The National Earthquake Hazards Reduction Program:
Past, Present, and Future
Hearing of
the
Subcommittee on Research
Committee on
Science
U.S. House of Representatives
Thursday, May 8,
2003
Written Testimony
Submitted
By
Dr. S. Shyam Sunder
Chief, Materials and Construction
Research Division
Building and Fire Research
Laboratory
National Institute of Standards and
Technology
Introduction
As a representative of one of the four primary
federal agencies that comprise the National Earthquake Hazards Reduction Program
(NEHRP), I congratulate the earthquake community and our three partners – the
Federal Emergency Management Agency as lead, the United States Geological
Survey, and the National Science Foundation – as we celebrate the 25th
anniversary of the founding of NEHRP.
NEHRP has been an extraordinary,
and often exemplary, collaboration between federal agencies, state and local
governments, and the private sector.
During its first 25 years, NEHRP has
contributed in very significant ways to reduce our nation’s vulnerability to
earthquakes and NIST is proud to have been a part of that record of
accomplishment.
While it is difficult to quantify loss prevention
through the adoption of improved mitigation practices, and such measures are
very much needed, there is no doubt that NEHRP products and results have
contributed in significant ways to reduce the loss of life and economic losses
from earthquakes. In addition, the loss of life from earthquakes in the
United States has been small compared with similar earthquakes in other
countries.
My testimony traces how NIST has contributed to the success of
NEHRP. It also reflects upon the broader public safety challenges the
nation now faces and how NEHRP can contribute to meeting those
challenges.
Earthquakes and Creation of NEHRP
Earthquakes
are among the most frightening and devastating natural disasters. They
strike virtually without warning, last only seconds, but can leave death and
destruction in their wake.
Seventy-five million Americans in 39 states
face significant risk from earthquakes. On an annualized basis,
earthquake losses amount to about $4 billion a year, while a single earthquake
has a loss potential of $100 billion or more.
For example, the
1971 San Fernando earthquake in California killed 65 people and caused $500
million in damage. The 1994 Northridge earthquake caused losses in excess of $40
billion, with $15 billion in insured property losses alone.
The San
Fernando earthquake led Congress to pass the Earthquake Hazards Reduction Act of
1977 to “reduce the risks of life and property from future earthquakes in the
United States through the establishment and maintenance of an effective
earthquake hazards reduction program.” Pursuant to the Act, the Executive
Office of the President developed the National Earthquake Hazards Reduction
Program and issued a program plan in June 1978.
Pre-NEHRP
Efforts
Prior to the creation of NEHRP, NIST and many other
government, private-sector organizations and universities were conducting
research on ways to improve the seismic design of constructed facilities.
NIST began work in earthquake hazards reduction with its
organization in 1969 of the U.S.-Japan Panel on Wind and Seismic Effects under
the U.S.-Japan Program in Natural Resources. This successful bi-lateral
program continues to this day, with the 35th annual meeting slated to be held
next May.
NIST work also included its significant investigation of
the performance of structures in the 1971 San Fernando, California, earthquake.
Also, in 1972, the Applied Technology Council, an organization
created by the Structural Engineers Association of California, called for a
cooperative effort of practice, research, and government to produce up-to-date
seismic design and construction provisions. A subsequent ATC study
completed in 1978 produced design provisions that were a significant advance on
existing provisions.
Role Assigned for NIST in NEHRP
NIST
was a natural part of NEHRP because of its long-time role in providing
measurements, standards, and technology to help federal, state, and local
government agencies and the private sector protect the nation and its citizens
from natural as well as manmade threats.
As part of NEHRP, NIST took on
three assignments:
• First, to develop seismic design
and construction standards for consideration and subsequent adoption in federal
construction, and encourage the adoption of improved seismic provisions in state
and local building codes;
• Second, to assist and
cooperate with federal, state, and local agencies, research and professional
organizations, model code groups and others that are involved in developing,
testing, and improving seismic design and construction provisions to be
incorporated into local codes, standards, and practices;
and
• Third, to conduct research on performance
criteria and supporting measurement technology for earthquake resistant
construction.
In addition, as part of the USGS-led Post-Earthquake
Investigation Program established by the NEHRP Reauthorization Act of 1990, NIST
took on another assignment:
• Fourth, to participate in
NEHRP post-earthquake investigations and analyze the behavior of structures and
lifelines, both those that were damaged and those that were undamaged, and to
analyze the effectiveness of the earthquake hazards mitigation programs and
actions and how those programs and actions could be
strengthened.
