Dependability of Offshore Wind Turbines

In recent years more and more demanding structures are designed, built and operated to satisfy the increasing needs of the Society. This kind of structures can be denoted as complex ones. Among large constructions arrangements, Offshore Wind Turbines (OWT) are definitely complex structural systems, being this complexity related to different aspects such as hard nonlinearities, wide uncertainties and strong interactions, either among the single parts or between the whole structure and the design environment. On the whole, the quality of a complex system is denoted by the idea of dependability, while for a structure the performances are connected to the property of structural integrity, considered as the completeness and consistency of the structural configuration. Even if these concepts have been originally developed, respectively, in computer science and for aerospace applications they can be applied to other high performance systems as OWT. The present paper will show some specific aspects of the modern approach for the design and the analysis of complex structural systems. In the first part of the paper, the general aspects are recalled like the System Engineering approach and the Performance-based Design. Attention is devoted to some important aspects, such as the structure breakdown and the safety and performance allocations. In the second part of the paper, a basic application of the concepts introduced is presented.