AbstractThis paper presents random vibrations of the Baltic drilling platform subjected to water waves and wind loads. The platform structure is discretized by the finite element method. Linear beam or truss elements can be used. The structure parameters (i.e. mass, damping and stiffness) are assumed as deterministic. Soil is modelled as an elastic half‐space that possesses deterministic or random parameters. Soil–structure interaction is idealized as a system of spring–dashpot elements connecting the structure and subsoil. The parameters of these elements can be random or deterministic. The sea surface is described by the one‐dimensional wave spectrum that was proposed by Striekalov and Massel24for inland seas. It is suitable for the Baltic Sea. The wind velocity is described by the well‐known Davenport spectrum. The water and wind loads are treated as stationary ergodic processes. Gaussian distributions and zero means of these processes are assumed. In addition to this, waves and wind loads are considered as independent. Such an assumption corresponds to the situation when the storm sea is fully developed. A frequency‐domain random‐vibration approach is utilized to obtain the dynamic response of the platform. The equations of motion of the problem were solved using modal reduction. The numerical calculations were made with a specially written computer program. From the results obtained, it is concluded that the wind influence on the response of the platform can be neglected. If random parameters are assumed for the subsoil, then the response of the system describes in a more realistic way the dynamic behaviour of the platform. The velocity coupling due to soil and hydrodynamical damping is negligible. This paper is a condensation of the author's Ph.D. thesis presented at the Technical University of Gdańs
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