Risk Management Series

Engineering Guideline

for Incremental Seismic

Rehabilitation

FEMA P-420 / May 2009

FEMA
Cover Photo: Courtesy of University of California, Berkeley. 

Steel Braced Frames were added to Hildebrand Hall at the University of California, Berkeley as part 

of a seismic rehabilitation for this building, which houses the College of Chemistry. The University 

received funding through FEMA’s Hazard Mitigation Grant Program to complete this and other 

seismic rehabilitation projects on the Berkeley campus. 
Engineering Guideline

for Incremental Seismic

Rehabilitation

FEMA P-420 / May 2009
Any opinions, findings, conclusions, or 

recommendations expressed in this publication 

do not necessarily reflect the views of FEMA. 

Additionally, neither FEMA or any of its 

employees makes any warrantee, expressed or 

implied, or assumes any legal liability or 

responsibility for the accuracy, completeness, or 

usefulness of any information, product, or 

process included in this publication. Users of 

information from this publication assume all 

liability arising from such use. 
Acknowledgements

This document was prepared by the Applied 

Technology Council for the Federal Emergency 

Management Agency 

Principal Authors: 

Frederick Krimgold, Virginia Tech Center for Disaster Risk 

Management, Virginia Polytechnic Institute and State 

University, Arlington, Virginia 

Melvyn Green, Melvyn Green & Associates Inc., Torrance, 

California 

David Hattis, Building Technology Inc., Silver Spring, 

Maryland 

Barry Welliver, BHW Engineers, Draper, Utah 

Jon A. Heintz, Applied Technology Council, Redwood City, 

California 

Contributors: 

Edwin Dean, Nishkian Dean, Portland, Oregon 

Reviewers: 

William T. Holmes, Rutherford & Chekene, San Francisco, 

California 

Thomas R. McLane, Applied Technology Council, Arlington, 

Virginia 

Ugo Morelli, FEMA (Retired), Washington, DC 

Lawrence Reaveley, University of Utah, Salt Lake City, Utah 

Christopher Rojahn, Applied Technology Council, Redwood 

City, California 

Charles Scawthorn, SPA Risk LLC, Denver, Colorado 

FEMA Project Monitor: 

Cathleen M. Carlisle, Washington, DC 

Production: 

Peter Mork, Applied Technology Council, Redwood City, 

California 

 iii 

 Contents 

Contents 

List of Figures................................................................................ vii 

List of Tables................................................................................. ix 

Foreword ....................................................................................... xi 

Chapter 1 Introduction to Incremental Seismic 

Rehabilitation ......................................................... 1-1 

1.1 Background ...................................................... 1-1 

1.2 What is Incremental Seismic Rehabilitation? ......... 1-1 

1.3 Are Incremental Seismic Rehabilitation 

Approaches Currently Being Used? ...................... 1-2 

1.4 The FEMA Incremental Seismic Rehabilitation 

Series .............................................................. 1-2 

1.5 Scope, Organization, and Content ....................... 1-3 

Chapter 2 Incremental Compared to Single-Stage Seismic 

Rehabilitation ......................................................... 2-1 

2.1 Options for Seismic Risk Reduction ...................... 2-1 

2.2 How Do the Benefits of Incremental and SingleStage Seismic Rehabilitation Compare? ................ 2-2 

2.3 The Approach to Incremental Seismic 

Rehabilitation ................................................... 2-4 

2.3.1 Elements of an Incremental Seismic 

Rehabilitation Program ............................ 2-4 

2.4 How do Engineering Services for Incremental 

Seismic Rehabilitation Differ from Typical 

Engineering Practice? ........................................ 2-6 
iv

Engineering Guideline for Incremental Seismic Rehabilitation 

2.4.1 Development of an Incremental Seismic 

Rehabilitation Plan .................................. 2-6 

2.4.2 Analysis and Design ................................ 2-6 

2.4.3 Special Design Considerations .................. 2-7 

2.4.4 Preparation of Construction Documents ..... 2-7 

2.4.5 Plan Check and Permitting ........................ 2-7 

2.4.6 Implementation of an Incremental 

Seismic Rehabilitation Plan over Time ........ 2-8 

2.5 How Does Incremental Seismic Rehabilitation 

Affect Liability? .................................................. 2-9 

Chapter 3 Owner/Operator Perspectives on Incremental 

Seismic Rehabilitation............................................. 3-1 

3.1 Owner/Operator Objectives: Revenue Generation, 

Equity, and Service Delivery ............................... 3-1 

3.2 Hazard, Vulnerability, and Risk ............................ 3-2 

3.3 Overview of the Facility Management Process ....... 3-3 

3.3.1 Integration of Incremental Seismic 

Rehabilitation Program Elements ............... 3-5 

3.4 The “Educated Client” Perspective ....................... 3-6 

3.5 Communicating with Multiple Client Audiences ...... 3-6 

3.5.1 Facility Managers .................................... 3-7 

3.5.2 Risk Managers ........................................ 3-7 

3.5.3 Financial Managers .................................. 3-7 

Chapter 4 Codes and Standards for Seismic Evaluation and 

Rehabilitation.......................................................... 4-1 

4.1 Seismic Rehabilitation in Building Codes and 

Standards ......................................................... 4-1 

4.1.1 Mandated Rehabilitation ........................... 4-2 

4.1.2 Triggered Rehabilitation ........................... 4-2 

4.1.3 Voluntary Rehabilitation ........................... 4-2 

4.2 Code Rationalizations for Incremental Seismic 

Rehabilitation .................................................... 4-2 

4.2.1 Voluntary Changes to the Seismic-ForceResisting System .................................... 4-3 

4.2.2 Repairs, Alterations, Additions, and 

Changes of Occupancy ............................. 4-3 

4.2.3 Pre-2000 Legacy Codes ........................... 4-4 

Chapter 5 Incremental Seismic Rehabilitation Engineering 

Process................................................................... 5-1 

5.1 Engineering Phases of an Incremental Seismic 

Rehabilitation Program ....................................... 5-1 
 v 

 Contents 

5.2 Engineering Resources Referenced in the FEMA 

ISR Series ....................................................... 5-2 

5.3 Performance-Based Seismic Design .................... 5-3 

5.3.1 Performance-Based Design Process ........... 5-4 

5.4 Incremental Seismic Rehabilitation Basic 

Information ...................................................... 5-5 

5.4.1 Building Type ......................................... 5-5 

5.4.2 Seismic Hazard Level .............................. 5-7 

5.4.3 Performance Objectives ........................... 5-9 

5.5 Due Diligence Analysis ..................................... 5-10 

5.6 Seismic Screening ........................................... 5-10 

5.7 Seismic Evaluation .......................................... 5-13 

5.8 Seismic Rehabilitation Planning for Specific 

Buildings ........................................................ 5-15 

5.8.1 Incremental Seismic Rehabilitation 

Plan .................................................... 5-15 

5.8.2 Design of Rehabilitation Measures ........... 5-16 

5.8.3 Prioritization of Rehabilitation 

Measures ............................................. 5-18 

5.8.4 Identification of Integration 

Opportunities ....................................... 5-22 

5.8.5 Definition of Appropriate Rehabilitation 

Increments .......................................... 5-23 

5.9 Staging Seismic Rehabilitation Increments ......... 5-24 

5.9.1 Coordination with Tenant Work ............... 5-24 

5.10 Seismic Rehabilitation Project Management ........ 5-24 

Chapter 6 Incremental Seismic Rehabilitation Needs and 

Possibilities ............................................................ 6-1 

6.1 Political, Social, and Economic Possibilities ........... 6-1 

6.2 How Can Incremental Seismic Rehabilitation 

Affect Decision-Making and Program 

Management? ................................................... 6-2 

6.3 What is needed to Further Promote Incremental 

Seismic Rehabilitation? ...................................... 6-2 

6.4 Summary and Conclusions ................................. 6-3 

Appendix A Case Study Example – Seattle Public Schools 

Incremental Seismic Rehabilitation Program ........... A-1 

A.1 Introduction ..................................................... A-1 

A.2 Regulatory Context ........................................... A-2 

A.3 Seismic Screening of the Building Inventory ......... A-2 

A.4 Seismic Evaluation of Individual Buildings ............ A-3 
vi

Engineering Guideline for Incremental Seismic Rehabilitation 

A.5 Seismic Rehabilitation Planning and Design .......... A-4 

A.6 Staging of Seismic Rehabilitation Increments ....... A-5 

A.6.1 Capital Levy Program (1982-1999) ........... A-5 

A.6.2 Buildings, Technology and Athletics 

Levy (1998-2004) .................................. A-6 

A.7 Local Jurisdictional Issues .................................. A-7 

A.8 Legal/Liability Issues ......................................... A-7 

Appendix B Case Study Example – Staging of Seismic 

Rehabilitation Increments ...................................... B-1 

B.1 Building Description .......................................... B-1 

B.2 Regulatory Context ........................................... B-2 

B.3 Rehabilitation Measures ..................................... B-3 

B.4 Staging of Seismic Rehabilitation Increments ....... B-4 

Appendix C Other Existing Building Resource Documents ......... C-1 

C.1 Relevant Resources from the FEMA Existing 

Buildings Program ............................................ C-1 

C.2 Other Existing Building Resource Documents ....... C-2 

References .............................................................................. R-1 
 vii 

 List of Figures 

List of Figures 

Figure 2-1 Options for Seismic Risk Reduction (FEMA ISR Series) ...... 2-1

Figure 2-2 Comparison of generalized life-cycle benefit/cost analyses: 

(top) relative benefit of single-stage rehabilitation projects 

conducted at different times; (bottom) step-function of an 

incremental rehabilitation project overlayed onto singlestage rehabilitation results ............................................ 2-3 

Figure 3-1 Simplified seismic hazard map showing red, yellow, and 

green areas indicating regions of high, moderate, and low 

seismicity, respectively (FEMA ISR Series) ...................... 3-2 

Figure 3-2 Typical sequential facility management process 

(FEMA ISR Series) ....................................................... 3-4 

Figure 3-3 Influences on the facility management process used in 

commercial office buildings (FEMA 397) .......................... 3-5 

Figure 3-4 Integration of typical incremental rehabilitation program 

elements within the typical sequential facility management 

process (FEMA ISR Series) ............................................ 3-6 

Figure 5-1 Integration of engineering services within the typical 

sequential facility management process (FEMA ISR 

Series) ....................................................................... 5-2 

Figure 5-2 Performance-based design flowchart (ATC, 2003) ............ 5-4 

Figure 5-3 FEMA 154 simplified seismic hazard map (FEMA, 2002) .... 5-8 

Figure 5-4 ASCE 31 Levels of Seismicity Definitions (ASCE, 2003) ..... 5-8 

Figure 5-5 Seismic performance objectives linking building 

performance levels to earthquake hazard levels 

(adapted from SEAOC, 1995) ........................................ 5-9 
viii

Engineering Guideline for Incremental Seismic Rehabilitation 

Figure 5-6 FEMA 154 data collection forms for Low, Moderate, and 

High regions of seismicity ............................................ 5-12 

Figure 5-7 Excerpt from the Basic Structural Checklist for Building 

Type C2: Concrete Shear Walls with Stiff Diaphragms 

(ASCE, 2003)............................................................. 5-14 

Figure 5-8 ASCE 41 Target Building Performance Levels 

(ASCE, 2006b). .......................................................... 5-17 

Figure 5-9 ASCE 41 Rehabilitation Objectives (ASCE, 2006b) .......... 5-17 

Figure 5-10 Tables of ranked deficiencies for Steel Moment Frame 

and Steel Braced Frame model building types 

(ASCE, 2006b) ........................................................... 5-19 

Figure 5-11 Excerpt from table of structural seismic performance 

improvements (FEMA 395) .......................................... 5-19 

Figure 5-12 Excerpt from table of nonstructural seismic 

performance improvements (FEMA 395) ........................ 5-20 

Figure 5-13 Prioritization of work based on integration opportunities: 

(1) roof work; (2) exterior wall work; and (3) localized 

interior work (FEMA ISR Series) ................................... 5-21 

Figure 5-14 Integration opportunities for roofing maintenance and 

repair (FEMA 400) ...................................................... 5-22 

Figure 5-15 Classification of integration opportunities by extent of 

engineering required (FEMA ISR Series) ........................ 5-23 

Figure B-1 Portion of the incremental seismic rehabilitation process 

illustrated in the case study example of Appendix B ......... B-2 

Figure B-2 First floor plan and rehabilitation increments 

(graphic courtesy of M. Green) ...................................... B-5 

Figure B-3 Second floor plan and rehabilitation increments 

(graphic courtesy of M. Green) ...................................... B-6 

Figure B-4 Building cross-section and rehabilitation increments 

(graphic courtesy of M. Green) ...................................... B-7 
 ix 

 List of Tables 

List of Tables 

Table 5-1 Comparison of Building Classifications in Various FEMA 

ISR Reference Documents ............................................... 5-6 

Table A-1 Seattle Public Schools Capital Levy Projects 1982-1999 ...... A-6 

Table A-2 Buildings, Technology and Athletics Levy Projects with 

Dedicated Seismic Work .................................................. A-8 

 xi 

 Foreword 

Foreword 

Initial cost and loss of normal building use have been cited as major 

obstacles to implementation of seismic rehabilitation. The Federal 

Emergency Management Agency (FEMA) has published a series of 

occupancy-specific manuals for building owners that presents incremental 

strengthening of buildings in discrete stages as a way of managing costs 

and minimizing disruption associated with seismic rehabilitation projects. 

Incremental strengthening was initially conceptualized for school buildings 

under a grant from the National Science Foundation to Building 

Technology Incorporated. The FEMA manuals are the result of a series of 

projects funded by FEMA and others dating back to the 1980s, which 

investigated financial incentives for seismic rehabilitation of existing 

hazardous buildings, physical seismic rehabilitation potential, and 

institutional capacity for mitigation investment. Work was conducted by a 

team of consultants led by the World Institute for Disaster Risk 

Management in association with Virginia Polytechnic Institute and State 

University, Building Technology Incorporated, Melvyn Green Associates, 

EQE Incorporated, and George Washington University. Early on, these 

projects concluded that a strategy for integrating the planning and 

implementation of seismic strengthening into the overall facility 

maintenance and capital improvement process was needed. 

The strategy was referred to as incremental seismic rehabilitation, and the 

resulting manuals present seismic rehabilitation within the context of the 

specific facility management, risk management, and financial management 

needs and practices of building owners. At present these manuals 

include: 

 FEMA 395, Incremental Seismic Rehabilitation of School 

Buildings (K-12)

 FEMA 396, Incremental Seismic Rehabilitation of Hospital 

Buildings 
xii

Engineering Guideline for Incremental Seismic Rehabilitation 

 FEMA 397, Incremental Seismic Rehabilitation of Office Buildings 

 FEMA 398, Incremental Seismic Rehabilitation of Multifamily 

Apartment Buildings

 FEMA 399, Incremental Seismic Rehabilitation of Retail Buildings 

 FEMA 400, Incremental Seismic Rehabilitation of Hotel and 

Motel Buildings 

The technical feasibility and economic viability of incremental seismic 

rehabilitation has been studied and validated. This Engineering Guideline 

for Incremental Seismic Rehabilitation is intended as a technical resource 

for design professionals who are implementing incremental seismic 

rehabilitation on their projects or advocating the use of an incremental 

approach to seismic rehabilitation in practice. It explains the concept of 

incremental seismic rehabilitation as a strategy, discusses owner 

maintenance, capital improvement and decision-making processes as a 

basis for communicating with decision-makers on seismic rehabilitation 

opportunities, summarizes available engineering resource documents, and 

outlines the overall engineering process for incremental seismic 

rehabilitation of buildings. 
 1-1 

 Chapter 1 

Chapter 1 Introduction to 

Incremental Seismic 

Rehabilitation 

1.1 Background 

The Federal Emergency Management Agency (FEMA) has published a 

series of occupancy-specific manuals for building owners that presents 

incremental strengthening of buildings in discrete stages as a way of 

managing costs and minimizing disruption associated with seismic 

rehabilitation projects. This series is based on the postulate that 

incremental improvement is better than delayed improvement or no 

improvement at all, and that seismic rehabilitation in existing buildings 

would occur more frequently if initial costs and functional disruption could 

be reduced. 

The concept of “incremental seismic rehabilitation” has been applied in 

various situations for different building types and occupancies around the 

country. It offers a way of eliminating some of the barriers to 

implementation of seismic rehabilitation, and innovative structural 

engineers have developed and implemented various aspects of this 

concept in practice. The purpose of the FEMA Incremental Seismic 

Rehabilitation Series is to elevate this occasional, ad hoc practice to the 

level of a general strategy for reduction of earthquake risk in existing 

buildings and expansion of seismic rehabilitation activities throughout the 

United States. 

1.2 What is Incremental Seismic Rehabilitation? 

Incremental seismic rehabilitation is an approach to seismic rehabilitation 

that integrates an ordered series of discrete rehabilitation actions into 

In Brief 

This chapter: 

 Defines incremental 

seismic rehabilitation 

 Explains where 

incremental seismic 

rehabilitation is being 

used 

 Describes the 

manuals in the FEMA 

Incremental Seismic 

Rehabilitation Series 

 Outlines the scope, 

organization, and 

content of this manual 
1-2

Engineering Guideline for Incremental Seismic Rehabilitation 

ongoing facility maintenance and capital improvement activities over an 

extended period of time. The process involves a series of projects that are 

planned around regularly scheduled building maintenance, repairs, or 

renovations, and are timed to coincide with periods of reduced occupancy 

or use. 

Initial cost and loss of normal building use have been cited as major 

obstacles to investment in seismic rehabilitation. The concept of 

incremental seismic rehabilitation is specifically designed to remove these 

obstacles. The underlying assumption is that integration of seismic 

rehabilitation work into normal building operation and maintenance cycles 

significantly reduces cost and disruption because scaffolding and other 

construction equipment are in place, work surfaces are exposed, 

occupants are already displaced, and interruptions in use are already 

accommodated. 

1.3 Are Incremental Seismic Rehabilitation Approaches 

Currently Being Used? 

Incremental seismic rehabilitation was initially conceptualized for school 

buildings. An incremental approach to seismic rehabilitation has been 

practiced by Seattle Public Schools in Seattle, Washington for more than 

25 years. This program was studied in detail, and contributed significantly 

to the approach described in the FEMA Incremental Seismic Rehabilitation 

Series. The Seattle Public Schools program is presented as a case study 

in Appendix A. 

Incremental seismic rehabilitation has also been utilized by schools in 

other areas, such as the Jordan and Davis County School Districts in Utah. 

