FEDERAL EMERGENCY MANAGEMENT AGENCY FEMA74/ September 1994

Supersedes 1985 Edition

Reducing the Risksof Nonstructural

Earthquake Damage

A PRACTI,CAL GUIDEIssued by FEMA in furtherance of the Decade for Natural Disaster Reduction

Re'ducing the Risks ofNonstructural EarthquakeD;amage

A Practical Guid'e

Third Edition

FE:MA 74JSeptember 1994Supersedes 1985 Edition

Originally developed by Robert Reiitherman of Scientific Service,. Inc., for theSouthern California Earthquake Preparedness Project (SCEPP)

Third Edition byWISS, JANNEY, ELSTNER ASSOCIATES, INC.FOi" the Federal Emergency Management Agency (FEMA)Under the National Earthquake Technical Assistance Contract (NETAC) EMW-92-C-3852

Authors.:Eduardo A. FierroCynthia L. PerrySigmund A. Freeman

Advisory Panel:Christopher Arnold Richard EisnerWilliam Holmes Robert Reitherman

TABLE OF CONTENTS

LIST OF FIGURES v

PREFACE vi

1. HOW TO USE THIS GmDEPURPOSE 1INTENDED AUDIENCE 1LIMITATIONS 2CHAPTER CONTENTS 2

2. OVERVIEWDEFINITIONS 4SIGNIFICANCE OF NONSTRUCTURAL DAMAGE 4CAUSES OF NONSTRUCTURAL DAMAGE 12METHODS FOR REDUCING NONSTRUCTURAL HAZARDS 15BUILDING CODE REQUIREMENTS FOR NONSTRUCTURAL COMPONENTS 16SEISMIC HAZARD 18

3. NONSTRUCTURAL SURVEY PROCEDURESTYPICAL NONSTRUCTURAL COMPONENTS 21FACILITY SURVEY 21ASSESSMENT PROCEDURES 22COMPARISON OF ALTERNATIVES 25

4. NONSTRUCTURAL EXAMPLES: EARTHQUAKE DAMAGEAND UPGRADE DETAILS

NONSTRUCTURAL EXAMPLES 26BUILDING UTILITY SYSTEMS

Batteries and Battery Rack 30Diesel Fuel Tank 31Electrical Bus Ducts and Primary Cable System 32Fire Extinguisher 33Propane Tank 34Water Heater: Corner Installation 35Water Heater: Wall Installation 36Piping 37Chiller 38Air Compressor (or other HVAC Equipment) 40Suspended Space Heater 41HVAC Distribution Ducts 42Air Diffuser 43Residential Chimney 44

ARCHITECTURAL ELEMENTSBuilt-In Partial-Height PartitionsBuilt-In Full-Height PartitionsSuspended T-Bar CeilingsSuspended Light FixturesPendant Light FixturesStairwaysWindowsUmeinforced Brick ParapetsVeneerFreestanding Wills or FencesExterior Signs

FURNITURE AND CONTENTSLarge Computers and Access FloorsDesktop Computers and Office EquipmentTall Shelving: FreestandingLibrary StacksTall Shelving: Wan UnitTall File CabinetsFlexible Connection for Gas or Fuel LinesDrawer and Cabinet LatchesFreestanding Wood StoveCompressed-Gas CylindersContainers of Hazardous MaterialsFragile ArtworkFreestanding Half-Height PartitionsMiscellaneous Furniture

INSTALLATION NOTES

5. DEVELOPING EARTHQUAKE PROTECTION PROGRAMSSELF-HELP VS. USE OF CONSULTANTSIMPLEMENTATION STRATEGIESEVALUATION

6. EMERGENCY PLANNING GUIDELINESIMPLICATIONS OF NONSTRUCTURAL DAMAGE

FOR EM:ERGENCY PLANNINGEARTHQUAKE PLANSTRAININGEXERCISESPERSONAL EMERGENCY KITSMASTER EARTHQUAKE PLANNING CHECKLIST

7. FACILITIES DEVELOPMENT GUIDELINESNONSTRUCTURAL CONSTRUCTION GUIDELINESSTRUCTURAL/NONSTRUCTURAL INTERACTION

4546474849505152535455

565758596061626364656667686970

767779

818283848484

8789

FEES FOR PROFESSIONAL SERVICES

GLOSSARYREFERENCESANNOTATED BffiLIOGRAPHY

APPENDIXESA: NONSTRUCTURAL INVENTORY FORMB: CHECKLIST OF NONSTRUCTURAL EARTHQUAKE HAZARDSC: NONSTRUCTURAL RISK RATINGS

90

919395

A-IB-1C-l

LIST OF FIGURES

1. NonstructuraI and Structural Components of a Typical Building2. Examples of Hazardous Nonstructural Damage3. Examples of Hazardous Nonstructural Damage4. Examples of Property Loss Due to Nonstructural Damage5. Examples of Loss. of Function Due to Nonstructural Damage6. Effects of Earthquakes on Nonstructural Components7. Map of Probable Shaking Intensity for the United States8. NonstructuraI Examples9. Information Gathering Checklist: Organizational Characteristics10. Master Nonstructural Earthquake Protection Checklist

Page568

10111419;

28-298586

PREFACEThe first edition of this guide was preparedunder contract to the Southern CaliforniaEarthquake Preparedness Project (SCEPP), ajoint state-federal effort. It was prepared byScientific Service, Inc., a firm specializing inengineering and emergency planning consultingrelated to natural and man-made hazards. Itwas written and researched by RobertReitherman with the assistance of Dr. T. C.Zsutty; they provided architectural andstructural engineering expertise, respectively, inthe field of nonstructural earthquake damage.

