Earthquake Risk Management: A Toolkit for Decision-Makers · Jennifer Rinna Fred Turner PRODUCT 2.2 PROJECT CONTRACTORS EQE International, Inc. 1111 Broadway, 10th Floor Oakland,

California SeismicSafety Commission

Proposition 122 Seismic Retrofit Practices Improvement ProgramProduct 2.2 Earthquake Risk Management Tools for Decision-MakersSSC Report 99-04

Earthquake RiskManagement:

A Toolkit for Decision-Makers

Proposition 122 Product 2.2Earthquake Risk Management: A Toolkit For Decision-Makers i

© 1999 California Seismic Safety CommissionALL RIGHTS RESERVED

No part of this document may be reproduced or transmitted in anyform or by any means, electronic or mechanical, includingphotocopying, recording, or by any information storage andretrieval systems, without permission in writing from the CaliforniaSeismic Safety Commission.

California Seismic Safety Commission1755 Creekside Oaks Drive, Suite 100

Sacramento, California 95833PHONE: (916) 263-5506

FAX: (916) 263-0594

http:\\www.seismic.ca.gov

ii Proposition 122 Product 2.2Earthquake Risk Management: A Toolkit For Decision-Makers

SEISMIC SAFETY COMMISSION

State of CaliforniaGray Davis, Governor

Patricia Snyder, ChairwomanSocial Services Representative

Daniel Shapiro, S.E., Vice ChairmanStructural Engineering

Assemblywoman Elaine White AlquistState Assembly

Representative: William Gates

State Senator Richard AlarconState Senate

Representative: Chris Modrzejewski

Lloyd S. CluffUtilities Representative

Jerry C. Chang, P.E.Soils Engineering

Robert DownerInsurance Representative

Scott P. HaggertyCounty Government Representative

Jeffrey A. JohnsonSeismology

Gary L. McGavin, AIAArchitectural/Planning

Lowell E. ShieldsMechanical Engineering

James E. SlossonGeology

Keith M. WheelerEmergency Services Representative

Donald O. ManningFire Protection Representative

Proposition 122 Product 2.2Earthquake Risk Management: A Toolkit For Decision-Makers iii

PROPOSITION 122 OVERSIGHT PANEL

Commissioner Lowell E. Shields, Chairman

Commissioner Dan Shapiro

Ross Cranmer

William E. Gates

Robert Hamilton

Fredrick M. Herman

Dr. Wilfred Iwan

Roy G. Johnston

David J. Martinez

Frank E. McClure

Joel A. McRonald

Steve Patterson

Stuart Posselt

SEISMIC SAFETY COMMISSION STAFF

Dick McCarthy, Executive Director

Henry Reyes, Product 2.2 Project Manager

Karen Cogan

Kyeshia Davis

Judy Deng

Kathy Goodell

Chris Lindstrom

Carmen Marquez

Ronnie Mitchell

Jennifer Rinna

Fred Turner

PRODUCT 2.2 PROJECT CONTRACTORS

EQE International, Inc.1111 Broadway, 10th FloorOakland, CA 94607-5500PHONE: (510) 817-3100FAX: (510) 663-1050http:\\www.eqe.com

Dr. Charles R. Scawthorn, S.E., Principal-in-Charge

Ronald O. Hamburger, S.E.

William M. Bruin, P.E.

iv Proposition 122 Product 2.2Earthquake Risk Management: A Toolkit For Decision-Makers

Executive Summary

California’s next earthquake couldaffect your community or business!

Are you prepared?

The only way you can answer thisquestion is to have a clearunderstanding of your potentialearthquake risk. Once the risk isdefined, the best way to protect thelives, property, and economic well-beingfor which you are responsible is toimplement a comprehensive earthquakerisk management program.

This Toolkit for Decision-Makersprovides the necessary tools fordeveloping an effective program. Itprovides basic information on thefollowing:

§ What earthquakes are,

§ Typical earthquake effects inCalifornia,

§ Causes of earthquake damageand loss,

§ Assessing the potential fordamage and loss to the buildingstructures and equipmentsystems in your community orbusiness,

§ Selecting an appropriateapproach to reduce earthquakerisk to acceptable levels, and

§ How to develop and implementthe selected approach.

In order to be effective, an earthquakerisk management program must involveparticipation and have the support of alllevels of the community or businessenterprise, including the executivedecision-makers, their managementstaff, technical and administrativesupport staff, constituents, andemployees. Often, it will be necessaryto retain professional consultants toassist with the implementation of phasesof the program.

This Toolkit is intended for executivedecision-makers, their managementstaff, and their technical andadministrative support personnel. Itprovides the information they need tocreate and manage an effectiveprogram for understanding andmitigating the seismic risk to buildingsand equipment systems. Usefulinformation for other participants in theprocess is available from sourcesreferenced in this Toolkit.

Many California communities, agencies,and businesses have already acted tounderstand and mitigate their potentialearthquake losses. A companionvolume to this Toolkit, MitigationSuccess Stories, provides examples ofsuccessful earthquake risk managementand loss reduction programs inCalifornia. The examples give usefulinsight into the practical aspects of theearthquake risk management process.

Proposition 122 Product 2.2Earthquake Risk Management: A Toolkit For Decision-Makers v

Table of Contents

Page

1. INTRODUCTION............................................................................................ 1-1

1.1 Purpose and Intent............................................................................. 1-1

1.2 Organization....................................................................................... 1-2

2. EARTHQUAKE RISK MANAGEMENT ......................................................... 2-1

2.1 Introduction......................................................................................... 2-1

2.2 Overview of Earthquake Risk ............................................................ 2-1

2.3 Earthquake Hazard ............................................................................ 2-3

2.4 Earthquake Damage and Loss.......................................................... 2-5

2.5 Mitigation Alternatives ........................................................................ 2-8

2.6 Earthquake Risk Management Decision-making .............................. 2-11

2.7 Implementing the Earthquake Risk Management Program .............. 2-14

2.8 Summary............................................................................................ 2-16

3. ASSESSING EARTHQUAKE RISK AND ALTERNATIVES ......................... 3-1

3.1 Introduction......................................................................................... 3-1

3.2 Assessing Earthquake Risk - Overview ............................................ 3-1

3.3 Identifying the Assets at Risk ........................................................... 3-4

3.4 Determine Acceptable Risk .............................................................. 3-7

3.5 Data Collection................................................................................... 3-16

3.6 Building Screening ............................................................................. 3-20

3.7 Building Assessment ......................................................................... 3-25

3.8 Equipment Screening......................................................................... 3-30

3.9 Equipment Assessment .................................................................... 3-43

3.10 Loss-of-Use Assessment................................................................... 3-45

3.11 Alternatives......................................................................................... 3-48

3.12 Baseline Risk ..................................................................................... 3-48

3.13 Summary............................................................................................ 3-50

TABLE OF CONTENTS

vi Proposition 122 Product 2.2Earthquake Risk Management: A Toolkit For Decision-Makers

Page

4. DECIDING WHAT TO DO ............................................................................ 4-1

4.1 Introduction......................................................................................... 4-1

4.2 Decision Analysis ............................................................................... 4-4

4.3 Benefit-Cost Analysis......................................................................... 4-6

4.4 The Retrofit Decision ......................................................................... 4-11

4.5 Olive Grove High School Example .................................................... 4-11

5. IMPLEMENTING THE EARTHQUAKE RISK MITIGATION PROGRAM..... 5-1

5.1 Introduction......................................................................................... 5-1

5.2 Earthquake Risk and Limited Resources .......................................... 5-1

5.3 Coordinating the Program ................................................................. 5-2

5.4 Funding the Program ......................................................................... 5-3

5.5 Retention of Professionals ................................................................. 5-5

5.6 Emergency Plans and Risk Transfer................................................. 5-8

5.7 What to Do after an Earthquake ........................................................ 5-11

6. REFERENCES ............................................................................................. 6-1

APPENDICES

Appendix A GLOSSARY

Appendix B RESOURCES

Appendix C EARTHQUAKE HAZARD

Appendix D EARTHQUAKE VULNERABILITY

Appendix E EQUIPMENT ASSESSMENT METHODOLOGY

Appendix F TYPICAL CONSULTANT WORK STATEMENT

Appendix G WORKSHEETS

Proposition 122 Product 2.2Earthquake Risk Management: A Toolkit For Decision-Makers 1-1

1. Introduction

…rational action is merely a question of calculating the chances [and the consequences].

- Raymond Aron, The Opium of the Intellectuals

Earthquakes are serious problems forCalifornia. They cause damage tobuildings and lifelines. In turn, this damagecan cause injury, loss of life and economichardship, and disrupt communities,organizations, and businesses. Executivedecision-makers are responsible forprotecting their enterprises1 from such loss.Since most executives are not earthquakeexperts, they need tools to deal with thisproblem.

1.1 Purpose and Intent

This Toolkit provides an overview of theearthquake risk management process, aswell as detailed, step-by-step information onhow to implement the process.

In most enterprises the decision-maker willset earthquake risk management as apriority, select or approve specific strategicapproaches to risk management, andauthorize and monitor program progress.However, much of the earthquake riskmanagement work must be done by others,including department managers, andadministrative and technical support staff.This Toolkit provides useful information forall these users. We recommend that

1 Through this Toolkit, we use the term enterprise tomean that community, public agency, orcommercial entity for which the decision-maker isresponsible.

everyone read this introductory chapter. Itguides the readers to those sections theyare most likely to need.

This Toolkit is intended for the followingindividuals:

§ Decision-Maker – The person whoprovides strategic direction for theenterprise. Decision-makers includemayors, supervisors, and membersof boards of direction.

§ Risk Manager – The person theappointed to develop and implementthe risk management program. Itmay be the City Manager, Director ofPublic Works, Chief FinancialOfficer, or their designee.

§ Financial Manager – The personresponsible for maintaining thefinancial accounts for the enterprise.It may be the Chief Financial Officer,Comptroller, or Treasurer.

§ Asset Manager – The personresponsible for maintaining thephysical property for the enterprise.It may include the Director of PublicWorks, Building Official, CityEngineer, or Facilities Manager.

INTRODUCTION

Proposition 122 Product 2.21-2 Earthquake Risk Management: A Toolkit For Decision-Makers

1.2 Organization

Chapter 2 is primarily intended for the RiskManager, although some Decision-Makerswill find the material of interest. Chapter 2discusses:

§ Earthquake Risk – The likelihood ofdamage and consequent loss.

§ Hazard – The probable intensity ofearthquake natural effects, such asshaking, ground fault rupture andliquefaction.

§ Damage -- The physical disruptiondue to an earthquake, such ascollapsed buildings, walls, ceilingsand fixtures, broken pipes, fires, anddamaged highways and bridges.

§ Loss – The human and financialconsequences of damage, includinginjuries or deaths, the costs ofrepair, or loss of revenue.

§ Mitigation – Any measure taken toreduce earthquake risk. Mitigationcan take many forms, includingbuilding strengthening, occupancyreduction, change of function,equipment anchoring or bracing,effective emergency andcontingency planning, and/orprocuring earthquake insurance2.

§ Decision-Making – Analyzing dataon the above issues and puttingthem into a rational frameworkwhereby certain mitigationalternatives emerge as the mostappropriate solution for the specificsituation at hand.

2 Note, however, that insurance only providesreimbursement for part of the financial loss anddoes not reduce damage and/or risk of injury.

§ Implementation – Putting themitigation program into action.

Chapter 3 is a step-by-step guide toassessing earthquake risk and evaluatingalternatives for reducing it. The entirechapter is of interest to the Risk Manager.The Asset Manager and Financial Managerwill also find some sections pertinent. Thebasic steps include:

§ Identifying the Assets at Risk (ofinterest to the Risk Manager) – Aninventory of everything the Decision-Maker is responsible for protectingthat could be damaged or lost in anearthquake

§ Framing the Problem (RiskManager) – Determiningperformance goals for the physicalassets at risk, that is, tolerable levelsof damage for each asset for twodifferent earthquake scenarios.

§ Data Collection (Risk Manager andAsset Manager) – Collectingavailable information on theconstruction of the physical assetsso that the existing level of risk canbe determined.

§ Building Screening (Risk Managerand Asset Manager) – Performingrapid evaluations of the probableearthquake performance of buildingsto determine whether they are likelyto meet the selected performancegoals.

§ Building Assessment (RiskManager and Asset Manager) –Performing more detailedassessment of the probableearthquake performance of buildingsthat fail the screening test anddeveloping mitigation concepts forthem.

INTRODUCTION


§ Equipment Screening (RiskManager and Asset Manager) –Performing rapid assessments of theprobable performance of criticalequipment and systems.

§ Equipment Assessment (RiskManager and Asset Manager) –Performing more detailedassessments of equipment andsystems that fail the screening testand developing mitigation conceptsfor them.

§ Financial Loss Assessment, (RiskManager and Financial Manager) –Estimating the potential financialconsequences of damage.

Chapter 4 provides a framework fordecision-making. This will be of interest tothe Risk Manager and the Decision-Maker.

Once the risk has been assessed, and amitigation program decided upon, it remainsto implement the program, that is, to do thework. Chapter 5 discusses practical issuesand steps involved in doing this. It will be ofprimary interest to the Decision-Maker.

Finally, a glossary and technical informationon hazard and earthquake structuralperformance are included in theappendices, where the reader is alsodirected to publications and to resources onthe Internet. Also contained in theappendices are clean copies of the Chapter3 worksheets as well as sample scope-of-work statements that can be used toprocure the services of professionalconsultants needed to assist with some ofthe above tasks.


2. Earthquake Risk Management

2.1 Introduction

Earthquakes are a significant risk inCalifornia. Everyone knows this, but whatto do about that risk, and how, is not soclear. This chapter provides an overview ofthe earthquake risk management process.The next three chapters provide detailedinformation on how to implement thisprocess.

2.2 Overview of Earthquake Risk

Earthquake loss results from a specificchain of events, illustrated in Figure 2.1.The links in this chain include:

§ The earthquake causes a variety ofearthquake hazards, including faultrupture, ground shaking (the primaryhazard), liquefaction and otherground failures, and water wavehazards called tsunamis andseiches.

§ For various reasons, which wediscuss below, many buildings andother structures cannot fully resistthese hazards, and sustain somedegree of primary damage.Depending on the severity of thehazards and the vulnerability of theconstruction, primary damage can

range from minor cracking to totalcollapse.

§ Even when a building sustains nostructural damage, its contents maybe severely damaged. For certainoccupancies, such as hospitals oremergency communication centers,damage to contents can becatastrophic. For any building, it isexpensive and time-consuming torepair.

§ Primary damage can lead tosecondary forms of hazard anddamage such as releases ofhazardous materials, major fires, orflooding.

§ Damage results in loss. Primaryloss can take many forms, but lifeloss or injury is the major concern.Financial loss, as well as loss offunction, are also serious issues.The likelihood of sustaining a loss istermed risk.

§ Primary losses lead to secondarylosses such as loss of revenuesresulting from business interruptionand loss of market share and/orreputation. These secondary formsof loss can affect enterprises in boththe public and private sectors.

Primary Interest:Risk Managers

Secondary Interest: Decision-Makers

EARTHQUAKE RISK MANAGEMENT


EARTHQUAKE OCCURS

PRIMARY DAMAGE:Building/Structural,

Nonstructural/Equipment



SECONDARY HAZARD/DAMAGE:Fire, Hazmat, Flooding...


PRIMARY LOSS:Life/Injury, Repair Costs, Function,

Communications/Control...



SECONDARY LOSS:Business/Operations Interruption,

Market Share, Reputation...



PRIMARY HAZARDS:Faulting, Shaking, Liquefaction,

Ground Failure, Landslide, Tsunami...



HAZARD

LOSS or RISK

DAMAGEor

VULNERABILITY

Figure 2-1: Earthquake Loss Process



2.3 Earthquake Hazard

Earthquake hazard can be expressed andmeasured in a variety of ways. Prior to theinvention of modern scientific instruments,earthquakes were qualitatively measured bytheir effect or intensity, which varied frompoint to point. With the deployment ofseismometers, instrumental quantification ofthe entire earthquake event becamepossible. Charles F. Richter was the first todefine earthquake magnitude on the so-called Richter scale in 1935. A number ofdifferent scales for magnitude and intensityhave been developed subsequently1.

In the United States, intensity is qualitativelymeasured using the Modified MercalliIntensity (MMI) scale (see Table C-1 inAppendix C). Engineers and scientistsquantify seismic intensity in terms of peakground acceleration (PGA) and othermeasures. PGA is often expressed in termsof a fraction of the acceleration of gravity(g), such as 0.5g or 50% of the accelerationof gravity. Following each majorearthquake, the United States GeologicalSurvey (USGS) and the Strong MotionInstrumentation Program of the CaliforniaDivision of Mines and Geology (CDMG)typically publish maps showing thedistribution of earthquake intensity inthroughout the affected region. Figure 2-2shows the MMI distribution published for the1994 Northridge earthquake.

1 Earthquake magnitude and ground shakingintensity are analogous to a lightbulb and the light itemits. A particular lightbulb has only one energylevel, or wattage (e.g., 100 watts), which isanalogous to an earthquake's magnitude. Near thelightbulb, the light intensity is very bright, whilefarther away the intensity decreases. Similarly, aparticular earthquake has only one magnitude, butit has many intensity values depending on distance.

The identification and determination ofearthquake hazards for a site or communityis a critical element in the earthquake riskmanagement process, and Appendix Cdiscusses this aspect in more detail.

In brief, earthquake ground shaking isusually very strong on or very close to thefault, and decreases or attenuates withdistance from the fault. This attenuationdepends on the magnitude of theearthquake, and the geology of the region.Soils, especially soft soils such as old filled-in marshes or ancient lake beds, can greatlyincrease or amplify the ground motion. Thiseffect of soils is a primary factor in theintensity of the shaking. Though shakinggenerally attenuates with distance from thefault, it can still be very strong at a greatdistance on poor soils.



Figure 2-2: Modified Mercalli ground shaking intensities for the 1994 Northridge earthquake(courtesy TRINET)

BLUE AREAMMI < V

Low ShakingIntensity

RED AREAMMI > IX

Severe ShakingIntensity

Epicenter of1994 Northridge

Earthquake



2.4 Earthquake Damage and Loss

This section summarizes the kinds ofdamage and loss that earthquakes cancause. Appendix D provides more detailedinformation on the earthquake performanceof specific structure types.

Buildings can be damaged in any ofseveral ways in an earthquake. Below arethe most common types of damage:

§ Exterior walls can fall away. This isthe primary deficiency ofUnreinforced Masonry (URM) andolder Tilt-Up buildings, and canresult in partial or even total collapseof the roof and floor systems, posinga significant life hazard and,typically, a major financial loss.

§ Concrete columns can shear,dropping the building in a pancakemode of collapse. This failure posesa great life safety hazard and iscommon in older, reinforcedconcrete frame buildings.

§ Concrete and masonry walls cancrack, causing unsightly damage. Ifcracking becomes severe, pieces ofthe wall can become loosened andfall away from the structure, creatinga safety hazard. This is common inolder, lightly reinforced structures.

§ Certain kinds of steel beam-columnconnections can crack. Thisproblem was discovered onlyrecently, following the 1994Northridge earthquake, when manysteel building frames were found tohave brittle fractures. None of thebuildings with this damagecollapsed, but they may beweakened. Inspection and repair

costs can result in significantfinancial loss to the owners.

§ Wood-frame buildings can slide offtheir foundations. This is theprimary mode of failure for oldersingle-family dwellings with a crawlspace beneath the first floor. Inaddition, the crawl space cancollapse, when the so-called cripplewalls supporting the first floor fallover. This failure mode usually doesnot cause life loss, but can destroythe building and leave the residentshomeless.

Structural damage occurs in varyingdegrees, depending on the intensity ofearthquake hazards and individual buildingdesign and construction quality. While mostbuildings are not expected to collapse,damage is common. As a rule of thumb,certain types of construction, dating tocertain eras, have particular vulnerability:

§ Masonry buildings constructed priorto the Second World War (early1940s) are typically unreinforced,and have a high likelihood of exteriorwall and parapet collapse, as well assevere wall cracking, even inmoderate shaking.

§ Multi-story concrete framesconstructed from the 1950s to early1970s often have inadequatereinforcing in their columns.Consequently, these buildings havethe potential for a pancake type ofcollapse, with great life loss.

§ Steel moment frame buildings of the1970s, 1980s, and early 1990s havewelded beam-column connectionsfor seismic resistance. As noted



above, certain kinds of theseconnections have recently beenobserved to crack in earthquakes.

§ Tilt-up buildings (a commoncommercial and industrial building inCalifornia) constructed prior to 1994may have a particularly weak wall-roof connection. This has resulted inmany instances of damage andcollapse. This weakness was firstobserved in the 1971 San Fernandoearthquake, so newer tilt-ups mayhave better connections and manyolder ones have already beenretrofitted.

When a building is damaged, it requiresinspection, perhaps vacating, and structuraland/or nonstructural repairs before normaloccupancy and function can be resumed.

Nonstructural damage and repairs can beas significant as structural damage.Tumbled and broken furniture andequipment; fallen ceilings; cracked floors;broken water, sprinkler, and/or gas lines;broken windows; extensive cracking of non-weight-bearing interior walls; broken heatingor air conditioning equipment; spillednoxious materials; and other types ofnonstructural damage can result inoccupant injuries or death, major costs,extended vacancies, and loss of productiveuse of the building.

For hospitals, fire stations, or emergencycommunication centers, this nonstructuraldamage can be catastrophic since thesefacilities are most needed following anearthquake. However, every enterprise cansuffer severe financial hardships from of thistype of disruption.

Infrastructure: When ground motion in aneighborhood is strong enough to causesignificant damage to buildings,infrastructure is usually damaged as well.Serious infrastructure damages include thefollowing:

§ Freeways, bridges andtransportation structures cancollapse. Examples include theI-880 Cypress Structure in the 1989Loma Prieta earthquake, and thecollapsed bridges and interchangeson Los Angeles area freeways in the1994 Northridge earthquake.CALTRANS has made significantimprovements in the ability of ourroadways to withstand strongearthquakes, but some vulnerabilityremains.

§ Underground piping can break,especially in areas of poorer soils.The combination of broken gas andwater lines provides the fuel for fireswhile taking the water necessary tofight them. More noxious materials,such as sewage or crude or refinedoil, may also be spilled, causingmajor occupancy and clean-upproblems.

§ Water and wastewater treatmentplants can be damaged, resulting inprolonged loss of potable waterservice, and spilling of raw sewageinto bays or rivers.

§ Electric power andtelecommunications may sufferwidespread short-term outages.Except in the hardest hit areas,these systems have performedreasonably well in recent quakesand been restored within a few days.



For certain types of businesses orservices, however, even a day'sdisruption to these vital services canbe a major problem.

Primary damage can lead to secondaryforms of damage, such as releases ofhazardous materials, major fires, orflooding. Fires frequently result fromearthquakes because damages releaseready fuels for fires and causes numerousignitions. Impaired fire departmentresponse (which results from disruptedcommunications and loss of fire fightingequipment and personnel in damagedstations) and lack of water for firefighting(due to damaged infrastructure) can lead toa catastrophic situation.

Loss: Damage results in loss. Primary losscan take many forms.

§ Life loss or injury is the primaryconcern2. If buildings collapse,major releases of hazardousmaterials and/or fires can beprevented; deaths and seriousinjuries would be reduced.

§ Major damage to property ispossible even when life loss/injury isminimal. The cost to repair orreplace damaged buildings,contents, equipment, and otherinfrastructure is a direct financialloss. Additional losses are incurredas a result of disruption of use.

2 Earthquake-related natural hazards, such astsunami or landslides, have killed hundreds ofpeople in other parts of the earth, and have causedsome fatalities in California. However, great loss oflife from these causes seems unlikely in California.

§ Loss of function can also be a majorloss. Loss of hospitals, city offices,emergency communication centers,and other important public functionsare clear examples. If schools areclosed for an extended period oftime, the postponement of educationis a loss.

§ Primary losses lead to other forms ofloss, such as loss of revenuesresulting from business interruption,loss of market share and/orreputation. These forms of loss canaffect both the public and privatesectors.

§ In the private sector, businessinterruption (usually termed ‘BI’) is aserious matter that some companiesinsure against. Businessinterruptions in recent Californiaearthquakes have caused the failureof a number of small and medium-sized businesses. Failedbusinesses and reduced commercialactivity bring significant reductions insales, property, and other taxes,adversely affecting a localgovernment’s finances.

§ In the public sector, besides theobvious disruption to public services,many local governments rely onrevenue from ports, airports, or otherspecial facilities. If these aredisrupted, finances are strained.Decreased tourism in the SanFrancisco Bay Area following the1989 Loma Prieta earthquakereduced sales and airport taxrevenues.

§ When businesses or factories, withtheir jobs, are closed, it affects the



well-being of the community. This isanalogous to loss of market share inthe private sector. If a jurisdictionrelies on revenue or jobs from afacility, and the operation of thatfacility is disrupted for a prolongedperiod, the customers go elsewhereand never return. After the 1995Kobe earthquake in Japan, the Portof Kobe -- the world’s largestcontainer port prior to theearthquake -- closed for about oneyear. In that time, it lost severalmajor-shipping lines to other ports.Though the Port of Kobe was closedfor one year, the customers werelost for many years, if not forever.

2.5 Mitigation Alternatives

Damage and loss can be reduced, ormitigated, in any of a number of ways.Figure 2-3 is modified from the previousfigure, and indicates how mitigation ispossible at each link in the earthquake riskchain. Just as Figure 2-1 laid out theearthquake loss chain of causation, Figure2-3 shows that breaking that chain at anylink reduces or eliminates the loss.Typically, the earlier (higher) in the processthe chain is broken, the more effective is themitigation.

Each of the mitigation approaches below isa proven technology:

§ Hazards such as faulting andshaking can be mapped and, inmany cases, have been mapped indetail in California. Over the last twodecades, the California Division ofMines and Geology (USGS) hasmapped the most active faults inCalifornia. Shaking intensity mapsare also readily available, even

through the Internet (see AppendixB). Such maps identify the presenceof these hazards. When thepotential for faulting or shaking issevere, the best mitigation is not tolocate important facilities on sitessubject to them.

If the hazard is poor soil, whereliquefaction or ground failure mightoccur, then ground remediation maybe appropriate. Recent decadeshave seen the development of newmethods for soil improvement andliquefaction reduction, including soilmixing, stone columns, soil wicks,and chemical and pressure grouting.Appendix C provides additionalinformation on this topic.

§ Primary damage mitigation is withinthe purview of structural engineersand other design professionals, whohave developed competencies inbracing, strengthening, or otherwiseimproving the earthquakeperformance of buildings and otherstructures, nonstructural elements,equipment, and contents. Later inthis report and in the appendices, wediscuss some of these techniques inmore detail.

§ Secondary damage results from theinteraction of several problems, andcan be very complex to deal with.Therefore, it is best mitigated prior tothe earthquake, through betterhandling of materials andinfrastructure improvements. Sincethis cannot be done everywhere,secondary damage must be dealtwith through improved emergencyresponse: acquisition of the



necessary equipment and on-goingtraining and exercises for personnel.

§ In certain circumstances, earthquakeinsurance can also be an effectivemethod of mitigating financial loss.However, it does nothing to addresslife loss or injury, and typically only

partially offsets primary financialloss.

The further down in the damage chain oneprogresses, the more difficult and lesseffective is mitigation. Secondary losses,such as damage to reputation, often cannotbe fully mitigated.



MITIGATION

Hazard mapping; groundremediation; tsunami walls...

Bracing and strengthening,reduction of mass, base isolation,supplemental damping...

Improved storage andinfrastructure, better emergencyresponse...

Improved emergency planningand response; insurance...

EARTHQUAKE OCCURS



















Figure 2-3: Earthquake Mitigation Spectrum



2.6 Earthquake Risk ManagementDecision-making

The fundamental problem of earthquake riskmanagement is not to find any solution, butto find a “best” solution. What this “best”solution will be depends on thecircumstances, values, and priorities of theindividual enterprise. The decision-makingprocess illustrated in Figure 2-4 is useful indecisions between available alternatives.The process consists of three basic steps:

Step 1 - Estimate the Risk§ Define the Problem – The Risk

Manager, with the concurrence ofthe Decision-Maker, must identifythe assets at risk and the acceptableperformance for each asset.Typically, the assets at risk compriseall that property that the enterpriseowns, occupies, relies upon, or mustsafeguard as part of its basicmission. At a minimum, acceptableperformance implies protection of lifesafety. Preservation of ability toprovide service, protection of culturalresources, and minimization offinancial loss should also beconsidered in setting performancegoals for some assets.

§ Quantify the Baseline Risk – TheRisk Manager, with assistance fromthe Asset Manager, the FinancialManager and technical consultants,must estimate the potential life,financial and other losses, undercurrent conditions. This process isdescribed in some detail in the nextchapter.

§ Determine if Further Action isNeeded – If the baseline risk is

acceptable, no further action isrequired. Otherwise, alternativemitigation approaches should beevaluated.

Step 2 - Examine MitigationAlternatives

§ Select the Basis for Analysis –The Risk Manager, with assistancefrom the Decision-Maker, shoulddetermine the constraints underwhich the enterprise must operate.For example, mandated retrofittingof residential buildings may not bepolitically feasible because thepublic will vote out whoever attemptsto enact it. In such a case, the basisfor analysis would be voluntaryretrofitting, and the alternativeswould consist of distributinginformation, providing financialincentives, and other more palatablemeasures.

§ Identify the Alternatives – TheRisk Manager and Asset Manager,together with assistance fromtechnical consultants, should identifya broad spectrum of mitigationalternatives that fit within the givenconstraints. The previous sectionindicated how each link in the chainof earthquake loss causation offersopportunities for mitigation, oftenmultiple ones. Develop as manyalternatives as possible. Don’t worryabout their feasibility or ranking.Such evaluations are made later inthe process.

§ Screen Alternatives – Once theRisk Manager, Asset Manager andtechnical consultants have



“brainstormed” a broad range ofalternatives, it may become ‘obvious’that some are not attractive orfeasible. Eliminate these fromfurther consideration.

§ Choose a Decision Method – TheRisk Manager and Decision-Makershould develop a framework andcriteria for choosing among thealternatives. This is a very importantstep, since the basis for a decisionmay be subject to close examinationafter the decision is made. Thereare many different methods andcriteria for deciding betweenalternatives, including simple scoringmethods, benefit-cost analysis andmulti-attribute utility theory. Refer toChapter 4 for more information onthe methods.

§ Describe the Alternatives – TheRisk Manager, with assistance fromthe Asset Manager, FinancialManager and technical consultants,should examine each feasiblealternative to determine its efficacyin reducing the risk to acceptablelevels. In order to do this, assumethat an alternative is implementedand then calculate the residual riskwith the same methods usedpreviously to determine the baselinerisk. Repeat this for eachalternative.

Step 3 - Make a Decision§ Collect and Organize the Data –

The Risk Manager should assembleinformation on the probableimplementation cost and the effect ofimplementation on the baseline risk(residual risk) for each alternative. It

is also important to determine howconfident (or certain) you are inassessing this data. Many decision-makers will want to avoid selectingan alternative that has a highlyuncertain cost or benefit. TheFinancial Manager and technicalconsultants should help the RiskManager to determine the level ofuncertainty.

§ Apply the Decision Method – TheRisk Manager, with the concurrenceof the Decision-Maker, shouldevaluate each alternative using thecriteria of the selected decisionmethod. Chapter 4 presentsinformation on the application of onesuch method.

§ Communicate the Results – Oncea specific set of alternativesemerges as the “best” solution, it isnecessary to explain the basis for itschoice to everyone who mustapprove of this decision. Differentstakeholders (such as tenants,owners, parents, ratepayers, andothers) will be interested in variousaspects of the decision. The RiskManager should attempt to identifyand address the needs of all suchpersons.

Making the decision is not always as easyas it sounds. Others will question, and thatwill require further analysis and justification.Eventually, however, it is desirable to obtainconsensus on the best alternative.



Define ProblemDefine Problem

ESTIMATERISK

MAKE ADECISION

EXAMINEMITIGATION

ALTERNATIVES

PROBLEMPROBLEM

Estimate Baseline RiskEstimate Baseline Risk

Select Basis for AnalysisSelect Basis for Analysis

Identify AlternativesIdentify Alternatives

Choose Decision MethodChoose Decision Method

Describe AlternativesDescribe Alternatives

Collect and Organize DataCollect and Organize Data

Apply Decision MethodApply Decision Method

Communicate ResultsCommunicate Results

DetermineFurther Action

Needed

DetermineFurther Action

Needed

Screen Alternatives

Screen Alternatives

MakeDecision

MakeDecision

Internal PolicyExternal

Constraints

Internal PolicyExternal

Constraints

Values Uncertainties

Values Uncertainties

StopStop

AlternativesEliminated

Y

N

FurtherAnalysis

FurtherAnalysis

ACTIONACTION

Figure 2-4: Earthquake Risk Management Decision Process



2.7 Implementing the EarthquakeRisk Management Program

Once a set of alternatives has beenselected, it remains to put the plan intoaction. The basic steps are shown in Figure2.5 and discussed below:

§ Funding – There are many ways topay for earthquake risk mitigation,depending on the circumstances ofyour enterprise. Public agenciesmay allocate funds from generalrevenues, levy special assessments,sell bonds, establish user’s feesand/or obtain grants from state orfederal programs. In the privatesector, there are analogous sourcesof funding: one-time charges, loansor bonds, and/or public subsidy.

§ Project Management – Actionrequires a dedicated staff formanaging the program; theengagement of specialists,consultants and/or contractors;scheduling the work; communicatingwith neighbors and affected parties;and follow-up to assure that goalsare being met.

§ Strategies – It is usually beneficialto conduct major strengthening andother large mitigation projects aspart of the overall CapitalImprovement Plan (CIP) or otherAsset Management Program.Smaller projects, such as bracing ofcontents and anchoring equipment,may be included within regularmaintenance outlays or fundeddirectly using general revenues.

§ Risk Transference – Instead ofreducing the potential for damage

and loss, it may be possible totransfer some of the risk to others.The most common method isthrough purchase of insurance.Recently, it has also becomepossible for some enterprises totransfer their risk to others throughthe securities markets, as analternative to insurance. It isimportant to note here that it isactually possible to transfer onlyparts of the financial risk to thirdparties.

§ Post-earthquake Action Plans – InCalifornia, it is seldom possible toeliminate earthquake riskcompletely. Therefore, everyenterprise should have anemergency response plan in place.The basis for this plan should be theresidual risk, that is, the portion ofthe baseline risk that theimplemented mitigation alternativescannot feasibly reduce.Understanding, preparing for, andclearly communicating this residualrisk is necessary to avoid surprisesand recriminations following anearthquake. It also should form thebasis for a recovery plan.



Obtain FundingGeneral revenues, special assessments, bonds,

user’s fees and/or grants from state or federal programs...

Obtain FundingGeneral revenues, special assessments, bonds,

user’s fees and/or grants from state or federal programs...

Program ManagementDedicate staff, find/retain specialists, consultants and/or contractors, schedule the work, communicate with neighbors, and affected parties

Program ManagementDedicate staff, find/retain specialists, consultants and/or contractors, schedule the work, communicate with neighbors, and affected parties

Decide on the Mitigation Alternatives

(Figure 2-4)

Decide on the Mitigation Alternatives

(Figure 2-4)

After the EarthquakeMaintain emergency plan, have backup sites ready,

engineers on-call…

After the EarthquakeMaintain emergency plan, have backup sites ready,

engineers on-call…

Risk TransferInsurance, capital markets...

Risk TransferInsurance, capital markets...

Emergency PlanDevelop as interim solution, and for on-going residual risk

Emergency PlanDevelop as interim solution, and for on-going residual risk

Implement CIP/Other ProjectsMulti-year implementation

Implement CIP/Other ProjectsMulti-year implementation

Residual RiskResidual Risk

Figure 2-5: Earthquake Risk Mitigation Program



2.8 Summary

This chapter has provided an overview ofthe earthquake risk problem, and a guide tothe management of this problem.

Earthquake risk management consists of aseries of rational steps aimed at:

§ identifying what is at risk – theassets,

§ assessing how the earthquakeplaces these assets at risk,

§ determining which alternatives mightreduce this risk ,

§ selecting the best alternatives for thespecific situation, and

§ putting these alternatives intopractice.


3. Assessing Earthquake Risk and Alternatives

3.1 Introduction

This chapter provides guidance onassessing the baseline earthquake risk. It isprimarily intended for the Risk Manager whomust initiate and lead the process ofearthquake risk assessment. In order toactually perform the risk assessment, theRisk Manager will need assistance from theAsset Manager, Financial Manager, andtechnical consultants. This chapter mayalso be of interest to those individuals.

3.2 Assessing Earthquake Risk -Overview

Assessment of earthquake risk consists of areview of buildings, non-building structures,and equipment for seismic vulnerabilities;relating these vulnerabilities to theearthquake hazard and determining theprobable extent of damage; and then,evaluating the probable losses resultingfrom this damage.

The Asset Manager, using guidelinespresented in this Toolkit, can conduct theinitial reviews of buildings, structures, andequipment for seismic vulnerability.However, detailed evaluation of earthquakevulnerability and the process of predictingdamage should be performed by structuralengineers or other professionalsknowledgeable and experienced inearthquake performance assessment. In

order to perform assessments of theseismic hazard this professional willtypically require the services of ageotechnical engineer, seismologist, orearth scientist. Some structural engineeringconsulting firms can offer these geo-hazardassessment services directly; however,most will wish to retain specialty geo-hazardconsultants.

Given that certain damage is expected tooccur, the Financial Officer can bestperform the assessment of losses . TheFinancial Officer should also be assisted bythose members of your staff who are mostfamiliar with the needs of your operationsand the ability to continue to operate, giventhat certain facilities are damaged orunavailable for use.

Since the comprehensive seismic review ofall structures and equipment can be asignificant undertaking (i.e., expensive),screening techniques have been developedto make this effort more reasonable.Specifically, screening consists of an initial,simple review of buildings and/orequipment, for the purpose of cost-effectively identifying those buildings orequipment, which are likely to performsatisfactorily in an earthquake. Many AssetManagers will be able to perform thisscreening with their own staff, usingprocedures described in this chapter.Buildings or equipment, which cannot be


Secondary Interest:Asset Managers

Financial Managers

ASSESSING EARTHQUAKE RISK AND ALTERNATIVES


screened out, must be reviewed in a moredetailed manner to identify key seismicvulnerabilities. It will typically be necessaryto retain an engineering consultant to dothis.

Once key vulnerabilities have beenidentified, there are usually severalalternatives available for addressing thesevulnerabilities. The basic process is shownin Figure 3-1, and consists of:

§ Identification of the Assets at Risk– The Risk Manager, with theconcurrence of the Decision-Maker,must identify the facilities and assetsthat may be affected, and potentiallydamaged or destroyed, by anearthquake. In addition to identifyingthese facilities, the Risk Managerand Decision-Maker must makesome basic decisions as to thedesired performance objective foreach facility – should it be functionalfollowing the earthquake, be allowedto sustain a moderate degree ofrepairable damage, or simplyprevented from collapse? Theprimary asset at risk is the safety ofpersonnel and the public, and theminimum performance level typicallydesired for this asset is preservationof life-safety.

§ Assessment of Facilities – TheRisk Manager should work with theAsset Manager to obtain evaluationsfor each building, equipment item,

and systems component identifiedas an important asset. Asmentioned above, several screeningtechniques (such as FEMA-154 forbuildings and MCEER 99-0008 forequipment) can be used to performinitial evaluations.

Once screening is completed, moredetailed evaluations must beperformed, typically relying ontechnical consultants. Part of thisprocess involves establishing theseismic hazard for each facility –that is, the likely intensity of shaking(taking into account the site-specificsoils), as well as the potential for soilfailure. At several steps in thisprocess, the facility may be found to“pass” – that is, the expectedperformance is satisfactory, and theassessment process is terminatedfor that facility.

§ Alternatives – Working with theAsset Manager and technicalconsultants, the Risk Managershould identify and evaluatemitigation alternatives, for facilitieswhere the expected seismicperformance is not satisfactory. Thisis discussed further below.

The remainder of this chapter discusses thisprocess in more detail.



Identify Assets at RiskIdentify Assets at RiskOccupantsBuildings

Other StructuresEquipment

InfrastructureOperations

ProfitsMarket ShareReputation

OccupantsBuildings

Other StructuresEquipment

InfrastructureOperations

ProfitsMarket ShareReputation

Buildings / StructuresBuildings / Structures EquipmentEquipment

Develop Performance ObjectiveDevelop Performance ObjectiveEstablishSeismicHazard

EstablishSeismicHazard

Is it OKper FEMA-

154?

Is it OKper FEMA-

154?

Is itOK perFEMA-310?

Is itOK perFEMA-310?

Is it OKper

MCEER99-0008?

Is it OKper

MCEER99-0008?

ALTERNATIVESALTERNATIVES

No

Yes

Yes

Yes

No No

Yes

No

Risk Screening

Detailed Review

StopStop

StopStop

StopStop

StopStop

Is itOK per

EquipmentAssessment?

Figure 3-1: Earthquake Risk Assessment



3.3 Identifying the Assets at Risk

Earthquake mitigation starts by defining theproblem, that is, what are the assets at risk?As a general rule of thumb,

whatever a Decision-Maker is responsible for,

is what is at risk from earthquakes.

This is at least true from the pragmaticviewpoint that the Decision-Maker can onlyaffect what he or she is responsible for.

The Risk Manager should start the processby developing a catalog of the assets atrisk. Tables 3-1 and 3-2 provide a samplecatalog of the typical assets that are at riskfrom earthquakes. Table 3-1 focuses on theprivate sector, and lists not only the assetsat risk, but also the threats that earthquakespose to these assets and, generally but notexhaustively, the mitigation alternativesavailable for countering each of thesethreats.

Table 3-2 provides similar information forthe public sector enterprise. In government,typically no one Decision-Maker will beresponsible for everything. Schools, waterutilities, and other public services may bethe responsibility of special service districts,independently elected. Even the mayor of alarge city or the city council is not typicallyresponsible for public utilities such as

telephones. However, this mayor or citycouncil, or state governor, will be expectedto act to protect the public interest if andwhen breakdowns occur in any arena andare not remedied in a timely manner. Whileperhaps not legally or literally responsible,high public officials will be held accountableif things go wrong for too long. In otherwords, the public sector has theresponsibility for protecting the public healthand safety, even if others must ultimately berelied upon to provided the neededservices.

