Overview

SER-TONG QUEK ^[*] , XIANG-YUAN ZHENG ^{[ ]} and CHIH-YOUNG LIAW ^{[ ]}
Department of Civil Engineering, National University of Singapore
117576, Singapore

This chapter focuses are on two frequency-domain methods to estimate the stochastic response of fixed offshore structures. The sources of nonlinearity including that due to drag and waves that lead to complexity in stochastic analyses are discussed. Both the Volterra series and cumulant spectral approaches are presented where the drag-related wave forces (including that due to inundation) are polynomialized into zero-memory processes. It is shown that up to fourth-order statistical moments of the response can be computed and in good agreement with values estimated from time domain simulations and the response is found to deviate significantly from Gaussianity.