Viscous Dampers Save Structures From Earthquake Damage 7-2013 (1)

7/29/2019 Viscous Dampers Save Structures From Earthquake Damage 7-2013 (1)

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Jul 2013

Viscous Dampers Save Steel

Struc tures from Earthquake Damage

By

David Lee, Ph.D.West Coast Technical Director

Taylor Devices, In.

And

Douglas P. TaylorPresident

Taylor Devices, Inc.

____________________________________________________________________________

(A copy of this report can be downloaded for personal use from www.steeltips.org)


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Viscous Dampers Save Structures from Earthquake Damage

By: David Lee, Ph.D. and Douglas P. Taylor

Viscous dampers now protect over 450 structures throughout the world from earthquakes.These dampers cut drift in half, greatly reduce shear forces, and make structures safe for theircontents by reducing shaking to only 25 or 30% of what happens in unprotected structures.

Structural Engineers can now design structures with immediate occupancy after a major event,at no additional cost over basic code design. The dampers decrease loads enough tosignificantly reduce the amount of steel and concrete, enough to offset the cost of the dampers.The added protection is essentially free.

Refurbishment of existing structures with dampers is often the least costly way to provideseismic protection. Taylor Devices can lower insurance premiums significantly, and greatlylessen the probability of lost income.

Viscous dampers have been used on well over 450 structures. A list is included in this paper asan Appendix. Some sample projects are described in this report, along with the story of howall this happened.

First Printing, July 2013.

__________________________________________________________________________________Douglas P. Taylor, President. Taylor Devices, Inc.. 90 Taylor Drive,. North Tonawanda, NY14120. [email protected] Web Site www.taylordevices.com

____________________________________________________________________________________________ David Lee, Ph.D., West Coast Technical Director, Taylor Devices, Inc, 2112

Disclaimer: The information presented in this publication has been prepared in accordance with recognized engineering

principles and is for general information only. While it is believed to be accurate, this information should not be used or

relied upon for any specific application without competent professional examination and verification of its accuracy,suitability, and applicability by a licensed professional engineer, designer or architect. The publication of the material

contained herein is not intended as a representation or warranty on the part of the Structural Steel Educational Council or

of any other person named herein, that this information is suitable for any general or particular use or of freedom from

infringement of any patent or patents. Anyone making use of this information assumes all liability arising from such use.

Caution must be exercised when relying upon specifications and codes developed by others and incorporated by reference

herein since such material may be modified or amended from time to time subsequent to the printing of this document. The

Structural Steel Educational Council or the authors bear no responsibility for such material other than to refer to it and

incorporate it by reference at the time of the initial publication of this document.
mailto:[email protected]:[email protected]:[email protected]


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ACKNOWLEDGMENTS

The publication of this report was made possible in part by the support of the Structural Steel

Educational Council (SSEC).

The authors wish to thank Michael Constantinou, Ph.D. of the State University of New York,Buffalo Campus, for all his help in making structural dampers a reality. We also wish to thankall the good people of Taylor Devices, Inc. for their past and continuing work in developingnew and better viscous dampers, and for keeping up with the steadily increasing demand.


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Viscous Dampers Save

Struc tures from Earthquake Damage

By:

David Lee, Ph.D., West Coast Technical Director, Taylor Devices,

Inc.

Douglas P. Taylor, President, Taylor Devices, Inc.

__________________________________________________

TABLE OF CONTENTS

ABSTRACT / Page 1

ACKNOWLEDGMENTS / Page 2

TABLE OF CONTENTS / Page 3

INTRODUCTION/ Page 4

CHAPTER 1. BUILDINGS/ PAGE 4

CHAPTER 2. BRIDGES/ PAGE 9

CHAPTER 3. OTHER PROJECTS/ PAGE 12

CHAPTER 4. THE HISTORY OF VISCOUS DAMPERS IN STRUCTURES/ PAGE 13

REFERENCES / Page 18

ABOUT THE AUTHOR(S) / Page 19

LIST OF PUBLISHED STEEL TIPS REPORTS / Page 20

_________________________________________________________________________


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1.Introduction

The addition of viscous dampers to an existing structure can providesignificantly improved seismic performance. Seismic shaking of two to fourtimes code maximum will cause cosmetic damage only, permittingimmediate occupancy after an event. Both analysis and tests referenced inthis report show these results.