In these school districts, rehabilitation measures that can be accomplished 

over the summer months have been implemented in many older school 

buildings. 

For the most part, use of incremental seismic rehabilitation to date has 

been the result of individual creative efforts on the part of innovative 

design professionals and building owners on a project-by-project basis. 

One such individual project is presented as a case study in Appendix B. In 

some jurisdictions incremental approaches have been written into seismic 

strengthening ordinances, such as the Earthquake Hazard Reduction 

Ordinance (City of Los Angeles, 1981) addressing unreinforced masonry 

buildings in the City of Los Angeles, California. 

1.4 The FEMA Incremental Seismic Rehabilitation 

Series 

Each manual in the FEMA Incremental Seismic Rehabilitation (ISR) Series 

addresses seismic rehabilitation within the context of the specific facility 

management, risk management, and financial management needs and 

practices within a particular type of occupancy. The manuals are written 

for building owners, operators, and other decision-makers, and provide 

guidance on how to integrate seismic rehabilitation into the overall 

building maintenance and capital improvement process. 
 1-3 

 Chapter 1 

At present, the FEMA ISR Series includes the following manuals: 

 FEMA 395, Incremental Seismic Rehabilitation of School 

Buildings (K-12) (FEMA, 2003) 

 FEMA 396, Incremental Seismic Rehabilitation of Hospital 

Buildings (FEMA, 2003) 

 FEMA 397, Incremental Seismic Rehabilitation of Office Buildings

(FEMA, 2003) 

 FEMA 398, Incremental Seismic Rehabilitation of Multifamily 

Apartment Buildings (FEMA, 2004) 

 FEMA 399, Incremental Seismic Rehabilitation of Retail Buildings

(FEMA, 2004) 

 FEMA 400, Incremental Seismic Rehabilitation of Hotel and 

Motel Buildings (FEMA, 2004) 

1.5 Scope, Organization, and Content 

This guide is a companion to the FEMA ISR Series of occupancy manuals. 

It is intended as a technical resource for design professionals who are 

implementing incremental seismic rehabilitation on their projects or 

advocating the use of an incremental approach to seismic rehabilitation in 

practice. It explains the concept of incremental seismic rehabilitation as a 

strategy, discusses owner maintenance, capital improvement and 

decision-making processes as a basis for communicating with decisionmakers on seismic rehabilitation opportunities, summarizes available 

engineering resource documents, and outlines the overall engineering 

process for incremental seismic rehabilitation of buildings. 

Chapter 1 provides background information and introduces the concept of 

incremental seismic rehabilitation. 

Chapter 2 explains the incremental seismic rehabilitation process and 

compares it to single-stage rehabilitation. 

Chapter 3 discusses building owner perspectives on seismic rehabilitation 

and outlines the maintenance and capital improvement decision-making 

processes. 

Chapter 4 summarizes available engineering resource documents and 

how to use them in the context of incremental seismic rehabilitation. 

Chapter 5 outlines the basic information and overall engineering process 

for incremental seismic rehabilitation of buildings. 

Chapter 6 discusses future needs and possibilities for incremental seismic 

rehabilitation. 

Appendix A presents a case study of how an overall program has been 

implemented in the Seattle Public Schools incremental seismic 

rehabilitation program. 
1-4

Engineering Guideline for Incremental Seismic Rehabilitation 

Appendix B presents a case study illustrating how seismic rehabilitation 

increments were staged in an individual building located in Southern 

California. 

Appendix C lists relevant existing building resource documents from the 

FEMA Existing Buildings Program and other sources, which could be 

applicable to the development and implementation of an incremental 

seismic rehabilitation program. 
 2-1 

 Chapter 2 

Chapter 2 Incremental Compared 

to Single-Stage Seismic 

Rehabilitation 

2.1 Options for Seismic Risk Reduction 

In vulnerable buildings, the risk of structural collapse poses the single 

greatest threat in a major earthquake. Beyond collapse, additional risks 

include casualties, injuries to building occupants, damage to nonstructural 

components and systems, loss of property, and loss of use. Options for 

reducing seismic risk in existing buildings are shown in Figure 2-1: 

Figure 2-1 Options for Seismic Risk Reduction (FEMA ISR Series). 

In Brief 

This chapter: 

 Compares 

incremental seismic 

rehabilitation to 

single-stage 

rehabilitation 

 Highlights differences 

in engineering 

practice 

 Discusses how 

incremental seismic 

rehabilitation affects 

liability 
2-2

Engineering Guideline for Incremental Seismic Rehabilitation 

These options include the following actions: 

Do Nothing. No capital investment is made in improving structural or 

nonstructural performance. This option can include the purchase of 

earthquake insurance or a plan to self-insure for capital losses. 

Replace. Demolition and reconstruction is carried out in accordance with 

current building codes. This alternative is generally associated with the 

greatest cost and lowest overall risk. Financial constraints, historic 

preservation concerns, and zoning restrictions can make replacement 

difficult or infeasible. 

Rehabilitate. Also referred to as “retrofit” or “strengthening,” 

rehabilitation involves capital investment to improve the structural 

performance, nonstructural performance, or both. 

Consideration of cost and disruption associated with seismic rehabilitation 

leads to two additional options: 

Single-Stage Rehabilitation. Rehabilitation that meets all seismic 

performance objectives in a single project, by incurring all costs and 

disruption of occupancy and use at one time. 

Incremental Rehabilitation. Rehabilitation that eventually meets 

seismic performance objectives by implementing an ordered series of 

discrete rehabilitation actions over an extended period of time. Often such 

work is integrated into ongoing facility maintenance and capital 

improvement operations. 

2.2 How Do the Benefits of Incremental and SingleStage Seismic Rehabilitation Compare? 

Annualized losses are the result of probable damage that can occur in any 

year from all possible earthquakes. The primary benefit of seismic 

rehabilitation is a reduction in damage that is likely to occur along with a 

corresponding reduction in annualized losses. Using information from 

FEMA 227, A Benefit-Cost Model for the Seismic Rehabilitation of Buildings

(FEMA, 1992) and FEMA 255, Seismic Rehabilitation of Federal Buildings: 

A Benefit/Cost Model (FEMA, 1994), it is possible to develop a life-cycle 

benefit/cost analysis that compares incremental to single-stage seismic 

rehabilitation. 

This benefit/cost analysis postulates a series of seismic rehabilitations 

undertaken over a range of time periods. Expected annual damage is 

calculated over an arbitrary remaining building service life (e.g., 50 years) 

and the benefits of rehabilitation (reduced damage) are discounted to a 

net present value for each rehabilitation scenario. Benefits are expressed 

as a percentage of the benefits achieved by a full seismic rehabilitation 

conducted in year zero, and the results are compared on a relative basis. 

Schematic diagrams in Figure 2-2 illustrate how the benefits of single-stage 

and incremental seismic rehabilitation scenarios vary over time. Figure 2-2 

(top) shows the relative benefits of single-stage rehabilitation projects 

occurring at year 0, year 20, and year 40. The largest benefit is derived 

from a single-stage rehabilitation project completed in the near term, 

designated as 100%. The relative benefits of single-stage rehabilitation 

projects occurring in later years are only a fraction of this value. 
 2-3 

 Chapter 2 

In Figure 2-2 (bottom), the benefits of an incremental seismic 

rehabilitation project are overlayed on the single-stage project results. In 

this example, the incremental program begins in year zero, and is 

completed in four increments over 20 years. The benefits of incremental 

stages of work completed in the future are discounted, so the relative 

benefit of the incremental program is less than the benefit of a singlestage rehabilitation conducted in year zero. But because increments of 

work are completed earlier, and corresponding benefits are realized 

sooner, the value of an incremental seismic rehabilitation project is higher 

than a single-stage project completed at the same time or later. 

Figure 2-2 Comparison of generalized life-cycle benefit/cost analyses: (top) 

relative benefit of single-stage rehabilitation projects conducted at 

different times; (bottom) step-function of an incremental rehabilitation 

project overlayed onto single-stage rehabilitation results. 
2-4

Engineering Guideline for Incremental Seismic Rehabilitation 

Such an analysis shows that a series of seismic rehabilitation increments 

conducted over a defined period of time can produce nearly as much 

benefit as a single-stage rehabilitation project conducted in year zero. 

While this example considers an incremental rehabilitation program 

occurring over a period of 20 years, this should not be considered a 

target. Reducing the overall duration of an incremental rehabilitation 

program will increase its benefit, and extending the duration will decrease 

it. There is a lasting value in overall risk reduction when work is 

completed early in the remaining service life of a building. Incremental 

seismic rehabilitation offers flexibility in the sequence and timing of 

rehabilitation actions, and can be more effective than a delayed, singlestage rehabilitation project. 

2.3 The Approach to Incremental Seismic Rehabilitation 

The approach to incremental seismic rehabilitation involves identification 

of seismic risk and seismic vulnerabilities, development of specific actions 

to rehabilitate potential deficiencies, and prioritization of work into a plan 

that takes advantage of ongoing maintenance or capital improvement 

activities over time. Incremental seismic rehabilitation terms, and their 

use, are defined below. 

Rehabilitation measures are specific actions that are taken to improve the 

seismic performance of existing structural and nonstructural components. 

Integration opportunities are ongoing maintenance and capital 

improvement projects that could be expanded to include seismic 

rehabilitation measures. Rehabilitation increments (or stages) are 

collections of rehabilitation measures that have been grouped to take 

advantage of integration opportunities. A rehabilitation plan includes all 

anticipated rehabilitation increments and their prioritization. 

Rehabilitation objectives are statements of the intended seismic 

performance level (for both structural and nonstructural components) at a 

specified earthquake hazard level. 

A comprehensive incremental seismic rehabilitation program involves 

assessment of risk, planning and design to mitigate risk, budgeting and 

financing, and construction management. In such a program, 

rehabilitation measures are implemented in a series of rehabilitation 

increments, which have been scheduled based on available integration 

opportunities. Collectively, rehabilitation actions achieve the selected 

rehabilitation objective once all of the increments in a rehabilitation plan 

have been completed. 

2.3.1 Elements of an Incremental Seismic Rehabilitation Program 

In the FEMA ISR Series, typical elements of an incremental seismic 

rehabilitation program include: 

 Due Diligence Analysis 

 Operator Risk Reduction Standards 

 Initial Integration Opportunities 

 Seismic Screening 

 Seismic Evaluation 
 2-5 

 Chapter 2 

 Developing a Risk Reduction Policy 

 Seismic Rehabilitation Planning for Specific Buildings 

 Staging Seismic Rehabilitation Increments 

 Budget Packaging 

 Financial Packaging 

 Seismic Rehabilitation Project Management 

Most of these program elements are generally applicable within the facility 

management processes for all occupancy categories covered in the FEMA 

ISR Series. Some program elements, however, are occupancy-specific, 

and some occupancies have special elements. Many program elements 

require engineering services in order to implement. 

The elements of an incremental seismic rehabilitation program that require 

engineering services are listed below, along with a brief description of the 

type of engineering services needed. Implementation of incremental 

seismic engineering processes is described in more detail in Chapter 5. 

Due Diligence Analysis. Due diligence analysis is an activity required by 

investors, lenders, and insurance companies to identify potential risks that 

might be incurred in a real estate transaction. Potential risks can include 

seismic risk, and due diligence analysis can be used to avoid acquiring 

buildings with seismic deficiencies that need rehabilitation. It can also be 

used to factor potential seismic risk and possible seismic rehabilitation into 

a plan for acquiring a specific building. Procedures for conducting due 

diligence analyses as part of an incremental seismic rehabilitation program 

are the same as typical engineering practice for single-stage projects. 

Seismic Screening. Seismic screening is a rapid, simple, preliminary 

assessment of potential seismic deficiencies. Typically it is used to assess 

and rank the seismic vulnerability of buildings within a portfolio of 

buildings, but it can also be used as a preliminary evaluation tool to get a 

sense of the possible seismic risk associated with an individual building. 

Procedures for conducting seismic screening as part of an incremental 

seismic rehabilitation program are the same as typical engineering 

practice for single-stage projects. 

Seismic Evaluation. Seismic evaluation is a more detailed assessment 

and confirmation of potential seismic deficiencies. Typically it is conducted 

on individual buildings that have been identified as vulnerable by a 

screening process. Procedures for conducting seismic evaluation as part 

of an incremental seismic rehabilitation program are the same as typical 

engineering practice for single-stage projects. 

Seismic Rehabilitation Planning for Specific Buildings. Incremental 

seismic rehabilitation differs most from typical engineering practice in this 

element. Planning for specific buildings involves the development of an 

incremental seismic rehabilitation plan, design and prioritization of 

rehabilitation measures, identification of integration opportunities, and 

definition of appropriate rehabilitation increments. 

Staging Seismic Rehabilitation Increments. In contrast with typical 

engineering practice for single-stage projects, staging of seismic 

rehabilitation increments involves phasing of work into appropriate stages, 
2-6

Engineering Guideline for Incremental Seismic Rehabilitation 

and development of an overall implementation timeline. Rehabilitation 

measures must be staged so that collectively, all seismic performance 

objectives are met when all increments have been completed, and that 

individually, no one increment leaves the building more vulnerable than 

when work was initiated. 

Seismic Rehabilitation Project Management. Seismic rehabilitation 

project management includes support during the construction phase. 

Similar to construction management or construction support services for 

single-stage projects, this phase involves ensuring that plans, 

specifications, and quality assurance provisions are properly implemented 

in the field. Additional construction support services may be required for a 

project that is staged in increments over several years. 

2.4 How do Engineering Services for Incremental 

Seismic Rehabilitation Differ from Typical 

Engineering Practice? 

Projects undertaken in a single stage generally have a short timeframe 

under which commencement and completion of the work is anticipated. 

With incremental seismic rehabilitation, work can extend over a period of 

years. In the FEMA ISR Series, building owners and operators are 

counseled to expect that implementation of incremental seismic 

rehabilitation will require more effort than typical design practice for 

single-stage projects. Development of an incremental rehabilitation plan, 

design of rehabilitation increments, negotiating plan check and permit 

approvals, performing construction support services, coordinating with 

tenant improvement activities, and tracking progress and completion of 

the work will all likely require special effort. 

In addition, there are other issues related to inevitable changes that can 

occur when a project is staged over an extended period of time. 

Similarities and differences between incremental seismic rehabilitation and 

typical engineering practice for single-stage projects are described below. 

2.4.1 Development of an Incremental Seismic Rehabilitation Plan 

An incremental seismic rehabilitation plan includes all anticipated 

rehabilitation increments and their prioritization. Such a plan is not part of 

typical engineering practice. An effective plan is one in which the 

rehabilitation increments are integrated into the facility management and 

capital improvement processes, which can vary with occupancy type. 

Development of an incremental seismic rehabilitation plan requires design 

professionals to understand the occupancy-specific facility management 

and decision-making processes to better identify integration opportunities. 

2.4.2 Analysis and Design 

The basic seismic analysis and design tools used in incremental seismic 

rehabilitation are the same as those used in typical engineering practice 

for single-stage projects. Currently available resources for seismic 

screening, evaluation, and rehabilitation, which have been published by 

FEMA and others, are described in Chapter 5 and Appendix C. 
 2-7 

 Chapter 2 

2.4.3 Special Design Considerations 

Because the premise of incremental seismic rehabilitation assumes that 

the building will be opportunistically upgraded over a period of time, there 

will be interim stages when the building is in a “partial” state of seismic 

upgrade. This requires that the design professional understand the 

potential consequences of prioritization and phasing of work. 

The overarching design consideration for incremental seismic rehabilitation 

is to “do no harm” to the building. Each increment of work must improve 

the overall seismic performance of the building, and no increment should 

leave the building in a condition that is more vulnerable than it was when 

work was initiated. Understanding the consequences of phasing, and 

effectively staging rehabilitation increments for improved performance, 

will likely require additional analyses of the partially upgraded building and 

multiple iterations in the design process. 

2.4.4 Preparation of Construction Documents 

Alternatives for the preparation of construction documents include: (1) 

separate documents for each rehabilitation increment; and (2) a single set 

of documents clearly defining the sequence and scope of work for each 

rehabilitation increment. 

Separate sets of construction documents have advantages with regard to 

permitting and construction phasing. Each increment is permitted 

separately, and each permit is closed out at the conclusion of the 

construction of each increment. This provides greater flexibility in the 

timing and completion of future increments of work. A possible 

disadvantage is that documentation for the work is split up among several 

sets of construction documents. This may make it more difficult to 

coordinate work between increments and to monitor progress toward 

ultimate completion. 

A single set of construction documents has advantages with regard to 

coordination and monitoring of work. With all information in one set of 

documents, it is more likely that rehabilitation measures in each increment 

are properly coordinated, and that no rehabilitation measures are 

inadvertently omitted. If all work is permitted under a single set of 

documents, it is also more likely that all increments of work will be 

completed. This has the possible disadvantage of reducing flexibility in 

the completion of future increments by forcing work to occur within the 

time frame of a single permit. 

2.4.5 Plan Check and Permitting 

Whether seismic rehabilitation work is voluntary or triggered by code 

requirements, incremental seismic rehabilitation may require special 

approvals in the plan check and permitting process. Negotiation with 

building officials may be required in determining appropriate increments 

that “do no harm” to the building, and in the sequence, scheduling, and 

completion of future increments of work. 
2-8

Engineering Guideline for Incremental Seismic Rehabilitation 

2.4.6 Implementation of an Incremental Seismic Rehabilitation Plan 

over Time 

As an incremental rehabilitation plan is implemented over time, potential 

changes from a variety of sources can affect the parameters on which a 

plan was based. Both owners and design professionals should be aware of 

the possible need to re-evaluate the elements of an incremental seismic 

rehabilitation plan, and make adjustments in the design and 

implementation of the plan, if needed. Sources of possible changes over 

time include: 

 Revisions to seismic codes and standards 

 Emerging building technologies, systems, and materials 

 Changes in building occupancy and use 

 Natural disasters or other events affecting the condition of the 

building 

 New building ownership 

 Owner financial status and evolving local market conditions 

 Owner strategic plans and changing priorities 

 Adjustments to maintenance and capital improvement plans 

 Turnover in professional design staff 

Changes in reference codes and standards, or in the condition of the 

building, have the potential to result in the need to re-design portions of 

the incremental seismic rehabilitation work in future years. An evolving 

financial climate could alter the perceived benefit/cost ratio of planned 

work. Changes in the status of building ownership, or in the priorities of 

the existing owner, can affect the implementation of future rehabilitation 

increments. 

In prioritizing and staging rehabilitation increments, design professionals 

should consider the possibility that future work may be delayed. During 

interim stages, while a building is in a state of partial upgrade, design 

professionals may find themselves in the position of advocating for the 

eventual completion of seismic rehabilitation work. This role is particularly 

important since building owners and other decision makers may not have 

seismic rehabilitation as their highest priority at all times. 

