HomeMy WebLinkAbout1996-10-22 - AGENDA REPORTS - EARTHQUAKE DESIGN BLDG CODE (2)AGENDA REPORT
City Manager Approval
Item to be presented
Ruben Barrera
NEW BUSINESS
DATE: October 22, 1996
SUBJECT: PROCESSING OF AMENDMENTS TO EARTHQUAKE DESIGN
REQUIREMENTS OF THE BUILDING CODE
DEPARTMENT: Building and Engineering Services
Following every major earthquake, there are public calls to enact more stringent seismic design
regulations for buildings. At the same time, the scientific and engineering communities are
reviewing data generated by the most recent earthquake to assess the adequacy of the current
seismic design regulations and answer questions raised by the public concerning these
regulations. This occurred following the 1989 Loma Preita Earthquake in Northern California,
the 1994 Northridge Earthquake, and the 1995 Kobe Earthquake in Japan. The purpose of this
report to the City Council is to present information on potential options for adoption of future
seismic design code amendments and to request feedback from the City Council on how to
proceed. This report is not intended to present technical information on what code changes
could be adopted.
Current Efforts to Enhance Seismic Safety
The City has taken certain steps toward enhancement of the Building & Safety program by
increasing the training budget for Building & Safety technical staff in accordancewith the
requirements of AB 717 which became effective on January 1, 1996. The State Bill requires
minimum training hours and certifications for Building & Safety inspectors and engineers, as
well as the Building Official, to ensure more effective enforcement of the State's building laws.
Also, the recent adoption of a revised City fee schedule included recovery of costs associated
with additional needed resources in Building & Safety which will allow for a greater degree of
enforcement of building regulations, including efforts to prevent and control illegal construction.
As a result, this year the Building & Safety Division has initiated an improved training and staff
development program.
In 1997-98 the City will be subject to a comprehensive evaluation by the insurance industry on
the effectiveness of its Building & Safety program. This effort is intended to ensure that certain
minimum enforcement efforts are being taken by building departments nationwide. This
program was developed by insurance companies to produce better results in terms of amounts
of building damage during future disasters. In accordance with the resulting effectiveness
PROCESSING OF AMENDMENTS TO EARTHQUAKE DESIGN
REQUIREMENTS OF THE BUILDING CODE
October 22, 1996 - Page 2
rating, local residents are expected to receive corresponding credits on home insurance
premiums. These efforts are expected to produce an overall improvement in the Building &
Safety program and should result in a higher level of construction compliance with seismic
safety measures.
Recently, the Building & Engineering Services Department also implemented revisions to our
grading requirements that address soils and geotechnical problems that are known to have
contributed to some of the structural damage observed during the 1994 earthquake. The
Department also adopted procedures to address soil liquefaction in accordance with the State's
new Liquefaction Zone Maps which were developed in part to address seismic safety.
Building & Safety's new automated permit issuance and tracking system was developed to
improve access to permit records and documentation. These are expected to accommodate a
state of the art records retrieval system that the Division intends to implement in the near
future and which will include approximately 400,000 to 500,000 permits for existing houses and
structures that the City inherited from the County. Making these records more easily accessible
and available will allow for greater access and flow of information to realtors, contractors and
the general public which should help address seismic safety limitations in existing structures.
Available Options for Adoption of Future Code Amendments
In light of the extent and type of damage suffered to buildings during the 1994 earthquake,
changes to the seismic provisions of the current building code would likely reduce the potential
for structural damage during a future earthquake. The following options represent a minimum,
a modest, and an extensive approach to the issue of amending the seismic provisions of our
building code. These are:
1. Minimum - Continue monitoring potential changes to the building code and adopt seismic
provisions through the established code change process as mandated by the State of
California.
2. Modest - Adopt interim technical amendments to the building code which have been
developed and adopted by the County of Los Angeles (Appendix A).
3. Extensive - Develop a task force containing all stake holders (i.e., architects, engineers,
contractors, developers and property owners) to assess the potential for developing our own
local seismic design amendments to the building code as well as planning how to educate the
community and construction industry on the local amendments.