Incorporation of viscous dampers in a new structure provides similar levels ofprotectionthe ability to withstand two to four times maximum expected

shaking with only cosmetic damage. There is another benefit as wellit is

possible with correct design to reduce the amount of steel in the structureenough to offset the cost of the dampers. The owner gets a building that ishighly resistant to earthquakes at no additional costpossibly even a cost savings.

Viscous dampers soak up the earthquake energy so the steel in the structureno longer needs to bend back and forth and yield, or at least not nearly asmuch. The beams and columns no longer need to yield and heat up, like a

paper clip that is bent back and forth repeatedly as it absorbs energy. A

building without dampers is like a car with bad shocksit bounces around alot in an earthquake. The viscous dampers smooth out the ride.

Viscous dampers have been used on well over 450 structures. A list isincluded here as a link(http://taylordevices.com/pdf/StructuralChart2010.pdf)Here is another link that leads to almost 100 technical papers showingvarious applications, analyses and tests of viscous dampers for structures.(http://taylordevices.com/literature.html) Some sample projects are describedin this report.

Chapter 1

Buildings that use Viscous Dampers

Colorado Center in Santa Monica, California


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The Colorado Center has six steel framebuildings, built in the 80s and 90s.All six of these three to six story buildings have been refurbished withdampers to make them earthquake resistant per todays requirements. Both

the buildings and the occupants are now protected.

James and Ken Lord of Lord Ficks Zayed and Associates, the structuralengineers on this project, did a fine job in designing the earthquakestrengthening of this building. They had to install dampers in a number ofdifficult locations. Here are some of them:


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In the loading dock


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In the Dry Cleaning Shop In the Fitness Center

Our thanks to Barrett Stone (senior property manager) and Alan Gaskell

(chief engineer) for all their help with this project.

Arrowhead Regional Medical Center

Formerly the San Bernardino Hospital, the new Arrowhead Regional MedicalCenter is in Colton, California near the intersection of three major faults.Five separate buildings, all on elastomeric base isolators. The predictedseismic induced displacement of +/- four feet was too much at that time notonly for the isolators, but also for the movable walkways between buildings

and the utilities that feed the buildings. Our dampers reduced this motion to alittle under +/- two feet, which was acceptable.


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These dampers were the largest that we had made at that time320 kips.Now our limit is around 2000 kips, and the limitation is the size of high alloysteel tubing that can be extruded. If we could get bigger tubes we couldmake even larger dampers. Heres what the installation looks like:


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Doug Taylor, president of Taylor Devices, is very proud of our performanceon this project. His foot points to the first prototype unit that we made. It

passed all qualification and life cycle tests required by both the owner andOSHPD. Later it was delivered to the job site and put on display outside one

of the buildings. You can tour the installation if you wish.

Chapter 2

Two Bridges that use viscous dampers

The Millennium pedestrian bridge across the Thames in London is possiblythe most beautiful pedestrian bridge in the world. It is a suspension bridge,and the suspension cables are highly angled instead of vertical. The bridge


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had to be closed two days after opening. It shook so badly that people werefalling down.

The bridge designers acted quickly and efficiently to find a way to correctthis problem. After a lot of consideration they decided to add viscousdampers to eliminate the shaking. The dampers block the vibration but still

permit thermally induced deformations. They work perfectlyvibration was

reduced by a factor of 40/1.

The dampers that we supplied are very special. They dont have our standard

lip type seals, but instead use a labyrinth seal with no friction and no rubbing

surfaces. Metal bellows contain the fluid, so there is infinite life andessentially zero friction, which is perfect for this bridge.