The second edition was published in 1985 bythe Bay Area Regional Earthquake PreparednessProject, now part of the California Office ofEmergency Services, Earthquake Program.Revisions were based on the suggestions ofusers and a peer review committee consisting ofChristopher Arnold, president, Building SystemsDevelopment, Inc.; Richard Eisner, director ofBAREPP; Eric Elsesser, vice president,ForelllElsesser; William Holmes, structuralengineer, Rutherford & Chekene; John Meehan,chief, structural safety, Office of the StateArchitect; and Gilbert Najera, SouthernCalifornia Earthquake Preparedness Project.

The revisions made in the second edition of theguide consisted primarily of modifying graphics,updating construction cost estimates, andidentifying the need for engineering andarchitectural assistance in designing andcarrying out the guide's recommendations.

This third edition was prepared by Wiss,Janney, Elstner Associates, Inc., for the FederalEmergency Management Agency (FEMA) underthe National Earthquake Technical AssistanceContract (EMW-92-C-3852). The objective of

this revision is to incorporate lessons learnedfrom earthquakes that have occurred since thesecond edition was published, provide additionaldetails, distinguish between do-it-yourself detailsand those for which there is additionalengineering required, update the cost estimatespresented, and incorporate new techniques,andtrends in earthquake engineering. The format ofthe document has been substantially revised.Review comments and suggestions wereprovided by the advisory panel, which wascomposed of Christopher Arnold, RichardEisner, William Holmes, and RobertReitherman.

Individual photo credits are provided, both forphotos carried over from previous editions andfor those new to the third edition. Some newanchorage or bracing details have been adaptedfrom other publications that are listed in theReferences (References 16 to 21).

Disclaimer FEMA and Wiss, Janney, ElstnerAssociates have attempted to produce reliableand practical information in this publication, butneither they nor any consultants involved inpreparing or reviewing material contained inthis guide can guarantee that its application willsafeguard people or property in case of anearthquake. The state of the art of earthquakeengineering is not sufficiently developed toperfectly predict the performance ofnonstructural elements or to guarantee adequateearthquake protection if these or otherguidelines are followed. Professional expertiseis recommended to increase the probability thatintended levels of earthquake protection will beachieved. Liability for any losses that mayoccur in an earthquake or as a result of usingthis guidance is specifically disclaimed.

!'ll HOW TO USE THIS GUIDEPURPOSETills guide was. developed to fuliill severaldifferent objectives and address a wide_ audiencewith varying needs. The primary intent is toexplain the sources of nonstructural earthquakedamag-e in simple tenns. and to provideinformation on effective methods of reducingthe potential risks. The r-eeommendationscontained in this guide are intended to reducethe potential hazards but cannot completelyeliminate them.

INTENDED AUDIENCEThis guide is intended primarily for use by a layaudience: building owners, facilities managers,maintenance personnel, store or officemanagers, corporate/agency department heads,business proprietors, homeowners, etc. Somereaders may be small-business owners with asmall number of potential problems that couldbe addressed in a few days' time by having athandyman install some of the generic detailspresented in this guide. Other readers may beresponsible foi" hundreds of facilities and mayneed a survey methodology to help themunderstand the magnitude of their potentialproblems.

The purpose of this section is to help readersidentify those portions of the guide that may beapplicable to their particular situation andinterests. The prospective audience can besubdivided into the four general categoriesdescribed below. Each description contains alist of the chapters that may be the most usefulfor that group of readers. The chapter contentsare also described below.

General Interest The lay reader who wantsan illustrated overview of the subject ofnonstructural ;earthquake damage.

Suggested readingfor thegeneral interest reader:Chapters 1 and 2 and thenonstroctural examples inChapter 4.

Do-It-Yourself The reader who wants atgeneral overview of the subjeet, help inidentifying potential hazards, and specificguidance with suggested upgrade details that thereader can implement him- or herself.

Suggested reading for thedo-it-yourself reader:Chapters 1, 2, 3,- and 4.

I Chapter 4 .contains some. generic details and

installation guidelines.

Facilities/Planning Personnel Facilitiesor planning personnel who need an overview ofthe subject as well as at survey methodologyapplicable to an organizational setting.. Thisguide contains forms and checklists that can beused to survey .a facility to identify potentialhazards, estimate seismic vulnerability andpotential earthqua.k:e losses and repair -costs., andestimate the costs in implementing hazardr-eduction methods. The guid·e differentiatesbetween methods that can be readilyimpl-emented by a handyman and those thatrequire professional assistance. The guide alsocontains a discussion of various implementationstrategies and general guidance on earthquakepreparedness and emergency planning.

Chapter 2 - Overview General discussion

When in doubt,consult a civilor structuralengineer.

, Suggested reading for ' ,,facUities/planning personnel: , "Chapters 1;'7 and survey' '

." ' fonns and checklists , ' '" (AppetidixesA, B, and C).

Architect/Engineer The AlE who has littleor no knowledge of nonstructural earthquakedamage and needs an introduction to the subjectand a list of sources that will provide moredetailed technical information.

Suggested reading for , ' ,architect/engineerunfamiliar. ,. 'with 'the subject matter: ',. ,',,','

, Chapters 1-7, survey forms· '. 'and checklists' (Appendixes

, A, B, and C), and annotated "bibliography.' .

The categories and suggested reading above areintended to be helpful, not restrictive. Readersare encouraged to use this guide and/or adaptthe forms and checklists herein in any way thatis helpful to' their particular circumstances.Self-diagnosis and self-implementation by thenonengineer may be adequate in many instances,and an attempt has been made to provideenough detail to allow for completeimplementation of some of the simplerprotective measures. However, there are limitsto the self-help approach, as explicitly statedbelow.