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Shortly after the Northridge Earthquake, the City amended our building code to require
building permits for all masonry or concrete walls over 42 inches in height, as opposed to the
previous 72 inch height limit. This was the only local amendment adopted by the City and was
done to address the large economic loss associated with the damage to block walls within our
City from the quake. The City has also adopted several technical amendments dealing with
earthquake design as part of our adoption of the 1994 Uniform Building Code, in accordance
with the State -mandated procedures, which were developed as a result of the Loma Prieta
Earthquake and adopted at a national level.
PROCESSING OF AMENDMENTS TO EARTHQUAKE DESIGN
REQUIREMENTS OF THE BUILDING CODE
October 22, 1996 - Page 3
Discussion on Option 1- Minimum Approach
In May of 1994, at the request of Mayor Pederson, the City brought together local engineers,
architects, contractors and developers to discuss potential amendments to the City's building
code based on the preliminary observations of damage from the Northridge Earthquake. The
consensus of the meeting was that the City should not hastily adopt any local amendment to the
seismic design requirements of the building code but should allow the traditional code change
process to handle any amendments to the building code. This approach did not require any
added resources and allowed the City to stay in conformance with the State Building Code.
The drawback to this approach is that any potential code changes developed from the
Northridge Earthquake would not be incorporated into our building code until sometime in
1998, when the State -mandated adoption of the 1997 edition of the Uniform Building Code takes
place.
Discussion on Option 2 - Moderate Anuroach
One step above the minimum approach would be to adopt the seismic design amendments which
have been developed and adopted by the County of Los Angeles. These amendments increase
the seismic resistance of buildings to some degree and would create consistency in the seismic
design of new stuctures between the City and the County.
Although these changes may increase the cost of some construction by up to 3-5%, newer
buildings would be less likely to experience damage during similar future earthquakes. Also,
not all engineers agree with the amendments or are familiar with them, and the City would
likely experience some delays in the time needed to review plans and permit applications until
local designers and contractors familiarize themselves with the changes.
It should also be noted that the County amendments are not as restrictive as those developed
by the City of Los Angeles and do not address the issue of retrofitting existing buildings to
upgrade certain structural deficiencies where present.
Discussion on Option 3 - Extensive Approach
Currently, there are approximately 30 independent organizations within California working on
various issues associated with seismic safety. A "Report to the Governor, W-78-94" by the
Seismic Safety Commission (see attached summary from the report), published a year after the
Northridge Earthquake, brought up issues such as:
* What is Acceptable Seismic Risk?
* Building Owner's Responsibility
* Building Designer's Responsibility and Qualifications
* Contractor's Responsibility and Qualifications
* Qualification and Knowledge of Plan Review and Inspection Staff
* Reducing Earthquake Risk from Non -Structural Portions of the Building
PROCESSING OF AMENDMENTS TO EARTHQUAKE DESIGN
REQUIREMENTS OF THE BUILDING CODE
October 22, 1996 - Page 4
The State has not decided on appropriate standards and answers to these questions and issues
as of this date. The development of an extensive approach to seismic safety would allow the
City to attempt to address all of these issues. Inasmuch as it would be a first for a City the size
of Santa Clarita to attempt to proactively approach the issue of seismic safety, the development
of programs and service, developed through a collaborative approach, would require added
resources. However, the results could vary tremendously and include retroactive programs for
steel buildings, tilt -up buildings, and school and public education programs, and would direct
staff to fully participate in the development of the national code's provisions.
The drawback to this approach is the cost of the program (between $60,000 to $250,000 per
year) and the fact that it may be up to 15 years or until the date of another large earthquake
in this area before we see the full benefits of such a program.
ncludina Remark
The City of Santa Clarita was fortunate during the Northridge Earthquake in that we have
fairly new structures in our City and most of them survived the earthquake. However, we need
to become more proactive in ensuring that buildings are built to adequate safety standards and
that our standards represent a reasonable level of earthquake damage prevention.
