Federal Emergency Management Agency FEMA 354/November 2000

A Policy Guide to

Steel Moment Frame

Construction
DISCLAIMER

This document provides information on the seismic performance of steel moment-frame structures and the

results and recommendations of an intensive research and development program that culminated in a series

of engineering and construction criteria documents. It updates and replaces an earlier publication with the

same title and is primarily intended to provide building owners, regulators, and policy makers with summary

level information on the earthquake risk associated with steel moment-frame buildings, and measures that

are available to address this risk. No warranty is offered with regard to the recommendations

contained herein, either by the Federal Emergency Management Agency, the SAC Joint Venture, the

individual Joint Venture partners, or their directors, members or employees or consultants. These

organizations and their employees do not assume any legal liability or responsibility for the

accuracy, completeness, or usefulness of any of the information, products or processes included in

this publication. The reader is cautioned to review carefully the material presented herein and

exercise independent judgment as to its suitability for specific applications. This publication has been

prepared by the SAC Joint Venture with funding provided by the Federal Emergency Management Agency,

under contract number EMW-95-C-4770.

Cover Art. The background photograph on the cover of this guide for Policy Makers is a cityscape of a

portion of the financial district of the City of San Francisco. Each of the tall buildings visible in this

cityscape is a steel moment-frame building. Similar populations of these buildings exist in most other

American cities and many thousands of smaller steel moment-frame buildings are present around the

United States as well. Until the 1994 Northridge earthquake, many engineers regarded these buildings as

highly resistant to earthquake damage. The discovery of unanticipated fracturing of the steel framing

following the 1994 Northridge earthquake shattered this belief and called to question the safety of these

structures.
A Policy Guide to

Steel Moment-frame Construction

SAC Joint Venture

a partnership of:

Structural Engineers Association of California (SEAOC)

Applied Technology Council (ATC)

California Universities for Research in Earthquake Engineering (CUREe)

Prepared for SAC Joint Venture by

Ronald O. Hamburger

Project Oversight Committee

William J. Hall, Chair

Shirin Ader

John M. Barsom

Roger Ferch

Theodore V. Galambos

John Gross

James R. Harris

Richard Holguin

Nestor Iwankiw

Roy G. Johnston

Len Joseph

Duane K. Miller

John Theiss

 John H. Wiggins

SAC Project Management Committee

SEAOC: William T. Holmes

ATC: Christoper Rojahn

CUREe: Robin Shepherd

Program Manager: Stephen A. Mahin

Project Director for Topical Investigations:

 James O. Malley

Project Director for Product Development:

 Ronald O. Hamburger

SAC Joint Venture

Structural Engineers Association of California

www.seaoc.org

Applied Technology Council

www.atcouncil.org

California Universities for Research in Earthquake Engineering

www.curee.edu

November, 2000
THE SAC JOINT VENTURE

SAC is a joint venture of the Structural Engineers Association of California (SEAOC), the Applied

Technology Council (ATC), and California Universities for Research in Earthquake Engineering (CUREe),

formed specifically to address both immediate and long-term needs related to solving performance

problems with welded, steel moment-frame connections discovered following the 1994 Northridge

earthquake. SEAOC is a professional organization composed of more than 3,000 practicing structural

engineers in California. The volunteer efforts of SEAOC’s members on various technical committees

have been instrumental in the development of the earthquake design provisions contained in the Uniform

Building Code and the 1997 National Earthquake Hazards Reduction Program (NEHRP) Recommended

Provisions for Seismic Regulations for New Buildings and Other Structures. ATC is a nonprofit

corporation founded to develop structural engineering resources and applications to mitigate the effects of

natural and other hazards on the built environment. Since its inception in the early 1970s, ATC has

developed the technical basis for the current model national seismic design codes for buildings; the defacto national standard for post earthquake safety evaluation of buildings; nationally applicable guidelines

and procedures for the identification, evaluation, and rehabilitation of seismically hazardous buildings; and

other widely used procedures and data to improve structural engineering practice. CUREe is a nonprofit

organization formed to promote and conduct research and educational activities related to earthquake

hazard mitigation. CUREe’s eight institutional members are the California Institute of Technology,

Stanford University, the University of California at Berkeley, the University of California at Davis, the

University of California at Irvine, the University of California at Los Angeles, the University of California at

San Diego, and the University of Southern California. These university earthquake research laboratory,

library, computer and faculty resources are among the most extensive in the United States. The SAC

Joint Venture allows these three organizations to combine their extensive and unique resources,

augmented by consultants and subcontractor universities and organizations from across the nation, into

an integrated team of practitioners and researchers, uniquely qualified to solve problems related to the

seismic performance of steel moment-frame structures.

ACKNOWLEDGEMENTS

Funding for Phases I and II of the SAC Steel Program to Reduce the Earthquake Hazards of Steel

Moment-Frame Structures was principally provided by the Federal Emergency Management Agency, with

ten percent of the Phase I program funded by the State of California, Office of Emergency Services.

Substantial additional support, in the form of donated materials, services, and data has been provided by

a number of individual consulting engineers, inspectors, researchers, fabricators, materials suppliers and

industry groups. Special efforts have been made to maintain a liaison with the engineering profession,

researchers, the steel industry, fabricators, code-writing organizations and model code groups, building

officials, insurance and risk-management groups, and federal and state agencies active in earthquake

hazard mitigation efforts. SAC wishes to acknowledge the support and participation of each of the above

groups, organizations and individuals. In particular, we wish to acknowledge the contributions provided by

the American Institute of Steel Construction, the Lincoln Electric Company, the National Institute of

Standards and Technology, the National Science Foundation, and the Structural Shape Producers

Council. SAC also takes this opportunity to acknowledge the efforts of the project participants – the

managers, investigators, writers, and editorial and production staff – whose work has contributed to the

development of these documents. Finally, SAC extends special acknowledgement to Mr. Michael

Mahoney, FEMA Project Officer, and Dr. Robert Hanson, FEMA Technical Advisor, for their continued

support and contribution to the success of this effort.
1

INTRODUCTION

The Northridge earthquake of January 17, 1994,

caused widespread building damage throughout

some of the most heavily populated communities

of Southern California including the San

Fernando Valley, Santa Monica and West Los

Angeles, resulting in estimated economic losses

exceeding $30 billion. Much of the damage

sustained was quite predictable, occurring in

types of buildings that engineers had previously

identified as having low seismic resistance and

significant risk of damage in earthquakes. This

included older masonry and concrete buildings,

but not steel framed buildings. Surprisingly,

however, a number of modern, welded, steel,

moment-frame buildings also sustained

significant damage. This damage consisted of a

brittle fracturing of the steel frames at the welded

joints between the beams (horizontal framing

members) and columns (vertical framing

members). A few of the most severely damaged

buildings could readily be observed to be out-ofplumb (leaning to one side). However, many of

the damaged buildings exhibited no outward

signs of these fractures, making damage

detection both difficult and costly. Then, exactly

one year later, on January 17, 1995, the city of

Kobe, Japan also experienced a large

earthquake, causing similar unanticipated

damage to steel moment-frame buildings.

Following discovery of hidden damage in

Los Angeles area buildings, the potential for

similar, undiscovered damage in San

Francisco and other communities affected by

past earthquakes was raised.

Ventura Boulevard in the San Fernando

Valley. Many of these buildings had hidden

damage.

Prior to the 1994 Northridge and 1995 Kobe

earthquakes, engineers believed that steel

moment-frames would behave in a ductile

manner, bending under earthquake loading, but

not breaking. As a result, this became one of

the most common types of construction used for

major buildings in areas subject to severe

earthquakes. The discovery of the potential for

fracturing in these frames called to question the

adequacy of the building code provisions dealing

with this type of construction and created a crisis

of confidence around the world. Engineers did

not have clear guidance on how to detect

damage, repair the damage they found, assess

the safety of existing buildings, upgrade

buildings found to be deficient or design new

steel moment-frame structures to perform

adequately in earthquakes. The observed

damage also raised questions as to whether

buildings in cities affected by other past

earthquakes had sustained similar undetected

damage and were now weakened and potentially

hazardous. In fact, some structures in the San

Francisco Bay area have been discovered to

have similar fracture damage most probably

dating to the 1989 Loma Prieta earthquake.

In response to the many concerns raised by

these damage discoveries, the Federal

Emergency Management Agency (FEMA)

sponsored a program of directed investigation

and development to identify the cause of the

damage, quantify the risk inherent in steel

structures and develop practical and effective
2

engineering criteria for mitigation of this risk.

FEMA contracted with the SAC Joint Venture, a

partnership of the Structural Engineers

Association of California (SEAOC), a

professional association with more than 3,000

members; the Applied Technology Council

(ATC), a non-profit foundation dedicated to the

translation of structural engineering research into

state-of-art practice guidelines; and the

California Universities for Research in

Earthquake Engineering (CUREe), a consortium

of eight California universities with

comprehensive earthquake engineering

research facilities and personnel. The resulting

FEMA/SAC project was conducted over a period

of 6 years at a cost of $12 million and included

the participation of hundreds of leading

practicing engineers, university researchers,

industry associations, contractors, materials

suppliers, inspectors and building officials from

around the United States. These efforts were

coordinated with parallel efforts conducted by

other agencies, including the National Science

Foundation and National Institute of Standards

and Technology (NIST), and with concurrent

efforts in other nations, including a large

program in Japan. In all, hundreds of tests of

material specimens and large-scale structural

assemblies were conducted, as well as

thousands of computerized analytical

investigations.

As the project progressed, interim guidance

documents were published to provide practicing

engineers and the construction industry with

important information on the lessons learned, as

well as recommendations for investigation,

repair, upgrade, and design of steel momentframe buildings. Many of these

recommendations have already been

incorporated into recent building codes. This

project culminated with the publication of four

engineering practice guideline documents.

These four volumes include state-of-the-art

recommendations that should be included in

future building codes, as well as guidelines that

may be applied voluntarily to assess and reduce

the earthquake risk in our communities.