Therefore, it is often in the best interest forall public Decision-Makers to provide localand regional leadership for a wide, if not full,earthquake mitigation program. Forexample, a mayor and mayoral staff shouldattempt an exhaustive identification of theassets at risk in their community, includingpublic and private assets, as the first steptowards earthquake risk mitigation. Thiscan then be pruned back, via regionalcoordination with the responsible agenciesand private owners, to those assets that arethe Decision-Maker’s direct responsibility, orcan be directly influenced, by the citygovernment.

Since the mitigation alternatives available tothe private sector tend to be the same asthose presented in Table 3-1, Table 3-2simply catalogs the impacts rather thanlisting mitigation alternatives.



Table 3-1

PRIVATE SECTOR ASSETS AT RISK

Asset / Loss Earthquake Threat Mitigation Alternatives

♦ Buildingdamage/collapse, viaground shaking, faultrupture, or otherearthquake hazard

§ Strengthen the building§ Base isolate the building§ Provide supplemental damping§ Provide ground or foundation improvements, if ground

failure is the issue§ Replace the building (i.e., move, or new construction)

♦ Building contentsdamage

§ Inventory all contents and brace or otherwise reducedamage

♦ Equipmentmalfunction

§ Identify and review critical equipment for continuity offunctionality during and after and earthquake (e.g.,check for relay chatter, backup power, water, fuel etc)

§ Assure equipment will not be damaged (i.e., brace etc)§ Provide redundant equipment§ Develop emergency plans and procedures for

equipment malfunction

q People/death andinjury

♦ Offsite threats § Identify and review neighborhood for earthquakehazards (e.g., tsunami, landslide) and threats (e.g.,nearby hazardous operations, such as a chemicalprocess plant)

§ Develop Emergency plans and procedures, includingpossible warning mechanisms

§ Build protective barriers§ Acquire protective equipment and training (e.g., fire

brigades)§ Modify offsite threat (e.g., earthmoving, for a landslide;

or buy out nearby hazardous operation; or move)q Building,

equipmentdamage/financialloss

♦ Same as above♦ Inventory

§ Same as above, plus§ Emergency plans and procedures to minimize damage

(e.g., recovery of inventory; quick shut-down of brokensprinklers)

§ Earthquake insuranceq Function/

BI, loss ofrevenue,marketshare

♦ Same as above plusloss of infrastructure(e.g., transportation),loss of vendors

§ Contingency planning for loss / replacement orrecovery of facilities (e.g., backup sites or suppliers,rapid recovery via pre-arranged inspection and repaircontractors)

§ Financial planning for loss of revenue§ Earthquake / Loss of profits insurance§ Planning for alternative production / transportation to

maintain market share



Table 3-2

PUBLIC SECTOR ASSETS AT RISK

Asset / Loss Earthquake Threat Impacts

q People/death andinjury

♦ Structuredamage/collapse,via ground shaking,fault rupture, or otherearthquake hazard

♦ Building contentsdamage

♦ Equipmentmalfunction

§ Residential – single family dwellings, apartments, hotels,dormitories

§ Commercial – offices, stores, factories, restaurants§ Public facilities – schools, correctional facilities, offices§ Public assembly – theaters, halls, stadiums§ Essential facilities – hospitals, police / fire stations§ Lifelines – power, water, sewer, gas and liquid fuels,

highways, ports, airports, railroads, telephone and othercommunications

§ Hazardous Facilities – dams, industrial facilitiesq Structure,

equipmentdamage/financialloss

♦ Same as above § For public sector, portion of repair costs not reimbursedby state / federal aid

q Function/BI, loss ofrevenue,marketshare

♦ Same as above § Employment – private sector loss of jobs (closedfactories, loss of tourism, …)

§ Tax base / revenues (sales, real estate, …)

q Reputation ♦ Lack of timelyrecovery

§ Loss of population§ Existing business decides to rebuild elsewhere§ Loss of new investment, development, tourism…§ Breakdown in political process – squabbling as to best

path to recovery …§ Loss of political office



3.4 Determine Acceptable Risk

Before beginning a seismic evaluation, theRisk Manager should establish its limits.This helps focus the risk-management efforton the information the Decision-Makerneeds. In the present situation, the mostimportant aspect of decision framing isdetermining the Decision-Maker’s policytoward facility performance, and to establishthe order in which risk-mitigation decisionswill be made. Therefore, the Risk Managershould begin the risk analysis by creating adecision hierarchy, which separatesdecisions into three groups: policy, strategy,and tactical.

§ Policy decisions will be resolvedfirst, before beginning the seismicrisk evaluation. As an example, anorganization must decide to attemptto reduce earthquake losses toacceptable levels, and determinewhat “acceptable” means. Policydecisions, like all decisions, oftenrequire additional information to befinalized, and may go throughseveral cycles of consideration,additional information required, etc.While the Decision-Maker mustultimately make policy decisions, theRisk Manager will usually have tosupport the process and mustultimately work within the frameworkof these policy decisions.

§ Strategic decisions are the real pointof the present seismic risk analysis.That is, the Risk Manager will gatherinformation on the seismic risk tofacilities for the purpose offacilitating strategic decisions. Anexample of a strategic decision isthat an office complex must remainoperational immediately following anearthquake or, alternatively, that it

can sustain damage, since itsfunctions are not immediatelyneeded.

§ Tactical decisions are made after thestrategic decisions. These are thedetail decisions that can be dealtwith later, and can perhaps bedelegated. An example of a tacticaldecision is that backup power mustbe available for an office complex, ifits required remain operationalimmediately following anearthquake. If the strategic decisionis that the office complex can sustaindamage, since its functions are notimmediately needed, then thetactical decision is that no backuppower is required.

This section leads the Risk Managerthrough the various steps necessary toestablish policy on seismic performance.This policy is established by settingperformance objectives for each facility.

A performance objective is a specification ofthe level of performance (limiting amount ofdamage) desired for various potentialearthquake scenarios. Generally, largedestructive earthquakes occur infrequently,while moderate, less destructiveearthquakes can be expected to occur moreoften. Typically, the Decision-Maker will bewilling to accept poorer performance (moredamage, increased hazard to life, increasedservice, and economic loss) in large,infrequent events than they are formoderate, more frequent earthquakes.



In this Toolkit, we suggest that the RiskManager set performance objectives for twodifferent levels of earthquake. These aredefined as follows:

§ Maximum Probable Earthquake(MPE). – This level of hazard isrepresentative of a severeearthquake that may occur one timeduring the life of a facility. We definethe MPE as having a mean returnperiod of approximately 500 years.In any 50-year period, there is, onaverage, approximately a 10%chance that ground motion of thisintensity will be exceeded.

For sites located adjacent to majoractive faults, the MPE can be takenas that intensity of ground shakinglikely to occur (50% probability ofexceedance) given that acharacteristic event occurs on thenearby fault. The California BuildingCode (CBC) requires that newbuildings be designed to resist thislevel of earthquake withoutendangering life safety.

§ Likely Earthquake (LE). – Thislevel of hazard is representative ofthe intensity of ground shaking likelyto be experienced one or more timesduring the facility’s life. We definethe LE as having a mean returnperiod of approximately 100 years.

In any 50-year period, there is, onaverage, approximately a 40%chance that such shaking will beexceeded.

In addition to the MPE and LE, someDecision-Makers may elect to protectcertain critical facilities for the most severeearthquake effects that could ever occur.There is great uncertainty in the definition ofsuch an event. For the purposes of thisToolkit, we recommend that the UpperBound Earthquake (UBE) defined in theCalifornia Building Code be taken asrepresentative of such an event. The UBEis defined as that intensity of groundshaking having a mean return period of1,000 years. In any 50-year period, onaverage, there is approximately a 5%chance that such shaking will be exceeded.

It is the Decision-Maker’s responsibility toselect an appropriate performance objectivefor each facility class for these variousearthquake events. This is a key anddifficult aspect of the entire earthquake riskmanagement process. Examples ofperformance levels, which are typicallyselected, are provided in the Table 3-3, as aguide. Table 3-4 describes the damage tobuilding structures and nonstructuralcomponents for each of the performanceobjectives described in Table 3-3.



Table 3-3

EXAMPLES OF TYPICAL PERFORMANCE OBJECTIVESFOR VARIOUS FACILITY-TYPES

Earthquake Event

Facility-type UBE(1,000-Year)

MPE(500-Year)

LE(100-Year)

Essential public facilities,• Hospitals• Police stations• Fire stations• Emergency communication centers

LS1 IO O

Public facilities with vulnerable occupants• Schools• Correctional Facilities

CP LS IO

Other public facilities CP LS -

Private commercial – emergency response LS IO O

Private commercial with hazardous materials LS IO O

Private commercial – essential operations LS IO O

Private commercial – ordinary operations CP LS -

Other private commercial facilities CP LS -

Multi-family residential buildings CP LS IO

Single-family residential buildings CP LS -

Historic buildings CP LS -1 Legend (refer to Table 3-4 for more detailed information):

CP – Collapse PreventionLS – Life SafetyIO – Immediate OccupancyO – Operational



Table 3-4

POST-EARTHQUAKE PERFORMANCE OBJECTIVES1

Objective Structural Performance Nonstructural Performance

Operational(O)

S-1 Structure is essentially undamagedand retains nearly all of its pre-earthquake strength and stiffness.Any minor damage sustained canbe repaired at convenience.Structure is safe for occupancy.

N-A Nonstructural components are essentiallyundamaged and all equipment, systems andutilities essential to normal operations arefunctional, though utility service may be suppliedfrom emergency sources. Building is suitable foruse in normal occupancy and to fulfill its primaryfunction.

ImmediateOccupancy

(IO)

S-1 Structure is essentially undamagedand retains nearly all of its pre-earthquake strength and stiffness.Any minor damage sustained canbe repaired at convenience.Structure is safe for occupancy.

N-B Nonstructural components essential to life safetyare including fire protection systems, emergencylighting and egress means are functional. Othernon-structural components may sustain minordamage and may or may not function, but do notpose a threat to life safety. Utility service may ormay not be available. Though the building issuitable for occupancy, it may not be availablefor use in its normal occupancy before somecleanup and repair is accomplished. Interruptionof service is expected to be limited

Life Safe(LS)

S-3 Structure has sustained somedamage and has experienced a lossof both stiffness and potentiallystrength. However, neither total norpartial collapse has occurred, andthe building retains some additionalcapacity to resist additional lateralloading, e.g. from after shocks. Thebuilding may not be safe for re-occupancy until temporary shoringor repairs are conducted.Permanent repair is feasible, thoughthey may potentially be quiteexpensive and time consuming

N-C Extensive damage to nonstructural components,systems and equipment. Utility service isgenerally not available and many systems wouldnot function even if service were available.Extensive damage due to water leakage frombroken piping. Substantial toppling and slidingof light components, however, no major hazardsoccur due to falling debris and egress ways arenot blocked. Interruption of service may be longterm.

CollapsePrevention

(CP)

S-5 Structure experiences extensivedamage with a substantial loss ofboth stiffness and strength.Although neither local nor globalcollapse has occurred, marginaladditional loading, as fromaftershocks could credibly causesuch collapse. The building is notsafe for occupancy and may not beeconomically or technically feasibleto repair.

N-E Widespread disarray and damage to contentsincluding toppling and sliding of many items ofcontents and equipment. Access and egressways may be impaired by debris. Thoughindividual large items may topple or fall, majornon-structural components that could pose ahazard to many people, such as largesuspended ceilings do not fall.

1 Performance Objective descriptions adapted from FEMA-273: NEHRP Guidelines for Seismic Rehabilitation ofStructures



Two worksheets are provided to assist theRisk Manager in setting performanceobjectives for the enterprise (see AppendixG for extra blank worksheets). These arethe Decision Hierarchy worksheet(Worksheet 1-A), and the Facility–typeDefinition worksheet (Worksheet 1-B). TheDecision Hierarchy worksheet is used toguide the process of strategic decision-making, including the establishment of thescope of the risk assessment and thedefinition of specific risk-managementobjectives. Working with the Decision-Maker, The Risk Manager should use thisworksheet to do the following:

1. First, choose a performance objectivefor the MPE and LE events for each ofthe several facility types. Fiveperformance options are offered:Operational (O), ImmediatelyOccupancy (IO), Life Safe (LS),Collapse Prevention (CP) or NotConsidered (N). These options aredefined in Table 3-4. For each class offacility listed on the worksheet (and forwhich the enterprise is responsible)circle the appropriate performanceobjective for both earthquakes.

2. Next, for each class of facility (exceptthose with a performance objective ofNot Considered for both earthquakes)determine whether the performanceobjectives are to be required (commonfor public facilities and high-risk privatefacilities) or encouraged (common formoderate- to low-risk private facilities).

Risk Manager: What you should do

Edit Worksheets 1-A and 1-B to match yourcircumstances. When considering policyoptions, confer with legal counsel to ensurethat potential alternatives meet local lawsand regulations. When considering facilitytypes, confer with zoning officials (publicagency) or asset management (private) toensure conformity with standard facility-usecategories.

Present both worksheets to your Decision-Maker, along with copies of performanceobjectives and earthquake event definitions.The purpose is to introduce them to thedecisions you will ask them to make, andthe order in which you intend to do so.

Ask the Decision-Maker:

(1) To approve the facility-type classificationsystem of Worksheet 1-B,

(2) To approve the decision hierarchy, thatis, the nature and order of the decisionsshown in Worksheet 1-A, and

(3) To resolve the policy decisions in thetop section of Worksheet 1-A.

Then begin gathering the proper informationfor making strategic decisions.


Proposition 122 Pr oduct 2.23-12 Earthquake Risk Management: A Toolkit For Decision-Makers

Following completion of the Decision-Hierarchy worksheet, the Risk Managershould complete the Facility-type Definitionworksheet. This worksheet lists the samefacilities types included on the Worksheet 1-A.

The Risk Manager should assign each ofthe assets to be included in the riskassessment to one of these categories.Use Column C of Worksheet 1-B to list theassets placed in each facility class. Publicagencies may do this by associating eachfacility type with local zoning or use codes,or in some cases with a list of specific

addresses. Private entities may wish tobegin with a list of enterprise operations andthen determine the addresses at whichthese operations occur. Attach additionalpages if Column C does not provide enoughroom.

Taken together, the Decision Hierarchyworksheet and Facility-type Definitionworksheet unambiguously define theearthquake performance objectives for theenterprise.



Worksheet 1-A: Decision Hierarchy

POLICY DECISIONS – MADE BEFORE RISK ASSESSMENT

Decision-Maker: For each facility-type and earthquake event, choose and circle the appropriateperformance objective: Operational (O), Immediate Occupancy (IO), Life Safe (LS), CollapsePrevention (CP) or Not Considered (N). Also choose and circle a corresponding enforcementalternative: required (R) or encouraged (E). For precise definitions of facility-types, seeWorksheet 1-B for examples. For precise definitions of performance objectives, see Table 3-4.

Facility type MPE(500 year)

LE(100 year) Mandate

Essential public facilities O IO LS CP N O IO LS CP N R E

Public facilities with vulnerable occupants O IO LS CP N O IO LS CP N R E

Other public facilities O IO LS CP N O IO LS CP N R E

Private commercial - emergency response O IO LS CP N O IO LS CP N R E

Private commercial with hazardous materials O IO LS CP N O IO LS CP N R E

Private commercial – essential operations O IO LS CP N O IO LS CP N R E

Private commercial - ordinary operations O IO LS CP N O IO LS CP N R E

Other private commercial O IO LS CP N O IO LS CP N R E

Multi-family residential O IO LS CP N O IO LS CP N R E

Single-family residential O IO LS CP N O IO LS CP N R E

Historic O IO LS CP N O IO LS CP N R E

STRATEGIC DECISIONS – MADE AFTER RISK ASSESSMENT

The Risk Manager will collect information on all facilities with a performance objective other than“N” in the table above. With the aid of the Asset Manager and engineering consultants, the RiskManager will evaluate each facility to determine if it is capable of meeting the selectedperformance objective. For those facilities that do not meet these objectives, the Risk Manager,assisted by the Asset Manager and engineering consultants, will recommend mitigationalternatives and select the alternative that best meets the stated objective. The Risk Manager willprovide the Decision-Maker with cost and benefit information necessary to evaluate therecommendation and make the final decision.


3-14 Proposition 122 Product 2.2Earthquake Risk Management: A Toolkit For Decision-Makers

Worksheet 1-B – Facility-type Definition

Risk Manager: Unambiguously define each facility-type you will use (e.g., by zoning or use code, by exactaddress, etc.) to prevent misunderstanding on the category of any particular facility. Decision-Maker:Adjust or endorse this classification system.

(A) Facility-type (B) Examples; notes (C) Zoning or use codes,addresses

Essential public facilities

Fire & police stations, hospitals,emergency operation &communication facilities, water supplyfacilities

Public facilities withvulnerable occupants

Schools, non-emergency medicalfacilities, correctional facilities,nursing homes

Other public facilities

Libraries, office buildings, publicworks equipment yards, localvehicular bridges, wastewatertreatment facilities

Private commercial -emergency response

Telephone switching facilities, privateambulance services, private medicalfacilities

Private commercial -hazardous materials

Chemical and gas manufacturers anddistributors, industrial facilities

Private commercial -essential operations

Bank data processing centers,customer service centers,manufacturing facilities in certainhigh-tech industries

Private commercial - ordinaryoperations

Research & development facilities,warehouses, retail, wholesale,service, transportation, constructionfacilities

Other private commercialfacilities Other facilities

Multi-family residentialApartment buildings, condominiumassociations

Single-family residential1Detached or attached single-familydwellings.

HistoricLocal, state, or national historicregistry

1 Public agencies rarely examine seismic risk for single-family residences, except in the case of unreinforcedmasonry (URM) buildings.



Moderate and Large Earthquakes

Performance objectives discussed in this Toolkit refer to earthquake size and probability. Twoearthquake sizes are considered: a large, rare event, and a moderate and more likely event.Think of the 1906 San Francisco earthquake as the former and the 1994 Northridgeearthquake as the latter.

The large earthquake is conventionally used to plan for earthquake life safety. This event hasa 10% probability of being exceeded in 50 years, or about 0.2% per year. Its mean returnperiod (average time between events) is roughly 500 years (average is emphasized, sinceactual intervals between events can vary substantially). This is the MPE event.

Planning for business operations more commonly considers a 5- to 10-year period. Themoderate event considered herein is one with 10% chance of exceedance in 10 years, orabout 1% annual probability of exceedance, or a mean return period of approximately 100years. This is the LE event.

The figure shown at rightillustrates the mathematicalrelationship:

( ) tPT

111

1

−−=

or

t

TP

−−=

111

where,

T is the mean return period inyears, and

P is the probability ofexceedance within theplanning period, t (in years).

0.001

0.01

0.1

1

0 10 20 30 40 50

Planning period t , years

Pro

babi

lity

of e

xcee

danc

e in

t y

ears

Very large

Large

Moderate

Some highly hazardous facilities plan for an earthquake with 5% exceedance probability in 50years; this is the very large earthquake in the figure or the UBE event.

Moderate Earthquake(LE)

Large Earthquake(MPE)

Very Large Earthquake(UBE)



3.5 Data Collection

After identifying the assets at risk, anddetermining the acceptable level of risk,gather sufficient data on the facilities,population, and assets at risk toestimate the baseline risk.

Information Gathering - During thisphase, the Risk Manager gathers dataon the hazard and vulnerability of eachfacility, and the costs and benefits ofvarious potential risk-mitigation options.Data-gathering tasks and theirassociated level of effort are listed inTable 3-5.

Risk Managers performing this processfor a large number of assets will want touse Facility Task List worksheet(Worksheet 2). This simple form allowsidentification of the individualsresponsible for providing the requiredinformation for each asset, and can alsobe used as a checklist to track progressin gathering this information. To useWorksheet 2, list each of the facilitiesidentified on Worksheets 1-A and 1-B asrequiring seismic examination(performance objectives O, IO, LS, orCP for either of the two earthquakelevels). As an individual is identified toperform steps in the informationgathering for each facility, list thecontact information for this individual onthe form, under the appropriate categoryand line.

There are three steps to theinformational phase:

1. Risk Screening. As a first step, werecommend that all facilities besubjected to a rapid screening. Thisis a first examination of the facilitiesin order to identify those that areclearly adequate. This will allow the

Risk Manager to focus remainingresources on facilities that pose thegreatest risk.

Rapid screening should beperformed for both buildingstructures and important equipmentand systems. Sections 3.6 and 3.8,respectively, provide detailedtechnical guidance on how toperform this task for buildings andequipment. The Asset Managershould perform this screening withsupport from technical staff. Someenterprises may need to retainconsultants for this task. Thescreening exercises will identify, ona preliminary basis, those facilitieslikely to fail their performanceobjectives under as-is conditions, aswell as the probability for this failure.

2. Detailed Risk Assessment andOptions Review. Facilities identifiedin risk screening as unlikely to meetthe selected performance objectivesshould be reviewed by qualifiedstructural and mechanical engineers.The engineers must estimate, foreach of the earthquake event, theprobable casualties, damage costs,and duration of facility outage.When these detailed evaluationsconfirm that probable performancedoes not meet the goals, theengineers should suggest practicalseismic mitigation options andestimate their effectiveness inreducing probable casualties,damage and facility outage duration.

In addition to engineering solutions,the Risk Manager should alsoexamine the costs and benefits ofnon-engineering risk-mitigationoptions such as insurance, facilityrelocation, and emergencyoutsourcing options. The Risk



Manager will need to engage theassistance of the Financial andAsset Managers in estimating thefinancial losses associated with lossof use, including relocation costsand temporary loss of market share.

3. Benefit-Cost Analysis. The RiskManager will tabulate in a worksheetthe costs and benefits of risk-mitigation options examined in Step2. Options that do not help a facilitymeet a performance objective will bescreened out. Remaining optionswill be sorted in order of decreasingbenefit-to-cost ratio, and the topcontenders proposed to the decisionmakers for consideration.

Ensure Information Quality - Note thatat each stage, information should beobtained from those best qualified toprovide it (e.g., building department orfacility manager for age and type ofconstruction, and chief financial officerfor cost of capital). All informationshould be carefully documented andfiled for later retrieval and review.

Whenever parties with whom theDecision-Makers are unfamiliar providedata, it is important to document thatparty’s qualifications and, in case ofdoubt, get the Decision-Makers’ buy-inon those qualifications. It is generallybetter to pay more for information thatthe Decision-Makers will trust than to tryto convince them of its adequacy afterthe fact.

In some cases, definitive information,such as the year in which a particularfacility was built, will be available. Inother cases, experts will have to providean estimate.

It is important to separate actualinformation from expert preferences.They may inadvertently color theirinformation to favor a particularoutcome. The Decision-Makers’preferences, informed by expertinformation, should guide the decision.For that reason, the Risk Managershould be involved in each step andremain on the alert for potentially biasedinformation.



Table 3-5

DATA-GATHERING TASKS

WorksheetNumber

WorksheetTitle

FacilitiesCovered

WorksheetCompleted by

EstimatedEffort

per Facility

2 Facility TaskList All (one worksheet) Risk Manager 5 to15

minutes total

3 Rapid BuildingScreening1 All buildings Asset Manager or

structural engineer 1 or 2 ph2

4 BuildingAssessment

Buildings with rapidscreening score ≤ 2.0 structural engineer 8 to 24 ph

-3 EquipmentScreening All equipment Asset Manager or

mechanical engineer 8 to 24 ph

5 EquipmentAssessment

Equipment items withscreening score ≤failing score

mechanical engineer 16 to 48 ph

6 Loss-of-UseAnalysis

Worksheet 4 facilitiesand Worksheet 5equipment items

Risk Manager aidedby Asset Managerand FinancialManager

4 to 8 ph

7 Benefit-costAnalysis All (one worksheet) Risk Manager 4 to 8 ph total

1 Worksheet 3 adapted from FEMA-154: Rapid Visual Screening for Potential Seismic Hazards – A Handbook .2 ph = person hour of effort, by appropriate professional. These estimates are very approximate and will vary by

specific facility-type. They are offered here as a rough guide for planning purposes only.3 Individual worksheets for specific equipment-types can be found in MCEER 99-0008: Seismic Reliability

Assessment of Critical Facilities – A Handbook, Supporting Documentation, and Model Code Provisions .



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3.6 Building Screening

3.6.1 Purpose of Building ScreeningBuilding screening determines whethera facility represents a significant enoughrisk to warrant more detailed evaluation.Although this can be done in a numberof ways, we recommend the use of themethod described in:

FEMA-154: Rapid VisualScreening of Buildings forPotential Hazards - AHandbook.

This method provides a convenient,standardized approach to buildingscreening that can be implemented withminimum effort.

Using the FEMA-154 methodology,calculate a structural risk screeningscore (typically on the order of 0.0 to 6.0for high seismic areas like California) forall buildings under consideration.FEMA-154 provides worksheets toassist in this calculation (see Worksheet3). This scoring system is based on arapid visual inspection and on importantfeatures such as construction materials,site soil conditions, and buildingconfiguration. A typical screening takesabout 15 minutes or so to perform foreach facility, plus travel time andapproximately ½ hour to gatherpreliminary information that may not beapparent at the site.

Buildings with a structural risk screeningscore of about 2.0 or less are typicallydeemed to represent a significant lifesafety risk and therefore should besubjected to a detailed buildingevaluation. If Immediate Occupancy(IO) or Operational (O) performance is

desired for a facility, we suggest aminimum score of 3.0 be employed as“passing” the screening process.Buildings scoring between 2.0 and 3.0may not present a significant life safetyrisk; however, these structures maysustain sufficient damage to be out ofoperational for some period of time afteran earthquake.

The Structural Risk Screening Score

The structural risk screening score, S,developed in the FEMA-154 rapid visualscreening procedure is an initialmeasure of building earthquakeadequacy, and is based on theprobability of major damage that mayoccur. Major damage in FEMA-154 arerepairs that would cost approximately 60percent of the building replacementvalue (not including land and siteimprovements). At this level of damage,it was judged that occupant life-safetybegins to become a concern.

A screening score of S=1 indicates thatthe probability of major damage for aparticular building is 1 in 10, given theoccurrence of expected ground shaking.S=2 corresponds to a probability of 1 in100, S=3 is 1 in 1000, and so on. Ahigh S score is good or “passing”, whilea low S denotes probable poorearthquake performance.

In general, if S is less than 2.0, it wasjudged that the seismic performance ofthat building may not be adequate, andmay possibly represent a life-safetyhazard. If Occupancy (IO) orOperational (O) post-earthquakeperformance is desired, a higher cut-offscore, such as 3.0, may be appropriate.



3.6.2 Gather PreliminaryInformation

Before performing a visual examination,the inspector charged with the screeningshould obtain three basic pieces ofinformation: structure type, year ofconstruction, and soil profile.

Structure Type – For structure type,consult an experienced buildingdepartment official or a structuralengineer. FEMA-154 uses aclassification system of 12 structuretypes, detailed in Table 3-6. A structuralengineer or highly experienced buildingofficial with access to constructiondrawings can determine structure typedefinitively. Structure type can beascertained visually with lessconfidence.

Year Built – Year of construction istypically available from the buildingdepartment or from the senior facilitymanager. Use the age of the oldestsignificant portion of a building. Theevolution of building codes in Californiais such that within given eras, buildingsof certain construction types are likely tohave common deficiencies and

vulnerabilities. The years when buildingcode regulations changed significantly,resulting in substantially reducedvulnerability, are commonly termedbenchmark years. Table 3-6 showsbasic benchmark years for typicalCalifornia buildings designed to theUniform Building Code (UBC).Benchmark year is used as a modifier inthe FEMA-154 methodology, asdiscussed below.

Soil Profile – Soil type is an importantaspect of shaking intensity and, for aparticular address, is often availablefrom the building department or from alocal geotechnical engineer. Thestructural engineer or possibly thearchitect who designed the building mayhave a copy of the original geotechnicalreport on file. If no specific informationis available, estimate a soil type basedon general geologic data, such as mapspublished by the California Departmentof Mines and Geology (CDMG) and theUnited States Geologic Survey (USGS).Determine the soil classification fromone of these sources in accordance withTable 3-7. Acquire a copy of thedocumentation used to determine thesoil profile in anticipation of the buildingassessment.



Table 3-6

FEMA-154 STRUCTURE TYPES

Code Meaning Benchmark Year

W Wood frame 1949

S1 Steel moment resisting frame 1997

S2 Steel braced frame 1988

S3 Light metal frame -1

S4 Steel frame with concrete shear wall 1976

C1 Concrete moment-resisting frame 1976

C2 Concrete shear wall 1976

C3/S5 Steel or concrete frame with masonry infill -

PC1 Tilt-up 1973

PC2 Precast frame -

RM Reinforced masonry 1976

URM Unreinforced masonry -1 No benchmark year – buildings of this type do not receive a positive age modifier.

Table 3-7

FEMA-154 SOIL PROFILES

Soil Profile Description

SL1 Rock or still clay less than 200 feet thick overlying rock

SL2 Cohesionless soil or still clay greater than 200 feet deep

SL3 Soft or medium stiff clay 30 or more feet deep



3.6.3 Performing Rapid Screening

As noted above, rapid screening ofbuildings can be performed usingappropriate techniques. The FEMA-154methodology is currently the mostwidely used and is recommended here.It requires completion of a one-pageform, reproduced here as Worksheet 3.Refer to FEMA-154 for additionalinformation. Copies of FEMA-154 areavailable directly from the FederalEmergency Management Agency(FEMA):

FEMA Distribution CenterP.O. Box 2012

Jessup, Maryland 20794PHONE: (800) 480-2520

FAX: (301) 497-6378

Any rapid screening procedure willtypically follow the same basic steps:the inspector completes theidentification section of the form, drawsa scale drawing of the facility footprint,attaches a photograph of the facility,and circles the structure type indicatedby the structural drawings. If structuraldrawings are not available, the inspectormust judge the possible structure typesand circle all of them. The inspectorthen circles modifiers relevant to thebuilding (in FEMA-154, these are highrise [8+ stories], plan irregularity, etc.).The inspector then sums the basic scorefor each possible structure type with themodifiers below it.

Setting up a Building Screening Task

If the inspectors or engineers have notperformed a rapid screening before,arrange for a training session. This istypically a 4- to 8-hour session and mayrequire two days of an instructor’s time,who should be an earthquake engineeror structural engineer familiar with theFEMA-154 rapid screeningmethodology.

Locate the structural drawings and thegeotechnical (or soils) report for eachfacility to be screened. Identify theperson who will provide access to thefacility to those charged with performingthe screening. Provide this information,along with copies of Worksheet to thescreeners. For each building reviewed,one copy of Worksheet 3 should befilled out.

Compile screening records afterwards,along with all structural drawings andgeotechnical reports. Identify thefacilities with “failing” structural riskscreening scores (S) as well as thosewith potential nonstructural fallinghazards. Contract with a licensedstructural engineer to perform a detailedbuilding assessment for thesepotentially vulnerable facilities.



Worksheet 3 – Rapid Building Screening1

1 Adapted from FEMA-154 Rapid Visual Screening and Data Collection Form



3.7 Building Assessment

Buildings that received a "failing"screening score represent a significantpotential for life-threatening damageand/or a significant potential for loss offunction (depending on the policydecision made). Buildings withnonstructural falling hazards alsorepresent a risk of life loss. All suchfacilities should be subjected to detailedevaluations to estimate probable lossesincluding life loss, repair costs, andlikely period of closure. Contract with alicensed structural engineer to performthese evaluations.

The evaluation should estimate thelosses for the existing facility for both aLE and MPE (baseline risk). In addition,the evaluation should includeidentification of potential mitigationmeasures, rough order of magnitude1

estimates of their potentialimplementation costs, and an estimateof the potential losses if the mitigation isimplemented (residual risk). Theengineer should complete Worksheet 4for each building evaluated.

The engineer should recommendupgrade alternatives that seem mostappropriate, given the existing facilityvulnerability and the performance goalsselected by the Decision-Maker. Thefollowing publications provide useful

1 rough order of magnitude or ROM is a termcommonly employed in construction estimating(Means, 1996) to indicate preliminary or initialcost estimates, which have an accuracy ofperhaps + or -20%. Note that ROM differsfrom the scientific term order of magnitude,which is a range of magnitude extending fromsome value to ten times that value.

information on common retrofit andupgrade strategies:

FEMA-273 and FEMA-274:NEHRP Guidelines for SeismicRehabilitation of Buildings andCommentary,

SSC 96-01: Seismic Evaluationand Retrofit of ConcreteBuildings (California SeismicSafety Commission), and

FEMA-172: NEHRP Handbookfor Seismic Rehabilitation ofExisting Buildings.

The FEMA-273 and SSC 96-01 reports,though intended for design of seismicupgrades, also may be used forevaluation of probable buildingperformance. However, thesemethodologies are quite detailed andare intended primarily for use in theupgrade design process. Generally, itwill be more cost-effective to performevaluations of probable seismicperformance using the followingpublication:

FEMA-310: Handbook for theSeismic Evaluation ofBuildings – A Prestandard.

FEMA-310 is a recent publication andsupercedes FEMA-178 (also termedATC-22), with which many engineersmay be more familiar (see Appendix B).The FEMA-310 evaluation methodologyis a two-tiered process, as shown inFigure 3-1. The Tier 1 evaluationprocess is shown in Figure 3-2 andconsists of responding to a series ofBasic Structural Checklists, one perbuilding type. The Tier 2 process, ifrequired, relies on more detailedstructural analyses.



It is important to emphasize to theengineer that the purpose of theanalysis is to develop approximateestimates and schematic retrofit options.The engineer need not do detailedstructural analyses or design of seismicretrofits. These steps will be undertakenonly if the Decision-Makers choose toperform a retrofit.

The Decision-Maker should be awarethat retrofit costs based on preliminaryevaluations could be excessively low orhigh. If many facilities are beingevaluated, this variation should not be asignificant concern as, on the average,the estimated costs should be adequate.However, on an individual building or

facility basis, costs estimated throughrapid analyses can be substantially off.Detailed evaluations, such as thoseconducted in accordance with FEMA-273 or SSC96-01 should be performedearly in the retrofit design process toconfirm budget allocations and to allowany necessary adjustments to be made.

This step is for information purposes,not for the detailed preparation of designdrawings. The level of effort to provideapproximate analyses will vary, but mayrange from 24 to several hundred hoursper facility.

Setting up a Building Assessment Task

Contract with a licensed structural engineer to complete Worksheet 4. One suchworksheet is required for each facility whose FEMA-154 structural risk screening score(S) was 2.0 or less. For facilities with a building score greater than 2.0, but identified ashaving a nonstructural falling hazard, contract with a structural engineer to assess riskfrom the falling hazard only.

Provide the engineer with the soil report and structural drawings acquired in preparationfor the building screening. If possible, provide the engineer with all the constructiondrawings, including architectural and mechanical drawings. Arrange for the engineer tohave access to inspect the building. Ensure that the engineer understands the level ofdetail required.

The structural engineer will benefit from the assistance of a licensed geotechnicalengineer. Hire one geotechnical engineer for all the building assessments, or allow thestructural engineer to select the geotechnical engineer.

Compile Worksheet 4 from all building assessments after the assessment is complete.Use these in the benefit-cost analysis to follow in Chapter 4.



Understand the Evaluation Process

General Provisions

1) Collect Data and Visit Site2) Determine Region of Seismicity3) Determine Level of Performance

Evaluation Requirements

Benchmark Building? OR

1) Complete the Structural Checklist(s).2) Complete the Foundation Checklist.3) Complete the Nonstructural Checklist(s).

Tier 1: Screening Phase Figure 3-2

Quick Checks

Deficiencies? FurtherEval?

EVALUATE Building using one of thefollowing procedures:1) Linear Static Procedure2) Linear Dynamic Procedure3) Special Procedure Tier 2: Evaluation Phase

ANALYSIS

FULL BUILDING or DEFICIENCY-ONLY EVALUATION

Deficiencies? FurtherEval?

Comprehensive Investigation (Nonlinear Analysis)

Tier 3: Detailed Evaluation Phase

Deficiencies?BuildingComplies

Buildingdoes NOT

Comply

Final Evaluation and Report

Mitigate

no noyes

yes

yesno no

yes

yesno

Figure 3-1: FEMA-310 Evaluation Process



Benchmark Building?

Selection of Checklists

Region of LowSeismicity & Life-Safety

Level of Perf?

Complete the Region of

Low Seismicity Checklist

Complete the BasicStructural Checklist

Quick Checks

Complete the SupplementalStructural Checklist

Quick Checks

Complete the BasicNonstructural Checklist

Quick Checks

Complete the SupplementalNonstructural Checklist

Quick Checks

Structure Deficiencies

FurtherEvaluationRequired?

ImmediateOccupancy

Level of Performance?

Region of HighSeismicity (O or LS) or

Region of ModerateSeismicity (IO)?

Complete theFoundation Checklist

Quick Checks

no

yes

no

yes

yes

no

no

yes

Required Information: Level of Performance Region of Seismicity General Building Description

Figure 3-2: FEMA-310 Tier 1 Evaluation Process



Worksheet 4 – Building Assessment

Facility: Date:

Engineer: Interest Rate Employed:

PRESENT VALUE OF RETROFIT COSTS

Retrofit OptionBest

Estimate ($)Contingency1

($)Duration2

(months)

Do Nothing (As-is Conditions) - -

Option 1 (describe):



1 Contingency is an amount held in reserve to account for unforeseen conditions.2 Duration is an indication of the amount of time required to implement the retrofit.

LOSS ESTIMATES

MPE (500-Year) LE (100-Year)

Retrofit Option Loss Item Best3 High3 Best High

As-is Conditions Repair Cost

Loss-of-Use4

Option 1 Repair Cost

Loss-of-Use3


Loss-of-Use3


Loss-of-Use3

3 The “best” estimate is the engineer’s estimate of the most probable outcome. There should be roughly a50% chance that the actual outcome would be either higher or lower than this estimate. The “high”estimate represents the engineer’s estimate associated with a high confidence of non-exceedance.Engineers familiar with the performance of Probable Maximum Loss estimates will associate this “high”estimate with a PML.

4 Loss-of-Use is the duration (measured in days or months) of the time that the facility will not fulfill itsnormal function.



3.8 Equipment Screening

3.8.1 Purpose and Summary ofEquipment Screening

Equipment screening determineswhether there is a significant risk thatthe facility will be inoperative or pose athreat to life safety because ofequipment failure. Similar to theprocess described above for buildingscreening, this is done by calculating arisk score (typically ranging from 0.0 to6.0). If the performance goal for eitherthe LE or MPE is operational (O) orImmediately Occupiable (IO), one riskscore is calculated for operationalequipment, one for life-safetyequipment. Otherwise, only life-safetyequipment must be screened.

Operational equipment includes allcomponents necessary to supportnormal operation of the facility. Life-safety equipment includes allcomponents necessary to support lifesafety, as well as any components thatwould jeopardize life safety if they failed.For example, emergency lightingsystems are considered life safetyequipment because they are needed toprotect people from injury when exiting abuilding. A cylinder containingflammable gas is also considered lifesafety equipment because, if it were tofail, it could cause a fire or explosionand jeopardize safety.

Each equipment system screened willbe assigned a risk score by theequipment inspector. The RiskManager must determine whether thesescores are adequate, using the passingscores listed in Table 3-8.

Equipment systems with a failing scorerepresent a significant risk of eitheroperational or safety-related failure, andtherefore should be subjected to adetailed evaluation of risk-mitigationmeasures.

The score sheets used for this processare analogous to those used in FEMA-154, and were developed as part of anew system-reliability assessmenttechnique documented in:

MCEER 99-0008: SeismicReliability Assessment of CriticalFacilities: A Handbook,Supporting Documentation, andModel Code Provisions.

MCEER 99-008 is available from theMultidisciplinary Center for EarthquakeEngineering (MCEER) at:

MCEERRed Jacket Quadrangle

State University of New York at BuffaloBuffalo NY, 14260, USAPhone: (716) 645-3391FAX: (716) 645-3399

http:\\[email protected].



Table 3-8

PASSING SCORES FOR EQUIPMENT SCREENING1

Life-safetyEquipment

OperationalEquipmentFacility Occupancy

MPE LE MPE LE

Emergency response or vulnerablepopulation 4 3.5 3 2.5

All others 3 2.5 2 1.5

1 Passing scores for the large event are documented in MCEER 98-0016: Appropriate Seismic Reliabilityfor Critical Equipment Systems – Recommendations Based on Regional Analysis of Financial andLife Loss. Passing scores for the moderate event are 0.5 lower than for the large event, based on theobservation that typical equipment systems are 2 to 4 times less likely to fail in a 100-year earthquakethan in a 475-year earthquake, equating with a logarithmic decrement of 0.5 in failure probability.

Setting up an Equipment Screening Task

If the equipment inspectors have not used the MCEER 99-0008 methodology before,arrange a training session. This is typically a 4- to 8-hour session and may require twodays of an instructor’s time. The training should be given by an earthquake engineer ora mechanical engineer experienced in using the methodology.

Find mechanical, electrical, and plumbing drawings as well as a geotechnical (or soils)report for each facility to be screened. If an outside engineer is to be used, arrange withan experienced facility engineer to assist and provide access. Provide these data to theequipment inspectors, along with a copy of the MCEER manual.

If the facility has a performance objective of operational (O) or immediate occupancy(IO) for either earthquake event, instruct the inspectors to screen the facility for both life-safety and operational equipment. Otherwise, instruct the inspectors to screen thefacility only for life-safety equipment.

Compile screening records afterwards, along with all drawings. Identify facilities withany equipment system with a failing risk score. Instruct the same engineers to perform adetailed equipment assessment, as described in Section 3.9. If all scores are passing,the equipment may be left as-is.



Example: Equipment Screening

The city office building being screened houses personnel from the Parks and RecreationDepartment and the city Controller’s Office. City policy for the LE (moderateearthquake) event is that this type of facility shall remain Operational (O). Policy for theMPE (large earthquake) event is that the facility remains Life Safe (LS).

The life-safety systems (fire detection and alarm equipment) within the building werescreened and given a score of 3.3. The operational equipment score was 1.2. What doyou do?