We know that we will experience future earthquakes that will have a significant impact on the
lives of our residents and the economy of our City. Preparation for future earthquakes is
imperative for minimizing these impacts on the community. Proactive involvement can and will
minimize the cost of a reactive response in the future. The determination of the priority of
added seismic safety programs in relation to the other services, such as youth programs, wildfire
programs, capital improvement programs, and police and fire services, is one that is left to the
community through the City Council.
ECOMMENDAT
The City Council direct staff to prepare an Ordinance to adopt Los Angeles County's Building
Code Amendments to improve seismic safety in construction of new buildings as presented in
Appendix A.
Report to the Governor, W-78-94 - Executive Summary
Summary of Los Angeles County Building Code Amendments
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Executive Summary
alifornia is a remarkable place in which to live and work. In
spite of its earthquake hazards, its residents are relatively safe
from earthquakes. Its building stock and lifelines and the people and
programs that address its earthquake risk are among the best in the world.
Californians are fortunate that seismic codes have been written and
Unless seismic safety
enforced here for the last half century, making California buildings
is afforded a priority
better able to withstand earthquakes than buildings elsewhere. People
that is now lacking,
can live and invest safely in California, knowing that earthquake risk
is addressed and that desired levels of seismic safety can be achieved
Californians will
if an effort is made.
continue to erperi-
Nevertheless, the messages from the Northridge and earlier earthquakes
once avoidable losses
are clear. Despite our codes and world-renowned expertise, too many of
from earthquakes.
our buildings and other structures remain vulnerable to earthquake dam-
age. There are significant weaknesses in the way we exercise land use
planning laws and design and construct buildings and lifelines. Too much
of what we do is done by people who lack the will, knowledge, or support
to deal with a hazard that has the public -safety and economic implica-
tions ofearthquakes. Much ofwhat we have learned in past earthquakes—
and were reminded of by Northridge—is not applied with the appropri-
ate level of commitment, consistency, and priority.
Steps can be taken to reduce future losses to more acceptable levels.
California's state and local agencies, building owners, lifelines organiza-
tions, construction industry, geologists, architects, and engineers can
and must do more to reduce future damage. Earthquake risk will not be
reduced significantly until earthquake lessons are consistently applied
with a new sense of urgency. The Seismic Safety Commission's recom-
mendations lay out needed actions, but unless seismic safety is afforded
a higher priority, Californians will continue to experience avoidable eco-
nomic and personal losses from earthquakes.
page a
N o r t h r i d g e E a r t h q u a k. a T u r n i n g L. o s s ! o C a i n
Governor Pete Wilson issued Executive Order
W-78-94 after the Northridge earthquake
struck the San Fernando Valley and surround-
ing areas. In that order, he asked the Commis-
sion to review the effects of the earthquake
and make recommendations on seismic safety
and land use planning. The Commission
responded by directing the preparation of 39
background reports and relying on research
done by others (including members of the
Commission); testimonies received at hear-
ings, commissioner -prepared issue statements,
and 27 case studies of buildings damaged in
the Northridge earthquake.
Effects of the Earthquake
The magnitude 6.7 Northridge earthquake
occurred at 4:31 in the morning of January 17,
1994, on a national holiday, when most
Californians were at home asleep. Fifty-seven
people lost their lives, nearly 9,000 were
injured, and damage exceeded $20 billion.
The summary of the Northridge earthquake's
impact is "It could have been a lot worse." In
fact, it would have been a lot worse if the
earthquake had occurred later in the day and
if its duration and intensity had been of the
nature anticipated for most of California. Most
of the collapses and other life-threatening
failures were to commercial, industrial, and
institutional buildings and to freeway bridges,
which were virtually empty at the time,
Ilundreds of apartment buildings, many of
them perched over open parking areas, were
damaged; 16 people died in one collapse.
Today, concentrations of these buildings are
ghost towns, since many owners have not yet
been able to rebuild. Thousands of homes and
apartments were damaged; though much of
the damage was not severe enough to compro-
mise safety, it will cost billions to repair or
replace these residences.
Thousands of commercial buildings were
damaged. Building codes that were revised for
tilt -up concrete buildings after the 1971 San
Fernando earthquake need to be further
revised, and they need to be better enforced;
page Y
once again, tilt -ups suffered major damage.