Some of the Taylor seismic dampers are immense. The Sutong Bridge inChina has some of the biggest dampers that we have ever made. It is thelongest cable stay bridge in the world.


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The Sutong Bridge dampers, besides being huge, are special in another way.They have elastomer springs at each end of travel, to provide extra seismic

protection. This feature can be added to any of our dampers. The spring canalso be continuous, so it acts throughout the stroke. Our spring dampers canadd stiffness to a structure as well as viscous damping.


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Chapter 3

Some Very Special Dampers

Boat Seat Shock Absorber

The boats that transport the Navy Seals are very fast, and very rough. Sorough that the Seals cant take it for more than eight hours at a time, andsometimes get injured. We designed a shock absorbing seat that makes theride as smooth as a luxury sedan.

The Negative Spring

Not content with the successful application of structural damping, andinventing a bunch of other amazing things, Dr. Constantinou recently createda new way to mitigate earthquakesthe negative spring. Taylor Devices

designed the mechanism to do this. A conventional spring pushes back. Themore it deflects, the harder it pushes back to its neutral position. A negative

spring does the reversethe more it moves away from neutral, the more itpushes itself away from its center point. By itself a negative spring is veryunstable, something like a cocked mousetrap. Add it to a structure and the

period gets longer, moving the base resonance away from the earthquakefrequency. Heres a picture of some of the testing of this remarkable

concept:


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Chapter 4

The History of Viscous Dampers in Structures How it all happened

Viscous dampers now protect over 450 structures throughout the world fromearthquakes. These dampers cut drift in half, greatly reduce shear forces, andmake structures safe for their contents by reducing shaking to only 25 or 30%of what happens in unprotected structures.

20 years ago no one had heard of viscous dampers for structures. Now theyare a standard way to protect structures. How did this happen?

We owe it all to the MX missile, that huge nuclear deterrent of the 1970s and1980s that carried multiple warheads. Authorized by President Carter in1972 and cancelled years later by President Reagan as sort of a mercy

killing, due to the demise of the Soviet Union and the end of the Cold War.During its life a number of very freaky basing modes were seriouslyevaluated. One was known as Deep Base MX.


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First find a huge mesa with a large flat top and hollow it out. Then fill theinterior caves with MX missiles & support equipment, plus huge tunnelingmachines. Now wait for Armageddon. After a nuclear attack the tunnelingmachines bore out 15 degree inclined exit tunnels, clearing the way to the

outside walls of the mesa. Then drive huge transporter erector missilesthrough the tunnels to the outside, tilt the MX missiles to vertical, and fireaway. Heres a picture:

Naturally all the equipment inside the mesa had to be protected from nuclearblast. So the Air Force gave us a small contract for a preliminary design of anumber of shock isolation systems.

The State of New York at that time had a grant program for any companydoing SBIR (Small Business Innovative Research). All we needed to gettheir $25,000 gift was a one page description of how we would use themoney. We used it to develop seismic dampers.

Our first step was to find a University to work with us. CalTech was notinterested because they did not work with the nuts and bolts of seismic

protection. Cal Berkeley was overloaded with other work. But Dr. MichaelConstantinou, a newcomer to State University of New York Buffalo Campuswas happy to work with us. He was doing research at that time on addeddamping for seismic protection. He found that damping greatly increased


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earthquake resistance. But the visco-elastic dampers he had been usingstiffened up at the velocities encountered in many earthquakes. The Taylordampers were good at high speeds- even the 30 ft/sec ground shaking speedsassociated with nuclear weapons detonations. This allowed much higher

damping ratios to be used. Dr. Constantinous first experiments using ourdampers were with 25% damping- with dramatic improvement over earlierapproaches. In most cases, the simple addition of dampers "borrowed" fromthe US nuclear missile programs offered a reduction of seismic loads within asteel building structure of a factor of nearly three- with no changes needed tothe structure itself. Heres an early test:

The tests showed that Dr. Constantinous predictions were correct; dampersreduced drift by 50% or more, and reduced inter-story shear by about thesame amount.