Solution:

Determine occupancy. First, the building does not house emergency personnel orvulnerable populations (schoolchildren, elderly) so occupancy in Table 3-8 is “All others.”

Consider life-safety equipment. This system scored 3.3. It must be available in thelarge event, because policy for the large event is that the facility must remain life safe. Apassing score for the large event is 3.0. So the life-safety equipment is adequate andmay be left as-is.

Consider operational equipment. These need not remain available for the large event,since the large-event performance requirement is life safe only. But they must beavailable after the moderate-event, since the facility must remain operational after themoderate event. A passing score is 1.5 for operational equipment in ordinary-occupancyfacilities in the moderate event. The operational equipment here scored 1.2, a failingscore. The Risk Manager should therefore submit the operational equipment at thisfacility for detailed assessment, but allow the life-safety equipment to remain as-is.

3.8.2 Performing the EquipmentScreening

The equipment reliability screeningprocess has four steps: (1) identifycritical equipment systems andcomponents; (2) assess the reliability ofindividual components using scoresheets; (3) assess system reliabilityusing a modified fault tree analysis; and,if necessary, (4) perform riskmanagement to improve systemreliability to tolerable levels.

The following material summarizesthese steps for the inspectors. It iscopied here, with permission, fromMCEER 99-0008, Chapter 2. Asummary is provided for informationpurposes, but the inspector performingthe equipment screening should use thecomplete methodology documented inthe MCEER report.



Step 1: System and Component Identification

What You Will Do: Look at the services your facility needs to provide, whichequipment items and support services are really necessaryto provide that function, and how the various items are tiedtogether.

How You Will Do It: Use checklists to help identify critical systems andcomponents. Sketch logic diagrams to illustrate howsystems are tied together and where you have backupsystem and equipment components. [Sample checklistsare presented in Figures 3-3 and 3-4. Sample logicdiagrams for the entire facility, the life-safety system, and afire detection and alarm sub-system are presented inFigures 3-5, 3-6, and 3-7, respectively.]

What This Does For You: Identifies possible “weak links” in your system andultimately helps to ensure fixes are limited to the mostimportant items.

A facility may have specific functionalityrequirements during or after anearthquake, as specified by federal lawor federal, state, or local regulators. Forexample, hospital performancerequirements for critical care may bespecified in a state-issued license; dataprocessing requirements for banks maybe specified in federal law. In addition,a facility owner may determine that afunction is essential if it is deemedfinancially important for continuedoperation or business recovery.

A critical system is one that is requiredto provide either (1) the essential facilityfunction, as defined above, or (2) life-safety protection as required by otherlaws or regulations. A component of a

critical system could be either aparticular equipment item, a portion of asystem such as piping or ducting, or ahuman action that is required to providefunction of the critical system.

The handbook describes how criticalsystems and critical components can beidentified for a facility. A method isprovided for systematically reviewingimportant systems and the impact oftheir failure on each other. A means isprovided to incorporate specialconsiderations, such as emergencyplans, personnel actions, and knownmaintenance problems.



Step 2: Assessment of Individual Components

What You Will Do: Assign “scores” to individual items indicating reliability tocontinue functioning after an earthquake. A higher scoremeans more reliability.

How You Will Do It: Do a mostly visual review of each component. Use datasheets in Handbook Appendix B to calculate scores. [Asample data sheet is presented in Figure 3-8.] You willreview for all items on the data sheets, assigning scoresapplying rules in the Handbook.

What This Does For You: Helps identify weaknesses in individual equipment items.

The handbook presents a method forrapidly evaluating individual equipmentcomponents and incorporating thoseevaluations into a system evaluation.That method uses assessmenttechniques based on historicalearthquake performance of similarequipment items. Assessments aremade of specific items that have beenknown to be causes of damage in pastearthquakes, or known to be seismicallyvulnerable for other reasons.

Score sheets are provided for individualcomponents, and a method forassigning scores is presented, based onthe design and installation of thecomponent, the location within abuilding and geographically, and otherfactors. Higher scores indicate higherseismic reliability.



Step 3: Assessment of System Reliability

What You Will Do: Assign “scores” to systems and the entire facility indicatingreliability to continue functioning after an earthquake. Ahigher score means more reliability.

How You Will Do It: Use the score from Step 2 with the graphical description ofthe system from Step 1. A set of simple rules to calculatethe score is provided.

What This Does For You: Provides the information you need to make decisions onwhat changes will increase reliability.

This handbook provides a method forrapidly, but systematically evaluating thereliability of critical systems in anearthquake. A system scoring system isprovided to quantify the relativereliability of systems and components.This method can be used by anindividual to identify and prioritizevulnerabilities on a system and facilitybasis.

For each of the major systemsidentified, a system evaluation shouldbe performed. The methodologydescribed in this handbook makes useof the system and componentinformation developed for each systemand the scores for individualcomponents.



Step 4: Risk Management

What You Will Do: Make decisions about actual system modifications, moredetailed analyses, or other steps to take (e.g., emergencyplans) to increase the reliability of your facility operatingfollowing an earthquake.

How You Will Do It: Use the results from Steps 1, 2, and 3. Review howscores may change if certain steps are taken.

What This Does For You: This is the reason for doing the entire assessment: tomake sure that money spent for risk reduction is being putto its best use. This gives you a basis for deciding onvarious options, such as structural modifications, systemchanges, operational or procedural changes, or otherreasonable ways of reducing risk.

The results of the screening provide abasis for making risk managementdecisions. The review of criticalelectrical and mechanical systems andtheir components provides theinformation necessary to create aspecific plan for improving a facility’spost-earthquake functionality.

The component and system evaluationsdescribed in this recommended practiceare part of a screening assessment. Ithighlights important systemcomponents, their interactions, and their

impact on system function. It is not theonly indicator of where upgrades orrepairs should be made, but it providesa consistent method for identifyingobvious vulnerabilities and prioritizingrisk management implementation.

Mitigation is not limited to physicalrepairs to equipment or systems, butcan be achieved through upgrades,analyses, and emergency responseprocedures. All mitigation efforts asdefined in this handbook are intended toimprove overall system reliability.



Critical Systems Identification List (Extract)

System / Sub-SystemLife

Safety BusinessOperations

NotCritical

NotApplicable

Fire Response:

Requirements of system: __________________________________________________________________________________________________________________________________________________________________________________________Sub-Systems:Detection and alarmSuppressionAir duct fire and smoke barriersSmoke purgeOther:___________________________________________________________________

Gas Shutoff:

Requirements of system: __________________________________________________________________________________________________________________________________________________________________________________________Sub-Systems:Other:___________________________________________________________________

Elevator Safety:

Requirements of system: __________________________________________________________________________________________________________________________________________________________________________________________Sub-Systems:Detection/controlOther:_______________________________________________________________________________________________________

Building/Evacuation Egress:

Requirements of system: __________________________________________________________________________________________________________________________________________________________________________________________Sub-Systems:Alarm/indicationAvailable routesOther:___________________________________________________________________

Figure 3-3: Extract of MCEER 99-0008 Critical Systems Identification Checklist



Critical System Component ID Worksheet (Extract)

SYSTEM: FIRE RESPONSE

Description:

SUB-SYSTEM: Detection And AlarmCriticality(circle one)

RedundantComponent

Support SystemRequired

E-essentialR-redundantN-non-essential

List redundant itemnumber

List function(i.e., power, cooling

water, etc.)A. Detection

A.1 Area/Spot Smoke Detectors E R NA.2 Line Smoke Detectors E R NA.3 HVAC/Plenum Smoke Detectors E R NA.4 Heat Detectors E R NA.5 Sprinkler Flow Sensors E R NA.6 Pull Stations E R NA.7 Other (define) E R N

B. AlarmsB.1 Bell/Siren Alarms E R NB.2 Speakers E R NB.3 Strobe Lights E R NB.4 Remote Alarm Monitors (specify) E R NB.5 Other (define) E R N

C. Detection/Alarm InterfaceC.1 Computer System E R NC.2 Fire Communication Center E R NC.3 Alarm Panel(s) E R NC.4 Cabling/Conduit E R NC.5 Other (define) E R N

D. General ItemsD.1 Is operator intervention required for operation of any of the above equipment? Y N

If yes, is the area expected to be accessible?

(Note: if the area is not accessible, equipment requiring manual operation should not be credited.)

D.2 Based on experience, has any of the identified equipment required an aboveaverage amount of maintenance or been inoperable or degraded for a significantamount of time due to failures? Y NIf yes, explain:

(Note: if the equipment is highly unreliable, it should not be credited except as a possible redundancy.)

Figure 3-4: Extract of MCEER 99-0008 Critical System Component ID Worksheet



KEY

SYMBOL NAME MEANING

AND GATE

OR GATE

Component above gate functionsif all components below function

Component above gate functionsif any component below functions

FacilityName

Life SafetyFunctions

BusinessOperation Functions

FunctionA

FunctionB

TelecommunicationsEquipment

Figure 3-5: Facility Logic Model

Life-SafetySystems

FireResponse

GasShut-off

ElevatorStopping System

StairwayEmergency Lighting

Fire Detectionand Alarm

Active FireSuppression Systems

Air Duct Fire andSmoke Dampers

Figure 3-6: Life-safety System Logic Model

Life-safetySystems



HVAC DuctSmoke Detectors

KEY

SYMBOL NAME MEANING

AND GATE

OR GATE




Fire AlarmPanel

FireDetection

Fire AlarmIndicating Device

SmokeDetection

ESSENTIAL

PullStations

HeatDetectors

SprinklerFlow Sensors

REDUNDANT

Spot SmokeDetectors

LineSmoke Detectors

Figure 3-7: Fire Detection and Alarm Sub-system Logic Model



Batteries and RacksComponent ID:

Location:

Comments:

Earthquake Load Level (circle one letter)

Location in Building

NEHRP UBCBottomThird

MiddleThird

TopThird

Z 1-3 1 A A A

O 4-5 2 A B C

N 6 3 B C D

E 7 4 C D E

Scores and Modifiers - Batteries and Racks(circle a Basic Score and all PMFs that apply - use the column indicated by the Earthquake Load Level above)

Description A B C D E

Basic Score à 5.3 4.4 3.9 3.5 3.2

1. No anchorage 1.5 1.5 1.5 1.5 1.52. “Poor” anchorage 1.3 1.3 1.3 1.3 1.3

P 3. No battery spacers 0.7 0.7 0.7 0.7 0.7M 4. No cross-bracing 0.9 0.9 0.9 0.9 0.9F 5. No battery restraints 2.0 2.0 2.0 2.0 2.0

6. Interaction concerns 0.5 0.5 0.5 0.5 0.57. Other:

Final Score = Basic Score – highest applicable PMF

Note that this is a screening process and is inherently conservative. If there is any question about an item, note it and select theappropriate PMF. See the following page for PMF guidelines.

Figure 3-8: Sample MCEER 99-0008 Component Scoresheet: Batteries and Racks



Explanation of Performance Modification Factors (PMFs)

1, 2 If there are no anchor bolts at the base of the frame, select PMF 1. If the anchors appear to be undersized, ifthere are not anchors for every frame of the rack, or if the anchorage appears to be damaged, select PMF 2.

3 Look for stiff spacers, such as Styrofoam, between the batteries that fit snugly to prevent battery pounding. Ifthere are none, select PMF 3.

4 The rack should provide restraints to assure that the batteries will not fall off. The photo above shows a rack withno restraints, while the photo to the left shows a rack with restraints. Select PMF 4 if adequate restraint is notprovided.

5 Racks with long rows of batteries need to be braced longitudinally as shown in the photo to the left. Select PMF 5if no cross-bracing is present.

6 If large items such as non-structural walls could fall and impact the battery racks, select PMF 6.

7 For other conditions that the reviewer believes could inhibit battery function following an earthquake (e.g., ahistory of problems with this piece of equipment), assign a PMF value relative to the existing PMFs in the table.Add a descriptive statement for the concern.

1, 2

1, 2

5

6

4

34

Figure 3-8 (continued): Sample MCEER 99-0008 Component Scoresheet: Batteries and Racks



3.9 Equipment Assessment

Facilities with equipment systems thatreceived a failing MCEER risk scorerepresent potential operational failure orrisks to life-safety. All such equipmentsystems should be examined toestimate the failure probabilities andlosses under the MPE and LE events,as well as to identify mitigationalternatives.

The equipment inspector (EI) shouldpropose various retrofit alternatives,such as those detailed in MCEER 99-0008, and reevaluate the probability ofsystem failure under the variousmitigation alternatives. The inspectorshould estimate the cost to implementthe mitigation measures, as well as anyassociated downtime.

The precise data required are listed inWorksheet 5. The equipment inspectorshould only fill out rows labeled “By EI”in the right-hand column. Other rowswill be filled in by the Asset Managerand Financial Manager as describedbelow.

It is important for the equipmentinspector to keep in mind that theanalysis needs only developapproximate estimates and schematicretrofit options. The inspector need notprepare detailed design of seismicretrofits. These steps will be undertakenonly if the Decision-Maker chooses toperform a retrofit.

The level of effort to provideapproximate analyses will vary, but mayrange from $2,500 to $20,000 perfacility, depending on complexity.

Risk Manager: What You Should Do

Ask the equipment inspector (EI) to examine equipment systemsthat failed the screening score. The EI should estimate the cost torepair the damaged equipment as well as the duration of loss ofuse, assuming failure occurs. The EI should also propose one ormore mitigation options that reduce the system risk scores toacceptable levels depending on the earthquake event considered.The costs to implement these options should also be provided.The EI’s estimates should be recorded in Worksheet 5. Use oneWorksheet 5 form per facility per system examined.

Compile Worksheet 5 forms from each equipment systemreviewed. Pass life-safety equipment assessment forms to thelife-safety operational expert (LSOE) or Asset Manager for loss-of-use assessment. Pass BI equipment assessment forms to theFinancial Manager. Loss-of-use assessments are describedfurther in Section 3-10.



Worksheet 5 – Equipment Assessment

Equipment System: Type (circle one): Damage / Life-safety / BI

Inspector: Date:

MitigationOption

Risk ScoreS

BestEstimate

HighEstimate

As-is (do nothing): - - By EI

Option 1: By EI

Option 2: By EI

Loss-of-use Costs for Failure (from Worksheet 6)

UGF (1 hr) UGF (1 week) UGF (1 day) UGF (1 month)

Case Loss Items MPE (500-year) LE (100-year)

As-isRepair Cost, R (Best $ Estimate): By EI

Duration Units (circle one): hour day week month hour day week month By EI

Loss-of-Use Duration, LUD: By EI

Loss-of-Use Cost (Given Failure), UGF:

Loss-of-Use Cost, U = 10-S⋅UGF:

Opt.1

Repair Cost, R (Best $ Estimate): By EI





Opt.2 Repair Cost, R (Best $ Estimate): By EI





Maximum repair cost Rmax (from Risk Manager or Asset Manager): $



3.10 Loss-of-Use Assessment

Operational failure can result in financiallosses; in the insurance industry, this istermed Business Interruption, or BI.This section addresses the estimation offinancial operational risk, or BI.

3.10.1 Financial OperationalAssessment

Complete one Worksheet 6 for eachfacility. This worksheet should be filledout by the Financial Manager. TheFinancial Manager must estimate thecost associated with losing the use ofeach facility for various periods of time.

These time periods, or “durations,”should be estimated by the engineerswho perform the building and equipmentassessments and can be obtained fromWorksheets 4 and 5. Rather thanproviding these individual estimates, itmay be easier for the Financial Managerto estimate losses for operationalinterruptions of one hour, one day, oneweek, and one month. The RiskManager can then develop appropriateestimates for the actual period ofinterruption estimated by the engineersusing this data. Worksheet 6 provides aline for tabulating these estimates.

The costs associated with loss of usewill vary by the type of facility underconsideration. A school, for example,will have loss-of-use costs associatedwith renting temporary facilities andmoving computers and administrativesupplies to the temporary facilities andback again. Total loss should be thesum of all potential sources of financialloss. Typical financial losses include thefollowing:

U1 = Difference in rent betweendamaged facility andtemporary (or new) facility

U2 = Moving expenses to and fromtemporary facilities

U3 = Lost productivity during moves

U4 = Lost profit associated withoutsourcing services ormanufacturing previously donein-house

U5 = Lost profit from temporary lossof market share

U6 = Extra costs to regain marketshare (e.g., extra advertisingand overtime costs)

In addition to the losses associated witharbitrary interruption periods, theFinancial Manager should alsodetermine the maximum loss-of-usecost, Umax. This is the cost associatedwith permanent loss of the facility.

Complete Worksheet 6 for eachfacility with performance goals of Oor IO for either the MPE or LE events.Transfer the totals from each Worksheet6 to the corresponding Worksheet 5.For each loss-of-use duration inWorksheet 5, note the total average losscosts resulting from that duration, in thefield marked Loss-of-Use Cost (GivenFailure), UGF. For each retrofit option,calculate the loss-of-use cost for theMPE and for the LE events.

Expected loss-of-use cost = 10-S⋅UGF

Where S is the risk score obtained fromthe equipment or building evaluationmethodologies (i.e., FEMA-154 or theMCEER 99-0008), see the Example:Loss-of-Use Calculation sidebar.



Example: Loss-of-Use Calculation

From Worksheet 6, the sum of the dollar costs resulting from the facility being out ofoperation for a week is found to be UGF = $100,000 (e.g., from lost production).

From the MCEER methodology, suppose that only one equipment item is found to bevulnerable to earthquake damage – the main electrical transformer for the plant, which isunbolted to its foundation pad (the As-Is condition). Due to the lack of anchorage, it isdetermined that this transformer will slide and be damaged, with a score S=1.5. Under alarge earthquake, it is determined that a replacement transformer will require one weekto be located and installed. Therefore, the LUD = 1 week. Repair Cost, R, for thetransformer (i.e., replacement) = $20,000. Therefore, the Loss-of-Use Cost, U, is:

U = 10-1.5 x ($100,000 + $20,000 = $120,000) = $3,795.

Mitigation Option 1 is to have maintenance personnel shut down the transformer on aSaturday (overtime is involved) and bolt the transformer down. Materials are a negligiblecost item, and the labor for two mechanics to work one-day overtime is $480 per person,or a total of about $1,000.

Mitigation Option 2 is to insure for the damage and/or BI. The insurance company offersan insurance policy for BI due to loss-of-power from any cause (including earthquake),with a one-day deductible and a premium for this plant of $2,000 per year. If thepostulated earthquake occurs, the losses due to the transformer damage wouldtherefore be $20,000 replacement + $20,000 (the one-day deductible, taken as 20% ofthe week’s lost production), or $40,000. Given the same time-discount as above (i.e.,3.795/120 = 0.0316), the expected value of the uninsured loss is $1,265.

The plant risk manager discusses electrical utility response in recent earthquakes, withhis electric utility account executive, and is informed that only parts of Los Angeles orSan Francisco lost power for more than a day, in recent earthquakes such as the 1994Northridge or 1989 Loma Prieta events.

Based on a comparison of the expected costs:

As-is: $3,795 weighted average of no earthquake and earthquake occurs$0 if no earthquake$120,000 loss if an earthquake

Option 1: $1,000, with no risk due to earthquake

Option 2: $2,000 per year for insurance + $1,265 weighted average of EQ / no EQ$40,000 loss if an earthquake(but also covered for loss of power due to other reasons than earthquake)

The risk manager decides for Option 1.



Worksheet 6 – Loss-of-Use by Facility

Expert(s): Date:

Facility:

Financial Manager: Provide best estimates of dollar costs resulting from this facility being out ofoperation for various durations. Assume the building is safe to enter to remove documents andequipment, but elevators, electric power, water, etc., are unavailable. Total UGF = sum of column

$ Units (circle one) = dollars / hundreds / thousands / millions

Loss-of-Use Duration

Cost Item 1 hour 1 day 1 week 1 month

Extra Rent: 0 0

Movers: 0 0

Production Losses:

Outsourcing Costs: 0

Loss of Market Share: 0 0

Extra Marketing: 0 0

Overtime: 0 0

Other:

Total UGF



3.11 Alternatives

Mitigation Alternatives were summarizedin Chapter 2 and are discussed in detailin Appendix D. They can be broadlycategorized as:

§ Buildings can be strengthened withthe addition of braced frames orshear walls. Additionally, buildingseismic vulnerability can beenhanced by mass-reduction, that is,reducing weight by removing a fewtop floors, replacing a heavy roofslab with light-weight concrete,moving heavy equipment from theroof to the basement, or byintroducing an atrium into a fewupper floors. Techniques attractivewhen continued operation isrequired following a largeearthquake include base-isolation(which introduces compliantbearings beneath the buildingcolumns, allowing the building todisplace without damage), andenergy dissipation systems (whichfunction akin to automobile shockabsorbers in dissipating the energyimparted to a building during a largeearthquake).

§ Equipment can also bestrengthened or braced in a varietyof ways, which in many cases is verycost-effective. Often, this is simply amatter of bolting the equipment to afloor or wall.

§ Emergency planning is arecommended practice, even whenbuildings and equipment have beenmitigated, since unforeseencircumstances can always arise, forwhich it is wise to be prepared.

§ Insurance purchase is also arecommended practice. However,bear in mind that insurance is only a

financial risk transfer mechanism; itdoes not protect lives. Significantrisk is often most cost-effectivelymitigated by strengthening orotherwise improving structures andequipment against earthquakeeffects. Employment of insurance isfor the residual risk – the damageaccepted by the Decision-Makerafter going through the processoutlined in this chapter.

3.12 Baseline RiskThe previous sections have presentedmethods for screening and focusing onthe greatest contributors to earthquakerisk. Several points are worth notinghere:

§ The total earthquake risk for acommunity or organization is theaggregate of the constituentelements. That is, the total liveswhich may be lost isapproximately equal to thesummation of the lives lost in allthe buildings, in all the fires, andin all the hazardous materialsspills. Similarly, the totalfinancial impact of an earthquakewill be the summation of the totalrepair costs of all the facilities,plus the total value of disruptedeconomic activity, due to allcauses traceable to theearthquake. Note that "double-counting" should not occur; theexpected loss due to shakingshould not be added to theexpected loss due to firefollowing earthquake, for thesame facility.2

2 In the insurance industry, this is known as‘burning the rubble.’



§ There is uncertainty associatedwith each estimate of lives lost,cost of repair, or other estimatesof loss. This uncertainty shouldbe taken into account indetermining the total losses dueto an earthquake. The rigorousmathematical procedures forneeded to do this are beyond thescope of this toolkit, and wesimply note that they exist andshould be employed. The RiskManager and Decision-Makershould be aware that uncertaintyexists and there are methods fordealing with it (e.g., Benjaminand Cornell, 1970; Ang andTang, 1975). They shouldrequire a proper treatment andaccounting of uncertainty, by thespecialists involved.

§ Losses can be estimated oneither a scenario, or annualized,basis. This is an important point,and the distinction should beclearly understood:

§ Scenario losses are those thataccrue due to a specific event,such as a magnitude 7earthquake on the San Andreasfault. Scenario losses are validfor a given event only, and areindependent of the probability ofthat event.

§ Annualized accrue on aprobabilistic basis from allpossible events that can occur,taking into account theprobability for each of theseevents in a given year.Annualized losses are expressedas the average losses expectedper year, taken over a period ofmany years. In insurance terms,annualized losses are the pure

premium, that is, they are theapproximate equivalent of theinsurance premium, before it isloaded with insurance companyoverhead, profit, taxes and otherexpenses. For an organizationthat elects to self-insure, theannualized loss is the amount ofmoney that should be set aside,on an annual basis, to coverlosses that will eventually occur.

§ In decision-making, bothscenario and annualized lossesshould be considered. TheDecision-Maker should graspwhat losses may result from aspecific large earthquake event(i.e., the scenario loss), and theloss cost per year ofearthquakes (i.e., the annualizedloss). The Decision-Maker cancompare scenario losses againstthe maximum tolerable loss, andcan compare annualized lossesagainst other losses, such as thenumber of persons killed inautomobile accidents, or theannual expected losses due tofire.

§ The uncertainty associated withall these losses should be takeninto account. Not only shouldthe mean (i.e., ‘average’) ormedian (i.e., 50th percentile)losses be reported andconsidered, but so also shouldupper fractiles, such as the 90thpercentile loss (that is, the losswhich has a 10% probability ofbeing exceeded). Thisconsideration of upper fractilescan get very complex, anddifficult to understand for theDecision-Maker and the layperson. Examples include:



1. 90th percentile scenario loss--equal to the loss for thescenario event which will notbe exceeded with 10%probability (can be thought ofas the loss which will not beexceeded for 9 out of 10repetitions of the samescenario event, all else beingequal).

2. 90th percentile annualizedloss--equal to the annualizedloss which will not beexceeded with 10%probability (can be thought ofas the loss which will not beexceeded for 9 out of 10years, all else being equal).

3. 90th percentile loss in 50years--equal to the losswhich will not be exceededwith 10% probability in 50years (can be thought of asthe loss expected to occurabout once in 500 years, allelse being equal).3

3.13 SummaryThis chapter has summarizedmethodologies for assessing earthquakerisk and alternatives.

§ Identify the Assets at Risk –from a Decision-Maker’sviewpoint, this is property andlives for which the Decision-Maker is responsible. Section 3-2 tabulated a broad spectrum of

3 If a poisson model is assumed, the annualprobability of exceedance for this case is 1/475per annum, and this is more accuratelyreferred to as the ‘475’ year loss, rather thanthe ‘500’ year loss, to which it is sometimesrounded for lay persons.

assets at risk, for both theprivate and public sectors.

§ Determine Acceptable Risk –this consists of making someinitial policy and strategicdecisions concerning therequired level of seismicreliability for various classes offacilities, and determiningwhether the programs formitigation are going to bemandated or voluntary.

§ Data Collection – once theassets at risk have beenidentified, and certain basicdecisions made, collect data onall the facilities. This is a basicstep in earthquake riskmanagement, and it can be acostly effort. Mitigating the datacollection cost is the recognitionthat the data, once collected andif maintained, can form the basisfor efficient facility management.

§ Building and EquipmentScreening – to examineeverything in detail is expensiveand not necessary. Therefore,screening methods have beendeveloped for buildings andequipment which can beemployed to quickly focus on thegreatest risks.

§ Building Assessment – FEMA-310 provides a standardmethodology for examiningthose buildings that pose asignificant risk.

§ Loss-of-Use Assessment –Loss of use is an importantelement of earthquake risk,leading to loss of revenues andpotentially even loss of life, as in



the case of a hospital renderedinoperable. Therefore, it is vitalto assess loss of use due tostructural and equipmentdeficiencies. There is nostandardized methodology forthis, but an approach has beenprovided in this chapter. Sinceloss of use is so critical to theoverall operations of anorganization or community, thisassessment should beperformed by a team comprisedof seismic experts and personsfamiliar with the specificoperations of the organization orcommunity.

Following these steps should provide agood assessment of the risk to anorganization or community, including theconstituent elements of the risk. Thischapter has not dwelt on the details ofthe many possible mitigationalternatives, since they are verynumerous and really best identified bytechnical specialists. Nevertheless, asthe constituents of risk are identified andassessed, many mitigation alternativeswill become readily apparent. Choosingamong them is the subject of the nextchapter.


4. Deciding What To Do

4.1 Introduction

In the previous section, we presentedmethods for determining the baseline risk;the risk under existing or as-is conditions.The decision about whether that risk isacceptable should be based on twofundamental criteria:

§ What loss would be tolerable, shouldit occur?, and

§ How easy (i.e., at what cost) would itbe to reduce the loss?

In general, significant risk of structuralcollapse1 is not tolerable in California today.In that sense, some aspects of the decision-making may be easy: if the baseline riskassessment indicates likely collapse orother significant risk to life-safety, then thatrisk must be reduced. The problem wediscuss here is how to determine anappropriate program of mitigation beyondprotection of life safety. This chapterprovides an overview of the many methodsavailable for making that decision2.

1 Or other risks to life-safety, such as major releasesof hazardous materials in an earthquake.

2 See Dames & Moore, 1994 or AIChE, 1995 forexcellent discussions of the available methods.

4.1.1 Maximization (benefit-cost) orMinimization (total cost)

The most common decision method ismaximization, which forms the core of thewell-known benefit-cost method. With thismethod, the Decision-Maker quantifies thenet benefits of each alternative method (i.e.,benefit minus cost associated with thealternative, where the benefit is the reducedloss), and selects that alternative that hasthe maximum net benefit.

The corollary of this is the minimization ofthe total cost, where the total cost is theexpected loss plus the cost of mitigation.This is shown in Figure 4-1, where Point Ais the least total cost. (Note that Point Adoes not necessarily correspond to Point B,the crossing of the expected loss curve withthe mitigation cost curve.)

In order to apply these rules, eachalternative must be associated with a singlevalue that represents benefits. Whenuncertainty is ignored, applying themaximization rule is straightforward andexpresses the Decision-Maker’s simpledesire for more of a good thing.


Secondary Interest:Decision-Makers

DECIDING WHAT TO DO


Mitigation(increasing effectiveness)

Cos

t

CM =Cost of mitigation

CL = Expected loss

Total Cost = CL + CM

A

Least total costB

C (satisficed)

Figure 4-1: Typical Cost of Mitigation Curve

When considering uncertainty, the usualprocedure for applying the maximizationrule is to determine the likelihood of thepossible outcomes of an alternative, andcompute an expected value for eachalternative. The expected value is theweighted sum of values for each possibleoutcome, with the weights determined bythe likelihood (probability) of theseoutcomes.

In order to apply these rules, eachalternative must be associated with a singlevalue that represents benefits. Whenuncertainty is ignored, applying themaximization rule is straightforward andexpresses the Decision-Maker’s simpledesire for more of a good thing. Whenconsidering uncertainty, the usualprocedure for applying the maximizationrule is to determine the likelihood of thepossible outcomes of an alternative, andcompute an expected value for eachalternative. The expected value is theweighted sum of values for each possible

outcome, with the weights determined bythe likelihood (probability) of theseoutcomes.

4.1.2 Maximin and MaximaxAnother common decision rule is themaximin rule ("maximize the minimum"). Itcan be applied in situations where multipleoutcomes are possible, but with likelihoodsthat are not known. Using this rule, theDecision-Maker takes each decision andassociates it with the value resulting fromthe worst possible outcome under thatalternative. The alternative that provides forthe highest value under its worst possibleoutcome is selected. The maximin rule istruly a pessimist's rule, for it ensures thatthe Decision-Maker avoids choosingalternatives that could lead to the worstpossible outcomes, even if thesealternatives could yield attractive outcomesas well.

DECIDING WHAT TO DO


The opposite approach is the maximax rule("maximize the maximum"). Using this rule,the Decision-Maker selects the alternativewhose return under the most favorablecircumstances is the greatest. In this case,the Decision-Maker is "going for broke" byignoring all possible downsides to eachalternative, and focusing only on thepossible benefits (AIChE, 1995).

4.1.3 Minimum RegretAfter a loss, a Decision-Maker may becriticized by others for having selected aninappropriate alternative on the grounds thata different one would have led to a betteroutcome under the circumstances. Forexample, a plant manager chooses to delayseismic retrofit due to its high cost and ajudgment that there is an extremely smallchance of a major earthquake in the nextfive years. An earthquake occurs soon afterthis decision, and causes a 30-dayinterruption of operations. Though thedecision was in fact a wise one given thedecision maker's understanding of the costsand risks, the plant manager is criticized fornot choosing the alternative that would haveyielded the best outcome. The regret ruleminimizes the risk to the Decision-Maker ofbeing confronted in hindsight. For eachpossible future scenario, the Decision-Maker assesses the difference in valuebetween each alternative and the bestalternative if the scenario were to occur.This difference is referred to as the "regret."Regret represents the "cost" of not havingperfect foresight and selecting the bestdecision. This rule applies a minimax rule,selecting the decision in which themaximum regret is the least.

4.1.4 Minimum UncertaintyMost Decision-Makers are risk-averse: theyprefer to avoid choosing alternatives forwhich the outcomes are uncertain. Whenoutcomes are presented to a Decision-Maker in terms of the probability for each ofthe possible resultant values, a decision rulecalled minimum uncertainty can beemployed. Minimum uncertainty may alsobe referred to as minimum risk, where riskrefers not to physical or financial risks, butto aversion to uncertainty, as describedabove. With outcomes quantified by aprobability distribution, extremely risk-averse Decision-Makers may wish to selectan alternative that gives them the mostcertainty about future rewards by minimizingthe variance on possible outcomes.Alternatively, some Decision-Makerschoose to account only for those outcomesassociated with the most likely future event.A minimum uncertainty rule can lead theDecision-Maker to reject attractive butuncertain alternatives, and choose a saferalternative with smaller potential rewards.

4.1.5 SatisficingNot all decision rules yield a single bestalternative. Many organizations areconcerned with meeting many, sometimescontradictory, goals. Satisficing is adecision rule that is used to find one ormore alternatives that can satisfy all (ormost) of the organization's goals. Whenusing a satisficing decision rule, a minimumlevel of achievement on each of severalgoals is set. For example, a safety goalmay be to "reduce the risk of death below“10-7 per year" and "spend less than$100,000." All alternatives that meet thesegoals would be considered satisfactory.

DECIDING WHAT TO DO


An example of satisficing is shown in Figure4-1, at Point C, which is not the least cost,but where the marginal cost of mitigation isa set ratio to the expected loss. Since manytotal cost curves are rather "flat," a near-minimum total cost can be achieved at acost of mitigation far below the cost ofmitigation corresponding to the trueminimum Point A.

Any of the above methods can be employedin decision-making. In the next sections, weemploy and illustrate an approach, whichcombines elements of decision analysis andbenefit-cost analysis.

4.2 Decision Analysis

Benefit-cost analysis is one method fordeciding among alternative mitigationmeasures. This approach has beenadapted from decision analysis (DA). DArepresents a set of convenient and powerfulprinciples to help make difficult decisions inan orderly, rational manner. Oil companiesuse DA to decide whether to bid on adevelopment field and how much to bid;high-tech firms use it when deciding whichresearch projects to fund. DA can be usedto help make life-and-death medicaldecisions. The DA process, adapted here,is generally best used when:

1. an organization faces a high-valuedecision,

2. the decision has many uncertainties,and

3. no single individual or small group in theorganization has all the expertise andinformation necessary to make thedecision. A related criterion is that theorganization is complex and buy-in mustbe obtained from a diverse group beforea decision can be carried out effectively.

For the application to earthquake riskmitigation, we have divided the approachinto a series of 13 sequential tasks, shownin Table 4-1. Also shown in the table is afinal task, development of post-earthquakeresponse plans. This is not specifically apart of the decision method, but is a veryimportant earthquake risk managementelement; it should be included in theprocess.

The “done by” column of Table 4-1 isimportant for maximizing decision quality,and for obtaining buy-in from stakeholdersin the decision. The Risk Manager mustinvolve all-important stakeholders inidentifying as complete and creative a set ofalternatives as possible, and in gatheringthe best information available. As describedbelow, the Financial Manager will be calledupon to estimate financial consequences offacility outage. Legal counsel may be askedearly on to identify legal obligations thatcould limit retrofit alternatives. Otherstakeholders should also be invited toparticipate in the process. This will improvethe quality of the information upon which thedecision is based and help to ensure thatthe decision is accepted by the enterprise.

DECIDING WHAT TO DO


Table 4-1

RETROFIT DECISION PROCESS

Task ToolkitSection Done by Aided by

1. Define Acceptable Risk 3.4 Decision-Maker Risk Manager

2. List Facilities 3.4 Risk Manager Various

3. Task-out Screenings 3.4 Risk Manager Various

4. Building Screening 3.6 Asset Manager Structural engineer

5. Building Assessment 3.7 Structural engineer Asset Manager

6. Equipment Screening 3.8 Asset Manager Structural engineer

7. Equipment Assessment 3.9 Mechanical engineer Asset Manager

8. Loss-of-Use Assessment 3.10 Risk Manager

Structural engineerMechanical engineerAsset ManagerFinancial Manager

9. Benefit-Cost Analysis 4.3 Risk Manager Financial Manager

10. Recommend retrofitstrategy 4.4 Risk Manager Structural engineer

11. Decide retrofit strategy 4.4 Decision-Maker Risk manager

12. Perform and maintainretrofit 5.3 Asset Manager Structural engineer

13. Enact emergency plans 5.6 Risk manager Asset Manager

DECIDING WHAT TO DO


4.3 Benefit-Cost Analysis

4.3.1 IntroductionRetrofit options should be screened basedon the performance goals that have beenselected; any alternative that does notsatisfy the desired performance goal shouldbe rejected. For example, the Decision-Maker has set a policy for Facility A that itshall remain life-safe in the event of anMPE. The Asset Manager performedbuilding screening using FEMA-154 andcalculated a score for Facility A of S=0.5.Therefore, a structural engineer wasretained to assess the building in greaterdetail.

The engineer confirmed that the buildingcould not reliably protect life safety for anMPE event. Three possible retrofit options(A, B, and C) were proposed. Options Band C were judged capable of providing forlife safety if the facility experienced MPEground shaking, while option A still left anon-negligible chance of collapse. The do-nothing option and option A should both berejected for failing to meet the life-safetyperformance goal selected by the Decision-Maker. Options B and C are bothacceptable and should be examined todetermine which one is most cost-effective.

The benefit-cost analysis method consistsof the following steps:

1. Each facility is evaluated to determineits probable earthquake performance(ability to protect life-safety, likelydamage repair costs, and potentialduration of loss-of-use). Chapter 3provided guidelines for this aspect of theprocess.

2. Facilities that represent an unacceptablerisk to life safety are targeted for retrofit(or other alternatives such asreplacement) which reduce the life-safety risk to an acceptable level.

3. Facilities that pose an acceptable life-safety risk but have significant potentialto result in financial loss due to damage,loss of occupancy or function areevaluated to identify alternative retrofit(and other mitigation measures) whichcan reduce the financial risk toacceptable levels:

(a) The implementation cost for eachalternative is estimated andamortized over an appropriateplanning period.

(b) Probable costs resulting fromdamage and loss of use areestimated and converted to anannualized basis, considering allpossible event sizes and theirassociated probabilities. This is thepresent annualized loss (PAL).

(c) Calculation of annualized loss isrepeated, assuming that each of thealternatives is implemented,exclusive of the other alternatives.In each case, the calculated value isthe residual annualized loss (RAL).

(d) The annualized benefit-cost ratio foreach alternative is computed as:

CostRALPAL

BCR−

= (4-1)

(e) A computed benefit-cost ratio of lessthan 1.0 indicates that it costs moreto implement an alternative than theprobable savings in avoided loss.

DECIDING WHAT TO DO


Benefit-cost ratios that exceed 1.0indicate that the probable savingsresulting from future avoided lossesexceed the cost of the mitigation.Alternatives with the largest benefit-cost ratio are the “best” choice.

While a benefit-cost ratio of less than 1.0indicates that the cost of mitigation exceedsthe probable benefits to be obtained, thisshould not, in itself, be interpreted toindicate that mitigation should not beperformed.

Inherent in this method of analysis is anassumption that the earthquake that causesdamage is equally likely to occur in anyyear, and may not actually occur until manyyears in the future. If it is assumed that thedamaging earthquake will actually occur inthe near future, which is a possibility, thenthe benefit of performing the mitigationwould be much more attractive relative tothe cost. Therefore, while benefit-costanalysis is an appropriate method to chooseamong mitigation alternatives, it may not bean appropriate model upon which to base adecision to mitigate.

4.3.2 Screen Out UnacceptableOptions

Any alternative that fails to meet theperformance goals determined inWorksheet 1A should be eliminated.

4.3.3 Estimate Amortized RetrofitCost

First, the appropriate planning period, T,must be determined. The Risk Managershould determine this in consultation withthe Financial Manager.

§ For a private organization: T isusually taken on the order of 5-0years.

§ For a public agency: T may belonger, perhaps on the order of 30-50 years.

In consultation with the Financial Manager,determine the cost of funds, i 3.

For each retrofit option, determine theexpected value of construction cost, C, andthe amortized retrofit cost (i.e., the retrofitcosts per annum), Cpa using the equation:

( )

+−

=

T

pa

i

CiC

11

1

(4-2)

Use the engineer’s best estimate for retrofitcost C (alternatively, an organization maywish to use a weighted average of theengineer’s best estimate, and thecontingency, for conservatism).

4.3.4 Estimate Annualized DamageCosts

For each mitigation alternative (including thecase of no mitigation), determine the

3 This is the cost of retrofit capital. Theoretically, thisis the real interest rate, which is the market interestrate minus the inflation rate [this is because thefunds accrue interest at the market rate, but thecapital and interest are paid back with futureinflated dollars]. In practice, many public andprivate agencies use the market interest rate as thecost of funds (e.g., the U.S. government OMBmandates that the market rate for Treasury bondsbe used) – the effect of this is to require projects tobe more beneficial than their theoretical return.

DECIDING WHAT TO DO


expected annualized value of damagerepairs due to future earthquakes. Inpractice, this is most often determined usingcomputer programs, which analyze thedamage due to all possible earthquakes,and multiply its cost by the probability peryear that each earthquake may occur.

The following procedure may be used as arough approximation of this more rigorousapproach.

(a) determine the annual expected costto repair damage due to the MPE as:

500MPED

where DMPE is the expected cost ofdamage repair if the MPE actuallyoccurs.

(b) determine the annual expected costto repair damage due to the LE as:

100LED

where DLE is the expected cost ofdamage repair if the LE actuallyoccurs.

(c) determine the total annual expectedcost to repair damage due to allpossible future earthquakes as:

[ ]

+≅

5001004 MPELE DD

paDE (4-3)

where E[D pa] is the expectedDamage per annum

This approximation is empirically based,and may be appropriate only for the high

seismicity areas of California. In otherareas, it may not be appropriate, and amore accurate computer program-basedapproach should be used4.

4.3.5 Estimate Annualized Loss-of-UseCosts

For each facility and each retrofit option,determine the expected value of loss of usecosts for the MPE and LE earthquake, usingthe Financial Manager’s best estimates ofloss-of-use cost U, from Section 3.2.

