Experimental analysis of wave–structure interaction for very large modular floating structures

Abstract

Very large floating structures represent a relatively new frontier in offshore engineering, offering diverse opportunities for ocean utilization and management. These structures, characterized by their sizable dimensions and relatively low bending stiffness, are often constructed modularly and connected flexibly. Consequently, studying very large modular floating structure (MFS) requires considering both multibody hydrodynamics and connector dynamics. This study experimentally investigates the hydrodynamic behavior of MFS in waves, examining configurations ranging from a single module to three modules, with the measurements of their motions and deformations. Various wavelengths are considered, and the wave-induced loads on the hinge connections between floating modules are also recorded. Results show that attaching additional modules to an existing module decreased surge responses, while heave and pitch responses remained relatively unaffected. Examination of wave-induced deformations reveals that maximum deformations occur when the wavelength approximated the module length, consistent with hogging and sagging phenomena. Notably, the middle module experienced the most pronounced deformations due to constraints from both front and rear modules. Furthermore, the analysis of forces exerted on hinge joints reveals strong nonlinear characteristics. Forces at different harmonic components varied with wavelength, with the contribution from higher harmonics posing a risk of fatigue damage to the connectors. Serving as an experimental benchmark, these results contribute to the development and validation of numerical methods and offer guidance for the structural design of hinged connectors in floating bodies.