Civil Engineering ETDs

Publication Date



Environmental contours describing extreme sea states are generated as the input for numerical or physical model simulations as a part of the standard current practice for designing marine structures to survive extreme sea states. Such environmental contours are characterized by combinations of significant wave height (Hs) and energy period (Te) or peak period (Tp) values calculated for a given recurrence interval using a set of data based on hindcast simulations or buoy observations over a sufficient period of record. The use of the inverse first-order reliability method (I-FORM) is standard design practice for generating environmental contours. This thesis develops enhanced methodologies for data analysis prior to the application of the I-FORM, including the use of principal component analysis (PCA) to create an uncorrelated representation of the variables under consideration as well as new distribution and parameter fitting techniques. These modifications are shown to contribute to the development of more accurate and reasonable representations of extreme sea states for use in survivability analysis for marine structures.


Inverse FORM, Principal Component Analysis, Environmental Contours, Extreme Sea State Characterization


This research was made possible by support from the U.S. Department of Energys (DOE) Energy Efficiency and Renewable Energy (EERE) Office's Wind and Water Power Technologies Office. This work was conducted at Sandia National Laboratories, a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.'

Document Type




Degree Name

Civil Engineering

Level of Degree


Department Name

Civil Engineering

First Advisor

Stone, Mark

First Committee Member (Chair)

Coonrod, Julie

Second Committee Member

Neary, Vincent

Third Committee Member