UMPE = best estimate of loss-of-use costfor the large event

ULE = best estimate of loss-of-use costfor the moderate event

Then, calculate E[U pa], the expectedannualized loss of use cost for eachmitigation alternative (as well as thealternative of no mitigation) as:

[ ]

+≅

5001004 MPELE UU

paUE (4-4)

4.3.6 Benefit-Cost AnalysisYou now have all the data required toperform a benefit-cost analysis using theBenefit-Cost Analysis worksheet(Worksheet 7). Next steps:

4 As noted, Equation 4-3 is an empirically basedapproximation. The multiplicative constant 4provided in empirically ranges between 3 and 5, sothat there may be significant uncertainty. Thisapproximation has not been thoroughly peerreviewed and is only the opinion of the authors.

DECIDING WHAT TO DO


§ List the facilities (Column A), retrofitoptions (Column B), performancegoals (Column C, MPE and LEevents), and occupancy class(Column D), grouping mitigationalternatives together for each facility.Remember to include the “nomitigation” alternative in this list.

§ For each facility and each mitigationalternative, enter the expectedretrofit cost (Column E), andamortized retrofit cost per Equation4-2 (Column F), expected LEdamage repair cost (Column G),expected MPE damage repair cost(Column H), expected annualdamage repair cost, E [D pa] perEquation 4-3 (Column I), expectedLE loss of use cost ULE (Column J),expected MPE loss of use cost UMPE

(Column K), and the annualexpected loss of use cost, E[U pa]per Equation 4-4 (Column L).

§ Enter the sum of the values fromColumns I and L in Column M. Thisis the annualized loss cost.

§ Calculate the annualized benefit foreach alternative as (M for nomitigation option) – (M for themitigation alternative), and enter inColumn N.

§ Calculate benefit-to-cost ratio foreach option, that is, as(Column N)/(Column M).

§ For each facility, recommend theoption with the greatest benefit-to-cost ratio.

DECIDING WHAT TO DO


DECIDING WHAT TO DO


4.4 The Retrofit Decision

With the Benefit-Cost Analysis worksheet(Worksheet 7) completed, the Decision-Maker has a clear set of choices, balancingexpected losses with costs of mitigation. Asnoted in Chapter 2, additional informationand analyses may be required at this point.However, eventually enough alternativeswill have been examined to present a clearset of choices, from which a decision can bemade according to the methods outlinedabove.

Once a decision is made, it is typicallysubject to outside review for severalreasons. Not everyone can be involved inthe decision process, and this is a commonsource of objections to seismic mitigationprograms. It is important to recognize thepotential for this and eliminate it, as ittypically leads to fractious and counter-productive defense of the decision after ithas been made.

The best way to eliminate this problem is toidentify all stakeholders in the earthquakemitigation program early, and to keep theminformed of the decision-making processfrom the beginning. Given the opportunityto comment on the process, stakeholdersmay offer valuable insights and suggestionsand, at least, are not deprived of their voicein the process.

4.5 Olive Grove High SchoolExample

The following example illustrates thedecision process. Olive Grove is a fictitiousschool campus with several buildings.

STEP 1: POLICY GOALS AND ASSETSAT RISK

The fictional city of Olive Grove lies inCentral California. In a resolution, the OliveGrove High School Board of Trusteesinstructs the superintendent to develop aseismic risk management plan, with thesegoals:

1. Safeguard lives of school studentsand employees;

2. Control damage to high schoolproperty if the benefits justify thecosts.

The school includes four buildings:

1. Gymnasium (14,000 square feet;built 1925; unreinforced masonry)

2. Science Building (15,000 squarefeet; built 1950s; reinforced concreteframe construction)

3. Foundation Building (6,000 squarefeet; original school house built in1911 and now used foradministrative offices; wood frame)

4. Liberal Arts Building (25,500 squarefeet; built 1985; braced steel frameconstruction)

All four buildings are regularly occupiedduring school hours, with a total student,staff, and faculty population of 250.

DECIDING WHAT TO DO


STEP 2: LIFE-SAFETY EVALUATIONAND MITIGATION

The school district contracts with “I.M. AbelStructural Engineers" to perform a seismicevaluation of the campus. After completionof a Tier-2 evaluation using the FEMA 310methodology, the engineers’ reportindicates that the gymnasium and sciencebuilding pose collapse hazards for the MPEearthquake. The administration and liberalarts buildings have some seismic problems,but are unlikely to collapse or pose aserious life-safety threat. The districtdirects Abel Engineers to respond to thelife-safety threat posed by the gym andscience buildings. The engineerrecommends the gym and science buildingbe assessed for retrofit according to theCalifornia Code of Building Conservation(California Building Standards Commission,1998), with the following results:

Gymnasium: The gymnasium is anunreinforced masonry building with a woodbowstring truss. The vulnerability that canlead to collapse is an inadequateconnection of the trusses to the pilasterssupporting them. In the design basisearthquake, the trusses will pull off thepilasters, dropping the trusses and roof intothe gym area. Two alternatives arepossible:

(i) The best retrofit involves (a)installing a new roof diaphragm byinstallation of diagonal steelmembers in the plane of the bottomchord of the trusses (this avoidsripping off the existing roofing); (b)strengthening the truss connectionto the pilasters (i.e., adding somesteel plates from the truss bottomchord which tie to a new beam); (c)installing a new steel beam running

along the top of the unreinforcedmasonry wall at the level of thebottom of the trusses (this beambraces the wall and serves as achord of the new roof diaphragm);and (d) installing a new mesh ofsteel reinforcing bars on the exteriorwalls, and shotcreting several inchesof new concrete to the exterior walls,to strengthen and contain theexisting brick walls. The total costfor this retrofit is estimated to be$250,000, or about $18 per squarefoot (sq. ft.).

(ii) The other alternative is to build anew gymnasium at a cost of about$125 per sq. ft., or a total cost of$1.75 million.

Science Building: The Science Building isa two-story reinforced concrete framebuilding with one-way floor slabs. Thevulnerability that can lead to collapse isinadequate ductility of the concretecolumns. In the design basis earthquake,the columns will fail in shear, resulting in a“pancake” type collapse. Two alternativesare possible:

(i) One retrofit involves replacingseveral of the interior classroompartitions (which are nonstructural)with structural concrete shear walls.Because of an interior corridor (withclassrooms along both sides), theshear walls can be placed in aregular pattern so as to take virtuallyall of the seismic lateral forces,without requiring significantstrengthening of the second floorand roof slabs. This work can beaccomplished in one summerrecess, and is estimated to be$200,000, or about $13 per sq. ft.

DECIDING WHAT TO DO


After painting, the new shear wallswill be virtually indistinguishablefrom the old partition walls.

(ii) The other alternative involvespartially demolishing partitionsaround many of the columns, andreinforcing the columns. Severalalternatives are available forreinforcing the columns, includingadding new lateral ties and concretecover, steel jacketing, or carbon fiberwrapping. Because this will have tobe done for almost all the columns,many partitions will be partiallydemolished, which makes this amore expensive alternative.

The best alternatives are retrofits estimatedto cost approximately $250,000 for thegymnasium, and $200,000 for the sciencebuilding. These retrofits are believed toprovide margin against collapse, that is,they will provide a reasonable degree of lifesafety, although they will not prevent alldamage in a strong earthquake.

In light of the life-safety threat to faculty,staff, and students, the superintendentrecommends that the trustees take theengineer’s advice and retrofit the gym andscience buildings, at a total cost of$450,000. The superintendent estimatesthis option to be more economical thanreplacing both buildings, which would costat least $4,000,000.

STEP 3: BENEFIT-COST ANALYSISFOR FOUNDATION BUILDING

The engineer finds that the wood frameFoundation Building lacks foundation boltsand has weak cripple walls (cripple wallsare short walls between the foundation andfirst floor). This situation does not pose a

substantial life-safety hazard, but thebuilding could shift from its foundation in adesign basis earthquake, resulting in repaircosts on the order of 40% of the building’sreplacement cost of $800,000, or $320,000.With repair design, fund allocation, andrepairs, the building might be vacant for upto a year.

The superintendent estimates that if theFoundation Building were vacant up to ayear, the high school would have to rent outnearby office space at a cost of $1.00 persquare foot per month, for a total of $72,000additional operating costs. Other expensesassociated with moving out of the damagedbuilding and back once repairs arecompleted could amount to $6,000 more, fora total loss under the MPE of $398,000,for the Foundation Building.

In a moderate event, the engineer’s reportgoes on to state, damage to the FoundationBuilding could be 20% of replacement cost,with two months of lost use. This equatesto $160,000 repair cost, $12,000 additionalrent, and $6,000 moving and other costs.Thus between damage and loss of use, aLE could cost $178,000.

The engineer recommends a standardrepair in such a situation: add foundationbolts and plywood sheathing to the inside ofthe cripple walls. Retrofitting theFoundation Building would costapproximately $20,000.

If the Foundation Building were retrofitted,the engineer estimates damage costs underthe MPE of $60,000, but only a few days’loss of use. In the LE, damage might cost$20,000 and have negligible loss of use. Itis now possible to perform a benefit-costanalysis for the Foundation Building.

DECIDING WHAT TO DO


The city’s planning period T is 30 years.Special loans are available, making theschool’s cost of capital i = 6% pa.

Annualized retrofit costs are therefore asfollows:

Annualized retrofit costs Cpa

Retrofit cost C = $20,000

( )

453,1$ 06.11

1

06.0000,20$

11

1

30

=

−

×

+−

=

T

pa

i

CiC

“Do-nothing” annualized damage andloss-of-use costs.

DMPE = $398,000DLE = $178,000;

[ ]

304,10$500

000,398$100

000,178$4

5001004

=

+=

+= MPELE DD

paDE

Post-retrofit annualized damage andloss-of-use costs.

DMPE = $60,000; DLE = $20,000;

[ ]

280,1$500

000,60$100

000,20$4

5001004

=

+=

+= MPELE DD

paDE

Annualized retrofit benefit B

B = E[D pa] as-is – E[D pa] retrofit

= $10,304 - $1,280

= $9,024

The benefit of retrofit in terms of reduceddamage is $9,024, or almost six times thecost, making it very cost-effective.Furthermore, the retrofit cost of $20,000 iswithin budgetary constraints, so thesuperintendent recommends performing theretrofit on the Foundation building.

STEP 4: BENEFIT-COST ANALYSIS FORLIBERAL ARTS BUILDING

The engineer examines the Liberal ArtsBuilding and determines that it was built to arecent building code, and has no significantstructural deficiencies. While the buildingmay suffer some damage in an MPE event,the engineer does not recommend anystructural retrofit.

The nonstructural component that posessubstantial damage potential are thesuspended light fixtures, which the engineernotes lack code-required braces. Thesecould come down in a LE or MPE.

DECIDING WHAT TO DO


The engineer estimates that damage in anMPE might cost $500,000 to repair, and in aLE, $50,000. If the light fixtures camedown, the debris could be removed, butsome loss of use would occur. This isdifficult to quantify; the duration would notbe long enough to justify obtainingalternative classrooms. To add bracing as aseismic retrofit would cost approximately$200,000. This would limit damage in alarge event to perhaps $5,000, and in amoderate event to a negligible amount.

Annualized retrofit costs Cpa

Retrofit cost C = $200,000

( )

600,14$ 06.11

1

06.0000,200$

11

1

30

=

−

×

+−

=

T

pa

i

CiC

Do-nothing annualized damage andloss-of-use costs.

DMPE = $500,000; DLE = $50,000;

[ ]

000,6$500

000,500$100

000,50$4

5001004

=

+=

+= MPELE DD

paDE

Post-retrofit annualized damage andloss-of-use costs.

DMPE = $5,000; DLE = $1;

[ ]

40$500

000,5$100

1$4

5001004

=

+=

+= MPELE DD

paDE

Annualized retrofit benefit B

B = E[D + U pa]as-is – E[D + Upa]retrofit

= $6000 - $40 = $5,960 = estimated annualized

reduced damage

In this situation, the annualized benefit ofretrofit is $5,960, while the annualized costis $14,600. It is not worth retrofitting thelight fixtures in the Liberal Arts Building froma financial perspective, but the performanceof light fixtures in recent earthquakesindicates they have potential to inflict headinjuries to students. Therefore, thesuperintendent recommends retrofitanyway.

The results for the Foundation and LiberalArts Buildings are summarized in Table 4-2.

DECIDING WHAT TO DO



5. Implementing the Earthquake Risk Mitigation

Program

5.1 Introduction

This chapter provides guidance on some ofthe more practical aspects of implementingan earthquake risk management program:balancing earthquake risk against otherneeds; coordinating the program with othercapital expenditures; funding the program;retention of professional services; risktransference; emergency responseplanning; and steps to take after anearthquake.

5.2 Earthquake Risk and LimitedResources

We introduced this Toolkit byacknowledging that earthquakes areserious problems in California and thatevery one knows this. Despite this wideknowledge, some Decision-Makers arereluctant to perform formal assessments oftheir earthquake risk. In some cases, thisreluctance can be attributed to a belief thatignorance of existing risk is an excuse forinaction, or to the corresponding fear thatonce the level of risk is known, action mustbe taken to reduce or eliminate it. Since allDecision-Makers operate under theconstraints of limited and often inadequateresources, there is an obvious bias towardsavoiding “new” problems and demands forexpenditure.

The perceived need to mitigate all risksonce they are discovered relates to issuesof potential liability. For example, once abuilding evaluation is performed and theDecision-Maker is informed that the buildingcould collapse in an earthquake, theDecision-Maker must either inform thepublic and personnel who spend time in thebuilding that this risk exists. Failing to do somakes the building owner subject towrongful endangerment litigation in theevent of an earthquake-induced collapse.However, some Decision-Makers think thatpersonnel who are informed of the dangermay refuse to work in the building, causingother obvious problems.

Since severe earthquakes affect a givenregion only infrequently, many Decision-Makers prefer to “bet” that damaging eventswill not occur during their term of office.Further, they believe that if an earthquakecauses the building to collapse, it will beconsidered an act of God for which they willhave no liability, particularly if no priorpositive identification of the risk wasavailable. Based on these beliefs, suchDecision-Makers adopt an "ignorance isbliss" approach to risk management, avoidhaving positive knowledge of a risk, andbelieve they have limited potential liability asa result.

In California today, the validity of anignorance-of-risk defense is highly

Primary Interest:Decision-Makers

Secondary Interest:Risk Managers

DOING – THE EARTHQUAKE RISK MITIGATION PROGRAM


questionable, particularly for publicagencies. Since everyone knows thatearthquakes are serious problems inCalifornia, Decision-Makers who areresponsible for protecting the welfare oftheir enterprises and the public are nowexpected to understand the extent of thisrisk and to deal with it in a responsiblemanner.

“Dealing with risk in a responsible manner”does not mean pretending that the risk doesnot exist. Before a risk can be managed, itmust be understood. Once the level of riskis understood, there is, at a minimum, arequirement to inform those who are at riskabout the peril they may be in. However, ifthe risk is presented with acknowledgmentof the consequences (e.g., the building maycollapse) as well as the likelihood ofoccurrence (e.g., collapse is expected onlyfor earthquakes that occur one time every500 years), most personnel will accept therisk. In essence, disclosure of potential riskto personnel is an effective mechanism forrisk transfer and is also fair.

Once an earthquake risk is understood, it ispossible for the Decision-Maker to balancethe potential losses and benefits gainedfrom a mitigation program against otherpotential uses of the limited resourcesavailable. For example, should acommunity’s limited capacity for bondindenture be limited to upgrade thewastewater processing system or used forearthquake risk reduction? It is impossibleto answer such a question until the risksand potential benefits of both programs aredefined and shared with all of the potentialstakeholders.

Often, an enterprise will find that it can notafford to embark on a major program ofearthquake retrofit, given the limited

resources available and the competing usesfor these resources. However, it is oftenpossible to obtain incremental reduction inrisk by performing limited mitigation as partof other programs. For example, if anexisting fire station is going to be expandedto provide space for an additional company,seismic upgrade of the fire station canprobably be accomplished concurrently, atlittle additional cost. Similarly, if a majorasbestos reduction program is going to bepursued, it may be possible at very littleadditional expenditure to perform concurrentseismic upgrades. Until the extent of risk isunderstood, and priorities set for mitigatingthis risk, decisions to embark on suchprograms can not be made.

After a disaster occurs, Decision-Maker areoften held responsible for having made thewrong decision, especially if losses areseen as unacceptably high and allstakeholders were not involved in thedecision process. Steps to understand therisk and share the information with theaffected stakeholders can help to minimizepost-event backlash, even if no action tomitigate is ultimately taken. Oncedisclosure is made, the stakeholders willeither acquiesce to the risk, essentiallyaccepting the role of joint Decision-Makerthemselves, or make it known that the riskmust be addressed. In either event, theDecision-Maker that actively addressesearthquake risk and involves allstakeholders is better off than one who doesnot.

5.3 Coordinating the Program

It is very important to include earthquakerisk mitigation measures with other facets ofthe asset management program. Keyissues related to this are the following:



§ Often by performing seismicupgrade work concurrently withother planned projects, it is possibleto reduce the cost and disruption ofthe upgrade work. For example, acommon requirement of seismicupgrade programs for low-risebuildings with wood roof structures isto increase the nailing of theplywood roof sheathing. This canonly be done upon removal of theroofing. Clearly, if such upgradework is performed concurrently withroutine replacement of the roofingsystem, it will be far moreeconomical.

§ If an existing facility is assessed asincapable of providing adequateseismic performance for its currentuse, consider changing its mission tobe more compatible with its seismicperformance category. Forexample, if a critical care wing of ahospital is judged incapable ofimmediate post-earthquakeoccupancy, and there issimultaneous need to develop newoutpatient care at the facility, thebest choice may be to build newcritical care space and convert theexisting space to use for outpatientcare.

§ Consideration should be given to thelength of time a facility is expected toremain in service. If a facility isscheduled for replacement orretirement in the near future, itmakes little sense to invest inupgrade of the facility.

§ Construction for seismicimprovements to a facility will oftentrigger mandatory requirements to

perform other types of upgradessuch as disabled accessimprovements, hazardous materialabatement, and fire/life safetyimprovements. These collateralupgrade requirements can havesubstantial impact on theimplementation cost and, in somecases, the cost of collateralupgrades is higher than the seismicconstruction cost. It is important toaccount for these impacts whenevaluating the cost of seismicmitigation.

Earthquake risk can not be effectivelymanaged in a vacuum. The Decision-Makerand the Risk Manager must involve theAsset Manager in planning andimplementing the mitigation program inorder to assure that collateral issues areaddressed and all capital improvements arecoordinated. It also important to askprofessional consultants, who may beretained to assist in quantifying risk andsuggesting mitigation alternatives, to bemindful of these needs.

5.4 Funding the Program

Like all programs, earthquake riskmanagement requires the investment offunds. The initial phases of the program, inwhich the risk is assessed and mitigationoptions explored, typically entails relativelymodest cost. By spreading these tasks outover a period of one or two years, mostenterprises will be able to accommodatethese costs within their normal operatingbudgets. However, major programs ofcapital improvement will typically requireextraordinary sources of funding.



The following sources should generally beconsidered when planning programs ofseismic mitigation:

§ General Operating andMaintenance Funds – Not allseismic upgrade projects areparticularly costly and some seismicupgrades can be done at nominalcost. For example, most equipmentitems can be anchored or braced forseismic resistance at a cost of a fewhundred dollars, or less. Manyenterprises will be able to coversignificant seismic upgrade activitiesout of their general operating andmaintenance funds.

§ Bond Issues – If a communityunderstands its existing earthquakerisk and is convinced that this isunacceptable, it may be willing tosupport additional bondedindebtedness as a means of raisingthe necessary funds. For example,the City of San Francisco obtainedpermission from its electorate toraise more than $100 million forearthquake safety retrofits of firestations and other municipalbuildings. From a strategicperspective, such bond measuresare most successful in the periodimmediately following a majorearthquake, when the public’sattention is drawn to the issue ofearthquake risk.

§ Special Use Fees – In some cases,it may be possible to support thecost of seismic upgrade through theestablishment of special use fees.As an example, the State ofCalifornia raised tolls on bridgescrossing San Francisco Bay as ameans of funding seismic upgradesof these structures.

§ Hazard Mitigation Grants –Occasionally, special grants becomeavailable from the federal and/orstate government for partial fundingof seismic mitigation work. Thesegrants are may be offered as 1)seed money for demonstrationprojects, to encourage and attractother sources of funding; or 2) inorder to reduce risk of damage infuture earthquakes and to helpcommunities become more self-sufficient. These grants are usuallyavailable only for public or non-profitenterprises and often are restrictedto, or give preference to, certaintypes of projects. For example,using funding obtained under theProposition 122 bond program, theState of California made limitedmitigation funding available to cities,counties and similar agencies.Generally, projects to strengthenemergency response facilities suchas fire stations, police stations, andcity halls received priority over othertypes of projects.

When mitigation grant programs areavailable, communities musttypically apply for funding incompetition with others. In addition,it is usually necessary for theenterprise to provide some co-funding of the project, often in theamount of 10% to 20% of totalproject costs.

§ Tax Preferences and Credits –Certain tax credit and tax preferenceincentives are available for therehabilitation of qualified historiclandmarks. These incentives aretypically applicable only to private,for-profit enterprises. In order to



qualify for these incentives, it isnecessary to comply with certainhistoric preservation standards andto be subjected to a review andapproval process for the design.

5.5 Retention of Professionals

Most enterprises will need to retain theservices of specialty professionalconsultants to assist the Risk Manager inimplementing portions of the earthquakerisk mitigation program. Appendix Gincludes sample scope of work statementsfor professional consultation agreementsrelated to the following services:

§ Building Risk Screening

§ Equipment Risk Screening

§ Building Risk Assessment

§ Equipment Risk Assessment

§ Building Upgrade Design

Many organizations will be able to performthe Building Risk Screening and EquipmentRisk Screening tasks with in-housetechnical personnel. However, should it benecessary to obtain consultant services forthese tasks, we recommend professionalstructural engineering consultants as themost qualified persons to perform theBuilding Risk Screening task. Eitherprofessional mechanical or structuralengineering consultants will be able toperform the Equipment Risk Screening task.

Most organizations will not have adequatestaff with the necessary qualifications toperform the Building Assessment orEquipment Assessment tasks, and it will benecessary for them to retain consultants for

this purpose. We recommend professionalstructural engineers as most qualified toperform the Building Assessment task andprofessional structural or mechanical orstructural engineers to perform theEquipment Assessment task.

Today, there are a number of options forretaining services related to buildingupgrade design and construction projects.Some of the most commonly usedapproaches include the following:

§ Conventional Project Delivery –Architectural Lead – This is howmost building construction projectshave been implemented in the past.In this method, the Owner advertisesa desire to retain Architect/Engineer(A/E) teams to design the projectand requests submittal ofqualifications form interestedproviders of services. Typically, inthis method of project delivery, anarchitect will be retained as theprime design professional. Thearchitect will then retain a team ofconsultants including structural,mechanical, and electricalengineers, as well as other specialtyconsultants to develop different partsof the design. The architectmanages the process andcoordinates the team's efforts. TheA/E team’s deliverables includedrawings and specifications that canbe used to obtain contractor bids,building permits and to perform thework. General contractors can beselected to perform the work, eitheron a low-bid, lump sum basis; anegotiated cost-plus-fixed-fee basis;or negotiated total cost basis. TheA/E team is typically retained tomonitor construction progress,



respond to contract requests forclarification of the documents andassist the owner in negotiatingchanges required to the basiccontract as a result of changedconditions.

Many agencies find this form ofproject delivery advantageous whenseismic upgrade work is performedconcurrently with other major capitalimprovements such as generalbuilding renovation or buildingexpansion. The advantages of thisproject delivery form are:

a) The architect is typically able tocoordinate large teams in thedesign of complex projects,efficiently.

b) Construction scope can be welldefined before retaining acontractor, allowing theconstruction cost to be fixed andchange orders minimized.

This project delivery form also has somedisadvantages, including:

a) Design of seismic upgradesrequires special knowledge andskills that are not possessed byall structural engineers. Thearchitect may not select the mostqualified structural engineer forthis work.

b) Because the architect may notbe focused on the needs of theseismic upgrade program, it maybecome subordinated to otherproject goals, and result in arelatively ineffective upgradedesign.

c) Since a contractor can not beretained until the design processis complete, the project may takea long time between initiation ofdesign and completion ofconstruction.

§ Conventional Project Deliverywith Structural Lead – This methodof project delivery is very similar tothat discussed above, except thatthe structural engineer acts as theprime design professional. Thisform of project delivery has beenused for a number of major seismicupgrade projects, including someprojects that had significant designcomponents from disciplines otherthan structural engineering.However, it probably makes mostsense for those projects whereseismic upgrade is the primary andmost important aspect of the project.Principal advantages of this projectdelivery method include:

a) This approach allows directselection of the structuralengineer as the leadprofessional, based onqualifications of the engineer toperform the seismic upgradedesign.

b) This approach maximizes theprobability that the projectdecisions will be made in thecontext of maximizing theeffectiveness of the seismicupgrade, as opposed to otherproject aspects.

Although this project delivery approachhas been used for some very largeprojects, such as the seismic upgrade of



the San Francisco City Hall and OperaHouse, not all structural engineers areexperienced in managing largemultidisciplinary design teams.Therefore, if this approach is selected, itis important to ascertain that the primeprofessional has the necessary skillsand knowledge to do the structuraldesign and to handle managementaspects of the project.

§ Conventional Project Deliverywith Contractor Pre-ConstructionServices – This approach may beconducted in a very similar mannerto either of the two approachespreviously described. The primarydifference is that either a GeneralContractor or Construction Manneris retained at the same time as thedesign team to provide pre-construction services, rather thanwaiting for the design to becompleted. These pre-constructionservices can include review ofdesigns for constructability, valueengineering, development of costestimates, and constructionschedules. Following completion ofthe design, the Owner can negotiatewith the contractor to provideconstruction services; retain thecontractor to act as a constructionmanager and perform the actualwork by obtaining lump-sum, low bidsubcontracts; or retain a newcontractor to provide the requiredconstruction services.

This approach has been found to beadvantageous on projects wherenew technologies with unusual orspecial construction requirementsare to be used, and on projectswhere construction is to be

performed while the facility remainsoccupied during construction. Theprincipal advantage of this approachis that the Contractor can help thedesign team to develop a design thatis more practical to build and canprovide more accurate estimates ofrequired cost and schedule thanmost design professionals. Adisadvantage is that this approachcan sometimes be more expensivethan the previous two.

§ Design-Build Delivery - In this formof project delivery the Owner retainsa general contractor to both designthe project and construct it. Theprincipal advantage of this approachis that the Owner need only dealwith a single party, the generalcontractor. This reduces some ofthe management tasks the Ownermust normally provide and, inaddition, greatly reduces thepotential for litigation between theOwner, contractor and design teamin the event that there are problemsin project execution. This projectapproach is coming into greater usein the public sector, particularly forthe construction of new facilities.Although it has occasionally beenused for renovation and upgradework, this use is relatively rarebecause successful projectexecution requires that the Ownerbe very precise in specifying theproject requirements, something thatis frequently difficult to do in seismicupgrade projects.

We can not emphasize enough that designof seismic upgrade projects is a specializedarea of practice. The building coderequirements as well as the types of



construction employed in such projects areoften quite different from those used intypical projects for the construction of newfacilities. Regardless of the type of projectdelivery system selected, we recommendthat care be taken to select consultants withappropriate qualifications and demonstratedpast success in design seismic upgrades.

5.6 Emergency Plans and RiskTransfer

After the seismic risk mitigation work hasbeen completed, the risk associated with afacility will be greatly reduced from originallevels. However, some residual risk willtypically still remain. Prudent riskmanagement suggests that effective stepsbe taken to further minimize the residual riskthrough the following steps:

§ Emergency Response Plan – Evenrelatively minor damage to a facilitycan result in extended interruption ofservice, and loss of use, if no oneknows what to do about assessingits condition, securing potentiallyhazardous contents and utilities, andconducting repairs so that servicecan be restored. Emergencyresponse plans that designate thepersons responsible for each ofthese actions, and specify how theycan be contacted in an emergencycan significantly reduce the amountof confusion and lost time when anearthquake actually occurs.

In addition to basic information onwho is responsible for specificemergency actions, Emergencyresponse plans should includeinformation on the critical equipmentand systems within the building, thestructural system, expected types

and locations of damage, andchecklists for specific post-earthquake actions. For criticalfacilities, the emergency plan canalso include provision for alternativework spaces if damage is so severethat re-occupancy of the facilitywithin the short term is not feasible.

§ Earthquake Insurance –Earthquake insurance can be aneffective method of guarding againstthe direct financial losses associatedwith an earthquake and is commonlyused in the private sector for thispurpose. Earthquake insurance isvery effective in reimbursing aproperty owner for the direct costsrelated to repair of damage. It isless effective with regard toreimbursement for businessinterruption costs, as thequantification of these costs is oftensomewhat arbitrary and thereforesubject to dispute. It is alsoimportant to note that mostearthquake insurance policiesinclude significant deductibles andwill not cover upgrades to the facilitythat may be triggered by the buildingofficial as part of damage repairwork. The cost of earthquakeinsurance is highly variable anddepends as much on the globalfinancial markets and health of theinsurance industry as it does on theactual risk associated with a facility.In some years, insurance can beobtained at a fraction of its realvalue, at other times it may costseveral times its actual value, or itmay not be available at all. Thus, itis prudent not to rely on earthquakeinsurance as the sole means of riskmanagement.



Recently, a new product on thefinancial markets--catastrophebonds--has become available as analternative to insurance. In essence,rather than purchasing insurance, anorganization can transfer its risk byselling bonds. Rather than payinginsurance premiums, the issuer ofthe bonds must pay interest to thebondholders. In the event that anearthquake loss occurs, thebondholders forfeit a portion of theirinterest and principal which may beused by the issuer to recover thecosts of the loss. Out of practicality,bond issues must have a largefinancial value to be viable, so thisapproach is typically appropriateonly for very large enterprises or forgroups of enterprises that elect topool their interests into a commonsurety.

For a number of years, the federalgovernment, through the FederalEmergency Management Agency,has adopted a practice of providinga form of zero-premium disasterinsurance for public agencies andcertain not-for-profit organizations,through disaster assistanceprograms. In essence, FEMA hasprovided up to 90% of the cost ofrepair, and in some cases upgrade,of facilities damaged by disasterssuch as earthquakes, hurricanes, ortornadoes. As a result, purchase ofinsurance has not been necessaryfor most public agencies

It is worth noting that, historically,the actual funding provided byFEMA has been variable.Sometimes it has been more than

sufficient to cover actual costs, whilein other cases it has not beensufficient. As a result, some publicagencies have elected to carryprivate earthquake insurance as asupplement to FEMA coverage. Inaddition, the federal government hasrecently come to the realization thatthese disaster assistance programshave served as a strong disincentiveagainst mitigation. As a result, therehave been several recent proposalsto either terminate these programsor condition their availability on thecommunity having taken substantiveaction to mitigate risk prior to thedisaster. If such policies areadopted, this will make risk transferthrough the private insurance andfinancial markets more attractive andimportant to public agencies.

§ Physical Redundancy andGeographic Dispersion. One ofthe most effective techniques formitigation of earthquake risk is todisperse operations intoindependent locations at differentsties. Although the effects ofearthquakes can be widelydispersed over a region of manysquare miles, the most extremeearthquake effects are typicallylimited to a small fraction of theaffected region. If all of the physicalfacilities associated with anoperation are concentrated at asingle site or location, there may besignificant potential for damage tocompletely interrupt operations foran extended period of time.However, if the physical facilities aredispersed to multiple locations, itbecomes much less likely that all ofthem would be damaged to an



extent that would limit operations atall of the locations. Thus, dispersioncan become an effective tool tomaintain at least partial operationalcapability following a majorearthquake. To the extent that thedispersed facilities provideredundant capacity, it may bepossible to have full operationalcapability even if some of thefacilities become damaged.

§ Data Backup – Redundant storageof critical records and data can be ahighly effective risk mitigationtechnique. Following the 1989 LomaPrieta earthquake, the City ofOakland’s Building Department wasdisplaced from the severelydamaged City Hall. The BuildingDepartment stored microfilm copiesof original construction drawings forprivate buildings in archives withinCity Hall. The red-tagging of thatbuilding effectively made theserecords unavailable for manymonths following the earthquake,hampering the efforts of thecommunity to assess and repairdamage sustained by otherbuildings. Had a redundant set ofmicrofilm records been maintained inan off-site location, access to bothsets of data would probably not havebeen lost.

Public agencies and privatebusinesses can maintain their ownoffsite records storage, or they canrely on providers of this service.This may be particularly importantfor electronic records that aremaintained on-line. There are anumber of private data centers thatprovide stand-by electronic records

storage, as well as data processingcapability.

§ Retain Structural Engineers andContractors – Following the 1989Loma Prieta earthquake, the City ofSan Francisco’s Building InspectionDepartment found itselfoverwhelmed by the demand toperform post-earthquake safetyinspections of public and privatebuildings in the city. Even with theassistance of many volunteerinspectors, it took months before allbuildings were evaluated and theircondition determined. During thisperiod of time, building owners andtenants often did not know whether itwas safe to reoccupy damagedbuildings, leading to extensiveeconomic losses.

In order to avoid these problems infuture earthquakes, the City of SanFrancisco later established thevoluntary Business OccupancyResumption Earthquake InspectionProgram (BOREIP). Under theBOREIP, building owners can retainqualified structural engineers toperform future post-earthquakeinspections of their buildings. Theseengineers must develop a post-earthquake inspection plan for thebuilding, and be certified by the cityas deputy building inspectors for thespecific building. Under theprogram, BOREIP inspectors areobligated to perform post-earthquake inspections within 36hours of an earthquake disaster.They then have the authority to postinspected buildings on behalf of thecity.



Building departments can developsimilar programs, to speed the post-earthquake recovery of theircommunities. In addition, even inthe absence of such programs,individual public and private buildingowners and tenants can retainstructural engineers to perform rapidpost-earthquake assessments ofbuildings, to advise as to whetherthe buildings are safe for occupancyand to develop repairs in the eventthese are required. While theseengineers would not have the powerto officially “post” a building, theycan provide assurance as thecondition of its structure andappropriate recovery actions. It isoften beneficial to develop retaineragreements with engineers beforean earthquake. In the days andweeks immediately following a majorearthquake, structural engineers areextremely busy and are unlikely tobe available on short notice unlessadvance arrangements have beenmade.

It may also be beneficial to developsimilar retainer agreements withgeneral contractors, so that there isassurance that if repairs are needed,there will be construction capabilityto do them.

5.7 What To Do after an EarthquakeAfter search and rescue operations areinitiated and the immediate threats to life-safety are addressed, the following actionsshould be undertaken following anearthquake.

§ Assess the Extent of Damage –Following an earthquake it is

necessary to assess the extent ofdamage. Determine whetherphysical facilities that are relied uponfor operations are functional andsafe, and estimate the amount oftime they may be out of service. It isimpossible to implement an effectiveresponse and recovery program untilthis information is known.

For many public agencies, theresponsibility for post-earthquakedamage assessment may extendbeyond the need to assess theperformance of the physicalfacilities, and include an assessmentof the extent of damage and losscommunity-wide. For example, ifhousing in a community is severelydamaged, public agencies will beexpected to provide for thetemporary shelter and care ofdisplaced families. If a number ofbuildings have collapsed, publicagencies will be expected to assistin locating and extracting victims. Inorder to respond to such needs, it isnecessary to be able to rapidlyassess the likely extent of damageand loss. These assessments canbe made by performing rapid post-earthquake reconnaissance, or byimplementing one of several disastersimulation software packages thatpermit rapid estimation of losses.

Regardless of the method an agencyor business elects to pursue, acurrent emergency response planand previously negotiatedagreements with necessaryengineering consultants andcontractors can speed this phase ofthe recovery effort.



§ Implement Emergency OperationsProcedures – As soon as anassessment of damage is made, andthe extent of impairment of ability toprovide service and the need forthese services is ascertained,recovery operations shouldcommence. In the periodimmediately following theearthquake, individual publicagencies and private businesses willhave to rely on their own resources.An effective emergency responseplan can help to smooth the difficultimmediate post-event recoveryperiod. Within days to weeks,outside assistance will begin tobecome available from such sourcesas the Federal EmergencyManagement Agency, the State ofCalifornia Office of EmergencyServices, the American Red Crossand other volunteer agencies. Inextreme emergencies, militaryassistance may also be madeavailable.

§ Restore Normal Operations – Overa period of days to weeks and, in theworst disasters, perhaps a period ofyears, normal operations will berestored. The length of timenecessary for restoration of normaloperations will be directly dependenton the severity of the event, as wellas the extent to which risks wereidentified and mitigated, andemergency response plansdeveloped prior to the event.

It many cases, what is deemed“normal operations” after theearthquake is not the same conditionthat existed before the event.Earthquakes can have broad

economic and social impacts thatcan completely change the characterof a community and the long-termprofitability of individual businesses.For this reason, it is particularlyimportant that public leaders viewearthquake risk reduction not only astheir responsibility with regard toprotection of public facilities, but alsoas a responsibility that the entirecommunity must share. One of themajor benefits of risk mitigation onthe part of a public agency is that itsets a leadership example for thecommunity at large.

§ Assess the Lessons Learned – Animportant, but often overlookedconcluding step in the earthquake-recovery process is a carefullyconducted review of the loss andrecovery experience. No matter howwell prepared a community orbusiness is for an emergency, it willtypically be found that unanticipatedproblems developed and thatpreparation could have been better.Although severe earthquakes arerare events, it is possible for somecommunities in California to havemajor damaging events more thanonce during a typical lifetime. TheSan Fernando Valley, for example,experienced large magnitude eventsin both 1971 and 1994. A carefulassessment of what went wrong andwhat went right in the disaster canallow for better preparation for thenext event. It will also serve as avaluable learning tool for othercommunities that have not yet beenaffected by their earthquakedisaster.

Proposition 122 Product 2.2Seismic Risk Management Tools For Decision Makers 6-1

6. References

1. American Institute of ChemicalEngineers (AIChE). Tools for MakingAcute Decisions with Chemical ProcessSafety Applications, Center for ChemicalProcess Safety of the AIChE, New York.1995.

2. American Society of Civil Engineers(ASCE). Standard Methodology forSeismic Evaluation of Buildings. ReportNo. FEMA-310. Federal EmergencyManagement Agency. Washington,D.C. 1998.

3. Ang, A. H-S., and Tang, W.H.,Probability Concepts in Engineering,Planning and Design. New York: Wiley.1966.

4. Applied Technology Council (ATC),Earthquake Damage Evaluation Data forCalifornia. Report No. ATC-13.Redwood City, CA. 1985.

5. Applied Technology Council.Methodology for Seismic Evaluation andUpgrade of Reinforced ConcreteBuildings. Report No. ATC-40.California Seismic Safety Commission.Sacramento, CA. 1997.

6. Applied Technology Council. RapidVisual Screening of Buildings. Report.No. ATC-21. Federal EmergencyManagement Agency. Washington, DC1987.

7. Applied Technology Council.Standardized Loss EstimationMethodology for Buildings in California.Report No. ATC-13, Redwood City, CA1985.

8. Aron, R., The Opium of the Intellectuals,tr. T. Kilmartin. Westport: GreenwoodPress Publications. 1955.

9. Benjamin, J. and Cornell, C.A.Probability, Statistics and Decision forCivil Engineers. New York: McGraw-Hill,1970.

10. Building Seismic Safety Council.NEHRP Guidelines for SeismicRehabilitation of Buildings. Report No.FEMA-273. Federal EmergencyManagement Agency. Washington, DC.1997.

11. California Division of Mines andGeology (CDMG). Earthquake PlanningScenario for a Magnitude 8.3Earthquake on the San Andreas Fault inthe San Francisco Bay Area. SpecialPublication 61, Sacramento, CA. 1982.

REFERENCES

Proposition 122 Product 2.26-2 Seismic Risk Management Tools For Decision Makers

12. California Division of Mines andGeology (CDMG). Earthquake PlanningScenario for a Magnitude 7.5Earthquake on the Hayward Fault in theSan Francisco Bay Area. SpecialPublication 78, Sacramento, CA. 1987.

13. Central United States EarthquakeConsortium (CUSEC). An Assessmentof damage and Casualties for Six Citiesin the Central United States Resultingfrom Earthquakes in the New MadridSeismic Zone. Washington, DC: FederalEmergency Management Agency. 1985.

14. Dames & Moore. Seismic RiskManagement Tools, Product 2.1,Contract SC2.1, for the CaliforniaSeismic Safety Commission.Sacramento, CA., November, 1994.

15. International Conference of BuildingOfficials. Uniform Building Code.Whittier, CA. 1997.

16. Johnson, G.S., Sheppard, R.E., Quilici,M.D., Eder, S.J. and Scawthorn, C.R.Seismic Reliability Assessment ofCritical Facilities: A Handbook,Supporting Documentation and ModelCode Provisions. Report No. 99-0008.Multidisciplinary Center for EarthquakeEngineering Research. Buffalo, NY.1999.

17. Porter, K., C. Scawthorn, C. Taylor, andN. Blais. Appropriate Seismic Reliabilityfor Critical Equipment Systems –Recommendations Based on RegionalAnalysis of Financial and Life Loss.Report No. 98-0016. MultidisciplinaryCenter for Earthquake EngineeringResearch. Buffalo, NY, 1998.

18. Naidus, R.M. “Can Our HospitalsHandle Another Loma Prieta?” Pages11-12 in San Francisco Medicine: theJournal of the San Francisco MedicalSociety. Vol. 69, no. 4, April 1996. SanFrancisco, CA.

Proposition 122 Product 2.2Earthquake Risk Management: A Toolkit For Decision-Makers A-1

Appendix A: Glossary

acceleration: The rate of change of velocity of a reference point. Commonly expressed as afraction or percentage of the acceleration due to gravity (g), where g = 980 cm/s2.

active fault: An earthquake fault that is considered likely to undergo renewed movement withina period of concern to humans. Faults are commonly considered to be active if they havemoved one or more times in the last 10,000 years, but they may also be considered active whenassessing the hazard for some applications even if movement has occurred in the last 500,000years. (see fault)

alluvium: A soil type consisting of loosely compacted gravel, sand, silt, or clay deposited bystreams. Structures founded on alluvium can experience amplified ground shaking intensities.