We then received an even larger contract for detail design of the Deep Baseisolators, which we completed. Then the program was dropped. Something


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to do with cost, and the fact that every tunneling machine in the world wouldstill not be near enough.

An even wilder MX basing scheme was the Carter plan, which had 400

missiles scattered amongst 4000 identical launch buildings that wereconnected by roads. The missiles could be shuffled from one launch buildingto another so no one could tell which ones were which. This confused theenemy. There were too many potential missile sites to attack all at once.

Later, under Secretary of Defense Casper Weinberger, the number of siteswas greatly reduced, and they were all located in a small area. This wascalled Dense Pack. The idea here was to have such massive retaliatory powerthat no one would dare attack us. If they did attack, the nuclear blasts from

that many warheads would cause fratricidethey would detonate each otherrelatively harmlessly. Fortunately this was never tested. It was not one ofour brightest defense plans.

Around that time we did a lot of work on nuclear blast protection for missiles.We designed and built and tested( without nuclear explosions, of course) fullsize prototype dampers for Mobile Minuteman ( Minuteman IV, fore-runnerto MX), as well as the Dense Pack and Multiple Protective Shelter systems.

At the same time we were in full scale production of dampers for US Navyship based nuclear missiles- with more than 23,000 dampers manufacturedfor the Navy during the Cold War years.

The Dense Pack shock absorbers were our greatest challenge. These dampershad a piston rod that was more than 20 feet long. This was what we neededto protect the missiles against nuclear blast. We had very limited space, as

both the silos and the launch buildings had already been designed. We had ahuge ground shock input, and only limited rattle space. It took everything we

had to come up with an isolation system.

Heres what we came up with for the earlier Carter system. These dampers

had 4 feet of stroke, and were the basis for the dampers that we built for theSan Bernardino Medical Center, which was described earlier.


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These were very big dampers, especially at that time. But, by coincidence,just about right for huge buildings and bridges. So when the need developed

to protect structures from earthquakes, we were ready. In fact, designingdampers for earthquake protection of structures was much easier thatdesigning dampers for nuclear blast. We have now installed Taylor Damperson over 450 projects.

References

Here is a link that leads to over 100 technical papers showing variousapplications, analyses and tests of viscous dampers for structures.

http://taylordevices.com/literature.html


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About the Authors:

David Lee, Ph.D. is West Coast Technical Director for Taylor Devices,Inc. He has invented a number of novel viscous damper configurations,and has published 12 technical papers in this field. He manages theWest Coast technical operations and marketing for Taylor Devices.

Douglas P. Taylor is president of Taylor Devices Inc., located in NorthTonawanda, NY. He has held this position since 1991. He has beenwith Taylor Devices since 1965.

At the end of the Cold War in 1990 Mr. Taylor conceived anddeveloped the concept of using large damping devices from U.S.Ballistic Missile Programs for earthquake protection of buildings and

bridges. This technology transfer to the private sector has proven highlysuccessful, and Mr. Taylor's contributions in this area have beenacknowledged as significant by the U.S. Department of Defense. DougTaylor has over 30 patents relating to viscous dampers, has publishedover 55 technical papers, and has won many awards.


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List of Published Steel TIPS Reports--------------------------------------------------------------------------------------------------------------------

--------------------July '13: The Manufacture and Supply of Structural Steel by Max D. Powell

July '11: Steel Plate Shear Walls-Performance Based Design by Nabih Youssef, Ryan Wilkerson and Daniel Tunick

July '11: Welding of Seismically-Resistant Steel Structures by Duane K. Miller

April '11: Notes on Gusset Plates in Steel Trusses-Evaluation, Repair and Retrofit by Abolhassan Astaneh-Asi and

Wahid Tadros

March '11: The Design of Continuity Plate Welds in Special Moment Frames by Chia-Ming Uang, Andy Tran and

Patrick M. Hassett

May 10: Notes on Blast Resistance of Steel and Composite Building Structures, by Abolhassan Astaneh-Asl.

