Nonlinear Modelling for Offshore Robustness. A Sensitivity Study.

The assessment of existing offshore steel jacket structures for use beyond their initial life requires a proper design of an inspection plan aimed to constantly check-up the structural elements (both members and joints). There is consequently a need to define a set of indicators that, possibly combined with a continuous dynamic monitoring system, provides a reasonable measure of structural robustness and damage tolerance. To investigate these aspects the paper proposes to develop non-linear static pushover analyses to assess the system reserve strength: damages, or deteriorations, of primary and secondary structural components are assumed to evaluate their effects on the robustness of the structure and to evaluate the possibility to employ a structural monitoring system as a check-up of the integrity of the structural elements.