This policy guide has been prepared to provide a

nontechnical summary of the valuable

information contained in the FEMA/SAC

publications, an understanding of the risk

associated with steel moment-frame buildings,

and the practical measures that can be taken to

reduce this risk. It is anticipated that this guide

will be of interest to building owners and tenants,

members of the financial and insurance

industries, and to government planners and the

building regulation community. Program to Reduce the Earthquake Hazards of Steel Moment Frame Structures

FEDERAL EMERGENCY MANAGEMENT AGENCY FEMA 353 / July, 2000

Recommended Seismic 

Design Criteria For

New Steel MomentFrame Buildings

Program to Reduce the Earthquake Hazards of

 Steel Moment Frame Structures

FEDERAL EMERGENCY MANAGEMENT AGENCY FEMA 352 /July, 2000

Recommended Seismic 

Design Criteria For

New Steel MomentFrame Buildings

Program to Reduce the Earthquake Hazards of

 Steel Moment Frame Structures

FEDERAL EMERGENCY MANAGEMENT AGENCY FEMA 351 /July, 2000

Recommended Seismic 

Design Criteria For

New Steel MomentFrame Buildings

Program to Reduce the Earthquake Hazards of

 Steel Moment Frame Structures

FEDERAL EMERGENCY MANAGEMENT AGENCY FEMA 350 / July, 2000

Recommended Seismic 

Design Criteria For

New Steel MomentFrame Buildings

FEMA 350 Recommended Seismic Design

Criteria for New Steel Moment-Frame

Buildings

FEMA 351 Recommended Seismic Evaluation

and Upgrade Criteria for Existing Welded

Steel Moment-Frame Buildings

FEMA 352 Recommended Post-earthquake

Evaluation and Repair Criteria for Welded

Steel Moment-Frame Buildings

FEMA 353 Recommended Specifications and

Quality Assurance Guidelines for Steel

Moment-Frame Construction for Seismic

Applications
3

AN OVERVIEW OF THE PROBLEM

What is a steel moment-frame building?

All steel-framed buildings derive basic structural

support for the building weight from a skeleton

(or frame) composed of horizontal steel beams

and vertical steel columns. In addition to being

able to support vertical loads, including the

weight of the building itself and the contents,

structures must also be able to resist lateral

(horizontal) forces produced by wind and

earthquakes. In some steel frame structures,

this lateral resistance is derived from the

presence of diagonal braces or masonry or

concrete walls. In steel moment-frame

buildings, the ends of the beams are rigidly

joined to the columns so that the buildings can

resist lateral wind and earthquake forces without

the assistance of additional braces or walls.

This style of construction is very popular for

many building occupancies, because the

absence of diagonal braces and structural walls

allows complete freedom for interior space

layout and aesthetic exterior expression.

Columns

Beams

Beam/

Column

Connection

Vertical

Force

Lateral 

Force

A steel moment-frame is an assembly of

beams and columns, rigidly joined together

to resist both vertical and lateral forces.

Construction of a modern steel frame

building in which the ends of beams are

rigidly joined to columns by welded

connections.

Are all steel moment-frame buildings

vulnerable to the type of damage that

occurred in the Northridge earthquake?

The steel moment-frame buildings damaged in

the 1994 Northridge earthquake are a special

type, known as welded steel moment-frames

(WSMF). This is because the beams and

columns in these structures are connected with

welded joints. WSMF construction first became

popular in the 1960s. In earlier buildings, the

connections between the beams and columns

were either bolted or riveted. While these older

buildings also may be vulnerable to earthquake

damage, they did not experience the type of

connection fractures discovered following the

Northridge earthquake. Generally, welded steel

moment-frame buildings constructed in the

period 1964-1994 should be considered

vulnerable to this damage. Buildings

constructed after 1994 and incorporating

connection design and fabrication practices

recommended by the FEMA/SAC program are

anticipated to have significantly less vulnerability.
4

What does the damage consist of?

The damage discovered in WSMF buildings

consists of a fracturing, or cracking, of the

welded connections between the beams and

columns that form the frame, or skeleton, of the

structure. This damage occurs most commonly

at the welded joint between a column and the

bottom flange of a beam. Once a crack has

started, it can continue in any of several different

patterns and in some cases has been found to

completely sever beams or columns.

Steel backing 

Column flange

Beam bottom flange

Weld

Fracture

Column flange

Beam bottom 

flange

Damage consists of fractures or cracks that

initiate in the welded joints of the beams to

columns.

Damage ranges from small cracks that are

difficult to see, to much larger cracks. Here,

a crack began at the weld and progressed

into the column flange, withdrawing a divot

of material.

What does the damage look like?

There are several common types of damage,

each of which looks somewhat different. The

most common cracks initiate in the weld itself or

just next to the weld. These cracks often are

very thin and difficult to see. In a few cases,

cracks cannot be seen at all. In some cases,

cracks cause large scoop-like pieces of the

column flange, called divots, to be pulled out. In

still other cases, the cracks run across the entire

column, practically dividing it into two

unconnected pieces.

What is the effect of the damage?

WSMF buildings rely on the connections

between their beams and columns to resist wind

and earthquake loads. When the welded joints

that form these connections break, the building

loses some of the strength and stiffness it needs

to resist these loads. The magnitude and

significance of this capacity loss depends on the

unique design and construction attributes of

each building, as well as the extent and type of

damage sustained. Few buildings were

damaged so severely in the Northridge

earthquake that they represented imminent

collapse hazards. However, significant

weakening of some buildings did occur. Once

the welded joints fracture, other types of damage

can also occur including damage to bolted joints.

Damage that results in the complete severing of

beams or columns or their connections poses a

serious problem and could result in the potential

for localized collapse.

Fracturing of welded connections can lead to

damage to the bolted connections that hold

the beams onto the columns, creating

potential for localized collapse.
5

Why did this damage occur?

We now understand that the vulnerability of

WSMF structures is a result of a number of interrelated factors. Early research, conducted in the

1960s and 70s suggested that a particular style

of connection could perform adequately.

Designers then routinely began to specify this

connection in their designs. However, the

particular style of connection tends to

concentrate high stresses at some of the

weakest points in the assembly, and in fact,

some of the early research showed some

potential vulnerability. As the cost of

construction labor increased, relative to the price

of construction materials, engineers adopted

designs that minimized the number of

connections in each building, resulting in larger

members and increased loads on the

connections. At the same time, the industry

adopted a type of welding that could be used to

make these connections more quickly, but

sometimes resulted in welds that were more

susceptible to cracking. Although building codes

required that inspectors ensure the quality of this

welding, the inspection techniques and

procedures used were often not adequate.

Finally, the steel industry found new ways to

economically produce structural steel with higher

strength. Although the steel became stronger,

designers were unaware of this and continued to

specify the same connections. Often, these

connections did not have adequate strength to

match the newer steel material and were

therefore, even more vulnerable. In the end, the

typical connections used in WSMF buildings

were just not adequate to withstand the severe

demands produced by an earthquake.

Fractures commonly initiate at the welded

joint of the beam bottom flange to column.

Beam

Column

Welds

The typical connection used prior to 1994.

Severe stress concentrations inherent in its

configuration were not considered in the

design.

How widespread was this damage?

Although no comprehensive survey of all of the

steel buildings affected by the Northridge

earthquake has been conducted, the City of Los

Angeles did enact an ordinance that required

mandatory inspection of nearly 200 buildings in

areas that experienced the most intense ground

shaking. Initial reports from this mandatory

inspection program erroneously indicated that

nearly every one of these buildings had

experienced damage and in some cases, that

this damage was extensive. It was projected

that perhaps thousands of buildings had been

damaged. It is now known that damage was

much less widespread than originally thought

and that many of the conditions that were

originally identified as damage actually were

imperfections in the original construction work.

Of the nearly 200 buildings that were inspected

under the City of Los Angeles ordinance, it now

appears that only about 1/3 had any actual

earthquake damage and that more than 90% of

the total damage discovered occurred within a

small group of approximately 30 buildings.

Therefore, although this damage was significant,

and does warrant a change in the design and

construction practices prevalent prior to 1994, it

appears that the risk of severe damage to

buildings is relatively slight, except under very

intense ground shaking.
6

Engineers expect steel to be ductile, capable

of extensive bending and deformation

without fracturing, as shown in this test

specimen. The development of cracks in the

steel at relatively low levels of loading was

unexpected.

Why was this damage a surprise?

In its basic form, steel is a very ductile material,

able to undergo extensive deformation and

distortion before breaking. This is the type of

behavior desired for earthquake resistance, so

engineers believed WSMF buildings would be

quite earthquake resistant. Following the 1971

San Fernando earthquake, the 1987 Whittier

Narrows earthquake, and the 1989 Loma Prieta

earthquake, there were few reports of significant

damage to steel buildings, especially as

compared to other types of construction,

confirming this general belief. However,

relatively few WSMF buildings were subjected to

severe ground motion in these events. As the

industry’s confidence in the ability of WSMF

buildings to resist earthquake damage grew,

design practice, material production processes

and construction techniques changed, adding

unexpected vulnerability. The 1994 Northridge

earthquake was the first event in which a large

number of recently constructed WSMF buildings

were subjected to strong ground motion.

Have other earthquakes caused similar

damage?

When damaged WSMF buildings were first

discovered following the Northridge earthquake,

there was speculation that this was a result of

some peculiar characteristic of the earthquake

itself or of local design and construction

practices in the Los Angeles region. It has now

been confirmed that similar damage occurred to

some buildings affected by the 1989 Loma Prieta

earthquake and also the 1992 Landers and Big

Bear earthquakes. In 1995, the Kobe

earthquake resulted in damage to several

hundred steel buildings, and the collapse of 50

older steel buildings. Japanese researchers

have confirmed problems similar to those

experienced in the Northridge earthquake.

Engineering researchers around the world have

recognized this behavior as a common problem

for welded steel moment-frame buildings

designed and constructed using practices

prevalent prior to the Northridge earthquake and

have been working together to find solutions.

Many steel moment-frame buildings were

damaged in the 1995 Kobe earthquake. The

building shown here, lying on its side, is one

of more than 50 older steel buildings that

collapsed.
7

How many WSMF buildings are there?

Thousands of WSMF buildings have been

constructed in all regions of the United States.

One of the factors contributing to the

seriousness of this problem is that WSMF

construction is often used in many of the nation’s

most important facilities, including hospital

buildings, emergency command centers and

other federal, state and local government office

buildings. It is commonly used for commercial

office structures. Most high-rise buildings

constructed in the United States in the last 30

years incorporate this type of construction.

WSMF construction has also frequently been

used for mid-rise and to a lesser extent, low-rise

commercial and institutional construction,

auditoriums and other assembly occupancies,

and has seen limited application in industrial

facilities. It is relatively uncommon in residential

construction, although some high-rise

condominium type buildings are of this

construction type.

Many of the tallest buildings in our major

cities are of WSMF construction.

Are existing WSMF structures safe?

No structure is absolutely safe and, if subjected

to sufficiently large loads, a structure made of

any material will collapse. Building codes in the

United States permit structures to be damaged

by strong earthquakes, but attempt to prevent

collapse for the most severe levels of ground

motion which can be expected at the site. No

WSMF structure in the United States has ever

collapsed as a result of earthquake loading.

However, research conducted as part of the

FEMA/SAC project confirms that WSMF

structures with the style of beam-column

connection typically used prior to the Northridge

earthquake have a higher risk of earthquakeinduced collapse than desired for new buildings.

