Finite Element Modeling of the Response of Long Floating Structures Under Harmonic Excitation

The response of long floating structures to a harmonic excitation is the basis for the response calculation in a short-crested wave field. This paper will present consistent formulas for obtaining the nodal loads in a finite element analysis. The accuracy of the method used is compared with the results obtained using a Rayleigh-Ritz approximation of the response with continuous eigenfunctions. The error of using an irrational finite element model is demonstrated for comparison, and to indicate to designers of similar structures the large effects which they may be overlooking.