Products and Results from NIST’s Problem-Focused
R&D
Through laboratory based problem-focused R&D NIST has
made important contributions to earthquake safety over the years. Examples
include our products and results related to:
• bridge
column reinforcing requirements,
• rehabilitation of
welded steel moment frame connections,
• test methods for
passive and active seismic energy absorption systems, and
•
precast concrete frames.
One example is our work with industry and
others on precast concrete frames (Attachment A provides summaries of the other
examples).
While construction with this type of frame has not been
extensive in high seismic regions of the United States, it has enormous benefits
in construction speed and quality control.
In 1987, NIST initiated a
project to develop a precast beam-to-column connection that was economical, easy
to construct, and capable of resisting earthquake loads. A few years
later, Pankow Builders, a California general contracting firm specializing in
quake-resistant construction, provided funding through the American Concrete
Institute (ACI) to further develop the concept. Close collaboration among
NIST, Pankow Builders, and the University of Washington resulted in a hybrid
connection that combined the use of low-strength reinforcing steel for energy
absorption with high-strength prestressing steel.
Tests at NIST
and on a five-story precast building at the University of California at San
Diego demonstrated that the concept worked. NIST-developed guidelines and
results were used to obtain approval from a code evaluation service. In
addition, the American Concrete Institute issued standards and the International
Building Code has adopted provisions that allow use of the system.
Recently, Pankow Builders used the hybrid connection to build a
$128-million, 39-story building in San Francisco. Topped out in June 2001,
the building is the tallest concrete frame building built in a high seismic
region.
Several other structures using the hybrid connection have
been built, are underway, or on the drawing board.
We are very proud of
our collaboration with Pankow Builders, the University of Washington and others
and are gratified that this design innovation and the contributions of its
developers have been widely recognized. This work has won numerous awards,
most recently the Harry H. Edwards Industry Advancement Award of the
Precast/Prestressed Concrete Institute.
Lessons Learned from NIST’s
Post-Earthquake Investigations
Throughout its history, NIST
scientists and engineers have been called in to investigate building failures
following fires, earthquakes, high winds, terrorist attacks, construction
accidents, and other events.
Tragically, we learn many lessons following
an earthquake about what type of design and construction works and what does
not. Our goal is to investigate and document building performance and the
adequacy of current codes and practices, as well as to identify research needed
to mitigate the impact of future earthquakes.
Our investigators have
traveled not only to earthquake sites in the United States, including the Loma
Prieta earthquake in 1989 and the Northridge earthquake in 1994, but also to
those places around the world including Japan, Romania, Nicaragua, Mexico,
Armenia, and – most recently – Turkey. The investigation following the
1999 earthquake in Turkey was a cooperative effort led by the USGS, with
participation of the U.S. Army Corps of Engineers.
Since NIST is not a
regulatory agency and does not issue building standards or codes, the institute
is viewed as a neutral, “third-party” investigator. Our investigations are
fact-finding, not fault finding. The focus is on improving public safety
and on deriving lessons for the future. And, by law, the data, analysis,
and reports resulting from NIST investigations may not be used in
litigation.
Formation of ICSSC and Federal Construction
One
of the early accomplishments of NEHRP was to involve federal agencies with
construction responsibilities. Federally-constructed facilities comprise
one of our nation’s largest building sectors. It was realized early in the
NEHRP that it was vital to assist the more than 30 federal agencies that are
involved in one way or another in construction to implement earthquake hazards
reduction elements into their ongoing programs.
In 1978, the White
House directed the Federal Emergency Management Agency to form an Interagency
Committee on Seismic Safety in Construction (ICSSC). ICSSC was assigned to
develop and implement seismic deign standards for federal construction.
NIST, with funding from FEMA, has provided the secretariat for ICSSC since its
inception, and the Director of NIST (or the Director’s designee) has chaired the
ICSSC since 1982.
Not only did the ICSSC provide up-to-date seismic
design and construction standards and practices that federal agencies used for
their own new buildings, but it had a broader effect as well. An executive
order issued by the President in 1990 required both federal and
federally-assisted homes, such as new homes with FHA or VA mortgages, be
designed and constructed using these standards.
This federal mandate was
welcomed by the national standards and model building code organizations since
it provided incentive for state and local governments to adopt and enforce
up-to-date standards and codes to be eligible for federally-assisted
construction.
The bottom line result was that NEHRP’s broad
goal of making adequate seismic resistance available for all new U.S. building
construction was achieved. This successful outcome would not have been
realized without a NIST study that was crucial to the issuance of the executive
order. That study revealed the modest cost implications of the recommended
seismic provisions as determined by trial designs.