Implementation of an incremental seismic rehabilitation plan over time will 

be more successful if design and construction documentation is more 

rigorous and more easily retrievable than might otherwise be necessary 

for single-stage rehabilitation projects. Owners and design professionals 

should consider the need to carefully document each phase of incremental 

seismic rehabilitation work and anticipate scheduling of follow-up work. 

With proper documentation, institutional knowledge on a specific project 

will not be sensitive to turnover in professional design staff or building 

ownership, and changes in the plan will be easier to evaluate and 

implement. 
 2-9 

 Chapter 2 

2.5 How Does Incremental Seismic Rehabilitation Affect 

Liability? 

Some design professionals have been reluctant to undertake rehabilitation 

projects that are not in full compliance with current seismic criteria for 

new or existing buildings. There is a belief that additional exposure to 

professional liability exists when work results in a partial upgrade, or when 

work is conducted in increments. 

While incremental seismic rehabilitation requires additional effort on the 

part of the design professional, the basic elements of incremental seismic 

design practice are the same as typical engineering practice for singlestage projects. Conduct of incremental seismic rehabilitation design in 

accordance with the requirements of currently available codes and 

standards for existing buildings, and in accordance with the standard of 

care for prevailing seismic design practice, should not result in an increase 

in professional liability. 

The key to this assertion is that rehabilitation increments should be 

designed in such a way as to “do no harm” to the building. Work should 

not result in any dangerous conditions, and should not make a building 

less conforming to the code. Staging rehabilitation measures so that each 

increment of work will result in an incremental improvement in 

performance serves to protect the building, and the design professional, in 

the event that future increments of work are not completed. While the 

performance objectives for the full rehabilitation project may not be met, 

overall performance will be improved. 

Design professionals must clearly document decisions and actions, what 

will be achieved, and what will not be achieved with each rehabilitation 

increment. The consequences of not completing all increments in an 

incremental rehabilitation plan, and the corresponding reduced benefits 

(increased risk), must be clearly communicated to building owners. The 

strategy of incremental seismic rehabilitation assumes a commitment to 

reduce seismic risk over time, which should be fully understood and 

appreciated by both parties. 

Additional considerations for professional liability associated with 

incremental seismic rehabilitation include: 

 Professional liability policy limitations 

 Extended liability coverage 

 Ownership (beneficiary) changes 

 Insurance provider changes 

Design professionals should review these and other potential risk and 

exposure concerns with their professional liability insurance provider. 

 3-1 

 Chapter 3 

Chapter 3 Owner/Operator 

Perspectives on 

Incremental Seismic 

Rehabilitation 

3.1 Owner/Operator Objectives: Revenue Generation, 

Equity, and Service Delivery 

Buildings are owned, occupied, and operated for the purpose of generating 

revenue, accruing equity, or delivering a service. Revenue is generated in 

the form of rent or lease payments, or through the sale of merchandise or 

manufactured products. Equity is value gained (or lost) over time. In all 

cases, revenue generation, equity gain, and service delivery depend upon 

continuous occupancy and use of a building. 

At some point in their useful life, portions of buildings can evolve into a 

state of disrepair or become obsolete in terms of performing their intended 

functions. Many building owners take these opportunities to periodically 

invest in building improvements that serve to maintain facilities, enhance 

revenue generation, or improve the quality of service provided. Ongoing 

maintenance and capital improvement work provides an opportunity to 

integrate seismic rehabilitation into a facility management program at a 

time when other work is scheduled to occur. Because construction crews 

are already mobilized, finishes are removed, and occupancy is already 

interrupted, seismic rehabilitation work can opportunistically occur at 

minimal additional cost and disruption to facility operations. 

Effective implementation of incremental seismic rehabilitation measures 

into the facility management process can remove the obstacles of initial 

cost and loss of normal building use associated with single-stage 

rehabilitation projects. 

In Brief 

This chapter: 

 Explains building 

owner/operator 

perspectives on 

earthquake hazard, 

vulnerability, and risk 

 Outlines the typical 

facility management 

process as depicted 

in the FEMA ISR 

Series 

 Provides guidance on 

communicating with 

multiple client 

audiences 
3-2

Engineering Guideline for Incremental Seismic Rehabilitation 

3.2 Hazard, Vulnerability, and Risk 

In the FEMA ISR Series, building owners and operators are presented with 

the concept that earthquake risk is a function of earthquake hazard and 

vulnerability. Failure to address earthquake risk can leave building owners 

exposed to potential losses from damage, disruption, and liability for 

deaths and injuries. While purchasing insurance can protect against 

financial losses due to damage and liability, it does not solve the problem 

of long-term disruption of operations. Seismic rehabilitation is presented 

as the best option for reducing all aspects of earthquake risk. 

Earthquakes are characterized as low-probability, high consequence 

events. In the FEMA ISR Series, geographic variation in earthquake 

hazard is illustrated with the use of a simplified seismic hazard map, as 

shown in Figure 3-1. 

Figure 3-1 Simplified seismic hazard map showing red, yellow, and green 

areas indicating regions of high, moderate, and low seismicity, 

respectively (FEMA ISR Series). 

The map in Figure 3-1 is based on United States Geological Survey 

(USGS) seismic hazard maps, but is a simplified representation of seismic 

hazard intended to explain regions of high, moderate, and low seismicity 

to building owners. It should be noted that engineering seismology is in a 

constant state of revision, and updated hazard characterization is available 

from the USGS. Seismic hazard characterization for use in engineering 

applications is explained in more detail in Chapter 5. 

Owners with buildings in regions of high seismicity (red areas) are advised 

to take immediate action in undertaking a comprehensive vulnerability 
 3-3 

 Chapter 3 

assessment to identify buildings in need of structural and nonstructural 

seismic rehabilitation or replacement. 

Owners with buildings in regions of moderate seismicity (yellow areas) are 

advised to further investigate their exposure to earthquake risk, identify 

vulnerable buildings for rehabilitation or replacement, and consider 

mitigation of risk due to potential nonstructural hazards in particular. 

Owners with buildings in regions of low seismicity (green areas) are 

advised to consider low-cost rehabilitation strategies that protect against 

casualties and property loss, although the probability of an earthquake 

occurring might be low. 

Given some level of seismic hazard, the concept of building vulnerability to 

damage in the event of an earthquake, including both structural and 

nonstructural damage, is explained. Owners are introduced to the 

concepts of seismic screening and seismic evaluation, and instructed to 

seek engineering assistance from design professionals in performing 

vulnerability assessments. Consequences of earthquake vulnerability are 

characterized as: 

 Deaths and injuries to building occupants, and related liability 

 Building collapse or damage to building components, including 

related costs for repair or replacement 

 Damage to building contents, and related costs or liabilities 

 Disruption of building operations and related costs or liabilities 

3.3 Overview of the Facility Management Process 

Engineering services associated with incremental seismic rehabilitation 

must be integrated into the facility management process. Each occupancy 

category is subject to its own set of constraints on the facility 

management process. These constraints, along with the specific facility 

management, risk management, and financial management needs and 

practices for each occupancy, are described in more detail in the FEMA ISR 

Series for the following occupancy categories: 

 School Buildings 

 Hospital Buildings 

 Office Buildings 

 Multifamily Apartment Buildings 

 Retail Buildings 

 Hotel and Motel Buildings 

Design professionals should understand the facility management process 

for each occupancy category and appreciate the many factors affecting 

how maintenance and capital improvement decisions are made. A typical 

facility management process includes the following phases of activity: 

 Acquisition 

 Redevelopment 
3-4

Engineering Guideline for Incremental Seismic Rehabilitation 

 Use 

 Planning 

 Budgeting 

 Funding 

 Implementation 

These phases of activity are generally applicable to the facility 

management processes for all occupancy categories covered in the FEMA 

ISR Series. Some activities, however, are occupancy-specific, and some 

occupancies have special activities. In the case of hospitals, for example, 

accreditation is an activity that is unique to that occupancy, and in the 

case of hotels and motels, change of management can be just as critical 

as a change in ownership, but quite different. 

The facility management process is sequential, progressing from the 

acquisition phase through the implementation phase, as illustrated in 

Figure 3-2. Planning horizons for maintenance and capital improvement 

projects differ from one owner to the next. Some may have a one-year 

time frame, others may use five years, while still others may extend this 

horizon to 15 years. An owner with a large inventory of buildings is likely 

to have ongoing activities in all phases of this process within different 

buildings across the entire inventory. 

Figure 3-2 Typical sequential facility management process (FEMA ISR 

Series). 

Facility management processes vary with building ownership and 

occupancy category. They are subject to influence from a number of 

internal and external factors such as board of director policies, risk 

management policies, market conditions, economic conditions, 

government regulations, building code requirements, and insurance and 

lending requirements. 

For example, in the case of commercial office buildings, internal and 

external influences on the facility management process are shown in 

Figure 3-3. This is one of a series of figures in FEMA 397 intended to 

illustrate the facility management process and interrelationship between 

internal and external factors that are specific to commercial office 

occupancies. In the figure, columns correspond to phases of facility 

management activity for commercial office occupancies, boxes identify 

stakeholder groups or other factors (e.g., policies, regulations, market 

conditions) that have the potential to influence facility management 

decisions in each phase, and arrows represent the flow of information or 

direction of influence. 

Appendices in each of the FEMA ISR occupancy manuals provide a detailed 

explanation of the facility management processes, along with the 

associated internal and external influences, for each occupancy category. 
 3-5 

 Chapter 3 

Figure 3-3 Influences on the facility management process used in 

commercial office buildings (FEMA 397). 

3.3.1 Integration of Incremental Seismic Rehabilitation Program 

Elements 

Elements of an incremental seismic rehabilitation program extend from the 

acquisition phase to the implementation phase of a typical facility 

management process. Typical elements of an incremental seismic 

rehabilitation program include: 

 Due Dilligence Analysis 

 Operator Risk Reduction Standards 

 Initial Integration Opportunities 

 Seismic Screening 

 Seismic Evaluation 

 Developing a Risk Reduction Policy 

 Seismic Rehabilitation Planning for Specific Buildings 

 Staging Seismic Rehabilitation Increments 

 Budget Packaging 

 Financial Packaging 

 Seismic Rehabilitation Project Management 

Most of these program elements are generally applicable within the facility 

management processes for all occupancy categories covered in the FEMA 
3-6

Engineering Guideline for Incremental Seismic Rehabilitation 

ISR Series. Some program elements, however, are occupancy-specific, 

and some occupancies have special elements. Figure 3-4 illustrates when 

the above program elements should be integrated into the phases of a 

typical facility management process. 

Figure 3-4 Integration of typical incremental rehabilitation program 

elements within the typical sequential facility management 

process (FEMA ISR Series). 

3.4 The “Educated Client” Perspective 

The occupancy-specific manuals of the FEMA ISR Series are intended to 

separately educate building owners, operators, and other stakeholders on 

the concepts of building vulnerability, seismic hazard, and mitigation of 

earthquake risk. They also lay out how incremental seismic rehabilitation 

can be integrated into occupancy-specific facility management processes. 

Owners and decision-makers that are familiar with the FEMA ISR manual 

for their specific occupancy have the advantage of coming to the table 

equipped to make informed decisions on the many choices associated with 

seismic evaluation and rehabilitation. With an understanding of how 

earthquake risk fits within their business and facility management plans, 

they may be more motivated to implement seismic rehabilitation in their 

buildings, and willing to be a collaborative partner in the seismic design 

process. 

This educated client perspective greatly improves discussions at an early 

stage, and helps form the basis for mutual understanding of the many 

factors affecting the successful completion of incremental seismic 

rehabilitation projects. The design professional, however, remains an 

important part of the overall client education process. 

3.5 Communicating with Multiple Client Audiences 

There are many variables associated with the feasibility of a project and 

with choosing among various maintenance, capital improvement, and 

seismic rehabilitation alternatives. Some owners may have extensive 

management teams that include facilities, risk, and financial management 

functions composed of multiple departments and many personnel. Others 

may have combined these business concerns into a single department, or 

even a single person. In the simplest of organizational structures, 
 3-7 

 Chapter 3 

however, maintenance, risk, and financial considerations are still valid, 

and design professionals may need to address each of these individually. 

Opportunities to influence the decision-making process are best afforded 

at the early stages of project development. The role of the design 

professional will be to provide both qualitative and quantitative 

information on seismic vulnerability and relative benefits and costs 

associated with seismic rehabilitation, which can then be weighed and 

discussed on equal footing with the other drivers for decision-making. 

An owner (or ownership team) may include one or more of the following: 

facility manager(s), risk manager(s), and financial manager(s). 

Understanding the perspectives of multiple client audiences is important 

for clearly communicating engineering considerations associated with 

incremental seismic rehabilitation. 

3.5.1 Facility Managers 

In general, facility managers are concerned about the overall condition 

and functionality of the assets. Facility managers carry out planning 

activities by considering market conditions, area demographics, physical 

condition, and projected useful life of existing buildings. Often they 

consider pressing social issues such as physical security and accessibility. 

Sometimes facility managers consider the risk to buildings associated with 

natural disasters, including earthquakes. 

3.5.2 Risk Managers 

Risk managers carry out planning activities by considering three aspects of 

risk management: (1) risk identification; (2) risk reduction; and (3) risk 

transfer. The latter generally involves the purchase of insurance. Owner 

and operator risks are generally classified into the following broad areas: 

liability risk, larceny risk, employee risk, and facility and environmental 

risk. Seldom do risk managers consider risks to buildings and their 

occupants associated with natural disasters. Rather, they tend to assume 

that such risks are addressed by building codes and similar regulations. 

3.5.3 Financial Managers 

Financial managers generally control and manage maintenance budgets, 

capital improvement budgets, and insurance budgets. Facility managers 

and risk managers present demands on these budgets to the financial 

managers, but the potential tradeoffs among these budgets are not often 

considered. The relative costs and benefits of various options for facility 

risk management are rarely explicitly addressed in the usual budgeting 

process.

 4-1 

 Chapter 4 

Chapter 4 Codes and Standards 

for Seismic Evaluation 

and Rehabilitation 

4.1 Seismic Rehabilitation in Building Codes and 

Standards 

In general, most states and local jurisdictions rely on model codes and 

standards that are developed through a national consensus process to 

establish building requirements. Current national model codes and 

standards include the following documents: 

 International Code Council (ICC), International Building Code

(ICC, 2006a) 

 International Code Council (ICC), International Existing Building 

Code (ICC, 2006b) 

 American Society of Civil Engineers, ASCE/SEI 7, Minimum 

Design Loads for Buildings and Other Structures (ASCE, 2006a) 

 American Society of Civil Engineers, ASCE/SEI 31, Seismic 

Evaluation of Existing Buildings (ASCE, 2003) 

 American Society of Civil Engineers, ASCE/SEI 41, Seismic 

Rehabilitation of Existing Buildings, (ASCE, 2006b) 

Most jurisdictions adopt building codes that regulate the continued use of 

existing buildings in some way. There are three ways in which the seismic 

evaluation and rehabilitation of existing buildings are initiated. Efforts are 

mandated, triggered, or voluntarily undertaken. 

In Brief 

This chapter: 

 Lists current national 

model building codes 

and standards 

relevant to seismic 

evaluation and 

rehabilitation 

 Summarizes building 

code requirements 

related to work on 

existing buildings 

 Explains the code 

rationalization for 

incremental seismic 

rehabilitation 
4-2

Engineering Guideline for Incremental Seismic Rehabilitation 

4.1.1 Mandated Rehabilitation 

Mandated programs are those that require seismic rehabilitation (or at 

least evaluation) for specified buildings regardless of action on the part of 

a building owner. Also called “active programs,” mandates are frequently 

driven by legislation or by some authority other than the building owner. 

The rationale for legislation varies, but it usually involves a persistent 

pattern of poor seismic performance along with a sizable remaining 

inventory of susceptible building stock. 

4.1.2 Triggered Rehabilitation 

In triggered programs, also called “passive programs,” seismic evaluation 

or rehabilitation might not be intended on the part of the building owner, 

but is required (or triggered) based on the scope of repairs, additions, 

alterations, changes of occupancy, or other work that is proposed. Most 

triggered rehabilitation is driven by business decisions to otherwise 

improve a property. Once rehabilitation is triggered, it is effectively 

mandatory if the proposed work is to be done. 

4.1.3 Voluntary Rehabilitation 

Voluntary rehabilitation is work initiated by the building owner (or other 

stakeholder) and subject to minimal outside requirements. Voluntary 

work is generally driven by institutional policy or the risk sensitivity of an 

individual building owner. Although full compliance is not required or 

necessary, codes and standards are often used to guide seismic evaluation 

and design as part of voluntary rehabilitation efforts. 

4.2 Code Rationalizations for Incremental Seismic 

Rehabilitation 

Building codes allow existing buildings to remain in use without having to 

fully comply with the requirements for new buildings. This is generally 

referred to as “nonconforming rights.” The traditional language permits 

the legal occupancy of existing structures to continue with no change, 

unless deemed necessary by the building official for the safety and welfare 

of the occupants and the public, as long as no action on the part of the 

owner has triggered a requirement for compliance. State and local 

jurisdictions have created exceptions to this by enacting mandatory 

ordinances that retroactively require existing buildings to mitigate an 

identified hazard or become compliant with certain provisions of the code. 

The primary code rationalization for incremental seismic rehabilitation is 

that building officials will generally permit voluntary modifications to the 

seismic-force-resisting system provided that the building is not made less 

conforming. This rationalization can be found in the language that is 

present in current national model building codes and standards, and 

similar ideas can be found in legacy (pre-2000) building code language. 

Incremental seismic rehabilitation will offer the greatest flexibility if work 

is undertaken voluntarily, and not subject to compliance through 

mandatory or triggered programs. Even so, there are examples of 

mandatory ordinances that explicitly permit seismic strengthening to occur 
 4-3 

 Chapter 4 

in increments, such as the Earthquake Hazard Reduction Ordinance (City 

of Los Angeles, 1981) addressing unreinforced masonry buildings in the 

City of Los Angeles, California. 

4.2.1 Voluntary Changes to the Seismic-Force-Resisting System 

In their most recent editions, the various model codes and standards have 

been aligned to clearly permit voluntary changes to the seismic-forceresisting system in an existing building without full compliance with the 

code. In general, they all say that when voluntary work is undertaken to 

increase the strength or stiffness of the seismic-force-resisting system, 

this work need not be designed for current code-level forces provided that 

the following criteria are met: 

 The strength of existing structural components required to resist 

seismic forces is not reduced 

 The seismic forces on existing structural components is not 

increased beyond their design strength 

 New structural components are designed and detailed in 

accordance with the code 

 New nonstructural components are anchored in accordance with 

the code 

 The work does not make a non-conforming condition in the 

building worse 

Specific requirements on voluntary changes to the seismic-force-resisting 

system can be found in IBC 2006, Chapter 34, Section 3403; IEBC 2006, 

Chapter 8, Section 807; and ASCE 7-05, Appendix 11B, Section 11B.4. 

