic Design of Nonstructural Building Components
January 12-15, 2015
Quito, Ecuador
Geometrical Considerations
3. Hysteretic Dampers
Seismic Design of Nonstructural Building Components
January 12-15, 2015
Quito, Ecuador
Experimental Studies Added Damping - Added Stiffness Systems (ADAS)
System Testing (Whittaker et al. 1991)
3. Hysteretic Dampers
Video
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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Experimental Studies Triangular Added Damping Added Stiffness (TADAS) Systems
Developed by Tsai et al. (1993).
Variation of ADAS system using triangular metallic plate dampers.
Triangular plates rigidly welded to a top plate but simply connected to a slotted base.
Main advantages of TADAS:
Not affected by gravity loads because of slotted holes in base plate.
No rotational restraint required at the top of the brace connection assemblage.
Disadvantages of TADAS:
Construction more complicated.
Careful welding required.
3. Hysteretic Dampers
Seismic Design of Nonstructural Building Components
January 12-15, 2015
Quito, Ecuador
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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Experimental Studies Cast Steel Yielding Fuse For
Concentrically Braced Frames
Developed by Gray et al. (2010) at the University of
Toronto, Canada.
Ductile cast steel connector in a concentrically braced
frame.
Seismic energy dissipated through inelastic flexural
yielding of specially designed
yielding elements similar to
TADAS elements in the cast
connector.
3. Hysteretic Dampers
http://www.youtube.com/watch?v=TAXpwimvbjA
Seismic Design of Nonstructural Building Components
January 12-15, 2015
Quito, Ecuador
Experimental Studies Cast Steel Yielding Fuse For
Concentrically Braced Frames
Main advantages:
No welding or bolting in the connector.
Stable hysteretic response with tension
stiffening at large
displacements.
Main disadvantage:
Cost?
Tested at full-scale at the University of Toronto.
3. Hysteretic Dampers
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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Experimental Studies Lead Extrusion Devices (LED)
Developed in the mid-1970s in New Zealand (Robinson and Greenbank 1976).
Metallic dampers that take advantage of extrusion of lead through orifices.
Two different types of LED devices: constricted tube and bulged shaft.
3. Hysteretic Dampers
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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Experimental Studies Lead Extrusion Devices (LED)
Component Testing
3. Hysteretic Dampers
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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Experimental Studies Lead Extrusion Devices (LED)
Desirable characteristics of LED dampers:
Hysteretic behaviour is stable and repeatable and is unaffected by number of load cycles.
Environmental factors have no significant influence on the behaviour.
Fatigue is not a major concern since lead is hot worked at room temperature.
Strain rate has only a minor effect on the hysteretic response.
Tests have demonstrated insignificant aging effects.
3. Hysteretic Dampers
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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Experimental Studies Buckling Restrained Braces (BRB) / Unbonded Braces
Originally manufactured by Nippon Steel Corporation in Japan.
Steel core plate encased in a steel tube filled with concrete.
Steel core carries the axial load while the outer tube, via the concrete, provides lateral support to the core and prevents global
buckling.
Thin layer of lubricating material at the concrete interface.
Cyclic qualification tests included in AISC Seismic Requirements.
3. Hysteretic Dampers
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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Experimental Studies Buckling Restrained Braces (BRB) / Unbonded Braces
3. Hysteretic Dampers
http://www.youtube.com/watch?v=_jUJ8Jv1ZPg
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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Structural Implementations
3. Hysteretic Dampers
Unbonded Braces inNew 4-story Central Dining Facility
Stanley HallUC Berkeley, 2003
Photo: Courtesy of M. Constantinou
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Friction Dampers
Studies on the Variation of Coefficient of Friction for Metal-Metal Interfaces Tremblay and Stiemer (1993)
3. Hysteretic Dampers
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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Friction Dampers
Studies on the Variation of Coefficient of Friction for Metal-Metal Interfaces Grigorian et al. (1993)
3. Hysteretic Dampers
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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Existing Friction Damping Systems Slotted-Bolted Connections
Simplest form of friction dampers.