How does the risk of WSMF structures

compare to other types of buildings?

Many other types of buildings present much

greater risks of collapse than do WSMF

buildings. Based on observations from past

earthquakes, buildings that present greater risks

include buildings of unreinforced masonry

construction, buildings of concrete and masonry

construction that pre-date the mid-1970s,

buildings of precast concrete construction and

even some types of wood frame construction.

However, many WSMF buildings are large and

house many occupants. The earthquake-induced

collapse of one such structure could result in a

very large and unacceptable life loss.

Older concrete frame, tilt-up and masonry buildings are generally more prone to earthquakeinduced collapse than WSMF buildings.
8

AFTER THE NEXT EARTHQUAKE

Can one tell if a WSMF building is

damaged?

Some damaged WSMF buildings permanently

lean to one side after an earthquake and have

severe damage to finishes, providing a clear

indication that the building has sustained

structural damage. However, many WSMF

buildings do not exhibit any obvious signs of

damage. To determine if these buildings are

damaged, it is necessary to conduct an

engineering inspection of the framing and

connections. To conduct these inspections, it is

necessary first to remove building finishes and

fireproofing. These inspections can be disruptive

of occupancy and very expensive, ranging from

a few hundred dollars to more than one

thousand dollars per connection. Large

buildings may have several thousand

connections. The presence of asbestos,

sometimes used in fireproofing in buildings

constructed prior to 1979, substantially increases

the inspection costs.

The most severely damaged buildings will

often lean to one side. However, there may

be no obvious indications of the damage in

some buildings.

Is it safe to occupy a damaged building?

If a building is severely damaged, there is a risk

that aftershocks or subsequent strong winds or

earthquakes may cause partial or total collapse

of the building. The more severe the damage,

the higher this risk. Most buildings damaged by

the Northridge earthquake were judged to be

safe for continued occupancy while repairs were

made. FEMA 352 provides engineering

procedures that can be used by building officials

and engineers to quantify the risk associated

with continued occupancy of damaged buildings.

FEMA 352 also provides recommendations as to

when a building should be deemed unsafe for

further occupancy.

How does an owner know if a building is

safe?

Following an earthquake, building departments

will typically perform rapid inspections of affected

buildings to identify buildings that may be

unsafe. Once such an inspection has been

performed, the building department will typically

post the building with a placard that indicates

whether the building is safe for occupancy.

FEMA 352 provides procedures that building

officials can use to conduct these rapid

inspections. If the building department doesn’t

provide this service, building owners can retain

private engineers or inspection firms for this

purpose.
9

Is the building department inspection

enough?

Rapid inspections conducted by building

departments after an earthquake are intended to

identify those buildings at greatest risk of

endangering the public safety. They are not

adequate to detect all damage a building has

sustained. If a building has experienced strong

ground motion, the building owner should retain

an engineer to conduct more thorough

inspections in accordance with FEMA 352, even

if the building department posts the building as

safe.

After an earthquake, is it necessary to

inspect every WSMF building?

The amount of damage sustained by a building

is closely related to the severity of ground motion

at the building site. Unless a building

experiences strong ground motion, it is unlikely

that it will sustain significant damage. FEMA 352

recommends that all buildings thought to have

experienced ground motion in excess of certain

levels be subjected to detailed inspections to

determine if they sustained significant damage.

Because detailed inspections can be time

consuming and costly, FEMA 352 also

recommends that an initial, rapid investigation be

performed to look for obvious signs of severe

damage that could pose an immediate threat to

life safety.

Is it necessary to inspect every

connection in a building?

The only way to ensure that all damage in a

structure is found is to inspect all of the

connections. However, as previously discussed,

connection inspections are costly and disruptive.

Therefore most owners would prefer not to

inspect every connection, if possible. Because

damage tends to be distributed throughout a

structure, it is possible to inspect a sample of the

total number of connections in a building and

make judgments as to how widespread damage

is likely to be throughout the entire building.

FEMA 352 provides recommendations for

selecting an appropriate sample and drawing

conclusions on the condition of the building,

based on the damage found in the sample.

Program to Reduce the Earthquake Hazards of

 Steel Moment Frame Structures

FEDERAL EMERGENCY MANAGEMENT AGENCY FEMA 352 / July, 2000

Recommended Post-earthquake

Evaluation and Repair Criteria

for Welded Steel Moment-Frame

Buildings

FEMA 352 contains recommended

procedures for identifying earthquake

damage in WSMF buildings and the risk of

continued occupancy.

Is it possible to repair any damaged

building?

It is technically possible to repair almost any

damaged building. However, if a building is

severely damaged, the cost of repair may

exceed the replacement cost. Repair may be

particularly difficult and costly if a building has

experienced large, permanent sideways

displacement, sometimes called drift. In such

cases, the structure may even be unsafe for

occupancy even for repair. In these cases, it

may make more sense to demolish a building

and replace it rather than to repair it. Following

the 1994 Northridge earthquake, the owner of

one building elected to do this.
10

How is the fracture damage repaired?

Each type of fracture requires a somewhat

different repair procedure. FEMA 352 provides

recommendations for many types of repair.

Generally, repairs consist of local removal of the

damaged steel using cutting torches or electric

arcs, and welding new, undamaged material

back in its place. To do this cutting and welding

safely, it is necessary first to remove any

combustible finishes from the work area and

also to provide ventilation to remove potentially

harmful fumes. In some cases, it may be

necessary to provide temporary shoring of the

damaged element while the repair work is done.

These operations are disruptive to normal

occupancy of the immediate work area and also

quite costly. Typical connection repair costs can

range from $10,000 to $20,000. Additional costs

are associated with the temporary loss of use of

floor space during repair operations.

Flange removal and replacement

per Figure 6-6, if required

Weld access holes as required

for weld terminations

FEMA 352 provides detailed repair

procedures for different types of damage.

One repair procedure is shown here as an

example.
11

DEALING WITH THE RISK OF EXISTING BUILDINGS

Is it possible to upgrade an existing

WSMF building?

It is technically feasible to upgrade an existing

steel moment-frame building and improve its

probable performance in future earthquakes.

The most common methods are upgrades of the

individual connections, addition of steel braces,

concrete or masonry walls, or addition of energy

dissipation systems. Each of these approaches

may offer advantages in particular buildings.

Buildings can be upgraded by modifying

connections, adding braces and other

methods.

Connections can be upgraded by welding or

bolting new plates onto the beams and

columns to change the connection shape

and reduce stress concentrations. In some

cases, it may also be appropriate to replace

defective welds and welds with low

toughness with welds with improved

toughness and workmanship.

What is a connection upgrade?

Connection upgrades are the most direct

approach to improving the seismic performance

of an existing steel moment-frame structure. As

previously discussed, existing connections can

fracture because their shape results in the

development of large stress concentrations;

some welds have large defects that reduce their

strength and the weld metal itself may be of low

toughness and unable to resist the large

stresses imposed on it. Connection upgrades

address these problems directly by modifying the

shape of the connection to reduce the stress

concentrations. In addition, depending on the

approach used, the upgrade may include

replacement of defective welds and welds with

low toughness with new welds that have

improved toughness and better workmanship.

FEMA 351 provides information and design

criteria for a number of alternative methods of

upgrading connections.
12

How does the addition of braces or walls

upgrade a building?

Connection fractures occur when the force

delivered by the earthquake exceeds the

connection strength or when connection

elements experience low-cycle fatigue. This is

similar to what happens to a paper clip, when it

is bent back and forth repeatedly. As the metal

is bent back and forth, it dissipates energy, but

also becomes damaged. Eventually, so much

damage occurs that the metal breaks. If a

connection is bent through a large angle of

deformation, or is relatively weak or brittle, it may

only be able to withstand one or two cycles, that

is, be bent back and forth once or twice.

However, if the bending deformation is relatively

small, or if the connection material has high

toughness, the connection may be able to

withstand a number of such cycles.

Earthquakes produce many cycles of motion.

When steel braces or masonry or concrete walls

are added to a building, they stiffen it and reduce

the amount that the building will sway in an

earthquake. This reduces the amount of

bending on the connections. Guidance on the

use of these techniques is already available in

such publications as FEMA-273, NEHRP

Guidelines for Seismic Rehabilitation of Buildings

and, therefore, is not repeated in FEMA 351.

Energy dissipation systems are typically

installed in buildings as part of a vertical

bracing system that extends between the

building’s floors.

Program to Reduce the Earthquake Hazards of

 Steel Moment Frame Structures

FEDERAL EMERGENCY MANAGEMENT AGENCY FEMA 351 / July, 2000

Recommended Seismic 

Evaluation and Upgrade

Criteria for Existing Welded

Steel Moment-Frame 

Buildings

FEMA 351 provides engineering procedures

for evaluating the probable performance of

buildings in future earthquakes. These

procedures address the safety as well as

financial aspects of earthquake performance.

What is an energy dissipation system?

Energy dissipation systems reduce the amount

that buildings sway in an earthquake by

converting the earthquake’s energy into heat.

Several types of energy dissipation devices are

available. One type is a hydraulic cylinder,

similar to the shock absorbers in an automobile.

Other types dissipate energy through friction. In

order for these systems to be effective, one end

of the device must move relative to the other

end. The most common way to do this is to

install the dissipation devices as part of a

bracing system between the building floors. As

the building sways in an earthquake and one

floor moves relative to another, this drives the

device and dissipates the energy as heat.

Detailed guidance on the design of energy

dissipation systems is already available in such

documents as FEMA 273 NEHRP Guidelines for

Seismic Rehabilitation of Buildings and,

therefore, is not covered in detail in the steel

moment-frame criteria documents.
13

What type of upgrade is best?

No one type of upgrade is best for all buildings.

Basic factors that affect selection of an optimal

alternative include the individual building’s

characteristics, the severity of motion anticipated

at the building site, desired building

performance, cost of the upgrade, the feasibility

of performing upgrade work while the building

remains occupied, and the effect of the upgrade

on building appearance and space utilization.

Addition of diagonal bracing may be the least

costly alternative; however, its effect on building

appearance and functionality may be viewed by

some owners as unacceptable. Addition of

energy dissipation devices will result in better

performance of the building, but may cost more.

Modification of individual connections would

have the least effect on building appearance, but

would inconvenience the existing tenants more

than some other approaches and may cost more

to implement.

How does an owner pick an appropriate

upgrade approach?

To determine the best method of upgrading a

building, an owner should retain an engineer to

evaluate the building’s probable earthquake

performance. An upgrade should be considered

if the probable performance is unacceptable. In

the absence of ordinances that require upgrade

of buildings, it will be necessary for each owner

to decide what constitutes acceptable

performance. The engineer can assist the

owner in understanding the various options.