The performance of steel moment -frame
buildings, thought to be state-of-the-art in
earthquake resistance, surprised the engineer-
ing community; studies are now underway to
determine why failures occurred in connec-
tions between beams and columns. Much of
the damage to these buildings was hidden
under fireproofing and finishes, so previous
earthquakes may also have caused undiscov-
ered damage and weakened buildings.
Although fires following earthquakes are
significant hazards for California, fires were
nota major problem in this event. However,
mobile home parks suffered disproportion-
ately when fires fed by natural gas swept
through them.
Freeway bridges built or designed before the
mid-1970s that had not yet been addressed
by Caltrans' retrofitting program suffered
major damage and collapse; with a few
exceptions, bridges built or retrofitted since
then performed well. The cost of repair was
over $350 million.
Predictably, telephone systems were compro-
mised, not primarily because of equipment
failures but because of system overloads. And
as usual, the various emergency response
units—firefighters, police, highway patrol,
sheriff, medical, and mutual -aid units—and
hospitals had difficulty communicating
because of incompatible radio equipment, loss
of power, inadequate backup power supplies,
and damage to equipment.
Other utilities also suffered failures. Electricity
was out for up to three days in some areas, but
power was restored to most customers within
24 hours. Most of the natural-gas lines that
broke were old pipe, which is being replaced as
part of a continuing pipeline replacement
program. Water lines broke, and water had to
be trucked to some of the hardest-hit areas for
several weeks.
To these physical damage losses must be added
the losses from business interruption, closings
of universities and schools, foreclosures, and
reduction of the tax base. Insurance claims
reached around $11 billion.
Although many scars remain, and the life
losses and some financial losses are perma
nent, the Los Angeles area as a whole will
recover from the Northridge earthquake. The
new debts assumed to make repairs will be
paid off, the affected businesses will recover,
the people will return to their daily rounds. All
too quickly, measures to reduce losses from
future earthquakes seem less and less impor-
tant to residents and government officials
unless steps are taken to reverse the usual
pattern observed after past earthquakes.
Buildings
The Northridge earthquake demonstrated that,
although California's current building codes and
practices are generally adequate to protect lives,
they are not intended to protect Californians
from the economic disaster that a major earth-
quake would cause. California has many of the
world's best earthquake safety experts and one of
the most comprehensive building codes for
earthquake resistance. The low loss of life in the
Northridge earthquake compares favorably to
similar earthquakes in other parts of the world,
but the unprecedented economic losses indicate
that California still needs to make major efforts
to reduce the earthquake damage vulnerability
of its buildings,.
The Northridge earthquake exposed a large
urban building stock to intense shaking for
the first time in California since the advent of
modern building codes. Strong shaking lasted
only about nine seconds; nevertheless, it
vividly demonstrated that, although California
has come a long way since the 1971 San
Fernando earthquake, there are many im-
provements that still should be made to
ensure that California's economy, as well as its
citizens, survive major urban earthquakes:
• The quality of design and construction
must be improved. Poor quality in design,
plan review, inspection, and construction
were encountered over and over again in the
buildings damaged by the earthquake.
E x e c u 1 i u e S u m m a r y
California's current system of building design
and construction encourages individual
gambles that add up to a significant risk, both
for those who own the buildings and for those
who depend on them as employees, tenants,
or customers. Improving the quality of design
and construction for new buildings and
retrofit projects would increase safety
dramatically at relatively minor increases in
building costs.
Building codes must be improved. As
expected, damage was more prevalent in
older buildings. Modern buildings—those
built to current codes—in general met the
intended life safety objective of the building
code. Notable exceptions to this included
poor performance in modern concrete
parking structures, tilt -up buildings, and
welded -steel moment -frame buildings.
Code changes have been proposed to begin
to address these and other problems for
future construction. Future codes and
seismic design guidelines should take
better account of enhanced performance
objectives and geologic and near -source
effects on structures. In light of the
extensive and costly damage to modern
buildings, the state should be more active
in its support of efforts to establish accept-
able levels of earthquake risk in buildings
and to develop codes and design guidelines
to meet performance objectives.