Slotted-bolted connections at the ends of conventional bracing members.
To maintain constant slip load, disc spring washers can be used.
3. Hysteretic Dampers
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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Existing Friction Damping Systems Slotted-Bolted Connections
3. Hysteretic Dampers
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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Existing Friction Damping Systems Sumitomo Friction Device (Sumitomo Metal Industries Ltd.,Japan)
More sophisticated friction device.
Incorporates a pre-compressed internal spring that induces a force that is converted through the action of inner and outer wedges into a
normal force on copper alloy friction pads containing graphite plug
inserts for lubrication.
3. Hysteretic Dampers
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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Existing Friction Damping Systems Pall Friction Device (Pall Dynamics Ltd., Canada)
Most implemented friction damping system.
Designed to be mounted in a moment-resisting framed structure.
Mechanism containing slotted slip joints introduced at intersection of frame cross-braces.
3. Hysteretic Dampers
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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Existing Friction Damping Systems Pall Friction Device (Pall Dynamics Ltd., Canada)
3. Hysteretic Dampers
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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Existing Friction Damping Systems Pall Friction Device (Pall Dynamics Ltd., Canada)
3. Hysteretic Dampers
Seismic Design of Nonstructural Building Components
January 12-15, 2015
Quito, Ecuador
Existing Friction Damping Systems Pall Friction Device (Pall Dynamics Ltd., Canada)
3. Hysteretic Dampers
Seismic Design of Nonstructural Building Components
January 12-15, 2015
Quito, Ecuador
Existing Friction Damping Systems Pall Friction Device (Pall Dynamics Ltd., Canada)
3. Hysteretic Dampers
Seismic Design of Nonstructural Building Components
January 12-15, 2015
Quito, Ecuador
Existing Friction Damping Systems Pall Friction Device (Pall Dynamics Ltd., Canada)
3. Hysteretic Dampers
Seismic Design of Nonstructural Building Components
January 12-15, 2015
Quito, Ecuador
Existing Friction Damping Systems Pall Friction Device (Pall Dynamics Ltd., Canada)
3. Hysteretic Dampers
Video
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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Structural Implementations
3. Hysteretic Dampers
Concordia University Library,
Montreal, Canada, 1991
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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Structural Implementations
3. Hysteretic Dampers
Freeport Water Tower, Sacramento,
CA, 1999
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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Structural Implementations
3. Hysteretic Dampers
Boeing Plant, Seattle, Washington,
2001
Seismic Design of Nonstructural Building Components
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4. Viscous Dampers
Linear Viscous Dampers
Hysteretic Response
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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4. Viscous Dampers
Nonlinear Viscous Dampers
Fluid type dampers can be designed to behave as nonlinear viscous elements by adjusting their silicone oil and orificing characteristics.
Main advantage of nonlinear viscous dampers is that in the event of a velocity spike, the force in the viscous damper is controlled to avoid overloading the damper or the bracing system to which it is connected.
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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4. Viscous Dampers
Nonlinear Viscous Dampers
Seismic Design of Nonstructural Building Components
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Photo: Courtesy of M. Constantinou
4. Viscous Dampers Typical fluid dampers incorporate a stainless steel piston with a
bronze orifice head.
Device filled with silicone oil.
Piston head utilizes specially shaped orifices that alter flow characteristics with fluid relative velocity.
Force produced by damper is generated by the pressure differential across piston head.
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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4. Viscous Dampers Various structural models, with and without fluid dampers
manufactured by Taylor Devices Inc., tested on the shake table at the University at Buffalo from 1991 to 1995.
e.g. 1/4 scale 3-storey test structure (Constantinou et al. 1993).
Model had weights = 28.5 kN distributed equally on the three floors.