Once a performance objective is selected, the

engineer can prepare preliminary designs for

various upgrade approaches, together with

estimates of probable construction cost. The

owner can then select the most appropriate

design considering the cost, structural

performance improvements, aesthetics and

other impacts of each upgrade approach on the

building.

Should all existing WSMF buildings be

upgraded?

A building should be upgraded only if the risk of

losses associated with its probable performance

in future earthquakes is deemed unacceptable.

Individual owners may make this judgement, or

in some cases, the local community may decide

that risk is unacceptable. The severity of

earthquake risk associated with a building’s

performance in future earthquakes, as well as

the acceptability of this risk, must be determined

on a building-specific basis. The earthquake

performance of some WSMF buildings housing

critical occupancies and located in zones likely to

experience frequent intense ground motion may

be unacceptable, whereas many other WSMF

buildings will be capable of performing

adequately in the levels of ground motion they

are likely to experience. To determine if a

building should be upgraded, an owner should

retain the services of an engineer to evaluate the

building’s probable performance in future

earthquakes, permitting the owner to balance the

assessed risks against the cost of mitigation.

What is the cost of upgrading a WSMF?

Upgrade costs are dependent on a number of

factors including the upgrade approach selected,

the structural configuration of the building, the

specific seismic deficiencies present, the

severity of earthquake motion used as a basis

for design, the intended performance of the

upgraded building, the building’s occupancy, and

the nature of tenant improvements and

furnishings. Costs can range from about $10

per square foot of building floor area to as much

as $30 or more. This can be compared to the

typical costs associated with new building

construction. Exclusive of the costs of land

acquisition, planning and design, the

construction cost of a new steel frame building

shell will range from about $70 to $125 per

square foot. The cost of tenant improvements,

including interior partitions, ceilings, lighting, and

furnishings can equal the building construction

costs.
14

When is the best time to upgrade?

Much of the cost of performing a seismic

upgrade relates to the need to demolish and

restore architectural finishes and to displace

tenants temporarily from construction work

areas. In many commercial buildings these

costs are incurred on a regular, periodic basis as

leases expire and tenants in a building change.

Therefore, the most economical time to perform

an upgrade is during a change of tenant

occupancy. Most buildings have many tenants

with staggered lease periods. If upgrade work is

to be done when tenant space is being changed

from one leaseholder to the next, it will usually

be necessary to phase the work over a period of

years. If such an approach is taken, the

probable performance of the building in the

event that an earthquake occurs while it is only

partially upgraded should be evaluated for each

of the potential stages of completion, to ensure

that an unsafe condition is not created

inadvertently. Another beneficial time to perform

upgrade work is at the time of property transfer.

If upgrade work is done as part of a building

ownership transfer, financing can include

additional funding to perform the upgrade work.

Is upgrading economically feasible?

The feasibility of an upgrade depends on the

individual economic circumstances of each

building, its tenants and owners. Earthquakes

are infrequent events. Even in areas of high

seismic risk, like California, most buildings will

experience at most only one or perhaps two

damaging earthquakes over their lives. Seismic

upgrades can greatly reduce the financial and

life losses that occur as a result of such

earthquakes. However, because the probability

of occurrence of a damaging earthquake is

usually small, the present value of these avoided

losses rarely exceeds the initial cost of the

upgrade unless there are large life loss or

occupancy interruption costs associated with the

potential damage. If upgrades are performed

concurrently with other building renovation work,

such as remodeling or asbestos removal, the

upgrade work will cost less and produce a more

attractive return on the investment.

How can an owner evaluate a building’s

probable future performance?

To determine the probable performance of a

building in future earthquakes, an owner should

retain an engineer. FEMA 351 provides

structural engineers with several methods for

evaluating the probable performance of buildings

in future earthquakes. These methods include

Simplified Loss Estimation, Detailed Loss

Estimation and Detailed Performance

Evaluation, a procedure that is compatible with

modern performance-based design approaches.

How can an owner tell if a building will

be safe in future earthquakes?

FEMA 351 presents engineering procedures that

can be used to estimate the probability that a

building will experience life-threatening damage

in future earthquakes. The ability of a building to

resist earthquakes without endangering life is

dependent on two primary factors, the capacity

of the building and the intensity of future

earthquake ground motion. It must be

remembered that any building has the potential

to experience life-threatening damage, if it

experiences sufficiently intense ground motion.

In typical regions with significant earthquake risk,

earthquakes that produce low levels of ground

motion may be felt relatively frequently, perhaps

one time every ten to twenty years. Such ground

motion rarely causes damage. Intense ground

motion, capable of causing severe damage to

modern buildings, will occur much less

frequently, perhaps only one time in a few

hundred to a few thousand years. The

procedures of FEMA 351 allow determination of

the probability that a building will experience

either partial or total collapse, if earthquake

ground motion of a specified intensity occurs. To

use this method, the owner and engineer must

agree upon an appropriate return period for the

ground motion to be used as a basis for the

evaluation. The return period is the average

number of years, for example, 100, 500, etc.,

between damage-causing earthquakes.
15

What is the Simplified Loss Estimation

Methodology?

The Simplified Loss Estimation Methodology

contained in FEMA 351 consists of a series of

graphs that indicate the probability that WSMF

buildings will experience various levels of

damage if they are subjected to certain levels of

ground motion. These graphs were compiled

from data obtained for buildings in the Los

Angeles area following the 1994 Northridge

earthquake. To use these graphs, an engineer

must estimate an intensity of ground motion to

which a building will be subjected. Using the

graph, an engineer can obtain an estimate of the

percentage of the building’s connections that will

be damaged and the probable cost of connection

repairs, if the building experiences an

earthquake of a certain intensity. These graphs

do not take into account the individual

characteristics of a building, except in an

approximate manner and, therefore, do not

provide precise estimates. Rather, they provide

an indication of the potential range of damage

and repair costs and the probability that damage

and repair costs will exceed certain amounts,

based on the behavior of the buildings that were

affected by the Northridge earthquake.

The Simplified Loss Estimation Methodology

uses a series of graphs to relate probable

earthquake losses to ground motion

intensity.

What is the Detailed Loss Estimation

Methodology?

In addition to the Simplified Loss Estimation

Methodology, FEMA 351 also presents a

procedure for developing building-specific,

damage and loss estimates for WSMF buildings.

This method can be implemented in HAZUS,

FEMA’s nationally applicable loss estimation

model, to explore the potential benefits to a

community of requiring upgrade of steel

buildings. The method can also be used to

develop loss estimates for individual buildings to

assist owners in making upgrade decisions.

Loss estimates generated using this technique

take into consideration the specific

characteristics of individual buildings and,

therefore, provide a more accurate basis for

cost-benefit studies for seismic upgrades.

However, the method is somewhat complex and

requires specialized expertise and training to

implement.

How safe should an existing building

be?

There is no single commonly accepted minimum

level of safety for existing buildings. However, it

is always useful to compare the safety of an

existing building with that intended for new

buildings as well as with that of other existing

buildings. New buildings are designed to provide

a high level of confidence, on the order of 90%,

that they will survive the most severe ground

motion likely to be experienced, every 1,000 to

2,500 years, without collapse. Therefore, it is

unlikely that most new buildings would ever

experience earthquake-induced collapse. Most

existing buildings will not be capable of providing

the same performance as a new building. An

existing building may be acceptably safe if it can

provide high confidence that it will resist collapse

under ground motion intensities likely to occur

every 500 years or so. The selection of an

acceptable level of safety depends on a number

of factors including the number of occupants in

the building, and its use. FEMA 351 presents

evaluation procedures that can be used to

estimate the probability that a building will

collapse in future earthquake ground motion and

to associate a confidence level with this

estimate.
16

Will it be possible to reuse a building

after an earthquake?

In addition to safety concerns, many owners and

tenants in buildings are concerned with their

ability to return to a building after an earthquake,

and continue to live or work in it. FEMA 351

provides an evaluation procedure that may be

used to determine the probability that a building

will experience so much damage that it should

not be reoccupied following an earthquake. To

use this procedure, it is necessary for the owner

and the engineer to select an appropriate return

period for the ground motion upon which this

evaluation will be based and the performance

that will be acceptable if this ground motion

occurs.

Is it cost effective to upgrade?

While earthquakes can cause catastrophic

damage, in most cases the probability that a

building will be affected by such an event is low.

Even in the most seismically active regions of

California, ground motions likely to cause

substantial damage to WSMF buildings are

currently projected to affect a building site only

one time every hundred years or so. Given that

many investors retain ownership in a building

asset for a relatively small number of years, the

likelihood that a loss will actually occur during an

ownership period is low. Therefore, when

owners balance the cost of a seismic upgrade

program against the probable economic benefit

to be gained during their ownership period, a

good return on investment is often found to exist

only if post-earthquake occupancy of a building

is perceived to be critical for economic or other

reasons, or if life loss is anticipated and the

economic value of such loss is included in the

evaluation.

Why is building performance expressed

in probabilities?

The amount of damage that a building will

sustain in an earthquake depends on a number

of factors including the configuration and

strength of the building, the quality of its

construction, and the specific characteristics of

the ground motion produced by the earthquake.

Although engineers can develop estimates of

each of these factors, it is not possible to predict

any of these things precisely. Therefore,

engineers must express future building

performance in probabilistic terms.

Should communities adopt mandatory

upgrade programs for steel frame

buildings?

Given the low benefit/cost ratio for seismic

upgrade of steel frame buildings, it is unlikely

that many owners will perform such upgrades

voluntarily. Mandatory upgrade ordinances can

be an effective measure to assure that these

buildings are upgraded. For example, a number

of California cities, including Los Angeles and

San Francisco, have successfully implemented

ordinances requiring upgrade of unreinforced

masonry buildings, a type of building that can

collapse in even moderate earthquakes.

However, similar ordinances requiring upgrade

of WSMF buildings may not be an effective

application of the limited resources available to a

community. It is likely that other financial and

health risks faced by the community are more

significant than the hazards posed by the

earthquake performance of steel frame

buildings. Indeed, many communities have large

inventories of buildings that are far more

hazardous than typical steel frame buildings,

including unreinforced masonry buildings and

older concrete buildings. Before adopting a

mandatory upgrade ordinance for steel frame

buildings, communities should carefully consider

the costs and benefits on a community-wide

basis and weigh these against other potential

applications of the limited resources available.

FEMA’s HAZUS loss estimation model is

available to communities and can be used to

provide guidance in deciding on the advisability

of adopting a mandatory upgrade ordinance.
17

CRITERIA FOR NEW BUILDING DESIGN

How should new buildings be designed?