4.2.2 Repairs, Alterations, Additions, and Changes of Occupancy 

Ongoing maintenance and capital improvement work on existing buildings 

can include repairs, alterations, additions, and changes of occupancy. 

Depending on the nature and extent of this work, triggers for seismic 

compliance within the model codes and standards can vary somewhat. In 

general, triggering factors relate to the condition of the existing building, 

the type of work, the percentage of the building affected by the new work, 

and the past and future use of the building. 

Repairs. Historically, repairs have been permitted to restore a building to 

its pre-damaged condition using materials and methods consistent with 

the original construction. Exceptions to this are based on the condition of 

the building. If existing structural components are found to be unsound, 

dangerous, or otherwise deficient, then repair work can trigger compliance 

with current code provisions. The IEBC 2006 further defines a term called 

“substantial structural damage,” which is determined by a threshold 

percentage of strength loss occurring in structural components over a 

threshold percentage of floor area. Buildings that have sustained 

“substantial structural damage” must be repaired to a minimum level of 

seismic resistance that is set somewhat below current code level forces. 

Buildings that have sustained less than “substantial structural damage” 

are permitted to be repaired using original materials and methods. 
4-4

Engineering Guideline for Incremental Seismic Rehabilitation 

Specific requirements on repairs can be found in IBC 2006, Chapter 34, 

Section 3403; and IEBC 2006, Chapter 5, Section 506. 

Alterations. Alterations made to existing buildings must comply with 

current code requirements. The rest of the altered building, however, 

does not always need to comply with the current code. Exceptions to this 

are based on the system that is being altered, and the extent of the 

alteration. Alterations to fire and life-safety systems often require 

upgrade of the entire system to full code compliance. Structural 

alterations, however, are generally permitted as long as loads on existing 

structural components are not increased, and capacities of existing 

structural components are not decreased (within certain limits). The IEBC 

2006 further defines three levels of alteration depending on the extent of 

the work, and defines a term called “substantial structural alteration,” 

which is based on how much of the floor area is being structurally altered. 

Buildings undergoing “substantial structural alteration” must meet a 

minimum level of seismic resistance that is set somewhat below current 

code level forces. 

Specific requirements on alterations can be found in IBC 2006, Chapter 

34, Section 3403; IEBC 2006, Sections 606, 707, and 807; and ASCE 7-

05, Appendix 11B, Section 11B.4. 

Additions. Additions made to existing buildings must comply with current 

code requirements. The rest of the building, however, does not always 

need to comply with the current code. Exceptions to this are based on the 

configuration of the addition, and the effect that the addition has on the 

existing structural system. Vertical additions, and additions that increase 

loads on existing structural components (beyond certain limits), trigger 

compliance for the entire structure. 

Specific requirements on additions can be found in IBC 2006, Chapter 34, 

Section 3403; IEBC 2006, Chapter 10, Section 1003; and ASCE 7-05, 

Appendix 11B, Section 11B.3. 

Changes of occupancy. Changes in the occupancy and use of a building 

that result in reclassification to a higher occupancy category (and a 

correspondingly higher seismic occupancy factor) require compliance of 

the entire building with current code provisions applicable to the new 

occupancy. 

Specific requirements on changes of occupancy can be found in IBC 2006, 

Chapter 34, Section 3406; IEBC 2006, Chapter 9, Section 907; and ASCE 

7-05, Appendix 11B, Section 11B.5. 

4.2.3 Pre-2000 Legacy Codes 

Prior to 2000, there were three organizations producing three model 

building codes in the United States. These were the International 

Conference of Building Officials (ICBO), which produced the Uniform 

Building Code (UBC), the Southern Building Code Congress International 

(SBCCI), which produced the Standard Building Code, and the Building 

Officials and Code Administrators International, Inc. (BOCA), which 

produced the National Building Code. In the mid-1990s, these three 

model code organizations formed the International Code Council (ICC) to 
 4-5 

 Chapter 4 

collaborate on the development of one model code for use throughout the 

United States. This effort resulted in the publication of the initial 

International Building Code (IBC) in 2000. 

The organizations that developed these codes were located in different 

regions of the country, and each focused on criteria for natural hazards 

that were the most important in their respective regions. Although 

seismic hazards were not the highest priority in all regions, these legacy 

codes contain provisions that allow for incremental seismic rehabilitation 

of existing buildings without full code compliance. 

BOCA National Building Code (BOCA, 1999). In the 1999 edition of 

the National Building Code, Section 3404 permits alterations to existing 

buildings without requiring full compliance with the current code. Section 

3405 requires changes of occupancy to comply with the intent of the code 

for new construction. Chapter 16 requires additions and changes of 

occupancy that reclassify the building to a higher Seismic Hazard Exposure 

Group to comply with the seismic provisions of the current code. 

ICBO Uniform Building Code (ICBO, 1997). The 1997 edition of the 

Uniform Building Code is the legacy code that most closely resembles 

current model codes and standards. Section 3403 permits voluntary 

increases to the strength and stiffness of seismic-force-resisting systems 

consistent with current code requirements. Section 3403 also permits 

additions, alterations, and repairs to be made without triggering full 

compliance, as long as the new work is constructed in accordance with the 

current code, and it does not cause the structure to be unsafe or any more 

hazardous than it was before the work was initiated. Section 3405 

requires changes of occupancy to conform to the requirements of the new 

occupancy, unless the new occupancy is less hazardous. 

SBCCI Standard Building Code (SBCCI, 1999). In the 1999 edition of 

the Standard Building Code, Section 3401 permits repairs, alterations, or 

rehabilitation work to be performed in any existing building without 

triggering full compliance with the code, as long as the new work is 

constructed in accordance with the current code. 

 5-1 

 Chapter 5 

Chapter 5 Incremental Seismic 

Rehabilitation 

Engineering Process 

5.1 Engineering Phases of an Incremental Seismic 

Rehabilitation Program 

The FEMA ISR Series presents information and guidance to building 

owners and operators that is intended to assist in the planning and 

completion of a successful incremental seismic rehabilitation program. As 

part of implementing such a program, building owners and operators are 

advised to seek engineering assistance from design professionals for: 

(1) seismic screening and evaluation; (2) incremental seismic 

rehabilitation planning and design; and (3) construction period support. 

These encompass the following elements of an incremental seismic 

rehabilitation program: 

 Due Diligence Analysis (performed during the acquisition phase) 

 Seismic Screening (performed during the current building use 

phase) 

 Seismic Evaluation (performed during the current building use 

phase) 

 Seismic Rehabilitation Planning for Specific Buildings (performed 

during the planning phase) 

 Staging Seismic Rehabilitation Increments (performed during 

the planning phase) 

 Seismic Rehabilitation Project Management and construction 

period support (performed during the implementation phase) 

In Brief 

This chapter: 

 Identifies the 

engineering phases of 

an incremental 

seismic rehabilitation 

program 

 Describes the 

performance-based 

design process 

 Explains the steps of 

the incremental 

seismic rehabilitation 

engineering process 

as depicted in the 

FEMA ISR Series 
5-2

Engineering Guideline for Incremental Seismic Rehabilitation 

Figure 5-1 illustrates when engineering services are integrated into the 

phases of a typical facility management process. 

Figure 5-1 Integration of engineering services within the typical sequential 

facility management process (FEMA ISR Series). 

These services, and how they relate to typical engineering practice for 

single-stage projects, were introduced in Chapter 2. Integration of 

incremental seismic rehabilitation into a facility management process was 

described in Chapter 3. Current national model building codes and 

standards, and their relation to work on existing buildings, were explained 

in Chapter 4. This chapter describes the specific elements of the 

incremental seismic rehabilitation engineering process in more detail. It 

identifies what services are needed when, and provides guidance on how 

existing building resource documents are used in providing incremental 

seismic rehabilitation engineering services. 

5.2 Engineering Resources Referenced in the FEMA ISR 

Series 

The engineering implementation of incremental seismic rehabilitation 

relies on the use of the following existing building resource documents, 

which are referenced in the FEMA ISR Series occupancy manuals and 

briefly described below. 

Collectively, these documents define the process of screening a building 

inventory to identify potentially hazardous buildings, evaluating potentially 

hazardous buildings to confirm deficiencies and identify rehabilitation 

needs, and designing necessary seismic rehabilitation measures. While 

they do not explicitly refer to incremental seismic rehabilitation, the 

engineering procedures are applicable to the incremental seismic 

rehabilitation process, and should be used along with other applicable 

resources in developing and implementing an incremental seismic 

rehabilitation plan. 

FEMA 154, Rapid Visual Screening of Buildings for Potential 

Seismic Hazards: A Handbook, Second Edition (FEMA, 2002). The 

FEMA 154 Handbook provides a relatively simple method for quickly 

screening and ranking buildings that are at risk for deaths, injuries, or loss 

of use in the event of an earthquake. The rapid visual screening (RVS) 

procedure can be used by trained personnel to identify potentially 

hazardous buildings with a brief exterior inspection and a data collection 

form included in the Handbook. 
 5-3 

 Chapter 5 

The FEMA 154 Handbook is intended for use on a large group of buildings 

for the purpose of relative comparison of risk and prioritization for further 

study. With some limitations, however, it can be used to quickly assess 

the potential seismic performance of a single building. 

ASCE/SEI 31, Seismic Evaluation of Existing Buildings (ASCE, 

2003). Based on a series of predecessor documents dating back to 

ATC-14, Evaluating the Seismic Resistance of Existing Buildings (ATC, 

1987), ASCE 31 is a national consensus standard for the seismic 

evaluation of existing buildings. It is applicable to structural and 

nonstructural evaluation of Life Safety and Immediate Occupancy 

performance levels at any level of seismicity. 

ASCE 31 defines a three-tiered process in which each successive tier 

involves more detailed evaluation, increased effort, and greater confidence 

in the identification and confirmation of seismic deficiencies. The basis of 

the methodology is the Tier 1 checklist procedure, which utilizes a series 

of checklists to identify building characteristics that have exhibited poor 

performance in past earthquakes. 

ASCE/SEI 41, Seismic Rehabilitation of Existing Buildings (ASCE, 

2006b). Based on a series of predecessor documents dating back to 

FEMA 273, NEHRP Guidelines for the Seismic Rehabilitation of Buildings

(BSSC, 1997), ASCE 41 is a national consensus standard for the seismic 

rehabilitation of existing buildings. Its immediate precursor, FEMA 356, 

Prestandard and Commentary for the Seismic Rehabilitation of Buildings

(FEMA, 2000), was referenced in the FEMA ISR Series, but has since been 

superseded by ASCE 41. It defines a performance-based approach for 

seismic analysis and design that can be used to achieve a desired 

performance objective selected from a range of performance levels 

(Collapse, Collapse Prevention, Life Safety, Immediate Occupancy, and 

Operational) at any seismic hazard level. It is intended to be generally 

applicable to structural and nonstructural components in buildings of any 

configuration and any construction type. 

The performance-based methodology of ASCE 41 involves selection of a 

rehabilitation objective, selection of a rehabilitation method, analysis and 

design of rehabilitation measures, performance verification of a 

rehabilitation design, and preparation of construction documents. 

Engineering analysis is based on a series of linear, nonlinear, static, and 

dynamic analysis options, which involve increasing levels of effort and 

greater confidence in the resulting rehabilitation design. 

5.3 Performance-Based Seismic Design 

The engineering process for incremental seismic rehabilitation is likely to 

include performance-based seismic design. Earthquake experience in 

recent years has forced recognition that damage (sometimes severe) can 

occur in a building designed in accordance with the code. “Performance” 

is used to identify levels of damage, and acceptable performance equates 

to acceptable levels of damage. This, in itself, represents a major change 

in perception. Building owners and occupants generally believe that 

adherence to building codes provides for a safe and habitable 

environment, and anticipated degrees of damage are not a normal topic of 

conversation between owners and design professionals. 
5-4

Engineering Guideline for Incremental Seismic Rehabilitation 

In contrast to prescriptive design approaches, performance-based design 

provides a systematic methodology for assessing the performance 

capability of a building, system or component. It can be used to verify the 

equivalent performance of alternatives, deliver standard performance at a 

reduced cost, or confirm higher performance needed for important 

facilities. It also establishes a vocabulary that facilitates meaningful 

discussion between building owners and design professionals on the 

development and selection of design options. It provides a framework for 

determining what level of safety and what level of property protection, at 

what cost, are acceptable based upon the specific needs of the project. 

5.3.1 Performance-Based Design Process 

In performance-based design, identifying the performance capability of a 

building is an integral part of the design process, and guides the many 

design decisions that must be made. Figure 5-2 shows a flowchart that 

presents the key steps in performance-based design. It is an iterative 

process that begins with the selection of performance objectives, followed 

by the development of a preliminary design, an assessment as to whether 

or not the design meets the performance objectives, and finally redesign 

and reassessment, if required, until the desired performance level is 

achieved. 

Select

Performance

Objectives

Develop

Preliminary

Design

Assess

Performance

Capability

Does

Performance

Meet

Objectives?

Revise

Design

and/or

Objectives

No

Done

Yes

Select

Performance

Objectives

Develop

Preliminary

Design

Assess

Performance

Capability

Does

Performance

Meet

Objectives?

Revise

Design

and/or

Objectives

No

Done

Yes

Figure 5-2 Performance-based design flowchart (ATC, 2003). 

Performance-based design initiates with the selection of design criteria 

stated in the form of one or more performance objectives. Each 

performance objective is a statement of the desired performance level 

(acceptable level of structural and nonstructural damage) given a specified 

level of seismic hazard. Generally, a team of decision makers, including 

the building owner and design professional, will participate in selecting the 

performance objectives for a building. This team may consider the needs 

and desires of a wider group of stakeholders including prospective tenants, 

lenders, insurers and others who have impact on the value or use of a 

building, but may not directly participate in the design process. 

Once the performance objectives for a project have been selected, the 

design professional must develop a preliminary design. For an existing 
 5-5 

 Chapter 5 

building, the preliminary design generally consists of the existing building 

without further modification. To assess an existing building, the following 

information is needed: building type, location, size and configuration, 

occupancy, quality and character of construction, and estimates of 

strength, stiffness, and ductility. 

Once the preliminary design has been identified, a series of simulations 

(analyses of building response to loading) are performed to estimate the 

probable performance of the building under various scenario events. In 

the case of extreme loading, as would be imparted by a severe 

earthquake, simulations may be performed using nonlinear analysis 

techniques. 

If the simulated performance meets or exceeds the performance 

objectives, the design is completed. If not, the design must be revised in 

an iterative process until the performance objectives are met. In some 

cases it may not be possible to meet the stated objective at reasonable 

cost, in which case, some relaxation of the original objectives may be 

appropriate. 

The overall analysis must consider not only the frequency at which the 

design earthquake occurs, but the effectiveness and reliability of the entire 

building as a system. Any seismic analysis method should also anticipate 

a certain level of “uncertainty,” and should address this uncertainty to the 

extent that available data allow. 

5.4 Incremental Seismic Rehabilitation Basic 

Information 

Application of performance-based design in incremental seismic 

rehabilitation requires basic information in the following three categories: 

 building type 

 seismic hazard level 

 performance objectives 

This information is used in existing building resource documents for 

screening, evaluation, and design of rehabilitation measures. This 

information, however, is defined and used somewhat differently in each of 

the resource documents. Similarities and differences are described in the 

sections that follow. 

5.4.1 Building Type 

The occupancy manuals in the FEMA ISR Series categorize buildings into 

seven building structural types based on the vertical load-carrying system 

and the floor and roof diaphragm types. These categories are used to 

identify integration opportunities and the relative complexity of 

engineering necessary to implement rehabilitation measures. The seven 

FEMA ISR building structural types are: 

 Wood 

 Unreinforced masonry 
5-6

Engineering Guideline for Incremental Seismic Rehabilitation 

 Reinforced masonry 

 Concrete with flexible diaphragms 

 Concrete with rigid diaphragms 

 Steel with flexible diaphragms 

 Steel with rigid diaphragms 

These are related to, but different from, building types as identified in 

FEMA 154, ASCE 31, and ASCE 41. Table 5-1 shows a comparison 

between the building type designations in the various FEMA ISR reference 

documents. 

Table 5-1 Comparison of Building Classifications in Various FEMA 

ISR Reference Documents 

FEMA ISR Occupancy Manuals 

FEMA 154 ASCE 31/ASCE 41 

Material Diaphragm Type 

Wood Flexible/Rigid 

W1 

W1 (Light Frame) 

W1A (Multi-Unit Residential) 

W2 W2 (Commercial/Industrial) 

Unreinforced 

Masonry 

Flexible 

URM 

URM 

Rigid URMA 

Reinforced 

Masonry 

Flexible RM1 RM1 

Rigid RM2 RM2 

Reinforced 

Concrete 

Rigid C1 C1 (Moment Frame) 

Rigid 

C2 

C2 (Shear Wall) 

Flexible C2A 

Rigid 

C3 

C3 (Frame with Infill) 

Flexible C3A 

Rigid 

PC1 

PC1A (Precast Tilt-up) 

Flexible PC1 

Rigid PC2 

PC2 (Precast Frame/Wall) 

PC2A (Precast Frame) 

Steel 

Rigid 

S1 

S1 (Moment Frame) 

Flexible S1A 

Rigid 

S2 

S2 (Braced Frame) 

Flexible S2A 

Flexible S3 S3 (Light Frame) 

Rigid S4 S4 (Frame with Concrete Walls) 

Rigid 

S5 

S5 (Frame with Masonry Infill) 

Flexible S5A 
 5-7 

 Chapter 5 

In FEMA 154, 15 building types are considered. These are categorized by 

the construction of the primary seismic-force-resisting system. Categories 

are used to establish basic scores that define initial relative building 

vulnerabilities in the rapid visual screening procedure. Information used 

to categorize buildings can be obtained from a visual survey, or from a 

review of available drawings. If the structural system is not visible from 

the interior or exterior, and drawings are not available, a range of possible 

building types must be considered. 

