Reliability of Offshore Structures – Requirements to and Limitations of Calibrated Deterministic Code Design and Assessment Approaches

Abstract This paper uses a new and validated SRA model based on Monte Carlo simulations to assess the performance of existing design and assessment approaches for offshore structures. Generic structures are designed to meet the ISO 19902 5 code requirements in ULS and ALS limit states at three sites in the Danish North Sea sector. We then run the Monte Carlo time domain simulation to obtain the response statistics and evaluate the annual failure probability for each failure mechanism within each generic model. Looking across the range of failure mechanisms, generic structures, and sites (water depth) the performance of the ISO 19902 design approach can be evaluated. We also use the SRA model and the generic structures to test the accuracy and validity of an existing (Shell 1997) SRA model 6, which outlines a SRA principle widely used for offshore reliability analysis. We will generally refer to this as the old SRA model. We examine each parameter of the model and identify the critical design assumptions and limitations.