Risk Analysis of Coastal
Structures
The coastal infrastructure in the USA is aging. Inspection, repair, and rehabilitation of
Description
existing structures represent a large part of coastal rubble-mound work within the USACE
while new construction of this class of structure represents a
diminishing fraction of the projects. The cost of maintaining
the existing coastal rubble-mound infrastructure is expensive.
One present focus on reducing the cost is by employing risk,
life-cycle, and reliability analysis techniques in both planning
and design studies in order to develop more efficient designs
which focus on life-cycle efficiency as opposed to the
historical perspective of "no damage" for the design storm.
Accurate life-cycle analyses (LCA) are required in order to
Issue
establish funding priorities for planning, design, and
maintenance of these structures. Predicting damage rates
over the entire life cycle is central to any LCA and damage
formulas have not historically been available. Because both
Corps personnel and Corps contractors do not have
standardized methods for LCA for new structure design or
for maintenance evaluation for existing structures, the
uncertainty in such an analysis is unnecessarily high and
Repair of North jetty tip at
unpredictable.
Yaquina, Oregon
District Engineers, Planners, and Engineering Consultants
Users
involved with rubble mound design.
Initial products from this research effort have included personal computer programs for
Products
predicting the reliability and the life cycle response of rubble mound structures. A new
reliability prediction tool for coastal structures called RELIABLE was developed and
incorporated into the program CEDAS. Two new computer programs called
LC_COST_REV and LC_COST_BW were developed for prediction of life cycle costs of
revetments and breakwaters, respectively. The programs use the historical time history of
waves and water levels to develop recommended lest cost design cross sections for
revetments and breakwaters.
These design tools provide a significant improvement in the Corps' ability to predict life-
Benefits
cycle costs of coastal rubble mound structures. The products have already been applied
two Corps projects resulting in actual savings of over
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M. The impact of the application
of this new technology is improved planning for Operations and Maintenance and, as a
result, improved structural performance. This results in better coastal protection and safer
navigation channels and harbors. These products will be enhanced during this research
and distributed through Corps publications, classes, and workshops.
Navigation Systems R&D Program
Corps Program
Dr. Jeffrey A. Melby, U.S. Army Engineer Research and Development Center,
Point of Contact
ATTN: CEERD-HN-H, 3909 Halls Ferry Road, Vicksburg, MS 39180-6199;
e-mail: . Additional information can be
U.S. Army Engineer Research and Development Center
December 2004
Coastal and Hydraulics Laboratory (Research)
www.erdc.usace.army.mil
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