In ASCE 31, 24 basic building types, called common building types, are 

considered. They are an expansion of the building types found in FEMA 

154, and are categorized by the construction of the primary seismic-forceresisting system. Classification depends on the material (e.g., wood, 

steel, concrete, masonry), framing type (e.g., shear wall or moment 

frame), and diaphragm behavior (e.g., rigid or flexible). Common building 

types are used to select system-specific checklists that identify building 

characteristics that are known to have exhibited poor performance in past 

earthquakes. For buildings that do not fit into one of the defined building 

types, ASCE 31 contains a general checklist for mixed building types. 

The provisions in ASCE 41 are intended to be generally applicable to all 

building types, system configurations, and construction materials. The 

Simplified Rehabilitation Procedure contained in ASCE 41 utilizes model 

building types that are identical to the 24 common building types found in 

ASCE 31. 

 5.4.2 Seismic Hazard Level 

The United States Geological Survey (USGS) is responsible for determining 

the seismic hazard throughout the United States. The USGS publishes a 

series of seismic hazard maps, which are updated on an ongoing basis. 

Short period maps and one-second period maps define the short period 

(SS) and one-second period (S1) spectral response acceleration 

parameters by location. Site class (soil type) will amplify or decrease the 

intensity of ground shaking at a site. By knowing the location and the soil 

type, one can determine the expected intensity of ground shaking that a 

building will experience. If the soil type is not known, use of a default soil 

type is possible, although default soil factors may result in more 

conservative analysis criteria (and, potentially, more expensive 

rehabilitation measures). 

In FEMA 154, seismic hazard level is determined by regions of seismicity. 

FEMA 154 uses the simplified hazard map shown in Figure 5-3 to define 

regions of low, moderate and high levels of seismicity. The map is based 

on the USGS hazard maps, and is similar to the one provided in the FEMA 

ISR Series, but aggregates the levels of seismicity somewhat differently. 

Seismic hazard characterization has evolved significantly since the time 

that FEMA 154 was published. Changes to earthquake source and 

occurrence rate models, along with new understanding of how earthquake 

ground motion decays with distance (attenuation relationships), have 

resulted in revised estimates of the hazard near known faults and other 

areas in the Central and Eastern United States. 
5-8

Engineering Guideline for Incremental Seismic Rehabilitation 

In the simplified hazard map shown in Figure 5-3, regions of low 

seismicity include areas of the country in which no seismic design is 

required by current seismic design codes and standards for new buildings. 

For this reason, it is recommended that the relative seismic hazard at a 

given site be characterized using the latest seismic hazard maps available 

from the USGS. 

Figure 5-3 FEMA 154 simplified seismic hazard map (FEMA, 2002). 

In ASCE 31, three levels of seismicity are defined in terms of short period 

(SDS) and one-second period (SD1) spectral response acceleration 

parameters. The SDS and SD1 parameters are based on the USGS 

mapped SS and S1 spectral response acceleration parameters, modified by 

site class. Figure 5-4 shows the definition of ASCE 31 levels of low, 

moderate, and high seismicity. 

Level of Seismicity1 SDS SD1

Low <0.167g <0.067g 

Moderate 0.167g 

<0.500g 

0.067g 

<0.200g 

High 0.500g 0.200g 

1 Sites with SDS and SD1 values in different levels of seismicity shall be classified as 

moderate.

Figure 5-4 ASCE 31 Levels of Seismicity Definitions (ASCE, 2003). 

In ASCE 41, three levels of seismicity are defined in terms of design short 

period (SXS) and design one-second period (SX1) spectral response 
 5-9 

 Chapter 5 

acceleration parameters. The SXS and SX1 design parameters are based 

on the USGS mapped SS and S1 spectral response acceleration 

parameters, modified by site class. The ranges of SXS and SX1 defining 

low, moderate, and high levels of seismicity are identical to the ranges of 

SDS and SD1 used in ASCE 31. 

5.4.3 Performance Objectives 

Performance is communicated in terms of discretely defined performance 

levels: Collapse, Collapse Prevention, Life Safety, Immediate Occupancy, 

and Operational Performance. These performance levels address damage 

to both structural and nonstructural components. Performance Objectives 

are developed by linking one of these performance levels to a specific level 

of earthquake hazard, as shown in Figure 5-5. 

Figure 5-5 Seismic performance objectives linking building performance 

levels to earthquake hazard levels (adapted from SEAOC, 1995). 

In FEMA 154, performance objectives are not addressed directly. The 

methodology does, however, identify potentially hazardous buildings that 

are at risk for deaths, injuries, or loss of use in the event of an 

earthquake. 

In ASCE 31, performance objectives are defined in terms of levels of 

performance and levels of seismicity. ASCE 31 contains criteria for 

detailed evaluation of buildings for Life Safety and Immediate Occupancy 

levels of performance. These levels of performance can be evaluated at 

low, moderate, and high levels of seismicity. In the ASCE 31 

methodology, the level of performance and level of seismicity affect the 

selection of checklists that are used for each building type. 

In ASCE 41, performance objectives are defined in terms of Rehabilitation 

Objectives. A Rehabilitation Objective is a combination of a Target 

Building Performance Level and an Earthquake Hazard Level. Target 
5-10

Engineering Guideline for Incremental Seismic Rehabilitation 

Building Performance Levels consider both structural and nonstructural 

component behavior. 

5.5 Due Diligence Analysis 

Due diligence analysis is performed on behalf of owners considering the 

acquisition of an existing building. The purpose of a due diligence analysis 

is to identify and quantify potential seismic risks that may exist so that 

they can be taken into account (or avoided) in a building acquisition plan. 

Seismic risks have traditionally been quantified in the due diligence 

process by means of Probable Maximum Loss (PML) analyses. PML 

analyses consist of estimating the damage that the building would 

experience in a major rare earthquake, expressed as a percentage of the 

value of the building. There are two resources offering guidance in 

conducting PML analyses: 

 ASTM E2026, Standard Guide for Seismic Risk Assessment of 

Buildings (ASTM, 2007a) 

 ASTM E2557, Standard Practice for Probable Maximum Loss 

(PML) Evaluations for Earthquake Due-Diligence Assessments

(ASTM, 2007b) 

These standards distinguish between scenario losses (SL) and probable 

losses (PL). In ASTM E2026, four levels of PML investigation are defined 

ranging from screening (level 0) to exhaustive investigation (level 3). 

Additionally, five different types of earthquake loss studies are provided, 

serving different financial and management needs: 

 Building Stability 

 Site Stability 

 Damageability 

 Contents Damageability 

 Business Interruption 

In ASTM E2557, scenario losses are expressed as either scenario expected 

loss (SEL) or scenario upper loss (SUL) with each related to a specified 

earthquake hazard level. Probable loss estimates account for the damage 

that a building might experience from all earthquakes that could affect the 

site. Owners, lenders, and insurers establish their own criteria for 

acceptable scenario loss or probable loss values, based on their respective 

tolerances for earthquake risk. 

5.6 Seismic Screening 

Seismic screening is intended to be a rapid, simple, preliminary 

assessment of potential seismic risk. The FEMA 154 Handbook defines a 

rapid visual screening process that can be used to rank the relative risk of 

buildings within an inventory of buildings. While intended for use on a 

large group of buildings, it can also be used as a preliminary evaluation 

tool to obtain a sense of the possible seismic risk associated with an 

individual building. 
 5-11 

 Chapter 5 

The rapid visual screening (RVS) procedure consists of an exterior 

inspection of the building to identify the seismic-force-resisting system 

and any building attributes that might modify the expected seismic 

performance of that system. The procedure is implemented using data 

collection forms recording the following information: 

 Address or other identifying information 

 Structural system type 

 Building age 

 Building occupancy category and number of occupants 

 Building plans if available 

 Soil conditions (soil type A-F) 

 Presence of falling hazards (chimneys, parapets, cladding, and 

veneer) 

The forms are shown in Figure 5-6. Based on the building structural 

system type, a Basic Structural Hazard (BSH) score is assigned. Scores 

are given for regions of low, moderate, and high levels of seismicity. For 

each level of seismicity, the score reflects the estimated likelihood that a 

typical building in that category would sustain major damage, defined as 

damage requiring repairs totaling approximately 60% or more of the 

building value. This level of damage is about the threshold where life 

safety begins to become a serious concern. 

Basic Structural Hazard scores are then increased or decreased by Score 

Modifiers that account for building or site features that increase or 

decrease seismic vulnerability. Score Modifiers consider such attributes 

as: 

 Number of stories 

 Vertical irregularities 

 Horizontal irregularities 

 Pre-code buildings (designed and constructed prior to the 

adoption of a seismic code) 

 Post-benchmark buildings (designed and constructed after 

significant improvements in seismic codes) 

 Soil type 

When Score Modifiers are combined with the Basic Structural Hazard 

Score, the result is a final Structural Score (S) for the building. Final 

Structural Scores typically range from 0 to 7, with higher scores 

corresponding to better expected seismic performance. For a large group 

of buildings, priorities for seismic evaluation can be based on the resulting 

Structural Scores (the lower the score, the higher the priority). 

If a building receives a high score it is considered to have low risk. 

Structural Scores of 2 or 3 are recommended as minimum values below 

which buildings should be further evaluated. If a building receives a low 

score it should be evaluated by a design professional. Buildings identified 

as needing more detailed evaluation should not be considered hazardous 

without additional evaluation. 
5-12

Engineering Guideline for Incremental Seismic Rehabilitation 

Figure 5-6 FEMA 154 data collection forms for Low, Moderate, and High 

regions of seismicity. 

Because FEMA 154 is intended to be used on a large inventory of 

buildings, FEMA has developed a software application for portable 

electronic devices called Rapid Observation of Vulnerability and Estimation 

of Risk (ROVER), which can be used to rapidly gather pre-earthquake 

building information in the field, screen buildings for potential seismic risk, 

and manage the resulting large volume of data (ATC, 2009). The ROVER 

software application uses electronic data collection forms, and takes 

advantage of global positioning system (GPS) technology to determine the 

seismic hazard at a site automatically, using the latest USGS seismic 

hazard information. 
 5-13 

 Chapter 5 

5.7 Seismic Evaluation 

Seismic evaluation is a more detailed assessment and confirmation of 

potential seismic deficiencies. Typically it is conducted on individual 

buildings that have been identified as vulnerable based on a screening 

process. The ASCE 31 standard defines a national consensus procedure 

for seismic evaluation consisting of a three-tiered process in which each 

successive tier involves more detailed evaluation, increased effort, and 

greater confidence in the identification and confirmation of seismic 

deficiencies. Unless otherwise triggered by local jurisdictional 

requirements, other established procedures for evaluating seismic 

deficiencies could be used. 

The procedure includes consideration of “Benchmark Buildings,” which are 

buildings designed and constructed in accordance with certain benchmark 

code provisions that include relevant seismic design and detailing 

requirements. Benchmark Buildings need not proceed with further 

evaluation, but design and construction in accordance with the benchmark 

provisions must be verified. 

Tier 1 utilizes a series of checklists and “quick check” calculations to 

identify building characteristics that have exhibited poor performance in 

past earthquakes. Based on building type, level of seismicity, and 

performance level, checklists are selected for use in a Tier 1 evaluation. 

An excerpt from one such checklist is shown in Figure 5-7. In addition to 

basic and supplemental structural checklists, there is a foundationgeologic hazard checklist, and nonstructural checklists covering 

architectural, mechanical, electrical, and plumbing components in a 

building. In Tier 1, the level of analysis is minimal. Evaluation is 

necessarily conservative as a trade-off for avoiding more detailed 

evaluation. 

A Tier 1 evaluation is required for all buildings. At each level, one could 

choose to stop the evaluation process and proceed with mitigation of 

deficiencies. In general, it is optional to proceed to higher tiers of 

evaluation. For certain combinations of building type and performance 

level, however, a Tier 2 or Tier 3 evaluation may be required. 

A Tier 2 evaluation involves simplified, but more detailed analyses to 

confirm or eliminate potential deficiencies identified in Tier 1. Tier 2 

utilizes four analysis procedures: (1) Linear Static Procedure; (2) Linear 

Dynamic Procedure; (3) Special Procedure for unreinforced masonry 

buildings with flexible diaphragms; and (4) a procedure for nonstructural 

components. As a minimum, only those items found deficient under the 

Tier 1 analysis need to be evaluated. A Tier 2 evaluation may require 

more information about the building than a Tier 1 Evaluation, which may 

include determination of material strengths. 
5-14

Engineering Guideline for Incremental Seismic Rehabilitation 

Figure 5-7 Excerpt from the Basic Structural Checklist for Building Type C2: 

Concrete Shear Walls with Stiff Diaphragms (ASCE, 2003). 

A Tier 3 evaluation involves more complex nonlinear analysis procedures 

in an effort to further confirm, or ultimately eliminate, potential 

deficiencies remaining after a Tier 2 evaluation. Additional, more detailed 

building information is required to conduct a Tier 3 evaluation. This could 

require acquisition or development of as-built drawings. Site verification 

to determine as-built construction may require removal of finishes and 

physical testing to determine material strengths, types of connections, or 

the presence of reinforcing steel. 

In general a Tier 3 evaluation refers the user to ASCE 41. Consistent with 

traditional engineering practice and industry consensus, however, 

acceptance criteria used for evaluation are relaxed in comparison with 
 5-15 

 Chapter 5 

acceptance criteria used for rehabilitation design. For this reason, a 0.75 

factor is applied when utilizing ASCE 41 in an ASCE 31 Tier 3 evaluation. 

This is also why component modification factors (or m-factors) in ASCE 31 

differ from those in ASCE 41. 

This difference represents an approximate adjustment to a mean level of 

earthquake shaking, which is considered appropriate for existing buildings 

with a remaining useful life that is shorter than that of new buildings 

(which are designed to a mean-plus-one standard deviation level of 

earthquake shaking). This reduction recognizes that while new designs 

have an inherent conservatism that comes with only marginal additional 

cost, the same conservatism applied to existing buildings would identify 

too many buildings as deficient. 

Differences in acceptance criteria between evaluation and design can 

make it difficult to reconcile results when moving from the evaluation 

phase to rehabilitation planning for specific buildings. These differences 

should be anticipated and considered in the implementation of an 

incremental seismic rehabilitation program. 

5.8 Seismic Rehabilitation Planning for Specific 

Buildings 

Seismic rehabilitation planning involves design of rehabilitation measures, 

prioritization, identification of integration opportunities, and definition of 

appropriate rehabilitation increments. In the FEMA ISR Series, the 

development and documentation of a seismic rehabilitation plan is an 

essential element in the implementation of incremental seismic 

rehabilitation. 

5.8.1 Incremental Seismic Rehabilitation Plan 

An incremental seismic rehabilitation plan should include all anticipated 

rehabilitation increments and their prioritization, and should be a written 

record of the goals and decisions made regarding implementation. 

Documentation should help guide the implementation of the overall 

incremental seismic rehabilitation program, and should help ensure that 

the building owner does not lose sight of overall rehabilitation goals during 

implementation of individual increments. 

Since work may continue over a period of years, an incremental seismic 

rehabilitation plan must be periodically re-evaluated, and possibly 

adjusted. It must be in a form that follow-on users can readily pick up 

and continue with work. 

An incremental seismic rehabilitation plan should include documentation of 

the following information: 

Building description: the building type and its seismic-force-resisting 

system in as much detail as possible; any available records concerning the 

construction of the building, including plans, shop drawings, details, 

calculations, and specifications. 
5-16

Engineering Guideline for Incremental Seismic Rehabilitation 

Level of seismicity: the basis for determining the level of seismicity, 

including seismic hazard maps and spectral response acceleration 

parameters, site class, geotechnical reports, and probabilistic seismic 

hazard assessments (if performed). 

Performance objectives: the selected target building performance 

levels, including both structural and nonstructural performance, the 

selected seismic hazard level, and the reasons for these selections. 

List of deficiencies: the results of an assessment as to whether or not 

the building meets the stated performance objectives; analytical results 

used in the evaluation; a complete list of all seismic deficiencies, including 

a description of the expected performance and resulting consequences of 

damage. 

Rehabilitation measures: a complete list of all rehabilitation measures 

required to address the complete list of deficiencies; analytical results and 

design calculations; design drawings and construction documents. 

Rehabilitation increments: prioritization of rehabilitation measures into 

discrete stages; rationale for establishing priorities; identification of 

integration opportunities in the maintenance and capital improvement 

process; explanation of performance expectations for each increment. 

Rehabilitation Project Schedule: the intended sequencing of 

rehabilitation increments and the overall intended project timeline. 

5.8.2 Design of Rehabilitation Measures 

The ASCE 41 standard defines a performance-based design approach for 

achieving a desired performance objective selected from a range of 

performance levels (Collapse, Collapse Prevention, Life Safety, Immediate 

Occupancy, and Operational) at any specified seismic hazard level. The 

methodology involves selection of a rehabilitation objective, selection of a 

rehabilitation method, analysis and design of rehabilitation measures, 

performance verification of a rehabilitation design, and preparation of 

construction documents. Unless otherwise triggered by local jurisdictional 

requirements, other established procedures for designing rehabilitation 

measures could be used. 

Rehabilitation Objectives are a function of Target Building Performance 

Levels and Earthquake Hazard Levels. Figure 5-8 shows the range of 

ASCE 41 Target Building Performance Levels. In the figure, alpha-numeric 

codes are used to identify the structural and nonstructural performance 

levels (e.g., the designation 3-C refers to structural performance level 3 

and nonstructural performance level C). Figure 5-9 shows how Target 

Building Performance Levels are linked with Earthquake Hazard Levels to 

define Rehabilitation Objectives. A Basic Safety Objective is defined, 

which is intended to be generally consistent with the safety level expected 

in current code-conforming buildings, and other rehabilitation objectives 

are characterized by comparison with the Basic Safety Objective. 

Enhanced rehabilitation objectives exceed the performance expectations of 

the Basic Safety Objective, and limited rehabilitation objectives improve 

seismic performance, but fall below the performance expectations of the 

Basic Safety Objective. 
 5-17 

 Chapter 5 

Two methods of rehabilitation are provided within ASCE 41: systematic 

rehabilitation and simplified rehabilitation. Systematic rehabilitation is 

intended to be generally applicable to structural and nonstructural 

components in buildings of any configuration and any construction type. 

Engineering analysis is based on a series of four analysis options: (1) 

Linear Static Procedure; (2) Linear Dynamic Procedure; (3) Nonlinear 

Static Procedure; and (4) Nonlinear Dynamic Procedure. Each successive 

option involves increasing levels of effort and greater confidence in the 

resulting rehabilitation design. 

Simplified rehabilitation is applicable to structural and nonstructural 

components in buildings within a specified range of building types and 

characteristics. Applicability depends on the number of stories and the 

level of seismicity. In general, simplified rehabilitation refers the user to 

ASCE 31, and permits a deficiency-only rehabilitation plan without an 

explicit requirement for a full-building analysis. 

