Dynamics of Fixed Towers in Deep-Water Random Waves

This paper is concerned with the design of offshore, bottom-supported structures which are subject to deflections and stresses due to deep water wave forces. Both periodic and random waves are considered. It is shown that the wave force on the structure can be adequately expressed by the inertia force component and that this linearization of the wave force expression leads to a criterion for the optimum spacing of structural supports which is a function of the random wave spectrum. Equations for the dynamic response of the platform are developed. The theoretical considerations were verified experimentally and the results indicated that for structures designed with optimum support spacing, the magnitude of structural response is relatively insensitive to wave direction.