System reliability-based assessment on Single Point Mooring jacket platform

The Single Point Mooring (SPM) jacket platforms have been developed over the last several decades and are widely applied in the exploitation of offshore oil-gas resources. The SPM jacket platforms are continuously subjected to environmental loads due to wave, cur-rent, wind and mooring force. As the uncertainty of those loads, the system reliability research of SPM jacket platforms is one of the most important research areas. A methodology of system reliability-based assessment of the SPM jacket platform was introduced in this paper and applied for the assessment of BZ28-1 SPM jacket platform. According to nonlinear mechanical analysis, the mechanics characteristics of SPM jacket platform subjected to extreme loads were analyzed on considering pile-soil-structure nonlinear interaction. Based on the FEM model, with Monte Carlo simulation, the reliability of SPM jacket platform was studied, and the system reliabilities in 20-year-based-period and 50-year-retum-period were calculated respectively. The results show that the statistical analysis of parametric variables based on 50-year return period is appropriate, and the mooring forces due to wave are the predominant loads for SPM jacket platforms. The system reliability-based assessment method can provide important and reliable referential suggestions for the design, maintenance and repair of SPM jacket platforms.