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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4. Viscous Dampers
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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4. Viscous Dampers
Seismic Design of Nonstructural Building Components
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Seismic Design of Nonstructural Building Components
January 12-15, 2015
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4. Viscous DampersWoodland Hotel, Woodland, CAFour-story reinforced concrete/shear
wall buildingConstructed in 192716 Taylor Dampers installed
horizontally Capacity of each damper = 100 kips
Seismic Design of Nonstructural Building Components
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4. Viscous DampersSan Francisco Civic Center
292 Fluid Viscous Dampers Installed In Line
Courtesy of M. Constantinou
Seismic Design of Nonstructural Building Components
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YERBA-BUENA TOWER, SAN FRANCISCO
37-STORY WITH REVERSE UPPER TOGGLE
SYSTEM. UNDER CONSTRUCTION 2001.
20 FLUID DAMPERS IN UPPER STORIES.
Courtesy of M. Constantinou
4. Viscous Dampers
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January 12-15, 2015
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4. Viscous Dampers
OLYMPIC COMMITTEE BUILDING, CYPRUS
3-STORY, V-SHAPED IN PLAN
52 SCISSOR-JACK ASSEMBLIES
COMPLETED JULY 2006 Courtesy of M. Constantinou
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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5. Laminated Rubber Bearings
Laminated rubber bearings (elastomeric bearings) used extensively for bridge superstructures to accommodate temperature-induced movements deformations.
In last 20 years, use extended to seismic isolation of buildings and other structures.
Lead-rubber (lead-plug) bearing: Elastomeric bearing with central lead plug designed to
yield under lateral deformation and to dissipate supplemental energy.
Discussed in next section.
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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5. Laminated Rubber Bearings
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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Laminated elastomeric bearings in a bridge
5. Laminated Rubber Bearings
Seismic Design of Nonstructural Building Components
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400 laminated elastomeric bearings and
186 Taylor viscous dampers with
displacement capacity of 600 mm.
San Bernardino Hospital, California, 1993
5. Laminated Rubber Bearings
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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5. Laminated Rubber Bearings
Photo: Courtesy of M. Constantinou
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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5. Laminated Rubber Bearings
Image T. Saito
Seismic Design of Nonstructural Building Components
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5. Laminated Rubber Bearings
Elastomeric Bearings for Sakhalin I Orlan Platform.
Tested at University at Buffalo.
Photos: Courtesy of M. Constantinou
Gravity Test Shear Test
Seismic Design of Nonstructural Building Components
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5. Laminated Rubber Bearings Force-Displacement relationship for various
types of elastomeric bearings
Shear strain defined as lateral displacement/total height of rubber
(From Thompson et al. 2000)
High Damping Rubber
Lead Rubber
Low Damping
Scragging
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5. Laminated Rubber Bearings
Full-Scale Isolated Bridge Testing
Video
Seismic Design of Nonstructural Building Components
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5. Laminated Rubber Bearings
Full-Scale Isolated Bridge Testing
-1.5 -1 -0.5 0 0.5 1 1.5-4
-3
-2
-1
0
1
2
3
4
Uy (in)
F (kip
)
Force-Displacement Hysteresis - Side A
LC6 vs D5
-5 -4 -3 -2 -1 0 1 2 3 4 5-4
-3
-2
-1
0
1
2
3
4
Uy (in)
F (
kip
)
Force-Displacement Hysteresis-Side B
LC2 vs D9
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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5. Laminated Rubber Bearings Disadvantage of Laminated Rubber Bearings:
Relatively low damping provided by the rubber.
High damping rubbers: Developed for laminated rubber bearings.
Used mainly in Japan (Pan et al. 2004).
Significant more energy dissipation than low damping rubbers.
20% damping at shear strains of 300%.
More susceptible to heat related property changes during cyclic loading and to aging effects.
Increases complexity to predict short and long term properties for bounding analysis.
Isolator damping external components: Lead plug inserted in center of the bearing (lead-rubber bearings).
External supplemental damping by hysteretic or viscous dampers.
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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6. Lead-rubber Bearings
Lead-rubber bearing composed of a laminated-rubber bearing with a cylindrical lead plug inserted in it center.
Lead plug introduced to increase damping by hysteretic shear deformations of the lead.