Operational (1-A)

Backup utility services maintain 

functions; very little damage. 

(S1+NA)

Immediate Occupancy (1-B)

The building remains safe to 

occupy; any repairs are minor. 

(S1+NB)

Life Safety (3-C)

Structure remains stable and 

has significant reserve 

capacity; hazardous 

nonstructural damage is 

controlled. (S3+NC)

Collapse Prevention (5-E)

The building remains standing, 

but only barely; any other 

damage or loss is acceptable. 

(S5 + NE)

lower performance

more loss

higher performance

less loss

Expected Post-Earthquake 

Damage State

Table C1-1. Rehabilitation Objectives 

Target Building 

Performance Levels 

Operational Performance Level (1-A) Immediate Occupancy Performance Level (1-B) Life Safety Performance Level (3-C) Collapse Prevention Performance Level (5-E) 

Earthquake Hazard Level 

50%/50 year a b c d 

20%/50 year e f g h 

BSE-1 

(~10%/50 year) i j k l 

BSE-2 

(~2%/50 year) m n o p 

1

Each cell in the above matrix represents a discrete Rehabilitation 

Objective. 

2

The Rehabilitation Objectives in the matrix above may be used to 

represent the three specific Rehabilitation Objectives defined in 

Sections 1.4.1, 1.4.2, and 1.4.3, as follows: 

 Basic Safety Objective (BSO) k and p 

 Enhanced Objectives k and m, n, or o 

 p and i or j 

 k and p and a, b, e, or f 

 m, n, or o alone 

 Limited Objectives k alone 

 p alone 

 c, d, g, h, or l alone 

Figure 5-9 ASCE 41 Rehabilitation Objectives 

(ASCE, 2006b). 

Figure 5-8 ASCE 41 Target Building 

Performance Levels 

(ASCE, 2006b). 
5-18

Engineering Guideline for Incremental Seismic Rehabilitation 

Data collection is an important consideration within ASCE 41. The extent 

to which material strengths and details of construction are known will have 

a significant effect on analytical simulations of building response, and on 

uncertainty in the resulting estimate of building performance. ASCE 41 

encourages explicit and comprehensive investigation to maximize 

knowledge of the building and minimize unknowns. 

Because of differences in criteria between evaluation and rehabilitation 

design, rehabilitation measures designed using ASCE 41 may differ 

somewhat from rehabilitation measures identified in an ASCE 31 

evaluation. These differences should be anticipated and considered in the 

implementation of an incremental seismic rehabilitation program. 

5.8.3 Prioritization of Rehabilitation Measures 

Since rehabilitation work will be staged over an extended period of time, 

some rehabilitation measures will be implemented sooner, and others will 

be implemented later. Rehabilitation measures can be prioritized based 

on: 

 structural priority, 

 use priority, and 

 integration priority. 

The most advantageous sequence of work will depend on the relative 

seismic risk reduction benefits and opportunity for performing the work. 

Often, priorities will begin with structural considerations and will then be 

adjusted based on facility use and opportunity for integration. 

Structural Priority. Structural priority is influenced by relative impact on 

overall seismic performance. Deficiencies that will result in damage with a 

high consequence of casualties, property loss, or loss of use should be 

mitigated first. Similarly, rehabilitation measures that will have a large 

impact on reducing potential damage (and consequences resulting from 

that damage) should be implemented first. 

The commentary in Chapter 10 of ASCE 41 provides a list of deficiencies 

for each model building type, ranked from highest to lowest priority in 

terms of the severity of the deficiency. This can be used as a general 

guide for establishing structural priority, although the ranking can vary 

somewhat for individual buildings. Examples of these tables are shown in 

Figure 5-10. 

To assist in understanding the impact and damage reduction potential of 

various rehabilitation measures, the occupancy manuals in the FEMA ISR 

Series provide tables that list possible structural and nonstructural seismic 

performance improvements along with their intended purpose. These 

tables identify what actions could be undertaken and what the expected 

outcome would be, which can be used to assist in assigning structural 

priority within each occupancy category. Excerpts from one set of tables 

are shown in Figure 5-11 and Figure 5-12. A complete set of tables is 

provided in each occupancy manual. 
 5-19 

 Chapter 5 

Figure 5-10 Tables of ranked deficiencies for Steel Moment Frame and Steel Braced Frame model 

building types (ASCE, 2006b). 

Figure 5-11 Excerpt from table of structural seismic performance improvements (FEMA 395). 

Table C10-4. S1 and S1A: Steel Moment Frames 

with Stiff or Flexible Diaphragms 

Typical Deficiencies 

Load Path 

 Redundancy 

 Vertical Irregularities 

 Plan Irregularities 

 Adjacent Buildings 

 Uplift at Pile Caps 

Steel Moment Frames 

 Drift Check 

 Frame Concerns 

 Strong Column-Weak Beam 

 Connections 

Re-entrant Corners 

 Diaphragm Openings 

 Diaphragm Stiffness/Strength 

Diaphragm/Frame Shear Transfer 

Anchorage to Foundations 

 Condition of Foundations 

 Overturning 

 Lateral Loads 

 Geologic Site Hazards 

Condition of Steel 

Table C10-5. S2 and S2A: Steel Braced Frames 

 with Stiff or Flexible Diaphragms 

Typical Deficiencies 

Load Path 

 Redundancy 

 Vertical Irregularities 

 Plan Irregularities 

 Uplift at Pile Caps 

Stress Level 

 Stiffness of Diagonals 

 Chevron or K-Bracing 

 Braced Frame Connections 

Re-entrant Corners 

 Diaphragm Openings 

 Diaphragm Stiffness/Strength 

Diaphragm/Frame Shear Transfer 

Anchorage to Foundations 

 Condition of Foundations 

 Overturning 

 Lateral Loads 

 Geologic Site Hazards 

Condition of Steel 
5-20

Engineering Guideline for Incremental Seismic Rehabilitation 

Figure 5-12 Excerpt from table of nonstructural seismic performance improvements (FEMA 395). 

An example of a code-developed approach to assigning structural priority 

is contained in the International Existing Building Code (IEBC), Appendix 

Section A404. This section applies to earthquake hazard reduction in 

existing wood-frame residential buildings that are three or more stories in 

height. Phasing is intended to address the most hazardous conditions 

first, and to avoid leaving the building in a more vulnerable condition. As 

defined in the IEBC, Phase 1 includes the ground floor, Phase 2 includes 

intermediate levels, and Phase 3 includes the remaining levels of the 

building through the top story. 

Use Priority. Use priority is influenced by the importance of current 

building use and occupancy. Buildings with higher occupant loads, critical 

functions, or high-value equipment or property should be rehabilitated 

first. Similarly, important portions of a building, such as assembly areas 

and elements of the egress system (e.g., corridors, stairs, lobbies), should 

be rehabilitated before other less critical areas. 

Use priority could also be influenced by planned future use. Some 

buildings might be scheduled for significant expansion or intensification of 

use, which should raise the priority for seismic rehabilitation in these 

buildings. In adjusting priorities and scheduling work, owners may 

consider planning alternative uses for seismically vulnerable buildings. 

Some could be scheduled for early demolition and replacement, or for 

conversion to a lower risk category of use (e.g., storage) until 

rehabilitation is complete. 

Integration Priority. Integration priority is influenced by the potential 

for integrating rehabilitation measures into other building maintenance or 

capital improvement projects that are routinely scheduled. Integration 
 5-21 

 Chapter 5 

priority is opportunistic in that seismic rehabilitation work is accomplished 

when other work is being undertaken, or when portions of the building are 

otherwise vacant. This reduces the cost of the seismic rehabilitation 

action by taking advantage of construction mobilization, access to the area 

of work, and disruption of occupancy and use that would have occurred 

anyway. 

Integration priority is affected by the nature, location, and extent of work. 

Rehabilitation measures that can be accomplished with the lowest 

additional cost and least disruption to building use are generally scheduled 

first. Examples of integration priorities are illustrated in Figure 5-13, and 

described below: 

 Work that can be accomplished from the exterior (roofs, exterior 

walls, and basements) with little or no effect on interior space 

use 

 Work that can be accomplished in localized spaces in the interior 

of the building (e.g., corridors) 

 Work that must be accomplished in spaces spread throughout 

the building (these may be tenant spaces and/or common 

spaces) 

 Work that requires access to concealed spaces 

 Work that involves mechanical, electrical, and plumbing 

systems 

Figure 5-13 Prioritization of work based on integration opportunities: (1) roof work; (2) 

exterior wall work; and (3) localized interior work (FEMA ISR Series). 
5-22

Engineering Guideline for Incremental Seismic Rehabilitation 

5.8.4 Identification of Integration Opportunities 

Maintenance and capital improvement activities vary by occupancy 

category. In general, these activities include: 

 Roofing maintenance and repair/re-roofing 

 Exterior walls maintenance and repair/window replacement 

 Fire and life safety improvements 

 Modernization/remodeling/accommodation of new technology 

 Underfloor and basement maintenance and repair 

 Energy conservation/weatherization/air conditioning 

 Hazardous materials abatement 

 Accessibility improvements 

The occupancy manuals in the FEMA ISR Series include matrices showing 

specific structural and nonstructural seismic performance improvements 

that can be integrated with their occupancy-specific maintenance and 

capital improvement activities. An excerpt from one set of matrices is 

shown in Figure 5-14. A complete set of matrices is provided in each 

occupancy manual. 

Level of

N LMH *rebmu Seismic Performance Improvement

Nonstructural

1 a/n n ts a/ ixEtaseiponaCfoegarohcnA       

2 a/n n nt a/ empiuqEpotfooRfogniliateDdnaegarohcnA       

5 a/n a/n dna,noitatnemanrO,selbaG,steparaPfognicarB

segadneppA       

8 a/n n rk a/ owtcuDegraLfognicarBdnatnemhcattA       

81 a/n n ys a/ enmihCfolavomeRrognicarB       

Structural

a/n llA

stnemelE srotcelloCdnahtaPdaoL       

a/n latnoziroH

stnemelE D es smgarhpai iradnuoBtagninehtgnertSdnatnemhcattA       

a/n latnoziroH

stnemelE D ss smgarhpai enffitS/htgnertS       

a/n latnoziroH

stnemelE D gs smgarhpai ninepOtagninehtgnertS     

a/n latnoziroH

stnemelE D rs smgarhpai enroCtnartne-eRtagninehtgnertS       

a/n latnoziroH

stnemelE D te smgarhpai ercnoCtsacerProfbalSgnippoT    

a/n lacitreV

stnemelE L on htaPdao itcennoCmgarhpaiDotmetsySgnitsiseRlaretaL       

a/n lacitreV

stnemelE

yrnosaMroetercnoCfoegarohcnAenalP-fo-tuO

llaW      

.esufoesaerofderebmunerastnemevorpmilarutcurtsnoN*

ybdezinagro,rehtartub,derebmuntonerastnemevorpmilarutcurtS .metsys-busdnatnemelelarutcurts

 .lanoisseforpngisedaybnoitaulavekciuqafosisabehtnotcejorpriaper/ecnanetniam/noitatilibahergnidliubehtnidedulcniebyamtahtkroW

 .ngisedgnireenignegniriuqerkroW

 gnissertsrevo,sdaoletubirtsiderdluoctahtkrowsetangised"x"ehT.stnemeriuqergnicneuqesfonoitaulavednasisylanagnireenignedeliatedgniriuqerkroW

.stnemeleemos

:1etoN .snoitporofmgarhpaidetercnoc,gnidliubetercnocehtesudluohsfooretercnocahtiwsgnidliubyrnosaM

Seismicity

Vertical Load Carrying Structure

Building

Structural

Element

Structural

Sub-System

Wood Concrete Steel Masonry1

Figure 5-14 Integration opportunities for roofing maintenance and repair (FEMA 400). 
 5-23 

 Chapter 5 

These matrices classify seismic performance improvements by level of 

seismicity, building structural element, structural subsystem, and verticalload-carrying structure. Depending on the building type and the specific 

seismic performance improvement, implementation could require one of 

three levels of engineering involvement: quick evaluation, engineering 

design, and detailed engineering analysis. These are identified by symbols 

in the matrices, as shown in Figure 5-15. 

Figure 5-15 Classification of integration opportunities by extent of 

engineering required (FEMA ISR Series). 

5.8.5 Definition of Appropriate Rehabilitation Increments 

It is possible that implementation of selected rehabilitation measures in 

certain portions of a building can increase seismic demands on other 

portions of a building, resulting in a condition that is more vulnerable or 

less conforming than when work was initiated. Rehabilitation measures 

that introduce vertical or horizontal irregularities in strength or stiffness, 

particularly in buildings with rigid diaphragms, should be avoided. 

Rehabilitation measures should be packaged into logical increments that 

can fit within the scope of a maintenance or capital improvement project 

and result in a rational incremental improvement in seismic performance. 

This can result in the need for iterative design processes and additional 

analyses of partial rehabilitation stages to understand the potential 

impacts of the following: 

 Partial changes to the seismic-force-resisting system: 

partial increases in strength or stiffness that create temporary 

irregularities and could result in instability. Work should result 

in balanced changes to the seismic-force-resisting system. 

 Partial strengthening in selected areas: work done in local 

areas that creates a concentration of seismic demand in the 

area that might not have been anticipated. Work should avoid 

creating “hard spots” in a building that concentrate seismic 

demands in areas that cannot resist these demands. 
5-24

Engineering Guideline for Incremental Seismic Rehabilitation 

 Vertical seismic improvements: changes in strength or 

stiffness in one story that create a vertical discontinuity that 

overloads elements in adjacent stories. Strengthening “from 

the ground up” helps to avoid this effect. 

 Element connection upgrades: strengthening connections 

between elements (e.g., out-of-plane connections on heavy 

exterior walls) that delivers loads to locations in the building 

that may or may not be able to resist them. Rehabilitation 

increments should consider potential impacts along the entire 

seismic load path. 

5.9 Staging Seismic Rehabilitation Increments 

Staging of seismic rehabilitation increments involves determining the 

number and scope of incremental stages that will be undertaken and the 

length of time over which the entire rehabilitation plan will be 

implemented. While structural priority and use priority can factor into 

when a rehabilitation increment should take place, staging of rehabilitation 

increments is primarily driven by integration opportunities. 

As part of the planning process, rehabilitation measures are grouped into 

logical packages for effectively improving seismic performance. Staging of 

seismic rehabilitation increments consists of matching an increment with 

an appropriate maintenance or capital improvement project, and mapping 

out subsequent increments within occupancy-specific maintenance and 

capital improvement schedules. 

5.9.1 Coordination with Tenant Work 

Specific to commercial office occupancies, major tenant improvement work 

offers a unique opportunity for staging of seismic rehabilitation 

increments. This is most likely to occur in the case of large commercial 

tenants with long-term leases. Large tenants conducting major 

improvements in their space will often have their own design professionals 

and contractors. Incremental seismic rehabilitation work performed by the 

owner in conjunction with major tenant improvement work performed by 

commercial tenants will require close coordination between the owner’s 

design professionals and contractors, and those of the tenant. 

5.10 Seismic Rehabilitation Project Management 

Seismic rehabilitation project management primarily refers to 

management of seismic rehabilitation construction projects as they are 

implemented within other maintenance and capital improvement work. 

Also known as construction management or construction support services, 

this effort involves ensuring that plans, specifications, and quality 

assurance provisions are properly implemented in the construction of 

seismic rehabilitation measures. 

 
 6-1 

 Chapter 6 

Chapter 6 Incremental Seismic 

Rehabilitation Needs 

and Possibilities 

As a partner in the National Earthquake Hazards Reduction Program 

(NEHRP), FEMA has invested significant effort and funding in the 

development of guidelines and procedures to promote earthquake hazard 

reduction in existing buildings. Incremental seismic rehabilitation offers a 

way of eliminating some of the barriers to implementation of seismic 

rehabilitation and expanding earthquake risk reduction activities in the 

United States. 

Validation of the basic concept of incremental seismic rehabilitation is 

critical to its successful implementation. The engineering and building 

regulatory communities must be convinced of the feasibility of the 

incremental approach, if it is to be used. Necessary safeguards and 

limitations must be defined to avoid the unintended temporary reduction 

of seismic resistance, and building owners must be convinced that the 

incremental approach offers adequate cost and use benefits to make 

seismic mitigation financially attractive. 

6.1 Political, Social, and Economic Possibilities 

Public policy and regulatory issues are critical to implementation of seismic 

rehabilitation programs. In the 2008 NEHRP Workshop on Meeting the 

Challenges of Existing Buildings, held in San Francisco, California, 

increased political will to support mitigation measures was identified as the 

most valuable contribution for meeting challenges faced by our existing 

building stock. The biggest impediment to seismic rehabilitation was 

identified as the lack of market forces aligned to support such activities 

(ATC, 2008). 

In Brief 

This chapter: 

 Describes the 

political, social, and 

economic possibilities 

of incremental 

seismic rehabilitation 

 Explains how 

incremental seismic 

rehabilitation can 

affect decisionmaking and program 

management 

 Recommends actions 

to assist in the further 

development and 

acceptance of 

incremental seismic 

rehabilitation 
6-2

Engineering Guideline for Incremental Seismic Rehabilitation 

Political entities are concerned with the safety of their constituents, but 

numerous impediments to implementation of mandated seismic 

rehabilitation programs exist. The economic burden of construction cost 

and disruption that must be borne by building owners and occupants is the 

most obvious impediment. Economic incentives can offset some of the 

cost, but incentive programs have generally not been substantial enough 

to overcome resistance. 

Balancing seismic safety against political, social and economic factors is 

not easy. Incremental seismic rehabilitation offers a solution to cost and 

disruption disincentives for seismic rehabilitation in existing buildings, and 

can be an effective measure for public officials to consider. 

6.2 How Can Incremental Seismic Rehabilitation Affect 

Decision-Making and Program Management? 

The FEMA ISR Series presents seismic rehabilitation within the context of 

occupancy-specific facility management processes. It communicates 

decisions on seismic risk and seismic rehabilitation investment in terms 

that can be related to normal maintenance and capital improvement 

activities and expenditures. It explains how seismic rehabilitation can be 

incorporated into business continuity planning. 

Building owners are accustomed to making periodic investments to repair 

and improve existing facilities. There is also precedent for such work to 

trigger upgrades to certain aspects of their facilities (e.g., fire and lifesafety upgrades, Americans with Disabilities Act modifications). The 

process of incremental seismic rehabilitation presents owners with a new 

paradigm in which seismic rehabilitation is a regular part of ongoing 

maintenance and capital improvement activities, and that reduction in 

earthquake risk will be in their long-term best interest. It presents an 

opportunity for seismic rehabilitation to be infused directly into the 

program management and decision-making process. 