LIMITATIONSIf this were a guide that explained how a personcould administer his or her own physical exam,diagnose any health problems, and prescribe andcarry out the appropriate treatment, certainobvious questions would arise: How far along

that path can an untrained person proceed beforerequiring the services of a physician? Wouldn'tthe layperson get into trouble trying to practiceself-help medical care?

There are similarlimitations andcaveats that must bemade explicit in thisguide's attempt toinstruct laypersons in self-help earthquakeengineering. In addition to the individual notesfound later, which point out specific areaswhere expertise is required" the generaldisclaimer should be made here that the use ofearthquake engineering expertise is oftendesirable to improve the reliability of identifyingand reducing earthquake risks. When in doubtabout a health problem, consult a doctor. Whenin doubt about the IIseismic health ll of a facility,consult a civil or structural engineer, or anarchitect. On the other hand, many self-helptechniques are commonly recommended bydoctors, such as taking one's temperature,treating minor colds with commonsensemeasures rather than costly trips to the doctor,managing one's diet with only occasionalprofessional advice, and so on. Similarly, thisguide attempts to provide advice for self-helpearthquake protection measures and presumesthat the advice will be applied wisely and thatexpert assistance will be obtained wherenecessary.

CHAYfER CONTENTSThe material in this book is organized asfollows.

Chapter 1 - How to Use This GuideInformation to help readers with differentinterests find the relevant portions of this guide.

of the problems associated with nonstructuralearthquake damage.

Chapter 3 - Survey and AssessmentProcedures Guidelines on how to survey thenonstructural items in a facility and assess thevulnerability of these items to earthquakedamage. The appendixes contain inventoryforms and detailed checklists with informationdesigned to help identify vulnerable items.

response planning, that is, how to includepotential damage to nonstructural components inan emergency plan. Have emergency exits beendesignated that do not have glass, v,eneer, orheavy canopies that are vulnerable to damage?Who is r.esponsible for' shutting off the waterand gas if the pipes, break, and is that person--and an alternate--available 24 hours a day?Does the organization pmvide training foremployees on what to do in an earthquake?

Chapter 5 Developing anEarthquake Protection Program Adiscussion of various implementation strategies:whether to use existing staff or outside,consultants; whether to embark on an ambitiousupgrade program or combine the upgrades withongoing maintenance or remodeling;, how toevaluate the success of a program.

Chapter 4 - Nonstructural Examples:Earthquake Damage and UpgradeDetails Examples for selected nonstructuraIitems. . Each example typically includes aphotograph showing earthquake damage to anunanchored or inadequately anchoi"ed item andsuggested upgrade details that can be used! toreduce the seismic vulnerability of such items.Some of the simpler details in this chapter aremarked! Do-It-Yourselfand can be installed by ahandyman following the installation guidelinescontained in the text. The details markedEngineering Required ,are schematic only, anddesign professionals should be retained toevaluate these systems and develop appropriateupgrade details. The design of upgrade detailsto protect against earthquake damage to theseitems is complicated and requires specializedprofessional expertise.

Chapter 6Ouidelines

Emergency PlanningA discussion of emergency

Chapter 7 - Facilities Developm,entGuidelines For essential facilities ,and/orlarge organizations. In these cases, it may beappmpriate to develop formal constructionguidelines. or specifications for the installation ofnonstructural components. Such guidelinesmight include a statement of the desiredperformance for particular equipment,requirements for inspection during cons.truction,Or' specification of a particular design code orforce level to be used in the design of·equipment anchorage.

Glossary :Earthquake engineering terms usedin this guide..

References References cited in the text.

Annotated Bibliography Additionalreferences that may be useful to architects,engineers, or others seeking more detailedinformation about this topic.

Appendix A - NonstmcturallnventoryFonn

Appendix B Checklist ofNonstructural Earthquake Hamrds

Appendix C- Nonstructural RiskRatings

[I] OVERVIEWThe primary focus of this guide is to help thereader understand which nonstructural items aremost vulnerable in an earthquake and mostlikely to cause personal injury, costly propertydamage, or loss of function if they aredamaged. In addition, this guide containsrecommendations on how to implement cost-effective measures that can help to reduce thepotential hazards.

DEFINITIONSAt the outset, two terms frequently used in theearthquake engineering field should be defined.

Structural The structural portions of abuilding are those that resist gravity,earthquake, wind, and other types of loads.These are called structural components andinclude columns (posts, pillars); beams (girders,joists); braces; floor or roof sheathing, slabs, ordecking; load-bearing walls (i.e., walls designedto support the building weight and/or providelateral resistance); and foundations (mat, spreadfootings, piles). For buildings planned bydesign professionals, the structure is typicallydesigned and analyzed in detail by a structuralengineer.

Nonstructural The nonstructural portions ofa building include every part of the building andall its contents with the exception of thestructure--in other words, everything except thecolumns, floors, beams,. etc. Commonnonstructural components include ceilings;windows; office equipment; computers;inventory stored on shelves; file cabinets;heating, ventilating, and air conditioning(HVAC) equipment; electrical equipment;furnishings; lights; etc. Typically, nonstructuralitems are not analyzed by engineers and may bespecified by architects, mechanical engineers

(who design HVAC systems and plumbing forlarger buildings), electrical engineers, orinterior designers; or they may be purchasedwithout the involvement of any designprofessional by owners or tenants afterconstruction of a building. Figure 1 identifiesthe structural and nonstructural components ofa typical building. Note that most of thestructural components of a typical building areconcealed from view by nonstructural materials.

SIGNIFICANCE OFNONSTRUCTURAL DAMAGEWhy is nonstructural earthquake damage ofconcern? What are the direct effects of damageto nonstructural items? What are the secondaryeffects or potential consequences of damage?