• Nonstructural hazards must be reduced. A
building's heating and air conditioning
systems, lighting fixtures, fire sprinklers,
furniture, and equipment can become
hazards in an earthquake if they are not
adequately secured, and their loss can make
a building unusable. Making these systems
more secure is a relatively inexpensive way
of improving seismic safety and post -
earthquake functioning of both new and
existing buildings.
• Risks from existing buildings need to be
identified, disclosed, and reduced. Some
types of older buildings pose significant
threats to both life and economy in
earthquakes, but it is impractical to
page xi
The Northridge
earthquake exposed
a large urban building
stock to intense
shaking for the
first time since the
advent of modern
building codes.
California's current
system of building
design and construc-
tion encourages
individual gambles
that add up to a
significant risk
N o r t h r i d g e E a r t h q u a k e;
recommend replacement or retrofit of all
such buildings overnight. Local govern-
ments can reduce the risk through better
land use planning and zoning incentives,
but financial incentives are needed to
encourage owners to retrofit.
Some types of buildings demonstrated special
problems during the Northridge earthquake.
Old, poorly built or maintained single-family
dwellings and multistory wood -frame build-
ings with inadequately braced ("soft") first
stories are vulnerable to damage. Many mobile
homes were thrown from their supports; some
were destroyed by fires fed by sheared natural-
gas connections. Despite code changes after
the 1971 San Fernando earthquake, tilt -up
and masonry buildings and aboveground
concrete parking structures sustained signifi-
cant damage with serious economic implica-
tions. Many older concrete -frame buildings
are vulnerable to sudden collapse and pose
serious threats to life.
Welded -steel moment -frame buildings, once
considered to be state-of-the-art in earth-
quake resistance, suffered serious damage to
their connections, damage with serious
implications that must be investigated and
solved. Public school and modern hospital
structures generally performed well, thanks
to the extra care taken in their design and
construction, but nonstructural damage was
serious enough to prevent some from
functioning immediately after the earth-
quake. California State University at
Northridge suffered major damage to a
parking structure and serious damage to
several other buildings, demonstrating the
need for better design review and construc-
tion inspection.
The earthquake demonstrated that un -
reinforced masonry buildings that had been
retrofitted to preserve life safety withstood the
earthquake better than those that were not
retrofitted. Ifowever, many were still damaged
beyond hope of repair, and owners who did not
understand the goal of retrofitting were
disappointed. Retrofitted older concrete and
page xii
T u r n i n g L. o s s t o C a i n
wood buildings also appear to have performed
better than their unretrofitted counterparts.
An overriding question that arises from the
Commission's study of the effects of the
Northridge earthquake on buildings is "What
level of risk to the public is acceptable?"
Professionals can describe the risks, but policy
makers, owners, and others may not under-
stand the implications and, therefore, not be
able to make truly informed decisions about
what is acceptable. We could build nothing but
square one-story houses with few windows on
flat ground well away from any known fault;
that would minimize earthquake risk, but
would significantly reduce the livability of our
homes. Or we could build "disposable" build-
ings, intended to be replaced after the first
damaging earthquake. The answer lies some-
where between these extremes, and the
Commission believes the question must be
answered at a policy level before building
codes and state law can adequately address the
practical issues of improving buildings.
Lifelines
All the affected area's lifeline systems—
freeways, railroads, and communications as
well as natural-gas, water, power, and sewage -
disposal systems—suffered damage in the
Northridge earthquake. The most spectacular
failures, those of the. freeway bridges, raise
questions regarding design and construction
of new bridges as well as retrofitting of
existing ones. Although Caltrans is addressing
these problems, the Commission believes the
toll bridge retrofit program must be acceler-
ated and properly funded.
Power outages and system overloads were the
culprits in most communications difficulties.
In this earthquake cellular telephones were
also overloaded. The cellular system must have
an emergency priority system similar to that of
land lines. The most serious failures of
communications were in medical and emer-
gency services. Many failures of hospital
communications systems were caused by
damage to unanchored equipment and failure
of emergency power generating equipment,
which in turn was a result of a lack of regular
testing or, in some cases, because operators
were unfamiliar with the equipment.