Photo: Courtesy of M. Constantinou
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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6. Lead-rubber Bearings
Reasons to use lead for central plug:
At room temperature, lead behaves as elastic-plastic solid.
Yields in shear at low stress of about 10 MPa.
Lead is hot-worked at room temperature.
Properties continuously restored when cycled in inelastic range.
Very good fatigue resistance properties.
Lead commonly available since used in batteries at purity level of more than 99.9%
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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6. Lead-rubber Bearings
Properties of Lead-Rubber Bearings
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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6. Lead-rubber Bearings SRMD Testing Machine, UC-San Diego
DIS LR Bearing, Vertical Load = 558 kips, Displacement = 22 in, velocity = 60 in/s
Seismic Design of Nonstructural Building Components
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6. Lead-rubber Bearings SRMD Testing Machine, UC-San Diego
DIS LR Bearing, 400% strain
Seismic Design of Nonstructural Building Components
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6. Lead-rubber Bearings Failure Test, NIED, Tsukuba, Japan
Seismic Design of Nonstructural Building Components
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7. Friction Pendulum System General Description
FPS manufactured by Earthquake Protection Systems (EPS), Richmond, California.
Friction-type sliding bearing using gravity as restoring force.
Seismic Design of Nonstructural Building Components
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7. Friction Pendulum System
General Description
Articulated friction slider traveling on spherical concave lining surface.
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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7. Friction Pendulum System General Description
Photo: Courtesy of M. Constantinou
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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7. Friction Pendulum System General Description
Slider on concave surface to provide re-centering capabilities through gravity Friction Pendulum bearing shown below
Typically PTFE on polished stainless steel surface
Seismic Design of Nonstructural Building Components
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7. Friction Pendulum System
Salkhalin II offshore gas platform bearings.
Largest seismic isolators.
700mm displacement.
87,400kN vertical load.
Full-scale testing
Reduced scale dynamic testing (load of up to
13,000kN, velocity of 1m/sec).
Photo: Courtesy of M. Constantinou
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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FPS Isolator, Vertical Load = 3490 kips, Displacement = 29 in, velocity = 53 in/s
Seismic Design of Nonstructural Building Components
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7. Friction Pendulum System
New International Terminal
San Francisco International Airport
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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7. Friction Pendulum System
HAYWARD CITY HALL, CALIFORNIA
NEXT TO HAYWARD FAULT
53 FP BEARINGS AND 15 NONLINEAR
VISCOUS DAMPING DEVICES
600 mm DISPLACEMENT CAPACITY
Courtesy of M. Constantinou
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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7. Friction Pendulum System
KODIAK, ALASKA
COLD TEMPERATURE APPLICATION
-40 DEG TEMPERATURE, STRONG WIND
Courtesy of M. Constantinou
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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Properties of Frictionless Pendulum System
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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Properties of Frictionless Pendulum System
Seismic Design of Nonstructural Building Components
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7. Friction Pendulum SystemShake table tests of a full-scale 5-story steel moment frame building (PI: K. Ryan, Reno; S. Mahin, Berkeley; G. Mosqueda, San Diego)
triple friction pendulum isolators
lead rubber bearing/cross linear slider
Fixed base
o Simulations designed to impose large displacement demands in isolation systems
o Simulations both with and without vertical component of ground motion
o 4th and 5th floor included nonstructural systems
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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7. Friction Pendulum System
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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7. Friction Pendulum System
Seismic Design of Nonstructural Building Components
January 12-15, 2015
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E-Defense Experiments: 5 story steel moment frame
Measured response
7. Friction Pendulum SystemLe
vel
Peak Acceleration Profile
Peak Acc. (g)
50 60 70 80 90 100
-0.5
0
0.5
-0.48446
-0.11864
0.14598
Fixed Base
TPB Isolated
LRB Isolated
50 60 70 80 90 100
-0.5
0
0.50.5844
0.14362
-0.23067
Base Shear Coefficient
X-d
ire
ctio
nY
-dir
ect
ion
Time (sec)
Seismic Design of Nonstructural Building Components
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Quito, Ecuador
Questions/Discussions