Buildings must be designed to meet minimum

criteria specified in building codes. Model

building codes are developed on a national basis

by professional organizations representing

engineers, architects, building officials and fire

marshals, and are adopted, sometimes with

modification, by individual cities, counties and

states. Prior to the 1994 Northridge earthquake,

the building codes contained prescriptive

requirements for the design and construction of

steel moment-frame buildings. These

requirements included specification of minimum

permissible strength and stiffness for resisting

earthquake loading, and specific requirements

for connections between beams and columns.

The Northridge earthquake demonstrated that

some of these prescriptive requirements were

not adequate. Following that discovery, the

prescriptive requirements were removed from

building codes used in regions of high

earthquake risk and replaced with a requirement

that designs include test data to show that

reliable performance could be achieved for each

new building. These new requirements were

both costly and difficult to enforce and resulted in

a decrease in the number of steel momentframe buildings constructed.

Studies conducted under the FEMA/SAC

program to reduce earthquake hazards in

welded moment-resisting steel frames confirm

that some of the design requirements contained

in the building codes prior to the Northridge

earthquake were inadequate. In the time since,

some of these inadequate requirements have

been improved based on interim findings and

recommendations of the FEMA/SAC program.

Now that the program is complete, FEMA 350

presents a series of additional criteria for the

design and construction of steel moment-frame

buildings that should make performance of these

structures in future earthquakes much more

reliable. It is recommended that the building

codes adopt these new recommendations and

that, until this occurs, engineers and owners

voluntarily adopt these criteria when developing

new buildings.

What types of changes to design and

construction practice does FEMA 350

recommend?

The FEMA 350 recommendations affect nearly

all phases of the design and construction

process. The recommendations address the

types of steel used, the way in which columns

and beams are connected, the way the steel is

fabricated, the type of welding that is performed,

and the techniques that are used to assure that

the construction work is performed properly.

In addition, FEMA 350 provides engineers with a

series of performance-based design criteria that

can be used to design and construct buildings to

resist earthquakes reliably while sustaining less

damage than anticipated by building codes. Program to Reduce the Earthquake Hazards of Steel Moment Frame Structures

FEDERAL EMERGENCY MANAGEMENT AGENCY FEMA 350 / July, 2000

Recommended Seismic 

Design Criteria For

New Steel MomentFrame Buildings

FEMA 350 provides recommendations for

design and construction of new steel

moment-frame buildings. These

recommendations affect the materials of

construction, design and construction

procedures, and methods of quality

assurance.
18

What are the recommended changes to

the types of structural steel that should

be used?

In the last few years, the steel industry in the

United States has undergone rapid change with

old rolling mills phased out and new mills, using

more modern technologies, coming on line.

Although the chemical composition and physical

properties of steel have changed rapidly during

this period, industry standard specifications and

design practice largely neglected this. Working

with the FEMA/SAC project, the American

Institute of Steel Construction (AISC) developed

new industry standard specifications for

structural steel material. These new

specifications provide better control of the critical

properties that are important to earthquake

performance. FEMA 350 recommends the use

of these more modern steels and also

recommends design procedures that properly

account for the high strength of modern steel

materials.

Methods of steel production have undergone

dramatic change in recent years and industry

standard design and material production

specifications did not adequately reflect the

material currently produced. FEMA 350

updates the code requirements to assure

specification of proper materials and proper

treatment in design.

If inadequately constructed, welded joints in

moment-frames can be weak links that fail

prematurely. FEMA 350 recommends careful

control of the materials, workmanship and

procedures used to make these joints and

verify their adequacy.

Are there any changes to welding

requirements?

FEMA 350 and its companion document, FEMA

353, present extensive new recommendations

for welding of moment-resisting connections in

frames designed for seismic applications. The

new recommendations address the types of

materials that may be used for this work, the

welding processes and procedures that should

be followed, the environmental conditions under

which welding should be performed, and the

level of training and workmanship required of

welders and inspectors engaged in this work. In

addition, FEMA 353 provides detailed

recommendations for quality control, quality

assurance and inspection procedures that

should be put into place to assure that this

critical work is properly performed. These new

recommendations affect all segments of the

design and construction process and require

designers, producers, fabricators, welding

electrode manufacturers, welders and

inspectors, among others, to adopt new

practices. These recommendations have been

submitted to the American Welding Society for

incorporation into the structural welding code.
19

What is different about the new design

procedures?

Prior to the Northridge earthquake, most steel

moment-frame designs used a standard

connection that was prescribed by the building

code. We know now that the configuration of

these connections was problematic and resulted

in unreliable connection performance. Following

this discovery, the building codes were changed

to require testing of each new connection

design. This was very costly and difficult to

implement. FEMA 350 presents a series of new

connection configurations that are

recommended as prequalified for use in

moment-frames conforming to certain

limitations. The use of these prequalified

connections will greatly simplify the design

process and make the construction of new

moment-frame buildings more economical and

more reliable.

1

2

3

General:

Applicable systems OMF, SMF

Hinge location distance sh dc/2

Critical Beam Parameters:

Depth Up to W36 (OMF)

Up to W30 (SMF)

Minimum Span OMF: 15 ft.

SMF: 20 ft.

bf/2tf of flange 52√Fy ; 35√Fy recommended minimum

Flange thickness Up to 1-1/4” (OMF)

Up to 3⁄4” (SMF)

Permissible Material Specifications A36, A572 Grade 50, A992

Critical Column Parameters:

Depth Not Limited

Permissible Material Specifications A572, Grade 50; A913 Grade 50

Minor Axis Connection PrequalifiedOMF: Yes

SMF: No

Beam/Column Relations:

PZ strength Section 3.3.3.2 for SMF; Cpr=1.2; Rv/Ru < 1.2 (recommended)

Column/beam bending strength Section 2.8.1; Cpr=1.2

Connection Details

Web connection Section 3.5.3.2. Welding QC Level 2.

Continuity plate thickness Section 3.3.3.1

Flange welds Section 3.5.3.1: Welding QC Level 1.

Weld electrodes CVN 20 ft-lbs at -20oF and 40 ft-lbs at 70oF

Weld access holes Not Applicable

FEMA 350 provides prescriptive criteria for

prequalified beam-to-column connections

capable of reliable performance.

The Reduced Beam Section, or “dog bone”

connection is one of 12 different types of

prequalified connections that engineers can

specify without project-specific testing.

How many different types of

connections are prequalified?

FEMA 350 contains design criteria for twelve

different types of prequalified, welded and bolted

beam-to-column connections. Each

prequalification includes specification of the

limiting conditions under which the connection

design is valid, the materials that may be used,

and the specific design and fabrication

requirements.

What is the basis for the new

prequalified connections?

The new prequalified connections contained in

FEMA 350 are based on extensive laboratory

and analytical investigations including more than

120 full-scale tests of beam-to-column

connection assemblies and numerous analytical

studies of the behavior of different connection

types. Connections were prequalified only after

their behavior was understood, analytical models

were developed that could predict this behavior

and laboratory testing demonstrated that the

connections would behave reliably.
20

What is the best type of connection to

use?

Each of the prequalified connections offers

certain advantages with regard to design

considerations, fabrication and erection

complexity, construction cost, and structural

performance capability. No one connection type

will be most appropriate for all applications. It is

likely that individual engineers and fabricators

will develop preferences for the use of specific

types of connections, and that certain

connections will see widespread use in some

parts of the country but not others.

Do the prequalified connections cover

all possible design cases?

The prequalifed connections should be

applicable to many common design conditions.

However, they are not universally applicable to

all structures and, in particular, are limited in

applicability with regard to the size, types and

orientation of framing members with which they

can be used. If a design requires the use of

types or sizes of framing that are not included in

the ranges for a prequalified connection, FEMA

350 recommends that supplemental testing of

the connection be performed to demonstrate that

it will be capable of performing adequately.

Is it possible to use types of

connections other than those that are

prequalified?

FEMA 350 contains information on several types

of proprietary connections that are not

prequalified and nothing in FEMA 350 prevents

engineers from developing or using other types

of connection designs. However, FEMA 350

does state that, when other types of connections

are used, a testing program should be

conducted to demonstrate that these

connections can perform adequately. FEMA 350

also presents information on the types of testing

that should be conducted and how to determine

if connection performance is acceptable.

Will designs employing these new

recommendations cost more?

The cost of a steel frame building is generally

dependent on the amount of labor required to

fabricate and erect the steel and the total

number of tons of steel in the building frame.

The new design recommendations both

formalize and simplify design procedures that

generally have been in use by engineers since

the 1994 Northridge earthquake. They do not

result in an increase in steel tonnage or

significantly greater labor for fabrication and

erection. However, more extensive construction

quality assurance measures are recommended

and these will result in some additional

construction cost. It is anticipated that this

additional cost will amount to less than 1% of the

total construction cost for typical buildings.

Will buildings designed to the new

recommendations be earthquake proof?

It is theoretically possible to design and construct

buildings that are strong enough to resist severe

earthquakes without damage, but it would not be

economical to do so and we could not afford to

construct many such buildings. The objective of

most building codes is to design buildings such

that they might be damaged by severe

earthquakes but not collapse and endanger

occupants in any earthquake they are likely to

experience. The FEMA 350 recommendations

adopt this same design philosophy. It is

anticipated that there would be a very low risk of

life threatening damage in buildings designed

and constructed in accordance with the FEMA

350 recommendations. However, they may

experience damage that will require repair,

including permanent bending and yielding of the

framing elements and possible permanent lateral

drift of the structure. Although it is possible that

some connections designed using the new

procedure may fracture, it is anticipated that this

will not be widespread.
21

Will the new recommendations be

included in the building codes?

The seismic provisions of current building codes

are largely based on the NEHRP Recommended

Provisions for Seismic Regulations of Buildings

and Other Structures, supplemented by standard

specifications developed by industry

associations, including the American Institute of

Steel Construction (AISC) and the American

Welding Society (AWS). Many of the design

recommendations contained in FEMA 350 have

already been incorporated into the standard

design specifications developed by AISC and are

directly referenced by the 2000 International

Building Code. The remaining

recommendations are being proposed for

incorporation into later editions of the AISC and

AWS specifications. This material is also being

included in the NEHRP Recommended

Provisions for Seismic Regulations of New

Buildings and Other Structures. Some of the

earlier material has already been included in the

1997 edition (FEMA 302/303) and the remainder

of the material will be incorporated into the new

2000 edition (FEMA 368/369), due to be

released in spring 2001. It is anticipated that

many jurisdictions around the United States will

adopt building codes based on these criteria as

the basis for building regulation in their

communities.

Is it possible to design to the new

recommendations before the new

building codes are adopted?

