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Seismic Risk Mitigation for Port Systems

Principal Investigator: Glenn Rix, Georgia Institute of Technology

Earthquakes pose a significant threat to many large U.S. seaports which serve as crucial gateways for international trade. Forty percent of the value of U.S. international trade passes through these ports, more than any other mode (Bureau of Transportation Statistics, 2004). Maritime trade value has nearly doubled in the last decade, from $434 billion in 1990 to $811 billion in 2003, and will likely increase further given the expected growth in trade with Asia and Pacific-Rim nations.

Current engineering practice for seismic risk reduction for port facilities is typically based on design or retrofit criteria for individual physical components (e.g., wharf structures) expressed in terms of arbitrary levels of force and/or displacement. However, the viability of a port following an earthquake depends not only on the performance of these individual components, but on their locations, redundancy, and physical and operational connectivity as well ­ that is, on the port system as a whole. This Grand Challenge research program uses the performance of the port system and associated uncertainties as the basis for seismic risk mitigation decisions. Thus, if overall port system performance is defined in terms of a minimum desired level of port-wide cargo handling capacity after an earthquake, wharf and crane structures whose operating capacity is determined to be critical for meeting this system performance requirement may be designed or upgraded to a more stringent level than other port components. This holistic approach allows limited resources to be used more wisely. Formulating system-wide performance goals effectively requires collaborative participation from a broad range of port stakeholders who are likely to differ in their understanding of the risks (e.g., life safety, economic, environmental, political, legal, and psychological) posed by an earthquake or other disasters. While ports pose unique seismic risk research and management challenges, the approach developed in this research program is relevant to other civil infrastructure systems as well as other natural and man-made hazards. The research program includes the following tasks and goals:

  1. using NEES resources to perform hybrid experimental and numerical simulations of the soilfoundation-structure systems characteristic of ports to improve understanding of the physical interaction between soil, foundation and structure, and to develop geotechnical and structural mitigation and repair strategies and computational tools. These advances will radically improve design methodologies transferable to engineering practice
  2. developing real-time operational models for ports that will provide decision support during irregular operations and parametric descriptive models of port system performance that can be readily incorporated within a risk mitigation decision framework
  3. using enterprise risk modeling criteria such as second-order stochastic dominance to evaluate benefits and costs of risk mitigation alternatives, which have highly skewed distributions
  4. developing and applying formal stakeholder participation, decision and risk research to define port system performance goals and routes to achieving them, addressing both the science and perceptions of seismic hazards and other potentially catastrophic risks
  5. developing education, outreach, and training programs are designed to accelerate technology transfer and increase the diversity of the workforce involved in natural and man-made hazards mitigation
Because of their unique physical infrastructure, long-range planning horizon, complex operational structure, and local authority, ports have seismic risk issues not encountered in other types of facilities and infrastructure systems. As a result, seismic risk mitigation at ports has received relatively little attention. The proposed tasks address these issues and will help safeguard the nation's ports and the communities and business interests that depend on them against losses due to earthquakes and other natural and man-made hazards. Moreover, the broad range of technical research issues addressed in this program, including liquefaction remediation, soil-structure interaction, and structural response are considered to be the most challenging and timely in the field of earthquake engineering (NRC, 2003).