The following discussion covers three types ofrisk associated with earthquake damage tononstructural components: life safety, propertyloss, and interruption or loss of essentialfunctions. Damage to a particular nonstructuralitem may have differing degrees of risk in eachof these three categories. In addition, damageto the item may result in direct injury or loss,or the injury or loss may be a secondary effector consequence of the failure of the item.

f1Il~ life Safety The first type of risk isthat people could be injured or killed bydamaged or falling nonstructural components.Even seemingly innocuous items can be lethal ifthey fallon an unsuspecting victim. If a25-pound fluorescent light fixture not properlyfastened to the ceiling breaks loose during anearthquake and falls on someone's head, thepotential for injury is great. Examples ofpotentially hazardous nonstructural damage that

NON-LOADBEARiNG

PARTITION

FIRESPRINKLER

SYSTEM.

REINFORCEDCONCRETE SLAB

ON METAL DECK ORCONCRETE SLAB.

COLUMN (STEELCOLUMN SHOWN...

USUALLY ENCASEDIN NONSTRUCTURAL

FIREPROOFING).

AIRDIFFUSER

AIR CONDITIONINGDUCT.

MASONRY ORCONCRETESTRUCTURALWALL.

. EXTERlOR. CURTAIN WALL,

WINDOWS,CLADDING.

STEEL ORCONCRETECOLUMNS.

ELECTRICALCONDUIT FORWIRING.

SUSPENDEDCEIUNGACOUSTICALTILE.

KEYNONSTRUCTURAL ~TEMS (STANDARD TEXT)STRUCTURAL ITEMS (ITALICS)

Fi, ure 1 - Nonstructural and Structural Com onents ofaT ical Suildin

Failure of office partitions, ceilings, and light fixturesEarthquake Damage: 1994. Northridge, CanfomiaPhoto Credit Wiss, Janne • Eistner Associates Inc.

•

Shard of broken nontempered glass that fell several stories (rom a multistory buildingEarthquake Damage: 1994. Northridge, CaliforniaPhoto Credit: WlSS, Janna Etstner Associates Inc.

FI ure 2 • Exam les of Hazardous Nonstruetural Dama e

has occurred during past earthquakes includebroken glass, overturned tall .and heavy cabinetsor shelves, falling ceilings or overhead lightfixtures, ruptured gas lines or other pipingcontaining hazardous materials, damaged friableasbestos materials, falling pieces of decorativebrickwork or precast concrete panels, and·collapsed masonry walls or fences. (Figures 2and 3).

Several specific examples will help to illustratethe point.

• More than 170 campuses in the Los AngelesUnified School District suffered damage--mostof it nonstructural--during the 1994 Northridge·earthquake. At Reseda High School, the ceilingin a classroom collapsed and cover·ed the schooldesks with debris. The acoustic ceiling panelsten in relatively large pieces, approximately 3feet or 4 feet square, accompanied by pieces ofthe metal ceiling runners and full-length sectionsof strip fluorescent light fixtures. Because theearthquake occurred! at 4:31 a.m., when thebuilding was unoccupied, none of the studentswer,e injured [1].

• A survey of elevator damage fonowing the1989 Lorna Prieta earthquake revealed 98instances where counterweights ·came out of theguide rails and 6 instances where thecounterweight impacted the elevator cab,.including one case where the counterweightcame through the roof of the cab. Fortunately,no injuries were reported [2].

• One hospital patient on a life-support systemdied during the 1994 Northridge earthquakebecause of failure of the hospitaPs electricalsupply [3].

• During the 1993 Guam ,earthquake, the fire-rated nonstructural. masonry partitions in the exitcorridors of one resort hotel were extensivelycracked" causing many of the metal fire doors inthe corridors to jam. Hotel guests had to·break

through the gypsum wallboard partitionsbetween rooms in order to get out of thebuilding, a process that took as long as sev.eralhours. It was fortunate that the earthquake didnot cause at fire in the building, and no seriousinjuries were r,eported.

Property Loss For mostcommercial buildings, the foundation andsuperstructure account for approximately 20-25 % of the original ·construction cost, while themechanical, electrical, and architecturalelements account for the remaining 75-80%.Contents belonging to the building occupants,such as movable partitions, fumitur,e, files, andoffice or medical equipment, represent asignificant additional expense. Damage to thenonstructuraIelements and contents of abuilding can be costly, since th:ese componentsaccount for the vast majority of building cos.ts.Immediate property losses attributable tocontents alone are often ·estimated to be onethird of the total earthquake losses [4].

Property losses may be the result of directdamage to a nonsttuctural item or ofconsequential damage. As used here, the termproperty loss refers only to immediate, directdamage. If water pipes or fire sprinkler linesbreak, the overall. property losses will includethe cost to repair the piping plus the cost torepair water damage to the facility. If the gasline to a water heater ruptures and causes a fire,clearly the property loss will be much gr,eaterthan the cost of a new pipe :fitting. On the otherhand, if many file cabinets. overturn and all thecontents end up on the floor, the direct damageto the cabinets and documents will probably benegligible {unless they are also affected bywater damage), but employees may spend manyhours or days refiling the documents. If areserve water tank is situated on the roof of abuilding,. the consequences of damage may bemore severe than they would be if it were in the

Failure of suspended ceiling and light fixtures in furniture storeEarthquake Damage: 1994, Northridge, CaliforniaPhoto Credit: William MCKevitt~iiU

• --.

Failure of heavy stucco soffrt at building entranceEarthquake Damage: 1994, Northridge, CaliforniaPhoto Credit: Robert Reitherman

---J

- I,~ ''' ...

Fi ure 3 - Exam les of Hazardous Nonstructural Oama e

basement or outside the building in the parkinglot.