Alquist-Priolo Fault Zoning Act: Passed in 1972 by the California Legislature, the Alquist-Priolo Earthquake Fault Zoning Act's main purpose is to prevent the construction of buildingsused for human occupancy on a fault trace. Passage of the Act was a direct result of the 1971San Fernando earthquake, which was associated with extensive surface fault ruptures thatdamaged numerous homes, commercial buildings, and other structures. The Act onlyaddresses the hazard of surface fault rupture and is not directed toward other earthquakehazards. The Act also establishes so-called Alquist-Priolo Earthquake Fault Zones ("SpecialStudies Zones" prior to January 1, 1994), regulatory regions around active faults that averageabout ¼ mile wide where construction of buildings for human occupancy are controlled. Non-surface fault rupture hazards are addressed by the Seismic Hazards Mapping Act. (seeseismic zonation)

amplification: An increase in seismic wave amplitude as it propagates through certain soils.

annualized loss: The loss per annum due to earthquakes, calculated as the probabilistic losscontribution of all events. Annualized loss is expressed as a probability distribution of loss perannum. The expected annual loss is the expectation of this probability distribution of loss perannum, and under certain assumptions may be calculated as the probability-weighted averageof loss due to all possible earthquake events.

attenuation: The rate at which seismic wave amplitude decreases with distance from itssource.

baseline risk: The existing risk, under current or as-is conditions. (see Section 3.12)

GLOSSARY

Proposition 122 Product 2.2A-2 Earthquake Risk Management: A Toolkit For Decision-Makers

base isolation: A structural design concept that reduces the magnitude of lateral response bypreventing earthquake ground motion from being transmitted from the foundation into thebuilding superstructure. Application is accomplished through the installation of isolator bearingsat all of the connections between the structure and the foundation. The isolators are verticallystiff, capable of supporting vertical gravity loads, while being laterally flexible, capable ofallowing large horizontal displacements. In effect, the ground is allowed to move back and forthunder a base isolated building during an earthquake, while leaving the building to remain“stationary.”

benefit-cost analysis: A risk management tool used to make decisions about accepting risk orusing some other risk management technique. (see Section 4.3)

brittle failure: Describe the failure mode of a structural element or material that has undergonevery little deformation with very little energy absorption.

business interruption (BI): Economic loss associated with loss of function of a commercialenterprise.

compaction: The uniform or differential settlement of loose soils or poorly consolidatedalluvium as a result of ground shaking.

completeness: Homogeneity of the seismicity record.

cripple wall: A carpenter’s term indicating a wood frame wall of less than full height, locatedbetween the foundation and the first floor framing.

damage: Physical disruption, such as cracking in walls or overturning of equipment (often usedsynonymously with loss).

damping: Represents the force or energy lost in the process of material deformation.

decision hierarchy: The priority in which decisions are required to be made (e.g., (1) whetherto retrofit or not?, (2) whether to retrofit for collapse prevention or for no damage?, (3) whetherto employ bracing vs. shear walls?, and so on).

deterministic methods: Refers to engineering and financial methods of calculating groundmotions for hypothetical earthquakes based on earthquake-source models and wave-propagation methods that exclude random effects.

ductile detailing: Special requirements for the placement of the reinforcing steel withinstructural elements of reinforced concrete and masonry construction necessary to achieveductile behavior (ductility). Examples of ductile detailing include close spacing of lateralreinforcement to attain confinement of a concrete core, appropriate relative dimensioning ofbeams and columns, 135 degree hooks on lateral reinforcement, and hooks on main beamreinforcement within the column.

GLOSSARY


ductility: The ability of a structural element or material to offer resistance, sustain largedeformations, and absorb energy without brittle failure. Commonly quantified by the ratio ofthe total displacement (elastic plus inelastic) to the elastic (i.e., yield) displacement.

earthquake : Ground shaking and radiated seismic energy caused most commonly by suddenslip on a fault, volcanic or magmatic activity, or other sudden stress changes in the earth.

earthquake hazard: The potential for or occurrence of any physical phenomenon associatedwith an earthquake to produce adverse effects on human activities that might lead to loss (ordamage). This includes ground shaking, fault rupture, landsliding, liquefaction, tectonicdeformation, tsunami, and seiche and their effects on land use, manmade structures, andsocioeconomic systems. A commonly used restricted definition of earthquake hazard is theprobability of occurrence of a specified level of ground shaking in a specified period of time.

earthquake risk: (see seismic risk)

energy dissipation systems : Various structural devices that actively or passively absorb aportion of the earthquake energy in order to reduce the magnitude or duration (or both) of thebuilding earthquake response. These devices include active mass systems, passive visco-elastic dampers, tendon devices, and base isolation, and may be incorporated into the buildingdesign.

epicenter: The projection on the ground surface directly above the hypocenter of anearthquake.

essential facilities: Structures whose ongoing performance during an emergency is requiredor whose failure could threaten many lives. May include (1) structures such as nuclear powerreactors or large dams whose failure might be catastrophic; (2) major communication, utility,and transportation systems; (3) involuntary- or high-occupancy buildings such as schools orprisons; and (4) emergency facilities such as hospitals, police and fire stations, and disaster-response centers.

fault: A fracture along which there has been significant displacement of the two sides relative toeach other parallel to the fracture. Strike-slip faults are vertical (or nearly vertical) fracturesalong which rock masses have mostly shifted horizontally. If the block opposite an observerlooking across the fault moves to the right, the slip style is termed right lateral; if the blockmoves to the left, the motion is termed left lateral. Dip-slip faults are inclined fractures alongwhich rock masses have mostly shifted vertically. If the rock mass above an inclined fault isdepressed by slip, the fault is termed normal, whereas if the rock above the fault is elevated byslip, the fault is termed thrust (or reverse). Oblique-slip faults have significant components ofboth slip styles.

fault rupture: A concentrated, permanent deformation that occurs along the fault trace andcaused by slip on the fault.

GLOSSARY


fault scarp: A step-like linear landform coincident with a fault trace and caused by geologicallyrecent slip on the fault.

fault trace: An intersection of a fault with the ground surface; also, the line commonly plottedon geologic maps to represent a fault.

fragility: The probability of having a specific level of damage given for a specified level ofhazard.

frequency: Number of cycles occurring in a given unit of time.

fundamental period: The longest period for which a structure shows a maximum response(the reciprocal of natural frequency).

ground failure: A general reference to fault rupture, liquefaction, landsliding, and lateralspreading that can occur during an earthquake.

ground fault rupture: (see fault rupture)

ground shaking: General term referring to the qualitative or quantitative aspects of movementof the ground surface from earthquakes. Ground shaking is produced by seismic waves thatare generated by sudden slip on a fault and travel through the earth and along its surface.

hazard: The potential for or occurrence of any physical phenomenon to produce adverseeffects on human activities and might lead to loss. (see earthquake hazard).

hypocenter: The location of initial radiation of seismic waves.

intensity: A subjective numerical index describing the severity of an earthquake in terms of itseffects at the ground surface and on humans and their structures. Several scales exist, but thetwo most commonly used in the United States are the Modified Mercalli Intensity (MMI) andthe Rossi-Forel (RF) scales.

isoseismal: Refers to a line on a map bounding points of equal ground shaking intensity for aparticular earthquake.

lateral force-resisting system: A structural system for resisting horizontal forces due toearthquake or wind (as opposed to the vertical force-resisting system, which providessupport against gravity forces).

landsliding: The abrupt downslope movement of soil and/or rock in response to gravity. Anearthquake or other natural causes can trigger landslides. Undersea landslides can causetsunamis.

lateral spreading: The landsliding of gentle, water-saturated slopes with rapid fluid-like flowmovement caused by ground shaking and liquefaction.

GLOSSARY


lifelines: Structures that are important or critical for urban functionality. Examples includeroadways, water distribution systems, pipelines, power transmission lines, sewers,communications, and port facilities.

Likely Earthquake (LE): An earthquake [as defined by various parameters, such as PGA orresponse spectra] representative of the intensity of ground shaking likely to be experiencedone or more times during the facility’s life. The LE is defined as having a mean return period of100 years. In any 50-year period, there is approximately a 40% chance that such shaking willbe exceeded.

liquefaction: A process by which water-saturated soil temporarily loses shear strength due to abuild-up of pore pressure and acts as a fluid.

loss: The human or financial consequences of damage, such as human death or injury, cost ofrepairs, or disruption of social or economic systems.

loss of market share: A reduction in market stature or economic position associated with lossof function of a commercial enterprise.

magnitude: A unique measure of an individual earthquake’s release of strain energy,measured on a variety of scales, of which the moment magnitude MW (derived from seismicmoment) is preferred. (see Richter Scale)

mass-reduction: A structural mitigation concept where the weight (or mass) of the building isreduced, in turn reducing the lateral earthquake response and the corresponding forces. Thismitigation measure is generally considered impractical since it usually requires the demolition ofa significant portion of the subject building.

Maximum Probable Earthquake (MPE): A severe earthquake [as defined by variousparameters, such as PGA or response spectra] that may occur one time during the life of afacility. The MPE is defined as having a mean return period of roughly 500 years. In any 50-year period, there is approximately a 10% chance that ground motion of this intensity will beexceeded. The California Building Code (CBC) requires that new buildings be designed toresist this level of earthquake without endangering life-safety.

mean: The average value in a distribution.

median: The value in a distribution where 50% of the distribution values are greater than orless than the median value.

Modified Mercalli Intensity (MMI) scale: A qualitative scale for measuring the severity ofearthquake ground shaking at a site through the evaluation of the way people react to it and itseffects on typical types of structures, such as chimneys and masonry buildings. The MMI scaleis the most commonly used intensity scale in the United States and is shown in Table C-1.

meizoseismal: The area of strong shaking and damage.

GLOSSARY


natural frequency(ies): The discrete frequency(ies) at which a particular elastic systemvibrates when it is set in motion by a single impulse and not influenced by other external forcesor by damping. It is the reciprocal of fundamental period.

non-ductile frames: Frames lacking ductility or energy absorption capacity due to lack ofductile detailing. Ultimate load is sustained over a smaller deflection (relative to ductileframes) and for only a fewer cycles before a generally brittle failure.

pancake collapse: A structural collapse-mode typical of multi-story, concrete-frame buildings,where the columns fail and the floors slabs collapse under gravity, resting in a pile of tightlypacked layers, similar to a stack of pancakes.

peak ground acceleration (PGA): The maximum amplitude of recorded acceleration (alsotermed the ZPA, or zero period acceleration).

performance objectives: A range of limiting structural damage and functionality states for afacility given a specific earthquake event. (see Table 3-4)

pounding: The collision of adjacent buildings during an earthquake due to insufficient lateralclearance.

probabalistic methods: Refer to engineering and financial methods of calculating groundmotions for hypothetical earthquakes based on earthquake-source models and wave-propagation methods that take into account the randomness and uncertainty associated with thenatural phenomena and associated structural and societal response.

probability of exceedence : A measure (expressed as a percentage or ratio) of estimation ofthe chance that an event will meet or exceed a specified threshold (e.g., magnitude, intensity, orloss).

probability of occurrence: A measure (expressed as a percentage or ratio) of estimation ofthe chance that a specific event will occur.

ranking: A process of establishing the order or priority.

recurrence interval: The average time span between events (such as large earthquakes orground shaking exceeding a particular intensity) at a particular site (also termed return period).

redundancy: (see structural redundancy)

residual risk: The remaining risk after risk management techniques have been applied.

response spectrum: A plot of maximum amplitudes (acceleration, velocity or displacement)of a single degree of freedom oscillator (SDOF), as the natural period of the SDOF is variedacross a spectrum of engineering interest (typically, for natural periods from 0.03 to 3 or moreseconds, or frequencies of 0.3 to 30+ hertz).

GLOSSARY


return period: (see recurrence interval)

Richter Scale: A system developed by American seismologist Charles Richter in 1935 tomeasure the strength (or magnitude) of an earthquake, indicating the energy released in anevent.

risk: The potential for loss. Risk can be expressed in absolute terms such as ‘the risk ofcollapse’, or in probabilistic terms, such as ‘the risk per year is $1,000’.

risk acceptance: A risk management technique that allows management to weigh the cost ofmanaging the risk versus the benefits of reducing the risk.

risk assessment: The identification of risk, the measurement of risk, and the process ofprioritizing risks for a specific hazard.

risk transference : A risk management technique to remove risk from one area to another orone party to another. Insurance transfers risk of financial loss from insured to insurer.

sand boils or mud volcanoes: Ejecta of solids (i.e., sand or silt) carried to the ground surfaceby water, due to excessive pore pressure associated with liquefaction.

satisficing: A risk management decision technique that is used to find one or more alternativesthat can satisfy all (or most) of the organization's goals rather than determining the bestalternative for a single goal.

scenario event: An earthquake for which all initiating event natural phenomena parameters arespecified (e.g., epicentral location, magnitude, length of fault rupture, fault displacement, etc.).Dependent natural phenomena, such as amount and location of liquefaction, are determinedfrom the initiating event parameters.

scenario loss: The loss due to a specific scenario event.

seiche: The movement of water in a lake, reservoir, or other enclosed body of water producedby a local or distant earthquake.

seismicity: The geographic and historical distribution of earthquakes.

seismic hazards: The phenomena and/or expectation of an earthquake-related agent ofdamage, such as vibratory ground motion (i.e., ground shaking), inundation (e.g., tsunami,seiche, dam failure), various kinds of permanent ground failure (e.g. fault rupture, liquefaction),fire or hazardous materials release.

Seismic Hazards Mapping Act: Passed in 1990 by the California Legislature, the SeismicHazards Mapping Act addresses non-surface fault rupture earthquake hazards, includingliquefaction and seismically induced landslides. Surface fault rupture is addressed by theAlquist-Priolo Fault Zoning Act.

GLOSSARY


seismic moment: A measure of the size of an earthquake based on the area of fault rupture,the average amount of slip, and the shear modulus of the rocks offset by faulting. Seismicmoment can also be calculated from the amplitude spectra of seismic waves.

seismic risk: The product of the hazard and the vulnerability and equals the probability ofsocial or economic consequences of an earthquake. (see risk)

seismic wave: An elastic wave generated by an earthquake impulse. Seismic waves maypropagate either along or near the ground surface (for example, Rayleigh and Love waves) orthrough the interior of the earth (P and S waves).

seismic zonation: Geographic delineation of areas having different potentials for hazardouseffects from future earthquakes. Seismic zonation can be done at any scale - national, regional,or local. California has two Seismic Zones as identified in the California Building Code (CBC),“Zone 3” and “Zone 4.” Zone 3 is the less seismically active area and is located in the northern-central valley of the State extending from the northern border to Bakersfield, plus a portion ofthe desert area east of the San Bernardino Mountains. This is a large portion of the State andincludes Sacramento. Zone 4 is the most seismically active area and is located along thewestern coast of the State extending from Eureka to San Diego. This is a large portion of theState and includes most all of the inland area from Bakersfield to the southern border. (also seeAlquist-Priolo Fault Zoning Act)

seismotectonic model: A mathematical model representing the seismicity, attenuation, andrelated environment.

site amplification: (see amplification)

slip: The relative displacement of formerly adjacent points on opposite sides of a fault,measured on the fault surface.

slip model: A kinematic model that describes the amount, distribution, and timing of slipassociated with a real or postulated earthquake.

slip rate: The average rate of displacement at a point along a fault as determined fromgeodetic measurements, from offset man-made structures, or from offset geologic featureswhose age can be estimated.

soft story: A story of a building significantly less stiff than adjacent stories (that is, the lateralstiffness is 70% or less than that in the story above, or less than 80% of the average stiffness ofthe three stories above [BSSC, 1994]).

soil: In earthquake engineering, all unconsolidated material above bedrock.

soil profile: The vertical arrangement of soil horizons down to the parent material or tobedrock.

GLOSSARY


source: The geologic structure that generates a particular earthquake.

Special Studies Zones: (see Alquist-Priolo Fault Zoning Act)

spectrum amplification factor: The ratio of a response spectral parameter to the groundmotion parameter (where parameter indicates acceleration, velocity or displacement).

strike: The approximate direction of the intersection of a fault and the surface of the earth,usually measured from North (e.g., the fault strike is N 60o W).

structural redundancy: The method of design where load resistance of a structure is suppliedby more than one load path.

subduction: Refers to the plunging of a tectonic plate (e.g., the Pacific) beneath another (e.g.,the North American) down into the mantle, due to convergent motion.

surface waves: Seismic waves transmitted within the surficial layer of the earth, and are of twotypes: horizontally oscillating Love waves (analogous to S-body waves) and vertically oscillatingRayleigh waves.

tsunami: An impulsively generated sea wave of local or distant origin that results from large-scale seafloor displacements associated with large earthquakes, major submarine slides, orexploding volcanic islands.

Upper Bound Earthquake (UBE): An earthquake [as defined by various parameters, such asPGA or response spectra] representative of the most severe ground shaking that could everoccur at a specific site. The UBE is defined as that intensity of ground shaking likely to beexperienced at least one time every 1,000 years. In any 50-year period, there is approximatelya 5% chance that such shaking will be exceeded.

vertical force-resisting system: A structural system for resisting vertical forces due to gravity(as opposed to the lateral force-resisting system, which provides support against earthquakeand wind forces).

vulnerability: The expected damage given a specified value of a hazard parameter.

yield: The point at which a structural element or material begins to loose its ability to resist anyadditional applied load. The transition point between elastic and inelastic behavior.

Proposition 122 Product 2.2Earthquake Risk Management: A Toolkit For Decision-Makers B-1

Appendix B: Resources

There is a variety of information and resources readily available on various aspects ofearthquake risk management, which we catalog below.

B.1 Internet Resources

Site URL Contains

Applied TechnologyCouncil (ATC)

www.atcouncil.org

ATC site contains information about thecouncil's mission and organization;recent news releases; newsletters;recent reports, briefs, and trainingmanuals; databases; seminars andworkshops; and other ATC products.

Association of BayArea Governments(ABAG)

www.abag.orgMaps of seismicity for the San FranciscoBay Area; information on buildingvulnerability.

California Division ofMines and Geology(CDMG)

www.consrv.ca.gov/dmg

CDMG has primary responsibility forwork in the geosciences in California,including hazard mapping, earthquakescenarios, a strong motioninstrumentation program, and policyimplementation.

California SeismicSafety Commission(CSSC)

www.seismic.ca.gov

CSSC Web site provides informationabout the commission, its publications,pending legislation relevant to seismichazards in California, and a table ofsignificant California earthquakes.

California Universitiesfor Research inEarthquakeEngineering (CUREe)

www.curee.org

CUREe is a consortium of eightuniversities to coordinate work onearthquake research problems:California Institute of Technology,Stanford University, University ofCalifornia at Berkeley, UC Davis, UCIrvine, UCLA, UC San Diego, and USC.

Disaster ResearchCenter (DRC) www.udel.edu/DRC

DRC is the first social science researchcenter in the world devoted to the studyof disasters.

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Proposition 122 Product 2.2B-2 Earthquake Risk Management: A Toolkit For Decision-Makers

Site URL Contains

EarthquakeEngineering ResearchCenter (EERC)

www.eerc.berkeley.edu/eea

Earthquake Engineering Abstractscovers the world literature in earthquakeengineering since 1971. Contentsinclude selected technical reports,conference papers, monographs, andjournal articles. Most materials areavailable for loan from the PEER library(University of California at Berkeley).

EarthquakeEngineering ResearchInstitute (EERI)

www.eeri.orgN\EERI is the de facto US nationalsociety for earthquake engineering –contains useful information and links.

EQNETwww.EQNET.org

Excellent database of EarthquakeInformation Sources on the Web.

Federal EmergencyManagement Agency(FEMA)

www.fema.govFEMA web site has many freepublications of high caliber, usefulinformation.

MultidisciplinaryCenter for EarthquakeEngineering Research(MCEER)

www.mceer.buffalo.edu

MCEER bibliographies, literature andresearch guides, and list of FEMA andNEHRP guidelines and handbooks forearthquake resistant construction anddesign. The latter category includesSeismic Safety of Lifelines, SeismicSafety of Existing Buildings, and SeismicSafety of New Buildings.

Natural HazardsResearch andApplicationsInformation Center(NHRAIC)

www.colorado.edu/hazards/litbase/litindex

HazLit is an excellent on-line index thatprovides bibliographic access only to thatcollection of NHRAIC at the University ofColorado at Boulder. While Hazlit is nota full-text database, and the HazardsCenter Library does not loan its holdingsto the public, this is an excellentresource.

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Site URL Contains

Pacific EarthquakeEngineering Research(PEER) Center

www.peer.berkeley.edu

PEER is a consortium of earthquakeengineering research universities in theWestern U.S. – the web site has theirreports, much useful information.

Southern CaliforniaEarthquake Center(SCEC)

www.scec.org

SCEC is a Science and TechnologyCenter of the National ScienceFoundation. Home Page containsbackground information about SCEC andlinks to its many member academicinstitutions. Both the SCEC newsletterand SCEC publications list are availablefrom this site. Also, check out theEarthquake Hazard Analysis Map--amap of probable future SouthernCalifornia earthquakes.

Structural EngineersAssociation ofCalifornia (SEAOC)

www.seaoc.org

SEAOC's site is useful for keeping upwith research specific to structuralengineering, esp. buildings, and with thepractice.

University ofWashingtonearthquake page

www.geophys.washington.edu/seismosurfing

Excellent general site, with directory tomany other sites related to earthquakes.

United StatesGeological Survey(USGS) EarthquakeInformation

www.quake.wr.usgs.govExcellent source of earthquakeinformation for many aspects.

B.2 Seismic Safety CommissionThe Seismic Safety Commission of California publishes a variety of documents related toearthquakes and earthquake safety. Listed below are the Commission's current publicationsrelated to earthquake risk management.

§ SSC 86-01 The Commission's Role in Seismic Research (Committee Report)

§ SSC 87-03 Guidebook to Identify and Mitigate Seismic Hazards in Buildings with Appendix(Commission Report)

§ SSC 87-02 Financial and Social Impacts of Unreinforced Masonry Building Rehabilitation(Commission Report)

§ SSC 88-01 California at Risk: Steps to Earthquake Safety for Local Governments(Commission Report)

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§ SSC 90-05 Earthquake Hazard Identification and Voluntary Mitigation: Palo Alto's CityOrdinance (Commission Report)

§ SSC 90-06 Report to the Governor on Executive Order D-86-90 (Commission Report)

§ SSC 90-07 Damage to Unreinforced Masonry Buildings in the Loma Prieta Earthquake ofOctober 17, 1989 (Rutherford & Chekene Consulting Engineers)

§ SSC 90-08 Earthquake Emergency Preparedness and Response (Commission Report)

§ SSC 91-02 Planning for the Next One (Transcripts of Hearings on the Loma PrietaEarthquake of Oct. 17, 1989)

§ SSC 91-05 Breaking the Pattern: A Research and Development Plan to Improve SeismicRetrofit Practices for Government Buildings (Charles Thiel, et al.)

§ SSC 91-06 Loma Prieta's Call To Action (Janice R. Hutton)

§ SSC 91-09 A California Business Owners' Earthquake Insurance Program (CommitteeReport)

§ SSC 91-10 Architectural Practice & Earthquake Hazards (A Report of the Committee on theArchitect's Role in Earthquake Hazard Mitigation)

§ SSC 92-03 The Right to Know: Disclosure of Seismic Hazards in Buildings

§ SSC 93-01 The Commercial Property Owner's Guide to Earthquake Safety

§ SSC 93-02 Proposed Maps for NEHRP's Recommended Provision

§ SSC 93-03 Creating a Seismic Safety Advisory Board: A Guide to Earthquake Risk

§ SSC 94-01 California at Risk: 1994 Status Report

§ SSC 94-02 Provisional Commentary for Seismic Retrofit, Product 1.1

§ SSC 94-03 Review of Seismic Research Results for Existing Buildings, Product 3.1

§ SSC 94-04 The Tsunami Threat to California: Hearings before the California Seismic SafetyCommission

§ SSC 94-05 Seismic Risk Management Tools, Product 2.1

§ SSC 94-06 Northridge Buildings Case Studies Project, Product 3.2

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§ SSC 94-07 Northridge Earthquake Hearings: Draft Transcripts of Hearings Held February 10& 11 and March 2 & 3, 1994

§ SSC 94-08 A Compendium of Background Reports on the Northridge Earthquake (January17,1994) for Executive Order, W-78-94

§ SSC 94-10 Research and Implementation Plan Earthquake Risk Reduction in California

§ SSC 94-11 Northridge Earthquake, January 17,1994: The Hospital Response (Donald H.Cheu, M.D.)

§ SSC 95-01 Northridge Earthquake: Turning Loss to Gain. Seismic Safety CommissionReport to Governor Pete Wilson, Governor's Executive Order, W-78-94

§ SSC 95-02 A Reconnaissance Report to the Seismic Safety Commission on the Hyogo-kenNanbu Earthquake, (Neisei Nana Nen) The South Hyogo Prefecture near Kobe, Japan,January 17, 1995 (L. Thomas Tobin, Executive Director, Seismic Safety Commission)

§ SSC 95-03 Public Safety Issues from the Northridge Earthquake of January 17,1994

§ SSC 95-04 1995 Recommended Model Ordinance for the Seismic Retrofit of HazardousUnreinforced Masonry Bearing Wall Buildings

§ SSC 95-05 1995 Status of California's Unreinforced Masonry Building Law

§ SSC 97-01 The Homeowner's Guide to Earthquake Safety,1998 Edition

§ SSC 97-02 California Earthquake Risk Reduction Plan, 1997-2001

§ 1990 SB 1250: Seismic Retrofit Cost Estimates for State Owned Buildings (CommissionReport)

§ Draft Commentary to the Structural Engineers Association of California & California BuildingOfficials, Joint Recommended Unreinforced Masonry Building Seismic Safety Provisions(Wiss Janny Elstner Associates)

How to Order: SSC publications can be order from:

Seismic Safety Commission1755 Creekside Oaks Drive, Suite 100

Sacramento, California 95833PHONE: (916) 263-5506

FAX: (916) 263-0594

Quantity discounts for orders of more than five copies of any one publication are also available.

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B.3 California Governor’s Office of Emergency Services

The California Governor’s Office of Emergency Services (OES) publishes a variety ofdocuments related to earthquakes safety and earthquake risk management. Listed below aresome of OES's current publications available for order.

§ Emergency Planning Guidance for Local Government. This document addressesemergency planning at the city and county level. It has evolved from the insight andexperience gathered from past disasters and the cooperation between OES staff and localgovernment emergency managers. This guidance document is divided into three volumes,as described below:

Volume I - The Emergency Planning Guide contains examples from sections of local plansfrom jurisdictions throughout California. This volume is intended to be a "cookbook"describing the elements and processes needed to develop critical parts of any emergencyplan.

Volume II & Volume III - The local government and the operational area emergency planexamples are represented as Santa Luisa Del Mar and Santa Luisa County, respectively.These "model" plans are included to provide an overall example of the content and structureof SEMS based disaster plans. The tables, checklists and functional organizations depictedare examples and are not intended to represent a single specific model of how jurisdictionsshould incorporate SEMS into their emergency plan.

§ Emergency Planning Guidance for Public and Private Water Utilities. This document isintended to assist water utilities of all sizes comply with the requirements of the StateDepartment of Health Services and the Standardized Emergency Management System, andimprove coordination among water utilities and other emergency response agencies.Compliance with the guidance may also assist investor owned utilities in cost recovery ofdamages and as an aid in reducing potential liability.

How to Order: OES publications can be obtained by contacting any regional OES office:

COASTAL REGION (OAKLAND)1300 Clay Street, Suite 408Oakland, CA 94612PHONE: (510) 286-0895

INLAND REGION NORTH2395 N. Bechelli LaneRedding, CA 96002PHONE: (916) 224-4835

INLAND REGION SOUTH2550 Mariposa Mall, Room 181Fresno, CA 93721PHONE: (209) 445-5672FAX: (209) 445-5987

SOUTHERN REGION (LOS ALAMITOS)11200 Lexington Drive, Bldg.283 LosAlamitos, CA 90720-5002PHONE: (562) 795-2900FAX: (562) 795-2877

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SOUTHERN REGION (SAN DIEGO)1350 Front Street, Suite 2041San Diego, CA 92101PHONE: (619) 525-4287

SOUTHERN REGION (SANTA BARBARA)117 W. Micheltorena Street, Suite DSanta Barbara, CA 93101PHONE: (805) 568-1207

B.4 Federal Emergency Management Agency

The Federal Emergency Management Agency (FEMA) publishes a variety of documents relatedto earthquake safety, preparedness, risk management, and mitigation. Listed below are someof FEMA's current publications available for order.

§ Rapid Visual Screening of Buildings for Potential Seismic Hazards: A Handbook (FEMA-154, 1988, 185 pages) and Rapid Visual Screening of Buildings for Potential SeismicHazards: Supporting Documentation (FEMA-155, 1988, 137 pages). Prepared by theApplied Technology Council, Redwood City, CA.

The Handbook presents a method for quickly identifying buildings posing risk of death,injury, or severe curtailment in use following an earthquake. The methodology, "RapidScreening Procedure (RSP)," can be used by trained personnel to identify potentiallyhazardous buildings on the basis of a 15 to 30 minute exterior inspection, using a datacollection form included in the Handbook. Twelve basic structural categories areinspected, leading to a numerical "structural score" based on visual inspection. Buildinginspectors are the most likely group to implement an RSP, although this report is alsointended for building officials, engineers, architects, building owners, emergencymanagers and interested citizens. The Supporting Documentation reviews the literatureand existing procedures for rapid visual screening.

§ NEHRP Handbook for the Seismic Evaluation of Existing Buildings (FEMA-178, 1992,227 pages). Prepared by the Building Seismic Safety Council, Washington, D.C.

The Handbook presents a nationally applicable method for engineers to identifybuildings or building components that present unacceptable risks in case of anearthquake. Four structural subsystems in which deficits may exist are identified:vertical elements resisting horizontal loads; horizontal elements resisting lateral loads;foundations; and connections between structural elements or subsystems. Fifteenstructural categories are defined for the evaluation of buildings by engineers. TheHandbook is formulated to be compatible with NEHRP Handbook of Techniques for theSeismic Rehabilitation of Existing Buildings (FEMA-172, 1992).

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§ NEHRP Handbook of Techniques for the Seismic Rehabilitation of Existing Buildings(FEMA-172, 1992, 197 pages). Prepared by the Building Seismic Safety Council,Washington, DC.

This handbook presents techniques for solving a variety of seismic rehabilitationproblems. Intended for engineers concerned with seismic rehabilitation of existingbuildings, the handbook identifies and describes seismic rehabilitation techniques for abroad spectrum of building types and building components (both structural andnonstructural). Most techniques are illustrated with sketches, and the relative merits ofthe techniques are discussed. Designed to be compatible with the NEHRP Handbookfor the Seismic Evaluation of Existing Buildings (FEMA-178, 1992), this publication isbased on a preliminary version prepared by URS/John A. Blume and Associates,Techniques for Seismically Rehabilitating Existing Buildings (FEMA-172, 1989).

§ Typical Costs for Seismic Rehabilitation of Existing Buildings: Volume 1: Summary,Second Edition (FEMA-156, 1994, approx. 70 pages); Volume 2: SupportingDocumentation, Second Edition (FEMA-157, 1995,approx. 102 pages). Prepared by theHart Consultant Group, Inc. Santa Monica, CA.

Typical Costs for Seismic Rehabilitation of Existing Buildings: Volume I: Summary,Second Edition provides a methodology that enables users to estimate the costs ofseismic rehabilitation projects at various locations in the United States. This greatlyimproved edition is based on a sample of almost 2100 projects. The data were collectedby use of a standard protocol, given a stringent quality control verification and a reliabilityrating, and then entered into a database that is available to practitioners. Asophisticated statistical methodology applied to this database yields costs estimates ofincreasing quality and reliability as more and more detailed information on the buildinginventory is used in the estimation process. Guidance is also provided to calculate arange of uncertainty associated with this process. The Supporting Documentationcontains an in-depth discussion of the approaches and methodology that were used indeveloping the second edition.

§ Benefit-Cost Model for the Seismic Rehabilitation of Hazardous Buildings. Volume 1: AUser's Manual (FEMA-227, 1992, approx. 68 pages); Volume 2: SupportingDocumentation (FEMA-228, 1992, approx. 62 pages); and Computer Software forBenefit-Cost Model for the Seismic Rehabilitation of Hazardous Buildings. Prepared byVSP Associates, Inc., Sacramento, CA.

The two benefit-cost models presented in this report are designed to help evaluate theeconomic benefits and costs of seismic rehabilitation of existing hazardous buildings.The single class model analyzes groups of buildings with a single structural type, asingle use, and a single set of economic assumptions. The multi-class model analyzesgroups of buildings that may have several structural types and uses. The User’s Manualpresents background information on the development of the benefit-cost model and anintroduction to the use of benefit/cost analysis in decision making. It reviews theeconomic assumptions of benefit-cost models, with and without including the value of

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life. The User’s Manual guides the user through the model by presenting synopses ofdata entries required, example model results, and supporting information. Sevenapplications of the models are presented: five of the single-class model; two of the multi-class model.

Supporting Documentation complements the User’s Manual by providing fourappendices that help the user understand how the benefit-cost models wereconstructed. The appendices include: 1) a review of relevant literature; 2) a section onestimating costs for seismic rehabilitation; 3) a compilation of tables for the Seattlebuilding inventory; and 4) some insights into the building rehabilitation of the nine citiesvisited during this project.

Computer Software to run the benefit/cost models is also available. The programs areon 3 ½" diskettes and can be used on IBM compatible personal computers.

§ Seismic Rehabilitation of Federal Buildings: A Benefit/Cost Model. Volume 1: A User’sManual (FEMA 255, 1994, approx. 158 pages); Volume 2: Supporting Documentation(FEMA-256, 1994, approx. 71 pages) and Computer Software for the SeismicRehabilitation of Federal Buildings. Prepared by VSP Associates, Inc., Sacramento, CA.

This User’s Manual and accompanying software present a second-generation cost-benefit model for the seismic rehabilitation of federal and other government buildings.Intended for facility managers, design professionals, and others involved in decisionmaking, the cost/benefit methodology provides estimates of the benefits (avoideddamages, avoided losses, and avoided casualties) of seismic rehabilitation, as well asestimates of the costs necessary to implement the rehabilitation. The methodology alsogenerates detailed scenario estimates of damages, losses, and casualties. The Manualdescribes the computer hardware and software required to run the program. It alsoexplains how to install the program, how to use Quattro Pro for Windows, and how toenter necessary data. A tutorial provides a fully worked example. Benefit/Cost analysesof eight federal buildings are included. The Supporting Documentation containsbackground information for the User’s Manual including information on valuing publicsector services, discount rates and multipliers, the dollar value of human life, andtechnical issues that affect benefit/cost analysis, such as seismic risk assessment andsensitivity analysis.

Computer Software to run the benefit/cost model is available on 3 1/2" diskettes and canbe used on IBM compatible personal computers with at least 386 CPU. The computermust also have Windows and Quattro Pro.

§ Establishing Programs and Priorities for the Seismic Rehabilitation of Buildings:Handbook (FEMA-174, 1989, 122 pages) and Establishing Programs and Priorities forthe Seismic Rehabilitation of Buildings: Supporting Report (FEMA-173, 1989, 190pages). Prepared by Building Systems Development, Inc. with Integrated DesignServices and Claire B. Rubin.

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These two volumes provide the information needed to develop a seismic rehabilitationprogram, with particular reference to establishing priorities. The Handbook is intendedto assist local jurisdictions in making informed decisions on rehabilitating seismicallyhazardous existing buildings by providing nationally applicable guidelines. It discussesthe pertinent issues that merit consideration, both technical and societal, and suggests aprocedure whereby these issues can be resolved. The Supporting Report includesadditional information and commentary directly related to sections in the Handbook:supporting documentation, annotated bibliographies, and reproductions of selected lawsand ordinances that are presented in summary form in the Handbook.

§ Financial Incentives for Seismic Rehabilitation of Hazardous Buildings - An Agenda forAction. Volume 1: Findings, Conclusions, and Recommendations (FEMA-198, 1990,104 pages); Volume 2: State and Local Case Studies and Recommendations (FEMA-199, 1990, 130 pages); and Volume 3: Applications Workshops Report (FEMA-216,1990, about 200 pages). Prepared by Building Technology, Inc., Silver Spring, MD.

The intent of these documents is to identify and describe the existing and potentialregulatory and financial mechanisms and incentives for lessening the risks posed byexisting buildings in an earthquake. Volume 1 includes a discussion of the methodologyused for these documents, background information on financial incentives, as well asfindings, conclusions and recommendations for use by decision makers at local, stateand national levels. Volume 2 includes detailed descriptions of the twenty case studiesthat were examined as part of this project. Volume 3 reports on workshops for thedevelopment of local agendas for action in seismic rehabilitation. It includes directionsfor convening additional workshops and teaching materials, which can be used in suchworkshops. This information is directed primarily to groups that are interested inplanning for local seismic mitigation in existing buildings who wish to convene aworkshop to initiate the process.

§ Development of Guidelines for Seismic Rehabilitation of Buildings - Phase 1: IssuesIdentification and Resolution (FEMA-237, November 1992, 150 pages). Prepared by theApplied Technology Council, Redwood City CA (ATC-28).

This report is intended to assist in the preparation of Guidelines for the SeismicRehabilitation of Existing Buildings. The report identifies and analyzes issues that mayimpact the preparation of the Guidelines and offers alternative as well as recommendedsolutions to facilitate their development and implementation. Also discussed are issuesconcerned with the scope, implementation, and format of the Guidelines, as well ascoordination efforts, and legal, political, social, and economic aspects. Issuesconcerning historic buildings, research and new technology, seismicity and mapping, aswell as engineering philosophy and goals are discussed. The report concludes with apresentation of issues concerned with the development of specific provisions for majorstructural and nonstructural elements.

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§ Interim Guidelines: Evaluation, Repair, Modification and Design of Steel Moment Frames(FEMA-267, 1995, approx. 248 pages). Prepared by the SAC Joint Venture,Sacramento, CA.

These Interim Guidelines apply to welded steel moment frame (WSMF) buildings andstructures that are subject to large inelastic demands from earthquakes. They areintended to provide practicing engineers and building officials with an understanding ofthe types of damage such structures may experience in strong earthquakes and thepotential implications of such damage. This publication provides recommendedmethods for evaluating, inspecting, and repairing existing damaged WSMF buildings, aswell as recommendations for designing and constructing new WSMF buildings andstructures for improved performance in future strong earthquakes.

§ Handbook for the Seismic Evaluation of Buildings – A Prestandard (FEMA-310, 1998,approx. 248 pages). Prepared by the American Society of Civil Engineers, Reston VA.

How to Order: FEMA publications can be obtained at no charge from:

FEMA Distribution CenterP.O. Box 2012

Jessup, MD 20794PHONE: 1-800-480-2520;

FAX: (301) 497-6378

B.5 Earthquake Engineering Research Institute

The Earthquake Engineering Research Institute (EERI) publishes a variety of documents relatedto earthquake safety, preparedness, and loss reduction. A partial list of EERI publications isprovided below.

§ Construction Quality, Education, and Seismic Safety. EF96-02

This white paper addresses a topic of critical importance to everyone involved indesigning, constructing, and inspecting buildings so they perform successfully in anearthquake. Recent earthquakes have shown that the construction and inspectionprocesses are responsible for a significant amount of unnecessary earthquake damage.The report examines the problem, focusing on the relationship between the education ofconstruction trades people, code enforcement personnel, and the earthquakeperformance of structures. The focus includes strategies to improve education of, andexisting training methods for, construction workers and building inspectors.

§ Expected Seismic Performance of Buildings. SP-10

Developed by the EERI ad hoc committee in order to help building owners, codeadministrators, and others involved in building maintenance programs understand howseismic design provisions and quality of construction affect earthquake performance.Focus on buildings in Seismic Zone 4 built to the recent 1991 Uniform Building Code

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(UBC), and on older unreinforced masonry buildings rehabilitated under the UniformCode for Building Conservation (UCBC).

§ Practical Lessons from the Loma Prieta Earthquake. LP-93

A report based on the proceedings of the symposium held in San Francisco, March 22-23, 1993. Edited by the National Research Council's Geotechnical Board, thepublication consists of keynote papers presented at the major sessions, and an overviewchapter that summarizes the principal lessons learned, as well as givingrecommendations to improve seismic safety and earthquake awareness in Californiaand other parts of the country vulnerable to earthquakes.

§ Public Policy and Building Safety, EERI Endowment Fund White Paper. EF96-01

This white paper has been written primarily for building officials and engineers involvedin incorporating social, economic, and political considerations in decisions about buildingsafety. It grew out of a concern that engineering design requirements often do notreflect a realistic understanding of many other issues important in their adoption. Thepaper is divided into four sections. Section I is a case study of the City of Los Angeles'recent experience in passing an inspection and repair ordinance for damaged steelframe buildings. Section II is a general discussion of the policy-making process.Section III is a checklist that summarizes the recommendations discussed in previoussection. Section IV provides suggestions for further reading for those who desire moretechnical backup.

§ Reducing Earthquake Hazards: Lessons Learned From Earthquakes. 86-02

Report prepared by a large, multidisciplinary group of earthquake professionals whoreviewed observations from many post-earthquake investigations. Disciplines involvedinclude geosciences, engineering, architecture and urban planning, and social sciences.The objectives of the publications are: to inform about advances; to promotecommunication; to detail lessons learned; and to target areas for future research.

§ Seismic Retrofit Policies: An Evaluation of Local Practices in Zone 4 and TheirApplication to Zone 3, PF92-1

The report is a result of six months research on California seismic retrofit policies with anattempt to develop recommendations for use in areas of moderate seismic hazard.

How to Order: EERI publications can be obtained from:

Earthquake Engineering Research Institute499 14th Street, Suite 320Oakland, CA 94612-1934PHONE: (510) 451-0905

FAX: (510) 451-5411

Proposition 122 Product 2.2Earthquake Risk Management: A Toolkit For Decision-Makers C-1

Appendix C: Earthquake Hazard

C.1 General

Earthquake risk has two basic components,hazard and vulnerability. The earthquakehazard is a quantification of the variousground effects at a specific site produced byearthquakes, and the likelihood that theseeffects will exceed certain levels. Moresimply stated, it is a representation of howhard the ground will shake, and how often itis likely to do so. Earthquake hazards aresite specific. That is, they are different ateach individual site, depending on the site’slocation and the properties of the groundbeneath the site. Earthquake vulnerability isa quantification of how much damage aconstructed facility is likely to experience,given that it is subjected to certain hazards.Again, more simply stated, vulnerability is arepresentation of how much damage islikely to occur when ground shaking of acertain level occurs. This appendixprovides background information onearthquake hazards, and the way in whichthey are quantified for purposes of riskevaluation. A later appendix providessimilar information on earthquakevulnerability.

