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This paper presents a hydroelastic analysis of a pontoon-type Very Large Floating Structure (VLFS) with multiple barriers of varying porosities. The Mindlin plate theory is applied to model the VLFS, while the linear potential wave theory is used to model fluid motions. For interactions between the fluid and impermeable solid surfaces, a boundary condition equating normal fluid and structural velocities is imposed. For fluid interactions with perforated barriers, an empirical model is adopted, where the pressure of fluid passing through the barriers is assumed to drop in a quadratic relationship with the fluid velocity. The mathematical model is solved using an iterative numerical framework based on the finite element method and dual boundary element method. Numerical examples of VLFSs with single and multiple barriers of different porosities are presented. The numerical results indicate that the number and porosity of barrier attachments can be optimized to minimize the hydroelastic responses of the VLFS under specific wave conditions. A combination of a perforated barrier placed in front of an impermeable barrier demonstrates good performance in mitigating the VLFS’s hydroelastic responses, with reasonable horizontal forces on the mooring system as compared to other possible combinations of barrier porosities.

This paper presents a spectral boundary element formulation for analysis of structures subjected to dynamic loading. Two types of spectral elements based on Lobatto polynomials and Legendre polynomials are used. Two-dimensional analyses of elastic wave propagation in solids with and without cracks are carried out in the Laplace frequency domain with both conventional BEM and the spectral BEM. By imposing the requirement of the same level of accuracy, it was found that the use of spectral elements, compared with conventional quadratic elements, reduced the total number of nodes required for modeling high-frequency wave propagation. Benchmark examples included a simple one-dimensional bar for which analytical solution is available and a more complex crack problem where stress intensity factors were evaluated. Special crack tip elements are developed for the first time for the spectral elements to accurately model the crack tip fields. Although more integration points were used for the integrals associated with spectral elements than the conventional quadratic elements, shorter computation times were achieved through the application of the spectral BEM. This indicates that the spectral BEM is a more efficient method for the numerical modeling of structural health monitoring (SHM) processes, in which high-frequency waves are commonly used to detect damage, such as cracks, in structures.