A few individual cases may help illustrate thepotential for property loss. (See Figure 4).

• A surv,ey of 25 commercial buildingsfollowing the 1971 San Fernando earthquakerevealed the fonowing breakdown of propertylosses: structural damage, 3 %;, electrical ,andmechanical, 7%; exterior finishes, 34%; andinterior fInishes, 56%. A similar survey of 50high-rise buildings, which were far enoughaway from the earthquake fault to experienceonly mild shaking, showed that none had majorstructur:al damage but 43 suffered damage todrywall or plaster partitions, 18 suffereddamaged elev.ators, 15 had broken windows,and 8 incurred damage to air conditioningsystems. [5].

Many offices and smaIl businesses suffer lossesas a result of nonstructural earthquake damagebut may not keep track of these losses unlessthey have earthquake insurance that will helpcover the cleanup and repair costs. The nextexamples,. which are more dramatic, involvelibrary and museum facilities whose function isto store and maintain v.aluable contents,. wherethe nonstructural losses are easy to identify.

• Following the 1989' Lorna Prieta earthquake,two libraries in San Francisco ,each sufferedover a million dollars in damage to buildingcontents; the money was spent primarily onreconstructing the library stacks, rebindingdamaged books, and sorting and reshelv:ingbooks. At- one of these facilities, $100,000 wasspent rebinding a relatively small number ofrare books [6, 7].

• A survey of eight museums. in the SanFrancisco Bay Area following the 1989 LomaPrieta earthquake indicated that approximately150 out of more than 500,000 items hadsuffer,ed some type of damage, resulting in

losses on the order of $10 million. At theAsian Art Museum in San Francisco, with acollection estimated to have a market value of$3 billion, damage to 26 items resulted in a totalloss of $3 million, or roughly 1%. All eight ofthese facilities had implemented some form ofseismic mitigation before the earthquake, andthese measures prevented more ,s.erious losses[2, 8].

ILFIi : Loss of Function In addition tothe life safety and property loss considerations,there is the additional possibility thatnonstructura1 damage will make it difficult orimpossible to carry out the functions normallyaccomplished in a facility. After the serious lifesafety threats have been dealt with, the potentialfor postearthquake downtime or reducedproductivity is often the most important risk.

Many external factors may affect postearthquakeoperations, including power and water outages,damage to transportation structures, civildisorder, ponce lines" curfews, etc. Theseeffects are outside the control of buildingowners and tenants and hence outside the scopeof this discussion.

The following are examples of nonstructuraldamage that resulted in interruptions topostearthquake emergency operations or tobusiness.

.' During the 1994 Northridge earthquake,nonstructural damage caused temporary dosure,evacuation, or patient transfer at ten essentialhospital facilities. These hospitals generally hadlittle or no structural damage but were renderedtemporarily inoperable, primarily because ofwater damage. At ov,er a dozen of thesefacilities, water leaks occurred when fuesprinkler, chilled-water, or other pipelinesbroke. Hospital personnel wer,e apparentlyunavailable or unable to shut off the water, and

Complete loss of suspended ceiling and light fixturesEarthquake Damage: 1994, Northridge, CaliforniaPhoto Credit: Wiss Janne Elstner Associates, Inc.

Damage to inventory on industrial storage racksEarthquake Damage: 1994, Northridge, CaliforniaPhoto Credit: WISS, Janne ,Elstner Associates, Inc,

Fi ure 4 • Exam les of Pro ert Loss Due to Nonstructural Dama e

I

'J

,

Broken sprinkler pipe at Olive View Hospital in Sylmar-pipe ruptured at the elbow joint due todifferential motion within the ceiling plenum. Water leakage from broken fire sprinklers and water linesforced the hospital to close for several days.Earthquake Damage: 1994, Northridge, CaliforniaPhoto Credit: Robert Reitherman

"-

HVAC damage at Holy Cross Medical Center in Sylmar-damage to signage and louvers caused whensuspended fans in the mechanical penthouse swung and impacted the louver panels. HVAC serviceoutage caused the temporary evacuation of all patients.Earthquake Damage: 1994, Northridge, CaliforniaPhoto Credit: Robert Reitherman

FI ure 5 • Exam les of Loss of Function Due to Nonstructural Dama e

in some cases water was flowing for manyhours. At one facility, water up to 2 feet deepwas reported at some locations in the buildingas a result of damage to the domestic watersupply tank on the roof. At another, theemergency generator was disabled when itscooling water line broke where it crossed aseparation joint. Other damage at thesefacilities included broken glass, dangling lightfixtures, elevator counterweight damage, andlack of emergency power due to failures in thedistribution or control systems. Two of thesefacilities, Los Angeles County Olive ViewMedical Center and Holy Cross Medical Center,both in Sylmar, California, had suffered severestructural damage or collapse during the 1971San Fernando earthquake and had beendemolished and entirely rebuilt [3]. (See Figure5).

• Of 32 data processing facilities surveyedfollowing the 1989 Lorna Prieta earthquake, atleast 13 were temporarily out of operation forperiods ranging from 4 to 56 hours. Theprimary cause of outage was loss of outsidepower; at least 3 facilities with UninterruptiblePower Supplies (UPS) or Emergency PowerSystems (BPS) did not suffer any downtime.Reported damage included overturning ofequipment (2 facilities); damage to access floors(4 facilities); movement of large pieces ofcomputer equipment over distances rangingfrom a few inches to 4 feet (26 facilities); anddislodged ceiling panels (13 facilities). Twentyof these facilities reported having an earthquakepreparedness program in place at the time of theearthquake, 3 reported no program, andinformation was unavailable for 9 facilities [2].