Many of the new design recommendations are

compatible with existing building code

regulations that are already in force around the

United States. It should be possible for

engineers to utilize the new recommendations,

on a voluntary basis, as a supplement to the

existing building code requirements. However,

the local building official is the ultimate authority

as to the acceptability of this practice. Engineers

should verify that the building official will accept

the new documents prior to using them to design

buildings.

Is it possible to design for better

performance?

As an option, FEMA 350 includes a methodology

which engineers can use to design for superior

performance relative to that anticipated by the

building code. This approach is similar to the

procedures contained in FEMA 351 for the

evaluation and upgrade of existing buildings. In

these procedures, a decision must be made as

to what level of performance is desired for a

specific level of earthquake motion. As an

example, one of the available performance

levels, termed Immediate Occupancy, results in

such slight damage that the building should be

available for occupancy immediately following

the earthquake. The performance-based

procedures of FEMA 350 can be used to design

a building such that there is a high probability the

building will provide Immediate Occupancy

performance for any level of earthquake intensity

that is desired. As a minimum, however,

buildings should be designed to satisfy the

prescriptive criteria of the applicable building

code, which are intended to protect life safety.
22

CONSTRUCTION QUALITY CONTROL AND ASSURANCE

What is construction quality control?

Construction quality control includes that set of

actions taken by the contractor to ensure that

construction conforms to the specified material

and workmanship standards, the requirements

of the design drawings and the applicable

building code. Construction quality control

includes hiring workers and subcontractors that

have the necessary training and experience to

perform the construction properly; making sure

that these workers understand the project

requirements and their responsibility to execute

them; and performing routine inspections and

tests to confirm that the work is properly

performed. Some contractors may retain

independent inspection and testing agencies to

assist them with their quality control functions.

What is construction quality assurance?

Construction quality assurance is that set of

actions, including inspections, observations and

tests, that are performed on the owner’s behalf

to ensure that the contractor is conforming to the

design and building code requirements. In

essence, construction quality assurance

represents a second line of defense and

supplements the contractor’s own quality control

program. Building codes specify minimum levels

of quality assurance for different types of

construction. If the contractor on a project does

not perform adequate quality control it may be

appropriate to provide more quality assurance

than required by the applicable building code.

Quality assurance tasks are typically performed

by design professionals and special inspection

and testing agencies specifically retained by the

owner for this purpose. It is recommended that

the engineer assist the owner in determining the

level of quality assurance appropriate to a

specific project, and also that the engineer be

retained by the owner to actively monitor and

participate in the quality assurance process.

Why is construction quality control and

quality assurance important?

Investigations performed after every earthquake

indicate that much of the damage that occurs is

a result of structures not being constructed in

accordance with the applicable building code or

the designer’s intent. This problem has affected

nearly every type of building construction,

including wood frame, masonry, concrete and

steel buildings. Construction errors and

construction work that is improperly performed

create weak links where damage in structures

can initiate. Earthquakes can place extreme

loading on structures and, if structures contain

improper construction, damage is likely to occur

where that poor construction occurs.

Was inadequate construction quality a

significant factor in the damage

sustained by steel buildings in the

Northridge earthquake?

One of the contributors to the damage sustained

by steel moment-frame buildings in the

Northridge earthquake was construction that did

not conform to the applicable standards. In

particular, investigations conducted after the

earthquake revealed that critical welds of beams

to columns were not made in accordance with

the building code requirements. A number of

defects were commonly found in the construction

including: welds that had large slag inclusions

and lack of fusion (bonding) with the steel

columns, welds that were placed too quickly and

with too much heat input into the joint; and

welding aids including backing and weld tabs

that were improperly installed. These

construction defects resulted in welded joints

that had lower strength and toughness than

should have been provided, resulting in a

propensity for damage.
23

Who is responsible for construction

quality control and assurance?

Each of the participants in building construction,

including the design engineer, the contractor, the

building official, and special inspectors, plays a

critical role in assuring that construction meets

the appropriate standards. The engineer must

specify the applicable standards and the quality

assurance measures that are to be used. The

contractor must perform the work in the required

manner and perform inspections to verify that

this occurs. Building codes require that the

owner retain a special inspection agency to

perform detailed inspections and assure that the

contractor is executing the work properly. The

responsible building official typically monitors the

entire process and makes sure that each of the

parties fulfills their individual responsibilities. Program to Reduce the Earthquake Hazards of Steel Moment Frame Structures

FEDERAL EMERGENCY MANAGEMENT AGENCY FEMA 353 / July, 2000

Recommended Specifications

and Quality Assurance 

Guidelines for Steel 

Moment-Frame Construction

for Seismic Applications

FEMA 353 provides recommended

specifications for fabrication, erection, and

quality assurance of steel moment-frame

structures designed for seismic applications.

Where can one find recommendations

on appropriate quality control and

quality assurance procedures?

FEMA 353 provides detailed recommendations

for procedures that should be followed to assure

that steel moment-frame construction complies

with the applicable standards. It includes

information that is useful to engineers, building

officials, contractors and inspectors. This

information is presented in the form of

specifications that can be included in the project

specifications developed by engineers for

specific projects. It also includes commentary

that explains the basis for the recommendations

and methods that can be used to implement

them.

Are the new quality recommendations

significantly different than those

required in the past?

Many of the recommendations contained in

FEMA 353 are a restatement and clarification of

requirements already contained in building codes

and in the standard AISC and AWS

specifications. There are also some important

new recommendations. These include new

requirements intended to assure that weld filler

metals and welding procedures are capable of

providing welded joints of adequate strength and

toughness. In addition, comprehensive

recommendations are provided as to the extent

of testing and inspection that should be

performed on different welded joints. In part,

these new requirements are based on findings

that the inspection methods traditionally used in

the past to assure weld quality are incapable of

reliably detecting nonconforming construction. It

is anticipated that many of these new

requirements will be incorporated into the AWS

standards in the future.
24

PREPARING FOR THE NEXT EARTHQUAKE

What should communities do before the

next disaster occurs?

Before the next disaster strikes, communities

should conduct a thorough examination of their

vulnerability to natural hazards and the risks they

may present to their citizens. In addition to a

potential earthquake threat, communities may be

vulnerable to other significant hazards, such as

flooding, high winds, hurricanes, tornadoes,

tsunami, etc. While this publication addresses

the potential earthquake risk of steel momentframe buildings, communities may have more

significant risks from other more hazardous

types of buildings, such as unreinforced

masonry, non-ductile concrete frame or tilt-up

concrete buildings. Communities should carefully

consider all of these potential risks and how they

may affect the different types of construction

present.

Regardless of the risk posed by existing

construction, before the next disaster occurs

communities should adopt reliable building

codes and building regulation practices that will

ensure that new buildings are adequately

designed and constructed to resist the future

earthquakes and other disasters that will

inevitably occur. Building codes that incorporate

the latest edition of the NEHRP Recommended

Provisions for Seismic Regulation for Buildings

and Other Structures are strongly

recommended.

Communities may wish to encourage building

owners to upgrade their existing hazardous

buildings to minimize potential damage,

economic and life loss. FEMA 351 can be used

as a technical basis for both voluntary and

mandatory upgrade programs. In addition,

communities should put emergency response

systems into place. Building departments should

train their personnel to conduct building

inspections. In large cities, building departments

will quickly become overwhelmed by this

responsibility. Before the next earthquake, the

building department should make arrangements

for assistance from outside the affected area.

Some states have agencies that will facilitate

this. Communities should also consider adopting

ordinances to govern the post-earthquake

building inspection and repair process.

Experience has shown that some building

owners will not act responsibly to inspect and

repair buildings, unless required by law to do so.

FEMA 352 can be used as a basis for

developing post-earthquake inspection and

repair ordinances.

Is help available?

FEMA has developed a number of tools that

communities can use to identify their exposure to

natural disasters, including both earthquake and

flood hazard maps. FEMA has also developed

standardized, GIS-based computer software that

can help a community to assess the risk that

these hazards present. This software package,

called HazardsUS, or HAZUS, presently

addresses earthquake risk, however modules

are currently under development that will also

address the risk from floods and high winds.

FEMA has also published a series of guidance

documents for both technical and non-technical

audiences to assist in addressing specific

hazard-related issues. All of these aids are

available, without charge, from FEMA.

Once the hazard and risk are known, FEMA has

a community-based initiative called Project

Impact to help encourage the implementation of

pre-disaster prevention, or mitigation, activities.

This initiative, which may include a one-time

seed grant, encourages the formation of

community-based partnerships between public

and private stakeholders. For more information

on this and other programs, visit FEMA’s website

at www.fema.gov.

Project Impact assists communities to form

public and private partnerships to reduce the

potential for natural disaster losses.
25

THE FEMA/SAC PROJECT AND DISSEMINATING ITS RESULTS

Why did FEMA elect to undertake such

an effort?

FEMA, as part of its role in the National

Earthquake Hazards Reduction Program

(NEHRP), is charged with reducing the everincreasing cost of damage in earthquakes.

Preventing losses before they happen, or

mitigation, is the only truly effective way of

reducing this cost. In this light, the role of this

nation's building codes and standards in mitigating

earthquake losses is critical, and FEMA is

committed to working with this nation's seismic

codes and standards to keep them among the

best in the world. Because the damage that

resulted from the Northridge earthquake called

into question the design assumptions and building

code requirements associated with steel momentframe construction and because of the unknown

life safety hazard of the damaged buildings, it was

crucial that adequate repair and retrofitting

procedures be quickly identified. This was

particularly critical for FEMA, because many of the

damaged steel buildings were publicly owned and

therefore the cost of damage repair was eligible

for funding under the public assistance provisions

of the Robert T. Stafford Disaster Relief and

Emergency Assistance Act. To fully respond to

this need, development of reliable and costeffective methods for use in the various building

codes and standards that address the design of

new construction and the repair and/or upgrading

of existing steel moment-frame buildings was

necessary.

The solution of this problem required a

coordinated, problem-focused program of

research, investigation and professional

development with the goal of developing and

validating reliable and cost-effective seismicresistant design procedures for steel momentframe structures. This work involved

consideration of many complex technical,

professional and economic issues including

metallurgy, welding, fracture mechanics,

connection behavior, system performance, and

practices related to design, fabrication, erection

and inspection.

How were related policy issues

addressed by the FEMA/SAC project?

As part of the project, an expert panel with

representation from the financial, legal,

commercial real estate, construction, and

building regulation communities was formed to

review social, economic, legal and political

issues related to the technical

recommendations. This panel was charged with

evaluating the potential impact of the

recommended design and construction criteria

on various stakeholder groups, identifying

potential barriers to effective implementation of

the recommendations and advising the project

team on potential ways of making the guidelines

more useful and effective. The panel held a

workshop in October 1997 that brought together

representatives of these constituencies, and

their recommendations were considered during

the development of technical recommendations

and in the preparation of this publication.