C.2 Primary Earthquake Hazards

The primary effects produced byearthquakes, that result in damage toconstructed facilities are ground faultrupture and ground shaking. These are

described below, other secondary hazardsare described in the following section.

C.2.1 Ground Fault RuptureA fault is a weakened zone within the crustof the earth along which movement canoccur. It can be thought of as being muchlike a crack in the rock that forms the earth’scrust, and along which, the material oneither side can move in opposite directions.It is this movement, or slipping, of the earthalong these faults that produceearthquakes. When a fault slips, it is said torupture. The amount of motion that occursalong the fault and the length of faultinvolved in the rupture is dependent on thesize of the earthquake. Small earthquakesproduce fault ruptures over only a fewsquare meters of fault surface and includeonly a few millimeters of slip. Greatearthquakes, such as the 1906 SanFrancisco earthquake, can include rupturesof a fault that extend for hundreds ofkilometers with slippage between oppositefaces of the fault being as large as 10meters.

In most places, deep soil deposits cover therock, and therefore, it is usually impossibleto directly observe a fault. However, mostlarge earthquakes produce so muchmovement along the fault that the soiloverlying the rock is also forced to movewith the rock that supports it. When thisoccurs, the movement of the fault can bedirectly observed on the ground surface.

EARTHQUAKE HAZARD

Proposition 122 Product 2.2C-2 Earthquake Risk Management: A Toolkit For Decision-Makers

Depending on the orientation of the faultwith respect to the ground surface and thetype of slippage that occurs, the groundsurface features may consist of a crack thatruns along the ground surface; a steep cliff,sometimes called a scarp; or a widedepression termed a graben. When any ofthese features appears on the groundsurface, they are termed ground faultruptures.

Large magnitude earthquakes can producevery severe deformations of the earth’ssurface along the zone of ground faultrupture. Figure C-1 is a picture of a fenceline that crosses the San Andreas fault,north of San Francisco. The large offset

seen in this fence occurred during theearthquake of 1906, when the ground in thisarea moved nearly 4 meters. Figure C-2shows a scarp that occurred in Nevada in1954, in an earthquake known as the DixieValley earthquake. When ground faultruptures of the type and size shown in thesefigures occur, any structures constructedacross the zone of rupture will be forced tofollow the ground movement. It is almostimpossible to design most types ofstructures to resist these types of groundfault rupture without very severe damage.Therefore, the best way to avoid faultrupture is to avoid building directly over thetraces of known active faults, where groundfault ruptures are most likely to occur.

Figure C-1: Fault rupture along the San Andreas Fault, 1906 San Francisco earthquake(courtesy EQUIIS Photographic Database)

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Figure C-2: Fault rupture along the Dixie Valley Fault, 1954 Dixie Valley earthquake(courtesy EQUIIS Photographic Database)

Ground fault rupture is most likely to occuralong the faults that are most active. Thesefaults are generally well defined and theirtraces have been mapped by the CaliforniaDivision of Mines and Geology (CDMG) in aseries of maps known as Maps of Alquist-Priolo Earthquake Fault Zones ("SpecialStudies Zones" prior to January 1, 1994).

These maps show the locations of knownactive traces of faults in sufficiently largescale to allow individual streets and largerbuildings to be identified. They areavailable from the CDMG by calling (916)445-5716. A sample of such a map isshown in Figure C-3.

Figure C-3: Typical Alquist-Priolo Earthquake Fault Zone Map (courtesy CDMG)

Fault Trace

Alquist-Priolo EarthquakeFault Zone

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C.2.2 Ground ShakingAlthough fault rupture is the primary effectof an earthquake, ground fault ruptures aretypically limited in extent and therefore donot pose a risk to most facilities. However,the movement that accompanies faultrupture produces violent ground shakingthat radiates outward from the zone of faultrupture and through the ground fordistances of many miles. This groundshaking is the single largest cause ofearthquake damage.

The severity of ground shaking that occursat a site, during an earthquake, isdependent on a number of factors. Theseinclude the size of the earthquake, thedistance of the fault rupture from the site,the type and direction of movement thatoccurred along the fault, and the types ofsoils that underlie the site. In general, thecloser a site is located to the zone of faultrupture, the stronger and more intense willbe the ground shaking experienced by thesite. Ground shaking is a very complexwave form, having components of differentfrequency and amplitude (much like thesound from an orchestra). The soils at asite tend to act as filters on this wave form,amplifying components at some frequencieswhile attenuating components with otherfrequency content. Generally, soft soilstend to amplify those components of groundmotion that are most damaging to buildingstructures, while rock tends to de-amplifythese components.

As stated above, the farther a site is locatedfrom the zone of fault rupture, the lessintense the ground shaking experienced at

the site is likely to be. Also the larger anearthquake is, the more intense will be theground shaking produced, the longer it willlast, and the larger the distance over whichintense ground shaking will be transmitted.Very small earthquakes may not producenoticeable shaking at all. Moderatemagnitude earthquakes may produceground shaking that can be felt over adistance of a few square miles, for a periodof a few seconds. Large magnitudeearthquakes can produce ground shakingintense enough to cause damage toconstructed facilities for distances of morethan 100 kilometers from the zone of faultrupture and the shaking can last for up toseveral minutes.

The severity of ground shaking can becharacterized in a number of different ways.The most common way is through the useof an intensity reading. Intensity scalesmeasure the severity of earthquake groundshaking at a site through evaluation of theway people react to it and its effects ontypical types of structures such as chimneysand masonry buildings. Since the effects bywhich intensity is gauged are somewhatdependent on the quality of the effectedconstruction, this is a somewhat subjectivemeasurement. However, intensity is aneasy concept to understand, so despite thislimitation, it is still commonly used as ameasure of ground shaking severity, and isone of the most common measures used inrisk analysis. Several different intensityscales are in use around the world. In theUnited States, the most commonly usedintensity scale is the Modified Mercalli scale,shown in Table C-1.

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Table C-1

MODIFIED MERCALLI INTENSITY SCALE.

MODIFIED MERCALLI INTENSITY SCALE

I. Not felt. Marginal and long-period effects of large earthquakes.

II. Felt by persons at rest, on upper floors, or favorably placed.

III. Felt indoors. Hanging objects swing. Vibration like passing of light trucks. Duration estimated. May not berecognized as an earthquake.

IV. Hanging objects swing. Vibration like passing of heavy trucks; or sensation of a jolt like a ball striking the walls.Standing motor cars rock. Windows, dishes, doors rattle. Glasses clink. Crockery clashes. In the upper range of IVwooden walls and frames creak.

V. Felt outdoors; direction estimated. Sleepers wakened. Liquids disturbed, some spilled. Small unstable objectsdisplaced or upset. Doors swing, close, open. Shutters, pictures move. Pendulum clocks stop, start, change rate.

VI. Felt by all. Many frightened and run outdoors. Persons walk unsteadily. Windows, dishes, glassware broken,knickknacks, books, etc., off shelves. Pictures off walls. Furniture moved or overturned. Weak plaster and masonry Dcracked. Small bells ring (church, school). Trees, bushes shaken (visible, or heard to rustle).

VII. Difficult to stand. Noticed by drivers of motor cars. Hanging objects quiver. Furniture broken. Damage to masonry D,including cracks. Weak chimneys broken at roof line. Fall of plaster, loose bricks, stones, tiles, cornices (alsounbraced parapets and architectural ornaments). Some cracks in masonry C. Waves on ponds; water turbid withmud. Small slides and caving in along sand or gravel banks. Large bells ring. Concrete irrigation ditches damaged.

VIII. Steering of motor cars affected. Damage to masonry C; partial collapse. Some damage to masonry B; none tomasonry A. Fall of stucco and some masonry walls. Twisting, fall of chimneys, factory stacks, monuments, towers,elevated tanks. Frame houses moved on foundations if not bolted down; loose panel walls thrown out. Decayed pilingbroken off. Branches broken from trees. Changes in flow or temperature of springs and wells. Cracks in wet groundand on steep slopes.

IX. General panic. Masonry D destroyed; masonry B seriously damaged. (General damage to foundations.) Framestructures, if not bolted, shifted off foundations. Frames racked. Serious damage to reservoirs. Underground pipesbroken. Conspicuous cracks in ground. In alluviated areas sand and mud ejected, earthquake fountains, sandcraters.

X. Most masonry and frame structures destroyed with their foundations. Some well-built wooden structures and bridgesdestroyed. Serious damage to dams, dikes, embankments. Large landslides. Water thrown on banks to canals,rivers, lakes, etc. Sand and mud shifted horizontally on beaches and flat land. Rails bent slightly.

XI. Rails bent greatly. Underground pipelines completely out of service.

XII. Damage nearly total. Large rock masses displaced. Lines of sight and level distorted. Objects thrown into the air.

Source: Richter, C.F. Elementary Seismology. San Francisco CA: W. H. Freeman Co., 1957.Note: To avoid ambiguity, the quality of masonry, brick, or other material is specified by the following lettering system. (This

has no connection with the conventional classes A, B, and C construction.)

Masonry A. Good workmanship, mortar, and design; reinforced, especially laterally, and bound together by usingsteel, concrete, etc.; designed to resist lateral forces.Masonry B. Good workmanship and mortar; reinforced, but not designed to resist lateral forces.Masonry C. Ordinary workmanship and mortar; no extreme weaknesses, like failing to tie in at corners, but neitherreinforced nor designed to resist horizontal forces.Masonry D. Weak materials, such as adobe; poor mortar; low standards of workmanship; weak horizontally.

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For a given earthquake, a wide range ofdifferent intensities of ground shakingoccurs, with the most intense motion beingexperienced near the site of fault rupture,and on deposits of soft soils, as previouslydescribed. Following the occurrence of adamaging earthquake, the USGS typicallyplots a map showing the distribution of

different intensities of ground motion overthe affected region. Figure C-4 is theintensity map produced following the 1989Loma Prieta earthquake. Study of thesemaps allows estimates of probableintensities of ground motion at different sitesin future earthquakes, to be estimated.

Figure C-4: Isoseismal map for the 1989 Loma Prieta earthquake (courtesy USGS)

Shaking Intensity(MMI)

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Although intensity is a useful measure ofground shaking severity for the purpose ofrisk analysis, it is not particularly useful forengineering purposes. In order to quantifythe effects of earthquake ground shaking forpurposes of structural analysis and design,engineers prefer to characterize groundshaking by the strength of groundaccelerations, velocities and displacements,and the frequency content of the waves thattransmit this motion. Engineers commonlyused a tool, known as a response spectrum,to depict these quantities. The responsespectrum is a plot that relates how hardstructures having specific dynamiccharacteristics will shake, when subjected toa specific ground motion. Important groundmotion parameters that may be obtainedfrom a response spectrum, and which areoften used by engineers in characterizingground motion include: peak ground andspectral response accelerations, peakground and spectral response velocity, andpeak ground and spectral responsedisplacements.

C.3 Secondary Hazards

Ground fault rupture and ground shakingare the primary earthquake-induced sitehazards. Secondary hazards includeseveral types of potential ground failureincluding liquefaction, lateral spreading,land sliding and compaction. These aredescribed in the sections below. In order toaccurately assess whether a site issusceptible to these secondary hazards,site specific geotechnical investigation istypically required. This may includeobtaining soil samples, by drilling borings,and analyzing the soil in testinglaboratories. However, CDMG has recentlypublished a series of maps known as “Mapsof Seismic Hazard Zones,” that indicate inan approximate manner the generalsusceptibility of different regions to theseground failures. One such map is shown inFigure C-5. If reference to such mapsindicates significant potential for one of theground failures described below, ageotechnical engineer should be retained tomore accurately assess the real significanceof this hazard, on a site-specific basis.

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Figure C-5: Typical Seismic Hazard Zone Map (courtesy CDMG)

C.3.1 LiquefactionLiquefaction is a type of ground failure thatcan occur on sites underlain by deposits ofloose sands or silts, with a high water tablepresent. Under the action of strong groundshaking, loose sand and silt soils becomecompacted and more dense. Essentially,the motion induced by the ground shakingtends to sift these materials, allowingparticles to fill in the voids between adjacentparticles. If this densification occurs insaturated soils, as the soil particles fill in thevoids between particles this forces out thewater which occupied that space. Thedisplaced water generally rises to theground surface. Under severe groundshaking, this effect can be very severe,

creating enough pressure in the rising waterto cause large geysers of muddy water tobe ejected from the ground.

When liquefaction occurs on a site, it canaffect structures in several ways. First, therejection of water from the soils and therising of this water to the ground surfacecan cause a quick sand like condition, inwhich soil supported foundations canexceed the temporary bearing strength ofthe soil, and in which buried utilities can become buoyant and float to the surface. Thequick sand condition can result in localsettling and tilting of foundations withsecondary damage occurring to thesupported structures. This effect can bemade more sever through the ejection of

Shaded areas indicatewhere there is potential of

ground failure duringsevere ground shaking.

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sand materials, in the geysers thatliquefaction creates. As sand and siltmaterial is ejected from the ground surface,this creates voids in the ground beneath thesurface, which leads to further settlement ofthe ground and ground supportedstructures.

Although liquefaction is a relatively rarephenomena, it can cause spectaculardamage to structures. Figure C-6 is aphotograph of several large apartmentbuildings in Japan, that suffered extremetilting due to liquefaction that occurred in the

1964 Nigaata earthquake. Construction ondeep foundations, such as piles and piers,tends to be more resistant to the effects ofliquefaction than are structures supportedon shallow spread footing foundations. Onsites where liquefaction potential representsa significant threat to existing construction,the risk can be reduced through a variety ofground improvement techniques. Theseinclude injection of chemical stabilizingmaterials into the liquefaction susceptiblesoils, and installation of dewateringsystems.

Figure C-6: Apartment buildings damaged by liquefaction, 1964 Nigaata earthquake(courtesy EQUIIS Photographic Database)

C.3.2 Lateral SpreadingLateral spreading is a secondary effect ofsoil liquefaction. When liquefaction occursin soils that are on a sloping surface, or areadjacent to an excavation or embankment,the liquefying soils can flow downhill under

the force of gravity. This typically results inthe formation of characteristic fissures in thesoils running parallel to the open face, orembankment edge.

Lateral spreading can also be extremelydestructive of structures, including

EARTHQUAKE HAZARD


structures supported on pile foundations.As the ground flows, it tends to drag with it,any structures that are supported on orwithin it. Since the displacement caused bythese flows is typically highly non-uniform,

these movements can literally rip structuresapart. Figure C-7 is a picture of a bridgethat was destroyed by lateral spreading inan earthquake in Costa Rica, in 1991.

Figure C-7: Bridge Destroyed by Lateral Spreading, 1991 Limón, Costa Rica earthquake(courtesy EQE International, Inc.)

C.3.3 LandslidingEarthquake-induced landslides are oftentriggered in areas of steep terrain. Most areminor and cause only local damage.However, very large earthquakes cantrigger catastrophic landslides. Forexample, a large earthquake off the coast ofPeru in 1971 triggered a landslide high inthe Andes Mountains, which buried the townof Ungay, killing 20,000 people. If alandslide occurs underwater or falls into aclosed body of water, it can cause atsunami or seiche, which locally can causeconsiderable damage. A landslide-induced

seiche destroyed the town of Valdez in 1964during the great (Mw 9.2) Prince WilliamSound, Alaska earthquake.

C.4 Quantifying Seismic Hazards

Small magnitude earthquakes, that producelow intensity effects occur very frequently,while great earthquakes, that produce veryintense and destructive earthquake effectsoccur very infrequently. In order torealistically assess the seismic risk to adevelopment (community, agency orbusiness) it is necessary to estimate theprobability that hazards of given severity will

EARTHQUAKE HAZARD


be experienced by the development. Therisk of damage or loss can then becomputed as the product of the probabilitythat earthquake effects of given severity willoccur and the probable loss, given thatthese earthquake effects are experienced.For example, if it is known that there is a10% chance in the next year that MMI VIIIground shaking will be experienced, andthat if MMI VIII ground shaking isexperienced a financial loss of $100 millionwill occur, then the risk has been defined asbeing a 10% chance that a loss of $100million will occur.

The probability that hazards of givenseverity will be experienced is typicallyrepresented graphically in the form of ahazard curve. A typical hazard curve isshown in Figure C-8. These curves can beused to estimate the probability thatearthquake ground shaking (or other

hazards) will be experienced at a site, withina defined period of years. Thus, in Figure 8,it can be seen that the site for which thiscurve has been developed would beexpected to experience Modified MercalliIntensity VI ground shaking approximately 1time every 10 years, Modified MercalliIntensity VIII ground shaking one time every100 years, and Modified Mercalli Intensity IXground shaking every 1,000 years or so.Alternatively, this data can also be read tomean that in any year, there isapproximately a 10% chance ofexperiencing MMI VI ground shaking at thesite, a 1% chance of MMI VIII and a 0.1%chance of experiencing MMI IX groundshaking. Such data can then be used toestimate probable losses over a period oftime.

Hazard Curve

1

10

1001000

10000

100000

0 1 2 3 4 5 6 7 8 9 10

Modified Mercalli Intensity

Ret

urn

Per

iod

- Y

ears

Figure C-8: Typical Seismic Hazard Curve

Hazard curves are typically developed bygeotechnical engineers and seismologists,using specialized software that can perform

the complex calculations involved.Generally, in order to develop a hazardcurve for a site, the seismologist or

EARTHQUAKE HAZARD


geotechnical engineer needs to identify allof the potential earthquake sources in aregion that could cause ground shaking (orother hazards) at the site, determine thedistance of these sources from the site,estimate the return period or probability ofdifferent size earthquakes on each of thesesources, then calculate the probableintensity of ground shaking at the site,presuming that an earthquake of givenmagnitude occurs on each of these sources.

The USGS has performed such hazardcalculations, on a regional basis, for siteslocated around the United States. Thisdata, which is available on the world wideweb, through the USGS, can be used toperform preliminary loss estimates in lieu ofretaining a geotechnical engineer to developsite specific hazard data.

The sections below describe the basicfactors and procedures used in hazardcalculation.

C.4.1 Earthquake SourcesMost earthquakes occur as a result ofstrains that build up in the earth’s crustunder the influence of gravitational forces.Rather than being solid, the earth’s crust isactually quite fractured and as shown inFigure C-9, is actually composed of a series

of individual tectonic plates. These platesare very large. One of them underlies mostof North America while another underliesmuch of the Pacific Ocean. Under theinfluence of forces created by the rotation ofthe earth, the tectonic plates tend to movewith respect to each other. Generally, eachof the plates tends to spin in a counter-clockwise direction, but in addition, someplates are growing outward, from areas ofsub-sea volcanic activity, while others areshrinking as they dive beneath the edges ofneighboring plates. The relative motion ofeach these plates with respect to theadjacent plates is very slow, but constant.For example the edge of the Pacific Platewhich lies along the western edge of theState of California tends to move about 2-1/2 inches (60 mm) relative to the NorthAmerican plate to its east. Locally, wherethe plates abut each other, they tend tointerlock preventing movement fromoccurring. As a result, over a period ofmany years, the plates build up very largestresses. Eventually, the stresses within therock build up to a point where they exceedthe strength of the rock. When thishappens, a rupture occurs, allowing theedges of the plate that were interlocked torapidly snap forward to a new displacedposition, releasing a portion of thepreviously accumulated strain and stress, inthe form of energy, that radiates through theground as ground shaking.

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Figure C-9: Map of Tectonic Plates (courtesy USGS)

Earthquakes nearly always occur alongfaults, as this is where the earth’s crust isweakest, and where the rupture processcan most readily occur. The largest andmost active faults, tend to be located at, orclose to the boundaries between thetectonic plates. The San Andreas fault, forexample, the source of the great 1906earthquake in northern California, and asimilar sized event centered near FortTejon, in southern California, in 1857, runsalong the boundary between the Pacific andNorth American plates. Typically, theearth’s crust adjacent to such plateboundaries is highly fractured and broken,due to past earthquake activity andtectonically induced stresses. As a result, anumber of large active faults are typicallypresent adjacent to plate boundaries. Thisis the case in coastal California as well.

The path of a fault, along the groundsurface is known as its trace. The traces ofhighly active faults, are usually quiteevident, due to the unique ground featuresthat constant movement along these faultshave created. The San Andreas fault, forexample, has created a deep rift valleyalong much of its length, that is clearlyvisible from the air (See Figure C-10).Other faults are evident because of thesharp faces of hillsides that were created byconstant uplift of the ground along the fault.Frequently, it is possible to detect the tracesof active faults by observing the courses ofrivers and streams, whose courses areoften offset along the fault trace, by pastearthquake activity.

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C-10: Aerial view of the San Andreas Fault, near Coachella Valley (courtesy USGS)

Not all faults are equally active and manyfaults have no obvious traces on the groundsurface. Such faults are sometimes termedhidden or undiscovered faults. Most faultstend to have a set activity rate. That is, theytend to produce earthquakes of a givensize, with some regularity over a giveninterval of years. The San Andreas fault forexample, is thought to produce earthquakeslike the great 1906 event, approximatelyone time every 300 years or so. The moreactive a fault is, the more likely that it hasproduced surface effects that have allowed

it to be mapped. Future earthquakes aremost likely to occur along these knownhighly active faults. However, earthquakescan also occur along other less active faults,that are not presently known. This hashappened several times in California inrecent years. The 1971 San Fernando,1987 Whittier Narrows, and 1994 Northridgeearthquakes all occurred on previouslyunknown faults. Figure C-11 is a mapshowing the major known active faultsystems in California.

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Figure C-11: Map of major active fault zones within California and Nevada (courtesy USGS)

To account for the possible presence ofunknown or unmapped faults, a seismichazard assessment will incorporatebackground seismicity in addition to knownfaults as potential sources of earthquakehazard. Background seismicity definesgeographically diffuse earthquake sourceswith magnitudes ranging from the smallestof interest, typically Mw > 5, up to about Mw

7. The frequencies of these earthquakesare calculated from the observed rates ofhistoric earthquakes.

Figure C-12 shows the location of majorearthquakes that have occurred in Californiasince 1769. Careful inspection of thisfigure, and comparison with Figure C-11,

indicates that the majority of theseearthquakes have occurred along known,mapped faults, and in a particular along theSan Andreas system, comprised of the SanAndreas fault itself and also its splay faults.In northern California the San Andreas faultsystem includes the San Andreas, Hayward,and Rodgers Creek faults. In southernCalifornia, this fault system is made up ofthe San Andreas, San Jacinto, Imperial, andWhittier-Elsinore faults. Most, but not all ofthe relevant movement between the Pacificand North American plates is relieved byslip along these faults. However, significantslip also occurs along other faults asindicated in Figure C-12.

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Figure C-12: Map of Major California Earthquakes since 1769

C.4.2 Quantifying Earthquake SizeThe size of an earthquake is typicallycharacterized by its magnitude. Magnitudeis actually a measurement of the amount ofenergy released by a fault rupture during anearthquake and is directly related to thelength and depth of the fault that ruptured,the amount of displacement along the fault,and the strength properties of the rock thatbreak during the earthquake. Theearthquake’s magnitude is estimated bymeasuring the amplitude of seismic waves

recorded on seismograms at stationsdistributed around the earthquake rupture,accounting for the distance between therecording site and the rupture and thegeologic conditions beneath the site. It isimportant to keep in mind that groundmotions from any earthquake may rangefrom high to low depending on the locationwith respect to the earthquake rupture andthe specific geologic conditions. Therefore,any one measurement of the ground motionmay give an indication of the magnitude, butis generally not enough information to

EARTHQUAKE HAZARD


constrain the size of an earthquake rupture.The earthquake’s magnitude may only bededuced by recording many seismogramssurrounding the earthquake to get anindication of the dimensions of the rupture.This is why the news media often givesdifferent reports of the magnitude of anearthquake. Initial estimates of earthquakemagnitude are typically based on thereadings obtained from a relatively fewinstruments. As more instrumental databecomes available, it is possible for earthscientists to improve their estimates, andmake them more accurate. Several weeksor months after the earthquake, earthscientists can also map the aftershockpatterns and surface displacements thathave occurred which give an independentindication of the dimensions of theearthquake rupture and, therefore, themagnitude of the earthquake.

A number of different magnitude scaleshave been developed to estimate the size ofthe earthquake. The more common scalesare the Richter, local, body-wave, surface-wave, and moment magnitudes. Thesescales are based on various measurementsof the seismic waves. Especially for largerearthquakes, these magnitudes may differfrom one another. The moment-magnitudescale (MW) is the most physically based,because it is directly related to the rupturedimensions and displacement on the fault.Geologic and seismic observations have ledto the conclusion that larger earthquakestypically rupture a larger section of a fault,cause the ground to vibrate longer, andradiate more energy than smallerearthquakes.

C.4.3 Recurrence RatesFor many faults of the San Andreas system,there is sufficient paleoseismic information

to characterize the repeat time of largeearthquakes (called characteristicearthquakes). Knowing the repeat time andthe date of the last large earthquake on thefault, scientists can determine where thefault is in its earthquake cycle, the timeperiod between large earthquakes. Thisallows them to calculate the probability thatthe next large earthquake on the fault willoccur by a specific date in the future. Afault with an elapsed time since the lastlarge earthquake approaching the averagerepeat time has a relatively high probabilityof producing another large earthquake inthe near future. In contrast, a fault with anelapsed time much smaller than the repeattime of large earthquakes have relativelylow probabilities of producing another largeearthquake soon.

The southern segment of the Hayward faultis a prime example of a fault that isrelatively late in its earthquake cycle. Thelast large earthquake on this fault was in1836 (162 years ago) and largeearthquakes are expected to occur on thisfault every 210 years or so. Severalsegments of the San Andreas Fault closestto Los Angeles are also late in theirearthquake cycle and pose a higher thanaverage hazard compared to their long-termpotential. San Bernardino is particularlyvulnerable in the near-future, since both thenearby San Andreas and San Jacinto Faultsare late in their cycle.

C.4.4 Attenuation RelationshipsA mathematical relationship between themagnitude, distance from the fault to aparticular site, and the intensity of groundshaking likely to occur at the site is knownas an attenuation relationship. Someattenuation equations also take otherfactors into account, such as site soil

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characteristics, the type of faulting, and theregional geologic characteristics. Suchattenuation equations are used to estimatethe expected level of ground shaking fromvarious postulated earthquakes whendeveloping a hazard curve.

Attenuation equations are derived bySeismologists by performing statisticalanalyses of data bases of recorded groundmotions from past earthquakes. Attenuationrelationships can not provide “exact”predictions of the ground shaking intensityat a site from a specific earthquake.However, they can be used to provide a“best estimate” of the likely intensity of suchground shaking, together with an indication,based on the statistical scatter present inthe data base, as to how much more or lessintense the ground shaking might actuallybe than the indicated amount.

The shaking parameters that are mostcommonly estimated by such an equationare the Modified Mercalli intensity (MMI),the peak ground acceleration (PGA), andthe response spectral acceleration (Sa). Inmany urbanized areas, such as California,strong ground shaking is recorded onaccelerographs. Such recordings representa quantitative measure of the groundshaking in terms of the acceleration of theground as a function of time. It is theserecordings that are used to developattenuation relationships.

C.4.5 Site AmplificationThe amplitude, duration, and frequencycontent of the ground shaking at a givenpoint on the Earth’s surface is stronglyaffected by the geologic materials thatunderlie the site. Deeper, softer materialswill tend to increase the amplitude, duration,and predominant period of the groundmotion, except possibly at high frequenciesas noted below. High levels of groundshaking on soft soils, such as Bay mudalong the margins of San Francisco Bay,will strongly attenuate high-frequencyground shaking through nonlinear soilresponse, which can actual result in de-amplification. However, this same nonlinearbehavior will generally amplify the longer-period components of ground motion inthese same deposits.

The best means of identifying areas whereground shaking is likely to be amplified bythe underlying soils is to determine theaverage shear-wave velocity in the upper 30meters of the deposit (Vs,30). This velocitycan be used directly to determine theamplification potential of the deposit bymeans of defined amplification factors, orsuch measurements can be correlated withgeologic map units to identify those unitswith given ground-shaking amplificationcharacteristics. This latter effort is currentlybeing done for all of California by the CDMGunder the auspices of the 1990 SeismicHazards Mapping Program.

Proposition 122 Product 2.2Earthquake Risk Management: A Toolkit For Decision-Makers D-1

Appendix D: Earthquake Vulnerability

D.1 General

Earthquake vulnerability is a measure of thedamage a constructed facility is likely toexperience given that it is subjected toground shaking, or other hazards, ofspecified intensity. The dynamic responseof a structure to ground shaking is a verycomplex behavior that is dependent on anumber of inter-related parameters that areoften very difficult, if not impossible, toprecisely predict. These include: the exactcharacter of the ground shaking that thebuilding will experience; the extent to whichthe structure will be excited by and respondto the ground shaking; the strength of thematerials in the structure; the quality of

construction and condition of individualstructural elements; the interaction of thestructural and non-structural elements of thebuilding; the weight of furnishings andcontents present in the building at the timeof the earthquake; and other factors. Mostof these factors can be estimated, but neverprecisely known. As a result, it is typicallynecessary to define vulnerability functionsfor buildings within levels of confidence.Figure D.1 is a typical vulnerability curve fora hypothetical facility, relating projecteddamage to ground shaking intensity, withlevels of confidence expressed.

Vulnerability Function

0%

20%

40%

60%

80%

100%

V VI VII VIII IX X

Modified Mercalli Intensity (MMI)

% D

amag

e

90% Chance of Exceedance

Median Confidence10% Chance of Exceedance

Figure D-1: Typical Vulnerability Function

EARTHQUAKE VULNERABILITY

Proposition 122 Product 2.2D-2 Earthquake Risk Management: A Toolkit For Decision-Makers

In Figure D-1, damage is expressed on apercentage scale, ranging from none (0%)to complete (100%), as a function of aground motion parameter, in this case,Modified Mercalli Intensity (MMI). Threeseparate curves are shown in the figure.The middle curve, represents the medianconfidence level estimate. This representsa best estimate of the probable damage thatwould be experienced by the facility at agiven ground motion intensity, and given theamount of data that was available uponwhich to form the estimate. The actualdamage experienced by the facility couldeither be less or greater than that indicatedby the median curve. In fact, it is equallylikely that actual damage would be less thanthe median estimate as it is that it would begreater than the median estimate.

The upper curve in the figure is labeled asbeing associated with a 10% chance ofexceedance. This means that there is onlya 10% chance that the actual damageexperienced by the facility would be greaterthan indicated by the curve and a 90%chance that it would be less. Similarly, thelower curve is indicated to represent a 90%chance of exceedance, indicating that thereis a 90% chance that damage would be lessthan indicated by this lower curve, and onlya 10% chance that it would be greater. Thisdifference between the lower, median andupper curves is a measure of theuncertainty inherent in the vulnerabilityestimate. Almost all vulnerability estimateshave significant levels of uncertaintyassociated with them. In large part, this isbecause the estimates are made withoutperforming detailed studies of theconstruction, condition and behavior of thefacility. Often, vulnerability estimates aremade based on visual observations, andwithout referencing drawings or performingengineering calculations. To the extent that

more detailed study of the construction,condition and behavior of the structure isperformed, through review of site specificsoils data, the construction documents forthe building, and the quantification ofstructural characteristics with calculation, itis possible to reduce this uncertainty andmake the estimates more precise.

Generally, development of vulnerabilityestimates requires the specializedknowledge of a structural engineer, expertin earthquake engineering. Three basicmethods are commonly used by suchengineers to develop vulnerabilityestimates. One of these is termed anexperience data approach, the second, anengineering approach, and the third acombined approach. The experience dataapproach is based on the fact that certainclasses of constructed facilities tend toshare common characteristics and toexperience similar types of damage inearthquakes. A series of standardvulnerability functions have been developedover the years for these classes ofbuildings. When using the experience dataapproach, it is only necessary to identify theclass of construction that the facility may becharacterized as, and then to makereference to one of these standardvulnerability functions. A commonly usedreference for such standardized vulnerabilitymatrices is ATC-131. Loss estimates thatare made using this approach tend to behighly uncertain and are more valid whenused to evaluate the risk of large portfoliosof facilities, than for individual facilities. Thisis because when applied to large portfolios

1 Applied Technology Council. Standardized LossEstimation Methodology for Buildings inCalifornia. Report No. ATC-13, Redwood City,CA, 1985.



of facilities, the uncertainties associatedwith estimation of the vulnerabilities of theindividual components of the portfolio tendto balance out. A useful reference forperforming vulnerability estimates ofbuildings using the experience dataapproach is the publication ATC-212.

In the engineering approach, engineeringcalculations are used to quantify the amountof force and deformation induced in thefacilities by the earthquake ground shaking,and to compare these with the capacity ofthe structure to resist these forces anddeformations. Engineered estimates ofvulnerability also tend to have significantuncertainties associated with them, becauseit is very difficult to accurately quantify theprecise strength and deformation capacityof the structure and also to predict itsresponse.

The combined approach, in which bothengineering calculations and experiencedata are used to estimate vulnerability is theleast uncertain in that it allows calibration ofthe engineering calculations with theobserved behavior of actual structures.This is the approach most commonly usedwhen knowledgeable structural engineersperform either vulnerability estimates orupgrade designs for facilities. A number ofstandardized methodologies have beendeveloped in recent years to guideengineers through this process. The mostrecently published methodologies may be

2 Applied Technology Council (ATC). Rapid VisualScreening of Buildings. Report. No. ATC-21,Redwood City, CA, 1987.

found in FEMA-2733, FEMA-310,4 and ATC-405.

The following sections describe the intent ofthe building codes, with regard to seismicperformance, and generalized performancedata for typical classes of construction.

D.2 Buildings and Structures

D.2.1 Building CodesThe building code sets minimum criteria forthe structural design of buildings. For manyyears, building codes enforced by localgovernments in California have been basedon the Uniform Building Code (UBC)6, amodel building code developed by theInternational Conference of BuildingOfficials. The first edition of this code waspublished in 1927 and updated editions ofthis code have been published on a three-year cycle, since. Since, 1991, Californiacities and counties have been required toadopt the same edition of this code, as isadopted by the State of California. The

3 Federal Emergency Management Agency (FEMA).NEHRP Guidelines for Seismic Rehabilitation ofBuildings. Report No. FEMA-273. Washington,D.C., 1997.

4 Federal Emergency Management Agency (FEMA).Standard Methodology for Seismic Evaluationof Buildings. Report No. FEMA-310. FederalEmergency Management Agency. Washington,D.C., 1998.

5 Applied Technology Council (ATC). Methodologyfor Seismic Evaluation and Upgrade ofReinforced Concrete Buildings. Report No. ATC-40. Redwood City, CA, 1987.

6 International Conference of Building Officials(ICBO). Uniform Building Code . Whittier, CA,1997.



State has typically adopted the most recentedition of the UBC, within about a year of itsfirst publication. However, prior to 1991, thebuilding code enforced by many cities wasoften quite out of date. With the publicationof the 1997 edition of the UBC, theInternational Conference of BuildingOfficials (ICBO) ceased publication of modelcodes. Future codes in California are likelyto be based on the International BuildingCode, a model code published by theInternational Code Council, a consortium ofthe International Conference of BuildingOfficials, the Building Officials and CodeAdministrators International, and theStandard Building Code CongressInternational.

The earthquake design provisions containedin the UBC have traditionally been based onrecommendations developed by theStructural Engineers Association ofCalifornia (SEAOC). Theserecommendations have adopted a seismicdesign philosophy intended to protect lifesafety, but allow for some structural andpotentially significant nonstructural damagefor earthquake levels as severe as can beexpected at some sites in the most activeseismic regions of California. Theprovisions are based on the observedperformance of real structures in pastearthquakes. After each major earthquake,engineers investigate the types of damagethat occurred and develop improvements tothe code to allow it to meet its basicperformance criteria, more reliably. Thecode implicitly sets forth the following three-level earthquake performance criteria:

1. Resist minor levels of earthquakeground motion with no structuraldamage and with only minordamage to nonstructural features

such as glazing, architecturalfinishes, and suspended ceilings.

2. Resist moderate levels ofearthquake ground motion withminor repairable structural damage,and possibly some extensivenonstructural damage.

3. Resist major levels of earthquakeground motion, which has anintensity equal to the strongest eitherexperienced or forecast for thebuilding site, without collapse butpossibly with some major structuralas well as extensive nonstructuraldamage.

Buildings designed in accordance with theUBC are anticipated to experiencesignificant damage and loss, when affectedby a major earthquake. Further, the designprovisions of the UBC primarily addressdamage caused by ground shaking. Theydo not address the effects of other sitehazards, such as liquefaction, consolidation,landslides, and ground-surface rupture.Any of these types of ground failures canresult in excessive damage and potentially,even collapse of buildings meeting the codecriteria. Major changes to the building codecriteria have been adopted following eachmajor earthquake that has affectedCalifornia including the 1994 Northridge,1989 Loma Prieta, and 1971 San Fernandoevents.

D.2.2 Lateral Force-resisting SystemsBuildings are designed to resist wind andearthquake forces through the provision of alateral force-resisting system. The lateralforce-resisting system for a building typicallycomprises a combination of vertical andhorizontal elements and their connections.



Typical vertical elements are frames (beamsand columns), braces, and walls. Typicalhorizontal elements are roofs, floors, andbraces. Horizontal elements are usuallytermed diaphragms. Details of how theseelements are constructed andinterconnected are critical to a building’sseismic performance.

D.2.3 Typical ConfigurationDeficiencies

A building’s configuration, that is its basicshape, can have a significant impact on theway it performs in an earthquake and thereare many geometric features of a buildingthat can result in poor structuralperformance. Some of the most importantof these are soft and weak stories, torsionalsystems, and discontinuous elements. Softand weak stories occur in buildings whenthere are fewer walls or frames, or tallerfloor to floor heights in the first story, than instories above. Unfortunately, becausearchitects like to design buildings with highceilings and airy spaces at the first story,this is a very common condition. A buildingis said to have a torsional system if in thelayout of the vertical elements of the lateralforce-resisting system are arranged suchthat instead of just shaking back and forth,the building tends to twist when affected byground shaking. This is a very commondefect in buildings located on a corner,which will often have solid walls on twosides and open walls on the street side.Discontinuous elements are another seriousproblem. An example of a discontinuouselement, is a solid wall that rises from thesecond story through the roof level, and issupported on columns at the first story.Such configurations can be problematicbecause the strong elements above canliterally crush the weaker elements below.

D.2.4 Performance of Typical BuildingTypes

D.2.4.1 Wood Frame BuildingsWood frame structures are typically fourstories or less in height. The most commontypes of wood frame construction consist ofrepetitively framed wood joists, supportingplywood or straight board flooring, andsupported by light framed walls. The wallsare typically comprised of 2x4 vertical studs,sheathed with various structural panels,such as plywood, or architectural finishessuch as plaster or gypsum board. Most low-rise residential construction in California isof this type, as are many smallercommercial buildings.

Wood-frame construction can be supportedon a slab-on-grade, a concrete or masonrystem wall, or on a wood cripple wallfoundation. Stem walls are concrete ormasonry foundations that project above theground. Cripple walls are short stud walls(varying from a few inches in height toseveral feet) between the foundation andthe first floor level. Both are used to elevatethe first floor above the ground and provideventilation under the building. Many olderwood frame buildings have no foundations,or weak foundations constructed ofunreinforced masonry or poorly reinforcedconcrete.

When properly designed and constructed,wood frame buildings have performed verywell in strong earthquakes. This is becausethese structures tend to be light andtypically have many walls providingsignificant strength, stiffness, andredundancy. Buildings with heavy finishes,such as masonry veneers on perimeterwalls, or slate or clay tile roofs tend to beheavier, and more susceptible to damage.



In smaller, single-story structures, the mostcommon seismic deficiency consists of alack of adequate anchorage of the buildingto its foundation. This can result in abuilding sliding off of its foundation, resultingin extensive damage. This vulnerability ismost common in structures constructedprior to about 1940. Another commondeficiency in these small buildings is a lackof adequate bracing of the cripple walls,located just above the foundation. Poorlybraced cripple walls include those with let-inbracing, horizontal wood siding, and stucco(no plywood beneath). If the cripple wall ispoorly braced, the structure may roll off thecripple studs below the first floor and fall tothe foundation. Such collapses haveoccurred in many older structures.

Older, large buildings, and buildings withtwo or more stories, tend to be more of aseismic concern. In such structures, thestucco, plaster and gypsum materialstraditionally used as wall sheathing do nothave adequate strength to resist the largeforces induced by strong ground shaking.Extensive damage to plaster, stucco, andgypsum board finishes is common. After anearthquake, older buildings are oftenobserved to be leaning a significant amount,and doors and windows in these structuresmay either become jammed or cracked.

In the 1994 Northridge earthquake, anumber of multistory apartment buildings,constructed with garages at the first story,collapsed. Similar damage was observed inthe 1989 Loma Prieta earthquake in theMarina District in San Francisco. The largegarage doors resulted in a weak, soft-storycondition.

Deteriorated condition can be a commoncause of poor earthquake performance ofwood structures. Wood framing can

deteriorate as a result of infestation fromtermites and other pests. Repeatedexposure to moisture, followed by drying,can lead to a condition known as dry rot.Similarly, poor construction practice thatleaves the structure in a weakenedcondition can contribute to failures.

Unreinforced masonry chimneys present acommon life-safety concern in woodbuildings. They are often inadequately tiedto the building and therefore fall whenstrongly shaken. Chimneys with tallprojections above the roof can break at theroof line and topple through the roof or ontothe ground. Masonry veneers can alsorepresent a significant hazard. In olderbuildings, the veneer can either beinsufficiently attached, or have poor qualitymortar, which often results in peeling off ofthe veneer during moderate or strongground shaking. Corrosion of veneer tieshas also been observed to be a problem.