• The 1971 San Fernando earthquake causedextensive damage to elevators in the LosAngeles area, even in some structures where noother damage was reported. An elevator surveyindicated 674 instances where counterweightscame out of the guide rails, in addition toreports of other types of elevator damage.

These elevators were inoperable until they couldbe inspected and repaired. Many thousands ofbusinesses were temporarily affected by theseelevator outages. The State of Californiainstituted seismic elevator code provisions in1975, and while these provisions appear to havehelped reduce the damage, there were still manyinstances of counterweight damage in the SanFrancisco area following the 1989 Lorna Prietaearthquake [2], and 688 cases in the Northridgeearthquake [3].

In some cases, cleanup costs or the value of lostemployee labor are not the key measures of thepostearthquake impact of an earthquake. Forexample, data processing facilities or financialinstitutions must remain operational on aminute-by-minute basis to maintain essentialservices and monitor transactions at distantlocations. In such cases, spilled fIles or damageto communications and computer equipmentmay represent less tangible but more significantoutage costs. Hospitals and fire and policestations are all facilities with essential functionsthat must remain operational after anearthquake; damage to their nonstructuralelements can be a major cause of loss offunctionality.

CAUSES OFNONSTRUCTURAL DAMAGEEarthquake ground shaking has three primaryeffects on nonstructural elements in buildings.These are inertial or shaking effects on thenonstructural elements themselves, distortionsimposed on nonstructural components when thebuilding structure sways back and forth, andseparation or pounding at the interface betweenadjacent structures (Figure 6) .

Inertial Forces When a building is shakenduring an earthquake, the base of the buildingmoves in unison with the ground, but the entirebuilding and building contents above the basewill experience inertial forces. These inertial

forces can be explained by using the analogy ofa passenger in a moving vehicle. As apassenger, you experience inertial forceswhenever the vehicle is rapidly accelerating ordecelerating. If the vehicle is accelerating, youmay feel yourself pushed backward against theseat, since the inertial force on your body actsin the direction opposite that of the acceleration.If the vehicle is decelerating or braking, youmay be thrown forward in your seat. Althoughthe engineering .aspects of earthquake inertialforces are more complex than a single principleof physics, the law fIrst formulated by Sir IsaacNewton, F = rna, or force is equal to the masstimes the acceleration, is the basic principleinvolved. In general, the ,earthquake inertialforces are gr,eater if the mass. is greater (if thebuilding or ob}ect within the building weighsmore) or if the acceleration or severity of theshaking is greater.

File cabinets, emergency power-generatingequipment, freestanding bookshelves,. officeequipment, and items stor,OO on shelves or rackscan all be damaged because of inertial forces.When unrestrained items are shaken by anearthquake, inertial forces may cause them toslide,. swing, strike other objeets, or overturn.Items may slide off shelves and faU to the floor.One common misconception is that large, heavyobjects. are stable and not as vulnerable toearthquake damage as lighter objects, perhapsbecause we may have difficulty moving them.In fact, many types of objects may bevulnerable to earthquake damage caused byinertial forces: since inertial forces during anearthquake are proportional to the mass orweight of an object, a -heavily loaded filecabinet requires much stronger restraints to keepit from sliding or overturning than a light onewith the same dimensions.

Building Distortion During an earthquake,building structures distort, or bend, from side toside in response to the earthquake forces. Forexamplle,the top of a tall office tower may lean

over a few feet in each dir,ection during anearthquake. The distortion over the height ofeach story, known as the story drift, mightrange from % inch to several inches, dependingon the size of the earthquake and thecharacteristics of the particular buildingstructure. Windows, partitions, and other itemsthat are tightly locked into the structure areforced to go along for the ride. As the columnsor walls distort and! become slightly out ofsquare, if only fman instant, any tightlyconfined windows or partitions must also distortthe same amount. The more space there isaround Ii pane of glass where it is mountedbetween stops or molding strips, the moredistortion the glazing assembly canaccommodate before the glass itself is subjectedto earthquake forces. Brittle materials likeglass, plaster or drywall partitions,and masonryinfill or veneer cannot tolerate any significantdistortion and! will crack when the perimetergaps dose and the building structure pushesdirectly on the brittle elements. Mostarchitectural components such as glass panes,partitions, and veneer are damaged because ofthis type of building distortion, not because theythemselves are shaken or damaged by inertialforces.

There have also been notable cases of structural-nonstructural interaction in past earthquakes,where rigid nonstructural components have beenthe cause of structural damage or collapse.These cases have generally involved rigid!,strong architectural components, such asmasonry infill or concrete spandrels, that inhibitthe movement or distortion of the structuralframing and cause pr,emature failure of columnor beam elements. While this is. a seriousconcern for structural designers, the focus ofthis guide is on earthquake damage tononstructural components,.

Building Separations Another source ofnonstructural damage involves pounding ormovement across separation joints between

OVERTURNING OFSLENDER OBJECTS

SLIDING OFSTOCKY OBJECTS

..... .