Why did it take so long to develop the

necessary information?

The damage experienced by steel momentframe structures in the Northridge earthquake

called to question the entire portions of building

codes that addressed this type of construction,

and which had been developed over a period of

more than 20 years. This project basically had

to start from scratch and either revalidate all of

the existing criteria, or when this criteria was

found to be inadequate, develop new design

criteria and construction standards that could be

relied upon. This involved a complete reevaluation of the properties of structural steels

and welding materials, the assumptions used in

designing and evaluating different types of

moment-connections, and the methods used in

inspecting and evaluating these connections and

their behavior. In the process, all of this material

had to be developed and presented in a rigorous

and scientifically defensible manner so that it

would be recognized as reliable and used by the

building design, construction and regulatory

communities. This project accomplished in six

years what originally evolved over 20 years.
26

How will this information be put unto

practice?

The new FEMA guidance documents are now

being widely disseminated to the structural

engineering and building regulation

communities. Three of these publications

provide recommended criteria for design of more

reliable new construction (FEMA 350), upgrading

existing structures to minimize the potential for

future damage (FEMA 351), and evaluating and

repairing buildings after an earthquake (FEMA

352). The fourth provides technical

specifications and quality assurance guidelines

(FEMA 353). Much of the information contained

in these publications, especially for new

construction, is being incorporated into both the

NEHRP Recommended Provisions for Seismic

Regulation of Buildings and Other Structures and

the latest standard design specification

published by AISC. Together, these publications

serve as the consensus design standard for

steel structures nationwide. This standard is

routinely adopted by reference into the model

building codes where it is in turn used as part of

state and/or local building codes. AISC has also

published a design guide, developed jointly with

NIST, for upgrade of existing structures, and

which compliments the recommendations

contained in FEMA 351.

How can one obtain additional

information?

The four FEMA publications described above

can be ordered free of charge by calling 1-800-

480-2520. In addition, a series of state-of-the-art

reports have been developed which summarize

the current state of knowledge that forms the

technical basis for the recommended criteria

publications. These reports are available from

FEMA in CD-ROM format (FEMA 355).

Individual reports on the technical investigations

performed in support of the FEMA/SAC project

are available as well. These technical reports

and FEMA 355 may be purchased in hard copy

format from the SAC Joint Venture. The SAC

Joint Venture will also continue to maintain a

publicly accessible site on the World Wide Web

at www.sacsteel.org. Future information and

training opportunities will be available from the

American Institute of Steel Construction (AISC)

and other organizations. Consult AISC’s World

Wide Web site at www.aisc.org for additional

information.
27

INDEX

American Institute of Steel Construction (AISC), 2,

18, 21, 23, 26

American Welding Society (AWS), 21, 23

building code, 1, 15, 17, 19, 20, 21, 22, 23, 25

collapse, 4, 7, 8, 14, 20

connection, 3, 5, 8, 9, 10, 11, 12, 15, 19, 20, 25

construction, 20

cost, 2, 5, 9, 13, 14, 15, 16, 19, 20, 25

crack, cracks, cracking 4, 5, 6

damage, i, 3, 4, 5, 6, 8, 9, 10, 12, 14, 15, 16, 17, 20,

21, 22, 25, 26

design, 1, 2, 4, 5, 6, 11, 12, 13, 14, 17, 18, 19, 20, 21,

23, 25, 26

FEMA 350 Recommended Seismic Design Criteria

for New Moment Resisting Steel Frame Buildings,

2, 17, 18, 19, 20, 21, 26

FEMA 351 Recommended Seismic Evaluation and

Upgrade Criteria for Existing Welded Steel Frame

Buildings, 2, 11, 12, 14, 15, 16, 21, 26

FEMA 352 Recommended Post Earthquake

Evaluation and Repair Criteria for Welded Steel

Moment Frame Buildings, 2, 8, 9, 10, 24, 26

FEMA 353 Recommended Specifications and Quality

Assurance Guidelines for Steel Moment Frame

Construction for Seismic Applications, 2, 18, 23,

26

fracture, 1, 4, 10, 20, 25

inspection, 5, 8, 9, 23, 24, 25

Kobe, 1, 6

Loma Prieta Earthquake, 1, 6

materials, 19

National Institute of Standards and Technology

(NIST), 2, 26

National Science Foundation (NSF), 2

NEHRP Recommended Provisions for Seismic

Regulation of Buildings and Other Structures

(FEMA 302/303), 12, 21, 25

Northridge earthquake, i, 3, 4, 6, 8, 9, 15, 17, 19,

20, 22, 25

quality assurance, 17, 20, 22, 23, 26

quality control, 22, 23

repair, 1, 2, 9, 10, 15, 20, 24, 25

safety, 7, 8, 9, 14, 15

upgrade, 2, 11, 12, 13, 14, 15, 16, 21

welding, 4, 11, 18, 22, 23

welded joint, 1, 4
The term “mitigation” describes actions 

which can help reduce or eliminate 

your long-term risk from natural 

disasters. With mitigation, you can 

avoid losses and reduce your risk of 

becoming a disaster victim. 

There are many low-cost mitigation 

measures you can take to protect 

yourself, your home, or your business 

from losses. For example: 

FLOODING 

■	 Move valuables and appliances out 

of the basement of your home or business if it is 

prone to flooding. This will increase the chance 

that your belongings will remain dry when a 

flood occurs. 

■	 Have the main breaker or fuse box and the 

utility meters elevated above the anticipated 

flood level in your home or business, so that 

flood water won’t damage your utilities. 

■	 Buy flood insurance to cover the value of your 

home and its contents. Not only will it give 

you greater peace of mind, but it will also 

greatly speed your recovery if a flood occurs. 

To learn more about flood insurance, contact 

your insurance company or agent, or call 

1-800-427-4661. 

EARTHQUAKES 

■	 Bolt or strap cupboards and bookcases to the 

wall, and keep heavy objects on the lower 

shelves. This will reduce both damages and the 

possibility of injury to those in your home or 

business. 

■	 Strap your water heater to a nearby wall using 

bands of perforated steel (commonly known as 

“plumber’s tape”). If a gas water heater falls 

during an earthquake, it could break the gas line 

and start a fire. 

■	 Install bolts to connect your home to its 

foundation. Anchor bolts cost as little as $2 a 

piece, but can prevent thousands of dollars of 

damage. Have them installed every six feet 

around the perimeter of your home. 

HAZARD 

MITIGATION WORKS, 

AND IT CAN SAVE YOU MONEY. 

IT HELPS PROTECT YOUR FAMILY, YOUR 

BUSINESS AND YOUR PROPERTY 

FROM THE EFFECTS 

OF NATURAL 

DISASTERS. 

HURRICANES AND 

TORNADOES 

■	 Have hurricane straps installed in your home or 

business to better secure the roof to the walls 

and foundation. This will reduce the risk of 

losing your roof to high winds. 

■	 Install and maintain storm shutters to protect 

all exposed windows and glass surfaces, and 

use them when severe weather threatens. 

Besides protecting against wind, shutters also 

prevent damage from flying debris. 

■	 Have your home inspected by a building 

professional to ensure that roof and other 

building components are capable of 

withstanding wind effects. 

WILDFIRES 

■	 Move shrubs and other landscaping away from 

the sides of your home or deck. All too often, 

homes burn when plantings around them catch fire. 

■	 Install tile or flame-retardant shingles on your 

roof, instead of wood shakes or standard 

shingles. This will reduce the chance that 

airborne burning debris will end up destroying 

your home. 

■	 Clear dead brush and grass from your property 

so that it will not provide fuel for a spreading 

fire. 
MAKE SURE TO 

MITIGATE PROPERLY — 

THE FIRST TIME! 

Most communities have building 

codes and ordinances which guide 

construction practices. Many of 

these are designed to reduce your 

risk from all types of hazards, 

including floods, earthquakes, high 

winds, and wildfires. 

If you have any questions about local 

codes or ordinances, and how they 

may impact mitigation efforts in your 

home or business, contact a 

professional or your building official. 

Either should be able to provide you 

with the assistance you need to 

mitigate right the first time. 

Mitigation Begins 

With You — Learn to 

Build Stronger, 

Safer, Smarter! 

To learn more about hazard mitigation measures that 

you can take to reduce your risk from disasters, 

visit FEMA’s Internet site (www.fema.gov), or call 

1-800-480-2520 to have a list of available mitigation 

publications mailed to your home or office. 

You can also contact the FEMA Regional Office nearest 

you: 

FEMA Region I (serving CT, NH, ME, MA, RI, VT)


J.W. McCormack Post Office


Courthouse Bldg., Rm. 442


Boston, MA 02109 tel: (617) 223-9540


FEMA Region II (serving NJ, NY, PR, VI)


26 Federal Plaza, Rm. 1337


New York, NY 10278 tel: (212) 225-7209


FEMA Region III (serving DC, DE, MD, PA, VA, WV)


Liberty Square Bldg., 2nd Floor


105 S. Seventh St.


Philadelphia, PA 19106 tel: (215) 931-5608


FEMA Region IV (serving AL, FL, GA, KY, MS, NC, SC, TN)


Koger Center - Rutgers Bldg.


3003 Chamblee-Tucker Road


Atlanta, GA 30341 tel: (770) 220-5200


FEMA Region V (serving IL, IN, OH, MN, WI)


175 W. Jackson Blvd., 4th Floor


Chicago, IL 60604 tel: (312) 409-5518


FEMA Region VI (serving AR, LA, NM, OK, TX)


Federal Regional Center


800 N. Loop


Denton, TX 76201 tel: (817) 898-5127


FEMA Region VII (serving IA, KS, MO, NE)


2323 Grand Blvd., Ste. 900


Kansas City, MO 64108 tel: (816) 283-7060


FEMA Region VIII (serving CO, MT, ND, SD, UT, WY)


Denver Federal Center, Bldg. 710


Box 25267


Denver, CO 80225 tel: (303) 235-4830


FEMA Region IX (serving AZ, CA, HI, NV)


Building 105, the Presidio


San Francisco, CA 94129 tel: (415) 923-7175


FEMA Region X (serving AK, ID, OR, WA)


Federal Regional Center


130 228th St., SW


Bothell, WA 98021 tel: (206) 481-8800


Is your family, home, or 

business protected from 

natural disasters? 

They can be. 

