Seismic Safety Technology and Regulations: A Look at the Near Future (Summary of a Symposium) (1992)

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DEVELOPMENT OF SEISMIC DESIGN AND CONSTRUCTION STANDARDS FOR LIFELINES James D. Cooper1 Federal Highway Administration and Robert D. Dikkers2 National Institute of Standards and Technology 1. INTRODUCTION Lifelines are defined as those utilities, facilities, and structures that are required to function following an earthquake to facilitate search and rescue, provide emergency services, allow for the movement of goods and materials and form a network which is required for post event reconstruction. Electric power and communications, gas and liquid fuel, transportation and water and sewer systems form today's modern lifeline network. Each lifeline is comprised of numerous components, some of which are critically vulnerable to earthquake induced damage and whose loss of function renders the lifeline useless. For example, a break in a major gas, oil, or water transmission pipeline can cause system failure. However, a break in a gas or water service line may eliminate service to a very local area only. In either case, failure may induce secondary problems such as fire caused by escaping gas from a broken pipe or the inability to control fires because of a broken water pipe. Increased attention was focused on the lifeline problem following the 1971 San Fernando earthquake. Since then, numerous post earthquake investigations have been made and damage assessment reports prepared documenting the performance of lifelines. Basic research is providing engineers an understanding of how and why components of lifelines perform the way they do. Yet little has ben published in the open literature to provide detailed guidance for the design and construction of lifelines to resist strong ground shaking. The design and construction of integrated lifelines involves the application of multidisciplinary topics and experience gained from previous earthquakes where weaknesses in design, construction, system architecture, and management have been 'Deputy Chief, Structures Division, Federal Highway Administration, McLean, Virginia 2Group Leader, Structures Evaluation, Building and Fire Research Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 16

highlighted. The performance and reliability of lifelines can affect a broad geopolitical area requiring the involvement of community leaders, public officials and the private sector to mitigate damaging effects. Pre-earthquake considerations include the identification of expected variations in earthquake intensity, engineering factors, and policies influencing risk and reliability. The planning process for each lifeline system will significantly influence the expected outcome of the effects of a seismic event. The process includes an understanding of the geologic factors that produce the seismic intensity levels that cause structural damage and ground failure. This knowledge supports systematic evaluation of hazards and risks required for planning reliability needed to mitigate earthquake damage. The easiest, most cost-effective way in which to mitigate seismically induced damage is to upgrade seismic design and construction procedure for new construction. This approach will take decades to enhance the seismic resistance of lifelines, but will ultimately reduce the potential for catastrophic impact in the event of a great earthquake. Limited seismic design procedures and details for lifelines have been developed over the past 20 years. However, some newer structures incorporating these procedures have been exposed to relatively strong earthquakes and have performed quite satisfactorily. Design and construction costs associated with enhanced seismic resistance is still being evaluated. A range of from one to 20 percent increased project costs for upgraded seismic resistance has been suggested and is highly dependent on the level of seismic detailing incorporated into the design. Nonetheless, these costs distributed over time become an inexpensive investment to significantly reduce the sudden loss potential from a great earthquake. A second method to mitigate seismically induced damage is to retrofit existing lifelines. Retrofit is typically much more costly than planning in advance for the seismic design of new construction. However, retrofit can be cost-effective even in regions outside of the traditionally thought of seismically active zones. For example, if potentially vulnerable transportation routes are identified, a large number of bridges along these critical routes could be "restrained" at low cost. Since this retrofit technique typically cost between 10 and 20 thousand dollars per bridge, 150 bridges could be retrofit for the approximate cost of one structure! For other types of lifelines, retrofit may not be cost- effective except in unusual circumstances. Retrofit details and designs are becoming more common in traditional seismically active areas, although retrofit is not yet a generally accepted policy in these areas. 2. EARTHQUAKE HAZARDS REDUCTION ACT OF 1977 In 1977, the Congress of the United States enacted the Earthquake Hazard Reduction Act of 1977 to reduce risks of life and property from future earthquakes. This act forms the basis for the formation of the National Earthquake Hazards Reduction Program (NEHRP). Several specific objectives cited in the NEHRP include the charge to develop seismic design and construction standards for Federal use; develop guides for facilities that are Federally owned, constructed or financed to ensure serviceability following an earthquake and coordinate the development of guides for the consideration of seismic risk in the development of Federal lands. In 1978, the Interagency Committee on Seismic Safety in Construction (ICSSC) was established as part of the NEHRP to assist Federal departments and agencies 17