6.3 What is needed to Further Promote Incremental 

Seismic Rehabilitation? 

Development of the approach described in the FEMA ISR Series included 

studies on the economic and technical validity of incremental seismic 

rehabilitation. Further development and acceptance will be based largely 

on its continued use. Recommendations for possible ways to help expand 

the use of incremental seismic rehabilitation include: 

 Advocacy at national and regional building owners’ associations 

by occupancy type 

 National advocacy at the model code development level 

 Local advocacy at the local code administrative level 

 Political advocacy to affect public policy on earthquake safety 

 Creation of an incremental seismic rehabilitation case studies 

repository 

 Collection of additional data on economic viability 
 6-3 

 Chapter 6 

6.4 Summary and Conclusions 

Incremental seismic rehabilitation offers a way of eliminating potential 

cost and disruption barriers to implementation of seismic rehabilitation. It 

offers flexibility in the sequence and timing of rehabilitation actions, and 

can be more cost-effective than a delayed, single-stage rehabilitation 

project. The concept of incrementally improving the seismic-forceresisting system of an existing building is permitted in the language 

contained in current national model building codes and standards, and 

similar ideas have been present in the history of building regulations. 

Engineering procedures associated with typical engineering practice for 

single-stage projects are applicable to incremental seismic rehabilitation. 

In some cases, however, engineering services may require more effort to 

implement within the context of incremental seismic rehabilitation. The 

overall approach to incremental seismic rehabilitation utilizes owner 

maintenance, capital improvement and decision-making needs as a basis 

for effectively communicating with stakeholders on seismic rehabilitation 

opportunities and encouraging active mitigation of seismic risk. 

 A-1 

 Appendix A 

Appendix A Case Study Example – 

Seattle Public Schools 

Incremental Seismic 

Rehabilitation 

Program 

This appendix presents a case study illustrating how an overall 

incremental seismic rehabilitation program was implemented for Seattle 

Public Schools in Seattle, Washington. It discusses seismic screening, 

seismic evaluation, rehabilitation planning, and staging of rehabilitation 

increments in the Seattle Public Schools building inventory, and includes 

budget information for reference. 

A.1 Introduction 

The Juan de Fuca plate is located off the coast of Washington, Oregon and 

Northern California. It is the source of shallow earthquakes widely 

distributed over Washington, and deep earthquakes in the western parts 

of Washington and Oregon. Large earthquakes are anticipated about 

every 35 years, although there is some disagreement over the recurrence 

interval. Earthquakes of magnitude 8 or greater are suggested by the 

geology, but none has occurred in the past 150 years. The return period 

for large-magnitude earthquakes appears to be several hundred years. 

Seattle Public Schools has a long history of seismic awareness dating back 

to 1949 when several schools were damaged in an earthquake near 

Olympia, Washington. Seismic surveys of schools began in Seattle in 

1977. Additional surveys were carried out in 1978 and 1979. A 

comprehensive survey of all Seattle schools was completed in 1983 as 

part of a long-range capital improvement plan. It was under this plan that 

In Brief 

This appendix: 

 Illustrates the 

implementation of an 

incremental seismic 

rehabilitation program 

 Shows how 

incremental seismic 

rehabilitation work 

was planned and 

staged 

 Provides budget 

information for 

reference 
A-2

Engineering Guideline for Incremental Seismic Rehabilitation 

integrated incremental seismic rehabilitation was initiated and carried out 

under two financing programs, the Capital Levy Program (CLP) and the 

Capital Improvement Program (CIP). The approach was refined with 

further studies in 1991 and 1992, and has continued under renewed 

funding to the present. 

A.2 Regulatory Context 

In 1955, the Washington state legislature passed statewide Earthquake 

Resistance Standards covering hospitals, schools, public assembly 

buildings, and all public-owned structures. The Uniform Building Code

(UBC) was adopted statewide, effective in 1978, and local jurisdictions 

were provided with the authority to adopt more stringent requirements. 

All buildings, including state-owned buildings, are subject to local code 

enforcement in Washington. 

The city of Seattle has code enforcement jurisdiction over Seattle Public 

Schools. In the case of existing buildings undergoing “extensive 

rehabilitation,” as defined in the Seattle Building Code, seismic 

strengthening is required. In such cases, the Uniform Code for Building 

Conservation (UCBC) is one option for seismic criteria, but is not required. 

The Seattle Public Schools seismic rehabilitation work has been primarily 

voluntary. 

A.3 Seismic Screening of the Building Inventory 

The Seattle Public Schools seismic program is based on a detailed 

inventory of the buildings and their components, including detailed seismic 

analysis results, and cost estimates. It demonstrates how a database is 

essential to the support of long range incremental seismic rehabilitation 

strategic planning. 

A utilization study identified five schools as “imminent hazards” and led to 

the Seismic Survey of 22 Seattle Schools, dated November 30, 1977. 

Three engineering firms conducted “limited observations of structural 

elements and a brief design review” of buildings consisting of masonry 

bearing walls and wood floors and roofs. Engineers recommended three 

levels of work (cost estimates were provided) involving: 

 Imminent hazards consisting mostly of parapets, gables, 

chimneys, and loose or poorly anchored masonry 

 Limited floor and roof ties, diaphragm reinforcement, and added 

shear walls 

 Present code requirements 

This was followed by the Seismic Survey of 10 Schools and Chimneys at 

53 Schools, dated September 6, 1978. Ten schools were inspected, 

consisting of masonry bearing walls and reinforced concrete or wood 

floors. Information on the chimneys at 53 schools was obtained by a 

questionnaire. Engineers recommended work to remove the imminent 

hazards, and cost estimates were provided. 

This in turn was followed by Seismic Inspections, 87 Schools, dated 

August 10, 1979. This survey was carried out by a district building 
 A-3 

 Appendix A 

inspector and a brick mason from the maintenance section. The survey 

found that 50 schools required no seismic work, 12 required “some 

attention to skylights only,” and 25 had problems which could be 

considered “grave risk hazards.” For the latter, items of corrective work 

were identified, but costs were not estimated. The report concluded that 

“with adequate funding, specifications can be prepared and work 

completed by the start of the 1980-81 school year.” 

A.4 Seismic Evaluation of Individual Buildings 

In 1982, the Seattle Public Schools commissioned CMB/KIM Architects & 

Engineers to carry out a comprehensive survey of all school buildings. A 

preliminary report consisting of three volumes and entitled Comprehensive 

Survey of Educational Facilities, Seattle School District No.1 was published 

on April 8, 1983. The study consisted of two basic parts: 

 An inventory and categorization of deficiencies 

 A seismic analysis of every building 

The deficiency inventory was based on a field inspection of each site by a 

minimum of five professionals, including an architect, a structural 

engineer, a mechanical and electrical engineer, and a certified roofing 

inspector. Approximately 50 man-hours were spent at each site, and 

about 6,000 deficiencies were documented at 101 sites. Deficiencies were 

prioritized in terms of their level of risk and the potential impact of nonaction. Hazardous conditions were prioritized under special procedures, 

and received immediate attention. 

The seismic analysis for each facility consisted of seven parts: 

 Field inspection and evaluation 

 Reporting of major deficiencies 

 Computation of ratings in terms of structural and nonstructural 

quality 

 Establishment of probabilities of occurrence for major 

earthquakes 

 Determination of possible site-dependent amplification due to 

poor soil conditions 

 Computation of risks (in terms of damage and casualties) 

 Comparisons with other commonly accepted risks 

This report concluded that “the majority of facilities exceed an ordinary 

level of acceptable risk. These structures should be strengthened or 

retired as soon as monetary resources permit it. The methodology taken 

in this evaluation is directed towards establishing procedures and priorities 

to reduce the risks to acceptable levels.” 

Since 1982, the approach to seismic rehabilitation under both the Capital 

Levy Program and the Capital Improvement Program was periodically 

refined. Over this same time period, significant changes occurred in the 

seismic requirements of the building code, reflecting a greater 

understanding of building performance in earthquakes. In order to keep 

pace with these changes, Seattle Public Schools undertook two new 

engineering studies that produced two new reports in 1991. 
A-4

Engineering Guideline for Incremental Seismic Rehabilitation 

The first study, entitled Structural Evaluation of Seattle Public Schools was 

published in early 1991 by TRA Architecture Engineering Planning Interiors 

of Seattle. This was a structural evaluation of the seismic resistance of all 

Seattle schools constructed before 1968, and was viewed as an update of 

the seismic portion of the 1983 report. The goal of the study was “to 

establish a minimum standard for seismic upgrade of all existing schools 

and to rate the schools relative to that standard.” 

Evaluations were based on the “Rapid Analysis Procedure” of ATC-14, 

Evaluating the Seismic Resistance of Existing Buildings (ATC, 1987), first 

published in 1987. A numerical rating was assigned in order to rank the 

buildings. A rating of 100 represented a building whose allowable shear 

stress and required shear stress are equal, and a rating of 165 

represented a new building designed to meet the 1988 Uniform Building 

Code. Ratings ranged from 20 to 750, for 166 separately identified 

buildings. Eighty-six buildings at 50 school campuses rated below 100. 

The 50 school campuses with ratings below 100 were subjected to further 

structural analysis by Dodd Pacific Engineering, Inc. of Seattle and San 

Francisco. This analysis was based on a review of drawings, but without 

site visits. The results of the analyses were used to prepare 

recommendations to eliminate major structural deficiencies, eliminate 

major nonstructural deficiencies, and develop preliminary construction 

cost estimates. Each building was assigned a priority ranking from 1 

(highest) to 7 (lowest). The results of this study were published in a 

report entitled Abbreviated ATC-14 and ABK Seismic Evaluations, and 

Preliminary Construction Cost Estimates in 1991. 

A.5 Seismic Rehabilitation Planning and Design 

Between 1986 and 1991, the Capital Improvement Program Phase I 

(CIP-I) resulted in the modernization or replacement of 14 elementary 

schools and one high school, at a cost of about $140 million (of which 

about $40 million were State funds). The program utilized data from the 

1983 CMB/KIM Architects and Engineers report. 

In early 1992, Seattle Public Schools published two related reports, a 

Proposed Facilities Master Plan 1992 to 2010, and a Proposed Phase II 

Capital Improvement Program. Following extensive public review, these 

documents were revised and adopted by the Board of Directors, and 

published as Superintendent's Final Recommendations – 2010 Facilities 

Master Plan and Capital Improvement Program Phase II on July 15, 1992. 

The plan states that “more than a third of Seattle schools are already 60 

years or older. Many are in poor condition and have outdated electrical, 

heating and ventilating systems. Forty percent still need significant work 

to improve resistance to earthquakes. Many lack the space and 

technology needed to educate today's students to be successful in 

tomorrow's competitive world.” 

The Board adopted 11 goals for Seattle Public Schools facilities, including 

the following: 

 Assure that buildings meet health and safety standards with 

regard to seismic, fire, and lighting 

 Provide safe, secure and efficient buildings from which essential 
 A-5 

 Appendix A 

and vital operations can be continued if a disaster occurs 

Between 1992 and 2000, the Capital Improvement Program Phase II 

(CIP-II) included the modernization, preservation or replacement of 25 

elementary schools, two middle schools, five high schools and six 

alternative/special education schools. The estimated cost of CIP-II was 

$795 million. Approximately $695 million was to be obtained through a 

15-year bond measure, and the remaining $100 million was to be 

supplemented from other sources such as interest earnings, state 

matching funds and possible future development impact fees. An initial 

bond issue of $339 million was authorized. Capital Levy Program funds 

were made available for schools not included in CIP-II, but still in need of 

seismic and other building improvements. 

The Board adopted six criteria for CIP-II project selection and 

prioritization. These were: 

 Completion of projects left over from Capital Improvement 

Program Phase I 

 Seismic conditions 

 Condition physical systems 

 Adequacy for educational uses 

 Need for increased capacity to meet projected student 

population and desegregation goals 

 Age 

A Seismic Action Plan was developed by Seattle Public Schools staff in 

parallel with the Superintendent's Final Recommendations – 2010 Facilities 

Master Plan and Capital Improvement Program Phase II. The Seismic 

Action Plan is viewed as the culmination of all previous structural 

evaluations and studies. Scheduling of seismic work in the plan is based 

on a “worst first” approach in which schools with lower seismic ratings are 

upgraded first. 

A.6 Staging of Seismic Rehabilitation Increments 

Seattle Public Schools has been carrying out seismic rehabilitation projects 

on existing school buildings for many years under the Capital Levy 

Program and the Capital Improvement Program. The Capital Levy 

Program consists of small to medium-sized projects that replace or 

upgrade existing facilities and systems to provide students with safe and 

secure buildings. These are generally carried out during the summer 

months when the schools are out of session. The Capital Improvement 

Program consists of major projects that involve demolition and 

reconstruction or substantial rehabilitation of existing schools. 

A.6.1 Capital Levy Program (1982-1999) 

Between 1982 and 1999, about 103 schools initiated Capital Levy Program 

projects. Of these, 51 had at least one seismic rehabilitation project, and 

some had more than one. When seismic rehabilitation was coupled with 

other work, it was most often roofing, followed by exterior wall 

improvements, accessibility improvements (ADA), and corridor 
A-6

Engineering Guideline for Incremental Seismic Rehabilitation 

improvements. Table A-1 summarizes Capital Levy Program projects that 

included seismic rehabilitation work between 1982 and 1999. 

Table A-1 Seattle Public Schools Capital Levy Projects 1982-1999 

School Year Work Description School Year Work Description 

Addams 1991 Seismic Madrona* 1992 Seismic 

Alki 1991 Seismic, Corridor Magnolia 1994 Seismic, Corridor, ADA 

Allen 1993 Seismic Mann 1993 Seismic, ADA 

Arbor Heights 1985 Seismic, Roof Marshall 1993 Seismic 

Bagley 1991 Seismic, Exterior McDonald 1993, 

1998 

Seismic 

Seismic, ADA 

Ballard* 1993 Seismic, Gutters & Downspouts McGilvra 1992 Seismic 

Blaine 1992 Seismic, Corridor Meany 1991 Seismic, Roof 

Boren* 1999 Seismic, Roof, Hazmat, Fire Alarms Memorial Stad. 1994 Seismic, Roof 

Brighton 1994 Seismic, Corridor, ADA Minor 1993 Seismic, ADA 

Bryant* 1989 Seismic Monroe 1998 Seismic, ADA 

Coe* 1993 Seismic Northbeach 1989 Seismic 

Columbia 1989 Seismic, Roof Northgate 1987 Seismic, Roof 

Concord* 1989, 

1992 

Seismic 

Seismic 

Pinehurst 1994 Seismic, Roof, Exterior 

Dearborn Park 1991 Seismic, Roofing Rainier Beach* 1992 Seismic, Roof 

Decatur 1989 Seismic Rogers 1987, 

1993 

Seismic, Roof 

Seismic 

Dunlap* 1993 Seismic Roosevelt 1993 Seismic, Roof 

Garfield 1999 Seismic, Windows, Arts/Science 

Improvements 

Sacajawea 1997 Seismic 

Genessee Hill 1985, 

1997 

Seismic, Roof 

Seismic 

Schmitz Park 1991 Seismic 

Greenwood* 1987 Seismic, Structural Seward* 1984, 

1991, 

1993 

Seismic, Windows, A/C 

Seismic 

Seismic 

Hamilton 1990 Seismic, Roof, Exterior Sharples 1994 Seismic, Roof, Exterior 

Highland Park* 1993 Seismic, ADA Stevens* 1993 Seismic, Roofing, ADA 

Hughes 1998 Seismic, ADA Whitman 1995 Seismic 

Latona* 1989, 

1992 

Seismic 

Seismic 

Wilson 1999 Seismic, Roof 

Lowell 1993 Seismic, ADA Van Asselt 1991 Seismic, Exterior 

Loyal Heights 1991 Seismic, Exterior West Seattle* 1993 Seismic, ADA 

Madison 1994 Seismic, Roof, Exterior 

*Schools scheduled for replacement or gut rehabilitation in the Capital Improvement Program

A.6.2 Buildings, Technology and Athletics Levy (1998-2004) 

In 1998, Seattle Public Schools implemented a new Capital Levy Program 

called the Buildings, Technology and Athletics (BTA) Levy. This was a sixyear program to finance more than 465 small and large facility 

improvement projects at every school in the District (112 schools). Voters 

approved $150 million for this program, extending through 2004. About 

$139 million was budgeted for school improvements and $11 million was 

budgeted for computer equipment. 
 A-7 

 Appendix A 

Work included improvements to building systems, technology 

infrastructure, and athletic facilities. About $59 million of the total was 

allocated to the following building system upgrades (which include seismic 

work): 

 Completion of the seismic mitigation program started in the 

early 1980s 

 Replacement of the most critical roofs (this work included 

seismic upgrade of diaphragms and improved diaphragm 

connections, if necessary, but was not classified as seismic 

work) 

 Replacement of windows to protect the building and improve 

energy efficiency 

 Provision of life safety improvements including upgrades to fire 

alarms, better ADA access, elevators, and selected hazards 

materials abatement 

 Replacement of heat pumps at the end of their useful life 

 Improvement of science and art facilities in all secondary 

schools 

These improvements were planned to be implemented during the summer 

months while the schools were closed. The individual scopes of work were 

packaged into a variety of small projects to meet these goals. 

Table A-2 shows a breakdown of the building system improvements with 

dedicated seismic work. Projects at 24 schools had dedicated seismic 

work in this program. Prior seismic work occurred at 11 of these schools. 

The absolute dollar value and percentage related to seismic work varies 

significantly between schools. Overall, the table shows a total budget of 

$6.9 million for dedicated seismic work, and another $6.7 million of roof 

work (a portion of which included seismic). In this program, seismic work 

on average accounted for 30% of the building budget at schools with 

dedicated seismic work, 12% of the total budget for building 

improvements, and about 5% of the budget for the overall BTA Levy 

program. 

A.7 Local Jurisdictional Issues 

Local jurisdictional problems (e.g., plan check and permit approval) in 

combining seismic work with other work categories have not been 

reported. Technical problems, such as increasing building vulnerability 

through partial incremental improvements, have not been reported. 