April 10: Gusset Plates in Steel Bridges-Design and Evaluation, by Abolhassan Astaneh-Asl.

April 10: Steel Plate Shear Walls: An Option for Lateral Resistance in High-Rise Core Wall Buildings, by James O.

Malley

Dec.09: Economy of Steel-Framed Buildings for Seismic Loading, by Christopher Hewitt, Rafael Sabelli, and

Jayson Bray.

Oct.08: A Comparison of Frame Stability Analysis Methods in AISC 360-05, by Charles J. Carter and

Louis F. Gerschwinder.Sept.08: Quality Assured Steel Bridge Fabrication and Erection, by Jay P. Murphy

June 08: Seismic Behavior and Design of Base Plates in Braced Frames, by Abolhassan Astaneh-Asl.

April 08: Cost-Effective Steel Bridge Fabrication and Erection, by Jay P. Murphy.

June 07: Early California Accelerated Steel Bridge Construction, by Jay P. Murphy.

June 07: Design of RBS Connections for Special Moment Frames, by Kevin S. Moore and Joyce Y. Feng.

May 07: Progressive Collapse Prevention of Steel Frames with Shear Connections, by Abolhassan Astaneh-Asl.

Jan.07: Seismic Detailing of Special Concentrically Braced Frames, by Abolhassan Astaneh-Asl, Michael Cochran,

and Rafael Sabelli.

Aug. 06: Alfred Zampa Memorial Steel Suspension Bridge, by Alfred Mangus, Sarah Picker

July 06: Buckling & Fracture of Concentric Braces Under Inelastic Loading, by B. Fell, A. Kanvinde, G. Deierlein, A.

Myers, and X. Fu.

Aug. 05: Steel Angle & Tee Connections for Gravity and Seismic Loads, by Abolhassan Astaneh-Asl.

May 05: Design of Shear Tab Connections for Gravity and Seismic Loads, by Abolhassan Astaneh-Asl.

Jul. 04: Buckling Restrained Braced Frames, by Walterio A. Lopez and Rafael Sabelli.

May 04: Special Concentric Braced Frames, by Michael Cochran and William Honeck.

Dec. 03: Steel Construction in the New Millennium, by Patrick M. Hassett.

Aug.02: Cost Consideration for Steel Moment Frame Connections, by Patrick M. Hassett and James J. Putkey.

June 02: Use of Deep Columns in Special Steel Moment Frames, by Jay Shen, Abolhassan Astaneh-Asl and

David McCallen.

May 02: Seismic Behavior and Design of Composite Steel Plate Shear Walls, by Abolhassan Astaneh-Asl.

Sept. 01: Notes on Design of Steel Parking Structures Including Seismic Effects, by Lanny J. Flynn, and Abolhassan

Astaneh-Asl.

Jun '01: Metal Roof Construction on Large Warehouses or Distribution Centers, by John L. Mayo.

Mar. 01: Large Seismic Steel Beam-to-Column Connections, by Egor P. Popov and Shakhzod M.Takhirov.

Jan 01: Seismic Behavior and Design of Steel Shear Walls, by Abolhassan Astaneh-Asl.Oct. '99: Welded Moment Frame Connections with Minimal Residual Stress, by Alvaro L. Collin and James J.

Putkey.

Aug. '99: Design of Reduced Beam Section (RBS) Moment Frame Connections, by Kevin S. Moore, James O. Malley

and Michael D. Engelhardt.

July '99: Practical Design and Detailing of Steel Column Base Plates, by William C. Honeck and Derek Westphal.

Dec. '98: Seismic Behavior and Design of Gusset Plates, by Abolhassan Astaneh-Asl.

Mar. '98: Compatibility of Mixed Weld Metal, by Alvaro L. Collin and James J. Putkey.