involved in construction to develop earthquake hazard reduction measures for incorporation in their ongoing programs. The measures will be based on existing standards when feasible. In meeting its responsibilities, the ICSSC cooperates with State and local governments and private organizations in developing nationally applicable earthquake hazard reduction measures. Five subcommittees of the ICSSC are responsible for responding to the charge contained in the NEHRP: 1. Standards for New and Existing Buildings 2. Lifelines 3. Evaluation of Site Hazards 4. Federal Domestic Assistance, Leasing and Regulatory Programs 5. Post Earthquake Response Investigations The mission of the Lifelines Subcommittee is to identify existing guidelines or standards for seismic design, construction and retrofit of energy, transportation, water, and telecommunication systems; to recommend Federal adoption of such standards when found adequate; and to encourage development of new standards where there are significant omissions. The Subcommittee will also study techniques for evaluating the seismic vulnerability of existing lifelines and for improving their resistance to seismic protection for ease of repair. The Lifelines Subcommittee is also considering strategies that will permit identification of those lifelines facilities important in the emergency, immediate recovery, and long-term economic recovery periods, and provide guidance for appropriate levels of seismic protection for each type. 3. NEHRP REAUTHORIZATION ACT OF 1990 Section 8(b) of the National Earthquake Hazards Reduction Program Reauthorization Act, Public Law 101-614, which was approved on November 6, 1990 requires the Director of the Federal Emergency Management Agency (FEMA), in consultation with the National Institute of Standards and Technology (NIST), to submit to the U.S. Congress, not later than June 30, 1991, a plan, including precise timetables and budget estimates, for developing and adopting, in consultation with appropriate private sector organizations, design and construction standards for lifelines. The plan is also required to include recommendations of ways Federal regulatory authority could be used to expedite the implementation of such standards. 4. FUTURE LIFELINE DESIGN STANDARDS The overall lifelines standards plan development process presently being implemented has been established with the advice of a Steering Group organized by FEMA. The Group, chaired by Dr. Ronald Eguchi, Chairman, ASCE Technical Council on Lifeline Earthquake Engineering (ASCE TCLEE), includes representatives from FEMA, NIST, Department of Energy, Federal Energy Regulatory Commission, National Center for Earthquake Engineering Research (NCEER), Interagency Committee on 18

Seismic Safety in Construction and several members from various private sector organizations. During its first meeting in March, 1991, the Steering Group approved a strategy for the lifelines standards development process. The strategy included using lifelines experts to prepare and review draft plans for the development of design and construction standards for the various lifeline systems. The experts identified by the Steering Group and selected to author the draft plans are: • Water and Sewer Systems-Mr. Donald Ballantyne, Kennedy/ Jenks/Chilton, Federal Way, Washington. • Transportation Systems--Dr. Ian Buckle, NCEER, Buffalo, New York. • Gas and Liquid Fuel Systems—Dr. Douglas Nyman, D. J. Nyman and Associates, Houston, Texas. • Electrical Power Systems—Dr. Anshel Schiff, Stanford University, Palo Alto, California. • Telecommunication Systems—Mr. Alex Tang, Northern Telecom Canada Ltd., Ontario, Canada. • Federal Implementation and Other Issues-Mr. Crane Miller, Attorney, Washington, D.C. In each of the above areas, five expert reviewers have also been identified and selected. These individuals reviewed the draft plans and participated in a discussion of the plans at a workshop held in Denver, Colorado, on September 25-27, 1991. Approximately 85 percent of the key individuals involved in the plan development process described above are active in the ASCE TCLEE. In general, the plan will include the following information for the various lifeline system categories: seismic vulnerability; current design and construction practices and standards; available knowledge to improve existing practices; recommended standards to be developed for new and existing construction; and recommended research to fill identified knowledge gaps. It will also contain recommended timetables and budget estimates and recommendations of ways Federal regulatory authority could be used to expedite the implementation of such standards. The current scheduled completion date for the final draft lifelines standards development plan is January 1, 1992. After this date, the plan will be submitted by FEMA to the Office of Management and Budget for review prior to its submission to the U.S. Congress not later than June 30, 1992. 5. CONCLUSION Although significant attention has been focused on the efforts earthquakes have on lifelines in recent times, relatively little guidance is available for the seismic resistant design and retrofit of these facilities. Clearly the intent of the Congress is to focus attention on the need to adopt existing standards where appropriate and develop new standards where appropriate and feasible to enhance the seismic resistance of Federal and private lifeline structures. In so doing, it is critically important to involve both the public and private sectors in the process. Federal agencies, acting through the ICSSC, 19

academia, trade and professional associations are being called upon to collaborate in the development and implementation of reasonable, technically feasible, economically justifiable standards for lifelines. 20