Evaluation of Nonlinear Material Behavior for Offshore Structures Subjected to Accidental Actions

Evaluation of the nonlinear structural response of any structure is a challenging task; a range of input parameters are needed, most of which have significant statistical variability and the evaluations require a high degree of craftsmanship. Hence, high demands are set forth both to the analyst and the body in charge of verification of the results. Recent efforts by DNVGL attempt to mitigate this with the second edition of the DNVGL-RP-C208 for the determination of nonlinear structural response, in which guidance or requirements are given on many of the challenging aspects. This paper discusses the various challenges and the direction to which the RP-C208 points compared to published research. Parameters affecting the plastic hardening, strain-rate effects, and ductile fracture are discussed separately. Then, the combined effect of the range of assumptions is evaluated to assess the resulting level of safety.