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BREAKAGE OFGLASS ORPARTITIONS

DEFORMED SHAPE BREAKAGE OF PIPING OR DUCTS MAY OCCUR ATOF BUILDING SEISMIC JOINTS DUE TO DIFFERENTIAL

..--~_-.Lo.__...., DISPLACEMENTS (SEPARATION AND POUNDING)

Fi ure 6 • Effects of Earth uakes on Nonstructur~[Com .om~rlts· .

adjacent structures. A separation joint, is thedistance between two different buildingstructures, often two wings of the same facility,that allows the structures to move independentlyof one another. A seismic gap is a separationjoint provided to accommodate relative lateralmovement during an earthquake. In order toprovide functionalcontinwty between separatewings, building utilities must often ,extendacross these building separations, andarchitectural finishes must be detailed toterminate on either side. For base-isolatedbuildings. that are mounted on seismic shock,absorbers, a seismic isolation gap occurs at theground level, between the foundation and thebase of the superstructure. The separation jointmay be only an inch or two in olderconstruction or as much as a foot in some newerbuildings, depending on the expected horizontallmovement, or seismic drift. Flashing, piping,fire sprinkler lines, HVAC ducts, partitions, andflooring all have to be detailed to accommodatethe seismic movement expected at theselocations when the two structures move closertogether or further apart. Damage to itemscrossing seismic gaps is a common type ofearthquake damage,. If the size of the gap isinsufficient, pounding between adjacentstructures may result in damage to structuralcomponents but often causes damage tononstructural components, such as parapets,veneer" or cornices on the facades of olderbuildings.

l\1ETHODS FOR REDUCINGNONSTRUCTURAL HAZARDSThere are a variety of methods available toreduce the potential risks associated withearthquake damage to nonstructuraI components.These methods range from simple commonsensesteps one can take oneself to complex solutionsrequiring professional help. Simple steps mightinclude relocating top-heavy furniture awayfrom the doorway or bed in a bedroom andinstalling some of the simple do-it-yourself

anchorage details pr,esented in this guide,. La:rgeorganizations with complex facilities may needto hire professional consultants to designengineering details for building utilities andarchitectural components. For facilities such ashospitals, museums, libraries, researchlaboratories, and industrial facilities,professional consultants would probably beneeded to provide specific design details forspeci~ed building contents as. well.

Facility Survey Nonstructural hazards maybe present in any type of facility-a home, anoffice,. a church, a day care center, a retailstore, a nursing care facility,. a school, a lightmanufacturing plant. Chapter 3 includesguidelines for performing a facility survey toidentify potential nonstructural hazards. Theforms and checldists provided in this guide areintended for use by laypersons, i.e.,nonengineers, who are familiar with the buildingor facility to be surveyed. The process ofconducting the survey should help to increaseuser awareness of the potential problems. Theresults of the survey should help buildingowners, managers, and/or occupants understandthe scope of the potential problems and assessthe building'·s seismic vulnerability, or presentlevel of risk of nonstructural earthquakedamage.

Commonsense Measures A facilitysurvey may identify many items that representa high or moderate risk in their present locationbut that could readily be relocated to reduce thepotential risk. The answers to the followingquestions may help identify commonsensemeasures that cam be used to reduce many of thepotential risks.• Where do you, your family, and your·employees spend the most time? Are thereheavy, unstable items. near your desk or bed thatcould be moved1' What is the probability thatsomeone will be injured by various items if theyfall? Which ,areas of the building have a higheroccupant load and hence a potentially higher life

safety risk? Are there items that no longerserve a useful function and can be removed?What items can be relocated to prevent possibleinjury and do not need to be anchored toprevent damage or loss?

• If something slides or falls, in what directionis it likely to go? While the answer to thisquestion is not always obvious, it may be usefulto rearrange some furniture and move tall orheavy objects to where they cannot block a dooror an exit. Shelved items might be rearrangedso that heavier items are near the bottom andlighter ones near the top. Incompatiblechemicals can be moved to prevent mixing if thecontainers break. Excess supplies or inventorycould be stored in the original shippingcontainers until ready for use, in order to reducethe possibility of breakage.

Upgrade Details There are manytechniques available to reduce potentialnonstructural earthquake damage. Possibleupgrade schemes might include one or more ofthe following measures: use anchor bolts toprovide rigid anchorage to a structural floor orwall; brace the item to a structural wall orfloor; provide a tether or safety cable to limitthe range of movement if the item falls orswings; provide stops or bumpers to limit therange of movement if the item slides; provideflexible connections for piping and conduitwhere they cross seismic joints or connect torigidly mounted equipment; attach contents to ashelf, desktop, or countertop; provide baseisolation or seismic shock absorbers forindividual pieces of vital equipment.

Some of these methods are designed to protectthe functional integrity of a particular item,some are designed merely to reduce theconsequences of failure. It is important tounderstand the applicability and limitations ofthe various upgrade schemes and to select anappropriate scheme for a particular item in aparticular context.

Critical and expensive items warrant specializedattention. For essential facilities in areas wheresevere shaking is anticipated, any or all of thefollowing elements may be needed in order toprovide an appropriate level of nonstructuralprotection: specialized engineering expertise,higher design forces than those required by thecode, experienced specialty contractors, specialconstruction inspection, load-rated hardware,vendor-supplied equipment that has been testedon a shaking table, special design details such asbase isolation for individual pieces ofequipment, larger seismic gaps to preventpounding between adjacent structures, or stifferstructural systems such as shear walls to avoidexcessive distortion of the structural framing.

Organimtional Planning Programs Inan organizational setting, an effective programto reduce nonstructural earthquake hazards mayhave to be integrated with other organizationalfunctions, including earthquake preparedness,emergency response, facilities maintenance,procurement, long-term planning, and/orfacilities development. Some organizationsmight choose to embark on an ambitiousprogram to anchor all of their existingequipment and contents, while others mayconcentrate on new facilities and newequipment. Many different implementationstrategies are possible. Programs to developemployee awareness and provide emergencytraining might be in order for someorganizations, since a successful nonstructuralhazards reduction program has to address themany human factors issues along with theengineering issues.

BUILDING CODEREQUIRE:MENTS FORNONSTRUCTURALCOMPONENTSBy and large, advances in earthquakeengineering made in recent decades have beensuccessfully applied to the task of making

building structures safer. In comparison, ther,ehas been much less application 'Of this technicalknowledge to the nonstructural components ofbuildings, although this is gradually changing.Design professionals, oode committees, andbuilding owners are learning that the seismicresistance of critical nonstructuraf componentsmust be addressed as part of the design process,since failures of nonstructural ,components maythreaten the safety of building occupants andr,esult in significant financial loss.

