Multichannel maximum entropy method of spectral analysis applied to offshore structures

Note: Pages 88-89 do not appear in original document.

The multichannel Maximum Entropy Method (MEM) ofspectral analysis is developed and applied in the dynamicanalysis of offshore structures. Two different algorithms are implemented and compared with the conventionalBlackman-Tukey method. These are (1) a direct on the dataor Burg method and (2) a Yule-Walker or correlation functionextension method. Cross-spectral estimates of magnitude, phase, coherence squared, and transfer function arecalculated. These estimates are then used in mode shapeidentification of a triple decked, single caisson offshoreplatform. The superiority of the multichannel Maximum Entropy Methods relative to conventional spectral analysistechniques in calculating these cross-spectral estimates andevaluating mode shapes is demonstrated.

This research was sponsored by the Branch of Marine Oiland Gas Operations of the United States Geological Survey,Department of the Interior and by the MassachusettsInstitute of Technology/Woods Hole Oceanographic InstitutionJoint Program in Ocean Engineering

Submitted in partial fulfillment of the requirements for the degree of Ocean Engineer at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 1981