Often, wood-frame buildings can be easilyand economically retrofitted to reduceseismic vulnerability. Common retrofittechniques include providing anchorage tothe foundation, providing supplementalplywood sheathing for selected shear walls(and cripple walls) and diaphragms, andproviding holddown hardware at the ends ofslender shear walls.

D.2.4.2 Unreinforced Masonry BearingWall Buildings

Unreinforced masonry bearing wallconstruction, commonly termed URM, isone of the oldest types of construction foundin California. In this type of construction,the perimeter walls, which are typicallyconstructed of multiple layers (wythes) ofred clay brick masonry provide the vertical



support for the floors and roofs, which aretypically constructed of heavy timberframing. Although most buildings of thistype employ walls composed of red claybrick, structures constructed of stonemasonry, unfired clay (adobe) andunreinforced concrete block also exist.Many brick URM structures have beenfaced with stone and/or terra cottaobscuring their actual construction. Themasonry tends to have relatively lowstrength, and therefore, the walls can bequite thick, as much as 30 inches or more,for multi-story structures. Typically, thesebuildings are less than 7 stories in height.URM buildings frequently collapse inearthquakes and following a series ofcollapses of these buildings in the 1933Long Beach earthquake, the State ofCalifornia adopted legislation prohibitingfurther construction of this building type.Therefore, most URM buildings pre-date theadoption of this legislation, in 1937.

Most URM floor and roof constructionconsists of wood joists, spanning betweenthe walls and sheathed with straight ordiagonal timber boards. Typically, minimalinterconnection exists between the wallsand the floors and roofs. Some largerbuildings have cast-in-place concrete floors.A few buildings have floors consisting of flatunreinforced masonry arches, with aconcrete topping.

Following extensive damage to URMs in the1983 Coalinga earthquake, the State ofCalifornia again adopted legislation dealingwith these buildings. Senate Bill 547required all cities and counties in Californiato inventory the URMs in their communitiesand develop plans for mitigation of thehazards associated with these buildings.Following the enactment of SB547, manyCalifornia cities began to adopt local

ordinances, requiring seismic upgrade ofURMs. Most such retrofits have beendesigned in accordance with criteria that areintended only as a life-safety improvementmeasure. Therefore, these upgradedbuildings can not typically be expected toperform as well as a new building a may stillpresent a significant seismic risk.Retrofitted buildings can usually beidentified by the presence of steel braces ormoment frames, and the presence ofclosely spaced steel plates at the outside ofthe wall, at each floor level and the roof.These plates are part of the hardware, usedto retroactively provide anchorage betweenthe diaphragms and walls.

URMs have been proven to represent asignificant hazard to life safety during nearlyevery damaging California earthquake.They present a hazard to occupants,pedestrians, and occupants of adjacentbuildings. Perhaps the most susceptiblecomponent of URMs are unbraced masonryparapets or cornices extending above theroof level. These architectural elements cantopple or separate from the masonry walland fall onto streets, sidewalks, or adjacentproperties. In addition, parapet failure canprecipitate failure of the wall below.

One of the major sources of damage andcollapse in past earthquakes has been thelack of adequate attachment between floorsand walls or roofs and walls. Earthquakescan result in large out-of-plane forces inwalls (loads perpendicular to face of thewall), and can cause the diaphragms andwalls to separate, leading to partial collapse.Unanchored tops of gable walls areespecially susceptible to this type ofdamage. Excessive horizontal deflection ofthe flexible and/or weak wood diaphragmshas also resulted in wall collapse.



Lack of adequate in-plane load transfercapacity between diaphragms and walls hasalso been a source of damage. Often noledger is provided, as framing members aresupported directly in pockets in the walls.When diaphragms are adequatelyconnected to walls, failure of theunreinforced masonry walls themselvesmay occur. This is most common for wallswith a large number of openings, or wallswith weak mortar.

A common deficiency for URMs is thepresence of an open storefront at the firststory, to accommodate commercialoccupancies. Long rectangular buildingsoften have virtually no wall at one or bothends to allow for displays, and thus havelittle strength in the transverse direction.Such buildings have collapsed in pastearthquakes. A variation of thisconfiguration is the building located on acorner with two adjacent walls relativelyopen. Such buildings are essentiallyunstable.

In many buildings of early construction, theexterior wythe may be joined to interiorwythes only by the mortar placed betweenthem in the vertical spaces, referred to ascollar joints. In other cases, adjacentwythes may be tied together using headercourses (a row of bricks laid with the longdimension across the collar joint). Withoutthe presence of headers, the outer wythecan easily peel off, representing a life safetyhazard to occupants and pedestrians.

The most common and cost-effectivestrengthening for URMs is to strengthen theparapet, by bracing it to the roof withdiagonal struts. Similarly provision ofanchors between the walls and the floorsand roof is a very cost-effective upgradetechnique.

Masonry walls with numerous openings maybe strengthened either by infilling selecteddoors and windows, adding new reinforcedconcrete or gunite walls, or providing newsteel bracing. In cases where the outerwythe of bricks is a veneer (no headerspresent) and could peel away, masonryanchors can be provided through the bricksto tie the wall together.

D.2.4.3 Unreinforced Masonry InfillUnreinforced masonry infill buildings arebuildings with perimeter unreinforcedmasonry walls that do not provide verticalsupport for the floors and roof. In thesebuildings, vertical support is provided eitherby structural steel or reinforced concreteframes embedded in the walls. Althoughthese buildings can be low-rise, mid-rise orhigh rise, they are most commonly found inmid- and high-rise commercial occupancies.

Steel-frame masonry infill buildings firstcame into use in the early 1890s, with theadvent of high-rise construction andcontinued through about 1940. Floorconstruction typically includes reinforcedconcrete slabs supported by steel beams.Interior partitions are often constructed outof unreinforced, hollow clay tile. The steelframes may or may not be encased inconcrete for fire proofing. Most majorCalifornia cities have a number of very largebuildings of this construction type.

Concrete-frame masonry infill buildingshave perimeter and interior walls ofunreinforced masonry filled-in betweenreinforced concrete columns and beams. Aswith the steel frame buildings of this type,interior walls were typically hollow clay tiles.In some more modern buildings, bothinterior and exterior walls may consist ofconcrete block.



There are no records of earthquake-inducedcollapse of steel frame masonry infillbuildings in the United States; however,they can be subject to extensive damage.When these buildings are subject to strongground shaking, the masonry infill tends towedge in place between the beams andcolumns, providing rigidity to the frame anddeveloping significant strength. However,the resulting stresses on the masonry,which can be very stiff with respect to thesteel frame, can cause extensive crackingand spalling. Decorative terra-cotta veneersare particularly susceptible to this type ofdamage, and debris from crushed terra-cotta ornamentation is a common fallinghazard in earthquakes.

One of the most common effects ofmasonry infills in concrete frames is thecreation of a short-column effect. When abuilding with masonry infill is subjected toground shaking, the masonry tends toprevent the frame from deflecting under theinfluence of the earthquake-generatedforces. When this action occurs, largecompressive forces are generated wherethe masonry bears against the framingelements. When the masonry walls areperforated with partial-height windows, thepoints of maximum bearing often will occurat the top and bottom of the windowopening, creating very high shear forces inthe columns at those locations. This hasled to partial collapse of a number ofbuildings, including some modernstructures.

Most infilled concrete frames are ofnonductile construction, resulting insignificant earthquake vulnerability. Inaddition, the presence of the masonry wallsoften makes these vulnerabilities moresevere. The masonry is a heavy materialthat adds significant mass to the building,

increasing both the amounts of force anddisplacement the building experiences in anearthquake. If the masonry is not properlyconfined within the plane of the frame,earthquake shaking can dislodge themasonry, causing it to topple.

Hollow clay tile interior partitions, commonlypresent in infill frame buildings are alsoconcerns. Infill frame buildings canexperience very large lateral deflections instrong ground shaking. When this occurs,the interior partitions will often tend tobehave as shear walls. However, thesewalls tend to be quite weak and brittle, andcan shatter when subjected to largeshearing deformations. If these partitionsare not solidly infilled between the floorsabove and below, they can also fall out-of-plane into adjacent corridors and rooms. Asis the case for the URM building, theparapets and ornamentation such ascornices are subject to damage and aresubstantial hazards to occupants andpedestrians. Although the SB547 legislationenacted by California in the mid-1980srequired inventory of these structures, mostcities have not adopted any ordinancesrequiring their retrofit.

A cost-effective retrofit of infill structuresthat can improve life safety is to strengthenthe unreinforced masonry parapet, and torestrain all ornamentation. Clay tile partitionwalls should either be removed or provisionmade to prevent collapse from endangeringlives of occupants. Wire meshes or steelstud walls have been installed to preventtoppling into corridors. An especially criticallocation for such measures are corridorsand stair wells that will be used as means ofegress after an earthquake. Similarlyveneers that could peel away during strongshaking should be removed or tied to thestructure.



In order to greatly reduce the risk inherent inthese structures, it is necessary to providesupplemental earthquake resisting elementsin the buildings, such as shear walls orbraced frames. Because these structuresare quite heavy, these walls and framesmust often be quite massive and requireextensive foundation work. Therefore,upgrade of these buildings if often quitecostly.

D.2.4.4 Reinforced Concrete WallBuildings

Concrete shear wall buildings have beencommonly constructed for institutional uses,such as government offices, hospital wards,schools, and prisons, since the early 1920s.They have also commonly been constructedfor larger multi-family residentialoccupancies including both apartmentbuildings and hotels. They can be of anynumber of stories, thought it is relativelyrare to find such structures in Californiaexceeding about 15 stories or so in height.Usually the entire structure, including thefoundations, walls, floor slabs, and anyinterior columns is constructed ofmonolithic, cast-in-place, concrete, thoughpre-cast concrete floor systems aresometimes used. The concrete wallsalmost always provide gravity support forthe floors and roofs as well as lateralresistance for earthquake and wind loads.In older buildings, the walls are most oftenlocated around the perimeter and are highlyperforated by windows, while for newerbuildings it is more common to locate thewalls around central service cores.

Various concrete floor and roof framingsystems used in concrete shear wallstructures include flat plate, pan joist orbeam and one-way slab, and waffle slab

systems. Single-story structures can havediaphragms consisting of wood sheathing.(Roofs of multi-story structures can alsoinclude wood sheathing.) Such rigidwall/flexible diaphragm structures willperform in a manner similar to tilt-ups,discussed in a later section.

The primary earthquake resistance in thesestructures is provided by the concrete walls.In older construction, walls are lightlyreinforced, but often extend throughout thebuilding. In newer construction, shear wallsoccur in isolated locations and are moreheavily reinforced. Although these newerbuildings, if adequately designed andconstructed can perform well, studies of theperformance of concrete shear wallbuildings in past earthquakes indicates thatbuildings with a high ratio of wall area tofloor area perform much better thanbuildings with less wall area.

In shear wall buildings it is not uncommon tofind some walls are terminated above thefoundation, either to create largecommercial spaces in the ground story oraccommodate parking spaces in thebasement. In such cases, the walls arecommonly supported by columns astructural discontinuity that has often lead tosevere damage in the past.

Collapse of concrete shear wall structures isrelatively rare. Where they have occurred,they have been traced to irregular walllayouts, poor quality concrete, inadequatereinforcement, or a grossly inadequatequantity of walls. Because concrete shearwall buildings are relatively stiff, incomparison to other building types, smallerdisplacements and less subsequentdamage to nonstructural elements areanticipated for these buildings. However,they can experience extensive damage to



the walls and, particularly at the edges ofthe walls and around openings for doorsand windows.

The layout of wall locations is, to a largepart, dictated by functional considerations.In many older buildings it was the onlyconsideration. Floor plans that inducetorsion, discontinuous walls or skewed wallsoften resulted. Buildings with wallsdistributed primarily around only two orthree sides are subject to large torsionaldisplacements (twisting) and have beenseverely damaged in past earthquakes.

Shear wall buildings with abrupt changes inlateral resistance have performed poorly inearthquakes. Damage concentrates inweak or flexible stories, or at locationswhere shear walls at upper levels do notcontinue to the foundation level.

Members not considered part of the lateralforce-resisting system (i.e., columns andfloor slabs) can experience damage if largedeformations occur and they are notdetailed to perform in a ductile manner.This is a common problem for many olderconcrete shear wall structures, with flat slabconcrete floors. The joints between theinterior columns and floors is ofteninadequately reinforced to withstand largeearthquake induced lateral buildingmovement, and punching type failures ofthe columns through the floor slabs havesometimes occurred.

Methods for retrofitting reinforced concreteshear wall structures are limited becauseany new components must havecomparable or greater stiffness and strengththen the existing walls. The addition ofinterior shear walls or braced frames (withnew foundations) can be used to reduce thedemand on weak perimeter walls. In some

locations exterior buttresses can also beadded, or the length of existing shear wallscan be increased. If these retrofits are notpossible, then the existing walls can bestrengthened by infilling existing door orwindow openings, or thickening existingwalls with shotcrete or cast-in-placeconcrete. Base isolation can be an effectivemitigation for some of these structures, butis often costly.

D.2.4.5 Reinforced Concrete FrameBuildings

Concrete frame structures have beenconstructed since about 1920. They caninclude commercial, institutional andresidential buildings and have also beencommonly used in transportation structuressuch as viaducts and bridges. Framebuildings can have any number of stories,but are most common in the mid-rise heightrange (4 to 15 stories). Most early concretemoment frames had perimeter walls ofunreinforced masonry infill as discussed in aprevious section. Many early framebuildings also had some shear walls. Pureconcrete frame construction (in whichneither extensive masonry nor concrete wallelements were present) started to bedeveloped in the 1940s.

Concrete moment frames are monolithicallycast systems of beams and columns. Floorand roof framing consists of cast-in-placeconcrete slabs, concrete beams, one-wayjoists, two-way waffle joists, or flat slabs.Curtain walls can include precast concretepanels, stone panels, metal skin panels, orglass panels. Foundations consist ofconcrete spread footings or deep pilefoundations.



Unreinforced concrete is weak in tensionand is brittle. Consequently, reinforcingsteel is typically provided along the top andbottom of the beams and distributed aroundthe perimeter of columns to resist tensionoriginating from bending of the members.Lateral reinforcing, or ties, are typicallywrapped around this longitudinal steel tohelp hold the longitudinal steel and theconcrete encased within it together, toprevent the bars from buckling, and to helpresist loads applied perpendicular to theaxis of the member. At ends of columnsand beams in moment frames, whereearthquake stresses are largest, it isnecessary for the tie spacing to be small(approximately 3 to 4 inches) to confine theconcrete and provide buckling restraint forthe longitudinal bars. For circular columns,continuous circular spirals, rather thanindividual rectangular ties, are often used.

Earthquake forces are resisted by theconcrete roof and floor diaphragms and themoment frames that develop their stiffnessthrough bending of beams and columns. Insome older construction, the momentframes may consist of the columns and two-way flat slab systems. Concrete momentframe structures can generally be groupedinto three categories, based on the age oftheir construction: pre-1964 (non-ductile),1964-1973 (ductility varies), and post-1973(ductile). These dates are general, basedon the prevailing building codes, and mayvary depending on specific location and thedesign engineer. The UBC adoptedsignificant changes to the designrequirements for concrete moment-framesin the late 1960s, based on publishedresearch. These changes were specificallyintended to provide for more ductile framebehavior. Where earlier codes focused onproviding strength to resist code-specifiedlateral forces, with the adoption of the 1967

UBC, the provisions began to focus onaspects of proportioning and detailing toachieve overall ductility as well as strengthrequirements. Nonductile concrete frames,although often designed to resist lateralforces, did not incorporate the specialdetailing provisions now required for ductileconcrete. Although the UBC first adoptedductile detailing requirements for concreteframes in the late 1960s, adoption of thesecode requirements was spotty until the 1971San Fernando earthquake. Extensivedamage to the Olive View Hospital, arecently constructed moment framestructure, in that event called attention tothe vulnerability of older design provisionsand spurred the local adoption of the newermore reliable provisions. Successiveimprovements and changes to theseprovisions have been made over the years,since.

Non-ductile concrete frame structures arevery vulnerable to severe earthquakedamage and collapse. Because thesestructures tend to have much largeroccupancies then URM buildings, tend tofail in a very brittle and sudden manner, andfew have been seismically upgraded theycurrently represent the single mostsignificant earthquake risk in California.Severe damage and collapse of thesestructures in strong earthquake groundshaking is common. The resulting heavydebris often results in large loss of life andmakes victim extraction difficult.

Properly designed and constructed ductileconcrete frame buildings have performedwell in recent earthquakes. However, theperformance of these structures is quitesensitive to how well the code provisionsare executed with regard to placement ofreinforcing, quality of construction andseparation of structural and non-structural



elements. At least one major ductileconcrete frame building has collapsed dueto a failure to faithfully execute the coderequirements in the design.

It is sometimes possible to make existingnon-ductile elements more ductile byjacketing the existing elements with newsteel, reinforced concrete, or compositefabric materials. Such approaches havecommonly been used when strengtheningcolumns of existing elevated freeways.However, mitigation of hazards associatedwith non-ductile concrete frame structurestypically involves provision of new lateralforce resisting elements rather thanstrengthening of existing ones. The mostcommon upgrade technique is theinstallation of new reinforced concrete wallsor steel braces. Because existing concretemoment frames are relatively flexible,supplemental energy dissipation systemscan also be an effective method ofupgrading these structures. The major goalof upgrade programs for concrete framebuildings is to reduce the structure’s lateraldeformations enough to protect the existingframe elements from failure.

D.2.4.6 Pre-cast Concrete StructuresThis type of construction may includestructures of all heights although inCalifornia, it is typically limited to low andmid-rise applications. Pre-cast structuresmay be used in commercial, institutional,industrial and residential occupancies.They are most commonly used for parkinggarages, hotels, mid-rise office buildings.This type of construction was firstdeveloped in the 1930s, but was not widelyused until the 1960s. Tilt-up construction, aspecial technique for pre-cast wallconstruction is discussed in a later section.

These structures consist of a frameassembly of pre-cast concrete girders andcolumns with or without the presence ofshear walls. Lateral forces are resisted bythe pre-cast or cast-in-place concrete shearwalls when present. If not, forces areresisted by pre-cast concrete momentframes that develop their stiffness throughbeam-column joints rigidly connected bywelded inserts or cast-in-place concreteclosures. Diaphragms commonly consist ofpre-cast elements interconnected with eitherwelded inserts or cast-in-place closurestrips, or reinforced concrete topping slabs.

The pre-cast frame is essentially a post andbeam system in concrete where columns,beams and slabs are prefabricated andassembled on the site. Various types ofmembers are used: vertical-load-carryingelements may be T’s, cross shapes, orarches and are often more than one story inheight. Beams are often T’s and double T’sor rectangular sections. Pre-stressing of themembers, including pre-tensioning andpost-tensioning, is often employed,especially when long spans are required.

Pre-cast concrete structures are subject tomany of the deficiencies of cast-in-placeconstruction. These deficiencies commonto cast-in-place construction will not bediscussed here. Rather the deficienciesspecifically associated with the pre-castconstruction procedure are highlighted.This type of building can perform well if thedetails used to connect the structuralelements have sufficient strength andductility, and there is a well-defined lateralload path. However, the connectionsbetween pre-cast units in most of thesestructures is not adequate. As a result, theunits can pull away from each other, leadingto local and global collapse.



A condition specific to precast structures(and especially prestressed structures) isthat they are often in a weakened conditionprior to being affected by an earthquake.Specifically the connections betweenadjacent elements are often stressed due toshrinkage, creep and temperature stresses.This can take the form of cracking aroundmetal connectors, or cracking in a toppingslab where it is doweled into a concrete wallthat resists shrinkage. Corrosion of metalconnectors between prefabricated elementscan also occur. Spalling of supports forprestressed beams is very common as thebeams try to shrink and the resulting forcesare resisted by friction at the supports.

The primary weakness associated with pre-cast concrete construction is theconnections, thus the most straightforwardretrofit is often to strengthen theconnections. However, as precast concreteframes are often non-ductile, the lateralforce-resisting system of many existingprecast frame structures should be modifiedas well.

Precast frame structures can bestrengthened by the addition of concreteshear walls or braced frames andassociated collectors and foundations. Forlarge structures subjected to largetemperature movement, the shear wallsshould be located near the center of thestructure, or special detailing should beprovided to avoid expansion/contractioninducing cracking in the diaphragm aroundthe walls. Connections of new interiorlateral force-resisting elements to theexisting structure is sometimes complicatedby the need to avoid prestressing tendons.

Some structures have pre-cast floor androof framing members that are connectedtogether with welded steel plates. These

members are intended to act as adiaphragm, but the connections are typicallytoo weak. Retrofit options include providingadditional connections, provision a toppingslab to act as a diaphragm, or strengtheningwith a composite fiber material if a toppingslab is unacceptable from a weightstandpoint. Reduction of diaphragmoverstresses in pre-cast structures may bemost readily achieved through the additionof interior shear walls and braces.

D.2.4.7 Steel Moment FramesSteel-frame buildings constructed before1940 are usually clad or infilled withunreinforced masonry. These structureswere discussed in a previous section.Modern steel-frame structures without infillinclude low- to high-rise commercial andresidential buildings, mostly constructedafter 1950. They are often recognizable bythe presence of glass curtain wall exteriors,or in buildings with other types of cladding,by the presence of many large windows.

Moment-resisting steel-frame buildingsconsist of an assembly of steel beams andcolumns. Typical moment frame structureshave bay widths (spacing between columns)of approximately 20 feet. Floor and roofframing consists of cast-in-place concreteslabs or metal deck with concrete fillsupported on steel beams, open web joistsor steel trusses. Foundations consist ofconcrete spread footings or deep pilefoundations.

These buildings rely on the rigid or semi-rigid interconnection of their beams andcolumns to provide lateral resistance.When such frames are subjected to lateralmotion, both the beams and columns aresubjected to bending stresses, with thelargest stress concentrations occurring at



the connections. Connections in modernsteel frame buildings are typically connectedby welded joints, although many olderbuildings (pre-mid 1960s) have bolted orriveted connections that may be consideredsemi-rigid in comparison with modernwelded joints.

Prior to the 1994 Northridge earthquake,many engineers regarded welded moment-resisting frames as the most reliable type ofconstruction for resisting earthquakedamage. No such buildings in the UnitedStates had ever collapsed in an earthquake,and there were few reported instances ofstructural damage in such buildings.However, following the Northridgeearthquake, fractured connections werediscovered in a number of buildings in theLos Angeles area. A large percentage ofthese buildings were relatively new (post-1976). The damage was often difficult andcostly to detect, requiring removal offinishes from the frame, and careful visualand nondestructive examination of theindividual joints. Repairs were also quitecostly to implement and is some cases,buildings remained permanently out ofplumb. Although none of these buildingscollapsed, at least one was so severelydamaged that it was deemed moreappropriate to demolish the structure, ratherthan repair it. It has now been determinedthat similar damage occurred to somebuildings in the San Francisco Bay Areaduring the 1989 Loma Prieta earthquake,and a number of these buildings weredamaged in the 1995 Kobe earthquake, withsome collapse reported.

In addition to connection problems, steelmoment-resisting frames can be subjectedto significant architectural damage, due totheir inherent flexibility. Elements that areparticularly susceptible to such damage

include interior partitions, ceilings andwindows. Cladding on many olderstructures was not designed with adequateprovision to accommodate the large lateralmovement of these buildings. In somecases, such cladding has occasionally fallenfrom the structure.

The retrofit of steel frame structures toaddress deficiencies other than the weldedsteel connections (e.g., configurationproblems) can be achieved by methodsoutlined in previous sections. For instancea soft story can be strengthened by theaddition of bracing. Deficient connectors forcladding can be modified, especially overmeans of egress or where pedestrians arejeopardized. Because of the flexibility of thestructures, a higher importance should beassigned to retrofit of nonstructural hazardssuch as bookcases, cabinets andsuspended ceilings that could pose a life-safety hazard.

Acceptable remedial measures have beenestablished for the welded moment steel-frame connections (removing weld materialand replacing with tougher material, andstrengthening the connection), but they tendto be quite expensive and disruptive andmay be comparable with the cost of damagerepair, given that an earthquake actuallyaffects the building. Assuming the risk ofsevere damage is relatively low, analternative is to evaluate the building toidentify high risk connections, and toestablish a post-earthquake inspection planthat can be used to either rapidly verifydamage, or provide confidence thatsignificant damage has not occurred.

D.2.4.8 Braced Steel FramesBraced steel frame structures have beenbuilt since the late 1800s with similar usage



and exterior finish as the steel momentframe buildings. They can be high-, mid- orlow-rise, but are typically in the range of 2 to10 stories in height. They are of similarconstruction to moment-resisting steelframes, but rather than relying on the rigidityof the beams and columns for lateralresistance, instead rely on the presence ofvertical diagonal bracing. Steel bracedframe buildings are characterized by thepresence of these diagonal steel braces thatrun between beam column connections atselected locations in the building. Mostcommonly, these braced frames are locatedadjacent to the perimeter walls of thebuildings. Because the braces tend todisrupt window space when placed onexterior walls, or prevent free use of floorspace when placed at building interiors,they are more common in industrial thancommercial applications. However, sincebraced frame buildings are generally moreeconomical to construct that moment-resisting frames, some speculativelyconstructed office buildings are of thisconstruction type.

Three common systems of braced framesexist: concentrically braced frames, specialconcentrically braced frames, andeccentrically braced frames. Concentricallybraced frames are the oldest form of thissystem. A number of patterns ofconcentrically braced frames are common.One pattern is diagonal “X” bracing, inwhich the braces extend directly betweenopposite beam-column joints in the frame.This system is often consideredarchitecturally undesirable because thebraces prevent access through the bracedbay and obscure window space. A morecommon system is the so-called chevronbracing, in which braces are arranged in a“V” or inverted “V” pattern extending fromadjacent beam-column connections to the

middle of the beam, above or below.Special concentrically braced frames aresimilar to ordinary braced frames, exceptthat they employ more rigorous detailing ofthe braces and their connections and areexpected to have superior earthquakeperformance. These special concentricframes were first introduced in the 1994UBC.

Eccentrically braced frames wereintroduced into the building codes in themid-1980s. They are a hybrid system thatemploys some of the characteristics of bothconcentrically braced frames and moment-resisting frames. Rather than meeting inthe middle of the beam, the bracing isslightly offset, and the short section of thebeam between the ends of the braces isdesigned to deform significantly under majorseismic forces and thereby dissipate aconsiderable portion of the energy. Thissystem protects the braces from thebuckling and yielding, a common damagemode for concentric braced frames. Theresulting behavior produces excellentstiffness to protect architectural elements,as well as enhanced energy dissipationcapacity.

The primary risk to braced frame structuresis that strong ground shaking can causebuckling and/or tension yielding of thediagonal braces or failure of theirconnections to other framing. In buildingswith “V” style braces, following buckling ofthe braces, large distortion of the floorbeams the braces are attached to typicallyoccurs. In some buildings, columns maybuckle under the large compressive loadsintroduced by the braces. Collapse ofbraced-frame structures is very rare, buthas occasionally occurred. A prominentexample is the failure of a high-rise braced-



frame building, the Piño Suarez complex, inthe 1985 Mexico City earthquake.

Although relatively few eccentrically bracedframes have experienced strong groundshaking, those that have are reported tohave performed very well.

In addition to retrofits that can addressdeficiencies associated with genericconfiguration problems, there are a numberof retrofit options for braced frames. One issimply to provide additional new bracedframes to reduce the loads on the existingframes. Typically new braced frames willalso require foundation modifications.Inadequate braced frames can sometimesbe strengthened by removing existingbraces and replacing them will larger onesor by modifying the existing braces and theirconnections.

D.2.4.9 Light Metal BuildingsThese buildings are typically pre-engineeredand prefabricated with moment-resistingframes providing lateral resistance in onedirection and light bracing providing lateralresistance in the orthogonal direction.Typically the exterior skin of these buildingsconsists of metal siding and roofing. Theyare usually one story in height, may havegabled roofs, and often enclose a large floorarea. Possible occupancies includeagricultural, industrial, and warehouseoccupancies. A majority of these structureswere constructed after 1950.

Lightweight steel structures have typicallyperformed very well in earthquakes. Moreearthquake damage has occurred to thesebuildings due to impact from topplingcontents than due to direct ground shaking.Structures that have sustained shakingdamage have typically been in poor

condition, or been modified since originalconstruction. Poor condition typicallyinvolves members that have been bent ordamaged by impacts from forklifts and othertraffic. Modifications typically includeremoval or cutting of rod braces foradditions or new openings. The addition ofmezzanines without lateral force-resistingsystems can also lead to damage.

The most common retrofit technique forthese buildings consists of replacement,supplementation or repair of deficienttension rod braces (both vertical andhorizontal). Retrofit is usually verystraightforward and can be achieved by theaddition of more rod bracing, replacingexisting rod braces with bigger rod braces,or replacing rod braces that have beenremoved by the tenants.

D.2.4.10 Tilt-up BuildingsThe concrete tilt-up design came intogeneral use in the early 1960s and is one ofthe least costly types of industrial and low-rise commercial structures to build. Thesebuildings are almost exclusively one andtwo-stories in height. They were initiallyused primarily as warehouse structures butare currently used for many othercommercial applications including officesand department and grocery stores. Theeffort spent on design is often minimized.Maximum advantage is taken ofstandardized design procedures andminimum building code requirements. Thisapproach is only reliable for regularbuildings with relatively few openings in wallpanels. However, modern tilt-ups can behighly irregular in plan and include manyarchitectural features that will cause theirearthquake performance to differ greatlyfrom the box-type structures originallyconstructed in this manner.



The name "tilt-up" is derived from themethod of constructing the perimeterreinforced concrete load-bearing walls.These walls are formed laying flat againstthe ground floor of the building in panelsthat are typically 20 to 30 feet wide. Wallthicknesses typically vary from 5-½ to 12inches. After having cured sufficiently towithstand erection stresses, the panels aretilted into a vertical position. Connectionsare made between the adjacent panels andbetween the panels and the roof and floorsto provide continuity and vertical stability.

In California, tilt-up buildings commonlyhave panelized plywood roofs supported bytimber framing. The primary componentstypically include glulam beams, usuallyspaced on 20- to 24-foot modules, 4-inchwide sawn purlins framing to the glulambeams on an eight-foot module, 2- by 4-inchor 2- by 6-inch sub-purlins (joists) framing tothe purlins on a two-foot module, andplywood sheathing. Other roof systemsinclude wood trusses, steel bar joists, orplywood- or oriented-strand board (OSB)-webbed members. Steel framing membersare sometimes used in combination withmetal decks. Roof and elevated floors,regardless of their construction, are typicallysupported by the perimeter walls and byinterior columns.

The single most common deficiency fortiltup buildings is the lack of adequateanchorage between the walls and thesupported floors and roofs. In strongground shaking, large forces are generatedwhich tend to pull the walls away from thefloors and roof. When this occurs, the wallscan fall away from the buildings and thesupported floors and roofs can collapse.These failures first occurred in the 1964Prince William Sound earthquake, inAlaska, but were again observed in the

1971 San Fernando earthquake. Prior tothe San Fernando earthquake, no formalinterconnection of the walls and supportedfloors and roofs was required. Followingthat earthquake, the code was modified torequired positive direct connections to avoidthese failures. However, with eachsuccessive California earthquake, it hasbeen demonstrated that the designrequirements for these connections havebeen inadequate, and major revisions to thedesign requirements have occurred in the1973, 1976, 1991, and 1997 editions of thebuilding code.

In addition to inadequate anchorage of wallsto floors and roofs, other deficiencies caninclude roof diaphragms that are inadequateto carry the seismic forces and walls thatare weakened by the presence of manydoor and window openings, and essentiallybehave as non-ductile concrete frames,discussed in a previous section.

Most efforts at retrofitting tilt-up structuresare aimed at improving the capacity of thewall anchorage system. This isaccomplished by post-installing anchor boltsinto the tiltup walls at floor and roof lines,and providing new attachment hardware toconnect the walls to the floor and roofframing. This can usually be accomplishedeconomically and without impact on buildingappearance or occupancy.

Weak diaphragms on these buildings canbe retrofitted by the addition of steel bracesat interior locations or by providingadditional nailing of the plywood to thesupporting framing. Walls that have beenweakened by excessive door and windowopenings can be reinforced by infill ofselected openings or by addition of bracedframes adjacent to the walls.



D.2.4.11 Reinforced MasonryThis type of construction became verypopular in the 1940s after unreinforcedmasonry was prohibited. Reinforcedmasonry buildings are mostly limited to low-rise perimeter bearing wall structures. Theoccupancy of this building type variesgreatly from small commercial buildings toresidential buildings. Generally they areless than five stories in height althoughmany mid-rise reinforced masonry buildingsexist.

Reinforced masonry walls in California aretypically constructed of hollow concreteblocks, with reinforcing steel inserted withinvertical and horizontal cavities in the block,which are then grouted solid (some wallsare only partially grouted, grout is providedonly in cells with reinforcement, while otherwalls are fully grouted). Some reinforcedbrick masonry walls have also beenconstructed. In these walls, two wythes(layers) of brick are laid up with a cavityspace in between. Reinforcing steel isplaced in the cavity between the wythes,which is then grouted solid.

The floors and roofs of masonry buildingscan comprise a number of differentsystems. Many one- and two-storystructures are provided with floors and roofsof timber construction; however, metal deckand concrete-filled metal deck supported bysteel framing are also common in suchstructures. Many apartment buildings andhotels are constructed with a system ofprecast, prestressed concrete plank floors,bearing directly on the masonry walls.Some small one-story buildings havereinforced concrete roof slabs.

Reinforced masonry buildings can performwell in moderate earthquakes if they areadequately reinforced and grouted, if the

floor and roof diaphragms are competentand if sufficient attachment exists betweenthe walls and roofs and floors. Theperformance or reinforced masonry wallswith flexible diaphragms has been similar tothat of tilt-up wall buildings, discussed in theprevious section. If the buildings haveprecast concrete floor elements, theirperformance depends on the ability of theconnections to tie the elements togetherand allow the structure to act as a unit whensubjected to lateral forces. Refer to theprevious discussion on pre-cast concretebuildings for deficiencies related to thisconstruction type.

An important factor in the performance ofreinforced masonry buildings is the degreeof quality control exercised duringconstruction. Some collapses of masonrybuildings in past earthquakes have beenattributed to failure of reinforced walls wherethe contractor had neglected to place thereinforcing or grout properly. Continuousinspection during the construction processis an effective method of avoiding suchproblems; however, such inspection is notrequired in all cases.

The configuration and detailing of the wallsthemselves is extremely important to thebuilding’s earthquake performance. Wallswith extensive openings are often subject tolarge cracking and spalling of the masonryunits around the openings. The pattern inwhich the masonry is laid up is alsoimportant. Most reinforced concretemasonry is laid up in a running bondpattern, in which the joints of the masonryunits in each layer are staggered relative tothe layers above and below. This is apreferred form of construction. Somebuildings incorporate a masonry patternknown as stack bond, in which the jointsbetween units align vertically from the top of



the wall to the bottom. Such a configurationis weaker with respect to resisting seismicforces.

As stated previously, many of thedeficiencies of reinforced masonry buildingswith wood roofs are common to tilt-ups.Refer to the previous section for discussionof upgrade techniques for mitigating thesedeficiencies. Existing masonry walls can bestrengthened for in-plane forces by infillingexisting openings in walls. Walls can alsobe strengthened by the application ofshotcrete. In such cases, sufficientanchorage must be supplied at interface ofthe existing wall and new shotcrete toprovide for shear transfer between theexisting and new walls. It may also bepossible to improve existing masonry wallsby bonding composite fibre fabrics to theface of the wall.

Some walls will be too weak for out-of-planebending due to either minimal reinforcing orrelatively tall heights. These walls may bebraced with external structural elements toreduce span lengths for out-of-planebending. Such elements are referred to asstrong backs, and are usually steel. Thesestrong backs must be adequately tied to thefoundation and the roof to transfer of forcesfrom the masonry wall.

D.2.5 Nonstructural ComponentsNonstructural components include portionsof the building not having a structuralfunction. Nonstructural componentsinclude, but are not limited to, mechanicalequipment, partitions, cladding, windowsand furniture.

Primary causes of damage to nonstructuralelements include sliding or overturning dueto inadequate anchorage, excessive

distortion due to attachment to a flexiblestructure and internal damage due toshaking. The type of structure anonstructural component is located withincan have a significant effect on its expectedperformance. Typically more nonstructuraldamage is expected for components withinflexible steel and concrete frame structuresthan in wall structures, because of theirflexibility.

Prior to the 1964 Alaska earthquake therewere no significant seismic requirements inthe building codes for protection ofarchitectural components and mechanicaland electrical systems. Following thatearthquake, the codes started to incorporateprovisions intended to protect thesecomponents. Although current codescontain adequate provisions, in practicethey often are not effectively implemented.This is because the responsibility fordesigning protection of these systems andcomponents is not clearly delineatedbetween the various members of the designteam, and often is overlooked.

There are three types of risk associated withearthquake damage to nonstructuralcomponents: life safety, property loss, andloss of function. Typically building codesare concerned with life safety risks only, andnot with providing damage control orproviding for functionality.

The primary life safety related risk is thatpeople could be injured or killed bydamaged or falling nonstructuralcomponents. Examples of potentiallyhazardous nonstructural damage that hasoccurred during past earthquakes includebroken windows, overturned tall and heavycabinets or bookcases, and falling precastpanels. Also, equipment operated usinggas such as boilers, furnaces and HVAC



equipment can cause fires or explosionswhen damaged by shaking.

The survival of critical equipment andcontents in a facility may be just asimportant as the survival of the buildings.Often, production and operations equipmentrepresents a large part of the investment ina facility and the greatest financialearthquake risk. For example, the value ofcomputer equipment in a data processingcenter will often greatly exceed the value ofthe building housing this equipment.Property damage to nonstructural elementscan be substantial. For most commercialbuildings, the foundation and superstructureaccount for approximately 20-25% of theoriginal construction cost, while themechanical, electrical and architecturalelements account for the remaining 75-80%.Contents belonging to the buildingoccupants represent a significant additionalexpense. Property losses may be the resultof direct damage to a nonstructural item dueto shaking or of consequential damage suchas water damage due to sprinkler failure, orfire due to a ruptured gas pipe. Indirectcosts associated with cleanup can besubstantial.

Nonstructural damage may make it difficultor impossible to carry out functions normallyaccomplished in a facility. After serious lifethreats have been dealt with, the potentialfor post-earthquake down time or reducedproductivity is often the most important risk.Loss of production equipment can lead toobvious impairment of business function,but loss of building equipment can also becritical. Many external factors affect post-earthquake operations, including power andwater outages. These effects are outsidethe control of a typical building owner,although backup systems can be provided.

The most common source of damage tononstructural components is lack ofadequate anchorage. It has beenconclusively demonstrated in pastearthquakes that properly anchored andbraced industrial-grade equipment, withsome caveats, has an inherent seismicruggedness and demonstrated capability towithstand significant seismic motion withoutstructural damage.

The behavior of any given equipment unitdepends on several factors. Among theseare the level of seismic shaking (dependenton some extent to the structure thenonstructural element is supported on), theunit’s height-to-width ratio and internaldistribution of weight, the coefficient offriction between the supports and the floor,and the proximity of other equipment.Consequences of damage may depend oncomponent location. For instance, failure ofa water tank on the roof may cause moredamage than failure of a water tank in thebasement.

Since explicit recommendations for bracingand anchorage of each component arebeyond the scope of this document, onlygeneral risk-reduction strategies forselected nonstructural components follow.

D.2.5.1 Computer EquipmentComputer installations have the potential tobe one of the most damage-prone areasduring a major earthquake. Potential lossesinclude both direct damage and businessinterruption resulting from the irretrievableloss of data and records. Many items foundin computer facilities are particularlysusceptible to damage, since they arerelatively tall and heavy, usuallyunanchored, and may tip over duringground shaking.



Seismic retrofit of computer equipmentusually includes improved attachment ofcomputer and installation racks through theaccess floor panels to the underlying floorsystem. However, because computerequipment is often sensitive to strongshaking and attaching equipment rigidly caninvalidate its warranty, unique solutions,such as isolating extremely sensitivecomponents, may be considered. Lowequipment that is unlikely to topple can betethered and bumpers installed on theperimeter of openings in the floor to stopequipment from sliding in and toppling.

Computer equipment is often supported ona raised access floor. Computer accessfloors are panelized, elevated floor systemsdesigned to facilitate access to wiring andother services associated with computersand other electrical components. Thesystem includes structural legs, horizontalpanel supports, and panels. Raised floorsmay collapse during strong ground shaking,due to a lack of lateral bracing. Seismicretrofit should include improving the lateral-load-carrying capacity of the steel stanchionsystem by installing braces or improving theconnection of the stanchion base to thesupporting floor, or both.

D.2.5.2 Electrical Equipment IncludingControl Panels and Transformers

This category includes switchgear, motorcontrol centers, and distributed controlsystem components. Properly braced andanchored electrical equipment has anexcellent performance record. However,inadequately anchored equipment isextremely susceptible to damage. Typicalobserved damage modes include tipping orsliding of transformers; tearing of attachedelectrical cabling and tipping of electrical

cabinets, control panels, and miscellaneousswitchgear; and tearing apart of longhorizontal runs of electrical conduit.Evaluation of this equipment is sometimescomplicated by the fact that verification ofanchorage often requires de-energizingequipment. Transformers owned byelectrical utilities can only be surveyed withutility cooperation.

In very intense ground shaking, it is notuncommon for slide-in-type components toroll out of their normal operating position orfor doors on units to open. Normally, whenthis occurs, replacement of the componentto its normal position and closing of thedoors return the unit to normal operation.

Seismic retrofit should include securelybolting components to the floor or adjacentwalls using angle brackets and heavy bolts.Detailing needs to be appropriate for thebase construction of the equipment.Transformers require well-engineeredanchorage because of their weight.

D.2.5.3 Storage Racks and StackedMaterial

Storage racks are generally purchased asproprietary systems installed by a tenantand are often not under the direct control ofthe building owner. Thus they are usuallynot part of the construction contract, andoften have little or no foundationattachment. Storage racks haveexperienced severe damage and collapsedin past earthquakes. Damage toinadequately designed and/or installedracks may include column deformation aswell as tearing of beam-to-columnconnections. Buckling of diagonal braces,column buckling near the base, and failureof column-to-base plate welds have also



been observed. Contents have fallen fromupper levels of racks.