That few fires caused by natural gas followed
this earthquake was due more to favorable
weather and good luck than to the strength of
the system. The gas companies need to
accelerate their replacement of old vulnerable
pipe and to address other weaknesses in the
system, such as the hazard created when
mobile homes fall off their supports and break
gas connections.
The Northridge earthquake caused extensive
power outages. A few high-voltage transmis-
sion towers were damaged when their footings
were displaced. This and other areas of
damage should be investigated, and the
electric utilities should continue their efforts
to improve the ability of their facilities to
resist earthquake damage.
In addition to disrupting the delivery of water
from the Colorado River and northern
California, the earthquake caused many local
breaks in water distribution lines; some areas
were without water for weeks. The potential
for massive disruption of water systems poses
significant public health hazards as well as
inhibiting firefighting ability and disrupting
businesses in the affected area. Like other
utilities, water districts must strengthen their
systems to withstand earthquakes.
Several dams were damaged but none failed, a
testimony to the effectiveness of the owners'
strengthening efforts and the Department of
Water Resources' Division of Safety of Dams.
However, damage patterns indicate that in
stronger or longer -lasting earthquakes, it will
be a different story. Federal dams, which are
built to different standards from the state's,
and dams for which failures would inundate
heavily populated areas should be reevaluated.
Land Use Planning
Community general plans can be used to
identify, avoid, or mitigate seismic hazards,
E x e c u l i v e S u. m m a r y
and they can also provide information that
local officials need to predict earthquake
damage patterns and plan for recovery. Zoning
can also be used to discourage seismic haz-
ards. Waivers of zoning regulations are one of
the options that cities and counties have for
encouraging retrofit or demolition of
seismically hazardous buildings. State guide-
lines for environmental impact reports
should include instructions for dealing with
seismic hazards of development and redevel-
opment projects.
Most local officials do not have up-to-date
geologic information to help them apply land
use planning as a tool to reduce their commu-
nities'seismic hazards. The California Division
of Mines and Geology's Seismic Hazards
Mapping Program must provide this informa-
tion to the majority of urban California within
a reasonable time.
Geologic and Geotechnical
Lessons
Like the Coalinga and Whittier Narrows
earthquakes in the 1980s, the Northridge
earthquake—which also occurred on a blind,
or buried, fault—proved that buried faults can
cause significant damage. Geologists believe
that such faults underlie many California
urban areas—not only the. Los Angeles basin
and the San Fernando Valley, but also the
Ventura -Santa Barbara region, the Santa
Clara -San Jose region, and other areas.
California has a program under the Alquist-
Priolo Earthquake Fault Zoning Act to identify
faults that break the surface and mitigate their
hazards, These efforts should be broadened to
identify areas with buried and other active
faults that do not meet the law's definitions of
an "active" fault.
Shortly after the Northridge earthquake, there
was speculation that the high level of damage
resulted from unusual vertical accelerations,
but the Commission has received no evidence
that vertical accelerations were unusual
relative to the horizontal accelerations.
P age xiii
NORTNRIDCE
ff,71' N o r t h r i d g e E a r l h g u a k e T u r n i n g L o s s t o G a i n
The 168 recommen-
dations in this report
form a blueprint to
reduce earthquake
risks.
Though the Northridge earthquake produced
the largest set of ground motion records ever
obtained from a California earthquake, many
of the badly shaken areas were not fully
instrumented. Shaking in the near -source
area—the area above and near a fault—has
unique characteristics that can increase
damage. Near -source and geological effects
should be considered in the design of
important buildings and in land use plan-
ning. More instruments are needed, as well
as research to determine what implications
the generally more severe ground motions
near the epicenter of the earthquake might
have for structural design.
Local site conditions played an important part
in the level of damage. The Seismic Hazards
Mapping Program being pursued by the
California Division of Mines and Geology must
be accelerated to identify site conditions that
might create or add to seismic risks, particu-
larly those under urban areas, so that appro-
priate precautions can be taken, both in
buildings and in land use planning, to mini-
mize earthquake damage.
