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.