ICSSC was much
involved in support to federal agencies in implementation of the executive order
for new buildings. It continues today to provide support for the
assessment of the equivalency of model building codes to the NEHRP recommended
provisions – the most recent assessment was issued in late 2001 – and the
development of proposed changes to model codes.
The ICSSC turned next to
the challenge of evaluating and strengthening existing buildings by developing
seismic safety standards and assisting federal agencies in implementing a second
executive order. That executive order called for agencies to inventory
buildings they own or lease and estimate the costs of mitigating unacceptable
seismic risks.
The ICSSC developed policies and practices
for evaluation and strengthening of existing federal buildings. This
included seismic safety standards for existing buildings, which were updated
recently; guidance to the federal agencies on implementation of the executive
order; assistance with estimating the costs of mitigating unacceptable seismic
risks; and extensive review and comment in drafting the resulting
report.
Currently, ICSSC is developing a handbook for the seismic
rehabilitation of existing buildings. This handbook will facilitate
implementation of the seismic rehabilitation plan for federal buildings when a
policy decision is made to proceed.
Major Challenges for the
Future
NEHRP has come a long way. But, it faces many challenges
in meeting its legislative mandate to “reduce the risks of life and property
from future earthquakes in the United States.”
Four of the key
challenges faced by NEHRP are to:
• fill the technology
transfer gap between basic research and practice,
•
develop and implement seismic safety standards for lifelines,
• develop and implement a multi-hazard approach to risk
mitigation, and
• better coordinate post-earthquake
investigations.
Challenge #1: Filling the Basic Research to
Practice Gap in Earthquake Engineering
Just as NEHRP strives
for better ways to improve the performance of construction during an earthquake,
NIST and its three NEHRP partners are continually looking for better ways to
carry out our mission.
Early in 2001, a NEHRP Strategic Plan was
approved by each of the four participating agencies. This plan, developed
in partnership with stakeholders, has identified the emergence of a technology
transfer gap that limits the adaptation of basic research knowledge into
practice. The plan recommends a much-expanded problem-focused research and
guidelines development effort:
• to develop future design,
construction, evaluation, and upgrade guidelines and standards of practice, and
• to facilitate the development of new mitigation
technologies.
It further recommends that NIST, in partnership with FEMA and
other NEHRP agencies, should develop a coordinated plan to support this effort.
NIST looks forward to working with its NEHRP agency partners and
with industry, academia, and the broader stakeholder community to address this
gap.
As a first step, NIST requested the Applied Technology
Council, a non-profit corporation to advance engineering applications for
natural hazard mitigation, to convene a workshop of national leaders in
earthquake design, practice, regulation, and construction in July of
2002.
The purpose of the meeting was to assess the state of knowledge and
practice and to suggest an action plan to address the gap between basic research
and practice.
Recently completed, the action plan identifies industry
priorities in two areas:
• support for the seismic code
development process through technical assistance and development of the
technical basis for performance standards; and
• improved
seismic design productivity through the development of tools and guidance and
evaluation of advanced technologies and practices.
This action
plan fits within the broader research and outreach plan developed by the
Earthquake Engineering Research Institute titled “Securing Society Against
Catastrophic Earthquake Losses.” It also incorporates issues raised under
Challenge #2 below.
NIST now looks forward to working with the
stakeholder community to explore ways to best meet those needs via a
public-private partnership. We expect this effort will build on NSF-funded
basic academic research, including that conducted as part of the George E.
Brown, Jr. Network for Earthquake Engineering Simulation (NEES)
Consortium.
Challenge #2: Developing and Implementing Seismic
Safety Standards for Lifelines
While up- to-date seismic
provisions for building codes are available today, there are no nationally
accepted standards or guidelines for lifelines, except for highway structures
and nuclear facilities.
Lifelines include all types of
transportation (highways, airports, railways, waterways, ports and harbors),
communication, and utility (electric power, gas and liquid fuels, water and
wastewater) systems. They provide the physical infrastructure that support
most human activities.
The American Lifelines Alliance, with support from
FEMA, is working on the development of guidelines and standards for
lifelines. Concurrently, the ICSSC has completed an initial survey of
lifelines that are the responsibility of federal agencies. It has begun a
major effort to identify the needs for standards and guidance for these
lifelines, with an initial focus on electric power generation, transmission, and
distribution facilities. It is anticipated that implementation of the
lifelines plan would be primarily through the existing voluntary standards
system with a possible executive order requiring agencies to adopt and use the
standards for federal lifelines.