Main contributors to observed damage arepoor seismic design, poor installation,overloading, and poor maintenance. Properinstallation of racks, specifically installationof anchor bolts, is key to their successfulresponse in earthquakes. Storage racksdamaged by forklift operations should bereplaced to prevent local and possibly totalcollapse. Retrofitting measures includeproviding base anchorage, tying adjacentrows of racks together, and providing slidingrestraints such that items cannot slide off ofshelves. Heavier materials should bestored at lower levels, and items on upperlevels should be shrink-wrapped to reducethe likelihood of falling hazards.

D.2.5.4 Suspended Tile CeilingsSuspended ceilings included suspendedmetal lath and plaster and suspendedacoustical board inserted within T-bars,together with lighting fixtures andmechanical items, to from an integratedsystem. The exposed-tee-grid systems thatconstitute about 90% of all installationshave sustained the greatest damage in thepast. Damage typically occurs due to a lackof positive lateral and vertical bracing.Falling ceiling tiles and metal framing cancause injury or damage to sensitiveequipment.

Original construction of such ceilingsystems involved no bracing. After damageto ceilings in the 1971 San Fernandoearthquake, diagonal wires were requiredfor ceilings, and independent wires wererequired for lights. Although the diagonalwires provided some improvement, it waslater determined that vertical compressionstruts at selected locations were also

required. Thus remedial measures forsuspended ceilings include installing verticalcompression struts and diagonal wires toprovide lateral bracing. Confinement of theceiling around the perimeter and sufficientbearing around the perimeter also enhanceseismic performance.

D.2.5.5 Vibration-Isolated Equipment.Mechanical equipment (e.g., standbygenerators, air handlers, and fans) is oftensupported on springs or isolations mounts tolimit transfer of the vibrations it creates tothe structure (thereby limiting discomfort tooccupants). Older isolators were typicallyprovided with no consideration of seismicloads. Since the 1980s isolators forsubstantial equipment typically havecapacity to resist seismic loads.

During past earthquakes, equipmentsupported on simple vertical spring vibrationisolators have been repeatedly observed tofail, with resulting misalignment of theequipment and damage to attached pipingor cabling. Isolators designed to resistseismic loads have also failed, primarilybecause of poor installation of anchor bolts,inadequate anchor bolt edge distance, orinadequate design. Anchors into equipmentpads in penthouses that consist oflightweight (weak) concrete have failed.

Seismic stops that limit lateral displacementbut allow vertical displacement requiredvibration can be used to prevent damage tosimple spring isolators. However, becauseisolated equipment does perform poorly,current codes require that anchorage designforces for them be larger. Prior to retrofit itshould be verified that isolation of theequipment is required. In many cases,equipment supported on isolators on grade



could be supported directly on grade,permitting more direct and effect anchorage.

D.2.5.6 Rigid Grade-mounted EquipmentRigid grade-mounted equipment, includingpumps, electric drivers, generators,compressors, air handlers, fans, and similarequipment, have historically performedexcellently, if they are appropriatelyanchored to foundations and no groundfailure occurs. In case of rotating ordynamic equipment, including pumps,compressors, and drivers, the anchor boltsnormally recommended by equipmentmanufacturers to resist operating loadshave proven adequate to prevent damage.

D.2.5.7 Standby Power SystemsAs it is generally accepted that power willnot be available from utilities immediatelyafter an earthquake, many facilities havedecided to have standby power. Standbypower typically includes diesel generatorsand supporting equipment (includingbatteries, fuel storage and transfer pumps)and in cases with computer orcommunications facilities, un-interruptablepower supply (including batteries, batterychargers and inverters).

Such facilities have typically performed wellin when properly anchored. Self-containeddiesel generators have about a 90%reliability for startup and prolongedoperation following strong ground shaking.Damage in past earthquakes has includedfailed isolation mounts, unrestrainedbatteries toppling, and failed fuel lines.Components on generators such asmufflers have also toppled due to lack ofrestraint.

In addition to verifying adequate anchorageof all equipment, the fuel line should beevaluated for adequate flexibility, andsusceptibility to settlement. Fuel linespenetrating building walls are susceptible toshearing if the adjacent soil settles withrespect to the building.

D.2.5.8 TanksThe importance of anchoring smaller tankshas been repeatedly demonstrated duringpast earthquakes. Tanks have "walked"across the floor or toppled wheninadequately legs or anchorage failed.Tank movement has sheared attachedpiping, resulting in loss of contents.Secondary damage from spilled liquids cancause business interruption problems.

Large, ground-supported atmospheric tanks(e.g., firewater, fuel, and wine) have beenrelatively poor performers in strong groundmotion. These tanks are frequentlyunanchored, have thin shells, andexperience amplified seismic effects fromthe sloshing motions that can develop withinthe contained liquids. Common damageincludes rupture of rigid piping connections,buckling of the shell, ripping of the floorplate, and flexure of the roof. Tanks whichexperience damage to floor plates or thewelds between the floor plate and the wallcan experience rapid loss of contents andimplosion due to the resulting vacuum. Instrong ground motion, atmospheric tankshave exhibited a failure rate as high as25%. However, failure does not alwaysimply complete release of materials(buckled walls often do not leak).

Retrofit of steel tanks can include providingflexibility in attached piping, anchorage, andthickening of the wall at the base course.Providing flexibility is typically the most cost-



effective. Providing anchorage to anunanchored tank can often involve provisionof a new foundation. Thickening of the wallat the base of the tank will only be effectiveif the base plate is thick enough.

D.2.5.9 PipingWelded steel and soldered or bracedcopper lines generally perform well inearthquakes. Threaded pipes, or pipesusing mechanical couplings, like those usedfor sprinklers, are more susceptible todamage. Failure usually initiates at joints.

Damage to piping has resulted frominadequate bracing, failure of bracinghardware, incompatible deflections ofstructural and nonstructural components. Ingeneral, when failure of this piping occurs, itis not as a result of inertial loading, butrather one of the following causes:

1. Rigid length of pipe attached to twostructures or pieces of equipmentthat move differentially. An exampleof where this can occur is a pipecrossing an expansion joint in a longstructure and being rigidly attachedto the structure on both sides.

2. Failure of several supports along arun of piping resulting in greatlyincreased inertial loading. The mostcommon type of support failureconsists of trapeze or rod supportssuspended from expansion inserts inthe undersides of concrete floorslabs. During ground motion, theinserts rock back and forth and workthemselves loose, allowing the pipeto fall.

Screwed and compression fitting piping hasa poorer performance record. This piping

can fail as a result of inertial loads, if it is runin long, improperly supported lengths.However, failures of this piping tend to be inthe category of minor leakage rather thanmassive joint failure.

To minimize damage, equipment attachedto piping should be restrained or anchoredto ensure that large relative displacementscannot occur. At locations where pipesspan between independent structures or atseismic joints, sufficient flexibility should beprovided to accommodate anticipatedmovements. The support and bracing ofbends in main risers and laterals isespecially important.

Different retrofit approaches should betaken based on the contents of the piping.In general, fluid piping includes twocategories: hazardous and flammablematerials that would pose an immediatesafety danger, materials that might poseproperty loss but no life safety danger.There are prescriptive design approach tosupport and bracing. Small diameter pipingin the second category are often leftunbraced. The increased flexibility of smalldiameter pipes often allows them to performbetter than larger diameter pipes, althoughthey are subject to damage at the joints.

D.2.5.10 Conduit and RacewaysConduit and cable run in cable trays bothhave an excellent performance record inearthquakes. Cases have been recordedwhere rods supporting cable trays havepulled out of the supporting structure, butthe cable had adequate strength to supportboth itself and the tray. Toppledcantilevered raceway supports have loss offunction.



Bracing of raceways can be implemented tominimize such occurrences. However,except for the case of cantilevered supports,bracing is usually not justified. Rehabilitationcan be accomplished by prescriptivemethods contained in SMACNA standards.

D.2.5.11 Firewater SystemsFire protection systems includes tanks,pumps, pipes, heat and smoke detectorsand panels. Firewater systems have beenquite vulnerable to seismic damage inrecent earthquakes. Piping has been themost significant vulnerability. Firesuppression piping includes main risers,laterals and branches. Bracing is usuallylimited to main risers and laterals. Unlikeprocess piping, jointing in firewater lines isoften compression-type couplings. Thesecouplings have proven to be vulnerable toseismic damage. In addition, firewaterpiping is usually field routed by theconstruction crews, often with little regardfor bracing requirements. As a result, thepiping is frequently vulnerable to damagefrom swaying and interaction with adjacentstructures. Sprinkler heads can beimpacted by structural elements orsuspended ceiling systems. In wet pipesystems, considerable damage to inventoryand electronic can occur as a result of theleaks that frequently develop.

The diesel-driven emergency firewaterpumps that pressurize these systems canalso be a problem. Frequently, the diesel-driven pumps are mounted on vibrationisolation supports. As discussed previously,these can be damaged by even moderateshaking, resulting in loss of functionality.Control cabinets, battery power supplies,day tanks, and other auxiliaries associatedwith the diesel pumps frequently are notadequately installed to prevent damage as

well. Thus, the ability of many firewatersystems to function following a majorearthquake is questionable.

Fire suppression piping must be evaluatedfor adequate support, flexibility, protection atseismic movement joints, and freedom fromimpact from adjoining materials at thesprinkler heads. The support and bracing ofbends of the main risers, and laterals, aswell as maintenance of adequate flexibilityto prevent buckling, are especiallyimportant. Rehabilitation is accomplishedusing the prescriptive requirements ofNFPA-13. Other components must beanchored or restrained as discussedpreviously.

D.2.5.12 Chimneys and StacksChimneys and stacks that are cantileveredabove building roofs have often failed inearthquakes. Unreinforced masonrychimneys and stacks typically represent thelargest risk. Rehabilitation may take theform of strengthening or bracing andmaterial repair.

D.2.5.13 Light FixturesLight fixtures include those recessed inceilings, surface-mounted to ceilings orwalls, supported within a suspended ceiling,or suspended from ceiling or structure withpendant or chain. The most common failureof lights occurs within suspended ceilingsand result from the loss of support from theT-bar system. Independent support of lightsshould be provided, as discussed withsuspended ceilings above.

Failure of lights suspended by pendants orchains can occur due to excessive swingingthat can cause impact. These lights shouldbe braced to ensure freedom to swing



without impacting adjoining materials.Fixtures weighing over 20 pounds shouldhave adequate articulating or ductileconnections to the building, and be free toswing without impacting adjoining materials.

Proposition 122 Product 2.2Earthquake Risk Management: A Toolkit For Decision-Makers E-1

Appendix E: Equipment Assessment Methodology

E.1 General

This section presents a summary of theMCEER methodology for assessing andreducing earthquake risk for critical facilityequipment systems discussed in Chapter 3of this document. This overall assessmentprocess was developed to provide a meansof quickly assessing the reliability of a facilityor system within a facility. MCEER 99-0008: Seismic Reliability Assessment ofCritical Facilities: A Handbook, SupportingDocumentation, and Model Code Provisions(MCEER 99-0008) was developed topresent a scoring system with which thereviewer can quickly evaluate criticalmechanical and electrical systems todetermine which systems might warrantmore detailed evaluation or modifications.This handbook can be obtained availabledirectly from MCEER.

E.2 Overall Assessment Process

The assessment process summarizedherein is intended to be used by peoplewithout expertise in engineering orseismicity. No engineering calculations orrigorous training are required to perform thereliability assessment. The guidelinespresented in the MCEER handbook areintended to give a complete overview of theprocess and detailed descriptions of thesteps involved in performing the review. Thescoring system has been developed to limitthe need for interpretation, but still retain

enough flexibility to be applicable to a broadrange of installations and facilitiesnationwide.

In order to develop a screening process thatcan be performed rapidly by facilitypersonnel on such a broad basis, a degreeof conservatism is inevitable. Since thismethodology is intended to provide broadestimates of a facility’s vulnerability, aconservative approach is acceptable, andeven desirable.

The following are the major steps involved inimplementing the reliability assessmentmethodology using the handbook.

STEP 1: SYSTEM AND COMPONENTIDENTIFICATION

A facility may have specific functionalityrequirements during or following anearthquake, as specified by federal law orfederal, state, or local regulators. Forexample, hospital performancerequirements for critical care may bespecified in a state-issued license; dataprocessing requirements for banks may bespecified in Federal law. In addition, afacility owner may determine that a functionis essential if it is deemed financiallyimportant for continued operation orbusiness recovery.

A critical system is one that is required toprovide either (i) the essential facility

EQUIPMENT ASSESSMENT METHODOLOGY

Proposition 122 Product 2.2E-2 Earthquake Risk Management: A Toolkit For Decision-Makers

function, as defined above, or (ii) life-safetyprotection as required by other laws orregulations. A component of a criticalsystem could be either a particularequipment item; a portion of a system suchas piping, ducting, etc.; or a human actionthat is required to provide function of thecritical system.

The handbook describes how criticalsystems and critical components can beidentified for a facility. A method is providedfor systematically reviewing importantsystems and the impact of their failure onother important systems. A means isprovided to incorporate specialconsiderations, such as emergency plans,personnel actions, and known maintenanceproblems.

STEP 2: ASSESSMENT OF INDIVIDUALCOMPONENTS

The handbook presents a method for rapidlyevaluating individual equipment componentsand incorporating those evaluations into asystem evaluation. That method usesassessment techniques based on historicalearthquake performance of similarequipment items. Assessments are madeof specific items that have been known to becauses of damage in past earthquakes, orknown to be seismically vulnerable for otherreasons.

Scoresheets are provided for individualcomponents, and a method for assigningscores is presented, based on the designand installation of the component, thelocation within a building and geographically,and other factors. Higher scores indicatehigher seismic reliability.

STEP 3: ASSESSMENT OF SYSTEMRELIABILITY

The handbook provides a method for rapidly,but systematically evaluating the reliability ofcritical systems in an earthquake. A systemscoring system is provided to quantify therelative reliability of systems andcomponents. This method can be used byan individual to identify and prioritizevulnerabilities on a system and facility basis.

For each of the major systems identified, asystem evaluation should be performed.The methodology described in the handbookmakes use of the system and componentinformation developed for each system andthe scores for individual components.

STEP 4: RISK MANAGEMENT

The results of the screening methodologyprovide a basis for making risk managementdecisions. The review of critical electricaland mechanical systems and theircomponents provides the informationnecessary to create a specific plan forimproving a facility’s post-earthquakefunctionality.

The component and system evaluationsdescribed in this process are part of ascreening assessment. It highlightsimportant system components, theirinteractions, and their impact on systemfunction. It is not the only indicator of whereupgrades or repairs should be made, but itprovides a consistent method for identifyingobvious vulnerabilities and prioritizing riskmanagement implementation.

Mitigation is not limited to physical repairs toequipment or systems. Mitigation can beachieved through means such as upgrades,analyses and emergency responseprocedures. All mitigation efforts as defined

EQUIPMENT ASSESSMENTMETHODOLOGY


in this process are intended to improveoverall system reliability.

E.3 Identifying Facility PerformanceRequirements

The owner of a facility should identify whatthe functional requirements of the facility areduring and following an earthquake.Essential functions are those which must beprovided by a facility during an earthquake,immediately following an earthquake, orwithin a specified time period following anearthquake. Examples may includerequirements to provide emergency orcritical care for hospitals or money transfersfor banks. Federal law or federal, state, orlocal regulators may specify other specificfunctionality requirements.

Essential functions may be identified by anyof the following means:

§ Specific facility performancerequirements that are unique to agiven facility, industry, or type ofinstallation, may be specified by lawor other regulatory or licensingrequirements, under federal, state, orlocal jurisdiction.

§ Minimum standards of life-safetyprotection must be maintainedirrespective of the event that hasoccurred and the level of escalation.This would include fire detection andalarm, fire response, buildingevacuation and egress, and similarsystems or functions, as required byfederal, state, or local laws andregulations.

§ A facility owner or manager mayidentify any additional function ascritical and evaluate systems using

this Recommended Practicebecause of financial considerationsor any other reasons. Examples ofsuch considerations would beconcerns for capital costs, businessinterruption, and damage andrecovery costs.

E.4 Identification of Critical Systems

As discussed above, critical systems arelikely to include both life-safety systems andbusiness operation systems. Life-safetysystems are usually defined as thosefunctions whose failure results in conditionswhere lives are in imminent danger or arenot sufficiently protected from potentialdangers. Typical examples of life-safetyfunctions are:

§ Fire response (including detection,suppression, and smokebarriers/purge)

§ Shutoff of hazardous materialreleases (primarily natural gas)

§ Elevator safety

§ Evacuation/Egress

Business operation systems are defined asthose systems that must function in order tocontinue operation of the facility at full orreduced capacity. This definition of capacityis the starting point for the identification ofthe critical business operation functions.For example, operation of elevators may beconsidered to be essential for full buildingoperation in one situation but non-essentialfor another similar building if the desiredstate is limited operation. This designationdepends on the essential function of thefacility, and is determined as the first step of



the evaluation. Typical examples ofbusiness operation functions are:

§ Lighting/Power (including lighting,normal building power, emergencypower)

§ Water Supply/Waste Removal(including water supply, sewageremoval)

§ Storm Drainage

§ Normal Personnel Transport(including elevators)

§ Building HVAC (including heating,ventilation, air conditioning, HVACcontrol)

§ Communications (includingtelephone/communications, datatelecommunications)

§ Data Processing (including dataprocessing equipment, computerequipment)

§ Refrigeration

§ Gas Supply

§ Structural Concerns (includingraised access floors)

Within MCEER 99-0008, there area seriesof checklists were developed to assist inidentifying critical systems and components.These checklists can be used to identifysubsystems and utilities that are alsorequired for functionality of the system.While functionality of the critical systems isgenerally provided by operation ofcombinations of equipment and/or humanactions, in some cases, a single operatoraction may be all that is required in order to

provide for functionality. In other cases, thecombined operation of several systems maybe required. In some cases there may beredundant means for providing full or partialoperation.

The goal of the entire process ofidentification of components is to narrow thescope of components examined from an all-encompassing list of building equipment to alist which reflects only those componentsnecessary to provide functionality of criticalsystems while also accounting for anyenhanced safety provided by installedredundancy.

E.5 Critical Systems Diagrams

One method of providing a pictorial view ofthe system interrelationships is bydeveloping diagrams of critical systems.These diagrams provide a framework forquantifying the relative reliability of thesystems following an earthquake and arealso a useful tool for the process of makingpractical risk management decisions. Thecritical system diagrams are a type of logictree, similar to a fault tree, which uses“AND” and “OR” logic to express the systeminterrelationships to the overall successfulfunctioning of the building being examined.Similar diagrams can be constructed

Diagrams can be used to define overallsystem requirements for life-safety orbusiness operations, as shown in Figure E-1, as well as detailed descriptions ofcomponents required for specific systems,as shown in Figure E-2.



(See page __)

KEY

SYMBOL N A M E MEANING

AND GATE

OR GATE



Life-SafetySystems

FireResponse

GasShut-off

ElevatorStopping System

StairwayEmergency Lighting

(See page __)

(See page __)


Active FireSuppression Systems

(See page __)

Air Duct Fire andSmoke Dampers

Figure E-1: Life-safety Systems/Fire Response Level Logic

See Figure E-2



HVAC DuctSmoke Detectors

KEY

SYMBOL NAME MEANING

AND GATE

OR GATE




Fire AlarmPanel

FireDetection

Fire AlarmIndicating Device

SmokeDetection

ESSENTIAL

PullStations

HeatDetectors

SprinklerFlow Sensors

REDUNDANT

Spot SmokeDetectors

LineSmoke Detectors

Figure E-2 Fire Detection and Alarm Logic Example

E.6 Components Evaluation

The scoring methodology for an individualcomponent uses the following logic:

1. Each component is assigned a basicscore that is a function of theperformance history of that type ofequipment, and the seismicity of thesite. Those scores have been

developed for broad categories ofmajor equipment components

2. The basic scores are modified byPerformance Modification Factors(PMFs) which indicate the decreasein reliability due to specificconfigurations or details that may bepresent in an equipment installation.Each detail that might affect the



seismic vulnerability is assigned aPMF consistent with its relative effecton functionality.

3. The evaluation and checklist arecompleted such that the basic scoreand all applicable PMFs areidentified.

4. The equipment item is assigned ascore equal to its basic score minusthe largest (worst case) applicablePMF. If further evaluations orsystem modifications lead to thedetermination that a particular PMFis no longer relevant, the secondmost critical PMF is then used.

An example data sheet is shown in FigureE-3. Similar sheets have been developedfor major electrical and mechanicalequipment categories found in criticalfacilities.

E.7 Component Scores

Scores for individual components weregenerated based on standard lognormalfragility formulations defining the conditionalprobability of failure, fO, for a givenacceleration level, a, as:

( )f =

ln a AO

m

RΦ

β

(E-1)

where Φ is the standard Gaussiancumulative distribution function, βR is ameasure of the random variability, and Am isthe median acceleration capacity.

Of course, perfect knowledge of a system isunattainable and some amount ofuncertainty exists. Including this uncertainty,

βU, makes the fragility a random variable. Amean fragility curve can also be calculated,which is the weighted average of all possiblecurves. An important short cut is availableto calculate the mean curve withoutaveraging all individual curves. The meancurve is also a lognormal function of themedian capacity and a combineduncertainty βc, where

β β βc = R + U2 2 (E-2)

Fragility data were generated using variousmethods, including earthquake experiencedata, limited testing data, statistics oncapacities and uncertainties used in riskcalculations for similar components at oldernuclear power plants, and judgment ofengineers intimately familiar with equipmentvulnerabilities.

Basic Scores were calculated as thenegative of the logarithm (base 10) of theannual probability of failure.

Basic Score = S = -log10(Pfa) (E-3)

The annual probability of failure is calculatedby convolving the fragility curve of acomponent with a “generic” seismic hazardcurve. The convolution is described by thefollowing equation:

PdH ada

P a dafa fc=−∞

∫( )

( )0 (E-4)

where Pfa is the annual probability of failureand Pfc is the conditional probability offailure. H(a) is the hazard curve.



Batteries and Racks

Component ID:

Location:

Comments:

Earthquake Load Level (circle one letter)

Location in Building

NEHRP UBCBottomThird

MiddleThird

TopThird

Z 1-3 1 A A A

O 4-5 2 A B C

N 6 3 B C D

E 7 4 C D E

Scores and Modifiers - Batteries and Racks(circle a Basic Score and all PMFs that apply - use the column indicated by the Earthquake Load Level above)

Description A B C D E

Basic Score à 5.3 4.4 3.9 3.5 3.2

1. No anchorage 1.5 1.5 1.5 1.5 1.52. “Poor” anchorage 1.3 1.3 1.3 1.3 1.3

P 3. No battery spacers 0.7 0.7 0.7 0.7 0.7M 4. No cross-bracing 0.9 0.9 0.9 0.9 0.9F 5. No battery restraints 2.0 2.0 2.0 2.0 2.0

6. Interaction concerns 0.5 0.5 0.5 0.5 0.57. Other:

Final Score = Basic Score – highest applicable PMF

Note that this is a screening process and is inherently conservative. If there is any question about an item, note itand select the appropriate PMF. See the following page for PMF guidelines.

Figure E-3: Sample MCEER 99-0008 Component Scoresheet: Batteries and Racks



Explanation of Performance Modification Factors (PMFs)

1, 2 If there are no anchor bolts at the base of the frame, select PMF 1. If the anchors appear to be undersized, ifthere are not anchors for every frame of the rack, or if the anchorage appears to be damaged, select PMF 2.

3 Look for stiff spacers, such as Styrofoam, between the batteries that fit snugly to prevent battery pounding. Ifthere are none, select PMF 3.

4 The rack should provide restraints to assure that the batteries will not fall off. The photo above shows a rackwith no restraints, while the photo to the left shows a rack with restraints. Select PMF 4 if adequate restraint isnot provided.

5 Racks with long rows of batteries need to be braced longitudinally as shown in the photo to the left. Select PMF5 if no cross-bracing is present.

6 If large items such as non-structural walls could fall and impact the battery racks, select PMF 6.

7 For other conditions that the reviewer believes could inhibit battery function following an earthquake (e.g., ahistory of problems with this piece of equipment), assign a PMF value relative to the existing PMFs in the table.Add a descriptive statement for the concern.

1, 2

1, 2

5

6

4

34



Figure E-3 (continued): Sample MCEER 99-0008 Component Scoresheet: Batteries and Racks

SYSTEM SCORING

An emphasis of this project was to developa methodology that allows the user to makerisk management decisions based onreliability of systems rather than individualcomponents. In order to achieve that goal, ascoring system was developed, such thatscores are assigned to individualcomponents and to entire systems.Eventually a score can be assigned to everysystem required to maintain the operationscapability of a given facility. Those scoresare based on the scores of the individualcomponents and the importance of thosecomponents in maintaining system function.

However, it was also recognized thatrigorous risk analyses using Booleanalgebra on complicated logic diagramswould not be practical. As such, severalsimplified methods were assessed fordetermining system scores, such as takingthe highest score or adding scores forredundant systems and taking the lowestscore for dependent systems (where failureof any component causes the system tofail).

Each method was tested by performingrigorous systems analyses of multiplecases with varying numbers of componentsusing the proprietary program EQESRA™.EQESRA™ was developed to evaluate theprobability distribution of system failurefrequency from information aboutcomponent fragilities (seismic or non-seismic failures), Boolean expressions foraccident or event sequences, and seismichazard. The program performs componentcombinations in accordance with the

Boolean expression to yield an overallsystem or plant level fragility. It thenconvolves the system fragility with theseismic hazard to yield a probabilitydistribution on failure frequency, which wastranslated into basic scores for comparisonto results from the simplified methods. TheEQESRA™ program uses the methodologydescribed in Kaplan (1981) and Kaplan andLin (1987).

Based on these analyses, the followingsimple rules were developed for scoring:

1. When a group of components islinked by an “and” gate (indicatingdependency), the overall score forthat group is the lowest of thecomponent scores, Smin.

2. When a group of components islinked by an “or” gate (indicatingredundancy), the overall score forthat group is the highest of thecomponent scores (Smax) plus afactor (f). This factor depends on thenumber of components (N) linked inparallel and takes the form: f =0.5(N-1). So the score for aredundant group of components is:Smax + 0.5(N-1).

An example is shown in Figure E-4.



FireSuppression

5.30

StorageTank4.40

Piping5.30

ElectricPump5.05

BuildingPower3.75

DieselPumps5.03

EmergencyGenerator

5.16

55 GallonDrums6.19

WaterPumps5.55

KEY

SYMBOL NAME MEANING

AND GATE

OR GATE



Valves5.39

StartSystem

5.31

Piping5.30

DayTank5.18

CityWater5.00

WaterSupply5.50

Smin = 5.05

Smax+0.5(N-1) = 5.66

Smin = 5.03

Smax+0.5(N-1) = 5.55Smax+0.5(N-1) = 5.50

Smin = 5.30

Figure E-4: Illustration of MCEER 99-0008 System Scoring(Numbers shown were selected for illustrative purposes only)

Proposition 122 Product 2.2Earthquake Risk Management: A Toolkit For Decision-Makers F-1

Appendix F: Typical Consultant Work Statement

F.1 Retaining Seismic RetrofitDesign Professionals

Retaining engineers experienced in seismicretrofit is an important aspect of the retrofitprocess. One of the most importantattributes to look for is experience andsatisfactory performance on previousprojects. As discussed previously, theseismic retrofit professional will typically goabout the assessment and mitigation in athree phased approach, consisting of:

1. Initial investigation;

2. Detailed investigation, conceptualretrofit design, and costing ofalternatives; and

3. Final design, production of designdocuments, and a ‘bid package’.

Step two is perhaps the most crucial fromthe decision-making viewpoint, since this iswhere the alternatives are evaluated forcost and effectiveness.

In retaining an engineer, a clear anddetailed scope of services should form thebasis for the relationship. The scope ofservices must of course be specific to theparticular situation, but might consist of thefollowing tasks:

Example Scope of Services for SeismicRetrofit Design Professional

Phase I – Initial Investigation1. Review all available construction

documents for the building includingstructural and architectural drawingsand specifications for the originalconstruction as well as similardocuments for any significantmodifications or upgrades. Thepurpose of this review shall be todetermine the basic structural loadcarrying systems, and to identifyseismic performance issues relatedto configuration and structuraldetailing.

2. Review available geotechnicalreports for the site to determine asite class for use in developingseismic hazards and to identifyconditions that could lead to groundfailure or other site instabilities.Where site specific soils data is notavailable, reference should be madeto available generalizedgeotechnical data such as found onregional maps produced by theUnited States Geologic Survey(USGS) and the California Divisionof Mines and Geology (CDMG).Reference should also be made tothe seismic safety element of localgeneral plans.


Proposition 122 Product 2.2F-2 Earthquake Risk Management: A Toolkit For Decision-Makers

3. Perform a seismic hazard foranalysis for the site to identify thelocation of the site relative tosignificant faults, and to estimate theprobable intensity of groundacceleration as a function of returnperiod (or probability ofexceedance).

4. Conduct a visual survey of thebuilding to document the structure’scondition and to confirm thatavailable construction documentsare representative of existingconditions. To the extent thatconstruction documents areunavailable, perform fieldinvestigation to develop sufficientinformation to identify the verticaland lateral structural load carryingsystems, and to quantify theirstrengths.

5. Perform a preliminary structuralevaluation to quantify the probableperformance of the building structureto resist the effects of groundshaking having a 10% probability ofexceedance in 50 years. {Note thateither more or less probable levelsof ground shaking may be specified,based on the importance ofindividual facilities. For facilitieslocated within a few miles of majoractive faults, it may be moreappropriate to specify that theevaluation be performed for amedian estimate of the groundshaking resulting from acharacteristic earthquake on thatfault.} The evaluation should, as aminimum, conform to therequirements of FEMA-310 for a Tier1 evaluation. Alternative evaluationsthat quantify the adequacy of the

seismic force resisting systemconsidering, strength, ductility, andconfiguration issues may be used.

6. Develop an inventory of critical non-structural components includingbuilding utility equipment (powersupply, HVAC systems), operatingequipment, ceilings, building fasciapanels, elevators and fire protectionsystems. Identify the adequacy ofinstallation of these non-structuralcomponents to resist damage.

7. Develop a preliminary opinion as tothe probable performance of thefacilities, in the event of thedesignated earthquake groundmotion (see item 5 above) using theperformance levels contained inFEMA-273 and FEMA-310.

8. Prepare a written reportdocumenting the scope of study, thefindings and recommendations, withwritten documentation of theevaluation process (FEMA-310checklists, calculations, etc.)included as appendices. Ifpreliminary study indicatessignificant potential for earthquakeinduced ground failure and sufficientsite specific soils data was notavailable to conclusively assess this,the report should include arecommendation for site specificgeotechnical investigation. If theexisting construction of the structureis not sufficiently well defined topermit quantification of its structuralcharacteristics, includerecommendations for detailed fieldinvestigations to confirm theconstruction.



Phase II – Detailed Investigation andConceptual Retrofit Design

9. Review the phase I evaluation reportand available constructiondocuments for the facility to developan overall understanding of thebuilding’s construction and itsprobable seismic performance.

10. Conduct a visual survey of thebuilding to observe the buildingcondition and note obviousdeviations from the availabledocumentation. Observe potentialopportunities for introduction ofseismic upgrade elements. Notesensitive areas of the building, suchas historic spaces, traffic corridors,etc. that may not be impacted byseismic upgrade measures.

11. Meet with the facility manager todiscuss alternative performancecriteria and to select an appropriatecriteria, or set of criteria. Alsodiscuss restrictions on placement ofretrofit elements, relative to buildingappearance and functionalityconcerns.

12. If recommended in the phase Ievaluation, perform fieldinvestigation of the building toconfirm the details of its constructionand material strengths.

13. If recommended in the phase Ievaluation, obtain site-specificgeotechnical data to evaluatepotential ground failure andassociated mitigation measures.

14. Perform structural engineeringcalculations to quantify seismicdeficiencies in the building relative to

the selected performance levels. Asa minimum, the criteria of FEMA-310for a Tier 2 evaluation should beperformed. Alternatively, theperformance analysis procedurescontained in the California BuildingCode, Division IIIR, or in FEMA-273,or in the California Seismic SafetyCommission’s SSC-96-01 may beused.

15. Review alternative potential methodsfor seismic upgrade for eachspecified performance criteria, to alevel sufficient to confirm feasibilityand to select a recommendedapproach. Meet with the facilitymanager to review the alternativesand to agree on the appropriatenessof the recommended approach.

16. Develop conceptual level upgradedesigns for each specifiedperformance criteria. Supportingcalculations shall be performed to asufficient level of detail to confirmthat the overall size and scope of therecommendations are appropriate.The level of detail should besufficient to permit a rough order ofmagnitude cost estimate to beperformed. Consideration should begiven to collateral upgradestriggered by the seismic work,including disabled access, fire/lifesafety and other code upgrades.

17. Prepare conceptual level sketchesshowing recommended upgrades fornon-structural components.

18. Prepare preliminary cost estimatesfor the recommended seismicupgrade work, for each performance


Proposition 122 Product 2.2F-4 Earthquake Risk Management: A Toolkit For Decision-Makers

criteria, together with requiredcollateral upgrades.

19. Prepare a report indicating thescope of the study, the findings withregard to building deficiency andperformance and therecommendations for alternativelevels of upgrade, as well as anyrecommendations for additionalinvestigation to be performed as partof final design. Include schematicdrawings documenting the upgraderecommendations and costestimating work sheets in anappendix.

Phase III – Construction Documents andConstruction Support

1. Assemble a complete design teamincluding project management,structural engineering, architecture,mechanical and electricalengineering, and cost estimating, asrequired to support the developmentof construction documents.

2. Review all available documentationfor the building as well as previousevaluation reports and supportingcalculations in order to develop anunderstanding of the buildingdeficiencies and recommendedupgrade approach.

3. Meet with the building official, asnecessary to confirm the designcriteria and proposed approach, aswell as to confirm the extent ofrequired collateral upgrades.

4. Develop construction documentsincluding drawings andspecifications, together with

supporting calculations, toimplement the recommendedstructural upgrades, together with allrequired collateral upgrades. Submitcopies of construction documents toclient for review, at the 40%, and90% stages of completion. Finalconstruction documents shall besuitable for obtaining buildingpermits, competitive constructionbids, and for executing the work.

5. Prepare an estimate of probableconstruction cost at each stage ofdocument submittal and for the finalconstruction documents.

6. Provide support to client indevelopment of bid packages forconstruction contracts.

7. Respond to comments from plancheckers and revise constructiondocuments as necessary to obtainapproval.

8. Respond to bidder requests forclarification.

9. Provide support to client inevaluation of construction contractbids for completeness andconsistency with the requirements ofthe construction documents.

10. Attend periodic meetings at theconstruction site, during theconstruction period to coordinatewith construction progress.

11. Conduct periodic site visits toconfirm that the work is generallybeing conducted in accordance withthe design requirements.



12. Review contractor submittals andshop drawings.

13. Respond to contractor Requests forInformation and assist client innegotiation of contractor changeorder requests.

14. Review special inspection and testreports.

15. Perform a walkthrough of the projectsite at 95% completion to develop apunchlist of items not completed bycontractor.

Worksheet 1-A: Decision Hierarchy

POLICY DECISIONS – MADE BEFORE RISK ASSESSMENT

Decision-Maker: For each facility-type and earthquake event, choose and circle the appropriateperformance objective: Operational (O), Immediate Occupancy (IO), Life Safe (LS), CollapsePrevention (CP) or Not Considered (N). Also choose and circle a corresponding enforcementalternative: required (R) or encouraged (E). For precise definitions of facility-types, seeWorksheet 1-B for examples. For precise definitions of performance objectives, see Table 3-4.

Facility typeMPE

(500 year)LE

(100 year) Mandate

Essential public facilities O IO LS CP N O IO LS CP N R E

Public facilities with vulnerable occupants O IO LS CP N O IO LS CP N R E

Other public facilities O IO LS CP N O IO LS CP N R E

Private commercial - emergency response O IO LS CP N O IO LS CP N R E

Private commercial with hazardous materials O IO LS CP N O IO LS CP N R E

Private commercial – essential operations O IO LS CP N O IO LS CP N R E

Private commercial - ordinary operations O IO LS CP N O IO LS CP N R E

Other private commercial O IO LS CP N O IO LS CP N R E

Multi-family residential O IO LS CP N O IO LS CP N R E

Single-family residential O IO LS CP N O IO LS CP N R E

Historic O IO LS CP N O IO LS CP N R E

STRATEGIC DECISIONS – MADE AFTER RISK ASSESSMENT

The Risk Manager will collect information on all facilities with a performance objective other than“N” in the table above. With the aid of the Asset Manager and engineering consultants, the RiskManager will evaluate each facility to determine if it is capable of meeting the selectedperformance objective. For those facilities that do not meet these objectives, the Risk Manager,assisted by the Asset Manager and engineering consultants, will recommend mitigationalternatives and select the alternative that best meets the stated objective. The Risk Manager willprovide the Decision-Maker with cost and benefit information necessary to evaluate therecommendation and make the final decision.

Worksheet 1-B – Facility-type Definition

Risk Manager: Unambiguously define each facility-type you will use (e.g., by zoning or use code, by exactaddress, etc.) to prevent misunderstanding on the category of any particular facility. Decision-Maker:Adjust or endorse this classification system.

(A) Facility-type (B) Examples; notes (C) Zoning or use codes,addresses

Essential public facilities

Fire & police stations, hospitals,emergency operation &communication facilities, water supplyfacilities

Public facilities withvulnerable occupants

Schools, non-emergency medicalfacilities, correctional facilities,nursing homes

Other public facilities

Libraries, office buildings, publicworks equipment yards, localvehicular bridges, wastewatertreatment facilities

Private commercial -emergency response

Telephone switching facilities, privateambulance services, private medicalfacilities

Private commercial -hazardous materials

Chemical and gas manufacturers anddistributors, industrial facilities

Private commercial -essential operations

Bank data processing centers,customer service centers,manufacturing facilities in certainhigh-tech industries

Private commercial - ordinaryoperations

Research & development facilities,warehouses, retail, wholesale,service, transportation, constructionfacilities

Other private commercialfacilities Other facilities

Multi-family residentialApartment buildings, condominiumassociations

Single-family residential1Detached or attached single-familydwellings.

HistoricLocal, state, or national historicregistry

1 Public agencies rarely examine seismic risk for single-family residences, except in the case of unreinforcedmasonry (URM) buildings.

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Worksheet 3 – Rapid Building Screening1

1 Adapted from FEMA-154 Rapid Visual Screening and Data Collection Form

Worksheet 4 – Building Assessment

Facility: Date:

Engineer: Interest Rate Employed:

PRESENT VALUE OF RETROFIT COSTS

Retrofit OptionBest

Estimate ($)Contingency1

($)Duration2

(months)

Do Nothing (As-is Conditions) - -




1 Contingency is an amount held in reserve to account for unforeseen conditions.2 Duration is an indication of the amount of time required to implement the retrofit.

LOSS ESTIMATES

MPE (500-Year) LE (100-Year)

Retrofit Option Loss Item Best3 High3 Best High

As-is Conditions Repair Cost

Loss-of-Use4


Loss-of-Use3


Loss-of-Use3


Loss-of-Use3

3 The “best” estimate is the engineer’s estimate of the most probable outcome. There should be roughly a50% chance that the actual outcome would be either higher or lower than this estimate. The “high”estimate represents the engineer’s estimate associated with a high confidence of non-exceedance.Engineers familiar with the performance of Probable Maximum Loss estimates will associate this “high”estimate with a PML.

4 Loss-of-Use is the duration (measured in days or months) of the time that the facility will not fulfill itsnormal function.

Worksheet 5 – Equipment Assessment

Equipment System: Type (circle one): Damage / Life-safety / BI

Inspector: Date:

MitigationOption

Risk ScoreS

BestEstimate

HighEstimate

As-is (do nothing): - - By EI

Option 1: By EI

Option 2: By EI

Loss-of-use Costs for Failure (from Worksheet 6)

UGF (1 hr) UGF (1 week) UGF (1 day) UGF (1 month)

Case Loss Items MPE (500-year) LE (100-year)

As-isRepair Cost, R (Best $ Estimate): By EI




Loss-of-Use Cost, U = 10-S ⋅UGF:











Maximum repair cost Rmax (from Risk Manager or Asset Manager): $

Worksheet 6 – Loss-of-Use by Facility

Expert(s): Date:

Facility:

Financial Manager: Provide best estimates of dollar costs resulting from this facility being out ofoperation for various durations. Assume the building is safe to enter to remove documents andequipment, but elevators, electric power, water, etc., are unavailable. Total UGF = sum of column

$ Units (circle one) = dollars / hundreds / thousands / millions

Loss-of-Use Duration

Cost Item 1 hour 1 day 1 week 1 month

Extra Rent: 0 0

Movers: 0 0

Production Losses:

Outsourcing Costs: 0

Loss of Market Share: 0 0

Extra Marketing: 0 0

Overtime: 0 0

Other:

Total UGF

State of CaliforniaGray Davis, Governor

Seismic Safety Commission

Where Can I Get MoreInformation?

1755 Creekside Oaks Drive, Suite 100Sacramento, California 95833

http://www.seismic.ca.govPhone: (916) 263-5506

FAX: (916) 263-0594

Prepared for the California Seismic Safety Commission by EQE International, Inc.

Copyright © 1999 California Seismic Safety Commission

Five case studies ofsuccessful earthquakehazard mitigationprojects within Califor-nia have been broughttogether in the Califor-nia Seismic SafetyCommission publica-tion:


MitigationSuccess Stories

(SSC Report 99-05)

This companion resourceillustrates the practicalaspects of the risk man-agement decision-makingprocess, offering valuablelessons and insight.These studies also showthat earthquake risk man-agement can be a finan-cially viable endeavor,especially when all of thecosts of potential losses,direct or otherwise, arefully considered.


Mitigation SuccessStories

California SeismicSafety Commission

Proposition 122 Seismic Retrofit Practices ImprovementProgram Product 2.2 Earthquake Risk Management Tools forDecision-MakersReport SSC 99-XX