A two year research project has been carried out, devoted to the design of SPMs for temporary and permanent tanker mooring in 1000 m water-depth in the Mediterranean Sea. The main component is a very slender and highly compliant vertical column, tensioned at its top by a proper buoyancy chamber. The column is connected down to the base and to the upper buoyancy chamber through tapered steel terminators, thus ensuring full structural continuity and avoiding any critical mechanical ball joint. A small lattice tower placed on top of the buoyancy chamber supports deck and facilities. The structure, designed as mooring/loading system, has natural period within the range of the wave periods so that it behaves in resonance conditions, yet the fatigue strength all along the column is adequate. This has been demonstrated through an extensive non-linear dynamic analysis and fatigue evaluation by spectral approach. A two phase transportation/installation procedure and a telescopic assembling of the column have been proposed in order to accomplish marine operations on structures of reasonable size. Furthermore, for the use of this concept as a permanent mooring, an original gravity yoke has been studied for the connection of the tanker to the top of the column. The paper, after a description of the structure configuration, its performance and proposed marine operations, presents the main results of an extensive dynamic-fatigue analysis. What is considered to be new, in this work, are the proposed simple but original structural concept, the installation procedure and the advanced nonlinear dynamic analysis carried out for a correct evaluation of the response of a compliant structure with several resonance conditions in the range of the wave period. INTRODUCTION The monopile concept was identified in a previous research project developed jointly by Tecnomare and Aker Engineering, where a design for a water depth of 350 m was performed. An extension of this concept to very deep waters is here proposed and discussed. New problems arising from such an extension are mainly inherent to its great length and flexibility. This led to conceive an installation procedure where several individual substructures were eventually connected to each other by means of mechanical connectors. In in-service condition several frequencies were found within the wave frequency range, so that an accurate prediction of motion, stresses and fatigue accounting in resonant condition was necessary. GENERAL DESCRIPTION Configuration The structure of the offshore mooring and loading terminal named Monopile is basically composed of the framed base structure, the very slender and high column, the buoyancy chamber, the upper tower and the head structure. The general arrangement is shown in Fig. 1, while in Table 2 the weight and buoyancy layout for the different parts of the structure is reported.

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