A.8 Legal/Liability Issues 

Incremental seismic strengthening has been practiced by Seattle Public 

Schools since the early 1950s. No legal problems have been reported. 
A-8

Engineering Guideline for Incremental Seismic Rehabilitation 

Table A-2 Buildings, Technology and Athletics Levy Projects with Dedicated 

Seismic Work 

School Prior Seismic 

Projects 

Total Building 

Program ($) 

Roof 

($) 

Seismic 

($) 

Percent Seismic 

(%) 

Marshall 1993 1,489,676 279,120 350,000 23% 

Rainier Beach 1992 2,592,847 1,021,020 39% 

Roosevelt 1989/1993 2,545,206 300,000 350,000 14% 

Denny 1,344,132 724,500 265,766 20% 

Madison 1994 800,179 350,000 44% 

McClure 869,736 556,206 64% 

Meany 1991 321,048 18,018 6% 

Arbor Heights 1985 1,157,910 453,338 423,191 37% 

Broadview 894,584 741,526 105,105 12% 

Fairmont Park 275,164 15,683 85,586 31% 

King 563,162 390,829 79,580 14% 

Laurelhurst 552,643 213,184 230,250 42% 

Loyal Heights 1991 676,950 165,179 230,250 34% 

North Beach 1989 159,920 58,559 37% 

Rainier View 534,774 325,086 67,568 13% 

Roxhill 655,952 482,265 22,523 3% 

Sacajawea 1997 495,367 367,500 74% 

Decatur 1989 829,932 456,058 373,874 45% 

Boren/Cooper 1,649,550 1,200,000 173,250 11% 

Hay NOMS 2,131,695 638,652 290,312 14% 

Hughes 595,123 127,575 420,000 71% 

Magnolia 1994 604,849 215,250 36% 

McDonald 1993 908,452 190,062 614,114 68% 

Monroe 568,372 247,919 44% 

 

Totals 23,217,223 6,703,057 6,915,841 30% 
 B-1 

 Appendix B 

Appendix B Case Study Example – 

Staging of Seismic 

Rehabilitation 

Increments 

This appendix presents a case study showing how seismic rehabilitation 

increments were staged in a privately-owned retail/office building located 

in Southern California. It is intended to illustrate one portion of the 

incremental seismic rehabilitation process in some detail (see Figure B-1), 

while omitting discussion on other portions of the process. In this 

example, mandatory compliance with specified criteria was triggered by 

the local jurisdiction. Seismic evaluation and rehabilitation design 

activities were performed (though not described here). Since there was 

considerable flexibility in the timeline for compliance, the owner decided 

on an incremental approach to performing the necessary work. An 

incremental seismic rehabilitation program was implemented to take 

advantage of scheduled maintenance (e.g., roof replacement) and 

occupancy turnover in the major tenant areas located throughout the 

building. 

B.1 Building Description 

The case study building is a two story unreinforced masonry (URM) 

bearing wall structure built in the early 1900s. It is an occupied historic 

building in the downtown district of the city. The first floor is used for 

retail sales and the second floor is used for offices. Given these uses, 

FEMA 397, Incremental Seismic Rehabilitation of Office Buildings (FEMA, 

2003), and FEMA 399, Incremental Seismic Rehabilitation of Retail 

Buildings (FEMA, 2004), would be applicable. 

In Brief 

This appendix: 

 Explains how seismic 

rehabilitation 

increments were 

staged in an individual 

building 

 Describes a set of 

rehabilitation 

measures typical of 

unreinforced masonry 

construction 

 Illustrates one 

approach to 

construction phasing 
B-2

Engineering Guideline for Incremental Seismic Rehabilitation 

The building measures approximately 29 feet wide by 90 feet long, with a 

single-story addition of reinforced concrete masonry block located in the 

rear. The walls are 13-inch unreinforced brick masonry founded on a 

concrete perimeter foundation. The first floor consists of wood joists 

spanning between wood girders supported on small concrete piers. The 

first floor diaphragm is a double layer of diagonal and straight wood 

sheathing. 

The second floor consists of 2x14 wood joists spanning the width of the 

building, sheathed with diagonal and straight wood sheathing. The roof 

consists of 1x6 straight wood sheathing spanning between carpenter 

trusses at 24 inches on center. Unreinforced masonry parapets extend 

above the roof in heights ranging from 20 to 48 inches. 

Figure B-1 Portion of the incremental seismic rehabilitation process illustrated in the case 

study example of Appendix B. 

B.2 Regulatory Context 

Unreinforced masonry buildings have been the cause of deaths and 

injuries in past earthquakes. In 1987, California adopted legislation 

requiring all local jurisdictions in Seismic Zone 4 (the highest seismic 

zone) to survey and identify URM buildings, and to notify building owners 

of the findings. In response to this potential hazard, many local 

jurisdictions adopted a variety of regulations with mandatory hazard 

reduction measures. Many such regulations included installation of 

parapet bracing and out-of-plane wall anchors. 

In the jurisdiction in which this case study building was located, owners 

were notified of their URM status and required to have seismic 

rehabilitation plans and calculations prepared and submitted for plan 

check. Seismic design work was based on the criteria contained in 

Appendix 1 of the Uniform Code for Building Conservation, which is now 

Appendix Chapter A-1 of the International Existing Building Code (ICC, 

2006). 

While the development of rehabilitation plans and calculations were 

required, no completion date for the construction work was specified at 

that time (1989). This flexibility in compliance opened the door to 

consider phasing of seismic strengthening work in increments. How 

eventual compliance was integrated into future tenant changes and 
 B-3 

 Appendix B 

maintenance cycles, and how rehabilitation work was packaged to 

incrementally improve seismic performance, are discussed in the sections 

that follow. 

B.3 Rehabilitation Measures 

A seismic evaluation was performed. The case study building was found 

to contain many seismic deficiencies typical of unreinforced masonry 

bearing wall construction. Rehabilitation designs were prepared. The 

following rehabilitation measures were planned to address deficiencies 

identified in the case study building: 

Parapet Bracing. Due to their unbraced height, parapets on all walls 

required bracing. Parapet bracing consisted of a horizontal steel channel 

located about 12 inches below the top of the wall, braced by steel angles 

anchored to the roof. 

Wall-to-Roof Anchorage. The unreinforced masonry walls required both 

out-of-plane anchors and in-plane shear force connections to the roof 

diaphragm. Anchors consisted of epoxy (adhesive) anchors installed at an 

angle of 22.5 degrees into the wall. Options included a through-bolt 

configuration, which was not selected in order to avoid impacts to the 

façade and disruption of an adjacent building. 

Wall Stability Bracing. The second floor wall exceeded acceptable 

height/thickness ratios for stability, and thus required stability bracing. 

Wall stability bracing consisted of vertical steel tubes attached to the floor 

and roof diaphragms. 

Wall-to-Second Floor Anchorage. Walls required both out-of-plane and 

in-plane anchorage at the second floor level, similar to details used at the 

roof. 

Lateral Bracing at Open Front. Because of a large entry door and 

windows, there was no lateral bracing across the front of the building. A 

two-story steel frame was needed one column line inside the building to 

provide the necessary lateral bracing at the front of the building. 

Lateral Bracing at Rear Wall. At the time when the one-story addition 

was constructed, most of the original rear wall was removed. To provide 

adequate lateral bracing at the back of the building, a layer of reinforced 

shotcrete was required on the remaining portions of the wall, and a 

collector was needed to deliver loads to the reinforced wall. 

Crosswalls. The existing roof diaphragm did not have sufficient capacity 

to span between existing shear wall elements without excessive 

deformation. Wood crosswalls were needed in the second story to couple 

the roof diaphragm to the stiffer second floor diaphragm to minimize 

diaphragm deflections. This option was chosen in lieu of creating a new 

roof diaphragm by placing a layer of plywood over the roof. 
B-4

Engineering Guideline for Incremental Seismic Rehabilitation 

B.4 Staging of Seismic Rehabilitation Increments 

Because of flexibility in the URM compliance timeline, the building owner 

had two choices for scheduling the work: (1) single-stage construction; 

and (2) phased construction. A single-stage project would require 

contractor access to the entire building, forcing existing tenants to 

temporarily relocate or to move. Since the building was completely 

occupied, and generating revenue, a single stage project did not appeal to 

either the building owner or the tenants. 

The owner decided to phase the work. Specific to the facility management 

process for retail/office occupancies, rehabilitation planning included 

coordination with tenant work. The incremental rehabilitation plan was 

based on the eventual expiration of tenant lease contracts, and the 

eventual need to perform certain maintenance work in the building. The 

planned rehabilitation measures were broken into phases conducted over 

a 10-year time frame. The resulting rehabilitation increments are shown 

in Figure B-1, Figure B-2, and Figure B-3. 

Each phase resulted in an incremental improvement in the expected 

seismic performance of the building. Because of floor and roof diaphragm 

flexibility, incremental work in one area did not create a torsional 

irregularity condition in the building during intermediate phases of work. 

Phase 1. The first phase was initiated in conjunction with a planned reroofing project. Since re-roofing could be accomplished without disrupting 

the tenants, all work for this phase was detailed to be done from above 

the roof. Work in this phase included the installation of all parapet bracing 

and all wall-to-roof anchors (Figure B-3). 

Phase 2. Several years later, the tenant on the first floor vacated the 

space. Work in this phase included installation of the first story of the 

steel frame at the front of the building, including the grade beam, 

columns, and beam under the second floor. Work also included shotcrete 

installation on the rear shearwall, and installation of all wall-to-second 

floor anchors from below the second floor (Figure B-1). 

Phase 3. When the tenant located in the front portion of the second floor 

decided to move, this provided an opportunity to work in about half of the 

second floor area. Work in this phase consisted of completing the second 

story of the steel frame at the front of the building, installation of the wall 

stability braces, and installation of crosswall extensions in this area of the 

building (Figure B-2). 

Phase 4. Eventually the rear portion of the second floor was vacated and 

the work could be completed. Work in this phase included installation of 

the remaining wall stability braces and the remainder of the crosswall 

extensions (Figure B-2). 

Additional work was also done during the various phases of construction. 

The owner took these opportunities to update and improve the electrical 

system, install accessible toilets, provide new finishes on the walls and 

ceilings, and upgrade mechanical (HVAC) systems. 
 B-5 

 Appendix B 

Figure B-2 First floor plan and rehabilitation increments (graphic courtesy of M. Green). 
B-6

Engineering Guideline for Incremental Seismic Rehabilitation 

Figure B-3 Second floor plan and rehabilitation increments (graphic courtesy of M. Green). 
 B-7 

 Appendix B 

Figure B-4 Building cross-section and rehabilitation increments (graphic courtesy of 

M. Green). 

 C-1 

 Appendix C 

Appendix C Other Existing Building 

Resource Documents 

This appendix lists other relevant existing building resource documents 

that could be applicable to the development and implementation of an 

incremental seismic rehabilitation program. 

C.1 Relevant Resources from the FEMA Existing 

Buildings Program 

FEMA’s Existing Buildings Program is part of the National Earthquake 

Hazard Reduction Program (NEHRP). Under this program, FEMA has 

developed a collection of documents related to earthquake hazard 

mitigation. Additional information is available on the FEMA website at 

http://www.fema.gov/plan/prevent/earthquake/. Other FEMA documents 

that could be applicable to the development of an incremental seismic 

rehabilitation program include: 

 FEMA 74, Reducing the Risks of Nonstructural Earthquake 

Damage: A Practical Guide, Third Edition, 1994 

 FEMA 156, Typical Costs for Seismic Rehabilitation of Existing 

Buildings, Volume 1 - Summary (Second Edition), 1994 

 FEMA 227, A Benefit-Cost Model for the Seismic Rehabilitation of 

Buildings, Volume 1: A User’s Manual, 1992 

 FEMA 255, Seismic Rehabilitation of Federal Buildings: A 

Benefit/Cost Model, Volume 1: A User’s Manual, 1994 

 FEMA 306, Evaluation of Earthquake Damaged Concrete and 

Masonry Wall Buildings, Basic Procedures Manual, 1999 

 FEMA 307, Evaluation of Earthquake Damaged Concrete and 

Masonry Wall Buildings, Technical Resources, 1999 

In Brief 

This appendix: 

 Lists other relevant 

documents from the 

FEMA Existing 

Buildings Program 

 Lists relevant 

documents from other 

sources 
C-2

Engineering Guideline for Incremental Seismic Rehabilitation 

 FEMA 308, Repair of Earthquake Damaged Concrete and 

Masonry Wall Buildings, 1999 

 FEMA 351, Recommended Seismic Evaluation and Upgrade 

Criteria for Existing Welded Steel Moment-Frame Buildings,

2000 

 FEMA 389, Primer for Design Professionals, Communicating with 

Owners and Managers of New Buildings on Earthquake Risk, 

2004 

 FEMA 412, Installing Seismic Restraints for Mechanical 

Equipment, 2002 

 FEMA 413, Installing Seismic Restraints for Electrical Equipment, 

2002 

 FEMA 414, Installing Seismic Restraints for Duct and Pipe, 2002 

 FEMA 547, Techniques for the Seismic Rehabilitation of Existing 

Buildings, 2006 

C.2 Other Existing Building Resource Documents 

Additional existing building resource documents from other sources 

include: 

 ASTM International, ASTM E2026-07, Standard Guide for 

Seismic Risk Assessment of Buildings (ASTM, 2007a) 

 ASTM International, ASTM E2557-07, Standard Practice for 

Probable Maximum Loss (PML) Evaluations for Earthquake DueDiligence Assessments (ASTM, 2007b) 

 Applied Technology Council, ATC-40, Seismic Evaluation and 

Retrofit of Concrete Buildings (ATC, 1996) 

 Structural Engineers Association of Northern California/ 

International Conference of Building Officials, Guidelines for 

Seismic Evaluation and Rehabilitation of Tilt-up Buildings and 

Other Rigid Wall/Flexible Diaphragm Structures (SEAONC/ICBO, 

2001) 
 R-1 

 References 

References 

ASCE, 2006a, Minimum Design Loads for Buildings and Other Structures, 

ASCE/SEI 7-05, American Society of Civil Engineers, Reston, Virginia. 

ASCE, 2006b, Seismic Rehabilitation of Existing Buildings, ASCE/SEI 

41-06, American Society of Civil Engineers, Reston, Virginia. 

ASCE, 2003, Seismic Evaluation of Existing Buildings, ASCE/SEI 31-03, 

American Society of Civil Engineers, Reston, Virginia. 

ASTM, 2007a, Standard Guide for Seismic Risk Assessment of Buildings, 

ASTM E2026-07, ASTM International, West Conshohocken, 

Pennsylvania. 

ASTM, 2007b, Standard Practice for Probable Maximum Loss (PML) 

Evaluations for Earthquake Due-Diligence Assessments, ASTM 

E2557-07, ASTM International, West Conshohocken, Pennsylvania. 

ATC, 2009, User Guide, ROVER Rapid Observation of Vulnerability and 

Estimation of Risk, prepared by Instrumental Software Technologies, 

Inc. and the Applied Technology Council for the Federal Emergency 

Management Agency, Redwood City, California 

ATC, 2008, Workshop Proceedings, NEHRP Workshop on Meeting the 

Challenges of Existing Buildings – Volume 1, ATC-71 Report, prepared 

by the Applied Technology Council for the Federal Emergency 

Management Agency, Redwood City, California 

ATC, 2003, Proceedings of FEMA-Sponsored Workshop on PerformanceBased Seismic Design, ATC-58-3 Report, Applied Technology Council, 

Redwood City, California 

ATC, 1996, Seismic Evaluation and Retrofit of Concrete Buildings, ATC-40 

Report, prepared by the Applied Technology Council for the California 

Seismic Safety Commission, Redwood City, California. 

ATC, 1987, Evaluating the Seismic Resistance of Existing Buildings, 

ATC-14 Report, Applied Technology Council, Redwood City, California. 
R-2

Engineering Guideline for Incremental Seismic Rehabilitation 

BOCA, 1999, National Building Code, Building Officials and Code 

Administrators International, Inc., Country Club Hills, Illinois. 

City of Los Angeles, 1981, “Earthquake Hazards Reduction in Existing 

Buildings,” Los Angeles Municipal Code, Division 88, City of Los 

Angeles, Building and Safety Department, Los Angeles, California. 

FEMA 154, 2002, Rapid Visual Screening of Buildings for Potential Seismic 

Hazards: A Handbook, Second Edition, prepared by the Applied 

Technology Council for the Federal Emergency Management Agency, 

Washington, D.C. 

FEMA 227, 1992, A Benefit-Cost Model for the Seismic Rehabilitation of 

Buildings, Volume 1: A User’s Manual, Federal Emergency 

Management Agency, Washington, D.C. 

FEMA 255, Seismic Rehabilitation of Federal Buildings: a Benefit/Cost 

Model, Volume 1: A User’s Manual, Federal Emergency Management 

Agency, Washington, D.C. 

FEMA 273, 1997, NEHRP Guidelines for the Seismic Rehabilitation of 

Buildings, prepared by the Applied Technology Council and the Building 

Seismic Safety Council for the Federal Emergency Management 

Agency, Washington, D.C. 

FEMA 356, 2000, Prestandard and Commentary for the Seismic 

Rehabilitation of Buildings, prepared by the American Society of Civil 

Engineers for the Federal Emergency Management Agency, 

Washington, D.C. 

FEMA 395, 2003, Incremental Seismic Rehabilitation of School Buildings 

(K-12), Federal Emergency Management Agency, Washington, D.C. 

FEMA 396, 2003, Incremental Seismic Rehabilitation of Hospital Buildings, 

Federal Emergency Management Agency, Washington, D.C. 

FEMA 397, 2003, Incremental Seismic Rehabilitation of Office Buildings, 

Federal Emergency Management Agency, Washington, D.C. 

FEMA 398, 2004, Incremental Seismic Rehabilitation of Multifamily 

Apartment Buildings, Federal Emergency Management Agency, 

Washington, D.C. 

FEMA 399, 2004, Incremental Seismic Rehabilitation of Retail Buildings, 

Federal Emergency Management Agency, Washington, D.C. 

FEMA 400, 2004, Incremental Seismic Rehabilitation of Hotel and Motel 

Buildings, Federal Emergency Management Agency, Washington, D.C. 

ICBO, 1997, Uniform Building Code, International Conference of Building 

Officials, Whittier, California. 

ICC, 2006a, International Building Code, International Code Council, 

Washington, D.C. 

ICC, 2006b, International Existing Building Code, International Code 

Council, Washington, D.C. 

SBCCI, 1999, Standard Building Code, Southern Building Code Congress 

International, Birmingham, Alabama. 

SEAONC/ICBO, 2001, Guidelines for Seismic Evaluation and Rehabilitation 

of Tilt-up Buildings and Other Rigid Wall/Flexible Diaphragm 

Structures, Structural Engineers Association of Northern 
 R-3 

 References 

California/International Conference of Building Officials, San Francisco, 

California. 

SEAOC, 1995, Performance-Based Seismic Engineering of Buildings, Vision 

2000 Report, Structural Engineers Association of California, 

Sacramento, California.