HYDRODYNAMIC-FORCES AND INTERACTIONS OF MULTIPLE CIRCULAR CYLINDRICAL STRUCTURE FLUID SOIL SYSTEMS

This paper presents a mathematical model for the prediction of hydrodynamic forces induced by divergent radiated and scattered waves and the resultant dynamic response of multiple large-scale elastic cylinders. These cylinders are subject to hydrodynamic interference one to another and can also interact with the soil deposit for the case of horizontal sea floor ground motion. The influences due to these aforementioned interactions in the structure-fluid-soil system on the determination of wave loading are described and analyzed separately. The cylinders are assumed to be flexible one-dimensional beams, and the soil is treated as a linear elastic half space The complex frequency response function of the system is derived semi-analytically. The solution procedure can be conveniently extended to a stochastic analysis in the frequency domain of the dynamic response of these types of offshore structures. The conclusions reached indicate that the wave loading on the structures due to interactions is affected distinctly near the water surface and around the excitation frequency of earthquake (and wave frequency) when this is coincident with any of the natural frequencies of the system.