While these initial public and
private sector efforts are laudable, I believe NEHRP has much work to do before
the nation will have seismic standards and guidelines for lifelines similar to
those we already have for new and existing buildings.
Challenge #3:
Developing and Implementing a Multi-Hazard Approach to Risk
Mitigation
Seismic hazards are one of many significant hazards that
must be considered in design and construction. From the viewpoint of an
owner or end-user, a multi-hazard approach to risk mitigation is desirable since
it likely will yield more cost-effective solutions. This is especially
true for existing construction, where seismic retrofit investments may be better
justified when made in conjunction with needed functional and security
upgrades.
A careful consideration of regional hazards such as earthquakes
and high winds shows that these hazards pose a major risk since they coincide
with geographical areas that have seen significant population growth and
development in recent years. The risks from fire hazards are spread across
the nation, while the risks from terrorist or technological threats are limited
to certain critical facilities or locations.
In comparison with the $4
billion annualized loss estimate for earthquakes, the annualized loss estimate
for extreme winds is about $8 B/year and for fire hazards is about $12 billion a
year. Similarly, in comparison with the $100 billion loss potential for a
major earthquake, a single hurricane event has a loss potential of as much as
$50 billion. Major earthquakes, high winds, and other extreme hazards have
one thing in common – they are all low probability, high consequence
events.
There is significant merit to multi-hazard risk mitigation if
practicable tools, practices, and guidance can be developed. Examples
include:
• improving overall structural integrity by
mitigating progressive collapse, where NIST is already working with the private
sector to develop needed tools and guidance;
• conducting
multi-hazard vulnerability assessments using an integrated framework based on
standard information representation models and interoperable software tools;
and
• evaluating the cost-effectiveness of alternate risk
reduction technologies and strategies using integrated software tools for making
cost-risk trade-offs.
I believe NEHRP has a unique opportunity to provide
national leadership in charting the course for a multi-hazard approach to risk
mitigation, while continuing with its important risk reduction mission for
earthquakes. The development of the HAZUS regional loss estimation model –
that now covers earthquakes, wind, and floods – is an excellent example of how
NEHRP has already demonstrated this kind of leadership.
Challenge
#4: Coordinating Post-Earthquake Investigations
NEHRP
has long supported post-earthquake investigations, and in 1990 Congress
specifically authorized the establishment of a coordinated program to conduct
such investigations with leadership to be provided by the United States
Geological Survey. Consistent with this legislation and the recent NEHRP
Strategic Plan, an implementation plan has been completed to coordinate future
post-earthquake investigations.
In the aftermath of the World Trade
Center disaster, Congress has given NIST additional authorities – beyond those
NIST already had – through the National Construction Safety Team Act. The
legislation, which is modeled in many ways on the National Transportation Safety
Board, was introduced by the House Science Committee and signed into law by
President Bush on October 1, 2002.
That law, Public Law 107-231,
established NIST as the lead agency to investigate building performance,
emergency response, and evacuation procedures in the wake of building failures
that result in substantial loss of life or that posed significant potential of
substantial loss of life. Currently, NIST is conducting two major
investigations: a building and fire safety investigation of the September 11,
2001, World Trade Center building collapses; and the February 20, 2003, fire at
The Station nightclub in West Warwick, R.I. The act calls for NIST to
establish investigative teams including public and private-sector
experts.
NIST is developing agreements for future investigations with
other federal agencies, and with the private sector so that we can quickly and
effectively deploy investigation teams and so that we can share the results of
those investigations and related research.
The National Construction
Safety Team Act gives NIST the authority to dispatch teams of experts within 48
hours when practicable. The law gives the teams a clear authority
to:
• Establish the likely technical cause of building
failures;
• Evaluate the technical aspects of procedures
used for evacuation and emergency response;
• Recommend
specific changes to building codes, standards and practices;
•
Recommend any research or other appropriate actions needed to improve the
structural safety of buildings, and/or changes in emergency response and
evacuation procedures; and
• Make final recommendations
within 90 days of completing an investigation.
The act gives NIST and its
investigation teams comprehensive authorities to:
• Access
the site of a building disaster;
• Subpoena
evidence;
• Access key pieces of evidence such as records
and documents, and
• Move and preserve
evidence.