Aug. '97: Dynamic Tension Tests of Simulated Moment Resisting Frame Weld Joints, by Eric J. Kaufmann.


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Apr. '97: Seismic Design of Steel Column-Tree Moment-Resisting Frames, by Abolhassan Astaneh-Asl.

Jan. '97: Reference Guide for Structural Steel Welding Practices.

Dec. '96: Seismic Design Practice for Eccentrically Braced Frames (Based on the 1994 UBC), by Roy Becker and

Michael Ishler.

Nov. '95: Seismic Design of Special Concentrically Braced Steel Frames, by Roy Becker.

Jul. '95: Seismic Design of Bolted Steel Moment-Resisting Frames, by Abolhassan Astaneh-Asl.

Apr. '95: Structural Details to Increase Ductility of Connections, by Omer W. Blodgett.Dec. '94: Use of Steel in the Seismic Retrofit of Historic Oakland City Hall, by William Honeck & Mason Walters.

Dec '93: Common Steel Erection Problems and Suggested Solutions, by James J. Putkey.

Oct. '93: Heavy Structural Shapes in Tension Applications.

Mar. '93: Structural Steel Construction in the '90s, by F. Robert Preece and Alvaro L. Collin.

Aug. '92: Value Engineering and Steel Economy, by David T. Ricker.

Oct. '92: Economical Use of Cambered Steel Beams.

Jul. '92: Slotted Bolted Connection Energy Dissipaters, by Carl E. Grigorian, Tzong-Shuoh Yang and Egor P. Popov.

Jun. '92: What Design Engineers Can Do to Reduce Fabrication Costs, by Bill Dyker and John D. Smith.

Apr. '92: Designing for Cost Efficient Fabrication, by W.A. Thornton.

Jan. '92: Steel Deck Construction.

Sep. '91: Design Practice to Prevent Floor Vibrations, by Farzad Naeim.

Mar. '91: LRFD-Composite Beam Design with Metal Deck, by Ron Vogel.

Dec. '90: Design of Single Plate Shear Connections, by Abolhassan Astaneh-Asl, Steven M. Call and Kurt M.

McMullin.

Nov. '90: Design of Small Base Plates for Wide Flange Columns, by W.A. Thornton.

May '89: The Economies of LRFD in Composite Floor Beams, by Mark C. Zahn.

Jan. '87: Composite Beam Design with Metal Deck.

Feb. '86: UN Fire Protected Exposed Steel Parking Structures.

Sep. '85: Fireproofing Open-Web Joists & Girders.

Nov. '76: Steel High-Rise Building Fire.


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3650 Mt. Diablo Blvd. Suite 201

Lafayette, CA 94549

Phone: (510) 835-5035

Fax: (510) 863-5015

Steel TIPS may be viewed and downloaded atwww.steeltips.org

Participating Members of SSEC

ABOLHASSAN ASTANEH-ASL, Ph.D., P.E.; UNIV. OF CALIFORNIA, BERKELEY

MICHAEL COCHRAN, S.E.; WIEDLINGER ASSOCIATES, INC.

RICH DENIO, S.E.; RUTHERFORD & CHEKENE

RICH DEVEAU; ALBANY STEEL, INC.

PATRICK M. HASSETT, S.E.; HASSETT ENGINEERING, INC.BRETT MANNING, S.E.; SCHUFF STEEL CO.

KEVIN MOORE, S.E.; SIMPSON GUMPERTZ & HEGER

JAY MURPHY; MURPHY PACIFIC CORPORATION

RICHARD PERSONS; PERSONS & ASSOCIATES

PAUL RANGEL; PDM STEEL SERVICE CENTERS, INC.

DAVID LEE, Ph.D.; TAYLOR DEVICES, INC.

SSEC Corporate Sponsors:

Taylor Devices

Intelligent Engineering

Contego International

STRUCTURAL STEEL EDUCATIONAL COUNCIL

Steel
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Viscous Dampers Save Structures From Earthquake Damage 7-2013 (1)