Reducing Earthquake Risk
in California
The 168 recommendations in this report form
a blueprint to reduce earthquake risks, but
will only be effective if they are carried out
with the level of effort needed. To begin,
government agencies, businesses, and private
individuals must be made accountable for
managing their earthquake risks to achieve
four basic goals:
• Make seismic safety a priority. Responsibility
for seismic safety actions and programs is
diffuse; seldom can one person or one agency
be held accountable for reaching seismic
safety goals. Seismic safety is usually only a
small part of a business' or public agency's
activity—and not the part that brings big
rewards or promotions if successful. Indeed,
it takes a damaging earthquake to prove that
risk -reduction efforts were successful. Efforts
page xi,
and laws to carry out seismic safety programs
must receive the attention they need to
ensure that California's earthquake risk is
reduced. The recommendations clarify
responsibility and require accountability.
Every agency secretary should be made
responsible for the efforts of departments,
boards, and commissions within their
jurisdictions to make seismic safety a priority.
Improve the quality of construction. Improv-
ing the quality of construction from top to
bottom is a far-reaching goal in terms of
number of people affected—owners, archi-
tects, engineers, contractors, workers,
inspectors, code writers, materials suppliers,
researchers, and more. But it is also the most
cost-effective way of reducing California's
earthquake risk. The many actions that
should be taken reflect the complex nature of
the problem, but they boil down to one
simple fact buildings that are properly
designed and constructed are better able to
resist earthquakes.
• Reduce the risk from seismically vulnerable
structures. California's greatest earthquake
risk is from structures that fail in earth-
quakes. The types that fail are well known,
but identifying individual structures that are
likely to collapse and strengthening or
phasing them out of use is a monumental
task that will take decades of efforts. Never-
theless, the risk must be addressed as a
priority. State government can help by
developing building retrofit guidelines and
financial incentives as it has with Proposition
122 local government grants, but local
governments must take the lead in develop-
ing similar incentives for individual owners.
Improve the performance of lifelines.
Caltrans and most utility companies are
aware of the seismic risks to their facilities
and are working to reduce or eliminate them.
Additional resources and actions are needed
to strengthen systems and speed earthquake
recovery. Vulnerable structures, pipelines,
and equipment must be replaced and reliable
backup power and communications provided.
Those four goals can be reached by imple-
menting the Commission's recommendations.
Seven broad tasks must be completed to
achieve those goals:
Define acceptable risk. State laws and
policies have attempted to define accept-
able earthquake damage levels for schools,
hospitals, and emergency services build-
ings. Similar policies are needed to define
what damage is acceptable for the rest of
the building stock, or it will be difficult or
impossible to define, let alone achieve,
goals of reducing structural and
nonstructural damage. Performance
objectives over and above the basic goal of
life safety are needed; they should reflect
the importance of the functions and
economic roles of many classes of build-
ings, and building codes should be re-
vised—and, optimally, simplified—to
achieve these objectives. A "California
Earthquake Risk Colloquium," an ad hoc
task force representing the various busi-
ness, government, emergency manage-
ment, health and social services, and public
safety interests that could contribute
should be convened by the Commission
and charged with recommending an
appropriate state policy on acceptable
earthquake risk.
Provide incentives for risk reduction. Interest
in improving earthquake risk -reduction
efforts --and the willingness to spend money
on them—disappears quickly after each
damaging earthquake. Permanent financial
and other incentives need to be developed
that will keep the level of interest high
enough to make sure that risk reduction is
carried out over the long term. Such risk
reduction helps more people than just the
building owners; the whole community
benefits from a more predictable business
climate, quicker earthquake recovery, and
enhanced public safety.
Even if building owners are aware of the
seismic hazards of their buildings and want
to address them, they are often hard
E x e c. a i i u e S u m m a. > y
pressed to obtain the resources needed.. And
it is difficult, whether at the state or local
government level, to provide financial
incentives. The private sector can help by
adjusting interest rates and insurance
premiums and deductibles to reflect
seismic risks; government can supply the
information needed to develop these tools
as well as providing grants, loans, and
other incentives for risk reduction.