Congress anticipated the NCST Act to be applicable to building
failures caused by earthquakes. The Act specifies that the NIST Director
develop implementing procedures that “provide for coordination with Federal,
State, and local entities that may sponsor research on investigations of
building failures, including research conducted under the Earthquake Hazards
Reduction Act of 1977.” In addition, the Committee Report 107-530
published by the House Science Committee on June 25, 2002, states that “The
Director should clearly define how earthquake researchers and Teams will carry
out their responsibilities in a coordinated fashion in cases where building
failures have been caused by an earthquake.”
NIST’s responsibilities
under the NSCT Act have been incorporated in the recently completed plan to
coordinate post-earthquake investigations issued by the four agencies comprising
the National Earthquake Hazards Reduction Program. The plan (USGS circular
#1242) states that, within 48 hours, NIST will examine the relevant factors
associated with building failures that occur as a result of the earthquake and
will make reasonable efforts to consult with the other NEHRP agencies prior to
determining whether to conduct an investigation under the Act. Any NIST
investigation conducted under the authority of the Act will be limited to
building failures on one or more buildings or on one or more class or type of
buildings selected by NIST.
Conclusion
As we look to the
future, I believe NEHRP will continue to play a vital leadership role in making
the performance of our buildings and lifelines highly measurable and
predictable. This measurement and prediction ability will provide the
critical underpinning upon which to achieve specified levels of performance and
seismic risk reduction via workable and practicable solutions. Our nation
will be safer and more secure for it.
We at NIST look forward to
contributing our part to address the challenges that lie ahead.
Attachment A
Products and Results of NIST Problem-Focused
R&D
Bridge Column Reinforcing Requirements
Immediately
following the 1971 San Fernando earthquake, NIST dispatched a team to document
and investigate structural damage caused by the earthquake. In particular,
many bridge columns suffered either significant damage or failure. As a
result, design requirements for bridge columns in seismic zones were
modified. However, the adequacy of these design modifications was not
verified.
NIST initiated a project in the 1980s to provide the
necessary verification, consisting of two full-scale bridge column tests.
The challenges arose from the size of the test specimens and the need to apply
horizontal seismic loads in addition to vertical gravity loads. The series
of column tests was the first of its kind and as such, provided important
benchmark data. The tests also verified the adequacy of the revised design
specifications.
In addition, NIST tested companion 1/6-scale
bridge columns and the results indicated that the behavior of full-scale bridge
columns could be extrapolated from small-scale bridge column tests. This
finding suggests that high costs associated with full-scale tests are not always
necessary and less expensive small-scale tests may be
sufficient.
Welded Steel Moment Frame Connections
Steel
framed buildings traditionally have been considered to be among the most seismic
resistant structural systems. The January 17, 1994, Northridge Earthquake,
however, caused unexpected damage to many welded steel moment frame
buildings. In general, the damage was confined to beam-to-column
connections that suffered brittle fracture in the flange welds.
In
response to these failures, NIST initiated a project to study methods to modify
existing buildings to improve their seismic performance, in collaboration with
the American Institute of Steel Construction, the University of Texas, the
University of California at San Diego, and Lehigh University. Eighteen
full-scale tests were conducted on three different methods to reduce the
stresses at the beam-to-column connections.
The result of this
multi-year effort was the publication of comprehensive guidelines for seismic
rehabilitation of existing welded steel frame buildings as an AISC Design Guide.
The guidelines provided experimentally-validated response prediction models and
design equations for the three connection modification concepts that shift
loading from the welded joints into the beams, thus enabling the structure to
absorb the earthquake’s energy in a non-brittle manner.
Test
Methods for Structural Control Devices
Structural control devices,
such as seismic isolation and passive energy dissipators, have been installed in
numerous structures throughout the world and have proven to be effective in
reducing both motions and forces during earthquakes and strong winds.
Still these devices are generally produced in small quantities, specifically for
each application.
To guarantee that the devices will perform as
the designer expected, many building codes and guidelines recommend that the
devices be tested before installation. While some of these standards
describe a limited number of specific tests, widely accepted test standards do
not yet exist. Such standards are useful to designers, manufacturers, and
contractors, since they will make the process of validating these devices
consistent.
To address the issue NIST has developed two sets of testing
guidelines. The Guidelines for Pre-Qualification, Prototype, and Quality
Control Testing of Seismic Isolation Systems was issued in 1996. ASCE has
developed and is currently balloting a national consensus standard based on the
NIST-developed isolation device testing guidelines.
While seismic
isolation is generally accepted in earthquake engineering practice and
recognized in the building codes in high-seismic areas, passive structural
dampers are still gaining acceptance and semi-active devices are still in the
development phase. NIST has just issued Guidelines for Testing Passive
Energy Dissipation Devices.