Code Philosophy Surveys of eXlstmgbuildings indicate that many nonstructural itemsare never explicitly designed to resist horizontalforces. Instead, they are instaIled in accordancewith oommon construction practice, whichvaries little from seismic to nonseismic areas.Modern building codes typicaHy include someseismic provisions, that apply to a limited list ofnonstructural items. Many nonstructural itemsare not specifically addressed in the provisionsand may therefore be interpreted as beingexempt from code requir,ements. For example.some specific code provisions, apply to concretemasonry unit fences taBer than 6 feet, but a 5foot tall masonry wall without properreinforcing can also be a hazard.

The fact that the building code is not as specificabout nonstructural items as it is about thestructural portions of buildings is indicative ofthe general intent of the earthquake provisionsto provide a minimum level of life safety and toavoid legislating property damage controlmeasures. In general, the concepts of life safetyand prevention of structural ,coHap,se have beenus,ed almost interchangeably in the thinkingunderlying the earthquake regulations in thebuilding code, although it is apparent that thereare significant nonstructural dangers to life andlimb as well. In some cases, the potential fornonstruetural property loss or outage is a strongreason for obtaining more than the codeminimum level of protection. Indeed, evencode requirements in early 1994 for the design

of nonstructural items in medical facHides inCalifornia, which were more stringent thanthose for offioeand r,esidential occupancies,wer,e apparently not restrictive enough tocompletely prevent disruption of servicefollowing the January 1994 Northridgeearthquake.

The point of this discussion is to emphasize thelife safety focus of current building codeprovisions, which are intended primariilly toreduce potential injuries, not to prevent costlydamage or loss of function. Code provisions,for nonstructural components are subject torevision every three years, and in the futurethese provisions may be revised to aim for ahigher level of nonstructural protection.

Engineering Design To design protectivedevices such as bolted connections. snubbers, orrestraining cables. engineers use a percentage ofthe weight of the object as the horizontalearthquake force that must be resisted by thedesign details. Design guidelines dev,eloped bythe National Earthquake Hazards ReductionProgram (NEHRP) are contained in NEHRPRecommended Provisions jor the Development ofSeismic Regulations for New Buildings ['9].Many state and local codes have adopted similardesign provisions for nonstructural components.These provisions specificaIlyaddress earthquakeinertial forces. The engineer must also accountfor the effects of buHding distortion (i.e.,seismic relative displacements between twoconnection points in the same building orstructural system) and the effects of buildingseparations (i.e., seismic relativ,e displacementsbetween two connection points on separatebuildings or structural systems) in the design.

The following is a brief description of thesimplest type of engineering design procedure.Minimum design l,evels for architectural,mechanical, and electrical systems andcomponents ,are described in the NEHRPprovisions. The provisions specify horizontal

seismic force factors to be used for the designof specific items, such as partitions, parapets,chimneys, ornaments, tank supports, storageracks over 8 feet tall, equipment or machinery,piping, and suspended ceilings. According tothe NEHRP procedure, the design force dependson a variety of factors such as, the seismiczone, the type of component, the location of theitem within a building, and the type ofoccupancy. Design forces are generally greaterfor emergency generators than for HVACequipment, greater for police and fire stationsthan for ordinary office buildings, and greater atthe roof than at the ground.

To use a specific case, the specified horizontalforce for a piece of rigid equipment situated atground level in a commercial facility in the LosAngeles area is 40% of the weight of the item.If the equipment weighs 1000 pounds, theengineer must design the bracing and floor. orwall anchorage details to resist 400 pounds ofhorizontal force acting through the center ofgravity of the item in any direction. If the itemis used to store hazardous contents or is locatedon a floor above ground level, the NEHRPprovisions require higher design forces. Undersome circumstances, an owner who isparticularly concerned about postearthquakeoperations may want a greater level ofprotection than is provided by the minimumrequirements in the NEHRP provisions. In thiscase, the owner and engineer or equipmentvendor should discuss the performance criteriaat the beginning of the project, as described inChapter 7.

This discussion of seismic forces is intended toillustrate the design procedure and themagnitude of the loads, not to turn thelayperson into an engineer. This guide does notadvocate the use by nonengineers of thecalculation procedure described above.

SEISMIC HAZARDThe seismic risk for a particular nonstructuralcomponent at a particular facility is governed bya variety of factors, including the regionalseismicity, the proximity to an active fault, thelocal soil conditions, the dynamic characteristicsof the building structure, the dynamiccharacteristics of the nonstructural componentand any connections to the structure, thelocation of the nonstructural component withinthe building, the function of the facility, and theimportance of the particular component to theoperation of the facility. While all of thesefactors may have to be considered in theevaluation of equipment in a hospital or nuclearfacility, we will consider only the issue ofregional seismicity for the purposes of thisdiscussion.

The seismic hazard in a given region orgeographic location is related both to theseverity of ground shaking expected in the areaand to the likelihood, or probability, that agiven level of shaking will occur. Seismologistsreview historical earthquake activity, locationsand characteristics of mapped faults, andregional geology to estimate the seismic hazard.This information is often depicted on a seismichazard map.

For the purposes of this guide, seismic hazardhas been characterized in terms of three levelsof shaking intensity: namely light, moderate,and severe. The seismic hazard maps presentedin Figure 7 show the geographic areas in theUnited States where light, moderate and severeshaking are likely to occur in futureearthquakes.

For engineering purposes, earthquake shaking isoften characterized by an effective peakacceleration (EPA), measured as a percentage ofthe acceleration of gravity. The effective peak