Nonlinear system identification in offshore structural reliability

Conference · Sat Dec 31 04:00:00 EST 1994

OSTI ID:55798

Spanos, P D; Lu, R ^[1]

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1. Rice Univ., Houston, TX (United States). Dept. of Mechanical Engineering

Nonlinear forces acting on offshore structures are examined from a system identification perspective. The nonlinearities are induced by ocean waves and may become significant in many situations. They are not necessarily in the form of Morison`s equation. Various wave force models are examined. The force function is either decomposed into a set of base functions or it is expanded in terms of the wave and structural kinematics. The resulting nonlinear system is decomposed into a number of parallel no-memory nonlinear systems, each followed by a finite memory linear system. A conditioning procedure is applied to decouple these linear sub-systems; a frequency domain technique involving autospectra and cross-spectra is employed to identify the linear transfer functions. The structural properties and the force transfer parameters are determined with the aid of the coherence functions. The method is verified using simulated data. It provides a versatile and non-iterative approach for dealing with nonlinear interaction problems encountered in offshore structural analysis and design.

• OSTI ID: 55798
• Report Number(s): CONF-940230--; ISBN 0-7918-1265-0
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
DYNAMIC LOADS
FLUID-STRUCTURE INTERACTIONS
MATHEMATICAL MODELS
OFFSHORE PLATFORMS
RESPONSE FUNCTIONS
TIME-SERIES ANALYSIS
WATER WAVES
WAVE FORCES