REDUCE


YOUR RISK


FROM


N ATURAL


DISASTERS


Federal Emergency 

Management Agency 

Reach us on the Internet 

at http://www.fema.gov 
FEDERAL EMERGENCY MANAGEMENT AGENCY


SEISMIC SAFETY OF BUILDINGS


Sources of information for design professionals and other decision makers in 

earthquake hazard mitigation 

EXISTING BUILDINGS


Rapid Visual Screening of Buildings for Potential Seismic 

Hazards: A Handbook (FEMA-I 54, 1988, 185 pages) and 

Rapid Visual Screening of Buildings for Potential Seismic 

Hazards: Supporting Documentation (FEMA-I 55,1988,137 

pages). Prepared by the Applied Technology Council, Redwood City, CA (ATC-21 and ATC-21 -1). 

The Handbook presents a method for quickly identifying buildings posing risk of death, injury, or severe curtailment in use 

following an earthquake. The methodology, “Rapid Screening 

Procedure (RSP),” can be used by trained personnel to identify 

potentially hazardous buildings on the basis of a 15 to 30 minute 

exterior inspection, using a data collection form included in the 

Handbook. Twelve basic structural categories are inspected, 

leading to a numerical “structural score” based on visual inspection. Building inspectors are the most likely group to implement an RSP, although this report is also intended for building 

officials, engineers, architects, building owners, emergency managers and interested citizens. The Supporting Documentation reviews the literature and existing procedures for rapid visual screening. 

NEHRP Handbook for the Seismic Evaluation of Existing 

Buildings (FEMA-178, 1992, 227 pages). Prepared by the 

Building Seismic Safety Council, Washington, D.C. 

The Handbook presents a nationally applicable method for 

engineers to identify buildings or building components that 

present unacceptable risks in case of an earthquake. Four 

structural subsystems in which deficits may exist are identified: vertical elements resisting horizontal loads; horizontal elements resisting lateral loads; foundations; and connections 

between structural elements or subsystems. Fifteen structural categories are defined for the evaluation of buildings by 

engineers. The Handbook is formulated to be compatible with 

NEHRP Handbook of Techniques for the Seismic Rehabilitation of Existing Buildings (FEMA-172/1992). 

NEHRP Handbook of Techniques for the Seismic Rehabilitation of Existing Buildings (FEMA-172, 1992,197 

pages). Prepared by the Building Seismic Safety Council, 

Washington, DC. 

This handbook presents techniques for solving a variety of 

seismic rehabilitation problems. intended for engineers concerned with seismic rehabilitation of existing buildings, the 

handbook identifies and describes seismic rehabilitation 

techniques for a broad spectrum of building types and building components (both structural and nonstructural). Most 

techniques are illustrated with sketches, and the relative 

merits of the techniques are discussed. Designed to be 

compatible with the NEHRP Handbook for the Seismic 

Evaluation of Existing Buildings (FEMA-178/1992), this 

publication is based on a prelimary version prepared by 

URS/John A. Blume and Associates, Technique for 

Seismically Rehabilitating Existing Buildings (FEMA172/1989). 

Typical Costs for Seismic Rehabilitation of Existing 

Buildings: Volume 1: Summary, Second Edition (FEMA156, 1994, approx. 70 pages); Volume 2: Supporting 

Documentation, Second Edition (FEMA-1 57, 

1995,approx. 102 pages). Prepared by the Hart Consultant Group, Inc. Santa Monica, CA. [FEMA-156, 1994 AND 

FEMA-157, 1995 SUPERSEDE FEMA-156, 1988 AND 

FEMA-157. 1988]. 

Typical Costa for Seismic Rehabilitation of Existing 

Buildings: Volume I: Summary second Editionprovides 

a methodology that enables users to estimate the costs of 

seismic rehabilitation projects at various locations in the 

United States. This greatly improved edition is based on a 

sample of almost 2100 projects. The data were collected by 

use of a standard protocol, given a stringent quality control 

verification and a reliability rating, and then entered into a 

database that is available to practitioners. A sophisticated 

statistical methodology applied to this database yields costs 

estimates of increasing quality and reliability as more and 

more detailed information on the building inventory is used 

in the estimation process. Guidance is also provided to calculate a range of uncertainty associated with this process. 

The Supporting Documentation contains an in-depth discussion of the approaches and methodology that were used 

in developing the second edition. 
Benefit-Cost Model for the Seismic Rehabilitation of Hazardous Buildings. Volume 1: A User’s Manual (FEMA-227, 

1992, approx. 68 pages); Volume 2: Supporting Documentation (FEMA-228, 1992, approx. 62 pages); and Computer 

Software for Benefit-Cost Model for the Seismic Rehabilifation of Hazardous Buildings. Prepared by VSP Associates, Inc., Sacramento, CA. 

The two benefit-cost models presented in this report are designed to help evaluate the economic benefits and costs of 

seismic rehabilitation of existing hazardous buildings. The 

single class model analyzes groups of buildings with a single 

structural type, a single use, and a single set of economic assumptions. The multi-class model analyzes groups of buildings that may have several structural types and uses. The 

User's manual presents background information on the development of the benefit-cost model and an introduction to the 

use of benefit/cost analysis in decision making. It reviews the 

economic assumptions of benefit-cost models, with and without including the value of life. The User’s Manual guides the 

user through the model by presenting synopses of data entries 

required, example model results, and supporting information. 

Seven applications of the models are presented: five of the 

single-class model; two of the multi-class model. 

Supporting Documentation complements the User’s Manual 

by providing four appendices that help the user understand 

how the benefit-cost models were constructed. The appendices include: 1 ) a review of relevant literature; 2) a section on 

estimating costs for seismic rehabilitation; 3) a compilation of 

tables for the Seattle building inventory; and 4) some insights 

into the building rehabilitation of the nine cities visited during 

this project. 

Computer Software to run the benefit/cost models is also available. The programs are on 31⁄2” diskettes and can be used on 

IBM compatible personal computers. 

Seismic Rehabilitation of Federal Buildings: A Benefit/ 

Cost Model. Volume 1: A User’s Manual (FEMA 255,1994, 

approx. 158 pages); Volume 2: Supporting Documentation 

(FEMA-256, 1994, approx. 71 pages) and Computer Software for the Seismic Rehabilitation of Federal Buildings. 

Prepared by VSP Associates, Inc., Sacramento, CA. 

This User’s Manuel and accompanying software present a 

second generation cost-benefit model for the seismic rehabilitation of federal and other government buildings. Intended 

for facility managers, design professionals, and others involved in decision making, the cost/benefit methodology provides estimates of the benefits (avoided damages, avoided 

losses, and avoided casualties) of seismic rehabilitation, as 

well as estimates of the costs necessary to implement the 

rehabilitation. The methodology also generates detailed scenario estimates of damages, losses, and casualties. The 

Manual describes the computer hardware and software required to run the program. It also explains how to install the 

program, how to use Quattro Pro for Windows, and how to 

enter necessary data. A tutorial provides a fully worked example. Benefit/Cost analyses of eight federal buildings are 

included. The Supporting Documentation contains background information for theUser’s Manual including information on valuing public sector services, discount rates and multipliers, the dollar value of human life, and technical issues 

that affect benefit/cost analysis, such as seismic risk assessment and sensitivity analysis. 

Computer Software to run the benefit/cost model is available on 3 1/2” diskettes and can be used on IBM compatible 

personal computers with at least 386 CPU. The computer 

must also have Windows and Quattro Pro. 

Establishing Programs and Priorities for the Seismic Rehabilitation of Buildings: handbook(FEMA-174,1989,122 

pages) and Establishing Programs and Priorities for the 

Seismic Rehabilitation of Buildings: Supporting Report 

(FEMA-173, 1989, 190 pages). Prepared by Building Systems Development, Inc. with integrated Design Services and 

Claire B. Rubin. 

These two volumes provide the information needed to develop a 

seismic rehabilitation? program, with particular reference establishing priorities. The Handbook is intended to assist local jurisdictions in making informed decisions on rehabilitating seismically 

hazardous existing buildings by providing nationally applicable 

guidelines. It discusses the pertinent issues that merit consideration, both technical and societal, and suggests a procedure 

whereby these issues can be resolved. The Supporting Report 

includes additional information and commentary directly related 

to sections in the Handbook supporting documentation, annotated bibliographies, and reproductions of selected laws and ordinances that are presented in summary form in the Handbook. 

Financial Incentives for Seismic Rehabilitation of Hazardous Buildings - An Agenda for Action. Volume 1: Findings, Conclusions, and Recommendations (FEMA-198, 

1990,104 pages); Volume 2: State and Local Case Studies 

and Recommendations (FEMA-199, 1990, 130 pages); and 

Volume 3: Applications Workshops Report (FEMA-216, 

1990, about 200 pages). Prepared by Building Technology, 

Inc., Silver Spring, MD. 

The intent of these documents is to identify and describe the 

existing and potential regulatory and financial mechanisms and 

incentives for lessening the risks posed by existing buildings 

in an earthquake. Volume 1 includes a discussion of the methodology used for these documents, background information 

on financial incentives, as well as findings, conclusions and 

recommendations for use by decision makers at local, state 

and national levels. Volume 2 includes detailed descriptions 

of the twenty case studies that were examined as part of this 

project. Volume 3 reports on workshops for the development 

of local agendas for action in seismic rehabilitation. It includes 

directions for convening additional workshops and teaching 

materials which can be used in such workshops. This information is directed primarily to groups that are interested in 

planning for local seismic mitigation in existing buildings who 

wish to convene a workshop to initiate the process. 
Development of Guidelines for Seismic Rehabilitation of 

Buildings - Phase 1: issues identification and Resolution 

(FEMA-237, November 1992, 150 pages). Prepared by the 

Applied Technology Council, Redwood City CA (ATC-28). 

This report is intended to assist in the preparation of Guidelines for the Seismic Rehabilitation of Existing Buildings. 

The report identifies and analyzes issues that may impact 

the preparation of the Guidelines and offers alternative as 

well as recommended solutions to facilitate their development and implementation. Also discussed are issues concerned with the scope, implementation, and format of the 

Guidelines, as well as coordination efforts, and legal, political, social, and economic aspects. Issues concerning historic buildings, research and new technology, seismicity and 

mapping, as well as engineering philosophy and goals are 

discussed. The report concludes with a presentation of issues concerned with the development of specific provisions 

for major structural and nonstructural elements. 

Publications concerning existing buildings can be obtained at no charge from the FEMA Distribution Center, P.O. Box 2012, Jessup, 

MD 20794. Telephone: 1-800-480-2520; Fax: (301 ) 497-6378. 

This list was prepared by the Information Service, National Center for Earthquake Engineering Research (NCEER), 304 Capen Hall, 

University at Buffalo, Buffalo, NY 14260-2200. Telephone: (716) 645-3377; Fax: (716) 645-3379; 

E-Mail: nernceer@ ubvms.cc.buffalo.edu; WWW: http://nceer.eng.buffalo.edu. Revised 10/20/95