A NUMERICALLY EFFICIENT METHOD FOR ANALYSIS OF VERY LARGE ARTICULATEDFLOATING STRUCTURES

A method is presented for evaluation of the motion of long structures composed of interconnected barges, or modules, of arbitrary shape. Suc h structures are being proposed in the construction of offshore airpor ts or other large offshore floating structures. It is known that the e valuation of the motion of jointed or otherwise interconnected modules which make up a long floating structure may be evaluated by three dim ensional radiation/diffraction analysis. However, the computing effort increases rapidly as the complexity of the geometric shape of the ind ividual modules and the total number of modules increases. This paper describes an approximate method which drastically reduces the computat ional effort without major effects on accuracy. The method relies on a ccounting for hydrodynamic interaction effects between only adjacent m odules within the structure rather than between all of the modules sin ce the near-field interaction is by far the more important. This appro ximation reduces the computational effort to that of solving the two-m odule problem regardless of the total number of modules in the complet e structure.