Generalized Estimation of Wave Force Spectra

Abstract

A generalized approach is presented to estimate the crossspectral densities of the wave forces exerted on cylindrical members of offshore structures. The structural members are assumed to be inclined in space and subjected to a multidirectional wave attack. It is shown that all possible interspectral combinations of the forces can be obtained based upon the surface spectrum and rms particle velocity. Another generalized theoretical development is also presented to obtain the estimates of the wave force coefficients for the inclined cylindrical members placed in multidirectional waves. This technique is based upon the principle of comparing the observed cross‐spectral densities with their theoretical estimates; it gives the frequency‐dependent estimates along different coordinate directions. A practical application of these theoretical developments to the available field data is also discussed.