A simplified analysis procedure based on 3-D hydroelasticity, which can be used to determine the motions and intermodule forces of a multi-module, very large floating structure (VLFS), is described. While the procedure is applicable to an arbitrary geometric layout of the modules, the modules are considered rigid, and hence all deformations occur in the module connectors. The procedure is used to analyze the response of a 5-module VLFS in both regular and irregular seas. The effect of fluid and structural coupling of the modules on the response is evaluated.
Numerous proposals have been made for very large floating structures (VLFS). Proposed applications range from the visionary floating "city" to the more likely floating airport (Lemke, 1987); military bases (Bretz, 1988; Brahtz, 1989); wave power generators (Katory, 1977); and deep ocean mining platforms (Winkler et aI., 1990). Many of these applications involve floating structures of ascale never before constructed. A floating airport, for example, would likely be several thousand meters long and several hundred meters wide, and it may be in an exposed ocean environment. By contrast, one of the largest floating structures ever constructed is the inland Hood Canal Bridge, which was approximately 2000 m long but only 15 m wide (Hartz, 1981), and the size of conventional floating platforms is on the order of 100 m × 100 m. Although the scale of a VLFS may be an order of magnitude greater than previous floating structures, the basic technology required for their design and construction is available. It is likely that an important class of VLFS will consist of multiple modules, each of which will be a conventional-sized floater. For open-ocean applications for which motions must be restricted, the modules will likely be similar to the large semisubmersibles presently used in the offshore oil industry.