Improve the use of earth science knowl-
edge to reduce risk. The earth sciences
have developed a great deal of information
about California geology, but much of it is
not in a form that can be used by builders,
local government planners, or state
lawmakers. Accelerating the progress of the
state's Seismic Hazards Mapping Program
would go a long way toward filling this gap.
Improvements in how Uniform Building
Code land -excavation and grading require-
ments are enforced and in continuing
education for earth science professionals
are also needed. Building designers must
do more to take the effects of geologic
conditions and the unique shaking charac-
teristics near faults into account.
Improve the use of land use planning to
manage seismic risk. General plans, zoning
and subdivision regulations, and environ-
mental reviews can provide powerful tools
for reducing and avoiding earthquake risk.
Some relatively minor changes to existing
laws and practices would make these tools
more usable, such as requiring general
plans to incorporate a description of the
building stock and mitigation measures or
incentives to reduce risk from vulnerable
buildings.
Improve the code development process..
The current method of developing building
codes with volunteer efforts has worked
well in the past but has resulted in long,
complicated regulations that are often slow
to recognize new advances. Moreover, no
single organization is accountable for
substantiating the basis underlying the
page xis
ff,ToT,7VT7TrTM N o r t h r i d g e E a r t h q u a k e;
code provisions. The California Building
Standards Commission should be empow-
ered to make improvements in the codes
and in the code development process to
make sure that code assumptions are valid
and that design guidelines will meet
performance objectives. More active state
government support for developing
building codes will have long-term impacts
on the earthquake resistance of California
buildings.
Support focused research. The more
California learns about earthquake mecha-
nisms and damage, the better prepared we
become. However, there are many critical
aspects as yet unanswered. Where are the
buried faults, and what kinds of earth-
quakes will they cause? How can damaged
steel -frame buildings be repaired, and how
can that kind of damage be prevented?
"'hat are appropriate guidelines for
evaluating seismic performance? What are
the true strengths of commonly used
building hardware? Without focused
research California will continue to invest
billions in improvements that are not
necessarily reliable during earthquakes
California needs answers to these questions
more urgently than any other state. The
state should amend existing statutes to
create and fund the Center for Earthquake
Risk Reduction, an entity to plan for and
fund focused research to develop answers
to such practical questions so they can be
applied to reduce earthquake risks. The
page s i
r a r n 7 n g L a s s t o G a i n
center would emphasize measures to
ensure that research results are actually
put to use by practitioners.
• Improve state -level programs. Resources,
authority, responsibility—these are the key
elements for making state seismic safety
activities effective. State agencies that have
seismic safety responsibilities must make
them an important part of their mission,
not just an afterthought; plans and sched-
ules for implementation of these responsi-
bilities should be a part of every budget
request. State agencies and California's
university systems must forecast the
damage and disruption that will be caused
by likely earthquake events and plan to
reduce these effects.
The Commission believes that its role in
carrying out California's earthquake risk -
reduction programs should continue to be
independent and advisory. Its unique perspec-
tive in considering all aspects of earthquake
risk reduction, response, and recovery will
help it identify those actions most likely to be
effective in turning the lessons from earth-
quake losses to California's gain,
The Northridge earthquake lends new urgency
to the need to carry out the initiatives in
California at Risk, the outline of the California
Earthquake Hazard Reduction Program, It is
imperative that adequate funding be provided
to meet the state's goal of reducing earthquake
risk significantly by the end of this century.
Summary of
Los Angeles County Building Code Amendments
The following is a summary of the areas or provisions of the Los Angeles County Building Code
which have been amended following the 1994 Northridge Earthquake.
1. Increases the anchorage requirements of concrete and masonry walls to plywood roofs.
2. Increases the design requirements for plywood diaphragms.
3. Increases the design requirements for concrete frame buildings.
4. Increases the design requirements for steel moment connections.
5. Changes the design approach to wood frame buildings by requiring deflection to be
calculated.
6. Amends design values for wood frame construction, such as plywood strength, connection
hardware strength, and anchor bolt values.
7. Amends conventional construction requirements to increase earthquake resisting
elements.
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